Switched robust tracking/impedance control for an active transfemoral prosthesis

A novel control method for an active transfemoral prosthesis is developed based on the combination of two previously published controllers, robust tracking/impedance control and switched impedance control. This controller is simulated and optimized to provide desired gait features and energy regeneration. Specifically, an evolutionary optimization algorithm termed biogeography-based optimization is used. Across all optimization trials a tracking error on the order of 10-2 rad rms or less results for both the knee and ankle joints. This is accompanied by ground reaction forces approximating able-bodied gait data and an energy regeneration capacity of about 9.6 J per stride.