Energy Optimization of Powered Ankle-Foot Prosthesis Based on Three-Chamber Hydraulic Cylinder

The powered ankle-foot prosthesis (AFP) provides active power during the gait of lower limb amputees, but its endurance is limited by the energy's weight and volume. A hydraulic-driven ATP system based on a three-chamber hydraulic cylinder is proposed. The system uses a three-chamber hydraulic cylinder, with the non-rod cavity connected to the accumulator and the rod cavity and plunger cavity connected to the pump. The accumulator absorbs energy during the control dorsiflexion process and provides energy during the power plantarflexion process, which can reduce the system's energy consumption. Optimizing the motion process of the AFP during the swing phase further reduces energy consumption. The three-chamber hydraulic cylinder was designed based on the working principle, and a theoretical calculation and simulation model were constructed to verify feasibility. The simulation results show that the hydraulic-driven AFP based on the three-chamber hydraulic cylinder can effectively reduce energy consumption and improve endurance. When the accumulator precharge pressure is 1.7 MPa, the energy consumption is reduced by 19.6%.