A Novel Design of Electro-Hydraulic Driven Active Powered Ankle-Foot Prosthesis

This paper presents the design and control architecture of a full active powered ankle prosthesis driven by electro-hydrostatic actuator (EHA) to improve amputee gait during the level-ground walking in full-time gait cycle. A 100 W brushless DC motor driving a 0.92 cc/rev bi-directional gear pump serves as the power kernel. An elastic element is configured in series connection with the hydraulic cylinder as energy store unit. With this architecture, better power characteristic, ability of energy storage and passive compliance were obtained to revive sound human characteristic as much as possible. To smooth the gait pattern, a neuromuscular model with Hill-type muscle tendon structure is introduced into the control system scheduled by finite state machine which was designed to carry on different control strategy during individual gait phase. The overall simulation was established utilizing MATLAB/Simulink platform to validate its feasibility.