Research On The Performance Of Piezoelectric Actuator Based On D₃₁ Mode And D₃₃ Mode

Piezoelectric actuator is a new type of micro-motor,which converts the input electric energy into the vibration energy of the stator through the inverse piezoelectric effect of piezoelectric ceramics,and then transmits the vibration energy to the rotor through friction to drive the rotor to move.Compared with traditional electromagnetic motors,piezoelectric actuators have the advantages of low speed and large torque,no electromagnetic interference,high integration,high control accuracy,and self-locking after power failure.Piezoelectric actuators can be divided into d31 vibration mode and d33 vibration mode according to different driving principles.Piezoelectric actuators based on the d31 vibration mode are mature and widely used,but their structure is relatively complex and requires complex external devices to apply pre-pressure.Piezoelectric actuators based on the d33 vibration mode are divided into resonant and non-resonant types according to the excitation mode.The resonant type needs to adjust the resonant frequencies of several vibration modes in the driver to the same,which results in complicated design of this type of driver and high manufacturing cost.The non-resonant type has a relatively small stroke and slow speed due to the stacked piezoelectric ceramics and structural limitations,and the clamping force is limited by the stacked piezoelectric ceramics.Compared with the resonant type,the non-resonant type has a lower frequency and a slower speed,but it has a large driving force,higher positioning accuracy,simple design and manufacture,and simple control system.Regarding the lack of piezoelectric actuators based on d31 vibration mode and non-resonant piezoelectric actuators based on d33 vibration mode,this article proposes two types of piezoelectric actuators to improve the above problems,and compares two piezoelectric actuators with different principles;a new type of contact-friction model is proposed to analyze the friction force distribution of the contact surface of the spherical multi-degree-of-freedom ultrasonic motor under different driving and load conditions.The main work of this paper is as follows:For the spherical multi-degree-of-freedom ultrasonic motor,the structure of each part of the motor is introduced in detail,the design and working principle of the pre-pressure regulating structure are analyzed,the principle of the stator drive and the principle of multi-degree-of-freedom operation are theoretically analyzed,modal analysis and transient analysis are carried out by finite element method,extract the resonant frequency,mode shape and transient trajectory of the circular traveling wave stator to verify the rationality of the stator and motor design.A new dynamic non-linear contact-friction model that takes into account the non-linearity of the frictional force distribution and the friction factor is proposed.The normal pressure of the contact layer is calculated by elastic mechanics,and the dynamic driving model of the spherical multi-degree-of-freedom ultrasonic motor is analyzed,establish a friction model based on Mindlin theory and Hertz contact theory to analyze the friction situation,and analyze the friction state of the spherical multi-degree-of-freedom ultrasonic motor under different motion and load conditions.For the piezoelectric actuator based on the secondary flexure hinge structure,the structure and size are introduced in detail,and the working principle is analyzed theoretically,by comparing with other stick-slip actuators,theoretical analysis of the superiority of structural improvement is carried out,perform static simulation to analyze the deformation,structural stress and displacement of the slide rail of the piezoelectric actuator.Finally,prototype the spherical multi-degree-of-freedom ultrasonic motor,design and build an experimental platform,introduce the composition and operation process of the experimental platform in detail,and test its resonance frequency and output performance,substitute the rotational speed,spatial attitude data and motor related parameters of the spherical multi-degree-of-freedom ultrasonic motor under different motion and load states into the contact friction model,the friction force distribution diagram is calculated and drawn by MATLAB.Prototype the piezoelectric actuator based on the secondary flexure hinge structure,the experimental platform was built,and the components,installation methods and operation processes used in each part of the experimental platform were introduced in detail,test the relationship between frequency,voltage and slide rail speed,slide rail motion trajectory and piezoelectric actuator load performance through experiments.Compare the advantages of two piezoelectric actuators with different principle.