A Fish-Like Underwater Miniature Robot Capable of High-Speed and Controllable Locomotion

This letter presents the design, fabrication, and performance test of a fish-like underwater miniature robot directly driven by two piezoelectric actuators. Considering the different medium conditions and the ever-present challenge of waterproofing in underwater motion, the miniaturization of underwater robots is regarded as an innovative task. In this letter, by mimicking the swing of fish caudal fins to generate thrust, a piezoelectric actuator is used to directly drive the artificial fins. This robot merely consists of six components, including two PZT actuators, a pair of caudal fins, and two glass fiber fixtures. Such a design serves to streamline the process of assembly. The total mass of prototype miniature robot is only 0.8 g and has a body length (BL) of 4 cm. The robot has demonstrated its capacity for flexible and swift underwater movement. It can perform straight and turning movements underwater, with a maximum forward speed of 8.01 BL/s (32.05 cm/s) at a driving voltage of 180 V. It has a maximum payload of 0.84 g and minimum turning radius of 7.9 cm.