Fault Detection And Decentralized Control For Nonlinear Interconnected Systems

With the continuous development of control science and the continuous improvement of industrial level,the control system is gradually transformed from a single system to a complex multi-dimensional interconnected system.The traditional centralized control mode can only be used to control structure is relatively simple interconnected system,for the structure more complex high-dimensional nonlinear interconnected system control effect is not so ideal,so decentralized control mode arises at the historic moment,dividing an interconnected system into multiple subsystems,independent of the controller was designed for each subsystem.Due to the large scale of interconnected system,information exchange between subsystems,coupled with external disturbances and other irresistible factors,interconnected system is prone to failure,so it is necessary to study a fault detection and decentralized control mode of interconnected system.This paper takes the nonlinear interconnected system as the research object,designs the communication protocol for the information exchange between subsystems,reduces the communication between subsystems,and designs the fault detection scheme based on this.By analyzing the system structure,decentralized fault-tolerant control method and decentralized state feedback control method are designed respectively.The research contents of this paper mainly include the following aspects:1.A communication protocol based on subsystems for nonlinear interconnected systems is proposed.Subsystems are connected with each other through interconnection functions.When the state of one subsystem changes,it will affect the state of other subsystems through interconnection functions.Therefore,this paper designs a communication protocol based on subsystems.When the error between the state of the subsystem and the expected state exceeds the set threshold,the system will transfer its state to other subsystems through the interconnection function,which reduces the communication between subsystems.2.In view of the nonlinear interconnected system we design a decentralized fault detection scheme.Based on the subsystem communication protocol,the estimator model is established for each subsystem,and the estimation error model is established.The upper bound of the estimation error when there is no fault is derived.When the estimation error exceeds the upper bound,the fault of the system is proved.3.In view of the nonlinear interconnected system we design a decentralized fault tolerant control scheme,using neural network approximation of the unknown interconnection function and external disturbance,combined with the adaptive boundary in the adaptive control method to correct the dead zone,to avoid the system instability problems caused by the parameter drift,through adaptive adjusting control to ensure that the size of the interconnected system quickly restore stability after failure.4.A decentralized state feedback control scheme is designed for the nonlinear interconnected closed loop system.The state of the subsystem is linearly transformed,and the decentralized state feedback control rate is obtained by using Lyapunov's theorem and Taylor's theorem.The control rate is applied to the subsystem to make up for the influence of the interconnection function on the subsystem.On the other hand,the states of the subsystem converge rapidly to an acceptable range near the origin,whether or not there are external disturbances.