Dual-Modes Grasping of SMA-Based Variable-Stiffness Soft Gripper

In this article, we have designed a novel variable-stiffness soft gripper that combines the advantages of both flexible and rigid grippers. It is capable of performing two different tasks: pinching and enveloping. The soft gripper comprises spring steel sheets, memory alloy sheets, tendons, and servo motors, offering the advantages of low cost and simple structure. This variable-stiffness soft gripper can freely switch between the pinching and enveloping by heating the memory alloy sheets and controlling the tendons with servo motors. Finally, to validate the effectiveness of the soft gripper and the algorithm, we constructed experimental platforms for autonomous grasping in virtual and real environments. Experimental results demonstrate that our variable-stiffness soft gripper exhibits excellent grasping performance, stably pinching, and enveloping objects of various shapes and materials, and the achieved grasping success rate is 90%, surpassing the performance of using only precision pinching or enveloping.