Analysis Of Abnormal Data Effects And Robustness Enhancement Of Model-free Adaptive Control Method

As a typical data driven control method,model free adaptive control method is studied in this paper from the perspective of data.According to the possible problems of data in the actual industrial production process,the effects of data measurement disturbance,data transmission delay and data transmission loss on the model free adaptive control system are analyzed in detail.Aiming at the problem of abnormal data,two improved model free adaptive control schemes with enhanced robustness are proposed.The main research contents and innovations of this paper are summarized as follows.1.For a class of nonlinear discrete time systems with abnormal data,the robustness of model free adaptive control method based on compact format dynamic linearization is studied.The error convergence of the model free adaptive control method under data measurement disturbance,data transmission delay,and data transmission loss is rigorously demonstrated,and the effects of abnormal data on the control performance of the model free adaptive control system are given.The simulation results visually verify the correctness of the theoretical analysis.2.A new model free adaptive control scheme with disturbance suppression is proposed for the data measurement disturbance problem.First,based on the dynamic linearized data model of the controlled system and the statistical properties of the measurement disturbance,an improved Kalman filter based on the input and output data of the system is derived under the minimum variance estimation criterion.Then a new model free adaptive control scheme with disturbance suppression is given by embedding the improved Kalman filter into the model free adaptive control system using a modular design.The error convergence of the scheme is also rigorously demonstrated.The simulation tracking results for two types of reference signals show that the new scheme can effectively enhance the robustness of the model free adaptive control method to data measurement disturbance.3.A new model free adaptive control scheme with time delay compensation is proposed for the data transmission delay problem.First,a limit on the rate of change of the tracking error is added to the basic control input criterion function and a new weighting factor is introduced.By adjusting the new parameters,the new scheme can effectively alleviate the contradiction between the system rapidity and the amount of overshoot.Then a new model free adaptive control scheme for time delay compensation is given by using the ability of the tracking differentiator to obtain the signal derivatives to predict the system output at future moments and input to the controller in advance,and the error convergence of the scheme is rigorously demonstrated.Simulation tracking results for systems with large time delay show that the new scheme can effectively enhance the robustness of the model free adaptive control method to data transmission delay.