Bioinspired Coil-Wrap Soft Gripper with Frictional Self-Locking for Enhanced Adaptability and High Load Capacity

Abstract

This article proposes a bioinspired soft coil-wrap gripper (CWG) that achieves concurrent enhancements in load capacity and object adaptability through innovative biomimetic structural design. The gripper incorporates a dual-layer pneumatic architecture: The primary structure comprises an elongated pneumatic chamber with an elastic coating layer, facilitating adaptive contour wrapping around target objects through a biomimetic coiling mechanism. An auxiliary end pneumatic chamber amplifies localized pressure postwrapping, ensuring optimal contact interface and grasping stability. By engineering contact layers with differential friction coefficients (higher inner layer versus lower outer layer), the gripper initiates a frictional self-locking effect during the wrapping process, thereby substantially improving grasping robustness. Experimental validation demonstrates that under pneumatic pressures of 0.1 MPa, the CWG effectively manipulates irregular objects spanning 25–120 mm in size, achieving a maximum payload capacity of 310 N. This research introduces a novel concept for soft grippers by using frictional self-locking to achieve a load capacity that far exceeds the actuation capability.