Research On Active Disturbance Rejection Control Technique Of APT System In Space Optical Communication

The APT system of optical communication has the advantages of high accuracy,large capacity,high speed,strong concealment,etc.As a research hotspot,it is widely used in the field of communication.Due to the complex operating environment and the high accuracy of the link stability of the APT system,the study of its control strategy becomes the key to improving the performance of the APT system.The APT system bandwidth of the traditional control method is severely restricted by its own resonant frequency at high frequency bands,and the anti-interference performance is poor.Moreover,when the environment of the controlled object changes,the gain of the controller needs to be frequently adjusted,which seriously hinders the improvement of the performance of the APT system.To solve these problems,this paper applies the active disturbance rejection controller to the APT system fine tracking loop to increase the system bandwidth,enhance the system robustness and improve the system control accuracy.This paper firstly establishes the mathematical model of APT system,analyzes the bandwidth relationship of the coarse precision tracking loop of APT system and concludes that the high-band system bandwidth mainly depends on the conclusion of the fine tracking loop bandwidth.Secondly,in order to solve the problem of bandwidth limitation of APT system,a linear active disturbance rejection controller is designed to apply to the precision tracking loop.After completing the parameter tuning,the controller has increased the loop bandwidth and improved the performance of APT system.Through simulation experiments,when the input signal is within 50 Hz,the control accuracy of APT system up to 5.20?rad at 350 Hz bandwidth.In order to further improve the system response speed and control accuracy,the paper designs the nonlinear tracking active disturbance rejection controller on the precision tracking loop of APT system,and uses the separation method to complete the parameter tuning of each component of the controller.The simulation results show that on the premise of response speed and high robustness of the APT system,the control accuracy has been further improved compared with the linear auto disturbance rejection controller.For the problem of mixed signal noise,it is proposed to use the tracking differentiator added with the prediction function as an improved method to preprocess the output noise.Simulation results show that the improved APT system tracking accuracy is 4.13 ?rad.The innovation of this paper are applying the active disturbance rejection controller to the APT system fine tracking loop to improve the system bandwidth and control accuracy and using the tracking differentiator added with the prediction function to filter the output signal of the precision tracking loop to improve the observation of the extended state observer in order to further enhance the performance of APT system.