Prosthetics and Orthotics International, zyxwvutsrq 1993, zyxwvut j - zyxwvutsrqp A clinical experience with a hierarchically controlled myoelectric hand prosthesis with vibro-tactile feedback zyx P. J. KYBERD*, N. MUSTAPHAt, F. CARNEGIE**, P. H. CHAPPELLtt *Oxford Orthopaedic Engineering Centre, NOC, Headington, Oxford, UK. fGarston Manor Medical Rehabilitation Centre, London, UK. **Arm Training Unit, Queen Mary’s Hospital, London, UK. t f Department zyxwvut of Electrical Engineering, University of Southampton, UK. Abstract Improved performance of externally powered myoelectric hands is possible when the direct control of the digit flexion and grip force are given over to an electronic controller which frees the operator to concentrate on other demands. Design: A commercial myoelectric hand was modified to take the new touch and slip sensors and novel control method. Subject: zyxwvuts An adult male with a traumatic mid- forearm amputation. Outcome measure: The range and ease of use of the prosthetics system. Result: The hand was easily and usefully operated in the home and work environment. Conclusion: Hierarchical control of a hand is possible using sensory feedback to a sophisticated electronic controller. Such a control method reduces the demands on the user’s concentration and enhances the hand’s range. Introduction The survival rate of an individual following amputation, prior to the development of successful anaesthesia, was poor. History records a few hardy individuals who survived (Pliny; Herodotus; Childress, 1985). The replacement limbs were often simple. The more sophisticated hands were often based on the techniques developed by armourers in building All correspondence to be addressed to P. J. Kyberd, Oxford Orthopaedic Engineering Centre, NOC, Headington, Oxford, UK. articulated gloves. Once the survival rate improved, the opportunities for commerical exploitation also grew and companies formed, the oldest in the UK being over a hundred years old. All practical prostheses were body powered and this continued to be the major form of actuation until the Seventies when electric sources became practical: such devices are fitted to a small proportion of the population. In the research arena, other forms of power sources have been used as far back as 1916 (Childress, 1985), for example carbon dioxide gas under pressure. However, none of these have achieved clinical significance, though small numbers of people continue to use gas powered arms. This is due to a variety of reasons, from the limited capabilities of the power supply, to the availability of power sources (Millstein et zyxw at., 1986; Simpson, 1972). The increase in the levels of complexity and the integration of electronic circuits and some improvements in the technology of electrical storage, have encouraged experimental designs of hand and controller that provide better performances or longer periods between re- charging than current designs (Gow and Douglas, 1990; Chappell and Kyberd, 1991). Control of prosthetic hands In the clinical setting there are still only two widely used means of control of prostheses. The first is in body powered terminal devices which usually are in the form of a split hook where control is by body movement. The second form zy 56 Prosthet Orthot Int Downloaded from informahealthcare.com by 177.155.212.60 on 05/20/14 For personal use only.