Development of a robotic digit joint mechanism for knot tying task

In this paper, we propose a novel transmission mechanism for developing a robotic hand for performing knot tying task. Our goal is to develop a robotic hand system that supports the people with disability in dexterous hand movements. The target is to handle clothing and other soft material which require both precision and strong grasp during its sequence. First, the design concept is discussed by analyzing the digit movements and their functions in a knot tying sequence. An issue of developing transmission mechanism is discussed from the result. A mechanism applying a swash plate cam is presented for joint movement control to minimize weight and complexity, while being capable of holding high torque. A prototype digit is assembled and tested to confirm its characteristic and discussion of future modification is presented.