A passive universal grasping mechanism based on an everting shell

2026-05-29

AI Summary

This work addresses the challenge of adaptive grasping for objects of arbitrary shape, size, and stiffness in general-purpose manipulation by proposing a passive, monolithic soft gripper based on elastic bistable shells. The design leverages contact-triggered shell buckling to drive compliant fingers that autonomously conform around an object and achieve self-locking, enabling stable grasping without external actuation, sensing, or feedback. The key innovation lies in the novel integration of bistable shell mechanisms with distributed compliant structures, which enables reliable enveloping grasps under entirely uncontrolled conditions. Experimental results demonstrate that the gripper effectively handles a wide range of rigid objects, with maximum graspable size and load capacity governed by finger length and stiffness.

Abstract

A passive monolithic compliant grasping mechanism that works based on the eversion of an elastically deformable bistable shell is conceptualized. It comprises grasping arms made of beam segments that work in conjunction with the everting shell. The grasper is capable of picking up a stiff object of any shape up to a maximum size and weight. The bistable shell everts upon contact with the object to enable the grasping arms envelop the object forming an enclosure. The mechanism then stays in that configuration until it is actuated again to turn the shell back to its original configuration and thereby opening the enclosure to release the object. The stiffness of the arms decides the payload of the mechanism. The size of the arms decides the largest object that can be grasped and held. The arms have distributed compliance so that they can conform to the shape of the object without applying undue force on it.

Problem

• passive grasping
• universal grasping
• bistable shell
• compliant mechanism
• object manipulation

Innovation

• passive grasping
• bistable shell
• eversion
• compliant mechanism
• universal gripper