Date of Award

1-31-1993

Document Type

Thesis

Degree Name

Master of Science in Electrical Engineering - (M.S.)

Department

Electrical and Computer Engineering

First Advisor

Peter Engler

Second Advisor

Stanley S. Reisman

Third Advisor

H. Michael Lacker

Abstract

In designing an artificial leg for an amputee, it is important to find those underlying principles which determine the normal human gait. For this purpose we have developed a model of human walking, in which it is possible to predict an optimal gait at any given speed of walking based on the principle of minimum mechanical energy consumption.

Our model is an extension of the model proposed by Mochon and McMahon (1980). Their model assumes that during the swing phase of walking mechanical energy is conserved. Non-conservative forces due to muscle activity are assumed to occur during the double support phase when both legs are in contact with the ground. We have applied these idealizations and have extended their model to calculate the energy required to maintain any periodic walking motion consistent with their model. A new constraint arises when the heel of the swing leg strikes the ground making the end of the swing phase. This constraint that after heel strike the heel of the swing leg remains on the ground produces a loss of energy to the system that must be resupplied by muscle activity to maintain a periodic motion. This allows us to uniquely determine an optimal gait for any given speed of walking which minimizes the mechanical energy loss per unit length of motion.

We propose that this energy minimizing walking motion is selected during normal periodic walking and therefore is an underlying principle determining the normal human gait. This hypothesis is tested by comparing our predicted gait with that actually observed experimentally.

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