Development of a high backdrivable partially powered Swing assistive actuator knee design: a multiobjective optimization framework

This manuscript presents a multiobjective optimization framework for high backdrivable partially powered swing assistive actuator knee design. The research exploits a Serial Elastic Actuator (SEA), in parallel with a motor valves controlled hydraulic cylinder, with the purpose of expanding the prosthesis capabilities into the power quadrants of the power plane, without sacrificing the benefits relative to existing microprocessor-controlled-knee prostheses (MPKs), able to allow a strictly-passive ballistic swing-phase. The mechatronic design parameters are optimized by exploiting the multi-objective evolutionary genetic algorithm and validated by means of a knee prosthesis multibody model. The backdrive torque found with the described model corresponds to a relatively low value of 2.56 Nm at the knee joint, allowing the pursued high backdrivability of the system.