Secure Control for Networked Control Systems With Actuator Failure and Random Hybrid Attacks

Event-triggered [formula omitted] stabilization of networked cascade control systems under periodic DoS attack: A switching approach

This paper investigates the stability of networked control systems under hybrid attacks. Two types of attacks are considered: Denial of Service (DoS) attacks and deception attacks. The analysis combines the dynamic event‐triggered mechanism with Linear Matrix Inequality (LMI) to examine the stability of the closed‐loop system. Additionally, by evaluating the maximum attack probability and the maximum attack intensity of deception attacks, a Lyapunov function equation is constructed to prove the system's stability. Finally, simulations are conducted to demonstrate the feasibility of the conclusions.

In this article, the problem of robust exponential stability and reliable stabilisation for a class of continuous-time networked control systems (NCSs) with a sample-data controller and unknown time-varying sampling rate is considered. The analysis is based on average dwell-time, Lyapunov–Krasovskii functional and linear matrix inequality (LMI) technique. The delay-dependent criteria are developed for ensuring the robust exponential stability of the considered NCSs. The obtained conditions are formulated in terms of LMIs that can easily be solved by using standard software packages. Furthermore, the result is extended to study the robust stabilisation for NCS with parameter uncertainties. A state feedback controller is constructed in terms of the solution to a set of LMIs, which guarantee the robust exponential stabilisation of NCS and the controller. Finally, numerical examples are presented to illustrate the effectiveness of the obtained results.

This paper focuses on addressing the challenges of finite‐time output tracking control for unmanned aerial vehicles (UAVs) with a particular emphasis on security concerns. The potential impact of denial‐of‐service (DoS) attacks on the integrity of measurement‐to‐control communication channels is incorporated into our analysis. Such attacks may disrupt the central control unit's capability to access real‐time measurement data, which encompasses the system states and the reference signal information. Under this consideration, we have formulated sufficient conditions based on the Lyapunov theory, aimed at ensuring that the system's state trajectory remains confined within a pre‐established boundary over a designated time frame. However, note that there are some coupling terms of unknown matrix variables, and the developed conditions are nonlinear and difficult to be solved by some commonly used linear matrix inequality (LMI) techniques. In order to handle the nonlinear and non‐convex constraints in the determination of the controller gains and the finite‐time performance, we have proposed a novel iterative algorithm. The novel presented algorithm mainly combines genetic algorithm with LMI techniques. To validate the effectiveness of our approach, a case study of a UAV networked output tracking control system is conducted and detailed in the final section of this paper.

This study is concerned with the reliable controller design for networked control systems (NCS) against both probabilistic sensors faults and actuators faults. The faults of each sensor or actuator occur randomly and their failure rates are governed by two sets of unrelated random variables satisfying certain probabilistic distribution. In terms of the probabilistic failures of every sensor or actuator, new type of distribution-based NCS fault model is proposed. Based on the new built model, reliable controller is designed and sufficient conditions for the exponentially mean square stability (EMSS) of NCS are obtained by using Lyapunov functional method. The main contribution of the proposed fault model and methods lies with its practicality and generalisation, which contains many realistic problems in the NCS, such as probabilistic sensors or actuators failures, partial degradation, data distortion, packet dropout, network-induced delay and so on. Moreover, some existing models in the open literatures are deemed as special cases of the proposed fault model. To illustrate the implementation procedure, a vertical take-off and landing (VTOL) aircraft system is given to show the effectiveness and application of the proposed method.

This article presents a method of suppressing packet losses and exogenous disturbances for a networked control system (NCS) subject to network-introduced delays. The NCS has two feedback loops: 1) a local one and 2) a main one. The local feedback loop contains a state observer, an equivalent-input-disturbance (EID) estimator, and state feedback. It is used to ensure prompt disturbance suppression. The controller in the main feedback loop contains an internal model to track a reference input. The system is divided into two subsystems for the design of controllers. The state-observer gain is designed for one subsystem using the concept of perfect regulation to ensure disturbance estimation performance. The state-feedback gains of the other subsystem are designed based on a stability condition in the form of a linear matrix inequality (LMI). A tracking specification is embedded in the LMI-based stability condition to ensure satisfactory tracking performance. A case study on a two-finger robot hand control system and a comparison with a Smith-EID and H∞ controller approach validate the effectiveness and superiority of the presented method.

This paper deals with static output feedback control of a class of discrete‐time networked control systems (NCS) subject to random failures and random delays. The different random processes are modeled as Markovian chains, and the resulting closed‐loop system belongs to the class of discrete‐time Markovian jump linear systems (MJLS). The main contribution is to formulate conditions for multi‐performance design related to this class of stochastic hybrid systems. The specifications and objectives under consideration include stochastic stability, ℋ︁2and ℋ︁∞performances. Results are formulated as matrix inequalities. A numerical algorithm is provided and its running is illustrated on a numerical example. Copyright © 2008 John Wiley and Sons Asia Pte Ltd and Chinese Automatic Control Society

Driven by recent telecommunication demand, shared communication channels are more abundant today than ever before. These shared wired/wireless networks for communication are being exploited more and more in control systems to connect sensors, controllers and actuators resulting in so-called networked control systems (NCSs). NCSs replace the more traditional control systems where dedicated point-to-point (wired) connections are being used. The advantages of using NCS technology are inexpensive and easily modifiable communication links which allow control algorithms to be easily implemented in situations where dedicated connections are not possible (either economically or physically). However, the drawback is that the control system is susceptible to undesirable (possibly destabilizing) side-effects such as time-varying transmission intervals, time-varying delays, packet dropouts, quantization and a shared communication medium. These network-induced effects undermine fundamental assumptions on which traditional control theory is built and, therefore, it is essential to develop new techniques and tools that can be used to analyze and/or design control systems which communicate via a shared network. This thesis advances NCS analysis and design methodologies by contributing new theoretical developments, new software tools and new experimental validation results. The first new theoretical development is in the area of analyzing robust stability properties with respect to network-induced effects. A sum of squares (SOS) approach for a class of nonlinear NCSs incorporating bounded time-varying delays, bounded time-varying transmission intervals and a shared communication medium is developed. Mathematical models that describe these nonlinear NCSs are cast into suitable hybrid system formulations. Based on these hybrid system formulations, (families of) Lyapunov functions are constructed using SOS techniques. Amongst other benefits, it is shown that this technique improves the guaranteed robustness margins compared to existing work. The second new theoretical development concerns the design of networkaware decentralized controllers guaranteeing robust stability properties with respect to network-induced effects. We develop one of the first approaches based on semidefinite programming techniques to synthesize stabilizing decentralized observer-based output-feedback controllers for linear plants where the controllers, sensors and actuators are connected via a shared communication network subject to time-varying transmission intervals and delays. To effectively deal with the shared communication medium, a switched observer structure is adopted that switches based on the transmitted measured outputs and a switched controller structure is also adopted that switches based on the transmitted control inputs at each transmission time. By taking a discrete-time switched linear system perspective on modeling these decentralized NCSs, we are able to derive a general model that captures all these networked and decentralized control aspects. We provide linear matrix inequality (LMI)-based synthesis conditions which, if satisfied, provide stabilizing observer-based controllers that are both decentralized and robust to network effects. Regarding new software tools, the first prototype of a toolbox is developed to automate (robust) stability analysis (and controller design) for NCSs. Specifically, it is shown that the toolbox can be employed to efficiently verify if a linear time-invariant (LTI) plant and an LTI controller interconnected with a shared network are robust to certain network imperfections. The main intention of the toolbox is to make the available theory readily accessible to and applicable for the general control community. Additionally, the chosen software structure enables the incorporation of custom models or custom stability/performance analysis conditions in an easy manner, thereby allowing the control community to contribute and to further develop the toolbox. Finally, an experimental case study involving a wirelessly controlled inverted pendulum/cart system is investigated. In particular, the communication network itself is analyzed such that the network-induced effects can be characterized in terms of bounds on the transmission intervals and transmission delays. Based on these bounds, the prototype toolbox is applied to analyze the robustness regions for different performance specifications, which aid in tuning the controller to achieve more closed-loop robustness with respect to the network-induced effects. This leads to a validation of the developed theory in an experimental setting. In addition to the validation of the developed theory, many new insights into the network behavior are obtained and explained, thereby raising new interesting questions for future research on NCSs.

For a class of uncertain continuously networked Lurie control systems with both sensor-to-controller time-delay and controller-to-actuator time-delay, the problem of codesigning its observer and fault-tolerant controller based on an event-triggered mechanism under actuator failure is investigated. Firstly, considering that the state of the system cannot be measured directly, an observer is constructed on the controller node. Secondly, to reduce the waste of network bandwidth resources and improve the performance of the network control system, a network control system approach based on event-triggered mechanism is proposed. By introducing the event-triggered mechanism and the actuator fault indication matrix, the Lurie networked control system is modeled as a Lurie system with time-delay using the state augmentation technique to obtain a model of the closed-loop system. Finally, based on Lyapunov stability theory, sufficient condition for the stability of the closed-loop system is obtained, and the design method of the fault-tolerant controller and the observer is given. The obtained results are given in the form of linear matrix inequalities, which are easy to be solved by using the linear matrix inequality toolbox. Finally, the feasibility and effectiveness of the method are illustrated by a simulation example.

This paper is concerned with the guaranteed cost controller design of networked control systems. The continuous time plant with state-delay is studied. A new model of the networked control systems is proposed under consideration of the network-induced delay and data packet dropout. In terms of the given model, a suboptimal guaranteed cost controller design method is proposed based on linear matrix inequalities (LMI) approach. Suboptimal allowable equivalent delay bound (SAEDB) and the feedback gain of a memoryless controller can be derived by solving a set of LMI for the networked control system based on Lyapunov functional method. An example is given to show the effectiveness of our method

Hybrid-triggered reliable dissipative control for singular networked cascade control systems with cyber-attacks

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

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

The integrity design problem of fault tolerant control for networked control system (NCS) with actuator failures and data packet dropouts is investigated. The data packet dropouts in both sensor-controller (S-C) and controller-actuator (C-A) links are described by two switches, which can be modeled as a discrete event system with known rate. After introducing the matrix of actuator failure, the closed-loop NCS is developed, which can be viewed as asynchronous dynamical systems (ADSs). Then, the sufficiency of exponential stability for the NCS is obtained based on the theory of ADSs. The output feedback controllers that can guarantee system stability are also proposed. Finally, two numerical examples are given to demonstrate the validity of our proposed approach.

This paper focuses on the fault-tolerant control (FTC) of networked control systems (NCSs) with packet dropouts using switched system approach. The basic idea is to model such NCSs as a discrete-time switched system. Thus, the FTC of such NCSs can be reduced to that of switched systems. Sufficient conditions are presented about the stabilization of NCSs. Stabilizing switched state/output feedback controllers can be constructed by solving a set of linear matrix inequalities (LMIs), which can be easily tested with efficient LMI algorithms. The maximum allowable dropout bound can be obtained by solving an optimization problem.