Grasp Synthesis for the Hands of Elderly People with Reduced Muscular Force, Slippery Skin, and Limitation in Range of Motion

Abstract

In this paper, we propose a synthesis method for grasping postures by using a digital hand for the elderly. For the virtual evaluation of inclusive design products, it is necessary to synthesize natural grasps for non-healthy hands, including those of the elderly. In modeling the hand of the elderly, we focused on the following three features: (1) narrowed range of motion (ROM), (2) decline in muscle strength, and (3) decline in friction coefficient. The modeling was based on existing studies of physical characteristics of the elderly, and it is possible to create hand models of any age from 20 to 100 years old. We improved our previous method for synthesizing grasps, which was developed for hands with limited thumb ROM, and synthesized grasping postures for elderly people. We found that the grasping posture of the 60-year-old hand was slightly different from that of the healthy hand and that the 100-year-old hand experienced great difficulty in grasping objects.