This paper presents an ultrasonic motor with a high thrust-weight ratio. The miniaturized motor is 13 mm × 5 mm × 3.8 mm in size and uses the first-order bending vibration mode (B1 mode) and second-order bending vibration mode (B2 mode) to realize bidirectional movement through a single-phase driving signal. The theoretical trajectory and output thrust of the motor driving foot are initially studied. Subsequently, a finite-element model of the motor is established, and its dynamic performance is studied. Next, the prototype of the motor is fabricated and tested. The results show that errors in the B1 and B2 modes are 1.976% and 0.436%, respectively. Finally, an experimental setup is constructed to test the mechanical properties of the motor. The maximum output velocities of the motor is approximately 158 mm/s at 58.917 kHz in the B1 mode and approximately 137 mm/s at 113.581 kHz in the B2 mode. The maximum thrust force values of the motor in the B1 and B2 modes are approximately 1.32 N and 1.08 N, respectively, with 7 N preload and 120 V voltage. The overall mass of the motor stator is 1.0 g, so the motor thrust-weight ratio reaches 134.69.
Equivalent circuits of piezoelectric structures such as bimorphs and unimorphs conventionally focus on the bending vibration modes. However, the longitudinal vibration modes are rarely considered even though they also play a remarkable role in piezoelectric devices. Losses, especially elastic loss in the metal substrate, are also generally neglected, which leads to discrepancies compared with experiments. In this paper, a novel equivalent circuit with four kinds of losses is proposed for a beamlike piezoelectric structure under the longitudinal vibration mode. This structure consists of a slender beam as the metal substrate, and a piezoelectric patch which covers a partial length of the beam. In this approach, first, complex numbers are used to deal with four kinds of losses—elastic loss in the metal substrate, and piezoelectric, dielectric, and elastic losses in the piezoelectric patch. Next in this approach, based on Mason’s model, a new equivalent circuit is developed. Using MATLAB, impedance curves of this structure are simulated by the equivalent circuit method. Experiments are conducted and good agreements are revealed between experiments and equivalent circuit results. It is indicated that the introduction of four losses in an equivalent circuit can increase the result accuracy considerably.
A novel standing wave linear ultrasonic motor with a single source of sinusoidal wave is presented for exciting first-order longitudinal and second-order bending coupling working modes. First, on the basis of a kinematics analysis of the composite piezoelectric beam, the initial motor structure size is created, and the frequency difference of the two working modes of the motor with the initial sizes is 10,950.8 Hz. Second, the initial motor design is optimized according to the subproblem approximation algorithm to obtain the final motor size. The frequency difference in the optimized motor becomes 121.2 Hz. Third, transient analysis of the optimized motor is carried out, and the motion trajectory of the driving foot is an oblique ellipse. Switching the drive electrodes can realize the bidirectional movement of the motor. Finally, the motor prototype is fabricated, and its vibration characteristics and mechanical properties are tested. The maximum no-load motor speed at 96.6 kHz is 168.5 mm/s. The performance in the forward and backward directions is identical according to a test of no-load velocity versus voltage. With 150 V pp voltage and 10 N preload, the motor's maximum output thrust is approximately 0.9 N with a moving speed of 16.6 mm/s at 96.6 kHz. The overall motor mass is approximately 3.4 g. Thus, the thrust-to-weight ratio reaches 27.01.
A novel standing wave linear ultrasonic motor with double driving feet based on longitudinal-bending coupling mode is designed in this study. The motor adopts the bonded-type structure, and four pieces of piezoelectric ceramics on a metal beam are divided into two groups. Two voltages with 90° phase difference are applied to two groups of Pb-based lanthanumdoped zirconate titanates ceramics, respectively. Then the first longitudinal and second bending modes generated are superimposed on the stator, which can produce elliptical motion trajectories on the driving feet. The excitation method and driving mechanism of the motor are illustrated in detail. A finite model of the stator is established in the ANSYS parametric design language interface, and the operating mode of the stator and motion trajectories on the driving feet are discussed. The prototype is fabricated, and its impedance characteristics and mechanical output performance are tested. The results show that the maximal no-load velocity of the motor is ∼147.78 mm/s under a voltage of 200 V and a preload of 3 N. The maximum thrust force is ∼1.1 N when the voltage and preload are 200 V and 6 N, respectively.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.