Production Engineering for Small-Size and Functional Motion of Total Arm Prosthesis
Yukio Saito and Takanori Higashihara
Faculty of Science and Technology, Tokyo Denki University, Hatoyama, Hiki, Saitama, 350-03 Japan
A total arm electrical prosthesis by microcomputer control is designed for patients who have both shoulders amputated by a work accident and these suffering from the disease of malignant tumour. The prothesis uses 6 coreless micro-motors as an actuator and can act flexion – extension and external – internal rotation of the shoulder, abduction – adduction of the upper arm, flexion – extension of elbow, forearm pro-supination, and openshut of fingers. Each movable part is modulated, and the prosthesis in each amputation part can be manufactured. We use a special linkage shoulder mechanism of rigid body and can obtain natural shoulder movement compatible with the human motion. The hand part can easily change an electrical cosmetic and hook-type hand in a quick change system according to the task. The control system of prosthesis is composed of three singlechip microcomputers and is stored together with a Ni-Cd battery within the dummy arm (left arm). Consequently, we set the following goals: (1) Compact and highly rigid shoulder mechanism. (2) Smaller multiple microcomputer and driven system set by flexible circuit technology. (3) The main controller keeps program in PROM, RAM area of microprocessor, and IC cord as fundamental motions and fixed motions. (4) CAD and/or artificial intelligence techniques are used to shorten the development period and the flexible accommodation. The judgement function of command by a microcomputer, the cooperative movements of each joint, and a teaching system of easy motion data by the handicapped are indispensable in order to ease the burden of operation. Therefore, the order input device which can transmit the intention of the handicapped to a control device of prosthesis and is not a burden to operation is necessary. The weight of prosthesis and control devices should realize portability. In addition the CAD/CAM of the socket for wear which is unaffected by the weight with prosthesis itself is necessary.