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It has been reported that using the method of one-frequency-two-mode to drive a piezoelectric linear motor, the nature resonant effect induced by the finite boundaries can be eliminated. The structure of the piezoelectric linear motor is based on placing two piezoelectric actuators on a one-dimensional finite plate. This method uses a single driving frequency at the middle of two adjacent bending modes to drive these two piezoelectric actuators with a 90° phase difference, and a traveling wave can be generated. However, due to the driving frequency was not directly at the resonant frequency, the efficiency and traveling distance cannot be very efficient. Based on our previous studies, it shows that the driving voltage and velocity of displacement has a linear relationship, and the size and location of actuators can also influence the distance of generated traveling waves. In this paper, we report our study on using another method of two-frequency-two-mode that used two adjacent bending modes to generate traveling waves. Since the operating frequencies of the two actuators are at resonant frequencies, the efficiency can be very high. Our studied showed that the difference between native electrical impedance and mechanical impedance of the two adjacent resonant modes, the performance of the induced traveling waves can be varied significantly. Furthermore, the total distance and profile of the traveling waves can also be different. To understand this mechanism, we study the influence of the two driving frequencies with different amplitude and phase differences. Thus, the energy that falls into the two adjacent modes can be changed, and the ratio of vibrating amplitudes of these two modes can be adjusted. We demonstrate that the total traveling distance can be much enhanced by controlling the driving amplitude and phase difference between two actuators.
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