A Powered Self-Contained Knee and Ankle Prosthesis for Near Normal Gait in Transfemoral Amputees

Abstract

The human leg serves as the primary mechanism to provide locomotion and general mobility, both of which require significant power generation at the joints. Today, commercial lower limb prostheses are generally passive devices capable of only dissipating or storing energy. Amputees must adapt their gait and mobility patterns to compensate for this lack of power. The hypothesis of this work postulates that restoring power to the knee and ankle joints can positively affect gait and increase the ease of mobility in above knee amputees. Described herein is the development of an electrically powered knee and ankle prosthesis intended to restore normal locomotive function to above knee amputees. Initial work focused on a tethered prototype with off-board power and computation to investigate electrical power requirements of such a device. Findings indicated that a device could be fabricated with an acceptable operating weight and range, though limited. Based on this work, a self-contained electrically powered knee and ankle prosthesis was developed. The design specifications, mechanical and electrical designs, control architecture for the self-contained version are described. Experimental results testing the device on an above knee amputee demonstrate the devices merit in restoring biomechanically normal gait patterns, assistive sit to stand transitions and powered slope ascent.