Light and Variable Stiffness Bending Actuator Bionic from Inchworm

Soft gripper is with many advantages, it can grasp and move fragile objects safely. Soft gripper has a good shape adaptive ability for grasping the irregular objects. The grippers actuated by shape memory alloy (SMA) are with the characteristics of light weight and easy control, but their bending angle is small and grasping ability is very limited. In this paper, we proposed a kind of super lightweight variable stiffness gripper based on the SMA wire, the design principle was inspired by the movement of the inchworm. Compared with the previous soft grippers, the bending theory of the gripper is novel. The gripper is with a larger bending angle, and the characteristics of light weight and simple fabrication structure. The gripper contacted the object at low stiffness and grasped at high stiffness. The experimental results indicated that the gripper could grasp the target object smoothly, and the bending angle and force can adapt to some special situations.