Fundamental Research And Application Of Piezoelectric Fiber Micro-actuator

This project is about the basic research and application of piezoelectric fiber micro actuator, including the issue about larger volume, low accuracy and the lack of complete sets of manufacturing technology suitable for industrialization in regard to piezoelectric fiber micro actuator at present. Firstly, this article makes a simple analysis of (K0.5Na0.5)1-3xEuxNb03 (KNN) ceramics mixed europium; Secondly, it introduces KNN1Eu lead-free piezoelectric fiber and preparation technology and processing of 1-3 piezoelectric fiber composites, and has made the brief analysis of them; Then it conducts a research about orthotropic piezoelectric fiber composites (OPFC) sensing/driving element on the basis of the analysis of piezoelectric fiber composite material characteristics and processing technology; Finally, it designs micro 6-DOF parallel platform according to the previous research work, and makes a research on the control system of six degrees of freedom parallel mechanism. The research of this project has an economic and social significance to our country’s movement platform drive technology and engineering structural damage monitoring technology, and improves the level of the intelligent materials and devices in our country.The paper’s detailed research work and achievements are as follows:(1) The paper introduces a europium doped KNN ceramics with the method of conventional solid phase reaction, and studies the relationship between microstructure, dielectric and ferroelectric performance. Obtained by experimental analysis:①With the increasing amount of europium-doped, X-ray diffraction peak appears broadened, and has pressure inequalities, and grains gradually refine;② When europium doping reaches 3% in the high temperature area, the wide range of dielectric constant has good temperature stability, and the doping of rare earth element europium can effectively improve the piezoelectric properties.③ The preparation of KNNlEu lead-free piezoelectric fiber was adopted by the method of plastic polymer, and the 1-3 piezoelectric fiber composites was prepared by the improved permutation-casting. Using the uniform field and microscopic mechanics theories, the author sets up electric model. Relying on the constitutive relations of piezoelectric and two polymer phases, the author deduces characteristic element for electrical parameters.The emergence of europium doped lead-free piezoelectric ceramic KNN, on the one hand effectively improves the piezoelectric properties of the material, and on the other hand applies piezoelectric fiber micro drive to piezoelectric micro actuator.1-3 type of micro/nano piezoelectric fiber composite materials has good performance of orthotropic and sensing/drive, and it can be seen that the orthotropic properties in AE structure damage detection and micro drive have a very broad application prospect.(2) On the basis of summarizing the analysis Piezoelectric Fiber Composites characteristics and production process, the author does the following works:①Theory model of OPFC (orthotropic piezoelectric fiber composites) drive/sensor is established.②Different size OPFC drives/sensors are made and introduced in detail from its manufacture craft, driving performance device construction and driving performance experiment and so on. Driving performance simulation and experiment test, such as orthotropic and sensitivity, have been completed, and the corresponding improvement measures have been put forward.③OPFC drive/sensor model is established with the use of the finite element simulation software COMSOL, and the finite element analysis is completed from the geometric size of piezoelectric fiber composite materials, components of piezoelectric polymer faces features and two-phase material parameter etc. At the same time the author explores a more mature technology of design, development, manufacture of this kind of sensor, which provides theoretical guidance for designing OPFC drive/sensor, selection of piezoelectric and polymer phase materials, and provides quality function components for the engineering structure testing and micro drive platform.(3) A lead-free piezoelectric ceramics is first proposed to preparation of new materials into OPFC piezoelectric fibers as the driving source applied to research and development of six degree of freedom micro parallel motion platform. The accuracy of the motion platform can reach nanometer scale level, and has many characteristics such as good orthotropic, small stroke and easy to control etc; A three-dimensional solid modeling of 6-DOF micro parallel platform has been done. Then the author uses software to analyze the kinematics simulation of micro parallel platform speed, acceleration, hinge Angle change and so on, to get the kinematics characteristic of the joints in the platform runtime and the driving force of the joints, which provides important theoretical basis for the following control system design; Piezoelectric fiber micro drive is applied to micro parallel platform, and deputy actual movement of an elastic hinge is replaced. By the elastic deformation of flexible hinges, the terminal platform movement can be achieved, which eliminates the mechanical friction and clearance friction, and improves the precision of the organization.(4) Finally, for micro platform, the author puts forward the overall composition program of micro platform control system, and carries out the hardware design of the control system in detail. In this paper, combined with PID Control engineering frequently used, with the use of adaptive laws to revise three key parameters of PID control, micro drive experiment platform of piezoelectric closed loop controller based on DFNN feed forward controller and PID is designed. Experimental results show that the controller greatly improves the static and dynamic properties of the micro-drive platform, and the accuracy of the position control. From the experimental results, the output displacement of piezoelectric micro-drive platform reach 10μm, and time is 0.05s; Displacement overshoot volume is very small, and the steady-state error is 0, and the controller on the static and dynamic performance of the moving platform has greatly improved; When the input signal is sine signal, the maximum tracking error is 0.21 μm, which improves the accuracy of the position control.