Picking food by robot hand with tree-frog like pad in various wet conditions

Abstract Achieving stability with less squeeze in picking up wet-soft objects is still challenging for robots. To accomplish this challenge, preventing slippage between robotic grippers and an object is crucial. We used micropatterned pads on robotic grippers to enhance wet adhesion when picking up food items. This paper examines the role of micropattern interfaces in preventing slippage by experimental evaluations, in which soft robotic grippers picked up and released food samples such as tofu, quail egg, coffee jelly, konjac, and jelly under various wet conditions. A micropatterned pad, inspired by the toe pad of a tree-frog, comprises a large number of squared cells that are separated by channels. Normal pads without any micropattern were also made for comparison. Experimental results showed the micropatterned pad required less squeeze force than that of the normal pads, resulting in less deformation of a grasped object such as a piece of tofu. The potential of the micropatterned pad to prevent slippage between a robotic gripper and a fragile deformable object in various wet conditions without a complicated control method was demonstrated, thereby promising wider robotic applications in the food, service, and medical industries.