Research On The Screw-type Ultrasonic Motor With Plate-attached Beam Structure

The screw-type ultrasonic motor has many technical characteristics such as high running accuracy, good stability and self-locking because its motion and power transmission is realized by screw pairs. It has extensive application prospects in aerospace,precision medical equipments, intelligent robots, optical precision instruments and so on.This paper is aimed at solving the problem of lower output force caused by single contact area driving between stator and mover. To increase output force, a screw-type ultrasonic motor with plate-attached beam structure which adopts multiple contact areas to drive simultaneously is designed and fabricated.Firstly, the working mode of the screw-type ultrasonic motor with plate-attached beam structure is studied in this paper. The piezoelectric ceramic plate with d31 working mode is used to excite the stator. The principle of bending vibration deformation for the elastomer excited by piezoelectric ceramic plate is analyzed. The vibration performance of the stator with free-beam structure under excitation of the piezoelectric ceramic plate is acquired through theoretical analysis and simulation. Then the exciting mode of the novel motor proposed in this paper is analyzed. The principle for realizing drive synchronously by means of multiple contact areas on the surface of stator is illuminated. To reveal the operational mechanism of the motor, the movement trajectory equations of the particles located on the surface of stator are established.Based on the theoretical analysis results of excitation mode, the screw-type ultrasonic motor is designed according to the realization conditions for driving simultaneously via multiple contact areas. And then the specific structure dimensions are determined. To obtain the vibration response of stator, the vibration performance is simulated by means of the software ANSYS of finite element simulation. And it will include the modal analysis,harmonic analysis and transient performance analysis specifically.According to the structure design, theoretical analysis and simulation results of the screw-type ultrasonic motor with plate-attached beam structure, the experimental prototype is processed and manufactured. Then the output characteristics test system of screw-type ultrasonic motor with plate-attached beam structure is established based on the implementation platform of programming software LabVIEW. And the system will contain many experimental instruments and equipments like the data acquisition card, laser displacement sensor and so forth.In order to verify the theoretical and simulation analysis results, the impedance and vibration characteristics of the prototype are measured to gain the performance such asresonant frequencies, vibration mode shapes, et al. According to the established test system,the output characteristics of the prototype are tested. The experimental results show that the output force and velocity of the prototype increase linearly with the increase of exciting voltage approximately. The maximum output force of 75 N is achieved when the exciting voltage and frequency are 160 Vp-p and 28.9 kHz, respectively. The maximum output power and efficiency are 14.56 mW and 3.74% under the exciting voltage of 120 Vp-p.