Mechanical damping with electrical regeneration for a powered transfemoral prosthesis

This paper presents the analytical model of a DC-motor actuated active-knee transfemoral prosthesis operating within the mechanically dissipative but electrically regenerative region of the knee actuator´s performance space. A switching-based control scheme is developed that enables damping control within the limb´s regenerative region of operation. This control approach allows the limb to realize bounded mechanical dissipation using a strictly passive means, while at the same time generating electrical power to augment the limb´s power requirements in active modes of operation. Experimental characterizations of the performance and regenerative efficiency of the switching-based controller indicate that the passive switching controller can provide damping modulation, but at the expense of decreased efficiencies of regeneration as compared to the theoretical projections of the actuator model.