Design And Application Research Of Improved Active Disturbance Rejection Controller

Based on the binary design idea of disturbance information,active disturbance rejection control(ADRC)technology overcomes the defects of proportional integral differential(PID)control technology,and has excellent performance such as high disturbance resistance and good robustness.At present,it has been widely used in servo system,power system and other fields,with remarkable achievements.The research on linear ADRC(LADRC)technology is becoming more and more mature,while the research on nonlinear ADRC(NADRC)technology still needs to be further improved and promoted.Therefore,in this thesis,the hyperbolic-tangent-like function(atanh)and high-order sliding mode technology are adopted to improve NADRC,and particle swarm optimization(PSO)algorithm is combined to adjust the controller parameters,thus completing the design of the improved ADRC.At the same time,the effectiveness of the algorithm is verified by taking the stabilized platform system as the controlled object.The main research work is as follows:(1)The basic structure and related theories of ADRC method are introduced.Meanwhile,the main functions of the controller modules and the influence of compensation factors on the control system are analyzed.(2)Without increasing the complexity of controller structure,NADRC is improved from two aspects.Firstly,aiming at the problem that the original fal function is easy to produce output jitter at the switching point,the atanh function with better smoothness is introduced to replace the fal function.Based on this,the state error feedback control law is designed and the stability is proved.Secondly,in order to further improve the observation accuracy of the system,the high-order sliding mode technology with finite time convergence is adopted to design the observer,and terminal attractor function is introduced to modify the original symbol function,so as to make the observation results smoother.In addition,a variable-gain high-order sliding mode observer based on atanh function is designed in order to solve the differential peak phenomenon.(3)PSO algorithm is used to optimize the system design to solve the problem of too many the controller parameters.Firstly,the basic flow of the algorithm is briefly introduced,and then the parameters to be set are selected by analyzing the controller,and finally the relevant fitness function is designed according to the system characteristics.(4)In order to verify the effectiveness of the algorithm in this paper,the two-input and two-output two axis stabilized platform system is selected as the controlled object,and the dynamic model,friction model and control motor model of the system are established.With the help of the controller designed by using the algorithm in this thesis,the uncertainties inside the system,friction disturbance and other external disturbances are lumped together to estimate and compensate,and the original complex system is simplified as parallel system for easy control.Compared with PID and the traditional ADRC,the improved active disturbance rejection controller has the advantages of good disturbance rejection,high accuracy of error convergence and other characteristics.