Control Methods for Powered Prostheses to Improve Mobility and Stability in Persons with Lower Limb Amputation

Abstract

This dissertation presents the motivation, development, and evaluation of controllers for powered lower limb prostheses. This document contains five chapters, three of which discuss individual contributions. Chapter I describes the motivation, background, and scope of the work. Chapter II presents an activity level controller for running with a powered knee and ankle prosthesis, a supervisory controller to switch between running and walking for use in emergency situations, and evaluation of the set of controllers with an amputee subject. Chapter III introduces a suite of controllers for a powered ankle prosthesis for walking at multiple speeds on level ground and supportive ground adaptive standing for use on a large range of inclines, with a supervisory controller to provide natural transitions between the two, all evaluated with an amputee subject. Chapter IV describes research regarding ambulation on even and uneven terrain, with a healthy subject study revealing chiefly a relationship between shank angle and ankle moment during the middle stance phase of walking which exists on both even and uneven terrain; this motivated a walking controller for a powered ankle prosthesis which adapts to terrain with variable local slope, evaluated on an amputee subject. Finally, Chapter V offers some concluding remarks, including suggestions for future work.