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Optimisation of bipedal walking motion with unbalanced masses. / Pooya Mahmoodi

Swansea University Author: Pooya, Mahmoodi

Abstract

Commercial prosthetic feet weigh about 25% of their equivalent physiological counterparts. The human body has a tendency to overcome the walking asymmetry resulting from the mass imbalance by exerting more energy. A two link passive walking kinematic model, with realistic masses for prosthetic, phys...

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Published: 2014
Institution: Swansea University
Degree level: Doctoral
Degree name: Ph.D
URI: https://cronfa.swan.ac.uk/Record/cronfa42489
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spelling 2018-08-02T16:24:29.4314045 v2 42489 2018-08-02 Optimisation of bipedal walking motion with unbalanced masses. e44c5ce3956d6738dbfcdc0cb3bd40a0 NULL Pooya Mahmoodi Pooya Mahmoodi true true 2018-08-02 Commercial prosthetic feet weigh about 25% of their equivalent physiological counterparts. The human body has a tendency to overcome the walking asymmetry resulting from the mass imbalance by exerting more energy. A two link passive walking kinematic model, with realistic masses for prosthetic, physiological legs and upper body, has been proposed to study the gait pattern with unbalanced leg masses. The 'heel to toe' rolling contact has significant influence on the dynamics of biped models. This contact is modelled using the roll-over shape defined in the local co-ordinate system aligned with the stance leg. The effect of rollover shape curvature and arc length has been studied on various gait descriptors such as average velocity, step period, inter leg angle (and hence step length), mechanical energy. The bifurcation diagrams have been plotted for point feet and different gain values. The insight gained by studying the bifurcation diagrams for different gain and length values is not only useful in understanding the stability of the biped walking process but also in the design of prosthetic feet. It is proposed that the stiffness and energy release mechanisms of prosthetic feet be designed to satisfy amputee's natural gait characteristics that are defined by an effective roll-over shape and corresponding ground reaction force combinations. Each point on the roll-over shape is mapped with a ground reaction force corresponding to its time step. The resulting discrete set of ground reaction force components are applied to the prosthetic foot sole and its stiffness profile is optimised to produce a desired deflection as given by the corresponding point on the roll-over shape. It is shown that the proposed methodology is able to provide valuable insights in the guidelines for selection of materials for a multi-material prosthetic foot. E-Thesis Biomechanics. 31 12 2014 2014-12-31 COLLEGE NANME Engineering COLLEGE CODE Swansea University Doctoral Ph.D 2018-08-02T16:24:29.4314045 2018-08-02T16:24:29.4314045 College of Engineering Engineering Pooya Mahmoodi NULL 1 0042489-02082018162458.pdf 10801719.pdf 2018-08-02T16:24:58.5270000 Output 18676125 application/pdf E-Thesis true 2018-08-02T16:24:58.5270000 false
title Optimisation of bipedal walking motion with unbalanced masses.
spellingShingle Optimisation of bipedal walking motion with unbalanced masses.
Pooya, Mahmoodi
title_short Optimisation of bipedal walking motion with unbalanced masses.
title_full Optimisation of bipedal walking motion with unbalanced masses.
title_fullStr Optimisation of bipedal walking motion with unbalanced masses.
title_full_unstemmed Optimisation of bipedal walking motion with unbalanced masses.
title_sort Optimisation of bipedal walking motion with unbalanced masses.
author_id_str_mv e44c5ce3956d6738dbfcdc0cb3bd40a0
author_id_fullname_str_mv e44c5ce3956d6738dbfcdc0cb3bd40a0_***_Pooya, Mahmoodi
author Pooya, Mahmoodi
author2 Pooya Mahmoodi
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publishDate 2014
institution Swansea University
college_str College of Engineering
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hierarchy_top_title College of Engineering
hierarchy_parent_id collegeofengineering
hierarchy_parent_title College of Engineering
department_str Engineering{{{_:::_}}}College of Engineering{{{_:::_}}}Engineering
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description Commercial prosthetic feet weigh about 25% of their equivalent physiological counterparts. The human body has a tendency to overcome the walking asymmetry resulting from the mass imbalance by exerting more energy. A two link passive walking kinematic model, with realistic masses for prosthetic, physiological legs and upper body, has been proposed to study the gait pattern with unbalanced leg masses. The 'heel to toe' rolling contact has significant influence on the dynamics of biped models. This contact is modelled using the roll-over shape defined in the local co-ordinate system aligned with the stance leg. The effect of rollover shape curvature and arc length has been studied on various gait descriptors such as average velocity, step period, inter leg angle (and hence step length), mechanical energy. The bifurcation diagrams have been plotted for point feet and different gain values. The insight gained by studying the bifurcation diagrams for different gain and length values is not only useful in understanding the stability of the biped walking process but also in the design of prosthetic feet. It is proposed that the stiffness and energy release mechanisms of prosthetic feet be designed to satisfy amputee's natural gait characteristics that are defined by an effective roll-over shape and corresponding ground reaction force combinations. Each point on the roll-over shape is mapped with a ground reaction force corresponding to its time step. The resulting discrete set of ground reaction force components are applied to the prosthetic foot sole and its stiffness profile is optimised to produce a desired deflection as given by the corresponding point on the roll-over shape. It is shown that the proposed methodology is able to provide valuable insights in the guidelines for selection of materials for a multi-material prosthetic foot.
published_date 2014-12-31T04:11:22Z
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score 10.810879