Evaluation of Pinching Effort by a Tendon-Driven Robot Hand

In this paper, we focus on the hand posture when a human subject pinches an object, and the correlation between the results of sensory evaluation by the subject and the tendon force of the subject's fingers are investigated. Surface electromyogram (surface EMG) and pinching force are measured during the pinching motion of human subjects. Experimental results show that subjects feel comfortable pinching a 60 [mm] cylinder. The surface EMGs are lower in the vicinity of 60 [mm]. Furthermore, a tendon-driven robot hand is developed as a sensing hand prototype. The surface EMGs and the motor torque are compared in a pinching experiment using the tendon-driven robot hand. Experimental results show that the tendon-driven robot hand is effective for quantitatively evaluating pinching effort. Simulation of the pinching motion is conducted using a simple finger model. The simulation results show the importance of finger posture and the moment arm in estimating tendon force. Taken together, these results demonstrate the possibility of conducting quantitative evaluation using the tendon-driven robot hand.