An Integrated, Back-Drivable Electro-Hydrostatic Actuator for a Knee Prosthesis

This paper focuses on the analysis, development and experimental evaluation of an electro-hydrostatic actuator for knee prosthetic devices. In contrast to traditional actuation, the goal is to obtain a highly-integrated and back-drivable actuator with both active and regenerative capabilities. A design procedure is established with the purpose of yielding a fully-customized compact actuation unit. Specifications are defined initially from a biomechanical perspective. Further constraints are imposed by the limitations of the actuation system components. Then, the methodology is applied to develop a custom prototype. From a control standpoint, admittance control is implemented to show actuation functionality and to make a preliminary evaluation of the ability to suit the application. Experimental results demonstrate the validation of the proposed technology and its high potential in active prostheses applications.