Kinematics and dynamics of a tendon-driven prosthetic finger

A tendon-driven finger structure is applied to optimize the mechanism, reduce the complexity and improve the reliability of prosthetic hand, which also realizes the independent movement for single finger. The structure consists of a drive tendon, three knuckles, three joints, torsion springs, and so on. The joint torsion spring is designed to realize the joint preload and the joint reversion after the tendon looseness. By optimizing the spring stiffness, it is able to realize the sequential curling and the large range grip. Based on these analyses, the relation between contact force on the knuckles and the drive torque of the wire wheel, the finger dynamic model and dynamic equations are established. The numerical calculation, simulation and experiments are done to validate the correctness of the theoretical analysis and the feasibility of the finger structure. By the advantages of fewer parts, simpler structure and higher reliability, the tendon-driven finger structure provides favorable conditions for development of multi-degree prosthetic hand.