Study On Self-sensing 2-D Micro-positioner And Its Control Method

The integration of sensor and actuator is essential demand of MEMS and smart materials and structures.Two integration patterns are summarized which are structural integration and functional integration.Functional integration can be termed as self-sensing actuator(SSA), in which a single element simultaneously functions as a sensor and an actuator.SSA has advantages in decreasing system volume and weight ,true collocation and increasing stability.Piezoceramic actuator exhibits remarkable properties such as high resolution,quick response,big stiffness and it is widely used. The work includes the theory study and application study.Firstly, on the basis of systematic analyses of electrostrictive effect, inverse piezoelectric effect ,the displacement mechanism and displacement contribution by ferroelectric effect, the causes of hysteresis nonlineanty of piezoceramic actuators have been intensely studied from the viewpoint of rotation of ferroelectric domain and incomplete reversibility of the rotation. The hysteresis nonlineanty of piezoceramic actuators under different conditions has been studied,which provide the design basis for the hysteresis nonlineanty model.Secondly, based on the static analysis by using finite element software Pro/Mechanic, The numerical analysis on the dimensions' influence on the modal frequency, stress and the stiffness of the stage is carried by using the parametric analysis. The result shows that the rigidity and the frequency of the micro-positioner satisfy the need of its control.Finally,by using charge integrator and the capacitive non-contact displacement transducer, the principle that the displacement of the piezoceramic actuator is proportional to the electric charge of the electrode is validated.According to the the similarity of the displacement-voltage curves while driving voltage increases and decreases, a method of coordinate transformation and proportional magnification of the first displacement-voltage curve has been adopted to set up a new type of simple and applicable hysteresis nonlinearity model of piezoceramic actuator, which is used as feedforward . Based on the charge control,and by using feedforward and fuzzy control together ,the stage is drived in 2 dimensions.The resolution is 0.01μm,and the high precision and the good stability are accomplished.