Functional assessment of control systems for cybernetic elbow prostheses--Part II: Application of the technique

This paper (Part II of II) presents application of the technique described in Part I to functional assessment of two myoelectric elbow-prosthesis controllers: the controller implemented in the Boston Elbow, a state-of-the-art elbow prosthesis, and a proposed control scheme that, to a crude degree, mimics control of the intact elbow. Assessment of the controllers was achieved by evaluating an amputee subject's functional capability as he performed a constrained motion task with a prosthesis that implemented each control scheme. Evaluation of the amputee's capability was accomplished off line using sampled values of his myoelectric activity, his limb kinematics, and the interface forces at the constraint. Superior performance was observed with the proposed scheme. Namely, the subject exhibited better synergy among his elbow and shoulder muscles. Furthermore, when using the proposed controller, he exhibited some natural patterns of muscle coordination.