Estimation of Passive Stiffness and Viscosity in Paraplegic: A Dynamic Leg Model in Visual Nastran

This paper presents investigations into pendulum test to measure passive knee motion from a paraplegic subject. The test is used to evaluate changes in the knee angular displacement, passive stiffness and viscosity. Then, genetic algorithm (GA) parameter optimization is used with Visual Nastran (Vn4D) to find passive stiffness and viscosity values for modelling the paraplegic leg. The best performance of the Vn4D leg model is achieved with the optimum values of the viscosity and the stiffness equal to 0.0031055 Nms/deg and 0.024244 Nm/deg respectively. The model was found to be the best Vn4D model with actual subject's leg properties to represent paraplegic leg model.