A Gated Two-Frequency Two-Mode Method for Piezoelectric Motorization

Abstract

In this study, we present a new driving method to generate traveling waves in a finite plate for the application of piezoelectric motorizations. Due to resonant modes which dominate the vibration of finite structures, methods to reduce resonant effects such as using an electric sinker or driving at a non-resonant frequency, have been reported. To take the advantage of natural resonance and to increase driving efficiency, a new method entitled a gated two-frequency-two-mode (G-TFTM) was developed. A piezoelectric bimorph of 1.1g weight with two rectangular actuators was implemented to verify the design concept. One actuator was operated at a first bending mode and the other actuator operated at a second bending mode with phase difference. The driving signal was gated to generate an intermittent excitation to provide a periodic propulsion. To determine the profile of the induced traveling wave, an analytical solution was derived and a numerical model was used. Using these design tools, we experimentally verified that traveling waves can be generated using a G-TFTM method. A 0.1 g object can be moved at a speed of 3.31 mm/s under the condition of a 70-to-20 voltage ratio and a 137-degree phase difference. The moving direction was found to be reversed by changing the phase to -43 degrees. The experimental and numerical data are detailed in this paper to demonstrate the feasibility of this G-TFTM method.

A two-dimensional piezoelectric traveling wave generator using a multi-integer frequency, two-mode method (MIF-TM)

“…However, these methods are not energy efficient since they do not operate at structural resonance. We previously reported a TFTM method and a G-TFTM method to generate traveling waves using resonant frequencies [19,20]. However, the gradual phase shift between the two driving frequencies at the two bending modes produce TFTM traveling waves with vibration profile which drifts from cycle to cycle.…”

“…However, its fabrication can be costly due to the need to have precision control and further fine-tuning on the structure dimension. To use structural resonance for enhancing the efficiency of a traveling-wave type piezoelectric linear motor, we previously reported a twofrequency-two-mode (TFTM) method [19] and a gated twofrequency-two-mode (G-TFTM) method [20]. Both methods demonstrated that using two resonant vibrations, it is possible to generate traveling waves and to push an object.…”

One-dimensional traveling wave type linear piezoelectric moving platform driven by a new two-frequency two-mode excitation method

“…Nonetheless, the velocity of the traveling waves generated in these works could not be adjusted, leading to lower precision and accuracy. In our previous research [13,14], we adopted this method to a fixed platform, generating traveling waves in a structure, and pushing the above objects by friction. However, similar to other works, a moving velocity adjustment was implemented by a vibration amplitude which was controlled by a voltage amplitude.…”