Event-triggered Adaptive Control Of Networked Interconnected Nonlinear Systems Under Several Types Of Attack

With the development of science and technology,the scale of controlled objects in practice is getting larger and more complex,and the control problem of interconnected systems has been widely concerned by scholars.Compared with traditional control systems,networked systems have unique advantages,such as flexible structure,low maintenance cost and efficient data transmission.Therefore,networked interconnected systems are widely used in smart grid,intelligent transportation and other fields.Due to its complexity and openness,the networked control systems are vulnerable to the threat of cyber attacks,which directly affect the industrial operation security.Therefore,it is of great theoretical and practical significance to ensure the normal operation of the system under the cyber attacks.In this paper,the eventtriggered adaptive control problem under several kinds of attacks is studied for networked interconnected nonlinear systems.The main contributions are as follows:Firstly,the problem of decentralized event-triggered adaptive control for interconnected nonlinear systems with external disturbances and intermittent denial-of-service(DoS)attacks is investigated.In the presence of DoS attacks,all state variables are not used for controller design via the standard backstepping method.To solve the above difficulty,a switching-type adaptive state observer with a disturbance compensation is constructed,where the disturbance compensation term is obtained via constructing a disturbance observer.A decentralized event-triggered adaptive controller is designed by using the backstepping method and neural network technique to weaken the influences of DoS attacks and the waste of communication resources,where a first-order sliding mode differentiator is combined to prevent the“calculation explosion”.By using linear matrix inequality techniques,some solvable sufficient conditions are attained.Based on the improved average dell time method and Lyapunov stability theory,it is demonstrated that the designed controller can ensure that all closedloop signals are semi-globally uniformly ultimately bounded.Finally,simulation results are utilized to demonstrate the effectiveness of the proposed control scheme.Secondly,the problem of decentralized event-triggered adaptive control for interconnected nonlinear systems under injection attacks and intermittent DoS attacks is studied.When the DoS attacks are active,the sensor-controller communication channel is jammed and a novel switching-type state observer is constructed to estimate unmeasured states.When the injection attacks occur,the input signals of the controller-actuator communication channel are changed.A decentralized adaptive event-triggered controller is designed by using the backstepping method and neural network technique,where a first-order sliding mode differentiator is combined to prevent the “calculation explosion”.The observer gain is derived via the linear matrix inequality technique simultaneously.By using the improved average dwell time method and Lyapunov stability theory,it is proved that all the signals of the closed-loop system are semi-globally uniform and finally bounded.Finally,simulation results verify the effectiveness of the proposed control scheme.Thirdly,the problem of decentralized dynamic event-triggered non-recursive adaptive output feedback control for interconnected nonlinear systems under hybrid cyber attacks is addressed,where the hybrid cyber attacks are composed of deception attacks and DoS attacks obeying Bernoulli distribution.A dynamic event-triggered mechanism is designed to reduces the number of sensor updates effectively.Based on the output of the event trigger,a decentralized linear observer is established to estimate the unknown states.Meanwhile,a decentralized adaptive output feedback controller is developed in a non-recursive method and neural network technology.All signals in closed-loop system are guaranteed to be semiglobally uniformly ultimately bounded based on the proposed control scheme,and the Zeno phenomenon is avoided.Finally,simulation results validate the feasibility of the proposed control scheme.