D. Dodou
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1
Large Language Models (LLMs) promise intuitive robot control through natural language, yet the gap between vague human intent and safe physical execution remains significant. This thesis investigates how the distribution of planning responsibility relates to the reasoning architecture of the model. In a study involving 226 participants who were new users in LLM-based robot prompting, a non-reasoning model (Gemini 2.0 Flash-Lite) and a reasoning model (Gemini 2.5 Pro) were compared on a baseline navigation task, followed by an evaluation of the reasoning model across tasks of increasing logical complexity. Results indicate a clear divergence in safety profiles: non-reasoning models showed more collision-prone goal-seeking behavior, whereas reasoning models demonstrated stricter adherence to the safety constraints in the system prompt, preferring to refuse a request rather than generating an unsafe plan when the task exceeded the model’s capabilities. However, even reasoning models showed declining performance in high-complexity tasks, which hyperparameter tuning (temperature/tokens) did not resolve. Analysis of user interaction reveals that effective prompting is less about linguistic precision and more about "distributed cognition": while models can autonomously plan simple tasks, complex scenarios require the human to reclaim the task planning effort and provide low-level guidance to reduce the solution space. These findings suggest that safe language-driven robotics depends on a dynamic partnership where the distribution of task planning effort shifts based on task difficulty and the capabilities of the specific LLM.
...
Large Language Models (LLMs) promise intuitive robot control through natural language, yet the gap between vague human intent and safe physical execution remains significant. This thesis investigates how the distribution of planning responsibility relates to the reasoning architecture of the model. In a study involving 226 participants who were new users in LLM-based robot prompting, a non-reasoning model (Gemini 2.0 Flash-Lite) and a reasoning model (Gemini 2.5 Pro) were compared on a baseline navigation task, followed by an evaluation of the reasoning model across tasks of increasing logical complexity. Results indicate a clear divergence in safety profiles: non-reasoning models showed more collision-prone goal-seeking behavior, whereas reasoning models demonstrated stricter adherence to the safety constraints in the system prompt, preferring to refuse a request rather than generating an unsafe plan when the task exceeded the model’s capabilities. However, even reasoning models showed declining performance in high-complexity tasks, which hyperparameter tuning (temperature/tokens) did not resolve. Analysis of user interaction reveals that effective prompting is less about linguistic precision and more about "distributed cognition": while models can autonomously plan simple tasks, complex scenarios require the human to reclaim the task planning effort and provide low-level guidance to reduce the solution space. These findings suggest that safe language-driven robotics depends on a dynamic partnership where the distribution of task planning effort shifts based on task difficulty and the capabilities of the specific LLM.
Human drivers routinely make interaction decisions by integrating multimodal, noisy perceptual information over time to decide whether to proceed or yield. Understanding the cognitive mechanisms underlying such decisions is crucial for explaining driver behaviour and for developing models that generalise across traffic scenarios.
This study examines human driver decision-making in a narrow-passage gap-acceptance task, an interaction scenario characterised by ambiguity of priority and described by interdependent kinematic and visual information. Behavioural data from laboratory ($N=36$) and ($N=175$) online experiments were analysed to assess whether decision dynamics generalise across populations with differing variability and experimental control.
Across datasets, decision behaviour showed systematic dependencies on kinematic conditions, with increased reaction times (RTs) and choice variability in ambiguous situations. Longitudinal kinematics-based drift diffusion models (LK-DDMs) captured both decision proportions and reaction-time distributions in the narrow passage task and generalised across datasets with differing coverage of the experimental conditions, including lab and online data. The same accumulation framework transferred to a related decision-making task, indicating that the inferred dynamics are not task-specific. Incorporating visual looming in the drift function yielded selective improvements in short-distance Wait decisions, without global gains in reaction-time accuracy.
OSF link: https://osf.io/5d6em/overview?view_only=18580aa504f24d92a55cbccf53bb5deb ...
This study examines human driver decision-making in a narrow-passage gap-acceptance task, an interaction scenario characterised by ambiguity of priority and described by interdependent kinematic and visual information. Behavioural data from laboratory ($N=36$) and ($N=175$) online experiments were analysed to assess whether decision dynamics generalise across populations with differing variability and experimental control.
Across datasets, decision behaviour showed systematic dependencies on kinematic conditions, with increased reaction times (RTs) and choice variability in ambiguous situations. Longitudinal kinematics-based drift diffusion models (LK-DDMs) captured both decision proportions and reaction-time distributions in the narrow passage task and generalised across datasets with differing coverage of the experimental conditions, including lab and online data. The same accumulation framework transferred to a related decision-making task, indicating that the inferred dynamics are not task-specific. Incorporating visual looming in the drift function yielded selective improvements in short-distance Wait decisions, without global gains in reaction-time accuracy.
OSF link: https://osf.io/5d6em/overview?view_only=18580aa504f24d92a55cbccf53bb5deb ...
Human drivers routinely make interaction decisions by integrating multimodal, noisy perceptual information over time to decide whether to proceed or yield. Understanding the cognitive mechanisms underlying such decisions is crucial for explaining driver behaviour and for developing models that generalise across traffic scenarios.
This study examines human driver decision-making in a narrow-passage gap-acceptance task, an interaction scenario characterised by ambiguity of priority and described by interdependent kinematic and visual information. Behavioural data from laboratory ($N=36$) and ($N=175$) online experiments were analysed to assess whether decision dynamics generalise across populations with differing variability and experimental control.
Across datasets, decision behaviour showed systematic dependencies on kinematic conditions, with increased reaction times (RTs) and choice variability in ambiguous situations. Longitudinal kinematics-based drift diffusion models (LK-DDMs) captured both decision proportions and reaction-time distributions in the narrow passage task and generalised across datasets with differing coverage of the experimental conditions, including lab and online data. The same accumulation framework transferred to a related decision-making task, indicating that the inferred dynamics are not task-specific. Incorporating visual looming in the drift function yielded selective improvements in short-distance Wait decisions, without global gains in reaction-time accuracy.
OSF link: https://osf.io/5d6em/overview?view_only=18580aa504f24d92a55cbccf53bb5deb
This study examines human driver decision-making in a narrow-passage gap-acceptance task, an interaction scenario characterised by ambiguity of priority and described by interdependent kinematic and visual information. Behavioural data from laboratory ($N=36$) and ($N=175$) online experiments were analysed to assess whether decision dynamics generalise across populations with differing variability and experimental control.
Across datasets, decision behaviour showed systematic dependencies on kinematic conditions, with increased reaction times (RTs) and choice variability in ambiguous situations. Longitudinal kinematics-based drift diffusion models (LK-DDMs) captured both decision proportions and reaction-time distributions in the narrow passage task and generalised across datasets with differing coverage of the experimental conditions, including lab and online data. The same accumulation framework transferred to a related decision-making task, indicating that the inferred dynamics are not task-specific. Incorporating visual looming in the drift function yielded selective improvements in short-distance Wait decisions, without global gains in reaction-time accuracy.
OSF link: https://osf.io/5d6em/overview?view_only=18580aa504f24d92a55cbccf53bb5deb
Master thesis
(2025)
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W.J. Kolff, J. Kober, D. Dodou, T.C.T. van Riet, M. Beuling, J.M. Prendergast
Force/torque sensors are essential tools that enable robots to effectively interact with their environments. Existing calibration methods often fail to capture inter-axis nonlinearities and coupling effects, particularly when available calibration data are sparse and discrete. To address this challenge, the presented approach employs a Deep Neural Network (DNN) that learns both the scaling and the direction of the input-output relationship. The method works by extracting the absolute magnitude and unit vector from the raw N-dimensional sensor output values, which can vary among sensors. The DNN takes this N-dimensional input and produces a 7-dimensional output—comprising a corrected 6D unit vector representing the desired force-torque direction and a scaling factor. The final measurement is then constructed by combining the output unit vector, the learned scaling factor, and the original input magnitude. This approach simplifies the calibration problem to a linear mapping along one axis, enabling the model to generalize well under limited training conditions while leveraging the DNN’s strength in capturing nonlinear inter-axis relationships. The proposed DNN was trained and evaluated on both artificially generated and real-world datasets, and its performance was compared to two baseline models: a commonly used linear transformation model and a comparative DNN approach from the literature. On generated data, the proposed DNN achieved an RMSE of 36.9 ± 3.44, outperforming the comparative DNN (48.3 ± 4.47) and the linear transformation model (62.3±0.76). Similar improvements were observed on the real-world dataset. Although these results are promising, they are based on artificially generated data and a single real-world dataset from one specific sensor. Further validation and more extensive testing are necessary. Nonetheless, the gains indicated here suggest meaningful potential for improved calibration strategies in force-controlled robotic applications, even under limited training conditions.
...
Force/torque sensors are essential tools that enable robots to effectively interact with their environments. Existing calibration methods often fail to capture inter-axis nonlinearities and coupling effects, particularly when available calibration data are sparse and discrete. To address this challenge, the presented approach employs a Deep Neural Network (DNN) that learns both the scaling and the direction of the input-output relationship. The method works by extracting the absolute magnitude and unit vector from the raw N-dimensional sensor output values, which can vary among sensors. The DNN takes this N-dimensional input and produces a 7-dimensional output—comprising a corrected 6D unit vector representing the desired force-torque direction and a scaling factor. The final measurement is then constructed by combining the output unit vector, the learned scaling factor, and the original input magnitude. This approach simplifies the calibration problem to a linear mapping along one axis, enabling the model to generalize well under limited training conditions while leveraging the DNN’s strength in capturing nonlinear inter-axis relationships. The proposed DNN was trained and evaluated on both artificially generated and real-world datasets, and its performance was compared to two baseline models: a commonly used linear transformation model and a comparative DNN approach from the literature. On generated data, the proposed DNN achieved an RMSE of 36.9 ± 3.44, outperforming the comparative DNN (48.3 ± 4.47) and the linear transformation model (62.3±0.76). Similar improvements were observed on the real-world dataset. Although these results are promising, they are based on artificially generated data and a single real-world dataset from one specific sensor. Further validation and more extensive testing are necessary. Nonetheless, the gains indicated here suggest meaningful potential for improved calibration strategies in force-controlled robotic applications, even under limited training conditions.
Assessing Human Drivers
From Raw Data to Context-Aware Interpretations
Road traffic accidents remain a major public health concern worldwide. Technological advances in vehicle sensing, automation, and artificial intelligence present novel opportunities to assess and improve human driving. This dissertation explores these opportunities by developing and evaluating algorithms to assess the behavior of car and truck drivers.
Initial research establishes the perspectives of driving examiners and professional truck drivers on the acceptance of data-driven tools to assess driver behavior. The work then demonstrates that practical methods using readily available GPS and accelerometer data can successfully identify driving styles and predict negative outcomes like fines and damage incidents at a population level. However, these simple metrics prove insufficient for fair individual assessment due to the lack of situational context embedded in such data.
To address this limitation, the thesis explores modern AI-based approaches. It demonstrates how AI systems from automated driving can provide continuous behavioral references to evaluate human performance, and concludes by showing that vision-language models can establish a more holistic, "context-aware" risk assessment using images of typical traffic situations. ...
Initial research establishes the perspectives of driving examiners and professional truck drivers on the acceptance of data-driven tools to assess driver behavior. The work then demonstrates that practical methods using readily available GPS and accelerometer data can successfully identify driving styles and predict negative outcomes like fines and damage incidents at a population level. However, these simple metrics prove insufficient for fair individual assessment due to the lack of situational context embedded in such data.
To address this limitation, the thesis explores modern AI-based approaches. It demonstrates how AI systems from automated driving can provide continuous behavioral references to evaluate human performance, and concludes by showing that vision-language models can establish a more holistic, "context-aware" risk assessment using images of typical traffic situations. ...
Road traffic accidents remain a major public health concern worldwide. Technological advances in vehicle sensing, automation, and artificial intelligence present novel opportunities to assess and improve human driving. This dissertation explores these opportunities by developing and evaluating algorithms to assess the behavior of car and truck drivers.
Initial research establishes the perspectives of driving examiners and professional truck drivers on the acceptance of data-driven tools to assess driver behavior. The work then demonstrates that practical methods using readily available GPS and accelerometer data can successfully identify driving styles and predict negative outcomes like fines and damage incidents at a population level. However, these simple metrics prove insufficient for fair individual assessment due to the lack of situational context embedded in such data.
To address this limitation, the thesis explores modern AI-based approaches. It demonstrates how AI systems from automated driving can provide continuous behavioral references to evaluate human performance, and concludes by showing that vision-language models can establish a more holistic, "context-aware" risk assessment using images of typical traffic situations.
Initial research establishes the perspectives of driving examiners and professional truck drivers on the acceptance of data-driven tools to assess driver behavior. The work then demonstrates that practical methods using readily available GPS and accelerometer data can successfully identify driving styles and predict negative outcomes like fines and damage incidents at a population level. However, these simple metrics prove insufficient for fair individual assessment due to the lack of situational context embedded in such data.
To address this limitation, the thesis explores modern AI-based approaches. It demonstrates how AI systems from automated driving can provide continuous behavioral references to evaluate human performance, and concludes by showing that vision-language models can establish a more holistic, "context-aware" risk assessment using images of typical traffic situations.
A large number of traffic accidents occur worldwide each year, of which a sizable portion involve pedestrians, making them a vulnerable group on the road. Many of these accidents occur due to visual distraction, meaning drivers and pedestrians fail to look where they should be looking. In addition to this tendency for distraction, the eyes are a means of exchanging information between road users, via behaviors such as eye contact. However, the role and importance of eye contact in traffic in connection with traffic safety and the decisions of road users is not yet entirely clear. Further, with the advent of automated vehicles, the role of eye contact in traffic may change or disappear altogether, due to the absence of drivers. One promising way to shed light on this matter is to use eye-tracking, a technology which can measure the eye movements of road users, and which might allow the engineering of solutions to mitigate the frequency and severity of accidents.
This dissertation aims to investigate the role of eye contact between drivers and pedestrians, as well as its influence on pedestrians’ road crossing intentions. Another aim of this dissertation is to assess the accuracy of eye-tracking devices and to objectively detect and operationalize driver-pedestrian eye contact using eye-tracking. Finally, this thesis aims to develop safety systems based on eye-tracking that can automatically analyze and contextualize gaze in traffic and warn vulnerable road users of danger. This thesis consists of four independently readable and empirical research papers.
The first study examines the effect of drivers’ eye contact on pedestrians’ crossing decisions using an online crowdsourced experiment. It shows that, although a car’s kinematics have a dominant effect, a driver’s eye contact also makes pedestrians feel safer and more likely to cross the road, and that the timing of the driver’s eye contact has an influence as well. The second study benchmarks the accuracies of mobile eye-trackers under static and dynamic conditions, finding that eccentricity worsens accuracy, but dynamicity does not necessarily worsen it. The third study presents a method to objectively detect and operationalize driver-pedestrian eye contact using two synchronized eye-trackers and computer vision, defining eye contact as mutual gaze within a 4° threshold. The fourth study explores the integration of mobile eye-tracking, object detection, and a vision-language model in an attempt to develop a real-time, context-aware safety system that can assess risk in traffic and enhance the situational awareness of road users.
This dissertation concludes that while eye contact is neither as powerful a cue as kinematics nor essential for crossing, it is still a “should-have” in driver-pedestrian interactions as it can increase perceived safety and willingness to cross. This thesis also concludes that certain types of external Human Machine Interfaces (eHMIs) – substitutes for the missing eye contact between pedestrians and automated vehicles – would be beneficial to maintain existing levels of comfort in interactions. Finally, this thesis also highlights the potential of using mobile eye-tracking in combination with computer vision and AI for applications in the traffic, manufacturing, medical, education, and other domains, and recommends topics for further research into eye contact and eye-tracking.
...
This dissertation aims to investigate the role of eye contact between drivers and pedestrians, as well as its influence on pedestrians’ road crossing intentions. Another aim of this dissertation is to assess the accuracy of eye-tracking devices and to objectively detect and operationalize driver-pedestrian eye contact using eye-tracking. Finally, this thesis aims to develop safety systems based on eye-tracking that can automatically analyze and contextualize gaze in traffic and warn vulnerable road users of danger. This thesis consists of four independently readable and empirical research papers.
The first study examines the effect of drivers’ eye contact on pedestrians’ crossing decisions using an online crowdsourced experiment. It shows that, although a car’s kinematics have a dominant effect, a driver’s eye contact also makes pedestrians feel safer and more likely to cross the road, and that the timing of the driver’s eye contact has an influence as well. The second study benchmarks the accuracies of mobile eye-trackers under static and dynamic conditions, finding that eccentricity worsens accuracy, but dynamicity does not necessarily worsen it. The third study presents a method to objectively detect and operationalize driver-pedestrian eye contact using two synchronized eye-trackers and computer vision, defining eye contact as mutual gaze within a 4° threshold. The fourth study explores the integration of mobile eye-tracking, object detection, and a vision-language model in an attempt to develop a real-time, context-aware safety system that can assess risk in traffic and enhance the situational awareness of road users.
This dissertation concludes that while eye contact is neither as powerful a cue as kinematics nor essential for crossing, it is still a “should-have” in driver-pedestrian interactions as it can increase perceived safety and willingness to cross. This thesis also concludes that certain types of external Human Machine Interfaces (eHMIs) – substitutes for the missing eye contact between pedestrians and automated vehicles – would be beneficial to maintain existing levels of comfort in interactions. Finally, this thesis also highlights the potential of using mobile eye-tracking in combination with computer vision and AI for applications in the traffic, manufacturing, medical, education, and other domains, and recommends topics for further research into eye contact and eye-tracking.
...
A large number of traffic accidents occur worldwide each year, of which a sizable portion involve pedestrians, making them a vulnerable group on the road. Many of these accidents occur due to visual distraction, meaning drivers and pedestrians fail to look where they should be looking. In addition to this tendency for distraction, the eyes are a means of exchanging information between road users, via behaviors such as eye contact. However, the role and importance of eye contact in traffic in connection with traffic safety and the decisions of road users is not yet entirely clear. Further, with the advent of automated vehicles, the role of eye contact in traffic may change or disappear altogether, due to the absence of drivers. One promising way to shed light on this matter is to use eye-tracking, a technology which can measure the eye movements of road users, and which might allow the engineering of solutions to mitigate the frequency and severity of accidents.
This dissertation aims to investigate the role of eye contact between drivers and pedestrians, as well as its influence on pedestrians’ road crossing intentions. Another aim of this dissertation is to assess the accuracy of eye-tracking devices and to objectively detect and operationalize driver-pedestrian eye contact using eye-tracking. Finally, this thesis aims to develop safety systems based on eye-tracking that can automatically analyze and contextualize gaze in traffic and warn vulnerable road users of danger. This thesis consists of four independently readable and empirical research papers.
The first study examines the effect of drivers’ eye contact on pedestrians’ crossing decisions using an online crowdsourced experiment. It shows that, although a car’s kinematics have a dominant effect, a driver’s eye contact also makes pedestrians feel safer and more likely to cross the road, and that the timing of the driver’s eye contact has an influence as well. The second study benchmarks the accuracies of mobile eye-trackers under static and dynamic conditions, finding that eccentricity worsens accuracy, but dynamicity does not necessarily worsen it. The third study presents a method to objectively detect and operationalize driver-pedestrian eye contact using two synchronized eye-trackers and computer vision, defining eye contact as mutual gaze within a 4° threshold. The fourth study explores the integration of mobile eye-tracking, object detection, and a vision-language model in an attempt to develop a real-time, context-aware safety system that can assess risk in traffic and enhance the situational awareness of road users.
This dissertation concludes that while eye contact is neither as powerful a cue as kinematics nor essential for crossing, it is still a “should-have” in driver-pedestrian interactions as it can increase perceived safety and willingness to cross. This thesis also concludes that certain types of external Human Machine Interfaces (eHMIs) – substitutes for the missing eye contact between pedestrians and automated vehicles – would be beneficial to maintain existing levels of comfort in interactions. Finally, this thesis also highlights the potential of using mobile eye-tracking in combination with computer vision and AI for applications in the traffic, manufacturing, medical, education, and other domains, and recommends topics for further research into eye contact and eye-tracking.
This dissertation aims to investigate the role of eye contact between drivers and pedestrians, as well as its influence on pedestrians’ road crossing intentions. Another aim of this dissertation is to assess the accuracy of eye-tracking devices and to objectively detect and operationalize driver-pedestrian eye contact using eye-tracking. Finally, this thesis aims to develop safety systems based on eye-tracking that can automatically analyze and contextualize gaze in traffic and warn vulnerable road users of danger. This thesis consists of four independently readable and empirical research papers.
The first study examines the effect of drivers’ eye contact on pedestrians’ crossing decisions using an online crowdsourced experiment. It shows that, although a car’s kinematics have a dominant effect, a driver’s eye contact also makes pedestrians feel safer and more likely to cross the road, and that the timing of the driver’s eye contact has an influence as well. The second study benchmarks the accuracies of mobile eye-trackers under static and dynamic conditions, finding that eccentricity worsens accuracy, but dynamicity does not necessarily worsen it. The third study presents a method to objectively detect and operationalize driver-pedestrian eye contact using two synchronized eye-trackers and computer vision, defining eye contact as mutual gaze within a 4° threshold. The fourth study explores the integration of mobile eye-tracking, object detection, and a vision-language model in an attempt to develop a real-time, context-aware safety system that can assess risk in traffic and enhance the situational awareness of road users.
This dissertation concludes that while eye contact is neither as powerful a cue as kinematics nor essential for crossing, it is still a “should-have” in driver-pedestrian interactions as it can increase perceived safety and willingness to cross. This thesis also concludes that certain types of external Human Machine Interfaces (eHMIs) – substitutes for the missing eye contact between pedestrians and automated vehicles – would be beneficial to maintain existing levels of comfort in interactions. Finally, this thesis also highlights the potential of using mobile eye-tracking in combination with computer vision and AI for applications in the traffic, manufacturing, medical, education, and other domains, and recommends topics for further research into eye contact and eye-tracking.
Objective: The aim of this study was to investigate the effect of autonomous-vehicle-to-pedestrian (AV2P) communication through augmented reality (AR) interfaces on the road crossing behaviour of pedestrians, and research whether subjective results from a previous Cave Automatic Virtual Environment (CAVE) study replicated in a real world AR experiment.
Background: Previous studies investigating the effects of AV2P communication have mostly been conducted through virtual reality (VR) providing researchers with safe experimentation methods and high experimental control, but also resulting in a common limitation: the lack of ecological validity and realism, thereby affecting participants’ behaviour and causing distractions. This study therefore introduces AR experiments that have been conducted in a real world environment to increase ecological validity.
Methods: An AR experiment was conducted in which 28 participants were situated in the real world with the objective to cross the road. The virtual vehicle, that was projected through a Varjo XR-3 head mounted display, approached from the right at a speed of 30 km/h while 4 interfaces (2x world-locked, head-locked, and vehicle-locked) appeared to communicate the vehicle’s intention towards the participants, in addition to a no-interface baseline. Participants were tasked with indicating when they were willing to cross through the push of a remote button from which their Willingness to cross and Decision certainty could be derived. Subjective data was collected after the trials and after the experiment through interviews and a questionnaire respectively.
Results: Results suggest a positive effect of the AV2P interfaces on the Willingness to cross and Decision certainty, although statistically not significant. In other words, Willingness to cross increases when the vehicle indicates that it will yield, and decreases when the vehicle communicates that it will not yield. Decision certainty also increases when an interface is present compared to the no-interface baseline. Moreover, participants indicated using the interfaces as a tool to validate their own decisions. Compared to the CAVE study, subjective intuitiveness ratings replicate in terms of observing higher intuitiveness of the interfaces than the no-interface baseline. However, the intuitiveness ratings were higher in the CAVE study than the real world AR experiment. Furthermore, the order of the top 3 most preferred interfaces ranking is in the opposite order. Both differences suggest that the increased ecological validity of the real world AR experiment introduces new insights into participants’ perception of interfaces. The Van der Laan acceptance scale shows that participants believe interfaces to be useful and satisfying overall.
Conclusion: The experiments suggest that AV2P interfaces have a positive effect on the crossing behaviour of pedestrians. Furthermore, participants indicate using the interfaces as a tool to validate their own decision, which increases confidence in their decisions. Although results partially replicate a previous virtual environment study, there are differences that suggest that real world AR experiments provide valuable insights into participants’ perception of interfaces in a more realistic experiment. ...
Background: Previous studies investigating the effects of AV2P communication have mostly been conducted through virtual reality (VR) providing researchers with safe experimentation methods and high experimental control, but also resulting in a common limitation: the lack of ecological validity and realism, thereby affecting participants’ behaviour and causing distractions. This study therefore introduces AR experiments that have been conducted in a real world environment to increase ecological validity.
Methods: An AR experiment was conducted in which 28 participants were situated in the real world with the objective to cross the road. The virtual vehicle, that was projected through a Varjo XR-3 head mounted display, approached from the right at a speed of 30 km/h while 4 interfaces (2x world-locked, head-locked, and vehicle-locked) appeared to communicate the vehicle’s intention towards the participants, in addition to a no-interface baseline. Participants were tasked with indicating when they were willing to cross through the push of a remote button from which their Willingness to cross and Decision certainty could be derived. Subjective data was collected after the trials and after the experiment through interviews and a questionnaire respectively.
Results: Results suggest a positive effect of the AV2P interfaces on the Willingness to cross and Decision certainty, although statistically not significant. In other words, Willingness to cross increases when the vehicle indicates that it will yield, and decreases when the vehicle communicates that it will not yield. Decision certainty also increases when an interface is present compared to the no-interface baseline. Moreover, participants indicated using the interfaces as a tool to validate their own decisions. Compared to the CAVE study, subjective intuitiveness ratings replicate in terms of observing higher intuitiveness of the interfaces than the no-interface baseline. However, the intuitiveness ratings were higher in the CAVE study than the real world AR experiment. Furthermore, the order of the top 3 most preferred interfaces ranking is in the opposite order. Both differences suggest that the increased ecological validity of the real world AR experiment introduces new insights into participants’ perception of interfaces. The Van der Laan acceptance scale shows that participants believe interfaces to be useful and satisfying overall.
Conclusion: The experiments suggest that AV2P interfaces have a positive effect on the crossing behaviour of pedestrians. Furthermore, participants indicate using the interfaces as a tool to validate their own decision, which increases confidence in their decisions. Although results partially replicate a previous virtual environment study, there are differences that suggest that real world AR experiments provide valuable insights into participants’ perception of interfaces in a more realistic experiment. ...
Objective: The aim of this study was to investigate the effect of autonomous-vehicle-to-pedestrian (AV2P) communication through augmented reality (AR) interfaces on the road crossing behaviour of pedestrians, and research whether subjective results from a previous Cave Automatic Virtual Environment (CAVE) study replicated in a real world AR experiment.
Background: Previous studies investigating the effects of AV2P communication have mostly been conducted through virtual reality (VR) providing researchers with safe experimentation methods and high experimental control, but also resulting in a common limitation: the lack of ecological validity and realism, thereby affecting participants’ behaviour and causing distractions. This study therefore introduces AR experiments that have been conducted in a real world environment to increase ecological validity.
Methods: An AR experiment was conducted in which 28 participants were situated in the real world with the objective to cross the road. The virtual vehicle, that was projected through a Varjo XR-3 head mounted display, approached from the right at a speed of 30 km/h while 4 interfaces (2x world-locked, head-locked, and vehicle-locked) appeared to communicate the vehicle’s intention towards the participants, in addition to a no-interface baseline. Participants were tasked with indicating when they were willing to cross through the push of a remote button from which their Willingness to cross and Decision certainty could be derived. Subjective data was collected after the trials and after the experiment through interviews and a questionnaire respectively.
Results: Results suggest a positive effect of the AV2P interfaces on the Willingness to cross and Decision certainty, although statistically not significant. In other words, Willingness to cross increases when the vehicle indicates that it will yield, and decreases when the vehicle communicates that it will not yield. Decision certainty also increases when an interface is present compared to the no-interface baseline. Moreover, participants indicated using the interfaces as a tool to validate their own decisions. Compared to the CAVE study, subjective intuitiveness ratings replicate in terms of observing higher intuitiveness of the interfaces than the no-interface baseline. However, the intuitiveness ratings were higher in the CAVE study than the real world AR experiment. Furthermore, the order of the top 3 most preferred interfaces ranking is in the opposite order. Both differences suggest that the increased ecological validity of the real world AR experiment introduces new insights into participants’ perception of interfaces. The Van der Laan acceptance scale shows that participants believe interfaces to be useful and satisfying overall.
Conclusion: The experiments suggest that AV2P interfaces have a positive effect on the crossing behaviour of pedestrians. Furthermore, participants indicate using the interfaces as a tool to validate their own decision, which increases confidence in their decisions. Although results partially replicate a previous virtual environment study, there are differences that suggest that real world AR experiments provide valuable insights into participants’ perception of interfaces in a more realistic experiment.
Background: Previous studies investigating the effects of AV2P communication have mostly been conducted through virtual reality (VR) providing researchers with safe experimentation methods and high experimental control, but also resulting in a common limitation: the lack of ecological validity and realism, thereby affecting participants’ behaviour and causing distractions. This study therefore introduces AR experiments that have been conducted in a real world environment to increase ecological validity.
Methods: An AR experiment was conducted in which 28 participants were situated in the real world with the objective to cross the road. The virtual vehicle, that was projected through a Varjo XR-3 head mounted display, approached from the right at a speed of 30 km/h while 4 interfaces (2x world-locked, head-locked, and vehicle-locked) appeared to communicate the vehicle’s intention towards the participants, in addition to a no-interface baseline. Participants were tasked with indicating when they were willing to cross through the push of a remote button from which their Willingness to cross and Decision certainty could be derived. Subjective data was collected after the trials and after the experiment through interviews and a questionnaire respectively.
Results: Results suggest a positive effect of the AV2P interfaces on the Willingness to cross and Decision certainty, although statistically not significant. In other words, Willingness to cross increases when the vehicle indicates that it will yield, and decreases when the vehicle communicates that it will not yield. Decision certainty also increases when an interface is present compared to the no-interface baseline. Moreover, participants indicated using the interfaces as a tool to validate their own decisions. Compared to the CAVE study, subjective intuitiveness ratings replicate in terms of observing higher intuitiveness of the interfaces than the no-interface baseline. However, the intuitiveness ratings were higher in the CAVE study than the real world AR experiment. Furthermore, the order of the top 3 most preferred interfaces ranking is in the opposite order. Both differences suggest that the increased ecological validity of the real world AR experiment introduces new insights into participants’ perception of interfaces. The Van der Laan acceptance scale shows that participants believe interfaces to be useful and satisfying overall.
Conclusion: The experiments suggest that AV2P interfaces have a positive effect on the crossing behaviour of pedestrians. Furthermore, participants indicate using the interfaces as a tool to validate their own decision, which increases confidence in their decisions. Although results partially replicate a previous virtual environment study, there are differences that suggest that real world AR experiments provide valuable insights into participants’ perception of interfaces in a more realistic experiment.
Save the meadow birds
Bird nest localization system for autonomous mowing machines
Master thesis
(2023)
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J.M.A. Schuurmans, Y.B. Eisma, D. Boonstra, J. Wijkhuizen, D. Dodou, J.F.P. Kooij
Inadvertent bird nest destruction by autonomous mowing machines poses significant threats to the breeding success of meadow birds. Drone-based detection methods represent the current state-of-the-art for bird nest localization to attain mower circumvention. However, they only identify 80% of bird nests with average localization error of 3.344 meters and are restricted to specific application times. This paper introduces alternative, fully automated nest localization systems integrated with autonomous mowers. Two strategies are proposed, 1) Directly detecting bird nests using thermal data, or 2) Indirectly, by tracking birds and extrapolating their trajectories back to their nests using RGBD data. These methods were validated with warmed chicken eggs hidden in grasslands and with drones simulating bird flight. YOLOv8 models were modified for both approaches. The thermal localization method is able to detect all bird nests with an average confidence of 73.4%. It allows for real-time localization and yields one unnecessary nest circumvention for every ten bird nests saved due to false positives. This method is shown to be effective in all breeding season temperatures, both day and night. Conversely, the trajectory extrapolation method detects birds with an average confidence of 82.2% and has localization error of 0.794 meters. Birds taking flight prematurely or from locations other than nests impact the number of bird nests saved and the number of unnecessary circumventions. It is demonstrated that this method fails to detect birds during nighttime. In conclusion, an automated thermal-based localization system integrated with autonomous mowers outperforms both RGBD- and current state-of-the-art drone-based methods. This study highlights therefore the potential of thermal-based solutions for bird nest protection in grasslands.
...
Inadvertent bird nest destruction by autonomous mowing machines poses significant threats to the breeding success of meadow birds. Drone-based detection methods represent the current state-of-the-art for bird nest localization to attain mower circumvention. However, they only identify 80% of bird nests with average localization error of 3.344 meters and are restricted to specific application times. This paper introduces alternative, fully automated nest localization systems integrated with autonomous mowers. Two strategies are proposed, 1) Directly detecting bird nests using thermal data, or 2) Indirectly, by tracking birds and extrapolating their trajectories back to their nests using RGBD data. These methods were validated with warmed chicken eggs hidden in grasslands and with drones simulating bird flight. YOLOv8 models were modified for both approaches. The thermal localization method is able to detect all bird nests with an average confidence of 73.4%. It allows for real-time localization and yields one unnecessary nest circumvention for every ten bird nests saved due to false positives. This method is shown to be effective in all breeding season temperatures, both day and night. Conversely, the trajectory extrapolation method detects birds with an average confidence of 82.2% and has localization error of 0.794 meters. Birds taking flight prematurely or from locations other than nests impact the number of bird nests saved and the number of unnecessary circumventions. It is demonstrated that this method fails to detect birds during nighttime. In conclusion, an automated thermal-based localization system integrated with autonomous mowers outperforms both RGBD- and current state-of-the-art drone-based methods. This study highlights therefore the potential of thermal-based solutions for bird nest protection in grasslands.
Master thesis
(2023)
-
A.K. Kejriwal, Y. Vardar, J. Krishnaswamy Balasubramanian, J.C.F. de Winter, D. Dodou
Electrovibration offers potential to enrich virtual touch experiences with authentic tactile sensations on touchscreens. In controlled environments, responses to tactile stimuli may be anticipated, yet this predictability becomes uncertain in unconstrained settings due to dynamic factors like varied applied force, finger scanning speed, and sensory adaptation. To address this issue, we conducted a psychophysical study with 21 participants to investigate the effect of tactile
rendering parameters on user exploratory behaviour and perception during unconstrained exploration of artificial textures, aiming to discern a predominant tendency of interaction. Our results revealed, signal amplitude shapes human tactile
perception considerably during unconstrained exploration. We also observed, higher signal amplitudes were associated with lower finger scanning speeds, a trend tempered by significant individual differences, thereby affecting its practical effect. In contrast, the measured applied normal force and obtained finger movement pattern remained consistent and were not affected by different tactile rendering parameters. Notably, the rate of change of measured lateral force was found
to be a better metric for the perceived tactile dimensions than the lateral force magnitude. These findings enhance our understanding of perception and physics of such interactions, that could be vital for designing and delivering improved
haptic feedback on electrovibration-based tactile interfaces. ...
rendering parameters on user exploratory behaviour and perception during unconstrained exploration of artificial textures, aiming to discern a predominant tendency of interaction. Our results revealed, signal amplitude shapes human tactile
perception considerably during unconstrained exploration. We also observed, higher signal amplitudes were associated with lower finger scanning speeds, a trend tempered by significant individual differences, thereby affecting its practical effect. In contrast, the measured applied normal force and obtained finger movement pattern remained consistent and were not affected by different tactile rendering parameters. Notably, the rate of change of measured lateral force was found
to be a better metric for the perceived tactile dimensions than the lateral force magnitude. These findings enhance our understanding of perception and physics of such interactions, that could be vital for designing and delivering improved
haptic feedback on electrovibration-based tactile interfaces. ...
Electrovibration offers potential to enrich virtual touch experiences with authentic tactile sensations on touchscreens. In controlled environments, responses to tactile stimuli may be anticipated, yet this predictability becomes uncertain in unconstrained settings due to dynamic factors like varied applied force, finger scanning speed, and sensory adaptation. To address this issue, we conducted a psychophysical study with 21 participants to investigate the effect of tactile
rendering parameters on user exploratory behaviour and perception during unconstrained exploration of artificial textures, aiming to discern a predominant tendency of interaction. Our results revealed, signal amplitude shapes human tactile
perception considerably during unconstrained exploration. We also observed, higher signal amplitudes were associated with lower finger scanning speeds, a trend tempered by significant individual differences, thereby affecting its practical effect. In contrast, the measured applied normal force and obtained finger movement pattern remained consistent and were not affected by different tactile rendering parameters. Notably, the rate of change of measured lateral force was found
to be a better metric for the perceived tactile dimensions than the lateral force magnitude. These findings enhance our understanding of perception and physics of such interactions, that could be vital for designing and delivering improved
haptic feedback on electrovibration-based tactile interfaces.
rendering parameters on user exploratory behaviour and perception during unconstrained exploration of artificial textures, aiming to discern a predominant tendency of interaction. Our results revealed, signal amplitude shapes human tactile
perception considerably during unconstrained exploration. We also observed, higher signal amplitudes were associated with lower finger scanning speeds, a trend tempered by significant individual differences, thereby affecting its practical effect. In contrast, the measured applied normal force and obtained finger movement pattern remained consistent and were not affected by different tactile rendering parameters. Notably, the rate of change of measured lateral force was found
to be a better metric for the perceived tactile dimensions than the lateral force magnitude. These findings enhance our understanding of perception and physics of such interactions, that could be vital for designing and delivering improved
haptic feedback on electrovibration-based tactile interfaces.
Towards continuous feedback on soft tissue anatomy during a percutaneous needle procedure in the liver
Exploring the use of endovascular markers to track the tumor location
Master thesis
(2023)
-
M.F. van Dommele, D. Dodou, Peggy Goossen-Nachtigall, Anne-Hilde Muris, J.C.F. de Winter
Percutaneous needle procedures (PNPs) are minimally invasive procedures that use imaging guidance to diagnose or treat medical conditions. In the treatment of liver cancer, PNPs are becoming increasingly used due to their shorter recovery times and lower complication rates. However, needle placement during PNPs can be challenging due to a lack of direct visualization of the target and liver tissue deformation caused by respiratory motion, patient (re)positioning, and needle insertion. Currently, no imaging modality provides continuous, qualitative visualization while maintaining acceptable radiation levels. Continuous feedback during PNPs could improve needle placement accuracy by enabling real-time adjustments in response to tissue deformation. Previous studies have used external- and internal markers for continuous feedback, but these markers have not been able to fully capture tumor displacement and the underlying causes of deformation. Endovascular insertion is a potential solution to this problem - it involves placing the marker close to the tumor by inserting it through the blood vessels. Here, we present exploratory research that aims to investigate the possibility of using an endovascular marker to capture the displacement of a liver tumor during a PNP.
An ex-vivo porcine liver with artificially created tumors and endovascular catheter markers was used. In the first experiment, robotic-assisted needle insertion was performed on seven tumors with a 13-gauge ablation needle. The second experiment involved simulating respiratory motion with an inflatable sachet to mimic the lungs and create a representable blow zone (the area affected by the inflated sachet). The displacement of the tumor- and endovascular catheter markers were tracked in the x-, y-, and z-directions using a C-arm system making Cone Beam Computed Tomography (CBCT). The x- and y-directions represents the horizontal plane within the liver, and the z-direction is the vertical plane (the direction of the ablation needle). The average offset in millimeters was calculated to quantify the error between the tumor- and catheter marker displacement.
The results of needle insertion showed that catheter markers placed 8-28 mm from the tumor could deduce tumor displacement in the x-direction, with a maximum offset of 1.23 mm. The catheter markers placed 8-13 mm from the tumor were also able to deduce displacement in the z-direction with a maximum offset of 0.23 mm and in Euclidean distance (total path length as measured using Pythagoras' theorem) with a maximum offset of 0.73 mm. Furthermore, the results indicated that, on average, catheter markers placed 8-28 mm from the tumor were able to accurately deduce tumor displacement for needle insertion depths of 0-15 mm. During respiratory motion simulation, tumor- and catheter marker displacement was influenced more by blow zone location than the distance between them. To apply these findings to the human body, it is recommended that the endovascular marker will be positioned in the same sagittal (longitudinal) and coronal (frontal) plane as the tumor. In this study, catheter markers could be used to deduce tumor displacement for inflation volumes of 0-500 ml, which is the typical resting breathing volume.
In conclusion, this study demonstrated that the ability to use endovascular catheter markers to deduce tumor displacement during a percutaneous needle procedure is influenced by the distance between the tumor- and the catheter marker, the depth of the needle, the inflation volume of simulated lungs, and whether the marker is positioned in the same sagittal and coronal plane in relation to the tumor. Future research should focus on determining the optimal number and location of endovascular markers, including a bigger variation and spread of tumor locations, and adjusting insertion techniques, to further realize the clinical applicability of endovascular catheter markers in percutaneous needle procedures. ...
An ex-vivo porcine liver with artificially created tumors and endovascular catheter markers was used. In the first experiment, robotic-assisted needle insertion was performed on seven tumors with a 13-gauge ablation needle. The second experiment involved simulating respiratory motion with an inflatable sachet to mimic the lungs and create a representable blow zone (the area affected by the inflated sachet). The displacement of the tumor- and endovascular catheter markers were tracked in the x-, y-, and z-directions using a C-arm system making Cone Beam Computed Tomography (CBCT). The x- and y-directions represents the horizontal plane within the liver, and the z-direction is the vertical plane (the direction of the ablation needle). The average offset in millimeters was calculated to quantify the error between the tumor- and catheter marker displacement.
The results of needle insertion showed that catheter markers placed 8-28 mm from the tumor could deduce tumor displacement in the x-direction, with a maximum offset of 1.23 mm. The catheter markers placed 8-13 mm from the tumor were also able to deduce displacement in the z-direction with a maximum offset of 0.23 mm and in Euclidean distance (total path length as measured using Pythagoras' theorem) with a maximum offset of 0.73 mm. Furthermore, the results indicated that, on average, catheter markers placed 8-28 mm from the tumor were able to accurately deduce tumor displacement for needle insertion depths of 0-15 mm. During respiratory motion simulation, tumor- and catheter marker displacement was influenced more by blow zone location than the distance between them. To apply these findings to the human body, it is recommended that the endovascular marker will be positioned in the same sagittal (longitudinal) and coronal (frontal) plane as the tumor. In this study, catheter markers could be used to deduce tumor displacement for inflation volumes of 0-500 ml, which is the typical resting breathing volume.
In conclusion, this study demonstrated that the ability to use endovascular catheter markers to deduce tumor displacement during a percutaneous needle procedure is influenced by the distance between the tumor- and the catheter marker, the depth of the needle, the inflation volume of simulated lungs, and whether the marker is positioned in the same sagittal and coronal plane in relation to the tumor. Future research should focus on determining the optimal number and location of endovascular markers, including a bigger variation and spread of tumor locations, and adjusting insertion techniques, to further realize the clinical applicability of endovascular catheter markers in percutaneous needle procedures. ...
Percutaneous needle procedures (PNPs) are minimally invasive procedures that use imaging guidance to diagnose or treat medical conditions. In the treatment of liver cancer, PNPs are becoming increasingly used due to their shorter recovery times and lower complication rates. However, needle placement during PNPs can be challenging due to a lack of direct visualization of the target and liver tissue deformation caused by respiratory motion, patient (re)positioning, and needle insertion. Currently, no imaging modality provides continuous, qualitative visualization while maintaining acceptable radiation levels. Continuous feedback during PNPs could improve needle placement accuracy by enabling real-time adjustments in response to tissue deformation. Previous studies have used external- and internal markers for continuous feedback, but these markers have not been able to fully capture tumor displacement and the underlying causes of deformation. Endovascular insertion is a potential solution to this problem - it involves placing the marker close to the tumor by inserting it through the blood vessels. Here, we present exploratory research that aims to investigate the possibility of using an endovascular marker to capture the displacement of a liver tumor during a PNP.
An ex-vivo porcine liver with artificially created tumors and endovascular catheter markers was used. In the first experiment, robotic-assisted needle insertion was performed on seven tumors with a 13-gauge ablation needle. The second experiment involved simulating respiratory motion with an inflatable sachet to mimic the lungs and create a representable blow zone (the area affected by the inflated sachet). The displacement of the tumor- and endovascular catheter markers were tracked in the x-, y-, and z-directions using a C-arm system making Cone Beam Computed Tomography (CBCT). The x- and y-directions represents the horizontal plane within the liver, and the z-direction is the vertical plane (the direction of the ablation needle). The average offset in millimeters was calculated to quantify the error between the tumor- and catheter marker displacement.
The results of needle insertion showed that catheter markers placed 8-28 mm from the tumor could deduce tumor displacement in the x-direction, with a maximum offset of 1.23 mm. The catheter markers placed 8-13 mm from the tumor were also able to deduce displacement in the z-direction with a maximum offset of 0.23 mm and in Euclidean distance (total path length as measured using Pythagoras' theorem) with a maximum offset of 0.73 mm. Furthermore, the results indicated that, on average, catheter markers placed 8-28 mm from the tumor were able to accurately deduce tumor displacement for needle insertion depths of 0-15 mm. During respiratory motion simulation, tumor- and catheter marker displacement was influenced more by blow zone location than the distance between them. To apply these findings to the human body, it is recommended that the endovascular marker will be positioned in the same sagittal (longitudinal) and coronal (frontal) plane as the tumor. In this study, catheter markers could be used to deduce tumor displacement for inflation volumes of 0-500 ml, which is the typical resting breathing volume.
In conclusion, this study demonstrated that the ability to use endovascular catheter markers to deduce tumor displacement during a percutaneous needle procedure is influenced by the distance between the tumor- and the catheter marker, the depth of the needle, the inflation volume of simulated lungs, and whether the marker is positioned in the same sagittal and coronal plane in relation to the tumor. Future research should focus on determining the optimal number and location of endovascular markers, including a bigger variation and spread of tumor locations, and adjusting insertion techniques, to further realize the clinical applicability of endovascular catheter markers in percutaneous needle procedures.
An ex-vivo porcine liver with artificially created tumors and endovascular catheter markers was used. In the first experiment, robotic-assisted needle insertion was performed on seven tumors with a 13-gauge ablation needle. The second experiment involved simulating respiratory motion with an inflatable sachet to mimic the lungs and create a representable blow zone (the area affected by the inflated sachet). The displacement of the tumor- and endovascular catheter markers were tracked in the x-, y-, and z-directions using a C-arm system making Cone Beam Computed Tomography (CBCT). The x- and y-directions represents the horizontal plane within the liver, and the z-direction is the vertical plane (the direction of the ablation needle). The average offset in millimeters was calculated to quantify the error between the tumor- and catheter marker displacement.
The results of needle insertion showed that catheter markers placed 8-28 mm from the tumor could deduce tumor displacement in the x-direction, with a maximum offset of 1.23 mm. The catheter markers placed 8-13 mm from the tumor were also able to deduce displacement in the z-direction with a maximum offset of 0.23 mm and in Euclidean distance (total path length as measured using Pythagoras' theorem) with a maximum offset of 0.73 mm. Furthermore, the results indicated that, on average, catheter markers placed 8-28 mm from the tumor were able to accurately deduce tumor displacement for needle insertion depths of 0-15 mm. During respiratory motion simulation, tumor- and catheter marker displacement was influenced more by blow zone location than the distance between them. To apply these findings to the human body, it is recommended that the endovascular marker will be positioned in the same sagittal (longitudinal) and coronal (frontal) plane as the tumor. In this study, catheter markers could be used to deduce tumor displacement for inflation volumes of 0-500 ml, which is the typical resting breathing volume.
In conclusion, this study demonstrated that the ability to use endovascular catheter markers to deduce tumor displacement during a percutaneous needle procedure is influenced by the distance between the tumor- and the catheter marker, the depth of the needle, the inflation volume of simulated lungs, and whether the marker is positioned in the same sagittal and coronal plane in relation to the tumor. Future research should focus on determining the optimal number and location of endovascular markers, including a bigger variation and spread of tumor locations, and adjusting insertion techniques, to further realize the clinical applicability of endovascular catheter markers in percutaneous needle procedures.
Contactless Heat Measurement System for Retinal Coagulation
Design and Evaluation
Introduction: Current heat measurement systems for retinal coagulation are insufficient to demonstrate the safety of intraocular diathermy instruments. Therefore, this paper aims to design and test a novel coagulation heat measurement system that attempts to infer direct retinal tissue temperature using contactless thermal measurements. Methods: In four experiment conditions, the direct temperature on the lower surface of the tissue is measured from below with a thermography camera measuring the temperature through a semi-transparent window that holds the tissue, and contactless measurements are made with a multi-sensor containing vertically aligned micro sensors located in the fluid medium above the sample. Results: The lowest mean temperature increase at both the thermography measurements (1.52°C) and sensor measurements (0.08°C), is found in the condition of 2.2 J (2.2 W and 1”). At thermography, the highest mean increase (8.67°C) resulted from the condition of 4 J (4 W and 1”) and positive. At the sensor, the highest mean increase (0.25°C) is found in the condition of 4 J (2 W and 2”). Discussion: The use of 2.2 J appears too low for proper sensor measurement. For the two conditions of 4 J there is a contradictory indication of the influence of application time in thermography measurements versus sensor measurements, as the sensor is expected to be more sensitive to changes in the application time than the thermal camera. Conclusion: Since no similar trends have been observed between the thermography and multi-sensor measurements, the contactless sensor cannot infer the direct tissue temperature.
...
Introduction: Current heat measurement systems for retinal coagulation are insufficient to demonstrate the safety of intraocular diathermy instruments. Therefore, this paper aims to design and test a novel coagulation heat measurement system that attempts to infer direct retinal tissue temperature using contactless thermal measurements. Methods: In four experiment conditions, the direct temperature on the lower surface of the tissue is measured from below with a thermography camera measuring the temperature through a semi-transparent window that holds the tissue, and contactless measurements are made with a multi-sensor containing vertically aligned micro sensors located in the fluid medium above the sample. Results: The lowest mean temperature increase at both the thermography measurements (1.52°C) and sensor measurements (0.08°C), is found in the condition of 2.2 J (2.2 W and 1”). At thermography, the highest mean increase (8.67°C) resulted from the condition of 4 J (4 W and 1”) and positive. At the sensor, the highest mean increase (0.25°C) is found in the condition of 4 J (2 W and 2”). Discussion: The use of 2.2 J appears too low for proper sensor measurement. For the two conditions of 4 J there is a contradictory indication of the influence of application time in thermography measurements versus sensor measurements, as the sensor is expected to be more sensitive to changes in the application time than the thermal camera. Conclusion: Since no similar trends have been observed between the thermography and multi-sensor measurements, the contactless sensor cannot infer the direct tissue temperature.
Automotive Diminished Reality
A vulnerable road user study in a pedestrian crossing environment
Objective: In this thesis, we explore whether augmented and diminished reality interfaces, which, respectively, add and remove information from the environment, improve a pedestrian's feeling of road crossing safety, and how this information should be conveyed to the pedestrian.
Background: Literature shows that view occlusion is a prominent cause in pedestrian collisions. The research focus is currently on vehicle technology and pedestrian warning systems. Whether aiding pedestrians with camera views from unobstructed positions helps to overcome the view occlusion problem is unclear.
Methods: Twenty-eight participants engaged in a virtual reality urban road crossing scenario, in which they took on the role of a pedestrian. The pedestrian was situated on the curb and positioned such that the view on the road was largely obstructed. An autonomous vehicle approached and drove past from the left of the pedestrian. Through a head-mounted display, the participants experienced seven prototypes: baseline (i.e., no display), see-through display, transparent car, and both a head-locked and body-locked display with and without view guidance. The order in which participants encountered the prototypes was determined by a balanced Latin square, and each interface was tested by means of six trials with a non-yielding and a yielding scenario randomly selected such that in total three non-yielding and three yielding scenarios occurred in each block. The participants were instructed to continuously indicate whether they felt safe to cross by pressing a button. The interface's acceptance, workload and preference were measured with questionnaires.
Results: The participants' perceived feeling of safety revealed improved performance for all interfaces compared to the baseline condition. For the baseline condition, in which the vulnerable road user did not have access to occlusion-free information, the perceived feeling of safety was the lowest on average and decreased the earliest in the autonomous vehicle approaching phase, as well as scoring the lowest rating on acceptance. The see-through display and the transparent car interfaces, which used a combination of augmented and diminished reality properties to convey the information in a world-anchored manner to the pedestrians, achieved a higher acceptance and perceived feeling of safety than the head-locked and body-locked display interfaces.
Conclusion: A vulnerable road user's perceived feeling of safety can be increased by means of camera views from unobstructed positions to help overcome the view occlusion problem in common road crossing scenarios. This study's findings suggest a positive effect for diminished reality techniques for pedestrians, and future research could examine this technology further in more demanding scenarios. ...
Objective: In this thesis, we explore whether augmented and diminished reality interfaces, which, respectively, add and remove information from the environment, improve a pedestrian's feeling of road crossing safety, and how this information should be conveyed to the pedestrian.
Background: Literature shows that view occlusion is a prominent cause in pedestrian collisions. The research focus is currently on vehicle technology and pedestrian warning systems. Whether aiding pedestrians with camera views from unobstructed positions helps to overcome the view occlusion problem is unclear.
Methods: Twenty-eight participants engaged in a virtual reality urban road crossing scenario, in which they took on the role of a pedestrian. The pedestrian was situated on the curb and positioned such that the view on the road was largely obstructed. An autonomous vehicle approached and drove past from the left of the pedestrian. Through a head-mounted display, the participants experienced seven prototypes: baseline (i.e., no display), see-through display, transparent car, and both a head-locked and body-locked display with and without view guidance. The order in which participants encountered the prototypes was determined by a balanced Latin square, and each interface was tested by means of six trials with a non-yielding and a yielding scenario randomly selected such that in total three non-yielding and three yielding scenarios occurred in each block. The participants were instructed to continuously indicate whether they felt safe to cross by pressing a button. The interface's acceptance, workload and preference were measured with questionnaires.
Results: The participants' perceived feeling of safety revealed improved performance for all interfaces compared to the baseline condition. For the baseline condition, in which the vulnerable road user did not have access to occlusion-free information, the perceived feeling of safety was the lowest on average and decreased the earliest in the autonomous vehicle approaching phase, as well as scoring the lowest rating on acceptance. The see-through display and the transparent car interfaces, which used a combination of augmented and diminished reality properties to convey the information in a world-anchored manner to the pedestrians, achieved a higher acceptance and perceived feeling of safety than the head-locked and body-locked display interfaces.
Conclusion: A vulnerable road user's perceived feeling of safety can be increased by means of camera views from unobstructed positions to help overcome the view occlusion problem in common road crossing scenarios. This study's findings suggest a positive effect for diminished reality techniques for pedestrians, and future research could examine this technology further in more demanding scenarios.
Increased backing softness of planar smooth dry adhesives enhances contact area and frictional load capacity on a cylindrical substrate
With bio-inspired backings: Solid, Sponge & Inflatable
Dry adhesives can reattach to surfaces due to the reversible bond made by Van der Waals forces. These adhesives can therefore be used as gripping surface that has a high frictional load capacity, independent of the grasping force. In many grippers, the adhesive surface is often pressed into contact with another surface (’substrate’) in an open and closing motion. Since, generally, substrates have non-flat shapes, the adhesive has to be pressed into more directions at once to make full contact. An additional part to the adhesive system is needed here to transform the closing motion to a multi-directional preload on the adhesive surface. To realize this, a passive soft material behind the adhesive is added in this study.
Design objectives for such a material (’backing’) were formulated and different types of bio-inspired backing concepts (solid, sponge, and inflatable) were fabricated. To gain insight in the suitability of these backing concepts with regard to some of the objectives, minimal required preload and minimal residual stresses to avoid detaching forces, two things are measured. Firstly, backing softness was measured as the compression stress-strain characteristic of the backing. Secondly, the preload contact stress distribution of backings was qualitatively measured.
The adhesive was a thin planar adhesive material reinforced with a planar mesh. One sponge backing type and one inflatable backing type were selected as practical backings to fabricate an adhesive system with. An experiment to measure frictional performance was done with these systems whereby backing softness was varied. These cuboid adhesive systems were pressed onto a cylindrical substrate and, after removal of the preload, loaded in the direction of the reinforcement while measuring frictional load capacity and contact area.
For both these two adhesive systems types, experiments showed that an increased backing softness caused an even or greater contact area throughout the whole loading cycle. The linear correlation coefficient, between rest phase contact area and maximum load capacity was 0.96, and at the end of the load phase, between the ’slide’ contact area and ’slide’ load capacity was 0.99.
With an inflatable or sponge backing design it is possible to make a softer backing compared to a solid design made by the same material. Only the sponge backing type distributed the preload relatively even at low and high compression, owing it to its stress plateau in its compression stress-strain characteristic. Although the inflatable has an equal pressure internally and also shows such a plateau, it was found that its contact stress is not even, due to the effect of its outer hull.
Concluding, the addition of a soft backing to help make and keep contact with a general shaped substrate, and thereby increasing load capacity, promises a new design paradigm in synthetic dry adhesives. Furthermore, the results indicates functional relevance of the presence of a relatively large and soft volume between the bones and the adhesive surface of the fingers/toe pads of geckos, tree frogs and humans. ...
Design objectives for such a material (’backing’) were formulated and different types of bio-inspired backing concepts (solid, sponge, and inflatable) were fabricated. To gain insight in the suitability of these backing concepts with regard to some of the objectives, minimal required preload and minimal residual stresses to avoid detaching forces, two things are measured. Firstly, backing softness was measured as the compression stress-strain characteristic of the backing. Secondly, the preload contact stress distribution of backings was qualitatively measured.
The adhesive was a thin planar adhesive material reinforced with a planar mesh. One sponge backing type and one inflatable backing type were selected as practical backings to fabricate an adhesive system with. An experiment to measure frictional performance was done with these systems whereby backing softness was varied. These cuboid adhesive systems were pressed onto a cylindrical substrate and, after removal of the preload, loaded in the direction of the reinforcement while measuring frictional load capacity and contact area.
For both these two adhesive systems types, experiments showed that an increased backing softness caused an even or greater contact area throughout the whole loading cycle. The linear correlation coefficient, between rest phase contact area and maximum load capacity was 0.96, and at the end of the load phase, between the ’slide’ contact area and ’slide’ load capacity was 0.99.
With an inflatable or sponge backing design it is possible to make a softer backing compared to a solid design made by the same material. Only the sponge backing type distributed the preload relatively even at low and high compression, owing it to its stress plateau in its compression stress-strain characteristic. Although the inflatable has an equal pressure internally and also shows such a plateau, it was found that its contact stress is not even, due to the effect of its outer hull.
Concluding, the addition of a soft backing to help make and keep contact with a general shaped substrate, and thereby increasing load capacity, promises a new design paradigm in synthetic dry adhesives. Furthermore, the results indicates functional relevance of the presence of a relatively large and soft volume between the bones and the adhesive surface of the fingers/toe pads of geckos, tree frogs and humans. ...
Dry adhesives can reattach to surfaces due to the reversible bond made by Van der Waals forces. These adhesives can therefore be used as gripping surface that has a high frictional load capacity, independent of the grasping force. In many grippers, the adhesive surface is often pressed into contact with another surface (’substrate’) in an open and closing motion. Since, generally, substrates have non-flat shapes, the adhesive has to be pressed into more directions at once to make full contact. An additional part to the adhesive system is needed here to transform the closing motion to a multi-directional preload on the adhesive surface. To realize this, a passive soft material behind the adhesive is added in this study.
Design objectives for such a material (’backing’) were formulated and different types of bio-inspired backing concepts (solid, sponge, and inflatable) were fabricated. To gain insight in the suitability of these backing concepts with regard to some of the objectives, minimal required preload and minimal residual stresses to avoid detaching forces, two things are measured. Firstly, backing softness was measured as the compression stress-strain characteristic of the backing. Secondly, the preload contact stress distribution of backings was qualitatively measured.
The adhesive was a thin planar adhesive material reinforced with a planar mesh. One sponge backing type and one inflatable backing type were selected as practical backings to fabricate an adhesive system with. An experiment to measure frictional performance was done with these systems whereby backing softness was varied. These cuboid adhesive systems were pressed onto a cylindrical substrate and, after removal of the preload, loaded in the direction of the reinforcement while measuring frictional load capacity and contact area.
For both these two adhesive systems types, experiments showed that an increased backing softness caused an even or greater contact area throughout the whole loading cycle. The linear correlation coefficient, between rest phase contact area and maximum load capacity was 0.96, and at the end of the load phase, between the ’slide’ contact area and ’slide’ load capacity was 0.99.
With an inflatable or sponge backing design it is possible to make a softer backing compared to a solid design made by the same material. Only the sponge backing type distributed the preload relatively even at low and high compression, owing it to its stress plateau in its compression stress-strain characteristic. Although the inflatable has an equal pressure internally and also shows such a plateau, it was found that its contact stress is not even, due to the effect of its outer hull.
Concluding, the addition of a soft backing to help make and keep contact with a general shaped substrate, and thereby increasing load capacity, promises a new design paradigm in synthetic dry adhesives. Furthermore, the results indicates functional relevance of the presence of a relatively large and soft volume between the bones and the adhesive surface of the fingers/toe pads of geckos, tree frogs and humans.
Design objectives for such a material (’backing’) were formulated and different types of bio-inspired backing concepts (solid, sponge, and inflatable) were fabricated. To gain insight in the suitability of these backing concepts with regard to some of the objectives, minimal required preload and minimal residual stresses to avoid detaching forces, two things are measured. Firstly, backing softness was measured as the compression stress-strain characteristic of the backing. Secondly, the preload contact stress distribution of backings was qualitatively measured.
The adhesive was a thin planar adhesive material reinforced with a planar mesh. One sponge backing type and one inflatable backing type were selected as practical backings to fabricate an adhesive system with. An experiment to measure frictional performance was done with these systems whereby backing softness was varied. These cuboid adhesive systems were pressed onto a cylindrical substrate and, after removal of the preload, loaded in the direction of the reinforcement while measuring frictional load capacity and contact area.
For both these two adhesive systems types, experiments showed that an increased backing softness caused an even or greater contact area throughout the whole loading cycle. The linear correlation coefficient, between rest phase contact area and maximum load capacity was 0.96, and at the end of the load phase, between the ’slide’ contact area and ’slide’ load capacity was 0.99.
With an inflatable or sponge backing design it is possible to make a softer backing compared to a solid design made by the same material. Only the sponge backing type distributed the preload relatively even at low and high compression, owing it to its stress plateau in its compression stress-strain characteristic. Although the inflatable has an equal pressure internally and also shows such a plateau, it was found that its contact stress is not even, due to the effect of its outer hull.
Concluding, the addition of a soft backing to help make and keep contact with a general shaped substrate, and thereby increasing load capacity, promises a new design paradigm in synthetic dry adhesives. Furthermore, the results indicates functional relevance of the presence of a relatively large and soft volume between the bones and the adhesive surface of the fingers/toe pads of geckos, tree frogs and humans.
Retinal detachment occurs when liquid slips behind the retina and does not allow the latter to lay flat on the posterior region of the eye. It alters the vision of the patient, hence requiring surgery to be corrected. In some cases, retinal detachment can occur after the retina has been treated for other pathologies.
Indeed, more than 20% of highly myopic patients who have been treated for retinal diseases are subject to retinal detachment a few months after the surgery and are required to undergo a second surgery. It is believed that a membrane, also called Vitreous Cortex Remnants (VCR), that arises due to vitreoschisis,
a retinal disease, is the reason for the re-detachment. VCR is often not dealt with during surgery because its removal is time-costly, the VCR is not well visible and instruments are not optimally adapted for removing VCR. The work aims to develop and experimentally evaluate new methods of removing VCR. For that purpose, a series of test prototypes were manufactured, and three surgeons assessed the efficiency of the prototypes for removing VCR from dissected pig’s eyes. Each eye was treated pre-experimentally according to a new model that tries to recreate vitreoschisis in a young porcine eye. The efficiency of each test prototype was assessed based on the force that the instrument tip exerted on
the pig’s retina, the number of strokes taken to remove the VCR completely, the tissue damage and the time used. Furthermore, the optimal tip length was determined based on the surgeons’ feedback. The results show that the force greatly depended on the stiffness of the instrument tip and that the most efficient prototype consisted of a PVA wipe cut to size 6x1x1 mm and a 0.1 mm diameter Nitinol wire. The prototype exerted a maximum force of 0.68 gr. The number of strokes was around 40, and the optimal tip length was just under 4.5 mm. While the experiments showed that it is a promising design, the tip needs to be remodeled to comply with the low stiffness needed and to be able to fit within a 23 gauge tube. ...
Indeed, more than 20% of highly myopic patients who have been treated for retinal diseases are subject to retinal detachment a few months after the surgery and are required to undergo a second surgery. It is believed that a membrane, also called Vitreous Cortex Remnants (VCR), that arises due to vitreoschisis,
a retinal disease, is the reason for the re-detachment. VCR is often not dealt with during surgery because its removal is time-costly, the VCR is not well visible and instruments are not optimally adapted for removing VCR. The work aims to develop and experimentally evaluate new methods of removing VCR. For that purpose, a series of test prototypes were manufactured, and three surgeons assessed the efficiency of the prototypes for removing VCR from dissected pig’s eyes. Each eye was treated pre-experimentally according to a new model that tries to recreate vitreoschisis in a young porcine eye. The efficiency of each test prototype was assessed based on the force that the instrument tip exerted on
the pig’s retina, the number of strokes taken to remove the VCR completely, the tissue damage and the time used. Furthermore, the optimal tip length was determined based on the surgeons’ feedback. The results show that the force greatly depended on the stiffness of the instrument tip and that the most efficient prototype consisted of a PVA wipe cut to size 6x1x1 mm and a 0.1 mm diameter Nitinol wire. The prototype exerted a maximum force of 0.68 gr. The number of strokes was around 40, and the optimal tip length was just under 4.5 mm. While the experiments showed that it is a promising design, the tip needs to be remodeled to comply with the low stiffness needed and to be able to fit within a 23 gauge tube. ...
Retinal detachment occurs when liquid slips behind the retina and does not allow the latter to lay flat on the posterior region of the eye. It alters the vision of the patient, hence requiring surgery to be corrected. In some cases, retinal detachment can occur after the retina has been treated for other pathologies.
Indeed, more than 20% of highly myopic patients who have been treated for retinal diseases are subject to retinal detachment a few months after the surgery and are required to undergo a second surgery. It is believed that a membrane, also called Vitreous Cortex Remnants (VCR), that arises due to vitreoschisis,
a retinal disease, is the reason for the re-detachment. VCR is often not dealt with during surgery because its removal is time-costly, the VCR is not well visible and instruments are not optimally adapted for removing VCR. The work aims to develop and experimentally evaluate new methods of removing VCR. For that purpose, a series of test prototypes were manufactured, and three surgeons assessed the efficiency of the prototypes for removing VCR from dissected pig’s eyes. Each eye was treated pre-experimentally according to a new model that tries to recreate vitreoschisis in a young porcine eye. The efficiency of each test prototype was assessed based on the force that the instrument tip exerted on
the pig’s retina, the number of strokes taken to remove the VCR completely, the tissue damage and the time used. Furthermore, the optimal tip length was determined based on the surgeons’ feedback. The results show that the force greatly depended on the stiffness of the instrument tip and that the most efficient prototype consisted of a PVA wipe cut to size 6x1x1 mm and a 0.1 mm diameter Nitinol wire. The prototype exerted a maximum force of 0.68 gr. The number of strokes was around 40, and the optimal tip length was just under 4.5 mm. While the experiments showed that it is a promising design, the tip needs to be remodeled to comply with the low stiffness needed and to be able to fit within a 23 gauge tube.
Indeed, more than 20% of highly myopic patients who have been treated for retinal diseases are subject to retinal detachment a few months after the surgery and are required to undergo a second surgery. It is believed that a membrane, also called Vitreous Cortex Remnants (VCR), that arises due to vitreoschisis,
a retinal disease, is the reason for the re-detachment. VCR is often not dealt with during surgery because its removal is time-costly, the VCR is not well visible and instruments are not optimally adapted for removing VCR. The work aims to develop and experimentally evaluate new methods of removing VCR. For that purpose, a series of test prototypes were manufactured, and three surgeons assessed the efficiency of the prototypes for removing VCR from dissected pig’s eyes. Each eye was treated pre-experimentally according to a new model that tries to recreate vitreoschisis in a young porcine eye. The efficiency of each test prototype was assessed based on the force that the instrument tip exerted on
the pig’s retina, the number of strokes taken to remove the VCR completely, the tissue damage and the time used. Furthermore, the optimal tip length was determined based on the surgeons’ feedback. The results show that the force greatly depended on the stiffness of the instrument tip and that the most efficient prototype consisted of a PVA wipe cut to size 6x1x1 mm and a 0.1 mm diameter Nitinol wire. The prototype exerted a maximum force of 0.68 gr. The number of strokes was around 40, and the optimal tip length was just under 4.5 mm. While the experiments showed that it is a promising design, the tip needs to be remodeled to comply with the low stiffness needed and to be able to fit within a 23 gauge tube.
Fruit and vegetable production is increasing worldwide, and farmers currently face a tough challenge in finding enough agricultural workers. Automation of the labour-intensive task of crop harvesting could help fill in this gap between supply and demand. However, picking soft fruits is challenging, as they can be easily damaged if not carefully handled. This paper focuses on designing and evaluating a novel robotic gripper for gently harvesting blackberries, which is nicknamed the Twisting-Tube gripper. The gripper consists of a fabric tube which closes in an enveloping manner due to a motorized twisting action of the ends of the tube. A custom tensile-testing bench was used to test blackberry detachment, release, and damage rates for three types of tubes: radially elastic, fully elastic, and compressible. These tubes were manufactured out of different combinations of foam padding, spandex and food-safe cotton cheesecloth and compared to a handpicked control. The results showed that compressible, thicker cheesecloth outperformed radially elastic or fully elastic or extremely compressible tubes with 82% successful detachment and 95% successful release rates. Furthermore, the Twisting-Tube gripper with thick cheesecloth discoloured at least one drupelet of 19% of the blackberries after 48 hours, which is less than the 33% measured in the handpicked control group, but still more than the 10% of the unhandled berries with discolouration. Moreover, the gripper with thick cheesecloth caused leakage to at least one drupelet for 29% of the successfully harvested blackberries compared to 13% of the hand-harvested control. It can be concluded that the presented Twisting-Tube gripper prototype shows promising results for harvesting small soft fruits.
...
Fruit and vegetable production is increasing worldwide, and farmers currently face a tough challenge in finding enough agricultural workers. Automation of the labour-intensive task of crop harvesting could help fill in this gap between supply and demand. However, picking soft fruits is challenging, as they can be easily damaged if not carefully handled. This paper focuses on designing and evaluating a novel robotic gripper for gently harvesting blackberries, which is nicknamed the Twisting-Tube gripper. The gripper consists of a fabric tube which closes in an enveloping manner due to a motorized twisting action of the ends of the tube. A custom tensile-testing bench was used to test blackberry detachment, release, and damage rates for three types of tubes: radially elastic, fully elastic, and compressible. These tubes were manufactured out of different combinations of foam padding, spandex and food-safe cotton cheesecloth and compared to a handpicked control. The results showed that compressible, thicker cheesecloth outperformed radially elastic or fully elastic or extremely compressible tubes with 82% successful detachment and 95% successful release rates. Furthermore, the Twisting-Tube gripper with thick cheesecloth discoloured at least one drupelet of 19% of the blackberries after 48 hours, which is less than the 33% measured in the handpicked control group, but still more than the 10% of the unhandled berries with discolouration. Moreover, the gripper with thick cheesecloth caused leakage to at least one drupelet for 29% of the successfully harvested blackberries compared to 13% of the hand-harvested control. It can be concluded that the presented Twisting-Tube gripper prototype shows promising results for harvesting small soft fruits.
Throughout history, different intraocular illumination methods for vitreoretinal surgery have been used and the most common limitations to the state-of-the-art intraocular illumination methods are the glare and reflections created by the illumination device and the relatively small illuminated area. A way to tackle these limitations could be by using a ring-light configuration, which produces diffuse scattered illumination for a full 360° around the object.
In this study, we developed and experimentally evaluated two ring-light configurations for intraocular illumination during vitreoretinal surgery: one for insertion through the pars plana (20 mm), and one for insertion through the cornea and placement in the posterior chamber (11 mm). Both prototypes are made from a 27 gauge Eckardt TwinLight (DORC, the Netherlands), placed inside a capillary tube cut in half through the length. Cuts were made in the fiber every 2 mm, perpendicular to the length of the fiber, to allow light to exit the fiber through the cladding.
By measuring the light intensity and illuminated area, we found that the ring-light configurations produce a lower light intensity but also a slightly larger illuminated area and a more diffuse and uniformly distributed illumination than the Eckardt TwinLight.
The placement of the ring-light in the posterior chamber proved to be unsafe and complex, since the installation procedure in ex-vivo porcine cadaver eyes could not be executed without damaging the lens bag, lens zonules, posterior iris and cornea, due to the lack of space in the posterior chamber, and the rigidity and sharp tip of the ring.
The ring-light configuration that is inserted through the pars plana also caused damage to the retina and lens bag, due to the ring’s rigidity and its sharp tip. However, this configuration shows potential when the ring would be made from a more flexible material and has an incorporated pigtail curve a the distal end, which can be easily achieved in a future version of the prototype. ...
In this study, we developed and experimentally evaluated two ring-light configurations for intraocular illumination during vitreoretinal surgery: one for insertion through the pars plana (20 mm), and one for insertion through the cornea and placement in the posterior chamber (11 mm). Both prototypes are made from a 27 gauge Eckardt TwinLight (DORC, the Netherlands), placed inside a capillary tube cut in half through the length. Cuts were made in the fiber every 2 mm, perpendicular to the length of the fiber, to allow light to exit the fiber through the cladding.
By measuring the light intensity and illuminated area, we found that the ring-light configurations produce a lower light intensity but also a slightly larger illuminated area and a more diffuse and uniformly distributed illumination than the Eckardt TwinLight.
The placement of the ring-light in the posterior chamber proved to be unsafe and complex, since the installation procedure in ex-vivo porcine cadaver eyes could not be executed without damaging the lens bag, lens zonules, posterior iris and cornea, due to the lack of space in the posterior chamber, and the rigidity and sharp tip of the ring.
The ring-light configuration that is inserted through the pars plana also caused damage to the retina and lens bag, due to the ring’s rigidity and its sharp tip. However, this configuration shows potential when the ring would be made from a more flexible material and has an incorporated pigtail curve a the distal end, which can be easily achieved in a future version of the prototype. ...
Throughout history, different intraocular illumination methods for vitreoretinal surgery have been used and the most common limitations to the state-of-the-art intraocular illumination methods are the glare and reflections created by the illumination device and the relatively small illuminated area. A way to tackle these limitations could be by using a ring-light configuration, which produces diffuse scattered illumination for a full 360° around the object.
In this study, we developed and experimentally evaluated two ring-light configurations for intraocular illumination during vitreoretinal surgery: one for insertion through the pars plana (20 mm), and one for insertion through the cornea and placement in the posterior chamber (11 mm). Both prototypes are made from a 27 gauge Eckardt TwinLight (DORC, the Netherlands), placed inside a capillary tube cut in half through the length. Cuts were made in the fiber every 2 mm, perpendicular to the length of the fiber, to allow light to exit the fiber through the cladding.
By measuring the light intensity and illuminated area, we found that the ring-light configurations produce a lower light intensity but also a slightly larger illuminated area and a more diffuse and uniformly distributed illumination than the Eckardt TwinLight.
The placement of the ring-light in the posterior chamber proved to be unsafe and complex, since the installation procedure in ex-vivo porcine cadaver eyes could not be executed without damaging the lens bag, lens zonules, posterior iris and cornea, due to the lack of space in the posterior chamber, and the rigidity and sharp tip of the ring.
The ring-light configuration that is inserted through the pars plana also caused damage to the retina and lens bag, due to the ring’s rigidity and its sharp tip. However, this configuration shows potential when the ring would be made from a more flexible material and has an incorporated pigtail curve a the distal end, which can be easily achieved in a future version of the prototype.
In this study, we developed and experimentally evaluated two ring-light configurations for intraocular illumination during vitreoretinal surgery: one for insertion through the pars plana (20 mm), and one for insertion through the cornea and placement in the posterior chamber (11 mm). Both prototypes are made from a 27 gauge Eckardt TwinLight (DORC, the Netherlands), placed inside a capillary tube cut in half through the length. Cuts were made in the fiber every 2 mm, perpendicular to the length of the fiber, to allow light to exit the fiber through the cladding.
By measuring the light intensity and illuminated area, we found that the ring-light configurations produce a lower light intensity but also a slightly larger illuminated area and a more diffuse and uniformly distributed illumination than the Eckardt TwinLight.
The placement of the ring-light in the posterior chamber proved to be unsafe and complex, since the installation procedure in ex-vivo porcine cadaver eyes could not be executed without damaging the lens bag, lens zonules, posterior iris and cornea, due to the lack of space in the posterior chamber, and the rigidity and sharp tip of the ring.
The ring-light configuration that is inserted through the pars plana also caused damage to the retina and lens bag, due to the ring’s rigidity and its sharp tip. However, this configuration shows potential when the ring would be made from a more flexible material and has an incorporated pigtail curve a the distal end, which can be easily achieved in a future version of the prototype.
Master thesis
(2022)
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L. Thirunavukkarasu Kumaaravelu, J.C.F. de Winter, D. Dodou, V. Onkhar, P. Bazilinskyy, W. Tabone, Y.B. Eisma
Vulnerable road users account for more than 50% of traffic fatalities, and among these, pedestrians are the most susceptible to fatalities due to their distraction and misperception of other road users. To mitigate their plight, systems that warn drivers and pedestrians in case of a possible collision have been developed. Among systems that focus on the pedestrian's perspective, existing concepts are capable of predicting collisions but lack elements that monitor the visual attention of pedestrians. We address this gap by developing a gaze-based pedestrian warning system based on the Tobii Pro Glasses 2, a head-mounted eye-tracker. The system consists of: (1) a custom trained fast neural network (YOLO v4) on the KITTI object detection dataset that processes the video feed of the eye-tracker to detect approaching vehicles and (2) a module that uses the pedestrian's gaze to identify whether their attention falls on the closest moving vehicle that is approaching the pedestrian, both in real-time. If the pedestrian does not look at the approaching vehicle, they are given an auditory alert that warns them of a possible collision. In a pilot study conducted on a busy road in an urban environment, the system was evaluated under different pedestrian walking speeds and gaze behaviours to test the algorithm's robustness. The pilot study revealed that our system alerted the inattentive pedestrian with an accuracy of 67%. The mean vehicle detection accuracy and a mean moving vehicle identification accuracy from the pilot were 93% and 60%, respectively, a promising result given the use of only a mono camera. Despite the use of computer vision techniques, the system worked at an inference speed of 50 FPS due to the multi-processing capabilities of our algorithm. Our efforts are a first step in developing pedestrian warning systems based on eye-tracking technology to improve road safety in the future. The algorithm (Python-based) code used for this work has been made publicly available.
...
Vulnerable road users account for more than 50% of traffic fatalities, and among these, pedestrians are the most susceptible to fatalities due to their distraction and misperception of other road users. To mitigate their plight, systems that warn drivers and pedestrians in case of a possible collision have been developed. Among systems that focus on the pedestrian's perspective, existing concepts are capable of predicting collisions but lack elements that monitor the visual attention of pedestrians. We address this gap by developing a gaze-based pedestrian warning system based on the Tobii Pro Glasses 2, a head-mounted eye-tracker. The system consists of: (1) a custom trained fast neural network (YOLO v4) on the KITTI object detection dataset that processes the video feed of the eye-tracker to detect approaching vehicles and (2) a module that uses the pedestrian's gaze to identify whether their attention falls on the closest moving vehicle that is approaching the pedestrian, both in real-time. If the pedestrian does not look at the approaching vehicle, they are given an auditory alert that warns them of a possible collision. In a pilot study conducted on a busy road in an urban environment, the system was evaluated under different pedestrian walking speeds and gaze behaviours to test the algorithm's robustness. The pilot study revealed that our system alerted the inattentive pedestrian with an accuracy of 67%. The mean vehicle detection accuracy and a mean moving vehicle identification accuracy from the pilot were 93% and 60%, respectively, a promising result given the use of only a mono camera. Despite the use of computer vision techniques, the system worked at an inference speed of 50 FPS due to the multi-processing capabilities of our algorithm. Our efforts are a first step in developing pedestrian warning systems based on eye-tracking technology to improve road safety in the future. The algorithm (Python-based) code used for this work has been made publicly available.
Master thesis
(2022)
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P. Sabu, D. Dodou, J.C.F. de Winter, Ivo Stuldreher, Anne-Marie Brouwer, Daisuke Kaneko
Food-evoked emotions are essential for consumers’ food choice prediction and market success. These food-evoked emotions are predominantly measured by explicit self-reports. Yet in certain situations such as social desirability, explicit measures might not reflect one’s true emotional experience. The additional use of implicit measures can be beneficial.
The present study investigated whether social pressure truly changes food experience by means of explicit and implicit measures of food liking. Explicit ratings were EmojiGrid valence and arousal ratings in response to familiar and unfamiliar food images and soups. Implicit measures consisted of frontal alpha asymmetry during pre-selected scenes of a movie about Japanese soy sauce as well as sip size of the soup. Explicit and implicit measures were compared to assess the effect of social pressure on Japanese and Dutch food liking.
No differences between the social pressure (n = 19) and control group (n = 23) emerged in any of the measures. Explicit ratings and the implicit measure sip size, but not frontal alpha asymmetry during watching the movie, showed differences between participants with high and low food neophobia. The insensitivity of frontal alpha asymmetry to food neophobia groups could be explained by the movie scenes showing rather familiar foods. BMI grouping similarly showed no effect on frontal alpha asymmetry during watching the movie, but also explicit measures were unaffected.
It was concluded that the social pressure intervention itself was not effective in inducing increased liking of Japanese food, since there was no increase in neither reported liking nor ‘true’ liking. Additional ways to induce social pressure, e.g., observation during rating, are advisable if the study was repeated. Furthermore, the use of stronger stimuli to induce approach or avoidance motivation as measured by frontal alpha asymmetry, is recommended. It cannot be concluded whether social pressure truly affects food experience. ...
The present study investigated whether social pressure truly changes food experience by means of explicit and implicit measures of food liking. Explicit ratings were EmojiGrid valence and arousal ratings in response to familiar and unfamiliar food images and soups. Implicit measures consisted of frontal alpha asymmetry during pre-selected scenes of a movie about Japanese soy sauce as well as sip size of the soup. Explicit and implicit measures were compared to assess the effect of social pressure on Japanese and Dutch food liking.
No differences between the social pressure (n = 19) and control group (n = 23) emerged in any of the measures. Explicit ratings and the implicit measure sip size, but not frontal alpha asymmetry during watching the movie, showed differences between participants with high and low food neophobia. The insensitivity of frontal alpha asymmetry to food neophobia groups could be explained by the movie scenes showing rather familiar foods. BMI grouping similarly showed no effect on frontal alpha asymmetry during watching the movie, but also explicit measures were unaffected.
It was concluded that the social pressure intervention itself was not effective in inducing increased liking of Japanese food, since there was no increase in neither reported liking nor ‘true’ liking. Additional ways to induce social pressure, e.g., observation during rating, are advisable if the study was repeated. Furthermore, the use of stronger stimuli to induce approach or avoidance motivation as measured by frontal alpha asymmetry, is recommended. It cannot be concluded whether social pressure truly affects food experience. ...
Food-evoked emotions are essential for consumers’ food choice prediction and market success. These food-evoked emotions are predominantly measured by explicit self-reports. Yet in certain situations such as social desirability, explicit measures might not reflect one’s true emotional experience. The additional use of implicit measures can be beneficial.
The present study investigated whether social pressure truly changes food experience by means of explicit and implicit measures of food liking. Explicit ratings were EmojiGrid valence and arousal ratings in response to familiar and unfamiliar food images and soups. Implicit measures consisted of frontal alpha asymmetry during pre-selected scenes of a movie about Japanese soy sauce as well as sip size of the soup. Explicit and implicit measures were compared to assess the effect of social pressure on Japanese and Dutch food liking.
No differences between the social pressure (n = 19) and control group (n = 23) emerged in any of the measures. Explicit ratings and the implicit measure sip size, but not frontal alpha asymmetry during watching the movie, showed differences between participants with high and low food neophobia. The insensitivity of frontal alpha asymmetry to food neophobia groups could be explained by the movie scenes showing rather familiar foods. BMI grouping similarly showed no effect on frontal alpha asymmetry during watching the movie, but also explicit measures were unaffected.
It was concluded that the social pressure intervention itself was not effective in inducing increased liking of Japanese food, since there was no increase in neither reported liking nor ‘true’ liking. Additional ways to induce social pressure, e.g., observation during rating, are advisable if the study was repeated. Furthermore, the use of stronger stimuli to induce approach or avoidance motivation as measured by frontal alpha asymmetry, is recommended. It cannot be concluded whether social pressure truly affects food experience.
The present study investigated whether social pressure truly changes food experience by means of explicit and implicit measures of food liking. Explicit ratings were EmojiGrid valence and arousal ratings in response to familiar and unfamiliar food images and soups. Implicit measures consisted of frontal alpha asymmetry during pre-selected scenes of a movie about Japanese soy sauce as well as sip size of the soup. Explicit and implicit measures were compared to assess the effect of social pressure on Japanese and Dutch food liking.
No differences between the social pressure (n = 19) and control group (n = 23) emerged in any of the measures. Explicit ratings and the implicit measure sip size, but not frontal alpha asymmetry during watching the movie, showed differences between participants with high and low food neophobia. The insensitivity of frontal alpha asymmetry to food neophobia groups could be explained by the movie scenes showing rather familiar foods. BMI grouping similarly showed no effect on frontal alpha asymmetry during watching the movie, but also explicit measures were unaffected.
It was concluded that the social pressure intervention itself was not effective in inducing increased liking of Japanese food, since there was no increase in neither reported liking nor ‘true’ liking. Additional ways to induce social pressure, e.g., observation during rating, are advisable if the study was repeated. Furthermore, the use of stronger stimuli to induce approach or avoidance motivation as measured by frontal alpha asymmetry, is recommended. It cannot be concluded whether social pressure truly affects food experience.
Preventing Anastomotic Leakage
An experimental approach to the redesign of a colorectal stent
The large intestines, or colon, is the last part of the digestive tract before the rectum. Colorectal cancer is one of the main reasons that patients need a colon resection. A colon resection is a surgery in which the malignant part of the colon is removed. After removal of the tumor, the two ends of the colon need to be reattached, also called anastomosed. This is usually done using sutures or staples. One of the most frequently occurring and major complications is that the anastomosis does not heal correctly. This can cause an anastomotic leakage, which means that fecal matter and fluids with bacteria can flow into the otherwise sterile abdominal cavity. This is a serious complication that can even result in death. Therefore, a solution can be to insert a stent to cover the anastomosis from the inside, preventing feces and fluids from entering the abdominal cavity. Such a stent was developed at the department of Surgery of the Erasmus MC.
This thesis focuses on the redesign of this stent to cover an anastomosis. Two main problems with the stent were stent migration due to insufficient friction between the stent and the colonic wall, and intestinal blockage due to the presence of the stent.
Preliminary research and a literature study showed that the addition of barbs to the stent could increase friction with the colonic wall. Optimal barb dimensions were researched on fresh colon specimens in an experimental setup. Ideal barb parameters were a height of 1.5 mm, diameter of 1.0 mm, an angle of 30 degrees, with a distribution of 3 barbs per cm2. In addition, the ideal stent diameter was explored in an experiment with fresh colon specimens. The stent should expand the colon with 50-60%. To safely insert and extract a stent with barbs in the colon, a patent search was executed to explore the possibilities of barb and colon protection. A stent with a reducible diameter and a tubular protection structure were identified as the most promising methods to safely insert a barbed stent. The second problem of intestinal blockage was analyzed and causes of intestinal blockage were identified. Minimizing the frontal contact surface at the proximal end of the stent was assumed to be the most important factor to reduce intestinal blockage. A minimal frontal contact surface also reduces the force that feces exerts on the stent, thus reducing the chance of stent migration.
The previously mentioned experiments and analysis formed the basis of a list of design requirements for a new prototype stent. The requirements were divided into five categories; fixation, dimensions, materials, delivery method and performance. After analyzing different manufacturing processes and available materials, two concepts were designed and produced. One concept was chosen after careful considerations of both options.
The final prototype consisted of a stent with barbs that was 3D printed. This design was validated on the set of requirements that were set up earlier. The material of the stent is both flexible and stiff. For insertion and extraction of the stent, the diameter can be reduced by longitudinal inward folding, while the stent forms a rigid tube while in a deployed state. The barbs are stiff and strong and can withstand the force that would move the stent. The frontal contact surface of the stent was reduced by more than 18 times compared to the old prototype, to reduce the influence on intestinal blockage. The stent is surrounded by a sheet to protect the barbs and prevent tissue damage during insertion. A validation experiment showed that the stent was improved in fixation compared to the old prototype. Therefore, based on the research executed in this thesis, the final prototype should theoretically migrate less and cause less blockage. However, an ex-vivo experiment should validate the fixation force of the new prototype, and in-vivo experiments on pigs should determine if the prototype actually does not migrate and actually does not cause intestinal blockage. ...
This thesis focuses on the redesign of this stent to cover an anastomosis. Two main problems with the stent were stent migration due to insufficient friction between the stent and the colonic wall, and intestinal blockage due to the presence of the stent.
Preliminary research and a literature study showed that the addition of barbs to the stent could increase friction with the colonic wall. Optimal barb dimensions were researched on fresh colon specimens in an experimental setup. Ideal barb parameters were a height of 1.5 mm, diameter of 1.0 mm, an angle of 30 degrees, with a distribution of 3 barbs per cm2. In addition, the ideal stent diameter was explored in an experiment with fresh colon specimens. The stent should expand the colon with 50-60%. To safely insert and extract a stent with barbs in the colon, a patent search was executed to explore the possibilities of barb and colon protection. A stent with a reducible diameter and a tubular protection structure were identified as the most promising methods to safely insert a barbed stent. The second problem of intestinal blockage was analyzed and causes of intestinal blockage were identified. Minimizing the frontal contact surface at the proximal end of the stent was assumed to be the most important factor to reduce intestinal blockage. A minimal frontal contact surface also reduces the force that feces exerts on the stent, thus reducing the chance of stent migration.
The previously mentioned experiments and analysis formed the basis of a list of design requirements for a new prototype stent. The requirements were divided into five categories; fixation, dimensions, materials, delivery method and performance. After analyzing different manufacturing processes and available materials, two concepts were designed and produced. One concept was chosen after careful considerations of both options.
The final prototype consisted of a stent with barbs that was 3D printed. This design was validated on the set of requirements that were set up earlier. The material of the stent is both flexible and stiff. For insertion and extraction of the stent, the diameter can be reduced by longitudinal inward folding, while the stent forms a rigid tube while in a deployed state. The barbs are stiff and strong and can withstand the force that would move the stent. The frontal contact surface of the stent was reduced by more than 18 times compared to the old prototype, to reduce the influence on intestinal blockage. The stent is surrounded by a sheet to protect the barbs and prevent tissue damage during insertion. A validation experiment showed that the stent was improved in fixation compared to the old prototype. Therefore, based on the research executed in this thesis, the final prototype should theoretically migrate less and cause less blockage. However, an ex-vivo experiment should validate the fixation force of the new prototype, and in-vivo experiments on pigs should determine if the prototype actually does not migrate and actually does not cause intestinal blockage. ...
The large intestines, or colon, is the last part of the digestive tract before the rectum. Colorectal cancer is one of the main reasons that patients need a colon resection. A colon resection is a surgery in which the malignant part of the colon is removed. After removal of the tumor, the two ends of the colon need to be reattached, also called anastomosed. This is usually done using sutures or staples. One of the most frequently occurring and major complications is that the anastomosis does not heal correctly. This can cause an anastomotic leakage, which means that fecal matter and fluids with bacteria can flow into the otherwise sterile abdominal cavity. This is a serious complication that can even result in death. Therefore, a solution can be to insert a stent to cover the anastomosis from the inside, preventing feces and fluids from entering the abdominal cavity. Such a stent was developed at the department of Surgery of the Erasmus MC.
This thesis focuses on the redesign of this stent to cover an anastomosis. Two main problems with the stent were stent migration due to insufficient friction between the stent and the colonic wall, and intestinal blockage due to the presence of the stent.
Preliminary research and a literature study showed that the addition of barbs to the stent could increase friction with the colonic wall. Optimal barb dimensions were researched on fresh colon specimens in an experimental setup. Ideal barb parameters were a height of 1.5 mm, diameter of 1.0 mm, an angle of 30 degrees, with a distribution of 3 barbs per cm2. In addition, the ideal stent diameter was explored in an experiment with fresh colon specimens. The stent should expand the colon with 50-60%. To safely insert and extract a stent with barbs in the colon, a patent search was executed to explore the possibilities of barb and colon protection. A stent with a reducible diameter and a tubular protection structure were identified as the most promising methods to safely insert a barbed stent. The second problem of intestinal blockage was analyzed and causes of intestinal blockage were identified. Minimizing the frontal contact surface at the proximal end of the stent was assumed to be the most important factor to reduce intestinal blockage. A minimal frontal contact surface also reduces the force that feces exerts on the stent, thus reducing the chance of stent migration.
The previously mentioned experiments and analysis formed the basis of a list of design requirements for a new prototype stent. The requirements were divided into five categories; fixation, dimensions, materials, delivery method and performance. After analyzing different manufacturing processes and available materials, two concepts were designed and produced. One concept was chosen after careful considerations of both options.
The final prototype consisted of a stent with barbs that was 3D printed. This design was validated on the set of requirements that were set up earlier. The material of the stent is both flexible and stiff. For insertion and extraction of the stent, the diameter can be reduced by longitudinal inward folding, while the stent forms a rigid tube while in a deployed state. The barbs are stiff and strong and can withstand the force that would move the stent. The frontal contact surface of the stent was reduced by more than 18 times compared to the old prototype, to reduce the influence on intestinal blockage. The stent is surrounded by a sheet to protect the barbs and prevent tissue damage during insertion. A validation experiment showed that the stent was improved in fixation compared to the old prototype. Therefore, based on the research executed in this thesis, the final prototype should theoretically migrate less and cause less blockage. However, an ex-vivo experiment should validate the fixation force of the new prototype, and in-vivo experiments on pigs should determine if the prototype actually does not migrate and actually does not cause intestinal blockage.
This thesis focuses on the redesign of this stent to cover an anastomosis. Two main problems with the stent were stent migration due to insufficient friction between the stent and the colonic wall, and intestinal blockage due to the presence of the stent.
Preliminary research and a literature study showed that the addition of barbs to the stent could increase friction with the colonic wall. Optimal barb dimensions were researched on fresh colon specimens in an experimental setup. Ideal barb parameters were a height of 1.5 mm, diameter of 1.0 mm, an angle of 30 degrees, with a distribution of 3 barbs per cm2. In addition, the ideal stent diameter was explored in an experiment with fresh colon specimens. The stent should expand the colon with 50-60%. To safely insert and extract a stent with barbs in the colon, a patent search was executed to explore the possibilities of barb and colon protection. A stent with a reducible diameter and a tubular protection structure were identified as the most promising methods to safely insert a barbed stent. The second problem of intestinal blockage was analyzed and causes of intestinal blockage were identified. Minimizing the frontal contact surface at the proximal end of the stent was assumed to be the most important factor to reduce intestinal blockage. A minimal frontal contact surface also reduces the force that feces exerts on the stent, thus reducing the chance of stent migration.
The previously mentioned experiments and analysis formed the basis of a list of design requirements for a new prototype stent. The requirements were divided into five categories; fixation, dimensions, materials, delivery method and performance. After analyzing different manufacturing processes and available materials, two concepts were designed and produced. One concept was chosen after careful considerations of both options.
The final prototype consisted of a stent with barbs that was 3D printed. This design was validated on the set of requirements that were set up earlier. The material of the stent is both flexible and stiff. For insertion and extraction of the stent, the diameter can be reduced by longitudinal inward folding, while the stent forms a rigid tube while in a deployed state. The barbs are stiff and strong and can withstand the force that would move the stent. The frontal contact surface of the stent was reduced by more than 18 times compared to the old prototype, to reduce the influence on intestinal blockage. The stent is surrounded by a sheet to protect the barbs and prevent tissue damage during insertion. A validation experiment showed that the stent was improved in fixation compared to the old prototype. Therefore, based on the research executed in this thesis, the final prototype should theoretically migrate less and cause less blockage. However, an ex-vivo experiment should validate the fixation force of the new prototype, and in-vivo experiments on pigs should determine if the prototype actually does not migrate and actually does not cause intestinal blockage.
Stability in Truck Driving Behaviour
A Geo-Specific Analysis
Master thesis
(2022)
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I. Surana, D. Dodou, J.C.F. de Winter, P. Bazilinskyy, T. Driessen, J. Pauwelussen , R. Happee
Naturalistic driving research with a focus on trucks has been gaining momentum in the past decade. With the advancement in sensor technology and access to big data, it becomes possible to understand driver behaviour at a more fundamental level. This can assist in mitigating the impact trucks have on the environment while enhancing safety. Several studies have worked towards examining the predictability of driving behaviour through driver profiling (i.e. scoring a driver's behaviour or classifying drivers by assigning them different categories such as aggressive/non-aggressive). However, little research still focuses on the importance and impact of individual features used to develop these models. In the current study, an analysis of driving data from 1,727 trucks recorded over one year as part of a Dutch Field Operational Test (FOT) has been performed. This FOT, to date, has not been investigated in the published academic literature. Recent studies have analysed historical location data to assess risk associated with specific routes and environments. This is being used to provide notifications to drivers around work zones to mitigate the impact of accidents.
The current thesis extends the geo-specific analysis of (truck) driving data by analysing stability in truck driving behaviour with a focus on time and location (urban areas and motorways). Here correlation analysis has been used to explore stability. Correlational analysis elucidates that metrics such as the number of headway warnings, braking events and lane departure warnings are stable over space and time. A discussion reflects on the role of vehicle characteristics (i.e. mass and engine power) towards stability.
It is concluded that in the case of spatial stability: Mean point speed has higher stability on motorways than in urban areas. It has been determined that trucks with higher mass and lower engine power tend to have lower mean speed than the norm. Contrary to mean point speed, headway warnings show higher stability in urban areas than on motorways. Braking events and lane departure warnings exhibit high stability. Secondly, a strong correlation between (t and t+1) hours over the entire day is observed for temporal stability.
This research is a precursor to building generalised models for profiling drivers and assessing various driving patterns. An in-depth understanding of different driving patterns can help driver coaching companies better understand metrics when time and location are factored in before providing targeted feedback. Apart from this can also facilitate fleet management. The code for analysing this dataset is accessible online and may stimulate future researchers to explore this dataset further. ...
The current thesis extends the geo-specific analysis of (truck) driving data by analysing stability in truck driving behaviour with a focus on time and location (urban areas and motorways). Here correlation analysis has been used to explore stability. Correlational analysis elucidates that metrics such as the number of headway warnings, braking events and lane departure warnings are stable over space and time. A discussion reflects on the role of vehicle characteristics (i.e. mass and engine power) towards stability.
It is concluded that in the case of spatial stability: Mean point speed has higher stability on motorways than in urban areas. It has been determined that trucks with higher mass and lower engine power tend to have lower mean speed than the norm. Contrary to mean point speed, headway warnings show higher stability in urban areas than on motorways. Braking events and lane departure warnings exhibit high stability. Secondly, a strong correlation between (t and t+1) hours over the entire day is observed for temporal stability.
This research is a precursor to building generalised models for profiling drivers and assessing various driving patterns. An in-depth understanding of different driving patterns can help driver coaching companies better understand metrics when time and location are factored in before providing targeted feedback. Apart from this can also facilitate fleet management. The code for analysing this dataset is accessible online and may stimulate future researchers to explore this dataset further. ...
Naturalistic driving research with a focus on trucks has been gaining momentum in the past decade. With the advancement in sensor technology and access to big data, it becomes possible to understand driver behaviour at a more fundamental level. This can assist in mitigating the impact trucks have on the environment while enhancing safety. Several studies have worked towards examining the predictability of driving behaviour through driver profiling (i.e. scoring a driver's behaviour or classifying drivers by assigning them different categories such as aggressive/non-aggressive). However, little research still focuses on the importance and impact of individual features used to develop these models. In the current study, an analysis of driving data from 1,727 trucks recorded over one year as part of a Dutch Field Operational Test (FOT) has been performed. This FOT, to date, has not been investigated in the published academic literature. Recent studies have analysed historical location data to assess risk associated with specific routes and environments. This is being used to provide notifications to drivers around work zones to mitigate the impact of accidents.
The current thesis extends the geo-specific analysis of (truck) driving data by analysing stability in truck driving behaviour with a focus on time and location (urban areas and motorways). Here correlation analysis has been used to explore stability. Correlational analysis elucidates that metrics such as the number of headway warnings, braking events and lane departure warnings are stable over space and time. A discussion reflects on the role of vehicle characteristics (i.e. mass and engine power) towards stability.
It is concluded that in the case of spatial stability: Mean point speed has higher stability on motorways than in urban areas. It has been determined that trucks with higher mass and lower engine power tend to have lower mean speed than the norm. Contrary to mean point speed, headway warnings show higher stability in urban areas than on motorways. Braking events and lane departure warnings exhibit high stability. Secondly, a strong correlation between (t and t+1) hours over the entire day is observed for temporal stability.
This research is a precursor to building generalised models for profiling drivers and assessing various driving patterns. An in-depth understanding of different driving patterns can help driver coaching companies better understand metrics when time and location are factored in before providing targeted feedback. Apart from this can also facilitate fleet management. The code for analysing this dataset is accessible online and may stimulate future researchers to explore this dataset further.
The current thesis extends the geo-specific analysis of (truck) driving data by analysing stability in truck driving behaviour with a focus on time and location (urban areas and motorways). Here correlation analysis has been used to explore stability. Correlational analysis elucidates that metrics such as the number of headway warnings, braking events and lane departure warnings are stable over space and time. A discussion reflects on the role of vehicle characteristics (i.e. mass and engine power) towards stability.
It is concluded that in the case of spatial stability: Mean point speed has higher stability on motorways than in urban areas. It has been determined that trucks with higher mass and lower engine power tend to have lower mean speed than the norm. Contrary to mean point speed, headway warnings show higher stability in urban areas than on motorways. Braking events and lane departure warnings exhibit high stability. Secondly, a strong correlation between (t and t+1) hours over the entire day is observed for temporal stability.
This research is a precursor to building generalised models for profiling drivers and assessing various driving patterns. An in-depth understanding of different driving patterns can help driver coaching companies better understand metrics when time and location are factored in before providing targeted feedback. Apart from this can also facilitate fleet management. The code for analysing this dataset is accessible online and may stimulate future researchers to explore this dataset further.
Generation of grip on soft tissue in the surgical field is most commonly done with forceps that generate friction grip, that is, the translation of normal (pinch) forces into shear forces. Errors made with these surgical grippers are often force-related: applying too low pinch forces results in slipping of the tissue out of the gripper, and too high pinch forces may lead to tissue damage. One possible solution for generating tissue grip that is secure yet gentle is the adhesive grip. In this case, contact between tissue and gripper is maintained by attracting gripper-tissue interactions, and gripping strength does not depend on the applied pinch forces. Inspiration for the design of such a gripper can be derived from the tree frog, an animal that uses adhesive grip to grip on a range of substrates in its habitat. The main aim of this thesis is to translate grip-generating principles used by tree frogs into designs of artificial adhesives that can generate firm yet gentle grip on soft substrates. The designs of the artificial adhesives in this thesis are inspired by two important characteristics of the tree frog’s attachment apparatus: the hierarchical surface pattern on the tree-frog toe-pad and reinforcing fibrillar structures located inside the pad. Specifically, the aim of this thesis is to mimic function rather than form, and focuses on mechanisms underlying the tree-frog attachment apparatus to satisfy two main requirements for strong grip: (1) contact formation and (2) preservation of the formed contact.
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Generation of grip on soft tissue in the surgical field is most commonly done with forceps that generate friction grip, that is, the translation of normal (pinch) forces into shear forces. Errors made with these surgical grippers are often force-related: applying too low pinch forces results in slipping of the tissue out of the gripper, and too high pinch forces may lead to tissue damage. One possible solution for generating tissue grip that is secure yet gentle is the adhesive grip. In this case, contact between tissue and gripper is maintained by attracting gripper-tissue interactions, and gripping strength does not depend on the applied pinch forces. Inspiration for the design of such a gripper can be derived from the tree frog, an animal that uses adhesive grip to grip on a range of substrates in its habitat. The main aim of this thesis is to translate grip-generating principles used by tree frogs into designs of artificial adhesives that can generate firm yet gentle grip on soft substrates. The designs of the artificial adhesives in this thesis are inspired by two important characteristics of the tree frog’s attachment apparatus: the hierarchical surface pattern on the tree-frog toe-pad and reinforcing fibrillar structures located inside the pad. Specifically, the aim of this thesis is to mimic function rather than form, and focuses on mechanisms underlying the tree-frog attachment apparatus to satisfy two main requirements for strong grip: (1) contact formation and (2) preservation of the formed contact.