Abstract
Use of a myoelectric prosthetic hand is an effective way to rehabilitate upper limb motor function of amputee. In our previous study, we have already developed a two DoF prosthetic hand which has driving MP (meta phalangeal) joint of interlocked middle finger and index finger, and CM (carpometacarpal) joint of thumb. It is structured to perform three grasping postures, namely, power grip, precision grip and lateral pinch. To realize holding function with these postures, 85% of hand movement for ADL is covered. Though the grip performance of the hand depends on joint angles of thumb and fingers, the shape of hand was decided on an empirically. Therefore, the problem that we cannot design the shape of hand according to desired function was remained. It should be solved to clarify the relationship between hand functions and shape with a proper shape model. In this study, we proposed a shape model for function design of the two-DoF prosthetic hand, and confirmed the hand function by some experiments. Then, we measured their gripping force by pull-out test, and evaluated the hand function in daily life by Pick-and-Place task with selected target which are frequently used in daily life. The result shows following tendency: (1) the bending angles of fingers and thumb are larger, their pull-out force are larger, and their grasping function- are lower, (2) the bending angles of fingers and thumb are smaller, their pull-out force are smaller, and their grasping functions are higher.
