A small-scale swimmer actuated by acoustic radiation force

A small-scale swimmer based on a piezoelectric actuator is proposed in this work, which could serve as the thruster for a minitype underwater robot. The out-of-plane stretching vibration mode in the thickness direction of the piezoelectric actuator is selected as the operating mode. Acoustic radiation propultion is generated due to the difference in acoustic impedance between solid and liquid media, then the opposite acoustic driving force makes the swimmer move forward. The vibration modes of piezoelectric actuator in dry and wet modals are compared through the finite element simulation, and verified by mechanical vibration characteristic test. Then a prototype with the size of & phi; 37 mm x 45 mm is fabricated. The underwater performance shows that its linear speed achieves 33.93 mm s-1 under the voltage of 160 Vp-p with the frequency of 900 Hz and has a capacity of carrying 20 g loads, which confirms the feasibility of the proposed underwater driving method.