THE DESIGN OF A MYOELECTRICALLY CONTROLLED HAND WITH MULTIPLE ACTUATORS FOR FIVE-YEAR OLD CHILDREN Thomas Redman 1 , Tara Sims 2 , Paul Chappell 1 , Maggie Donovan-Hall 2 , Andy Cranny 1 , Cheryl Metcalf 2 and Neil White 1 1 School of Electronics and Computer Science, University of Southampton, SO17 1BJ, UK 2 Faculty of Health Sciences, University of Southampton, SO17 1BJ, UK ABSTRACT Myoelectric prosthetics are complex functional devices that can improve significantly a person’s quality of life. This paper describes the development of a myoelectrically controlled prosthetic hand for a five-year old child. A key consideration in the design of upper-body prostheses is to use information from studies highlighting the main causes of rejection. These studies emphasize that in order to reduce rejection, it is necessary to include the opinions of the users in the design process. Additional constraints are introduced due to the small size and mass of a five-year old child’s hand compared to that of an adult. The main points of the final design are detailed, including the areas where these constraints were overcome. Modularity was used throughout the design; it allows the hand to be configured for the individual user, and also helps to reduce the potential cost of the hand. The final design has three actuators controlled individually through the use of a master-slave microchip combination. This design has a final mass of 105.8g and produces a pinching force of 4.35 N. INTRODUCTION There have been greater advances in the design of prosthetic hands for adults compared to those for children. Although there have been developments to child prostheses, they have not always been in line with those made to adult prostheses. Acceptance of the user is a key consideration in the design of upper-body prosthetics. It is generally recognised that the younger a user is introduced to a myoelectrically controlled prosthesis, the greater their acceptance of the technology [1]; this is encouraging the fitment of functional and adaptable prosthetic limbs to young children. To provide choice, hands designed specifically for the needs of children are required. Currently there are two commercially available upper-limb prostheses specifically designed for children: the Otto Bock 2000 Electric Hand, and the RSL Steeper Scamp Myo Electric Hand. Both of these hands are single degrees of freedom devices that are available in various sizes, and driven by a single actuator that closes the first and second fingers onto the thumb. Improvements in child prosthetics could be made with improved adaptability and an increased number of individually driven axes. To address this, the development of prostheses for children that are produced in conjunction with research into the acceptance and needs of children is needed. This paper describes how a prostheses for young children was designed with multiple degrees of freedom, modularity and functionality, taking into account considerations from both a user’s perspective and from technical constraints. (A final prototype can be seen in figure 1.) Figure 1 – A Prototype Myoelectric Hand. USER CONSIDERATIONS Rejection rates of upper limb prostheses amongst children have been reported to be as high as 50% [2]; indicating that upper limb prostheses that are currently being prescribed are not meeting the needs of young people [3]. Research into rejection of prostheses amongst adult users found dissatisfaction with the prosthesis to be linked to rejection [4], therefore highlights the importance of including the views of users when developing new prosthetic devices. This is supported by Bidiss & Chau’s [3] historical review of upper limb prosthetic use and abandonment, which concluded that “increased emphasis on participatory research and consumer satisfaction is needed” Bidiss et al [5] involved prosthetic wearers of all ages to inform prosthetic design by identifying their key From "MEC 11 Raising the Standard," Proceedings of the 2011 MyoElectric Controls/Powered Prosthetics Symposium Fredericton, New Brunswick, Canada: August 14-19, 2011. Copyright University of New Brunswick. Distributed under a Creative Commons Attribution-Noncommercial-No Derivative Works 3.0 United States License by UNB and the Institute of Biomedical Engineering, through a partnership with Duke University and the Open Prosthetics Project.