Investigating the effect of viscoelastic ankle foot prosthesis on below-knee amputee gait cycle: Modeling and simulation

The purpose of this paper is to investigate the effect of viscoelastic ankle foot prosthesis on below-knee amputee gait cycle by using dynamic simulation of human walking. A two dimensional, seven segment model is developed to simulate normal and amputee entire gait cycle equipped with foot-ground contact model in order to simulate entire gait cycle in an integrated way. In the first step, optimization procedure was coupled with forward dynamic to simulate normal gait cycle. Next step was started by replacing ideal torque generator of ankle joint with passive elements that represents passive prosthetic ankle-foot, in order to simulate below-knee amputee gait cycle. The optimal coefficients of joints that were obtained from dynamic simulation of normal gait cycle were then used for amputee model’s intact joints. Three type of optimal passive ankle foot prosthesis were designed using forward dynamic optimization and the simulation results were employed to compare the performance of different prostheses. The results indicated that using viscoelastic ankle foot prosthesis decreases speed-normalized total work, cost function, dynamic effort and increases speed of the amputee model. Hence using viscoelastic ankle foot prosthesis can improve below-knee amputee walking pattern