Bistable Soft Gripper With Tension Net Applied to UAV

Abstract

Physical intelligence for aerial robots greatly enhances grasping and perching performance, but remains in emerging stages. This letter proposes a novel bistable soft gripper for aerial robots with high response speed (0.11 s), large holding force (23.47 N), and active/passive adaptive grasping and perching. The soft gripper is constructed by four bistable fingers, tension nets, and a bidirectional actuation system. The soft finger evolves from a simple bistable rotational joint. Tension nets inspired by spider webs are proposed to improve the energy barrier and grasping performance. Experiments are conducted to measure the gripper's potential energy variation and grasping performance. One peak and two local minima in the energy curve indicate the gripper's bistability. Experimental results show that tension nets can enhance the gripper's energy barrier, response speed, and maximum holding force by 915.07%, 38.55%, and 62.08%, respectively. The gripper's adjustability of the energy barrier is validated, enabling it to switch active/passive modes as needed. The experiments demonstrated static/dynamic grasping and perching for various daily objects with different shapes, sizes, and stiffness for the gripper and aerial robot. Finally, the robot can transport objects outdoors, and can be aerially manipulated by external force, demonstrating its great potential in aerial application.