Preliminary Evaluation of Myoelectric Control of an Active Transfemoral Prosthesis During Stair Ascent

This paper presents the development and preliminary validation of a control interface for a transfemoral prosthesis that enables EMG-based control of a powered knee during stair ascent. The approach uses results from non-amputee gait studies of stair ascent in the design of a control architecture that enables EMG modulation of knee torque in a manner biomechanically similar to that exhibited by non-amputee subjects. The myoelectric torque controller is formulated with a finite-state linear impedance model in stance and swing. The stance phase is modulated by surface EMG signals co-activated by antagonist residuum muscles. Preliminary results with a sound-limb subject using a knee immobilizer indicate that the EMG-based control architecture has the potential to enable the amputee to directly generate torque commands appropriate for stair ascent using an actively powered artificial limb.