Research On The New Style Inertial Rotary Actuator Driven By Piezoelectric Bimorphs

Piezoelectric inertial actuator has many characteristics such as compact configuration, good response characteristic, non-electromagnetism interference, convenient control. It's often applied on the occasion of high resolution and large displacement, and has attracted widely attention. Especially in recent years as the performance of piezoelectric element being improved, its applications are gradually becoming wider and wider.This article proposes changing friction moment method between the driving mechanism and the contact surface through the way of changing the friction coefficient between them, and cooperate with the inertial driving moment to form the research plan of new style inertial rotary actuator driven by piezoelectric bimorphs.Analyzed the working principle of the actuator, designed and fabricated new inertia driving mechanism that had been possible to realize precise rotary movement, and has made the related performance test.Simultaneously in order to enhance the moving performence of the new inertia driving mechanism, we designed a set of close-loop step control system. Main contents are as follows:1. The research and development of the piezoelectric inertial actuatorDriven by piezoelectric materials has great advantages over other kinds of drivng ways, such as small volume, high movement precision, rapid response, low ullage, easy to control. Piezoelectric actuators are devided into there kinds.The inertial drive actuator plays an important role in this field as a result of its particular characteristic.At present, the piezoelectric inertial actuators are applied in various fields.Introducing the development of this field all over the world. The paper presents a new style inertial actuator driven by symmetry waveform voltage and has great research value and will be a new kind of MEMS.2. Basic theory oF piezoelectric actuationThe piezoelectric actuation principle and the correlative basic theory is the theoretical start of analyzing piezoelectric multilayered actuator. So it is necessary to expatiate the basic theory of piezoelectric actuation. Piezoelectric actuation main makes use of the converse piezoelectric effect.The basic physical properties and main performance parameters are discussed. Piezoelectric material is a elastomer, it has four piezoelectric equations with different independent variable at various boundary conditions.The paper introduces respectively the performance the piezoelectric stack and piezoelectric bimorph. Piezoelectric bimorph has the advantages of large distortion,easy to link other object,cheap etc. Piezoelectric bimorph adopt the LE mode of piezoelectric oscillator which is the main mode when the piezoelectric oscillator is bending.The piezoelectric cantilever suits for producing the inertial impact force. These basic theories are the foundation for structural design and performance analyse of the inertial actuator.3. Research on the performance of the piezoelectric cantileverAs the driving element of the actuator,the performance of the piezoelectric cantilever is very important to the movement performance of the actuator.Through the way of theory research and testing,analysed the relationship between the parameters of the bimorph and the displacement in the end of the piezoelectric cantilever and the stiffness. Build the vibration equations.Test the change curves of the displacement in the end of the cantilever with the voltage and the frequency of the driving signal.The results: the displacement in the end of the piezoelectric cantilever increases with increasing of the voltage,while vibrated with the increasing of the frequency.The resonate frequency of the piezoelectric cantilever is 40Hz,and its response waveform to the saltation voltage is similar with the system which is composed of the mass,the stifnesse vibration equations.Test the change curves of the displacement in the end of the cantilever with the voltage and the frequency of the driving signal.The results: the displacement in the end of the piezoelectric cantilever increases with increasing of the voltage,while vibrated with the increasing of the frequency.The resonate frequency of the piezoelectric cantilever is 40Hz,and its response waveform to the saltation voltage is similar with the response when the saltation force operated on the system composed of the mass,the spring and the damp.The rectangle voltage signal can make the piezoelectric cantilever produce greater impact force.4. Inertial actuator principle and structure designAnalyse the moving principle of inertial actuator,propose to control friction moment between inertial actuator and the contact surface, with the cooperation of the inertial driving moment to form the research plan of new style inertial rotary actuator drived by piezoelectric bimorphs.The fast libration of the piezoelectric cantilever can form the driving moment.At the effect of the four special driving"feet",the friction moment in one direction is different from that of the other direction.Design the new style inertial actuator and make some research on its movement condition. It makes a conclusion that if the driving moment is more powerful than the friction moment,the actuator can rotate in the set direction.5. Testing research on inertial actuatorAccording to the driving principle of new style rotary actuator,design and manufacture a rotary actuator, build the testing system based on the character of the actuator. Test the relationship among the rotary velocity, rotary step size, load ability with the voltage and frequency of the driving signal. The result: the maximum rotary speed of the actuator is 0.01723rad/s,the minimum step is 3.28μrad, the largest moving range is 1800 and its carrying capacity is more than 500g. The results show that the actuator has good moving performance.6. Research on the step control system based on LabVIEWIntroduce briefly three kinds of control system, and choose the control system which uses the LabVIEW virtual instrument software and the NI data acquisition card. LabVIEW uses the graph language to carry on the programming, which makes the procedure development simple,direct-viewing,efficient. Use some function modules in LabVIEW and edit the step control system. Having done some test research on the control system.The results:when the actuated voltage is 17V,the frequency is 1Hz,the syep fluctuation of the actuator can fall from 0.1282 to 0.08155 at the situation of using the steo control system.The results show that the step control system can greatly enhance the moving step stability of the inertial actuator. Analyze the disadvantages of the system and present the improving direction with the help of PID.7. ConclusionGive the main conclusions obtained in this paper and the prospect for further research.