A novel pneumatic soft sensor for measuring contact force and curvature of a soft gripper

Soft pneumatic grippers always have characteristics of simple structure, good compliance, and natural motion, which make them have a wide range of applications. Nevertheless, there is a significant challenge that sensors used for detecting gripper's force and deformation are asked for having good deformability and simple structure, and doing not limit gripper's behavior. Based on the requirements, a novel pneumatic soft sensor (PSS) is designed and manufactured in this paper. It is composed of a sensing body and a pressure sensor. The sensing body is made of silicon rubber, and has a simple structure and fabrication process. Due to the characteristic of silicon rubber, it can be easily embedded into a soft gripper without restricting its behavior. According to the inner pressure of sensing body, PSS can measure contact force and curvature by building relation models of pressure vs. contact force and pressure vs. curvature, and its measurement accuracy is tested by a large of experiments. The results validate the effectiveness and reliability of PSS. Finally, a novel soft pneumatic finger with two air chambers is designed and fabricated. One of air chambers named inflated air chamber is used for actuating the finger, and another is called sensing air chamber with the function of PSS. Each air chamber has a pressure sensor for measuring inner pressure. The sensing air chamber makes the finger have a self-sensing ability, which has been verified by several tests.