A Bioinspired Composite Finger with Self-Locking Joints

This paper presents a bioinspired composite finger with self-locking joints that can perform long-time and high-load (27.8 N) grasping tasks with low power consumption. Inspired by the ratchet wrench, the self-locking joint includes a ratchet mechanism to provide a large grip force for the finger through mechanical interlocking. The finger uses two shape memory alloy coils (SMAc) to drive the tendon and open the interlocking. The locked position and strength are studied through kinematics and finite element analysis. In the experiments, the motion of the finger is optimized to achieve a robust grasp. A portable three-finger gripper is used to grasp and lift heavy objects with high payload-to-weight ratio. The gripper with remote control shows its potential applications, for example, in assisting unmanned aerial vehicles to perform tasks of perching and grasping.