Design and evaluation of voluntary opening and voluntary closing prosthetic terminal device

Abstract

Abstract-Body-powered prostheses use a cable-operated system to generate forces and move prosthetic joints. However, this control system can only generate forces in one direction, so current body-powered prehensor designs allow the user either to voluntarily open or voluntarily close the tongs. Both voluntary opening (VO) and voluntary closing (VC) modes of operation have advantages for certain tasks, and many endusers desire a terminal device (TD) that can switch between the two modes. However, such a TD must maintain the same thumb position (i.e., point of Bowden cable attachment) and movement direction in both modes in order to avoid the need to readjust the harness after every mode switch. In this study, we demonstrate a simple design that fulfills these requirements while allowing the user to switch easily between modes. We describe the design concept, describe a rugged split-hook prototype, provide specifications (size, weight, efficiency, etc.), and present a pilot study in which five subjects with intact arms and two subjects with amputation used the VO and VC splithook prehensor to perform the Southampton Hand Assessment Procedure. Subjects performed an average of 4 to 7 (+/-0.2) points better when they could choose to switch between modes on a task-by-task basis than when they were constrained to using only VO or VC modes.

Case-study of a user-driven prosthetic arm design: bionic hand versus customized body-powered technology in a highly demanding work environment

“…For work with occupational heat exposure, biological or chemical hazards, large weights or widely ranging ambient temperatures, there is no other technology. Development of body-powered technology currently is only conducted by a small number of individuals and groups (e.g., Randall Alley [ 147 , 148 ], Bob Radocy [ 40 , 149 ], Bradley Veatch [ 74 , 150 , 151 ], Dick Plettenburg’s group [ 152 – 156 ], Aaron Dollar’s group [ 157 ] and John Sensinger’s group [ 158 ]).…”

“…We also found that optimal usage entailed a relatively frequent switch of terminal devices, most notably between the VC and VO control type. For PDW under such conditions, the next frontier is thus in perfecting the design of body-powered heavy duty devices that contain a switchable VO/VC control [ 151 , 158 ].…”

The SoftHand Pro-H: A Hybrid Body-Controlled, Electrically Powered Hand Prosthesis for Daily Living and Working

“…This system allows for the translation of the Bowden cable movement into a motor command with a considerable effort reduction compared to commercial BP devices (see Table 3). An upgrade to this system, implemented following the Cybathlon, was the introduction of a switch B between two different modalities with a working principle similar to the one presented in [23]. It is possible to switch between a voluntary opening (VO) and a voluntary closing (VC) mode by pushing the lever.…”

Design and 3d-printing of a body-powered prosthetic limb for amputee

“…Many prosthetic devices, while not readily available to all, are highly developed with technological features. The need for low cost and easily made artificial limbs is strong in developing nations, which is one of the reasons for these solutions [6]. This refers to amputated children who develop quickly and need to upgrade their prosthesis devices quickly as the years.…”

“…The low knowledge level and narrow experience of the resident medical personnel have not provided the required enabling assistance. Violence, diabetes, polio and the diffuse presence of landmines are considered to be the most common causes of limb damage which eventually lead to amputations in developing countries [6].…”