Research On The PZT Adaptive Control System Based On Fiber Grating

Series of PZT piezoelectric ceramics are widely used in many aspects of people's life. There are so many kind of manufacturing equipment which is based on piezoelectric ceramic. Including high voltage ignition detonated device, pressure gauge, piezoelectric micro-displacement actuator, piezoelectric transformer, etc. Although piezoelectric ceramics has decades of research history, but the research about developing new type of piezoelectric materials and the method to control them has never stopped.There has been many mathematical model of the inverse piezoelectric effect of piezoelectric ceramics, such as PI model, Duhem model, etc. These models are very effective when the frequency of the voltage signal which is driven the piezoelectric ceramics is low, but when it is high, the model error will be much higher, and when the PZT is driven by a high frequency signal, the traditional capacitance or inductance based deformation measurement device can't get the amplitude of the PZT. For this kind of problem, this paper uses measurement system which is based on FGB to measure the amplitude of the PZT piezoelectric ceramic which is driven by the high frequency ac voltage signal, and builds the mathematic model to describe the relationship between fixed frequency voltage input and PZT output amplitude. Then select the appropriate adaptive control algorithm, which can achieve the precise control of PZT output amplitude at different load conditions. Specific research works are as follows:(1)Research on the measurement principle of fiber Bragg grating sensor. Get the PZT vibration amplitude through the change of the wavelength in the fiber grating, and the change of the wavelength in the fiber grating is get through the optical fiber grating sensor which is fixed in the PZT deformation measurement device and high-speed optical fiber grating demodulation instrument. Through the relationship between the changes of the length of the fiber grating sensor and the changes of the reflection light wavelength in fiber Bragg grating sensor we can get the PZT mechanical vibration amplitude.(2)Analyzing the existing problems of the models when they are used to describe PZT which is driven by the ac voltage signal. Studying the relationship between the output PZT mechanical vibration amplitude and fixed frequency ac signal input, and builds the appropriate mathematic model about them. Then using the experimental data that fiber Bragg grating strain measuring system gives and the forgetting factor recursive extended least square method to calculate the parameters of PZT vibration model.(3)Designed the adaptive control system, which is based on the mathematical model of output PZT mechanical vibration amplitude and the GMVC algorithm. The method of calculating the scope of the control weight value based on overshoot and risetime. And make the adaptive system can complete the control of the PZT amplitude by adjusting the amplitude of the fixed frequency ac drive signal amplitude, while the load condition of PZT has changed. Then designed the test to verify that the adaptive control system can control the output amplitude of PZT precisely when there are unknown changes in the load of PZT.