Research On Active Disturbance Rejection Preassigned Finite Time Control For Several Kinds Of Nonlinear Systems

In practical control systems,strict feedback and pure feedback nonlinear systems are two kinds of common systems.This paper studies the tracking control problem of these two kinds of systems.At the same time,because the actual system needs to use the communication network to exchange information between sensors,controllers and actuators,and the network bandwidth is limited,there are often network problems such as transmission delay,data packet loss,etc.In this paper,quantization and event trigger mechanisms are used to improve the signal transmission quality and reduce the waste of communication resources by reducing the transmission frequency of signals.The reduction of signal transmission frequency will reduce the signal accuracy,and then the system performance will decline.In this paper,a new preassigned performance control method is adopted to improve the transient-state performance and steady-state performance of the system.The main contents and innovations are as follows:1.The problem of event-triggered active disturbance rejection control(ADRC)preassigned finite time tracking control is studied for a class of strict feedback nonlinear systems.Based on the Backstepping method,ADRC technology,preassigned performance and finite time control method,an event-triggered preassigned performance finite time control strategy with ADRC is proposed.In the recursive design of each step,an extended state observer in ADRC is used to estimate the unknown items in the system,and a tracking differentiator is used to estimate the derivative of the virtual control to avoid differential expansion.The designed event-triggered preassigned performance finite time controller can ensure that the tracking error of the system converges to a preassigned small neighborhood near an equilibrium point within a given finite time,and all the signals in the closed-loop system are bounded.Using the event trigger mechanism makes the control input no longer continuously updated,thus the communication resources are saved.The simulation results verify the effectiveness of the proposed method.2.The preassigned finite time quantized tracking control problem with active disturbance rejection is investigated for a class of non-affine pure feedback nonlinear systems with quantized input in this paper.Based on the Backstepping method,and combining active disturbance rejection control(ADRC)technique,preassigned performance control with finite time control method,a preassigned performance finite time quantized control scheme by means of ADRC technique is proposed.In each step of the controller design,the extended state observer in ADRC is used to estimate the unknown function items in the system,and the tracking differentiator is used to estimate the derivative of the virtual control in order to avoid differential expansion.The proposed preassigned performance finite time quantization controller can ensure that the tracking error of the system converges to a predetermined small neighborhood of the equilibrium point within an arbitrarily given settling time,and all signals in the closed-loop system are bounded.Because ADRC technique is adopted,this control scheme has better anti-interference ability.In order to verify this advantage,a neural preassigned finite time quantized controller using RBF neural network to approach unknown functions is designed as well in this paper.And the two control methods are compared together,the simulation results verify the effectiveness and superiority of the proposed method.