Closed-loop Control of a Pneumatic Soft Gripper for Fast and Accurate Response

Abstract

Soft pneumatic actuators can perform continuous deformation, allowing them to adapt to objects with irregular shapes. Most of the existing research works on pneumatic soft gripper focus on the chosen of material, mechanical structures and the stiffness tunability. The conventional method to realize the motion control of soft pneumatic actuators is by adopting open-loop control but the open-loop control cannot accurately control the movement. In this paper, a closed-loop control strategy is proposed to ensure the fast and stable response of pneumatic soft actuators. The design of a well-studied pneumatic soft actuator is presented in this study. The pneumatic actuation is controlled by the positive and negative proportional valves. The bending angle and velocity of the soft gripper are closed-loop controlled based on the feedback signals provided by the pressure sensors and ranging sensors, respectively. In addition, a soft gripper prototype assembled with three soft fingers is fabricated and demonstrated. The dynamic experiment verifies the performance of the proposed closed-loop control strategy.