| With the development of technology,especially the progress of biomedicine,aerospace,delicate electronic apparatus,the higher-level requirements of new micro-actuators are put forward,such as miniaturization,light weight,and no electromagnetic interference.Among them,due to their superiorities,for instance,fast response speed,strong output force,compact structure and strong antiinterference ability,the piezoelectric actuators show better performance among the various new micro-special actuators.Currently,there are few researches on the dynamic transfer theory modeling of piezoelectric actuators and the influence of specific stator structure parameters on motor performance at home.Therefore,the industrial application of piezoelectric actuators is limited.A piezoelectric actuator structure was designed which is based on stick-slip drive in this paper,and its dynamic transmission model also has been constructed.This study was about analyzing the performance output of piezoelectric actuator theoretically,and verified by simulation and experiment.In this paper,the piezoelectric actuator was studied through stick-slip drive mechanism,dynamic modeling and analysis,structural devise optimization,devise optimization of control system,and prototype experimental verifying.The specific research contents are as follows:(1)As for the piezoelectric actuator,the parameters affected the performance of the piezoelectric materials,including dielectric constant,piezoelectric constant and compliance constant,have been deeply studied.The influence factors of each characteristic parameter on the output of the actuator system were verified through relevant experimental analysis.Experiment results showed that the piezoelectric constant d31 has the greatest influence on the displacement output of the SMD(Surface Mounted Devices)actuator,which lays the foundation for the selection of piezoelectric ceramic materials.(2)The electromechanical coupling effect of piezoelectric ceramics,the formation mechanism of the stick-slip drive between the moving stator and the formation principle of the elliptical motion track at the end of the tuning fork were studied.It can be said that the end of the stator is moving only when the two-phase input phase difference is α=π/2.The trajectory is a standard elliptical shape,and the actuator system at this time theoretically has the largest single-step output displacement.Meanwhile,the experimental tests have verified the validity of this theory.(3)According to the design criteria of the actuator,a stator structure of a tuning-fork piezoelectric actuator was designed.Meanwhile,it was finished to select the materials of piezoelectric ceramics and metal elastic body,devise the pre-loading structure and the overall assembly of the electric actuator system.Finally,PZT-5H and QBe2 were selected as the stator materials.the modal and harmonic response has been analyzed by ANSYS 16.0,which could optimize the sensitive structural parameters,and increase the single-step maximum resonance amplitude.Meanwhile,the best longitudinal and bending resonance mode and its corresponding resonance frequency were obtained.In the interval of[0°,30°],the analysis shows that when the angle of the tuning fork is 15°,the elliptical motion trajectory of the end of the tuning fork stator is close to a perfect circle,and the comprehensive parameter performance of the piezoelectric actuator is the best at this angle.(4)In this study,based on the electromechanical coupling equivalent model of the piezoelectric composite beam,and the friction model of the contact surface between the moving stator and the LuGre model,the dynamic transmission model of the piezoelectric actuator was established.Meanwhile,the model of the output displacement and the input voltage were obtained.(5)A closed-loop control system for piezoelectric actuators was designed,which focuses on the research of PID control methods.And considering the hysteresis characteristics and speed output characteristics of piezoelectric actuators,an improved PSO-Elman neural network model was designed to identify and predict the speed of the actuator.Through simulation and comparison,it can be obtained that the model is better than the basic Elman model and the PSO-BP model in forecasting error of the actuator speed,reduced by 10.86%and 1.31%,which fully demonstrates the effectiveness of the improved PSO-Elman model in the identification and prediction of the actuator speed.(6)A piezoelectric actuator test system was designed and built,which based on the excitation frequency,voltage,pre-pressure,load and other variables on the output speed of the piezoelectric actuator prototype model research.A prototype piezoelectric actuator with a tuning fork angle of 15°was designed and manufactured,and a series of experiments on the basic performance parameters of piezoelectric actuators(step length,displacement,repeat positioning accuracy,and stability)were carried out to further verify the construction of this article.Finally,the correctness of the dynamics model was verified. |
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