Research On H_? Fault Detection Methods For Complex Networked Systems Based On Communication Protocol

In an actual networked control system,the occurrence of a fault will degrade the performance of the system and lead to a reduction in the security and reliability of the system.Therefore,it is very important to use the measurable information in the system to detect possible faults.In the networked control system,all components are connected to the shared communication network in the form of nodes to complete data transmission.In view of the fact that collisions and collisions may occur when data is transferred between network nodes,communication networks usually adopt appropriate communication protocols to schedule data.The use of communication protocols can improve the utilization of network resources,but will affect system performance to a certain extent.At present,people's research on communication protocols mainly focuses on the control/filtering problems of linear and deterministic systems.The impact of communication protocols on fault detection in complex systems with network-induced factors has not been fully studied.In this engineering background,this article aims to study the fault detection problems of a series of complex systems under the Round-Robin protocol and stochastic communication protocol.The main tasks are as follows:Firstly,the H_?fault detection problem for a class of stochastic time-delay systems based on the Round-Robin protocol is studied.Aiming at the random time-varying delay and non-linear phenomena existing in the network environment,a complex network mathematical model is established,and the Round-Robin protocol is used for scheduling in the process of transmitting signals in the sensor network,so that the nodes have average access to the network,thereby greatly reducing data conflicts and other phenomena that occur during transmission.A non-fragile H_?filter is designed for this type of random time-delay system based on the Round-Robin protocol to ensure that the filter error system under the influence of the Round-Robin protocol is random and stable,and the performance index is established to evaluate the influence of external interference of the network control system on the residual signal observation error.Thus,the problem of fault detection in networked systems with random delay and nonlinearity under the scheduling of Round-Robin protocol is realized.Secondly,the H_?fault detection problem for data packet loss system and random nonlinear system under stochastic communication protocol is studied.Aiming at the phenomenon that each node's access to the communication network in the signal transmission is random,a stochastic communication protocol,which is a communication protocol with better scalability,is used to schedule the signal transmission between the nodes to optimize the communication process.When establishing the system state equation,focus on the impact of data packet loss,time delay and randomly occurring nonlinearity on system analysis,the Bernoulli random distribution is used to describe the packet loss during data transmission.The equation of state is established using a suitable nonlinear function and a reasonable random representation method.At the same time,the channel fading characteristics are considered on the basis of the random nonlinear system following the stochastic communication protocol.Based on a communication network with a stochastic communication protocol,the non-fragile H_?filtering problems of a class of random packet-drop systems with time delay and a class of random nonlinear systems with channel fading are considered respectively.The fault detection index and residual evaluation strategy are designed to provide a basis for the detection of system faults.The sufficient conditions for the existence of the H_? non-fragile fault detection filter under the stochastic communication protocol satisfying the corresponding performance indexes are solved,and the influence of the stochastic communication protocol on the fault detectability is obtained to solve the corresponding fault detection problem.Finally,the H_?fault detection problem of an actual communicated train operation control system is studied.Newton's kinematics equation is used to establish the train operation model,and the CSMA protocol,which is similar to the SCP principle,is used to transmit the information data between the vehicles and the ground to ensure the orderliness of the train operation.On the basis of the fault detection method established above,the system performance analysis and filter design are carried out for the established train operation system and the filter design scheme based on the communication protocol to realize the fault detection of the system.This is an exploratory attempt of the model-based fault detection method in engineering applications,and provides a new theoretical basis for engineering practice.