Study On Hysteresis Compensation And Control Method Of Piezoelectric Ceramic Actuator

With the development of communication technology,satellite laser communication has become a hot topic in various countries.Fast steering mirror is used as the optical path adjustment unit to adjust the beam angle through continuous deflection movement,so as to achieve smooth links.Because the communication distance between the satellite and the earth or between the satellite and the satellite is so far that the so-called " a miss makes great difference ".In order to achieve precise motion of the fast steering mirror,its motion actuator is the key.The piezoelectric ceramic actuator has the advantages of fast response,high resolution,small size,no heating and no friction,etc.It is an ideal actuator.However,due to the inherent nonlinear hysteresis and creep characteristics of piezoelectric ceramics,the positioning accuracy of the system will be reduced,the system will oscillate and the system will be unstable.In addition,due to the hysteresis non-linearity of piezoelectric ceramics,the existing mathematical models are difficult to accurately describe this complex motion behavior,which is beneficial to piezoelectric ceramics.Actuator modeling and system controller design pose some challenges.In order to solve these problems,this paper will take piezoelectric ceramic actuator as the research object,and make a thorough and systematic study on the modeling of non-linear hysteresis and creep and compensation control methods.Firstly,in order to describe the hysteresis behavior of piezoelectric ceramic actuators,a piecewise analytical model based on Prandtl-Ishlinskii model is proposed,which can only describe the static symmetric hysteresis and frequency-independent.The integral terms in the traditional model are eliminated,and the hysteresis behavior is divided into two parts: the rising and the falling segments.The motion characteristics of hysteresis are modeled and analyzed.Finally,the operator-class model is transformed into a piecewise n-order polynomial analytical model,and the method to determine the order of the model is given.According to the choice of the order of the rising and falling segments,the static symmetric hysteresis and the asymmetric hysteresis can be described respectively.In order to describe the frequency-dependent dynamic hysteresis characteristics,the frequency term is introduced into the model coefficients to obtain the dynamic hysteresis model,and the relationship between the coefficients and frequencies is determined.Experiments show that the proposed dynamic and static model has the advantages of simple structure,fewer parameters and low computational complexity,and it is easier to implement in engineering.Secondly,in order to improve the hysteresis linearity of piezoelectric ceramic actuators.Based on the proposed dynamic and static model,a simple and effective direct inverse compensation method is proposed,and an open loop feed forward inverse compensation controller is designed.In order to improve the accuracy of inverse compensation,a control method of local correction is proposed for the deviation of local compensation points.In order to improve the efficiency of model parameter identification,an "adjustable forgetting factor" is designed.The forgetting factor is coupled with the weight factor to form an adjustable forgetting factor,which can ensure the tracking ability of the algorithm and effectively reduce the fluctuation of the parameters.In order to solve the problem of parameter fluctuation,a parameter switching controller is designed to control the parameter identification rate through sensitivity factor.The experimental results show that the linearity can be improved by an order of magnitude by open loop feed forward inverse compensation.Thirdly,Based on the mechanical and electrical characteristics of the piezoelectric ceramic drive system,the integrated dynamic model of the piezoelectric platform system is presented.In order to further improve the positioning accuracy of piezoelectric actuator,an adaptive sliding mode feedback controller is introduced to form a closed-loop composite control method on the basis of feedforward and inverse compensation to reduce the residual error of inverse compensation,unknown disturbance and parameter uncertainty.The influence of these factors on the system.At the same time,in order to estimate and compensate disturbance,disturbance state observer is designed.In order to solve the chattering problem during sliding mode change and avoid the continuous growth of estimation value in self-adaptive law,hyperbolic tangent function and projection algorithm are introduced to improve the control law.At the same time,in order to solve the signal differentiation problem in sliding mode control process,the design is carried out.A fast tracking differential controller is proposed.Finally,the effectiveness of the composite control method is verified.Finally,the method proposed in this paper is applied to the fast tilting mirror system.A fast tilting mirror experimental platform was designed,and static positioning and dynamic scanning experiments were carried out for the fast tilting mirror system respectively.A creep two-stage fitting method was proposed to predict and compensate the creep phenomena during the static positioning process,and the spiral-sinusoidal scanning strategy was used to track the creep dynamically.The experimental results show that the proposed method is feasible and effective in controlling the precise motion of the fast tilting mirror.