Design of a robotic finger using series gear chain mechanisms

This paper designs a new underactuated robotic finger using a special transmission mechanism. The transmission mechanism consists of a set of gears and a spring to produce connected motions and adaptive curling when the finger moves in free space and when it contacts with the environment, respectively. The connected motion is realized by kinematic constraints of the joints instead of the static equilibrium of joint elastic elements that are frequently adopted in underactuated mechanisms. The motor torque is effectively used to increase the gripping force due to the mechanism. In addition, a reduction of the transmission components also simplifies the assembly process and decreases the size and weight of the finger, which is useful in attaching it to the arm as a prosthesis.