Nozzle-vibration piezoelectric jet for compact underwater robots

Piezoelectric jet drive offers distinct advantages for deep-water operation and miniaturization of underwater vehicles. However, existing piezoelectric jet drives predominantly rely on cavity vibration, where each driving unit requires an independent sealed cavity, making further miniaturization difficult. In this study, a nozzle-vibration piezoelectric jet driving method is proposed. This method uses the piezoelectric vibrator itself as the vibrating nozzle, enabling multiple jet units to operate cooperatively within an open cavity without requiring individual sealed chambers. Furthermore, multi-unit control is achieved through a single signal line by adjusting the driving frequency. The driving mechanism of the nozzle-vibration jet is revealed, and the influence of key structural parameters on driving force is investigated. A modular driving unit is developed, and a control strategy for realizing different motion modes is provided. The proposed modular unit size is 60 mm × 63 mm × 70 mm. It can achieve maximum linear motion velocity 78.95 mm/s (equivalent to 1.305 BL/s), maximum floating velocity 166.67 mm/s (equivalent to 2.381 BL/s), maximum rotational angular velocity 0.909 rad/s, minimum rotation radius 59.6 mm and curvilinear motion. The wireless control scheme is given, and modular driving unit has been tested in several typical application scenarios (load motion and underwater attachment drive).