Underactuated Finger Mechanism for Natural Motion and Self-adaptive Grasping towards Bionic Partial Hand

This paper presents an underactuated finger mechanism enabling both self-adaptive grasping and natural motion such as flexion and extension. It has three degrees-of-freedom mechanism composed of one actuator and a couple of passive components including torsional springs and mechanical stoppers. In detail, the proposed mechanism consists of two five-bar and one four-bar linkages. Since each five-bar linkage contains passive components, it is allowed to have adaptive grasping as well as natural motion for human finger-like behavior. Kinematics and static force analysis are performed to reveal the operational principle of the proposed mechanism. Finally both simulation and experiments are conducted to show the design feasibility of the proposed mechanism