Underactuated Finger Mechanism Using Contractible Slider-Cranks and Stackable Four-Bar Linkages

This paper presents an underactuated finger mechanism that is able to conduct both self-adaptive grasping and natural motions, such as flexion and extension. The robotic finger is realized with a three degrees-of-freedom mechanism composed of stackable four-bar linkages and contractible slider-cranks having a linear spring in each mechanism layer. Kinematics and static force analysis are performed to reveal the operation principle of the proposed finger mechanism. The procedure for synthesizing the linkages is also suggested using Freudenstein's equation. Finally, both simulations and experiments are conducted to confirm the design feasibility.