Open-Loop Control for Displacement of Balloon-Type Dielectric Elastomer Actuator Pre-Stretched with Water Pressure

Soft actuators have attracted significant attention owing to their unique characteristics and potential for various applications. A dielectric elastomer actuator (DEA) is a type of soft actuator driven by electric voltage and has superior characteristics, such as a fast response, light weight, and simple structure. Several studies have been conducted to analyze the static and dynamic characteristics of a DEA to control its displacements. However, a theoretical analysis of dynamic characteristics of balloon-type DEA including their drive system has not yet been performed. In this study, we analyzed the dynamic characteristics of a balloon-type DEA pre-stretched with water pressure. To this end, we fabricated a DEA using poly (dimethylsiloxane) (PDMS) as an elastomer film and carbon grease as an electrode. We constructed a physical model of the balloon-type DEA pre-stretched with water pressure based on a water oscillation model in an experimental system. Further, we derived an analytical solution for the equation of motion of the system and evaluated the frequency and dynamic responses of the DEA. The theoretical values calculated by the model are in good agreement with the experimental values. Furthermore, we attempted an open-loop control for the displacements of the DEA using the constructed model and successfully achieved it for various input signals. Finally, we demonstrated an application of the balloon-type DEA pre-stretched with water pressure as a membrane pump, which can help generate various pressure waves that are important for artificial hearts or microfluidic cell culture systems.