Biomechanical Analysis of Subjective Pinching Effort Using the Tendon Skeletal Model

In this paper, we analyze a human pinching motion based on biomechanics for the quantification system of a product usability. We compare three experimental results to analyze the relationship between the deep sensation and subjective pinching effort. First, the surface EMG and the pinching force were measured during the pinching motion by a human. Questionnaire results show that subjects feel easy to pinch a cylinder of 60[mm] length. Experimental results show the profile of the surface EMGs reflects the human subjective pinching effort. Second, the pinching motion was simulated using the tendon skeletal model that mimics the variation of human joint moment arm. Simulation results show that the profile of the tendon forces has similar characteristics to that of the human muscle activity. These result suggest the finger posture influences the subjective pinching effort. Furthermore, a tendon-driven robot hand was developed as a sensing hand prototype. The motor torques and the human muscle activity were compared in a pinching experiment using the tendon-driven robot hand. Experimental results show the profile of the motor torques mirrors the human muscle activity. These results show that the tendon force is a useful index for the evaluation of the subjective pinching effort, and it can be used for the quantitative evaluation instead of EMGs.