Nonlinear Multi-model Modeling And Adaptive Robust Control Of Two-axis Turntable

Nowadays,the high-precision turntable is widely used,especially in the application of target tracking.This paper takes the two axis turntable in the actual project as the research object.The model of the two axis turntable is established according to the characteristics of the turntable,and the controller is designed to effectively suppress the external disturbance and improve the accuracy of the turntable,which has important practical significance.First,this paper carries out the modeling of the turntable.Based on the Lagrange method,the second kind of Lagrange equation is used to establish the motion equation of the turntable.Then the classical friction model and the static and dynamic characteristics of the friction are synthetically analyzed.The nonlinear multi-model of friction is established on the basis of different velocity conditions.Finally,the servo system nonlinear multi-model with the motion specificity of the turntable and the multi-model of the friction nonlinear model is established.Then,after obtaining the nonlinear multi-model structure of the system,the multiple models are identified.For the structure of the models are known and the parameters are unknown,the identification problem is discussed.Considering the high frequency noise and other problems,the model is preprocessed and the parameters are linearized before identification.Under the different angular velocity conditions,the actual values of multi-model parameters are identified by recursive least square method,and the accuracy of the model structure and parameters is verified by comparing the simulation experiment with the actual experiment of the turntable.Then,the adaptive robust controller is designed under the nonlinear multi-model of the turntable servo system.For a multi-model,each specific model is further divided into several fixed models according to the parameter interval.In allusion to the multi-model structure,a switching strategy combining speed direct switching and performance index indirect switching is proposed.In allusion to multiple fixed models,performance index indirect switching strategy is adopted.According to the parameter selection of multiple fixed models,the adaptive rate of parameter interval change is designed.Then model parameter identifier is used to get the model parameter identification value.After Calman filtering,the adaptive estimation value of parameters and identification value under the identifier are fused,and the optimal parameter estimation is obtained.Similarly,in the design of robust controller,the parameter interval will be selected according to the parameters of the current multiple fixed models.Finally,the above contents are verified in practical application.In the hardware in the loop simulation experiment system based on x PC Target,the parameters identification experiment,model verification experiment and control effect verification experiment are carried out respectively,and the results are consistent with the theoretical analysis.