Feedback in myoelectric prostheses.

This article briefly reviews the history of the use of feedback in artificial limbs. It suggests that researchers have concentrated unduly upon the use of feedback to control prehensile force or joint angle and advocates a broader perspective. In that context, the article presents a comprehensive view of the need for feedback in myoelectric prostheses. The difficulties of designing transducers to meet the stringent demands of prosthetics applications are considered, and problems inherent in several alternatives are identified. Various means of conveying feedback information to the amputee are reviewed in some detail. The concept of feedback in control systems is introduced in the context of closed-loop control of a prosthesis. The surprisingly good performance of skilled users of myoelectric prostheses is noteworthy implying that the distinction between sensory and proprioceptive feedback may be somewhat artificial. By integrating these two feedback types a satisfactory feedback system may become an attainable goal.