A Pneumatic Soft Gripper with Configurable Workspace and Self-sensing

In this paper, we present a novel pneumatic soft gripper with a configurable workspace and perception to grasp various objects and recognize their sizes. The soft gripper consists of three pneu-net soft fingers embedded with resistive strain sensors and cascaded by a stretchable palm. The pneu-net soft fingers are fabricated through a lost-wax casting process. Each strain sensor is designed with an ionic hydrogel-elastomer hybrid structure and embedded into a soft finger to recognize its deformation. The stretchable palm is designed with an opening-closing parallel mechanism driven by a pneumatic fiber-reinforced soft actuator to modify the grasping workspace of the gripper. The characterization experiments are conducted to demonstrate the excellent performance of soft gripper. Based on the measurement of the strain sensors, we propose two kinds of grasping strategies for the soft gripper: a traditional finger-bending identification strategy (FBI strategy) without the active palm and a new palm-closing identification strategy (PCI strategy) with the active palm. Experimental results with an industrial robot demonstrate that our soft gripper with the PCI strategy can perform more robust picking tasks and more accurate identification tasks than with the FBI strategy.