Research On Inertial Piezoelectric Actuator With Changeable Pressure

With the development of science and technology, micro-precision actuator isneeded in many technical fields. Piezoelectric cell have a biggish advantage inachieving high precision, fast response and large displacement precision actuatingbecause of its characteristics such as little volume, quick speed of response, highenergy conversion efficiency and higher displacement resolution etc.After analyzing recent researching status of piezoelectric actuator, a newmethod to construct inertial impact precision piezoelectric actuator driven bypiezoelectric bimorphs is proposed. In this method, the actuator is able to realizedirectional movement due to the orderly changing of friction controlled by pressurebetween mechanism and support. Based on this principle, a linear inertial impactpiezoelectric actuator prototype and a circumrotatory inertial impact piezoelectricactuator prototype are made after designing, then testing is performed in this paper.The paper consists of five chapters, given as follows:1. IntroductionThe main applications of micro-precision actuator, the purpose andsignificance of the subject are introduced. It conclude that piezoelectric drivingmode has large advantage over other mode in the precise drive field afterintroducing the main types of precise drive and analyzing the characteristic of somekind of common drive types. Then the kinds of piezoelectric actuator are related. Areview about the history and recent studying status of piezoelectric inertial impactactuator in domestic and international is given, at the same time ,relate theirscharacteristics and working principle. At last, the main research contents of thepaper are list. 2. Basic theory of piezoelectric componentThis chapter introduces the basic theories of piezoelectricity as well aspiezoelectric phenomena,ceramic, equations and piezoelectric vibrator. Thepiezoelectric effect and converse piezoelectric effect are the fundamental ofpiezoelectric drive. The piezoelectric ceramic is one of piezoelectric material whichin common use. The factors influence performance include dielectric constant ε,elastic constant s , piezoelectric constant d , electromechanically coupledcoefficients K,mechanical quality factor Qm, etc. Piezoelectric material is aelastomer, it has four piezoelectric equations with different independent variable atvarious boundary conditions.In general, piezoelectric material fixed with some elasticity material to formthe vibrating body, and it is called the complex piezoelectric vibrator. ThePiezoelectric bimorph vibrator is made of piezoelectric ceramic part and metal part.Piezoelectric bimorph adopt the LE mode of piezoelectric oscillator and is apiezoelectric component with large deformation output, easy-to-control, higherresponse rapid which suits for the inertial impact precise drive. The paperintroduces the structural style and the performance parameter of piezoelectricbimorph, its performance parameter is the main basis to design the piezoelectricvibrator.3. The driving principle and structure design of inertial impact actuatorAfter analyzing the principle of present inertial impact precision piezoelectricactuator, the new inertia driving method with friction changing is advanced in thispaper. The structural style of friction changing actuator driven by piezoelectricbimorphs is related. The moving principle and characteristic of actuator areanalyzed. In this paper, the piezoelectric bimorph are analyzed by FEM method, inwhich, parameters of piezoelectric bimorphs are changed in order to know how thedeformation and natural frequency of piezoelectric bimorphs are influenced. Aim atanalyzing the selected piezoelectric bimorphs, static and dynamic analysisincluding the theory modeling and the experiment test is carried out. From thisanalysis, some important characteristics of piezoelectric bimorphs are obtained andthese provide a reliable theoretic fundamental for next research. At last , advicesabout how to design the base,connecting part of the actuator and orientedmechanism are given.4. Experiments of the inertial actuator with changeable pressureAfter designing an experiment system to test the piezoelectric actuator, thepaper introduces the testing method and the testing results. Main contentssummarize as follows:1. The prototype of actuator is made and the testing system is built base on the characterof actuator.2. Testing the deformation of piezoelectric bimorphs in order to select suitablepower signal for piezoelectric actuator.3. Some experiments are implemented for piezoelectric actuator to demonstrateits kinematical characteristics. Base on experimental results , how the velocity, stepsize and load ability of actuator are affected by driving voltage and frequency areanalyzed. According to these results, the control method is provided:select suitableworking frequency, uses adjusting driving voltage amplitude way to realizevelocity and step size adjustment.The experiment results show that the actuators have the required performance.The linear actuator can work with minimum stable step of 0.7μm, maximummoving velocity ≥1mm/s, loading capacity of 150g as frequency of 10Hz. Thecircumrotatory actuator is able to realize 180°rotating.5. Conclusion and expectationThe chapter gives the main conclusion obtained in this paper and the prospectfor next research.