Design and Optimization of a Deep Sea Bionic Robot Fish Based on Phase Change Actuator

ABSTRACT In this study, a bionic fin drive system suitable for deep‐sea environments is proposed. The system heats the phase change material (PCM) through the heat‐conducting medium and converts the expansion generated during the phase change process into hydraulic energy. Finally, the tail fin swing and pectoral fin expansion are realized through a novel motion conversion device, which offers the advantages of simple structure and low cost. In addition, the effects of the heat transfer medium and the thickness of the fish body outside the phase change actuator (PCA) on the output performance of the fin PCA were analyzed. The flexible adjustment of the tail fin's swinging characteristics can be realized by adjusting the voltage and duty cycle applied to the PCA heating sheet. A bionic fish prototype equipped with a phase‐change drive system has been successfully fabricated. The experimental results indicate that the robot can swim straight at a speed of 36 mm/s and complete a quick turn with a radius of 3.2 BL. Through the simulation of deep‐sea environment experiments, the robot can still achieve flexible underwater movement under water pressure of up to 110 MPa without bulky pressure‐resistant devices. These excellent performances demonstrate the reliable movement ability of the bionic robotic fish in the extreme deep‐sea environment.