Research On Detection Of Dynamic Performance Of Fast Steering Mirror

With the progress of science and technology,space optical communication technology appears in people's vision,and has been paid more and more attention.At present,microwave communication is the common satellite communication method,which can not meet the needs of people.Compared with microwave communication,satellite laser communication has many advantages,and plays an important role in the field of satellite communication.Aiming,capturing and tracking technology is an important technology in the process of satellite laser communication,among which aiming technology is an important part.Aiming is divided into coarse aiming and fine aiming.In precision aiming control technology,the fast tilt mirror plays an important role as a core executive device.Piezoelectric ceramics are the driving parts of the fast tilt mirror,especially the reverse piezoelectric effect.Under the action of electric field,it will expand and expand,which will promote the angular deflection of the fast tilt mirror.Piezoelectric ceramics work in space for a long time,exposed to the harsh environment such as space,will be affected by the radiation and temperature changes in the environment,and its macro performance will gradually change,which will lead to the impact on the working state of the fast tilt mirror.In order to ensure the stability of the whole communication link and the accuracy of communication,it is necessary to detect whether the fast tilt mirror is in a healthy working state.Based on the system identification,the dynamic performance of the system can be detected.The main process of system identification is as follows: 1.Identification or test experiment;2.The selection of the model order structure;3.Parameter estimation;4.Model inspection.When the dynamic performance of the fast tilt mirror is tested,the basic steps above are also followed.The hysteresis characteristics of piezoelectric ceramics are analyzed.At present,it is an urgent problem to establish accurate expression of the relationship between input and output for the hysteresis characteristics of piezoelectric ceramics.In recent decades,researchers have put forward a large number of hysteresis models.In order to study the hysteresis characteristics of piezoelectric ceramics more scientifically,so as to detect the working state of the fast tilt mirror more accurately,it is of great significance to study the dynamic characteristics.In this paper,three different dynamic hysteresis models of piezoelectric ceramics are analyzed.The first is the generalized bouc Wen model.Based on the classical bouc Wen model,the exponential function related to the input signal frequency is introduced as relaxation operator.The model can be used to describe the relationship between the hysteresis characteristics of piezoelectric ceramics and the input signal frequency while retaining the advantages of the original model.The second is generalized P-I model,which adds initial displacement term and quadratic term to describe the nonlinear hysteresis more accurately.At the same time,the dynamic hysteresis characteristics of piezoelectric ceramics are described by studying the relationship between parameters and input signal frequency.The third is Hammerstein model,which can be regarded as the series of nonlinear static hysteresis part and linear dynamic part.The nonlinear dynamic part selects classical P-I model description,and linear dynamic part selects ARX model description.Because of the linear dynamic part,it has obvious advantages at higher frequency.Finally,the experimental data are obtained to verify the feasibility of the three models.The results show that the three models can better fit the dynamic hysteresis characteristics of piezoelectric ceramics.Finally,in order to compare the fitting effect of the three dynamic models on the dynamic hysteresis characteristics of piezoelectric ceramics,the input and output data are obtained by the same input signal in the experiment,and the parameters are identified and replaced by the model,and the model results are verified.The three models are described by introducing the error criterion of maximum error,maximum relative error and root mean square error.By comparison,Hammerstein model has the best fitting effect on the dynamic hysteresis characteristics of piezoelectric ceramics.