Cunyue Lu

Study of a Mini-Ultrasonic Motor with Square Metal Bar and Piezoelectric Plate Hybrid

A new mini-ultrasonic motor with a metal bar and piezoelectric plate hybrid as a stator has been studied. Four piezoelectric plates are bonded to four sides of the metal bar. The metal bar is made of brass and the piezoelectric plates are made of Pb(Zr–Ti)O3. The polarization direction is vertical to the piezoelectric plate. Compared with the cylindrical type of motor, the motor with a square cross-section makes polarization more sufficient and the signal wire easier to be welded. In this study, the modal and harmonic analyses of the stator were performed by using the Finite Element Method. The resonance frequency of the motor is about 100 kHz, the no-load revolution is above 6000 rpm and the maximum torque is about 60 µN m. This new mini-ultrasonic motor has potential applications.

Temperature evaluation of traveling-wave ultrasonic motor considering interaction between temperature rise and motor parameters.

In this paper, a novel model for evaluating the temperature of traveling-wave ultrasonic motor (TWUSM) is developed. The proposed model, where the interaction between the temperature rise and motor parameters is considered, differs from the previous reported models with constant parameters. In this model, losses and temperature rises of the motor were evaluated based on the temperature-related varying parameters: the feedback voltage Vaux of the stator, dielectric permittivity ɛ and dielectric loss factor tanδ. At each new temperature, Vaux, ɛ and tanδ were updated. The feasibility and effectiveness of this proposed model was verified by comparing the predicted temperatures with the measured one. The effects of driving voltage, driving frequency and ambient temperature on the predicted temperature were also analyzed. The results show that the proposed model has more accurate predicted temperature than that with constant parameters. This will be very useful for the optimal design, reducing the heat loss, improvement of control and reliability life of TWUSM.

Piezoelectric Rod Micro Ultrasonic Motor with Shear-bending Modes

In this paper we propose a new mechanism for exciting shear-bending vibration in a piezoelectric ceramic rod. A mini-ultrasonic motor prototype with this concept was designed. Both finite element method (FEM) analysis and experimental results demonstrate the concept.

Ultrasonic motors using shear-type piezoelectric ceramics

The shear piezoelectric constant value for d<inf>15</inf> has a higher value compared with constant d<inf>31</inf> or d<inf>33</inf>. Also, the value of the shear electromechanical coupling coefficient k<inf>15</inf> is bigger than that of k<inf>31</inf> or k<inf>33</inf>. A design for an ultrasonic motor based on the shear coefficients has the potential for superior performance, relative to conventional d<inf>31</inf> and d<inf>33</inf> based ones. Thus, this paper presents ring type, tube type, disk type and rod type piezoelectric ceramic elements, which use the d<inf>15</inf> shear piezoelectric constant effect. The application methods and driving mechanism of the typical ultrasonic motors which use the shear piezoelectric ceramic elements are analyzed. The applications of shear piezoelectric ceramic elements accords with the requirements of the development trends of ultrasonic motors, such as large strain and miniaturization.

Design and finite element analysis of a novel longitudinal-torsional hybrid ultrasonic motor

This paper reported an ultrasonic motor using the 1st longitudinal and the 2nd torsional (L-T) modes. The stator slots were useful to tune the resonance frequencies and increased L-T displacements largely. By cutting slots, which determined the number of oscillators, the whole stator was changed into independent vibrators. The more independent vibrators, the bigger power it outputs. The stator possessing different number of vibrators can realize frequency tuning by increasing outer diameter. Piezoelectric elements were pasted on the outer surface of the metal substrate. L-T hybrid vibrations of the driving surface can be excited when suitable electrical signals were applied to piezoelectric units. The working principle of the designed motor was analyzed particularly. The optimal slots dimension and location, including vibration characteristics can be obtained using the finite element analysis software, ANSYS. The analyzed results and experiments verified the proposed motor possessing good performance.

A piezoelectric-drive micro displacement platform for microscanning

In this work, a new type of micro-displacement amplification driving platform is proposed. Piezoelectric stacks are used as the driving elements in the platform. The displacement amplification mechanism is a diamond shaped amplification mechanism based on flexible hinge. Four displacement amplification mechanisms place around the platform to decouple two dimensional motions. Finite element method is used to study the displacement amplification factor, natural frequency and two-dimensional motion displacement correlation. At last, a platform is made to validate the simulation results. The results between test and simulation are basically the same. The micro displacement amplification platform can be used for microscanning. The platform can carry a camera to do microscan, so the cameras pixel resolution can be improved without increasing the cameras size.

A powder transport system based on piezoelectric ceramic stack actuators

A novel actuator-driven powder transport system is proposed in this paper. It has two sets of piezoelectric ceramic stacks whose vibrations couple together and make the powder transport pipe do elliptical vibration. The powder on the pipe wall can be thrown up, leading to the relative motions between the powder and pipe wall and thus the powder is transported. To get higher transport efficiency and speed, a displacement amplifier is adopted. The movement of the whole system is analyzed and discussed in theory and the mathematic model is established. The relationship between the input voltage and the output speed is obtained by means of simulation analysis. Theory foundation is provided for further study and practical application.

Research on transient characteristics of a novel longitudinal-torsional ultrasonic motor

This paper introduces a longitudinal-torsional USM. Based on the electrical characteristics of the piezoelectric vibrator, a theoretical model was investigated. It can be used to derive the transient response characteristics of electrical parameters. The finite element analysis was also used to verify the correctness of the parameters change trend. The transient state of the analyzed parameters includes three time interval, the on transient state, steady state and off transient state. The simulation and experiment verified the validity of the theoretical model and performance of the USM. The above mentioned electrical and mechanical parameters rise or fall by degrees in accordance with an exponential form except that the speed of revolution falls linearly approximately. The revolution speed of this USM is about 45 r/min. Experimental results also showed that the response speed of the USM is fast, as the startup time is about 6 ms and the turnoff time is 2 ms.