Distributed Filtering Of Time-delay Systems Based On Adaptive Event Trigger

In recent years,with the rapid development of sensor technology and communication technology,wireless sensor networks have been widely used in industrial,military,and other fields.Because there are many real-life problems that can be treated as evaluations of system states,the design of distributed filtering algorithms in wireless sensor networks is a research topic that has received a lot of attention.The research of distributed filtering focus on how to integrate the information of multiple devices in the network to achieve high availability and high robustness,and to deal with the data distortion and loss caused due to complex network environment.Devices in wireless sensor networks are usually powered by lithium batteries,and the battery capacity is limited.Frequent data communications inevitably lead to increased device energy consumption.Besides that,the deployment cost is much higher in the environments such as underwater and battlefields.Therefore,event triggering mechanisms are introduced to increase the utilization of network resources,reduce the energy consumption of equipment,and extend the lifespan of system.The event trigger mechanism is applied to the data transmission process of the filter node,and the event trigger condition is used to determine whether the latest estimated data is transmitted to the neighbor node.In this paper,a distributed filter is designed for discrete time-delay systems which have problems such as,deception attacks,switching topologies,and data quantization.The specific work is as follows:(1)Research a group of distributed filtering problem of time-delay system with network deception attack based on threshold fixed event trigger mechanism.The description of deception attack adopts from the random sequence distributed by Bernoulli and establishes the corresponding spoofing attack model.The Lyapunov stability theory is used to analyze and prove that the filter error system is mean square exponentially stable,also to show the system satisfy the l₂-l_?performance.The l₂-l_?distributed filter of the discrete time delay system is designed to suppress the external disturbance of the system and the network deception attack on the system.The linear matrix inequality method is used to solve the filter parameters,and numerical simulation is used to prove the effectiveness of the filter.(2)Research a group of distributed filtering problems of time-delay system with data quantization based on adaptive event trigger mechanism.The adaptive event trigger mechanism adopts an adaptive threshold adjustment scheme.Its threshold parameter is adjusted dynamically according to the difference between the filter's current estimated value and the latest release data to maximize the utilization of network resources while the performance of filtering is guaranteed.Consider the data quantification problem caused by the limitation of sensor accuracy and network transmission bandwidth.A simulation example shows that the filter can reduce the impact of data quantization.(3)Research a group of distributed filtering problems in time-delay systems with network topology switching and adaptive event triggering.Design a kind of adaptive event triggering scheme with fixed step adjustment.The Markov chain is used to describe the switching of the filter network topology.The filter error system is analyzed by constructing a Lyapunov function to prove that the system has mean square stability and can meet the l₂-l_?performance.The linear matrix inequality method is used to solve the filter parameters.Finally,numerical simulations are implemented to compare two groups of distributed filtering mechanisms.The result shows that the filter can adapt to the switching topology,reduce the signal transmission frequency between devices while ensuring the estimation accuracy and save network communication resources.