Research On T-shaped Linear Ultrasonic Motor Based On Longitudinal Vibration Mode

With the development of science and technology,people from all walks of life put forward higher requirements in the precision field,and linear ultrasonic motors have emerged in this situation.The linear ultrasonic motor is a high-tech product based on piezoelectric ceramics,which is applied to materials science,mechanical design,electricity,automatic control and other disciplines.In this paper,the related theories of T-shaped motors and their mechanical structures,drive systems and control methods are studied in combination with related disciplines.The main research contents are as follows:(1)Completed the relevant theoretical analysis.Based on the piezoelectric equation,the relationship between the two electrical quantities of piezoelectric ceramics(applied electric field,electric displacement)and two mechanical quantities(stress,strain)is analyzed,and the inverse piezoelectric effect equation used is determined.At the same time,the vibration mode of the piezoelectric ceramics was studied,and the piezoelectric ceramic sheets vibrating in the thickness direction were laminated and applied to the stator of the linear ultrasonic motor.After studying the performance and use of piezoelectric ceramics,the mechanical structure of the motor needs to be designed.(2)The mechanical structure of the linear ultrasonic motor was designed.Firstly,the mechanical structure of existing linear ultrasonic motors at home and abroad are compared and analyzed,and the T-shaped structure was confirmed as the research object of this paper.The feasibility of the design is verified by theoretical analysis.Then,a three-dimensional model of the mechanical structure was established through SolidWorks and imported into ANSYS Workbench for related simulation analysis.The simulation analysis mainly performs modal analysis,determines the working mode,and optimize the size of the motor structure to ensures that the frequency difference between the two-order working modes is as small as possible;Harmonic response analysis further verifies that the resonant response occurs at the operating mode frequency;The instantaneous dynamics analysis verifies whether the trajectory of the motor stator driving foot meets the theoretically required elliptical shape.(3)The drive system of linear ultrasonic motor was studied.Since the linear ultrasonic motor presents capacitive characteristics,a series inductance matching circuit is first used to eliminate such capacitive interference.Then through the research on the current situation of ultrasonic motor drive system at home and abroad,it is determined that the DDS technology is used to generate the drive signal.The signal is processed by a conditioning circuit such as amplification and filtering,so that the signal can meet the requirements for driving the piezoelectric ceramic piece.Finally,in order to ensure real-time adjustment of the parameters of the drive signal,this paper uses the form of upper and lower machine to ensure human-computer interaction.The host computer is designed with client software to realize real-time display and adjustment of the drive signal.The lower computer is the drive signal generation and conditioning circuit with STM32 single chip as the core.(4)The control method of the linear ultrasonic motor was determined.Firstly,the control methods of linear ultrasonic motor at home and abroad are studied to determine the control method which is suitable for this paper.According to the working principle of the linear ultrasonic motor,the output stability control and the output speed control are respectively performed.In terms of speed control,the effects of PID control and fuzzy PID control are compared by Matlab simulation analysis,and the control of the speed of linear ultrasonic motor by fuzzy PID is determined to be more excellent.(5)An experimental platform was built to test the drive system and prototype.