Structural Design And Performance Study Of Columnar Ultrasonic Motor

With the rapid development of science and technology,many emerging fields have put forward higher requirements for driving equipment.Column ultrasonic motors have a broad application prospect in biomedical,precision instruments,aerospace,robotics and other fields because of their compact structure,small size,high operating accuracy,power-off self-locking and fast response.Most of the current column ultrasonic motors are designed based on the axial bending vibration mode of the column,which decreases in amplitude as the stator height decreases,so this type of motor is mostly designed to be slender,resulting in limited space inside the motor,which is not conducive to miniaturized design.To address the above problems,this paper proposes and produces an ultrasonic motor using a bending vibration mode inside the column face to improve the internal adaptability of the motor and make it more advantageous in miniaturization.The main research contents are as follows:(1)The structure and working principle of the columnar ultrasonic motor designed in this paper are introduced,including the basic theory of piezoelectric materials and the synthesis of traveling waves on the stator end face,and the elliptical motion trajectory of the stator driving surface plasmas is derived.(2)By analyzing the vibration characteristics of the stator with different materials and structural dimensions,the materials and structural dimensions of the stator are determined.The structural dynamics analysis of the stator is carried out by the finite element method,and the operating frequency,vibration pattern and motion trajectory of the driving surface plasmas of the stator are obtained,which theoretically proves the feasibility of the motor structure.(3)Develop a test system for columnar ultrasonic motor to test the linear velocity of the motor.The test system is designed based on Lab VIEW and STM32 microprocessor.Its working principle is to collect the position signal of the motor through the laser displacement sensor.The STM32 microprocessor controls the analog-to-digital conversion module to collect the output signal of the sensor and send it to the upper computer through the serial communication module.The upper computer program based on Lab VIEW receives,processes,displays and saves the data.(4)Test the experimental prototype,conduct impedance characteristics experiments on the prototype,and obtain the resonant frequency of the prototype.The mechanical characteristics test platform of the prototype was built using the test system,signal generator,power amplifier,DC power supply and other instruments and equipment,and the output characteristics of the prototype were studied experimentally.The experimental results show that the maximum output force reaches 1.2 N at an excitation voltage of 130 V and a frequency of 79.4 k Hz.Finally,the motor structure is optimized and the effect of different recess heights on the stator vibration characteristics is studied by setting a recess in the middle of the stator threaded hole.The calculation results show that increasing the height of the groove leads to a decrease in the structural stiffness of the stator and an increase in the amplitude.The optimized experimental prototype was fabricated,and the experiments showed that the load capacity of the optimized prototype was increased by 16.7% compared with that before the optimization.