| Networked control systems(NCSs)are a class of closed-loop distributed control systems that use wireless networks as the transmission medium while integrating sensors,controllers,controlled objects and actuators.Because of its many advantages such as high reliability,low installation cost and easy maintenance,it is gradually being widely applied in various fields.However,the rapid development of NCSs is accompanied by many problems to be solved.Due to the openness and sharing nature of wireless communication networks,they are easily interfered by malicious cyber attacks.On the other hand,considering that the network bandwidth is always limited in reality,when a large number of packets are transmitted centrally,it will lead to the blockage of the network channel.That may cause serious problems such as packet loss and network induced delay,and then make the system performance degrade.These interference factors make the theoretical research of networked system control and filtering full of challenges.Based on the above analysis,this thesis takes the networked systems as the research object and mainly studies their control problem under denial-of-service(DoS)attacks and filtering problem under hybrid cyber attacks.The introduction of event-triggered mechanism(ETM)can optimize data transmission and save network resources,and it can also attenuate the impact of DoS attacks on system performance.The main contents are summarized as follows:(1)The dynamic output feedback control problem of networked systems based on adaptive event-triggered mechanism(AETM)and quantization under DoS attack is concerned.Firstly,the unmanned marine vehicle(UMV)system is selected as the research object and its error dynamic equation is constructed.The sampled data signals are processed by AETM and quantizer to achieve the effect of optimizing data transmission and saving network resources.In addition,the aperiodic DoS attacks and network induced delay are considered in the sensor-to-controller network channel.The error dynamic system under the effect of DoS attack is modeled as a switching system.Sufficient criterion for ensuring global exponential stability of the closed-loop system satisfying H_∞performance is obtained.Co-design of dynamic output feedback controller and the AETM is derived.(2)The adaptive event-based finite-time H_∞filtering problem for networked systems is investigated.A switching system and a random Bernoulli variable are used to describe the effects of hybrid cyber attacks consisting of aperiodic DoS attacks and random deception attacks on the closed-loop system,respectively.The network bandwidth constraint problem can be solved effectively by the proposed AETM.After considering the above factors and the effect of network-induced delay on the measured output signal of the system,a filtering error system is established.By the construction of a novel Lyapunov-Krasovskii function,sufficient conditions are obtained to make the filtering error system satisfies finite-time boundedness and H_∞performance.The matrix parameters of the designed filter and the AETM are derived by solving the linear matrix inequality. |
