Fault Detection In Network Control Systems Based On Delta Operators

Along with the rapid development of computer technology and the growing demand for communication network technology in real production life,network control systems are gaining more and more attention.Due to the defects of limited network transmission capacity and small network bandwidth,it will cause the system to produce time-varying delay,data loss and multi-packet transmission.In this paper,the network control system with time-varying delay and packet loss is used to study the fault detection problem in complex situations based on the network model obtained by discretization of Delta operator.The research of this paper is divided into three parts as follows:(1)For a class of network control systems with faults and external disturbances,the design of a fault detection observer based on the Delta operator is studied.Based on the Luenberger observer,a new fault detection observer is designed by discretizing the Delta operator to obtain a network control system.Based on the constraints of the Luenberger observer,the existence conditions and expressions of the new observer described by the Delta operator are obtained,and the design algorithm of the observer is given.Finally,Matlab simulation example verifies the effectiveness of the design method.(2)For a class of network control systems with faults and external disturbances,the problem of fault detection in Delta arithmetic systems based on an event-triggered mechanism is studied.In order to alleviate the network blockage problem caused by a large number of packets,this chapter uses the event-triggered mechanism for selective transmission of packets.While co-designing the fault detection filter and controller,a constructive vector is added to the Delta operator filter model to avoid the generation of bilinear terms in the parameter design.The stability and H_∞performance of the residual system is analyzed by constructing Lyapunov-Krasovskii generalized functions inδdomain.Finally,Matlab simulation example verifies the effectiveness of the design method.(3)For a class of network control systems with faults and external disturbances,the problem of designing a fault detection filter based on the Delta operator is studied when there are two-channel data packet loss and time-varying time delays.Two independent Bernoulli random variables are used to describe the two-channel data packet loss respectively.The system is modeled as a network switching system,and the design method of fault detection filter under arbitrary switching law is proposed.The sufficient conditions for the system to have exponential mean square stability are obtained using linear matrix inequality method,Lyapunov-Krasovskii generalization and mean residence time,and the designed switching system is proved to satisfy the H_∞performance.Finally,Matlab simulation example verifies the effectiveness of the design method.