Understanding how harnessing affects a user's workspace

Abstract

Despite the fundamental importance of reachable workspace in upper-limb prosthetics, to date there have been no studies on this aspect. We have developed a methodology to quantify the reduction in the reachable volume of body-powered prosthesis users due to harness setup, and to record the range-of-motion of the prehensor at a series of locations within the workspace. For this proof-of-concept study ten anatomically intact participants were assessed using a prosthesis simulator. Data was collected using a 3D motion capture system and an electronic goniometer. The harness/cable reduced the reachable workspace by 15-62% with participants struggling to reach across the body and above the head. Across all arm postures assessed, participants were only able to achieve full prehensor range-of-motion in 9%. The methodologies could be useful in guiding the setup of body powered prostheses and in the evaluation of future designs of both body-powered and myoelectric prostheses.