THE NTNU REVOLUTE WRIST DEVICE (NRWD): A KINEMATICALLY OPITMIZED EXTERNALLY POWERED WRIST PROSTHESIS

Abstract

Transradial amputation implies the loss of the wrist. It therefore also implies the loss of the ability to do flexion/extension and radioulnar deviation as well as the forearm’s ability to rotate the wrist (prosupination). Prosupination is offered by some prostheses, but many users choose not to use a powered wrist because the benefits are literally outweighed by its weight, poor cosmesis and the complexity of controlling multiple degrees of freedom. This is also why a wrist with more than one motorized function is considered by many not to be a viable concept. This paper reports a study that aims at producing a lightweight, single-degree-of-freedom, externally powered wrist whose kinematic properties are optimized to match the movements of a healthy wrist in conjunction with certain Activities of Daily Living (ADL). The rationale for this is the assumption that reducing the need for compensatory movements whilst keeping the weight and control complexity unchanged will improve user acceptance and utilization of the device. The prosthesis provides for digital communication and coordinated motion.