Fabrication of a Miniature Rubber Muscle Actuator Driven by Gas-Liquid Phase Change

Abstract

The ultimate goal of this research is to develop an artificial micro muscle in which a tiny compressor is installed. Pneumatic actuators, such as pneumatic artificial rubber muscle (PARM) or rubber bellows, have been widely used in many industrial and research fields, since they have merits such as being compact and lightweight. However, the size of the compressor driving the actuator is relatively large. In order to solve this problem, the authors have been researching soft actuators driven by the gas-liquid phase change (GLPC) of fluorocarbon. Fluorocarbon (C₅F₁₁NO) is a substance that has a relatively low boiling point (50°C) and a low heat of evaporation (104.65 kJ/kg, whereas that of water is 2260 kJ/kg). In this research, PARM driving experiments utilizing the GLPC were conducted, and a PI control system was built to test step response and frequency response of actuator. The frequency response up to 4.0 Hz was clarified and the corner frequency of approximately 1.5 Hz was confirmed.