Proportionally controlled linear power assist device for artificial arms.

A new prosthetic add-on device is being developed which promises to provide an economical means of adding power assist to a patient's existing conventional cable-operated prosthesis. Only minor modifications by a prosthetist would be required. Patients wearing conventional cable-operated above-elbow prostheses, who lack adequate function because they cannot generate the necessary cable excursion, are expected to dramatically improve their performance with little or no retraining. The proposed system will operate at speeds comparable to those of a conventional cable-operated prosthesis. The system will retain considerable function even if there is no power assist, and it will imporve the quality of the sensory feedback normally associated with a conventional cable-operated body powered prosthesis.