Design and evaluation of a prosthetic shoulder controller.

The first goal of this study was to develop a 2 degree of freedom (DOF) upper limb controller utilizing shoulder elevation/depression and protraction/retraction. Its primary purpose is to control powered prosthetic shoulder joints being incorporated into a new generation of prosthetic arms for shoulder disarticulation and very high transhumeral amputees. More generally, however, such a controller can be applied to simultaneously control any 2 DOF's under a direct, proportional control scheme. There is no generally accepted method to objectively and quantitatively evaluate prosthesis and prosthesis control performance, and the second goal of this study was to develop one based on Fitts Law. The evaluation protocol has quite general applicability as well, and can be used to compare different reaching/ pointing devices, or to compare variations in the design or operation of a particular device.