Design of An Anthropomorphic Tendon-Driven Robotic Finger

The flexor digitorum profundus, extensor digitorum communis and lumbrical muscle of the human hand play a significant role in the movement of the finger. The structure consisting of these muscles and tendons is important to consider an anthropomorphic tendon-driven finger. However, there are some problems to apply the structure found in humans to robotic fingers using mechanical elements. One of them is that the origin of the lumbrical muscle is not on any bones but on the tendon of the flexor digitorum profundus. Another is the non-constant length of the moment arm of the lateral band at the proximal interphalangeal (PIP) joint. We propose a design based on the kinematic model proposed by Leijnse et al. [1] considering the equalization of the joint torques. The proposed model can be easily realized by a structure consisting of actuators fixed to a base and a tendon-pulley system that maintains the function of those three muscle and their tendons.