BASIC EXPERIMENT TO COMPARE THE PERFORMANCE OF MULTI-ARTICULATED 3-DIGIT MYOELECTRIC HAND

Abstract

The anthropomorphic hands with multi-articulated digit are appealing compared to conventional 1-Degree-of-Freedom hands with 3-digits 3-joints. The coordinated movable joints ease to grasp objects with variety of shape and size while reducing compensative joint movements of the residual limb and torso. Therefore, the developers state their design superiority based on the number of capable prehensile forms, which are important index to describe the static function of holding object(s) within the hand. However, to conduct tasks, the response and efficiency grasping motion are nevertheless important. Further understanding the effect of multi-articulated digit design on the static and dynamic functions, in relation with myoelectric control is a notable topic. In this research, we conducted a comparative experiment between 3-digit hands: 3-joint conventional, Ottobock DMC hand, and 7-joint multi-articulated fingered THK TRX hand. Gripping time of pick-and-place task on large and small diameter cylinders were measured. 3 non-amputee subjects participated in the test using hand mounted on a quasi-prosthesis socket. As result, the large diameter cylinder’s average gripping time of 7-joint hand was 0.77 seconds, larger than that of the 3-joint hand, 0.42 seconds. For the small diameter cylinder, the gripping time for 7-joint hand was shorter than the 3-joint hand.