Research Papers

Forward Dynamic Optimization of Human Gait Simulations: A Global Parameterization Approach

[+] Author and Article Information
Mohammad Sharif Shourijeh

University of Waterloo,
Waterloo, Ontario N2L3G1, Canada
e-mail: msharifs@uwaterloo.ca

John McPhee

University of Waterloo,
Waterloo, Ontario N2L3G1, Canada
e-mail: mcphee@real.uwaterloo.ca

1Corresponding author.

Contributed by the Design Engineering Division of ASME for publication in the Journal of Computational and Nonlinear Dynamics. Manuscript received June 12, 2013; final manuscript received December 11, 2013; published online March 6, 2014. Assoc. Editor: Arend L. Schwab.

J. Comput. Nonlinear Dynam 9(3), 031018 (Mar 06, 2014) (11 pages) Paper No: CND-13-1136; doi: 10.1115/1.4026266 History: Received June 12, 2013; Revised December 11, 2013

This study presents a 2D gait model that uses global parameterization within an optimal control approach and a hyper-volumetric foot contact model. The model is simulated for an entire gait stride, i.e., two full steps. Fourier series are utilized to represent muscle forces to provide a periodic gait with bilateral symmetry. The objectives of this study were to develop a predictive gait simulation and to validate the predictions. The comparison of simulation results of optimal muscle activations, joint angles, and ground reaction forces against experimental data showed a reasonable agreement.

Copyright © 2014 by ASME
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Fig. 1

Two dimensional gait model with nine segments, eleven dofs, and eight muscle groups per leg: 1, ilipsoas; 2, rectus femoris; 3, glutei; 4, hamstrings; 5,vasti; 6, gastrocnemius; 7, tibialis anterior; and 8, soleus

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Fig. 2

The foot contact configuration with three volumetric contact sphere elements at the points H*, P*, and T*, which are the relaxed locations of the heel (H), metatarsal-phalangeal joint (P), and toe tip (T)

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Fig. 3

Schematic of the FF design work flow in the DO framework

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Fig. 4

Schematic of the IFT design in DO framework

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Fig. 5

Schematic of the IFM design in DO framework

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Fig. 6

Schematic of the inverse muscle model: lt is the tendon length, lm is the muscle length, and αp is the muscle pennation angle, which is assumed to be constant

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Fig. 7

(left) Comparison of the simulated muscle activations (solid line) against the muscle EMGs (μ ± σ) from Ref. [1], except for the iliopsoas group where the simulated normalized force is compared against that of Ref. [40] (circles). (right) Simulated muscle activations (solid line) plotted against the muscle excitations (dashed line). The vertical axis bounds for the left side is the same as the right side.

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Fig. 8

Simulated joint angles (hip extension, knee flexion, and ankle plantarflexion) against the experimental data (shaded area, μ ± σ)

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Fig. 9

(a)–(c) Simulated and experimental ground reaction forces divided by body mass (μ ± σ) and center of pressure location. Comparison of optimal torso kinematics (solid line) against the reference (dashed line), (d) torsoX, (e) torsoY, and (f) torso orientation.




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