UT hand I: A lock-based underactuated hand prosthesis

•A new anthropomorphic hand prosthesis prototype has been developed: the UT Hand I.•The hand is moved via a combination of DC motors and tendon-pulley underactuation.•It contains joint locking mechanisms to control underactuated degrees of freedom.•The hand can perform three different grasp types used in the activities of daily life.

In this paper, a new prototype underactuated hand prosthesis is presented. Its design is based on a robotic finger concept featuring tendon-pulley underactuation, joint coupling, and a series of joint locking mechanisms. The joint locks serve to actively control the degrees of freedom of the four fingers, allowing a single actuator to perform a variety of grasping motions. The thumb is separately actuated by a combination of opposition and flexion motors. Rubber fingertips add compliance to the grasp, and can be equipped with an integrated tactile sensor array. The prototype's kinematics are evaluated, and its functionality is demonstrated by performing a series of grasps. The results show that the UT Hand I provides the advantages of minimal actuation, without reducing its functionality.