Design and development of a variable structure gripper with electroadhesion

Soft grippers are a novel kind of front-end actuators for robotics that offer great benefits such as easy control, superior grabbing capability, and close contact with the environment. They have vast application possibilities in numerous industries such as agricultural picking, item sorting, and medical rehabilitation. In this paper, a soft gripper with a variable structure and electrostatic adsorption is proposed. The gripper includes three fingers uniformly dispersed in the shape of a circle, which can adapt to varying sizes of grabbing objects by dynamically modifying the opening angle of the fingers. Aimed at addressing the existing issue of lacking multi fingers soft pneumatic grippers (SPGs) in grabbing tiny flat items, it is enhanced by embedding an electroadhesion (EA) films at the bottom of the soft pneumatic fingers of the gripper. It is simulated that the diameter adjustment range of this gripper is 0-482 mm, and the angle adjustment range is 0-180 degrees via ABAQUS simulation. Finally, the adaptive grabbing capacity of the soft gripper was validated via experiments. The trials reveal that the gripper can grab items of different sizes by altering the opening angle of the fingers and the maximum load of the gripper can reach 10.91 N during specific grasping operations. The findings confirm that the SPGs with variable structure and EA described in this paper has a high gripping range and the capacity to grab thin flat items. We believe that its excellent gripping performance will encourage different uses of this gripper in everyday life and industry.