A particle jamming soft gripper integration of annular microwedge adhesion

A key challenge in robotics is developing efficient methods for grasping objects of different shapes, sizes, poses, and properties. In this study, we propose a positive pressure actuation gripper that combination of annular microwedge adhesion and particle jamming. The gripper comprises an elastic membrane enclosing a mass of granular material, allowing for control of the backing stiffness during contact. In the inflated state, the elastic membrane is stretched, generating centripetal loading force for annular microwedge adhesion. By transitioning into a negative pressure jammed state, a rigid backing stiffness is achieved to maintain adhesion stability, later reverting to atmospheric pressure enables the gripper to release the object. Consequently, this gripper through annular microwedge adhesion offers controllable adhesion for grip and release a wide range of objects that are typically challenging for current soft grippers, such as flat objects, soft objects, or objects with complex geometries. We fabricate the positive pressure actuation gripper and clarify its working mechanism for both flat and curved surfaces. Furthermore, a theoretical analysis is carried out to calculate the frictional stress of the elastic membrane when it is in contact with an object. Experimental results on contact area demonstrate the feasibility of positive pressure actuation mechanism for annulus microwedge adhesion. The payload test determines the parameters of the elastic membrane with the best adhesion performance. The final demonstration shows the applicability of this soft gripper in various scenarios.