An anthropomorphic design guideline for the thumb of the dexterous hand

The preeminent manipulation capabilities of the human hand are undoubtedly related to the thumb. In view of this, this paper presents an anthropomorphic design guideline for the thumb of the dexterous hand. Anatomy analysis of the human thumb represents an excellent base from which a robotic design can be inferred. With simplification of human thumb's joint motion model, five configurations of thumb are given for the design of dexterous robotic hand. A new method for determining the position of thumb on the palm is proposed, according to the Euler Theorem about Finite Rotation of Rigid Body. A numeric method for computing the opposability of the thumb is described based on Monte Carlo methods, to evaluate dexterity of the hand in object manipulation. In order to verify the effectiveness of the proposed method, it is applied to the revised design of the HIT/DLR II hand. Performance indexes of both the original and the revised hand are calculated for comparison. The opposability of the thumb on revised dexterous robotic hand is 2.92 times of the original, which indicates the effectiveness of the proposed method.