"uuid","repository link","title","author","contributor","publication year","abstract","subject topic","language","publication type","publisher","isbn","issn","patent","patent status","bibliographic note","access restriction","embargo date","faculty","department","research group","programme","project","coordinates"
"uuid:2a454ba8-3134-417a-83a4-a665772c9a69","http://resolver.tudelft.nl/uuid:2a454ba8-3134-417a-83a4-a665772c9a69","Spatial lipidomics of coronary atherosclerotic plaque development in a familial hypercholesterolemia swine model","Slijkhuis, Nuria (Erasmus MC); Razzi, F. (TU Delft ChemE/Product and Process Engineering; Erasmus MC); Korteland, Suze Anne (Erasmus MC); Heijs, Bram (Leiden University Medical Center); van Gaalen, Kim (Erasmus MC); Duncker, Dirk J. (Erasmus MC); van der Steen, A.F.W. (TU Delft ImPhys/Medical Imaging; TU Delft ImPhys/Verweij group; Erasmus MC; Chinese Academy of Sciences); van Steijn, V. (TU Delft ChemE/Product and Process Engineering); van Beusekom, Heleen M.M. (Erasmus MC); van Soest, G. (TU Delft Biomechanical Engineering; Massachusetts General Hospital; Erasmus MC)","","2024","Coronary atherosclerosis is caused by plaque build-up, with lipids playing a pivotal role in its progression. However, lipid composition and distribution within coronary atherosclerosis remain unknown. This study aims to characterize lipids and investigate differences in lipid composition across disease stages to aid in the understanding of disease progression. Matrix-assisted laser desorption/ionization mass spectrometry imaging (MALDI-MSI) was used to visualize lipid distributions in coronary artery sections (n ¼ 17) from hypercholesterolemic swine. We performed histology on consecutive sections to classify the artery segments and to investigate colocalization between lipids and histological regions of interest in advanced plaque, including necrotic core and inflammatory cells. Segments were classified as healthy (n ¼ 6), mild (n ¼ 6), and advanced disease (n ¼ 5) artery segments. Multivariate data analysis was employed to find differences in lipid composition between the segment types, and the lipids' spatial distribution was investigated using non-negative matrix factorization (NMF). Through this process, MALDI-MSI detected 473 lipid-related features. NMF clustering described three components in positive ionization mode: triacylglycerides (TAG), phosphatidylcholines (PC), and cholesterol species. In negative ionization mode, two components were identified: one driven by phosphatidylinositol(PI)(38:4), and one driven by ceramidephosphoethanolamine(36:1). Multivariate data analysis showed the association between advanced disease and specific lipid signatures like PC(O-40:5) and cholesterylester(CE)(18:2). Ether-linked phospholipids and LysoPC species were found to colocalize with necrotic core, and mostly CE, ceramide, and PI species colocalized with inflammatory cells. This study, therefore, uncovers distinct lipid signatures correlated with plaque development and their colocalization with necrotic core and inflammatory cells, enhancing our understanding of coronary atherosclerosis progression.","Atherosclerosis; dyslipidemias; familial hypercholesterolemia; histology; inflammation; lipids; lipids/chemistry; mass spectrometry imaging; plaque progression; vascular biology","en","journal article","","","","","","","","","","Biomechanical Engineering","ChemE/Product and Process Engineering","","",""
"uuid:c87ae011-bca8-4dca-a055-07003d1c4fd1","http://resolver.tudelft.nl/uuid:c87ae011-bca8-4dca-a055-07003d1c4fd1","Trunk motion influences mechanical power estimates during wheelchair propulsion","van Dijk, M.P. (TU Delft Biomechanical Engineering); Hoozemans, Marco J.M. (Vrije Universiteit Amsterdam); Berger, M.A.M. (The Hague University of Applied Sciences); Veeger, H.E.J. (TU Delft Biomechatronics & Human-Machine Control)","","2024","In wheelchair sports, there is an increasing need to monitor mechanical power in the field. When rolling resistance is known, inertial measurement units (IMUs) can be used to determine mechanical power. However, upper body (i.e., trunk) motion affects the mass distribution between the small front and large rear wheels, thus affecting rolling resistance. Therefore, drag tests – which are commonly used to estimate rolling resistance – may not be valid. The aim of this study was to investigate the influence of trunk motion on mechanical power estimates in hand-rim wheelchair propulsion by comparing instantaneous resistance-based power loss with drag test-based power loss. Experiments were performed with no, moderate and full trunk motion during wheelchair propulsion. During these experiments, power loss was determined based on 1) the instantaneous rolling resistance and 2) based on the rolling resistance determined from drag tests (thus neglecting the effects of trunk motion). Results showed that power loss values of the two methods were similar when no trunk motion was present (mean difference [MD] of 0.6 ± 1.6 %). However, drag test-based power loss was underestimated up to −3.3 ± 2.3 % MD when the extent of trunk motion increased (r = 0.85). To conclude, during wheelchair propulsion with active trunk motion, neglecting the effects of trunk motion leads to an underestimated mechanical power of 1 to 6 % when it is estimated with drag test values. Depending on the required accuracy and the amount of trunk motion in the target group, the influence of trunk motion on power estimates should be corrected for.","Inertial measurement unit; Mechanical power; Rolling resistance force; Wheelchair propulsion; Wheelchair sports","en","journal article","","","","","","","","","","Biomechanical Engineering","Biomechatronics & Human-Machine Control","","",""
"uuid:b9603c2c-ab8c-4120-8913-df209ca6a628","http://resolver.tudelft.nl/uuid:b9603c2c-ab8c-4120-8913-df209ca6a628","Pre-transplant kidney quality evaluation using photoacoustic imaging during normothermic machine perfusion","Nikolaev, Anton V. (Erasmus MC); Fang, Yitian (Erasmus MC); Essers, Jeroen (Erasmus MC); Panth, Kranthi M. (Erasmus MC); Ambagtsheer, Gisela (Erasmus MC); Clahsen-van Groningen, Marian C. (Erasmus MC); Minnee, Robert C. (Erasmus MC); van Soest, G. (TU Delft Biomechanical Engineering; Erasmus MC; Massachusetts General Hospital); de Bruin, Ron W.F. (Erasmus MC)","","2024","Due to the shortage of kidneys donated for transplantation, surgeons are forced to use the organs with an elevated risk of poor function or even failure. Although the existing methods for pre-transplant quality evaluation have been validated over decades in population cohort studies across the world, new methods are needed as long as delayed graft function or failure in a kidney transplant occurs. In this study, we explored the potential of utilizing photoacoustic (PA) imaging during normothermic machine perfusion (NMP) as a means of evaluating kidney quality. We closely monitored twenty-two porcine kidneys using 3D PA imaging during a two-hour NMP session. Based on biochemical analyses of perfusate and produced urine, the kidneys were categorized into ‘non-functional’ and ‘functional’ groups. Our primary focus was to quantify oxygenation (sO2) within the kidney cortical layer of depths 2 mm, 4 mm, and 6 mm using two-wavelength PA imaging. Next, receiver operating characteristic (ROC) analysis was performed to determine an optimal cortical layer depth and time point for the quantification of sO2 to discriminate between functional and non-functional organs. Finally, for each depth, we assessed the correlation between sO2 and creatinine clearance (CrCl), oxygen consumption (VO2), and renal blood flow (RBF). We found that hypoxia of the renal cortex is associated with poor renal function. In addition, the determination of sO2 within the 2 mm depth of the renal cortex after 30 min of NMP effectively distinguishes between functional and non-functional kidneys. The non-functional kidneys can be detected with the sensitivity and specificity of 80% and 85% respectively, using the cut-off point of sO2 < 39%. Oxygenation significantly correlates with RBF and VO2 in all kidneys. In functional kidneys, sO2 correlated with CrCl, which is not the case for non-functional kidneys. We conclude that the presented technique has a high potential for supporting organ selection for kidney transplantation.","Kidney; Normothermic machine perfusion; Oxygen saturation; Oxygenation; Photoacoustics; Pre-transplant kidney quality; Transplantation","en","journal article","","","","","","","","","","Biomechanical Engineering","","","",""
"uuid:ee4cdfe3-53c1-4962-b2c0-cac021779085","http://resolver.tudelft.nl/uuid:ee4cdfe3-53c1-4962-b2c0-cac021779085","The value of collision feedback in robotic surgical skills training","Postema, R.R. (TU Delft Biomechanical Engineering; Amsterdam UMC); Hardon, Hidde (Amsterdam UMC; Vrije Universiteit Amsterdam); Rahimi, A. Masie (Amsterdam UMC; Amsterdam Skills Centre for Health Sciences); Horeman, Roel; Nickel, Felix (University of Heidelberg); Dankelman, J. (TU Delft Medical Instruments & Bio-Inspired Technology); Bloemendaal, A.L.A. (TU Delft Medical Instruments & Bio-Inspired Technology; Reinier de Graaf Gasthuis); van der Elst, M. (TU Delft Medical Instruments & Bio-Inspired Technology; Reinier de Graaf Gasthuis); van der Peet, Donald L. (Amsterdam UMC); Daams, Freek (Amsterdam UMC); Hardon, S.F. (TU Delft Medical Instruments & Bio-Inspired Technology; Amsterdam UMC); Horeman, T. (TU Delft Medical Instruments & Bio-Inspired Technology)","","2024","Collision feedback about instrument and environment interaction is often lacking in robotic surgery training devices. The PoLaRS virtual reality simulator is a newly developed desk trainer that overcomes drawbacks of existing robot trainers for advanced laparoscopy. This study aimed to assess the effect of haptic and visual feedback during training on the performance of a robotic surgical task. Robotic surgery-naïve participants were randomized and equally divided into two training groups: Haptic and Visual Feedback (HVF) and No Haptic and Visual Feedback. Participants performed two basic virtual reality training tasks on the PoLaRS system as a pre- and post-test. The measurement parameters Time, Tip-to-tip distance, Path length Left/Right and Collisions Left/Right were used to analyze the learning curves and statistically compare the pre- and post-tests performances. In total, 198 trials performed by 22 participants were included. The visual and haptic feedback did not negatively influence the time to complete the tasks. Although no improvement in skill was observed between pre- and post-tests, the mean rank of the number of collisions of the right grasper (dominant hand) was significantly lower in the HVF feedback group during the second post-test (Mean Rank = 8.73 versus Mean Rank = 14.27, U = 30.00, p = 0.045). Haptic and visual feedback during the training on the PoLaRS system resulted in fewer instrument collisions. These results warrant the introduction of haptic feedback in subjects with no experience in robotic surgery. The PoLaRS system can be utilized to remotely optimize instrument handling before commencing robotic surgery in the operating room.","Haptic feedback; Patient safety; Robotic surgery; Simulation training; Skills acquisition; Visual feedback","en","journal article","","","","","","","","","","Biomechanical Engineering","Medical Instruments & Bio-Inspired Technology","","",""
"uuid:ac261766-a741-48d5-8db3-018dbd0979fb","http://resolver.tudelft.nl/uuid:ac261766-a741-48d5-8db3-018dbd0979fb","The Simultaneous Model-Based Estimation of Joint, Muscle, and Tendon Stiffness is Highly Sensitive to the Tendon Force-Strain Relationship","Cop, Christopher P. (University of Twente); Jakubowski, Kristen L. (Emory University); Schouten, A.C. (TU Delft Biomechanical Engineering); Koopman, Bart (University of Twente); Perreault, Eric J. (Northwestern University); Sartori, Massimo (University of Twente)","","2024","Objective: Accurate estimation of stiffness across anatomical levels (i.e., joint, muscle, and tendon) in vivo has long been a challenge in biomechanics. Recent advances in electromyography (EMG)-driven musculoskeletal modeling have allowed the non-invasive estimation of stiffness during dynamic joint rotations. Nevertheless, validation has been limited to the joint level due to a lack of simultaneous in vivo experimental measurements of muscle and tendon stiffness. Methods: With a focus on the triceps surae, we employed a novel perturbation-based experimental technique informed by dynamometry and ultrasonography to derive reference stiffness at the joint, muscle, and tendon levels simultaneously. Here, we propose a new EMG-driven model-based approach that does not require external joint perturbation, nor ultrasonography, to estimate multi-level stiffness. We present a novel set of closed-form equations that enables the person-specific tuning of musculoskeletal parameters dictating biological stiffness, including passive force-length relationships in modeled muscles and tendons. Results: Calibrated EMG-driven musculoskeletal models estimated the reference data with average normalized root-mean-square error ≈ 20%. Moreover, only when calibrated tendons were approximately four times more compliant than typically modeled, our approach could estimate multi-level reference stiffness. Conclusion: EMG-driven musculoskeletal models can be calibrated on a larger set of reference data to provide more realistic values for the biomechanical variables across multiple anatomical levels. Moreover, the tendon models that are typically used in musculoskeletal modeling are too stiff. Significance: Calibrated musculoskeletal models informed by experimental measurements give access to an augmented range of biomechanical variables that might not be easily measured with sensors alone.","Biomechanics; Electromyography; Impedance; Joint stiffness; Mathematical models; muscle stiffness; Muscles; musculoskeletal modeling; Perturbation methods; tendon stiffness; Tendons","en","journal article","","","","","","","","","","Biomechanical Engineering","","","",""
"uuid:7d073c83-1da2-47e1-9244-06c7e26129b1","http://resolver.tudelft.nl/uuid:7d073c83-1da2-47e1-9244-06c7e26129b1","Keep the pitcher’s elbow load in the game: Biomechanical analysis of injury mechanisms in baseball pitching towards injury prevention","van Trigt, B. (TU Delft Biomechanical Engineering)","Veeger, H.E.J. (promotor); van der Helm, F.C.T. (promotor); Hoozemans, Marco J.M. (promotor); Delft University of Technology (degree granting institution)","2023","In baseball pitching, high performance is closely related to injuries. The baseball pitch is a rapid, full-body throwing motion that culminates in a ballistic motion of the throwing arm, creating high ball velocity but exposing the elbow to significant loads. As a result, injuries to the medial side of the elbow involving the Ulnar Collateral Ligament (UCL) are currently a major concern in baseball pitchers at all levels of play. UCL injuries are recently prevalent among youth pitchers and injury rates have gradually increased over the years. It is important to prevent injuries in (youth) pitchers, not only to attain healthy pitching performance but also to avoid injuries at older ages. The general aim underlying the present dissertation is to establish biomechanical injury mechanisms related to the Ulnar Collateral Ligament in baseball pitchers. Knowledge of these mechanisms can eventually be used to develop an ‘early warning system’ to safeguard baseball pitchers from UCL injuries. This dissertation is divided into three parts.","","en","doctoral thesis","","978-94-6469-687-5","","","","","","","","Biomechanical Engineering","","","",""
"uuid:1ed0bc44-60d5-42d7-a0f6-769e528c99e6","http://resolver.tudelft.nl/uuid:1ed0bc44-60d5-42d7-a0f6-769e528c99e6","An organ-on-chip device with integrated charge sensors and recording microelectrodes","Aydogmus, H. (TU Delft EKL Processing); Hu, M. (TU Delft Biomechanical Engineering; Leiden University Medical Center); Ivancevic, Lovro; Frimat, Jean Philippe (Leiden University Medical Center); van den Maagdenberg, Arn M.J.M. (Leiden University Medical Center); Sarro, Pasqualina M (TU Delft Electronic Components, Technology and Materials); Mastrangeli, Massimo (TU Delft Electronic Components, Technology and Materials)","","2023","Continuous monitoring of tissue microphysiology is a key enabling feature of the organ-on-chip (OoC) approach for in vitro drug screening and disease modeling. Integrated sensing units are particularly convenient for microenvironmental monitoring. However, sensitive in vitro and real-time measurements are challenging due to the inherently small size of OoC devices, the characteristics of commonly used materials, and external hardware setups required to support the sensing units. Here we propose a silicon-polymer hybrid OoC device that encompasses transparency and biocompatibility of polymers at the sensing area, and has the inherently superior electrical characteristics and ability to house active electronics of silicon. This multi-modal device includes two sensing units. The first unit consists of a floating-gate field-effect transistor (FG-FET), which is used to monitor changes in pH in the sensing area. The threshold voltage of the FG-FET is regulated by a capacitively-coupled gate and by the changes in charge concentration in close proximity to the extension of the floating gate, which functions as the sensing electrode. The second unit uses the extension of the FG as microelectrode, in order to monitor the action potential of electrically active cells. The layout of the chip and its packaging are compatible with multi-electrode array measurement setups, which are commonly used in electrophysiology labs. The multi-functional sensing is demonstrated by monitoring the growth of induced pluripotent stem cell-derived cortical neurons. Our multi-modal sensor is a milestone in combined monitoring of different, physiologically-relevant parameters on the same device for future OoC platforms.","","en","journal article","","","","","","","","","","Biomechanical Engineering","EKL Processing","","",""
"uuid:1f610c78-6000-42c7-9319-264a3e2e41b7","http://resolver.tudelft.nl/uuid:1f610c78-6000-42c7-9319-264a3e2e41b7","Sex differences in characteristics of atrial fibrillation recurrence post surgical pulmonary vein isolation","Veen, Danny (Erasmus MC; Onze Lieve Vrouwe Gasthuis); Verbeek, Eva C. (Onze Lieve Vrouwe Gasthuis); Kavousi, Maryam (Erasmus MC); Huigen, Jos (Onze Lieve Vrouwe Gasthuis); Mijnen-Schra, Annet (Onze Lieve Vrouwe Gasthuis); Cocchieri, Riccardo (Onze Lieve Vrouwe Gasthuis); Khan, Muchtiar (Onze Lieve Vrouwe Gasthuis); de Groot, N.M.S. (TU Delft Biomechanical Engineering; TU Delft Signal Processing Systems; Erasmus MC)","","2023","Background: Prior studies demonstrated that female sex is associated with arrhythmia recurrence after endovascular pulmonary vein isolation (PVI). However, it is unknown if the sexes differ in outcome after video assisted thoracoscopic (VATS) PVI. The aim of this study was therefore to compare characteristics of recurrent AF episodes in a matched male and female population, using implantable loop recorders for continuous rhythm monitoring. Methods: 40 matched (based on propensity score) males (age: 60.0 ± 7.71 (45–75)) and females (age: 62.0 ± 7.0 (37–74)) were retrieved from an existing database from a prior conducted study by the cardiothoracic department of the OLVG hospital (1) containing patients who received an implantable looprecorder and underwent a VATS PVI between 2012 and 2017. Patients were continuously monitored for a period of 12 months after VATS PVI and AF characteristics were compared. Results: An equal number of males and females had AF episodes during all periods (P > 0.05). The number of AF episodes was higher in females, during the first 6 months (P = 0.01, P = 0.034). During the entire follow up, the total AF duration was longer in females (P = 0.01, for all periods) with shorter inter - episode intervals (P = 0.001, P = 0001, P = 0.04) and a higher AF burden (P = 0.003, P = 0001, P = 0.006). After 3 months, AF recurrences during the night were more frequently observed in female patients (P = 0.001, P = 0.001). Conclusions: AF episodes occur frequently in both sexes after VATS PVI and warrant frequent rhythm monitoring. The observed sex differences in AF burden after VATS PVI, calls for intensive rhythm monitoring and aggressive treatment of recurrent AF epsiodes in females.","AF recurrences; Atrial fibrillation; Sex differences; VATS PVI","en","journal article","","","","","","Publisher Copyright: © 2023 The Authors","","","","Biomechanical Engineering","Signal Processing Systems","","",""
"uuid:0587da55-4476-41d6-8564-f7fb11171679","http://resolver.tudelft.nl/uuid:0587da55-4476-41d6-8564-f7fb11171679","Spectroscopic optical coherence tomography at 1200 nm for lipid detection","Kuttippurath, Vivek (Erasmus MC); Slijkhuis, Nuria (Erasmus MC); Liu, Shengnan (Erasmus MC); van Soest, G. (TU Delft Biomechanical Engineering)","","2023","Significance: Spectroscopic analysis of optical coherence tomography (OCT) data can yield added information about the sample's chemical composition, along with high-resolution images. Typical commercial OCT systems operate at wavelengths that may not be optimal for identifying lipid-containing samples based on absorption features. Aim: The main aim of this study was to develop a 1200 nm spectroscopic OCT (SOCT) for the classification of lipid-based and water-based samples by extracting the lipid absorption peak at 1210 nm from the OCT data. Approach: We developed a 1200 nm OCT system and implemented a signal processing algorithm that simultaneously retrieves spectroscopic and structural information from the sample. In this study, we validated the performance of our OCT system by imaging weakly scattering phantoms with and without lipid absorption features. An orthogonal projections to latent structures-discriminant analysis (OPLS-DA) model was developed and applied to classify weakly scattering samples based on their absorption features. Results: The OCT system achieved an axial resolution of 7.2 m and a sensitivity of 95 dB. The calibrated OPLS-DA model on weakly scattering samples with lipid and water-based absorption features correctly classified 19/20 validation samples. Conclusions: The 1200 nm SOCT system can discriminate the lipid-containing weakly scattering samples from water-based weakly scattering samples with good predictive ability.","biomedical imaging; lipid-rich plaques; optical coherence tomography; spectroscopic optical coherence tomography","en","journal article","","","","","","","","","","Biomechanical Engineering","","","",""
"uuid:8bcb339f-3f76-4d19-8644-1bbb7f5023bc","http://resolver.tudelft.nl/uuid:8bcb339f-3f76-4d19-8644-1bbb7f5023bc","Ankle-Foot-Orthosis “Hermes” Compensates Pathological Ankle Stiffness of Chronic Stroke—A Proof of Concept","Rodriguez Hernandez, K.E. (TU Delft Biomechatronics & Human-Machine Control); de Groot, J.H. (Leiden University Medical Center); Baas, Frank (InteSpring BV); Stijntjes, M. (TU Delft Support Biomechanical Engineering; Leiden University Medical Center); Grootendorst, E.R.M. (TU Delft Biomechatronics & Human-Machine Control; Leiden University Medical Center); Schiemanck, S.K. (TU Delft Biomechanical Engineering; Leiden University Medical Center); van der Helm, F.C.T. (TU Delft Biomechatronics & Human-Machine Control); van der Kooij, H. (TU Delft Support Biomechanical Engineering; University of Twente); Mugge, W. (TU Delft Biomechatronics & Human-Machine Control)","","2023","Individuals with an upper motor neuron syndrome, e.g., stroke survivors, may have a pathological increase of passive ankle stiffness due to spasticity, that impairs ankle function and activities such as walking. To improve mobility, walking aids such as ankle-foot orthoses and orthopaedic shoes are prescribed. However, these walking aids generally limit the range of motion (ROM) of the foot and may therewith negatively influence activities that require a larger ROM. Here we present a new ankle-foot orthosis 'Hermes', and its first experimental results from four hemiparetic chronic stroke patients. Hermes was designed to facilitate active ankle dorsiflexion by mechanically compensating the passive ankle stiffness using a negative-stiffness mechanism. Four levels of the Hermes' stiffness compensation (0%, 35%, 70% and 100%) were applied to evaluate active ROM in a robotic ankle manipulator and to test walking feasibility on an instrumented treadmill, in a single session. The robotic tests showed that Hermes successfully compensated the ankle joint stiffness in all four patients and improved the active dorsiflexion ROM in three patients. Three patients were able to walk with Hermes at one or more Hermes' stiffness compensation levels and without reducing their preferred walking speeds compared to those with their own walking aids. Despite a small sample size, the results show that Hermes holds great promise to support voluntary ankle function and to benefit walking and daily activities.","equinus deformity; Footwear; joint range of motion; Legged locomotion; Manipulators; Motion control; muscle spasticity; orthotic devices; Read only memory; stroke; Torque; Torque measurement","en","journal article","","","","","","","","","","Biomechanical Engineering","Biomechatronics & Human-Machine Control","","",""
"uuid:38dd500a-7e71-4ae1-9b38-3d8c756c2637","http://resolver.tudelft.nl/uuid:38dd500a-7e71-4ae1-9b38-3d8c756c2637","The future of artificial intelligence in intensive care: moving from predictive to actionable AI","Smit, J.M. (TU Delft Pattern Recognition and Bioinformatics; Erasmus MC); Krijthe, J.H. (TU Delft Pattern Recognition and Bioinformatics); van Bommel, Jasper (Erasmus MC); van Genderen, M. E.; Labrecque, J. A.; Komorowski, M.; Gommers, D.A.M.P.J. (TU Delft Biomechanical Engineering); Reinders, M.J.T. (TU Delft Pattern Recognition and Bioinformatics)","","2023","Artificial intelligence (AI) research in the intensive care unit (ICU) mainly focuses on developing models (from linear regression to deep learning) to predict out-
comes, such as mortality or sepsis [1, 2]. However, there is another important aspect of AI that is typically not framed as AI (although it may be more worthy of the name), which is the prediction of patient outcomes or events that would result from different actions, known as causal inference [3, 4]. This aspect of AI is crucial for decision-making in the ICU. To emphasize the impor- tance of causal inference, we propose to refer to any data- driven model used for causal inference tasks as ‘action- able AI’, as opposed to ‘predictive AI’, and discuss how these models could provide meaningful decision support in the ICU.","","en","journal article","","","","","","","","","","Biomechanical Engineering","Pattern Recognition and Bioinformatics","","",""
"uuid:6a0ed4b8-8b19-4078-b678-3345956b33d5","http://resolver.tudelft.nl/uuid:6a0ed4b8-8b19-4078-b678-3345956b33d5","Pre-clinical evaluation of the new veress needle+ mechanism on thiel-embalmed bodies: a controlled crossover study - Experimental research","Postema, R.R. (TU Delft Biomechanical Engineering; Amsterdam UMC); Hardon, S.F. (TU Delft Medical Instruments & Bio-Inspired Technology; Amsterdam UMC); Cefai, David (ProVinci Medtech); Dankelman, J. (TU Delft Medical Instruments & Bio-Inspired Technology); Jansen, F.W. (Leiden University Medical Center); Camenzuli, Christian (University of Malta); Calleja-Agius, Jean (University of Malta); Horeman, T. (TU Delft Medical Instruments & Bio-Inspired Technology)","","2023","Background:
Veress needles (VN) are commonly used in establishing pneumoperitoneum in laparoscopic surgery. Previously, a VN with a new safety mechanism ‘VeressPLUS’ needle (VN+) was developed to reduce the amount of overshoot.
Methods:
Eighteen participants (novices, intermediates, and experts) performed in total of 248 insertions in a systematic way on Thiel-embalmed bodies with wide and small bore versions of the conventional VN (VNc) and the VN+. Insertion depth was measured by recording the graduations on the needle under direct laparoscopic vision.
Results:
Participants graded the bodies and the procedures as lifelike. Overall, a significant reduction (P<0.001) in average insertion depth was found for the VN+ compared to the VNc of 26.0 SD16 mm versus 46.2 SD15 mm. The insertion depth difference in the novice group was higher compared to the intermediates and experts (P<0.001). The average insertion depth for both needle types was less (P<0.001) for female participants compared to male.
Conclusion:
This study indicated that the VN+ significantly reduced the insertion depth in all tested conditions. Whether the difference between female and male performance can be linked to differences in muscle control or arm mass should be further investigated. Useful technical information was gathered from this study to further improve the VN+.
Methods: A cohort of community dwelling young (mean = 23.6 years, N = 20) and older adults (mean = 70.1 years, N = 20) participated in this balance learning study. Participants stood on a robotic balance simulator which was used to artificially impose a 250 ms delay into their control of standing. Young and older adults practiced to balance with the imposed delay either with or without visual feedback (i.e., eyes open or closed), resulting in four training groups. We assessed their balance behavior and performance (i.e., variability in postural sway and ability to maintain upright posture) before, during and after training. We further evaluated whether training benefits gained in one visual condition transferred to the untrained condition.
Results: All participants, regardless of age or visual training condition, improved their balance performance through training to stand with the imposed delay. Compared to young adults, however, older adults had larger postural oscillations at all stages of the experiments, exhibited less relative learning to balance with the delay and had slower rates of balance improvement. Visual feedback was not required to learn to stand with the imposed delay, but it had a modest effect on the amount of time participants could remain upright. For all groups, balance improvements gained from training in one visual condition transferred to the untrained visual condition.
Conclusion: Our study reveals that while advanced age partially impairs balance learning, the older nervous system maintains the ability to recalibrate motor control to stand with initially destabilizing sensorimotor delays under differing visual feedback conditions.","sensorimotor learning; aging; sensorimotor delay; standing balance; posture; visual feedback; generalization of learning","en","journal article","","","","","","","","","","Biomechanical Engineering","Biomechatronics & Human-Machine Control","","",""
"uuid:53e8ba52-452a-4951-b3f3-c284f105dff0","http://resolver.tudelft.nl/uuid:53e8ba52-452a-4951-b3f3-c284f105dff0","DAIS: The Delft Database of EEG Recordings of Dutch Articulated and Imagined Speech","Dekker, Bo (Student TU Delft); Schouten, A.C. (TU Delft Biomechanical Engineering); Scharenborg, O.E. (TU Delft Multimedia Computing)","","2023","Silent speech interfaces could enable people who lost the ability to use their voice or gestures to communicate with the external world, e.g., through decoding the person’s brain signals when imagining speech. Only a few and small databases exist that allow for the development and training of brain computer interfaces (BCIs) that can decode imagined speech from recorded brain signals. Here, we present an open database consisting of electroencephalography (EEG) and speech data from 20 participants recorded during the covert (imagined) and actual articulation of 15 Dutch prompts. A validation speaker-independent classification experiment using a ResNet-50 model with spatial-spectral-temporal features extracted from the EEG signals obtained an average accuracy of 70.6% for the classification of rest vs. covert vs. articulated speech trials. This and observed structural differences in the EEG signals between covert and articulated speech demonstrate that the EEG signals in the three classes contain discriminative information.","Brain computer interfaces; covert (imagined) speech; , electroencephalography (EEG); ResNet","en","conference paper","IEEE","","","","","Green Open Access added to TU Delft Institutional Repository 'You share, we take care!' - Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.","","2023-11-05","","Biomechanical Engineering","Multimedia Computing","","",""
"uuid:a45a1aa5-3877-4265-af34-623425eaad8f","http://resolver.tudelft.nl/uuid:a45a1aa5-3877-4265-af34-623425eaad8f","Deep reinforcement learning for cerebral anterior vessel tree extraction from 3D CTA images","Su, Jiahang (Erasmus MC); Li, Shuai (Erasmus MC); Wolff, Lennard (Erasmus MC); van Zwam, Wim (Maastricht UMC); Niessen, W.J. (TU Delft ImPhys/Vos group; TU Delft ImPhys/Computational Imaging; Erasmus MC); van der Lugt, Aad (Erasmus MC); van Walsum, T. (TU Delft Biomechanical Engineering; Erasmus MC)","","2023","Extracting the cerebral anterior vessel tree of patients with an intracranial large vessel occlusion (LVO) is relevant to investigate potential biomarkers that can contribute to treatment decision making. The purpose of our work is to develop a method that can achieve this from routinely acquired computed tomography angiography (CTA) and computed tomography perfusion (CTP) images. To this end, we regard the anterior vessel tree as a set of bifurcations and connected centerlines. The method consists of a proximal policy optimization (PPO) based deep reinforcement learning (DRL) approach for tracking centerlines, a convolutional neural network based bifurcation detector, and a breadth-first vessel tree construction approach taking the tracking and bifurcation detection results as input. We experimentally determine the added values of various components of the tracker. Both DRL vessel tracking and CNN bifurcation detection were assessed in a cross validation experiment using 115 subjects. The anterior vessel tree formation was evaluated on an independent test set of 25 subjects, and compared to interobserver variation on a small subset of images. The DRL tracking result achieves a median overlapping rate until the first error (1.8 mm off the reference standard) of 100, [46, 100] % on 8032 vessels over 115 subjects. The bifurcation detector reaches an average recall and precision of 76% and 87% respectively during the vessel tree formation process. The final vessel tree formation achieves a median recall of 68% and precision of 70%, which is in line with the interobserver agreement.","3D CTA; Bifurcation detection; Brain vessel; CNN; Deep reinforcement learning; Tracking","en","journal article","","","","","","","","","","Biomechanical Engineering","ImPhys/Vos group","","",""
"uuid:c01a254e-d5cd-4a04-8b21-49ea4a2bcbfa","http://resolver.tudelft.nl/uuid:c01a254e-d5cd-4a04-8b21-49ea4a2bcbfa","Examining the role of intrinsic and reflexive contributions to ankle joint hyper-resistance treated with botulinum toxin-A","van’t Veld, Ronald C. (University of Twente); Flux, Eline (Vrije Universiteit Amsterdam); van Oorschot, Wieneke (Sint Maartenskliniek, Nijmegen); Schouten, A.C. (TU Delft Biomechanical Engineering; University of Twente); van der Krogt, Marjolein M. (Vrije Universiteit Amsterdam); van der Kooij, H. (TU Delft Support Biomechanical Engineering; University of Twente); Vos-van der Hulst, Marije (Sint Maartenskliniek, Nijmegen); Keijsers, Noël L.W. (Radboud University Medical Center; Sint Maartenskliniek, Nijmegen); van Asseldonk, Edwin H.F. (University of Twente)","","2023","Background: Spasticity, i.e. stretch hyperreflexia, increases joint resistance similar to symptoms like hypertonia and contractures. Botulinum neurotoxin-A (BoNT-A) injections are a widely used intervention to reduce spasticity. BoNT-A effects on spasticity are poorly understood, because clinical measures, e.g. modified Ashworth scale (MAS), cannot differentiate between the symptoms affecting joint resistance. This paper distinguishes the contributions of the reflexive and intrinsic pathways to ankle joint hyper-resistance for participants treated with BoNT-A injections. We hypothesized that the overall joint resistance and reflexive contribution decrease 6 weeks after injection, while returning close to baseline after 12 weeks. Methods: Nine participants with spasticity after spinal cord injury or after stroke were evaluated across three sessions: 0, 6 and 12 weeks after BoNT-A injection in the calf muscles. Evaluation included clinical measures (MAS, Tardieu Scale) and motorized instrumented assessment using the instrumented spasticity test (SPAT) and parallel-cascade (PC) system identification. Assessments included measures for: (1) overall resistance from MAS and fast velocity SPAT; (2) reflexive resistance contribution from Tardieu Scale, difference between fast and slow velocity SPAT and PC reflexive gain; and (3) intrinsic resistance contribution from slow velocity SPAT and PC intrinsic stiffness/damping. Results: Individually, the hypothesized BoNT-A effect, the combination of a reduced resistance (week 6) and return towards baseline (week 12), was observed in the MAS (5 participants), fast velocity SPAT (2 participants), Tardieu Scale (2 participants), SPAT (1 participant) and reflexive gain (4 participants). On group-level, the hypothesis was only confirmed for the MAS, which showed a significant resistance reduction at week 6. All instrumented measures were strongly correlated when quantifying the same resistance contribution. Conclusion: At group-level, the expected joint resistance reduction due to BoNT-A injections was only observed in the MAS (overall resistance). This observed reduction could not be attributed to an unambiguous group-level reduction of the reflexive resistance contribution, as no instrumented measure confirmed the hypothesis. Validity of the instrumented measures was supported through a strong association between different assessment methods. Therefore, further quantification of the individual contributions to joint resistance changes using instrumented measures across a large sample size are essential to understand the heterogeneous response to BoNT-A injections.","BoNT-A injections; Instrumented SPAT; Joint resistance; Spasticity; System identification","en","journal article","","","","","","","","","","Biomechanical Engineering","Support Biomechanical Engineering","","",""
"uuid:698d224d-9259-4796-b52d-83a187a4c251","http://resolver.tudelft.nl/uuid:698d224d-9259-4796-b52d-83a187a4c251","Real-Life Wheelchair Mobility Metrics from IMUs","de Vries, W.H.K. (Swiss Paraplegic Research); van der Slikke, R.M.A. (TU Delft Biomechatronics & Human-Machine Control; The Hague University of Applied Sciences); van Dijk, M.P. (TU Delft Biomechanical Engineering); Arnet, Ursina (Swiss Paraplegic Research)","","2023","Daily wheelchair ambulation is seen as a risk factor for shoulder problems, which are prevalent in manual wheelchair users. To examine the long-term effect of shoulder load from daily wheelchair ambulation on shoulder problems, quantification is required in real-life settings. In this study, we describe and validate a comprehensive and unobtrusive methodology to derive clinically relevant wheelchair mobility metrics (WCMMs) from inertial measurement systems (IMUs) placed on the wheelchair frame and wheel in real-life settings. The set of WCMMs includes distance covered by the wheelchair, linear velocity of the wheelchair, number and duration of pushes, number and magnitude of turns and inclination of the wheelchair when on a slope. Data are collected from ten able-bodied participants, trained in wheelchair-related activities, who followed a 40 min course over the campus. The IMU-derived WCMMs are validated against accepted reference methods such as Smartwheel and video analysis. Intraclass correlation (ICC) is applied to test the reliability of the IMU method. IMU-derived push duration appeared to be less comparable with Smartwheel estimates, as it measures the effect of all energy applied to the wheelchair (including thorax and upper extremity movements), whereas the Smartwheel only measures forces and torques applied by the hand at the rim. All other WCMMs can be reliably estimated from real-life IMU data, with small errors and high ICCs, which opens the way to further examine real-life behavior in wheelchair ambulation with respect to shoulder loading. Moreover, WCMMs can be applied to other applications, including health tracking for individual interest or in therapy settings.","IMU; wearable sensors; spinal cord injury; activities of daily living; wheelchair propulsion; shoulder","en","journal article","","","","","","","","","","Biomechanical Engineering","Biomechatronics & Human-Machine Control","","",""
"uuid:53710c2d-2342-44e5-b9bd-aea9985a3451","http://resolver.tudelft.nl/uuid:53710c2d-2342-44e5-b9bd-aea9985a3451","EASIER: A new model for online learning of minimally invasive surgery skills","Oropesa, Ignacio (Universidad Politécnica de Madrid); Sánchez-Peralta, Luisa F. (Jesús Usón Minimally Invasive Surgery Centre); Chmarra, M.K. (TU Delft Biomechanical Engineering; TU Delft Medical Instruments & Bio-Inspired Technology); Berner-Juhos, Krisztina (Semmelweis University); Tiu, Calin (MEDIS Foundation); Mettouris, Christos (University of Cyprus); Blas Pagador, José (Jesús Usón Minimally Invasive Surgery Centre); Post, Joeri (SIMENDO BV); Dankelman, J. (TU Delft Medical Instruments & Bio-Inspired Technology)","","2023","Introduction: Technology Enhanced Learning (TEL) can provide the tools to safely master minimally invasive surgery (MIS) skills in patient-free environments and receive immediate objective feedback without the constant presence of an instructor. However, TEL-based systems tend to work isolated from one another, focus on different skills, and fail to provide contents without a sound pedagogical background. Objective: The objective of this descriptive study is to present in detail EASIER, an innovative TEL platform for surgical and interventional training, as well as the results of its validation. Methods: EASIER provides a Learning Management System (LMS) for institutions and content creators that can connect and integrate TEL “external assets” (virtual reality simulators, augmented box trainers, augmented videos, etc.) addressing different skills. The platform integrates all skills under an Assessment Module that measures skills’ progress in different courses. Finally, it provides content creators with a pedagogical model to scaffold contents while retaining flexibility to approach course design with different training philosophies in mind. Three courses were developed and hosted in the platform to validate it with end-users in terms of usability, performance, learning results in the courses and student self-perception on learning. Results: In total 111 volunteers completed the validation. The study was limited due to the COVID-19 pandemic, which limited access to external assets (virtual reality simulators). Nevertheless, usability was rated with 73.1 in the System Usability Scale. Most positive aspects on performance were easiness to access the platform, easiness to change the configuration and not requiring additional plug-ins to use the platform. The platform was rated above average in the six scales of the User Experience Questionnaire. Overall, student results improved significantly across the three courses (p < 0.05). Conclusions: This study provides, within its limitations, evidence on the usefulness of the EASIER platform for distance learning of MIS skills. Results show the potential impact of the platform and are an encouraging boost for the future, especially in the aftermath of the COVID-19 pandemic.","Computer simulation; Distance; Education; Information and Communication Technologies Projects; Medical Education; Surgery; Training Simulation","en","journal article","","","","","","Green Open Access added to TU Delft Institutional Repository 'You share, we take care!' - Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.","","2024-04-21","","Biomechanical Engineering","Medical Instruments & Bio-Inspired Technology","","",""
"uuid:b88cbd13-efc7-4ad6-9f81-4201c2f4abdd","http://resolver.tudelft.nl/uuid:b88cbd13-efc7-4ad6-9f81-4201c2f4abdd","Magnitude and variability of individual elbow load in repetitive baseball pitching","van Trigt, B. (TU Delft Biomechanical Engineering); van Hogerwou, Thomas (Student TU Delft); Leenen, A.J.R. (Vrije Universiteit Amsterdam); Hoozemans, Marco J.M. (Vrije Universiteit Amsterdam); van der Helm, F.C.T. (TU Delft Biomechatronics & Human-Machine Control); Veeger, H.E.J. (TU Delft Biomechatronics & Human-Machine Control)","","2023","In baseball pitchers the elbow is exposed to high and repetitive loads (i.e. external valgus torque), caused by pitching a high number of balls in a practice session or game. This can result in overuse injuries like the ulnar collateral ligament (UCL) injury. To understand injury mechanisms, the effect of repetitive pitching on the elbow load magnitude and variability was investigated. In addition, we explored whether repetitive pitching affects elbow muscle activation during pitching. Fifteen pitchers threw each 60 to 110 balls. The external valgus torque and electromyography of three elbow muscles were quantified during each pitch. Linear mixed model analyses were performed to investigate the effect of repetitive pitching. On a group level, the linear mixed models showed no significant associations of repetitive pitching with valgus torque magnitude and variability and elbow muscle activity. Significant differences exist between pitchers in their individual trajectories in elbow valgus torque and muscle activity with repetitive pitching. This shows the importance of individuality in relation to repetitive pitching. In order to achieve effective elbow injury prevention in baseball pitching, individual characteristics of changes in elbow load and muscle activity in relation to the development of UCL injuries should be investigated.","","en","journal article","","","","","","","","","","Biomechanical Engineering","Biomechatronics & Human-Machine Control","","",""
"uuid:d8b295c8-c14e-4406-b604-fb595cba8358","http://resolver.tudelft.nl/uuid:d8b295c8-c14e-4406-b604-fb595cba8358","The relevance of reducing Veress needle overshooting","Horeman, T. (TU Delft Medical Instruments & Bio-Inspired Technology; European Association of Endoscopic Surgery (EAES)); Postema, R.R. (TU Delft Biomechanical Engineering; Amsterdam UMC); Fischer, T. (Student TU Delft); Calleja-Agius, J. (University of Malta); Camenzuli, C. (University of Malta); Alvino, L. (Nyenrode Business Universiteit); Hardon, S.F. (TU Delft Medical Instruments & Bio-Inspired Technology; Amsterdam UMC); Bonjer, H. J. (Amsterdam UMC; European Association of Endoscopic Surgery (EAES))","","2023","Safe insertion of the Veress needle during laparoscopy relies on the surgeons’ technical skills in order to stop needle insertion just in time to prevent overshooting in the underlying organs. To reduce this risk, a wide variety of Veress needle systems were developed with safety mechanisms that limit the insertion speed, insertion depth or decouple the driving force generated by the surgeon’s hand on the needle. The aim of this study is to evaluate current surgeons’ perceptions related to the use of Veress needles and to investigate the relevance of preventing overshooting of Veress needles among members of the European Association of Endoscopic Surgery (EAES). An online survey was distributed by the EAES Executive Office to all active members. The survey consisted of demographic data and 14 questions regarding the use of the Veress needle, the training conducted prior to usage, and the need for any improvement. A total of 365 members residing in 58 different countries responded the survey. Of the responding surgeons, 36% prefer the open method for patients with normal body mass index (BMI), and 22% for patients with high BMI. Of the surgeons using Veress needle, 68% indicated that the reduction of overshoot is beneficial in normal BMI patients, whereas 78% indicated that this is beneficial in high BMI patients. On average, the members using the Veress needle had used it for 1448 (SD 3031) times and felt comfortable on using it after 22,9 (SD 78,9) times. The average years of experience was 17,6 (SD 11,1) and the surgeons think that a maximum overshoot of 9.4 (SD 5.5) mm is acceptable before they can safely use the Veress needle. This survey indicates that despite the risks, Veress needles are still being used by the majority of the laparoscopic surgeons who responded. In addition, the surgeons responded that they were interested in using a Veress needle with an extra safety mechanism if it limits the risk of overshooting into the underlying structures.","OA-Fund TU Delft","en","journal article","","","","","","","","","","Biomechanical Engineering","Medical Instruments & Bio-Inspired Technology","","",""
"uuid:0acc81b0-244c-4707-a223-90caba885063","http://resolver.tudelft.nl/uuid:0acc81b0-244c-4707-a223-90caba885063","Mild Stroke, Serious Problems: Limitations in Balance and Gait Capacity and the Impact on Fall Rate, and Physical Activity","Roelofs, Jolanda M.B. (Radboud University Medical Center); Zandvliet, Sarah B. (Radboud University Medical Center); Schut, I.M. (TU Delft Biomechatronics & Human-Machine Control); Huisinga, Anouk C.M. (Rehabilitation Centre Klimmendaal); Schouten, A.C. (TU Delft Biomechanical Engineering; University of Twente); Hendricks, Henk T. (Rijnstate Hospital); de Kam, Digna (Radboud University Medical Center); Aerden, Leo A.M. (Reinier de Graaf Gasthuis); Bussmann, J.B.J. (Erasmus MC); Geurts, Alexander C.H. (Radboud University Medical Center; Sint Maartenskliniek, Nijmegen); Weerdesteyn, Vivian (Radboud University Medical Center; Sint Maartenskliniek, Nijmegen)","","2023","Background: After mild stroke persistent balance limitations may occur, creating a risk factor for fear of falling, falls, and reduced activity levels. Objective. To investigate whether individuals in the chronic phase after mild stroke show balance and gait limitations, elevated fall risk, reduced balance confidence, and physical activity levels compared to healthy controls. Methods: An observational case-control study was performed. Main outcomes included the Mini-Balance Evaluation Systems Test (mini-BEST), Timed Up and Go (TUG), 10-m Walking Test (10-MWT), and 6-item version Activity-specific Balance Confidence (6-ABC) scale which were measured in 1 session. Objectively measured daily physical activity was measured for 7 consecutive days. Fall rate in daily life was recorded for 12 months. Individuals after a mild stroke were considered eligible when they: (1) sustained a transient ischemic attack or stroke longer than 6 months ago, resulting in motor and/or sensory loss in the contralesional leg at the time of stroke, (2) showed (near-) complete motor function, that is, ≥24 points on the Fugl-Meyer Assessment—Lower Extremity (range: 0-28). Results: Forty-seven healthy controls and 70 participants after mild stroke were included. Participants with stroke fell more than twice as often as healthy controls, had a 2 point lower median score on the mini-BEST, were 1.7 second slower on TUG, 0.6 km/h slower on the 10-MWT, and had a 12% lower 6-ABC score. Intensity for both total activity (8%) as well as walking activity (6%) was lower in the participants with stroke, while no differences were found in terms of duration. Conclusions: Individuals in the chronic phase after a mild stroke demonstrate persistent balance limitations and have an increased fall risk. Our results point at an unmet clinical need in this population.","accidental falls; gait; postural balance; stroke; stroke rehabilitation; transient ischemic attack","en","journal article","","","","","","","","","","Biomechanical Engineering","Biomechatronics & Human-Machine Control","","",""
"uuid:88108b16-24b2-42f3-9bdc-be5cbfc4aaff","http://resolver.tudelft.nl/uuid:88108b16-24b2-42f3-9bdc-be5cbfc4aaff","Identifying lipid traces of atherogenic mechanisms in human carotid plaque","Slijkhuis, Nuria (Erasmus MC); Mirzaian, Mina (Erasmus MC); Korteland, Suze Anne (Erasmus MC); Heijs, Bram (Leiden University Medical Center); van Gaalen, Kim (Erasmus MC); Nieuwenhuizen, Ingeborg (Erasmus MC); van der Heiden, Kim (Erasmus MC); Claude, Emmanuelle (Waters Corporation); van Soest, G. (TU Delft Biomechanical Engineering; Erasmus MC)","","2023","Background and aims: Lipids play an important role in atherosclerotic plaque development and are interesting candidate predictive biomarkers. However, the link between circulating lipids, accumulating lipids in the vessel wall, and plaque destabilization processes in humans remains largely unknown. This study aims to provide new insights into the role of lipids in atherosclerosis using lipidomics and mass spectrometry imaging to investigate lipid signatures in advanced human carotid plaque and plasma samples. Methods: We used lipidomics and desorption electrospray ionization mass spectrometry imaging (DESI-MSI) to investigate lipid signatures of advanced human carotid plaque and plasma obtained from patients who underwent carotid endarterectomy (n = 14 out of 17 whose plaque samples were analyzed by DESI-MSI). Multivariate data analysis and unsupervised clustering were applied to identify lipids that were the most discriminative species between different patterns in plaque and plasma. These patterns were interpreted by quantitative comparison with conventional histology. Results: Lipidomics detected more than 300 lipid species in plasma and plaque, with markedly different relative abundances. DESI-MSI visualized the spatial distribution of 611 lipid-related m/z features in plaques, of which 330 m/z features could be assigned based on exact mass, comparison to the lipidomic data, and high mass resolution MSI. Matching spatial lipid patterns to histological areas of interest revealed several molecular species that were colocalized with pertinent disease processes in plaque including specific sphingomyelin and ceramide species with calcification, phospholipids and free fatty acids with inflammation, and triacylglycerols and phosphatidylinositols with fibrin-rich areas. Conclusions: By comparing lipid species in plaque and plasma, we identified those circulating species that were also prominently present in plaque. Quantitative comparison of lipid spectral patterns with histology revealed the presence of specific lipid species in destabilized plaque areas, corroborating previous in vitro and animal studies.","Atherosclerosis; Carotid endarterectomy; Desorption electrospray ionization-mass spectrometry imaging; Histology; Lipidomics; Plaque destabilization","en","journal article","","","","","","","","","","Biomechanical Engineering","","","",""
"uuid:1a9044e9-9cf9-4afa-8c03-0dfd410c2866","http://resolver.tudelft.nl/uuid:1a9044e9-9cf9-4afa-8c03-0dfd410c2866","Characterization of unipolar electrogram morphology: A novel tool for quantifying conduction inhomogeneity","Ye, Ziliang (Erasmus MC); van Schie, M.S. (TU Delft Biomechanical Engineering; Erasmus MC); Pool, Lisa (Erasmus MC); Heida, Annejet (Erasmus MC); Knops, Paul (Erasmus MC); Taverne, Yannick J.H.J. (Erasmus MC); Brundel, Bianca J.J.M. (Amsterdam UMC); de Groot, N.M.S. (TU Delft Biomechanical Engineering; TU Delft Signal Processing Systems; Erasmus MC)","","2023","Aims: Areas of conduction inhomogeneity (CI) during sinus rhythm may facilitate the initiation and perpetuation of atrial fibrillation (AF). Currently, no tool is available to quantify the severity of CI. Our aim is to develop and validate a novel tool using unipolar electrograms (EGMs) only to quantify the severity of CI in the atria. Methods and results: Epicardial mapping of the right atrium (RA) and left atrium, including Bachmann's bundle, was performed in 235 patients undergoing coronary artery bypass grafting surgery. Conduction inhomogeneity was defined as the amount of conduction block. Electrograms were classified as single, short, long double (LDP), and fractionated potentials (FPs), and the fractionation duration of non-single potentials was measured. The proportion of low-voltage areas (LVAs, <1mV) was calculated. Increased CI was associated with decreased potential voltages and increased LVAs, LDPs, and FPs. The Electrical Fingerprint Score consisting of RA EGM features, including LVAs and LDPs, was most accurate in predicting CI severity. The RA Electrical Fingerprint Score demonstrated the highest correlation with the amount of CI in both atria (r = 0.70, P < 0.001). Conclusion: The Electrical Fingerprint Score is a novel tool to quantify the severity of CI using only unipolar EGM characteristics recorded. This tool can be used to stage the degree of conduction abnormalities without constructing spatial activation patterns, potentially enabling early identification of patients at high risk of post-operative AF or selection of the appropriate ablation approach in addition to pulmonary vein isolation at the electrophysiology laboratory.","Atrial fibrillation; Conduction inhomogeneity; Diagnostic tool; Epicardial mapping; Sinus rhythm","en","journal article","","","","","","","","","","Biomechanical Engineering","Signal Processing Systems","","",""
"uuid:a6b2f9f5-2a85-46d3-92fd-a097f8a4367c","http://resolver.tudelft.nl/uuid:a6b2f9f5-2a85-46d3-92fd-a097f8a4367c","Mechanical and shape memory properties of NiTi triply periodic minimal surface structures fabricated by laser powder bed fusion","Sun, Lingqi (Huazhong University of Science and Technology); Chen, K. (TU Delft Biomechanical Engineering); Geng, Peng (Huazhong University of Science and Technology); Zhou, Yan (Huazhong University of Science and Technology); Wen, Shifeng (Huazhong University of Science and Technology); Shi, Yusheng (Huazhong University of Science and Technology)","","2023","Porous NiTi lattice structures are widely used in the manufacture of crucial components owing to their excellent shape memory effect, superelasticity, and high damping capacities. However, the specific strength and lightweight characteristics of porous NiTi lattice structures fabricated by conventional technologies are limited by unpredictability. In this work, three types of porous NiTi structures based on triply periodic minimal surface (TPMS) – Diamond, Gyroid, and Primitive – were designed and manufactured by the laser powder bed fusion (LPBF) additive manufacturing process. This work demonstrates LPBF is a feasible and efficient approach to fabricate highly accurate porous NiTi TPMS structures. Moreover, the influence of each of these structures on the mechanical and shape memory properties was investigated. Among the three structures, Gyroid had the smallest volume fraction deviation. Furthermore, the Diamond structure had the largest compressive modulus (782.82 MPa) and ultimate yield strength (163.14 MPa). The Gyroid and Primitive structures exhibit excellent elastic recovery deriving from high values of compressive modulus (662.44 MPa, and 703.29 MPa), and can maintain reliable structural robustness. The Primitive structure exhibited the lowest mechanical properties (37.80 MPa). During the cyclic compression test, Gyroid and Primitive show a smaller unrecovered strain than Diamond. Primitive shows the largest recovered strain during the heating process (6.98%). The higher mechanical flexibility of Primitive structure endows this structure with higher recovery ratio. During the direct compression test, the residual strain exhibits a positive correlation with the loading strain. All three structures exhibit good deformation recovery capability with a strain of 4%. At a strain of 12%, recovered strain during heating became the dominant factor in the recovery of the TPMS structure. Overall, porous NiTi TPMS structures are capable of reversible compressibility composed of rapid elastic recovery and controllable shape memory recovery. The unique performance of porous NiTi TPMS structure fabricated by LPBF renders it a highly efficiency energy-absorbing structure.","Laser powder bed fusion; NiTi alloy; Shape memory effect; Three-period minimum surface","en","journal article","","","","","","Green Open Access added to TU Delft Institutional Repository 'You share, we take care!' - Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.","","2024-01-05","","Biomechanical Engineering","","","",""
"uuid:956476f0-dbdc-4402-a16d-c99d225c4c04","http://resolver.tudelft.nl/uuid:956476f0-dbdc-4402-a16d-c99d225c4c04","Developing a Digital Medication Adherence Intervention for and With Patients With Asthma and Low Health Literacy: Protocol for a Participatory Design Approach","Faber, J.S. (TU Delft Design Aesthetics); Poot, Charlotte C. (Leiden University Medical Center); Dekkers, Tessa (University of Twente); Romero Herrera, N.A. (TU Delft Design Conceptualization and Communication); Chavannes, N.H. (TU Delft Biomechanical Engineering; Leiden University Medical Center); Meijer, Eline (Leiden University Medical Center); Visch, V.T. (TU Delft Design Aesthetics)","","2023","Background: Current eHealth interventions are poorly adopted by people with low health literacy (LHL) as they often fail to meet their needs, skills, and preferences. A major reason for this poor adoption is the generic, one-size-fits-all approach taken by designers of these interventions, without addressing the needs, skills, and preferences of disadvantaged groups. Participatory design approaches are effective for developing interventions that fit the needs of specific target groups; yet, very little is known about the practical implications of executing a participatory design project for and with people with LHL. Objective: This study aimed to demonstrate the application of participatory design activities specifically selected to fit the needs and skills of people with LHL and how these were manifested within an overarching eHealth design process. In addition, the study aims to present reflections and implications of these activities that could support future designers to engage people with LHL in their design processes. Methods: We used the design process of a smart asthma inhaler for people with asthma and LHL to demonstrate participatory design activities. The study was framed under 5 stages of design thinking: empathize, define, ideate, prototype, and test within 2 major iteration cycles. We integrated 3 participatory design activities deemed specifically appropriate for people with LHL: co-constructing stories, experience prototype exhibition, and video prototype evaluation. Results: Co-constructing stories was found to deepen the understanding of the participant’s motivation to use or not to use maintenance medication. This understanding informed and facilitated the subsequent development of diverse preliminary prototypes of possible interventions. Discussing these prototypes in the experience prototype exhibition helped provoke reactions, thoughts, and feelings about the interventions, and potential scenarios of use. Through the video prototype evaluation, we were able to clearly communicate the goal and functionality of the final version of our intervention and gather appropriate responses from our participants. Conclusions: This study demonstrates a participatory design approach for and with patients with asthma and LHL. We demonstrated that careful consideration and selection of activities can result in participants that are engaged and feel understood. This paper provides insight into the practical implications of participatory activities with people with LHL and supports and inspires future designers to engage with this disadvantaged target group.","asthma; eHealth; health care; health literacy; low health literacy; medication; medication adherence; mHealth; participatory design; participatory medicine; OA-Fund TU Delft","en","journal article","","","","","","","","","","Biomechanical Engineering","Design Aesthetics","","",""
"uuid:79681030-8cba-4a19-b83a-161214dbfd27","http://resolver.tudelft.nl/uuid:79681030-8cba-4a19-b83a-161214dbfd27","Sensory weighting of position and force feedback during pinching","Geelen, J.E. (TU Delft Biomechatronics & Human-Machine Control); van der Helm, F.C.T. (TU Delft Biomechatronics & Human-Machine Control); Schouten, A.C. (TU Delft Biomechanical Engineering); Mugge, W. (TU Delft Biomechatronics & Human-Machine Control)","","2023","Human hands are complex biomechanical systems that allow for dexterous tasks with many degrees of freedom. Coordination of the fingers is essential for many activities of daily living and involves integrating sensory signals. During this sensory integration, the central nervous system deals with the uncertainty of sensory signals. When handling compliant objects, force and position are related. Interactions with stiff objects result in reduced position changes and increased force changes compared to compliant objects. Literature has shown sensory integration of force and position at the shoulder. Nevertheless, differences in sensory requirements between proximal and distal joints may lead to different proprioceptive representations, hence findings at proximal joints cannot be directly transferred to distal joints, such as the digits. Here, we investigate the sensory integration of force and position during pinching. A haptic manipulator rendered a virtual spring with adjustable stiffness between the index finger and the thumb. Participants had to blindly reproduce a force against the spring. In both visual reference trials and blind reproduction trials, the relation between pinch force and spring compression was constant. However, by covertly changing the spring characteristics in catch trials into an adjusted force-position relation, the participants’ weighting of force and position could be revealed. In agreement with previous studies on the shoulder, participants relied more on force sense in trials with higher stiffness. This study demonstrated stiffness-dependent sensory integration of force and position feedback during pinching.","Fingers; Motor control; Pinching; Proprioception; Sensory integration; Sensory weighting","en","journal article","","","","","","","","","","Biomechanical Engineering","Biomechatronics & Human-Machine Control","","",""
"uuid:6b1b0620-1f59-4d7b-b95c-5c7f51ce9266","http://resolver.tudelft.nl/uuid:6b1b0620-1f59-4d7b-b95c-5c7f51ce9266","Biomarker identification for endometriosis as a target for real-time intraoperative fluorescent imaging: A new approach using transcriptomic analysis to broaden the search for potential biomarkers","Tummers, Fokkedien H.M.P. (Leiden University Medical Center); Bazelmans, Maria K. (Leiden University Medical Center); Jansen, F.W. (TU Delft Medical Instruments & Bio-Inspired Technology; Leiden University Medical Center); Blikkendaal, Mathijs D. (Reinier de Graaf Gasthuis); Vahrmeijer, Alexander L. (Leiden University Medical Center); Kuppen, P.J.K. (TU Delft Biomechanical Engineering; Leiden University Medical Center)","","2023","Intra-operative fluorescent imaging of endometriosis could help to optimize surgical treatment. Potential biomarkers to use as target for endometriosis-binding fluorescent probes were identified using a new five-phase transcriptomics-based approach to broaden the search for biomarkers. Using publicly available datasets, a differentially expressed gene (DEG) analysis was performed for endometriosis versus surgically relevant surrounding tissue (peritoneum, bladder, sigmoid, rectum, transverse colon, small intestine, vagina, and fallopian tubes) for which data was available. The remaining relevant surrounding tissues were analyzed for low expression levels. DEGs with a predicted membranous or extracellular location and with low expression levels in surrounding tissue were identified as candidate targets. Modified Target Selection Criteria were used to rank candidate targets based on the highest potential for use in fluorescent imaging. 29 potential biomarkers were ranked, resulting in Folate receptor 1 as the most potential biomarker. This is a first step towards finding a fluorescent tracer for intra-operative visualization of endometriosis. Additionally, this approach, using transcriptomics analysis to identifying candidate targets for a specific type of tissue for use in fluorescence-guided surgery could be translated to other surgical fields. Tweetable abstract: A new approach using transcriptomics analysis is shown to identify candidate targets for intra-operative fluorescent imaging for endometriosis, resulting in 29 potential candidates.","Biomarker; Differentially expressed genes analysis; Endometriosis; Fluorescence-guided surgery; Minimally invasive surgery; Transcriptomics","en","review","","","","","","","","","","Biomechanical Engineering","Medical Instruments & Bio-Inspired Technology","","",""
"uuid:7d9d451c-9d31-4154-96da-87ed09e688df","http://resolver.tudelft.nl/uuid:7d9d451c-9d31-4154-96da-87ed09e688df","Critical appraisal of technologies to assess electrical activity during atrial fibrillation: a position paper from the European Heart Rhythm Association and European Society of Cardiology Working Group on eCardiology in collaboration with the Heart Rhythm Society, Asia Pacific Heart Rhythm Society, Latin American Heart Rhythm Society and Computing in Cardiology","de Groot, N.M.S. (TU Delft Signal Processing Systems; TU Delft Biomechanical Engineering; Erasmus MC); Shah, Dipen (University Hospital of Geneva); Boyle, Patrick M. (University of Washington); Anter, Elad (Cleveland Clinic Foundation); Clifford, Gari D. (Emory University); Deisenhofer, Isabel (German Heart Center Munich and Technical University of Munich); van Dessel, Pascal (Medisch Spectrum Twente); Dilaveris, Polychronis (National and Capodistrian University of Athens); van der Veen, A.J. (TU Delft Signal Processing Systems; Circuits and Systems (CAS) Group)","","2022","We aim to provide a critical appraisal of basic concepts underlying signal recording and processing technologies applied for (i) atrial fibrillation (AF) mapping to unravel AF mechanisms and/or identifying target sites for AF therapy and (ii) AF detection, to optimize usage of technologies, stimulate research aimed at closing knowledge gaps, and developing ideal AF recording and processing technologies. Recording and processing techniques for assessment of electrical activity during AF essential for diagnosis and guiding ablative therapy including body surface electrocardiograms (ECG) and endo- or epicardial electrograms (EGM) are evaluated. Discussion of (i) differences in uni-, bi-, and multi-polar (omnipolar/Laplacian) recording modes, (ii) impact of recording technologies on EGM morphology, (iii) global or local mapping using various types of EGM involving signal processing techniques including isochronal-, voltage- fractionation-, dipole density-, and rotor mapping, enabling derivation of parameters like atrial rate, entropy, conduction velocity/direction, (iv) value of epicardial and optical mapping, (v) AF detection by cardiac implantable electronic devices containing various detection algorithms applicable to stored EGMs, (vi) contribution of machine learning (ML) to further improvement of signals processing technologies. Recording and processing of EGM (or ECG) are the cornerstones of (body surface) mapping of AF. Currently available AF recording and processing technologies are mainly restricted to specific applications or have technological limitations. Improvements in AF mapping by obtaining highest fidelity source signals (e.g. catheter-electrode combinations) for signal processing (e.g. filtering, digitization, and noise elimination) is of utmost importance. Novel acquisition instruments (multi-polar catheters combined with improved physical modelling and ML techniques) will enable enhanced and automated interpretation of EGM recordings in the near future.","Atrial fibrillation; Cardiac implantable electronic devices; EHRA position paper; Machine learning; Mapping; Signal processing; Signal recording","en","journal article","","","","","","","","","","Biomechanical Engineering","Signal Processing Systems","","",""
"uuid:c440aace-675e-4417-ae4b-b064eaf9e5bc","http://resolver.tudelft.nl/uuid:c440aace-675e-4417-ae4b-b064eaf9e5bc","Feasibility of a home-based physiotherapy intervention to promote post-stroke mobility: A randomized controlled pilot study","Jarbandhan, Ameerani (Anton de Kom University of Suriname); Toelsie, Jerry (Anton de Kom University of Suriname); Veeger, H.E.J. (TU Delft Biomechanical Engineering); Bipat, Robbert (Anton de Kom University of Suriname); Vanhees, Luc (Katholieke Universiteit Leuven); Buys, Roselien (Katholieke Universiteit Leuven)","","2022","Objectives Home-based physiotherapy interventions to improve post-stroke mobility are successful in high-income countries. These programs require less resources compared to center-based programs. However, feasibility of such an intervention in a low and middle-income setting remains unknown. Therefore, the SunRISe (Stroke Rehabilitation In Suriname) study aimed to assess feasibility and preliminary effectiveness of a home-based semi-supervised physiotherapy intervention to promote post-stroke mobility in a low resource setting. Design Prospective randomized controlled trial. Methods Chronic stroke patients were recruited and randomized into either an intervention group (IG (N = 20)) or a control group (CG (N = 10)). The IG received a 3-days-a-week home-based physiotherapy program that was supervised in the first 4 weeks and tele-supervised during the second 4 weeks. The physiotherapy program consisted of walking as well as functional and mobilization exercises. The CG received usual care. Feasibility outcome measures included adherence, patient satisfaction and safety. Efficacy measures included functional exercise tolerance (six-minute walking test (6MWT), functional balance (Berg Balance Score (BBS), upper extremity (UE) function (Disabilities of the Arm, Shoulder and Hand (DASH) Questionnaire), and UE strength ((non-)paretic handgrip (HG) strength). Two-way analysis of variance was used for data analysis. Results Thirty participants (61.8 ± 9.2 years old, 13 men) were enrolled in the study. The intervention was completed by 14 participants (70%). Adherence was affected by rainy season associated infrastructural problems (n = 2), the medical status of participants (n = 3) and insufficient motivation to continue the program without direct supervision (n = 1). No adverse events were noted and participants were satisfied with the program. Functional exercise tolerance (57.2 ± 67.3m, p = 0.02) and UE function (-9.8 ± 15.2, p = 0.04) improved in the IG compared to no change in the CG. HG strength was unaltered and a ceiling effect occurred for BBS. Conclusion Our home-based semi-supervised physiotherapy intervention seems safe, associated with moderate to high levels of engagement and patient satisfaction and results in functional improvements.","","en","journal article","","","","","","","","","","Biomechanical Engineering","","","",""
"uuid:f2d77f43-df76-4861-b06f-9b6747b985de","http://resolver.tudelft.nl/uuid:f2d77f43-df76-4861-b06f-9b6747b985de","Augmented reality navigation for minimally invasive craniosynostosis surgery: a phantom study","Thabit, Abdullah (Erasmus MC); Benmahdjoub, Mohamed (Erasmus MC); van Veelen, Marie Lise C. (Erasmus MC); Niessen, W.J. (TU Delft ImPhys/Medical Imaging; TU Delft ImPhys/Computational Imaging; Erasmus MC); Wolvius, Eppo B. (Erasmus MC); van Walsum, T. (TU Delft Biomechanical Engineering; Erasmus MC)","","2022","Purpose: In minimally invasive spring-assisted craniectomy, surgeons plan the surgery by manually locating the cranial sutures. However, this approach is prone to error. Augmented reality (AR) could be used to visualize the cranial sutures and assist in the surgery planning. The purpose of our work is to develop an AR-based system to visualize cranial sutures, and to assess the accuracy and usability of using AR-based navigation for surgical guidance in minimally invasive spring-assisted craniectomy. Methods: An AR system was developed that consists of an electromagnetic tracking system linked with a Microsoft HoloLens. The system was used to conduct a study with two skull phantoms. For each phantom, five sutures were annotated and visualized on the skull surface. Twelve participants assessed the system. For each participant, model alignment using six anatomical landmarks was performed, followed by the participant delineation of the visualized sutures. At the end, the participants filled a system usability scale (SUS) questionnaire. For evaluation, an independent optical tracking system was used and the delineated sutures were digitized and compared to the CT-annotated sutures. Results: For a total of 120 delineated sutures, the distance of the annotated sutures to the planning reference was 2.4 ± 1.2 mm. The average delineation time per suture was 13 ± 5 s. For the system usability questionnaire, an average SUS score of 73 was obtained. Conclusion: The developed AR-system has good accuracy (average 2.4 mm distance) and could be used in the OR. The system can assist in the pre-planning of minimally invasive craniosynostosis surgeries to locate cranial sutures accurately instead of the traditional approach of manual palpation. Although the conducted phantom study was designed to closely reflect the clinical setup in the OR, further clinical validation of the developed system is needed and will be addressed in a future work.","Augmented reality; Cranial sutures; Craniectomy; Craniosynostosis; Image guidance; Surgical navigation","en","journal article","","","","","","","","","","Biomechanical Engineering","ImPhys/Medical Imaging","","",""
"uuid:8eb0cbcb-e61e-4750-bbf4-169ceb2cbbab","http://resolver.tudelft.nl/uuid:8eb0cbcb-e61e-4750-bbf4-169ceb2cbbab","Surface Electrocardiogram Reconstruction Using Intra-operative Electrograms","Moghaddasi, Hanie (TU Delft Signal Processing Systems); Hunyadi, Borbala (TU Delft Signal Processing Systems); van der Veen, A.J. (TU Delft Signal Processing Systems); de Groot, N.M.S. (TU Delft Signal Processing Systems; TU Delft Biomechanical Engineering); Hendriks, R.C. (TU Delft Signal Processing Systems)","Louveaux, Jérôme (editor); Quitin, François (editor)","2022","Atrial Fibrillation (AF) is the most sustained arrhythmia in the heart. On the surface electrocardiogram (ECG), AF is characterised by the irregular RR intervals and by fibrillatory waves or the absence of a P wave. Since AF is a progressive disease, timely and correct detection is crucial for AF treatment. Detailed insight into the areas of arrhythmia-related electropathology can be obtained by analyzing high-resolution (inter-electrode distance 2mm) electrograms (EGMs). However, these measurements are rather invasive. By integration of high-resolution epicardial mapping data and surface ECG data, we hope to learn how different stages of AF represent themselves on the ECG. Eventually this can help to guide to identify areas of electropathology as target sites of ablation therapy on the less invasive ECG. A first step in this direction is to learn how to reconstruct the ECG based on EGM measurements. In practice, however, EGMs are only measured at few atrial locations, not covering the complete atria. An important question therefore is: How can we reconstruct ECG based on the observations from a limited part of the heart? To answer this question, we propose two methods. In the first method, we increase the number of observations from a part of the right atrium (RA) to the whole RA by synchronizing EGMs that are measured at different moments in time based on the local activation time (LAT). In the second method, under the assumption that atrial EGMs measured at different spatial areas are linearly related, the conductivity matrix is estimated for the whole atrium which enables us to reconstruct the ECGs from the limited observations. The second method brings twofold benefits. First, the conductivity matrix can be used as a novel diagnostic tool to detect AF as well as areas of electropathology. Second, it provides a practical solution to reconstruct epicardial potentials from ECGs, non- This research was funded in part by the Medical Delta Cardiac Arrhythmia Lab (CAL), the Netherlands. invasively. The results show that method one increases the reconstruction accuracy. Furthermore, the conductivity matrix reveals the structural differences between sinus rhythm (SR) and AF episodes which could be the first step to interpret the underlying electropathology of AF","","en","conference paper","","","","","","","","","","Biomechanical Engineering","Signal Processing Systems","","",""
"uuid:b07323b1-bc59-499f-836b-ff744d7e624e","http://resolver.tudelft.nl/uuid:b07323b1-bc59-499f-836b-ff744d7e624e","The effect of an occlusion-induced delay on braking behavior in critical situations: A driving simulator study","de Winter, J.C.F. (TU Delft Human-Robot Interaction); Saffarian, M (TU Delft Biomechanical Engineering; University of Toronto); Senders, John W. (University of Toronto)","","2022","Objective: To share results of an experiment that used visual occlusion for a new purpose: inducing a waiting time. Background: Senders was a leading figure in human factors. In his research on the visual demands of driving, he used occlusion techniques. Methods: In a simulator experiment, we examined how drivers brake for different levels of urgency and different visual conditions. In three blocks (1 = brake lights, 2 = no brake lights, 3 = occlusion), drivers followed a vehicle at 13.4 or 33.4 m distance. At certain moments, the lead vehicle decelerated moderately (1.7 m/s2) or strongly (6.5 m/s2). In the occlusion condition, the screens blanked for 0.4 s (if 6.5 m/s2) or 2.0 s (if 1.7 m/s2) when the lead vehicle started to decelerate. Participants were instructed to brake only after the occlusion ended. Results: The lack of brake lights caused a delayed response. In the occlusion condition, drivers adapted to the instructed late braking by braking harder. However, adaptation was not always possible: In the most urgent condition, most participants collided with the lead vehicle because the ego-vehicle’s deceleration limits were reached. In non-urgent conditions, some drivers braked unnecessarily hard. Furthermore, while waiting until the occlusion cleared, some drivers lightly touched the brake pedal. Conclusion: This experimental design demonstrates how drivers (sometimes fail to) adjust their braking behavior to the criticality of the situation. Application: The phenomena of biomechanical readiness and (inappropriate) dosing of the brake pedal may be relevant to safety, traffic flow, and ADAS design.","brake control; brake lights; emergency braking; occlusion","en","journal article","","","","","","","","","","Biomechanical Engineering","Human-Robot Interaction","","",""
"uuid:85be473e-1513-4a29-8602-9230551eb7af","http://resolver.tudelft.nl/uuid:85be473e-1513-4a29-8602-9230551eb7af","Management of displaced humeral surgical neck fractures in daily clinical practice: hanging does not re-align the fracture","Spek, Reinier W.A. (Flinders Medical Centre; University Medical Center Groningen; Onze Lieve Vrouwe Gasthuis); Hoogervorst, Lotje A. (Leiden University Medical Center); Elias, Michaëla E.C. (Onze Lieve Vrouwe Gasthuis); Jaarsma, Ruurd L. (Flinders Medical Centre); Veeger, H.E.J. (TU Delft Biomechanical Engineering); Doornberg, Job N. (University Medical Center Groningen); Jutte, Paul C. (University Medical Center Groningen); van den Bekerom, Michel P.J. (Vrije Universiteit Amsterdam)","","2022","Introduction: It is unclear if the collar and cuff treatment improve alignment in displaced surgical neck fractures of the proximal humerus. Therefore, this study evaluated if the neckshaft angle and extent of displacement would improve between trauma and onset of radiographically visible callus in non-operatively treated surgical neck fractures (Boileau type A, B, C). Materials and Methods: A consecutive series of patients (≥ 18 years old) were retrospectively evaluated from a level 1 trauma center in Australia (inclusion period: 2016–2020) and a level 2 trauma center in the Netherlands (inclusion period: 2004 to 2018). Patients were included if they sustained a Boileau-type fracture and underwent initial non-operative treatment. The first radiograph had to be obtained within 24 h after the initial injury and the follow-up radiograph(s) 1 week after trauma and before the start of radiographically visible callus. On each radiograph, the maximal medial gap (MMG), maximal lateral gap (MLG), and neck-shaft angle (NSA) were measured. Linear mixed modelling was performed to evaluate if these measurements would improve over time. Results: Sixty-seven patients were included: 25 type A, 11 type B, and 31 type C fractures. The mean age (range) was 68 years (24–93), and the mean number (range) of follow-up radiographs per patient was 1 (1–4). Linear mixed modelling on both MMG and MLG revealed no improvement during follow-up among the three groups. Mean NSA of type A fractures improved significantly from 161° at trauma to 152° at last follow-up (p-value = 0.004). Conclusions: Apart from humeral head angulation improvement in type A, there is no increase nor reduction in displacement among the three fracture patterns. Therefore, it is advised that surgical decision-making should be performed immediately after trauma. Level of clinical evidence: Level IV, retrospective case series.","Boileau classification; Non-operative management; Proximal humerus fracture; Radiographic evaluation; Re-alignment; Surgical neck fractures","en","journal article","","","","","","","","","","Biomechanical Engineering","","","",""
"uuid:e88060db-e270-4014-9642-6fcddb3d8e80","http://resolver.tudelft.nl/uuid:e88060db-e270-4014-9642-6fcddb3d8e80","Quantifying Within-Individual Elbow Load Variability in Youth Elite Baseball Pitchers and Its Role in Overuse Injuries","van Trigt, B. (TU Delft Biomechanical Engineering); Bouman, F.F. (Student TU Delft); Leenen, Antonius J. R. (Vrije Universiteit Amsterdam); Hoozemans, Marco J.M. (Vrije Universiteit Amsterdam); van der Helm, F.C.T. (TU Delft Biomechatronics & Human-Machine Control); Veeger, H.E.J. (TU Delft Biomechanical Engineering)","","2022","Medial elbow overuse injuries are rising in baseball. The external valgus torque magnitude is a possible risk factor for medial elbow injuries. The magnitude on its own cannot explain why one pitcher sustains an injury and another does not. Therefore, the aim of this study is to describe the within-individual external valgus torque variability and to determine whether the within-individual external valgus torque variability can be described by a Gaussian distribution. Eleven youth elite baseball pitchers threw twenty-five fastball pitches. Body kinematics were measured with VICON motion capture at 400 Hz. Elbow valgus torques of the total 270 pitches were calculated with a custom-made inverse dynamic model in Python. Visual inspection and the Shapiro–Wilk test were performed to test for the within-individual elbow valgus torque normality. The results showed that within-individual valgus torque variability was present in pitchers and differed among pitchers. Furthermore, it was shown that the within-individual valgus torque variability was normally distributed in nine out of eleven subjects. In conclusion, the presence of and differences in within-individual elbow load variability among baseball pitchers can be useful variables as they might be related to overuse elbow injuries.","fastball; biomechanics; valgus torque; kinetics; ulnar collateral ligament (UCL); injury prevention","en","journal article","","","","","","","","","","Biomechanical Engineering","Biomechatronics & Human-Machine Control","","",""
"uuid:2aed8c7e-88bb-4d10-a40f-797ee6c702cc","http://resolver.tudelft.nl/uuid:2aed8c7e-88bb-4d10-a40f-797ee6c702cc","Shoulder muscle activity after latissimus dorsi transfer in an active elevation","Gurnani, Navin (Vrije Universiteit Amsterdam); van Deurzen, Derek F.P. (Onze Lieve Vrouwe Gasthuis); Willems, W. Jaap (DC Expert Centre, Amsterdam); Janssen, Thomas W.J. (Vrije Universiteit Amsterdam); Veeger, H.E.J. (TU Delft Biomechanical Engineering)","","2022","Background: After latissimus dorsi transfer (LDT), an increase in scapulothoracic (ST) contribution in thoracohumeral (TH) elevation is observed when compared to the asymptomatic shoulder. It is not known which shoulder muscles contribute to this change in shoulder kinematics, and whether the timing of muscle recruitment has altered after LDT. The aim of the study was to identify which shoulder muscles and what timing of muscle recruitment are responsible for the increased ST contribution and shoulder elevation after LDT for a massive irreparable posterosuperior rotator cuff tear (MIRT). Methods: Thirteen patients with a preoperative pseudoparalysis and MIRT were recruited after LDT with a minimum follow-up of 1 year. Three-dimensional electromagnetic tracking was used to assess maximum active elevation of the shoulder (MAES) in both the LDT and the asymptomatic contralateral shoulder (ACS). Surface electromyography (EMG) tracked activation (% EMG max) and activation timing of the latissimus dorsi (LD), deltoid, teres major, trapezius (upper, middle and lower) and serratus anterior muscles were collected. MAES was studied in forward flexion, scapular abduction and abduction in the coronal plane. Results: In MAES, no difference in thoracohumeral motion was observed between the LDT and ACS, P = .300. However, the glenohumeral motion for MAES was significantly lower in LDT shoulders F(1,12) = 11.230, P = .006. The LD % EMG max did not differ between the LDT and ACS in MAES. A higher % EMG max was found for the deltoid F(1,12) = 17.241, P = .001, and upper trapezius F(1,10) = 13.612, P = .004 in the LDT shoulder during MAES. The middle trapezius only showed a higher significant difference in % EMG max for scapular abduction, P = .020 (LDT, 52.3 ± 19.4; ACS, 38.1 ± 19.7).The % EMG max of the lower trapezius, serratus anterior and teres major did not show any difference in all movement types between the LDT and ACS and no difference in timing of recruitment of all the shoulder muscles was observed. Conclusions: After LDT in patients with a MIRT and preoperative pseudoparalysis, the LD muscle did not alter its % EMG max during MAES when compared to the ACS. The cranial transfer of the LD tendon with its native %EMG max, together with the increased %EMG max of the deltoid, middle and upper trapezius muscles could be responsible for the increased ST contribution. The increased glenohumeral joint reaction force could in turn increase active elevation after LDT in a previous pseudoparalytic shoulder.","Basic Science Study; Electromyography; Kinesiology; Latissimus dorsi; Massive rotator cuff tear; Muscle transfer; Shoulder surgery","en","journal article","","","","","","","","","","Biomechanical Engineering","","","",""
"uuid:e5efb3ad-7223-4c7f-ab97-3e356dbce8a0","http://resolver.tudelft.nl/uuid:e5efb3ad-7223-4c7f-ab97-3e356dbce8a0","Energy flow through the lower extremities in high school baseball pitching","de Swart, A.F.M.J. (TU Delft Support Biomechanical Engineering; Vrije Universiteit Amsterdam); van Trigt, B. (TU Delft Biomechanical Engineering; Vrije Universiteit Amsterdam); Wasserberger, Kyle (Auburn University; Driveline Baseball); Hoozemans, Marco J.M. (Vrije Universiteit Amsterdam); Veeger, H.E.J. (TU Delft Biomechanical Engineering); Oliver, Gretchen D. (Auburn University)","","2022","It is generally accepted that most of the energy transferred to the ball during a baseball pitch is generated in the trunk and lower extremities. Therefore, purpose of this study was to assess the energy flow through the lower extremities during a baseball pitch. It was hypothesised that the (stabilising) leading leg mainly transfers energy in a distal-to-proximal order as a kinetic chain while the (driving) trailing leg generates most energy, primarily at the hip. A joint power analysis was used to determine the rates of energy (power) transfer and generation in the ankles, knees, hips and lumbosacral joint (L5-S1) for 22 youth pitchers. Analyses showed that the leading leg mainly transfers energy upwards in a distal-to-proximal order just before stride foot contact. Furthermore, energy generation was higher in the trailing leg and primarily arose from the trailing hip. In conclusion, the legs contribute differently to the energy flow where the leading leg acts as an initial kinetic chain component and the trailing leg drives the pitch by generating energy. The actions of both legs are combined in the pelvis and passed on to the subsequent, more commonly discussed, open kinetic chain starting at L5-S1.","biomechanics; kinetic chain; lower body; power generation; Power transfer","en","journal article","","","","","","","","","","Biomechanical Engineering","Support Biomechanical Engineering","","",""
"uuid:848760ed-77ba-4f42-ae83-70c8841c7209","http://resolver.tudelft.nl/uuid:848760ed-77ba-4f42-ae83-70c8841c7209","Classification of Wheelchair Related Shoulder Loading Activities from Wearable Sensor Data: A Machine Learning Approach","de Vries, Wiebe H.K. (Swiss Paraplegic Research); Amrein, Sabrina (Swiss Paraplegic Research; ETH Zürich); Arnet, Ursina (Swiss Paraplegic Research); Mayrhuber, Laura (Swiss Paraplegic Research); Ehrmann, Cristina (Swiss Paraplegic Research); Veeger, H.E.J. (TU Delft Biomechanical Engineering)","","2022","Shoulder problems (pain and pathology) are highly prevalent in manual wheelchair users with spinal cord injury. These problems lead to limitations in activities of daily life (ADL), labor- and leisure participation, and increase the health care costs. Shoulder problems are often associated with the long-term reliance on the upper limbs, and the accompanying “shoulder load”. To make an estimation of daily shoulder load, it is crucial to know which ADL are performed and how these are executed in the free-living environment (in terms of magnitude, frequency, and duration). The aim of this study was to develop and validate methodology for the classification of wheelchair related shoulder loading ADL (SL-ADL) from wearable sensor data. Ten able bodied participants equipped with five Shimmer sensors on a wheelchair and upper extremity performed eight relevant SL-ADL. Deep learning networks using bidirectional long short-term memory networks were trained on sensor data (acceleration, gyroscope signals and EMG), using video annotated activities as the target. Overall, the trained algorithm performed well, with an accuracy of 98% and specificity of 99%. When reducing the input for training the network to data from only one sensor, the overall performance decreased to around 80% for all performance measures. The use of only forearm sensor data led to a better performance than the use of the upper arm sensor data. It can be concluded that a generalizable algorithm could be trained by a deep learning network to classify wheelchair related SL-ADL from the wearable sensor data.","classification; deep learning; shoulder loading activities; wearable sensors; wheelchair","en","journal article","","","","","","","","","","Biomechanical Engineering","","","",""
"uuid:f3ad7f40-b4e4-48b1-9959-ad65bf89becc","http://resolver.tudelft.nl/uuid:f3ad7f40-b4e4-48b1-9959-ad65bf89becc","Using Wearable Sensors to Estimate Mechanical Power Output in Cyclical Sports Other than Cycling: A Review","De Vette, V.G. (TU Delft Medical Instruments & Bio-Inspired Technology); Veeger, H.E.J. (TU Delft Biomechatronics & Human-Machine Control); van Dijk, M.P. (TU Delft Biomechanical Engineering)","","2022","More insight into in-field mechanical power in cyclical sports is useful for coaches, sport scientists, and athletes for various reasons. To estimate in-field mechanical power, the use of wearable sensors can be a convenient solution. However, as many model options and approaches for mechanical power estimation using wearable sensors exist, and the optimal combination differs between sports and depends on the intended aim, determining the best setup for a given sport can be challenging. This review aims to provide an overview and discussion of the present methods to estimate in-field mechanical power in different cyclical sports. Overall, in-field mechanical power estimation can be complex, such that methods are often simplified to improve feasibility. For example, for some sports, power meters exist that use the main propulsive force for mechanical power estimation. Another non-invasive method usable for in-field mechanical power estimation is the use of inertial measurement units (IMUs). These wearable sensors can either be used as stand-alone approach or in combination with force sensors. However, every method has consequences for interpretation of power values. Based on the findings of this review, recommendations for mechanical power measurement and interpretation in kayaking, rowing, wheelchair propulsion, speed skating, and cross-country skiing are done.","cyclic sports; mechanical power; power output; wearable sensors; wearable technology; inertial measurement unit; IMU; power meter","en","review","","","","","","","","","","Biomechanical Engineering","Medical Instruments & Bio-Inspired Technology","","",""
"uuid:7a972596-c121-49d1-a081-a215c092bd04","http://resolver.tudelft.nl/uuid:7a972596-c121-49d1-a081-a215c092bd04","Unperceived motor actions of the balance system interfere with the causal attribution of self-motion","Tisserand, Romain (University of British Columbia; Université de Poitiers; Université Tours); Rasman, Brandon G. (Erasmus MC; University of Otago); Omerovic, Nina (Erasmus MC); Peters, Ryan M. (University of British Columbia; University of Calgary); Forbes, P.A. (TU Delft Biomechanical Engineering; Erasmus MC); Blouin, Jean Sébastien (University of British Columbia)","","2022","The instability of human bipedalism demands that the brain accurately senses balancing self-motion and determines whether movements originate from self-generated actions or external disturbances. Here, we challenge the longstanding notion that this process relies on a single representation of the body and world to accurately perceive postural orientation and organize motor responses to control balance self-motion. Instead, we find that the conscious sense of balance can be distorted by the corrective control of upright standing. Using psychophysics, we quantified thresholds to imposed perturbations and balance responses evoking cues of self-motion that are (in)distinguishable from corrective balance actions. When standing immobile, participants clearly perceived imposed perturbations. Conversely, when freely balancing, participants often misattributed their own corrective responses as imposed motion because their balance system had detected, integrated, and responded to the perturbation in the absence of conscious perception. Importantly, this only occurred for perturbations encoded ambiguously with balance-correcting responses and that remained below the natural variability of ongoing balancing oscillations. These findings reveal that our balance system operates on its own sensorimotor principles that can interfere with causal attribution of our actions, and that our conscious sense of balance depends critically on the source and statistics of induced and self-generated motion cues.","perception; action; standing; postural sway; balance control; psychophysics; perturbation; OA-Fund TU Delft","en","journal article","","","","","","","","","","Biomechanical Engineering","","","",""
"uuid:350a9817-7f91-4729-87cb-b9c71845407b","http://resolver.tudelft.nl/uuid:350a9817-7f91-4729-87cb-b9c71845407b","Human monoclonal antibodies against Staphylococcus aureus surface antigens recognize in vitro and in vivo biofilm","de Vor, Lisanne (University Medical Center Utrecht); van Dijk, Bruce (University Medical Center Utrecht); van Kessel, Kok (University Medical Center Utrecht); Kavanaugh, Jeffrey S. (University of Colorado School of Medicine); de Haas, Carla (University Medical Center Utrecht); Aerts, Piet C. (University Medical Center Utrecht); Ramakers, R.M. (TU Delft RST/Technici Pool; University Medical Center Utrecht; MILabs B.V.); Beekman, F.J. (TU Delft RST/Biomedical Imaging; University Medical Center Utrecht; MILabs B.V.); Weinans, Harrie (TU Delft Biomechanical Engineering; TU Delft Biomaterials & Tissue Biomechanics; University Medical Center Utrecht)","","2022","Implant-associated Staphylococcus aureus infections are difficult to treat because of biofilm formation. Bacteria in a biofilm are often insensitive to antibiotics and host immunity. Monoclonal antibodies (mAbs) could provide an alternative approach to improve the diagnosis and potential treatment of biofilm-related infections. Here, we show that mAbs targeting common surface components of S. aureus can recognize clinically relevant biofilm types. The mAbs were also shown to bind a collection of clinical isolates derived from different biofilm-associated infections (endocarditis, prosthetic joint, catheter). We identify two groups of antibodies: one group that uniquely binds S. aureus in biofilm state and one that recognizes S. aureus in both biofilm and planktonic state. Furthermore, we show that a mAb recognizing wall teichoic acid (clone 4497) specifically localizes to a subcutaneously implanted pre-colonized catheter in mice. In conclusion, we demonstrate the capacity of several human mAbs to detect S. aureus biofilms in vitro and in vivo.","","en","journal article","","","","","","","","","","Biomechanical Engineering","RST/Technici Pool","","",""
"uuid:79ebe221-3a00-4b4f-a57c-596f35c022d7","http://resolver.tudelft.nl/uuid:79ebe221-3a00-4b4f-a57c-596f35c022d7","Obtaining wheelchair kinematics with one sensor only? The trade-off between number of inertial sensors and accuracy for measuring wheelchair mobility performance in sports","van Dijk, M.P. (TU Delft Biomechanical Engineering); van der Slikke, R.M.A. (TU Delft Biomechatronics & Human-Machine Control; The Hague University of Applied Sciences); Rupf, Rob (University of Toronto); Hoozemans, Marco J.M. (Vrije Universiteit Amsterdam); Berger, Monique A.M. (The Hague University of Applied Sciences); Veeger, H.E.J. (TU Delft Biomechanical Engineering)","","2022","In wheelchair sports, the use of Inertial Measurement Units (IMUs) has proven to be one of the most accessible ways for ambulatory measurement of wheelchair kinematics. A three-IMU configuration, with one IMU attached to the wheelchair frame and two IMUs on each wheel axle, has previously shown accurate results and is considered optimal for accuracy. Configurations with fewer sensors reduce costs and could enhance usability, but may be less accurate. The aim of this study was to quantify the decline in accuracy for measuring wheelchair kinematics with a stepwise sensor reduction. Ten differently skilled participants performed a series of wheelchair sport specific tests while their performance was simultaneously measured with IMUs and an optical motion capture system which served as reference. Subsequently, both a one-IMU and a two-IMU configuration were validated and the accuracy of the two approaches was compared for linear and angular wheelchair velocity. Results revealed that the one-IMU approach show a mean absolute error (MAE) of 0.10 m/s for absolute linear velocity and a MAE of 8.1°/s for wheelchair angular velocity when compared with the reference system. The two-IMU approach showed similar differences for absolute linear wheelchair velocity (MAE 0.10 m/s), and smaller differences for angular velocity (MAE 3.0°/s). Overall, a lower number of IMUs used in the configuration resulted in a lower accuracy of wheelchair kinematics. Based on the results of this study, choices regarding the number of IMUs can be made depending on the aim, required accuracy and resources available.","Accuracy; Inertial measurement unit; Kinematics; Paralympic sports; Wheelchair mobility performance","en","journal article","","","","","","","","","","Biomechanical Engineering","Biomechatronics & Human-Machine Control","","",""
"uuid:08c942fb-aab7-4b19-8948-e3129d005d0c","http://resolver.tudelft.nl/uuid:08c942fb-aab7-4b19-8948-e3129d005d0c","Shoulder kinematics and muscle activity following latissimus dorsi transfer for massive irreparable posterosuperior rotator cuff tears in shoulders with pseudoparalysis","Gurnani, Navin (Spaarne Gasthuis, Hoofddorp); Willems, W. Jaap (DC Expert Centre, Amsterdam); van Deurzen, Derek F.P. (DC Expert Centre, Amsterdam); Weening, Alexander A. (Diakonessehuis Utrecht); Bouwer, Joran (Vrije Universiteit Amsterdam); Janssen, Thomas W.J. (Vrije Universiteit Amsterdam); Veeger, H.E.J. (TU Delft Biomechanical Engineering)","","2022","Background: The aim of this study was to evaluate the thoracohumeral (TH) and glenohumeral (GH) motion with muscle activity after latissimus dorsi transfer (LDT) in a shoulder with a massive irreparable posterosuperior rotator cuff tear (MIRT) and pseudoparalysis compared with the asymptomatic contralateral shoulder (ACS). Methods: We recruited and evaluated 13 patients after LDT in a shoulder with preoperative clinical pseudoparalysis and an MIRT on magnetic resonance imaging, with a minimum follow-up period of 1 year, and with a Hamada stage of 3 or less. Three-dimensional electromagnetic tracking was used to assess shoulder active range of motion in both the LDT shoulder and the ACS. The maximal active elevation of the shoulder (MAES) was assessed and consisted of forward flexion, scapular abduction, and abduction in the coronal plane. Maximal active internal rotation and external rotation were assessed separately. Surface electromyography (EMG) was performed to track activation of the latissimus dorsi (LD) and deltoid muscles during shoulder motion. EMG was scaled to its maximal isometric voluntary contraction recorded in specified strength tests. Results: In MAES, TH motion of the LDT shoulder was not significantly different from that of the ACS (F1,12 = 1.174, P = .300) but the GH contribution was significantly lower in the LDT shoulder for all motions (F1,12 = 11.230, P = .006). External rotation was significantly greater in the ACS (26° ± 10° in LDT shoulder vs. 42° ± 11° in ACS, P < .001). The LD percentage EMG maximum showed no significant difference between the LDT shoulder and ACS during MAES (F1,11 = 0.005, P = .946). During maximal active external rotation of the shoulder, the LDT shoulder showed a higher percentage EMG maximum than the ACS (3.0% ± 2.9% for LDT shoulder vs. 1.2% ± 2.0% for ACS, P = .006). Conclusions: TH motion improved after LDT in an MIRT with pseudoparalysis and was not different from the ACS except for external rotation. However, GH motion was significantly lower after LDT than in the ACS in active-elevation range of motion. The LD was active after LDT but not more than in the ACS except for active external rotation, which we did not consider relevant as the activity did not rise above 3% EMG maximum. The favorable clinical results of LDT do not seem to be related to a change in LD activation and might be explained by its effect in preventing proximal migration of the humeral head in active elevation.","Basic Science Study; electromyography; Kinesiology; Latissimus dorsi; massive rotator cuff tear; muscle transfer; shoulder kinematics; shoulder surgery","en","journal article","","","","","","Green Open Access added to TU Delft Institutional Repository 'You share, we take care!' - Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.","","2023-07-01","","Biomechanical Engineering","","","",""
"uuid:e335b683-9a16-4518-9252-68129bc2ba7c","http://resolver.tudelft.nl/uuid:e335b683-9a16-4518-9252-68129bc2ba7c","Electromyography-driven model-based estimation of ankle torque and stiffness during dynamic joint rotations in perturbed and unperturbed conditions","Cop, Christopher P. (University of Twente); Schouten, A.C. (TU Delft Biomechanical Engineering; University of Twente); Koopman, Bart (University of Twente); Sartori, Massimo (University of Twente)","","2022","The simultaneous modulation of joint torque and stiffness enables humans to perform large repertoires of movements, while versatilely adapting to external mechanical demands. Multi-muscle force control is key for joint torque and stiffness modulation. However, the inability to directly measure muscle force in the intact moving human prevents understanding how muscle force causally links to joint torque and stiffness. Joint stiffness is predominantly estimated via joint perturbation-based experiments in combination with system identification techniques. However, these techniques provide joint-level stiffness estimations with no causal link to the underlying muscle forces. Moreover, the need for joint perturbations limits the generalizability and applicability to study natural movements. Here, we present an electromyography (EMG)-driven musculoskeletal modeling framework that can be calibrated to match reference joint torque and stiffness profiles simultaneously via a multi-term objective function. EMG-driven models calibrated on <2 s of reference torque and stiffness data could blindly estimate reference profiles across 100 s of data not used for calibration. Model calibrations using an objective function comprising torque and stiffness terms always provided less feasible solutions than an objective function comprising solely a torque term, thereby reducing the space of feasible muscle–tendon parameters. Results also showed the proposed framework's ability to estimate joint stiffness in unperturbed conditions, while capturing differences against stiffness profiles derived during perturbed conditions. The proposed framework may provide new ways for studying causal relationships between muscle force and joint torque and stiffness during movements in interaction with the environment, with broad implications across biomechanics, rehabilitation and robotics.","Calibration; Electromyography; Joint stiffness; Musculoskeletal modeling","en","journal article","","","","","","","","","","Biomechanical Engineering","","","",""
"uuid:3da888eb-21d1-4608-973a-d95381225bee","http://resolver.tudelft.nl/uuid:3da888eb-21d1-4608-973a-d95381225bee","Quantification of the development of trunk control in healthy infants using inertial measurement units","Blok, Janneke (Student TU Delft); Poggensee, K. (TU Delft Biomechatronics & Human-Machine Control; Erasmus MC); Lemus Perez, D.S. (TU Delft Biomechatronics & Human-Machine Control; Erasmus MC); Kok, M. (TU Delft Team Manon Kok); Pangalila, Robert F. (Erasmus MC; Rijndam Revalidatie); Vallery, H. (TU Delft Biomechatronics & Human-Machine Control; Erasmus MC); Deferme, Jolien (Rijndam Revalidatie); Toussaint-Duyster, Leontien (Erasmus MC); Horemans, H.L.D. (TU Delft Biomechanical Engineering; Erasmus MC)","","2022","Trunk motor control is essential for the proper functioning of the upper extremities and is an important predictor of gait capacity in children with delayed development. Early diagnosis and intervention could increase the trunk motor capabilities in later life, but current tools used to assess the level of trunk motor control are largely subjective and many lack the sensitivity to accurately monitor development and the effects of therapy. Inertial measurement units could yield an objective quantitative assessment that is inexpensive and easy-to-implement. We hypothesized that root mean square of jerk, a proxy for movement smoothness, could be used to distinguish age and thereby presumed motor development. We attached a sensor to the trunks of six young children with no known developmental deficits. Root mean square of jerk decreases with age, up to 24 months, and is correlated to a more established method, i.e., center-of-pressure velocity, as well as other standard inertial measurement unit outputs. This metric therefore shows potential as a method to differentiate trunk motor control levels.","Motor drives; Pediatrics; Measurement units; Sensitivity; Medical treatment; Inertial navigation; Robot sensing systems","en","conference paper","IEEE","","","","","Green Open Access added to TU Delft Institutional Repository 'You share, we take care!' - Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.","","2023-03-28","","Biomechanical Engineering","Biomechatronics & Human-Machine Control","","",""
"uuid:0b1c5dfa-d24f-4688-b867-54c230c04a23","http://resolver.tudelft.nl/uuid:0b1c5dfa-d24f-4688-b867-54c230c04a23","Feasibility and validity of a single camera CNN driven musculoskeletal model for muscle force estimation during upper extremity strength exercises: Proof-of-concept","Noteboom, L. (Vrije Universiteit Amsterdam); Hoozemans, Marco J.M. (Vrije Universiteit Amsterdam); Veeger, H.E.J. (TU Delft Biomechanical Engineering); van der Helm, F.C.T. (TU Delft Biomechatronics & Human-Machine Control)","","2022","Muscle force analysis can be essential for injury risk estimation and performance enhancement in sports like strength training. However, current methods to record muscle forces including electromyography or marker-based measurements combined with a musculoskeletal model are time-consuming and restrict the athlete's natural movement due to equipment attachment. Therefore, the feasibility and validity of a more applicable method, requiring only a single standard camera for the recordings, combined with a deep-learning model and musculoskeletal model is evaluated in the present study during upper-body strength exercises performed by five athletes. Comparison of muscle forces obtained by the single camera driven model against those obtained from a state-of-the art marker-based driven musculoskeletal model revealed strong to excellent correlations and reasonable RMSD's of 0.4–2.1% of the maximum force (Fmax) for prime movers, and weak to strong correlations with RMSD's of 0.4–0.7% Fmax for stabilizing and secondary muscles. In conclusion, a single camera deep-learning driven model is a feasible method for muscle force analysis in a strength training environment, and first validity results show reasonable accuracies, especially for prime mover muscle forces. However, it is evident that future research should investigate this method for a larger sample size and for multiple exercises.","artificial intelligence; fitness; markerless motion capture; musculoskeletal modeling; strength training; video-based motion capture","en","journal article","","","","","","","","","","Biomechanical Engineering","Biomechatronics & Human-Machine Control","","",""
"uuid:70fb29ee-28bb-4478-b2bd-5589db614e30","http://resolver.tudelft.nl/uuid:70fb29ee-28bb-4478-b2bd-5589db614e30","Fastball pitching performance only slightly decreases after mobility impediment of the pelvis and trunk—Do (catch-up) compensation strategies come into play?","Leenen, A.J.R. (Vrije Universiteit Amsterdam); van Trigt, B. (TU Delft Biomechanical Engineering); Hoozemans, M. J.M. (Vrije Universiteit Amsterdam); Veeger, H.E.J. (TU Delft Biomechatronics & Human-Machine Control)","","2022","Background: Baseball pitching performance can be mechanically explained by the summation of speed principle and the principle of optimal coordination of partial momenta. Impeding optimal energy generation or transfer by or between the pelvis and trunk segments could provide valuable insight into possible compensation or catch-up mechanisms that may manifest themselves based on these principles. Aim: The aim of the present study was to explore the effects of experimentally impeding the mobility of and between the pelvis and trunk segments (1) on ball speed and mechanical peak joint power, and (2) on mechanical peak load of the elbow and shoulder joints at maximal external rotation (MER) during fastball pitching. Methods: Eleven elite baseball pitchers (mean age 17.4, SD 2.2 years; mean pitching experience 8.9, SD 3.0 years) were instructed to throw at least 15 fastballs as fast and accurately as possible under two conditions. One condition involved impeding the mobility of the pelvis and trunk segments to hamper their ability to rotate independently, which consequently should affect the separation time, defined as the time interval between the pelvis and trunk peak angular velocities. In the other condition, pitchers threw unimpeded. Ball speed, mechanical peak joint power and peak net moment of the elbow and shoulder at MER were compared between conditions using Generalized Estimating Equations (GEE). Results: In the impeded pitching condition, the mean difference of the separation time was 12.4 milliseconds [95% CI (4.0, 20.7)] and for ball speed 0.6 mph [95% CI (0.2, 0.9)] lower compared to the unimpeded condition. Only the peak pelvic angular velocity, in addition to the trunk, upper arm and forearm, was 45 deg/s [95% CI (24, 66)] higher impeded condition. The mean differences of the joint power and net moments at the shoulder and elbow did not reach statistical significance. Conclusion: In elite adolescent baseball, the observed pitching performance after experimentally impeding pelvic and trunk mobility undermines a potential distal catch-up strategy based on the summation of speed principle. The increased peak pelvic angular velocity may indicate a compensation strategy following the optimal coordination of partial momenta principle to practically maintain pitching performance.","baseball; biomechanics; catch-up phenomenon; elbow; injury; kinematic chain; performance; shoulder","en","journal article","","","","","","","","","","Biomechanical Engineering","Biomechatronics & Human-Machine Control","","",""
"uuid:d03df0fc-77e6-4a2d-9395-8f2cf3cc6ebd","http://resolver.tudelft.nl/uuid:d03df0fc-77e6-4a2d-9395-8f2cf3cc6ebd","Individualised Ball Speed Prediction in Baseball Pitching Based on IMU Data","Gomaz, L. (TU Delft Statistics; TU Delft Biomechanical Engineering); Veeger, H.E.J. (TU Delft Biomechanical Engineering); van der Graaff, E. (Vrije Universiteit Amsterdam); van Trigt, B. (TU Delft Biomechanical Engineering; Vrije Universiteit Amsterdam); van der Meulen, F.H. (TU Delft Statistics)","","2021","Ball velocity is considered an important performance measure in baseball pitching. Proper pitching mechanics play an important role in both maximising ball velocity and injury-free participation of baseball pitchers. However, an individual pitcher’s characteristics display individuality and may contribute to velocity imparted to the ball. The aim of this study is to predict ball velocity in baseball pitching, such that prediction is tailored to the individual pitcher, and to investigate the added value of the individuality to predictive performance. Twenty-five youth baseball pitchers, members of a national youth baseball team and six baseball academies in The Netherlands, performed ten baseball pitches with maximal effort. The angular velocity of pelvis and trunk were measured with IMU sensors placed on pelvis and sternum, while the ball velocity was measured with a radar gun. We develop three Bayesian regression models with different predictors which were subsequently evaluated based on predictive performance. We found that pitcher’s height adds value to ball velocity prediction based on body segment rotation. The developed method provides a feasible and affordable method for ball velocity prediction in baseball pitching","ball velocity; inertial measurement unit; multilevel modeling; pitching; baseball","en","journal article","","","","","","","","","","Biomechanical Engineering","Statistics","","",""
"uuid:9778f3fc-363a-47e9-a2d5-aeb5b8a9c1f7","http://resolver.tudelft.nl/uuid:9778f3fc-363a-47e9-a2d5-aeb5b8a9c1f7","Establishing the Role of Elbow Muscles by Evaluating Muscle Activation and Co-contraction Levels at Maximal External Rotation in Fastball Pitching","van Trigt, B. (TU Delft Biomechanical Engineering); Galjee, E.N. (Student TU Delft); Hoozemans, Marco J.M. (Vrije Universiteit Amsterdam); van der Helm, F.C.T. (TU Delft Biomechatronics & Human-Machine Control); Veeger, H.E.J. (TU Delft Biomechanical Engineering)","","2021","Background: Baseball pitching is associated with a high prevalence of ulnar collateral ligament injuries, potentially due to the high external valgus load on the medial side of the elbow at the instant of maximal shoulder external rotation (MER). In-vitro studies show that external valgus torque is resisted by the ulnar collateral ligament but could also be compensated by elbow muscles. As the potential active contribution of these muscles in counteracting external valgus load during baseball pitching is unknown, the aim of this study is to determine whether and to what extent the elbow muscles are active at and around MER during a fastball pitch in baseball.
Methods: Eleven uninjured pitchers threw 15 fastball pitches. Surface electromyography of six muscles crossing the elbow were measured at 2000 Hz. Electromyography signals were normalized to maximal activity values. Co-contraction index (CCI) was calculated between two pairs of the flexor and extensor elbow muscles. Confidence intervals were calculated at the instant of MER. Four ranges of muscle activity were considered; 0–20% was considered low; 21–40% moderate; 41–60% high and over 60% as very high. To determine MER, the pitching motion was captured with a highspeed camera at 240 Hz.
Results: The flexor pronator mass, pronator teres, triceps brachii, biceps brachii, extensor supinator mass and anconeus show moderate activity at MER. Considerable variation between participants was found in all muscles. The CCI revealed co-contraction of the two flexor-extensor muscle pairs at MER.
Interpretation: The muscle activation of the flexor and pronator muscles at MER indicates a direct contribution of forearm muscles crossing the medial side of the elbow in counteracting the external valgus load during fastball pitching. The activation of both flexor and extensor muscles indicates an in-direct contributory effect as the combined activity of these muscles counteract opening of the humeroulnar joint space. We believe that active muscular contributions counteracting the elbow valgus torque can be presumed to relieve the ulnar collateral ligament from maximal stress and are thus of importance in injury risk assessment in fastball pitching in baseball.","electromyography; musculoskeletal injuries; Tommy John surgery; overhead sports; ulnar collateral ligament (UCL); injury prevention; baseball","en","journal article","","","","","","","","","","Biomechanical Engineering","Biomechatronics & Human-Machine Control","","",""
"uuid:d7484e8e-2262-4e93-be31-0864ff2b5f0b","http://resolver.tudelft.nl/uuid:d7484e8e-2262-4e93-be31-0864ff2b5f0b","The influence of the exclusion of central necrosis on [18F]FDG PET radiomic analysis","Noortman, Wyanne A. (Leiden University Medical Center; University of Twente); Vriens, Dennis (Leiden University Medical Center); Mooij, C.D.Y. (TU Delft Biomechanical Engineering; Leiden University Medical Center); Slump, Cornelis H. (University of Twente); Aarntzen, Erik H. (Radboud University Medical Center); van Berkel, Anouk (Radboud University Medical Center); Timmers, Henri J.L.M. (Radboud University Medical Center); Bussink, Johan (Radboud University Medical Center); Meijer, Tineke W.H. (University Medical Center Groningen); de Geus-Oei, Lioe Fee (Leiden University Medical Center; University of Twente); van Velden, Floris H.P. (Leiden University Medical Center)","","2021","Background: Central necrosis can be detected on [18F]FDG PET/CT as a region with little to no tracer uptake. Currently, there is no consensus regarding the inclusion of regions of central necrosis during volume of interest (VOI) delineation for radiomic analysis. The aim of this study was to assess how central necrosis affects radiomic analysis in PET. Methods: Forty-three patients, either with non-small cell lung carcinomas (NSCLC, n = 12) or with pheochromocytomas or paragangliomas (PPGL, n = 31), were included retrospectively. VOIs were delineated with and without central necrosis. From all VOIs, 105 radiomic features were extracted. Differences in radiomic features between delineation methods were assessed using a paired t-test with Benjamini-Hochberg multiple testing correction. In the PPGL cohort, performances of the radiomic models to predict the noradrenergic biochemical profile were assessed by comparing the areas under the receiver operating characteristic curve (AUC) for both delineation methods. Results: At least 65% of the features showed significant differences between VOIvital-tumour and VOIgross-tumour (65%, 79% and 82% for the NSCLC, PPGL and combined cohort, respectively). The AUCs of the radiomic models were not significantly different between delineation methods. Conclusion: In both tumour types, almost two-third of the features were affected, demonstrating that the impact of whether or not to include central necrosis in the VOI on the radiomic feature values is significant. Nevertheless, predictive performances of both delineation methods were comparable. We recommend that radiomic studies should report whether or not central necrosis was included during delineation.","Central necrosis; Radiomics; Tumour delineation; [F]FDG PET/CT","en","journal article","","","","","","","","","","Biomechanical Engineering","","","",""
"uuid:de7e37f8-4476-498f-80ab-7cb2e79c8743","http://resolver.tudelft.nl/uuid:de7e37f8-4476-498f-80ab-7cb2e79c8743","Theta but not beta power is positively associated with better explicit motor task learning","van der Cruijsen, J. (Erasmus MC); Manoochehri, M. (TU Delft Biomechatronics & Human-Machine Control); Jonker, Z.D. (TU Delft Biomechanical Engineering; Erasmus MC); Andrinopoulou, Eleni Rosalina (Erasmus MC); Frens, Maarten A. (Erasmus MC); Ribbers, G.M. (Erasmus MC; Rijndam Rehabilitation Center); Schouten, A.C. (TU Delft Biomechatronics & Human-Machine Control; University of Twente); Selles, R.W. (Erasmus MC)","","2021","Neurophysiologic correlates of motor learning that can be monitored during neurorehabilitation interventions can facilitate the development of more effective learning methods. Previous studies have focused on the role of the beta band (14–30 Hz) because of its clear response during motor activity. However, it is difficult to discriminate between beta activity related to learning a movement and performing the movement. In this study, we analysed differences in the electroencephalography (EEG) power spectra of complex and simple explicit sequential motor tasks in healthy young subjects. The complex motor task (CMT) allowed EEG measurement related to motor learning. In contrast, the simple motor task (SMT) made it possible to control for EEG activity associated with performing the movement without significant motor learning. Source reconstruction of the EEG revealed task-related activity from 5 clusters covering both primary motor cortices (M1) and 3 clusters localised to different parts of the cingulate cortex (CC). We found no association between M1 beta power and learning, but the CMT produced stronger bilateral beta suppression compared to the SMT. However, there was a positive association between contralateral M1 theta (5–8 Hz) and alpha (8–12 Hz) power and motor learning, and theta and alpha power in the posterior mid-CC and posterior CC were positively associated with greater motor learning. These findings suggest that the theta and alpha bands are more related to motor learning than the beta band, which might merely relate to the level of perceived difficulty during learning.","EEG; Independent component analysis; Motor learning","en","journal article","","","","","","","","","","Biomechanical Engineering","Biomechatronics & Human-Machine Control","","",""
"uuid:a612989e-a07e-44c6-811f-627362c4a3a2","http://resolver.tudelft.nl/uuid:a612989e-a07e-44c6-811f-627362c4a3a2","Progression along data-driven disease timelines is predictive of Alzheimer's disease in a population-based cohort","Venkatraghavan, Vikram (Erasmus MC); Vinke, Elisabeth J. (Erasmus MC); Bron, Esther E. (Erasmus MC); Niessen, W.J. (TU Delft ImPhys/Computational Imaging; TU Delft ImPhys/Medical Imaging; Erasmus MC); Arfan Ikram, M. (Erasmus MC); Klein, S. (TU Delft Biomechanical Engineering; Erasmus MC); Vernooij, Meike W. (Erasmus MC)","","2021","Data-driven disease progression models have provided important insight into the timeline of brain changes in AD phenotypes. However, their utility in predicting the progression of pre-symptomatic AD in a population-based setting has not yet been investigated. In this study, we investigated if the disease timelines constructed in a case-controlled setting, with subjects stratified according to APOE status, are generalizable to a population-based cohort, and if progression along these disease timelines is predictive of AD. Seven volumetric biomarkers derived from structural MRI were considered. We estimated APOE-specific disease timelines of changes in these biomarkers using a recently proposed method called co-initialized discriminative event-based modeling (co-init DEBM). This method can also estimate a disease stage for new subjects by calculating their position along the disease timelines. The model was trained and cross-validated on the Alzheimer's Disease Neuroimaging Initiative (ADNI) dataset, and tested on the population-based Rotterdam Study (RS) cohort. We compared the diagnostic and prognostic value of the disease stage in the two cohorts. Furthermore, we investigated if the rate of change of disease stage in RS participants with longitudinal MRI data was predictive of AD. In ADNI, the estimated disease timeslines for ϵ4 non-carriers and carriers were found to be significantly different from one another (p<0.001). The estimate disease stage along the respective timelines distinguished AD subjects from controls with an AUC of 0.83 in both APOE ϵ4 non-carriers and carriers. In the RS cohort, we obtained an AUC of 0.83 and 0.85 in ϵ4 non-carriers and carriers, respectively. Progression along the disease timelines as estimated by the rate of change of disease stage showed a significant difference (p<0.005) for subjects with pre-symptomatic AD as compared to the general aging population in RS. It distinguished pre-symptomatic AD subjects with an AUC of 0.81 in APOE ϵ4 non-carriers and 0.88 in carriers, which was better than any individual volumetric biomarker, or its rate of change, could achieve. Our results suggest that co-init DEBM trained on case-controlled data is generalizable to a population-based cohort setting and that progression along the disease timelines is predictive of the development of AD in the general population. We expect that this approach can help to identify at-risk individuals from the general population for targeted clinical trials as well as to provide biomarker based objective assessment in such trials.","Alzheimer's disease; APOE; Disease progression modeling; Event-based model; Population study","en","journal article","","","","","","","","","","Biomechanical Engineering","ImPhys/Computational Imaging","","",""
"uuid:9b28ccc9-ce7f-4a9d-a883-a519f2166cbc","http://resolver.tudelft.nl/uuid:9b28ccc9-ce7f-4a9d-a883-a519f2166cbc","Machine Learning to Improve Orientation Estimation in Sports Situations Challenging for Inertial Sensor Use","van Dijk, M.P. (TU Delft Biomechanical Engineering; Vrije Universiteit Amsterdam); Kok, M. (TU Delft Team Manon Kok); Berger, Monique A.M. (The Hague University of Applied Sciences); Hoozemans, Marco J.M. (Vrije Universiteit Amsterdam); Veeger, H.E.J. (TU Delft Biomechanical Engineering)","","2021","In sports, inertial measurement units are often used to measure the orientation of human body segments. A Madgwick (MW) filter can be used to obtain accurate inertial measurement unit (IMU) orientation estimates. This filter combines two different orientation estimates by applying a correction of the (1) gyroscope-based estimate in the direction of the (2) earth frame-based estimate. However, in sports situations that are characterized by relatively large linear accelerations and/or close magnetic sources, such as wheelchair sports, obtaining accurate IMU orientation estimates is challenging. In these situations, applying the MW filter in the regular way, i.e., with the same magnitude of correction at all time frames, may lead to estimation errors. Therefore, in this study, the MW filter was extended with machine learning to distinguish instances in which a small correction magnitude is beneficial from instances in which a large correction magnitude is beneficial, to eventually arrive at accurate body segment orientations in IMU-challenging sports situations. A machine learning algorithm was trained to make this distinction based on raw IMU data. Experiments on wheelchair sports were performed to assess the validity of the extended MW filter, and to compare the extended MW filter with the original MW filter based on comparisons with a motion capture-based reference system. Results indicate that the extended MW filter performs better than the original MW filter in assessing instantaneous trunk inclination (7.6 vs. 11.7° root-mean-squared error, RMSE), especially during the dynamic, IMU-challenging situations with moving athlete and wheelchair. Improvements of up to 45% RMSE were obtained for the extended MW filter compared with the original MW filter. To conclude, the machine learning-based extended MW filter has an acceptable accuracy and performs better than the original MW filter for the assessment of body segment orientation in IMU-challenging sports situations.","inertial measurement unit; kinematics; machine learning; madgwick filter; orientation estimation; sports","en","journal article","","","","","","","","","","Biomechanical Engineering","Team Manon Kok","","",""
"uuid:70c66d02-9aca-4ef3-9e8f-a3a90ae49f62","http://resolver.tudelft.nl/uuid:70c66d02-9aca-4ef3-9e8f-a3a90ae49f62","Fixation effects of different types of cannulated screws on vertical femoral neck fracture: A finite element analysis and experimental study","Zhan, Shi (Shanghai Jiao Tong University); Jiang, Dajun (Shanghai Jiao Tong University); Ling, Ming (Shanghai Jiao Tong University); Ding, Jian (Shanghai Jiao Tong University); Yang, Kai (Shanghai Jiao Tong University); Duan, Lei (Shanghai Jiao Tong University); Tsai, Tsung Yuan (Shanghai Jiao Tong University); Feng, Yong (Shanghai Jiao Tong University); van Trigt, B. (TU Delft Biomechanical Engineering); Jia, Weitao (Shanghai Jiao Tong University); Zhang, Changqing (Shanghai Jiao Tong University); Hu, Hai (Shanghai Jiao Tong University)","","2021","Femoral neck fractures (FNFs) in young patients usually result from high-energy violence, and the vertical transcervical type is typically challenging for its instability. FNFs are commonly treated with three cannulated screws (CS), but the role of screws type on fixation effects (FE) is unclear. The purpose of this study was to evaluate the FE of ten types of CS with different diameters, lengths, depths, and pitches of thread via finite element analysis which was validated by a biomechanical test. Ten vertical FNF models were grouped, fixed by ten types of CS, respectively, all in a parallel, inverted triangular configuration. Their FE were scored comprehensively from six aspects via an entropy evaluation method, as higher scores showed better results. For partial-thread screws, thread length and thread shape factor (TSF) are determinative factors on stability of FNF only if thread depth is not too thick, and they have less cut-out risk, better compression effects and better detached resistance of fracture than full-thread screws, whereas full-thread screws appear to have better shear and shortening resistance. A combination of two superior partial-thread screws and one inferior full-thread screw for vertical FNF may get optimal biomechanical outcomes. The type of cannulated screw is important to consider when treating vertical FNF.","Biomechanics; Finite element analysis; Types of screws; Vertical femoral neck fracture","en","journal article","","","","","","Accepted Author Manuscript","","2022-10-06","","Biomechanical Engineering","","","",""
"uuid:30a4327c-4d3c-4187-b92f-d9991ba7fc67","http://resolver.tudelft.nl/uuid:30a4327c-4d3c-4187-b92f-d9991ba7fc67","Quantifying neural and non-neural components of wrist hyper-resistance after stroke: Comparing two instrumented assessment methods","Andringa, Aukje (Vrije Universiteit Amsterdam); Meskers, Carel (Vrije Universiteit Amsterdam; Northwestern University; Amsterdam Rehabilitation Research Center Reade); van de Port, Ingrid (Revant Rehabilitation Center); Zandvliet, Sarah (Vrije Universiteit Amsterdam); Scholte, Larissa (Vrije Universiteit Amsterdam; Student TU Delft); de Groot, J.H. (TU Delft Biomechanical Engineering; Leiden University Medical Center); Kwakkel, Gert (Vrije Universiteit Amsterdam; Northwestern University; Amsterdam Rehabilitation Research Center Reade); van Wegen, Erwin (Vrije Universiteit Amsterdam)","","2021","Patients with poor upper limb motor recovery after stroke are likely to develop increased resistance to passive wrist extension, i.e., wrist hyper-resistance. Quantification of the underlying neural and non-neural elastic components is of clinical interest. This cross-sectional study compared two methods: a commercially available device (NeuroFlexor®) with an experimental EMG-based device (Wristalyzer) in 43 patients with chronic stroke. Spearman's rank correlation coefficients (r) between components, modified Ashworth scale (MAS) and range of passive wrist extension (PRoM) were calculated with 95% confidence intervals. Neural as well as elastic components assessed by both devices were associated (r = 0.61, 95%CI: 0.38-0.77 and r = 0.53, 95%CI: 0.28–0.72, respectively). The neural component assessed by the NeuroFlexor® associated significantly with the elastic components of NeuroFlexor® (r = 0.46, 95%CI: 0.18–0.67) and Wristalyzer (r = 0.36, 95%CI: 0.06–0.59). The neural component assessed by the Wristalyzer was not associated with the elastic components of both devices. Neural and elastic components of both devices associated similarly with the MAS (r = 0.58, 95%CI: 0.34–0.75 vs. 0.49, 95%CI: 0.22–0.69 and r = 0.51, 95%CI: 0.25–0.70 vs. 0.30, 95%CI: 0.00–0.55); elastic components associated with PRoM (r = -0.44, 95%CI: -0.65- -0.16 vs. -0.74, 95%CI: -0.85- -0.57 for NeuroFlexor® and Wristalyzer respectively). Results demonstrate that both methods perform similarly regarding the quantification of neural and elastic wrist hyper-resistance components and have an added value when compared to clinical assessment with the MAS alone. The added value of EMG in the discrimination between neural and non-neural components requires further investigation.","Assessment; Hyper-resistance; Muscle spasticity; Stroke; Upper extremity; Validity","en","journal article","","","","","","","","","","Biomechanical Engineering","","","",""
"uuid:11f6a1ac-899f-4f3f-b2a9-2f1a48be1327","http://resolver.tudelft.nl/uuid:11f6a1ac-899f-4f3f-b2a9-2f1a48be1327","The ulnar collateral ligament loading paradox between in-vitro and in-vivo studies on baseball pitching (narrative review)","van Trigt, B. (TU Delft Biomechanical Engineering); Vliegen, Liset (Student TU Delft); Leenen, Ton (Vrije Universiteit Amsterdam); Veeger, H.E.J. (TU Delft Biomechanical Engineering)","","2021","Ulnar collateral ligament (UCL) weakening or tears occur in 16% of professional baseball pitchers. To prevent players from sustaining a UCL injury, it is important to understand the relationship between the UCL properties and elbow stabilizers with the load on the UCL during pitching. In-vitro studies showed that the ultimate external valgus torque of 34 Nm would rupture the UCL, which is in apparent conflict with the reported peak valgus torques in pitching (40–120 Nm). Assuming both observations are correct, the question rises why ‘only’ 16 out of 100 professional pitchers sustain a UCL rupture. Underestimation of the effect of other structures in in-vivo studies is most likely the explanation of this mismatch because the calculated in-vivo torque also includes possible contributions of functional and structural stabilizers. In-vitro studies show that the flexor-pronator mass has the potential to counteract valgus torque directly, whereas the elbow flexor-extensor muscles combined with the humeroradial joint might have an indirect effect on valgus torque by increasing the joint compression force. Accurate experimental electromyography data and a more detailed (musculoskeletal)mechanical model of the elbow are needed to investigate if and to what extent the structural and functional stabilizers can shield the UCL during pitching.","elbow injury; electromyography; Tommy John Surgery;; musculoskeletal modelling; overhead sports; UCL; OA-Fund TU Delft","en","review","","","","","","","","","","Biomechanical Engineering","","","",""
"uuid:153ad0ce-e040-4945-90e5-9c99b4073494","http://resolver.tudelft.nl/uuid:153ad0ce-e040-4945-90e5-9c99b4073494","Digital biomarkers and algorithms for detection of atrial fibrillation using surface electrocardiograms: A systematic review: Digital Biomarkers for AF in Surface ECGs","Wesselius, F.J. (TU Delft Biomechanical Engineering; Erasmus MC); van Schie, M.S. (TU Delft Biomechanical Engineering; Erasmus MC); de Groot, N.M.S. (TU Delft Signal Processing Systems; TU Delft Biomechanical Engineering; Erasmus MC); Hendriks, R.C. (TU Delft Signal Processing Systems)","","2021","Aims: Automated detection of atrial fibrillation (AF) in continuous rhythm registrations is essential in order to prevent complications and optimize treatment of AF. Many algorithms have been developed to detect AF in surface electrocardiograms (ECGs) during the past few years. The aim of this systematic review is to gain more insight into these available classification methods by discussing previously used digital biomarkers and algorithms and make recommendations for future research. Methods: On the 14th of September 2020, the PubMed database was searched for articles focusing on algorithms for AF detection in ECGs using the MeSH terms Atrial Fibrillation, Electrocardiography and Algorithms. Articles which solely focused on differentiation of types of rhythm disorders or prediction of AF termination were excluded. Results: The search resulted in 451 articles, of which 130 remained after full-text screening. Not only did the amount of research on methods for AF detection increase over the past years, but a trend towards more complex classification methods is observed. Furthermore, three different types of features can be distinguished: atrial features, ventricular features, and signal features. Although AF is an atrial disease, only 22% of the described methods use atrial features. Conclusion: More and more studies focus on improving accuracy of classification methods for AF in ECGs. As a result, algorithms become increasingly complex and less well interpretable. Only a few studies focus on detecting atrial activity in the ECG. Developing innovative methods focusing on detection of atrial activity might provide accurate classifiers without compromising on transparency.","Algorithms; Atrial fibrillation; Classification; ECG signal Processing; Machine learning; Telemetry","en","review","","","","","","","","","","Biomechanical Engineering","Signal Processing Systems","","",""
"uuid:d5b4a20d-bd1d-4eba-a41f-50fdd21cac7c","http://resolver.tudelft.nl/uuid:d5b4a20d-bd1d-4eba-a41f-50fdd21cac7c","Graph-time spectral analysis for atrial fibrillation","Sun, M. (TU Delft Signal Processing Systems); Isufi, E. (TU Delft Multimedia Computing); de Groot, N.M.S. (TU Delft Biomechanical Engineering; Erasmus MC); Hendriks, R.C. (TU Delft Signal Processing Systems)","","2020","Atrial fibrillation is a clinical arrhythmia with multifactorial mechanisms still unresolved. Time-frequency analysis of epicardial electrograms has been investigated to study atrial fibrillation. However, deeper understanding can be achieved by incorporating the spatial dimension. Unfortunately, the physical models describing the spatial relations of atrial fibrillation signals are complex and non-linear; hence, conventional signal processing techniques to study electrograms in the joint space, time, and frequency domain are less suitable. In this study, we wish to put forward a radically different approach to analyze atrial fibrillation with a higher-level model. This approach relies on graph signal processing to represent the spatial relations between epicardial electrograms. To capture the frequency content along both the time and graph domain, we propose the joint graph and short-time Fourier transform. The latter allows us to analyze the spatial variability of the electrogram temporal frequencies. With this technique, we found the spatial variation of the atrial electrograms decreases during atrial fibrillation since the high temporal frequencies of the atrial waves reduce. The proposed analysis further confirms that the ventricular activity is smoother over the atrial area compared with the atrial activity. Besides using the proposed graph-time analysis to conduct a first study on atrial fibrillation, we demonstrate its potential by applying it to the cancellation of ventricular activity from the atrial electrograms. Experimental results on simulated and real data further corroborate our findings in this atrial fibrillation study.","Atrial activity extraction; Atrial fibrillation; Graph signal processing; Graph-time signal processing; Spectral analysis","en","journal article","","","","","","","","2022-03-06","","Biomechanical Engineering","Signal Processing Systems","","",""
"uuid:5002c245-78a1-40b4-a285-66a245bc195d","http://resolver.tudelft.nl/uuid:5002c245-78a1-40b4-a285-66a245bc195d","Wearable Wheelchair Mobility Performance Measurement in Basketball, Rugby, and Tennis: Lessons for classification and training","van der Slikke, R.M.A. (The Hague University of Applied Sciences); Berger, Monique A.M. (The Hague University of Applied Sciences); Bregman, D.J.J. (TU Delft Research Funding National); Veeger, H.E.J. (TU Delft Biomechanical Engineering; Vrije Universiteit Amsterdam)","","2020","Athlete impairment level is an important factor in wheelchair mobility performance (WMP) in sports. Classification systems, aimed to compensate impairment level effects on performance, vary between sports. Improved understanding of resemblances and differences in WMP between sports could aid in optimizing the classification methodology. Furthermore, increased performance insight could be applied in training and wheelchair optimization. The wearable sensor-based wheelchair mobility performance monitor (WMPM) was used to measure WMP of wheelchair basketball, rugby and tennis athletes of (inter-)national level during match-play. As hypothesized, wheelchair basketball athletes show the highest average WMP levels and wheelchair rugby the lowest, whereas wheelchair tennis athletes range in between for most outcomes. Based on WMP profiles, wheelchair basketball requires the highest performance intensity, whereas in wheelchair tennis, maneuverability is the key performance factor. In wheelchair rugby, WMP levels show the highest variation comparable to the high variation in athletes’ impairment levels. These insights could be used to direct classification and training guidelines, with more emphasis on intensity for wheelchair basketball, focus on maneuverability for wheelchair tennis and impairment-level based training programs for wheelchair rugby. Wearable technology use seems a prerequisite for further development of wheelchair sports, on the sports level (classification) and on individual level (training and wheelchair configuration).","wheelchair mobility performance; evidence-based classification; wearables; wheelchair sports","en","journal article","","","","","","","","","","Biomechanical Engineering","Research Funding National","","",""
"uuid:4b4457d4-631e-4531-8c48-eef2e01bf86d","http://resolver.tudelft.nl/uuid:4b4457d4-631e-4531-8c48-eef2e01bf86d","Effects of seat height, wheelchair mass and additional grip on a field-based wheelchair basketball mobility performance test","De Witte, A. M.H. (The Hague University of Applied Sciences; Vrije Universiteit Amsterdam); van der Slikke, R.M.A. (TU Delft Biomechatronics & Human-Machine Control; The Hague University of Applied Sciences); Berger, M. A.M. (The Hague University of Applied Sciences); Hoozemans, M. J.M. (Vrije Universiteit Amsterdam); Veeger, H.E.J. (TU Delft Biomechanical Engineering; Vrije Universiteit Amsterdam); Van Der Woude, L. H.V. (University Medical Center Groningen)","","2020","OBJECTIVE: The purpose of this study was to determine the effects of seat height, wheelchair mass and grip on mobility performance among wheelchair basketball players and to investigate whether these effects differ between classification levels. METHODS: Elite wheelchair basketball players with a low (n= 11, class 1 or 1.5) or high (n= 10, class 4 or 4.5) classification performed a field-based wheelchair mobility performance (WMP) test. Athletes performed the test six times in their own wheelchair, of which five times with different configurations, a higher or lower seat height, with additional distally or centrally located extra mass, and with gloves. The effects of these configurations on performance times and the interaction with classification were determined. RESULTS: Total performance time on the WMP test was significantly reduced when using a 7.5% lower seat height. Additional mass (7.5%) and glove use did not lead to changes in performance time. Effects were the same for the two classification levels. CONCLUSIONS: The methodology can be used in a wheelchair fitting process to search for the optimal individual configuration to enhance mobility performance. Out of all adjustments possible, this study focused on seat height, mass and grip only. Further research can focus on these possible adjustments to optimize mobility performance in wheelchair basketball.","Classification; Paralympic; Wheelchair basketball; Wheelchair configuration; Wheelchair mobility performance","en","journal article","","","","","","Accepted Author Manuscript","","","","Biomechanical Engineering","Biomechatronics & Human-Machine Control","","",""
"uuid:bca6aa02-505b-4b2f-83a7-23a71a5b0755","http://resolver.tudelft.nl/uuid:bca6aa02-505b-4b2f-83a7-23a71a5b0755","Technical note: a novel servo-driven dual-roller handrim wheelchair ergometer","De Klerk, R. (University Medical Center Groningen); Vegter, R. J.K. (University Medical Center Groningen); Veeger, H.E.J. (TU Delft Biomechanical Engineering; Vrije Universiteit Amsterdam); van der Woude, L.H.V. (University Medical Center Groningen)","","2020","The measurement of handrim wheelchair propulsion characteristics and performance in the field is complicated due to the non-stationary nature of wheelchair driving. In contrast, the laboratory provides a constrained and standardisable environment to conduct measurements and experiments. Apart from wheelchair treadmills, dynamometers or ergometers for handrim wheelchairs are often custom-made, one-of-a-kind, expensive, and sparsely documented in the research literature. To facilitate standardised and comparable lab-based measurements in research, as well as in clinical settings and adapted sports, a new wheelchair ergometer was developed. The ergometer with instrumented dual rollers allows for the performance analysis of individuals in their personal handrim wheelchair and facilitates capacity assessment, training and skill acquisition in rehabilitation or adapted sports. The ergometer contains two servomotors, one for each rear wheel roller, that allow for the simulation of translational inertia and resistive forces as encountered during wheelchair propulsion based on force input and a simple mechanical model of wheelchair propulsion. A load cell configuration for left and right roller enables the measurement of effective user-generated torque and force on the handrim and the concomitant timing patterns. Preliminary results are discussed.","Dynamometer; Ergometry; Biomechanics; Power output; Wheelchair training","en","journal article","","","","","","Accepted Author Manuscript","","","","Biomechanical Engineering","","","",""
"uuid:87601938-083d-4c20-a539-583d3b171d71","http://resolver.tudelft.nl/uuid:87601938-083d-4c20-a539-583d3b171d71","Determining and Controlling External Power Output During Regular Handrim Wheelchair Propulsion","De Klerk, Rick (University Medical Center Groningen); Vegter, Riemer J.K. (University Medical Center Groningen); Leving, Marika T. (University Medical Center Groningen); de Groot, Sonja (University Medical Center Groningen; Amsterdam Rehabilitation Research Center Reade); Veeger, H.E.J. (TU Delft Biomechanical Engineering; Vrije Universiteit Amsterdam); van der Woude, Lucas H.V. (University Medical Center Groningen)","","2020","The use of a manual wheelchair is critical to 1% of the world's population. Human powered wheeled mobility research has considerably matured, which has led to improved research techniques becoming available over the last decades. To increase the understanding of wheeled mobility performance, monitoring, training, skill acquisition, and optimization of the wheelchair-user interface in rehabilitation, daily life, and sports, further standardization of measurement set-ups and analyses is required. A crucial stepping-stone is the accurate measurement and standardization of external power output (measured in Watts), which is pivotal for the interpretation and comparison of experiments aiming to improve rehabilitation practice, activities of daily living, and adaptive sports. The different methodologies and advantages of accurate power output determination during overground, treadmill, and ergometer-based testing are presented and discussed in detail. Overground propulsion provides the most externally valid mode for testing, but standardization can be troublesome. Treadmill propulsion is mechanically similar to overground propulsion, but turning and accelerating is not possible. An ergometer is the most constrained and standardization is relatively easy. The goal is to stimulate good practice and standardization to facilitate the further development of theory and its application among research facilities and applied clinical and sports sciences around the world.","wheelchairs; propulsion technique; motor skills; efficiency; ergonomics; ergometry; biomechanical phenomena; medicine","en","journal article","","","","","","","","","","Biomechanical Engineering","","","",""
"uuid:3ebe8d4a-1b7d-4ea5-8d50-6da733be89da","http://resolver.tudelft.nl/uuid:3ebe8d4a-1b7d-4ea5-8d50-6da733be89da","Effects of a Disturbed Kinetic Chain in the Fastball Pitch on Elbow Kinetics and Ball Speed","Leenen, A.J.R. (Vrije Universiteit Amsterdam); van Trigt, B. (TU Delft Biomechanical Engineering); Hoozemans, Marco J.M. (Vrije Universiteit Amsterdam); Veeger, H.E.J. (TU Delft Biomechanical Engineering)","","2020","The purpose of the present study was to investigate the effect of an experimentally imposed kinetic chain disturbance in baseball pitching on ball speed and elbow kinetics. The experimental design consisted of two (within-subject) conditions. In one condition there was no manipulation (control condition). The other condition involved a manipulation of the kinetic chain by taping the pelvis and trunk. In both conditions, pitchers were instructed to throw fastballs until a minimum of 15 pitches were captured. Inverse dynamic solutions were used calculate the internal elbow moments of six elite youth baseball pitchers. The pitchers that were hampered in throwing fastballs, by the taped pelvis and trunk, showed significant lower ball speeds and peak internal varus moments compared to the pitchers that were allowed to throw without any hindrance.
2 =.127, p <.001). A higher knee extension velocity resulted in higher ball speeds within the individual, without negatively affecting the accuracy. It is advised to train, within an elite drag-flick group, for higher knee extension speed to improve the drag-flick performance. Whether training to improve this parameter results in higher ball speeds should be subject of future studies.","biomechanics; elite; Hockey; kinematics; knee; speed","en","journal article","","","","","","","","","","Biomechanical Engineering","Biomechatronics & Human-Machine Control","","",""
"uuid:7e84ce9a-9d46-42df-8787-f39c643774ef","http://resolver.tudelft.nl/uuid:7e84ce9a-9d46-42df-8787-f39c643774ef","Validation of a 5-DoF intrumented speed skate: Towards a power meter for speed skating","van der Eb, J.W. (TU Delft Biomechatronics & Human-Machine Control; Universiteit Leiden; Vrije Universiteit Amsterdam); Veeger, H.E.J. (TU Delft Biomechanical Engineering; TU Delft Biomechatronics & Human-Machine Control; Vrije Universiteit Amsterdam); de Koning, Jos (Vrije Universiteit Amsterdam)","","2019","Speed skates are the most important part of equipment of a speed skater, where weight, rocker and bend are just a few characteristics that are to a high degree individualized. This poses a challenge for any type of research in speed skating where forces have to be measured in a reliable manner. For this purpose, a 5 degrees of freedom (DoF) instrumented speed skate (VU-Skate) has been designed and validated, weighing only 130 gram extra. Skaters use their own blades and shoes, something skaters are very keen on. A calibration tool has been developed to calibrate the 5 DoF. The quality of the data has been validated in 2 ways: 1. With the use of force plates and 2. By comparing the signals to another (also newly developed) Ultra-light Forces sensor. The results are remarkably good. This is the first step in being able to measure power continuously during each stroke.","speed skating; instrumented speed skate; dynamic forces and moments","en","journal article","","","","","","","","","","Biomechanical Engineering","Biomechatronics & Human-Machine Control","","",""
"uuid:f7b56825-167b-42fa-9128-ff8f5d940705","http://resolver.tudelft.nl/uuid:f7b56825-167b-42fa-9128-ff8f5d940705","The vestibular drive for balance control is dependent on multiple sensory cues of gravity","Arntz, Anne I. (Erasmus MC; Student TU Delft); Van Der Putte, Daphne A.M. (Erasmus MC); Jonker, Z.D. (TU Delft Biomechanical Engineering; Erasmus MC; Rijndam Rehabilitation Centre); Hauwert, Christopher M. (Erasmus MC); Frens, Maarten A. (Erasmus MC); Forbes, P.A. (TU Delft Biomechatronics & Human-Machine Control; Erasmus MC)","","2019","Vestibular signals, which encode head movement in space as well as orientation relative to gravity, contribute to the ongoing muscle activity required to stand. The strength of this vestibular contribution changes with the presence and quality of sensory cues of balance. Here we investigate whether the vestibular drive for standing balance also depends on different sensory cues of gravity by examining vestibular-evoked muscle responses when independently varying load and gravity conditions. Standing subjects were braced by a backboard structure that limited whole-body sway to the sagittal plane while load and vestibular cues of gravity were manipulated by: (a) loading the body downward at 1.5 and 2 times body weight (i.e., load cues), and/or (b) exposing subjects to brief periods (20 s) of micro- (<0.05 g) and hyper-gravity (∼1.8 g) during parabolic flights (i.e., vestibular cues). A stochastic electrical vestibular stimulus (0-25 Hz) delivered during these tasks evoked a vestibular-error signal and corrective muscles responses that were used to assess the vestibular drive to standing balance. With additional load, the magnitude of the vestibular-evoked muscle responses progressively increased, however, when these responses were normalized by the ongoing muscle activity, they decreased and plateaued at 1.5 times body weight. This demonstrates that the increased muscle activity necessary to stand with additional load is accompanied a proportionally smaller increase in vestibular input. This reduction in the relative vestibular contribution to balance was also observed when we varied the vestibular cues of gravity, but only during an absence (<0.05 g) and not an excess (∼1.8 g) of gravity when compared to conditions with normal 1 g gravity signals and equivalent load signals. Despite these changes, vestibular-evoked responses were observed in all conditions, indicating that vestibular cues of balance contribute to upright standing even in the near absence of a vestibular signal of gravity (i.e., micro-gravity). Overall, these experiments provide evidence that both load and vestibular cues of gravity influence the vestibular signal processing for the control of standing balance.","Balance control; Electrical vestibular stimulation; Gravity; Vestibular system; Vestibular-evoked responses","en","journal article","","","","","","","","","","Biomechanical Engineering","Biomechatronics & Human-Machine Control","","",""
"uuid:5174ddd6-091e-4527-9d30-168bd5222b0e","http://resolver.tudelft.nl/uuid:5174ddd6-091e-4527-9d30-168bd5222b0e","Timing of peak pelvis and thorax rotation velocity in baseball pitching","van der Graaff, Erik (Vrije Universiteit Amsterdam); Hoozemans, Marco J.M. (Koninklijke Nederlandse Baseball en Softball Bond (KNBSB)); Nijhoff, Martijn (Koninklijke Nederlandse Baseball en Softball Bond (KNBSB)); Davidson, Michael (Manual Fysion); Hoezen, Merel (Manual Fysion); Veeger, H.E.J. (TU Delft Biomechanical Engineering; TU Delft Biomechatronics & Human-Machine Control; Vrije Universiteit Amsterdam)","","2018","The objective of the present study was to examine the magnitude and timing of peak pelvis and thorax rotations in achieving high throwing velocities in pitching fastballs. During the preseason (Test 1 or T1) and four months later (Test 2 or T2), kinematic analysis was performed on eight elite youth pitchers throwing fastballs. Peak rotation velocities of the pelvis and thorax were determined and separation time, defined as the time between the maximal rotation velocities of the pelvis and thorax, was calculated. Peak thorax rotation velocity was not associated with throwing velocity. However, separation time appeared to be significantly and positively associated with throwing velocity. Also, the changes in separation time from T1 to T2 were significantly and positively associated with the observed increase in throwing velocity from T1 to T2. There was no significant association between the changes in pelvis or thorax peak rotation velocities from T1 to T2 and the change in throwing velocity. Results indicate that the relative timing of pelvis and thorax peak rotation velocity in pitching fastballs in baseball is likely to be a determinant of throwing velocity in skilled pitchers.","throwing; motion analysis; kinematics; performance","en","journal article","","","","","","","","","","Biomechanical Engineering","Biomechatronics & Human-Machine Control","","",""
"uuid:19b61a8e-45ed-43b4-84d0-ef90178f0c39","http://resolver.tudelft.nl/uuid:19b61a8e-45ed-43b4-84d0-ef90178f0c39","Development, construct validity and test–retest reliability of a field-based wheelchair mobility performance test for wheelchair basketball","de Witte, AMH (The Hague University of Applied Sciences; Vrije Universiteit Amsterdam; MOVE Research Institute Amsterdam); Hoozemans, MJM (Vrije Universiteit Amsterdam; MOVE Research Institute Amsterdam); Berger, MAM (The Hague University of Applied Sciences); van der Slikke, R.M.A. (TU Delft Biomechatronics & Human-Machine Control; The Hague University of Applied Sciences); van der Woude, LHV (University Medical Center Groningen); Veeger, H.E.J. (TU Delft Biomechanical Engineering; TU Delft Biomechatronics & Human-Machine Control; Vrije Universiteit Amsterdam; MOVE Research Institute Amsterdam)","","2018","The aim of this study was to develop and describe a wheelchair mobility performance test in wheelchair basketball and to assess its construct validity and reliability. To mimic mobility performance of wheelchair basketball matches in a standardised manner, a test was designed based on observation of wheelchair basketball matches and expert judgement. Forty-six players performed the test to determine its validity and 23 players performed the test twice for reliability. Independent-samples t-tests were used to assess whether the times needed to complete the test were different for classifications, playing standards and sex. Intraclass correlation coefficients (ICC) were calculated to quantify reliability of performance times. Males performed better than females (P ","paralympic; Skill performance; task performance and analysis; wheelchairs","en","journal article","","","","","","","","2018-07-16","","Biomechanical Engineering","Biomechatronics & Human-Machine Control","","",""
"uuid:f71d60b9-f3eb-4da9-afb8-78bf2171b4ac","http://resolver.tudelft.nl/uuid:f71d60b9-f3eb-4da9-afb8-78bf2171b4ac","Stable image registration for in-vivo fetoscopic panorama reconstruction","Gaisser, F. (TU Delft Intelligent Vehicles); Peeters, Suzanne H.P. (Universiteit Leiden); Lenseigne, B.A.J. (TU Delft Biomechanical Engineering); Jonker, P.P. (TU Delft Biomechatronics & Human-Machine Control); Oepkes, Dick (Universiteit Leiden)","","2018","A Twin-to-Twin Transfusion Syndrome (TTTS) is a condition that occurs in about 10% of pregnancies involving monochorionic twins. This complication can be treated with fetoscopic laser coagulation. The procedure could greatly benefit from panorama reconstruction to gain an overview of the placenta. In previous work we investigated which steps could improve the reconstruction performance for an in-vivo setting. In this work we improved this registration by proposing a stable region detection method as well as extracting matchable features based on a deep-learning approach. Finally, we extracted a measure for the image registration quality and the visibility condition. With experiments we show that the image registration performance is increased and more constant. Using these methods a system can be developed that supports the surgeon during the surgery, by giving feedback and providing a more complete overview of the placenta.","panorama reconstruction; in-vivo fetoscopy; stable region detection","en","journal article","","","","","","","","","","Biomechanical Engineering","Intelligent Vehicles","","",""
"uuid:29c3cedf-f054-4a5c-a0a0-0c23dd0aac31","http://resolver.tudelft.nl/uuid:29c3cedf-f054-4a5c-a0a0-0c23dd0aac31","Wheelchair mobility performance enhancement by changing wheelchair properties: What Is the effect of grip, seat height, and mass?","van der Slikke, R.M.A. (TU Delft Biomechatronics & Human-Machine Control; The Hague University of Applied Sciences); De Witte, Annemarie M.H. (The Hague University of Applied Sciences; Vrije Universiteit Amsterdam); Berger, Monique A.M. (The Hague University of Applied Sciences); Bregman, D.J.J. (TU Delft Research Funding National; TU Delft Biomechanical Engineering); Veeger, H.E.J. (TU Delft Biomechanical Engineering; TU Delft Biomechatronics & Human-Machine Control; Vrije Universiteit Amsterdam)","","2018","Purpose: To provide insight on the effect of wheelchair settings on wheelchair mobility performance (WMP). Methods: Twenty elite wheelchair basketball athletes of low (n = 10) and high classification (n = 10) were tested in a wheelchair-basketball-directed field test. Athletes performed the test in their own wheelchairs, which were modified for 5 additional conditions regarding seat height (high–low), mass (central–distributed), and grip. The previously developed inertial-sensor-based WMP monitor was used to extract wheelchair kinematics in all conditions. Results: Adding mass showed most effect on WMP, with a reduced average acceleration across all activities. Once distributed, additional mass also reduced maximal rotational speed and rotational acceleration. Elevating seat height had an effect on several performance aspects in sprinting and turning, whereas lowering seat height influenced performance minimally. Increased rim grip did not alter performance. No differences in response were evident between low- and high-classified athletes. Conclusions: The WMP monitor showed sensitivity to detect performance differences due to the small changes in wheelchair configuration. Distributed additional mass had the most effect on WMP, whereas additional grip had the least effect of conditions tested. Performance effects appear similar for both low- and high-classified athletes. Athletes, coaches, and wheelchair experts are provided with insight into the performance effect of key wheelchair settings, and they are offered a proven sensitive method to apply in sport practice, in their search for the best wheelchair–athlete combination.","paralympic sports; classification; wheelchair basketball","en","journal article","","","","","","Accepted Author Manuscript","","","","Biomechanical Engineering","Biomechatronics & Human-Machine Control","","",""
"uuid:c56d7611-7348-4443-87ae-3ab0843966a2","http://resolver.tudelft.nl/uuid:c56d7611-7348-4443-87ae-3ab0843966a2","Knee angle and Stride Length in Association with Ball Speed in Youth Baseball Pitchers","van Trigt, B. (Vrije Universiteit Amsterdam); Schallig, W. (Vrije Universiteit Amsterdam); van der Graaff, E. (Vrije Universiteit Amsterdam); Hoozemans, Marco J.M. (Vrije Universiteit Amsterdam); Veeger, H.E.J. (TU Delft Biomechanical Engineering; TU Delft Biomechatronics & Human-Machine Control; Vrije Universiteit Amsterdam)","","2018","The purpose of this study was to determine whether stride length and knee angle of the leading leg at foot contact, at the instant of maximal external rotation of the shoulder, and at ball release are associated with ball speed in elite youth baseball pitchers. In this study, fifty-two elite youth baseball pitchers (mean age 15.2 SD (standard deviation) 1.7 years) pitched ten fastballs. Data were collected with three high-speed video cameras at a frequency of 240 Hz. Stride length and knee angle of the leading leg were calculated at foot contact, maximal external rotation, and ball release. The associations between these kinematic variables and ball speed were separately determined using generalized estimating equations. Stride length as percentage of body height and knee angle at foot contact were not significantly associated with ball speed. However, knee angles at maximal external rotation and ball release were significantly associated with ball speed. Ball speed increased by 0.45 m/s (1 mph) with an increase in knee extension of 18 degrees at maximal external rotation and 19.5 degrees at ball release. In conclusion, more knee extension of the leading leg at maximal external rotation and ball release is associated with higher ball speeds in elite youth baseball pitchers","kinematics; biomechanics; sports; fastball","en","journal article","","","","","","","","","","Biomechanical Engineering","Biomechatronics & Human-Machine Control","","",""
"uuid:a1e9d161-7c6e-4452-b68b-291f08117c55","http://resolver.tudelft.nl/uuid:a1e9d161-7c6e-4452-b68b-291f08117c55","Power in sports: A literature review on the application, assumptions, and terminology of mechanical power in sport research","van der Kruk, E. (TU Delft Biomechatronics & Human-Machine Control); van der Helm, F.C.T. (TU Delft Biomechatronics & Human-Machine Control); Veeger, H.E.J. (TU Delft Biomechanical Engineering; TU Delft Biomechatronics & Human-Machine Control); Schwab, A.L. (TU Delft Biomechatronics & Human-Machine Control)","","2018","The quantification of mechanical power can provide valuable insight into athlete performance because it is the mechanical principle of the rate at which the athlete does work or transfers energy to complete a movement task. Estimates of power are usually limited by the capabilities of measurement systems, resulting in the use of simplified power models. This review provides a systematic overview of the studies on mechanical power in sports, discussing the application and estimation of mechanical power, the consequences of simplifications, and the terminology. The mechanical power balance consists of five parts, where joint power is equal to the sum of kinetic power, gravitational power, environmental power, and frictional power. Structuring literature based on these power components shows that simplifications in models are done on four levels, single vs multibody models, instantaneous power (IN) versus change in energy (EN), the dimensions of a model (1D, 2D, 3D), and neglecting parts of the mechanical power balance. Quantifying the consequences of simplification of power models has only been done for running, and shows differences ranging from 10% up to 250% compared to joint power models. Furthermore, inconsistency and imprecision were found in the determination of joint power, resulting from inverse dynamics methods, incorporation of translational joint powers, partitioning in negative and positive work, and power flow between segments. Most inconsistency in terminology was found in the definition and application of ‘external’ and ‘internal’ work and power. Sport research would benefit from structuring the research on mechanical power in sports and quantifying the result of simplifications in mechanical power estimations.","Mechanical power; Internal power; External power; Mechanical energy expenditure; Joint power","en","review","","","","","","Accepted Author Manuscript","","2019-09-18","","Biomechanical Engineering","Biomechatronics & Human-Machine Control","","",""
"uuid:7664e917-56e8-4d31-a281-0cc5147f3531","http://resolver.tudelft.nl/uuid:7664e917-56e8-4d31-a281-0cc5147f3531","Asymmetry and evolution over a one-year period of the upward rotation of the scapula in youth baseball pitchers","van der Graaff, E. (TU Delft Biomechanical Engineering; Vrije Universiteit Amsterdam); Kom, Bengt (Vrije Universiteit Amsterdam); van Dis, Femke (Vrije Universiteit Amsterdam); Gasparutto, X. (TU Delft Biomechatronics & Human-Machine Control); Hoozemans, Marco (Vrije Universiteit Amsterdam); Veeger, H.E.J. (TU Delft Biomechanical Engineering; TU Delft Biomechatronics & Human-Machine Control; Vrije Universiteit Amsterdam)","","2018","The pitching motion is an asymmetric action by which coordination of scapular rotation in the dominant arm might be affected in time and in comparison with the non-dominant arm. The study aimed to compare asymmetry and the evolution of scapular upward rotation over a one-year period. Data were collected twice, before and after a one-year period, from 92 participants (age = 15.1 SD 1.4 years, body height = 177.3 SD 10.9 cm, body weight 69.2 SD 14.5 kg). Scapular motion was tracked at different glenohumeral angles of elevation in the scapular plane: anatomical position (0°), 45°, 90° and 135°. Scapular upward rotation was calculated as the angle between the spinae scapula and the spine. Scapular upward rotation of the dominant arm was 5.1° (95% CI: 2.1°−8.1°) more compared to the non-dominant arm. Age group or glenohumeral angles of elevation did not affect this difference. Scapular upward rotation of the dominant arm decreased 1.9° (95% CI: −0.5° to 4.3°) after a one-year period, however, neither this observation, nor the interaction with age group or elevation angle was significant. These findings may indicate that pitchers could be at risk to develop shoulder injuries especially those that have been associated with scapular asymmetry.","baseball; overhead throwing; Pitching; scapular dyskinesis; scapular upward rotation","en","journal article","","","","","","","","","","Biomechanical Engineering","Biomechatronics & Human-Machine Control","","",""
"uuid:2d7cfedf-de64-4f5a-a5b7-09be2c04fb34","http://resolver.tudelft.nl/uuid:2d7cfedf-de64-4f5a-a5b7-09be2c04fb34","A musculoskeletal model of the hand and wrist: model definition and evaluation","Mirakhorlo, M. (Vrije Universiteit Amsterdam); Van Beek, N. (Vrije Universiteit Amsterdam); Wesseling, M. (Katholieke Universiteit Leuven); Maas, H. (Vrije Universiteit Amsterdam); Veeger, H.E.J. (TU Delft Biomechanical Engineering; TU Delft Biomechatronics & Human-Machine Control; Vrije Universiteit Amsterdam); Jonkers, I. (Katholieke Universiteit Leuven)","","2018","To improve our understanding on the neuromechanics of finger movements, a comprehensive musculoskeletal model is needed. The aim of this study was to build a musculoskeletal model of the hand and wrist, based on one consistent data set of the relevant anatomical parameters. We built and tested a model including the hand and wrist segments, as well as the muscles of the forearm and hand in OpenSim. In total, the model comprises 19 segments (with the carpal bones modeled as one segment) with 23 degrees of freedom and 43 muscles. All required anatomical input data, including bone masses and inertias, joint axis positions and orientations as well as muscle morphological parameters (i.e. PCSA, mass, optimal fiber length and tendon length) were obtained from one cadaver of which the data set was recently published. Model validity was investigated by first comparing computed muscle moment arms at the index finger metacarpophalangeal (MCP) joint and wrist joint to published reference values. Secondly, the muscle forces during pinching were computed using static optimization and compared to previously measured intraoperative reference values. Computed and measured moment arms of muscles at both index MCP and wrist showed high correlation coefficients (r = 0.88 averaged across all muscles) and modest root mean square deviation (RMSD = 23% averaged across all muscles). Computed extrinsic flexor forces of the index finger during index pinch task were within one standard deviation of previously measured in-vivo tendon forces. These results provide an indication of model validity for use in estimating muscle forces during static tasks.","Finger; moment arm; pinch force","en","journal article","","","","","","","","","","Biomechanical Engineering","Biomechatronics & Human-Machine Control","","",""
"uuid:7eb875fb-03f3-48d4-b054-022ff8f260cc","http://resolver.tudelft.nl/uuid:7eb875fb-03f3-48d4-b054-022ff8f260cc","Understanding the constraints of finger motor control","Maas, Huub (Vrije Universiteit Amsterdam); Veeger, H.E.J. (TU Delft Biomechanical Engineering; TU Delft Biomechatronics & Human-Machine Control; Vrije Universiteit Amsterdam); Stegeman, Dick F. (Vrije Universiteit Amsterdam; Radboud Universiteit Nijmegen)","","2018","","","en","contribution to periodical","","","","","","","","2018-10-16","","Biomechanical Engineering","Biomechatronics & Human-Machine Control","","",""
"uuid:5698671c-9dea-41b4-8638-187fbadac8b2","http://resolver.tudelft.nl/uuid:5698671c-9dea-41b4-8638-187fbadac8b2","Influence of biomechanical models on joint kinematics and kinetics in baseball pitching","Gasparutto, X. (TU Delft Biomechatronics & Human-Machine Control); van der Graaff, E. (TU Delft Biomechanical Engineering; Vrije Universiteit Amsterdam); van der Helm, F.C.T. (TU Delft Biomechatronics & Human-Machine Control); Veeger, H.E.J. (TU Delft Biomechanical Engineering; TU Delft Biomechatronics & Human-Machine Control; Vrije Universiteit Amsterdam)","","2018","In baseball pitching, biomechanical parameters have been linked to ball velocity and potential injury risk. However, although the features of a biomechanical model have a significant influence on the kinematics and kinetics of a motion, this influence have not been assessed for pitching. The aim of this study was to evaluate the choice of the trunk and shoulder features, by comparing two models using the same input. The models differed in thoraco-humeral joint definition (moving or fixed with the thorax), joint centre estimation, values of the inertial parameters and computational framework. One professional pitcher participated in the study. We found that the different features of the biomechanical models have a substantial influence on the kinematics and kinetics of the pitchers. With a fixed thoraco-humeral joint the peak average thorax angular velocity was delayed and underestimated by 17% and the shoulder internal rotation velocity was overestimated by 7%. The use of a thoraco-humeral joint fixed to the thorax will lead to an overestimation of the rotational power at the shoulder and will neglect the power produced by the forward and upward translation of the shoulder girdle. These findings have direct implications for the interpretation of shoulder muscle contributions to the pitch.","Inverse dynamics; modelling; overhand throw; shoulder; trunk","en","journal article","","","","","","","","","","Biomechanical Engineering","Biomechatronics & Human-Machine Control","","",""
"uuid:6277e46d-c662-430f-b1dc-c83dbceb24cb","http://resolver.tudelft.nl/uuid:6277e46d-c662-430f-b1dc-c83dbceb24cb","Understanding and improving driving performance by removing and adding visual information","Saffarian, M (TU Delft Biomechanical Engineering)","van der Helm, F.C.T. (promotor); de Winter, J.C.F. (copromotor); Happee, R. (copromotor); Delft University of Technology (degree granting institution)","2017","","","en","doctoral thesis","","","","","","This research has been financially supported by the Dutch Ministry of Economic affairs through the program High Tech Automotive Systems (HTAS), grant HTASD08002 to the project Connect & Drive and by the Natural Science and Engineering Research Council of Canada (NSERC) graduate scholarship program.","","","","Biomechanical Engineering","","","",""
"uuid:aed40c4d-d407-4320-b323-f9792e5cb1a5","http://resolver.tudelft.nl/uuid:aed40c4d-d407-4320-b323-f9792e5cb1a5","Characterizing human skin blood flow regulation in response to different local skin temperature perturbations","Wu, Y. (TU Delft Biomechatronics & Human-Machine Control); Nieuwenhoff, M.D. (Erasmus Universiteit Rotterdam); Huygen, F.J.P.M. (Erasmus Universiteit Rotterdam); van der Helm, F.C.T. (TU Delft Biomechatronics & Human-Machine Control); Niehof, S.P. (TU Delft Biomechanical Engineering; Erasmus Universiteit Rotterdam; Maasstad Hospital); Schouten, A.C. (TU Delft Biomechatronics & Human-Machine Control; University of Twente)","","2017","Small nerve fibers regulate local skin blood flow in response to local thermal perturbations. Small nerve fiber function is difficult to assess with classical neurophysiological tests. In this study, a vasomotor response model in combination with a heating protocol was developed to quantitatively characterize the control mechanism of small nerve fibers in regulating skin blood flow in response to local thermal perturbation. The skin of healthy subjects’ hand dorsum (n = 8) was heated to 42 °C with an infrared lamp, and then naturally cooled down. The distance between the lamp and the hand was set to three different levels in order to change the irradiation intensity on the skin and implement three different skin temperature rise rates (0.03 °C/s, 0.02 °C/s and 0.01 °C/s). A laser Doppler imager (LDI) and a thermographic video camera recorded the temporal profile of the skin blood flow and the skin temperature, respectively. The relationship between the skin blood flow and the skin temperature was characterized by a vasomotor response model. The model fitted the skin blood flow response well with a variance accounted for (VAF) between 78% and 99%. The model parameters suggested a similar mechanism for the skin blood flow regulation with the thermal perturbations at 0.03 °C/s and 0.02 °C/s. But there was an accelerated skin vasoconstriction after a slow heating (0.01 °C/s) (p-value ","Modelling; Skin blood flow; Skin temperature; Small nerve fibers; Thermoregulation","en","journal article","","","","","","","","","","Biomechanical Engineering","Biomechatronics & Human-Machine Control","","",""
"uuid:0829f5fe-d9cb-40e5-8900-92fe4cbedff4","http://resolver.tudelft.nl/uuid:0829f5fe-d9cb-40e5-8900-92fe4cbedff4","Influence of posture variation on shoulder muscle activity, heart rate, and perceived exertion in a repetitive manual task","Luger, Tessy (University of Gävle; TNO; Vrije Universiteit Amsterdam; Eberhard Karls Universität Tübingen); Mathiassen, Svend Erik (University of Gävle); Bosch, Tim (TNO); Hoozemans, Marco (Vrije Universiteit Amsterdam); Douwes, Marjolein (TNO); Veeger, H.E.J. (TU Delft Biomechanical Engineering; TU Delft Biomechatronics & Human-Machine Control; Vrije Universiteit Amsterdam); de Looze, Michiel (TNO; Vrije Universiteit Amsterdam)","","2017","In repetitive work, more physical variation is believed to reduce the risk of eventually developing musculoskeletal disorders. We investigated the extent to which workstation designs leading to more variation in upper arm postures during a pick-and-place task influenced outcomes of relevance to musculoskeletal disorder risk, including muscle activity, cardiovascular response, and perceived exertion, measured through the maximal acceptable work pace. Posture variation to the extent obtained in our experiment had only minor effects on these outcomes, and considerably less impact than a moderate change in working height. Apparently, substantial manipulations of the workstation or of the work task will be needed to accomplish variation to an extent that can significantly change outcomes of relevance to occupational musculoskeletal disorders and, thus, represent a potential for reduction in musculoskeletal disorder risk.","Arm elevation; exposure variation; maximal acceptable work pace; muscle activity; repetitive work","en","journal article","","","","","","","","","","Biomechanical Engineering","Biomechatronics & Human-Machine Control","","",""
"uuid:f7bb4c1e-7b0c-4a61-81cc-b7be95e6642c","http://resolver.tudelft.nl/uuid:f7bb4c1e-7b0c-4a61-81cc-b7be95e6642c","Timing and extent of finger force enslaving during a dynamic force task cannot be explained by EMG activity patterns","Mirakhorlo, M. (Vrije Universiteit Amsterdam); Maas, Huub (Vrije Universiteit Amsterdam); Veeger, H.E.J. (TU Delft Biomechanical Engineering; TU Delft Biomechatronics & Human-Machine Control; Vrije Universiteit Amsterdam)","","2017","Finger enslaving is defined as the inability of the fingers to move or to produce force independently. Such finger enslaving has predominantly been investigated for isometric force tasks. The aim of this study was to assess whether the extent of force enslaving is dependent on relative finger movements. Ten right-handed subjects (22–30 years) flexed the index finger while counteracting constant resistance forces (4, 6 and 8 N) orthogonal to the fingertip. The other, non-instructed fingers were held in extension. EMG activities of the mm. flexor digitorum superficialis (FDS) and extensor digitorum (ED) in the regions corresponding to the index, middle and ring fingers were measured. Forces exerted by the non-instructed fingers increased substantially (by 0.2 to 1.4 N) with flexion of the index finger, increasing the enslaving effect with respect to the static, pre-movement phase. Such changes in force were found 260–370 ms after the initiation of index flexion. The estimated MCP joint angle of the index finger at which forces exerted by the non-instructed fingers started to increase varied between 4° and 6°. In contrast to the finger forces, no significant changes in EMG activity of the FDS regions corresponding to the non-instructed fingers upon index finger flexion were found. This mismatch between forces and EMG of the non-instructed fingers, as well as the delay in force development are in agreement with connective tissue linkages being slack when the positions of the fingers are similar, but pulled taut when one finger moves relative to the others. Although neural factors cannot be excluded, our results suggest that mechanical connections between muscle-tendon structures were (at least partly) responsible for the observed increase in force enslaving during index finger flexion.","","en","journal article","","","","","","","","","","Biomechanical Engineering","Biomechatronics & Human-Machine Control","","",""
"uuid:cb0b4a56-505a-449a-83a6-853e9fe3ef5e","http://resolver.tudelft.nl/uuid:cb0b4a56-505a-449a-83a6-853e9fe3ef5e","Focus of attention instructions during baseball pitching training","van der Graaff, Erik (Vrije Universiteit Amsterdam); Hoozemans, Marco (Vrije Universiteit Amsterdam); Pasteuning, Maurice (Vrije Universiteit Amsterdam); Veeger, H.E.J. (TU Delft Biomechanical Engineering; TU Delft Biomechatronics & Human-Machine Control; Vrije Universiteit Amsterdam); Beek, Peter J. (Vrije Universiteit Amsterdam)","","2017","It has often been shown that performance and learning in movement tasks may be improved by focusing on the effect of the movement in the environment (external focus of attention) instead of the movement itself (internal focus of attention). Nevertheless, most coaching instructions and feedback information given in sports seem to favor an internal focus of attention over an external one. In the present study, we investigated coaches’ instructions and feedback in an instrumental sports action, viz. baseball pitching, in which external targets are readily identifiable, such as the strike area or the catcher’s glove. To this end, we recorded and analyzed the pitching instructions and feedback statements of six baseball coaches given to 70 elite youth baseball pitchers (mean age 15.3 (SD 1.67) years) during regular pitching training sessions over a training period of four weeks. All instructions and feedback statements were classified according to the type of focus of attention invoked (i.e. internal or external), and a rest category of all other statements. Of the statements promoting a specific focus of attention (717/1699), only 31% (224/717) were classified as external focus of attention statements. Correspondingly, the responses on a questionnaire filled out by the pitchers indicated that they used an internal focus of attention during practice and preferred to receive internally oriented over externally oriented instructions and feedback. The present results show that, even in sports involving clear external targets such as baseball pitching, the internal focus of attention instructions prevails, the experimental evidence in favor of external focus of attention instructions notwithstanding","Baseball; coaching; focus of attention; instructions; training","en","journal article","","","","","","","","","","Biomechanical Engineering","Biomechatronics & Human-Machine Control","","",""
"uuid:20c38d35-4492-4e16-b080-51420266205a","http://resolver.tudelft.nl/uuid:20c38d35-4492-4e16-b080-51420266205a","Edward Valstar (1970–2017): In memoriam","Nelissen, R.G.H.H. (TU Delft Biomechatronics & Human-Machine Control); Kaptein, B.L. (TU Delft Biomechanical Engineering); Veeger, H.E.J. (TU Delft Biomechanical Engineering; TU Delft Biomechatronics & Human-Machine Control)","","2017","","","en","journal article","","","","","","","","","","Biomechanical Engineering","Biomechatronics & Human-Machine Control","","",""
"uuid:f1ce6206-45cc-46ab-8f58-0b2917d92677","http://resolver.tudelft.nl/uuid:f1ce6206-45cc-46ab-8f58-0b2917d92677","Design and verification of a simple 3D dynamic model of speed skating which mimics observed forces and motions","van der Kruk, E. (TU Delft Biomechatronics & Human-Machine Control); Veeger, H.E.J. (TU Delft Biomechanical Engineering; TU Delft Biomechatronics & Human-Machine Control); van der Helm, F.C.T. (TU Delft Biomechatronics & Human-Machine Control); Schwab, A.L. (TU Delft Biomechatronics & Human-Machine Control)","","2017","Advice about the optimal coordination pattern for an individual speed skater, could be addressed by simulation and optimization of a biomechanical speed skating model. But before getting to this optimization approach one needs a model that can reasonably match observed behaviour. Therefore, the objective of this study is to present a verified three dimensional inverse skater model with minimal complexity, which models the speed skating motion on the straights. The model simulates the upper body transverse translation of the skater together with the forces exerted by the skates on the ice. The input of the model is the changing distance between the upper body and the skate, referred to as the leg extension (Euclidean distance in 3. D space). Verification shows that the model mimics the observed forces and motions well. The model is most accurate for the position and velocity estimation (respectively 1.2% and 2.9% maximum residuals) and least accurate for the force estimations (underestimation of 4.5-10%). The model can be used to further investigate variables in the skating motion. For this, the input of the model, the leg extension, can be optimized to obtain a maximal forward velocity of the upper body.","Multibody model; Optimization; Speed skating; Verification","en","journal article","","","","","","","","","","Biomechanical Engineering","Biomechatronics & Human-Machine Control","","",""
"uuid:85e3c405-25c3-4ea1-8d03-0956ec30f547","http://resolver.tudelft.nl/uuid:85e3c405-25c3-4ea1-8d03-0956ec30f547","Improving mobility performance in wheelchair basketball","Veeger, Thom T.J. (Vrije Universiteit Amsterdam); De Witte, Annemarie M.H. (The Hague University of Applied Sciences; Vrije Universiteit Amsterdam); Berger, Monique A.M. (The Hague University of Applied Sciences); van der Slikke, R.M.A. (TU Delft Biomechatronics & Human-Machine Control; The Hague University of Applied Sciences); Veeger, H.E.J. (TU Delft Biomechanical Engineering; TU Delft Biomechatronics & Human-Machine Control; Vrije Universiteit Amsterdam); Hoozemans, Marco J.M. (Vrije Universiteit Amsterdam)","","2017","Objectiev:
This study aimed to investigate which characteristics of athlete, wheelchair and athlete-wheelchair interface are the best predictors of wheelchair basketball mobility performance.
Design:
Sixty experienced wheelchair basketball players performed a wheelchair mobility performance test to assess their mobility performance. To determine which variables were the best predictors of mobility performance, forward stepwise linear regression analyses were performed on a set of 33 characteristics, including ten athlete, nineteen wheelchair and four athlete-wheelchair interface characteristics.
Results:
Eight of the characteristics turned out to be significant predictors of wheelchair basketball mobility performance. Classification, experience, maximal isometric force, wheel axis height and hand rim diameter - which both interchangeable with each other and wheel diameter - camber angle, and the vertical distance between shoulder and rear wheel axis – which was interchangeable with seat height - were positively associated with mobility performance. The vertical distance between the front seat and the footrest was negatively associated with mobility performance.
Conclusion:
With this insight, coaches and biomechanical specialists are provided with statistical findings to determine which characteristics they could focus on best to improve mobility performance. Six out of eight predictors are modifiable and can be optimized to improve mobility performance. These adjustments could be carried out both in training (maximal isometric force) and in wheelchair configurations (e.g. camber angle).","wheelchair configuration; athletic performance; Paralympic; wheelchair-athlete interface","en","journal article","","","","","","Accepted Author Manuscript","","","","Biomechanical Engineering","Biomechatronics & Human-Machine Control","","",""
"uuid:d3b3ba0e-b590-451c-a43a-3d3755662155","http://resolver.tudelft.nl/uuid:d3b3ba0e-b590-451c-a43a-3d3755662155","Effects of offense, defense, and ball possession on mobility performance in wheelchair basketball","De Witte, Annemarie M.H. (The Hague University of Applied Sciences; Vrije Universiteit Amsterdam); Berger, Monique A.M. (The Hague University of Applied Sciences); Hoozemans, Marco J.M. (Vrije Universiteit Amsterdam); Veeger, H.E.J. (TU Delft Biomechanical Engineering; TU Delft Biomechatronics & Human-Machine Control; Vrije Universiteit Amsterdam); van der Woude, Lucas H.V. (Rijksuniversiteit Groningen)","","2017","The aim of this study was to determine to what extent mobility performance is influenced by offensive or defensive situations and ball possession and to what extent these actions are different for the field positions. From video analysis, the relative duration of the various wheelchair movements during team offense/defense and individual ball possession was compared in 56 elite wheelchair basketball players. A two-way analysis of variance indicated that during offense, the guards and forwards performed longer driving forward than during defense. Overall, centers stood still longer during offense than during defense. Without ball, centers performed driving forward longer than with ball possession. It is concluded that offense, defense, and ball possession influenced mobility performance for the different field positions. These differences can be used to design specific training protocols. Furthermore, field positions require potentially different specific wheelchair configurations to improve performance.","Offense/defense; Video analysis; Wheelchair configurations; Wheelchair–athlete interaction","en","journal article","","","","","","Accepted Author Manuscripts","","","","Biomechanical Engineering","Biomechatronics & Human-Machine Control","","",""
"uuid:4786421d-ccfa-43b3-ad2c-6b71055d929e","http://resolver.tudelft.nl/uuid:4786421d-ccfa-43b3-ad2c-6b71055d929e","Towards real-time feedback in high performance speed skating","van der Eb, Jeroen (Vrije Universiteit Amsterdam); Zandee, Willem (Vrije Universiteit Amsterdam); van den Bogaard, Timo (Vrije Universiteit Amsterdam); Geraets, Sjoerd (Vrije Universiteit Amsterdam); Veeger, H.E.J. (TU Delft Biomechanical Engineering; TU Delft Biomechatronics & Human-Machine Control; Vrije Universiteit Amsterdam); Beek, Peter (Vrije Universiteit Amsterdam)","Potthast, Wolfgang (editor); Niehoff, Anja (editor); David, Sina (editor)","2017","The aim of the current study is to evaluate several performance indicators to be used as real-time feedback in the coming experiments to enhance performance of elite speeds skaters. Six speed skaters, wearing one IMU per skate, collected data over one full training season to evaluate and pinpoint useful performance indicators. Promising performance indicators were picked in close collaboration with the coaches. One of those is the time that two skates are on the ice simultaneously, the double stance phase (DS). Coaches believe it has an inverse relation to velocity of the skater. In the curve this relationship is found for some skaters but not all. Also other factors seem to influence the DS phase as well. Data of a higher quality skating ring are inline with this finding but more profound, indicating that ice quality or anxiety, could influence the double stance phase as well.","biomechanic al analysis; elite sports performance; direct feedback","en","conference paper","International Society of Biomechanics in Sports","","","","","","","","","Biomechanical Engineering","Biomechatronics & Human-Machine Control","","",""
"uuid:318c29f7-4a32-40a1-aa50-837f6b3f3d88","http://resolver.tudelft.nl/uuid:318c29f7-4a32-40a1-aa50-837f6b3f3d88","A new approach to simplify surgical colpotomy in laparoscopic hysterectomy","Van den Haak, L.; Rhemrev, J.P.; Bikkendaal, M.D.; Luteijn, A.C.; Van den Dobbelsteen, J.J.; Driessen, S.R.; Jansen, F.W.","","2016","New surgical techniques and technology have simplified laparoscopic hysterectomy and have enhanced the safety of this procedure. However, the surgical colpotomy step has not been addressed. This study evaluates the surgical colpotomy step in laparoscopic hysterectomy with respect to difficulty and duration. Furthermore, it proposes an alternative route that may simplify this step in laparoscopic hysterectomy. A structured interview, a prospective cohort study, and a problem analysis were performed regarding experienced difficulty and duration of surgical colpotomy in laparoscopic hysterectomy. Sixteen experts in minimally invasive gynecologic surgery from 12 hospitals participated in the structured interview using a 5-point Likert scale. The colpotomy in LH received the highest scores for complexity (2.8 ± 1.2), compared to AH and VH. Colpotomy in LH was estimated as more difficult than in AH (2.8 vs 1.4, p < .001). In the cohort study, 107 patients undergoing LH were included. Sixteen percent of the total procedure time was spent on colpotomy (SD 7.8 %). BMI was positively correlated with colpotomy time, even after correcting for longer operation time. No relation was found between colpotomy time and blood loss or uterine weight. The surgical colpotomy step in laparoscopic hysterectomy should be simplified as this study demonstrates that it is time consuming and is considered to be more difficult than in other hysterectomy procedures. A vaginal approach to the colpotomy is proposed to achieve this simplification.","laparoscopic hysterectomy; colpotomy; new technology; innovation of surgical technique","en","journal article","Springer","","","","","","","","Mechanical, Maritime and Materials Engineering","BioMechanical Engineering","","","",""
"uuid:195f8765-39a2-40b3-b976-aa877d4a945a","http://resolver.tudelft.nl/uuid:195f8765-39a2-40b3-b976-aa877d4a945a","Is the force with you? On the accuracy of human force perception","Onneweer, B.","Van der Helm, F.C.T. (promotor); Schouten, A.C. (promotor); Mugge, W. (promotor)","2016","Haptic technology is more and more widely used to improve human interaction with devices, for example in touch screens of smartphones that vibrate when touched. Another application is haptic-tele-manipulation where a human controls a slave manipulator (e.g. a surgical-robot) by using a master device (e.g. a joystick). In haptic-tele-manipulation, forces measured at the slave manipulator are fed back to the human operator is order to improve task performance. Currently, human force perception is neglected in haptic system design, implicitly assuming perfect force perception, requiring high performance of the master and slave devices. The goal of this thesis is to identify key factors that influence isometric (static) force perception, and to develop metrics and computational models that quantify and predict this influence. To reach this goal, isometric force reproduction experiments were performed in which subjects were asked to actively generate the target and reproduction force using the same hand. In this thesis, we analyzed the influences of different factors using the same experimental protocol. Subjects were asked to perform series of two interchanging trials: matching an onscreen force in magnitude and direction (target trial), and subsequently reproducing the same force vector without visual feedback (reproduction trial). The difference in forces exerted during the target and reproduction trial is called the force reproduction error. In chapter two, we analyzed the effect of force magnitude on the force reproduction error and position reproduction error in one degree of freedom (DOF). Subjects performed force reproduction tasks at different force levels (10N – 160N, with 30N increments), against a fixed handle, and performed a position reproduction task against a haptic manipulator, which applied constant opposing forces. Subjects reproduced too high forces for low force levels (<40N) and too low forces for high force levels (>130N). No effect of force level on the position reproduction error was found. If the force reproduction error is exclusively caused by the reafference feedback (by the CNS predicted sensory feedback caused by self-generated forces), the force reproduction error should disappear when both target and reproduction force are self-generated. The results of this study show an effect of force level on the force reproduction error, indicating that reafference feedback is not the sole factor in force reproduction tasks. In chapter three, we analyzed the effect of force direction and arm-posture on the force reproduction error in the horizontal plane. The force reproduction protocol was performed in eight force directions and in four arm postures at a force level of 10N. Results showed that the force reproduction error depends on force direction. The orientation of the ellipses fitted through the reproduction forces changed with arm posture and the least accurate direction aligned with the shoulder in all postures. For each of the four arm postures, a joint torque scaling model based on arm biomechanics was fitted to the other three postures and was shown to accurately explain the reproduction ellipse. This chapter shows that force reproduction depends on force direction and arm posture, which corresponds with our model based on arm biomechanics and suggests that the force reproduction errors at the endpoint originate at the joint torque level. Chapter four assesses the effect of force magnitude on the force reproduction error in the horizontal plane. Three groups of subjects performed the force reproduction protocol in eight force directions and in two arm postures at three force levels (group1: 10N, group2: 40N and group3: 70N). Results show that the orientation of the reproduction ellipses changes with arm posture but not with force level, indicating that the arm biomechanics (i.e. arm orientation) affect the directional and force effects. Additionally, the results show that force level affects the force reproduction error differently depending on the force direction, i.e. increased force magnitude increases the errors in the direction of the shoulder and decreases the errors in the perpendicular direction. To incorporate the force level dependency of the force reproduction error, a novel joint-torque-dependent joint-torque-scaling model is developed, which allows us to accurately predict the force reproduction errors in the horizontal plane between 10N and 70N. In chapter five, we present an experimental study to examine whether the systematic errors result from an incorrect representation of forces or incorrect execution of correctly represented forces. In this experiment we asked the subjects to reproduce the same magnitude of force (5N or 15N) in either the same direction (reference trial) or in a 90?-counter-clockwise-rotated direction (CCW trial). We hypothesize that if the force reproduction errors arose through an execution error, subjects would obtain the correct representation of target force but reproduce this incorrectly in the CCW trials, resulting in an identically oriented reproduction ellipse as in the reference trials. However, if these systematic errors arose through an incorrect representation, then we hypothesize that subjects would produce a 90?-rotated ellipse relative to the reference trials. The absence of any rotation in our results demonstrates that the forces were represented correctly, and the systematic errors arise as execution errors during reproduction. Moreover, the results suggest that the sensorimotor system does not attempt to match the sensory percept or the motor commands, but instead develops an internal representation of the forces. In chapter six the main results of the thesis are discussed, where we present three overall conclusions: 1) Human force perception comprises systematic errors; 2) Systematic errors in force perception originate at joint level and are predictable; 3) The systematic errors in force perception are execution errors. Based on these overall conclusions we provide two guidelines for haptic system design (H) and two guidelines for neuroscience (N): H1) Take the accuracy of human force perception into account to make haptic devices more affordable; H2) Compensate for the systematic errors in human force perception; N1) The errors for different modalities originate in different reference frames; N2) The central nervous system does not simply compare sensory information or motor commands to control the body. The work described in this thesis provides novel insight in the accuracy of human force perception, presents a model that can accurately predict the force reproduction error, and provides the first steps in determining where the errors originate.","Human force perception; Human factors; Haptic human machine interaction","en","doctoral thesis","","","","","","","","","Mechanical, Maritime and Materials Engineering","Biomechanical Engineering","","","",""
"uuid:4d1395c6-bf7e-4fd3-b6c7-10102612e542","http://resolver.tudelft.nl/uuid:4d1395c6-bf7e-4fd3-b6c7-10102612e542","Reliability of System Identification Techniques to Assess Standing Balance in Healthy Elderly","Pasma, J.H.; Engelhart, D.; Maier, A.B.; Aarts, R.G.K.M.; Van Gerven, J.M.A.; Arendzen, J.H.; Schouten, A.C.; Meskers, C.G.M.; Van der Kooij, H.","","2016","Objectives System identification techniques have the potential to assess the contribution of the underlying systems involved in standing balance by applying well-known disturbances. We investigated the reliability of standing balance parameters obtained with multivariate closed loop system identification techniques. Methods In twelve healthy elderly balance tests were performed twice a day during three days. Body sway was measured during two minutes of standing with eyes closed and the Balance test Room (BalRoom) was used to apply four disturbances simultaneously: two sensory disturbances, to the proprioceptive and the visual system, and two mechanical disturbances applied at the leg and trunk segment. Using system identification techniques, sensitivity functions of the sensory disturbances and the neuromuscular controller were estimated. Based on the generalizability theory (G theory), systematic errors and sources of variability were assessed using linear mixed models and reliability was assessed by computing indexes of dependability (ID), standard error of measurement (SEM) and minimal detectable change (MDC). Results A systematic error was found between the first and second trial in the sensitivity functions. No systematic error was found in the neuromuscular controller and body sway. The reliability of 15 of 25 parameters and body sway were moderate to excellent when the results of two trials on three days were averaged. To reach an excellent reliability on one day in 7 out of 25 parameters, it was predicted that at least seven trials must be averaged. Conclusion This study shows that system identification techniques are a promising method to assess the underlying systems involved in standing balance in elderly. However, most of the parameters do not appear to be reliable unless a large number of trials are collected across multiple days. To reach an excellent reliability in one third of the parameters, a training session for participants is needed and at least seven trials of two minutes must be performed on one day.","OA-Fund TU Delft","en","journal article","Public Library of Science","","","","","","","","Mechanical, Maritime and Materials Engineering","Biomechanical Engineering","","","",""
"uuid:7b54bd2d-5f67-40e5-962d-e85d113950b8","http://resolver.tudelft.nl/uuid:7b54bd2d-5f67-40e5-962d-e85d113950b8","Geometry-based control of instability patterns in cellular soft matter","Janbaz, S.; Weinans, H.; Zadpoor, A.A.","","2016","Recent research has shown the potential of rationally designed geometrical features for controlling the functionality of advanced materials. Of particular recent interest has been the use of geometry for controlling the buckling behaviour of soft materials under compression. However, the effects of geometry may be mixed with those of the mechanical properties. In this paper, we present a specific class of 2D cellular soft matter for which the geometry, independent from the mechanical properties of the bulk material, activates the instability pathways of the material, thereby controlling the instability threshold and the instability mode (instability pattern). The geometrical parameters include those characterizing the shape of the voids and the porosity of the cellular solid. A critical strain that solely depends on the geometry controls the transition to instability. Depending on the above-mentioned geometrical parameters, the onset of instability is followed by either symmetric compaction or side buckling. We provide instability maps that relate the geometrical parameters to the critical strain and the instability mode of the presented cellular soft material. These open up the possibility of using geometry for programming the functionalities of materials.","Gold for Gold · Open Access","en","journal article","RSC Publishing","","","","","","","","Mechanical, Maritime and Materials Engineering","Biomechanical Engineering","","","",""
"uuid:2950ce7b-0daa-4789-a10d-366690d62fe7","http://resolver.tudelft.nl/uuid:2950ce7b-0daa-4789-a10d-366690d62fe7","Crossing Total Occlusions: Navigating Towards Recanalization","Sakes, A.; Regar, E.; Dankelman, J.; Breedveld, P.","","2016","Chronic total occlusions (CTOs) represent the “last frontier” of percutaneous interventions. The main technical challenges lies in crossing the guidewire into the distal true lumen, which is primarily due to three problems: device buckling during initial puncture, inadequate visualization, and the inability to actively navigate through the CTO. To improve the success rate and to identify future research pathways, this study systematically reviews the state-of-the-art of all existing and invented devices for crossing occlusions. The literature search was executed in the databases of Scopus and Espacenet using medical and instrument-related keyword combinations. The search yielded over 840 patents and 69 articles. After scanning for relevancy, 45 patents and 16 articles were included. The identified crossing devices were subdivided based on the determinant for the crossing path through the occlusion, which is either the device (straight and angled crossing), the environment (least resistance, tissue selective, centerline, and subintimal crossing) or the user (directly steered and sensor enhanced crossing). It was found that each crossing path is characterized by specific advantages and disadvantages. For a future crossing device, a combination of crossing paths is suggested were the interventionist is able to exert high forces on the CTO (as seen in the device approach) and actively steer through the CTO (user: directly steered crossing) aided by intravascular imaging (user: sensor enhanced crossing) or an intrinsically safe device following the centerline or path of least resistance (environment: centerline crossing or least resistance crossing) to reach the distal true lumen.","chronic total occlusions (CTO); crossing; percutaneous coronary intervention (PCI); state of the art; treatment; recanalization; review","en","journal article","Springer","","","","","","","","Mechanical, Maritime and Materials Engineering","Biomechanical Engineering","","","",""
"uuid:51557b9a-964b-43f6-a161-da72bd6a8317","http://resolver.tudelft.nl/uuid:51557b9a-964b-43f6-a161-da72bd6a8317","Anatomical parameters for musculoskeletal modeling of the hand and wrist","Mirakhorlo, M (Vrije Universiteit Amsterdam); Visser, J.M.A. (The Hague University of Applied Sciences); Goislard de Monsabert, B.A.A.X. (Imperial College London); van der Helm, F.C.T. (TU Delft Biomechatronics & Human-Machine Control); Maas, H. (Vrije Universiteit Amsterdam); Veeger, H.E.J. (TU Delft Biomechanical Engineering; TU Delft Biomechatronics & Human-Machine Control)","","2016","A musculoskeletal model of the hand and wrist can provide valuable biomechanical and neurophysiological insights, relevant for clinicians and ergonomists. Currently, no consistent data-set exists comprising the full anatomy of these upper extremity parts. The aim of this study was to collect a complete anatomical data-set of the hand and wrist, including the intrinsic and extrinsic muscles. One right lower arm, taken from a fresh frozen female specimen, was studied. Geometrical data for muscles and joints were digitized using a 3D optical tracking system. For each muscle, optimal fiber length and physiological cross-sectional area were assessed based on muscle belly mass, fiber length, and sarcomere length. A brief description of model, in which these data were imported as input, is also provided. Anatomical data including muscle morphology and joint axes (48 muscles and 24 joints) and mechanical representations of the hand are presented. After incorporating anatomical data in the presented model, a good consistency was found between outcomes of the model and the previous experimental studies.","musculoskeletal modeling; intrinsic muscles; extrinsic muscles; extensor mechanism","en","journal article","","","","","","","","","","Biomechanical Engineering","Biomechatronics & Human-Machine Control","","",""
"uuid:d2184a49-5950-4581-b691-7b5ae8c0e8a2","http://resolver.tudelft.nl/uuid:d2184a49-5950-4581-b691-7b5ae8c0e8a2","Wireless instrumented klapskates for long-track speed skating","van der Kruk, E. (TU Delft Biomechatronics & Human-Machine Control); Den Braver (student), O. (Student TU Delft); Schwab, A.L. (TU Delft Biomechatronics & Human-Machine Control); van der Helm, F.C.T. (TU Delft Biomechatronics & Human-Machine Control); Veeger, H.E.J. (TU Delft Biomechanical Engineering; TU Delft Biomechatronics & Human-Machine Control)","","2016","In the current project, we aim to provide speed skaters with real-time feedback on how to improve their skating performance within an individual stroke. The elite skaters and their coaches wish for a system that determines the mechanical power per stroke. The push-off force of the skater is a crucial variable in this power determination. In this study, we present the construction and calibration of a pair of wireless instrumented klapskates that can continuously and synchronously measure this push-off force in both the lateral direction and normal direction of the skate and the centre of pressure of these forces. The skate consists of a newly designed rigid bridge (0.6 kg), embedding two three-dimensional force sensors (Kistler 9602, Kistler Group, Winterthur, Switzerland), which fits between most individual skate shoes and Maple skate blades. The instrumented klapskates were calibrated on a tensile testing machine, where they proved to be unaffected to temperature conditions and accurate up to an RMS of 42 N (SEM = 1 N) in normal and up to an RMS of 27 N (SEM = 1 N) in lateral direction. Furthermore, the centre of pressure of these forces on the blade was determined up to a mean error of 10.1 mm (SD = 6.9 mm). On-ice measurements showed the possibility of recording with both skates simultaneously and synchronously, straights as well as curves. The option to send data wirelessly and real-time to other devices makes it possible to eventually provide skaters and coaches with visual real-time feedback during practice.","Calibration; Force measurements; Instrumentation design; Real-time feedback; Speed skating","en","journal article","","","","","","","","","","Biomechanical Engineering","Biomechatronics & Human-Machine Control","","",""
"uuid:85975d8f-3767-4214-aa4b-1707bbba85e2","http://resolver.tudelft.nl/uuid:85975d8f-3767-4214-aa4b-1707bbba85e2","From big data to rich data: The key features of athlete wheelchair mobility performance","van der Slikke, R.M.A. (TU Delft Biomechatronics & Human-Machine Control; The Hague University of Applied Sciences); Berger, MAM (The Hague University of Applied Sciences); Bregman, DJJ (TU Delft Research Funding National); Veeger, H.E.J. (TU Delft Biomechanical Engineering; TU Delft Biomechatronics & Human-Machine Control; Vrije Universiteit Amsterdam)","","2016","Quantitative assessment of an athlete׳s individual wheelchair mobility performance is one prerequisite needed to evaluate game performance, improve wheelchair settings and optimize training routines. Inertial Measurement Unit (IMU) based methods can be used to perform such quantitative assessment, providing a large number of kinematic data. The goal of this research was to reduce that large amount of data to a set of key features best describing wheelchair mobility performance in match play and present them in meaningful way for both scientists and athletes. To test the discriminative power, wheelchair mobility characteristics of athletes with different performance levels were compared. The wheelchair kinematics of 29 (inter-)national level athletes were measured during a match using three inertial sensors mounted on the wheelchair. Principal component analysis was used to reduce 22 kinematic outcomes to a set of six outcomes regarding linear and rotational movement; speed and acceleration; average and best performance. In addition, it was explored whether groups of athletes with known performance differences based on their impairment classification also differed with respect to these key outcomes using univariate general linear models. For all six key outcomes classification showed to be a significant factor (p<0.05). We composed a set of six key kinematic outcomes that accurately describe wheelchair mobility performance in match play. The key kinematic outcomes were displayed in an easy to interpret way, usable for athletes, coaches and scientists. This standardized representation enables comparison of different wheelchair sports regarding wheelchair mobility, but also evaluation at the level of an individual athlete. By this means, the tool could enhance further development of wheelchair sports in general.","Wheelchair basketball; Wheelchair sports; Wheelchair mobility performance; Inertial Measurement Unit","en","journal article","","","","","","Accepted Author Manuscript","","2017-10-03","","Biomechanical Engineering","Biomechatronics & Human-Machine Control","","",""
"uuid:6c16daa1-bd15-44d5-98bb-f2ea309579d9","http://resolver.tudelft.nl/uuid:6c16daa1-bd15-44d5-98bb-f2ea309579d9","Longitudinal changes in shoulder ROM and strength in association with ball-throwing speed in elite youth baseball pitchers","van Dis, F. (Vrije Universiteit Amsterdam); Hoozemans, M (Vrije Universiteit Amsterdam); van der Graaff, E (Vrije Universiteit Amsterdam); Veeger, H.E.J. (TU Delft Biomechanical Engineering; TU Delft Biomechatronics & Human-Machine Control; Vrije Universiteit Amsterdam)","","2016","The purpose of this prospective study was to examine the longitudinal changes in shoulder ER ROM and relative IR strength in elite youth baseball pitchers over one year and to determine their associations with changes in ball speed for throwing fastballs. One hundred and five Dutch elite youth baseball pitchers were measured three times over a period of one year. Statistical analyses of the data revealed that changes in ER ROM and relative IR strength were not significantly associated with changes in ball-throwing speed.","baseball; pitching; performance; screening; prospective study","en","conference paper","International Society of Biomechanics in Sports","","","","","","","","","Biomechanical Engineering","Biomechatronics & Human-Machine Control","","",""
"uuid:5a73fac3-e273-47cb-bab3-a6d79d665a43","http://resolver.tudelft.nl/uuid:5a73fac3-e273-47cb-bab3-a6d79d665a43","New methods for mobility performance measurement in wheelchair basketball","van der Slikke, R.M.A. (TU Delft Biomechatronics & Human-Machine Control; The Hague University of Applied Sciences); Berger, MAM (The Hague University of Applied Sciences); Bregman, DJJ (TU Delft Research Funding National); Veeger, H.E.J. (TU Delft Biomechanical Engineering; TU Delft Biomechatronics & Human-Machine Control; Vrije Universiteit Amsterdam)","","2016","Increased professionalism in wheelchair sports demand a more precise and quantitative measure of individual wheelchair mobility performance, to allow it to be an evaluation measure of wheelchair setting or training optimization. This research describes the application of an inertial sensor based method for measuring wheelchair kinematics and a factor analysis based selection of outcomes best describing wheelchair mobility performance. This set of kinematic outcomes was analysed for sensitivity towards wheelchair performance differences due to competition level and classification of the match data of 29 wheelchair basketball athletes. The method proved sensitive and is believed to provide a solid basis for a kinematics based definition of wheelchair mobility performance in sports.","Inertial Measurement Unit; Wheelchair Sports; Wheelchair Performance","en","conference paper","International Society of Biomechanics in Sports","","","","","","","","","Biomechanical Engineering","Biomechatronics & Human-Machine Control","","",""
"uuid:14ec680b-326e-4192-9e0b-08fb63773205","http://resolver.tudelft.nl/uuid:14ec680b-326e-4192-9e0b-08fb63773205","Ball velocity and elbow loading in fastball pitching","Gasparutto, X. (TU Delft Biomechatronics & Human-Machine Control); van der Graaff, E (Vrije Universiteit Amsterdam); Veeger, H.E.J. (TU Delft Biomechanical Engineering; TU Delft Biomechatronics & Human-Machine Control; Vrije Universiteit Amsterdam); van der Helm, F.C.T. (TU Delft Biomechatronics & Human-Machine Control)","","2016","Among baseball players, the pitchers are the most prone to injuries. These injuries occur mainly at the medial part of the elbow and at the shoulder. It is widely accepted that high joint loading are linked to overuse injury for repetitive motion. At maximal exo-rotation (MER), the elbow maximal abduction moment is predominantly counteracted by the ulnar collateral ligament and causes great stress on this structure. The aim of this study is to investigate the relationship between the elbow maximal abduction moment, ball velocity and technique. Thirteen elite pitchers participated in this study. Elbow maximal abduction moment was computed by an inverse dynamics method. Results indicate that the mean maximal abduction moment of the forearm on the upper arm was 41+-9Nm and can be reduced without hampering ball velocity by lowering the elbow flexion angle at MER.","baseball pitching; injury; elbow loading; ball velocity","en","conference paper","International Society of Biomechanics in Sports","","","","","","","","","Biomechanical Engineering","Biomechatronics & Human-Machine Control","","",""
"uuid:74d0ddde-89bf-49db-99b2-7b9f1e26c3cf","http://resolver.tudelft.nl/uuid:74d0ddde-89bf-49db-99b2-7b9f1e26c3cf","The role of pelvis and thorax rotation velocity in baseball pitching","van der Graaff, E (Vrije Universiteit Amsterdam); Hoozemans, M (Koninklijke Nederlandse Baseball en Softball Bond (KNBSB)); Nijhoff, M. (Koninklijke Nederlandse Baseball en Softball Bond (KNBSB)); Davidson, M (Manual Fysion); Hoezen, M (Manual Fysion); Veeger, H.E.J. (TU Delft Biomechanical Engineering; TU Delft Biomechatronics & Human-Machine Control; Vrije Universiteit Amsterdam)","","2016","The objective of the present study was to examine the relative timing of pelvis and thorax rotations in achieving high throwing velocities in baseball pitching. During the preseason, a kinematic analysis was performed on eight pitchers. Peak angular velocities of the pelvis and thorax were determined and separation, defined as the time between the moments of maximal rotation velocity of the pelvis and thorax, was calculated. By themselves, maximal pelvis and thorax rotation velocity were not associated with throwing velocity. Separation was positively and significantly associated with throwing velocity. Results indicate that the relative timing of pelvis and thorax peak rotation velocity in pitching fastballs in baseball is a determinant of throwing velocity in skilled pitchers.","biomechanics; kinematics; performance; pitching; separation","en","conference paper","International Society of Biomechanics in Sports","","","","","","","","","Biomechanical Engineering","Biomechatronics & Human-Machine Control","","",""
"uuid:306bc477-9f41-42fd-a12e-97b2eac20efc","http://resolver.tudelft.nl/uuid:306bc477-9f41-42fd-a12e-97b2eac20efc","Giving the force direction: Analysis of speed skater push off forces with respect to an inertial coordinate system","van der Kruk, E. (TU Delft Biomechatronics & Human-Machine Control); van der Helm, F.C.T. (TU Delft Biomechatronics & Human-Machine Control); Schwab, A.L. (TU Delft Biomechatronics & Human-Machine Control); Veeger, H.E.J. (TU Delft Biomechanical Engineering; TU Delft Biomechatronics & Human-Machine Control)","","2016","Pushoff in speed skating requires an extensive motion strategy. During speed skating the skater continuously changes the lean and steering angle of the skate and therewith the direction of push-off, The forces in an inertial coordinate system can give insight into what amount of the push-off force is directed into the forward motion. In this paper we present the preliminary results of a study on the global forces in speed skating. From a mechanical viewpoint, increasing the lean angle of the skate seems beneficial at the end of the stroke, but detrimental at the start of the stroke. Furthermore the necessity of the
lateral force on the skate in the overall force production is a variable of interest for further investigation, since dynamically it has a disadvantageous effect on the forward motion.","Speed Skating; Winter Sports; Kinematics; Kinetics; Power","en","conference paper","International Society of Biomechanics in Sports","","","","","","","","","Biomechanical Engineering","Biomechatronics & Human-Machine Control","","",""
"uuid:aca98617-e8d1-4137-8680-24a952e4431b","http://resolver.tudelft.nl/uuid:aca98617-e8d1-4137-8680-24a952e4431b","Prevalence of self-reported stroke in association with ethnic background within a multi-ethnic population in Paramaribo, Suriname: Results from the helisur study","Jarbandhan, Ameerani V. (Katholieke Universiteit Leuven; Anton de Kom University of Suriname); Hoozemans, Marco J.M. (Vrije Universiteit Amsterdam); Buys, Roselien (Katholieke Universiteit Leuven); Diemer, Frederieke S. (Academic Hospital of Paramaribo); Baldew, Se Sergio M. (Katholieke Universiteit Leuven); Aartman, Jet (Universiteit van Amsterdam); Brewster, Lizzy M. (Universiteit van Amsterdam); Van Montfrans, Gert A. (Universiteit van Amsterdam); Oehlers, Glenn P. (Academic Hospital of Paramaribo); Veeger, H.E.J. (TU Delft Biomechanical Engineering; TU Delft Biomechatronics & Human-Machine Control); Toelsie, Jerry (Anton de Kom University of Suriname); Vanhees, Luc (Katholieke Universiteit Leuven)","","2016","Background: Suriname is a middle-income country with a multi-ethnic population. Urbanization and ethnicity may be associated with incidence of cerebrovascular disease, but so far this has not been documented for Suriname. The objective of this study was to examine the prevalence of stroke in the capital of Suriname, and its association with ethnicity. Methods: Using the self-reported data from the ‘Healthy life in Suriname’ (HeliSur) study, we determined the prevalence of stroke in 1,478 subjects. The odds for having suffered from stroke in Javanese, Maroons and Creoles were separately compared to the odds in Hindustani. Odds ratios were adjusted for traditional risk factors including age, sex, diabetes, hypertension, dyslipidemia, and smoking, by use of multiple logistic regression analysis. Results:The overall prevalence of stroke in urban Surinameis 3.2% (95% CI 2.3 to 4.0%). Hindustani reported the highest prevalence of stroke (4.1%, 95% CI 2.4 to 5.8%) compared to the Javanese (2.0%, 95% CI 0 to 4.0%), Creoles (3.6%, 95% CI 2.7 to 4.5%) and Maroons (1.8%, 95% CI 0.5 to 3.1%). Adjusted odds ratios showed no significant association between ethnic background and stroke. Conclusions: Stroke prevalence is high in urban Suriname, and there seems to be ethnic difference in its prevalence. However, with and without adjustments for traditional risk factors, no significant association between stroke and ethnicity could be shown.","","en","journal article","","","","","","","","","","Biomechanical Engineering","Biomechatronics & Human-Machine Control","","",""
"uuid:0b411453-48ba-4ba9-b21d-a4576479c4c8","http://resolver.tudelft.nl/uuid:0b411453-48ba-4ba9-b21d-a4576479c4c8","Push characteristics in wheelchair court sport sprinting","van der Slikke, R.M.A. (TU Delft Biomechatronics & Human-Machine Control; The Hague University of Applied Sciences); Berger, Monique (The Hague University of Applied Sciences); Bregman, D.J.J. (TU Delft Research Funding National); Veeger, H.E.J. (TU Delft Biomechanical Engineering; TU Delft Biomechatronics & Human-Machine Control; Vrije Universiteit Amsterdam)","van der Helm, FCT (editor); Jansen, AJ (editor)","2016","Short sprints are important components of most wheelchair court sports, since being faster than the opponent often determines keeping ball possession or not. Sprinting capacity is best measured during a field test, allowing the athlete to freely choose push strategies adapted to their own wheelchair setting, physical ability, classification and speed changes during a sprint. The key test outcome is sprint duration, but there are various ways to accomplish the same sprint time. So can different push strategies be identified in a wheelchair sport and how do they relate to athlete level/classification and wheelchair configuration? These relationships were investigated by field tests of 30 male wheelchair basketball athletes during a 12 meter sprint in their own wheelchair. A recently developed method for ambulatory measurement was used to calculate wheelchair kinematics [1], providing outcomes on displacement, speed, acceleration and pushes. Additionally maximal isometric push force was recorded and rear seat height was noted. Within the measured athletes, internationals were expected to be faster due to a better physical training status and technique, allowing them to sprint with fewer (but more powerful) pushes. Likewise, athletes of higher classification were expected to be faster due their superior physical capacity, but the effect on the number of pushes used was not that evident. Video analysis was added to validate push detection of the ambulatory measurement system. Mutual correlations and competition level differences of sprint characteristics were calculated. General Linear Models (GLM) were drawn to determine the effect of competition level and classification on sprint time and number of pushes. In the overall dataset sprint characteristics did not correlate significantly with classification, but if split by competition level, there were significant correlations with sprint time (r=-0.715, p=0.006) and number of pushes (r=-0.647, p= 0.017) in the national level athletes. Sprint time, number of pushes and isometric push force differed significantly between national and international level wheelchair basketball athletes. Competition level showed to be a significant (","Inertial Measurement Unit; Instrumented wheelchair; Push detection; Wheelchair Basketball; Wheelchair kinematics","en","conference paper","Elsevier","","","","","","","","","Biomechanical Engineering","Biomechatronics & Human-Machine Control","","",""
"uuid:58d7c8ab-ab11-4dbb-a93c-b1c71a01615f","http://resolver.tudelft.nl/uuid:58d7c8ab-ab11-4dbb-a93c-b1c71a01615f","Getting the angles straight in speed skating: A validation study on an IMU filter design to measure the lean angle of the skate on the straights","van der Kruk, E. (TU Delft Biomechatronics & Human-Machine Control); Schwab, A.L. (TU Delft Biomechatronics & Human-Machine Control); van der Helm, F.C.T. (TU Delft Biomechatronics & Human-Machine Control); Veeger, H.E.J. (TU Delft Biomechanical Engineering; TU Delft Biomechatronics & Human-Machine Control)","van der Helm, FCT (editor); Jansen, AJ (editor)","2016","To assist speed skaters in improving their skating performance, we would like to provide them with real time feedback on the orientation of the skate within a single stroke. While of course the forces generated by the skater on the ice determine the acceleration of the skater, the orientation of the skate determines in which direction this force, and thus acceleration, is headed. In this study we focus on the validation of the lean angle measurements of the skate, which distributes the push-off forces over the global vertical and transverse component. To measure this angle, an inertial measurement unit (IMU) would be a logical choice, but two aspects render measuring with commercially available IMUs and their filters on an ice rink rather difficult, first the ferromagnetic materials in the vicinity of the IMU and secondly the large linear accelerations. In this paper we therefore propose filters that bypass these problems. In total three complementary filters with adaptive gain were validated with a motion capture system. The filter based on the assumption that the lean angle can be reset to zero (upright) when there is no change in steer angle of the skate, showed the most accurate results (mean RMSE error of 5.30 and 3.60, for the left and right skate respectively). Integrated into the filter is an IMU based stroke detection, which as a stand-alone system could provide feedback on stroke frequency, stroke length, contact time or double stance phase time. It is concluded that an IMU used with this filter can provide individual elite speed skaters reliable feedback on their skate lean angle.","IMU; Lean Angle; Speed Skating; Validation measurements","en","conference paper","Elsevier","","","","","","","","","Biomechanical Engineering","Biomechatronics & Human-Machine Control","","",""
"uuid:1c19114a-cf60-4d80-a133-fe4fd477dba7","http://resolver.tudelft.nl/uuid:1c19114a-cf60-4d80-a133-fe4fd477dba7","Elite athlete motor and loading actions on the upper limb in baseball pitching","Gasparutto, X. (TU Delft Biomechatronics & Human-Machine Control); Van Der Graaff, E. (Vrije Universiteit Amsterdam); van der Helm, F.C.T. (TU Delft Biomechatronics & Human-Machine Control); Veeger, H.E.J. (TU Delft Biomechanical Engineering; TU Delft Biomechatronics & Human-Machine Control; Vrije Universiteit Amsterdam)","van der Helm, FCT (editor); Jansen, AJ (editor)","2016","In baseball, pitchers are the players that are most prone to injury. Most injuries occur at the elbow and shoulder of the throwing upper limb. It is widely accepted that understanding the loading in the joints during pitching is a key factor to prevent injuries. To deepen the understanding of the joint actions this study proposes to split the net joint actions into two part: the motor actions and the stability actions representing respectively the actions generating the joint motion and the actions maintaining the joint integrity. The actions represent the actions applied on the distal segment of the joint. Eight youth elite pitchers participated the study and performed 5 fastball pitches while equipped with skin markers. Three pitches per pitchers were used to compute the joint actions with an inverse dynamics method. The results indicate at the elbow a maximal elbow stability moment in adduction (52±5Nm) on the lower arm at maximal external rotation and a motor action in flexion (38±10Nm) during the acceleration phase. At maximal internal rotation the maximal stability shoulder loading occurred, with a pulling force of 520±80N, a downward force of -290±95N and a depression moment of 65±17Nm. The motor actions at the shoulder were mainly a forward force (93±46N) and an exorotation moment (24±12Nm) during the arm acceleration phase. This study suggest that the main action of the shoulder is to stabilise the joint, with a maximal load at maximal internal rotation, and that the main action at the elbow is avoiding hyperextension, with a critical phase at maximal external rotation. Further study is needed to link the stability actions to injury risk.","baseball; elbow; joint loading; joint moment; pitching; shoulder","en","conference paper","Elsevier","","","","","","","","","Biomechanical Engineering","Biomechatronics & Human-Machine Control","","",""
"uuid:7958a3ef-2775-4d8a-a326-4a4a12db4e8f","http://resolver.tudelft.nl/uuid:7958a3ef-2775-4d8a-a326-4a4a12db4e8f","Corrigendum: EEG beta suppression and low gamma modulation are different elements of human upright walking","Seeber, M.; Scherer, R.; Wagner, J.; Solis Escalante, T.; Müller-Putz, G.R.","","2015","A corrigendum on EEG beta suppression and low gamma modulationare different elements of human upright walking by Seeber,M.,Scherer,R.,Wagner,J.,Solis-Escalante,T.,andMüller-Putz,G.R.(2014)Front.Hum. Neurosci.8:485.doi:10.3389/fnhum.2014.00485","electroencephalography(EEG); gait; brainmapping; motor cortex; magnetic resonance imaging","en","journal article","Frontiers","","","","","","","","Mechanical, Maritime and Materials Engineering","Biomechanical Engineering","","","",""
"uuid:51e6856c-a6fb-4f3c-8673-dfac8f434cc7","http://resolver.tudelft.nl/uuid:51e6856c-a6fb-4f3c-8673-dfac8f434cc7","A literature review on human factors research using motorcycle simulators (poster)","Kovacsova, N.; Di Gesu, M.; Schwab, A.L.; Gubitosa, M.; Hagenzieker, M.P.; De Winter, J.C.F.","","2015","","","en","journal article","TU Delft","","","","","","","","Mechanical, Maritime and Materials Engineering","Biomechanical Engineering","","","",""
"uuid:9641039c-21cc-4f21-8605-11c68d5cc5e9","http://resolver.tudelft.nl/uuid:9641039c-21cc-4f21-8605-11c68d5cc5e9","Dynamic functional brain connectivity for face perception","Yang, Y.; Qiu, Y.; Schouten, A.C.","","2015","","face perception; dynamic functional connectivity; high-density EEG; phase lag index; ERP","en","journal article","Frontiers Media","","","","","","","","Mechanical, Maritime and Materials Engineering","BioMechanical Engineering (BME)","","","",""
"uuid:23a62bc5-57bc-4d15-9b33-dfaf0c6069e8","http://resolver.tudelft.nl/uuid:23a62bc5-57bc-4d15-9b33-dfaf0c6069e8","A literature review on human factors research using motorcycle simulators","Kovacsova, N.; Di Gesu, M.; Schwab, A.L.; Gubitosa, M.; Hagenzieker, M.P.; De Winter, J.C.F.","","2015","","powered two wheeler (PTW); simulation; rider assessment; rider training; assistance systems","en","conference paper","Max Planck Institute for Biological Cybernetics","","","","","","","","Mechanical, Maritime and Materials Engineering","Biomechanical Engineering","","","",""
"uuid:8fd2763c-6eea-48a0-a11b-b4c740058427","http://resolver.tudelft.nl/uuid:8fd2763c-6eea-48a0-a11b-b4c740058427","Airway segmentation and centerline extraction from thoracic CT: Comparison of a new method to state of the art commercialized methods","Reynisson, P.J.; Scali, M.; Smistad, E.; Hofstad, E.F.; Leira, H.O.; Lindseth, F.; Nagelhus Hernes, T.A.; Amundsen, T.; Sorger, H.; Lango, T.","","2015","Our motivation is increased bronchoscopic diagnostic yield and optimized preparation, for navigated bronchoscopy. In navigated bronchoscopy, virtual 3D airway visualization is often used to guide a bronchoscopic tool to peripheral lesions, synchronized with the real time video bronchoscopy. Visualization during navigated bronchoscopy, the segmentation time and methods, differs. Time consumption and logistics are two essential aspects that need to be optimized when integrating such technologies in the interventional room. We compared three different approaches to obtain airway centerlines and surface.","","en","journal article","","","","","","","","","Mechanical, Maritime and Materials Engineering","BioMechanical Engineering (BME)","","","",""
"uuid:79689f0a-cb02-46d8-95eb-0743397a1f48","http://resolver.tudelft.nl/uuid:79689f0a-cb02-46d8-95eb-0743397a1f48","Effect of steering model fidelity on subjective evaluation of truck steering feel","Shyrokau, B.; Loof, J.; Stroosma, O.; Wang, M.; Happee, R.","","2015","The steering behaviour in a driving simulator has a significant influence on a driving realism. This study investigates the influence of the complexity of a steering-system model on the subjective assessment of truck steering feel in on-centre handling. Ten subjects drove a highway task with and without lateral wind disturbance with 4 steering-system model variants. The results show that detailed modelling of the steering system plays a significant role in the subjective assessment of truck steering feel, and has a corresponding effect on objective steering performance.","truck steering wheel; steering model; subjective assessment; on-centre handling; driving simulator","en","conference paper","Max Planck Institute for Biological Cybernetics","","","","","","","","Mechanical, Maritime and Materials Engineering","Biomechanical Engineering","","","",""
"uuid:283edffc-dac7-45a9-a83b-92b5f7dcc6c8","http://resolver.tudelft.nl/uuid:283edffc-dac7-45a9-a83b-92b5f7dcc6c8","A novel ultrasound technique for detection of osteochondral defects in the ankle joint: A parametric and feasibility study","Sarkalkan, N.; Loeve, A.J.; Van Dongen, K.W.A.; Tuijthof, G.J.M.; Zadpoor, A.A.","","2015","(Osteo)chondral defects (OCDs) in the ankle are currently diagnosed with modalities that are not convenient to use in long-term follow-ups. Ultrasound (US) imaging, which is a cost-effective and non-invasive alternative, has limited ability to discriminate OCDs. We aim to develop a new diagnostic technique based on US wave propagation through the ankle joint. The presence of OCDs is identified when a US signal deviates from a reference signal associated with the healthy joint. The feasibility of the proposed technique is studied using experimentally-validated 2D finite-difference time-domain models of the ankle joint. The normalized maximum cross correlation of experiments and simulation was 0.97. Effects of variables relevant to the ankle joint, US transducers and OCDs were evaluated. Variations in joint space width and transducer orientation made noticeable alterations to the reference signal: normalized root mean square error ranged from 6.29% to 65.25% and from 19.59% to 8064.2%, respectively. The results suggest that the new technique could be used for detection of OCDs, if the effects of other parameters (i.e., parameters related to the ankle joint and US transducers) can be reduced.","diagnosis; (osteo)chondral defect; ankle joint; joint space; ultrasound propagation; 2D finite-difference time-domain model; OA-Fund TU Delft","en","journal article","MDPI","","","","","","","","Mechanical, Maritime and Materials Engineering","Biomechanical Engineering","","","",""
"uuid:75bd8b41-2bb2-4cd3-aa40-bbb7c8414d6f","http://resolver.tudelft.nl/uuid:75bd8b41-2bb2-4cd3-aa40-bbb7c8414d6f","Robust Hand Motion Tracking through Data Fusion of 5DT Data Glove and Nimble VR Kinect Camera Measurements","Arkenbout, E.A.; De Winter, J.C.F.; Breedveld, P.","","2015","Vision based interfaces for human computer interaction have gained increasing attention over the past decade. This study presents a data fusion approach of the Nimble VR vision based system, using the Kinect camera, with the contact based 5DT Data Glove. Data fusion was achieved through a Kalman filter. The Nimble VR and filter output were compared using measurements performed on (1) a wooden hand model placed in various static postures and orientations; and (2) three differently sized human hands during active finger flexions. Precision and accuracy of joint angle estimates as a function of hand posture and orientation were determined. Moreover, in light of possible self-occlusions of the fingers in the Kinect camera images, data completeness was assessed. Results showed that the integration of the Data Glove through the Kalman filter provided for the proximal interphalangeal (PIP) joints of the fingers a substantial improvement of 79% in precision, from 2.2 deg to 0.9 deg. Moreover, a moderate improvement of 31% in accuracy (being the mean angular deviation from the true joint angle) was established, from 24 deg to 17 deg. The metacarpophalangeal (MCP) joint was relatively unaffected by the Kalman filter. Moreover, the Data Glove increased data completeness, thus providing a substantial advantage over the sole use of the Nimble VR system.","human-computer interaction; Kalman filter; data fusion; gestures; finger joint angle measurements; sensor redundancy; OA-Fund TU Delft","en","journal article","MDPI","","","","","","","","Mechanical, Maritime and Materials Engineering","Biomechanical Engineering","","","",""
"uuid:f9d46e00-34c9-443e-b437-72c651a540a2","http://resolver.tudelft.nl/uuid:f9d46e00-34c9-443e-b437-72c651a540a2","Exploiting Dynamics in robotic arms with repetitive tasks","Plooij, M.C.","Van der Helm, F.C.T. (promotor); Wisse, M. (promotor)","2015","Since the industrial revolution, machines have taken over many tasks from humans, increasing labor productivity and prosperity. In the 20th century, the introduction of robots created a second wave of automation, increasing the labor productivity even further. In order to create a third wave of automation, it is necessary to develop a new generation of robots that is able to act in unknown, unstructured environments, such as households, space and factories in which humans and robots collaborate. Two of the main aspects of robots that have to be improved in order to be successful are their energy consumption and their reliability. This thesis is split into two parts. The first part focuses on reducing the energy consumption of robots by using elasticity. The second part focuses on increasing the reliability by using feedforward control. Throughout this thesis, we focus on one type of robot: robotic arms with repetitive tasks, such as pick-and-place tasks.","robots; dynamics; energy; reliability; control; springs","en","doctoral thesis","","","","","","","","2016-06-09","Mechanical, Maritime and Materials Engineering","BioMechanical Engineering","","","",""
"uuid:e54b829b-95d7-426d-8c7b-07d834b5edd5","http://resolver.tudelft.nl/uuid:e54b829b-95d7-426d-8c7b-07d834b5edd5","Where are my instruments? Hazards in delivery of surgical instruments","Guédon, A.C.P.; Wauben, L.S.G.L.; Van der Eijk, A.C.; Vernooij, A.S.N.; Meeuwsen, F.C.; Van der Elst, M.; Hoeijmans, V.; Dankelman, J.; Van den Dobbelsteen, J.J.","","2015","Background Unavailability of instruments is recognised to cause delays and stress in the operating room, which can lead to additional risks for the patients. The aim was to provide an overview of the hazards in the entire delivery process of surgical instruments and to provide insight into how Information Technology (IT) could support this process in terms of information availability and exchange. Methods The process of delivery was described according to the Healthcare Failure Mode and Effects Analysis methodology for two hospitals. The different means of information exchange and availability were listed. Then, hazards were identified and further analysed for each step of the process. Results For the first hospital, 172 hazards were identified, and 23 of hazards were classified as high risk. Only one hazard was considered as ‘controlled’ (when actions were taken to remove the hazard later in the process). Twenty-two hazards were ‘tolerated’ (when no actions were taken, and it was therefore accepted that adverse events may occur). For the second hospital, 158 hazards were identified, and 49 of hazards were classified as high risk. Eight hazards were ‘controlled’ and 41 were ‘tolerated’. The means for information exchange and information systems were numerous for both cases, while there was not one system that provided an overview of all relevant information. Conclusions The majority of the high-risk hazards are expected to be controlled by the use of IT support. Centralised information and information availability for different parties reduce risks related to unavailability of instruments in the operating room.","surgical instruments; safety; risk analysis; information technology; logistics","en","journal article","Springer","","","","","","","","Mechanical, Maritime and Materials Engineering","Biomechanical Engineering","","","",""
"uuid:2c595513-a149-4d0f-b45a-be192885efc4","http://resolver.tudelft.nl/uuid:2c595513-a149-4d0f-b45a-be192885efc4","Active Vision for Humanoid Robots","Wang, X.","Jonker, P.P. (promotor)","2015","Human perception is an active process. By altering its viewpoint rather than passively observing surroundings and by operating on sequences of images rather than on a single frame, the human visual system has the ability to explore the most relevant information based on knowledge, therefore when growing up a human is able to develop cognitive perception. Comparably, for humanoid robots to develop cognitive perception, active vision is indispensable. Humanoid robot research has already nearly half a century history. There are approximately 2000 research papers on active vision published during 1986?2010 that covered a large range of research fields in robotics. Nowadays, the new trend is to use a stereo setup or a Kinect with neck movements to realize active vision. However, human perception is a combination of eyes and neck movement. In order to design such an advanced humanoid active vision system, eye movements with biological inspiration similar to human eyes should be taken into consideration. Depth perception based on pure image information can then be obtained without utilizing any advanced sensors. This thesis presents a complete active vision system with 4 degrees of freedom that works in a similar way as human vision. It is composed of the following parts: 1. The mechanical design has 4 motors with independent vergence angle control, one tilt motor for both eyes and one pan motor for the neck. 2. The controllers simulate the eye movements as humans: saccade eye movements, pursuit eye movements, vestibulo-ocular reflex (VOR) eye movements and vergence eye movements, where motor positions and velocities are controlled with input from an Inertia Measurement Unit (IMU). 3. An optimal feature selection mechanism which is based on various properties of objects is applied before tracking. 4. In order to smoothly pursue and learn an object from different perspectives, three different trackers are used: a color based tracker, an AR marker based tracker for testing, and a robust online tracker. 5. A saliency detector segments the most dominant objects from the scenes and a robust online tracker provides refined segmentations. As a result, the robots have a self-explorative ability for unknown environments. 6. Owing to vergent eyes moving at different angles, intrinsic calibration as well as extrinsic calibration is required to ensure the accuracy of 3D perception. Here the motor positions are utilized together with a robust M-Estimator to recover the geometry between two eyes. 7. Humans utilize multiple cues for depth perception. Depth perception is strongly related to eye movements. Multi-mode depth perception is applied to perceive environment and objects in 3D for further vision tasks such as object recognition, and object grasping. The realized system works within real-time constraints and with low cost cameras and motors. Therefore it provides an affordable solution for industrial applications. In conclusion, active vision can be applied to various applications and it is a rapid-growing research domain. This thesis and its proposed vision system provides an insight into the research field of active humanoid robot vision.","active vision; humanoid robots; object tracking and segmentation; vergence eye movements; convergence; smooth pursuit eye movements; stereopsis; optimal feature selection; saccadic eye movements","en","doctoral thesis","","","","","","","","","Mechanical, Maritime and Materials Engineering","BioMechanical Engineering","","","",""
"uuid:c52dc04c-073c-4cc9-bc5a-8a4595e45326","http://resolver.tudelft.nl/uuid:c52dc04c-073c-4cc9-bc5a-8a4595e45326","Estimation of the mechanical loading of the shoulder joint in daily conditions","De Vries, W.H.K.","Van der Helm, F.C.T. (promotor); Veeger, H.E.J. (promotor)","2015","The goal of this thesis is to assemble a method to estimate shoulder joint reaction forces, in daily conditions, based on long term collection of ambulatory measurable variables, to obtain the desired long term mechanical load profile of the shoulder. Chapter 2 examines, and discusses one of the general assumptions used in IMMS is: the homogeneousness of the earth magnetic field. Chapter 3 describes a method and its accuracy in obtaining anatomically interpretable coordinate systems for the segments of the upper extremity using only IMMS, under daily conditions. Chapter 4 describes an experiment in which the NN method is used to predict input for a musculoskeletal model, to obtain ambulatory joint loading in more detail. Chapter 5 explores the direct prediction of joint reaction forces at the glenohumeral head. Several factors which might influence the predictive power of neural networks are examined. In Chapter 6 the method is discussed on its strengths and weaknesses, and the feasibility for obtaining a detailed joint load profile under daily conditions. This chapter ends with future directions to improve the method or tailor it to more specific research questions.","Shoulder Joint Reaction Force; Ambulatory; Neural Networks; IMMS (Inertial Magnetic Measurement Systems)","en","doctoral thesis","","","","","","","","","Mechanical, Maritime and Materials Engineering","BioMechanical Engineering","","","",""
"uuid:020881a3-c83b-42dc-93c8-b42475f1baa5","http://resolver.tudelft.nl/uuid:020881a3-c83b-42dc-93c8-b42475f1baa5","Delays in admittance-controlled haptic devices make simulated masses feel heavier","Kuling, I.A.; Smeets, J.B.J.; Lammertse, P.; Onneweer, B.; Mugge, W.","","2015","In an admittance-controlled haptic device, input forces are used to calculate the movement of the device. Although developers try to minimize delays, there will always be delays between the applied force and the corresponding movement in such systems, which might affect what the user of the device perceives. In this experiment we tested whether these delays in a haptic human-robot interaction influence the perception of mass. In the experiment an admittance-controlled manipulator was used to simulate various masses. In a staircase design subjects had to decide which of two virtual masses was heavier after gently pushing them leftward with the right hand in mid-air (no friction, no gravity). The manipulator responded as quickly as possible or with an additional delay (25 or 50 ms) to the forces exerted by the subject on the handle of the haptic device. The perceived mass was ~10% larger for a delay of 25 ms and ~20% larger for a delay of 50 ms. Based on these results, we estimated that the delays that are present in nowadays admittance-controlled haptic devices (up to 20ms) will give an increase in perceived mass which is smaller than the Weber fraction for mass (~10%for inertial mass). Additional analyses showed that the subjects’ decision on mass when the perceptual differences were small did not correlate with intuitive variables such as force, velocity or a combination of these, nor with any other measured variable, suggesting that subjects did not have a consistent strategy during guessing or used other sources of information, for example the efference copy of their pushes.","","en","journal article","","","","","","","","","Mechanical, Maritime and Materials Engineering","Biomechanical Engineering","","","",""
"uuid:7b8a8c2f-9c46-4a69-a97c-424ae56dd4a5","http://resolver.tudelft.nl/uuid:7b8a8c2f-9c46-4a69-a97c-424ae56dd4a5","NeuroControl of movement: System identification approach for clinical benefit","Meskers, C.G.M.; De Groot, J.; De Vlugt, E.; Schouten, A.C.","","2015","Progress in diagnosis and treatment of movement disorders after neurological diseases like stroke, cerebral palsy (CP), dystonia and at old age requires understanding of the altered capacity to adequately respond to physical obstacles in the environment. With posture and movement disorders, the control of muscles is hampered, resulting in aberrant force generation and improper impedance regulation. Understanding of this improper regulation not only requires the understanding of the role of the neural controller, but also attention for: (1) the interaction between the neural controller and the “plant”, comprising the biomechanical properties of the musculaskeletal system including the viscoelastic properties of the contractile (muscle) and non-contractile (connective) tissues: neuromechanics; and (2) the closed loop nature of neural controller and biomechanical system in which cause and effect interact and are hence difficult to separate. Properties of the neural controller and the biomechanical system need to be addressed synchronously by the combination of haptic robotics, (closed loop) system identification (SI), and neuro-mechanical modeling. In this paper, we argue that assessment of neuromechanics in response to well defined environmental conditions and tasks may provide for key parameters to understand posture and movement disorders in neurological diseases and for biomarkers to increase accuracy of prediction models for functional outcome and effects of intervention.","afferent feedback modulation; neuromechanics; system identification; ageing; stroke; movement disorders","en","journal article","Frontiers","","","","","","","","Mechanical, Maritime and Materials Engineering","Biomechanical Engineering","","","",""
"uuid:b0e90b4e-13a8-4e6e-8e3a-f326e32ddbfa","http://resolver.tudelft.nl/uuid:b0e90b4e-13a8-4e6e-8e3a-f326e32ddbfa","Wheel skid correction is a prerequisite to reliably measure wheelchair sports kinematics based on inertial sensors","Van der Slikke, R.M.A.; Berger, M.A.M.; Bregman, D.J.J.; Veeger, H.E.J.","","2015","Accurate knowledge of wheelchair kinematics during a match could be a significant factor in performance improvement in wheelchair basketball. To date, most systems for measuring wheelchair kinematics are not suitable for match applications or lack detail in key kinematic outcomes. This study describes the construction of wheel skid correction algorithms when using a three inertial measurement unit (IMUs) configuration for estimating wheelchair kinematics. The reliability of the skid corrected outcomes was assessed in wheelchair basketball match-like conditions. Twenty participants performed a series of tests reflecting different motion aspects of wheelchair basketball. IMU based estimations were compared to the outcomes of a 24-camera optical motion analysis system serving as gold standard. Once the skid correction algorithms were applied, estimation errors were reduced up to 4% of their original magnitude. Calculated Root Mean Square Errors (RMSE) showed good estimates for frame displacement (RMSE? 0.05m) and speed (RMSE? 0.1m/s) except for three truly vigorous tests. Estimates of horizontal frame rotation (RMSE<3°) and rotational speed (RMSE<7°/s) were very accurate in all conditions. Differences in calculated instantaneous rotation centers (IRC) were small, but somewhat larger in tests performed at high speed (RMSE up to 0.19m). Average test outcomes for linear speed (ICCs > 0.90), rotational speed (ICC>0.99) and IRC (ICC> 0.90) showed high correlations between IMU data and gold standard. Results indicate that wheel skid correction is a prerequisite to reliably measure wheelchair kinematics in sports conditions. Once applied, this method using cheap and affordable sensors, might enable prospective research in wheelchair basketball match conditions and contribute to individual support of athletes in everyday sports practice.","wheelchair kinematics; wheelchair basketball; reliability; Inertial Measurement Unit; instrumented wheelchair","en","conference paper","Elsevier","","","","","","","","Mechanical, Maritime and Materials Engineering","Biomechanical Engineering","","","",""
"uuid:6af6054b-1634-4672-8606-5b3cef87b53e","http://resolver.tudelft.nl/uuid:6af6054b-1634-4672-8606-5b3cef87b53e","Fast long-distance control of spin qubits by photon-assisted cotunneling","Stano, P.; Klinovaja, J.; Braakman, F.R.; Vandersypen, L.M.K.; Loss, D.","","2015","We investigate theoretically the long-distance coupling and spin exchange in an array of quantum dot spin qubits in the presence of microwaves. We find that photon-assisted cotunneling is boosted at resonances between photon and energies of virtually occupied excited states and show how to make it spin selective. We identify configurations that enable fast switching and spin echo sequences for efficient and nonlocal manipulation of spin qubits. We devise configurations in which the near-resonantly boosted cotunneling provides nonlocal coupling which, up to certain limit, does not diminish with distance between the manipulated dots before it decays weakly with inverse distance.","","en","journal article","American Physical Society","","","","","","","","Applied Sciences","Biomechanical Engineering","","","",""
"uuid:2034bea0-72c2-4f41-b5a1-4bc47f80b7a2","http://resolver.tudelft.nl/uuid:2034bea0-72c2-4f41-b5a1-4bc47f80b7a2","Mechanics of Biological Tissues and Biomaterials: Current Trends (editorial)","Zadpoor, A.A.","","2015","Investigation of the mechanical behavior of biological tissues and biomaterials has been an active area of research for several decades. However, in recent years, the enthusiasm in understanding the mechanical behavior of biological tissues and biomaterials has increased significantly due to the development of novel biomaterials for new fields of application, along with the emergence of advanced computational techniques. The current Special Issue is a collection of studies that address various topics within the general theme of “mechanics of biomaterials”. This editorial aims to present the context within which the studies of this Special Issue could be better understood. I, therefore, try to identify some of the most important research trends in the study of the mechanical behavior of biological tissues and biomaterials.","mechanical behavior; biological tissues; biomaterials; measurement techniques; constitutive modeling; OA-Fund TU Delft","en","journal article","MDPI","","","","","","","","Mechanical, Maritime and Materials Engineering","Biomechanical Engineering","","","",""
"uuid:c28da2ef-333d-4728-83bf-535b6a326b9c","http://resolver.tudelft.nl/uuid:c28da2ef-333d-4728-83bf-535b6a326b9c","Industrial of medical tool with steering cables","Breedveld, P.; Henselmans, P.W.J.; Arkenbout, E.A.; Van Furth, W.; Gerboni, G.","","2015","Instrument provided with cables extending between a first portion and a second portion of the instrument at opposite sides of its longitudinal axis and disposed at predefined angles with respect to said axis, which instrument has one or more sets of cables, each set of cables comprising in combination a first cable running parallel to the longitudinal axis, a second cable running at a first predefined angle with respect to said longitudinal axis, and a third cable running at a second predefined angle with respect to said longitudinal axis and having a sign that is opposite to the sign of the first predefined angle so as to arrange that the second and third cables cross each other. The instrument is preferably a joystick or a surgical instrument, such as a laparoscopic tool.","","en","patent","European Patent Office","","","","","","","","Mechanical, Maritime and Materials Engineering","Biomechanical Engineering","","","",""
"uuid:056bd4ba-1624-46a6-8490-1c2dcea79489","http://resolver.tudelft.nl/uuid:056bd4ba-1624-46a6-8490-1c2dcea79489","What quantitative mechanical loading stimulates in vitro cultivation best?","Natenstedt, J.; Kok, A.C.; Dankelman, J.; Tuijthof, G.J.M.","","2015","Articular cartilage has limited regeneration capacities. One of the factors that appear to affect the in vitro cultivation of articular cartilage is mechanical stimulation. So far, no combination of parameters has been identified that offers the best results. The goal is to review the literature in search of the best available set of quantitative mechanical stimuli that lead to optimal in vitro cultivation. The databases Scopus and PubMed were used to survey the literature, and strict in- and exclusion criteria were applied regarding the presence of quantitative data. The review was performed by studying the type of loading (hydrostatic compression or direct compression), the loading magnitude, the frequency and the loading regime (duration of the loading) in comparison to quantitative evidence of cartilage quality response (cellular, signaling and mechanical). Thirty-three studies met all criteria of which 8 studied human, 20 bovine, 2 equine, 1 ovine, 1 porcine and 1 canine cells using four different types of cultivated constructs. Six studies investigated loading magnitude within the same setup, three studies the frequency, and seven the loading regime. Nine studies presented mechanical tissue response. The studies suggest that a certain threshold exits for enhanced cartilage in vitro cultivation of explants (>20 % strain and 0.5 Hz), and that chondrocyte-seeded cultivated constructs show best results when loaded with physiological mechanical stimuli. That is a loading pressure between 5–10 MPa and a loading frequency of 1 Hz exerted at intermittent intervals for a period of a week or longer. Critical aspects remain to be answered for translation into in vivo therapies.","chondrocytes; BMMSC; compression; mechanical loading; in vitro; collagen type II; GAG; cell therapy; OA-Fund TU Delft","en","journal article","Springer","","","","","","","","Mechanical, Maritime and Materials Engineering","Biomechanical Engineering","","","",""
"uuid:c0a2223d-c9c3-491b-a584-21c52e9078c7","http://resolver.tudelft.nl/uuid:c0a2223d-c9c3-491b-a584-21c52e9078c7","Stereo-imaging sensor position localization method and system","Vardy, A.N.","","2015","The disclosure relates to a method and system wherein sensors on a cap or directly disposed on a head can be localized using a stereo camera. By capturing a plurality of stereo images, the positions of the sensors can be determined with respect to each other. At least a first stereo image having a first set of sensors and a second stereo image having a second set of sensors are captured in a first position respectively a second position of the stereo camera relative to the cap by a relative rotation of the stereo camera around the cap. The first set of sensors and the second set of sensors may have one or more sensors in common. The relative rotation of the stereo camera around the cap can be obtained by at least one of a rotation of the stereo camera around a non-rotating cap and a rotation of the cap with respect to a fixed stereo camera.","","en","patent","European Patent Office","","","","","","","","Mechanical, Maritime and Materials Engineering","Biomechanical Engineering","","","",""
"uuid:9f4bec27-3cd7-477c-8450-6f4502ff9e29","http://resolver.tudelft.nl/uuid:9f4bec27-3cd7-477c-8450-6f4502ff9e29","Analysis of isometric cervical strength with a nonlinear musculoskeletal model with 48 degrees of freedom","De Bruijn, E.; Van der Helm, F.C.T.; Happee, R.","","2015","Background: Musculoskeletal models served to analyze head–neck motion and injury during automotive impact. Although muscle activation is known to affect the kinematic response, a model with properly validated muscle contributions does not exist to date. The goal of this study was to enhance a musculoskeletal neck model and to validate passive properties, muscle moment arms, maximum isometric strength, and muscle activity. Methods: A dynamic nonlinear musculoskeletal model of the cervical spine with 48 degrees of freedom was extended with 129 bilateral muscle segments. The stiffness of the passive ligamentous spine was validated in flexion/extension, lateral bending, and axial rotation. Instantaneous joint centers of rotation were validated in flexion/extension, and muscle moment arms were validated in flexion/extension and lateral bending. A linearized static model was derived to predict isometric strength and muscle activation in horizontal head force and axial rotation tasks. Results: The ligamentous spine stiffness, instantaneous joint centers of rotation, muscle moment arms, cervical isometric strength, and muscle activation patterns were in general agreement with biomechanical data. Taking into account equilibrium of all neck joints, isometric strength was strongly reduced in flexion (46 %) and axial rotation (81 %) compared to a simplified solution only considering equilibrium around T1–C7, while effects were marginal in extension (3 %). Conclusions: For the first time, isometric strength and muscle activation patterns were accurately predicted using a neck model with full joint motion freedom. This study demonstrates that model strength will be overestimated particularly in flexion and axial rotation if only muscular moment generation at T1–C7 is taken into account and equilibrium in other neck joints is disregarded.","musculoskeletal; neck; cervical; model; isometric; validation; load sharing; muscle","en","journal article","Springer","","","","","","","","Mechanical, Maritime and Materials Engineering","Biomechanical Engineering","","","",""
"uuid:64a8f6ab-4583-44ea-9c53-da9032bf8db2","http://resolver.tudelft.nl/uuid:64a8f6ab-4583-44ea-9c53-da9032bf8db2","Etiology of Femoroacetabular Impingement in Athletes: A Review of Recent Findings","Zadpoor, A.A.","","2015","The relationship between hip deformities and osteoarthritis has recently received a lot of attention. In particular, it has been shown that both osteoarthritis and its precursors, such as the hip deformities that lead to femoroacetabular impingement (FAI), are more prevalent in elite athletes compared with the general population. However, the etiology of the above-mentioned types of hip deformity is not currently well understood. Many recent studies have attempted to shed light on the etiology of this disease. In this article, the main clinical, radiological, mechanobiological, and biomechanical findings of relevance to understanding the etiology of hip deformities leading to FAI are reviewed. Based on these findings, a consistent biomechanical theory explaining the development of hip deformities in athletes is then presented. According to the presented theory, the repetitive, impact-like musculoskeletal loads that athletes experience, particularly when they undertake extreme ranges of hip motion, cause the development of hip deformities. According to this theory, these musculoskeletal loads trigger abnormal growth patterns during the years of skeletal development and cause the formation of hip deformities. A number of hypotheses based on the proposed theory are then formulated that could be tested in future studies to ascertain whether the proposed theory could sufficiently describe the development of hip deformities in athletes.","","en","journal article","Springer","","","","","","","","Mechanical, Maritime and Materials Engineering","Biomechanical Engineering","","","",""
"uuid:fdb94679-1255-4dc2-a0e2-cd927059af11","http://resolver.tudelft.nl/uuid:fdb94679-1255-4dc2-a0e2-cd927059af11","Linear Identification of Nonlinear Wrist Neuromechanics in Stroke","Klomp, A.","Van der Helm, F.C.T. (promotor); Arendzen, J.H. (promotor)","2015","In many stroke patients, a motor cortex lesion alters motor control. Initially, paresis is most prominent, but then over time, joint stiffening and hyperreflexia may occur. How these different disorders develop over time is still unknown due to high system complexity. Secondary changes in the corticospinal tract, peripheral biomechanics and spinal reflexive system, may also occur. This thesis is part of the EXPLICIT-Stroke study (see Chapters 1, 2 and 3), a randomized, controlled trial that researches the effect of early therapy on post stroke recovery of the upper limb. Amongst other measurements, the EXPLICIT-Stroke study investigates post-stroke changes of brain function and corticospinal tract with fMRI and TMS, respectively. The work in this thesis aims to identify post stroke changes in peripheral biomechanics and the spinal reflexes of the wrist: wrist joint neuromechanics. Neuromechanics play an important role in the functioning of a joint. Inputs to the neuromechanical system are: neural input originating from supraspinal regions and externally applied rotation/torque. Neuromechanics therefore represent the translation from supraspinal input to muscle contraction and resultant joint rotation, torque and/or stiffness, and also describe the relationship between external perturbation and joint response. Joint impedance, the dynamic relationship between joint angle and resultant joint torque, was used to investigate joint neuromechanics. Neuromechanics can be split into: dynamics of passive soft tissues, voluntary muscle contraction and reflexive muscle contraction. Knowledge of changes in the underlying properties yields insight into the complex development of movement disorders and can eventually lead to targeted therapy. Measurement of impedance is achieved by external (motorised) angular perturbation of the joint whilst measuring the joint torque response. This is commonly supported by measurement of muscle activation: Electromyography (EMG). Joint neuromechanics are highly nonlinear. Although many nonlinear neuromechanical properties are known from literature, the effects of these nonlinear properties on joint impedance, and thus their functional and clinical relevance, have generally not been quantified. Commonly known examples of nonlinearity are increased resistance against movement in extreme angles of the range of motion and increased joint stiffness with muscle contraction. Due to nonlinearity, linearly observed neuromechanics depend on input, i.e., depend on measurement conditions. In line with the previous examples, joint stiffness depends on muscle contraction and joint angle. Therefore, understanding nonlinearity is essential for interpretation of joint impedance. Linear modelling and system identification methods allow for estimation of neuromechanical parameters. Use of these linear methods restricts measurement to small deviations in joint angle, angular velocity and muscle contraction. As normal movement often includes large deviations in angle, angular velocity and muscle contraction, such measurements do not describe the full range of interest in joint neuromechanics. Furthermore, comparison of subjects requires that they are measured in the same angles, angular velocities and contraction levels, such that observed differences between subjects are due to differences in neuromechanical properties, and not due to nonlinearity. For example, high joint stiffness in Chapter 9, was hypothesized to be caused by co-activation of the antagonistic muscle pair, i.e., the nonlinear system under a different contraction level (active state), and not caused by different peripheral neuromechanical properties.","","en","doctoral thesis","","","","","","","","","Mechanical, Maritime and Materials Engineering","Biomechanical Engineering","","","",""
"uuid:cee19d5c-2b42-48bf-a867-646d31dbbf2e","http://resolver.tudelft.nl/uuid:cee19d5c-2b42-48bf-a867-646d31dbbf2e","Robust and Transparent Multi-Degree-of-Freedom Bilateral Teleoperation with Time-Delay","Pinto Rebelo, J.L.","Van der Helm, F.C.T. (promotor); Schiele, A. (promotor)","2015","Robots are particularly well suited for executing tasks that take place in locations which are too dangerous or inaccessible to human operators. For robot manipulators to execute complex activities in unknown, unstructured environments, despite the recent increases in computation power, human input is still required for task planning and execution. Most of the existing bilateral teleoperation systems, which make use of commercially available master devices to control industrial slave manipulators, show three main limitations: instability on contact with stiff environments, reduced force-feedback performance to the operator and limited master workspaces. It is the main goal of the research presented in this thesis to achieve high transparency and time-delay robustness in bilateral teleoperation using dissimilar multi-dof master-slave devices, in particular making use of impedance-type masters to command impedance-controlled slave manipulators. This research focuses on tasks which a human operator could manually execute if physically present in the remote environment. This implies that there should be no force scaling and the motion remains within the limits of the human operator arm. It is also assumed that a high level of transparency should be provided to the operator to enable the execution of the required tasks in teleoperation. Currently, modern communication devices and the Internet allow connections throughout the world with round-trip communication delays in the range of hundreds of milliseconds. Throughout this work, communication delay values smaller or equal to 250 ms, for which direct bilateral teleoperation is the most usable, are considered. Under these premises, the research approach followed on this thesis is divided in three main parts. These parts are: (1) Effect of different parameters on system stability and performance for a system with impedance-type master commanding an impedance-controlled slave (2) Robust stability methods for 4-channel architecture under time-delay (3) Propose hardware/software architectures for multi-dof teleoperation","bilatereal teleoperation; time-delay systems; robotics","en","doctoral thesis","","","","","","","","","Mechanical, Maritime and Materials Engineering","BioMechanical Engineering","","","",""
"uuid:68322e34-d86e-44c3-ad89-15537a44167b","http://resolver.tudelft.nl/uuid:68322e34-d86e-44c3-ad89-15537a44167b","Efficacy and safety of uterine manipulators in laparoscopic surgery: A review","Van den Haak, L.; Alleblas, C.; Nieboer, T.E.; Rhemrev, J.P.; Jansen, F.W.","","2015","Purpose This review aims to objectively assess the efficacy and safety of uterine manipulators as reported in scientific literature. Furthermore, it evaluates as to which manipulator best suits which surgical procedure. Methods PubMed, Embase, Web of Science, COCHRANE, CINAHL, Academic Search Premier, Science Direct and the MAUDE database were searched. Technical information was retrieved from the manufacturers. Results 25 articles covering 10 uterine manipulators were found. Studies regarding implementation and use of manipulators are scarce; only two surveys were found comparing different manipulators. Moreover, clinical evidence proving the efficacy of manipulators with respect to prevention of complications, inherent to laparoscopic surgery, does not exist. Conclusion The use of uterine manipulators is well established and it is clear that uterine manipulators offer the easiest way to handle the uterus during surgery. However, detailed information regarding efficacy and safety is scarce. Clinical evidence substantiating the assumed mechanism of prevention of ureter injuries was not found. Our review did not find the optimal manipulator. Some are more versatile than others and not all instruments are appropriate for all types of surgery. Therefore, gynecologists should choose the manipulator that best suits the type of surgery that is performed.","hysterectomy; laparoscopy; review; uterine manipulator","en","journal article","Springer","","","","","","","","Mechanical, Maritime and Materials Engineering","Biomechanical Engineering","","","",""
"uuid:a4d84eb9-88b1-4dd1-b92f-f3b62cf2420d","http://resolver.tudelft.nl/uuid:a4d84eb9-88b1-4dd1-b92f-f3b62cf2420d","Low-Back Stabilization: Contribution of co-contraction and proprioceptive, vestibular and visual feedback","Van Drunen, P.","Van der Helm, F.C.T. (promotor); Van Dieën, J.H. (promotor); Happee, R. (copromotor)","2015","","low-back stabilization; neuromuscular control; sensory feedback; low-back pain; system identification","en","doctoral thesis","","","","","","","","","Mechanical, Maritime and Materials Engineering","BioMechanical Engineering","","","",""
"uuid:f9eea0e0-56a1-4f58-84f6-e5fe98049ed4","http://resolver.tudelft.nl/uuid:f9eea0e0-56a1-4f58-84f6-e5fe98049ed4","Laparoscopic suturing learning curve in an open versus closed box trainer","Rodrigues, S.P.; Horeman, T.; Blomjous, M.S.H.; Hiemstra, E.; Van den Dobbelsteen, J.J.; Jansen, F.W.","","2015","Background The aim of this study was to examine the influence of training under direct vision prior to training with indirect vision on the learning curve of the laparoscopic suture task. Methods Novices were randomized in two groups. Group 1 performed three suturing tasks in a transparent laparoscopic box trainer under direct vision followed by three suturing tasks in a standard non-transparent laparoscopic box trainer equipped with a 0° laparoscope. Group 2 performed six suturing tasks in a standard laparoscopic box trainer. Performance time, motion analysis parameters (economy of movements) and interaction force parameters (tissue handling) were measured. Participants completed a questionnaire assessing: self-perceived dexterity before and after the training, their experienced frustration and the difficulty of the training. Results A total of 34 participants were included, one was excluded because of incomplete training. Group 1 used significantly less time to complete the total of six tasks (27 %). At the end of the training, there were no differences in motion or force parameters between the two groups. Group 2 rated their self-perceived dexterity after the training significantly lower than before the training and also reported significantly higher levels of frustration compared to group 1. Both groups rated the difficulty of the training similar. Conclusion Novices benefit from starting their training of difficult basic laparoscopic skills, e.g., suturing, in a transparent box trainer without camera. It takes less time to complete the tasks, and they get less frustrated by the training with the same results on their economy of movements and tissue handling skills.","training; endoscopy; surgical; technnical","en","journal article","Springer","","","","","","","","Mechanical, Maritime and Materials Engineering","Biomechanical Engineering","","","",""
"uuid:86f27958-d3a5-4cff-a315-7b3e18c08972","http://resolver.tudelft.nl/uuid:86f27958-d3a5-4cff-a315-7b3e18c08972","Additively Manufactured Open-Cell Porous Biomaterials Made from Six Different Space-Filling Unit Cells: The Mechanical and Morphological Properties","Ahmadi, S.M.; Yavari, S.A.; Wauthle, R.; Pouran, B.; Schrooten, J.; Weinans, H.; Zadpoor, A.A.","","2015","It is known that the mechanical properties of bone-mimicking porous biomaterials are a function of the morphological properties of the porous structure, including the configuration and size of the repeating unit cell from which they are made. However, the literature on this topic is limited, primarily because of the challenge in fabricating porous biomaterials with arbitrarily complex morphological designs. In the present work, we studied the relationship between relative density (RD) of porous Ti6Al4V EFI alloy and five compressive properties of the material, namely elastic gradient or modulus (Es20–70), first maximum stress, plateau stress, yield stress, and energy absorption. Porous structures with different RD and six different unit cell configurations (cubic (C), diamond (D), truncated cube (TC), truncated cuboctahedron (TCO), rhombic dodecahedron (RD), and rhombicuboctahedron (RCO)) were fabricated using selective laser melting. Each of the compressive properties increased with increase in RD, the relationship being of a power law type. Clear trends were seen in the influence of unit cell configuration and porosity on each of the compressive properties. For example, in terms of Es20–70, the structures may be divided into two groups: those that are stiff (comprising those made using C, TC, TCO, and RCO unit cell) and those that are compliant (comprising those made using D and RD unit cell).","cellular solids; selective laser melting; compressive properties; porous TTi alloy; OA-Fund TU Delft","en","journal article","MDPI","","","","","","","","Mechanical, Maritime and Materials Engineering","Biomechanical Engineering","","","",""
"uuid:8cf37c65-a48c-476e-8dcc-eb97c06c26d9","http://resolver.tudelft.nl/uuid:8cf37c65-a48c-476e-8dcc-eb97c06c26d9","Human-Exoskeleton Interaction","Van Dijk, W.","Van der Kooij, H. (promotor); Van der Helm, F.C.T. (promotor)","2015","Walking is a very efficient way of getting around and covering large distances. Due to impairments or in extreme conditions, such as carrying a heavy load, one might encounter difficulties while walking. In many cases, wheeled vehicles offer a solution. However, wheeled vehicles are often not suitable for indoor environments or heavy outdoor terrain. Furthermore, wheeled vehicles do not exploit the walking capabilities of the human. As an alternative, exoskeletons have been proposed. These exoskeletons fit around the human body as a portable mechanical suit. The effort and control needed to fulfill a task are shared by the human and the exoskeleton. Human physical effort is measured by metabolism. Metabolism can be measured by recording the intake and exchange of oxygen and carbon dioxide. Many different exoskeletons have been developed in recent decades. Recently experiments showed that walking metabolism can be reduced with an exoskeleton. The goal of this dissertation is to improve exoskeletons that reduce the metabolic cost of walking. One of the main difficulties in achieving this goal is the difficulty in determining in advance what the effect of the exoskeleton will be on the metabolic energy consumption of walking. As a consequence, the design process is characterized by trial and error. This dissertation contributes to improving the complete design process, which includes the modelling, the hardware and control design, and the evaluation of exoskeletons. Based on a literature review, three challenges were defined that facilitate a more systematic design approach for exoskeletons. These challenges are: Improving knowledge of human–exoskeleton interaction Improving exoskeleton hardware and control Fast and detailed evaluation of exoskeleton concepts These challenges have been the cornerstones of the research described in this dissertation. IMPROVING KNOWLEDGE OF HUMAN-EXOSKELETON INTERACTION --Walking simulations The dynamics of human walking are highly non-linear. This has been shown in both simulation studies and experimental studies. The development of exoskeletons requires knowledge of this non-linear behavior. A way to predict this behavior is through biomechanical models. These models predict the kinematics, kinetics, muscle activation, and metabolism of walking (Geyer and Herr, 2010; van den Bogert et al., 2011). Until now, these models have not been used to predict walking with an exoskeleton. This dissertation makes a first attempt to use these models for exoskeleton design. The model developed by Geyer and Herr (2010) is used to simulate human walking with exoskeleton dynamics based on the exoskeleton by (Cain et al., 2007). The model of Geyer and Herr was used since it also has a model of the neuromuscular controller. This controller model has a relatively small number of parameters, which makes it suitable for optimization. Optimization of the control parameters showed that the walking model can adapt to exoskeletal walking. Some experimental trends were captured by the simulation study. However the model does not yet predict the quantitative results that can directly be used in the development process. --Empirical knowledge Since biomechanical models have insufficient accuracy to predict the metabolic cost of walking with an exoskeleton, an alternative solution must be found. One of these solutions is to use empirical data that has been obtained with studies with previous exoskeletons. This dissertation has further expanded this empirical knowledge. The XPED exoskeletons that are described in this dissertation are a realization of the exotendon concept of Van den Bogert (2003). This concept makes use of long elastic cables that run parallel to the human leg. These cables have a similar function to the long tendons that are observed in some animals that move very efficiently, like horses. The cables can temporarily store energy and redistribute energy over the joints. In simulation these exotendons reduce the human joint moments by 71 percent. This model-based prediction is based on the assumption that the joint angles do not change under the load and also the total joint torques stay are invariant. A second assumption is that a reduction in the human joint moments leads to a reduction in the walking metabolism. This dissertation contradicted both assumptions. Experiments with the Achilles exoskeleton, an active ankle exoskeleton, have shown that the joint angles are strongly influenced by the support provided by the Achilles exoskeleton. This should be taken into account when designing a support strategy for the exoskeleton. In the XPED and Achilles exoskeleton, the joint angle patterns were assumed to be influenced by the exoskeleton support. When the joint angles changed in the experimental studies, the support decreased. From this result it was concluded that the support should be robust against changes in the walking pattern. It is noted that in other exoskeletons (Malcolm et al., 2013; Sawicki and Ferris, 2008), the support was high despite the changes in the walking pattern. Still it is difficult to make an exact copy of the controllers of these exoskeletons for implementation in the Achilles exoskeleton since an exact description of the dynamics of these exoskeletons is not available. For the exoskeletons described in this dissertation, an exact description of the dynamics is included. The intention of this description is to make the results obtained with these exoskeletons more generally applicable. IMPROVING EXOSKELETON HARDWARE AND CONTROL Many exoskeletons are not powerful enough or are too heavy to be successful. This follows from regression equations comparing the results of different exoskeletons (Mooney et al., 2014a). In this dissertation, two design methods are presented that can be used to design exoskeletons that can generate much mechanical power and a relatively low weight. --Use of passive mechanisms If the mechanical power in exoskeletons is delivered directly by motors, these motors are relatively heavy. Analogous to mechanisms found in musculoskeletal systems, passive elements could be used to reduce the required motor power. For specific supports, it is even possible to design exoskeletons without motors. The previously mentioned XPED exoskeletons are an example of these passive exoskeletons. Passive elements can also be used in combination with active elements. An example in the human body is the combination of the soleus muscle and the Achilles tendon (Ishikawa et al., 2005). In this dissertation, a similar principle is applied in the Achilles exoskeleton. The Achilles exoskeleton supports the ankle push off. In this exoskeleton, a spring in series with an actuator is used. Temporarily storing energy in the spring can generate a higher mechanical peak power than the maximal motor power and reduce the energy consumption. --Numerical optimization The performance of the exoskeleton is determined by the interaction between many different components. It is difficult to see how changes in one component influence the functioning of other components. This dissertation solves this problem through modelling and optimization. A model of the exoskeleton is made that contains the (electro-)mechanical properties of exoskeletons. The dimensioning and choice for components can be acquired through optimization of the model. This principle has been applied in the design of the XPED and Achilles exoskeletons. --Improvement of exoskeleton control Walking is a cyclic motion. This dissertation has shown how this property of walking can be used to improve the force control of exoskeletons. The gait phase can be estimated with an adaptive frequency oscillator (AFO). Input to the AFO is a cyclic signal. In the case of walking, the hip angle or ground reaction force are suitable candidates. Based on the phase estimation cyclic signals can be estimated. The estimated signal is build up from primitive function. In this case, these are Gaussian functions. The amplitude of these signals is determined by a non-linear filter. The estimated signals can be used to improve tracking or to attenuate undesired dynamical effects. FAST AND DETAILED EVALUATION OF EXOSKELETON CONCEPTS --Improvement in gait analysis The human effort during walking and the change of human metabolic cost due to support with an exoskeleton is measured with respiratory analysis. This measure gives no insight in how changes in metabolic energy emerge. To get this insight, additional measurements are needed. Some of these measurements are kinetic and kinematic measures obtained from gait analysis. This analysis can, for example, be used to see how much mechanical power the human and the exoskeleton absorb and generate. Data is commonly acquired by tracking optical markers placed on the human body and measuring interaction forces with dynamometers such as force plates. Gait analyses are sensitive to errors and in the case of exoskeletal walking, the protocol is hindered due to occlusion of markers by the exoskeleton. The kinematic and kinetic acquired data is redundant. Current data analysis protocols do not make optimal use of this redundancy. This dissertation describes a generic method to process gait data based on an extended Kalman filter. The filter assumes consistent dynamics, and makes it possible to improve the accuracy of estimated joint angles moments, and estimate system parameters (e.g. segment lengths). The latter makes it possible to eliminate the need for palpation of anatomical landmarks. Since the method can be used in real-time, it can be used to evaluate the effects of changes in control settings of the exoskeletons while walking. --Exoskeleton testbeds The development of new hardware to evaluate new exoskeleton concepts is very time consuming. It would therefore be beneficial to be able to test multiple concepts on one platform, an exoskeleton testbed. This requires some flexibility in the hardware and control. Also the dynamics of the exoskeleton should be well defined. This makes it possible to generalize the knowledge that is obtained with exoskeletons and use it in new exoskeleton designs. In this dissertation, two exoskeletons are described that could serve as a testbed. The Achilles exoskeleton is an autonomous exoskeleton for support of the ankle. The Achilles exoskeleton is force controlled and different controllers can be implemented on the exoskeleton. Secondly, this dissertation evaluated how existing rehabilitation robots can be used to simulate the design of new exoskeletons. This dissertation specifically focuses on attenuation of the existing exoskeletons dynamics and improvement of the tracking. CONCLUSION The goal of this dissertation was to improve exoskeletons that reduce the metabolic cost of walking. The research has not directly led to such new exoskeletons. One of the main causes is the difficulty of predicting with sufficient accuracy the effect of an exoskeleton on the walking kinetics, kinematics, and metabolism. Some biomechanical models that might be suitable for this are available and have also been used in this dissertation. However, these models have not been validated. Therefore this dissertation paid special attention to the evaluation of exoskeletons to make these validation studies possible. Altogether, this has led to new methods to model, design, and evaluate exoskeletons. Hopefully, these methods will be valuable tools for the design of future exoskeletons.","exoskeleton; walking; augmentation; biomechanics","en","doctoral thesis","","","","","","","","2015-10-17","Mechanical, Maritime and Materials Engineering","Biomechanical Engineering","","","",""
"uuid:bb3b2d37-3050-45a0-8fa1-7ca51500d13b","http://resolver.tudelft.nl/uuid:bb3b2d37-3050-45a0-8fa1-7ca51500d13b","Comparing different ultrasound imaging methods for breast cancer detection","Ozmen, N.; Dapp, R.; Zapf, M.; Gemmeke, H.; Ruiter, N.V.; Van Dongen, K.W.A.","","2015","Ultrasound is frequently used to evaluate suspicious masses in breasts. These evaluations could be improved by taking advantage of advanced imaging algorithms, which become feasible for low frequencies if accurate knowledge about the phase and amplitude of the wave field illuminating the volume of interest is available. In this study, we compare five imaging and inversion methods: time-of-flight tomography, synthetic aperture focusing technique, backpropagation, Born inversion, and contrast source inversion. All methods are tested on the same full-wave synthetic data representing a 2-D scan using a circular array enclosing a cancerous breast submerged in water. Of the tested methods, only contrast source inversion yielded an accurate reconstruction of the speed-ofsound profile of the tumor and its surroundings, because only this method takes effects such as multiple scattering, refraction, and diffraction into account.","breast; frequency-domain analysis; image reconstruction; imaging; integral equations; receivers; scattering","en","journal article","IEEE","","","","","","","","Mechanical, Maritime and Materials Engineering","Biomechanical Engineering","","","",""
"uuid:eb5b945f-78da-4ae8-b074-b6dc94e3a0c5","http://resolver.tudelft.nl/uuid:eb5b945f-78da-4ae8-b074-b6dc94e3a0c5","Effect of Alkali-Acid-Heat Chemical Surface Treatment on Electron Beam Melted Porous Titanium and Its Apatite Forming Ability","Bsat, S.; Yavari, S.; Munsch, M.; Valstar, E.R.; Zadpoor, A.A.","","2015","Advanced additive manufacturing techniques such as electron beam melting (EBM), can produce highly porous structures that resemble the mechanical properties and structure of native bone. However, for orthopaedic applications, such as joint prostheses or bone substitution, the surface must also be bio-functionalized to promote bone growth. In the current work, EBM porous Ti6Al4V alloy was exposed to an alkali acid heat (AlAcH) treatment to bio-functionalize the surface of the porous structure. Various molar concentrations (3, 5, 10M) and immersion times (6, 24 h) of the alkali treatment were used to determine optimal parameters. The apatite forming ability of the samples was evaluated using simulated body fluid (SBF) immersion testing. The micro-topography and surface chemistry of AlAcH treated samples were evaluated before and after SBF testing using scanning electron microscopy and energy dispersive X-ray spectroscopy. The AlAcH treatment successfully modified the topographical and chemical characteristics of EBM porous titanium surface creating nano-topographical features ranging from 200–300 nm in size with a titania layer ideal for apatite formation. After 1 and 3 week immersion in SBF, there was no Ca or P present on the surface of as manufactured porous titanium while both elements were present on all AlAcH treated samples except those exposed to 3M, 6 h alkali treatment. An increase in molar concentration and/or immersion time of alkali treatment resulted in an increase in the number of nano-topographical features per unit area as well as the amount of titania on the surface.","porous titanium; chemical surface treatment; apatite formation; additive manufacturing; OA-Fund TU Delft","en","journal article","MDPI","","","","","","","","Mechanical, Maritime and Materials Engineering","Biomechanical Engineering","","","",""
"uuid:f837f2d9-1011-4395-88bc-552c864f446f","http://resolver.tudelft.nl/uuid:f837f2d9-1011-4395-88bc-552c864f446f","Predicting Object Size from Hand Kinematics: A Temporal Perspective","Ansuini, C.; Cavallo, A.; Koul, A.; Jacono, M.; Yang, Y.; Becchio, C.","","2015","Research on reach-to-grasp movements generally concentrates on kinematics values that are expression of maxima, in particular the maximum aperture of the hand and the peak of wrist velocity. These parameters provide a snapshot description of movement kinematics at a specific time point during reach, i.e., the maximum within a set of value, but do not allow to investigate how hand kinematics gradually conform to target properties. The present study was designed to extend the characterization of object size effects to the temporal domain. Thus, we computed the wrist velocity and the grip aperture throughout reach-to-grasp movements aimed at large versus small objects. To provide a deeper understanding of how joint movements varied over time, we also considered the time course of finger motion relative to hand motion. Results revealed that movement parameters evolved in parallel but at different rates in relation to object size. Furthermore, a classification analysis performed using a Support Vector Machine (SVM) approach showed that kinematic features taken as a group predicted the correct target size well before contact with the object. Interestingly, some kinematics features exhibited a higher ability to discriminate the target size than others did. These findings reinforce our knowledge about the relationship between kinematics and object properties and shed new light on the quantity and quality of information available in the kinematics of a reach-to-grasp movement over time. This might have important implications for our understanding of the action-perception coupling mechanism.","","en","journal article","Public Library of Science","","","","","","","","Mechanical, Maritime and Materials Engineering","Biomechanical Engineering","","","",""
"uuid:b19c9b46-1f77-4ba5-ac63-320c0c2accce","http://resolver.tudelft.nl/uuid:b19c9b46-1f77-4ba5-ac63-320c0c2accce","Comprehensive neuromechanical assessment in stroke patients: Reliability and responsiveness of a protocol to measure neural and non-neural wrist properties","Van der Krogt, H.; Klomp, A.; De Groot, J.H.; De Vlugt, E.; Van der Helm, F.C.T.; Meskers, C.G.M.; Arendzen, J.H.","","2015","Background: Understanding movement disorder after stroke and providing targeted treatment for post stroke patients requires valid and reliable identification of biomechanical (passive) and neural (active and reflexive) contributors. Aim of this study was to assess test-retest reliability of passive, active and reflexive parameters and to determine clinical responsiveness in a cohort of stroke patients with upper extremity impairments and healthy volunteers. Methods: Thirty-two community-residing chronic stroke patients with an impairment of an upper limb and fourteen healthy volunteers were assessed with a comprehensive neuromechanical assessment protocol consisting of active and passive tasks and different stretch reflex-eliciting measuring velocities, using a haptic manipulator and surface electromyography of wrist flexor and extensor muscles (Netherlands Trial Registry number NTR1424). Intraclass correlation coefficients (ICC) and Standard Error of Measurement were calculated to establish relative and absolute test-retest reliability of passive, active and reflexive parameters. Clinical responsiveness was tested with Kruskal Wallis test for differences between groups. Results: ICC of passive parameters were fair to excellent (0.45 to 0.91). ICC of active parameters were excellent (0.88-0.99). ICC of reflexive parameters were fair to good (0.50-0.74). Only the reflexive loop time of the extensor muscles performed poor (ICC 0.18). Significant differences between chronic stroke patients and healthy volunteers were found in ten out of fourteen parameters. Conclusions: Passive, active and reflexive parameters can be assessed with high reliability in post-stroke patients. Parameters were responsive to clinical status. The next step is longitudinal measurement of passive, active and reflexive parameters to establish their predictive value for functional outcome after stroke.","stroke; biomechanics; stretch reflex; wrist; validation studies","en","journal article","BioMed Central","","","","","","","","Electrical Engineering, Mathematics and Computer Science","Biomechanical Engineering","","","",""
"uuid:d8961a8a-d99d-47d5-8eab-e1f7fb486e63","http://resolver.tudelft.nl/uuid:d8961a8a-d99d-47d5-8eab-e1f7fb486e63","Early motor learning changes in upper-limb dynamics and shoulder complex loading during handrim wheelchair propulsion","Vegter, R.J.K.; Hartog, J.; De Groot, S.; Lamoth, C.J.; Bekker, M.J.; Van der Scheer, J.W.; Van der Woude, L.H.V.; Veeger, H.E.J.","","2015","Background To propel in an energy-efficient manner, handrim wheelchair users must learn to control the bimanually applied forces onto the rims, preserving both speed and direction of locomotion. Previous studies have found an increase in mechanical efficiency due to motor learning associated with changes in propulsion technique, but it is unclear in what way the propulsion technique impacts the load on the shoulder complex. The purpose of this study was to evaluate mechanical efficiency, propulsion technique and load on the shoulder complex during the initial stage of motor learning. Methods 15 naive able-bodied participants received 12-minutes uninstructed wheelchair practice on a motor driven treadmill, consisting of three 4-minute blocks separated by two minutes rest. Practice was performed at a fixed belt speed (v?=?1.1 m/s) and constant low-intensity power output (0.2 W/kg). Energy consumption, kinematics and kinetics of propulsion technique were continuously measured. The Delft Shoulder Model was used to calculate net joint moments, muscle activity and glenohumeral reaction force. Results With practice mechanical efficiency increased and propulsion technique changed, reflected by a reduced push frequency and increased work per push, performed over a larger contact angle, with more tangentially applied force and reduced power losses before and after each push. Contrary to our expectations, the above mentioned propulsion technique changes were found together with an increased load on the shoulder complex reflected by higher net moments, a higher total muscle power and higher peak and mean glenohumeral reaction forces. Conclusions It appears that the early stages of motor learning in handrim wheelchair propulsion are indeed associated with improved technique and efficiency due to optimization of the kinematics and dynamics of the upper extremity. This process goes at the cost of an increased muscular effort and mechanical loading of the shoulder complex. This seems to be associated with an unchanged stable function of the trunk and could be due to the early learning phase where participants still have to learn to effectively use the full movement amplitude available within the wheelchair-user combination. Apparently whole body energy efficiency has priority over mechanical loading in the early stages of learning to propel a handrim wheelchair.","(MeSH); biomechanics; motor learning; rehabilitation; optimization; wheeled mobility","en","journal article","BioMed Central","","","","","","","","Mechanical, Maritime and Materials Engineering","Biomechanical Engineering","","","",""
"uuid:7e039a22-3252-4263-b58c-42515de7af1f","http://resolver.tudelft.nl/uuid:7e039a22-3252-4263-b58c-42515de7af1f","Full regeneration of segmental bone defects using porous titanium implants loaded with BMP-2 containing fibrin gels","Van der Stok, J.; Koolen, M.K.E.; De Maat, M.P.M.; Amin Yavari, S.; Alblas, J.; Patka, P.; Verhaar, J.A.N.; Van Lieshout, E.E.M.; Zadpoor, A.A.; Weinans, H.H.; Jahr, H.","","2015","Regeneration of load-bearing segmental bone defects is a major challenge in trauma and orthopaedic surgery. The ideal bone graft substitute is a biomaterial that provides immediate mechanical stability, while stimulating bone regeneration to completely bridge defects over a short period. Therefore, selective laser melted porous titanium, designed and fine-tuned to tolerate full load-bearing, was filled with a physiologically concentrated fibrin gel loaded with bone morphogenetic protein-2 (BMP-2). This biomaterial was used to graft critical-sized segmental femoral bone defects in rats. As a control, porous titanium implants were either left empty or filled with a fibrin gels without BMP-2. We evaluated bone regeneration, bone quality and mechanical strength of grafted femora using in vivo and ex vivo ?CT scanning, histology, and torsion testing. This biomaterial completely regenerated and bridged the critical-sized bone defects within eight weeks. After twelve weeks, femora were anatomically re-shaped and revealed open medullary cavities. More importantly, new bone was formed throughout the entire porous titanium implants and grafted femora regained more than their innate mechanical stability: torsional strength exceeded twice their original strength. In conclusion, combining porous titanium implants with a physiologically concentrated fibrin gels loaded with BMP-2 improved bone regeneration in load-bearing segmental defects. This material combination now awaits its evaluation in larger animal models to show its suitability for grafting loadbearing defects in trauma and orthopaedic surgery.","BMP; bone graft; bone regeneration; fibrin; metal surface treatment; scaffold; titanium","en","journal article","AO Research Institute Davos","","","","","","","","Mechanical, Maritime and Materials Engineering","Biomechanical Engineering","","","",""
"uuid:5e879685-c161-48c4-8654-495cfdd631d8","http://resolver.tudelft.nl/uuid:5e879685-c161-48c4-8654-495cfdd631d8","Catheter for use in endovascular intervention","Dobbelsteen, J.J.; Clogenson, H.C.","","2015","","","en","patent","European Patent Office","","","","","","","","Mechanical, Maritime and Materials Engineering","Biomechanical Engineering","","","",""
"uuid:56ae618e-4efc-4a5a-92c3-f73ed68a8606","http://resolver.tudelft.nl/uuid:56ae618e-4efc-4a5a-92c3-f73ed68a8606","Early subsidence of shape-closed hip arthroplasty stems is associated with late revision","Van der Voort, P.; Pijls, B.G.; Nieuwenhuijse, M.J.; Jasper, J.; Fiocco, M.; Plevier, J.W.M.; Middeldorp, S.; Valstar, E.R.; Nelissen, R.G.H.H.","","2015","Background and purpose — Few studies have addressed the association between early migration of femoral stems and late aseptic revision in total hip arthroplasty. We performed a meta-regression analysis on 2 parallel systematic reviews and meta-analyses to determine the association between early migration and late aseptic revision of femoral stems. Patients and methods — Of the 2 reviews, one covered early migration data obtained from radiostereometric analysis (RSA) studies and the other covered long-term aseptic revision rates obtained from survival studies with endpoint revision for aseptic loosening. Stems were stratified according to the design concept: cemented shape-closed, cemented force-closed, and uncemented. A weighted regression model was used to assess the association between early migration and late aseptic revision, and to correct for confounders. Thresholds for acceptable and unacceptable migration were determined in accordance with the national joint registries (? 5% revision at 10 years) and the NICE criteria (? 10% revision at 10 years). Results — 24 studies (731 stems) were included in the RSA review and 56 studies (20,599 stems) were included in the survival analysis review. Combining both reviews for the 3 design concepts showed that for every 0.1-mm increase in 2-year subsidence, as measured with RSA, there was a 4% increase in revision rate for the shape-closed stem designs. This association remained after correction for age, sex, diagnosis, hospital type, continent, and study quality. The threshold for acceptable migration of shapeclosed designs was defined at 0.15 mm; stems subsiding less than 0.15 mm in 2 years had revision rates of less than 5% at 10 years, while stems exceeding 0.15 mm subsidence had revision rates of more than 5%. Interpretation — There was a clinically relevant association between early subsidence of shape-closed femoral stems and late revision for aseptic loosening. This association can be used to assess the safety of shape-closed stem designs. The published research is not sufficient to allow us to make any conclusions regarding such an association for the force-closed and uncemented stems.","","en","journal article","","","","","","","","","Mechanical, Maritime and Materials Engineering","Biomechanical Engineering","","","",""
"uuid:e44077c2-b6bd-4e4a-a709-18d700201679","http://resolver.tudelft.nl/uuid:e44077c2-b6bd-4e4a-a709-18d700201679","A surge of p-values between 0.041 and 0.049 in recent decades (but negative results are increasing rapidly too)","De Winter, J.C.F.; Dodou, D.","","2015","It is known that statistically significant (positive) results are more likely to be published than non-significant (negative) results. However, it has been unclear whether any increasing prevalence of positive results is stronger in the ""softer"" disciplines (social sciences) than in the ""harder"" disciplines (physical sciences), and whether the prevalence of negative results is decreasing over time. Using Scopus, we searched the abstracts of papers published between 1990 and 2013, and measured longitudinal trends of multiple expressions of positive versus negative results, including p-values between 0.041 and 0.049 versus p-values between 0.051 and 0.059, textual reporting of ""significant difference"" versus ""no significant difference,"" and the reporting of p < 0.05 versus p > 0.05. We found no support for a ""hierarchy of sciences"" with physical sciences at the top and social sciences at the bottom. However, we found large differences in reporting practices between disciplines, with p-values between 0.041 and 0.049 over 1990-2013 being 65.7 times more prevalent in the biological sciences than in the physical sciences. The p-values near the significance threshold of 0.05 on either side have both increased but with those p-values between 0.041 and 0.049 having increased to a greater extent (2013-to-1990 ratio of the percentage of papers = 10.3) than those between 0.051 and 0.059 (ratio = 3.6). Contradictorily, p < 0.05 has increased more slowly than p > 0.05 (ratios = 1.4 and 4.8, respectively), while the use of ""significant difference"" has shown only a modest increase compared to ""no significant difference"" (ratios = 1.5 and 1.1, respectively). We also compared reporting of significance in the United States, Asia, and Europe and found that the results are too inconsistent to draw conclusions on cross-cultural differences in significance reporting. We argue that the observed longitudinal trends are caused by negative factors, such as an increase of questionable research practices, but also by positive factors, such as an increase of quantitative research and structured reporting.","bias; biological sciences; physical sciences; science policy; significant differences; social sciences","en","journal article","PeerJ","","","","","","","","Mechanical, Maritime and Materials Engineering","Biomechanical Engineering","","","",""
"uuid:a066f9fb-5ea6-43c7-8dba-f8f90d4ee591","http://resolver.tudelft.nl/uuid:a066f9fb-5ea6-43c7-8dba-f8f90d4ee591","Wheelchair-specific fitness of inactive people with long-term spinal cord injury","Van der Scheer, J.W.; De Groot, S.; Tepper, M.; Gobets, D.; Veeger, H.E.J.; Van der Woude, L.H.V.; Woldring, F.; Valent, L.; Slootman, H.; Faber, W.","","2015","Objectives: To describe wheelchair-specific anaerobic work capacity, isometric strength and peak aerobic work capacity of physically inactive people with long-term spinal cord injury using outcomes of tests that are feasible for use in rehabilitation centres, and to determine associations among these fitness components. Design: Cross-sectional study. Participants: Manual wheelchair users with spinal cord injury for at least 10 years, who were inactive based on a norm score of a physical activity questionnaire (n?=?29; 22 men; 20 with paraplegia; median age 53 years). Methods: Participants performed 3 exercise tests in their own wheelchair to determine: highest 5-s power output over 15-m overground sprinting (P5–15m); highest 3-s isometric push-force (Fiso); and peak power output (POpeak) and peak oxygen uptake (VO2peak) over a peak test. Results: Median (interquartile range) was in P5–15m 16.1 W (9.4–20.9); in Fiso 399 N (284–610); in POpeak 40.9 W (19.1–54.9); and in VO2peak 1.26 l/min (0.80–1.67). Correlations among outcomes of fitness components were weak (r?=?0.50–0.67, p?0.01), except for P5–15m with POpeak (r?=?0.79, p?0.001). Conclusion: All fitness components measured in this sample were at relatively low levels, implying a specific need for interventions to improve wheelchair-specific fitness. The weak-to-moderate associations among components imply that separate tests should be used when monitoring wheelchair-specific fitness in rehabilitation centres.","paraplegia; physical fitness; tetraplegia; wheelchairs; work power; aerobic capacity; mechanical efficiency; anaerobic power; isometric strength","en","journal article","Foundation for Rehabilitation Information","","","","","","","2015-07-16","Mechanical, Maritime and Materials Engineering","Biomechanical Engineering","","","",""
"uuid:18bc7cc6-153b-4ffe-8da1-474f08a212fc","http://resolver.tudelft.nl/uuid:18bc7cc6-153b-4ffe-8da1-474f08a212fc","Steering and Harvesting Technology for Minimally Invasive Biopsy","Jelínek, F.","Dankelman, J. (promotor); Breedveld, P. (promotor)","2015","Contemporary medical imaging technologies, such as computed tomography or magnetic resonance imaging, play a pivotal role in medical diagnosis, allowing for a relatively fast and non-invasive examination of the human body. In the field of cancer surgery they allow for preoperative detection of tumorous tissue and aid the surgical planning. However, only recent developments in the imaging field have introduced the possibility for a real-time non-invasive intraoperative detection of tumorous tissue with sufficient margins for radical tumour resection. These imaging technologies are collectively called optical biopsy and besides providing the real-time visualisation of the tumorous tissue on a large scale, e.g. near-infrared fluorescence, they allow for an instant tumour detection and analysis on a small scale, e.g. differential pathlength spectroscopy, ultimately without the need for any pathological analysis. While the optical biopsy provides an answer to the tumour detection, its subsequent accurate resection, or mechanical biopsy, remains a challenge. This challenge is further aggravated with more demanding applications, such as minimally invasive surgery, as compared to open surgery, and accurate resection of organ exterior as compared to organ interior. Yet, as challenges are here to be solved, the aim of this work is to provide an answer to combining the optical and the mechanical biopsies in an accurate manner with the aim to perform safe minimally invasive resection of small tumours at organ and tissue surfaces. Furthermore, as minimally invasive surgical applications pose various spatial restrictions on tissue manipulation, the second objective of this work is to present a reliable joint construction for the envisioned tissue resection instrument, allowing it to attain a proper orientation to the tissue of interest. As the focus of this thesis is twofold, its chapters are grouped into two parts. The first part of this thesis treats the combination of the optical and the mechanical biopsies in a reliable and an effective manner, showing the development of a resection tip, the opto-mechanical biopsy harvester, for a minimally invasive surgical instrument (Chapters 2-4). The second part of this thesis addresses the issue of steerable joint constructions in the minimally invasive surgical instruments and their reliable controllability in order to provide both flexibility and stability for the accurate tumour detection and resection (Chapters 5-8). With the vision to devise the design of the opto-mechanical biopsy harvester, a review of the state-of-the-art minimally invasive surgical instruments capable of performing the optical and the mechanical biopsies successively and accurately was performed and it is presented in Chapter 2. In addition, the review outlines any and all the minimally invasive surgical devices housing an accessory channel, thus mechanically capable of integrating a fibre optic cable for optical biopsy. As the findings of the aforementioned literature review were rather limited, this gave an opportunity to conceive and develop a novel bio-inspired design of a frontally-acting opto-mechanical biopsy harvester. Its experimental design and prototype are presented in Chapter 3 together with feasibility tests proving the concept. While the instrument steerability was not yet incorporated, the experimental design was created with a great consideration of its ultimate functionality. Chapter 4 concludes the first part of this thesis with a follow-up optimisation of the biopsy harvester’s collapsible resection device, the crown-cutter, bio-inspired by the sea urchin’s chewing organ Aristotle’s lantern and shaped as a crown of numerous pointy teeth. The study researches the impact of tooth quantity and type of their bevel on the induced tissue deformation, penetration forces and proper tooth collapsibility. Similarly to the first part of this thesis, the second part begins with a review article in Chapter 5 of all the mechanical joint constructions used in the state-of-the-art steerable minimally invasive surgical instruments. By clear categorisation, the aim of this review is to help identify a reliably controllable steerable joint ensuring accurate operation of the envisioned instrument’s tip. The fundamental joint classification can also serve as a design aid for other developments in this field. With the vision to develop a stiff and reliably controllable joint for the envisioned biopsy instrument, a novel steerable laparoscopic instrument prototype DragonFlex was developed. As discussed in Chapter 6, its simple, repetitive and symmetrical design incorporates a rolling joint with a special tight cable guidance. Together they maximise the driving cable lifespan, equalise the forces in both cables and enable control of seven instrument degrees of freedom by only seven structural components. Not only is DragonFlex the world’s first almost entirely additive manufactured steerable laparoscopic instrument prototype, but it also sheds new light on the potential of additive manufacturing in the surgical field. The promisingly high bending stiffness of DragonFlex’s rolling joint is evaluated in Chapter 7, which provides an empirical evidence that this joint construction is indeed superior to the state of the art in this respect. As clarified, the insight into achieving high bending stiffness of cable-driven joint constructions lies in the principle of full actuation of each degree of freedom, as opposed to underactuation. In order to perfect DragonFlex’s already stiff rolling joint Chapter 8 illustrates a way to minimise the small degree of remaining cable slack in the original design. As opposed to the common design practice attempting to eliminate the cable slack by a cable tensioning mechanism, this chapter introduces a more fundamental solution applicable to rolling joints in general. On top of minimising the cable slack, this solution removes the need for a cable tensioning mechanism, hence simplifying the overall design and assembly even further. The thesis is concluded with a discussion section in Chapter 9 outlining the combination of the reliable steering and the accurate harvesting technology developed for the purpose of minimally invasive biopsy. This last chapter presents the envisioned design and the real-scale fully functional prototype of the steerable minimally invasive opto-mechanical biopsy harvester composed of a permanent and a disposable section. The fusion of all the presented insights and designs is addressed in a practical manner, especially with regard to the manufacturability and the proposed usage of the final envisioned instrument.","minimally invasive surgery; laparoscopy; biopsy; optical biopsy; differential pathlength spectroscopy; steerable instrument; joint; biological inspiration; sea urchin; Aristotle's lantern","en","doctoral thesis","","","","","","","","2016-01-12","Mechanical, Maritime and Materials Engineering","BioMechanical Engineering","","","",""
"uuid:accc68b7-0c5f-46ce-98ea-2b9efdbf1339","http://resolver.tudelft.nl/uuid:accc68b7-0c5f-46ce-98ea-2b9efdbf1339","Task, muscle and frequency dependent vestibular control of posture","Forbes, P.A.; Siegmund, G.P.; Schouten, A.C.; Blouin, J.S.","","2015","The vestibular system is crucial for postural control; however there are considerable differences in the task dependence and frequency response of vestibular reflexes in appendicular and axial muscles. For example, vestibular reflexes are only evoked in appendicular muscles when vestibular information is relevant to postural control, while in neck muscles they are maintained regardless of the requirement to maintain head on trunk balance. Recent investigations have also shown that the bandwidth of vestibular input on neck muscles is much broader than appendicular muscles (up to a factor of 3). This result challenges the notion that vestibular reflexes only contribute to postural control across the behavioral and physiological frequency range of the vestibular organ (i.e., 0–20 Hz). In this review, we explore and integrate these task-, muscle- and frequency-related differences in the vestibular system’s contribution to posture, and propose that the human nervous system has adapted vestibular signals to match the mechanical properties of the system that each group of muscles controls","vestibular reflexes; postural control; task dependent; frequency response; appendicular muscles; axial muscles","en","journal article","","","","","","","","","Mechanical, Maritime and Materials Engineering","Biomechanical Engineering","","","",""
"uuid:592c7c6f-7440-49ca-9a9f-3e00199cdab3","http://resolver.tudelft.nl/uuid:592c7c6f-7440-49ca-9a9f-3e00199cdab3","Control strategies for active lower extremity prosthetics and orthotics: A review","Tucker, M.R.; Olivier, J.; Pagel, A.; Bleuler, H.; Bouri, M.; Lambercy, O.; Del R Millan, J.; Riener, R.; Vallery, H.; Gassert, R.","","2015","Technological advancements have led to the development of numerous wearable robotic devices for the physical assistance and restoration of human locomotion. While many challenges remain with respect to the mechanical design of such devices, it is at least equally challenging and important to develop strategies to control them in concert with the intentions of the user. This work reviews the state-of-the-art techniques for controlling portable active lower limb prosthetic and orthotic (P/O) devices in the context of locomotive activities of daily living (ADL), and considers how these can be interfaced with the user’s sensory-motor control system. This review underscores the practical challenges and opportunities associated with P/O control, which can be used to accelerate future developments in this field. Furthermore, this work provides a classification scheme for the comparison of the various control strategies. As a novel contribution, a general framework for the control of portable gait-assistance devices is proposed. This framework accounts for the physical and informatic interactions between the controller, the user, the environment, and the mechanical device itself. Such a treatment of P/Os – not as independent devices, but as actors within an ecosystem – is suggested to be necessary to structure the next generation of intelligent and multifunctional controllers. Each element of the proposed framework is discussed with respect to the role that it plays in the assistance of locomotion, along with how its states can be sensed as inputs to the controller. The reviewed controllers are shown to fit within different levels of a hierarchical scheme, which loosely resembles the structure and functionality of the nominal human central nervous system (CNS). Active and passive safety mechanisms are considered to be central aspects underlying all of P/O design and control, and are shown to be critical for regulatory approval of such devices for real-world use. The works discussed herein provide evidence that, while we are getting ever closer, significant challenges still exist for the development of controllers for portable powered P/O devices that can seamlessly integrate with the user’s neuromusculoskeletal system and are practical for use in locomotive ADL.","prosthetic; orthotic; exoskeleton; control architecture; intention recognition; activity mode recognition; volitional control; shared control; finite-state machine; electromyography; sensory feedback; sensory substitution; seamless integration; sensory-motor control; rehabilitation robotics; bionic; biomechatronic; legged locomotion","en","journal article","BioMed Central","","","","","","","","Mechanical, Maritime and Materials Engineering","Biomechanical Engineering","","","",""
"uuid:85385521-d8a7-41e0-aa29-b36ab7088b21","http://resolver.tudelft.nl/uuid:85385521-d8a7-41e0-aa29-b36ab7088b21","Active Grasp Synthesis for Grasping Unknown Objects","Çall?, B.","Jonker, P.P. (promotor)","2015","Manipulation is a key feature for robots which are designed to work in daily environments like homes, offices and streets. These robots do not often have manipulators that are specialized for specific tasks, but grippers that can grasp the target object. This makes grasping a crucial ability that enables many manipulation tasks. Robotic grasping is a complex process with various aspects: design of the gripper, detecting grasping points/regions that lead to a stable grasp (grasp synthesis), avoiding surrounding objects while executing the grasp (obstacle avoidance), detecting task related features of the object, altering the pose of the object to free up graspable regions (pre-grasp manipulation) are some of these aspects. In order to maintain a robust grasping system, all these aspects should work in harmony, aid each other and preferably cover each others mistakes. Among these aspects, vision based grasp synthesis for unknown objects forms a large portion of the robotic grasping literature. These algorithms deal with the problem of detecting grasping points or regions on a target object without an object shape model supplied a priori; instead they utilize visual information provided by the robot's sensors. The majority of these algorithms use one single image of the target object for grasp synthesis, and make implicit or explicit assumptions on the missing shape information of the target object. The missing information is a function of the shape of the object as well as the viewpoint of the vision sensor. So far in literature, there is no reliable grasp synthesis algorithm that can cope with the missing shape information and provide successful grasp synthesis for a large variety of objects and viewpoints. This thesis proposes a novel framework in which grasp synthesis process is coupled with active vision strategies in order to relax the assumptions on the viewpoint of the vision sensor and increase grasp success rate. Unlike prior work which considers grasp synthesis as a passive data analysis process that uses only the provided image of the target object, the proposed framework introduces strategies to improve the quality of the data by leading the sensor to viewpoints by which the grasp synthesis algorithms can generate higher quality grasps. With such a strategy, the burden of the grasp synthesis algorithms is shared with an active vision stage which boosts their success rates. Within the framework two novel methodologies are presented each of which utilizes a different active vision strategy. In the first methodology, local viewpoint optimization methods are analyzed; an extremum seeking control based optimization method is utilized to optimize the viewpoint of the sensor locally by maximizing the grasp quality value continuously. This methodology is easy to implement as it does not necessitate any prior training, but it has a risk of getting stuck at local optima. With this method up to 94\% success rate has been achieved for power grasps. However, it is observed that, noise on the grasp quality value and not being able to avoid local optima affect the performance negatively. In the second methodology, supervised learning algorithms are used to obtain an exploration policy. This strategy has a lower risk of getting stuck at local optima, but requires a training process. Furthermore, with this strategy, the information acquired during the process can be fused, and assumption on the missing object shape data can be relaxed significantly. The experimental results show that the strategy is superior than heuristic based and random search techniques in terms of both success rate and efficiency. With the proposed framework, we hope to encourage a new way of thinking about the grasp synthesis problem by introducing the use of active vision tools. We believe such an approach can have significant contribution for solving this challenging robotics problem.","grasping; robotics; manipulation; active vision; object recognition; extremum seeking; supervised learning; viewpoint optimization","en","doctoral thesis","","","","","","","","","Mechanical, Maritime and Materials Engineering","BioMechanical Engineering","","","",""
"uuid:034c51e9-f0b3-46b9-a091-169ae50882d2","http://resolver.tudelft.nl/uuid:034c51e9-f0b3-46b9-a091-169ae50882d2","Shoulder joint velocity during fastball pitching in baseball","Gasparutto, X. (TU Delft Biomechatronics & Human-Machine Control); van der Graaff, E (Vrije Universiteit Amsterdam); van der Helm, F.C.T. (TU Delft Biomechatronics & Human-Machine Control); Veeger, H.E.J. (TU Delft Biomechanical Engineering; TU Delft Biomechatronics & Human-Machine Control; Vrije Universiteit Amsterdam)","Colloud, F. (editor); Domalain, M. (editor); Monnet, T. (editor)","2015","The purpose of this study was to assess the rotation and translation velocity of the shoulder complex during fastball pitching in baseball. 8 pitchers from the Dutch AAA team performed each 3 fastball pitches. Their motion was recorded by an opto-electronic device. Kinematic computation was performed using the quaternion algebra. The results showed that the endo-rotation, depression and backward rotation velocity of the humerus at ball release are initiated by a translation of the scapular girdle in the forward and upward direction before ball release.","baseball; pitching; upper limb; shoulder; velocity","en","conference paper","International Society of Biomechanics in Sports","","","","","","","","","Biomechanical Engineering","Biomechatronics & Human-Machine Control","","",""
"uuid:5f96057b-46bb-4e82-80ad-90519aee6916","http://resolver.tudelft.nl/uuid:5f96057b-46bb-4e82-80ad-90519aee6916","Isometric and Dynamic Control of Neck Muscles: Reflexive contributions and muscle synergies","De Bruijn, E.","Van der Helm, F.C.T. (promotor); De Koning-Tijssen, M.A.J. (promotor); Happee, R. (copromotor)","2014","It is well established that the central nervous system (CNS) stabilizes the head using reflexive feedback and cocontraction. The major reflexive pathways in the neck are through muscle spindles generating the cervicocollic reflex (CCR) and through the vestibular organ generating the vestibulocollic reflex (VCR). The CNS modulates the contribution of the different pathways and the level of cocontraction to change the system dynamics in an effort to optimally withstand motion disturbances. Predetermined groups of muscles, called synergies, are used to generate stabilizing forces, but it is not clear how the CNS modulates the reflexive pathways and how the muscle groups are chosen. To understand the function of the different reflexive pathways and the responses of the different muscles musculoskeletal models are necessary. To date, a neck model with sufficient detail to simulate vertebral injury and reflexive control of individual muscles does not exist. There are a number of reasons why the behavior of the CNS in neck muscle control should be investigated. Cervical dystonia is a movement disorder characterized by involuntary activity of the neck muscles leading to debilitating abnormal postures and twisting movements. Current evidence points towards changes in the neuronal circuitry in the brain, but the underlying pathology remains for the most part unclear. The understanding of normal and aberrant control of muscles is an important key to finding a solution for this disorder. The current treatment involves injecting the dystonic muscles with botulinum toxin. Although this treatment is generally quite successful, it often remains difficult to distinguish dystonic muscles from healthy compensatory activation. Improvements in the protocols to select aberrant muscles in patients would improve the effectiveness of the treatment and could be an asset when treating more difficult cases. Two aims were set out in this thesis. The first was to establish how the CCR and VCR pathways activate individual muscles to ensure head and neck stabilization and how their gains modulate under different loading conditions. To this end a detailed neuromuscular model was developed containing reflexive neuromuscular feedback and cocontraction. The second aim was to understand the pathology behind cervical dystonia by quantifying aberrance of individual muscle activation in patients, and to develop a protocol to improved muscle selection for possible diagnostic use. In total, five studies were performed to achieve these goals. The first aim of this thesis was achieved by investigating neuromuscular control of healthy subjects using a dynamic experiment and a detailed neuromuscular model. First, we wanted to establish a relationship between the modulation of reflexes and the amplitude and bandwidth of a disturbance to the head and neck (Chapter 2). This was determined by perturbing seated subjects in an anteriorposterior direction with varying amplitudes and frequency content. We found a substantial attenuation of both vestibulocollic and cervicocollic reflexes as the frequency content of the perturbation increased, but only small changes with amplitude. The subjects performed these tasks with the eyes open and closed, and it was observed that with the eyes open subjects were able to further reduce the head motion in space. To investigate how and why the reflex pathways modulate with bandwidth a neuromuscular model was developed. A model including eight vertebrae and the skull and full joint motion was extended with a detailed set of 258 muscle segments. The spinal stiffness, muscle moment arms, instantaneous axes of rotation, and cervical strength were validated in its neutral position (Chapter 3). The importance of a mechanical equilibrium in the neck when estimating model strength was also addressed. The model was able to predict isometric muscle activation patterns of healthy subjects, and the study demonstrated that model strength will be overestimated particularly in flexion and axial rotation the equilibrium over all the neck joints is ignored. Neuromuscular control of the model was then implemented to enable dynamic simulations, which included the vestibulocollic and cervicocollic reflexes and cocontraction. Nonlinear sensory and muscle activation dynamics were implemented along with neural delays for the different feedback pathways. Muscle synergies defined in isometric conditions to generate directional forces under joint equilibrium were used to convert the reflexive vestibulocollic feedback of the semicircular canals and otoliths to individual muscle activations. A similar muscle synergy was used to generate cocontraction over a predefined set of muscles. The cervicocollic reflex was modelled such that each muscle element contained its stretch reflex (muscle length and velocity). The neuromuscular model was subsequently used to investigate the modulation changes with bandwidth observed in Chapter 2 by optimizing reflexive gains and cocontraction of the model to experimental subject data. A possible strategy involved in reflex modulation was also investigated by estimating muscle energy consumption (strategy to minimize effort) and head motion (strategy to stabilize the head). In this study, reflexive gains semicircular and muscle spindle gains were modulated in congruence with our hypothesis, showing gain reductions with increasing bandwidth. However, in contrast to the hypothesis cocontraction was also found to steadily increase with bandwidth. The primary strategy of the CNS appeared to be a suppression of resonant oscillations of the head between 1-3 Hz and, if necessary, between 6-8 Hz. When the perturbation bandwidth increased the reflexes and cocontraction were modulated to dampen the higher frequencies as they were being excited. To investigate aberrant activity of dystonic muscles a standardized protocol was developed by fixing the head of subjects in an isometric device. This ensured a similar position of the head and neck and allowed for controlled task instructions using head force measurements and visual feedback. Individual muscle electromyography (EMG) of 10 cervical dystonia patients and 10 healthy subjects were compared in different loading directions. To addresses a possible worsening of dystonic responses due to an increase in voluntary muscle contractions, activity was evaluated at different contraction levels. Increased levels of mean and minimum (cocontraction) EMG were found in clinically diagnosed dystonic muscles (Chapter 5) and the spectral content of these muscles was shifted (Chapter 6), likely indicating an altered control of the muscles by the central nervous system. The abnormal activity was found during submaximal contractions and in rest, but no differences were observed during maximal contractions. Also, no evidence was found of an exacerbation of dystonic activity related to an increase in muscle contraction when the head was fixed. These results seem to indicate that dystonic muscles are controlled during submaximal contractions much like healthy muscles are activated during maximal contractions. The identified aberrant activity in patient muscles was then evaluated as an identifier of dystonic muscles. The protocols were able to distinguish dystonic activity on a group level, but were not yet sufficiently accurate to be used as a diagnostic tool. Currently, a study is being performed with an improved setup and including patients not previously treated with botulinum toxin to further investigate the applicability of these methods for diagnostics. The contents of this thesis can be summarized with the following main conclusions: I. The central nervous system modulates reflex gains and cocontraction with the frequency content of perturbations with the goal to suppress resonant frequencies of the head while minimizing effort. II. Dystonia patients show increased mean and altered spectral muscle activity during submaximal contractions and rest, but not during maximal contractions. In addition, a higher level of muscle activation does not exacerbate dystonic activity. A neuromuscular model with full joint motion and reflexive control of individual muscles was developed, which is a valuable tool for future investigations into neuromuscular disorders and injury of the neck. The protocols for the identification of aberrant muscle activity in dystonia patients that were established in this thesis have the potential to be used for dystonic muscle selection in the future.","cervical dystonia; isometric; muscle synergy; neuromuscular model; voluntary contraction","en","doctoral thesis","","","","","","","","","Mechanical, Maritime and Materials Engineering","Biomechanical Engineering","","","",""
"uuid:2b140a5e-af59-4313-bd4c-c00bda879420","http://resolver.tudelft.nl/uuid:2b140a5e-af59-4313-bd4c-c00bda879420","Factors contributing to pedelec crashes in the Netherlands (poster)","Kovácsová, N.; De Winter, J.C.F.; Schwab, A.L.; Hagenzieker, M.P.","","2014","","","en","conference paper","","","","","","","","","Mechanical, Maritime and Materials Engineering","Biomechanical Engineering","","","",""
"uuid:8b509ddb-ca42-4420-9b35-bc5543ae0d60","http://resolver.tudelft.nl/uuid:8b509ddb-ca42-4420-9b35-bc5543ae0d60","Forming of magnesium alloy microtubes in the fabrication of biodegradable stents","Wang, L.; Fang, G.; Qian, L.; Leeflang, M.A.; Duszczyk, J.; Zhou, J.","","2014","Magnesium alloys have, in recent years, been recognized as highly promising biodegradable materials, especially for vascular stent applications. Forming of magnesium alloys into high-precision thin-wall tubes has however presented a technological barrier in the fabrication of vascular stents, because of the poor workability of magnesium at room temperature. In the present study, the forming processes, i.e., hot indirect extrusion and multi-pass cold drawing were used to fabricate seamless microtubes of a magnesium alloy. The magnesium alloy ZM21 was selected as a representative biomaterial for biodegradable stent applications. Microtubes with an outside diameter of 2.9 mm and a wall thickness of 0.2 mm were successfully produced at the fourth pass of cold drawing without inter-pass annealing. Dimensional evaluation showed that multi-pass cold drawing was effective in correcting dimensional non-uniformity arising from hot indirect extrusion. Examinations of the microstructures of microtubes revealed the generation of a large number of twins as a result of accumulated work hardening at the third and fourth passes of cold drawing, corresponding to the significantly raised forming forces. The work demonstrated the viability of the forming process route selected for the fabrication of biodegradable magnesium alloy microtubes.","vascular stent; microtube; magnesium alloy; extrusion; drawing","en","journal article","Elsevier","","","","","","","","Mechanical, Maritime and Materials Engineering","Biomechanical Engineering","","","",""
"uuid:242cca2b-577b-4ee9-8300-7cf4bd64700b","http://resolver.tudelft.nl/uuid:242cca2b-577b-4ee9-8300-7cf4bd64700b","Comparison of optical coherence tomography and histopathology in quantitative assessment of goat talus articular cartilage","Cernohorsky, P.; Kok, A.C.; De Bruin, D.M.; Brandt, M.J.; Faber, D.J.; Tuijthof, G.J.M.; Kerkhoffs, G.M.; Strackee, S.D.; Van Leeuwen, T.G.","","2014","Background and purpose — Optical coherence tomography (OCT) is a light-based imaging technique suitable for depiction of thin tissue layers such as articular cartilage. Quantification of results and direct comparison with a reference standard is needed to confirm the role of OCT in cartilage evaluation. Materials and methods — Goat talus articular cartilage repair was assessed quantitatively with OCT and compared with histopathology using semi-automated analysis software. Osteochondral defects were created centrally in goat tali with subsequent healing over 24 weeks. After sacrifice, the tali were analyzed using OCT and processed into histopathology slides. Cartilage thickness, repair tissue area, and surface roughness were measured. Also, light attenuation coefficient measurements were performed to assess differences in the properties of healthy tissue and repair tissue. Results — Intra-class correlation coefficients for resemblance between the 2 techniques were 0.95 (p < 0.001) for thickness, 0.73 (p = 0.002) for repair tissue area, and 0.63 (p = 0.015) for surface roughness. Light attenuation differed significantly between healthy cartilage (8.2 (SD 3.9) mm-1) and repair tissue (2.8 (SD 1.5) mm-1) (p < 0.001). Interpretation — Compared to histopathology as the standard reference method, OCT is a reproducible technique in quantitative analysis of goat talus articular cartilage, especially when assessing cartilage thickness and to a lesser extent when measuring repair tissue area and surface roughness. Moreover, differences in local light attenuation suggest measurable variation in tissue structure, enhancing the clinical applicability of quantitative measurements from cartilage OCT images.","","en","journal article","Taylor & Francis","","","","","","","","Mechanical, Maritime and Materials Engineering","Biomechanical Engineering","","","",""
"uuid:5648e091-ebb2-4ac9-b2de-82ec3bd3146e","http://resolver.tudelft.nl/uuid:5648e091-ebb2-4ac9-b2de-82ec3bd3146e","Subject-specific upper extremity modelling","Bolsterlee, B.","Van der Helm, F.C.T. (promotor); Veeger, H.E.J. (promotor)","2014","Insight into the mechanical interaction between muscles and bones can be of great help to understand normal function of the human body and to improve diagnoses and treatments of musculoskeletal disorders. This research presented in this thesis aims to improve the predictions of a musculoskeletal model of the shoulder and elbow (the Delft Shoulder and Elbow Model or DSEM) by extracting anatomical information from MRI scans and other imaging modalities. Several techniques are presented to personalise anatomical parameters and the effect on muscle and joint force predictions are calculated. Due to difficulties related to validation of modelling results and the limited ability to measure all relevant model parameters in vivo, it is concluded that subject-specific models are not likely to lead to a vast new range of applications in the near future.","biomechanics; musculoskeletal model; shoulder and elbow; MRI; ultrasound","en","doctoral thesis","","","","","","","","","Mechanical, Maritime and Materials Engineering","BioMechanical Engineering","","","",""
"uuid:c483d0c8-1d45-4889-a85d-3bce9d281b11","http://resolver.tudelft.nl/uuid:c483d0c8-1d45-4889-a85d-3bce9d281b11","Manual Control for Medical Instruments in Minimally Invasive Surgery","Fan, C.","Dankelman, J. (promotor); Breedveld, P. (promotor); Dodou, D. (promotor)","2014","With the introduction of new technologies, surgical procedures have been varying from free access in open surgery towards limited access in minimal invasive surgery. During such procedures, surgeons have to manoeuver the instruments from outside the patient while looking at the monitor. Long and slender instruments are developed that can insert into the patients body through small incision(s) or natural orifice(s) with help of an endoscope following instrument created or transluminal pathways. In these types of procedures, called pathway surgery throughout this thesis, the incisions limit the instrumentmotion and reduce the number of degree of freedom (DoF) from six to four, while the curvature of the pathway restricts the instrument motion within a narrow tunnel, further reducing the number of DoF down to two. After the establishment of conventional instruments, steerable instruments (instruments with one steerable segment on its tip) and manoeuvrable instruments (instruments with multiple steerable segments) are under development, yet the development of an intuitive and effective control interface for such instruments remains a challenge. The goal of this thesis is to assess the manoeuvrability of currently available commercial steerable instruments, and to find potential solutions to manoeuvring difficulties of medical instruments used in pathway surgery. To achieve this goal, we developed a simulator emulating the shaft and handle of a manoeuvrable instrument, and we conducted experiments that investigate the effects of various factors of manual manoeuvrability on human performance in a simulated surgical pathway task. As many studies have reported new developments of steerable and manoeuvrable instruments, the first part of this thesis includes a survey of literature related with manual control methods for handheld steerable instruments, to investigate what would be the bestsuited manual control method for future instruments for pathway surgery. A full overview of manoeuvrable approaches and their controls interfacing were provided, and a novel way of categorizing control methods for handheld manoeuvrable instruments based on physical coupling between the controllers was proposed. This study shows that in the case of controlling single steerable segment, direct- as well as indirect- control methods have been developed, whereas in the case of controlling multiple steerable segments, a gradual shift can be noticed from parallel and serial control to integrated control. The survey results are linked to future developments in pathway surgery, that is, instead of providing full manoeuvrability at each steerable segment, Integrated Single-Segment control (ISS, i.e. using one controller to manoeuvre the leading segment while the other steerable segments copy the leading motion) would generate a user experience similar to conventional steerable instruments in aspects like eye-hand coordination, 3-dimensional vision and surgical workflow. The second part of this thesis provides two experiments that compare control methods for steerable instruments used in neuroendovascular surgery and laparoscopic surgery respectively. Firstly, an experiment was designed to investigate the effectiveness of two widely used 1DoF control methods, rotating control and sliding control, and their effects on human performance, such as accuracy, safety and intuitiveness. Based on directions of the control motions, four handles were built. The slider-vertical handle provided general faster and safer performance, whereas rotator handles were more preferred by participants at the end of the experiment. Subsequently, two 2DoF steerable instruments, one controlled by the thumb and the other by the wrist, were compared in a positioning task in a portable laparoscopic trainer. The experiment results showed that although the two compared control methods were not significantly different in terms of time, thumb control was strongly preferred by novices. Currently the development of manoeuvrable instruments is still in its infancy, the ISS concept and the other outcome from the literature review was a trigger to develop a simulator, Endo-PaC (EndoPathController), allowing great possibility of investigating manual manoeuvrability for manoeuvrable medical instruments. Endo-PaC mimics the shaft and handle of a manoeuvrable instrument with standard dimensions, measures the control motion in 5DoF, and is electronically connected to a laptop computer. Custom-designed software visualizes circular tunnels, and participants were asked to guide the virtual steerable tip without collision towards a target that located at the end of the virtual curved tunnel as fast as possible. The last part of this thesis presents four experiments using Endo-PaC for assessing two main aspects of manual controllability, cognitive aspect and ergonomic aspect, respectively. The first two experiments investigated two factors, visual-display compatibility and local disorientation, both of which contribute to spatial disorientation and yield a high cognitive load for surgeons in an endoscopic navigation task. The latter experiments assessed two methods of control mode, DR (Deflection Rotation) control and DD (Double Deflection) control, and two methods of control device, joystick control and handgrip control, for their effect on human performance with regard to task time, path length tracelled by the virtual tip, motion smoothness, subjective workload as well as personal preference. It is concluded that manual controllability is key to the success ratio of using handheld instruments in minimally invasive surgery. To new MIS procedures, such as pathway surgery, manoeuvrable instruments featuring ISS control allows less manoeuvrability but provide a strong benefit leading to easy control and high precision by just one clinician. Experiments with novice participants revealed that, in order to improve the manual controllability for ISS control during a navigation task, control interfacing featuring DD control leads to faster and safer performance compared with DR control, while handgrip control appeared to be more intuitive to master than joystick control. Furthermore, eliminating the visual-display misalignment, so that the controlled tip movements are in line with the surgeons hand movements, and providing a visible cue, so that the surgeon knows where the instruments heading for in the next advancing step, could greatly reduce the training time, facilitate performance and cause less cognitive load.","Minimally Invasive Surgery; Manual Control Interfacing; Steerable Instrument","en","doctoral thesis","","","","","","","","","Mechanical, Maritime and Materials Engineering","BioMechanical Engineering","","","",""
"uuid:2072623d-2139-4111-9e6f-3412ba2e1c64","http://resolver.tudelft.nl/uuid:2072623d-2139-4111-9e6f-3412ba2e1c64","Impact of Open Access Publication from the view of journal of Mechanical Sciences","Tolou, N.","","2014","","open access; international open access week; open access journals; motivations; publication statistics; citations; downloads; TU Delft","en","conference paper","TU Delft Library","","","","","","","","Mechanical, Maritime and Materials Engineering","BioMechanical Engineering","","","",""
"uuid:ce270203-0afc-4607-bd2d-1d8742e8b14b","http://resolver.tudelft.nl/uuid:ce270203-0afc-4607-bd2d-1d8742e8b14b","How valid are commercially available medical simulators?","Stunt, J.J.; Wulms, P.H.; Kerkhoffs, G.M.; Dankelman, J.; Van Dijk, C.N.; Tuijthof, G.J.M.","","2014","Background: Since simulators offer important advantages, they are increasingly used in medical education and medical skills training that require physical actions. A wide variety of simulators have become commercially available. It is of high importance that evidence is provided that training on these simulators can actually improve clinical performance on live patients. Therefore, the aim of this review is to determine the availability of different types of simulators and the evidence of their validation, to offer insight regarding which simulators are suitable to use in the clinical setting as a training modality. Summary: Four hundred and thirty-three commercially available simulators were found, from which 405 (94%) were physical models. One hundred and thirty validation studies evaluated 35 (8%) commercially available medical simulators for levels of validity ranging from face to predictive validity. Solely simulators that are used for surgical skills training were validated for the highest validity level (predictive validity). Twenty-four (37%) simulators that give objective feedback had been validated. Studies that tested more powerful levels of validity (concurrent and predictive validity) were methodologically stronger than studies that tested more elementary levels of validity (face, content, and construct validity). Conclusion: Ninety-three point five percent of the commercially available simulators are not known to be tested for validity. Although the importance of (a high level of) validation depends on the difficulty level of skills training and possible consequences when skills are insufficient, it is advisable for medical professionals, trainees, medical educators, and companies who manufacture medical simulators to critically judge the available medical simulators for proper validation. This way adequate, safe, and affordable medical psychomotor skills training can be achieved.","validity level; training modality; medical education; validation studies; medical skills training","en","journal article","Dove Medical Press","","","","","","","","Mechanical, Maritime and Materials Engineering","Biomechanical Engineering","","","",""
"uuid:c11ff40a-cf64-4459-95df-6908b6245354","http://resolver.tudelft.nl/uuid:c11ff40a-cf64-4459-95df-6908b6245354","Smart needles for percutaneous interventions","Henken, K.R.","Dankelman, J. (promotor); van den Dobbelsteen, J.J. (copromotor)","2014","The development of advanced needles for diagnostic and therapeutic purposes such as ablation and brachytherapy in the liver has offered minimally invasive therapies to patients that were previously untreatable. This thesis focuses on accurate placement of such needles guided by magnetic resonance imaging (MRI) to maximize the effect of the treatment and to minimize unwanted side-effects. To this end, an MRI-compatible steerable needle is developed which consists of a cable-actuated tip and a passively flexible shaft. The trajectory of this needle can be adjusted after the needle has been inserted. In addition, shape sensing based on optical strain sensors (fiber Bragg gratings or FBGs) is investigated aiming at feeding back information about the position and orientation of the needle tip in real-time. This is essential for accurate targeting, particularly when the needle trajectory is curved. Finally, steerability and shape sensing are integrated in a robotic system for needle steering in MRI-guided percutaneous interventions in the liver. The master-slave system comprises a steerable needle equipped with FBGs for tracking and a piezoelectric actuator unit. Needle insertion and steering is controlled by the physician through a master device, while FBG-based visual feedback of the needle shape is provided.","needle; robotics; FBG; biomedical engineering; sensors; MRI; medical instruments; shape sensing; needle steering","en","doctoral thesis","","","","","","","","2015-09-30","Mechanical, Maritime and Materials Engineering","BioMechanical Engineering","","","",""
"uuid:11e315ac-141d-4657-81b0-2e1f4a39bfac","http://resolver.tudelft.nl/uuid:11e315ac-141d-4657-81b0-2e1f4a39bfac","Surgical device, in particular for minimally invasive surgery","Tuijthof, G.J.M.; Horeman, T.","","2014","Surgical device, in particular for minimally invasive surgery, provided with a shaft having a distal end to which a surgical instrument is mounted or mountable and a proximal end equipped for handling the instrument, wherein the shaft is hollow and the surgical instrument is mounted or mountable on inserts that are longitudinally movable in the said shaft parallel to the longitudinal axis of the shaft, which inserts are provided diametrically opposed to each other within said shaft. The shaft comprises an outer tube and an inner tube which are rotatable in opposite directions with respect to the longitudinal axis of the shaft, and the inserts are coupled to the outer tube and the inner tube so as to convert rotational movement of said tubes into longitudinal movement of the inserts.","","en","patent","European Patent Office","","","","","","","","Mechanical, Maritime and Materials Engineering","Biomechanical Engineering","","","",""
"uuid:75b9f6e8-84c0-4b56-bbdf-dda274c09597","http://resolver.tudelft.nl/uuid:75b9f6e8-84c0-4b56-bbdf-dda274c09597","MRI-Compatible Endovascular Instruments: Improved Maneuverability during Navigation","Clogenson, H.C.M.","Dankelman, J. (promotor); Van den Dobbelsteen, J.J. (promotor)","2014","Endovascular diagnostics and interventions are performed using long, thin and flexible instruments that are inserted in the blood vessel and manipulated toward a target in the vasculature. This technique has proven to be successful with the millions of patients diagnosed and treated worldwide every year. Though, this technique presents several drawbacks: the tools are limited in shape and flexibility and are difficult to control and, as endovascular interventions are performed under 2D projection X-ray image guidance, any difficulty in navigating the instruments increases exposure of patient and staff to ionizing radiation. In this thesis, we focus on the navigation challenges during procedures performed in the peripheral vasculature. It is imperative to reach the target in the anatomy quickly and safely, while protecting both the patient and staff from ionizing radiation. For this reason, navigation under Magnetic Resonance Imaging (MRI) is considered. In this project, novel endovascular instruments with improved maneuverability at the tip were designed to support navigation during endovascular intervention in the peripheral vascular tree under real-time MRI guidance. The instruments were assembled, and their capabilities evaluated in pre-clinical settings. We believe that the designed instruments are a good first step toward novel easy-to-use endovascular instruments, which will enable interventionalists to perform a broader range of interventions more quickly, safely and with greater accuracy under MRI-guidance (or X-ray). Fully compatible with conventional instruments, they will increase the efficiency of cath-labs without requiring the purchase of additional equipment.","Deflectable; Interventional Radiology; Magnetic Resonance Imaging; Steerable","en","doctoral thesis","","","","","","","","2015-09-08","Mechanical, Maritime and Materials Engineering","BioMechanical Engineering","","","",""
"uuid:df44d0c7-0b83-478c-8fd0-c969202eda1e","http://resolver.tudelft.nl/uuid:df44d0c7-0b83-478c-8fd0-c969202eda1e","The influence of water jet diameter and bone structural properties on the efficiency of pure water jet drilling in porcine bone","Den Dunnen, S.; Tuijthof, G.J.M.","","2014","Using water jets in orthopedic surgery to drill holes in bones can be beneficial due to the absence of thermal damage and the always sharp cut. To minimize operating time and the volume of water that is used, the efficiency (volume of removed bone per added volume of water) of the water jet should be maximized. The goal was to study the effect of the open trabecular bone structure on the efficiency for different water jet diameters. 86 holes were drilled in porcine tali and femora submerged in water with nozzles of 0.3, 0.4, 0.5 and 0.6mm at 70MPa during 5 s and a standoff distance of 8 mm. MicroCT scans were made to measure the removed bone volume and the bone structural properties Trabecular Spacing (Tb.Sp.), Trabecular Thickness (Tb.Sp.) and Bone Volume Fraction (BV/TV). Pearson’s correlation tests (p < 0.05, 95% confidence interval) were performed for each water jet diameter using the bone structural property as an independent factor and the efficiency as a dependent factor. No significant differences were found between the nozzle diameters in the material removal rates per added volume of water. The efficiency decreased for an increase in Tb.Th. and BV/TV for nozzles of 0.3, 0.4 and 0.5 mm. The 0.6mm nozzle showed less influence of the Tb.Th. and BV/TV. The Tb.Sp. has no influence on the efficiency of a water jet. The total volume of added water combined with the Tb.Th. or BV/TV is a leading measure for the volume of bone material that is removed, which provides freedom in the development of water jet instruments as the nozzle diameter, pressure and jet time can be chosen in accordance to the maximum operating time requirements or dimensional limitations of a design.","OA-Fund TU Delft","en","journal article","Copernicus Publications","","","","","","","","Mechanical, Maritime and Materials Engineering","Biomechanical Engineering","","","",""
"uuid:e2623fdd-8747-4ec4-8abc-4bd7ec16939a","http://resolver.tudelft.nl/uuid:e2623fdd-8747-4ec4-8abc-4bd7ec16939a","A method to model anticipatory postural control in driver braking events","Osth, J.; Eliasson, E.; Happee, R.; Brolin, K.","","2014","Human body models (HBMs) for vehicle occupant simulations have recently been extended with active muscles and postural control strategies. Feedback control has been used to model occupant responses to autonomous braking interventions. However, driver postural responses during driver initiated braking differ greatly from autonomous braking. In the present study, an anticipatory postural response was hypothesized, modelled in a whole-body HBM with feedback controlled muscles, and validated using existing volunteer data. The anticipatory response was modelled as a time dependent change in the reference value for the feedback controllers, which generates correcting moments to counteract the braking deceleration. The results showed that, in 11 m/s2 driver braking simulations, including the anticipatory postural response reduced the peak forward displacement of the head by 100 mm, of the shoulder by 30 mm, while the peak head flexion rotation was reduced by 18°. The HBM kinematic response was within a one standard deviation corridor of corresponding test data from volunteers performing maximum braking. It was concluded that the hypothesized anticipatory responses can be modelled by changing the reference positions of the individual joint feedback controllers that regulate muscle activation levels. The addition of anticipatory postural control muscle activations appears to explain the difference in occupant kinematics between driver and autonomous braking. This method of modelling postural reactions can be applied to the simulation of other driver voluntary actions, such as emergency avoidance by steering.","human body model; anticipatory postural control; active muscles; driver braking","en","journal article","Elsevier","","","","","","","","Mechanical, Maritime and Materials Engineering","Biomechanical Engineering","","","",""
"uuid:faeb5c70-1b7d-460f-b73f-6685df296a11","http://resolver.tudelft.nl/uuid:faeb5c70-1b7d-460f-b73f-6685df296a11","A novel self-aligning mechanism to decouple force and torques for a planar exoskeleton joint","Schorsch, J.F.; Keemink, A.Q.L.; Stienen, A.H.A.; Van der Helm, F.C.T.; Abbink, D.A.","","2014","The design of exoskeletons is a popular and promising area of research both for restoring lost function and rehabilitation, and for augmentation in military and industrial applications. A major practical challenge to the comfort and usability for exoskeletons is the need to avoid misalignment of the exoskeletal joint with the underlying human joint. Alignment mismatches are difficult to prevent due to large inter-user variability, and can create large stresses on the attachment system and underlying human anatomy. Previous self-aligning systems have been proposed in literature, which can compensate for muscle forces, but leave large residual forces passed directly to the skeletal system. In this paper we propose a new mechanism to reduce misalignment complications. A decoupling approach is proposed which allows large forces to be carried by the exoskeletal system while allowing both the muscle and skeletal joint force presented to the user to be compensated to any desired degree.","OA-Fund TU Delft","en","journal article","Copernicus Publications","","","","","","","","Mechanical, Maritime and Materials Engineering","Biomechanical Engineering","","","",""
"uuid:77ed9363-9abe-4a8a-8aee-ae3d3c34e071","http://resolver.tudelft.nl/uuid:77ed9363-9abe-4a8a-8aee-ae3d3c34e071","Balance asymmetry in Parkinson's disease and its contribution to freezing of gait","Boonstra, T.A.; Van Vugt, J.P.P.; Van der Kooij, H.; Bloem, B.R.","","2014","Balance control (the ability to maintain an upright posture) is asymmetrically controlled in a proportion of patients with Parkinson’s disease. Gait asymmetries have been linked to the pathophysiology of freezing of gait. We speculate that asymmetries in balance could contribute to freezing by a) hampering the unloading of the stepping leg and/or b) leading to a preferred stance leg during gait, which then results in asymmetric gait. To investigate this, we examined the relationship between balance control and weight-bearing asymmetries and freezing. We included 20 human patients with Parkinson (tested OFF medication; nine freezers) and nine healthy controls. Balance was perturbed in the sagittal plane, using continuous multi-sine perturbations, applied by a motion platform and by a force at the sacrum. Applying closed-loop system identification techniques, relating the body sway angle to the joint torques of each leg separately, determined the relative contribution of each ankle and hip joint to the total amount of joint torque. We also calculated weight-bearing asymmetries. We determined the 99-percent confidence interval of weight-bearing and balance-control asymmetry using the responses of the healthy controls. Freezers did not have larger asymmetries in weight bearing (p = 0.85) nor more asymmetrical balance control compared to non-freezers (p = 0.25). The healthy linear one-to-one relationship between weight bearing and balance control was significantly different for freezers and non-freezers (p = 0.01). Specifically, nonfreezers had a significant relationship between weight bearing and balance control (p = 0.02), whereas this relation was not significant for freezers (p = 0.15). Balance control is asymmetrical in most patients (about 75 percent) with Parkinson’s disease, but this asymmetry is not related to freezing. The relationship between weight bearing and balance control seems to be less pronounced in freezers, compared to healthy controls and non-freezers. However, this relationship should be investigated further in larger groups of patients.","","en","journal article","Public Library of Science","","","","","","","","Mechanical, Maritime and Materials Engineering","Biomechanical Engineering","","","",""
"uuid:302b8e30-6dd7-469d-b63a-47e73795b3ba","http://resolver.tudelft.nl/uuid:302b8e30-6dd7-469d-b63a-47e73795b3ba","How cognitive enhancement can change our duties","Santoni de Sio, F.; Faulmüller, N.; A Vincent, N.","","2014","This theoretical paper draws the scientific community’s attention to how pharmacological cognitive enhancement may impact on society and law. Namely, if safe, reliable, and effective techniques to enhance mental performance are eventually developed, then this may under some circumstances impose new duties onto people in high-responsibility professions—e.g., surgeons or pilots—to use such substances to minimize risks of adverse outcomes or to increase the likelihood of good outcomes. By discussing this topic, we also hope to encourage scientists to bring their expertise to bear on this current public debate.","","en","journal article","Frontiers","","","","","","","","Mechanical, Maritime and Materials Engineering","Biomechanical Engineering","","","",""
"uuid:57f85414-fe2d-4e83-a683-142f011ede96","http://resolver.tudelft.nl/uuid:57f85414-fe2d-4e83-a683-142f011ede96","Balance and control of a rear-wheel steered speed-record recumbent bicycle","Schwab, A.L.; Kooijman, J.D.G.","","2014","The goal of the Human Power Team from the TU Delft and the Free University of Amsterdam is to break the world speed record in unpaced cycling (Sam Whittingham, 133.28 km/h). The design of such a faired recumbent bicycle is a challenge. The Delft design, called VeloX (Human Power Team (2013)), is a fully-faired monocoque front-driven recumbent bicycle, with minimized air drag and maximized space for a big and strong athlete. However, front driven bicycles have the disadvantage that the front driving induces unwanted steering and that the frontal area of the bicycle cannot be reduced any further. A solution would be rear-wheel steering. A common thought is that a rear-wheel steered bicycle cannot be laterally self-stable, and therefore hard to control. However, recent research (Knoll et al. (2012)) has shown that one can design a rear-wheel steered bicycle which shows a stable forward speed range. Based on these results a rear-wheel steered recumbent bicycle has been designed, within the existing design constraints. Although not self-stable, this design shows a mildly lateral unstable behavior in the desired forward speed range of 0 to 40 m/s (0 to 144 km/h). Computer simulations demonstrate that the bicycle can be stabilized by adding a human controller model (Schwab et al. (2013)) to the bicycle model. For a set of expected lateral perturbations (side wind perturbations) it is shown that rider steer torque stays within human bounds, both in magnitude and in frequency. Future work is dedicated to building and testing a prototype of the design.","bicycle; dynamics; control; design; rear wheel steering","en","conference paper","Elsevier","","","","","","","","Mechanical, Maritime and Materials Engineering","Biomechanical Engineering","","","",""
"uuid:8a1fab62-ff71-42dc-ab97-a55c7b5c7492","http://resolver.tudelft.nl/uuid:8a1fab62-ff71-42dc-ab97-a55c7b5c7492","EEG beta suppression and low gamma modulation are different elements of human upright walking","Seeber, M.; Scherer, R.; Wagner, J.; Solis Escalante, T.; Müller-Putz, G.R.","","2014","Cortical involvement during upright walking is not well-studied in humans. We analyzed non-invasive electroencephalographic (EEG) recordings from able-bodied volunteers who participated in a robot-assisted gait-training experiment. To enable functional neuroimaging during walking, we applied source modeling to high-density (120 channels) EEG recordings using individual anatomy reconstructed from structural magnetic resonance imaging scans. First, we analyzed amplitude differences between the conditions, walking and upright standing. Second, we investigated amplitude modulations related to the gait phase. During active walking upper ? (10–12 Hz) and ? (18–30 Hz) oscillations were suppressed [event-related desynchronization (ERD)] compared to upright standing. Significant ? ERD activity was located focally in central sensorimotor areas for 9/10 subjects. Additionally, we found that low ? (24–40 Hz) amplitudes were modulated related to the gait phase. Because there is a certain frequency band overlap between sustained ? ERD and gait phase related modulations in the low ? range, these two phenomena are superimposed. Thus, we observe gait phase related amplitude modulations at a certain ERD level. We conclude that sustained ? and ? ERD reflect a movement related state change of cortical excitability while gait phase related modulations in the low ? represent the motion sequence timing during gait. Interestingly, the center frequencies of sustained ? ERD and gait phase modulated amplitudes were identified to be different. They may therefore be caused by different neuronal rhythms, which should be taken under consideration in future studies.","electroencephalography (EEG); gait; brain mapping; motor cortex; magnetic resonance imaging","en","journal article","Frontiers","","","","","","","","Mechanical, Maritime and Materials Engineering","Biomechanical Engineering","","","",""
"uuid:5b9c836b-31a7-4932-a2ef-2a2793499ed0","http://resolver.tudelft.nl/uuid:5b9c836b-31a7-4932-a2ef-2a2793499ed0","EMG patterns during assisted walking in the exoskeleton","Sylos-Labini, F.; La Scaleia, V.; d'Avella, A.; Pisotta, I.; Tamburella, F.; Scivoletto, G.; Molinari, M.; Wang, S.; Wang, L.; Van Asseldonk, E.; Van der Kooij, H.; Hoellinger, T.; Cheron, G.; Thorsteinsson, F.; Ilzkovitz, M.; Gancet, J.; Hauffe, R.; Zanov, F.; Lacquaniti, F.; Ivanenko, Y.P.","","2014","Neuroprosthetic technology and robotic exoskeletons are being developed to facilitate stepping, reduce muscle efforts, and promote motor recovery. Nevertheless, the guidance forces of an exoskeleton may influence the sensory inputs, sensorimotor interactions and resulting muscle activity patterns during stepping. The aim of this study was to report the muscle activation patterns in a sample of intact and injured subjects while walking with a robotic exoskeleton and, in particular, to quantify the level of muscle activity during assisted gait. We recorded electromyographic (EMG) activity of different leg and arm muscles during overground walking in an exoskeleton in six healthy individuals and four spinal cord injury (SCI) participants. In SCI patients, EMG activity of the upper limb muscles was augmented while activation of leg muscles was typically small. Contrary to our expectations, however, in neurologically intact subjects, EMG activity of leg muscles was similar or even larger during exoskeleton-assisted walking compared to normal overground walking. In addition, significant variations in the EMG waveforms were found across different walking conditions. The most variable pattern was observed in the hamstring muscles. Overall, the results are consistent with a non-linear reorganization of the locomotor output when using the robotic stepping devices. The findings may contribute to our understanding of human-machine interactions and adaptation of locomotor activity patterns.","robotic exoskeleton; assisted gait; EMG patterns; spinal cord injury; neuroprosthetic technology","en","journal article","Frontiers","","","","","","","","Mechanical, Maritime and Materials Engineering","Biomechanical Engineering","","","",""
"uuid:b91ab314-daa3-4857-acfc-3edf134579ea","http://resolver.tudelft.nl/uuid:b91ab314-daa3-4857-acfc-3edf134579ea","Computational bone mechanics: The interrelationships between shape, density distribution, and loading","Campoli, G.","Weinans, H.H. (promotor); Zadpoor, A.A. (promotor)","2014","","Finite Element Method; Biomechanics; Artificial Neural Networks; Muscoloskeletal models","en","doctoral thesis","","","","","","","","","Mechanical, Maritime and Materials Engineering","BioMechanical Engineering","","","",""
"uuid:25897a06-bb52-4adc-b015-a0b6c80ab3d2","http://resolver.tudelft.nl/uuid:25897a06-bb52-4adc-b015-a0b6c80ab3d2","Fabrication of metallic biomedical scaffolds with the space holder method: A review","Arifvianto, B.; Zhou, J.","","2014","Bone tissue engineering has been increasingly studied as an alternative approach to bone defect reconstruction. In this approach, new bone cells are stimulated to grow and heal the defect with the aid of a scaffold that serves as a medium for bone cell formation and growth. Scaffolds made of metallic materials have preferably been chosen for bone tissue engineering applications where load-bearing capacities are required, considering the superior mechanical properties possessed by this type of materials to those of polymeric and ceramic materials. The space holder method has been recognized as one of the viable methods for the fabrication of metallic biomedical scaffolds. In this method, temporary powder particles, namely space holder, are devised as a pore former for scaffolds. In general, the whole scaffold fabrication process with the space holder method can be divided into four main steps: (i) mixing of metal matrix powder and space-holding particles; (ii) compaction of granular materials; (iii) removal of space-holding particles; (iv) sintering of porous scaffold preform. In this review, detailed procedures in each of these steps are presented. Technical challenges encountered during scaffold fabrication with this specific method are addressed. In conclusion, strategies are yet to be developed to address problematic issues raised, such as powder segregation, pore inhomogeneity, distortion of pore sizes and shape, uncontrolled shrinkage and contamination.","tissue engineering; scaffold; space holder method; powder metallurgy; titanium","en","journal article","MDPI","","","","","","","","Mechanical, Maritime and Materials Engineering","Biomechanical Engineering","","","",""
"uuid:4bf60a69-48b7-46b0-a955-b267da3cb969","http://resolver.tudelft.nl/uuid:4bf60a69-48b7-46b0-a955-b267da3cb969","Porous titanium for bone substitution: Mechanobiology meets surface science","Amin Yavari, S.","Weinans, H. (promotor)","2014","People in both developing and developed worlds are increasingly facing musculoskeletal problems that require long-term clinical performance of orthopaedic implants including bone substitutes. Porous biomaterials could play an important role in improving the longevity and overall performance of orthopaedic implants and that is why they have been extensively studied recently. Highly porous biomaterials hold promise for such applications partly because their porous structures provide enough space for bone in-growth and vascularization. Controllability of mechanical properties is another favorable feature of such biomaterials that has led to their increased popularity for bone substitution. Nevertheless, the full potential of porous metallic biomaterials in general and porous titanium alloy structures in particular has not yet been fully exploited. In this thesis, some important aspects relevant for application of porous titanium alloy biomaterials as bone substitutes have been studied. In particular, we focus on the mechanical properties of porous titanium biomaterials, the modification of the surface properties of such biomaterials using chemical and electrochemical surface treatments, and on the effects of applied surface treatment on the mechanical properties of porous titanium biomaterials. To study the mechanical properties of porous titanium biomaterials, it is important to study the mechanical properties of bone that is replaced by the biomaterial. Given the fact that bone is a complex and heterogeneous material, a recently developed method called digital image correlation (DIC) was employed to study the full-field strain map and fracture behavior of the rat femur (chapter 2). It was found that bone fracture is strain-controlled and that the onset of fracture could be predicted using the equivalent strain criterion. On the other hand, segmental bone defect animal models are often used in pre-clinical studies of the bone regeneration performance of bone substitutes. In such animal models, it is very important to study how mechanical load is transferred after stabilization of the defect. In chapter 3, a specific animal model and fixation technique were considered. The load transferred through the femur and the distribution of the transferred load between the implant and fixation plate were studied for the considered animal model and fixation technique. It was found that there is a large variability in terms of the transmitted loads and that one needs to optimize the fixation technique in order to obtain a more consistent mechanical loading after surgery. Dynamic and static mechanical properties of selective laser melted porous titanium were studied in chapter 4 where the S-N curves of the porous structures were obtained for four different porosities. The S-N curves of the porous structures with different porosities were drastically different with more porous structures demonstrating a weaker fatigue behavior. When normalized with respect to the plateau stress, the S-N curves were mostly overlapping and very well conforming to a power law (R2=0.94). This power law might be useful for estimating the fatigue life of similar porous structures in the cases where actual fatigue tests could not be performed. In addition, it was found that the normalized endurance limit of porous structures is somewhat lower than that of the matrix material. Bio-functionalizing surface treatment are important for improving the surface properties of biomaterials. However, they might adversely affect the mechanical properties of the biomaterial. The effects of two different types of chemical surface treatments, namely alkali-acid-heat treatment and acid-alkali treatment, on the mechanical properties of porous titanium biomaterials were studied. It was found that while one of the surface treatments, namely alkali-acid-heat treatment, did not have any major adverse effect on the mechanical properties of the tested biomaterials, the other surface treatment resulted in significant mass loss and, thus, significant loss of mechanical properties. The nanotopographical features and crystal structure of an additional surface treatment technique, namely anodizing, were studied as well. The parameters of the surface treatment procedure were optimized to achieve a hierarchical structure on the surface of porous titanium biomaterials. In addition, it was found that the temperature and heat treatment duration need to be optimized, so as to ensure the nanotopographical features created using the surface treatment are not disrupted after heat treatment. All the three above-mentioned surface treatment techniques were subsequently evaluated in a longitudinal in-vivo and in-vitro study to assess the bone regeneration performance, apatite-forming ability, and cell response of the surface-treated porous titanium biomaterials. It was found that the applied surface treatments notably influenced both in-vitro and in-vivo performances of porous titanium alloy biomaterials. Acid-alkali treatment resulted in the best apatite forming ability and significantly larger volumes of regenerated bone as compared to anodizing. However, porous titanium biomaterials treated with anodizing exhibited significantly higher torsional strength. It was concluded that larger volumes of regenerated bone does not necessarily translate to better mechanical stability. Although this thesis tried to cover several aspects relevant for application of porous titanium biomaterials as bone substitutes, further research is needed to explore several other unexplored aspects of porous titanium biomaterials.","porous titanium; biomaterials; mechanobiology; surface science","en","doctoral thesis","","","","","","","","","Mechanical, Maritime and Materials Engineering","BioMechanical Engineering","","","",""
"uuid:08db0fa0-08c0-47d0-b017-201df465b334","http://resolver.tudelft.nl/uuid:08db0fa0-08c0-47d0-b017-201df465b334","Validation of the in vivo volumetric wear measurement for total knee prostheses in model-based RSA","Van IJsseldijk, E.A.; Lebel, B.; Stoel, B.C.; Valstar, E.R.; Gouzy, S.; Vielpeau, C.; Kaptein, B.L.","","2014","Implant failure related to polyethylene wear remains an important issue in total knee arthroplasty. Polyethylene wear is usually assessed in vivo by measuring the remaining insert thickness on X-ray images of the knee. To reflect the amount of wear debris more accurately, a 3-dimensional overlap measurement has been suggested, which is based on implant component models which are matched on calibrated stereo X-ray images using model-based roentgen stereophotogrammatic analysis. The goal of this study was to determine the influence of pose estimation, insert thickness deviation and variation in the femoral-tibial contact location on the accuracy and precision of the measurement using simulations and a phantom experiment. We found that the pose estimation was the largest source of variation. The 95% prediction interval varied between 111 and 283 mm3, which is approximately 100–200% of the detected volumetric wear. Insert thickness variation resulted in prediction intervals of 74–174 mm3. Variation of the femoral-tibial contact location in the phantom experiment gave a prediction interval of 40 mm3. Large differences in the detected wear volume were found for different flexion angles. At most 56% of the true wear volume was detected (129 of 230 mm3, 30° of flexion). In summary, both the accuracy and precision of the volumetric wear measurement were low. The prediction interval of the volumetric wear measurement is at least as large as the measurement outcome itself. This is an important limitation to the applicability of the volumetric wear measurement in clinical practice and further clinical validation is required.","total knee arthroplasty; polyethylene wear; image-based measurements; model-based RSA","en","journal article","Elsevier","","","","","","","","Mechanical, Maritime and Materials Engineering","Biomechanical Engineering","","","",""
"uuid:d2e38b97-1a2a-492a-ab60-e8403422adf5","http://resolver.tudelft.nl/uuid:d2e38b97-1a2a-492a-ab60-e8403422adf5","Evaluation of EMG, force and joystick as control interfaces for active arm supports","Lobo-Prat, J.; Keemink, A.Q.L.; Stienen, A.H.A.; Schouten, A.C.; Veltink, P.H.; Koopman, B.F.J.M.","","2014","Background: The performance capabilities and limitations of control interfaces for the operation of active movement-assistive devices remain unclear. Selecting an optimal interface for an application requires a thorough understanding of the performance of multiple control interfaces. Methods: In this study the performance of EMG-, force- and joystick-based control interfaces were assessed in healthy volunteers with a screen-based one-dimensional position-tracking task. The participants had to track a target that was moving according to a multisine signal with a bandwidth of 3 Hz. The velocity of the cursor was proportional to the interface signal. The performance of the control interfaces were evaluated in terms of tracking error, gain margin crossover frequency, information transmission rate and effort. Results: None of the evaluated interfaces was superior in all four performance descriptors. The EMG-based interface was superior in tracking error and gain margin crossover frequency compared to the force- and the joystick-based interfaces. The force-based interface provided higher information transmission rate and lower effort than the EMG-based interface. The joystick-based interface did not present any significant difference with the force-based interface for any of the four performance descriptors. We found that significant differences in terms of tracking error and information transmission rate were present beyond 0.9 and 1.4 Hz respectively. Conclusions: Despite the fact that the EMG-based interface is far from the natural way of interacting with the environment, while the force-based interface is closer, the EMG-based interface presented very similar and for some descriptors even a better performance than the force-based interface for frequencies below 1.4 Hz. The classical joystick presented a similar performance to the force-based interface and holds the advantage of being a well established interface for the control of many assistive devices. From these findings we concluded that all the control interfaces considered in this study can be regarded as a candidate interface for the control of an active arm support.","control interface; electromyography; force; joystick; performance evaluation; learning curve; human-operator; OA-Fund TU Delft","en","journal article","BioMed Central","","","","","","","","Mechanical, Maritime and Materials Engineering","Biomechanical Engineering","","","",""
"uuid:952735c4-bfc0-4828-b217-b9ecb252f7f7","http://resolver.tudelft.nl/uuid:952735c4-bfc0-4828-b217-b9ecb252f7f7","The effect of impedance-controlled robotic gait training on walking ability and quality in individuals with chronic incomplete spinal cord injury: An explorative study","Fleerkotte, B.M.; Koopman, B.; Buurke, J.H.; Van Asseldonk, E.H.F.; Van der Kooij, H.; Rietman, J.S.","","2014","Background There is increasing interest in the use of robotic gait-training devices in walking rehabilitation of incomplete spinal cord injured (iSCI) individuals. These devices provide promising opportunities to increase the intensity of training and reduce physical demands on therapists. Despite these potential benefits, robotic gait-training devices have not yet demonstrated clear advantages over conventional gait-training approaches, in terms of functional outcomes. This might be due to the reduced active participation and step-to-step variability in most robotic gait-training strategies, when compared to manually assisted therapy. Impedance-controlled devices can increase active participation and step-to-step variability. The aim of this study was to assess the effect of impedance-controlled robotic gait training on walking ability and quality in chronic iSCI individuals. Methods A group of 10 individuals with chronic iSCI participated in an explorative clinical trial. Participants trained three times a week for eight weeks using an impedance-controlled robotic gait trainer (LOPES: LOwer extremity Powered ExoSkeleton). Primary outcomes were the 10-meter walking test (10MWT), the Walking Index for Spinal Cord Injury (WISCI II), the six-meter walking test (6MWT), the Timed Up and Go test (TUG) and the Lower Extremity Motor Scores (LEMS). Secondary outcomes were spatiotemporal and kinematics measures. All participants were tested before, during, and after training and at 8 weeks follow-up. Results Participants experienced significant improvements in walking speed (0.06 m/s, p?=?0.008), distance (29 m, p?=?0.005), TUG (3.4 s, p?=?0.012), LEMS (3.4, p?=?0.017) and WISCI after eight weeks of training with LOPES. At the eight-week follow-up, participants retained the improvements measured at the end of the training period. Significant improvements were also found in spatiotemporal measures and hip range of motion. Conclusion Robotic gait training using an impedance-controlled robot is feasible in gait rehabilitation of chronic iSCI individuals. It leads to improvements in walking ability, muscle strength, and quality of walking. Improvements observed at the end of the training period persisted at the eight-week follow-up. Slower walkers benefit the most from the training protocol and achieve the greatest relative improvement in speed and walking distance.","spinal cord injury; robotic gait rehabilitation; locomotor training; impedance control; OA-Fund TU Delft","en","journal article","BioMed Central","","","","","","","","Mechanical, Maritime and Materials Engineering","Biomechanical Engineering","","","",""
"uuid:0fdc13c0-af9a-4f67-96f5-28107bbec3c0","http://resolver.tudelft.nl/uuid:0fdc13c0-af9a-4f67-96f5-28107bbec3c0","Force-based assessment of tissue handling skills","Horeman, T.","Dankelman, J. (promotor); Jansen, F.W. (promotor); van den Dobbelsteen, J.J. (copromotor)","2014","In laparoscopic surgery, special instruments with long and slender shafts are inserted through small incisions in the abdominal wall. A laparoscope is used for a clear vision inside the inflated abdominal cavity while laparoscopic graspers and cutters are used for manipulation of tissue. The use of long instruments makes it difficult to “feel” the force exerted on tissue during manipulation especially when friction factors disturb the force sensation even further. Tissue manipulation plays an important role in surgery and there is relatively little knowledge of forces applied on tissue during surgery. The main objectives of this thesis were to develop force measurement systems to measure the forces during training, to combine motion and force measurements to come to objective assessment of training of basic MIS skills, and finally to develop force feedback systems to improve force application during training. The first part of this thesis focuses on the force exerted by the instrument tips during placement of surgical sutures. In many educational programs in surgery, the suture task is used to test the technical skills of the trainee. We proved that the force exerted on the suture pad can be recorded without modification of the instruments or suture pad if a 3DOF force sensor is placed under the suture pad in a box trainer. We showed that performance parameters can be calculated from recorded force data to expose skills important for safe tissue handling during suturing. A validation study showed that it is possible to classify participants with an accuracy of 84% if only force parameters are used. The second part of this thesis describes a method to reduce the tissue handling force of trainees. By generating a virtual arrow in the laparoscopic image that represents the size and direction of the exerted force during suturing in real time, we found that training with well explained visual feedback can help trainees to minimize the interaction force during needle insertion in a box trainer. For training of wound suturing outside the box trainer, we found that colours, representing the exerted force on the tissue, can help trainees to balance forces between the two tensioned threads during knot tying and to improve the quality of the knot. In another study we showed that it is possible to inform the surgeon about the pulling force during surgery if a small and lightweight sensor is used that can be easily attached to the tensioned thread. The third part of this thesis we integrated the TrEndo and a force platform into ForMoST, a box trainer that measures both tissue handling force as instrument motion. For this box trainer we developed and validated two new bimanual training tasks for training of tissue handling. The validation study performed with novices, intermediates and experts indicated that force parameters are not strongly correlated to motion parameters and that force and motion parameters have similar discriminative power in both tasks. A study performed with novices that received visual force feedback or visual time feedback during training indicated that visual force feedback during training reduces the tissue manipulation force significantly even when a post task is performed that is different from the training task. We showed that training with visual force feedback improves tissue handling skills with no negative effect on task time and instrument motion and that training with visual time feedback improves instrument motion and task time, but does not improve tissue manipulation skills. This thesis contributes to the field of training of surgical skills in multiple ways. Mechanical force sensors were developed that can be used for training of tissue handling, to find force thresholds for traction on tissues or for safety monitoring during suturing of incisions. It is shown that force parameters that reflect tissue handling or suture tension, can now be used to inform surgeons about the risk of tissue damage while training laparoscopic skills or suturing tissues.","tissue handling skills; force parameters; motion parameters; surgical sutures; laparoscopy; training","en","doctoral thesis","","","","","","","","","Mechanical, Maritime and Materials Engineering","BioMechanical Engineering","","","",""
"uuid:c4f20906-f0ce-405c-944e-7dfe8284669b","http://resolver.tudelft.nl/uuid:c4f20906-f0ce-405c-944e-7dfe8284669b","Mapping patient safety: A large-scale literature review using bibliometric visualisation techniques","Rodrigues, S.P.; Van Eck, N.J.; Waltman, L.; Jansen, F.W.","","2014","Background The amount of scientific literature available is often overwhelming, making it difficult for researchers to have a good overview of the literature and to see relations between different developments. Visualisation techniques based on bibliometric data are helpful in obtaining an overview of the literature on complex research topics, and have been applied here to the topic of patient safety (PS). Methods On the basis of title words and citation relations, publications in the period 2000–2010 related to PS were identified in the Scopus bibliographic database. A visualisation of the most frequently cited PS publications was produced based on direct and indirect citation relations between publications. Terms were extracted from titles and abstracts of the publications, and a visualisation of the most important terms was created. The main PS-related topics studied in the literature were identified using a technique for clustering publications and terms. Results A total of 8480 publications were identified, of which the 1462 most frequently cited ones were included in the visualisation. The publications were clustered into 19 clusters, which were grouped into three categories: (1) magnitude of PS problems (42% of all included publications); (2) PS risk factors (31%) and (3) implementation of solutions (19%). In the visualisation of PS-related terms, five clusters were identified: (1) medication; (2) measuring harm; (3) PS culture; (4) physician; (5) training, education and communication. Both analysis at publication and term level indicate an increasing focus on risk factors. Conclusions A bibliometric visualisation approach makes it possible to analyse large amounts of literature. This approach is very useful for improving one's understanding of a complex research topic such as PS and for suggesting new research directions or alternative research priorities. For PS research, the approach suggests that more research on implementing PS improvement initiatives might be needed.","","en","journal article","BMJ Publishing Group","","","","","","","","Mechanical, Maritime and Materials Engineering","Biomechanical Engineering","","","",""
"uuid:dcefd6fd-b198-47da-8862-549e94003d9c","http://resolver.tudelft.nl/uuid:dcefd6fd-b198-47da-8862-549e94003d9c","HEADS UP: Sensorimotor control of the head-neck system","Forbes, P.A.","Van der Helm, F.C.T. (promotor); Happee, R. (promotor); Schouten, A.C. (promotor)","2014","Head-neck stabilization is inherently challenging even when stationary, requiring constant vigilance to counter the downward pull of gravity. It involves a highly complex biomechanical system comprised of a large mass (the head) balanced on top of seven vertebrae (the neck), that are in turn connected to a moving base (the torso). This multi-degree-of-freedom system is controlled by an equally impressive array of more than 30 bilateral muscle pairs that connect across various combinations of the skull, vertebrae and thorax. Visual and vestibular systems, together with neck somatosensory inputs are integrated by the central nervous system to provide an estimate of both the external world and an internal representation of ourselves. When our external (or internal) environments change, for example through unexpected or unpredictable disturbances, neck muscles make nimble corrections, through CNS control, to ensure the head remains upright and stable. However, for patients suffering from neck sensorimotor disorders, stable head posture is a constant challenge, often leading to complaints of neck pain and fatigue. This thesis investigates the contribution of different sensory feedback mechanisms – with particular focus on vestibular and proprioception sensory systems – to natural head-neck stabilization. The experimental methods developed and the research outcomes obtained from studying healthy controls are in turn used to investigate patients suffering from the neck movement disorder, cervical dystonia. This thesis draws two primary conclusions. The first conclusion is that healthy subjects substantially modulate vestibular and proprioception reflexes with the bandwidth and amplitude of torso perturbations, and that this modulation is dependent upon the presence of visual feedback and the descending motor command. In cervical dystonia patients, neck reflex dynamics were modulated across conditions in a manner similar to healthy controls, provided patients were engaged in a task to overcome the reorienting effects of the dystonia. The second conclusion is that the neurophysiological properties of the vestibular neck reflex indicate a highly robust and wide bandwidth influence of vestibular information over neck muscle control that differs markedly from other muscles throughout the body.","head-neck stabilization; sensorimotor control; vestibular; proprioception; cervical dystonia; system identification","en","doctoral thesis","","","","","","","","","Mechanical, Maritime and Materials Engineering","BioMechanical Engineering","","","",""
"uuid:ab1990d3-825b-4905-a651-9c1c5de6005b","http://resolver.tudelft.nl/uuid:ab1990d3-825b-4905-a651-9c1c5de6005b","It's how you get there: Walking down a virtual alley activates premotor and parietal areas","Wagner, J.; Solis-Escalante, T.; Scherer, R.; Neuper, C.; Müller-Putz, G.","","2014","Voluntary drive is crucial for motor learning, therefore we are interested in the role that motor planning plays in gait movements. In this study we examined the impact of an interactive Virtual Environment (VE) feedback task on the EEG patterns during robot assisted walking. We compared walking in the VE modality to two control conditions: walking with a visual attention paradigm, in which visual stimuli were unrelated to the motor task; and walking with mirror feedback, in which participants observed their own movements. Eleven healthy participants were considered. Application of independent component analysis to the EEG revealed three independent component clusters in premotor and parietal areas showing increased activity during walking with the adaptive VE training paradigm compared to the control conditions. During the interactive VE walking task spectral power in frequency ranges 8-12, 15-20, and 23-40 Hz was significantly (p ? 0.05) decreased. This power decrease is interpreted as a correlate of an active cortical area. Furthermore activity in the premotor cortex revealed gait cycle related modulations significantly different (p ? 0.05) from baseline in the frequency range 23-40 Hz during walking. These modulations were significantly (p ? 0.05) reduced depending on gait cycle phases in the interactive VE walking task compared to the control conditions. We demonstrate that premotor and parietal areas show increased activity during walking with the adaptive VE training paradigm, when compared to walking with mirror- and movement unrelated feedback. Previous research has related a premotor-parietal network to motor planning and motor intention. We argue that movement related interactive feedback enhances motor planning and motor intention. We hypothesize that this might improve gait recovery during rehabilitation.","neurorehabilitation; robotic gait training; locomotion; motor planning; electroencephalography; interactive feedback; gait adaptation","en","journal article","Frontiers","","","","","","","","Mechanical, Maritime and Materials Engineering","Biomechanical Engineering","","","",""
"uuid:889dde98-8649-451e-8651-06d4bab97ca2","http://resolver.tudelft.nl/uuid:889dde98-8649-451e-8651-06d4bab97ca2","Increased physical activity severely induces osteoarthritic changes in knee joints with papain induced sulfate-glycosaminoglycan depleted cartilage","Siebelt, M.; Groen, H.C.; Koelewijn, S.J.; De Blois, E.; Sandker, M.; Waarsing, J.H.; Müller, C.; Van Osch, G.J.V.M.; De Jong, M.; Weinans, H.H.","","2014","Introduction Articular cartilage needs sulfated-glycosaminoglycans (sGAGs) to withstand high pressures while mechanically loaded. Chondrocyte sGAG synthesis is regulated by exposure to compressive forces. Moderate physical exercise is known to improve cartilage sGAG content and might protect against osteoarthritis (OA). This study investigated whether rat knee joints with sGAG depleted articular cartilage through papain injections might benefit from moderate exercise, or whether this increases the susceptibility for cartilage degeneration. Methods sGAGs were depleted from cartilage through intraarticular papain injections in the left knee joints of 40 Wistar rats; their contralateral joints served as healthy controls. Of the 40 rats included in the study, 20 rats remained sedentary, and the other 20 were subjected to a moderately intense running protocol. Animals were longitudinally monitored for 12 weeks with in vivo micro-computed tomography (?CT) to measure subchondral bone changes and single-photon emission computed tomography (SPECT)/CT to determine synovial macrophage activation. Articular cartilage was analyzed at 6 and 12 weeks with ex vivo contrast-enhanced ?CT and histology to measure sGAG content and cartilage thickness. Results All outcome measures were unaffected by moderate exercise in healthy control joints of running animals compared with healthy control joints of sedentary animals. Papain injections in sedentary animals resulted in severe sGAG-depleted cartilage, slight loss of subchondral cortical bone, increased macrophage activation, and osteophyte formation. In running animals, papain-induced sGAG-depleted cartilage showed increased cartilage matrix degradation, sclerotic bone formation, increased macrophage activation, and more osteophyte formation. Conclusions Moderate exercise enhanced OA progression in papain-injected joints and did not protect against development of the disease. This was not restricted to more-extensive cartilage damage, but also resulted in pronounced subchondral sclerosis, synovial macrophage activation, and osteophyte formation.","OA-Fund TU Delft","en","journal article","BioMed Central","","","","","","","","Mechanical, Maritime and Materials Engineering","Biomechanical Engineering","","","",""
"uuid:c1c0ceb5-5853-4ba2-9ab1-76ea19e015e6","http://resolver.tudelft.nl/uuid:c1c0ceb5-5853-4ba2-9ab1-76ea19e015e6","Electrical vestibular stimuli to enhance vestibulo-motor output and improve subject comfort","Forbes, P.A.; Dakin, C.J.; Geers, A.M.; Vlaar, M.P.; Happee, R.; Siegmund, G.P.; Schouten, A.C.; Blouin, J.S.","","2014","Electrical vestibular stimulation is often used to assess vestibulo-motor and postural responses in both clinical and research settings. Stochastic vestibular stimulation (SVS) is a recently established technique with many advantages over its square-wave counterpart; however, the evoked muscle responses remain relatively small. Although the vestibular-evoked responses can be enhanced by increasing the stimulus amplitude, subjects often perceive these higher intensity electrical stimuli as noxious or painful. Here, we developed multisine vestibular stimulation (MVS) signals that include precise frequency contributions to increase signal-to-noise ratios (SNR) of stimulus-evoked muscle and motor responses. Subjects were exposed to three different MVS stimuli to establish that: 1) MVS signals evoke equivalent vestibulo-motor responses compared to SVS while improving subject comfort and reducing experimentation time, 2) stimulus-evoked vestibulo-motor responses are reliably estimated as a linear system and 3) specific components of the cumulant density time domain vestibulo-motor responses can be targeted by controlling the frequency content of the input stimulus. Our results revealed that in comparison to SVS, MVS signals increased the SNR 3-6 times, reduced the minimum experimentation time by 85% and improved subjective measures of comfort by 20-80%. Vestibulo-motor responses measured using both EMG and force were not substantially affected by nonlinear distortions. In addition, by limiting the contribution of high frequencies within the MVS input stimulus, the magnitude of the medium latency time domain motor output response was increased by 58%. These results demonstrate that MVS stimuli can be designed to target and enhance vestibulo-motor output responses while simultaneously improving subject comfort, which should prove beneficial for both research and clinical applications.","","en","journal article","Public Library of Science","","","","","","","","Mechanical, Maritime and Materials Engineering","Biomechanical Engineering","","","",""
"uuid:a8c2e360-f686-4ec5-af6d-75bf33f6245e","http://resolver.tudelft.nl/uuid:a8c2e360-f686-4ec5-af6d-75bf33f6245e","Design and evaluation of two different finger concepts for body-powered prosthetic hand","Smit, G.; Plettenburg, D.H.; Van der Helm, F.C.","","2014","The goal of this study was to find an efficient method of energy transmission for application in an anthropomorphic underactuated body-powered (BP) prosthetic hand. A pulley-cable finger and a hydraulic cylinder finger were designed and tested to compare the pulley-cable transmission principle with the hydraulic cylinder transmission principle. Both fingers had identical dimensions and a low mass. The only thing that differed between the fingers was the transmission principle. The input energy was measured for a number of tasks. The pulley-cable finger required more input energy than the hydraulic cylinder finger to perform the tasks. This was especially the case in tasks that required high pinch forces. The hydraulic cylinder transmission is therefore the more efficient transmission for application in BP prosthetic fingers.","articulating finger; body-powered; efficiency; hydraulic cylinder finger; hysteresis; prosthetic design; prosthetics; pulley-cable finger; qualitative testing; upper limb","en","journal article","Rehabilitation Research and Development Service","","","","","","","","Mechanical, Maritime and Materials Engineering","Biomechanical Engineering","","","",""
"uuid:6a110e97-a39e-4073-9974-4d2a1edd3cba","http://resolver.tudelft.nl/uuid:6a110e97-a39e-4073-9974-4d2a1edd3cba","Preliminary results from a field experiment on e-bike safety: Speed choice and mental workload for middle-aged and elderly cyclists","Twisk, D.A.M.; Boele, M.J.; Vlakveld, W.P.; Christoph, M.; Sikkema, R.; Remij, R.; Schwab, A.L.","","2013","To study the safety of e-bikes for the elderly, an experimental field study was conducted, using instrumented bicycles and comparing two age groups: older cyclists, n= 29, mean age = 70, SD = 4.2 and middle-aged cyclists, n = 29, mean age = 38, SD = 4.3. All were regular cyclists. They rode a fixed route with a length of about 3.5 km: once on an instrumented e-bike and once on an instrumented conventional bike, in counterbalanced order. Measures were taken on heart rate, mental workload, and geographical position (GPS), balance and riding speed. This paper only reports a subset of the results namely the main findings on speed and mental workload. As predicted, both age groups rode significantly faster on an e-bike than on a conventional bike. This difference was greatest on the straight sections, but only small in bends. In all situa-tions (turn to the left, and straight) older cyclists rode slower than middle-aged bicyclists, both on an e-bike and a conventional bicycle. In fact, the speed of elderly on e-bikes did not differ from that of middle-aged participants on conventional bikes. As expected, mental workload was higher in complex situations (left turns), than in simple ones (straight sections). Mental workload in complex situations were even higher for the elderly. But no difference was found for bicycle type. These results suggest that cyclists slow down their speeds in complex traffic situations, and that this pattern does not differ between conventional or e-bikes, nor between the two age groups. It is still too early to draw conclusions about the safety of e-bikes. Addi-tional analyses will be carried out to assess the robustness of these conclusions.","e-bike; older cyclists; field study; instrumented bicycles; safety; speed; mental workload","en","conference paper","ICSC","","","","","","","","Mechanical, Maritime and Materials Engineering","Biomechanical Engineering","","","",""
"uuid:19afe386-8b4f-4240-bd8b-47bd6994aa12","http://resolver.tudelft.nl/uuid:19afe386-8b4f-4240-bd8b-47bd6994aa12","Künstliches feedback für oberschenkelamputierte; theoretische Analyse - Artificial feedback for transfemoral amputees: Theoretical analysis","Pagel, A.K.; Oes, J.; Pfeifer, S.; Riener, R.; Vallery, H.","","2013","Dieser Beitrag untersucht auf Basis von Modellen der menschlichen Wahrnehmung den Einfluss künstlichen sensorischen Feedbacks auf posturale Kontrolle und Gangsymmetrie von Oberschenkelamputierten. In der Standphase wird ein vereinfachtes, statisches neuromechanisches Modell verwendet, in der Schwungphase ein Erweitertes Kalman-Filter, das dynamische Effekte berücksichtigt. Die Simulation lässt den Schluss zu, dass Rückmeldung des Fußdruckpunktes während der Standphase die Wahrnehmung verbessern könnte, künstliches Feedback während der Schwungphase jedoch nicht von Vorteil ist. Eine klinische Fallstudie wäre nötig, um die in der Simulation beobachteten Effekte sensorischen Feedbacks in der praktischen Anwendung mit Amputierten zu uberprufen","Erweitertes Kalman-Filter; Beobachtermodell; sensorische Augmentation; posturale Kontrolle","de","journal article","Oldenbourg Verlag","","","","","","","","Mechanical, Maritime and Materials Engineering","Biomechanical Engineering","","","",""
"uuid:109ef8ac-8b2f-421b-bf3b-cab59c155194","http://resolver.tudelft.nl/uuid:109ef8ac-8b2f-421b-bf3b-cab59c155194","Force sensing in surgical sutures","Horeman, T.; Meijer, E.J.; Harlaar, J.J.; Lange, J.F.; Van den Dobbelsteen, J.J.; Dankelman, J.","","2013","The tension in a suture is an important factor in the process of wound healing. If there is too much tension in the suture, the blood flow is restricted and necrosis can occur. If the tension is too low, the incision opens up and cannot heal properly. The purpose of this paper is to describe the design and evaluation of the Stitch Force (SF) sensor and the Hook-In Force (HIF) sensor. These sensors were developed to measure the force on a tensioned suture inside a closed incision and to measure the pulling force used to close the incision. The accuracy of both sensors is high enough to determine the relation between the force in the thread of a stitch and the pulling force applied on the suture by the physician. In a pilot study, a continuous suture of 7 stitches was applied on the fascia of the abdominal wall of multiple pigs to study this relationship. The results show that the max force in the thread of the second stitch drops from 3 (SD 1.2) to 1 (SD 0.3) newton after the 4(th) stitch was placed. During placement of the 5(th), 6(th) and 7(th) stitch, the force in the 2(nd) stitch was not influenced anymore. This study indicates that in a continuous suture the force in the thread remains constant up to more than 3 stiches away from the pulled loose end of the suture. When a force feedback tool is developed specially for suturing in surgery on patients, the proposed sensors can be used to determine safety threshold for different types of tissue and sutures.","","en","journal article","Public Library of Science","","","","","","","","Mechanical, Maritime and Materials Engineering","Biomechanical Engineering","","","",""
"uuid:cc9ea327-f780-43dd-96cb-f00ad5ffc8bb","http://resolver.tudelft.nl/uuid:cc9ea327-f780-43dd-96cb-f00ad5ffc8bb","Grip op loslating","Valstar, E.R.","","2013","","Intreerede","en","public lecture","Universiteit Leiden/TU Delft","","","","","","","","Mechanical, Maritime and Materials Engineering","Biomechanical Engineering","","","",""
"uuid:c2dac8ee-0529-49ae-8374-2d49efd0ba90","http://resolver.tudelft.nl/uuid:c2dac8ee-0529-49ae-8374-2d49efd0ba90","Needle-Tissue Interaction by Experiment","Van Gerwen, D.J.","Dankelman, J. (promotor); Van den Dobbelsteen, J.J. (promotor)","2013","Medical needles may not be very popular among patients, but they are exceptionally versatile instruments that have found their way into virtually every clinical intervention imaginable. However, despite their versatility, needles can be very difficult to use, and there is much room for improvement. Improvements can be realized by optimization of needle geometry, by the development of training facilities for clinicians, imaging modalities and needle-based sensors, by development of needle-steering mechanisms and path planning methods, or even by fully automating the needle insertion process. These approaches all rely on a proper understanding of the mechanical interaction between needle and soft-tissue. Ideally, insight into needle-tissue interaction mechanics should follow from the development and refinement of theoretical models based on experimental observation. The development of theoretical models has received a lot of attention in the literature, but our inability to collect useful and reliable experimental data remains an important obstacle. For this reason, the present thesis deals with the experimental study of needle-tissue interaction. The goal of the thesis is to provide insight into needle-tissue interaction mechanics based on experimental observation. To achieve this goal we measure the axial component of the external force acting on the needle during interaction with tissue, and we observe the position of the needle relative to the surrounding tissue. The first part of the thesis provides a basis for experimentation. This includes a survey of literature related to needle-tissue interaction force measurements. The intention of this survey is to gather existing experimental evidence regarding the influence of different factors, such as needle type, tissue type, and insertion speed, on the axial force. Based on this survey, a data model is constructed that describes the interrelations between the different aspects of needle-tissue interaction experiments. This data model enables the detailed encoding of experimental equipment, conditions, design, and results, and can be used as the blueprint for a database for experimental needle-tissue interaction data. The second part of the thesis presents two examples of relatively well-controlled experiments involving artificial specimens. These examples illustrate what happens at the tip of a needle during puncture of a membrane. The first experiment involves the use of high speed video to investigate the relation between axial force and needle tip geometry. The second experiment presents a follow-up study that investigates the influence of needle coating (lubrication) on the axial force during membrane puncture. The last part of the thesis presents two examples of experiments involving biological tissue. The first example is an exploratory study aimed at the characterization of forces during needle insertion into the kidney of a human cadaver. This is done with the help of synchronized ultrasound visualization. The second example is concerned with needle insertion into isolated porcine kidneys, intended to achieve a more detailed characterization of forces for different anatomical structures inside the kidney. This experiment uses synchronized ultrasound visualization with the ultrasound probe moving along with the needle. The thesis contributes to the field of needle-tissue interaction mechanics by providing an overview of available knowledge concerning needle-tissue interaction forces, and by providing a framework for structuring and expanding this knowledge. The thesis provides some insight by illustrating how needle reuse, needle coating, and specimen boundary conditions influence specific force metrics in artificial specimens. In addition, the thesis provides a first impression of the variability encountered during needle insertion into human cadaverous kidneys, and it provides a multivariate stochastic model of membrane puncture forces in porcine kidneys that can be used to simulate puncture events. However, the most important contribution consists of a set of tools for gathering, analyzing, and disseminating experimental needle-tissue interaction data.","","en","doctoral thesis","","","","","","","","","Mechanical, Maritime and Materials Engineering","BioMechanical Engineering","","","",""
"uuid:893379c9-0e8c-43d8-9f57-06149a778183","http://resolver.tudelft.nl/uuid:893379c9-0e8c-43d8-9f57-06149a778183","Exploiting the possibilities of simulators for driver training","De Groot, S.","Wieringa, P.A. (promotor); Mulder, M. (promotor); de Winter, J.C.F. (copromotor)","2013","Training in a simulator offers potential advantages compared to training in a non-simulated environment. Generally it is cheaper, safer, there is more control over the environment, and data collection is less complicated. These potential advantages give simulators the possibility to offer effective training. This thesis is divided into three parts, aimed at realizing cost-effective driver training and driver assessment using simulators. The first part focuses on driver performance in fixed-base simulators, the second part focuses on learning to drive in a simulator and the third part evaluates a newly developed simulator for the training and assessment of racecar drivers. Valid and reliable performance measures are required to analyze driver performance. Chapter 1 evaluates a large amount of measures for the task of braking and then stopping at a stop-sign, which is a common task for research into driver performance. A computer simulation was executed and also empirical data was used to study the performance measures. The main conclusions were that reliable and valid measures for the braking task are: speed and distance to the stop-sign at the start of braking, the stopping position with respect to the stop-sign, and a measure which indicates whether or not the deceleration was constant while the vehicle was slowed down. Chapter 2 tests eight low-cost non-vestibular acceleration and speed feedback systems: a tensioning seatbelt, a vibrating steering wheel, a motion seat, screeching tire sound, auditory beeps, a vibrating seat-pan in two configurations, and a pressure seat. For five systems, which provide longitudinal acceleration feedback, the measures of Chapter 1 were used to analyze the effect of the feedback systems on driver performance during the braking task. Chapter 2 concludes that vehicle acceleration cues can be fed back to the driver without a motion platform. The system which made the largest gain in making driver performance more realistic was the tensioning seatbelt system. Chapter 3 investigates the modality with which instructions are presented in the simulator. Generally, instructions in simulators are presented verbally. The auditory modality is a logical choice because car driving can be seen as a predominantly visual task. However, beginner drivers receive a lot of verbal instructions in a limited amount of time, and therefore it is interesting to investigate the effects of presenting the route instructions in a different modality. The experiment in the driving simulator showed that both visual and visual-auditory route-instructions resulted in less turning errors than the auditory route-instructions. The visual-auditory instructions also reduced indicator reaction times. The visual-auditory instructions were preferred by people who drove faster, and people who had low self-reported driving skill. Most people preferred the visual instructions over the auditory instructions. This experiment showed that even though the visual instructions interfere with the predominantly visual driving task according to the ‘multiple research theory’ (Wickens, 1999), they did result in better driving performance. The second part of this thesis focuses on learning to drive in a simulator. First, the didactical properties of four commercially available driving simulators are analyzed. A survey shows that the intelligent tutoring systems of current driver training simulators are mostly imitating the human instructor and that the “first principles of instruction” (Merrill, 2002a) are not implemented to their full potential. Hence, there is ample room for improvement of the didactical properties by fully exploiting the many visualization, demonstration, and performance-assessment opportunities provided by modern driving simulators. Furthermore, objective performance ratings of students can be used to provide accurate and consistent feedback-on-performance, something that is not possible in real cars, but which is often essential for effective skills training. It is recommended to use empirical experimentations to improve the instructional design of simulator-based driver training for specific learning outcomes and validate the use of the first principles of instruction to facilitate learning. The following three experiments investigate whether potential advantages which are offered by simulators can be used to teach driving skills to learner drivers. Some psychological principles concerning augmented feedback are studied and used to create a new learning environment. In the first experiment, seat vibrations which reacted to the lateral position in the lane were used to teach inexperienced drivers to drive in the middle of the right lane. There were four experimental groups: (a) on-target, receiving seat vibrations when the center of the car was within 0.5 m of the lane center; (b) off-target, receiving seat vibrations when the center of the car was more than 0.5 m away from the lane center; (c) control, receiving no vibrations; and (d) realistic, receiving seat vibrations depending on engine speed. During retention, all groups were provided with the realistic vibrations. Every participant drove five 8 minute sessions: three training sessions, one retention test directly after practice, and one retention test the following day. During practice, on-target and off-target groups had better lane-keeping performance than the nonaugmented groups, but this difference diminished in the retention phase. Furthermore, during late practice and retention, the off-target group outperformed the on-target group. The conclusion of this experiment is that off-target feedback is superior to on-target feedback for learning the lane-keeping task. During the following two experiments, the difficulty of the training was varied by changing the friction coefficient of the tire on the road. The first experiment deals with a normal road-car, while the second experiment deals with a racing car. Previous research in motor learning has shown that degrading the task conditions during practice can enhance long-term retention performance. Just like in the previous experiment, the driving task was keeping the car in the center of the right lane. The inexperienced drivers were divided into three groups: low grip (LG), normal grip (NG), and high grip (HG). All groups drove six sessions: four practice sessions, an immediate retention session, and a delayed retention session the following day. The two retention sessions were driven with normal-grip tires. The results show that LG drove with lower speed than NG during practice and retention. Transferring from the last practice session to the immediate retention session, LG’s workload decreased, as measured with a secondary task, whereas HG’s workload increased. This experiment also showed that it is possible to influence self-reported confidence level, which may have potential implications for the way drivers are trained. In the second experiment in which the tire-road friction coefficient is varied during training, we are not investigating normal car driving, but racecar driving. Now the goal is not to make people drive slower, but faster instead. Three groups of inexperienced racecar drivers were trained and tested on the same simple racetrack: low grip (LG), normal grip (NG), and high grip (HG). Just like in the previous experiment, LG drove slower than the other groups during training and the first retention session. The second retention session was driven in a different car than the training and the first retention session (Formula 1 car instead of a Formula 3 car), and in this session no differences in lap time were found between the groups. LG reported a higher confidence and lower frustration than NG and HG after each of the two retention sessions. In conclusion, practicing with low grip, as compared to practicing with normal or high grip, resulted in increased confidence but slower lap times. The third part of this thesis investigates the validity and controllability of a racing simulator. A modest validation study was performed by comparing the fastest lap times of 13 racing drivers during training sessions in the simulator to the fastest lap times these same drivers did on the same track in the real world. A correlation between the lap times was found, which indicates that the simulator has some degree of predictive value for performance in the real world. A (racing) simulator can be used for controlled experiments which are difficult to perform in reality. In different racecars, we have found large differences in gain and stiffness of the brake pedal. We assume that there exists an optimal stiffness and gain of the brake pedal for racecar drivers, but this is hard to investigate in reality. The expected performance differences are small, the time it takes to adapt the brake system is lengthy, and the environmental factors, such as grip of the tires and track, vary all the time. In two independent experiments the effect of the brake pedal stiffness on lap times is investigated. The expectations were that a softer brake pedal would be better in long brake zones, and that a stiff pedal would result in faster control inputs by the driver. The conclusions of the two experiments are that racing car drivers can deal with a large range of brake pedal stiffness, that a stiff pedal results in faster control inputs, and that the simulator is a useful tool for experiments concerning the human-machine interface which are difficult to perform in reality. To get a more detailed idea about which properties of the brake pedal are important for brake force control of racecar drivers, the gain of the brake pedal is investigated further in Chapter 9. During the last experiment participants did not drive on a virtual track, but performed a one dimensional control task. The test setup was a formula racing car cockpit fitted with an isometric brake pedal, which means that the pedal does not deflect under load and the pedal force determines the output. Four control-display gains, varying from very low to very high, were compared with two target functions; a step function and a multisine function. The control-display gain had only minor effects on root mean-squared error between output value and target value but it had large effects on build-up speed, overshoot, within-participants variability, and self-reported physical load. The results confirm the hypothesis that choosing an optimum gain involves balancing stability against physical effort.","driving simulator; driver performance; driver training; racecar simulator","en","doctoral thesis","","","","","","","","","Mechanical, Maritime and Materials Engineering","BioMechanical Engineering","","","",""
"uuid:17fde810-f092-4773-9c07-af6dfb33f822","http://resolver.tudelft.nl/uuid:17fde810-f092-4773-9c07-af6dfb33f822","Assessment of Laparoscopic Skills Based on Force and Motion Parameters","Horeman, T.; Dankelman, J.; Jansen, F.W.; Van den Dobbelsteen, J.J.","","2013","Box trainers equipped with sensors may help in acquiring objective information about a trainee's performance while performing training tasks with real instruments. The main aim of this study is to investigate the added value of force parameters with respect to commonly used motion and time parameters such as path length, motion volume, and task time. Two new dynamic bimanual positioning tasks were developed that not only requiring adequate motion control but also appropriate force control successful completion. Force and motion data for these tasks were studied for three groups of participants with different experience levels in laparoscopy (i.e., 11 novices, 19 intermediates, and 12 experts). In total, 10 of the 13 parameters showed a significant difference between groups. When the data from the significant motion, time, and force parameters are used for classification, it is possible to identify the skills level of the participants with 100% accuracy. Furthermore, the force parameters of many individuals in the intermediate group exceeded the maximum values in the novice and expert group. The relatively high forces used by the intermediates argue for the inclusion of training and assessment of force application during tissue handling in future laparoscopic skills training programs.","","en","journal article","IEEE","","","","","","","","Mechanical, Maritime and Materials Engineering","Biomechanical Engineering","","","",""
"uuid:0e3f6f5e-edea-476c-b3a3-cf89ac926356","http://resolver.tudelft.nl/uuid:0e3f6f5e-edea-476c-b3a3-cf89ac926356","Delayed gadolinium-enhanced MRI of cartilage (dGEMRIC) shows no change in cartilage structural composition after viscosupplementation in patients with early-stage knee osteoarthritis","Van Tiel, J.; Reijman, M.; Bos, P.K.; Hermans, J.; Van Buul, G.M.; Bron, E.E.; Klein, S.; Verhaar, J.A.N.; Krestin, G.P.; Bierma-Zeinstra, S.M.A.; Weinans, H.; Kotek, G.; Oei, E.H.G.","","2013","","","en","journal article","Public Library of Science PLOS","","","","","","","","Mechanical, Maritime and Materials Engineering","Biomechanical Engineering","","","",""
"uuid:f2523458-cb32-4c69-963e-da7b1e89ddd5","http://resolver.tudelft.nl/uuid:f2523458-cb32-4c69-963e-da7b1e89ddd5","Silver-based antibacterial surfaces for bone implants","Necula, B.S.","Katgerman, L. (promotor); Apachitei, I. (promotor)","2013","Total hip arthroplasty (THA) is the most effective and safest method for treating severe degenerative, post-traumatic and other diseases of the joints. With an aging population that is increasingly active, the use of biomedical implants will continue to rise. It is estimated that more than 1,000,000 THAs are performed each year globally. Consequently, the threat posed by implant associated infections (IAI) will affect a large percentage of this populace. IAI are serious complications, caused by infectious bacteria that colonize the implant surface, rapidly proliferate and secrete a matrix of polysaccharides known as a biofilm. Once formed, the biofilm is extremely resistant to host-defense mechanisms or antibiotics, and ultimately will lead to implant loosening and revision surgery with devastating effects on the patient. Currently, no solutions are clinically available to prevent IAI on cementless implants. Therefore, intense research efforts are focused on development of antibacterial surfaces that will kill any adherent bacteria and thus, prevent the bacteria from generating a biofilm. The aim of this PhD thesis was to develop a novel antibacterial surface for cementless implants. The research was focused on the synthesis, physicochemical characterization and biological evaluation of an Ag-based antibacterial surface on the Ti6Al7Nb biomedical alloy. Using the plasma electrolytic oxidation (PEO) process, various concentrations of Ag nanoparticles were incorporated into a microporous TiO2 layer grown on the Ti6Al7Nb alloy to render its surface antibacterial. Following synthesis, thorough characterization of the novel oxide layers with regard to Ag nanoparticles distribution, chemical and phase composition, surface roughness, coating porosity, pore density, pore size distribution, and surface free energy was performed. Furthermore, their antibacterial effectiveness and toxicity to human bone cells were assessed in vitro. Finally, a feasibility study assessing whether Ag-based antibacterial surfaces can be applied on commercially available bone implants such as plasma sprayed titanium hip components was also performed. The thesis comprises six chapters starting with an introduction in Chapter 1 that provides the background, as well as the state of the art information on implant associated infections and current biomaterial-based strategies to prevent this problem. Furthermore, a description of the PEO process, as a possible process for generating antibacterial surfaces for bone implants, and the motivation of using Ag nanoparticles as antibacterial agent are also presented. Finally, the aim of the research and the thesis outline are defined. The experimental conditions and the required equipment for the synthesis and characterization of novel Ag-based antibacterial layers on the Ti6Al7Nb alloy are presented in Chapter 2. In addition, the main results on surface characterization are reported in this chapter. During the PEO process, the Ti6Al7Nb disk was immersed in an aqueous calcium acetate/calcium glycerophosphate-based electrolyte bearing dispersed Ag nanoparticles and connected to a high-voltage power supply. A stainless steel plate served as the counter-electrode. When the applied voltage exceeded a certain critical value, dielectric breakdown of the anodic barrier TiO2 layer occurred on the surface of the Ti6Al7Nb alloy thereby resulting in a modified surface. The morphological investigations by scanning electron microscopy (SEM) revealed the presence of a porous TiO2 layer with well-separated round/elongated pores, ranging from a few nanometers up to 10 ?m in size. The presence of Ag nanoparticles in the porous TiO2 layers was confirmed by high-resolution SEM coupled with the back-scattering and energy dispersive X-ray spectroscopy (EDX) detectors. Except the presence of different concentrations of Ag nanoparticles in the TiO2 layers, the other surface characteristics such as chemical and phase composition, surface roughness, porosity, pore density, pore size distribution, mean pore size and surface free energy remained unchanged as compared with the Ag-free TiO2 layers. Therefore, the effect of Ag nanoparticles embedded in the TiO2 coatings in various concentrations, on the bacteria killing ability and viability of the bone cells could be evaluated without the interference of the other factors. The challenge addressed in Chapter 3 was the investigation of the mechanism of Ag nanoparticles incorporation in the TiO2 layers during the PEO process. How and where are the Ag nanoparticles incorporated in the porous TiO2 layer were the main research questions addressed. Thus, the Ag-bearing TiO2 layers were grown at different oxidation times i.e., 10, 30, 60, 90, 120, 180, 240 and 300 seconds and thoroughly studied in plan view and cross-section using state of the art imaging techniques such as high-resolution transmission electron microscopy and SEM coupled with EDX analyses for chemical composition. It was observed that Ag nanoparticles could be incorporated in the growing TiO2 layers starting with very initial stages of oxidation (i.e., 10 seconds) with further incorporation as the PEO process was continued for longer durations. Thorough investigation of the coatings for evidence of particles revealed three different locations of Ag within the oxide: (i) fused on the surface of the oxide (with some particles protruding from the layer), (ii) fused into the pore walls (both open and closed pores), and (iii) embedded across the thickness of the dense oxide layer (starting just above the barrier-like layer). The morphology of the Ag nanoparticles found in the layers seemed to match that of the nanoparticles used in the electrolyte. As far as the mechanism of Ag nanoparticles incorporation is concern, four main steps were proposed: (i) transport of Ag nanoparticles at the TiO2/electrolyte and Ti6Al7Nb/TiO2 interfaces by mechanical agitation and electrophoretic mobility through short-circuit channels, open pores and cracks; (ii) attachment/adsorption of Ag nanoparticles to the sites of coating growth, where under the local heating generated by the sparking events the layer is relatively soft; (iii) fusion of Ag nanoparticles into the soft oxide once the sparks extinguish and the site is cooled by the electrolyte; (iv) encroachment of the already embedded Ag nanoparticles during the coating growth as the new coating formed close to the Ti6Al7Nb/TiO2 interface might be extruded through the breakdown channels causing the molten material to fill the previously created pores and cracks moving along the Ag nanoparticles that were fused in a previous discharge event. The particular focus of Chapter 4 was to perform in vitro tests to evaluate the antibacterial activity of the TiO2 layers bearing different concentrations of Ag nanoparticles. The main challenge was to find and use the proper antibacterial assays to investigate the antibacterial activity of solid surfaces. Considering that the current available assays do not reflect the precise conditions under which the bacteria will come in close contact with a potentially bactericidal surface, new assays for surface antibacterial activity as well as leachable antibacterial activity were proposed and tested. The pathogen used for the tests was methicillin-resistant Staphylococcus aureus (MRSA), one of the most prevalent and virulent microorganism responsible for implant associated infections. Surface antibacterial activity, tested by a direct contact assay, revealed 98% and 99.75% reduction in bacteria colony forming units (CFU) for 0.3Ag and 3.0Ag surfaces, respectively. In contrast, the untreated Ti6Al7Nb and Ag-free (0Ag) surfaces showed a 1000-fold increase in bacterial CFU. Testing of leachable antibacterial activity revealed a well-defined inhibition zone around the Ag-bearing samples due to the release of Ag ions after 24 hours of incubation with MRSA. Quantification of Ag ions release and determination of total Ag content in the layers, together with the antibacterial tests, led to the conclusion that both Ag nanoparticles per se as well as Ag ions release contributed to the bactericidal activity of the TiO2 surfaces. The next step in the development of antibacterial surfaces for bone implants was to check their toxicity to human cells. Whether or not the Ag-bearing TiO2 layers were toxic to osteoblast cells was described in Chapter 5. For this, a Simian Virus 40 (SV40)-immortalized human fetal osteoblast (SV-HFO) cell line was used. Cell viability, cell morphology and spreading, and the actin cytoskeletal organization and nucleus were studied in vitro using the Alamar Blue assay, SEM and fluorescence microscopy, respectively on TiO2 surfaces bearing different concentrations of Ag nanoparticles (i.e., 0.3Ag, 0.8Ag, 1.6Ag and 3.0Ag). The results showed that the viability of osteoblast cells was strongly dependent on the concentration of Ag nanoparticles in the layers. The 3.0Ag surfaces, because of the higher concentration of Ag nanoparticles in the TiO2, were found to be toxic to osteoblast cells. In contrast, the osteoblasts viability on the 0.3Ag surfaces, assessed by Alamar Blue, SEM and fluorescence microscopy, was not inhibited after 2, 5 and 7 days of culture. The testing of the TiO2 surfaces bearing intermediate concentrations of Ag nanoparticles appeared to follow the same trend. A significantly lower number of bone cells survived on the 0.8Ag and 1.6Ag samples after 2 days of culture. Chapter 6 covers a feasibility study to see whether the PEO process, used to render the surface of a Ti6Al7Nb alloy antibacterial, can be applied on commercially available cementless bone implants such as plasma-sprayed titanium hip components. Such implants have very complex geometries and the main challenge was to create an Ag-bearing antibacterial TiO2 layer that covers accurately the topography of such implants. A titanium plasma-sprayed acetabular cup was chosen as a substrate and PEO was performed using the Ag-bearing calcium acetate/calcium glycerophosphate electrolyte. The superimposed layers were then characterized with respect to surface morphology and chemistry using SEM and EDX. The surface morphology results showed the successful creation of the TiO2 layer, with its fine network of interconnected, round or elongated pores, superimposed on the macro-porous structure of the plasma-sprayed coating. The PEO antibacterial layer followed accurately the surface topography of the plasma-sprayed sample. Furthermore, the Ag nanoparticles were found to be present on top as well as in the porous structure of TiO2 layer. The work performed in this thesis leads to the final conclusions that (i) TiO2 layers bearing Ag nanoparticles can be produced on titanium biomedical alloys and on titanium-based bone implants using the plasma electrolytic oxidation process and (ii) the resultant novel layers can be a suitable engineering solution for the clinical problem of implant associated infections of cementless bone implants.","antibacterial coatings; bone implants; titanium dioxide; porous coatings; silver nanoparticles; in vitro evaluation; biomaterials; biomedical","en","doctoral thesis","","","","","","","","2014-11-06","Mechanical, Maritime and Materials Engineering","BioMechanical Engineering","","","",""
"uuid:68c4665d-7a41-4b94-84d5-6ba8a08fc219","http://resolver.tudelft.nl/uuid:68c4665d-7a41-4b94-84d5-6ba8a08fc219","The Improvement of Strabismus Surgery: The Role of the Suspension of the Human Eye","Schutte, S.","Van der Helm, F.C.T. (promotor); Simonsz, H.J. (promotor)","2013","","","en","doctoral thesis","","","","","","","","","Mechanical, Maritime and Materials Engineering","BioMechanical Engineering","","","",""
"uuid:e800b06d-afe3-4f0a-b1d8-224d600b3e1c","http://resolver.tudelft.nl/uuid:e800b06d-afe3-4f0a-b1d8-224d600b3e1c","The evolution of biomaterials research","Zadpoor, A.A.","","2013","Amir A. Zadpoor discusses how the field of biomaterials has changed since the turn of the century.","","en","journal article","Elsevier","","","","","","","","Mechanical, Maritime and Materials Engineering","Biomechanical Engineering","","","",""
"uuid:b7ecabb3-3292-4ae7-9a7c-402c2c0e9f6d","http://resolver.tudelft.nl/uuid:b7ecabb3-3292-4ae7-9a7c-402c2c0e9f6d","Obstacle avoidance, visual detection performance, and eye-scanning behavior of glaucoma patients in a driving simulator: A preliminary study","Prado Vega, R.; Van Leeuwen, P.M.; Rendon Velez, E.; Lemij, H.G.; De Winter, J.C.","","2013","The objective of this study was to evaluate differences in driving performance, visual detection performance, and eye-scanning behavior between glaucoma patients and control participants without glaucoma. Glaucoma patients (n = 23) and control participants (n = 12) completed four 5-min driving sessions in a simulator. The participants were instructed to maintain the car in the right lane of a two-lane highway while their speed was automatically maintained at 100 km/h. Additional tasks per session were: Session 1: none, Session 2: verbalization of projected letters, Session 3: avoidance of static obstacles, and Session 4: combined letter verbalization and avoidance of static obstacles. Eye-scanning behavior was recorded with an eye-tracker. Results showed no statistically significant differences between patients and control participants for lane keeping, obstacle avoidance, and eye-scanning behavior. Steering activity, number of missed letters, and letter reaction time were significantly higher for glaucoma patients than for control participants. In conclusion, glaucoma patients were able to avoid objects and maintain a nominal lane keeping performance, but applied more steering input than control participants, and were more likely than control participants to miss peripherally projected stimuli. The eye-tracking results suggest that glaucoma patients did not use extra visual search to compensate for their visual field loss. Limitations of the study, such as small sample size, are discussed.","attention; glaucoma; reaction time; vision; visual impairments; steering; sensory perception; eyes","en","journal article","Public Library of Science","","","","","","","","Mechanical, Maritime and Materials Engineering","Biomechanical Engineering","","","",""
"uuid:e3cfea0d-63f8-4f99-8373-734f07aa4491","http://resolver.tudelft.nl/uuid:e3cfea0d-63f8-4f99-8373-734f07aa4491","Control of thumb force using surface functional electrical stimulation and muscle load sharing","Westerveld, A.J.; Schouten, A.C.; Veltink, P.H.; Van der Kooij, H.","","2013","Background Stroke survivors often have difficulties in manipulating objects with their affected hand. Thumb control plays an important role in object manipulation. Surface functional electrical stimulation (FES) can assist movement. We aim to control the 2D thumb force by predicting the sum of individual muscle forces, described by a sigmoidal muscle recruitment curve and a single force direction. Methods Five able bodied subjects and five stroke subjects were strapped in a custom built setup. The forces perpendicular to the thumb in response to FES applied to three thumb muscles were measured. We evaluated the feasibility of using recruitment curve based force vector maps in predicting output forces. In addition, we developed a closed loop force controller. Load sharing between the three muscles was used to solve the redundancy problem having three actuators to control forces in two dimensions. The thumb force was controlled towards target forces of 0.5 N and 1.0 N in multiple directions within the individual’s thumb work space. Hereby, the possibilities to use these force vector maps and the load sharing approach in feed forward and feedback force control were explored. Results The force vector prediction of the obtained model had small RMS errors with respect to the actual measured force vectors (0.22±0.17 N for the healthy subjects; 0.17±0.13 N for the stroke subjects). The stroke subjects showed a limited work range due to limited force production of the individual muscles. Performance of feed forward control without feedback, was better in healthy subjects than in stroke subjects. However, when feedback control was added performances were similar between the two groups. Feedback force control lead, especially for the stroke subjects, to a reduction in stationary errors, which improved performance. Conclusions Thumb muscle responses to FES can be described by a single force direction and a sigmoidal recruitment curve. Force in desired direction can be generated through load sharing among redundant muscles. The force vector maps are subject specific and also suitable in feedforward and feedback control taking the individual’s available workspace into account. With feedback, more accurate control of muscle force can be achieved.","FES; load sharing; muscle recruitment; stroke; rehabilitation; force control; thumb","en","journal article","BioMed Central","","","","","","","","Mechanical, Maritime and Materials Engineering","Biomechanical Engineering","","","",""
"uuid:081e3d0e-173b-4a36-b8d6-c29c70eb7ae3","http://resolver.tudelft.nl/uuid:081e3d0e-173b-4a36-b8d6-c29c70eb7ae3","Statically Balanced Compliant Mechanisms: Theory and Synthesis","Gallego Sánchez, J.A.","Herder, J.L. (promotor); Van der Helm, F.C.T. (promotor)","2013","","energy-free systems; static balancing; continuous equilibrium; zero stiffness; compliant mechanisms; flexible mechanisms; topology optimization; design of mechanisms","en","doctoral thesis","","","","","","","","","Mechanical, Maritime and Materials Engineering","BioMechanical Engineering","","","",""
"uuid:3531544a-6750-4575-b8b8-6138a662472f","http://resolver.tudelft.nl/uuid:3531544a-6750-4575-b8b8-6138a662472f","Differences in abdominal force between conventional and single port laparoscopy","Sun, S.; Dankelman, J.; Horeman, T.","","2013","In laparoendoscopic single-site surgery (LESS), only one single incision is used to introduce all instruments into the abdominal cavity. The introduction of multi-channel single-port devices enabled insertion of laparoscopic instruments and laparoscope through one single entry point instead of multiple entry points in conventional laparoscopic surgery (CLS). From recent studies is known that the distance between instruments influences the force exerted on tissue during manipulation. To investigate whether this force difference can also be found on the abdominal wall, a two-dimensional force measurement mechanism was designed and incorporated in a standard trainer box. The sensors were used to measure the abdominal force exerted by either the standard trocar or the single-port device on the artificial skin that mimics the abdominal wall. A randomized crossover study consisted of 16 students and three experienced surgeons was conducted. The subjects were asked to perform a task with two different instrument configurations (CLS and LESS) in randomized order. The results showed that when performing a force-related task with LESS configuration, the maximum abdominal force was significantly higher compared with the conventional twoport CLS configuration.","","en","conference paper","","","","","","","","","Mechanical, Maritime and Materials Engineering","Biomechanical Engineering","","","",""
"uuid:9f979d35-00a7-4a97-8f23-913a2e1bacf8","http://resolver.tudelft.nl/uuid:9f979d35-00a7-4a97-8f23-913a2e1bacf8","Towards safer laparoscopic surgery: Training and assessment of surgical skills and equipment handling","Van Hove, P.D.","Dankelman, J. (promotor)","2013","The objective of this thesis is to improve laparoscopic surgical skills training and assessment with an emphasis on equipment-related safety and competence. A comparison was made between a hospital and a petrochemical company and showed that employees at the petrochemical company were trained and certified in equipment handling much more structurally than in the hospital. A national survey revealed that in Dutch hospitals training with operating equipment is more voluntary than obligatory and usually only takes place on introduction of a new device. As a possible solution to improve training with operating equipment, two online interactive simulation modules for operating equipment were developed to train both theoretical and practical competence. The research in this thesis showed that users who trained with the modules made only half the amount of the mistakes in operating the equipment compared to users who did not train with the modules.","surgery; laparoscopy; training; equipment; safety","en","doctoral thesis","","","","","","","","","Mechanical, Maritime and Materials Engineering","Biomechanical Engineering","","","",""
"uuid:d1300320-34e2-4603-b117-25184cf6fafe","http://resolver.tudelft.nl/uuid:d1300320-34e2-4603-b117-25184cf6fafe","Technical development of common anesthesiology techniques; Neuraxial anesthesia and laryngoscopy for endotracheal intubation","Lee, R.A.","Wieringa, P.A. (promotor); Van Zundert, A.A.J. (promotor)","2013","","","en","doctoral thesis","Wöhrmann Print Service","","","","","","","","Mechanical, Maritime and Materials Engineering","Biomechanical Engineering","","","",""
"uuid:6351529f-fd6e-4860-9d5c-29c5ef21c979","http://resolver.tudelft.nl/uuid:6351529f-fd6e-4860-9d5c-29c5ef21c979","Comparison of mechanical properties of silicone and PVC (polyvinylchloride) cosmetic gloves for articulating hand prostheses","Smit, G.; Plettenburg, D.H.","","2013","Current articulating electric and body-powered hands have a lower pinch force (15–34 N) than electric hands with stiff fingers (55–100 N). The cosmetic glove, which covers a hand prosthesis, negatively affects the mechanical efficiency of a prosthesis. The goal of this study is to mechanically compare polyvinylchloride (PVC) and silicone cosmetic gloves and quantify the stiffness of the finger joints, the required actuation energy, and the energy dissipation during joint articulation. Six cosmetic gloves, identical in size but made from different materials, were mechanically tested: three PVC and three silicone. The silicone gloves required less work and dissipated less energy during flexing. They also had a lower joint stiffness and required a lower maximum joint torque. Based on energy requirements, joint stiffness, and required joint torque, the tested silicone glove is most suitable for application on an articulating hand prosthesis.","body powered; efficiency; hysteresis; prosthetic design; prosthetic evaluation; prosthetic hand; cosmetic glove; silocone glove; pvc glove; handprothese; handprothesen; armprothese; armprothesen; kunstledematen; upper limb","en","journal article","U.S. Department of Veterans Affairs","","","","","","","","Mechanical, Maritime and Materials Engineering","BioMechanical Engineering","","","",""
"uuid:266266e8-a237-431f-8cb3-54643dba3d5d","http://resolver.tudelft.nl/uuid:266266e8-a237-431f-8cb3-54643dba3d5d","Sustained release of BMP-2 in bioprinted alginate for osteogenicity in mice and rats","Poldervaart, M.T.; Wang, H.; Van der Stok, J.; Weinans, H.H.; Leeuwenburgh, S.C.G.; Cumhur Öner, F.; Dhert, W.J.A.; Alblas, J.","","2013","The design of bioactive three-dimensional (3D) scaffolds is a major focus in bone tissue engineering. Incorporation of growth factors into bioprinted scaffolds offers many new possibilities regarding both biological and architectural properties of the scaffolds. This study investigates whether the sustained release of bone morphogenetic protein 2 (BMP-2) influences osteogenicity of tissue engineered bioprinted constructs. BMP-2 loaded on gelatin microparticles (GMPs) was used as a sustained release system, which was dispersed in hydrogel-based constructs and compared to direct inclusion of BMP-2 in alginate or control GMPs. The constructs were supplemented with goat multipotent stromal cells (gMSCs) and biphasic calcium phosphate to study osteogenic differentiation and bone formation respectively. BMP-2 release kinetics and bioactivity showed continuous release for three weeks coinciding with osteogenicity. Osteogenic differentiation and bone formation of bioprinted GMP containing constructs were investigated after subcutaneous implantation in mice or rats. BMP-2 significantly increased bone formation, which was not influenced by the release timing. We showed that 3D printing of controlled release particles is feasible and that the released BMP-2 directs osteogenic differentiation in vitro and in vivo.","","en","journal article","Public Library of Science PLOS","","","","","","","","Mechanical, Maritime and Materials Engineering","Biomechanical Engineering","","","",""
"uuid:fad5c41f-74b7-439f-9ffa-4f44b2843446","http://resolver.tudelft.nl/uuid:fad5c41f-74b7-439f-9ffa-4f44b2843446","Enhanced Bone Regeneration of Cortical Segmental Bone Defects Using Porous Titanium Scaffolds Incorporated with Colloidal Gelatin Gels for Timeand Dose-Controlled Delivery of Dual Growth Factors","Van der Stok, J.; Wang, H.; Yavari, S.A.; Siebelt, M.; Sandker, M.; Waarsing, J.H.; Verhaar, J.A.N.; Jahr, H.; Zadpoor, A.A.; Leeuwenburgh, S.C.G.; Weinans, H.","","2013","Porous titanium scaffolds are a promising class of biomaterials for grafting large bone defects, because titanium provides sufficient mechanical support, whereas its porous structure allows bone ingrowth resulting in good osseointegration. To reinforce porous titanium scaffolds with biological cues that enhance and continue bone regeneration, scaffolds can be incorporated with bioactive gels for time- and dose-controlled delivery of multiple growth factors (GFs). In this study, critical femoral bone defects in rats were grafted with porous titanium scaffolds incorporated with nanostructured colloidal gelatin gels. Gels were loaded with bone morphogenetic protein-2 (BMP-2, 3 mg), fibroblast growth factor-2 (FGF-2, 0.6 mg), BMP-2, and FGF-2 (BMP-2/FGF-2, ratio 5:1) or were left unloaded. GF delivery was controlled by fine tuning the crosslinking density of oppositely charged nanospheres. Grafted femurs were evaluated using in vivo and ex vivo micro-CT, histology, and three-point bending tests. All porous titanium scaffolds containing GF-loaded gels accelerated and enhanced bone regeneration: BMP-2 gels gave an early increase (0–4 weeks), and FGF-2 gels gave a late increase (8–12 weeks). Interestingly, stimulatory effects of 0.6 mg FGF-2 were similar to a fivefold higher dose of BMP-2 (3 mg). BMP-2/FGF-2 gels gave more bone outside the porous titanium scaffolds than gels with only BMP-2 or FGF-2, resulted in bridging of most defects and showed superior bone-implant integrity in three-point bending tests. In conclusion, incorporation of nanostructured colloidal gelatin gels capable of time- and dose-controlled delivery of BMP-2 and FGF-2 in porous titanium scaffolds is a promising strategy to enhance and continue bone regeneration of large bone defects.","","en","journal article","Mary Ann Liebert","","","","","","","","Mechanical, Maritime and Materials Engineering","Biomechanical Engineering","","","",""
"uuid:fd274942-cdb7-4824-8ff3-4792f0277f1e","http://resolver.tudelft.nl/uuid:fd274942-cdb7-4824-8ff3-4792f0277f1e","Adaptive multi-dimensional data decomposition","Lenseigne, B.A.J.; Van Breda, E.C.C.; Jonker, P.P.","","2013","A method of decomposing an image or video into a plurality of components. The method comprises: obtaining (10) an intensity signal of the image or video; and decomposing (30) the intensity signal into a component representing the three-dimensional structure shape of one or more objects in the scene and at least one other component. Also provided is a method of performing an Empirical Mode Decomposition on data in two or more dimensions, using normalised convolution.","","en","patent","European Patent Office","","","","","","","","Mechanical, Maritime and Materials Engineering","Biomechanical Engineering","","","",""
"uuid:9e6b05eb-c173-46e2-89cc-45678ea4604b","http://resolver.tudelft.nl/uuid:9e6b05eb-c173-46e2-89cc-45678ea4604b","Differentiation between non-neural and neural contributors to ankle joint stiffness in cerebral palsy","De Gooijer-van de Groep, K.L.; De Vlugt, E.; De Groot, J.H.; Van der Heijden-Maessen, H.C.M.; Wielheesen, D.H.M.; Van Wijlen-Hempel, R.M.S.; Arendzen, J.H.; Meskers, C.G.M.","","2013","Background Spastic paresis in cerebral palsy (CP) is characterized by increased joint stiffness that may be of neural origin, i.e. improper muscle activation caused by e.g. hyperreflexia or non-neural origin, i.e. altered tissue viscoelastic properties (clinically: “spasticity” vs. “contracture”). Differentiation between these components is hard to achieve by common manual tests. We applied an assessment instrument to obtain quantitative measures of neural and non-neural contributions to ankle joint stiffness in CP. Methods Twenty-three adolescents with CP and eleven healthy subjects were seated with their foot fixated to an electrically powered single axis footplate. Passive ramp-and-hold rotations were applied over full ankle range of motion (RoM) at low and high velocities. Subject specific tissue stiffness, viscosity and reflexive torque were estimated from ankle angle, torque and triceps surae EMG activity using a neuromuscular model. Results In CP, triceps surae reflexive torque was on average 5.7 times larger (p?=?.002) and tissue stiffness 2.1 times larger (p?=?.018) compared to controls. High tissue stiffness was associated with reduced RoM (p?.001). Ratio between neural and non-neural contributors varied substantially within adolescents with CP. Significant associations of SPAT (spasticity test) score with both tissue stiffness and reflexive torque show agreement with clinical phenotype. Conclusions Using an instrumented and model based approach, increased joint stiffness in CP could be mainly attributed to higher reflexive torque compared to control subjects. Ratios between contributors varied substantially within adolescents with CP. Quantitative differentiation of neural and non-neural stiffness contributors in CP allows for assessment of individual patient characteristics and tailoring of therapy.","cerebral palsy; movement disorder; ankle joint; stiffness; spasticity; contracture; neuromechanics; system identification; neuromuscular modeling","en","journal article","BioMed Central","","","","","","","","Mechanical, Maritime and Materials Engineering","Biomechanical Engineering","","","",""
"uuid:1fbf9ca4-bb43-4ccc-8c15-a0b9d2056097","http://resolver.tudelft.nl/uuid:1fbf9ca4-bb43-4ccc-8c15-a0b9d2056097","Making function modeling practically usable","Tomiyama, T.; Van Beek, T.; Alvarez Cabrera, A.A.; Komoto, H.; D'Amelio, V.","","2013","","function; function modeling; function reasoning; product development; systems architecting","en","journal article","Cambridge University Press","","","","","","","2014-07-23","Mechanical, Maritime and Materials Engineering","Biomechanical Engineering","","","",""
"uuid:3b46f593-9d00-47ba-983d-d3af5cc18e93","http://resolver.tudelft.nl/uuid:3b46f593-9d00-47ba-983d-d3af5cc18e93","Why selective publication of statistically significant results can be effective","De Winter, J.C.F.; Happee, R.","","2013","Concerns exist within the medical and psychological sciences that many published research findings are not replicable. Guidelines accordingly recommend that the file drawer effect should be eliminated and that statistical significance should not be a criterion in the decision to submit and publish scientific results. By means of a simulation study, we show that selectively publishing effects that differ significantly from the cumulative meta-analytic effect evokes the Proteus phenomenon of poorly replicable and alternating findings. However, the simulation also shows that the selective publication approach yields a scientific record that is content rich as compared to publishing everything, in the sense that fewer publications are needed for obtaining an accurate meta-analytic estimation of the true effect. We conclude that, under the assumption of self-correcting science, the file drawer effect can be beneficial for the scientific collective.","","en","journal article","Public Library of Science","","","","","","","","Mechanical, Maritime and Materials Engineering","Biomechanical Engineering","","","",""
"uuid:0231b507-ebe4-466b-b9ac-21e6ae2c780d","http://resolver.tudelft.nl/uuid:0231b507-ebe4-466b-b9ac-21e6ae2c780d","Natural grasping, design and evaluation of a voluntary closing adaptive hand prosthesis","Smit, G.","Van der Helm, F.C.T. (promotor); Plettenburg, D.H. (promotor)","2013","Replacement of a missing hand by an artificial alternative remains one of the biggest challenges in rehabilitation. Although many different terminal devices are available, around 27% of the amputees does not actively use their device and 20% totally refrains from wearing it. There are various reasons for prosthesis abandonment, e.g. wearing discomfort (too heavy, too hot), too little added functionality, difficult or tiring to use, lack of sensory feedback. User studies identified multiple aspects of the prostheses that need improvement, in order to meet the user demands. Mass reduction was identified as the most important design priority. In general the user demands can be summarised by the three C’s: Cosmesis, Comfort, and Control. The prosthesis should be beautiful to look at, comfortable to wear, and easy to operate. The goal of this thesis was to design and test a new lightweight and efficient body-powered hand prosthesis with articulating fingers. A low mass will increase wearing comfort. Mechanical efficiency will decrease the required actuation force, which will lead to an increased control comfort. It will also enable the hand to produce a higher pinch force, which will increase the functionality of the hand. The articulating fingers of the hand will enable both power and pinch grip. This enables the grasping and holding of a broad range of different objects and enhances natural cosmesis. The first step of the study was to determine the state-of-the-art in body-powered prostheses. Chapter 2 describes the testing of voluntary closing devices and Chapter 3 the testing of voluntary opening devices. The mechanical performance of the hooks was better than that of the hands. The hands required a high actuation force and energy (1058-2292 Nmm). They dissipated a large part of the actuation energy and produced only a low pinch force (~15 N). The mass of the hands was high (~423 gram). Comparison with data of a study from 1987 showed no improvement in the mechanical performance of the terminal devices over the last decades. In order to meet the user demands, a new hand design should have a lower mass, require less actuation energy, dissipate less energy and should be able to produce a higher pinch force. Chapter 4 describes the design and testing of two underactuated finger prototypes. One finger had a pulley cable transmission, the other a hydraulic cylinder transmission. The fingers were optimized for application in a finger of a cosmetic glove of a prosthetic hand. The fingers had identical dimensions and they had a very low mass. Quantitative mechanical tests were performed to select the most efficient way of transmission. The pulley finger required 35-74% more energy for various tasks than the hydraulic finger. Based on the results the hydraulic finger was selected as the most suitable for application in a prosthetic hand, as it had a higher energy efficiency than the pulley finger. Furthermore the hydraulic transmission offers an additional improvement of efficiency of 10-40% of the entire system, when hydraulics is used to replace the Bowden-cable in the shoulder harness. Therefore the hydraulic transmission was chosen to be used in the new hand prototype. Chapter 5 describes the mechanical comparison of silicone and PVC cosmetic gloves. Both types of gloves can be used for a prosthesis. The tests were performed to select the most energy efficient cosmetic glove. The tested silicone gloves had a 2.5-4.5 lower stiffness than the PVC glove, required 1.8 to 3.8 times less actuation energy and dissipated 1.7 to 3.4 times less energy. Therefore for the new hand prototype a silicone glove was used. Chapter 6 describes the design and testing of a glove compensation mechanism. This mechanism, which fit inside a finger, had a negative stiffness which compensates the undesired positive stiffness of a cosmetic glove. The negative stiffness of the mechanism reduced the required input torque range by 58% for the PVC glove and by 52% for the silicone glove. A negative stiffness mechanism was applied to the new hand prototype, in order to reduce the actuation effort for the user. The final step of the study was the design, and testing of a new hand prototype, described in Chapter 7. The new hand prototype, the Delft Cylinder Hand, has underactuated articulating fingers which adapt to the grasped object. It has voluntary closing body-powered control and it has a hydraulic cylinder transmission. The hand was subjected to various mechanical and functional tests. Chapter 8 describes the comparison of the performance of the hand to current available hands. Through the application of a hydraulic transmission, the hand requires 49-162% less energy from the user when compared to commercially available body-powered hands and it has a higher maximum pinch force (30-60 N). In functional tests the hand scored similar to current myoelectric hands. Yet its mass (152 gram without glove; 217 gram with glove) is 68% lower than the lightest available articulating myoelectric hand and 55% less than the lightest body-powered hand of similar size. Functional tests showed that The ‘Delft Cylinder hand’ provides the amputee with a level of function that is at least comparably to contemporary hands, at a cost (mass and actuation effort) which is much lower than that of all currently available hands. The Delft Cylinder Hand has articulating fingers and is anthropomorphic, slender, fast, efficient and silent. The hand mass is much lower than the lightest commercially available hand. The hand therefore meets one of the most important user demands in upper limb prosthetics, which is a low hand mass. The hand can pinch harder (>30 N) at a lower user effort. Samenvatting Natuurlijk Grijpen: Ontwerp en evaluatie van een actief sluitende adaptieve hand prothese Het vervangen van een ontbrekende menselijke hand, door een kunsthand is een van de grootste uitdagingen op het gebied van de revalidatie. Hoewel er veel verschillende handprothesen beschikbaar zijn, gebruikt 27% van de handprothesedragers de prothese niet actief en draagt 20% helemaal geen prothese. Er zijn verschillende redenen waarom mensen stoppen met het dragen van de prothese, bijv. draagcomfort (te zwaar, te warm), te weinig functioneel voordeel, moeilijk of vermoeiend in het gebruik, gebrek aan sensorische feedback. Gebruikersstudies laten zien dat verschillende aspecten van de prothesen verbeterd dienen te worden, om te voldoen aan de eisen van de gebruiker. Vermindering van de massa van de prothese heeft hierbij de hoogste prioriteit. De gebruikerseisen kunnen kortweg samengevat worden door de drie C’s: Cosmetiek, Comfort en Controle. De prothese moet mooi zijn om te zien, comfortabel om te dragen en moet makkelijk te bedienen zijn. Het doel van deze studie was het ontwerpen en het testen van een lichtgewicht en mechanisch efficiënte lichaamsbekrachtigde handprothese met articulerende ofwel scharnierende vingers. Een lage prothesemassa zal het draagcomfort verbeteren. Mechanische efficiëntie zal de bedieningskracht verlagen en daarmee het bedieningscomfort verhogen. Ook zal de hand hierdoor harder kunnen knijpen, wat zal resulteren in een verbeterde functionaliteit van de hand. De articulerende vingers maken het mogelijk om zowel de pincetgreep als de cilindergreep te vormen. Hierdoor kan een breed scala aan verschillende objecten worden vastgehouden. Bovendien verbetert dit de natuurlijke cosmetiek. De eerste stap in de studie was om de state-of-the-art van de huidige lichaamsbekrachtigde prothesen te bepalen. Hoofdstuk 2 beschrijft het testen van actief sluitende prothesen en hoofdstuk 3 beschrijft het testen van actief openende prothesen. De mechanische efficiëntie van de geteste haken was beter dan die van de handen. Voor het bedienen van de handen was een hoge bedieningsinspanning en bedieningsenergie (1058-2292 Nmm) nodig. Ook dissipeerden de handen een groot gedeelte van de bedieningsenergie en leverden ze slechts een lage knijpkracht (~15 N). De massa van de handen was hoog (~423 gram). Een vergelijking met de resultaten van een studie uit 1987 liet zien dat de prothesen de afgelopen decennia niet verbeterd waren. Om te voldoen aan de gebruikerseisen moet een nieuw handontwerp een lagere massa hebben, minder bedieningsenergie vragen, minder bedieningsenergie dissiperen en de hand dient een hogere knijpkracht te leveren. Hoofdstuk 4 beschrijft het ontwerp en het testen van twee ondergeactueerde vingerprototypen. Het ene vingerprototype was voorzien van een kabel-katrol transmissie, het andere van een hydraulisch transmissie. Beide vingers waren geoptimaliseerd voor toepassing in een cosmetische handschoen van een handprothese. De vingers hadden identieke afmetingen en hadden een erg lage massa. Er zijn kwantitatieve testen uitgevoerd om te bepalen welke transmissie het efficiëntst was. De vinger met de kabel-katrol transmissie had 35-74% meer energie nodig voor verschillende taken dan de hydraulische vinger. Vanwege de hogere mechanische efficiëntie van de hydraulische vinger, is deze vinger geselecteerd als meest geschikte vinger voor toepassing in een handprothese. Bovendien biedt een hydraulische transmissie een extra efficiëntieverbetering van 10-40%, wanneer de hydraulische transmissie gebruikt wordt om de Bowdenkabel te vervangen. Daarom is besloten om in het nieuwe handprototype de hydraulische transmissie toe te passen. Hoofdstuk 5 beschrijft vergelijking van mechanische eigenschappen van cosmetische handschoenen van siliconen en PVC. Beiden typen handschoen kunnen gebruikt worden op een handprothese. De testen zijn uitgevoerd om de handschoen te selecteren met de hoogste energie-efficiëntie. De stijfheid van de gemeten siliconen handschoenen was 2.5-4.5 keer lager dan die van de PVC handschoenen. De siliconen handschoen hadden een 1.8 tot 3.8 keer lagere actuatie-energie nodig en dissipeerden 1.7 tot 3.4 keer minder energie. Er is daarom gekozen om voor het nieuwe hand prototype een siliconen handschoen te gebruiken. Hoofdstuk 6 beschrijft het ontwerp en het testen van een handschoencompensatiemechanisme. Dit mechanisme, dat binnenin een vinger past, heeft een negatieve stijfheid die de ongewenste positieve stijfheid van de handschoen compenseert. De negatieve stijfheid van het mechanisme verminderde het benodigde actuatiemoment met 58% voor de PVC handschoen en met 52% voor de siliconen handschoen. In het nieuwe handprototype is ook een mechanisme met een negatieve stijfheid toegepast, om de vereiste bedieningsinspanning van de gebruiker te verlagen. De laatste stap van de studie was het ontwerpen en het testen van een nieuwe handprototype, beschreven in hoofdstuk 7. Het nieuwe handprototype, de Delft Cylinder Hand, heeft ondergeactueerde articulerende vingers die zich aanpassen aan de vorm van het object. De hand wordt bediend met een lichaamsbekrachtigde actief-sluitende bediening. De transmissie van de hand is hydraulisch. De hand is onderworpen aan verschillende mechanische en functionele testen. Hoofdstuk 8 beschrijft de vergelijking van de prestaties van de hand met die van de huidige prothesehanden. Door de toepassing van een hydraulische transmissie hoeft de gebruiker 49-162% minder energie te leveren om de hand te bedienen dan voor de huidige lichaamsbekrachtigde handen nodig is. De hand kan een hogere knijpkracht leveren (30-60 N). In de functionele testen behaalde de hand vergelijkbare scores als die van myo-elektrische handen. De massa van de hand (152 gram zonder handschoen; 217 gram met handschoen) is 68% lager dan die van de lichtste articulerende myo-elektrische hand en 55% lager dan die van de lichtste lichaamsbekrachtigde hand van vergelijkbaar formaat. De functionele testen lieten zien dat de ‘Delft Cylinder Hand’ de prothesegebruiker een functionaliteit biedt die tenminste vergelijkbaar is met die van de huidige prothesehanden, tegen een belasting (handmassa en bedieningsinspanning) die veel kleiner is dan die van alle huidig beschikbare handen. De Delft Cylinder Hand heeft articulerende vingers en is antropomorfisch, rank, snel, efficiënt en stil. De handmassa is veel lager dan die van de lichtste commercieel verkrijgbare hand. De hand beantwoord daarmee aan een van de belangrijkste gebruikerseisen, namelijk die van een lage handmassa. De hand kan harder knijpen (>30 N) met een lagere bedieningsinspanning.","body powered; efficiency; hysteresis; prosthetic design; prosthetic evaluation; prosthetic hand; prosthetics; qualitative testing; upper limb; voluntary opening; handprothese; handprothesen; armprothese; armprothesen; kunstledematen; Delft Cylinder Hand; hydrauliek; hydraulics; pinch force","en","doctoral thesis","TU Delft","","","","","","","2015-02-09","Mechanical, Maritime and Materials Engineering","BioMechanical Engineering","","","",""
"uuid:5d33302b-cf06-4e25-b1ff-de1389969ae4","http://resolver.tudelft.nl/uuid:5d33302b-cf06-4e25-b1ff-de1389969ae4","The effect of directional inertias added to pelvis and ankle on gait","Meuleman, J.H.; Van Asseldonk, E.H.F.; Van der Kooij, H.","","2013","Background Gait training robots should display a minimum added inertia in order to allow normal walking. The effect of inertias in specific directions is yet unknown. We set up two experiments to assess the effect of inertia in anteroposterior (AP) direction to the ankle and AP and mediolateral (ML) direction to the pelvis. Methods We developed an experimental setup to apply inertia in forward backward and or sideways directions. In two experiments nine healthy subjects walked on a treadmill at 1.5 km/h and 4.5 km/h with no load and with AP loads of 0.3, 1.55 and 3.5 kg to the left ankle in the first experiment and combinations of AP and ML loads on the pelvis (AP loads 0.7, 4.3 and 10.2 kg; ML loads 0.6, 2.3 and 5.3 kg). We recorded metabolic rate, EMG of major leg muscles, gait parameters and kinematics. Results & discussion Adding 1.55 kg or more inertia to the ankle in AP direction increases the pelvis acceleration and decreases the foot acceleration in AP direction both at speeds of 4.5 km/h. Adding 3.5 kg of inertia to the ankle also increases the swing time as well as AP motions of the pelvis and head-arms-trunk (HAT) segment. Muscle activity remains largely unchanged. Adding 10.2 kg of inertia to the pelvis in AP direction causes a significant decrease of the pelvis and HAT segment motions, particularly at high speeds. Also the sagittal back flexion increases. Lower values of AP inertia and ML inertias up to 5.3 kg had negligible effect. In general the found effects are larger at high speeds. Conclusions We found that inertia up to 2 kg at the ankle or 6 kg added to the pelvis induced significant changes, but since these changes were all within the normal inter subject variability we considered these changes as negligible for application as rehabilitation robotics and assistive devices.","inertia; kinematics; pelvis; metabolic rate; locomotion; leg loading; emg; robotic gait trainers","en","journal article","BioMed Central","","","","","","","","Mechanical, Maritime and Materials Engineering","Biomechanical Engineering","","","",""
"uuid:b36e3335-d85a-4953-9416-f852514b75f1","http://resolver.tudelft.nl/uuid:b36e3335-d85a-4953-9416-f852514b75f1","Identifying intrinsic and reflexive contributions to low-back stabilization","Van Drunen, P.; Maaswinkel, E.; Van der Helm, F.C.T.; Van Dieën, J.H.; Happee, R.","","2013","Motor control deficits have been suggested as potential cause and/or effect of a-specific chronic low-back pain and its recurrent behavior. Therefore, the goal of this study is to identify motor control in low-back stabilization by simultaneously quantifying the intrinsic and reflexive contributions. Upper body sway was evoked using continuous force perturbations at the trunk, while subjects performed a resist or relax task. Frequency response functions (FRFs) and coherences of the admittance (kinematics) and reflexes (sEMG) were obtained. In comparison with the relax task, the resist task resulted in a 61% decrease in admittance and a 73% increase in reflex gain below 1.1 Hz. Intrinsic and reflexive contributions were captured by a physiologically-based, neuromuscular model, including proprioceptive feedback from muscle spindles (position and velocity) and Golgi tendon organs (force). This model described on average 90% of the variance in kinematics and 39% of the variance in sEMG, while resulting parameter values were consistent over subjects.","Lumbar Spine; postural control; system identification; muscle spindles; Golgi tendon organ","en","journal article","Elsevier","","","","","","","","Mechanical, Maritime and Materials Engineering","Biomechanical Engineering","","","",""
"uuid:518525d0-8b26-4155-a3c6-1d88e92933f4","http://resolver.tudelft.nl/uuid:518525d0-8b26-4155-a3c6-1d88e92933f4","Statische houdingen tijdens levende-nierdonaties: De handgeassisteerde versus de laparoscopische aanpak","Wauben, L.S.G.L.; Albayrak, A.; Dols, N.; Goossens, R.H.M.; IJzermans, J.","","2013","In 2010 ontvingen 865 Nederlanders die lijden aan chronisch nierfalen een nieuwe nier. Maar er wachten nog steeds 892 patiënten op een donornier en ongeveer 1275 dialysepatiënten sterven elk jaar. Levende-nierdonatie lijkt een geschikte optie om het donortekort te verminderen. Hierbij staat een ‘gezond’ familielid (maar soms ook een anonieme donor) een nier af. In 2010 was 55% van de getransplanteerde nieren afkomstig van een levende donor. Aangezien deze gezonde donoren geen direct voordeel van de operatie ondervinden, moet hun veiligheid en daarmee dus ook de veiligheid van de operatie worden gewaarborgd.","","nl","journal article","Nederlandse Vereniging voor Ergonomie","","","","","","","","Mechanical, Maritime and Materials Engineering","Biomechanical Engineering","","","",""
"uuid:5f5c0ac8-9d21-4d28-af24-e9e71bf50f84","http://resolver.tudelft.nl/uuid:5f5c0ac8-9d21-4d28-af24-e9e71bf50f84","Integration of Sensory Force Feedback Is Disturbed in CRPS-Related Dystonia","Mugge, W.; Van der Helm, F.C.T.; Schouten, A.C.","","2013","Complex regional pain syndrome (CRPS) is characterized by pain and disturbed blood flow, temperature regulation and motor control. Approximately 25% of cases develop fixed dystonia. The origin of this movement disorder is poorly understood, although recent insights suggest involvement of disturbed force feedback. Assessment of sensorimotor integration may provide insight into the pathophysiology of fixed dystonia. Sensory weighting is the process of integrating and weighting sensory feedback channels in the central nervous system to improve the state estimate. It was hypothesized that patients with CRPS-related dystonia bias sensory weighting of force and position toward position due to the unreliability of force feedback. The current study provides experimental evidence for dysfunctional sensory integration in fixed dystonia, showing that CRPS-patients with fixed dystonia weight force and position feedback differently than controls do. The study shows reduced force feedback weights in CRPS-patients with fixed dystonia, making it the first to demonstrate disturbed integration of force feedback in fixed dystonia, an important step towards understanding the pathophysiology of fixed dystonia.","OA-Fund TU Delft","en","journal article","Public Library of Science","","","","","","","","Mechanical, Maritime and Materials Engineering","Biomechanical Engineering","","","",""
"uuid:40046ceb-b970-4db5-bb74-3e643e70d70c","http://resolver.tudelft.nl/uuid:40046ceb-b970-4db5-bb74-3e643e70d70c","Dora will watch over you","Wassink, J.","Van den Dobbelsteen, J. (contributor)","2013","A black box, but then in the operating room. Meet the digital surgical assistant Dora. TU Delft is developing the system together with hospitals and businesses in the province of Zuid-Holland. “We can learn a lot from aviation.”","Dora","en","journal article","Delft University of Technology","","","","","","","","Mechanical, Maritime and Materials Engineering","Biomechanical Engineering","","","",""
"uuid:e31c8b76-c705-44f3-8be9-c12637011217","http://resolver.tudelft.nl/uuid:e31c8b76-c705-44f3-8be9-c12637011217","Identification of the contribution of the ankle and hip joints to multi-segmental balance control","Boonstra, T.A.; Schouten, A.C.; Van der Kooij, H.","","2013","Background Human stance involves multiple segments, including the legs and trunk, and requires coordinated actions of both. A novel method was developed that reliably estimates the contribution of the left and right leg (i.e., the ankle and hip joints) to the balance control of individual subjects. Methods The method was evaluated using simulations of a double-inverted pendulum model and the applicability was demonstrated with an experiment with seven healthy and one Parkinsonian participant. Model simulations indicated that two perturbations are required to reliably estimate the dynamics of a double-inverted pendulum balance control system. In the experiment, two multisine perturbation signals were applied simultaneously. The balance control system dynamic behaviour of the participants was estimated by Frequency Response Functions (FRFs), which relate ankle and hip joint angles to joint torques, using a multivariate closed-loop system identification technique. Results In the model simulations, the FRFs were reliably estimated, also in the presence of realistic levels of noise. In the experiment, the participants responded consistently to the perturbations, indicated by low noise-to-signal ratios of the ankle angle (0.24), hip angle (0.28), ankle torque (0.07), and hip torque (0.33). The developed method could detect that the Parkinson patient controlled his balance asymmetrically, that is, the right ankle and hip joints produced more corrective torque. Conclusion The method allows for a reliable estimate of the multisegmental feedback mechanism that stabilizes stance, of individual participants and of separate legs.","balance control; closed-loop system identification; multivariate systems; asymmetry","en","journal article","BioMed Central","","","","","","","","Mechanical, Maritime and Materials Engineering","Biomechanical Engineering","","","",""
"uuid:5d9259e6-cbfe-4a5b-a06d-80b852166377","http://resolver.tudelft.nl/uuid:5d9259e6-cbfe-4a5b-a06d-80b852166377","Variability in bimanual wheelchair propulsion: Consistency of two instrumented wheels during handrim wheelchair propulsion on a motor driven treadmill","Vegter, R.J.K.; Lamoth, C.J.; De Groot, S.; Veeger, H.E.J.; Van der Woude, L.H.V.","","2013","Background Handrim wheelchair propulsion is a complex bimanual motor task. The bimanually applied forces on the rims determine the speed and direction of locomotion. Measurements of forces and torques on the handrim are important to study status and change of propulsion technique (and consequently mechanical strain) due to processes of learning, training or the wheelchair configuration. The purpose of this study was to compare the simultaneous outcomes of two different measurement-wheels attached to the different sides of the wheelchair, to determine measurement consistency within and between these wheels given the expected inter- and intra-limb variability as a consequence of motor control. Methods Nine able-bodied subjects received a three-week low-intensity handrim wheelchair practice intervention. They then performed three four-minute trials of wheelchair propulsion in an instrumented hand rim wheelchair on a motor-driven treadmill at a fixed belt speed. The two measurement-wheels on each side of the wheelchair measured forces and torques of one of the two upper limbs, which simultaneously perform the push action over time. The resulting data were compared as direct output using cross-correlation on the torque around the wheel-axle. Calculated push characteristics such as power production and speed were compared using an intra-class correlation. Results Measured torque around the wheel axle of the two measurement-wheels had a high average cross-correlation of 0.98 (std=0.01). Unilateral mean power output over a minute was found to have an intra-class correlation of 0.89 between the wheels. Although the difference over the pushes between left and right power output had a high variability, the mean difference between the measurement-wheels was low at 0.03 W (std=1.60). Other push characteristics showed even higher ICC’s (>0.9). Conclusions A good agreement between both measurement-wheels was found at the level of the power output. This indicates a high comparability of the measurement-wheels for the different propulsion parameters. Data from both wheels seem suitable to be used together or interchangeably in experiments on motor control and wheelchair propulsion performance. A high variability in forces and timing between the left and right side were found during the execution of this bimanual task, reflecting the human motor control process.","(MeSH); wheelchairs; rehabilitation; biomechanics; motor skills","en","journal article","BioMed Central","","","","","","","","Mechanical, Maritime and Materials Engineering","Biomechanical Engineering","","","",""
"uuid:1546b0da-29dd-4dfa-ad6f-b19ebab09aa9","http://resolver.tudelft.nl/uuid:1546b0da-29dd-4dfa-ad6f-b19ebab09aa9","Selective control of gait subtasks in robotic gait training: Foot clearance support in stroke survivors with a powered exoskeleton","Koopman, B.; Van Asseldonk, E.H.F.; Van der Kooij, H.","","2013","Background Robot-aided gait training is an emerging clinical tool for gait rehabilitation of neurological patients. This paper deals with a novel method of offering gait assistance, using an impedance controlled exoskeleton (LOPES). The provided assistance is based on a recent finding that, in the control of walking, different modules can be discerned that are associated with different subtasks. In this study, a Virtual Model Controller (VMC) for supporting one of these subtasks, namely the foot clearance, is presented and evaluated. Methods The developed VMC provides virtual support at the ankle, to increase foot clearance. Therefore, we first developed a new method to derive reference trajectories of the ankle position. These trajectories consist of splines between key events, which are dependent on walking speed and body height. Subsequently, the VMC was evaluated in twelve healthy subjects and six chronic stroke survivors. The impedance levels, of the support, were altered between trials to investigate whether the controller allowed gradual and selective support. Additionally, an adaptive algorithm was tested, that automatically shaped the amount of support to the subjects’ needs. Catch trials were introduced to determine whether the subjects tended to rely on the support. We also assessed the additional value of providing visual feedback. Results With the VMC, the step height could be selectively and gradually influenced. The adaptive algorithm clearly shaped the support level to the specific needs of every stroke survivor. The provided support did not result in reliance on the support for both groups. All healthy subjects and most patients were able to utilize the visual feedback to increase their active participation. Conclusion The presented approach can provide selective control on one of the essential subtasks of walking. This module is the first in a set of modules to control all subtasks. This enables the therapist to focus the support on the subtasks that are impaired, and leave the other subtasks up to the patient, encouraging him to participate more actively in the training. Additionally, the speed-dependent reference patterns provide the therapist with the tools to easily adapt the treadmill speed to the capabilities and progress of the patient.","robotic gait rehabilitation; stroke; reference trajectories; virtual model control; support of subtasks; adaptive control; impedance control; reliance; compensatory strategies; visual feedback","en","journal article","BioMed Central","","","","","","","","Mechanical, Maritime and Materials Engineering","Biomechanical Engineering","","","",""
"uuid:93fc609e-03da-4a71-af6a-c632a3c541ec","http://resolver.tudelft.nl/uuid:93fc609e-03da-4a71-af6a-c632a3c541ec","Robotic Bipedal Running: Increasing disturbance rejection","Karssen, J.G.D.","Van der Helm, F.C.T. (promotor)","2013","The goal of the research presented in this thesis is to increase the understanding of the human running gait. The understanding of the human running gait is essential for the development of devices, such as prostheses and orthoses, that enable disabled people to run or that enable able people to increase their running performance. Although these devices are currently being developed, there is not much insight yet in the fundamentals of the running gait. This fundamental knowledge is required for improving these devices. One of the big unknowns is how these devices affect the ability of the user to handle disturbances, like sudden pushes or variations in floor height. To gain insight in the fundamentals of the human running gait and the disturbance rejection behavior in particular, the gait synthesis approach is taken. In this approach, the running gait is studied by synthesizing the human running on simulation models and on robots. This allows studying the effects of specific system parameters in a simplified and controlled environment. A number of simulation models and a physical running robot have been developed. The simulation models vary in complexity, from simple simulation models based on the well-known spring loaded inverted pendulum (SLIP) model to simulation models that closely resemble the physical running robot. The simple simulation models are useful to get fundamental insights, due to their simple dynamics. The results of the simple models are validated with the more realistic models and physical running robot. This thesis focuses on the effect of three important system parameters on the disturbance rejection behavior. These three parameters are: the leg stiffness profile, the location of the center-of-mass, and the swing-leg retraction rate. These three parameters were selected, based on our experience with walking robots. The research in this thesis shows that the effects of these parameters are the following. The leg stiffness profile has a significant influence on the disturbance rejection behavior. For a simple running model, we show that nonlinear leg springs can improve the disturbance rejection up to a factor 7 compared to the optimal linear leg spring. The optimal leg stiffness profile for the maximal disturbance rejection behavior is strongly nonlinear. These results show that the generally used linear leg springs are far from optimal in terms of disturbance rejection behavior. The location of the center-of-mass of the torso also has a large influence on the disturbance rejection. The optimal center-of-mass location depends on the type of the expected disturbance, which is above the hip for floor height disturbances and below the hip for push disturbances on the center-of-mass. The commonly used center-of-mass location at the hip is far from optimal. An offset of the center-of-mass location can increase the disturbance rejection up to a factor 10 compared to the center-of-mass at the hip. The swing-leg retraction rate, the speed of the backwards rotation of the front leg prior to touchdown, affects the disturbance rejection rate. We show that this effect is maximal at a mild retraction rate, which is much lower than the retraction rate for ground speed matching. The optimal retraction rate decreases with increasing running velocity. Besides improving disturbance rejection, swing-leg retraction can also reduce energetic losses, impact forces, and the risk of slipping. However, we show that all of the benefits of swing-leg retraction occur at different retraction rates, which indicates that there is an inherent tradeoff to consider when selecting the retraction rate for a robot control system. In addition, the effect of the retraction rate on these benefits is strongly model and/or parameter dependent, making it difficult to make general rules on how to select the retraction rate. Besides the above-mentioned results, this research also revealed the following insights. Firstly, not all results from simple running model studies transfer well to more realistic models and robots. This is especially the case for studies on effects that involve impact dynamics, as impact dynamics greatly depend on the leg morphology. Secondly, the gait sensitivity norm, the disturbance rejection measured introduced by Hobbelen for walking systems, is also suitable for running systems. Finally, the implementation of a spring in parallel with the actuator in the knee joint can greatly reduce the required actuator torque and power. Overall, the results of this thesis show that there are many opportunities to improve the disturbance rejection performance of bipedal running robots. This can be done either by mechanical changes to the robotics system, e.g. implementing a nonlinear leg spring or placing the center-of-mass away from the hip, or by changes to the controller, e.g. implementing swing-leg retraction. The results of this thesis also point out promising directions for the development of better running orthoses and prostheses. Most promising is the implementation of nonlinear springs in exoskeletons, because the results show a large improvement in the disturbance rejection behavior and because nonlinear springs are relatively easy to implement in exoskeletons.","running; robot","en","doctoral thesis","","","","","","","","2013-01-04","Mechanical, Maritime and Materials Engineering","BioMechanical Engineering","","","",""
"uuid:4368c493-b659-47fb-aa43-22503a692a15","http://resolver.tudelft.nl/uuid:4368c493-b659-47fb-aa43-22503a692a15","A method to reduce ambiguities of qualitative reasoning for conceptual design applications","D'Amelio, V.; Chmarra, M.K.; Tomiyama, T.","","2013","Qualitative reasoning can generate ambiguous behaviors due to the lack of quantitative information. Despite many different research results focusing on ambiguities reduction, fundamentally it is impossible to totally remove ambiguities with only qualitative methods and to guarantee the consistency of results. This prevents the wide use of qualitative reasoning techniques in practical situations, particularly in conceptual design, where qualitative reasoning is considered intrinsically useful. To improve this situation, this paper initially investigates the origin of ambiguities in qualitative reasoning. Then it proposes a method based on intelligent interventions of the user who is able to detect ambiguities, to prioritize interventions on these ambiguities, and to reduce ambiguities based on the least commitment strategy. This interaction method breaks through the limit of qualitative reasoning in practical applications to conceptual design. The method was implemented as a new feature in a software tool called the Knowledge Intensive Engineering Framework in order to be tested and used for a printer design.","ambiguity reduction; conceptual design; qualitative process theory; qualitative reasoning; user intervention","en","journal article","Cambridge University Press","","","","","","","2014-01-15","Mechanical, Maritime and Materials Engineering","Biomechanical Engineering","","","",""
"uuid:3f0a35f2-c1c1-4a6b-a5cb-28cb897c9c36","http://resolver.tudelft.nl/uuid:3f0a35f2-c1c1-4a6b-a5cb-28cb897c9c36","Exploration and Learning for Cognitive Robots","Rudinac, M.","Jonker, P. (promotor)","2013","Before a future with household robots is really feasible, those robots need to be easily adaptable to novel environments and users, be able to apply previously acquired knowledge, and able to learn from perceiving and interacting with the world and users around them. This thesis proposes a cognitive architecture and a set of underlining methods for automatic knowledge acquisition that will bring household robots one step closer to reality. The thesis was inspired by the cognitive development of babies and subsequently treats the topics: Knowledge representation, Sensory motor integration, Knowledge acquisition & learning and Real world applications. We derived ways to describe and efficiently combine visual information, despite cluttered environments and changing illumination. We propose a method to combine different key-point extractors and to select only a small subset based on their information entropy. Since object appearances can vary in colour, texture and 2D/3D shape, we extract feature vectors from multiple viewpoints of the object and calculate the dominant features, which leads to a more robust object recognition process. This also automatically calculates the most efficient way to store the representative features of unknown objects. This method is similar to the information storage process in humans; an important characteristic of human learning is the pruning of information in the working memory to the most relevant information to be stored in long term memory. In order to detect and segment objects without any prior knowledge on their appearance or their background, we designed a visual-attention module that is able to find the salient parts of an image and clusters them into objects ranked by their saliency. Once these objects are localized, the system must act upon them to efficiently learn their properties. This is achieved by simultaneous exploration and manipulation of the selected - most salient - unknown object. However, such a cognitive system cannot be realized without a robot body, and therefore we designed a simple and affordable robot. Another cognitive ability that a future household robot certainly must have is knowledge accumulation from previous experiences. Consequently, we designed a cognitive architecture that allows a robot that has no pre- insight in the world and its objects to incrementally acquire all its expertise from interaction with the environment. We proposed models of working and long term memory as well as algorithms for novelty detection. Finally, we treat two realized applications for external parties, based on our algorithms: Bin-picking by an industrial robot and action detection in ceiling mounted cameras in elderly homes.","cognitive robots; attention modeling; object segmentation; knowledge acquisition and learning; real world applications","en","doctoral thesis","","","","","","","","2013-01-08","Mechanical, Maritime and Materials Engineering","BioMechanical Engineering","","","",""
"uuid:e55403e9-75e1-439e-a5ee-21b804060beb","http://resolver.tudelft.nl/uuid:e55403e9-75e1-439e-a5ee-21b804060beb","Enhancing driver car-following performance with a distance and acceleration display","Saffarian, M (TU Delft Biomechatronics & Human-Machine Control); de Winter, J.C.F. (TU Delft Medical Instruments & Bio-Inspired Technology); Happee, R. (TU Delft Biomechanical Engineering)","","2013","A car-following assisting system named the rear window notification display (RWND) was developed, with the aim of improving a driver's manual car-following performance. The RWND presented lead-car acceleration and time headway (THW) (i.e., intervehicle distance divided by the speed of the following car) on the rear window of a lead car, which was driven automatically. A simulator-based experiment with 22 participants showed that the RWND reduced both the mean and standard deviation of THW but did not increase the occurrence of potentially unsafe headways of less than 1 s. The parameter estimation of a common linear car-following model showed that drivers accomplished the performance improvements by adopting higher control gains with respect to intervehicle distance, relative speed, and acceleration. A postexperiment questionnaire revealed that the display was generally not regarded as a distraction nor did participants think that it provided too much information, with means of 4.0 and 2.9, respectively, on a scale from one (completely disagree) to ten (completely agree). The results of this study suggest that the RWND can be used along with Cooperative Adaptive Cruise Control to increase traffic flow without degrading safety.","","en","journal article","","","","","","Green Open Access added to TU Delft Institutional Repository 'You share, we take care!' - Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.","","2013-03-12","","Biomechanical Engineering","Biomechatronics & Human-Machine Control","","",""
"uuid:457d1e32-8300-47ea-884e-5246f52d3606","http://resolver.tudelft.nl/uuid:457d1e32-8300-47ea-884e-5246f52d3606","A statically balanced and bi-stable compliant end effector combined with a laparoscopic 2DoF robotic arm","Lassooij, J.; Tolou, N.; Tortora, G.; Caccavaro, S.; Menciassi, A.; Herder, J.L.","","2012","This article presents the design of a newly developed 2DoF robotic arm with a novel statically balanced and bi-stable compliant grasper as the end effector for laparoscopic surgery application. The arm is based on internal motors actuating 2 rotational DoFs: pitch and roll. The positive stiffness of the monolithic grasper has been compensated using pre-curved straight guided beams that are preloaded collinear with the direction of actuation of the grasper. The result is a fully compliant statically balanced laparoscopic grasper. The grasper has been successfully adapted to a robotic arm. The maximum force and stiffness compensations were measured to be 94% and 97% (i.e. near zero stiffness) respectively. Furthermore, the feasibility of adjusting for bi-stable behavior has been shown. This research can be a preliminary step towards the design of a statically balanced fully compliant robotic arm for laparoscopic surgery and similar areas.","OA-Fund TU Delft","en","journal article","Copernicus Publications","","","","","","","","Mechanical, Maritime and Materials Engineering","Biomechanical Engineering","","","",""
"uuid:3adeccef-19db-4a06-ab26-8636ac03f5c0","http://resolver.tudelft.nl/uuid:3adeccef-19db-4a06-ab26-8636ac03f5c0","Robust Augmented Reality","Akman, O.","Jonker, P.P. (promotor)","2012","The field of Computer Vision is concerned with problems that involve interfacing computers with their surrounding environment through cameras. Consequently artificial vision systems can replace human perception in many tasks. Recent advances in technology, such as increase in computational power, good quality low cost CMOS cameras, improvement in peripherals and decreasing form-factor, allow the vision systems to be carried on roaming platforms such as tablet PCs and mobile phones. More generally, it leads to the possibility of wearable visual computing that can assist its carrier such as humans or robots in executing various perception-action tasks. Augmented Reality (AR) technologies already have a history in the field of computer vision and many attempts have been made to use AR to create meaningful, immersive experiences incorporating humans and computers. It is appealing for many applications such as in entertainment and gaming to improve and enrich perception, cognition and interaction by providing extra information and guidance that is not available in the immediate surroundings. This thesis presents the application of computer vision algorithms to create a marker-less, mobile and wearable AR system that can provide assistive services to its users. The overall system design includes definition and implementation of the necessary software modules as well as its combination with digital hardware. In the wearable mobile set-up we discuss in this thesis, the user can perceive 3D virtual moving objects augmenting the real world perceived at the same time. The Delft University of Technology initiated their AR research in 1999 with outdoor head-mounted optical see-through AR, fusing data from a GPS, a natural feature tracking camera, and an inertia tracker, using a desktop PC in a backpack. Soon a switch back was made to indoor AR based on markers and inertia tracker data in order to improve the real-time performance and static and dynamic accuracy of the head-pose estimation by the visual odometry system. For applications we collaborated since 2006 with the Royal Academy of Art in The Hague, which has implemented many projects in art and design with our systems. In this thesis, our focus has shifted from art and design onto the design and implementation of a system for multi-user collaboration and spatial analysis using multiple AR systems; more specifically we selected Crime Scene Investigation (CSI) as our application domain. For this we collaborated with the Systems Engineering Section (SES-TPM) of TU Delft and the National Forensic Institute in The Hague. We also switched from optical see-through head-mounted displays (HMD) to cheaper video see-through head mounted displays a.k.a eye wear. In this thesis, we introduce the challenges of mobile AR and CSI, and derive the system requirements that can meet these challenges. We further discuss how a remote collaborator can work with on-site users by decoupling him/her self from the on-site user's view while assisting the investigation. Then we present the real-time and on-line modules that satisfy these requirements: -Robust, marker-less, extensible auto-motion tracking based on the tracking of 3D key-points observed by a low cost stereo camera pair -Coarse 3D map-building to be able to augment a real scene with virtual objects, while roaming around in e.g. crime scenes -On-line and on-site scene structure capturing by reconstructing a metric, dense 3D map of the scene in real time, with the aim to let off-scene experts guide the CSIs -Human-Computer Interaction (HCI) software that exploits the user's hand motions. This acts as an interaction device for user interface operation instead of other auxiliary equipment, such as keyboard and mouse. With this HCI the user - e.g. a CSI - can place virtual objects in the scene, such as tags indicating the position of found evidence -Software for remote connection to and on-line collaboration with off-scene experts, a lightweight and affordable HMD and a wearable computer The realized head-mounted AR system allows interaction and collaboration between two or more parties and their environment, while it provides tools, guidance and information to on-site and off-site users to perform their tasks both independently and in collaboration with each other. According to our knowledge, this is one of the first examples of a complete 3D stereo AR system that integrates 3D marker-less AR capabilities with dense reconstruction, remote collaboration and HCI in a carefully engineered way that can be applied in the CSI domain and many other applications in which on-scene and off-scene experts work together.","Augmented Reality; Human-Computer-Interaction; Natural feature tracking; 3D Reconstruction; Head-Mounted Display","en","doctoral thesis","","","","","","","","","Mechanical, Maritime and Materials Engineering","BioMechanical Engineering","","","",""
"uuid:2d84a076-cb3c-4797-9f2e-11e4ba7044a2","http://resolver.tudelft.nl/uuid:2d84a076-cb3c-4797-9f2e-11e4ba7044a2","Human hand modelling: Kinematics, dynamics, applications","Gustus, A.; Stillfried, G.; Visser, J.; Jörntell, H.; Van der Smagt, P.","","2012","An overview of mathematical modelling of the human hand is given. We consider hand models from a specific background: rather than studying hands for surgical or similar goals, we target at providing a set of tools with which human grasping and manipulation capabilities can be studied, and hand functionality can be described. We do this by investigating the human hand at various levels: (1) at the level of kinematics, focussing on the movement of the bones of the hand, not taking corresponding forces into account; (2) at the musculotendon structure, i.e. by looking at the part of the hand generating the forces and thus inducing the motion; and (3) at the combination of the two, resulting in hand dynamics as well as the underlying neurocontrol. Our purpose is to not only provide the reader with an overview of current human hand modelling approaches but also to fill the gaps with recent results and data, thus allowing for an encompassing picture.","human hand model; hand kinematics; muscle dynamics; tendon dynamics; cadaver studies","en","journal article","Springer-Verlag","","","","","","","","Mechanical, Maritime and Materials Engineering","Department of Biomechanical Engineering","","","",""
"uuid:986ea1c5-9e30-4aac-ab66-4f3b6b6ca002","http://resolver.tudelft.nl/uuid:986ea1c5-9e30-4aac-ab66-4f3b6b6ca002","Reinforcement Learning on autonomous humanoid robots","Schuitema, E.","Jonker, P.P. (promotor); Babuska, R. (promotor)","2012","Service robots have the potential to be of great value in households, health care and other labor intensive environments. However, these environments are typically unique, not very structured and frequently changing, which makes it difficult to make service robots robust and versatile through manual programming. Having robots learn to solve tasks autonomously through interaction with the real world forms an attractive alternative. With Reinforcement Learning (RL), a system can learn to perform tasks by receiving only coarse feedback on its actions: desired behavior is reinforced by positive rewards, undesired behavior is punished by negative rewards. In this research, a bipedal walking robot named Leo was designed and built specifically to study the application of RL to real robots. Robot Leo is able to learn two basic motor control tasks: placing a foot on a step of stairs, and walking. To learn to walk, Leo receives a positive reward for moving its foot forward, and negative rewards for falling and for spending time and energy. This process takes about 5 hours of practice in simulation, as well as thousands of falls. On the real prototype, the learning time was shortened by first letting the robot observe a hand coded, sub-optimal controller, which it was quickly able to mimic and even improve in a matter of hours. Algorithmic improvements are proposed to address complications of RL on real robots, such as time delays in the control loop and large disturbances such as a sudden push. To reduce the continuous risk of damage due to the trial-and-error nature of RL, a modular approach is proposed through which the robot can coarsely but quickly learn about the risk of its behavior and learn the actual task more safely and in more detail.","robotics; robots; reinforcement learning; markov decision process; temporal difference learning","en","doctoral thesis","","","","","","","","","Mechanical, Maritime and Materials Engineering","BioMechanical Engineering","","","",""
"uuid:d6781373-17d2-42ec-859e-a506021e3d1a","http://resolver.tudelft.nl/uuid:d6781373-17d2-42ec-859e-a506021e3d1a","On-ward observations in neonatal intensive care: Towards safer supplemental oxygen & IV therapy","Van der Eijk, A.C.","Dankelman, J. (promotor); Simonsz, H.J. (promotor)","2012","The focus of this thesis is on supplemental oxygen therapy and intrave nous (IV) therapy in neonatal intensive care. Both therapies are essential, but potentially dangerous for (preterm) newborn infants. Supplemental oxygen therapy refers to the therapy where a gas mixture with >21% of oxy gen is supplied to the patient via (mechanical) ventilation to reach and maintain adequate tissue oxygenation. Unfortunately the accurate manual control of the oxygenation in newborn infants is difficult and time consuming. In IV therapy various types of nutrition, drugs, and/or fluids are administered directly into the veins of the patient. Although it is expected that the IV substances are supplied to the patient with the pre-programmed flow-rate, the actual volume delivery varies over time. Particularly in newborn infants, these sudden changes in delivered volume can have severe consequences. The objective of the research was to determine the limitations of supplemental oxygen therapy and IV therapy in current neonatal intensive care and to identify areas for improvements. To meet the objective, several studies were performed including on-ward observations. The overall conclusion is that in both therapies (unregistered) variations in clinical practice are present. It is to be expected that these unnoticed differences in care lead to differences in outcome of patients. To achieve a more standardised approach and to improve the safety of both supplemental oxygen therapy and IV therapy, in this thesis several recommendations are provided.","Neonatal Intensive Care; Oxygen; Preterm infants; Pulse oximetry; Alarm management; Intravenous therapy","en","doctoral thesis","","","","","","","","2014-02-01","Mechanical, Maritime and Materials Engineering","BioMechanical Engineering","","","",""
"uuid:20bd403a-4a5c-4c46-9daf-c25ac14a1d26","http://resolver.tudelft.nl/uuid:20bd403a-4a5c-4c46-9daf-c25ac14a1d26","Patient safety risk factors in minimally invasive surgery: A validation study","Rodrigues, S.P.; Ter Kuile, M.; Dankelman, J.; Jansen, F.W.","","2012","This study was conducted to adapt and validate a patient safety (PS) framework for minimally invasive surgery (MIS) as a first step in understanding the clinical relevance of various PS risk factors in MIS. Eight patient safety risk factor domains were identified using frameworks from a systems approach to patient safety. A questionnaire was drafted containing 34 questions. Three experts in the field of patient safety critically reviewed the questionnaire on clinical relevance and completeness. The questionnaire was distributed among known patient safety experts in person and also sent electronically. A total of 41 questionnaires were distributed and the response rate was 71%. The intraclass correlation coefficient was 0.42 representing moderate agreement. For seven of nine risk domains, Cronbach’s alpha was sufficient (??>?0.7). Mean scores of the risk domains showed the following order of influence on patient safety from high to low: surgeon’s experience [6.6, standard deviation (SD) 0.5], technical skills surgeon (6.6, SD 0.7), technology (5.9, SD 1.1), complications (5.9, SD 1.2), social interaction (5.0, SD 1.0), leadership surgeon (5.4, SD 1.2), blood loss (5.0, SD 1.2), length of surgery (5.0, SD 1.3), surgical team (4.9, SD 1.3), fallibility (4.9, SD 1.3), patient (4.5, SD 1.5), safety measures (4.4, SD 1.5), and finally environment(3.9, SD 1.5). This study is an initiative to give insight into clinical relevance of the maze of PS risk factors in MIS. All investigated risk domains were considered to be of noticeable influence on PS. Nevertheless, it is possible to prioritize various risk domains. In fact, experience and technical skills of the surgeon, technology, and complications are rated as the most important risk factors, closely followed by social interaction and leadership of the surgeon. Patient, safety measures, and environment are rated as the least important risk factors.","patient safety; risk factors; risk domains; MIS; laparoscopy; systems approach","en","journal article","Springer-Verlag","","","","","","","","Mechanical, Maritime and Materials Engineering","Biomechanical Engineering","","","",""
"uuid:81ad2fa1-212c-4eb4-8eb3-f186f39a23fb","http://resolver.tudelft.nl/uuid:81ad2fa1-212c-4eb4-8eb3-f186f39a23fb","The gap between clinical gaze and systematic assessment of movement disorders after stroke","Van der Krogt, H.J.M.; Meskers, C.G.M.; De Groot, J.H.; Klomp, A.; Arendzen, J.H.","","2012","Background: Movement disorders after stroke are still captured by clinical gaze and translated to ordinal scores of low resolution. There is a clear need for objective quantification, with outcome measures related to pathophysiological background. Neural and non-neural contributors to joint behavior should be separated using different measurement conditions (tasks) and standardized input signals (force, position and velocity). Methods: We reviewed recent literature for the application of biomechanical and/or elektromyographical (EMG) outcome measures under various measurement conditions in clinical research. Results: Since 2005, 36 articles described the use of biomechanical and/or EMG outcome measures to quantify post-stroke movement disorder. Nineteen of the articles strived to separate neural and non-neural components. Only 6 of the articles measured biomechanical and EMG outcome measures simultaneously, while applying active and passive tasks and multiple velocities. Conclusion: The distinction between neural and non-neural components to separately assess paresis, stiffness and muscle overactivity is not commonplace yet, while a large gap is to be bridged to attain reproducible and comparable results. Pathophysiologically clear concepts, substantiated with a comprehensive and concise measuring protocol will help professionals to identify and treat limiting factors in movement capabilities of poststroke patients","stroke; bomechanics; electromyography; outcome measures","en","journal article","Springer-Verlag","","","","","","","","Mechanical, Maritime and Materials Engineering","Biomechanical Engineering","","","",""
"uuid:a599e8a4-0daa-427e-b435-b84bd775549a","http://resolver.tudelft.nl/uuid:a599e8a4-0daa-427e-b435-b84bd775549a","Are Shoulders with A Reverse Shoulder Prosthesis Strong enough? A Pilot Study","Alta, T.D.W.; Veeger, H.E.J.; Janssen, T.W.J.; Willems, W.J.","","2012","Background It has been suggested that limited active ROM of reverse shoulder prostheses relates to lack of strength. However, the postoperative strength has not been quantified. Questions/purposes We therefore measured joint torques in patients with reverse shoulder prostheses and correlated torques with functional scores. Methods We recruited 33 patients (age, 72 ± 8 years) with a reverse prosthesis (37 shoulders, 21 primary and 16 revisions). We obtained Constant-Murley, DASH, and Simple Shoulder Test ([D]SST) scores, and performed two isokinetic protocols (abduction/adduction and external/internal rotation) at 60° per second. Minimum followup was 4 months (average, 23 months; range, 4–63 months). Results Twenty-three patients (24 shoulders; 13 primaries, 11 revisions) were able to perform at least one of the defined tasks. Mean abduction and adduction torques were 15 Nm ± 7 Nm and 16 Nm ± 10 Nm (19%–78% of normal shoulders). External and internal rotation tasks could be performed by only 13 patients (14 shoulders; nine primary, five revisions) generating 9 Nm ± 4 Nm and 8 Nm ± 3 Nm, respectively (13%–71% of normal shoulders). We found moderate correlations between Constant-Murley, DASH and (D)SST (D = Dutch translation) scores and abduction and external rotation. Conclusions Patients with a reverse prosthesis had reduced strength when compared with normal values reported in the literature (only 65% of patients could perform the protocol). This effect was greatest for external rotation and might explain clinical outcomes with which a moderately strong relationship was observed. Our observations suggest limited strength is a major factor in reduced ROM.","","en","journal article","Springer-Verlag","","","","","","","","Mechanical, Maritime and Materials Engineering","Biomechanical Engineering","","","",""
"uuid:af5f08dd-6486-497f-96f7-a7734939b3c9","http://resolver.tudelft.nl/uuid:af5f08dd-6486-497f-96f7-a7734939b3c9","Assessment of joystick and wrist control in hand-held articulated laparoscopic prototypes","Okken, L.M.; Chmarra, M.K.; Hiemstra, E.; Jansen, F.W.; Dankelman, J.","","2012","Various steerable instruments with flexible distal tip have been developed for laparoscopic surgery. The problem of steering such instruments, however, remains a challenge, because no study investigated which control method is the most suitable. This study was designed to examine whether thumb (joystick) or wrist control method is designated for prototypes of steerable instruments by means of motion analysis. Methods: Five experts and 12 novices participated. Each participant performed a needle-driving task in three directions with two prototypes (wrist and thumb) and a conventional instrument. Novices performed the tasks in three sessions, whereas experts performed one session only. The order of performing the tasks was determined by Latin squares design. Assessment of performance was done by means of five motion analysis parameters, a newly developed matrix for assigning penalty points, and a questionnaire. Results: The thumb-controlled prototype outperformed the wrist-controlled prototype. Comparison of the results obtained in each task showed that regarding penalty points, the up ? down task was the most difficult to perform. Conclusions: The thumb control is more suitable for steerable instruments than the wrist control. To avoid uncontrolled movements and difficulties with applying forces to the tissue while keeping the tip of the instrument at the constant angle, adding a ‘‘locking’’ feature is necessary. It is advisable not to perform the needle driving task in the up down direction","minimally invasive surgery; hand-held articulated instruments; motion analysis; needle-driving","en","journal article","Springer","","","","","","","","Mechanical, Maritime and Materials Engineering","Biomechanical Engineering","","","",""
"uuid:f1f3782a-98b3-4e9a-b79a-00b210aecee3","http://resolver.tudelft.nl/uuid:f1f3782a-98b3-4e9a-b79a-00b210aecee3","Shaft-Guidance for Flexible Endoscopes","Loeve, A.J.","Dankelman, J. (promotor)","2012","Flexible endoscopes (long, slender, flexible instruments with a camera and light at the distal end, having working channels to introduce flexible instruments) are used for diagnostic and therapeutic interventions inside the human digestive system and inside the abdomen. Though used for their flexibility, the flexibility of these instruments causes several difficulties during insertion and use. During insertion, flexible endoscopes can buckle and loop, which may hamper full insertion into the patient’s body. During therapeutic interventions, the flexible endoscope fails to provide stability for surgical instruments that are introduced through the flexible endoscope. In this thesis, firstly, the fundamental mechanical causes of the difficulties that accompany the use of flexible endoscopes are analysed. Next, an extensive, categorizing review explores the available and potentially suitable solutions to causes of the flexibility-induced difficulties in flexible endoscopy. The review suggests that passive guiding of the flexible endoscope shaft using guides with rigidity control is the most feasible solution. Three potentially suitable rigidity control concepts are selected and further investigated to quantitatively and qualitatively predict the maximally achievable flexural rigidity of these rigidity control mechanisms. The first investigated rigidity control mechanism (“Vacu-SL” mechanism) utilizes the flexural rigidity increase that is achieved by vacuuming foil tubes filled with small particles. The thesis proceeds with experiments on the influence of particle hardness, size, and shape on the flexural rigidity of vacuumed foil tubes filled with these particles. The experiments showed that the flexural rigidity increases with the hardness and irregularity of the particles and that there may be an optimal particle size in the low particle diameter region. Next, a mechanism using friction between a rubber tube, stainless steel cables, and a stainless steel spring ( “FORGUIDE mechanism”) is presented, as well as a mathematical model predicting the maximally achievable flexural rigidity of that mechanism. The results of that chapter suggest that there is great potential for improvement of the FORGUIDE mechanism and that this mechanism may very well provide sufficient support for flexible endoscopes. A chapter on the static friction between several kinds of rubber and several types of stainless steel cables aids to advise on how the flexural rigidity of the friction-based FORGUIDE mechanism can be increased by properly choosing the materials of the tube, cables, and spring. The third rigidity control mechanism ( “PlastoLock” mechanism) changes rigidity by heating and cooling a lactide-based polymer through its glass-transition. A feasibility study shows the great potential of this concept in terms of achievable flexural rigidity, miniaturization, and simplicity. Finally, the thesis presents a force analysis and a number of functional design considerations that should guide the further design of a new generation of flexible endoscopes with passively guided shafts. The discussion of the thesis advises on what rigidity control mechanisms are most likely to provide a proper solution for what application areas, and on what steps should be taken next to finally obtain a good solution to the current flexibility-induced difficulties in flexible endoscopy. It is concluded that the FORGUIDE mechanism and the PlastoLock mechanism are most suitable for application in flexible endoscopes for the gastrointestinal tract. These mechanisms are simple, provide high flexural rigidity (especially when considering their size), and may be applied in a very broad range of applications. Many improvements in existing applications and a broadening of the diagnostic and therapeutic possibilities in gastrointestinal health care may be achieved by further developing the investigated rigidity control mechanisms into fully functional guided instruments. Arjo Loeve, 2012","shaft-guidance; flexible endoscopy; colonoscopy; instrument design; endoscopy","en","doctoral thesis","","","","","","","","2012-05-29","Mechanical, Maritime and Materials Engineering","BioMechanical Engineering","","","",""
"uuid:87f43ef4-c94a-43f1-8c24-d487b387ebbb","http://resolver.tudelft.nl/uuid:87f43ef4-c94a-43f1-8c24-d487b387ebbb","Driver Steering Support Interfaces Near the Vehicle’s Handling Limits","Katzourakis, D.","Van der Helm, F.C.T. (promotor); Holweg, E.G.M. (promotor); Happee, R. (copromotor)","2012","The goal of this thesis is to propose steering support systems that can reduce the driver’s control effort, mental load and promote safety. The driver dictates the vehicle’s motion and the support should centralize him/her in the control loop; thus our design philosophy is to increase driver’s responsibility and support him/her in the sense of information rather than automation. Incarnating such an abstract theme into a concrete problem which can be methodologically solved in terms of engineering science, necessitates a milestone-oriented work approach. Thus, the path to realize this development is to systematically sub-divide the concept into distinct milestones allowing to embody this high-level idea into objectively assessed steering interfaces. This milestone-oriented approach can be divided into seven steps: i) Study the state-of-the-art driver support systems and identify the potential space for improvement. ii) Develop the means (driving simulators, vehicular instrumentation and data analysis methods) to aid the driver steering support interface research. iii) Study the driver steering interface without any support. iv) Utilize the gathered knowledge to develop steering support interfaces, assess them in simulation level, v) and adapt the simulation support controllers into real vehicles and test them. vi) Evaluate the influence of the support interface with the real vehicle results. vii) Based upon the assessment, make a road-map for the commercial implementation of the support interface; if it is fruitful promote its further development with ultimate goal the adoption into production vehicles. he aforementioned milestone-oriented approach has been followed for the development of the driver steering support interfaces presented in this thesis. The current summary substantiates the milestones into the distinct goal addressed in Chapters 2 – 7. The goal to develop the hardware and performance evaluation-control methods in order to engineer realistic haptic cues on the steering wheel of our driving simulator is addressed in Chapter 2. A relatively low-cost solution for hardware is deployed, consisting of a velocity-controlled three-phase brushless servomotor, whose high bandwidth control allows for a realistic representation of forces. To test the system, different inertia-spring-damper systems were simulated and evaluated in time and frequency domain. We concluded, that the designed system allowed reproduction of a large range of steering wheel dynamics and forces, comparable to those found in actual cars. Our target to systematically adjust the steering systems properties of the driving simulator so that it matches the steering feedback and vehicle response of a certain vehicle is addressed in Chapter 3. To do so, we employed the steering sensitivity and steering torque gradient, which are two important metrics describing on-centre vehicle dynamics response and steering feedback. We acquired the steering metrics of real cars during double-lane change tests and indicated the key parameters of the vehicle that determine these steering metrics. We instrumented and tested five modern passenger cars, and used a vehicle dynamics model to extract the metrics for multiple vehicular parameterizations (steering ratio, power assist level, etc.) and test speeds. Sensitivity analysis showed that steering sensitivity was mainly influenced by the components that determine the steering ratio whereas the steering torque gradient was also affected by power assist steering settings. By completing this work, we had the foundation to easily assess the realism of our simulated vehicles’ response as well as to easily adapt the vehicular settings to achieve a realistic steering feedback in our driving simulator. Lane departure appears relevant in 179,000 crashes per year and is related to the greatest number of fatal crashes; up to 7,500 fatal crashes per year in the United States. Infiniti predicts that if lane departure prevention (LDP) were fitted to all vehicles, some 12% of all road fatalities could be prevented annually. The problem is that although numerous studies have shown the potential of lane keeping and LDP systems, there are few studies related to their effects during emergency manoeuvres. Thus, Chapter 4 aims to investigate a road-departure prevention (RDP) system during an emergency manoeuvre. We present a driving-simulator experiment which evaluated various steering interfaces of a road-departure prevention (RDP) system in an emergency situation. The interfaces were: 1) haptic-feedback (HF) where the RDP provided advisory steering torque; 2) drive-by-wire (DBW) where the RDP automatically corrected the front-wheel angle; and 3) DBW & HF, which combined both setups. The RDP system intervenes by applying haptic (guidance) feedback torque and/or correcting the angle of the front wheels (drive-by-wire) when road departure is likely to occur. Thirty test drivers tried to avoid an obstacle (a pylon-confined area) while keeping the vehicle on the road. The results showed that HF without DBW had a significant impact on the measured steering torque, but no significant effect on steering-wheel angle or vehicle path. DBW prevented road departure and reduced mental workload, but lead to inadvertent human-initiated counter-steering. It was concluded that a low level of automation, in the form of HF, does not prevent road departures in an emergency situation. A high level of automation, on the other hand, is highly effective in preventing road departures. Chapter 5 has been divided into three parts (A, B, C), all related to real vehicle testing. Our goal to construct a versatile low-cost instrumentation suitable to be fitted on race cars and develop the methods for processing from raw measurements to user-friendly data suitable for driver behaviour studies is addressed in part A. Through a case study on driving behaviour, during the execution of high speed skid-pad manoeuvres, we could easily notice the markedly different driving behaviours between an expert and a novice driver. The experienced driver could learn quickly how to perform repeatable trajectories, unlike the novice driver. The consistently high performance of the expert driver was realized by relatively small correcting inputs (steering wheel angle, throttle). The experienced driver was able to quickly learn how to generate the correct inputs to the vehicle, to yield repeatable vehicle behaviour and consistently perform well. Our aim to investigate driver control actions during high speed cornering with a rear wheel drive vehicle is depicted in Chapter 5, part B. Six drivers were instructed to perform the fastest manoeuvres possible around a marked circle, while trying to retain control of the vehicle and constant turning radius. The data reveal that stabilization of the vehicle is achieved with a combination of steering and throttle regulation. The results show that the drivers used steering control to compensate for disturbances in yaw rate and sideslip angle. Vehicle accustomed drivers had the most consistent performance resulting in reduced variance of task metrics and control inputs. Our target to design controllers that can stabilize the vehicle as an expert driver would is approached in part C of Chapter 5. There, we present data of driver control commands and vehicle response during the execution of cornering manoeuvres at high sideslip angles (drifting) by an expert driver using a RWD vehicle. The data reveal that stabilization of the vehicle with respect to such cornering equilibria requires a combination of steering and throttle regulation. A four wheel vehicle model with nonlinear tire characteristics is introduced and the steady-state drifting conditions are solved numerically to derive the corresponding control inputs. A sliding mode control is proposed to stabilize the vehicle model with respect to steady-state drifting, using steering angle and drive torque inputs. The performance of the controller is validated in a high fidelity simulation environment; the controller can stabilize the vehicle similarly to an expert driver. We also conceptually describe how the proposed controller can motivate a driver steering support drifting interface in the by-wire sense. Our goal to objectively evaluate vehicular steering systems through detailed driver models is substantiated in Chapter 6. It presents a driver model that consists of a preview controller part that responds to visual feedback and a neuromuscular component that reacts to force-feedback. The developed model is sensitive to steering wheel systems with different dynamics, and can predict both goal-directed steering wheel movements, as well as neuromuscular feedback. To provide evidence, we simulated different parameterizations of a steering system and tested them in conjunction with the developed driver model. We concluded that the developed model could predict the expected response for different steering setups. Our milestone goal to propose haptic steering wheel support when driving near the vehicle’s handling limit (Haptic Support Near the Limits: HSNL) is addressed in Chapter 7. The rationale behind the HSNL, derives from the vehicle’s property to reduce the steering “stiffness” (the steering feedback torque as a function of the steering wheel angle) before the vehicle reaches its handling limits and starts to understeer. The HSNL exaggerates the reduction of the steering “stiffness” and makes it profound to the driver, so he/she avoids excessive steering angle inputs which will result in increased tire slip and consequently lateral force loss. Chapter 7 is divided into two parts (A, B). Part A of Chapter 7 studies the influence of the HSNL in (a) driver-in-the-loop simulation and in (b) real track testing with a vehicle (Opel Astra G/B) equipped with a variable steering feedback torque system. In the simulator study (a) 25 drivers attempted to achieve maximum velocity, on a dry skid-pad while trying to retain control of the simulated vehicle parameterized as the Astra. In (b) 17 drivers attempted to achieve maximum velocity, around a wet skid-pad while trying to retain control of the Astra. Driving aids (ABS and traction control) were disabled during testing. Both the driving simulator and the real vehicle tests led to the conclusion that HSNL assisted the test subjects to drive closer to the designated path while achieving effectively the same speed. In the presence of HSNL, the drivers operated the tires in smaller slip angles and hence avoided saturation the front wheels’ lateral forces and excessive understeer. Finally, the support reduced their mental and physical demand. Part B of Chapter 7, studies the influence of HSNL during high speed cornering in a test-track. 17 test subjects drove around a narrow-twisting tarmac circuit, the aforementioned Opel Astra equipped with a variable steering feedback torque system. The drivers were instructed to achieve maximum velocity through corners, while receiving haptic steering feedback cues related to the vehicle’s cornering potentials. Driving aids (ABS and traction control) were disabled during testing. The test-track tests led to the conclusion that HSNL reduced drivers’ mental and physical demand. One of the primal goals of automotive manufacturers is to reduce the driver’s mental and control effort (c.f. Chapter 7); the work that will be presented in this thesis revealed that steering support near the vehicle’s handling limits can reduce the drivers’ mental and physical demand and can potentially promote safety. We can therefore conclude that certain of the developed support interfaces can be implemented into production vehicles.","Automotive control; Double-lane change experiments; Driver modelling and behaviour analysis; Driving at the Handling Limits; Driving simulation; drive-by-wire; Emergency manoeuvre; Haptic Steering Support; Haptic-feedback; shared control; High Speed Driving; Human Machine Interface; Lateral Stability Limit handling; Racecar instrumentation; Road-departure prevention; RWD drifting controller; Steady-state; Steering assist; Steering force-feedback; Steering sensitivity & torque gradient Steering system modelling; Test-track Driving; Torque hysteresis loop","en","doctoral thesis","","","","","","","","2012-06-12","Mechanical, Maritime and Materials Engineering","BioMechanical Engineering","","","",""
"uuid:3381b881-c668-4dc4-8107-627b2e222c10","http://resolver.tudelft.nl/uuid:3381b881-c668-4dc4-8107-627b2e222c10","Efficiency of voluntary opening hand and hook prosthetic devices, 24 years of development?","Smit, G.; Bongers, R.M.; Van der Sluis, C.K.; Plettenburg, D.H.","","2012","Quantitative data on the mechanical performance of upper-limb prostheses are very important in prostheses development and selection. The primary goal of this study was to objectively evaluate the mechanical performance of adult-size voluntary opening (VO) prosthetic terminal devices and select the best tested device. A second goal was to see whether VO devices have improved in the last two decades. Nine devices (four hooks and five hands) were quantitatively tested (Hosmer model 5XA hook, Hosmer Sierra 2 Load VO hook, RSL Steeper Carbon Gripper, Otto Bock model 10A60 hook, Becker Imperial hand, Hosmer Sierra VO hand, Hosmer Soft VO hand, RSL Steeper VO hand, Otto Bock VO hand). We measured the pinch forces, activation forces, cable displacements, mass, and opening span and calculated the work and hysteresis. We compared the results with data from 1987. Hooks required lower activation forces and delivered higher pinch forces than hands. The activation forces of several devices were very high. The pinch forces of all tested hands were too low. The Hosmer model 5XA hook with three bands was the best tested hook. The Hosmer Sierra VO hand was the best tested hand. We found no improvements in VO devices compared with the data from 1987.","body powered; efficiency; hysteresis; prosthetic design; prosthetic evaluation; prosthetic hand; prosthetics; qualitative testing; upper limb; voluntary opening","en","journal article","U.S. Department of Veterans Affairs","","","","","","","","Mechanical, Maritime and Materials Engineering","BioMechanical Engineering","","","",""
"uuid:91680790-5545-4505-a85d-d1aaf9086cf8","http://resolver.tudelft.nl/uuid:91680790-5545-4505-a85d-d1aaf9086cf8","Resuscitation of very preterm infants with 30% vs. 65% oxygen at birth: Study protocol for a randomized controlled trial","Rook, D.; Schierbeek, H.; Van der Eijk, A.C.; Longini, M.; Buonocore, G.; Vento, M.; Van Goudoever, J.B.; Vermeulen, M.J.","","2012","Background Resuscitation at birth with 100% oxygen is known to increase the oxidative burden with concomitant deleterious effects. Although fractions of inspired oxygen (FiO2)?100% are widely used in preterm infants, starting resuscitation at a (too) low FiO2 may result in hypoxia. The objective of this study is to compare the safety and efficacy of resuscitating very preterm infants with an initial FiO2 of 30% versus 65%. Methods/design In this double-blind, randomized controlled trial, 200 very preterm infants with a gestational age?32 weeks will be randomized to start resuscitation after birth with either 30% or 65% oxygen. The FiO2 will be adjusted based on oxygen saturation measured by pulse oximetry (SpO2) and pulse rate (which should be over 100 beats per minute) in order to achieve a target SpO2 of 88–94% at 10 min of life. The FiO2 and pulse oximetry data will be continuously recorded. The primary outcome is survival without bronchopulmonary dysplasia, as assessed by a physiological test at 36 weeks postmenstrual age. The secondary outcomes include the time to achieve SpO2?>?88%, Apgar score at 5 min, cumulative O2 exposure, oxidative stress (as determined by glutathione synthesis and oxidative stress markers), retinopathy of prematurity, brain injury and neurodevelopmental outcome at 2 years of age. This study will provide insight into determining the appropriate initial FiO2 to start resuscitation of very preterm infants.","preterm infants; resuscitation; oxygen; bronchopulmonary dysplasia; oxidative stress; glutathione synthesis","en","journal article","BioMed Central","","","","","","","","Mechanical, Maritime and Materials Engineering","Biomechanical Engineering","","","",""
"uuid:e7af790a-290e-419b-b5e3-9e167a694bce","http://resolver.tudelft.nl/uuid:e7af790a-290e-419b-b5e3-9e167a694bce","Characterization of porous TiO2 surfaces formed on 316L stainless steel by plasma electrolytic oxidation for stent applications","Huan, Z.; Fratila-Apachitei, L.E.; Apachitei, I.; Duszczyk, J.","","2012","In this study, a porous oxide layer was formed on the surface of 316L stainless steel (SS) by combining Ti magnetron sputtering and plasma electrolytic oxidation (PEO) with the aim to produce a polymer-free drug carrier for drug eluting stent (DES) applications. The oxidation was performed galvanostatically in Na3PO4 electrolyte. The surface porosity, average pore size and roughness varied with PEO treatment duration, and under optimum conditions, the surface showed a porosity of 7.43%, an average pore size of 0.44 ?m and a roughness (Ra) of 0.34 ?m. The EDS analyses revealed that the porous layer consisted of Ti, O and P. The cross-sectional morphology evidenced a double-layer structure, with a porous titania surface and an un-oxidized dense Ti film towards the interface with 316L SS. After the PEO treatment, wettability and surface free energy increased significantly. The results of the present study confirm the feasibility of forming a porous TiO2 layer on stainless steel by combining sputtering technology and PEO. Further, the resultant porous oxide layer has the potential to be used as a drug carrier for DES, thus avoiding the complications associated with the polymer based carriers.","drug eluting stent; plasma electrolytic oxidation; titanium oxide layer; stainless steel; surface porosity","en","journal article","MDPI","","","","","","","","Mechanical, Maritime and Materials Engineering","Biomechanical Engineering","","","",""
"uuid:030d309f-2bb3-4921-8f6c-6f110eff48d0","http://resolver.tudelft.nl/uuid:030d309f-2bb3-4921-8f6c-6f110eff48d0","Kinematics and early migration in single-radius mobile- and fixed-bearing total knee prostheses","Wolterbeek, N.; Garling, E.H.; Mertens, B.J.; Nelissen, R.G.H.H.; Valstar, E.R.","","2012","Background The mobile-bearing variant of a single-radius design is assumed to provide more freedom of motion compared to the fixed-bearing variant because the insert does not restrict the natural movements of the femoral component. This would reduce the contact stresses and wear which in turn may have a positive effect on the fixation of the prosthesis to the bone and thereby decreases the risk for loosening. The aim of this study was to evaluate early migration of the tibial component and kinematics of a mobile-bearing and fixed-bearing total knee prosthesis of the same single-radius design. Methods Twenty Triathlon single-radius posterior-stabilized knee prostheses were implanted (9 mobile-bearing and 11 fixed-bearing). Fluoroscopy and roentgen stereophotogrammetric analysis (RSA) were performed 6 and 12 months post-operatively. Findings The 1 year post-operative RSA results showed considerable early migrations in 3 out of 9 mobile-bearing patients and 1 out of 11 fixed-bearing patients. The range of knee flexion was the same for the mobile-bearing and fixed-bearing group. The mobile insert was following the femoral component during motion. Interpretation Despite the mobile insert following the femoral component during motion, and therefore performing as intended, no kinematic advantages of the mobile-bearing total knee prosthesis were seen. The fixed-bearing knee performed as good as the mobile-bearing knee and maybe even slightly better based on less irregular kinematics and less early migrations.","mobile-bearing; single-radius; migration; kinematics; fluoroscopy","en","journal article","Elsevier","","","","","","","","Mechanical, Maritime and Materials Engineering","Biomechanical Engineering","","","",""
"uuid:52ac43ed-3573-47e4-b02e-b5ab6809596a","http://resolver.tudelft.nl/uuid:52ac43ed-3573-47e4-b02e-b5ab6809596a","Implications of the law on video recording in clinical practice","Henken, K.R.; Jansen, F.W.; Klein, J.; Stassen, L.P.S.; Dankelman, J.; Van den Dobbelsteen, J.J.","","2012","Background Technological developments allow for a variety of applications of video recording in health care, including endoscopic procedures. Although the value of video registration is recognized, medicolegal concerns regarding the privacy of patients and professionals are growing. A clear understanding of the legal framework is lacking. Therefore, this research aims to provide insight into the juridical position of patients and professionals regarding video recording in health care practice. Methods Jurisprudence was searched to exemplify legislation on video recording in health care. In addition, legislation was translated for different applications of video in health care found in the literature. Results Three principles in Western law are relevant for video recording in health care practice: (1) regulations on privacy regarding personal data, which apply to the gathering and processing of video data in health care settings; (2) the patient record, in which video data can be stored; and (3) professional secrecy, which protects the privacy of patients including video data. Practical implementation of these principles in video recording in health care does not exist. Conclusion Practical regulations on video recording in health care for different specifically defined purposes are needed. Innovations in video capture technology that enable video data to be made anonymous automatically can contribute to protection for the privacy of all the people involved.","health care; law; patient safety; privacy; surgery; video","en","journal article","Springer","","","","","","","","Mechanical, Maritime and Materials Engineering","Biomechanical Engineering","","","",""
"uuid:b970b831-d92f-49fe-8394-69acce9a5679","http://resolver.tudelft.nl/uuid:b970b831-d92f-49fe-8394-69acce9a5679","Relationship Between Distal and Proximal Neoplasia","Dodou, D.; De Winter, J.C.F.","","2012","","","en","journal article","Springer","","","","","","","","Mechanical, Maritime and Materials Engineering","Biomechanical Engineering","","","",""
"uuid:795fa8f5-84a0-4673-810c-a8265e29791c","http://resolver.tudelft.nl/uuid:795fa8f5-84a0-4673-810c-a8265e29791c","Foot placement in robotic bipedal locomotion","De Boer, T.","Van der Helm, F.C.T. (promotor)","2012","Human walking is remarkably robust, versatile and energy-efficient: humans have the ability to handle large unexpected disturbances, perform a wide variety of gaits and consume little energy. A bipedal walking robot that performs well on all of these aspects has not yet been developed. Some robots are versatile, others are energy-efficient, and none are robust since all robots often lose balance. This lack of performance impedes their applicability in daily life. Also, it indicates that the fundamental principles of walking are not adequately understood. The goal of this thesis is to increase the understanding of the mechanics and control of bipedal locomotion and thereby increase the performance of robotic bipedal locomotion. This increased understanding will also be useful for the development of robotic devices that can help people with a decreased ambulatory ability or that can augment the performance of able-bodied persons. Bipedal locomotion is in essence about the ability to maintain control over the position and velocity of the body's center of mass (CoM). This requires controlling the forces that act on the CoM through the foot. The contact forces between the foot and the ground can be manipulated to some extent through ankle torques or upper body motions, but are mostly determined by the location of the foot relative to the CoM. The limited influence that ankle torques and upper body motions have on the contact forces and consequently on the CoM is best illustrated when one tries to remain balanced on one foot without taking a step. When slightly perturbed, balance is quickly lost and a step must be taken to prevent a fall. This demonstrates that balance control in walking relies on adequate control of foot placement (i.e., the location and timing of a step), which therefore is our main focus in the control of robotic gait. The focus on foot placement control is different from other popular control approaches in robotics. In ZMP-based control, one typically adjusts the robot's state to achieve a predefined foot placement. In Limit Cycle Walking, passive system dynamics mostly determine foot placement. This thesis presents foot placement strategies that can be adapted both in step time and step location, are an explicit function between the initial robot state and the desired future robot state, and are computationally relatively inexpensive to allow for real-time application on the robot. The contributions of this thesis to bipedal walking research are: a theoretical framework, simulation studies, and prototype experiments. These contributions provide insight in how foot placement control can improve the robustness, versatility and energy-efficiency of bipedal gait. Regarding robustness, this thesis introduces the theoretical framework of capturability to analyze or synthesize actions that can prevent a fall. Fall avoidance is analyzed by considering N-step capturability: the system's ability to eventually come to a stop without falling by taking N or fewer steps, given its dynamics and actuation limits. Low-dimensional gait models are used to approximate capturability of complex systems. It is shown how foot placement, ankle torques and upper body motions affect the CoM motion and contribute to N-step capturability. N-step capture regions can be projected on the floor: these define where the system can step to remain capturable. The size of these regions can be used as a robustness metric. Regarding versatility, this thesis derives foot placement strategies that enable the system to evolve from the initial state to a desired future state in a minimal number of steps. Simulations on simple gait models demonstrate how these foot placement strategies can be used to change walking speed or walking direction. Regarding energy-efficiency, we learn that simple gait models demonstrate human-like foot placement strategies in response to a stumble when optimizing for either one of the following cost measures for foot placement: peak torque, power, impulse, and torque divided by time. For robotic control, these results indicate that actuator limitations should be taken into account in the execution and planning of foot placement strategies. Regarding robot experiments, we integrate the concepts from the capturability framework into the control of a robot. The low-dimensional gait models are shown to be useful for the robust control of a complex robot. The model takes only the CoM dynamics with respect to the center of pressure (CoP) into account. The application of this model together with force-based control strategies lead to robust robot behavior: upright postural balance is maintained when the robot is pushed and one of the feet is placed on a moving platform. Successful application is also shown for single legged balancing with compensatory stepping to regain balance after a push and (simulated) walking. The main conclusion is that analyzing walking control as a combination of decoupled and low dimensional control tasks allows us to derive simple and useful control heuristics for the control of a complex bipedal robot. We find that the key control task is foot placement, which mostly determines the system's CoM motion by defining possible CoP locations. We can approximate the set of possible foot placement strategies that will not lead to a fall. This set specifies the bounds to which foot placement strategies can be adjusted to achieve more versatile or energy-efficient behavior.","robot; humanoid; force control; capture point","en","doctoral thesis","","","","","","","","2012-02-13","Mechanical, Maritime and Materials Engineering","BioMechanical Engineering","","","",""
"uuid:77c42d1d-d9ab-409d-9f7d-abf72433cfc6","http://resolver.tudelft.nl/uuid:77c42d1d-d9ab-409d-9f7d-abf72433cfc6","Haptic shared control: Smoothly shifting control authority?","Abbink, D.A.; Mulder, M.; Boer, E.R.","","2012","Literature points to persistent issues in humanautomation interaction, which are caused either when the human does not understand the automation or when the automation does not understand the human. Design guidelines for human-automation interaction aim to avoid such issues and commonly agree that the human should have continuous interaction and communication with the automation system and its authority level and should retain final authority. This paper argues that haptic shared control is a promising approach to meet the commonly voiced design guidelines for human-automation interaction, especially for automotive applications. The goal of the paper is to provide evidence for this statement, by discussing several realizations of haptic shared control found in literature. We show that literature provides ample experimental evidence that haptic shared control can lead to short-term performance benefits (e.g., faster and more accurate vehicle control; lower levels of control effort; reduced demand for visual attention). We conclude that although the continuous intuitive physical interaction inherent in haptic shared control is expected to reduce long-term issues with humanautomation interaction, little experimental evidence for this is provided. Therefore, future research on haptic shared control should focus more on issues related to long-term use such as trust, overreliance, dependency on the system, and retention of skills","automation; humanmachine interface; haptic guidance; shared control; neuromuscular identification; levels of automation; force feedback","en","journal article","Springer-Verlag","","","","","","","","Mechanical, Maritime and Materials Engineering","Department of Biomechanical Engineering","","","",""
"uuid:7be14e91-5e19-4d82-8da4-28111fd447de","http://resolver.tudelft.nl/uuid:7be14e91-5e19-4d82-8da4-28111fd447de","Micro-electromechanical system","Tolou, N.; Herder, J.L.","","2012","Micro-electromechanical system (MEMS) comprising a substrate or substrate parts, and a compliant first segment or segments within the substrate or substrate parts with a predefined positive stiffness, wherein the first segment or segments is or are statically balanced. This is embodied by applying a second segment or segments within the substrate or substrate parts that provide a balancing force to the first segment or segments so as to counteract at least in a predefined working range of the first segment or segments the said predefined positive stiffness.","","en","patent","European Patent Office","","","","","","","","Mechanical, Maritime and Materials Engineering","Biomechanical Engineering","","","",""
"uuid:62c424e4-65d5-4091-aba0-004db25d1bb3","http://resolver.tudelft.nl/uuid:62c424e4-65d5-4091-aba0-004db25d1bb3","Shoulder load during handcycling at different incline and speed conditions","Arnet, U.; Van Drongelen, S.; Van de Woude, L.H.V.; Veeger, H.E.J.","","2012","Background The manual wheelchair user population experiences a high prevalence of upper-limb injuries, which are related to a high load on the shoulder joint during activities of daily living, such as handrim wheelchair propulsion. An alternative mode of propulsion is handcycling, where lower external forces are suggested to be applied to reach the same power output as in handrim wheelchair propulsion. This study aimed to quantify glenohumeral contact forces and muscle forces during handcycling and compare them to previous results of handrim wheelchair propulsion. Methods Ten able-bodied men propelled the handbike on a treadmill at two inclines (1% and 4% with a velocity of 1.66 m/s) and two speed conditions (1.39 and 1.94 m/s with fixed power output). Three-dimensional kinematics and kinetics were obtained and used as input for a musculoskeletal model of the arm and shoulder. Output variables were glenohumeral contact forces and forces of important shoulder muscles. Findings The highest mean and peak glenohumeral contact forces occurred at 4% incline (420 N, 890 N respectively). The scapular part of the deltoideus, the triceps and the trapezius produced the highest force. Interpretation Due to the circular movement and the continuous force application during handcycling, the glenohumeral contact forces, as well as the muscle forces were clearly lower compared to the results in the existing literature on wheelchair propulsion. These findings prove the assumption that handcycling is mechanically less straining than handrim wheelchair propulsion, which may help preventing overuse to the shoulder complex.","handbike; shoulder load; glenohumeral contact force; muscle force; musculoskeletal model; cyclic exercise","en","journal article","Elsevier","","","","","","","","Mechanical, Maritime and Materials Engineering","Biomechanical Engineering","","","",""
"uuid:b8382fbc-e2ae-4630-9cd5-a985a79952fc","http://resolver.tudelft.nl/uuid:b8382fbc-e2ae-4630-9cd5-a985a79952fc","Underactuated grasper","Steutel, P.; Kragten, G.A.; Herder, J.L.","","2012","","","en","patent","European Patent Office","","","","","","","","Mechanical, Maritime and Materials Engineering","Biomechanical Engineering","","","",""
"uuid:fd4b760b-ce38-49e0-9714-48824e6945f8","http://resolver.tudelft.nl/uuid:fd4b760b-ce38-49e0-9714-48824e6945f8","Modeling of a compliant joint in a Magnetic Levitation System for an endoscopic camera","Simi, M.; Tolou, N.; Valdastri, P.; Herder, J.L.; Menciassi, A.; Dario, P.","","2012","A novel compliant Magnetic Levitation System (MLS) for a wired miniature surgical camera robot was designed, modeled and fabricated. The robot is composed of two main parts, head and tail, linked by a compliant beam. The tail module embeds two magnets for anchoring and manual rough translation. The head module incorporates two motorized donut-shaped magnets and a miniaturized vision system at the tip. The compliant MLS can exploit the static external magnetic field to induce a smooth bending of the robotic head (0–80º), guaranteeing a wide span tilt motion of the point of view. A nonlinear mathematical model for compliant beam was developed and solved analytically in order to describe and predict the trajectory behaviour of the system for different structural parameters. The entire device is 95mm long and 12.7mm in diameter. Use of such a robot in single port or standard multiport laparoscopy could enable a reduction of the number or size of ancillary trocars, or increase the number of working devices that can be deployed, thus paving the way for multiple view point laparoscopy.","OA-Fund TU Delft","en","journal article","Copernicus Publications","","","","","","","","Mechanical, Maritime and Materials Engineering","Biomechanical Engineering","","","",""
"uuid:63205b16-dbe3-4c49-b5d3-cf5ef90d54ee","http://resolver.tudelft.nl/uuid:63205b16-dbe3-4c49-b5d3-cf5ef90d54ee","Indirect measurement of pinch and pull forces at the shaft of laparoscopic graspers","Van den Dobbelsteen, J.J.; Lee, R.A.; Van Noorden, M.; Dankelman, J.","","2012","The grasping instruments used in minimally invasive surgery reduce the ability of the surgeon to feel the forces applied on the tissue, thereby complicating the handling of the tissue and increasing the risk of tissue damage. Force sensors implemented in the forceps of the instruments enable accurate measurements of applied forces, but also complicate the design of the instrument. Alternatively, indirect estimations of tissue interaction forces from measurements of the forces applied on the handle are prone to errors due to friction in the linkages. Further, the force transmission from handle to forceps exhibits large nonlinearities, so that extensive calibration procedures are needed. The kinematic analysis of the grasping mechanism and experimental results presented in this paper show that an intermediate solution, force measurements at the shaft and rod of the grasper, enables accurate measurements of the pinch and pull forces on tissue with only a limited number of calibration measurements. We further show that the force propagation from the shaft and rod to the forceps can be approximated by a linear two-dimensional function of the opening angle of the grasper and the force on the rod.","health care; human performance; medical simulation; tactile device","en","journal article","Springer","","","","","","","","Mechanical, Maritime and Materials Engineering","Biomechanical Engineering","","","",""
"uuid:bcd7ce58-2804-4242-873c-e219a8ebcb5f","http://resolver.tudelft.nl/uuid:bcd7ce58-2804-4242-873c-e219a8ebcb5f","Method of steering a vehicle","Della Penna, M.; Van Passen, M.M.; Abbink, D.A.; Mulder, M.","","2011","Vehicle and method of steering such a vehicle, wherein the vehicle has a steering wheel and steerable driving wheels and a transfer system for converting steering wheel actions to a steering angle of the steerable driving wheels, and wherein the transfer system is provided with a predefined stiffness value that determines said transfer system's transfer characteristic pertaining to a required amount of torque that is required in turning the steering wheel to effect a desired steering angle of the steerable driving wheels. In this vehicle and method of steering this vehicle, an area in front of the vehicle is monitored for detecting objects that the vehicle may hit when it continues its current path of movement. Depending on the detection of any such object the stiffness value of the transfer system is reduced so as to ease turning the steering wheel for effecting the desired steering angle of the steerable driving wheels.","","en","patent","European Patent Office","","","","","","","","Mechanical, Maritime and Materials Engineering","Biomechanical Engineering","","","",""
"uuid:37411804-13fa-4e3b-94ed-1903741625ef","http://resolver.tudelft.nl/uuid:37411804-13fa-4e3b-94ed-1903741625ef","Skill acquisition of manual wheelchair propulsion: Initial motor learning","Vegter, R.J.K.; Lamoth, C.J.; Veeger, H.E.J.; De Groot, S.; Van der Woude, L.H.V.","","2011","Changes in propulsion technique due to motor learning might account for a higher mechanical efficiency (ME, the ratio of internal power over external power). The changes in ME and propulsion technique were studied in a learning experiment, three times a week for eight minutes, with nine able-bodied subjects, simulating early rehabilitation. Instrumented wheels measured three-dimensional forces and torques on the handrim. During practice peak torques were reduced, work per cycle increased, while push frequency decreased, at a stable power output and speed of the treadmill. Over the three weeks of practice propulsion technique kept changing in combination with an increase of ME. Results suggest skill acquisition because of motor learning. The rise in ME seems logically related to propulsion technique, but is not yet fully understood. More insight in motor learning and skill acquisition will contribute to understanding and optimizing rehabilitation strategies in the light of wheelchair provision in early rehabilitation.","","en","conference paper","EDP Sciences","","","","","","","","Mechanical, Maritime and Materials Engineering","Biomechanical Engineering","","","",""
"uuid:c57e9013-5e83-4af3-bb7a-f52f7271129b","http://resolver.tudelft.nl/uuid:c57e9013-5e83-4af3-bb7a-f52f7271129b","The Relationship Between Distal and Proximal Colonic Neoplasia: A Meta-Analysis","Dodou, D.; De Winter, J.C.F.","","2011","To investigate the association between proximal colonic neoplasia and distal lesions as a function of the lesion type. The extent to which health, demographic, and study characteristics moderate this association was also examined.","cancer screening; colorectal cancer; systematic review","en","journal article","Springer","","","","","","","","Mechanical, Maritime and Materials Engineering","Biomechanical Engineering","","","",""
"uuid:eaf340c0-5798-43ab-bc9d-e27c6dcd4e94","http://resolver.tudelft.nl/uuid:eaf340c0-5798-43ab-bc9d-e27c6dcd4e94","Accelerating reinforcement learning on a robot by using subgoals in a hierarchical framework","Van Vliet, B.; Caarls, W.; Schuitema, E.; Jonker, P.P.","","2011","Reinforcement learning is a way to learn control tasks by trial and error. Even for simple motor control tasks, however, this can take a long time. We can speed up learning by using prior knowledge, but this is not always available, especially for an autonomous agent. One way to add limited prior knowledge is to use subgoals, defining points that the controller should aim for on the way to reaching the real goal. In this study, we use the MAXQ hierarchical framework to specify subgoals. This decreased the learning time by a factor two on a robot leg step-up task and we show that tests on a real robot give similar results. The worse end performance that is a result of the reduced solution space can be partially canceled out by hierarchical greedy execution. To our knowledge, this is the first time the MAXQ framework is applied to a real robot.","","en","conference paper","","","","","","","","","Mechanical, Maritime and Materials Engineering","Biomechanical Engineering","","","",""
"uuid:88e266af-cddd-4659-bf18-3a45fc65276b","http://resolver.tudelft.nl/uuid:88e266af-cddd-4659-bf18-3a45fc65276b","The effect of ankle foot orthosis stiffness on the energy cost of walking: A simulation study","Bregman, D.J.J.; Van der Krogt, M.M.; De Groot, V.; Harlaar, J.; Wisse, M.; Collins, S.H.","","2011","Background In stroke and multiple sclerosis patients, gait is frequently hampered by a reduced ability to push-off with the ankle caused by weakness of the plantar-flexor muscles. To enhance ankle push-off and to decrease the high energy cost of walking, spring-like carbon-composite Ankle Foot Orthoses are frequently prescribed. However, it is unknown what Ankle Foot Orthoses stiffness should be used to obtain the most efficient gait. The aim of this simulation study was to gain insights into the effect of variation in Ankle Foot Orthosis stiffness on the amount of energy stored in the Ankle Foot Orthosis and the energy cost of walking. Methods We developed a two-dimensional forward-dynamic walking model with a passive spring at the ankle representing the Ankle Foot Orthosis and two constant torques at the hip for propulsion. We varied Ankle Foot Orthosis stiffness while keeping speed and step length constant. Findings We found an optimal stiffness, at which the energy delivered at the hip joint was minimal. Energy cost decreased with increasing energy storage in the ankle foot orthosis, but the most efficient gait did not occur with maximal energy storage. With maximum storage, push-off occurred too late to reduce the impact of the contralateral leg with the floor. Maximum return prior to foot strike was also suboptimal, as push-off occurred too early and its effects were subsequently counteracted by gravity. The optimal Ankle Foot Orthosis stiffness resulted in significant push-off timed just prior to foot strike and led to greater ankle plantar-flexion velocity just before contralateral foot strike. Interpretation Our results suggest that patient energy cost might be reduced by the proper choice of Ankle Foot Orthosis stiffness.","gait; stroke; multiple sclerosis; biomechanics; orthoses; AFO","en","journal article","Elsevier","","","","","","","","Mechanical, Maritime and Materials Engineering","Biomechanical Engineering","","","",""
"uuid:2f74b2f5-974e-4f72-9de5-ae5f8a96efee","http://resolver.tudelft.nl/uuid:2f74b2f5-974e-4f72-9de5-ae5f8a96efee","Development of a comprehensive musculoskeletal model of the shoulder and elbow","Asadi Nikooyan, A.; Veeger, H.E.J.; Chadwick, E.K.J.; Praagman, M.; Van der Helm, F.C.T.","","2011","The Delft Shoulder and Elbow Model (DSEM), a musculoskeletal model of the shoulder and elbow has been extensively developed since its introduction in 1994. Extensions cover both model structures and anatomical data focusing on the addition of an elbow part and muscle architecture parameters. The model was also extended with a new inverse-dynamics optimization cost function and combined inverse-forward-dynamics models. This study is an update on the developments of the model over the last decade including a qualitative validation of the different simulation architectures available in the DSEM. To validate the model, a dynamic forward flexion motion was performed by one subject, of which the motion data and surface EMG-signals of 12 superficial muscles were measured. Patterns of the model-predicted relative muscle forces were compared with their normalized EMG-signals. Results showed relatively good agreement between forces and EMG (mean correlation coefficient of 0.66). However, for some cases, no force was predicted while EMG activity had been measured (false-negatives). The DSEM has been used and has the potential to be used in a variety of clinical and biomechanical applications.","shoulder; elbow; musculoskeletal model; inverse and forward dynamics; validation; muscle force; EMG","en","journal article","Springer","","","","","","","","Mechanical, Maritime and Materials Engineering","Biomechanical Engineering","","","",""
"uuid:29fce0ab-5b53-4d59-9688-ad5118e04a5b","http://resolver.tudelft.nl/uuid:29fce0ab-5b53-4d59-9688-ad5118e04a5b","Architecture-Centric Design: Modeling and Applications to Control Architecture Generation","Alvarez Cabrera, A.A.","Tomiyama, T. (promotor)","2011","Design activities, including control design, are becoming increasingly difficult due to a corresponding increase in product and product development complexity. Model-based (or driven) engineering, development and design have become common concepts related to modern complex product development practices. However, it is argued here that currently such approaches only remain successful within a domain-specific context. This work has as main contributions the analysis of desirable characteristics and a proposal for a model which can effectively support model-based development in general (i.e., not only within specific domains), coined here as “architecture-centric”. Another contribution of this work is an intensive review (though hardly complete) on existing tools and methods related to the model-based development of control architectures for complex mechatronic systems. Synthesis, analysis, and verification of the proposals are based on the generic case of control (architecture) design, which represents most of the relevant characteristics and problems in current design practices for complex mechatronic products. Besides the main contributions above, the case studies for control architecture generation provide an overview of the control design process, as well as additional insight into the required characteristics of the model and possible methods to effectively implement it and use it in the context of industrial product development.","design method; architecture; mechatronics; control; methods; model-based; design model","en","doctoral thesis","VSSD","","","","","","","","Mechanical, Maritime and Materials Engineering","BioMechanical Engineering","","","",""
"uuid:a2213934-6648-4951-aa32-ead994deea6d","http://resolver.tudelft.nl/uuid:a2213934-6648-4951-aa32-ead994deea6d","On the way to pole position: The effect of tire grip on learning to drive a racecar","De Groot, S.; De Winter, J.C.F.","","2011","Racecar drivers could benefit from new training methods for learning to drive fast lap times. Inspired by the learning-from-errors principle, this simulator-based study investigated the effect of the tire-road friction coefficient on the training effectiveness of a car racing task. Three groups of 15 inexperienced racecar drivers (low grip (LG), 66% of normal grip; normal grip (NG); high grip (HG), 150% of normal grip) completed four practice sessions of 10 minutes in a Formula 3 car on an oval track of 800 m. After the practice sessions, two retention sessions followed: a retention session with normal grip in a Formula 3 car and another retention session with a Formula 1 car. The results showed that LG was significantly slower than HG in the first retention session. Furthermore, LG reported a higher confidence and lower frustration than NG and HG after each of the two retention sessions. In conclusion, practicing with low grip, as compared to practicing with normal or high grip, resulted in increased confidence but slower lap times.","learning from errors; simulator-based training; racecar driving; learning; retention; transfer; task difficulty","en","conference paper","IEEE","","","","","","","","Mechanical, Maritime and Materials Engineering","BioMechanical Engineering","","","",""
"uuid:ecd28765-1f4f-4625-9b22-0c2f30187b0e","http://resolver.tudelft.nl/uuid:ecd28765-1f4f-4625-9b22-0c2f30187b0e","Preparing drivers for dangerous situations: A critical reflection on continuous shared control","De Winter, J.C.F.; Dodou, D.","","2011","Shared control (also known as continuous haptic guidance or haptically active controls) has recently been introduced in car driving. With shared control, the driver receives continuous force feedback on the gas pedal or steering wheel, so that human and machine conduct the driving task simultaneously. Experiments in driving simulators have shown that shared control reduces control variability and mental workload, and improves accuracy in path tracking and car following. Crucial to road safety, however, is not whether shared control improves performance in routine driving tasks, but what happens in dangerous situations when a conflict of authority occurs, or when the force feedback cannot be relied upon or is suddenly disengaged. Drawing on research into transfer of training, it is shown that shared control may induce aftereffects and may hamper retention of robust driving skills. Supplementary information should not be provided continuously, but on an as-needed basis, warning or assisting drivers only when deviations from acceptable tolerance limits arise.","shared control; guidance hypothesis; haptic guidance; concurrent continuous feedback; bandwidth feedback; road safety; transfer of learning; transfer of training","en","conference paper","IEEE","","","","","","","","Mechanical, Maritime and Materials Engineering","BioMechanical Engineering","","","",""
"uuid:8c40006e-3bc1-43d6-b9c5-5907eb063c49","http://resolver.tudelft.nl/uuid:8c40006e-3bc1-43d6-b9c5-5907eb063c49","Risk factors in patient safety: Minimally invasive surgery versus conventional surgery","Rodrigues, S.P.; Wever, A.M.; Denkelman, J.; Jansen, F.W.","","2011","Background This study aimed to identify the frequency of events in the different patient safety risk domains during minimally invasive surgery (MIS) and conventional surgery (CS). Methods A convenience sample of gynecologic MIS and CS was observed. Events were observed and categorized into one of the predefined patient safety risk domains. Results A total of 53 procedures were observed: 26 CS and 27 MIS procedures. The general characteristics were comparable between the two groups. A large number of environmental events were observed, averaging one every 2.5 min. Technical events and events of an organizational nature occurred more often in MIS (P < 0.01) than in CS (P < 0.01). The relative risk for the occurrence of one or more technical events in MIS compared with CS was 1.7, and the risk for two or more technical events was 4.1. A time out according to protocol showed no relationship to the occurrence of the different types of patient safety-related events. Conclusion The technological complexity inherent in MIS makes this type of surgery more prone to technology-related problems than CS, even in a specially designed minimally invasive surgical suite. A regular time-out procedure developed for CS lacks the attention necessary for the complex technology used in MIS and therefore is insufficient for MIS procedures briefing. Incorporating a specially designed technology checklist in a regular briefing protocol could be a solution to decrease the number of events in MIS.","minimally invasive surgery; patient safety; risk factor; safety; surgery; systems approach","en","journal article","Springer","","","","","","","","Mechanical, Maritime and Materials Engineering","Biomechanical Engineering","","","",""
"uuid:9af735f3-2f27-4b46-8ae5-b9c99d1b6bfb","http://resolver.tudelft.nl/uuid:9af735f3-2f27-4b46-8ae5-b9c99d1b6bfb","Why the Fitts list has persisted throughout the history of function allocation","De Winter, J.C.F.; Dodou, D.","","2011","Function allocation is a core activity of the human–machine systems discipline. Sixty years ago, Paul Fitts marked the outset of function allocation research with an 11-statements list. Since then numerous function allocation methods have been proposed, but strikingly the seminal Fitts list spans the entire history of this domain and continues to be cited today. In this paper, we intend to explain why the Fitts list is such a pervasive factor in function allocation research, despite having received extensive criticism. We invoke philosophy of science, and we show that the Fitts list fulfils six important criteria for appraising scientific theories: plausibility, explanatory adequacy, interpretability, simplicity, descriptive adequacy, and generalisability. Furthermore, we show that the Fitts report identified issues which decades later became known as the ironies of automation. We conclude that the Fitts list is an adequate approximation that captures the most important regularity of automation, and that the Fitts report represents an unprecedented intellectual achievement that has succeeded in its pioneering objective.","the Fitts list; MABAMABA; function allocation; humanmachine systems","en","journal article","Springer","","","","","","","","Mechanical, Maritime and Materials Engineering","Biomechanical Engineering","","","",""
"uuid:110c5f9e-340f-4917-b9ca-ab9f4adbb556","http://resolver.tudelft.nl/uuid:110c5f9e-340f-4917-b9ca-ab9f4adbb556","Visual force feedback in laparoscopic training","Horeman, T.; Rodrigues, S.P.; Van den Dobbelsteen, J.J.; Jansen, F.W.; Dankelman, J.","","2011","Background - To improve endoscopic surgical skills, an increasing number of surgical residents practice on box or virtual reality (VR) trainers. Current training is focused mainly on hand–eye coordination. Training methods that focus on applying the right amount of force are not yet available. Methods - The aim of this project is to develop a low-cost training system that measures the interaction force between tissue and instruments and displays a visual representation of the applied forces inside the camera image. This visual representation continuously informs the subject about the magnitude and the direction of applied forces. To show the potential of the developed training system, a pilot study was conducted in which six novices performed a needledriving task in a box trainer with visual feedback of the force, and six novices performed the same task without visual feedback of the force. All subjects performed the training task five times and were subsequently tested in a post-test without visual feedback. Results - The subjects who received visual feedback during training exerted on average 1.3 N (STD 0.6 N) to drive the needle through the tissue during the post-test. This value was considerably higher for the group that received no feedback (2.6 N, STD 0.9 N). The maximum interaction force during the post-test was noticeably lower for the feedback group (4.1 N, STD 1.1 N) compared with that of the control group (8.0 N, STD 3.3 N). Conclusions - The force-sensing training system provides us with the unique possibility to objectively assess tissuehandling skills in a laboratory setting. The real-time visualization of applied forces during training may facilitate acquisition of tissue-handling skills in complex laparoscopic tasks and could stimulate proficiency gain curves of trainees. However, larger randomized trials that also include other tasks are necessary to determine whether training with visual feedback about forces reduces the interaction force during laparoscopic surgery.","augmented reality; visual force feedback; training/courses; box trainers; laparoscopy; endoscopy","en","journal article","Springer","","","","","","","","Mechanical, Maritime and Materials Engineering","Biomechanical Engineering","","","",""
"uuid:6715a175-c745-4ddd-8f15-bfde35c20978","http://resolver.tudelft.nl/uuid:6715a175-c745-4ddd-8f15-bfde35c20978","Inventory of platforms towards the design of a statically balanced six degrees of freedom compliant precision stage","Dunning, A.G.; Tolou, N.; Herder, J.","","2011","For many applications in precision engineering, a six degrees of freedom (DoF) compliant stage (CS) with zero stiffness is desirable, to deal with problems like backlash, friction, lubrication, and at the same time, reduce the actuation force. To this end, the compliant stage (also known as compliant mechanism) can be statically balanced with a stiffness compensation mechanism, to compensate the energy stored in the compliant parts, resulting in a statically balanced compliant stage (SBCS). Statically balanced compliant stages can be a breakthrough in precision engineering. This paper presents an inventory of platforms suitable for the design of a 6 DoF compliant stage for precision engineering. A literature review on 3–6 DoF compliant stages, static balancing strategies and statically balanced compliant mechanisms (SBCMs) has been performed. A classification from the inventory has been made and followed up by discussion. An obviously superior architecture for a 6 DoF compliant stage was not found. All the 6 DoF stages are either non-statically balanced compliant structures or statically balanced non compliant structures. The statically balanced non-compliant structures can be transformed into compliant structures using lumped compliance, while all SBCMs had distributed compliance. A 6 DoF SBCS is a great scope for improvements in precision engineering stages.","OA-Fund TU Delft","en","journal article","Copernicus Publications","","","","","","","","Mechanical, Maritime and Materials Engineering","BioMechanical Engineering","","","",""
"uuid:06e3223b-6802-408b-81e0-4fbff28fa96f","http://resolver.tudelft.nl/uuid:06e3223b-6802-408b-81e0-4fbff28fa96f","Parallel kinematics robot with five legs","Lambert, P.","","2011","Robot with multiple degrees of freedom comprising five legs (2) linked at a first of their ends to a base ( 3), and at a second of their ends opposite to the first ends to a mobile platform (4), which platform carries at least one tool (5, 6, 121, 12 ""), and wherein the robot further comprises an actuator for operating the tool or tools, which actuator is embodied by the joint operation of the motor drives ( 9 ) of the legs that are positioned at the base.","","en","patent","European Patent Office","","","","","","","","Mechanical, Maritime and Materials Engineering","Biomechanical Engineering","","","",""
"uuid:122dbfb6-7797-4330-b44f-0d00569a9b30","http://resolver.tudelft.nl/uuid:122dbfb6-7797-4330-b44f-0d00569a9b30","AQUILA: Assessment of quality in lower limb arthroplasty. An expert Delphi consensus for total knee and total hip arthroplasty","Pijls, B.G.; Dekkers, O.M.; Middeldorp, S.; Valstar, E.R.; Van der Heide, H.J.L.; Van der Linden-Van der Zwaag, H.M.J.; Nelissen, R.G.H.H.","","2011","Background: In the light of both the importance and large numbers of case series and cohort studies (observational studies) in orthopaedic literature, it is remarkable that there is currently no validated measurement tool to appraise their quality. A Delphi approach was used to develop a checklist for reporting quality, methodological quality and generalizability of case series and cohorts in total hip and total knee arthroplasty with a focus on aseptic loosening. Methods: A web-based Delphi was conducted consisting of two internal rounds and three external rounds in order to achieve expert consensus on items considered relevant for reporting quality, methodological quality and generalizability. Results: The internal rounds were used to construct a master list. The first external round was completed by 44 experts, 35 of them completed the second external round and 33 of them completed the third external round. Consensus was reached on an 8-item reporting quality checklist, a 6-item methodological checklist and a 22-item generalizability checklist. Conclusions: Checklist for reporting quality, methodological quality and generalizability for case series and cohorts in total hip and total knee arthroplasty were successfully created through this Delphi. These checklists should improve the accuracy, completeness and quality of case series and cohorts regarding total hip and total knee arthroplasty.","total knee arthroplasty; total hip arthroplasty; reporting quality; methodological quality; generalizability","en","journal article","BioMed Central","","","","","","","","Mechanical, Maritime and Materials Engineering","Biomechanical Engineering","","","",""
"uuid:c35ff578-5120-41b2-bee3-d1d42163c40c","http://resolver.tudelft.nl/uuid:c35ff578-5120-41b2-bee3-d1d42163c40c","No differences in in vivo kinematics between six different types of knee prostheses","Wolterbeek, N.; Nelissen, R.G.H.H.; Valstar, E.R.","","2011","Purpose: The aim of this study was to compare a broad range of total knee prostheses with different design parameters to determine whether in vivo kinematics was consistently related to design. The hypothesis was that there are no clear recognizable differences in in vivo kinematics between different design parameters or prostheses. Methods: At two sites, data were collected by a single observer on 52 knees (49 subjects with rheumatoid arthritis or osteoarthritis). Six different total knee prostheses were used: multi-radius, single-radius, fixed-bearing, mobilebearing, posterior-stabilized, cruciate retaining and cruciate sacrificing. Knee kinematics was recorded using fluoroscopy as the patients performed a step-up motion. Results: There was a significant effect of prosthetic design on all outcome parameters; however, post hoc tests showed that the NexGen group was responsible for 80% of the significant values. The range of knee flexion was much smaller in this group, resulting in smaller anterior-posterior translations and rotations. Conclusion: Despite kinematics being generally consistent with the kinematics intended by their design, there were no clear recognizable differences in in vivo kinematics between different design parameters or prostheses. Hence, the differences in design parameters or prostheses are not distinct enough to have an effect on clinical outcome of patients.","kinematics; fluoroscopy; single-radius; multi-radius; mobile-bearing; fixed-bearing","en","journal article","Springer Verlag","","","","","","","","Mechanical, Maritime and Materials Engineering","Biomechanical Engineering","","","",""
"uuid:81429406-446a-4701-9c21-9a82ebaca171","http://resolver.tudelft.nl/uuid:81429406-446a-4701-9c21-9a82ebaca171","Short range stiffness elastic limit depends on joint velocity","De Vlugt, E.; Van Eesbeek, S.; Baines, P.; Hilte, J.; Meskers, C.G.M.; De Groot, J.H.","","2011","Muscles behave as elastic springs during the initial strain phase, indicated as short range stiffness (SRS). Beyond a certain amount of strain the muscle demonstrates a more viscous behavior. The strain at which the muscle transits from elastic- to viscous-like behavior is called the elastic limit and is believed to be the result of breakage of cross-bridges between the contractile filaments. The aim of this study was to test whether the elastic limit, measured in vivo at the wrist joint, depended on the speed of lengthening. Brief extension rotations were imposed to the wrist joint (n=8) at four different speeds and at three different levels of voluntary torque using a servo controlled electrical motor. Using a recently published identification scheme, we quantified the elastic limit from measured joint angle and torque. The results showed that the elastic limit significantly increased with speed in a linear way, indicating to a constant time of approximately 30 ms before cross-bridges break. The implications for movement control of the joint are discussed.","short range stiffness; joint stiffness; muscle; cross-bridges; elastic limit; model; identification","en","journal article","Elsevier","","","","","","","","Mechanical, Maritime and Materials Engineering","Biomechanical Engineering","","","",""
"uuid:dd0bd871-fbf4-4def-8494-43758a85808f","http://resolver.tudelft.nl/uuid:dd0bd871-fbf4-4def-8494-43758a85808f","EMG feedback tasks reduce reflexive stiffness during force and position perturbations","Forbes, P.A.; Happee, R.; Van der Helm, F.C.T.; Schouten, A.C.","","2011","Force and position perturbations are widely applied to identify muscular and reflexive contributions to posture maintenance of the arm. Both task instruction (force vs. position) and the inherently linked perturbation type (i.e., force perturbations-position task and position perturbations-force tasks) affect these contributions and their mutual balance. The goal of this study is to explore the modulation of muscular and reflexive contributions in shoulder muscles using EMG biofeedback. The EMG biofeedback provides a harmonized task instruction to facilitate the investigation of perturbation type effects irrespective of task instruction. External continuous force and position perturbations with a bandwidth of 0.5–20 Hz were applied at the hand while subjects maintained prescribed constant levels of muscular co-activation using visual feedback of an EMG biofeedback signal. Joint admittance and reflexive impedance were identified in the frequency domain, and parametric identification separated intrinsic muscular and reflexive feedback properties. In tests with EMG biofeedback, perturbation type (position and force) had no effect on joint admittance and reflexive impedance, indicating task as the dominant factor. A reduction in muscular and reflexive stiffness was observed when performing the EMG biofeedback task relative to the position task. Reflexive position feedback was effectively suppressed during the equivalent EMG biofeedback task, while velocity and acceleration feedback were both decreased by approximately 37%. This indicates that force perturbations with position tasks are a more effective paradigm to investigate complete dynamic motor control of the arm, while EMG tasks tend to reduce the reflexive contribution.","biofeedback; neuromuscular control; electromyography; afferent feedback; mechanical admittance; reflexive impedance","en","journal article","Springer","","","","","","","","Mechanical, Maritime and Materials Engineering","Biomechanical Engineering","","","",""
"uuid:e6e4b937-08ef-48d7-b380-03eaa98fbca8","http://resolver.tudelft.nl/uuid:e6e4b937-08ef-48d7-b380-03eaa98fbca8","Underactuated hands: Fundamentals, performance analysis and design","Kragten, G.A.","Van der Helm, F.C.T. (promotor); Herder, J.L. (promotor)","2011","There is an emerging need to apply adaptive robotic hands to substitute humans in dangerous, laborious, or monotonous work. The state-of-the-art robotic hands cannot fulfill this need, because they are expensive, hard to control and they consist of many vulnerable motors and sensors. It is aimed to develop simple, adaptive hands that are capable of grasping and holding a large variety of objects. To achieve these properties, the concept of underactuation (i.e. having fewer actuators than independently moving fingers) is applied. First new metrics are defined which quantify the range of object sizes that underactuated hands can grasp and hold. Furthermore, a new method is developed to dimension the main design parameters of underactuated hands, such that the fingers can envelope and stably grasp the required range of objects. The new performance metrics and design method are applied to the design and evaluation of a new robotic hand that consists of a minimum number of motors (i.e. one) and sensors (i.e. zero). The innovation of this hand is that it mechanically decides whether to hold an object in a precision grasp or a power grasp configuration. No sensors, auxiliary actuation mechanisms, motors or control are needed to convert between these two distinct grasp configurations. It is concluded that the principle of underactuation and the proposed design method are effective to achieve self-adaptive, robust and cheap hands that are capable to grasp and hold a large range of different objects.","underactuated hand; underactuated grasping; grasp performance; robot hand","en","doctoral thesis","","","","","","","","","Mechanical, Maritime and Materials Engineering","BioMechanical Engineering","","","",""
"uuid:baa3af75-8d0b-4037-8ea1-ad86524f31ee","http://resolver.tudelft.nl/uuid:baa3af75-8d0b-4037-8ea1-ad86524f31ee","Reflex mechanisms in CRPS-related dystonia","Mugge, W.","Van der Helm, F.C.T. (promotor); Van Hilten, J.J. (promotor); Schouten, A.C. (promotor)","2011","Complex Regional Pain Syndrome (CRPS) is a disabling syndrome associated with sensory (e.g., burning pain, allodynia, hyperalgesia), autonomic (e.g., edema, skin color and temperature changes), and motor impairments (e.g., tremor, myoclonus, dystonia). Approximately 25% of the patients with CRPS develop fixed dystonia which is characterized by abnormal sustained muscle contractions and abnormal postures. No definitive pathophysiology of CRPS and related dystonia exists. Neurophysiological studies have found evidence of impaired inhibition at the spinal cord and motor cortex. In this thesis, a computational neuromuscular model has been developed to explain the movement disorder fixed dystonia through disturbed proprioceptive reflexes. To validate the model, methods have been developed to quantify proprioceptive reflexes in vivo during postural control of patients with fixed dystonia. The prime goal of this thesis is to gain insight into the pathophysiology of fixed dystonia and develop a diagnostic protocol. Although the mechanisms behind fixed dystonia are still elusive, the evidence implicating involvement of aberrant muscle force feedback is compelling. Aberrant muscle force feedback successfully mimicked dystonia in the neuromuscular model while experiments demonstrated involvement of muscle force feedback in fixed dystonia.","human motor control; afferent feedback; system identification; movement disorders; dystonia; CRPS","en","doctoral thesis","","","","","","","","","Mechanical, Maritime and Materials Engineering","BioMechanical Engineering","","","",""
"uuid:964b2942-585e-4a03-9457-723762440476","http://resolver.tudelft.nl/uuid:964b2942-585e-4a03-9457-723762440476","Forces in the Shoulder Joint: On validation of musculoskeletal shoulder models","Asadi Nikooyan, A.","Van der Helm, F.C.T. (promotor); Veeger, H.E.J. (promotor)","2011","Detailed information about muscle forces in the human musculoskeletal system are highly demanded for several applications. Unfortunately, the measurement of muscle forces in-vivo is hardly possible. To date, musculoskeletal models are best alternative for the direct measurement of these forces. A major concern in musculoskeletal modeling is, however, model validity. To validate a model we need to compare its predictions to real measured muscle forces which, as mentioned, are difficult to measure. The main objective of this thesis is the validation of a comprehensive musculoskeletal shoulder model, the Delft Shoulder and Elbow Model, at the level of kinematic and dynamic models. Recently, an implantable instrumented shoulder endoprosthesis has been developed that is capable of measuring contact loads in the glenohumeral joint in-vivo. Although direct measurement of muscle forces is still not possible by this implant, it does allow for a general validation at the level of the summed muscle forces in the glenohumeral joint. In the first part of this thesis, the in-vivo measured forces in the instrumented shoulder implant are used, as a ‘golden standard’, to quantitatively validate the model. A general conclusion of this part is that the model is moderately accurate for estimation of glenohumeral joint reaction forces. The second part of this thesis explores the reasons for the differences between model predictions and experimental data that were observed and described in the first part and focuses on model adjustments to find a closer match between model and experiment. A selection of potential causes (e.g. muscle co-contraction, articular friction) is identified and investigated. An important conclusion of this part would be that antagonist muscle co-contraction should be considered in the modeling procedure. It is also concluded that friction moments in the shoulder endoprosthesis are considerable and should be included in the biomechanical analysis of artificial shoulder joints.","force; shoulder joint; validation; instrumented endoprosthesis; model; EMG; articular friction; load sharing","en","doctoral thesis","Boxpress","","","","","","","","Mechanical, Maritime and Materials Engineering","BioMechanical Engineering","","","",""
"uuid:7796c1b5-f7c3-4e86-8070-fb2ffc681ea7","http://resolver.tudelft.nl/uuid:7796c1b5-f7c3-4e86-8070-fb2ffc681ea7","The influence of foot geometry on the calcaneal osteotomy angle based on two-dimensional static force analyses","Reilingh, M.L.; Tuijthof, G.J.M.; Van Dijk, C.N.; Blankevoort, L.","","2011","Background: Malalignment of the hindfoot can be corrected with a calcaneal osteotomy (CO). A well-selected osteotomy angle in the sagittal plane will reduce the shear force in the osteotomy plane while walking. The purpose was to determine the presence of a relationship between the foot geometry and loading of the calcaneus, which influences the choice of the preferred CO angle. Methods A static free body force analysis was made of the posterior calcaneal fragment in the second half of the stance phase to determine the main loads: the plantar apeunorosis (PA) and Achilles tendon (AT). The third load is on the osteotomy surface which should be oriented such that the shear component of the force is zero. The force direction of the PA and AT was measured on 58 MRIs of the foot, and the force ratio between both structures was taken from the literature. In addition the PA-to-AT force ratio was estimated for different foot geometries to identify the relationship. Results: Based on the wish to minimize the shear force during walking, a mean CO angle was determined to be 33º (SD8) relative to the foot sole. In pes planus foot geometry, the angle should be higher than the mean. In pes cavus foot geometry, the angle should be smaller. Conclusion: Foot geometry, in particular the relative foot heights is a determinant for the individual angle in performing the sliding calcaneal osteotomy. It is recommended to take into account the foot geometry (arch) when deciding on the CO angle for hindfoot correction.","calcaneal osteotomy; achilles tendon; plantar apeunorosis; force analysis; foot model","en","journal article","Springer Verlag","","","","","","","","Mechanical, Maritime and Materials Engineering","Biomechanical Engineering","","","",""
"uuid:12ecb37d-9d89-459a-9f29-6050552decad","http://resolver.tudelft.nl/uuid:12ecb37d-9d89-459a-9f29-6050552decad","Fixed Dystonia in Complex Regional Pain Syndrome: A Descriptive and Computational Modeling Approach","Munts, A.G.; Mugge, W.; Meurs, T.S.; Schouten, A.C.; Marinus, J.; Lorimer Moseley, G.; Van der Helm, F.C.T.; Van Hilten, J.J.","","2011","Background: Complex regional pain syndrome (CRPS) may occur after trauma, usually to one limb, and is characterized by pain and disturbed blood flow, temperature regulation and motor control. Approximately 25% of cases develop fixed dystonia. Involvement of dysfunctional GABAergic interneurons has been suggested, however the mechanisms that underpin fixed dystonia are still unknown. We hypothesized that dystonia could be the result of aberrant proprioceptive reflex strengths of position, velocity or force feedback. Methods: We systematically characterized the pattern of dystonia in 85 CRPS-patients with dystonia according to the posture held at each joint of the affected limb. We compared the patterns with a neuromuscular computer model simulating aberrations of proprioceptive reflexes. The computer model consists of an antagonistic muscle pair with explicit contributions of the musculotendinous system and reflex pathways originating from muscle spindles and Golgi tendon organs, with time delays reflective of neural latencies. Three scenarios were simulated with the model: (i) increased reflex sensitivity (increased sensitivity of the agonistic and antagonistic reflex loops); (ii) imbalanced reflex sensitivity (increased sensitivity of the agonistic reflex loop); (iii) imbalanced reflex offset (an offset to the reflex output of the agonistic proprioceptors). Results: For the arm, fixed postures were present in 123 arms of 77 patients. The dominant pattern involved flexion of the fingers (116/123), the wrists (41/123) and elbows (38/123). For the leg, fixed postures were present in 114 legs of 77 patients. The dominant pattern was plantar flexion of the toes (55/114 legs), plantar flexion and inversion of the ankle (73/114) and flexion of the knee (55/114). Only the computer simulations of imbalanced reflex sensitivity to muscle force from Golgi tendon organs caused patterns that closely resembled the observed patient characteristics. In parallel experiments using robot manipulators we have shown that patients with dystonia were less able to adapt their force feedback strength. Conclusions: Findings derived from a neuromuscular model suggest that aberrant force feedback regulation from Golgi tendon organs involving an inhibitory interneuron may underpin the typical fixed flexion postures in CRPS patients with dystonia.","","en","journal article","BioMed Central","","","","","","","","Mechanical, Maritime and Materials Engineering","Biomechanical Engineering","","","",""
"uuid:f2674c11-299c-41b0-9bfd-c4a2dd8268ce","http://resolver.tudelft.nl/uuid:f2674c11-299c-41b0-9bfd-c4a2dd8268ce","Sampling duration effects on centre of pressure descriptive measures","Van der Kooij, H.; Campbell, A.D.; Carpenter, M.G.","","2011","The different measures used to characterize postural sway are sensitive to variations in sampling duration, yet there remains marked variability and a lack of consistency in this temporal parameter when compared between studies. We investigated the effect of sampling duration on 22 commonly used frequency and time domain measures and stabilogram diffusion coefficients. Participants stood quietly on a forceplate during two 600 s standing trials with eyes open and eyes closed. The results clearly show that the amplitudes of the descriptive measures are sensitive to sampling duration. Only measures related to the amount of sway were sensitive for eyes open versus eyes closed conditions. In addition to sample duration, the filter settings, sampling frequency and fitting windows should be standardized since they also affect the magnitude of the descriptive measures. Without such standards, the inability to accurately compare between studies will persist.","sample duration; centre of pressure; quiet stance; reliability; descriptive measures; posturography","en","journal article","Elsevier","","","","","","","","Mechanical, Maritime and Materials Engineering","Biomechanical Engineering","","","",""
"uuid:b249a0c7-7230-4e58-8e08-60c411ddfe23","http://resolver.tudelft.nl/uuid:b249a0c7-7230-4e58-8e08-60c411ddfe23","Performance of arthroscopic irrigation systems assessed with automatic blood detection","Tuijthof, G.J.M.; De Vaal, M.M.; Sierevelt, I.N.; Blankevoort, L.; Van der List, M.P.J.","","2011","","arthroscopy; shoulder; performance; bleeding episode; view; irrigation system","en","journal article","Springer Verlag","","","","","","","","Mechanical, Maritime and Materials Engineering","Biomechanical Engineering","","","",""
"uuid:0b59c956-87db-4fbf-82d2-9ce357755fa3","http://resolver.tudelft.nl/uuid:0b59c956-87db-4fbf-82d2-9ce357755fa3","Early design interference detection based on qualitative physics","D'Amelio, V.; Chmarra, M.K.; Tomiyama, T.","","2011","Developing multi-disciplinary products presents cross-disciplinary problems that are difficult to predict and to solve. Unfortunately, those cross-disciplinary problems are often discovered only at a later stage of the design through physical prototypes and can lead to modification of the conceptual design of a product. This is extremely costly and time consuming. This paper describes a new software tool, a Design Interference Detector (DID), which based on qualitative reasoning infers possible problematic physical phenomena that may appear in a design. However, qualitative reasoning techniques often reveal a shortcoming of generating too many negligible solutions. This is a burden to the designer and makes qualitative reasoning practically unusable. Therefore, we developed two filtering methods that filter out such negligible solutions and highlight only potential cross-disciplinary problems. DID with these filtering methods aims particularly at supporting redesign of complex multi-disciplinary products. The paper analyzes advantages and limitations of the filtering methods through a case study.","multi-disciplinary design; qualitative physics; complexity management; conceptual design","en","journal article","Springer","","","","","","","","Mechanical, Maritime and Materials Engineering","Biomechanical Engineering","","","",""
"uuid:4ce91f4d-0d11-4df1-9582-c0b9d18c35ac","http://resolver.tudelft.nl/uuid:4ce91f4d-0d11-4df1-9582-c0b9d18c35ac","Comparison of Two Methods for In Vivo Estimation of the Glenohumeral Joint Rotation Center (GH-JRC) of the Patients with Shoulder Hemiarthroplasty","Asadi Nikooyan, A.; Van der Helm, F.C.T.; Westerhoff, P.; Graichen, F.; Bergmann, G.; Veeger, H.E.J.","","2011","Determination of an accurate glenohumeral-joint rotation center (GH-JRC) from marker data is essential for kinematic and dynamic analysis of shoulder motions. Previous studies have focused on the evaluation of the different functional methods for the estimation of the GH-JRC for healthy subjects. The goal of this paper is to compare two widely used functional methods, namely the instantaneous helical axis (IHA) and symmetrical center of rotation (SCoRE) methods, for estimating the GH-JRC in vivo for patients with implanted shoulder hemiarthroplasty. The motion data of five patients were recorded while performing three different dynamic motions (circumduction, abduction, and forward flexion). The GH-JRC was determined using the CT-images of the subjects (geometric GH-JRC) and was also estimated using the two IHA and SCoRE methods. The rotation centers determined using the IHA and SCoRE methods were on average 1.4760.62 cm and 2.0760.55 cm away from geometric GH-JRC, respectively. The two methods differed significantly (two-tailed p-value from paired t-Test ,0.02, post-hoc power ,0.30). The SCoRE method showed a significant lower (two-tailed p-value from paired t-Test ,0.03, post-hoc power ,0.68) repeatability error calculated between the different trials of each motion and each subject and averaged across all measured subjects (0.6260.10 cm for IHA vs. 0.4360.12 cm for SCoRE). It is concluded that the SCoRE appeared to be a more repeatable method whereas the IHA method resulted in a more accurate estimation of the GH-JRC for patients with endoprostheses.","","en","journal article","Public Library of Science","","","","","","","","Mechanical, Maritime and Materials Engineering","Biomechanical Engineering","","","",""
"uuid:d5a6799b-38cf-40e9-803c-f795f35af41d","http://resolver.tudelft.nl/uuid:d5a6799b-38cf-40e9-803c-f795f35af41d","Apparatus and method for automatically determining a strabismus angle","Schutte, S.; Geukers, E.B.M.; Simonsz, H.J.; Van der Helm, F.C.T.","","2011","Apparatus and method for automatically determining a strabismus angle of the eyes of an individual by performing a reflection test on said eyes, comprising the steps of : -directing at least a first beam of light onto said eyes of the individual; -having the individual focus its eyes; -using at least one imaging device for: measuring the light beam reflected from the eyes for establishing which eye is fixating, and performing a reflex test on both eyes to estimate the strabismus angle, wherein -the reflex test is carried out by applying at least two light sources at known differing positions and measuring the corneal reflections of said light sources in both eyes by monitoring said corneal reflections by an imaging device or devices; -the said corneal reflections are used to derive corneal center coordinates for both eyes individually; -for both eyes individually pupil center coordinates are estimated; -the corneal center coordinates and the pupil center coordinates of both eyes are used to estimate the strabismus angle. For the eye that is fixating an angle kappa is calculated representing an angle between the eyes' optical axis through the corneal center and the pupil center, and the visual axis through the corneal center and the eye's fovea, and the angle kappa is then used for determining the strabismus angle.","","en","patent","European Patent Office","","","","","","","","Mechanical, Maritime and Materials Engineering","Biomechanical Engineering","","","",""
"uuid:591f1879-a667-4e15-9fdf-08cbfb6bd69d","http://resolver.tudelft.nl/uuid:591f1879-a667-4e15-9fdf-08cbfb6bd69d","Clinically Translatable Cell Tracking and Quantification by MRI in Cartilage Repair Using Superparamagnetic Iron Oxides","Van Buul, G.; Kotek, G.; Wielopolski, P.A.; Farrell, E.; Bos, P.K.; Weinans, H.; Grohnert, A.U.; Jahr, H.; Verhaar, J.A.N.; Krestin, G.P.; Van Osch, G.J.V.M.; Bernsen, M.R.","","2011","Background: Articular cartilage has very limited intrinsic regenerative capacity, making cell-based therapy a tempting approach for cartilage repair. Cell tracking can be a major step towards unraveling and improving the repair process of these therapies. We studied superparamagnetic iron oxides (SPIO) for labeling human bone marrow-derived mesenchymal stem cells (hBMSCs) regarding effectivity, cell viability, long term metabolic cell activity, chondrogenic differentiation and hBMSC secretion profile. We additionally examined the capacity of synovial cells to endocytose SPIO from dead, labeled cells, together with the use of magnetic resonance imaging (MRI) for intra-articular visualization and quantification of SPIO labeled cells. Methodology/Prinicipal Findings: Efficacy and various safety aspects of SPIO cell labeling were determined using appropriate assays. Synovial SPIO re-uptake was investigated in vitro by co-labeling cells with SPIO and green fluorescent protein (GFP). MRI experiments were performed on a clinical 3.0T MRI scanner. Two cell-based cartilage repair techniques were mimicked for evaluating MRI traceability of labeled cells: intra-articular cell injection and cell implantation in cartilage defects. Cells were applied ex vivo or in vitro in an intra-articular environment and immediately scanned. SPIO labeling was effective and did not impair any of the studied safety aspects, including hBMSC secretion profile. SPIO from dead, labeled cells could be taken up by synovial cells. Both injected and implanted SPIO-labeled cells could accurately be visualized by MRI in a clinically relevant sized joint model using clinically applied cell doses. Finally, we quantified the amount of labeled cells seeded in cartilage defects using MR-based relaxometry. Conclusions: SPIO labeling appears to be safe without influencing cell behavior. SPIO labeled cells can be visualized in an intra-articular environment and quantified when seeded in cartilage defects.","","en","journal article","Public Library of Science","","","","","","","","Mechanical, Maritime and Materials Engineering","Biomechanical Engineering","","","",""
"uuid:09ce8f3e-5728-4065-978c-16f65539a344","http://resolver.tudelft.nl/uuid:09ce8f3e-5728-4065-978c-16f65539a344","Design and performance assessment of an underactuated hand for industrial applications","Meijneke, C.; Kragten, G.A.; Wisse, M.","","2011","The Delft Hand 2 (DH-2) is an underactuated robot hand meant for industrial applications, having six degrees of freedom (DoF), one actuator (DoA) and no sensors. It was designed to provide a cheap and robust hand to grasp a large range of objects without damaging them. The goal of this paper is to assess the design and performance of the DH-2, demonstrating how the design was optimized for its intended application area and how the hand was simplified to make it commercially attractive. Performance tests show that the DH-2 has a payload of 2 kg for an object range of 60 to 120 mm, it can close or open within 0.5 s, and it only uses open-loop control by means of the input voltage of the motor. The results demonstrate that the industrial need of a simple, cheap and effective robotic hand can be achieved with the principle of underactuation and the use of conventional components.","","en","journal article","Copernicus Publications","","","","","","","","Mechanical, Maritime and Materials Engineering","Biomechanical Engineering","","","",""
"uuid:d4ca87c5-0af4-43e0-94ac-9b193df6cffd","http://resolver.tudelft.nl/uuid:d4ca87c5-0af4-43e0-94ac-9b193df6cffd","Artificial hand","Wisse, M.; Wilbers, F.; Meijneke, C.","","2011","Artificial hand (1) suitable for robotic applications or as a prosthesis, comprising a frame (2) with a thumb (3) and at least two fingers (4,5), and having a motor drive (6) for adjusting the thumb and the fingers with respect to the frame, wherein the motor drive has a housing (7) and an axle (8) which is rotatably positioned within the housing, and wherein the housing is mounted in a first bearing (9') supported by the frame to enable that the housing may rotate with regard to the frame, and that the thumb and fingers are drivingly connected with the housing and the axle respectively.","","en","patent","European Patent Office","","","","","","","","Mechanical, Maritime and Materials Engineering","Biomechanical Engineering","","","",""
"uuid:b9a5907f-c079-41a8-8912-09efab8d6219","http://resolver.tudelft.nl/uuid:b9a5907f-c079-41a8-8912-09efab8d6219","Guest editorial: State-of-the-art in underactuated grasping","Birglen, L.; Kragten, C.A.; Herder, J.L.","","2010","","","en","journal article","Copernicus Publications","","","","","","","","Applied Sciences","Biomechanical Engineering","","","",""
"uuid:bbd99a7c-001c-4687-97d4-ad07e894e70a","http://resolver.tudelft.nl/uuid:bbd99a7c-001c-4687-97d4-ad07e894e70a","A proposal for benchmark tests for underactuated or compliant hands","Kragten, G.A.; Meijneke, C.; Herder, J.L.","","2010","There is a lack of agreement in the literature as to what exactly quantifies the performance of underactuated hands. This paper proposes two benchmark tests to measure the ability of underactuated hands to grasp different objects and the ability to hold the objects when force disturbances apply. The first test determines the smallest and largest cylindrical object which can be successfully grasped in an enveloping grasp or in a pinch grasp. The second test provides the maximal allowable force which can be applied to a grasped object without loosing it. A setup was constructed consisting of standard components. Exemplary tests were applied to the Delft Hand 2. The proposed benchmark tests are representative to quantify the performance of pick and place operations with underactuated hands. The results of the tests can be applied to evaluate, compare, and improve the performance of robotic hands.","","en","journal article","Copernicus","","","","","","","","Mechanical, Maritime and Materials Engineering","Biomechanical Engineering","","","",""
"uuid:4f5277d7-33c5-4ac8-91a3-befde91aabad","http://resolver.tudelft.nl/uuid:4f5277d7-33c5-4ac8-91a3-befde91aabad","Editorial","Herder, J.L.; Barrari, A.; Tolou, N.","","2010","Yet another journal? And what is the windmill about? Those are two questions that we heard a lot lately. Yes, another journal, or rather, a different journal, called Mechanical Sciences (MS). The main difference is that the journal is open access, of which there are not many in the field of mechanical sciences. Grant agencies more and more demand part of the research output to be in open access form, the reasoning being that the knowledge was generated with tax money so it should be available to all tax payers, including small and medium sized enterprises. In knowledge economies this makes good sense. But there is more.","","en","journal article","Copernicus Publications","","","","","","","","Mechanical, Maritime and Materials Engineering","Biomechanical Engineering","","","",""
"uuid:8370ba88-4109-4bb0-93fc-04c6fe555a86","http://resolver.tudelft.nl/uuid:8370ba88-4109-4bb0-93fc-04c6fe555a86","Delta robot","Herder, J.L.; Van der Wijk, V.","","2010","The invention relates to a delta robot comprising a stationary base (2) and a movable platform (3) that is connected to the base with three chains of links (4,5,6), and comprising a balancing system incorporating at least one pantograph (7) for balancing the robot's center of mass, wherein the at least one pantograph has a first free extremity (10) at which it supports a countermass (13) which is arranged to balance the center of mass of the robot.","","en","patent","European Patent Office","","","","","","","","Mechanical, Maritime and Materials Engineering","Biomechanical Engineering","","","",""
"uuid:24f35943-0b67-4c15-9877-8961dcf74342","http://resolver.tudelft.nl/uuid:24f35943-0b67-4c15-9877-8961dcf74342","Van structuur naar functie?","Veeger, H.E.J.","","2010","","Intreerede","nl","public lecture","Delft University of Technology","","","","","","","","Mechanical, Maritime and Materials Engineering","Biomechanical Engineering","","","",""
"uuid:b40171fc-a7dc-42dd-8f4c-cd4d4aa2c36f","http://resolver.tudelft.nl/uuid:b40171fc-a7dc-42dd-8f4c-cd4d4aa2c36f","The Effects of Large Disturbances on On-Line Reinforcement Learning for aWalking Robot","Schuitema, E.; Caarls, W.; Wisse, M.; Jonker, P.P.; Babuska, R.","","2010","Reinforcement Learning is a promising paradigm for adding learning capabilities to humanoid robots. One of the difficulties of the real world is the presence of disturbances. In Reinforcement Learning, disturbances are typically dealt with stochastically. However, large and infrequent disturbances do not fit well in this framework; essentially, they are outliers and not part of the underlying (stochastic) Markov Decision Process. Therefore, they can negatively influence learning. The main reasons for such disturbances for a humanoid robot are sudden changes in the dynamics (such as a sudden push), sensor noise and sampling time irregularities. We investigate the effects of these types of outliers on the on-line learning process of a simple walking robot simulation. We propose to exclude the outliers from the learning process with the aim to improve convergence and the final solution. While infrequent sensor and timing outliers had a negligible influence, infrequent pushes heavily disrupted the learning process. By excluding the outliers from the learning process, performance was again restored.","","en","conference paper","","","","","","","","","Mechanical, Maritime and Materials Engineering","Biomechanical Engineering","","","",""
"uuid:679cdab0-8c0f-41db-bf45-1051ffbff968","http://resolver.tudelft.nl/uuid:679cdab0-8c0f-41db-bf45-1051ffbff968","Mechanical device for tissue regeneration","Herder, J.L.; Maij, E.","","2010","The invention relates to a mechanical device for tissue- regeneration inside a patient, comprising means (2, 3) to place a scaffold for the tissue under mechanical stress. Said means comprise a first device-part (2) and a second device-part (3) which parts are arranged to be movable with respect to each other, and wherein the first device-part supports a first receptacle (4) and the second device-part supports a second receptacle (5), which receptacles both have open tops (6, 7) that are pointed towards each other so that both receptacles together define a confined area (8) for holding the scaffold.","","en","patent","European Patent Office","","","","","","","","Mechanical, Maritime and Materials Engineering","Biomechanical Engineering","","","",""
"uuid:9a0e9cd2-8f8c-4fc6-bb40-a98a7a1563a1","http://resolver.tudelft.nl/uuid:9a0e9cd2-8f8c-4fc6-bb40-a98a7a1563a1","Relating reflex gain modulation in posture control to underlying neural network properties using a neuromusculoskeletal model","Schuurmans, J.; Van der Helm, F.C.T.; Schouten, A.C.","","2010","During posture control, reflexive feedback allows humans to efficiently compensate for unpredictable mechanical disturbances. Although reflexes are involuntary, humans can adapt their reflexive settings to the characteristics of the disturbances. Reflex modulation is commonly studied by determining reflex gains: a set of parameters that quantify the contributions of Ia, Ib and II afferents to mechanical joint behavior. Many mechanisms, like presynaptic inhibition and fusimotor drive, can account for reflex gain modulations. The goal of this study was to investigate the effects of underlying neural and sensory mechanisms on mechanical joint behavior. A neuromusculoskeletal model was built, in which a pair of muscles actuated a limb, while being controlled by a model of 2,298 spiking neurons in six pairs of spinal populations. Identical to experiments, the endpoint of the limb was disturbed with force perturbations. System identification was used to quantify the control behavior with reflex gains. A sensitivity analysis was then performed on the neuromusculoskeletal model, determining the influence of the neural, sensory and synaptic parameters on the joint dynamics. The results showed that the lumped reflex gains positively correlate to their most direct neural substrates: the velocity gain with Ia afferent velocity feedback, the positional gain with muscle stretch over II afferents and the force feedback gain with Ib afferent feedback. However, position feedback and force feedback gains show strong interactions with other neural and sensory properties. These results give important insights in the effects of neural properties on joint dynamics and in the identifiability of reflex gains in experiments.","reflexes; afferent feedback; reflex gains; sensitivity analysis; system identification","en","journal article","Springer","","","","","","","","Mechanical, Maritime and Materials Engineering","Biomechanical Engineering","","","",""
"uuid:0f1e10e5-8397-4da0-a697-60cdc1c648a9","http://resolver.tudelft.nl/uuid:0f1e10e5-8397-4da0-a697-60cdc1c648a9","Feasibility of noncontact piezoelectric detection of photoacoustic signals in tissue-mimicking phantoms","Kolkman, R.G.M.; Blomme, E.; Cool, T.; Bilcke, M.; Van Leeuwen, T.G.; Steenbergen, W.; Grimbergen, K.A.; Den Heeten, G.J.","","2010","The feasibility of air-coupled ultrasound transducers to detect laser-induced ultrasound from artificial blood vessels embedded in an optically scattering phantom is demonstrated. These air-coupled transducers allow new applications in biomedical photoacoustic imaging where contact with tissue is not preferred. One promising application of such transducers is the addition of photoacoustic imaging to the regular x-ray mammographic screening procedure.","photoacoustic; optoacoustic; ultrasound; blood vessel; imaging; air-coupled ultrasound; air-coupled detection","en","journal article","Society of Photo-Optical Instrumentation","","","","","","","","Mechanical, Maritime and Materials Engineering","Biomechanical Engineering","","","",""
"uuid:59feac56-a603-4b25-8cf8-43cab4c4daa5","http://resolver.tudelft.nl/uuid:59feac56-a603-4b25-8cf8-43cab4c4daa5","Probing forces of menisci: What levels are safe for arthroscopic surgery","Tuijthof, G.J.M.; Horeman, T.; Schafroth, M.U.; Blankevoort, L.; Kerkhoffs, G.M.M.J.","","2010","Purpose To facilitate effective learning, feedback on performance during arthroscopic training is essential. Less attention has been paid to feedback on monitoring safe handling of delicate tissues such as meniscus. The goal is to measure in vitro probing forces of menisci and compare them with a theoretical maximum probing force (TMPF). Method Menisci samples of ten cadavers were mounted on force platforms to measure probing forces up to 20 N in three directions. Nineteen subjects participated: six novices (experience <60 arthroscopies), ten intermediates (>60 arthroscopies), and three faculty (>250 a year). All had to perform three tasks on each meniscus sample with an arthroscopic probe: push three times on the superior meniscal surface, perform one continuous run on the superior meniscal surface, and push three times on the inferior meniscal surface. The absolute maximum probing force (AMPF) was determined for each condition. A multivariable linear regression analysis was performed to assess the influence of experience on the force magnitude (P < 0.05). AMPFs were compared to the TMPF (estimated to be 8.5 N). Results The AMPF of the push task was on average 2.8 N (standard deviation (SD) of 0.8 N), of the continuous run task 2.5 N (SD 0.9 N), and of the pull task 3.9 N (SD 2.0 N). Significant difference was present between experts and novices (P < 0.05). The AMPFs are in the same order of magnitude as the TMPF. Conclusion The results indicate the necessity of using a safety level for tissue manipulation when training arthroscopy and a value for is magnitude.","safety; force; meniscus; arthroscopy","en","journal article","Springer","","","","","","","","Mechanical, Maritime and Materials Engineering","Biomechanical Engineering","","","",""
"uuid:09181a53-13a4-448f-ab14-55e78f2fe2e2","http://resolver.tudelft.nl/uuid:09181a53-13a4-448f-ab14-55e78f2fe2e2","The Neuromuscular System","Hosman, R.J.A.W.; Abbink, D.A.; Cardullo, F.M.","","2010","The aim of flight simulation is to create an environment for the pilot wherein he or she can perform the piloting task in such a way that the objective of the simulation, training or research, is reached. To simulate the flight environment in a simulator models describing the aircraft dynamic behavior and its systems, the atmosphere, the geographical and navigational environment, etc. are used. To fulfill his task, the pilot needs to perceive all relevant information and must have the means to control the simulated aircraft. This means that the pilot-aircraft interface, the cockpit with all its displays and controls, the aircraft motions, etc. has to be simulated accurately so that the pilot can perform in the simulator as in the real aircraft. Not only all cockpit systems have to provide the pilot with the proper stimulation of his senses but also the cockpit controls need to produce the proper control force-stick displacement characteristics. To make that possible not only all aircraft systems to be simulated have to be understood but also all human systems i.e. the characteristics of the senses (visual, vestibular, auditory, proprioceptive, etc.) and the actuation mechanisms have to be known. Based on this broad knowledge the pilot - aircraft interface for simulation can be specified, designed and employed. The MST Motion Working Group is currently documenting on the human capabilities and simulator systems. In this paper the neuromuscular system will be discussed. Both the physiology of the muscle and the sensors, the muscle spindle and the Golgi tendon organ, and the components of the nervous system regulating the force and position of the limb, as well as the adaptation of the neuromusculosketal system to the task requirements are discussed. Recently a neuromusculosketal system model was developed at Delft University. This model is used to explain the adaptation to three typical tasks in response to stick forces: resisting forces (maintaining a constant position), ignoring forces (minimizing muscle activity) and giving way to them (maintaining a constant force). Based on the model it is shown which parts of the system are adaptable and how the model parameters change to adapt the admittance, the external force/displacement characteristic, to the task.","","en","conference paper","American Institute of Aeronautics and Astronautics (AIAA)","","","","","","","","Mechanical, Maritime and Materials Engineering","Biomechanical Engineering","","","",""
"uuid:0193898b-74f5-4232-886e-d7a737dfa690","http://resolver.tudelft.nl/uuid:0193898b-74f5-4232-886e-d7a737dfa690","The relation between neuromechanical parameters and Ashworth score in stroke patients","De Vlugt, E.; De Groot, J.H.; Schenkeveld, K.E.; Arendzen, J.H.; Van der Helm, F.C.T.; Meskers, C.G.M.","","2010","Quantifying increased joint resistance into its contributing factors i.e. stiffness and viscosity (""hypertonia"") and stretch reflexes (""hyperreflexia"") is important in stroke rehabilitation. Existing clinical tests, such as the Ashworth Score, do not permit discrimination between underlying tissue and reflexive (neural) properties. We propose an instrumented identification paradigm for early and tailor made interventions.","OA-Fund TU Delft","en","journal article","BioMed Central","","","","","","","","Mechanical, Maritime and Materials Engineering","BioMechanical Engineering","","","",""
"uuid:e7c0bbf1-33da-4fdc-960f-5d15f47d7f20","http://resolver.tudelft.nl/uuid:e7c0bbf1-33da-4fdc-960f-5d15f47d7f20","Propulsion-unit and robot provided with such a propulsion-unit","Breedveld, P.; Dodou, D.","","2010","The invention relates to a propulsion-unit provided with a body and comprising at least one element having an external adhesive layer for providing frictional contact with an object's surface along which the unit in use moves, wherein the element is a supporting layer that supports said adhesive layer, and wherein drive means are provided for moving the supporting layer and the body with respect to each other.","","en","patent","European Patent Office","","","","","","","","Mechanical, Maritime and Materials Engineering","Biomechanical Engineering","","","",""
"uuid:bf75ced6-d0d8-48a8-ae79-b4cdf1cefc17","http://resolver.tudelft.nl/uuid:bf75ced6-d0d8-48a8-ae79-b4cdf1cefc17","Vacuum packed particles as flexible endoscope guides with controllable rigidity","Loeve, A.J.; Van de Ven, O.S.; Vogel, J.G.; Breedveld, P.; Dankelmann, J.","","2010","In order to fully benefit from the functionalities of flexible endoscopes in surgery a simple shaft-guide that can be used to support the flexible endoscope shaft is required. Such a shaft-guide must be flexible during insertion into the human body and rigidified when properly positioned to support the flexible endoscope shaft. A shaft-guide called ‘Vacu-SL’ was designed, consisting of a foil tube, filled with particles, that is rigidified by creating a vacuum in its tube. It is expected that the bending stiffness of a loaded, rigidified Vacu-SL shaft-guide is significantly influenced by the shape, hardness and size of the filler particles used. The goal of this study was to find the relations between the filler particles’ size, shape and hardness and a rigidified Vacu-SL shaft-guide’s bending stiffness. Vacu-SL test models were made using polystyrene, acrylic glass, glass, steel, and corundum particles as spheres, pebbles and granulate, with average diameters between 0.16–1.7 mm. These test models were rigidified and then loaded in a tensile tester. The forces needed for 5 and 10 mm deflections of the rigidified test models were measured. The results show that particle size, shape and hardness all influence a rigidified Vacu-SL shaft-guide’s bending stiffness. Size and hardness showed an optimum and granules performed better than spheres. Although the maximally measured bending stiffness might be insufficient to enable proper guidance of flexible endoscope shafts, the results suggest several ways to successfully improve the Vacu-SL shaft-guide.","Size; Shape; Hardness; Vacuum; Shaft-guide; Endoscopy","en","journal article","Springer","","","","","","","","Applied Sciences","Biomechanical Engineering","","","",""
"uuid:9219aa10-08e7-4143-8dd4-f7ae4aa659c4","http://resolver.tudelft.nl/uuid:9219aa10-08e7-4143-8dd4-f7ae4aa659c4","Design, fabrication, and preliminary results of a novel below knee prosthesis for snowboarding: A case report","Minnoye, A.L.M.; Plettenburg, D.H.","","2010","Snowboarding with a below-knee prosthesis is compromised by the limited rotation capabilities of the existing below-knee prostheses, which are designed for use in normal walking. Based on snowboarding range of motion analyses, a novel below-knee prosthesis was designed with the aim to achieve similar range of motions like able-bodied snowboarders. The new prosthesis allows for passive inversion/eversion, passive plantarflexion/dorsiflexion and additional ‘voluntary’ plantarflexion/dorsiflexion initiated by lateral or medial rotation of the upper leg and knee. A prototype was tested on a single subject, a professional snowboarder. The results indicate that snowboarding with the new prosthesis is more comparable to able-bodied snowboarding.","prosthetic design; prosthetic feet; rehabilitation of prostheses users; lower extremity prostheses; sports; snowboarding; bio-inspired design","en","journal article","Elsevier","","","","","","","","Mechanical, Maritime and Materials Engineering","Biomechanical Engineering","","","",""
"uuid:8b60b894-f85d-411b-9662-4513753313be","http://resolver.tudelft.nl/uuid:8b60b894-f85d-411b-9662-4513753313be","Hands-on experience of manual control in a human-machine systems engineering course","De Winter, J.C.F.; Dodou, D.; De Groot, S.; Abbink, D.A.; Wieringa, P.A.","","2010","This paper presents the results of integrating hands-on experience in an engineering MSc course on human-machine systems. Students could voluntarily complete a homework assignment in which they performed manual control tasks using dedicated software. The tasks were accompanied by questions that students had to answer using the theory taught in the lectures. The lecturer processed the students’ recorded data and presented the results in class. One-and-a-half month after the completion of the assignment, students took a written exam on all topics of the course, including manual control theory. Students (n = 32) reported in a questionnaire that the assignment was valuable in improving their understanding of manual control (mean = 7.80, SD = 1.53 on a 10-point scale with anchors at 1 (poor) and 10 (excellent)). A correlation analysis of assignment participation, questionnaire responses, assignment grades, and exam scores is reported as well.","","en","conference paper","","","","","","","","","Mechanical, Maritime and Materials Engineering","BioMechanical Engineering","","","",""
"uuid:17f32317-dbd1-47ef-87aa-58c2a250bc8c","http://resolver.tudelft.nl/uuid:17f32317-dbd1-47ef-87aa-58c2a250bc8c","Left turn gap acceptance in a simulator: Driving skill or driving style?","De Winter, J.C.F.; Spek, A.C.E.; De Groot, S.; Wieringa, P.A.","","2010","This paper describes two driving simulator experiments on left turn gap acceptance at intersections. In the first experiment, participants (N = 24) had to turn left at 25 intersections and cross an approaching traffic stream of 25 equally-spaced vehicles, with a different combination of intervehicle gap time and approach speed at each intersection. In the second experiment (N = 20), gap time and approach speed differed also within each intersection stream. The first hypothesis that licensed drivers (who are assumed to have better perceptual skills) would more take into account approaching vehicles’ speed in their gap acceptance decisions than unlicensed drivers was moderately supported in the second experiment. Additionally, it was found that unlicensed drivers accepted significantly shorter gap times, significantly later in the stream of approaching vehicles. The second hypothesis that drivers who had higher self-reported violating behaviour (i.e., a poorer driving style) would be inclined to accept shorter gap times than drivers with a low violation score was not accepted. However, in the second experiment, drivers with higher violation scores were found to accept gaps that were earlier in the stream. In summary, results showed that both driving skill (i.e., having a driving licence) and driving style (i.e., violation scores) correlated with gap acceptance in a simulator. Some complicating factors, such as non-perceptual effects of driving skill, interactions between driving skill and driving style, and simulator fidelity, are discussed.","","en","conference paper","","","","","","","","","Mechanical, Maritime and Materials Engineering","BioMechanical Engineering","","","",""
"uuid:a8904771-a428-4460-9c7f-2fcc98713823","http://resolver.tudelft.nl/uuid:a8904771-a428-4460-9c7f-2fcc98713823","An analysis of braking measures","De Groot, S.; De Winter, J.C.F.; Wieringa, P.A.; Mulder, M.","","2010","Braking to a full stop at a prescribed target position is a driving manoeuvre regularly used in experiments to investigate driving behaviour or to test vehicle acceleration feedback systems in simulators. Many different performance measures have been reported in the literature for analysing braking. These may or may not be useful to analyse the stopping manoeuvre, because a number of potential problems exist: 1) the scores on a measure may be insufficiently reliable, 2) the measure may be invalid, or 3) the measure may be strongly intercorrelated. A simulation and empirical study were conducted to analyse various measures. From the simulation study it was concluded that 1) An R2 measure based on the speed vs time relationship can be used to measure deviations from a constant deceleration, 2) minimum time-to-collision is sensitive to target position offsets, and 3) mean TTC-dot can capture braking behaviour characteristics but the required definition of a begin and end sample-point for its calculation is a disadvantage. The empirical study calculated a set of measures using data of 60 participants driving a simulation-based session of 10 stops. It is concluded that reliable and valid measures for a braking experiment are provided by the speed and distance to the target position at braking onset, the stopping position with respect to the target and the R2 measure to measure deviations from a constant deceleration. Recommended additional measures are: The mean speed of the complete braking manoeuvre, stopping position consistency, maximum deceleration and onset jerk.","","en","conference paper","","","","","","","","","Mechanical, Maritime and Materials Engineering","BioMechanical Engineering","","","",""
"uuid:e81ef586-f0c9-40d6-acbd-f1ec8ea752e6","http://resolver.tudelft.nl/uuid:e81ef586-f0c9-40d6-acbd-f1ec8ea752e6","Force measurement platform for training and assessment of laparoscopic skills","Horeman, T.; Rodrigues, S.P.; Jansen, F.W.; Dankelman, J.; Van den Dobbelsteen, J.J.","","2010","Background - To improve endoscopic surgical skills, an increasing number of surgical residents practice on box or virtual-reality (VR) trainers. Current training is mainly focused on hand–eye coordination. Training methods that focus on applying the right amount of force are not yet available. Methods - The aim of this project is to develop a system to measure forces and torques during laparoscopic training tasks as well as the development of force parameters that assess tissue manipulation tasks. The force and torque measurement range of the developed force platform are 0–4 N and 1 Nm (torque), respectively. To show the potential of the developed force platform, a pilot study was conducted in which five surgeons experienced in intracorporeal suturing and five novices performed a suture task in a box trainer. Results - During the pilot study, the maximum and mean absolute nonzero force that the novice used were 4.7 N (SD 1.3 N) and 2.1 N (SD 0.6 N), respectively. With a maximum force of 2.6 N (SD 0.4 N) and mean nonzero force of 0.9 N (SD 0.3 N), the force exerted by the experts was significantly lower.","minimally invasive surgery; laparoscopy; box trainers; force feedback; training methods","en","journal article","Springer","","","","","","","","Mechanical, Maritime and Materials Engineering","Biomechanical Engineering","","","",""
"uuid:a446a509-c221-41ad-94b0-1afe3aafc4d9","http://resolver.tudelft.nl/uuid:a446a509-c221-41ad-94b0-1afe3aafc4d9","System provided with an assistance-controller for assisting an operator of the system, control-operation assisting device, control-operation assisting method, driving-operation assisting device, and driving-operation assisting method","Mulder, M.; Abbink, D.; Van Paassen, R.; Mulder, M.; Van der Helm, F.; Boer, E.R.; Takada, Y.","","2010","A target-travel-path generating circuit calculates a target travel path along which the controlled object can travel in the future from the current controlled object position, an ideal-control-signal calculating circuit calculates a control profile S to travel along the target travel path P, and a difference calculating circuit calculates a difference d between the ideal control magnitude S and a current control magnitude S. An operation system assistance controller controls the operation system based on the magnitude of the calculated difference d to assist the control operation of the operator, the control-operation-state of the operator, the environment-state, and the required operation-precision. Accordingly, it is possible to provide the operator with control operation assistance that is a function of the magnitude of the difference d from an ideal control state, the control-operation-state of the operator, the environment-state, and the required operation-precision, and thus, a control-operation assistance control can be outputted that is suitable for the conditions that characterize the state of the operator, the environment, and the controlled object.","","en","patent","European Patent Office","","","","","","","","Mechanical, Maritime and Materials Engineering","Biomechanical Engineering","","","",""
"uuid:164d8e28-76a7-4459-b6a8-1ca298296720","http://resolver.tudelft.nl/uuid:164d8e28-76a7-4459-b6a8-1ca298296720","Neuromuscular Analysis as a Guideline in designing Shared Control","Abbink, D.A.; Mulder, M.","","2010","","","en","book chapter","InTech","","","","","","","","Mechanical, Maritime and Materials Engineering","BioMechanical Engineering","","","",""
"uuid:dc35d9a7-d9e3-42fe-bdde-8247a478c661","http://resolver.tudelft.nl/uuid:dc35d9a7-d9e3-42fe-bdde-8247a478c661","Intrinsically Safe Robot Arm: Adjustable Static Balancing and Low Power Actuation","Vermeulen, M.; Wisse, M.","","2010","We present a design for a manipulator that is intrinsically mechanically safe, i.e. it can not cause pain (let alone damage) to a human being even if the control system has a failure. Based on the pressure pain thresholds for human skin, we derive a pinching safety constraint that limits the actuator torque, and an impact safety constraint that results in a trade-off between mass and velocity. To fulfill all constraints, the manipulator requires a spring balancing system that counteracts gravity in all configurations of the manipulator. This allows the use of extremely low-power DC motors (only 4.5 W). Thanks to the torque and speed limitations of these motors the manipulator is indeed intrinsically safe, yet still capable of moving a useful payload of 1.2 kg over a distance of 0.8 m in 1.5 s.","safe robot; gravity compensation; gravity balancing; low power robot; manipulator","en","journal article","Springer","","","","","","","","Mechanical, Maritime and Materials Engineering","Biomechanical Engineering","","","",""
"uuid:c8ce4ad2-e961-46cc-87ed-f606c80661fa","http://resolver.tudelft.nl/uuid:c8ce4ad2-e961-46cc-87ed-f606c80661fa","An explorative, cross-sectional study into abnormal muscular coupling during reach in chronic stroke patients","Prange, G.B.; Jannink, M.J.A.; Stienen, A.H.A.; Van der Kooij, H.; IJzerman, M.J.; Hermens, H.J.","","2010","Background: In many stroke patients arm function is limited, which can be related to an abnormal coupling between shoulder and elbow joints. The extent to which this can be translated to activities of daily life (ADL), in terms of muscle activation during ADL-like movements, is rather unknown. Therefore, the present study examined the occurrence of abnormal coupling on functional, ADL-like reaching movements of chronic stroke patients by comparison with healthy persons. Methods: Upward multi-joint reaching movements (20 repetitions at a self-selected speed to resemble ADL) were compared in two conditions: once facilitated by arm weight compensation and once resisted to provoke a potential abnormal coupling. Changes in movement performance (joint angles) and muscle activation (amplitude of activity and co-activation) between conditions were compared between healthy persons and stroke patients using a repeated measures ANOVA. Results: The present study showed slight changes in joint excursion and muscle activation of stroke patients due to shoulder elevation resistance during functional reach. Remarkably, in healthy persons similar changes were observed. Even the results of a sub-group of the more impaired stroke patients did not point to an abnormal coupling between shoulder elevation and elbow flexion during functional reach. Conclusions: The present findings suggest that in mildly and moderately affected chronic stroke patients ADL-like arm movements are not substantially affected by abnormal synergistic coupling. In this case, it is implied that other major contributors to limitations in functional use of the arm should be identified and targeted individually in rehabilitation, to improve use of the arm in activities of daily living.","","en","journal article","BioMed Central","","","","","","","","Mechanical, Maritime and Materials Engineering","Biomechanical Engineering","","","",""
"uuid:db0b7a06-bb8d-4e5c-a6cc-7f7b814c4c1b","http://resolver.tudelft.nl/uuid:db0b7a06-bb8d-4e5c-a6cc-7f7b814c4c1b","Recycling Energy to Restore Impaired Ankle Function during Human Walking","Collins, S.H.; Kuo, A.D.","","2010","Background: Humans normally dissipate significant energy during walking, largely at the transitions between steps. The ankle then acts to restore energy during push-off, which may be the reason that ankle impairment nearly always leads to poorer walking economy. The replacement of lost energy is necessary for steady gait, in which mechanical energy is constant on average, external dissipation is negligible, and no net work is performed over a stride. However, dissipation and replacement by muscles might not be necessary if energy were instead captured and reused by an assistive device. Methodology/Principal Findings: We developed a microprocessor-controlled artificial foot that captures some of the energy that is normally dissipated by the leg and ‘‘recycles’’ it as positive ankle work. In tests on subjects walking with an artificially-impaired ankle, a conventional prosthesis reduced ankle push-off work and increased net metabolic energy expenditure by 23% compared to normal walking. Energy recycling restored ankle push-off to normal and reduced the net metabolic energy penalty to 14%. Conclusions/Significance: These results suggest that reduced ankle push-off contributes to the increased metabolic energy expenditure accompanying ankle impairments, and demonstrate that energy recycling can be used to reduce such cost.","","en","journal article","Public Library of Science","","","","","","","","Mechanical, Maritime and Materials Engineering","Biomechanical Engineering","","","",""
"uuid:cb36e3f3-de76-40b2-b996-94abebc8ce63","http://resolver.tudelft.nl/uuid:cb36e3f3-de76-40b2-b996-94abebc8ce63","The intermuscular 3–7 Hz drive is not affected by distal proprioceptive input in myoclonus-dystonia","Van der Meer, J.N.; Schouten, A.C.; Bour, L.J.; De Vlugt, E.; Van Rootselaar, A.F.; Van der Helm, F.C.T.; Tijssen, M.A.J.","","2010","In dystonia, both sensory malfunctioning and an abnormal intermuscular low-frequency drive of 3–7 Hz have been found, although cause and eVect are unknown. It is hypothesized that sensory processing is primarily disturbed and induces this drive. Accordingly, experimenter-controlled sensory input should be able to inXuence the frequency of the drive. In six genetically conWrmed myoclonus-dystonia (MD) patients and six matched controls, the low-frequency drive was studied with intermuscular coherence analysis. External perturbations were applied mechanically to the wrist joint in small frequency bands (0–4, 4–8 and 8–12 Hz; ‘angle protocol) and at single frequencies (1, 5, 7 and 9 Hz; ‘torque’ protocol). The low-frequency drive was found in the neck muscles of 4 MD patients. In these patients, its frequency did not shift due to the perturbation. In the torque protocol, the externally applied frequencies could be detected in all controls and in the two patients without the common drive. The common low-frequency drive was not be aVected by external perturbations in MD patients. Furthermore, the torque protocol did not induce intermuscular coherences at the applied frequencies in these patients, as was the case in healthy controls and in patients without the drive. This suggests that the dystonic 3–7 Hz drive is caused by a sensory-independent motor drive and sensory malfunctioning in MD might rather be a consequence than a cause of dystonia.","EEG; EMG; Dystonia; Proprioception; Sensorimotor integration","en","journal article","Springer","","","","","","","","Applied Sciences","Biomechanical Engineering","","","",""
"uuid:5672673a-9667-4ba6-94b4-7556feb56b18","http://resolver.tudelft.nl/uuid:5672673a-9667-4ba6-94b4-7556feb56b18","An Isolator System for minimally invasive surgery: The new design","Horeman, T.; Jansen, F.W.; Dankelman, J.","","2010","Background - The risk of obtaining a postsurgical infection depends highly on the air quality surrounding the exposed tissue, surgical instruments, and materials. Many isolators for open surgery have been invented to create a contained sterile volume around the exposed tissue. With the use of an isolator, a surgical procedure can be performed outside sterile environments. The goal of this study was to design an Isolator System (IS) for standard laparoscopic instruments while instrument movements are not restricted. Methods - The developed IS consists of a sleeve to protect the instrument shaft and tip and a special balloon to protect the incision and trocar tube. A coupling mechanism connected at the sleeve allows instrument changes without contamination of the isolated parts. Smoke tests were performed to show that outside air does not enter the new IS during a simulated laparoscopic procedure. Eight test runs and one baseline run inside a contained volume filled with thick smoke were performed to investigate whether smoke particles entered the Isolator System. Filters were used to identify smoke entering the Isolator System. Results - Seven filters showed no trace of smoke particles. In one test run, a part of the IS loosened and a small brown spot was visible. The filter from the baseline run was completely covered with a thick layer of particles, proving the effectiveness of the test. During all test runs, the isolated instrument was successfully locked on and unlocked from the isolated trocar. Instrument movements gave no complications. After removal of the isolated instrument, it took three novices an average of 3.1 (standard deviation (SD), 0.7) seconds to replace it correctly on the isolated trocar. Conclusions - The designed IS for laparoscopy can increase sterility in environments where sterility cannot be guaranteed. The current design is developed for laparoscopy, but it can easily be adapted for other fields in minimally invasive surgery.","laparoscopy; minimally invasive surgery; isolator systems; infection prevention; trocar friction","en","journal article","Springer","","","","","","","","Mechanical, Maritime and Materials Engineering","Biomechanical Engineering","","","",""
"uuid:eb90135c-36aa-4de0-8057-c4d026abcf42","http://resolver.tudelft.nl/uuid:eb90135c-36aa-4de0-8057-c4d026abcf42","Discovery of high-level tasks in the operating room","Bouarfa, L.; Jonker, P.P.; Dankelman, J.","","2010","Recognizing and understanding surgical high-level tasks from sensor readings is important for surgical workflow analysis. Surgical high-level task recognition is also a challenging task in ubiquitous computing because of the inherent uncertainty of sensor data and the complexity of the operating room environment. In this paper, we present a framework for recognizing high-level tasks from low-level noisy sensor data. Specifically, we present a Markov-based approach for inferring high-level tasks from a set of low-level sensor data. We also propose to clean the noisy sensor data using a Bayesian approach. Preliminary results on a noise-free dataset of ten surgical procedures show that it is possible to recognize surgical high-level tasks with detection accuracies up to 90%. Introducing missed and ghost errors to the sensor data results in a significant decrease of the recognition accuracy. This supports our claim to use a cleaning algorithm before the training step. Finally, we highlight exciting research directions in this area.","ubiquitous computing; activity recognition; high-level activity; cognitive environment; Hidden Markov Model; surgical workflow; noisy sensors; uncertainty; Bayesian networks","en","journal article","Elsevier","","","","","","","","Mechanical, Maritime and Materials Engineering","Biomechanical Engineering","","","",""
"uuid:def9e955-cda6-4dd2-85ea-54112c53379f","http://resolver.tudelft.nl/uuid:def9e955-cda6-4dd2-85ea-54112c53379f","Tizanidine does not affect the linear relation of stretch duration to the long latency M2 response of m. flexor carpi radialis","Meskers, C.G.M.; Schouten, A.C.; Rich, M.M.L.; De Groot, J.H.; Schuurmans, J.; Arendzen, J.H.","","2009","The long latency M2 electromyographic response of a suddenly stretched active muscle is stretch duration dependent of which the nature is unclear. We investigated the inXuence of the group II aVerent blocker tizanidine on M2 response characteristics of the m. Xexor carpi radialis (FCR). M2 response magnitude and eliciting probability in a group of subjects receiving 4 mg of tizanidine orally were found to be signiWcantly depressed by tizanidine while tizanidine did not aVect the signiWcant linear relation of the M2 response to stretch duration. The eVect of tizanidine on the M2 response of FCR is supportive of a group II aVerent contribution to a compound response of which the stretch duration dependency originates from a diVerent mechanism, e.g., rebound Ia Wring.","M2 response; II aVerent; Stretch reXex; Tizanidine","en","journal article","Springer","","","","","","","","Applied Sciences","Biomechanical Engineering","","","",""
"uuid:9e22f784-5741-4a73-aeb5-7e8bf8c92c56","http://resolver.tudelft.nl/uuid:9e22f784-5741-4a73-aeb5-7e8bf8c92c56","Augmented Reality for Art, Design and Cultural Heritage: System Design and Evaluation","Caarls, J.; Jonker, P.; Kolstee, Y.; Rotteveel, J.; Van Eck, W.","","2009","This paper describes the design of an optical see-through head-mounted display (HMD) system for Augmented Reality (AR). Our goals were to make virtual objects “perfectly” indistinguishable from real objects, wherever the user roams, and to find out to which extent imperfections are hindering applications in art and design. For AR, fast and accurate measuring of head motions is crucial. We made a head-pose tracker for the HMD that uses error-state Kalman filters to fuse data from an inertia tracker with data from a camera that tracks visual markers. This makes on-line head-pose based rendering of dynamic virtual content possible. We measured our system, and found that with an A4-sized marker viewed from > 20? at 5m distance with an SXGA camera (FOV 108?), the RMS error in the tracker angle was < 0.5? when moving the head slowly. Our Kalman filters suppressed the pose error due to camera delay, which is proportional to the angular and linear velocities, and the dynamic misalignment was comparable to the static misalignment. Applications of artists and designers lead to observations on the profitable use of our AR system. Their exhibitions at world-class museums showed that AR is a powerful tool for disclosing cultural heritage.","","en","journal article","Hindawi Publishing Corporation","","","","","","","","Mechanical, Maritime and Materials Engineering","Biomechanical Engineering","","","",""
"uuid:a6d88455-53cc-474b-9c49-a2b0a2ca40b7","http://resolver.tudelft.nl/uuid:a6d88455-53cc-474b-9c49-a2b0a2ca40b7","Objective classification of residents based on their psychomotor laparoscopic skills","Chmarra, M.K.; Klein, S.; De Winter, J.C.F.; Jansen, F.W.; Dankelman, J.","","2009","Background - From the clinical point of view, it is important to recognize residents’ level of expertise with regard to basic psychomotor skills. For that reason, surgeons and surgical organizations (e.g., Acreditation Council for Graduate Medical Education, ACGME) are calling for assessment tools that credential residents as technically competent. Currently, no method is universally accepted or recommended for classifying residents as ‘‘experienced,’’ ‘‘intermediates,’’ or ‘‘novices’’ according to their technical abilities. This study introduces a classification method for recognizing residents’ level of experience in laparoscopic surgery based on psychomotor laparoscopic skills alone. Methods - For this study, 10 experienced residents (>100 laparoscopic procedures performed), 10 intermediates (10– 100 procedures performed), and 11 novices (no experience) performed four tasks in a box trainer. The movements of the laparoscopic instruments were recorded with the TrEndo tracking system and analyzed using six motion analysis parameters (MAPs). The MAPs of all participants were submitted to principal component analysis (PCA), a data reduction technique. The scores of the first principal components were used to perform linear discriminant analysis (LDA), a classification method. Performance of the LDA was examined using a leave-one-out crossvalidation. Results - Of 31 participants, 23 were classified correctly with the proposed method, with 7 categorized as experienced, 7 as intermediates, and 9 as novices. Conclusions - The proposed method provides a means to classify residents objectively as experienced, intermediate, or novice surgeons according to their basic laparoscopic skills. Due to the simplicity and generalizability of the introduced classification method, it is easy to implement in existing trainers.","assessment; classification; minimally invasive surgery; motion analysis; training","en","journal article","Springer","","","","","","","","Mechanical, Maritime and Materials Engineering","Biomechanical Engineering","","","",""
"uuid:28b9efe5-8650-476e-98e5-74991bb215df","http://resolver.tudelft.nl/uuid:28b9efe5-8650-476e-98e5-74991bb215df","A rigorous model of reflex function indicates that position and force feedback are flexibly tuned to position and force tasks","Mugge, W.; Abbink, D.A.; Schouten, A.C.; Dewald, J.P.A.; Van der Helm, F.C.T.","","2009","This study aims to quantify the separate contributions of muscle force feedback, muscle spindle activity and co-contraction to the performance of voluntary tasks (‘‘reduce the influence of perturbations on maintained force or position’’). Most human motion control studies either isolate only one contributor, or assume that relevant reflexive feedback pathways during voluntary disturbance rejection tasks originate mainly from the muscle spindle. Human ankle-control experiments were performed, using three task instructions and three perturbation characteristics to evoke a wide range of responses to force perturbations. During position tasks, subjects (n = 10) resisted the perturbations, becoming more stiff than when being relaxed (i.e., the relax task). During force tasks, subjects were instructed to minimize force changes and actively gave way to imposed forces, thus becoming more compliant than during relax tasks. Subsequently, linear physiological models were fitted to the experimental data. Inhibitory, as well as excitatory force feedback, was needed to account for the full range of measured experimental behaviors. In conclusion, force feedback plays an important role in the studied motion control tasks (excitatory during position tasks and inhibitory during force tasks), implying that spindle-mediated feedback is not the only significant adaptive system that contributes to the maintenance of posture or force.","human motion control; neuromusculoskeletal modeling; afferent feedback; Golgi tendon organs; muscle spindles; muscle force feedback","en","journal article","Springer","","","","","","","","Mechanical, Maritime and Materials Engineering","Biomechanical Engineering","","","",""
"uuid:255f7330-a144-45f7-9d39-4fc861d5f680","http://resolver.tudelft.nl/uuid:255f7330-a144-45f7-9d39-4fc861d5f680","The videolaryngoscope is less traumatic than the classic laryngoscope for a difficult airway in an obese patient","Maassen, R.; Lee, R.; Van Zundert, A.; Cooper, R.","","2009","This report describes the anesthetic management of an obese patient with a difficult airway and the merits of videolaryngoscopy, specifically in terms of the reduced risk of dental damage during intubation. A 49-year-old woman (body mass index; BMI, 36 kg·m?2), was scheduled to undergo an elective laparoscopic cholecystectomy because of cholelithiasis. Based upon the obesity of the patient and preoperative metrics (Mallampati grade IV; interdental distance of 2.9 cm; thyromental distance, 5.5 cm) a difficult airway was anticipated. Classic direct laryngoscopy using a Macintosh blade size IV failed, despite three intubation attempts—each resulting in a Cormack-Lehane grade IV view. Intubation using a video-assisted Macintosh laryngoscope (V-Mac; Karl Storz, Tuttlingen, Germany) was successful upon the first attempt. The maximum force exerted on the patient’s maxillary incisors was 61 N by direct laryngoscopy and 7.6 N using the indirect videolaryngoscope, both using a Macintosh blade.","General anesthesia; Intubation; Videolaryngoscopy; Difficult airway; Force measurement","en","journal article","Springer","","","","","","","","Mechanical, Maritime and Materials Engineering","Biomechanical Engineering","","","",""
"uuid:74569c39-b587-4175-af36-82722b8a4c0e","http://resolver.tudelft.nl/uuid:74569c39-b587-4175-af36-82722b8a4c0e","First validation of the PASSPORT training environment for arthroscopic skills","Tuijthoff, G.J.M.; Van Sterkenburg, M.N.; Sierevelt, I.N.; Van Oldenrijk, J.; Van Dijk, C.N.; Kerkhoffs, G.M.M.J.","","2009","The demand for high quality care is in contrast to reduced training time for residents to develop arthroscopic skills. Thereto, simulators are introduced to train skills away from the operating room. In our clinic, a physical simulation environment to Practice Arthroscopic Surgical Skills for Perfect Operative Real-life Treatment (PASSPORT) is being developed. The PASSPORT concept consists of maintaining the normal arthroscopic equipment, replacing the human knee joint by a phantom, and integrating registration devices to provide performance feedback. The first prototype of the knee phantom allows inspection, treatment of menisci, irrigation, and limb stressing. PASSPORT was evaluated for face and construct validity. Construct validity was assessed by measuring the performance of two groups with different levels of arthroscopic experience (20 surgeons and 8 residents). Participants performed a navigation task five times on PASSPORT. Task times were recorded. Face validity was assessed by completion of a short questionnaire on the participants’ impressions and comments for improvements. Construct validity was demonstrated as the surgeons (median task time 19.7 s [8.0–37.6]) were more efficient than the residents (55.2 s [27.9–96.6]) in task completion for each repetition (Mann–Whitney U test, P < 0.05). The prototype of the knee phantom sufficiently imitated limb outer appearance (79%), portal resistance (82%), and arthroscopic view (81%). Improvements are required for the stressing device and the material of cruciate ligaments. Our physical simulation environment (PASSPORT) demonstrates its potential to evolve as a training modality. In future, automated performance feedback is aimed for.","Arthroscopy; Skills; Simulator; Training; Validity; Knee","en","journal article","Springer","","","","","","","","Applied Sciences","Biomechanical Engineering","","","",""
"uuid:4d003efb-92af-42f0-b370-ebf40a112687","http://resolver.tudelft.nl/uuid:4d003efb-92af-42f0-b370-ebf40a112687","Muscle weakness and lack of reflex gain adaptation predominate during post-stroke posture control of the wrist","Meskers, C.G.M.; Schouten, A.C.; De Groot, J.H.; De Vlugt, E.; Van Hilten, B.J.J.; Van der Helm, F.C.T.; Arendzen, H.J.H.","","2009","Background Instead of hyper-reflexia as sole paradigm, post-stroke movement disorders are currently considered the result of a complex interplay between neuronal and muscular properties, modified by level of activity. We used a closed loop system identification technique to quantify individual contributors to wrist joint stiffness during an active posture task. Methods Continuous random torque perturbations applied to the wrist joint by a haptic manipulator had to be resisted maximally. Reflex provoking conditions were applied i.e. additional viscous loads and reduced perturbation signal bandwidth. Linear system identification and neuromuscular modeling were used to separate joint stiffness into the intrinsic resistance of the muscles including co-contraction and the reflex mediated contribution. Results Compared to an age and sex matched control group, patients showed an overall 50% drop in intrinsic elasticity while their reflexive contribution did not respond to provoking conditions. Patients showed an increased mechanical stability compared to control subjects.","","en","journal article","BioMed Central","","","","","","","","Mechanical, Maritime and Materials Engineering","Biomechanical Engineering","","","",""
"uuid:e6625561-b41e-4002-a5b9-15f0ea36acb9","http://resolver.tudelft.nl/uuid:e6625561-b41e-4002-a5b9-15f0ea36acb9","A Semianalytical Approach to Large Deflections in Compliant Beams under Point Load","Tolou, N.; Herder, J.L.","","2009","The deflection of compliant mechanism (CM) which involves geometrical nonlinearity due to large deflection of members continues to be an interesting problem in mechanical systems. This paper deals with an analytical investigation of large deflections in compliant mechanisms. The main objective is to propose a convenient method of solution for the large deflection problem in CMs in order to overcome the difficulty and inaccuracy of conventional methods, as well as for the purpose of mathematical modeling and optimization. For simplicity, an element is considered which is a cantilever beam out of linear elastic material under vertical end point load. This can further be used as a building block inmore complex compliant mechanisms. First, the governing equation has been obtained for the cantilever beam; subsequently, the Adomian decomposition method (ADM) has been utilized to obtain a semianalytical solution. The vertical and horizontal displacements of a cantilever beam can conveniently be obtained in an explicit analytical form. In addition, variations of the parameters that affect the characteristics of the deflection have been examined. The results reveal that the proposed procedure is very accurate, efficient, and convenient for cantilever beams, and can probably be applied to a large class of practical problems for the purpose of analysis and optimization.","","en","journal article","Hindawi Publishing Corporation","","","","","","","","Mechanical, Maritime and Materials Engineering","Biomechanical Engineering","","","",""
"uuid:8f607e6a-a432-4421-8d51-52e554380049","http://resolver.tudelft.nl/uuid:8f607e6a-a432-4421-8d51-52e554380049","Energy efficient walking with central pattern generators: From passive dynamic walking to biologically inspired control","Verdaasdonk, B.W.; Koopman, H.F.J.M.; Van der Helm, F.C.T.","","2009","Like human walking, passive dynamic walking—i.e. walking down a slope with no actuation except gravity—is energy efficient by exploiting the natural dynamics. In the animal world, neural oscillators termed central pattern generators (CPGs) provide the basic rhythm for muscular activity in locomotion. We present a CPG model, which automatically tunes into the resonance frequency of the passive dynamics of a bipedal walker, i.e. the CPG model exhibits resonance tuning behavior. Each leg is coupled to its own CPG, controlling the hip moment of force. Resonance tuning above the endogenous frequency of the CPG—i.e. the CPG’s eigenfrequency—is achieved by feedback of both limb angles to their corresponding CPG, while integration of the limb angles provides resonance tuning at and below the endogenous frequency of the CPG. Feedback of the angular velocity of both limbs to their corresponding CPG compensates for the time delay in the loop coupling each limb to its CPG. The resonance tuning behavior of the CPG model allows the gait velocity to be controlled by a single parameter, while retaining the energy efficiency of passive dynamic walking.","Legged locomotion; Central pattern generator; Resonance tuning; Energy efficiency; Passive dynamic walking; Route to chaos","en","journal article","Springer","","","","","","","","Mechanical, Maritime and Materials Engineering","Biomechanical Engineering","","","",""
"uuid:0b66b626-c2a0-4eb4-87c6-ba4fabad93a3","http://resolver.tudelft.nl/uuid:0b66b626-c2a0-4eb4-87c6-ba4fabad93a3","Sensory Weighting of Force and Position Feedback in Human Motor Control Tasks","Mugge, W.; Schuurmans, J.; Schouten, A.C.; Van der Helm, F.C.T.","","2009","In daily life humans integrate force and position feedback from mechanoreceptors, proprioception, and vision. With handling relatively soft, elastic objects, force and position are related and can be integrated to improve the accuracy of an estimate of either one. Sensory weighting between different sensory systems (e.g., vision and proprioception) has been extensively studied. This study investigated whether similar weighting can be found within the proprioceptive sensory system, more specifically between the modalities force and position. We hypothesized that sensory weighting is governed by object stiffness: position feedback is weighted heavier on soft objects (large deflections), while force feedback is weighted heavier on stiff objects (small deflections). Subjects were instructed to blindly reproduce either position or force while holding a one degree of freedom haptic manipulator that simulated a linear spring with one of four predetermined stiffnesses. In catch trials the spring was covertly replaced by a nonlinear spring. The difference in force (?F) and position (?X) between the regular and the catch trials revealed the sensory weighting between force and position feedback. A maximum likelihood estimation model predicted that: (1) task instruction did not affect the outcome measures, and (2) force feedback is weighted heavier with increasing object stiffness as was hypothesized. Both effects were found experimentally, and the subjects’ sensory weighting closely resembled the optimal model predictions. To conclude, this study successfully demonstrated sensory weighting within the proprioceptive system.","","en","journal article","Society for Neuroscience","","","","","","","","Mechanical, Maritime and Materials Engineering","Biomechanical Engineering","","","",""
"uuid:918a6c1e-e841-4aa8-a91e-8aa4e59dfe9f","http://resolver.tudelft.nl/uuid:918a6c1e-e841-4aa8-a91e-8aa4e59dfe9f","The monosynaptic Ia afferent pathway can largely explain the stretch duration effect of the long latency M2 response","Schuurmans, J.; De Vlugt, E.; Schouten, A.C.; Meskers, C.G.; De Groot, J.H.; Van der Helm, F.C.T.","","2009","Sudden stretch of active muscle typically results in two characteristic electromyographic responses: the short latency M1 and the long latency M2. The M1 response originates from the monosynaptic Ia afferent reflex pathway. The M2 response is less well understood and is likely a compound response to different afferent inputs mediated by spinal and transcortical pathways. In this study the possible contribution of the Ia afferent pathway to the M2 response was investigated. A mechanism was hypothesized in which the M1 response synchronizes the motoneurons, and therewith their refractory periods. Stretch perturbation experiments were performed on the wrist and results were compared with a computational model of a pool of motoneurons receiving tonic and Ia afferent input. The simulations showed the same stretch amplitude, velocity, and duration-dependent characteristics on the M2 as found experimentally. It was concluded that the stretch duration effect of the M2 likely originates from the proposed Ia afferent mediated mechanism.","reflexes; neural modeling","en","journal article","Springer","","","","","","","","Mechanical, Maritime and Materials Engineering","Biomechanical Engineering","","","",""
"uuid:d5f04e70-37aa-4a53-8e8d-af17cc402d1e","http://resolver.tudelft.nl/uuid:d5f04e70-37aa-4a53-8e8d-af17cc402d1e","Advancing simulation-based driver training","De Winter, J.C.F.","Wieringa, P.A. (promotor); Mulder, J.A. (promotor)","2009","","","en","doctoral thesis","","","","","","","","2010-02-01","Mechanical, Maritime and Materials Engineering","BioMechanical Engineering","","","",""
"uuid:c116e30f-cd01-4543-b7c9-4affe7a21c50","http://resolver.tudelft.nl/uuid:c116e30f-cd01-4543-b7c9-4affe7a21c50","Impact of early applied upper limb stimulation: The EXPLICIT-stroke programme design","Kwakkel, G.; Meskers, C.G.M.; Van Wegen, E.E.; Lankhorst, G.J.; Geurts, A.C.H.; Van Kuijk, A.A.; Lindeman, E.; Visser-Meily, A.; Vlugt, E.; Arendzen, J.H.","","2008","Main claims of the literature are that functional recovery of the paretic upper limb is mainly defined within the first month post stroke and that rehabilitation services should preferably be applied intensively and in a task-oriented way within this particular time window. EXplaining PLastICITy after stroke (acronym EXPLICIT-stroke) aims to explore the underlying mechanisms of post stroke upper limb recovery. Two randomized single blinded trials form the core of the programme, investigating the effects of early modified Constraint-Induced Movement Therapy (modified CIMT) and EMG-triggered Neuro-Muscular Stimulation (EMG-NMS) in patients with respectively a favourable or poor probability for recovery of dexterity.","OA-Fund TU Delft","en","journal article","BioMed Central","","","","","","","","Mechanical, Maritime and Materials Engineering","BioMechanical Engineering","","","",""
"uuid:7b8d1b1c-4bce-4b3d-a3eb-78db5b4b5947","http://resolver.tudelft.nl/uuid:7b8d1b1c-4bce-4b3d-a3eb-78db5b4b5947","An Electric Scooter Simulation Program for Training the Driving Skills of Stroke Patients with Mobility Problems: A Pilot Study","Jannink, M.J.A.; Erren-Wolters, C.V.; De Kort, A.C.; Van der Kooij, H.","","2008","This paper describes an electric scooter simulation program and a first evaluation study in which we explored if it is possible to train the driving skills of future users of electric mobility scooters by means of an electric scooter simulation program in addition to conventional electric scooter training. Within this explorative study, 10 stroke survivors were randomly assigned to either the control (n = 5) or the electric scooter simulation intervention group (n = 5). Participants were assessed twice on the functional evaluating rating scale. During the followup measurement, subjective experiences regarding both forms of electric scooter training were elicited by a questionnaire. After a training period of 5 weeks, both groups improved on the Functional Evaluation Rating Scale. It can be concluded that the patients with stroke were satisfied with the electric scooter simulation training.","","en","journal article","Mary Ann Liebert","","","","","","","","Mechanical, Maritime and Materials Engineering","Biomechanical Engineering","","","",""
"uuid:5d7d74b3-69ad-47f7-9d90-da37af8be508","http://resolver.tudelft.nl/uuid:5d7d74b3-69ad-47f7-9d90-da37af8be508","Human error in strabismus surgery: Quantification with a sensitivity analysis","Schutte, S.; Polling, J.R.; Van der Helm, F.C.T.; Simonsz, H.J.","","2008","Background- Reoperations are frequently necessary in strabismus surgery. The goal of this study was to analyze human-error related factors that introduce variability in the results of strabismus surgery in a systematic fashion. Methods- We identified the primary factors that influence the outcome of strabismus surgery. For each of the human-error related factors we quantified variation with clinical assessments: measurement of the angle of strabismus, surgical strategy and surgical accuracy. Firstly, six patients were examined by six orthoptists, and accuracy of prism cover tests was assessed. Secondly, a questionnaire with sample cases (10°, 15° and 20° of infantile esotropia) was put to orthoptists, to determine variation in current surgical strategy. Finally, photographs made during surgery were analyzed to assess surgical accuracy. The influence of human-error related factors was related to the influence of inter-patient differences with a mechanical model. The relative contribution of all factors was assessed with a sensitivity analysis, and results were compared to clinical studies. Results- The surgical trajectory of strabismus surgery could be modeled mathematically. Measurement of angle of strabismus, surgical technique, anatomy and physiology were considered. Variations in the human-error related factors were: (1) the latent angle at distant fixation was measured with a 90% confidence interval of 5°, and comprised 20% of the total variance of the postoperative angle, (2) orthoptists decided for bilateral recessions of, respectively, 7.3±1.7 mm (total amount of two recessions), 9.1±1.2 mm and 10.3±1.3 mm, which comprised 15% of the total variance, and (3) surgical accuracy was estimated at ±0.5 mm, which comprised 20% of the total variance. Conclusion- The human error in strabismus surgery could be quantified with a sensitivity analysis. Approximately half of the reoperations in strabismus surgery are caused by inaccuracy in the measurement of the angle of strabismus, variability in surgical strategy and imprecise surgery.","strabismus; strabismus surgery; pediatric ophthalmology; sensitivity analysis; human error","en","journal article","Springer","","","","","","","","Mechanical, Maritime and Materials Engineering","Biomechanical Engineering","","","",""
"uuid:eda09b15-40de-48a6-a497-f2eab649c6e6","http://resolver.tudelft.nl/uuid:eda09b15-40de-48a6-a497-f2eab649c6e6","Requirements for the design and implementation of checklists for surgical processes","Verdaasdonk, E.G.G.; Stassen, L.P.S.; Widhiasmara, P.P.; Dankelman, J.","","2008","Background- The use of checklists is a promising strategy for improving patient safety in all types of surgical processes inside and outside the operating room. This article aims to provide requirements and implementation of checklists for surgical processes. Methods- The literature on checklist use in the operating room was reviewed based on research using Medline, Pubmed, and Google Scholar. Although all the studies showed positive effects and important benefits such as improved team cohesion, improved awareness of safety issues, and reduction of errors, their number still is limited. The motivation of team members is considered essential for compliance. Currently, no general guidelines exist for checklist design in the surgical field. Based on the authors’ experiences and on guidelines used in the aviation industry, requirements for the checklist design are proposed. The design depends on the checklist purpose, philosophy, and method chosen. The methods consist of the ‘‘call-doresponse’’ approach,’’ the ‘‘do-verify’’ approach, or a combination of both. The advantages and disadvantages of paper versus electronic solutions are discussed. Furthermore, a step-by-step strategy of how to implement a checklist in the clinical situation is suggested. Conclusions- The use of structured checklists in surgical processes is most likely to be effective because it standardizes human performance and ensures that procedures are followed correctly instead of relying on human memory alone. Several studies present promising and positive first results, providing a solid basis for further investigation. Future research should focus on the effect of various checklist designs and strategies to ensure maximal compliance.","endoscopy; human error; safety checklist; instruments; technical; human/robotic","en","journal article","Springer","","","","","","","","Mechanical, Maritime and Materials Engineering","Biomechanical Engineering","","","",""
"uuid:44b7bb0a-a3b8-40d8-9819-ea223b890d25","http://resolver.tudelft.nl/uuid:44b7bb0a-a3b8-40d8-9819-ea223b890d25","Can a structured checklist prevent problems with laparoscopic equipment?","Verdaasdonk, E.G.G.; Stassen, L.P.S.; Hoffmann, W.F.; Van der Elst, M.; Dankelman, J.","","2008","Background A high incidence of problems with the technical equipment is known to occur during routine laparoscopic procedures. Use of a structured checklist of preparatory measures could help to prevent these problems. This study aimed to determine the extent to which a checklist reduced the number of incidents with technical laparoscopic equipment. Methods A 28-item checklist was developed based on frequently occurring laparoscopic equipment problems during 30 laparoscopic cholecystectomies (the control group). A further 30 procedures were conducted with the checklist (the checklist group). The number and type of incidents with the technical equipment were compared between the groups. All the procedures were recorded using a special audio–video system (black-box). Results In the checklist group, the total number of incidents per procedure was 53% lower than in the control group (23/30 versus 49/30). The checklist led to fewer incidents of wrong positioning (9/30 versus 22/30), and wrong settings and connections (7/30 versus 12/30) of the equipment. Defects or malfunctions decreased from 15/30 in the control group to 7/30 in the checklist group. One or more incidents with the equipment occurred in 47% (14/30) of the checklist procedures compared with 87% (26/30) of the control procedures. Median time taken to complete the checklist items was 3.3 min (range 1.0–8.3 min). Conclusions Use of a checklist was feasible and helped to reduce problems with the laparoscopic equipment in the operating room. Future research should aim to implement checklists for different procedures and investigate their effects.","wrong-site surgery; anesthetic machines","en","journal article","Springer","","","","","","","","Mechanical, Maritime and Materials Engineering","Biomechanical Engineering","","","",""
"uuid:6237c2b9-f70e-4e97-be1a-c782b3fd3104","http://resolver.tudelft.nl/uuid:6237c2b9-f70e-4e97-be1a-c782b3fd3104","Fall detection in walking robots by multi-way principal component analysis","Karssen, J.G.; Wisse, M.","","2008","Large disturbances can cause a biped to fall. If an upcoming fall can be detected, damage can be minimized or the fall can be prevented. We introduce the multi-way principal component analysis (MPCA) method for the detection of upcoming falls. We study the detection capability of the MPCA method in a simulation study with the simplest walking model. The results of this study showthat the MPCA method is able to predict a fall up to four steps in advance in the case of single disturbances. In the case of random disturbances the MPCA method has a successful detection probability of up to 90%.","Bipeds; Legged robots; Humanoid robots; Robot dynamics; Pose estimation and registration","en","journal article","Cambridge University Press","","","","","","","","Applied Sciences","Biomechanical Engineering","","","",""
"uuid:2b872e5e-019b-4b56-8427-149ebfde9cd3","http://resolver.tudelft.nl/uuid:2b872e5e-019b-4b56-8427-149ebfde9cd3","Design of Perturbation Signals for the Estimation of Proprioceptive Reflexes","Schouten, A.C.; De Vlugt, E.; Van der Helm, F.C.T.","","2008","This study aimed to identify the functional contribution of reflexes to human motor control during posture maintenance. Continuous random force disturbances were applied at the hand while the subjects were instructed to minimize the deviation resulting from the force disturbances. The results were analyzed in the frequency domain with frequency response functions (FRFs). Two FRFs were evaluated: 1) the mechanical admittance and 2) the reflexive impedance, expressing the dynamic relation between position and muscle activation (assessed via electromyography, EMG). The reflexive impedance is a direct measure of the proprioceptive reflexes. To record all relevant dynamical characteristics of the arm, wide bandwidth signals were used as force disturbance. Distributing the power of the signal over fewer frequencies within the bandwidth improved the signal-to-noise-ratio SNR of the EMG recordings, facilitating reliable estimation of the reflexive impedance. The coherence indicated that the relation between force disturbance and EMG is linear under the given conditions and improved with the SNR. The method of designing disturbance signals and the estimation of the reflexive impedance are useful for studies aiming to quantify proprioceptive reflexes and to investigate its functionality.","arm admittance; electromyography (EMG); identification; proprioceptive reflexes; reflexive impedance","en","journal article","IEEE","","","","","","","","Applied Sciences","Biomechanical Engineering","","","",""
"uuid:e930c885-edae-4ba7-80f3-6a23b31268b9","http://resolver.tudelft.nl/uuid:e930c885-edae-4ba7-80f3-6a23b31268b9","Force feedback and basic laparoscopic skills","Chmarra, M.K.; Dankelman, J.; Van den Dobbelsteen, J.J.; Jansen, F.W.","","2008","Background - Not much is known about the exact role offorce feedback in laparoscopy. This study aimed to determine whether force feedback influences movements of instruments during training in laparoscopic tasks and whether force feedback is required for training in basic laparoscopic force application tasks. Methods - A group of 19 gynecologic residents, randomly divided into two groups, performed three laparoscopic tasks in both the box trainer and the virtual reality (VR) trainer. The box-VR group began with the box trainer, whereas the VR-box group began with the VR trainer. The three selected tasks included different levels of force application. The box trainer provides natural force feedback, whereas the VR trainer does not provide force feedback. The performance of the two groups was compared with regard to time, path length, and depth perception. Results - For the tasks in which force plays hardly a role, no differences between box-VR group and the VR-box group were found. During a task in which force application (pulling and pushing forces) plays a role, the box-VR group outperformed VR-box group in the box trainer. Moreover, training with the box trainer had a positive effect on subsequent performance of the task with the VR trainer. This was not found the other way around. No differences were found between box-VR and the VR-box group in tasks not requiring force application. Conclusion - Force feedback influences basic laparoscopic skills during tasks in which pulling and pushing forces are applied. For these tasks, the switch from the trainer without force feedback to the one with natural force feedback has a detrimental effect on performance. Therefore, training for tasks in which forces play an important role (e.g., stretching, grasping) should be done using systems with natural force feedback, whereas eye–hand coordination can be trained without force feedback.","laparoscopy; training; force feedback; basic laparoscopic skills; motion analysis","en","journal article","Springer","","","","","","","","Mechanical, Maritime and Materials Engineering","Biomechanical Engineering","","","",""
"uuid:cd94c472-a14e-4e85-807d-87f82914f4aa","http://resolver.tudelft.nl/uuid:cd94c472-a14e-4e85-807d-87f82914f4aa","Virtual reality training and equipment handling in laparoscopic surgery","Verdaasdonk, E.G.G.","Dankelman, J. (promotor); Stassen, L.P.S. (promotor)","2008","Laparoscopic surgery is one of the most important surgical innovations of the 20th century. Despite the well-known benefits for the patient, such as reduced pain, reduced hospital stay and quicker return to normal physical activities, there are also some drawbacks. Performing laparoscopic surgery requires specific psychomotor skills and extensive training. Furthermore, training solely on patients is considered unethical and therefore no longer acceptable. Besides the specific psychomotor skills required for laparoscopic surgery, its technical equipment has made the surgical environment more complex and has introduced new risks for the patients safety. The first objective of this thesis is the validation of the VR simulator SIMENDO for the training of laparoscopic psychomotor skills, in order to incorporate this simulator effectively into the surgical curriculum. The second objective of this thesis is the determination of the current problems and needs encountered during laparoscopic surgery in the operation room in order to develop methods to improve safety and efficiency. Validation of the SIMENDO VR simulator. The SIMENDO simulator was subjectively evaluated by a group of experienced laparoscopic surgeons and a group of surgical trainees, inexperienced with laparoscopic surgery (face validation). The groups considered the SIMENDO to be a useful simulator for the training of hand-eye coordination skills for laparoscopic surgery. The learning effect of a simple hand-eye coordination task in the SIMENDO with a single instrument was comparable to the learning effect of a similar task in a box trainer (concurrent validation). The parameters of the tasks in the simulator could distinguish groups with different laparoscopic experience levels (construct validation). The learning curve showed that training on the SIMENDO is useful and valid for subjects with limited or no laparoscopic experience. Training laparoscopic skills on a simulator distributed over several days seems better than training on just one day. Criterion-based training was successfully incorporated in the surgical curriculum. Laparoscopic knot-tying skills acquired on the simulator were shown to be transferable to the knot-tying performance on an animal model. In a randomised controlled trial, subjects that were trained on the VR simulator with the knot-tie module were 30% faster and made 33% fewer errors (transfer or predictive validity) in a laparoscopic animal model, as compared to the control group. Furthermore, a national on-line competition with a reward for the best performance was initiated. The use of competition elements on the simulator may enhance the motivation of surgical trainees to train voluntary. Current problems and needs during laparoscopic surgery in the operating room Analysis of 30 laparoscopic cholecystectomies showed that the incidence of problems with the technical equipment was strikingly high (49 incidents in 30 procedures, only four procedures without technical problems). These problems could be prevented by improvement and standardisation of equipment, in combination with the incorporation of a checklist before the start of the procedure. A structured checklist was developed to prevent incidents with laparoscopic equipment. In the group with the checklist the number of equipment problems decreased with more than 50% compared to the procedures studied previously without the checklist. To gain insight into the communication content during surgical training in the operation room, a classification method was developed. The application revealed that communication was mainly focussed on explaining of the operation method (27%), explaining the anatomy (19%), and learning the positioning of the instrument and how to interact with the tissue (25%). The results of the study may be used to specify training needs and to evaluate different training methods.","","en","doctoral thesis","","","","","","","","","Mechanical, Maritime and Materials Engineering","Biomechanical Engineering","","","",""
"uuid:856ec80b-6c1f-40e8-9a80-d89f4d748dbf","http://resolver.tudelft.nl/uuid:856ec80b-6c1f-40e8-9a80-d89f4d748dbf","Incorporation of proficiency criteria for basic laparoscopic skills training: How does it work?","Verdaasdonk, E.G.; Dankelman, J.; Lange, J.F.; Stassen, L.P.S.","","2008","Background - It is desirable that surgical trainees are proficient in basic laparoscopic motor skills (eye–hand coordination). The present study evaluated the use of predefined proficiency criteria on a basic virtual reality (VR) simulator in preparation for a laparoscopic course on animal models. Methods - Twenty-eight surgical trainees who enrolled for a basic laparoscopic course were trained on a basic (VR) simulator until their performance met predefined criteria. Two different criteria were defined, based on the performance of experienced laparoscopic surgeons on the simulator. In the first group (n = 10), the criteriawere set at the 75th percentile of the laparoscopic surgeons’ performance on the simulator and in the second group, at the 50th percentile (n = 18). Training time and number of attempts needed until the performance criteria were met were measured. Results - In the first group, training time needed to pass the test ranged from 29 to 77 min (median: 63 min) with a range of 43–90 attempts (median 61 attempts). In the second group, training time ranged from 38 to 180 min (median 80 min) with a range of 55–233 attempts (median 95 attempts). Experience with assisting or performing laparoscopic procedures varied widely and was not correlated with the training time and number of attempts needed to pass the criteria. Conclusions - The performance criteria for training laparoscopic motor skills on a (VR) simulator resulted in wide variation between surgical trainees in time and number of attempts needed to pass the criteria. This demands training courses with a flexible time span tailored to the individual level of the trainee.","training; education; surgery; laparoscopic; virtual reality; simulation; proficiency; criterion-based","en","journal article","Springer","","","","","","","","Mechanical, Maritime and Materials Engineering","Biomechanical Engineering","","","",""
"uuid:f8c763eb-92b3-499a-b984-ee9f99ed756c","http://resolver.tudelft.nl/uuid:f8c763eb-92b3-499a-b984-ee9f99ed756c","Swing-Leg Retraction for Limit Cycle Walkers Improves Disturbance Rejection","Hobbelen, D.G.E.; Wisse, M.","","2008","Limit cycle walkers are bipeds that exhibit a stable cyclic gaitwithout requiring local controllability at all times during gait. A well-known example of limit cycle walking is McGeer’s “passive dynamic walking,” but the concept expands to actuated bipeds as involved in this study. One of the stabilizing effects in limit cycle walkers is the dissipation of energy that occurs when the swing foot hits the ground.We hypothesize that this effect can be enhanced with a negative relation between the step length and step time. This relation is implemented through an open-loop strategy called swing-leg retraction; a predefined time trajectory for the swing leg makes the swing leg move backwards just prior to foot impact. In this paper, we study the effect of swing-leg retraction through three bipeds; a simple point mass simulation model, a realistic simulationmodel, and a physical prototype. Their stability is analyzed using Floquet multipliers, followed by an evaluation of how well disturbances are handled using the Gait Sensitivity Norm. We find that mild swing-leg retraction is optimal for the disturbance rejection of a limit cyclewalker, as it results in a system response that is close to critically damped, rejecting the disturbance in the fewest steps. Slower retraction results in an overdamped response, characterized by a positive dominant Floquet multiplier. Likewise, faster retraction results in an underdamped response, characterized by a negative Floquet multiplier.","bipeds; disturbance rejection; dynamic walking; limit cycle walkers; swing-leg retraction","en","journal article","IEEE","","","","","","","","Mechanical, Maritime and Materials Engineering","Biomechanical Engineering","","","",""
"uuid:7ae60177-079f-4936-8f55-9043372a33a0","http://resolver.tudelft.nl/uuid:7ae60177-079f-4936-8f55-9043372a33a0","Mucoadhesive films inside the colonic tube: Performance in a three-dimensional world","Dodou, D.; Van den Berg, M.; Van Gennip, J.; Breedveld, P.; Wieringa, P.A.","","2008","A self-propelling colonoscopic device moving inside the colonic tube should be able to periodically grip safely to the colonic wall as well as to manipulate the generated friction. The feasibility of achieving high grip and friction manipulation by covering the device with mucoadhesive films is experimentally tested. More precisely, the frictional behaviour of mucoadhesive films inside the colonic tube is tested in vitro in porcine colon. It appears that mucoadhesive films generate significantly higher friction than conventional materials (ANOVA p=0, 95% CIs=-3.04, -2.14). The geometry of the film plays a role as well. When holes are, for instance, present in the film geometry and are large enough so that the colonic tissue can wrap their borders, friction can be significantly increased (ANOVA p=0, 95% CIs=-2.53, -1.26). By altering the contact area or the film geometry, friction manipulation can be achieved. Moreover, a simple theoretical model is developed and experimentally verified (R=0.92). The model can be used to estimate the level of the friction generated by three-dimensional configurations of mucoadhesive films as a function of their geometric characteristics and the material properties of the colon.","colonoscopy; colonoscopic device; friction; mucoadhesives","en","journal article","The Royal Society of London","","","","","","","","Mechanical, Maritime and Materials Engineering","Biomechanical Engineering","","","",""
"uuid:3c365db5-057f-4b9a-9c09-a199fd790fd8","http://resolver.tudelft.nl/uuid:3c365db5-057f-4b9a-9c09-a199fd790fd8","A review of function modeling: Approaches and applications","Erden, M.S.; Komoto, H.; Van Beek, T.J.; D'Amelio, V.; Echavarria, E.; Tomiyama, T.","","2008","This work is aimed at establishing a common frame and understanding of function modeling (FM) for our ongoing research activities. A comparative review of the literature is performed to grasp the various FM approaches with their commonalities and differences. The relations of FM with the research fields of artificial intelligence, design theory, and maintenance are discussed. In this discussion the goals are to highlight the features of various classical approaches in relation to FM, to delineate what FM introduces to these fields, and to discuss the applicability of various FM approaches in these fields. Finally, the basic ideas underlying our projects are introduced with reference to the general framework of FM.","Behavior; Design; Function Modeling; Maintenance; Service","en","journal article","Cambridge University Press","","","","","","","","Mechanical, Maritime and Materials Engineering","Biomechanical Engineering","","","",""
"uuid:e3b442bb-5cda-4dbb-b2ef-f0d8eef4f543","http://resolver.tudelft.nl/uuid:e3b442bb-5cda-4dbb-b2ef-f0d8eef4f543","Model prediction of subendocardial perfusion of the coronary circulation in the presence of an epicardial coronary artery stenosis","Van den Wijngaard, J.P.H.M.; Kolyva, C.; Siebes, M.; Dankelman, J.; Van Gemert, M.J.C.; Piek, J.J.; Spaan, J.A.E.","","2008","The subendocardium is most vulnerable to ischemia, which is ameliorated by relaxation during diastole and increased coronary pressure. Recent clinical techniques permit the measuring of subendocardial perfusion and it is therefore important to gain insight into how measurements depend on perfusion conditions of the heart. Using data from microsphere experiments a layered model of the myocardial wall was developed. Myocardial perfusion distribution during hyperemia was predicted for different degrees of coronary stenosis and at different levels of Diastolic Time Fraction (DTF). At the reference DTF, perfusion was rather evenly distributed over the layers and the effect of the stenosis was homogenous. However, at shorter or longer DTF, the subendocardium was the first or last to suffer from shortage of perfusion. It is therefore concluded that the possible occurrence of subendocardial ischemia at exercise is underestimated when heart rate is increased and DTF is lower.","Coronary reserve; Steal; Heart model; Regional conductance; Diastolic time fraction","en","journal article","Springer","","","","","","","","Applied Sciences","Department of BioMechanical Engineering","","","",""
"uuid:f1a67f2b-06a1-457d-b2be-c4171c6b489a","http://resolver.tudelft.nl/uuid:f1a67f2b-06a1-457d-b2be-c4171c6b489a","A Two-Dimensional Weighting Function for a Driver Assistance System","De Winter, J.; Mulder, M.; Van Paassen, M.M.; Abbink, D.A.; Wieringa, P.A.","","2008","Driver assistance systems that supply force feedback (FF) on the accelerator commonly use relative distance and velocity with respect to the closest lead vehicle in front of the own vehicle. This 1-D feedback might not accurately represent the situation and can cause unwanted step-shaped changes in the FFs during lateral maneuvers. To address these shortcomings, a 2-D system is proposed that calculates FF using a weighted average of the influences of lead vehicles. Offline simulations and an experiment in a driving simulator were performed to compare no feedback, 1-D systems, and the novel 2-D system during a car-following task with cut-in maneuvers. Results show that the 2-D feedback resulted in lower mean forces, lower response times to cut-in vehicles, and favorable subjective experiences as compared to the 1-D systems.","accelerator; driver assistance; force feedback (FF); weighting function","en","journal article","IEEE","","","","","","","","Mechanical, Maritime and Materials Engineering","Biomechanical Engineering","","","",""
"uuid:f72b15cb-70c7-4bbc-8056-1756adcee55c","http://resolver.tudelft.nl/uuid:f72b15cb-70c7-4bbc-8056-1756adcee55c","A Two-Dimensional Weighting Function for a Driver Assistance System","De Winter, J.C.F.; Mulder, M.; Van Paassen, M.M.; Abbink, D.A.; Wieringa, P.A.","","2008","Driver assistance systems that supply force feedback (FF) on the accelerator commonly use relative distance and velocity with respect to the closest lead vehicle in front of the own vehicle. This 1-D feedback might not accurately represent the situation and can cause unwanted step-shaped changes in the FFs during lateral maneuvers. To address these shortcomings, a 2-D system is proposed that calculates FF using a weighted average of the influences of lead vehicles. Offline simulations and an experiment in a driving simulator were performed to compare no feedback, 1-D systems, and the novel 2-D system during a car-followingtask with cut-in maneuvers. Results show that the 2-D feedback resulted in lower mean forces, lower response times to cut-in vehicles, and favorable subjective experiences as compared to the 1-D systems.","accelerator; driver assistance,; force feedback (FF); weighting function","en","journal article","IEEE","","","","","","","","Mechanical, Maritime and Materials Engineering","Biomechanical Engineering","","","",""
"uuid:5fef4b7a-840b-429f-932e-cb3e81feda2e","http://resolver.tudelft.nl/uuid:5fef4b7a-840b-429f-932e-cb3e81feda2e","Quantifying Proprioceptive Reflexes During Position Control of the Human Arm","Schouten, A.C.; De Vlugt, E.; Van Hilten, J.J.; Van der Helm, F.C.","","2008","This study aimed to analyse the dynamic properties of the muscle spindle feedback system of shoulder muscles during a posture task. External continuous force disturbances were applied at the hand while subjects had to minimize their hand displacements. The results were analysed using two frequency response functions (FRFs) from which the model parameters were derived, being 1) the mechanical admittance and 2) the reflexive impedance. These FRFs were analysed by a neuromusculoskeletal model that implicitly separates the reflexive feedback properties (position, velocity and acceleration feedback gains) from intrinsic muscle visco-elasticity. The results show substantial changes in estimated reflex gains under conditions of variable bandwidth of the applied force disturbance or variable degrees of external damping. Position and velocity feedback gains were relatively larger when the force disturbance contained only low frequencies. With increasing damping of the environment, acceleration feedback gain decreased, velocity feedback gain remained almost constant and position feedback gain increased. It is concluded that under the aforementioned circumstances, the reflex system increases its gains to maximize the mechanical resistance to external force disturbances while preserving sufficient stability.","arm admittance; electromyography; identification; proprioceptive reflexes; reflexive impedance","en","journal article","IEEE","","","","","","","","Mechanical, Maritime and Materials Engineering","Biomechanical Engineering","","","",""
"uuid:cfdc87cf-c539-43b8-8fb8-6c02e69fdfad","http://resolver.tudelft.nl/uuid:cfdc87cf-c539-43b8-8fb8-6c02e69fdfad","Transfer validity of laparoscopic knot-tying training on a VR simulator to a realistic environment: A randomized controlled trial","Verdaasdonk, E.G.G.; Dankelman, J.; Lange, J.F.; Stassen, L.P.S.","","2007","Background- Laparoscopic suturing is one of the most difficult tasks in endoscopic surgery, requiring extensive training. The aim of this study was to determine the transfer validity of knot-tying training on a virtual-reality (VR) simulator to a realistic laparoscopic environment. Methods- Twenty surgical trainees underwent basic eye–hand coordination training on a VR simulator (SIMENDO, DelltaTech, Delft, the Netherlands) until predefined performance criteria were met. Then, they were randomized into two groups. Group A (the experimental group) received additional training with the knot-tying module on the simulator, during which they had to tie a double laparoscopic knot ten times. Group B (controls) did not receive additional manual training. Within a week the participants tied a double knot in the abdominal cavity of an anaesthetized porcine model. Their performance was captured on digital video and coded. Objective analysis parameters were: time taken to tie the knot and number of predefined errors made. Subjective assessments were also made by two laparoscopic surgeons using a global rating list with a five-point Likert scale. Results- Trainees in group A (n = 9) were significantly faster than the controls (n = 10), with a median of 262 versus 374 seconds (p = 0.034). Group A made a significantly lower number of errors than the controls (median of 24 versus 36 errors, p = 0.030). Subjective assessments by the laparoscopic experts did not show any significant differences in economy of movement and erroneous behavior between the two groups. Conclusion- Surgical trainees who received knot-tying training on the VR simulator were faster and made fewer errors than the controls. The VR module is a useful tool to train laparoscopic knot-tying. Opportunities arose to improve simulator-based instruction that might enhance future training.","education; VR simulation; suturing; laparoscopy","en","journal article","Springer","","","","","","","","Mechanical, Maritime and Materials Engineering","Biomechanical Engineering","","","",""
"uuid:95a55f2e-dbb5-4eb8-9647-5fe1664d87b4","http://resolver.tudelft.nl/uuid:95a55f2e-dbb5-4eb8-9647-5fe1664d87b4","Retracting and seeking movements during laparoscopic goal-oriented movements. Is the shortest path length optimal?","Chmarra, M.K.; Jansen, F.W.; Grimbergen, C.A.; Dankelman, J.","","2007","Aims- Minimally invasive surgery (MIS) requires a high degree of eye–hand coordination from the surgeon. To facilitate the learning process, objective assessment systems based on analysis of the instruments’ motion are being developed. To investigate the influence of performance on motion characteristics, we examined goaloriented movements in a box trainer. In general, goal-oriented movements consist of a retracting and a seeking phase, and are, however, not performed via the shortest path length. Therefore, we hypothesized that the shortest path is not an optimal concept in MIS. Methods-Participants were divided into three groups (experts, residents, and novices). Each participant performed a number of one-hand positioning tasks in a box trainer. Movements of the instrument were recorded with the TrEndo tracking system. The movement from point A to B was divided into two phases: A-M (retracting) and M-B (seeking). Normalized path lengths (given in %) of the two phases were compared. Results- Thirty eight participants contributed. For the retracting phase, we found no significant difference between experts [median (range) %: 152 (129–178)], residents [164 (126–250)], and novices [168 (136–268)]. In the seeking phase, we find a significant difference (<0.001) between experts [180 (172–247)], residents [201 (163–287)], and novices [290 (244–469)]. Moreover, within each group, a significant difference between retracting and seeking phases was observed. Conclusions- Goal-oriented movements in MIS can be split into two phases: retracting and seeking. Novices are less effective than experts and residents in the seeking phase. Therefore, the seeking phase is characteristic of performance differences. Furthermore, the retracting phase is essential, because it improves safety by avoiding intermediate tissue contact. Therefore, the shortest path length, as presently used during the assessment of basic MIS skills, may be not a proper concept for analyzing optimal movements and, therefore, needs to be revised.","minimally invasive surgery; training; motion analysis; objective assessment; goal-oriented movement; path length","en","journal article","Springer","","","","","","","","Mechanical, Maritime and Materials Engineering","Biomechanical Engineering","","","",""
"uuid:0db235a5-2e51-42e3-b194-533756139f02","http://resolver.tudelft.nl/uuid:0db235a5-2e51-42e3-b194-533756139f02","Surgical Simulator Design and Development","Dankelman, J.","","2007","With the introduction of minimally invasive surgery (MIS), it became necessary to develop training methods to learn skills outside the operating room. Several training simulators have become commercially available, but fundamental research into the requirements for effective and efficient training in MIS is still lacking. Three aspects of developing a training program are investigated here: what should be trained, how it should be trained, and how to assess the results of training. In addition, studies are presented that have investigated the role of force feedback in surgical simulators. Training should be adapted to the level of behavior: skill-based, rule-based, or knowledgebased. These levels can be used to design and structure a training program. Extra motivation for training can be created by assessment. During MIS, force feedback is reduced owing to friction in the laparoscopic instruments and within the trocar. The friction characteristics vary largely among instruments and trocars. When force feedback is incorporated into training, it should include the large variation in force feedback properties as well. Training different levels of behavior requires different training methods. Although force feedback is reduced during MIS, it is needed for tissue manipulation, and therefore force application should be trained as well.","","en","journal article","Springer","","","","","","","","Mechanical, Maritime and Materials Engineering","Biomechanical Engineering","","","",""
"uuid:ef9d1a47-209e-4e2a-9026-e98f89221db0","http://resolver.tudelft.nl/uuid:ef9d1a47-209e-4e2a-9026-e98f89221db0","New Technologies Supporting Surgical Interventions and Training of Surgical Skills: A Look at Projects in Europe Supporting Minimally Invasive Techniques","Dankelman, J.; Grimbergen, C.A.; Stassen, H.G.","","2007","","","en","journal article","IEEE","","","","","","","","Mechanical, Maritime and Materials Engineering","Biomechanical Engineering","","","",""
"uuid:b4e034c8-bbe9-49e4-a55c-a64f972d4d5c","http://resolver.tudelft.nl/uuid:b4e034c8-bbe9-49e4-a55c-a64f972d4d5c","Principle and design of a mobile arm support for people with muscular weakness","Herder, J.L.; Vrijlandt, N.; Antonides, T.; Cloosterman, M.; Mastenbroek, P.L.","","2006","This article describes the development of a mobile arm support for people with muscular diseases. The arm support is spring-balanced, with special attention on reduction of operating effort (high balancing quality and low friction), functionality (large range of motion), and aesthetics (inconspicuous design). The spring settings can be adjusted for wearing heavier clothing or picking up an object, a function that can also be used for moving up or down. The device levels itself automatically to compensate for uneven floors, a function that can be overruled to assist forward/backward motion of the arm. Thus, the balancer can compensate for the weight of the arm and be adjusted to generate force to a limited (safe) extent. The principle and design of the mechanism are presented and preliminary field trial results are given. Two users report on 6 months of continuous use of the arm support in their home and social environments.","adjustable spring mechanism; assistive device; biomechanics; gravity equilibrator; mobile arm support; neuromuscular diseases; passive orthosis; rehabilitation; static balancing; upper limb; user opinions","en","journal article","U.S. Department of Veterans Affairs","","","","","","","","Mechanical, Maritime and Materials Engineering","Biomechanical Engineering","","","",""
"uuid:ad7b5e45-7b37-4a54-a323-160cb06cd488","http://resolver.tudelft.nl/uuid:ad7b5e45-7b37-4a54-a323-160cb06cd488","The role of geometry in the friction generated on the colonic surface by mucoadhesive films","Dodou, D.; Breedveld, P.; Wieringa, P.A.","","2006","One of the main challenges in designing diagnostic devices able to move along the colon is their locomotion method. Generating friction without applying high normal forces is a key requirement in order to eliminate the risk of tissue damage. One possible solution is to generate friction by means of adhesive forces. For this reason, the device can be covered with mucoadhesive films, which are able to stick on the colonic surface. This paper identifies that the friction of mucoadhesive films depends strongly on their geometry. It seems therefore feasible to adapt the level of the friction to the properties of the colonic surface by altering the geometry of the films covering the device. Moreover, an eventual influence of the film geometry on the generated friction can reveal film shapes which create high grip despite their small size, leading to a decrease in the overall size of the device. The aim of the paper is to test in vitro the relationship between film geometry and generated friction, to fit the experimental findings in a simplified but generic macroscopic theoretical model able to predict the behavior of various geometries, and to embed those findings in the principles of the design implementation.","adhesion; friction; biomechanics; biological tissues; biomedical equipment","en","journal article","American Institute of Physics","","","","","","","","Mechanical, Maritime and Materials Engineering","Biomechanical Engineering","","","",""
"uuid:74fa22c2-3e4f-47e4-beb0-76fa5f67f351","http://resolver.tudelft.nl/uuid:74fa22c2-3e4f-47e4-beb0-76fa5f67f351","The Perspective Effect of Wide-Angle Lenses in Laparoscopes","Wentink, M.; Fischer, H.; Dankelman, J.; Stassen, L.P.S.; Wieringa, P.A.","","2002","Purpose: To evaluate the effect of perspective distortion of wide-angle lenses in laparoscopes on hand-eye coordination during endoscopic manipulation. Methods: Sixteen subjects repeatedly performed a standardized positioning task in a pelvi-trainer under two conditions. The subjects had no prior experience with endoscopic manipulation. In one condition, a wide-angle lens with considerable perspective distortion was used; in the other, a telephoto lens without perspective distortion was used. Task time and number of errors were measured. Results: Task time and the number of errors did not significantly increase in the condition with a wide-angle lens. Conclusions: The perspective effect did not influence task performance in endoscopic manipulation in this experiment. Subjects indicated that they even preferred the wide-angle lens because its extreme perspective improved their perception of depth.","","en","journal article","Mary Ann Liebert","","","","","","","","Mechanical, Maritime and Materials Engineering","Biomechanical Engineering","","","",""
"uuid:d9d6078f-690b-4a69-88c1-8b8d0e205d2c","http://resolver.tudelft.nl/uuid:d9d6078f-690b-4a69-88c1-8b8d0e205d2c","How Crouch Gait Can Dynamically Induce Stiff-Knee Gait","Van der Krogt, M.M.; Bregman, D.J.J.; Wisse, M.; Doorenbosch, C.A.M.; Harlaar, J.; Collins, S.H.","","","Children with cerebral palsy frequently experience foot dragging and tripping during walking due to a lack of adequate knee flexion in swing (stiff-knee gait). Stiff-knee gait is often accompanied by an overly flexed knee during stance (crouch gait). Studies on stiff-knee gait have mostly focused on excessive knee muscle activity during (pre)swing, but the passive dynamics of the limbs may also have an important effect. To examine the effects of a crouched posture on swing knee flexion, we developed a forwarddynamic model of human walking with a passive swing knee, capable of stable cyclic walking for a range of stance knee crouch angles. As crouch angle during stance was increased, the knee naturally flexed much less during swing, resulting in a ‘stiff-knee’ gait pattern and reduced foot clearance. Reduced swing knee flexion was primarily due to altered gravitational moments around the joints during initial swing. We also considered the effects of increased push-off strength and swing hip flexion torque, which both increased swing knee flexion, but the effect of crouch angle was dominant. These findings demonstrate that decreased knee flexion during swing can occur purely as the dynamical result of crouch, rather than from altered muscle function or pathoneurological control alone.","Human; Walking; Biomechanics; Rehabilitation; Orthopedics, Cerebral palsy; Passive dynamics, Mathematical model; Simulation","en","journal article","Springer","","","","","","","","Mechanical, Maritime and Materials Engineering","Biomechanical Engineering","","","",""
"uuid:0d4d7c96-119d-469d-8bf8-b9b6a3c75086","http://resolver.tudelft.nl/uuid:0d4d7c96-119d-469d-8bf8-b9b6a3c75086","Poor motor function is associated with reduced sensory processing after stroke","Campfens, S.F.; Zandvliet, S.B.; Meskers, C.G.M.; Schouten, A.C.; Van Putten, M.J.A.M.; Van der Kooij, H.","","","Abstract The possibility to regain motor function after stroke depends on the intactness of motor and sensory pathways. In this study, we evaluated afferent sensory pathway information transfer and processing after stroke with the coherence between cortical activity and a position perturbation (position-cortical coherence, PCC). Eleven subacute stroke survivors participated in this study. Subjects performed a motor task with the affected and non-affected arm while continuous wrist position perturbations were applied. Cortical activity was measured using EEG. PCC was calculated between position perturbation and EEG at the contralateral and ipsilateral sensorimotor area. The presence of PCC was quantified as the number of frequencies where PCC is larger than zero across the sensorimotor area. All subjects showed significant contralateral PCC in affected and non-affected wrist tasks. Subjects with poor motor function had a reduced presence of contralateral PCC compared with subjects with good motor function in the affected wrist tasks. Amplitude of significant PCC did not differ between subjects with good and poor motor function. Our results show that poor motor function is associated with reduced sensory pathway information transfer and processing in subacute stroke subjects. Position-cortical coherence may provide additional insight into mechanisms of recovery of motor function after stroke.","stroke; coherence; afferent pathways; motor control; joint position perturbation; EEG","en","journal article","","","","","","","","","Mechanical, Maritime and Materials Engineering","Biomechanical Engineering","","","",""