This paper proposes a novel co-design method of denial-of-service (DoS) attack-resilient time varying estimators/observers and controllers aimed at addressing these challenges in a discrete-time linear networked control systems (NCSs) under sensor and actuator false data injection (FDI) attacks. Our time-varying estimators have uniquely equipped to perform a joint estimation of the system state, sensor and actuator attack signals despite the presence of the intermittent DoS attacks. The main features of the developed time-varying observers are twofold: firstly, it involves time-varying gains corresponding to the DoS attack off/on transitions, and secondly, it entails augmenting the estimations of sensor and actuator FDI attacks within the piecewise observer error dynamics, thus providing a comprehensively and rigorous estimation and control methodologies. By introducing the conceptions of minimum and maximum sleeping/active durations of DoS attacks, a new time-varying DoS attack instant-dependent piecewise Lyapunov function approach is proposed to analyze theH∞stability of the augmented estimation error system and closed-loop control system under sensor and actuator FDI attacks. Based on the obtainedH∞stability analysis results, time-varying gains of state and attack observers are formulated to construct the DoS-resilient observers. Besides, the time-varying feedback gains are also obtained to construct the DoS-resilient controllers by attack compensation based on the actuator FDI attack estimations of time-varying observers, thus achieving the mitigation of sensor and actuator FDI attacks. Case studies are performed on a three-area interconnected power systems under DoS and FDI attacks to validate the effectiveness and advantages of the developed theoretical findings.

This paper is concerned with a resilient load frequency control (LFC) of multi-area power systems subject to unknown load disturbances and intermittent denial-of-service (DoS) attacks. The central aim is to develop a feasible and less conservative DoS-resilient LFC scheme that constrains jammer’s actions as less as possible and explores available attack information as much as possible in desired analysis and design criteria. Towards this aim, we first present a partially known DoS model that bounds merely the DoS-on durations. We then elaborate a sampled-data-based transmission paradigm which characterizes explicitly the uniform sampling instants and intermittent DoS-on and -off instants as well as the nonuniform arriving instants of the transmitted system data. Furthermore, we develop a novel attack-parameter-dependent Lyapunov functional to establish less conservative conditions for both stability analysis and controller design. It is shown that the exponential stability of the resultant closed-loop LFC system can be guaranteed, while also preserving both the desired minimum sleeping rate of DoS attacks and the prescribedH∞performance index against changing load disturbances. Finally, several case studies of a three-area power system are provided to verify the effectiveness and superiority of the derived theoretical results.

The issue of bipartite time-varying formation (BTVF) tracking for linear multiagent systems (MASs) with a leader of unknown input on signed digraphs is investigated. An adaptive nonsmooth protocol is taken in this article that utilizes only the local output feedback information among neighbors and, thus, can avoid employing the eigenvalue information of the Laplacian matrix of the graph. It is proven that if the interaction network of agents containing a spanning tree is structurally balanced, the BTVF tracking can be achieved with a leader of the bounded input via the proposed scheme. This leader-following BTVF includes two time-varying subformations, whose relationship is antagonistic. A convergence analysis of the proposed protocol for MASs is reflected by the Lyapunov method. Finally, the validly numerical simulations are illustrated to show the performance of the proposed schemes.

This paper presents a secure chaotic communication scheme using observer-based synchronization of chaotic systems. A class of chaotic systems satisfying incremental quadratic constraints are considered as the transmitter. The original message is encrypted in the noise-like output of the system. A circle criterion-based observer is designed for the system as the receiver by using the linear matrix inequalities technique. The message is recovered at the receiver end from the estimation error of the observer. To design the observer, a general algorithm to calculate incremental multiplier matrices for nonlinearities in chaotic systems is presented. Moreover, the proposed observer-based chaotic secure communication scheme is feasible for many common chaotic systems with ellipsoidal bounds. The simulation results show the good performance of the proposed communication scheme through an example of image transmission.