Research on pre-curved spiral wound pneumatic soft gripper

The use of elastic instability to improve the performance of bionic soft robots is getting more and more attention. In this paper, a pre-curved spiral wound pneumatic soft gripper with a monostable structure was designed, which consisted of a strain-limiting layer and a fast pneumatic grid channel layer. The strain-limiting layer was axially pre-stretched, and the fast pneumatic grid channel layer was deflected at a certain angle along the axial pre-stretching direction to bond with the strain-limiting layer. After the pre-stretching was released, a spiral gripper with a pre-curved angle was obtained, which could exhibit a monostable behavior when actuated. Through theoretical and simulation analysis, the pre-bending mechanism under non-pressure actuation and the bending mechanical behavior under pressure actuation were studied. The analysis shows that the stretching ratio and the deflection angle are the key parameters affecting the performance of the gripper. At last, the static test and grasping test of the soft gripper are carried out. The results show that the gripper has good target adaptability and grasping ability. Due to its monostable structure, the gripper can hold objects 1.35 times its weight in the initial state of zero air pressure, and under the condition of pressure actuation, it can hold objects up to 20.85 times its weight.