A reconfigurable exoskeleton bionic rigid-soft combination gripper

Soft-body grippers are highly pliable due to the use of flexible materials, which enable safe grasping of objects, but their load-bearing capacity is limited by the mechanical properties of the materials themselves. To address the problem of insufficient stiffness of traditional soft-body grippers, this paper proposes a reconfigurable exoskeleton bionic stiff-flexible gripper inspired by the hydraulic legs of spiders. The gripper is designed with three switchable working modes, and the quick-connect removal mechanism works in concert with the lower fixed jaws to adapt to the grasping needs of objects of different sizes and masses. The joints adopt balloon actuators that mimic the hydraulic leg mechanism of a spider, which can realize adaptive adjustment of the center position and drive the exoskeleton structure to complete the deformation action. Based on the contact-induced extrusion interaction between the balloon and the exoskeleton, a theoretical model of nonlinear actuation is developed. The balloon is simulated using finite element analysis to determine its effective operating range. Furthermore, a rectangular silicone membrane is designed to envelop the exoskeleton surface, enhancing the system's flexibility and ensuring consistent structural support. The experimental evaluation of the comprehensive grasping performance of the gripper shows that the reconfigurable exoskeleton gripper can effectively grasp objects in the size range of 3-230 mm with a maximum weight of 1 kg, which significantly extends the application range and load-bearing capacity of the traditional soft gripper.