A Computer Simulation of Human Gait

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Abstract

The overall goal of this project was to develop a computer simulation of normal human walking that would use as driving moments the resultant joint moments calculated in a 3-D gait analysis. Accordingly, three component projects were undertaken. The first study tested the feasibility of using data generated by an inverse dynamics analysis to drive a computer simulation. Artificial displacement data were created using a direct dynamics analysis of three different three-segment models: constant moments were applied and predicted kinematics were generated. Displacement data for specific points on the model were then run through an inverse dynamics analysis, both with and without random noise added. The calculated joint moments were used to drive a second simulation. It was found that even a small amount of error in the displacement data resulted in an extremely poor prediction of the kinematics by the second simulation. The conclusion drawn was that system controllers are necessary to run successful simulations of this type.

The second study was the development of a foot model suitable for use in a gait simulation. For this, ankle joint forces and moments were used to run simulations of one foot in isolation. The foot was divided into two parts with nine visco-elastic elements aligned along the midline. Torsional dampers controlled the rotation about each axis. The displacement patterns and the ground reaction forces predicted by the simulation closely matched the measured data for a complete stance phase.

The third study encompassed the development of a nine-segment, 3-D gait simulation. The hip, knee and ankle joints were modelled as three, one and two dcgrce-of-freedom joints, respectively. The foot model described above was incorporated with only minor modifications. The 'controllers' used were all torsional, linear springs and/or dampers at various joints. Irunk controllers altered the hip joint moments to keep the trunk vertical. Range-of-motion controllers prevented non-physiological motion at the knees and ankles. Other dampers were required to control the motion, particularly during the double support phase. The simulated human successfully completed one step (550 ms).

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Cited By (2)

Year	Entry
2002	Camacho DLA, Ledoux WR, Rohr ES, Sangeorzan BJ, Ching RP. A three-dimensional, anatomically detailed foot model: a foundation for a finite element simulation and means of quantifying foot-bone position. J Rehab Res Dev. 2002;39(3):401-410.
1999	Ledoux WR II. A Biomechanical Model of the Human Foot With Emphasis on the Plantar Soft Tissue [PhD thesis]. Philadelphia, PA: University of Pennsylvania; 1999.