Model of a Coil-Reinforced Cylindrical Soft Actuator

Abstract

A cylindrical soft actuator is suitable for applications in which pneumatic or hydraulic cylinders are conventionally used. In this report, we discuss the force output model of a spring-reinforced-type cylindrical soft actuator. This type of actuator outputs a larger force than the air pressure multiplied by the pressure-receiving area. We construct a quasi-static model to explore the reason for this phenomenon, based on the strength of materials. A thick-walled cylinder model with three boundary conditions was defined and analyzed. The model indicates that the rubber cylinder itself transmits pneumatic pressure and contributes to the output force. We also modeled the relationship between the pressure and the elongation of the soft actuator. Experiments were conducted to evaluate the proposed models.