Design of an SMA-driven compliant constant-force gripper based on a modified chained pseudo-rigid-body model

Compliant grippers are important devices for assembling small parts. Analyzing the mechanism efficiently and accurately and designing grippers carefully have also become crucial. In this paper, a shape memory alloy-driven compliant constant-force gripper is developed to create extensive and safe operations. A modified chained pseudo-rigid-body model with additional prismatic pairs is proposed for optimal performance according to mechanical analysis. In the developed gripper, a two-beam binding constant-force mechanism is proposed to apply a constant gripping force in the gripper’s jaws; a constant-force guide mechanism is utilized to extend the actuation stroke and connect the jaws with the actuator. The simulation results of the functional parts are in good agreement with the theoretical results, demonstrating the high accuracy of the proposed beam model. In addition, experimental studies on the gripping force and grasp-release operations verify the effectiveness of the designed gripper and its components.