Abstract
This paper introduces the state-/output-feedback control for multi-channel nonlinear cyber–physical systems (CPSs). Many cyber-attacks are considered such as Denial-of-Service (DoS), replay and deception attacks. The deception cyber-attacks can be treated as measurement additive and multiplicative uncertainties. Both time-varying state-dependent and state-independent sensor additive attacks are considered. As DoS attack makes the CPS states unavailable, the standard modeling and control methods cannot be applied directly. Alternatively, as attackers in the replay attack re-transmit previous data and prevent the transmission of the more recent data, a delayed model is generated. To deal with these problems, a new observer at the controller side is proposed. It is used to perform two main tasks. The first is to estimate all system states at every time instant. The second is to exclude some unsecured transmitting channels from affecting the system response. Therefore, all attacks in these channels will have no effect on the system response. Using the estimated states, an anti-cyber-attacks state-feedback controller is investigated. Meanwhile, it is verified that the suggested approach certifies the convergence of all the CPSs states under different cyber-attacks. The effectiveness of the proposed secure control approach against different kinds of cyber-attacks is confirmed through two examples with simulation results.
•A new model of DoS, replay, and deception attacks with degradation gain and state-dependent/-independent forms is proposed.•An asymptotic observer at the controller side is synthesized to reconstruct the system states at every time instant.•There is no need to design predictors for predicting the time of occurrence of the DoS attacks.•A new multi-channel transmission method in which some channels are excluded from affecting the system response is proposed.•For state and output feedback, controllers are designed such that asymptotic stability rather than boundedness is ensured.