Research On UDE Control For Hysteresis Of Pzt

Because of its high control accuracy,high resolution,high driving force,low energy consumption and fast response,piezoelectric actuators are widely used in nano-positioning systems.However,they have some nonlinear characteristics such as hysteresis,creep and temperature characteristics.These nonlinear characteristics have a great impact on the output accuracy,especially the hysteresis nonlinearity,which must be taken into account in the actual control system.In this paper,the hysteresis characteristics of piezoelectric actuators are studied from three perspectives.In order to compensate the hysteresis of piezoelectric actuators,the Prandtl-Ishlinskii model is used to model the hysteresis.For the sake of compensating for the modeling error caused by the central symmetry of the classical Prandtl-Ishlinskii model,an improved Prandtl-Ishlinskii model is obtained by changing the slope of the rising and falling curve of the classical Prandtl-Ishlinskii operators.The accuracy of the improved Prandtl-Ishlinskii model is proved to be greatly improved.In addition,a direct method of obtaining the inverse model of hysteresis is proposed,which reduces the computational complexity.In order to minimize the influence of modeling error on the control effect,an UDE(Uncertainty and Disturbance Estimator)-based controller is introduced in the next chapter.The controller doesn't need the precise model,and the hysteresis can be transformed into the disturbance of a linear system,then the UDE-based controller can deal with the disturbance and other uncertainties.Experimental results show that the proposed controller is more effective than the PID controller.In the last chapter,a model-based UDE controller is applied to the piezoelectric actuator,it combines feedforward control and UDE feedback control.In the feedforward part,the improved Prandtl-Ishlinskii inverse model is adopted to compensate the system,resulting that the uncertainty of the compensated system is smaller so that the UDE-based controller can get better results.Finally,the experimental results show that the model-based UDE controller is better than PID controller and UDE feedback controller.