V. Panneerselvam

The active fault‐tolerant tracking control strategy is employed in this work for nonlinear cyber‐physical systems under deception attacks, sensor faults and actuator faults. Briefly, the aforesaid tracking controller is designed based on the fast adaptive unknown input observer technique, which not only ascertains the state tracking of the addressed system but also ensures multiple faults reconstructions. Prior to formulate the observer, the nonlinearity of the cyber‐physical systems is proficiently handled by the fuzzy approach, in particular, the non‐parallel distributed compensation concept is employed in the controller design to relax its conditions. Moreover, the simultaneous reconstruction of system states, actuator faults and sensor faults is assured by the dint of fast adaptive unknown input observer design. Then, the reconstruction information is combined with the tracking error feedback controller to attain the required state tracking outcomes of the investigated system even in the face of multiple faults. It should be noted that the fuzzy‐based reference system is framed in this study for obtaining the required results. In parallel, the occurrence of deception attacks is indicated by the Bernoulli distributed stochastic random variable. Besides, the required stability conditions are obtained by means of the Lyapunov stability method. Thereafter, the two numerical simulations are provided to highlight the significance of the developed control strategy both theoretically and practically.

This study addresses the issue of finite‐time observer‐based control design for a nonlinear fractional‐order system under additive faults and disturbances. The main motive is to construct a nonlinear fractional‐order proportional‐integral observer such that it simultaneously estimates the states and fault signal. A controller is designed to overcome the mismatch between the quantization parameters, and also the estimated fault signal is incorporated in the control design to eliminate the effects of the fault in the system. Furthermore, by choosing an appropriate Lyapunov function, the results are deduced in terms of linear matrix inequalities, based on which the observer and controller gain values are obtained. Then the viability of the developed controller and observer is verified by numerical simulation results.

The main thrust of this study is to scrutinize the issues of fault estimation and asynchronous sampled‐data fault‐tolerant control for semi‐Markov jump cyber‐physical systems with external disturbances, faults and deception attacks. To do so, initially, an intermediate variable is framed and then using that variable as a foundation, a mode‐dependent intermediate estimator is constructed, which estimates the fault signals and system's state simultaneously. Due to the unavailability of mode information in the Markov chain for the observer/controller, a hidden Markov model is employed to represent the asynchronous scenario between the mode of the original system and that of the designed observer/controller. Subsequently, benefited by the estimated terms and sampled‐data approach, an asynchronous sampled fault‐tolerant control protocol is offered up that facilitates compensating for the faults occurring in the system. In the meantime, the extended passive performance is used to lessen the negative impact of external disturbances exerting on the system. Besides this, the deception attacks occurring in the system are presumed to have a stochastic nature that adheres to the Bernoulli distribution. Moreover, by constructing mode‐dependent Lyapunov–Krasovskii functional and blending it with integral inequalities, the sufficient condition confirming the intended outcomes is procured in the framework of linear matrix inequalities. Thereafter, on the platform of deduced adequate criteria, an explicit formulation for the requisite gain values can be obtained. Ultimately, simulation results are offered to verify the reliability of presented outcomes.

Utilising the fault alarm approach, the fuzzy rule-based hybrid controller is designed for interval type-2 fuzzy cyber-physical systems with actuator faults, deception attacks and external disturbances. Precisely, a fuzzy rule-based fault-alarm system is configured relying on the alarm threshold in order to notify the controller in a timely manner to make the transition from the robust controller to the fault-tolerant controller. Thereafter, with the benefit of Lyapunov stability theory, sufficient requirements affirming the asymptotic stability of the assayed system are procured. From thereon, the explicit structure of a robust and reliable controller is offered. Eventually, a numerical example is proffered to certify the prominence of the theoretical insights accorded.