Dynamic event‐triggered control for networked control systems under hybrid cyber‐attacks

Recent technological advances have enabled distributed control systems to be implemented via networks. This allows feedback control loops to be closed over a shared communication channel. Network-induced delays are inevitable, however, when transmitting digital data between control devices. This paper analyzes the stability of such networked control systems (NCS). We first review some previous work on this topic, offering some improvements. We analyze the influence of the sampling rate and network delay on system stability. We further study the stability of NCS using a hybrid system stability analysis technique.

The problem of stabilization of networked control systems (NCSs) with time-varying transmission delays is investigated. The time-varying delays lie in any two adjoining sampling instants of the plant. A technique is proposed for designing stabilizing controllers by converting NCSs with time-varying transmission delays into parameter uncertain systems with constant input delay, then the theory of robust stabilization of delay systems can be applied to solving this problem. Sufficient condition on stabilization of such NCSs is developed in terms of linear matrix inequality.

The problem of stabilization of networked control systems (NCSs) with data packet dropout is studied. Sufficient conditions are presented on the stability and stabilization of the NCSs with packet dropout. The novelty of this work lies in that NCSs with arbitrary but finite data packet dropout are modelled as switched linear systems, and this enables us to apply the result of switched systems to the analysis and synthesis of such NCSs. The admissible upper bound of the dropped packets can be determined by a set of linear matrix inequalities (LMIs) which guarantee the stability of the NCSs. Stabilizing controllers (via state feedback and static output feedback) can be constructed by solving a set of LMIs. Also, for an NCS with a convergence rate constraint, similar results are obtained. Examples are worked out to illustrate the effectiveness of the proposed method

Attack-model-independent stabilization of networked control systems under a jump-like TOD scheduling protocol

Exponential stability of networked control systems with network-induced random delaysIn this paper, the problem of exponential stability for the standard form of the state control, realized in a networked control system structure, is studied. To deal with the problem of stability analysis of the event-time-driven modes in the networked control systems the delayed-dependent exponential stability conditions are reformulated and proven. Based on the delay-time dependent Lyapunov-Krasovskii functional, exponential stability criteria are derived. These criteria are expressed as a set of linear matrix inequalities and their structure can be modified to use the bilinear inequality techniques.

Network-induced delays and packet dropouts are relevant issues that can degrade networked control systems' performance and may even lead to instability. This paper concerns the establishment of a stability criterion for networked control systems (NCSs) consisting of an LTI process and a dynamic feedback controller. Conditions for stability are provided in terms of Linear Matrix Inequalities (LMIs), whose solution yields network-induced delay upper bounds. Numerical examples and a simulation ratify the theoretical results.

Output feedback stabilization for Markov-based nonuniformly sampled-data networked control systems

The presence of a communication network in a control loop induces many imperfections such as varying transmission delays, varying sampling/transmission intervals, packet loss, communication constraints and quantization effects, which can degrade the control performance significantly and even lead to instability. Various techniques have been proposed in the literature for stability analysis and controller design for these so-called networked control systems. The aim of this chapter is to survey the main research lines in a comprehensive manner.

New stability criteria and stabilization methods on networked control systems (NCSs) with short time-varying delay (STVD) are proposed in this paper. An NCS with STVD is transformed into a time-varying discrete time system. And then, this discrete time system is converted into a equivalent time-invariant system with norm-bounded uncertainties by using robust control techniques. Using this method, the conservatism of the stability condition caused by STVD can be reduced. Based on that, a single norm-bounded uncertainty is replaced by N norm-bounded uncertainties to further reduce conservatism. Theoretical analysis shows that when N is increased, the stability condition becomes less conservative. For a fixed sampling period, the obtained stability conditions explicitly depend on the upper and lower bounds of the time delay. The existence condition and design method for the controllers are also presented. Finally, three numerical examples are provided to demonstrate the effectiveness of the proposed scheme.

This paper deals with the stochastic stability of networked control systems with the presence of network-induced delay and transmitted data dropout. Based on Lyapunov approach, sufficient conditions for the mean-square stability of the networked control system are derived subject that the sequence of transmission interval is driven by an identically independently distributed (i.i.d.) sequence and by a finite state Markov chain, respectively. Stabilization controllers are constructed in terms of linear matrix inequalities correspondingly. An example is provided to illustrate our results.

The increasing vulnerability of networked control systems (NCSs) to cyber-physical attacks necessitates the development of adaptive security strategies to mitigate risks and ensure system stability. This study explores the Markovian switching-based security strategies for interconnected NCSs, incorporating stochastic optimization and linear matrix inequality (LMI)-based approaches to enhance system resilience against adversarial threats. The primary objectives include formulating a robust mathematical framework that integrates Markovian jump linear systems (MJLSs) with dynamic security mechanisms, designing LMI-based security constraints for stability assurance, and validating the proposed approach through numerical simulations. The study models various cyber-attacks, including denial-of-service (DoS), replay attacks, and hybrid attacks, while employing Markovian switching dynamics to represent system transitions under attack conditions. The results reveal that persistent and hybrid attacks cause significant degradation in system performance, lowering the stability index and control efficiency while increasing response time. Statistical analysis using ANOVA confirms the significant impact of attack types on system stability and efficiency. The findings support the hypothesis that adaptive Markovian switching strategies improve system resilience compared to conventional static security methods. This research contributes to the development of real-time security frameworks for cyber-physical systems, offering practical recommendations for integrating AI-driven detection algorithms, cryptographic security, and hierarchical control strategies to counter evolving cyber threats in industrial automation and smart infrastructures.

Delay-dependent stability criteria for a class of networked control systems with multi-input and multi-output☆

International audience

This research investigates the design of state feedback controllers for Networked Control Systems (NCSs) subject to actuator failures alongside hybrid cyber‐attacks, specifically Denial‐of‐Service (DoS) and deception attacks. To reduce the use of network resources, two distinct dynamic event‐triggered schemes (DETSs) are proposed. These DETSs govern the data transmission scheduling for both measurement outputs and control inputs across the communication network. A key contribution lies in the simultaneous consideration of actuator malfunctions and the aforementioned hybrid cyber‐attack scenarios. Utilizing Lyapunov stability theory, conditions for the mean square asymptotic stability of the resultant augmented closed‐loop system are established. Subsequently, controller gains and event‐triggering parameters are co‐designed through the application of linear matrix inequality (LMI) techniques. Finally, a simulation example validates the theoretical results, demonstrating the proposed method's efficacy in mitigating the adverse impact of such cyber‐attacks and actuator failures on networked control systems' performance.

In this paper, we derive a necessary and sufficient condition for stability of networked control systems (NCSs) in the mean square sense and introduce the packet dropping margin to determine the robustness of the system with respect to packet dropping. By analyzing the relationship between the packet dropping probability and stability robustness, it is shown that a controller designed by a robust pole assignment approach makes the system less sensitive to packet dropping.