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P.M. Baines

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5 records found

Experimental estimation of energy absorption during heel strike in human barefoot walking

Journal article - P.M. Baines, A.L. Schwab, A.J. van Soest, A.J. van Soest

Metabolic energy expenditure during human gait is poorly understood. Mechanical energy loss during heel strike contributes to this energy expenditure. Previous work has estimated the energy absorption during heel strike as 0.8 J using an effective foot mass model. The aim of our study is to investigate the possibility of determining the energy absorption by more directly estimating the work done by the ground reaction force, the force-integral method. Concurrently another aim is to compare this method of direct determination of work to the method of an effective foot mass model. Participants of our experimental study were asked to walk barefoot at preferred speed. Ground reaction force and lower leg kinematics were collected at high sampling frequency (3000 Hz; 1295 Hz), with tight synchronization. The work done by the ground reaction force is 3.8 J, estimated by integrating this force over the foot-ankle deformation. The effective mass model is improved by dropping the assumption that foot-ankle deformation is maximal at the instant of the impact force peak. On theoretical grounds it is clear that in the presence of substantial damping that peak force and peak deformation do not occur simultaneously. The energy absorption results, due the vertical force only, corresponding to the force-integral method is similar to the results of the improved application of the effective mass model (2.7 J; 2.5 J). However the total work done by the ground reaction force calculated by the force-integral method is significantly higher than that of the vertical component alone. We conclude that direct estimation of the work done by the ground reaction force is possible and preferable over the use of the effective foot mass model. Assuming that energy absorbed is lost, the mechanical energy loss of heel strike is around 3.8 J for preferred walking speeds (≈ 1.3 m/s), which contributes to about 15–20% of the overall metabolic cost of transport.@en

Reaction moments matter when designing lower-extremity robots for tripping recovery

Journal article - S. Jabeen, P.M. Baines, J. Harlaar, J. Harlaar, H. Vallery, H. Vallery, Andrew Berry, Andrew Berry

Balance recovery after tripping often requires an active adaptation of foot placement. Thus far, few attempts have been made to actively assist forward foot placement for balance recovery employing wearable devices. This study aims to explore the possibilities of active forward foot placement through two paradigms of actuation: assistive moments exerted with the reaction moments either internal or external to the human body, namely 'joint' moments and 'free' moments, respectively. Both paradigms can be applied to manipulate the motion of segments of the body (e.g., the shank or thigh), but joint actuators also exert opposing reaction moments on neighbouring body segments, altering posture and potentially inhibiting tripping recovery. We therefore hypothesised that a free moment paradigm is more effective in assisting balance recovery following tripping. The simulation software SCONE was used to simulate gait and tripping over various ground-fixed obstacles during the early swing phase. To aid forward foot placement, joint moments and free moments were applied either on the thigh to augment hip flexion or on the shank to augment knee extension. Two realizations of joint moments on the hip were simulated, with the reaction moment applied to either the pelvis or the contralateral thigh. The simulation results show that assisting hip flexion with either actuation paradigm on the thigh can result in full recovery of gait with a margin of stability and leg kinematics closely matching the unperturbed case. However, when assisting knee extension with moments on the shank, free moment effectively assist balance but joint moments with the reaction moment on the thigh do not. For joint moments assisting hip flexion, placement of the reaction moment on the contralateral thigh was more effective in achieving the desired limb dynamics than placing the reaction on the pelvis. Poor choice of placement of reaction moments may therefore have detrimental consequences for balance recovery, and removing them entirely (i.e., free moment) could be a more effective and reliable alternative. These results challenge conventional assumptions and may inform the design and development of a new generation of minimalistic wearable devices to promote balance during gait.@en

Neglected physical human-robot interaction may explain variable outcomes in gait neurorehabilitation research

Journal article - M.C. Plooij, M.C. Plooij, M.C. Plooij, S. Apte, S. Apte, U. Keller, U. Keller, P.M. Baines, B.T. Sterke, B.T. Sterke, L. Asboth, L. Asboth, G. Courtine, G. Courtine, J. von Zitzewitz, H. Vallery, H. Vallery

During gait neurorehabilitation, many factors influence the quality of gait patterns, particularly the chosen body-weight support (BWS) device. Consequently, robotic BWS devices play a key role in gait rehabilitation of people with neurological disorders. The device transparency, ...

Neglected physical human-robot interaction may explain variable outcomes in gait neurorehabilitation research

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Validation of a single wearable sensor to monitor performance during clinical measures of gait and balance

Master thesis - M.D. Hidalgo Araya, H. Vallery, Arun Jayaraman, Megan O'Brien, M. Kok, P.M. Baines

Deterioration of gait and balance, whether from aging, disease, or injury, has been linked to reduced mobility and increased risk of falling. Wearable sensing technologies, such as inertial measurement units (IMUs), may augment clinical assessments by providing continuous gait and balance data at an increased resolution. The objective of this work was to validate spatiotemporal gait features with a single IMU sensor and to examine changes in sensor-derived features with age during the common clinical tests of gait and balance. We tested the use of an IMU place in the lower back (L5) on age-ranged, healthy individuals (N=34, 20-70 years) during the 10-meter walk test (10MWT), Timed Up and Go (TUG), and Berg Balance Scale (BBS). A total of 49 features were derived from the sensors based on a novel selection of algorithms from previous works. Six spatiotemporal gait features were validated against gold standard measures to assess accuracy and bias. There was an excellent agreement for step time, stance time, swing time, and step count (ICCs 0.90–0.99), and good agreement for gait velocity and step length (ICCs 0.84–0.88). There were 33 linear correlations between age and the sensor-derived features, including a negative correlation between age and vertical displacement of the center of mass during gait. The strongest correlation with age was found for the first slope of the second turn in the TUG (r=-0.545, p≤0.001). For the features that showed moderate correlations (|r|>30, p<0.05), a hierarchical multivariate regression model showed that age was the most important predictor independent of weight, height, and gender. Furthermore, when looking at gender-specific differences after correcting for the contribution of weight and height, women exhibited 5-fold more correlations compared to men. In conclusion, sensor-derived features demonstrated greater sensitivity to individual differences in gait and balance, which may be of a particular interest for future implementation in a clinical setting in impaired populations. The structure of this thesis is as follows: The first chapter contains the project overview, future vision, and specific aims. The second chapter contains a manuscript that will be submitted for peer-reviewed journal publication. Finally, the third chapter is an appendix with more detailed explanations of the methods and findings of this work.