Analysis on the joint independence of hand and wrist

Due to the hand biomechanical constrains and coordinate manner of motor control, single one joint is difficult to move independently. The aim of this paper is to have an analysis on the joint independence of hand and wrist. At first, a grasp experiment under the tolerance grasping was completed, and the hand and wrist joint angles in different grasping postures were recorded for representing the functionality of human hand. Moreover, based on the recorded postures, the characteristics of each joint were analyzed from correlation and adaptability, for representing the joint inter-joint characteristic and self-characteristic, respectively. In this case, the joint independence was quantified through the joint independence-correlation and independence-adaptability. The quantified joint independence results show that the thumb, index finger and pinky had the highest independence from the view of finger, while from the joint view, the joint independence from high to low were: wrist, metacarpo-phalangeal (MCP), proximal interphalangeal (PIP) and abduction/adduction (ABD). Finally, based on the quantified joint independence, a preliminary actuation configuration was proposed.