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Design and experimental verification of a planar type two-dimensional piezoelectric actuator

Piezoelectric actuators have been applied to various applications due to its compact configuration, high force to volume ratio and high precision. In this paper, we present a planar type piezoelectric actuator that has two-dimensional (2-D) motorization capability. This 2-D piezoelectric actuator is constructed by a 0.5 mm thick stainless-steel plate with one 45 mm by 31.8 mm by 0.2 mm piezoelectric PZT that attached on its surface. Using this PZT sheet and driving at two different resonant frequencies with a relationship of integer multiples and a phase difference, traveling waves can be generated to drive the 2-D piezoelectric actuator moving in x- or in y- directions. This driving method is called two-frequency-two-mode. Setting driving frequencies of activated modes to be integer multiples is to stabilize the period of the generated traveling wave and thus increase the propelling efficiency. In addition, the input signal is superposed by the two resonant frequencies on two specific bending modes to selectively drive the 2-D piezoelectric actuator to move in a particular direction. Furthermore, to assist the chosen of the driving voltage ratio and phase difference, Hilbert transform was applied. The weight of the piezoelectric actuator is 17.4 g, and the average moving velocity can reach 1.60 mm/s in x direction and 0.93 mm/s in y direction, where the driving voltage was 100 Vpp. In this paper, numerical studies and experimental studies are presented to verify the performance of this 2-D piezoelectric actuator.