Design and Analysis of Modular Gripper Finger Actuated by Antagonistic Wire and Shape Memory Alloy Springs

Abstract

The traditional underactuated grippers can only passively adapt to the shape contour of the object to complete the envelope or grasping action. In this paper, a wire and shape memory alloy (SMA) spring‐based differential drive gripper finger are proposed, which can actively control the grasping morphology according to the objects to be grasped, and are more in line with the grasping characteristics of the human hand. The wire simulates the flexor muscle, and the SMA and reset springs simulate the extensor muscle of the finger, which together control the finger morphology. According to the principle of moment equilibrium, the static mechanical model of the gripper is established, and the influence of the wire driving force and the equivalent stiffness of the finger joints on the grasping morphology are analysed, and the theoretical grasping force is verified by ADAMS simulation. A comparative analysis of the grasping force between the non‐active and active morphology control is presented. Finally, the experimental system of the gripper is constructed, and the verification of the deformation morphology of the single finger and the gripper’s grasping experiments is completed. The results show that according to the contour size of the object, by actively controlling the wire force of the gripper and the equivalent stiffness of the joints, the enveloping or grasping action for different objects can be completed. In addition, the grasping force of the finger can be improved by actively controlling the grasping morphology.