Distributed Adaptive Consensus Control for Nonlinear Network Systems With Event-Based Switching Mechanism Against Malicious Attacks

In this paper, the distributed adaptive consensus control problem for nonlinear network systems with unmatched unknown parameters is investigated. The communication channels among subsystems are directed and suffer from malicious attacks. Besides, only part of subsystems can access the reference states. To depict different kinds of attacks, a unified attack model is established from the viewpoint of attacked subsystems. Then, an event-based communication switching mechanism is proposed for subsystems to establish new communication channels, such that attack effects on these channels can be mitigated actively. Noting that malicious attacks and switching communication make transmitted states discrete, it is also a tough issue to design controllers by adopt the backstepping technique. To handle this problem and mitigate residual attack effects, a continuous virtual controller is designed by introducing normalization terms in the adaptive laws. Then, a distributed adaptive control scheme is proposed to guarantee that consensus errors are globally uniformly bounded under arbitrary switching dwell-time and malicious communication attacks. Experimental results are provided to validate the effectiveness of the proposed control scheme. Note to Practitioners—This paper is motivated by the secure consensus control problem for nonlinear network systems under malicious communication attacks. In the practice, the Frequency-Hopping Spread Spectrum (FHSS) technique has been used to defend malicious attacks. However, the switched communication induced by the FHSS technique may destroy the consensus performance. Moreover, how to economize the switching resource and improve the active defense ability of control schemes against malicious attack is still a tough issue. Motivated by these points, an active distributed adaptive consensus control scheme is proposed to defend malicious attacks, which contains an event-based switching mechanism and a novel secure controller. The event-triggered switching mechanism is designed with attack-sensitive functions to determine the switching time instants, such that the switching resources can be utilized more efficiently. By introducing a unified attack model, the attack-defense ability of the secure controller against different kinds of attacks can be improved and analyzed mathematically. Moreover, this controller can also be applied to the switched topologies with arbitrary switching dwell-time. In conclusion, this proposed distributed adaptive control scheme can greatly reduce the effects of malicious attacks and switched piecewise states on the consensus performance and controller design, such that engineers can pay more focuses on selecting suitable control parameters to adjust consensus performance. However, to enable above advantages, some bounded biases are involved in the consensus performance. In the future work, more accuracy attack-sensitive functions, optimization algorithms for parameters, switched secure controllers and unknown nonlinear functions satisfying Lipschitz condition can be considered to decrease above bounded biases and improve the consensus performance under malicious attacks.