Crossing Obstacles during Walking through Self-adaptive Volitional Control of a Powered Knee Prosthesis

Powered knee prosthesis can enhance mobility by allowing voluntary control of knee flexion, thereby improving foot clearance for crossing obstacle. However, prior controllers have typically focused on crossing obstacle with the prosthesis serving as the trailing leg, while the scenario where the prosthesis leads has been overlooked. This paper introduces a self-adaptive volitional control method utilizing mechanical signals, enabling amputee to cross an obstacle with the prosthesis either as the leading or trailing leg, and even negotiate multiple continuous obstacles. In volitional controller, we partition the swing flexion phase into four conditions and calculate the desired maximum knee angle in real-time accordingly. We recruited amputees to participate in experiments, which included three distinct tasks: single obstacle crossing with the prosthesis leading, single obstacle crossing with the prosthesis trailing, and dual obstacles crossing. This work offers amputees capability to cross obstacle freely and naturally, a functionality that is currently unavailable.