Research On Auto-Coupling PID Cooperative Control Strategy For Unknown MIMO Nonlinear System

The controlled objects such as permanent magnet synchronous motor,aircraft and mechanical arm are all multi-input multi-output(MIMO)nonlinear systems,due to their complex characteristics including nonlinear characteristics,time-varying characteristics of parameters and multi-variable coupling characteristics,it is difficult to achieve the desired control effect with all kinds of existing control methods.Aiming at the control problem of unknown MIMO nonlinear system,a cooperative control method of auto-coupling PID(ACPID)based on adaptive speed factor is studied in this paper.This control method not only inherits the classical control theory essence of PID control,sliding mode control and auto disturbance rejection control to eliminate the error by error,but also eliminates the problem of poor robustness of PID gain,the problem of natural high frequency chattering of sliding mode control and the problem of large amount of calculation of auto disturbance rejection control.Referring to the definition of "summation disturbance" of auto disturbance rejection control,Is defined as the system all the unknown complicated factors combined disturbance(expanded state),and arbitrary complicated nonlinear system is mapped to the unknown linear system,and form a reverse excitation,disturbances in the combined control error of the system,using a speed has nothing to do with the controlled object model factor will be proportional,integral and differential three links tightly coupled together,so as to realize a different function and goals of coordinated control system,and respectively analyzed in time domain and frequency domain ACPID coordinated control system of the global robust stability and resistance to disturbance robustness,expected the research results have been achieved,formed the obvious characteristic and innovation:1)The unknown internal dynamics and external uncertainties are defined as summation perturbations,and the unknown MIMO nonlinear system is mapped to the unknown MIMO linear system,the concepts of system classification such as linear and nonlinear,coupled and uncoupled,affine and non-affine,time varying and time invariance are weakened.2)According to the controlled system from the dynamic process in the process of steady state transition time to set the minimum speed factor,makes ACPID model and controller gain setting rules related to the speed factor only and has nothing to do with the model of the controlled system,not only effectively solve the problem according to different objects of the corresponding control method,but also effectively solves the problem of PID gain setting.3)In order to avoid overshoot and oscillation due to integral saturation in the dynamic process of the control system,an adaptive speed factor model varying with the rate of error change is designed to effectively solve the contradiction between speediness and overshoot.In order to verify the effectiveness of the research method in this paper,the ACPID,ACPD and ACPI control methods based on the adaptive speed factor are applied to the unknown MIMO nonlinear system,the unknown MIMO nonlinear non-affine system and the unknown MIMO nonlinear time-varying system,respectively.The experimental results based on MATLAB/Simulink simulation platform show that the control method presented in this paper does not depend on the mathematical model of the controlled object,it has a simple structure,small in calculation,high in control accuracy,fast in response,and has good anti-disturbance robustness.It has a broad application prospect in the field of industrial control.