Research On A New Structure Of Precision Piezoelectric Linear Stepper Actuator

In recent years, with the rapid development of micro / nano technology, the traditional Precision actuators are already difficult to meet the requirements of modern precision driving. And compared to the other precision drive technology, piezoelectric actuator has much higher precision and quicker frequency response, simpler structure, etc, already applying to the technology of micro-electronics, aviation, and manufacture, micro-assemble machine, micro-robot, biomedicine and genetics engineering etc. This paper designs a precision piezoelectric linear stepper actuator according to the principle of stepper drive. The main contents are presented as follows:1. IntroductionFirstly, the research background of Precision actuator is introduced. Also, compared with other precision driving techniques and specifically analyzed the advantages and disadvantages of piezoelectric actuators; three actuation types of PZT actuators are introduced and compared. At last, it discusses the current development of PZT actuators in and abroad and the main application fields of precision actuation.2. Basic Theory of Piezoelectric MaterialsThe basic theory of piezoelectric ceramic and different kinds of piezoelectric actuator are discussed to know the piezoelectric drive better before actuator is designed, Found a solid academic foundation for designing the precision actuator. The principle of piezoelectric driving utilizes converse piezoelectric effect. The piezoelectric ceramic materials relevant parameters are mainly mechanical quality factor Qm, electromechanical coupling coefficient K, relative dielectric constantε, elastic constants S, piezoelectric constants d etc. The piezoelectric pile is the vital power element of the piezoelectric precision step actuator and the working principle is the basis to make sure that the actuator can work normally. The characteristics of the piezoelectric pile include the piezoelectricity, the capacitance trait, response trait, hysterics, dynamics trait, resolution trait, and repetition trait and so on.3. Structure Design of the Precision Piezoelectric Stepper ActuatorFirstly, describing the basic principle of stepper drive and its working process. Based on the work principle of the piezoelectric stepper actuator, studying the control process of actuator to control time- sequence relationship, and this paper designs 6 segments period wave voltage sequence, then gives a detail introduction about flexure hinge and fingers out its design principles. Makes a theory analysis of flexure hinge, and gains its stiffness equation, analyses the related factors affecting the stiffness.Then Based on the work principle of the piezoelectric stepper actuator, design the outer clamping mode structure of a precision actuator. Analyze working process and moving state of precision actuator, and does a lot of work of design on clamping part, driving part, preload part, runner and guide-way. At the same time, make analysis about dynamic model and finite model to clamping part and driving part, ensure the reliability of the structural design. Finally, change the sliding friction into rolling friction between the runner and guide-way by combinating symmetrical layout with rolling slide with stepper actuators, to improve the bearing capacity of small driving voltage.4. ExperimentsFirstly, introduces the devices used in the experiments and principle of experiment. In this paper, using the flat-form which including personal computer,LabVIEW software and data acquisition card to establish the control system of actuator. Design the three-way control voltage signal which movement of the actuator needed by using LabVIEW Software on the PC, and Analog Output by NI data acquisition card. Power amplifier and piezoelectric ceramic power amplify signals which can drive piezoelectric actuator to move.Then, testifies the prototype of the actuator, mainly about the clamping characteristics, the length of steps, solution tests, driving-speed, and the load bearing. It is proved by the test that actuator has Stable property and high resolution, especially, after applying rolling slide structure to actuator, the ability of load bearing of actuator is greatly enhanced. Stepping precision actuators main performance indicators are as follows: maximum clamping force is 4.4Kgf.the biggest step distance is 8.8μm, the resolution is 0.05μm, the fastest speed is 610μm/s, and the minimum load capacity is 480g.maximum load capacity is more than 4Kg.Finally, designed a stop positioning closed-loop feedback control system based on LabVIEW software .it is a graphical programming language and it discards the traditional version, making the program simple and visual. The design and development time of program is significantly reduced. Using the functional modules of NI-DAQmx to design this control system, this control system is simple, visual image. Doing some experimental study on control systems. It is proved that this control system can greatly enhance the positioning accuracy.5. ConclusionMakes a conclusion to the whole paper, and gives some suggestion for future development.