Design and Control of a Compliant Electro-Hydrostatic-Powered Ankle Prosthesis

In this article, a new compliant powered ankle prosthesis driven by electro-hydraulic technology is proposed. Compared with ankle prostheses driven by electromechanical or hydraulic driving systems, the proposed prosthesis solves the contradiction between the output power and the prosthetic mass, thus provides sufficient output performance with a lower installed power. Specifically, we novelly combine the hydraulic pump and accumulators to realize the precise control of energy storage and release. Moreover, high-speed on - off valves controlled by pulsewidth modulation is used to adjust the hydraulic damping in real time, which provides a concept for the active compliance control of the prosthesis. The effectiveness of proposed prosthesis is tested via a series of experiments, which shows that the efficiency reaches 62%.