Event-triggered secure observer-based control for cyber-physical systems under adversarial attacks

This article considers the problem of adaptive control against deception attacks for a class of switched nonlinear cyber‐physical systems (CPSs), in which each subsystem has more general and unknown nonlinearities. Specifically, an adaptive controller is designed for CPSs with unknown switching mechanisms to mitigate the impact of state‐dependent sensor attacks and input‐dependent actuator attacks. Compared with the existing researches, the actuator attacks considered in our article are input‐dependent, which means the controller is substantially attacked, besides, the signs of unknown time‐varying gains caused by state‐dependent sensor attacks and input‐dependent actuator attacks are all unknown. To deal with these scenarios, Nussbaum‐type functions are introduced. In addition, by constructing a common Lyapunov function for all subsystems, the closed‐loop system signals are proved to be globally bounded under arbitrary switchings. Finally, we give a simulation example of a continuously stirred tank reactor system with state‐dependent sensor attacks and input‐dependent actuator attacks to illustrate the effectiveness of our results.

This article concerns the problem of observer-based event-triggered control for cyber-physical systems (CPSs) under denial-of-service (DoS) attacks. In contrast to the existing studies where DoS attacks on different channels are the same, the considered attacks compromise each channel independently. Correspondingly, a decentralized event-triggered scheme is adopted based on the tradeoff between the transmission efficiency and tolerable attack intensity with guarantees on the closed-loop stability. Inspired by the Lyapunov theory for switched systems, the proposed stabilization criteria reveals a link between the tolerable attack intensity and the event-triggering parameters. An example is finally provided to illustrate the effectiveness of the proposed approaches.

This note is devoted to study the stabilization problem of stochastic nonlinear delay systems with exogenous disturbances and the event-triggered feedback control. By introducing the notation of input-to-state practical stability and an event-triggered strategy, we establish the input-to-state practically exponential mean-square stability of the suggested system. Moreover, we investigate the stabilization result by designing the feedback gain matrix and the event-triggered feedback controller, which is expressed in terms of linear matrix inequalities. Also, the lower bounds of interexecution times by the proposed event-triggered control method are obtained. Finally, an example is given to show the effectiveness of the proposed method. Compared with a large number of results for discrete-time stochastic systems, only a few results have appeared on the event-triggered control for continuous-time stochastic systems. In particular, there have been no published papers on the event-triggered control for continuous-time stochastic delay systems. This note is a first try to fill the gap on the topic.

This article addresses the problem of event-triggered quantized control for cyber-physical systems under multiple-channel denial-of-service (DoS) attacks, which independently affect each communication channel. First, to conserve communication resources, a decentralized event-triggered scheme (ETS) with quantization is proposed. Specifically, a transmission interval bound is introduced in the decentralized ETS to reduce the transmission frequency, and an adjustable parameter is designed for the quantizer to decrease the number of bits. Second, the DoS intervals are redefined by applying the transmission interval bound. Subsequently, the transmission interval bound is adopted as the update interval of the controller, and an attack switched mode is developed based on the multiple-channel DoS attacks, thereby designing a control strategy. Furthermore, based on Lyapunov theory, sufficient conditions are derived that reveal the relationship among the eventtriggering parameters, quantizer parameters, and attack intensity, ensuring the closedloop stability of the system. Finally, a numerical example is employed to demonstrate the feasibility of the presented approach.

This manuscript studies the problem of secure state estimation (SSE) for a class of linear discrete cyber‐physical systems (CPSs) considered with output disturbances, actuator, and sensor attacks. The disturbances and attacks considered are unbounded. A finite time SSE (FTSSE) method is designed to realize SSE for CPSs in a predetermined finite time. First, a finite time observer is designed to implement the FTSSE for CPSs with actuator attacks and output disturbances. After that, the FTSSE method for CPSs with simultaneous sensor attacks is proposed by extending the designed finite time observer. The necessary conditions for the existence of the proposed FTSSE method are given, and its effectiveness is analyzed theoretically. In addition, the simultaneous estimation of disturbance and attack can be achieved by the designed estimator when the system satisfies some given conditions. Finally, the effectiveness of the designed method is verified by a simulation experiment.

This paper investigates the problem of event-triggered networked predictive control for systems with data loss. An event-triggered networked predictive control system is proposed. Based on predictive control model, a data loss compensation strategy is presented and an extended event-triggered transmission mechanism is developed. The closed-loop event-triggered predictive control system is described as a switched system and sufficient closed-loop stability conditions related to event-triggered mechanism are established. Under the event-triggered networked predictive control scheme, the consumption of the communication resources is reduced. Finally, an example is provided to illustrate the effectiveness of the proposed method.

To characterise the resilience of a control system in cyber‐physical systems (CPSs) against actuator attacks and sensor attacks, we introduce new notions of controllability and observability to derive conditions under whether the state can be stabled and reconstructed by the existing control signal and measurements over a period of time. With the understanding that some of the available system's inputs and outputs may have been compromised by the adversary, we derive the necessary and sufficient conditions to utilise standard controllability and observability matrix tests to be calculated in checking whether a CPS is ‘controllable and observable under attacks’, and verify the theorems by a simulation of 9‐bus power grid system under attacks.

A survey on recent advances in event-triggered communication and control

Event-triggered controller design of nonlinear discrete-time networked control systems in T-S fuzzy model

Cyber-physical systems (CPSs), which integrate sensing, computation, and control, are widely deployed in safety-critical applications such as industrial monitoring and predictive maintenance. Industrial fault diagnosis systems (IFDSs), as a representative CPS, enable intelligent health monitoring but are increasingly vulnerable to stealthy adversarial attacks—carefully crafted input perturbations that mislead models while remaining imperceptible. These attacks compromise system safety, highlighting the urgent need for learning-based security control in CPS. This article proposes multilayered noisy mixup (MLNM)-frequency shift (FrSh), a theoretically grounded adversarial defense framework for IFDS under real-world conditions involving nonstationary signals and class imbalance. The framework integrates two components: multilayered noisy mixup (MLNM) and frequency shift (FrSh). MLNM injects structured additive and multiplicative noise during training and is theoretically proven to introduce first- and second-order regularization terms in the loss function, enhancing generalization and gradient stability. FrSh performs spectrum-aware transformations that preserve conjugate symmetry and spectral integrity, with formal guarantees of aliasing-free, reversible frequency mapping, facilitating effective learning of high-frequency diagnostic features. Extensive experiments on benchmark datasets demonstrate that MLNM-FrSh significantly improves adversarial robustness and standard accuracy compared to state-of-the-art baselines. This work contributes a reliable and theoretically principled solution for attack-resilient fault diagnosis, advancing the broader goal of intelligent security control in CPS.

This paper is concerned with the problem of event-triggered control for a networked discrete-time singular system. A novel event-triggered networked control scheme is proposed to save the limited network communication bandwidth. By using a delay system approach, a unified model of event-triggered control system is established. A new criterion is proposed in terms of strict linear matrix inequality (LMI) by using Lyapunov functional method, which guarantees the admissibility of the discrete-time networked singular system without resorting to decomposing the system matrices. A state feedback controller is then designed based on this criterion. Finally, a numerical example is provided to illustrate the effectiveness of the proposed method.

Cyber attacks threaten the security of cyber-physical systems (CPSs) seriously. Resilient control has been studied to defend cyber attacks. However, existing resilient control schemes have not considered system structure changes caused by actuator attacks. Such structure changes are more destructive and harmful than the actuator attack scenarios investigated in the literature, demanding new resilient control strategies. They will be addressed in this article in cloud computing environments, which are increasingly deployed in large-scale CPSs. More specifically, a resilient control scheme is designed which consists of two controllers: a local resilient controller and cloud-based resilient controller. The local resilient controller withstands actuator attacks that simply tampers the actuator output to a large extent. The cloud-based resilient controller aims to resist the actuator attacks that destroy the system structure. Simulations are conducted on a permanent synchronous motor control system to demonstrate the proposed resilient control scheme.

Cyber-Physical System (CPS) is a symbol of the fourth industrial revolution (4IR) by integrating physical and computational processes which can associate with humans in various ways. In short, the relationship between Cyber networks and the physical component is known as CPS, which is assisting to incorporate the world and influencing our ordinary life significantly. In terms of practical utilization of CPS interacting abundant difficulties. Currently, CPS is involved in modern society very vastly with many uptrend perspectives. All the new technologies by using CPS are accelerating our journey of innovation. In this paper, we have explained the research areas of 14 important domains of Cyber-Physical Systems (CPS) including aircraft transportation systems, battlefield surveillance, chemical production, energy, agriculture (food supply), healthcare, education, industrial automation, manufacturing, mobile devices, robotics, transportation, and vehicular. We also demonstrated the challenges and future direction of each paper of all domains. Almost all articles have limitations on security, data privacy, and safety. Several projects and new dimensions are mentioned where CPS is the key integration. Consequently, the researchers and academicians will be benefited to update the CPS workspace and it will help them with more research on a specific topic of CPS. 158 papers are studied in this survey as well as among these, 98 papers are directly studied with the 14 domains with challenges and future instruction which is the first survey paper as per the knowledge of authors.

Distributed robust event-triggered adaptive control for a class of uncertain nonlinear multi-agent systems with actuator saturation

Almost all of the available literature on secure state estimation focus on sensor attacks. Unlike the existing results, this study investigates the attack‐resilient state estimation problem for continuous‐time linear systems with sparse actuator attacks and process noises. It is assumed that, the attacker has limited resources and can only manipulate a certain number of actuators. Specifically, a novel switched observer is proposed with milder design conditions which are derived in terms of linear matrix (in)equalities. It is shown that, the observer not only provides an attack‐resilient state estimation, but also guarantees that the resulting observer error system is with noise attenuation level which can be optimised. Finally, a simulation example of a linearised reduced‐order aircraft system is provided to show the effectiveness of the proposed approach.