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This paper is concerned with the security issue in the state estimation problem for a networked control system (NCS). A new model of joint false data injection (FDI) attack is established wherein attacks are injected to both the remote estimator and the communication channels. Such a model is general that includes most existing FDI attack models as special cases. The joint FDI attacks are subjected to limited access and/or resource constraints, and this gives rise to a few attack scenarios to be examined one by one. Our objective is to establish the so-called insecurity conditions under which there exists an attack sequence capable of driving the estimation bias to infinity while bypassing the anomaly detector. By resorting to the generalized inverse theory, necessary and sufficient conditions are derived for the insecurity under different attack scenarios. Subsequently, easy-to-implement algorithms are proposed to generate attack sequences on insecure NCSs with respect to different attack scenarios. In particular, by using a matrix splitting technique, the constraint-induced sparsity of the attack vectors is dedicatedly investigated. Several numerical examples are

This article considers the problem of periodic event-triggered control design for dual-rate networked control systems subject to nonvanishing disturbance. The plant considered in this article is a kind of dual-rate networked control system, where the sensor samples the measurement output at a slow rate and the actuator updates the control input at a fast rate. Despite the slow-rate sampling of the sensor, a new output predictor-based observer is proposed to accurately estimate system state and disturbance in the intersample time interval, and an active anti-disturbance controller that updates at a fast rate is accordingly proposed, such that the desirable control performance and disturbance rejection performance can be achieved. At each fast-rate updating time instant, we use the prediction technique to generate a data packet, including the computed current control input and the predicted values of the control inputs for the future finite steps, and design a new periodic event-triggered mechanism to determine whether to transmit the data packet via a communication network or not. The proposed control method is easily implemented in digital platform since it has a discrete-time form. To verify the effectiveness of the proposed control method, we finally present the simulation results of a practical speed control system.

Although transmission of a data packet containing sensory information in a networked control system improves the quality of regulation, it has indeed a price from the communication perspective. It is, therefore, rational that such a data packet be transmitted only if it is valuable in the sense of a cost-benefit analysis. Yet, the fact is that little is known so far about this valuation of information and its connection with traditional event-triggered communication. In the present article, we study this intrinsic property of networked control systems by formulating a rate-regulation tradeoff between the packet rate and the regulation cost with an event trigger and a controller as two distributed decision makers, and show that the valuation of information is conceivable and quantifiable grounded on this tradeoff. In particular, we characterize an equilibrium in the rate-regulation tradeoff, and quantify the value of information $\text{VoI}_k$ there as the variation in a so-called value function with respect to a piece of sensory information that can be communicated to the controller at each time $k$. We prove that, for a multi-dimensional Gauss-Markov process, $\text{VoI}_k$ is a symmetric function of the discrepancy between the state estimates at the event trigger and the controller, and that a data packet containing sensory information at time $k$ should be transmitted to the controller only if $\text{VoI}_k$ is nonnegative. Moreover, we discuss that $\text{VoI}_k$ can be computed with arbitrary accuracy, and that it can be approximated by a closed-form quadratic function with a performance guarantee.

This article presents a novel stochastic event-triggered communication scheme (SETS) and a switching-like H∞ control method for networked control systems (NCSs) through an open bandwidth-limited network. To overcome the stochastic Denial of Service (DoS) attacks and save the limited network resource, a SETS is first proposed to decrease the number of packets transmitted while considering the malicious DoS attacks. Compared with the existing event-triggered schemes under a precondition that all triggered packets must be successfully transmitted, the proposed SETS has outstanding flexibility since it allows part event-triggered packets to be lost during the communication process. To fully use the dynamic features of communication in an open network, a switching-like control scheme is well designed, which can actively choose the different controller gains based on the current network Quality of Services (QoSs). Then, a networked closed-loop model is constructed, which considered both the effects of SETS and stochastic DoS attacks in a unified framework. Sufficient conditions for the existence of the switching-like controller are presented to ensure the stability of the networked control system while achieving the prescribed performance index. Gain matrices of the desired switching-like controller and the SETS parameters are reached in the light of the solutions to certain matrix inequalities. Compared with the existing time-invariant control strategy in a transmission interval, higher control performance can be expected since both the dynamic network information and the latest available state are well considered in the proposed communication and control framework. Finally, an illustrative example is given to verify the effectiveness of the proposed scheme.

With the widespread adoption of Internet-of-Things (IoT) technologies, cyber-physical systems (CPSs) are facing threats from cyberattacks due to the vulnerabilities exposed in IoT devices. In this paper, we analyze the feasibility of a coordinated attack named TD-FDIA on CPS by synchronizing the time-delay attack (TDA) and false data injection attack (FDIA). It seems that the coordinated attack is more powerful than either one. But the analysis of its stealthiness and effectiveness is challenging. In the context of the networked control system, we first propose a general formulation for the impact of TD-FDIA on the system’s stability. Then, we analyze whether the combination of TDA and FDIA can destabilize the system and remain stealthy or not with different setups when the controller is with and without an observer, and the communication protocol between the controller and actuator is UDP and TCP, respectively. The conditions required to make TD-FDIA stealthy are given in some cases. Finally, we conduct extensive experiments to evaluate the impact of TDA, FDIA, and TD-FDIA on the system’s stability with two different CPS scenarios.

The main objective of the study is to investigate the Takagi-Sugeno fuzzy-model-based networked control system under the fuzzy event-triggered H ∞ control scheme. Instead of considering the conventional network transmission delay, the paper introduces the probability distribution based network transmission delay, which is more compatible with real time-simulations. Due to distributed transmission delay, the closed-loop network control system has become distributed delay system. To make use of full information about the membership function, the Lyapunov function candidate is designed as fuzzy-membership-dependent Lyapunov function. A switching concept with respect to the rate of changes in membership functions is introduced to design the optimal control gain matrices for the considered system. The main advantage of the fuzzy-membership-dependent Lyapunov function is that it can ensure the less conservatism of the result without increasing the number of decision variables. To validate the effectiveness of the proposed approach, two kinds are real-time systems are taken into account, one is nonlinear mass-spring-damper model, followed by an industrial example, say, surface mounted permanent magnet synchronous motor model. The corresponding simulation results show the superiority of the proposed results over the existing works.

In this paper, the problem of tracking control of networked control systems with false data injection attacks is studied. A new terminal integral adaptive sliding mode control method is proposed. Firstly, the mathematical model of networked control system with the actuator and sensor false data injection attacks is modeled. Secondly, an augmented state observer is designed in order to estimate the augmented states, in which, a discontinuous input term is designed to defenses the actuator attack, and the convergence of the estimation error is proved. Thirdly, the tracking output errors are introduced to design the terminal integral sliding mode control method. Furthermore, in order to reduce the oscillation induced by the sensor false data injection attack, the terminal integral adaptive sliding mode control algorithm using the estimation error as adaptive factor is structured, and the stability of the algorithm are proved by using Lyapunov theory. Finally, a numerical simulation and a practical experiment are executed to verify the superiority of proposed control strategies.

The main objective of the study is to investigate the Takagi-Sugeno fuzzy-model-based networked control system under the fuzzy event-triggered H ∞ control scheme. Instead of considering the conventional network transmission delay, the paper introduces the probability distribution based network transmission delay, which is more compatible with real time-simulations. Due to distributed transmission delay, the closed-loop network control system has become distributed delay system. To make use of full information about the membership function, the Lyapunov function candidate is designed as fuzzy-membership-dependent Lyapunov function. A switching concept with respect to the rate of changes in membership functions is introduced to design the optimal control gain matrices for the considered system. The main advantage of the fuzzy-membership-dependent Lyapunov function is that it can ensure the less conservatism of the result without increasing the number of decision variables. To validate the effectiveness of the proposed approach, two kinds are real-time systems are taken into account, one is nonlinear mass-spring-damper model, followed by an industrial example, say, surface mounted permanent magnet synchronous motor model. The corresponding simulation results show the superiority of the proposed results over the existing works.

In this paper, the resilient controller design and synthesis issues of networked control systems under denial-of-service (DoS) attacks are investigated via an adaptive event-triggered strategy. In a networked control system, DoS attacks have serious impacts on the security of communication, possibly causing degraded stability performance of the system. To remove threats from DoS attacks, an adaptive event-triggered communication mechanism is proposed, which also provides benefits in reducing the consumption of communication resources and relieving the pressure on network bandwidth. Since the system state information is usually not fully known, an observer-based controller is developed to stabilize the system and maintain a desired performance index despite the occurrence of stochastic attacks. Furthermore, a joint design method is proposed to obtain the controller gain, observer gain and event-triggered weight matrix. Finally, practical examples based on a four-tank system, an Internet-based three-tank system and an Internet-based test rig system are presented to illustrate the effectiveness of the proposed techniques to respond and eliminate the impact of DoS attacks.

In recent years, a new paradigm in control engineering, called networked control system (NCS), has emerged due to the success of internet and associated communication infrastructure. The NCS offers various advantages compared to traditional control systems which include increase of agility, wiring reduction, and easy maintenance and diagnosis. With an objective to investigate the effectiveness of various controllers in networked environment, the present study designs a -based single-bit PID controller for the rotor side converter (RSC) of a doubly-fed induction generator (DFIG) based wind energy conversion system (WECS). This consists of 20-DFIGs of 5MW capacity each. A comparative performance investigation has been carried out with three other controllers; a conventional PID, Q-Learning and Dynamic Fuzzy Q-Learning (DFQL) controller. The study considers various imperfections of a Zigbee protocol based practical communication network such as random delay and packet dropout. The results of both the simulation and experiment demonstrate that the -based single-bit PID controller shows better performance compared to other controllers.

This brief considers the analysis of networked structural control systems with measurement loss. This is modeled as a sampled-data system that integrates the discrete-time operation of the controller with a fast-sampling approximation of the continuous-time structural (plant) dynamics. Random measurement loss in each channel due to the use of the wireless transmission is modeled as a Bernoulli process. This leads to a discrete-time, Markov jump linear model for the feedback system. An H₂-norm analysis is proposed to assess the stability and the performance of the structural control. An example of a three-story building model is used to illustrate this approach. The H₂-norm results are shown to be in agreement with the numerical simulations. The analysis can, thus, be used to assess various design choices. For example, the relationship between the probability of signal loss and the H₂-norm depends on the method used to handle the signal loss. Moreover, the analysis shows that, for a jump controller setup using steady-state Kalman gains, the system can become unstable at very small probabilities of signal loss.

The interval type-2 Takagi-Sugeno (T-S) fuzzy dynamic output feedback and H-infinity stability analysis is studied for a class of networked control systems with multiple time-varying additive uncertainties, time-varying signal communication delay and external disturbance . Firstly, the interval type-2T-S fuzzy is employed to denote the system plant. Secondly, the multiple time-varying additive uncertainties are introduced in the controller design and the state variables depending on additive uncertainties. Thirdly, the delay-dependent Lyapunov-Krasovskii functional with double integral terms is designed to derive the less conservative stability conditions in terms of linear matrix inequalities (LMIs). The characteristic of the state variables are reflected effectively by employing the controller with multiple time-varying additive uncertainties. The closed-loop system is asymptotically stable with prescribed H-infinity performance index γ by employing the matrices transformation information. The less conservative stability conditions are derived and extended into the networked control system without additive uncertainties. Finally, simulations are presented to show the effectiveness of the proposed methods.

Time synchronization is an important function for networked control systems. At present, most of the time synchronization methods are based on proportional–integral controllers. These methods rely on the time offset calculated by the sampling data and are, therefore, vulnerable to sampling noise. This study introduces a stochastic search method and proposes a novel time synchronization method with antinoise ability, especially pulse noise. In this article, mathematical models of the proposed method are given, and its behavior is analyzed through simulation. The performance of the proposed method is verified by a comparative experiment, and the experiment results show that the proposed method has a faster convergence speed and better accuracy in a switched networked control system.

The robustness of process control systems to cyberattacks has become an increasingly important topic, especially in light of the increased dependence of process operations on networked control system architectures wherein dedicated sensor-controller and controller-actuator links are replaced by real-time, wired or wireless, shared communication networks. To mitigate the risks of cyberattacks, we propose in this work an integrated model-based framework for the detection, estimation and mitigation of false data injection cyberattacks in nonlinear networked process systems. The framework leverages a classification-based neural network scheme for attack detection and estimation, coupled with a stability-based attack mitigation strategy based on a model-based controller design. An illustrative chemical process example is used to demonstrate the effectiveness of the proposed framework and assess its robustness with respect to possible attack detection and estimation errors.

In this article, a predictive active disturbance rejection control (ADRC) scheme is proposed for high-precision position tracking control of servo systems with communication delays via sliding mode approach. In the proposed framework, a filtered state predictor is employed to handle time delays in the networked control system. Based on the predictive states, a linear extended state observer is used to compensate unknown perturbations for ADRC, and a boundary layer solution of the sliding mode control is applied via the internal model control rules for robust control. Since the filtered predictive scheme can compensate the time delays and alleviate the effect of the ignored high-frequency dynamics, higher control gains and observer bandwidth of the ADRC can be achieved, leading to a better position tracking accuracy of the control system in the presence of uncertainties and disturbances. The stability of the overall control system is also analyzed via the Lyapunov method. Comparative experiments were carried out to validate the superior performance of the proposed controller.

Strictly unstable linear systems under additive and nonvanishing stochastic noise with unbounded supports are known to be impossible to stabilize by using deterministically constrained control inputs. In this paper, similar impossibility results are obtained for the scenarios where the control input is probabilistically constrained and the support of the noise distribution is not necessarily unbounded. In particular, control policies that have bounded time-averaged second moments are considered. It is shown that for such control policies, there are critical average moment bounds, below which second moment stabilization of a linear stochastic system is not possible, and moreover, second moment of the state diverges regardless of the choice of control policy and the initial state distribution. Nonnegative-definite Hermitian matrices are exploited to extract sufficient instability conditions that can be assessed by using the eigenstructure of the system matrix and the distribution of the noise. The results indicate that in certain networked control system settings with noise, designing stabilizing constrained controllers is an impossible task, if the probability of successful transmissions of control commands over the network is known to be too small in average.

In this paper, the robust stability and disturbance rejection performance analysis of an energy-efficient control is addressed in the framework of Networked Control System (NCS). The control scheme under study integrates periodic event-triggered control, packet-based control, time-varying Kalman filter, dual-rate control and prediction techniques, whose design is aimed at reducing energy consumption and bandwidth usage. The robust stability against time-varying model uncertainties is analyzed by means of a sufficient condition based on Linear Matrix Inequalities (LMI). Finally, the effectiveness of the proposed approach is experimentally validated in a tracking control for an Unmanned Ground Vehicle (UGV), which is a battery-constrained mobile device with limited computation capacities.

A networked output feedback loop subject to packetized transmissions of the output signal is considered. Based on the small gain theorem, an easy‐to‐use stability criterion covering two important cases is presented. In the first case a packet numbering mechanism is employed whereas in the second case neither packet numbering nor synchronization between sender and receiver is assumed. The analysis makes use of acausal subsystems and deduces the optimal constant time delay with respect to the minimization of the ℓ2 gain due to uncertain packet delays. This additional delay is then used in a nominal controller design such that additional admissible packet delay variations introduced by the network are maximized. A simulation example of a networked control system with a filtered Smith predictor illustrates the application of the proposed criterion. It is shown that the proposed novel technique is less‐conservative than existing stability criteria based on the small gain theorem.

With the widespread application of communication networks in industrial control systems , cyber-attacks bring a huge threat to the networked control system . In this paper, the issue of secure control of nonlinear jump networked systems with false data inject (FDI) attacks is investigated. In order to against the malicious attacks , a reduced-order-asynchronous sliding-mode control (SMC) strategy is proposed. Firstly, in order to damp the effect of nonlinear term and FDI attacks, an asynchronous sliding-mode function is designed, and the resultant sliding-mode dynamics is generated by using the reduced-order method. Then, the stability conditions for the reduced-order sliding-mode dynamics are given, and the sliding-mode parameters are solved by linear matrix inequality technology. Furthermore, the sliding-mode controllers are designed under the situation of the parameters is known or unknown, respectively, and the reachability of the sliding-mode motion is certificated. Finally, two examples are implemented to illustrate the potential of the presented control strategy.

The coupling of physical systems with information technologies infrastructure in a networked control system (NCS) has a number of advantages such as remote control, reduced system complexity, low maintenance cost and improved system efficiency. But these benefits come at the cost of making the NCS vulnerable to cyberphysical attacks on the communication layer. One such class of attacks is the zero-dynamics attack (ZDA) which targets the internal dynamics of an NCS with the potential to cause serious damage to the physical system while remaining stealthy. A better understanding of how ZDAs are constructed will enable more effective countermeasures. In this paper, we discuss two approaches for constructing a ZDA and demonstrate using three industrial processes studied in this context perhaps for the first time.

This paper deals with the analysis of the stability of networked control systems (NCS). In NCS, the signal transmission between the plant and the controller is done through a communication network. Usually, this data transmission faces packet delay and dropout. Two types of NCS modeling for networks with packet dropout and one type of modeling for networks with packet delays are introduced. These models are of discrete-time switched linear types and there may be constraints on the order of the subsystems’ occurrence. The analysis will be conservative if these constraints are not taken into account. It is shown that by considering these constraints, the stability analysis will be less conservative. Both deterministic and stochastic analyses are considered and compared.

This article focuses on observer-based state feedback H ∞ control for a jacket structure against DoS attacks and external wave loads. First, a networked model of the structure is formulated as a switched delay system, in which DoS attacks and network-induced delays are considered simultaneously. A matching switched observer is developed for estimating states of the networked jacket structure system. Then, some new sufficient conditions are provided for the observer-based networked H ∞ controller for the resultant switched system. Finally, it is shown from several case studies that the provided mechanism can maintain desired performance of the jacket structure against attacks and wave loads. In addition, the developed control schemes can save the control cost significantly.

This article is concerned with the problem of observer-based dynamic event-triggered control for a networked control system (NCS) under a class of power-constrained denial-of-service (DoS) attacks that aim at impeding the network communication from time to time. First, by carefully modeling such DoS attacks as aperiodic pulse-width-modulated (PWM) jamming signals, a switching observer, adapting to the DoS attacks, is delicately constructed to deal with the unavailability of full-state information. Second, to economize the limited bandwidth resources, a dynamic event-triggered communication scheme is designed under the aperiodic DoS jamming attacks, whose duration and frequency are assumed to be restricted. Third, a switching system model with artificial state delay is formulated, which characterizes the effects of the aperiodic DoS attacks and event-triggered communication scheme in a unified framework. Then, the asymptotic stability analysis and controller/observer synthesis conditions of the resulting switching system are obtained by using a piecewise Lyapunov-Krasovskii functional approach. Furthermore, a co-design method of the dynamic triggering parameters, controller, and observer gains is presented. Finally, an example is employed to verify the effectiveness of the obtained results.

This paper deals with the problem of finite-time stabilization for the multi-rate networked control system with network-induced time delays. In order to guarantee the finite-time stability and overcome the adverse impact of network-induced time delays in both sensor-to-controller channel and controller-to-actuator channel, a networked predictive control strategy is proposed based on multi-rate sampling mechanism. By utilizing the techniques of lifting and augmenting, the augmented closed-loop system is derived with a uniform sampling rate. By applying the Lyapunov stability theorem, sufficient conditions are established such that the multi-rate networked control system can be finite-time stabilized. Furthermore, the gain matrices are determined for the observer and the controller by solving bilinear matrix inequality or linear matrix inequality. Finally, a numerical example is presented to show the validity of the obtained results.

Contribution: A 3-D interactive learning environment, from which students of different levels in the control engineering background can benefit regarding classroom demonstration and online experimentation, is present. The findings support that students can benefit from the application of the online laboratory. Background: Control system design is vital in control engineering education. Conventionally, lectures on control system design are difficult for students to comprehend. Some online laboratories can be used for remote and virtual experiments on control system design. However, little attention has been paid to the possible classroom demonstration using online laboratories. Intended Outcomes: Students in a course on control system design are expected to be able to: 1) comprehend theories and concepts better from improved classroom teaching with online interactive demonstrations; 2) customize control algorithms in after-class experimentation; and 3) tailor monitoring interfaces with rich interactive features. Application Design: Education-oriented technologies are provided to offer both remote and virtual experimental services. 3-D visualization and interaction are achieved which enable great flexibility and interactivities for users. The proportional–integral (PI) control of a remote fan speed control test rig has been used to teach the design of integral anti-windup. Teaching and learning scenarios have been demonstrated regarding students at four different levels, which can help students to comprehend different concepts in control related modules. Findings: The multiyear evaluation results show that there is an improvement in student performance with the application of Networked Control System Laboratory (NCSLab). Students obtained a higher final score in the two class modules on average. Moreover, there is a boost regarding the assessment of the two class modules.

This paper investigates the networked control system (NCS) with faults and disturbances which affect both actuator and sensor. A fast high-order sliding mode (FHOSM) controller is proposed to compensate for actuator faults and sensor disturbances, which is constructed based on the estimated information of the NCS. Accordingly, an adaptive observer with multi-stage is designed to estimate the states and sensor disturbances and protect the NCS from actuator faults. Furthermore, a new sliding function is assembled to realize the finite-time convergence of system states. The stability of the system with the suggested procedure is illustrated by the stability analysis underneath the designed control law. Finally, the simulation results are implemented and confirm the effectiveness of the proposed method in defending the system against both issues and inhibiting system failures.

The Android-based networked control system laboratory (NCSLab) is a remote control laboratory that adopts an extensible architecture, mainly including Android mobile devices, MATLAB servers, controllers and test rigs. In order to conduct various simulations and experiments more effectively in NCSLab, the first key issue that needs to be solved is to enable users to design their own control algorithms or functional blocks on the Android client, rather than just using the basic block libraries provided by the system. So, this paper proposes and implements a scheme for Android-based compilation of C-MEX S-functions. With this new feature, users can design personalized algorithm according to their requirements in the form of S-functions, which can be called and executed after being compiled by MATLAB server. Finally, through the experiment validation of the three-degree-of-freedom air bearing spacecraft platform, it is proved that the method of Android-based C-MEX S-functions is reliable and efficient, and this scheme well enhances the functionality and mobility of Android-based NCSLab.

In this article, the actuator fault estimation of a networked control system (NCS) with packet dropout is studied. First, a Markov chain is utilized to describe the packet loss behaviour. Then, the global system is modelled as a Markovian jump linear system (MJLS). Next, a proportional–integral observer is used to estimate the actuator’s fault. Sufficient conditions are written in the form of linear matrix inequality (LMI) after using the stochastic Lyapunov–Krasovskii functional. By applying matrix theory skills, we introduce some slack variables in the LMI for more relaxation. The obtained LMI has more advantages than others existing in the literature. Finally, a simulation is provided to show the validity of the proposed approach and compare the obtained results with other presented works.

The large integrated industrial applications require unified communication to combine data from multiple domains forming a hybrid network. The scheduling of network access time to multi-domain data...

For the linear discrete networked control system (NCS) which may suffer DoS attack on both sides of the controller, when the actuator has time-varying failure, the intelligent sensor unit uses wireless sensors to collect data. According to the large amount of data collected, the active fault tolerance/active passive capacity of linear discrete NCS under the discrete event-triggered communication mechanism (DETCS) is studied. The problem of cooperative controller design is discussed. Firstly, a linear discrete NCS model integrating DETCS, actuator fault, and network attack is established. Then, based on the idea of integral sliding mode control, an active fault-tolerant/attack active passive intrusion-tolerant cooperative controller is designed, and the actuator attack side network attack and sensor side network attack are extended to the state to obtain a new state vector. Then, an adaptive Kalman filter estimator (AKF) estimates the fault and attack information and then adjusts the initial fault-tolerant/intrusion-tolerant cooperative controller in real time according to the estimated information obtained by the adaptive Kalman filter estimator; finally, the MATLAB simulation example is used to verify the improvement of system performance by the designed control law and the saving of network resources by the introduction of DETCS.

In a networked control system (NCS) environment, where all closed-loop signals (control and state) are quantized, we consider the problem of establishing prescribed, transient, and steady-state, performance guarantees on the output tracking error (minimum convergence rate, maximum steady-state error). The controlled system is of high relative degree, multi-input multi-output (MIMO), uncertain, nonlinear, and time-varying. The proposed control solution is of low-complexity, in the sense that no hard calculations, analytic or numerical, are involved. Illustrative simulations clarify and verify the developed control scheme.

In this paper, a new method is presented to design a $$H_\infty$$ decentralized static output feedback controller for the load frequency control problem. A power system which includes diesel generator, wind turbine, photovoltaic panel, and battery storage in each area is considered as case study. It is assumed that all control loops of the interconnected multi-area power system are closed under network communication. Thus, a networked control system model is extended for this class of large-scale system based on a modified event-triggered scheme; which decreases the bandwidth utilization. A Wirtinger inequality, which encompasses the Jensen inequality, is used to derive less conservative synthesis conditions in terms of linear matrix inequalities. Some sufficient conditions are presented to guarantee the stability and the $$H_\infty$$ performance, based on LKF and integral estimation. Also, design of optimal output feedback controllers are based on stability conditions. The effectiveness of the proposed method is shown in simulation study for a four-area interconnected microgrid.

This article concerns the event‐triggered fuzzy filter design for Takagi‐Sugeno (T‐S) fuzzy systems subject to deception attacks under the stochastic multiple time‐varying delays. A sequen...

Using an event-based switching law, we address the stability issue for continuous-time switched affine systems in the network environment. The state-dependent switching law in terms of the region function is firstly developed. We combine the region function with the event-triggering mechanism to construct the switching law. This can provide more candidates for the selection of the next activated subsystem at each switching instant. As a result, it is possible for us to activate the appropriate subsystem to avoid the sliding motion. The Zeno behavior for the switched affine system can be naturally ruled out by guaranteeing a positive minimum inter-event time between two consecutive executions of the event-triggering threshold. Finally, two numerical examples are given to demonstrate the effectiveness of the proposed method.

This paper proposes a novel cognitive control strategy for overcoming the impacts of time-varying delay and data packet losses in networked control system. The Bernoulli distribution is used to characterize the packet losses and time-varying delay. Then, the information entropy is employed for computing the corresponding uncertainties and describe the information gap in the cognitive control. With Q-learning, PID and adaptive RBF neural networks, an improved cognitive control is designed, which is composed of three sub-controllers, i.e., cognitive controller A, PID controller and cognitive controller B. Cognitive controller A is designed with Q-learning, and cognitive controller B is designed by blending adaptive RBF neural networks with Q-learning. For an extensive analysis, the presented control methodology is compared to Q-learning-PID. The simulations show that the proposed cognitive control scheme has better robustness to packet losses and time delay than Q-learning-PID.

This study proposes a novel predictive control compensation method to deal with random time-delay in networked control system. Different from other compensation strategies, this study adopts different compensation strategies for input time-delay and output time-delay to improve the control effect. First, for the input channel time-delay, the corresponding buffer is set by the time-stamp in the packet. Combining the historical output value and the control variable, the fast implicit generalized predictive control algorithm is adopted to design the predictive controller to compensate for the input channel time-delay. Second, for the output channel time-delay, the controller cannot measure it. A control compensator is designed by adding a feedback loop. The output control variable of the predictive controller is adjusted by predicting the error between the actual control signal and the controller output at the historical sampling time, so as to compensate for the time-delay of the output channel. In addition, the stability of the proposed time-delay compensation method is analyzed. Finally, simulation and experimental results show that the proposed method has good control and compensation effect, and improves the output performance of the system. The networked control system with random time-delay is stable. Furthermore, the simulation results also show that this time-delay compensation method needs less computing time and is more suitable for the practical applications.

In this paper, two different systems, a pH process and a DC motor, are considered for networked control, where pH is a non-linear system and the DC motor is a linear system. Majority of the industr...

The optimization in the configuration of network communication with time delays among field devices is a major challenging task of a networked control system (NCS). In view with the network-based model of literature, the present paper introduces the dynamic network scheduler to customize the aperiodic time delay for optimal bandwidth allocation of the network. This is achieved with the following three objectives: (a) classification of data packets among periodic and aperiodic communication using support vectors; (b) deciding the bandwidth associated with the priority weightage for aperiodic data packets; (c) simulation for fairness of NCS with dynamic network scheduler switching integrated the weighted fair queuing algorithm. The outcome of proposed dynamic network scheduler is compared with the network model of literature for reduced and bounded delays of aperiodic communication in NCS.

The operating frequency of the networked control system (NCS) determines both its control performance and heat flux density. Considering the significant effect of thermal stress on the reliability of electronics, a quantitative reliability analysis framework is proposed for NCSs with the consideration of its operating frequency. It includes 5 main steps: 1) compute the power consumption of all its electronic components using circuit simulation; 2) obtain the thermal stress of these components by thermal simulation; 3) apply the thermal stress results to assess the reliability of components using the part stress analysis method; 4) calculate the reliability of the modules using reliability block diagrams; and 5) quantify the reliability of the NCS by combining the graph reduction method and other network reliability algorithms together. A double loop networked control system is used as an example to verify the effectiveness of our method.

In this paper, the design problem of fault detection filter for a class of networked control system subject to Markov jump parameters, randomly occurring uncertainties, sensor faults and packet dropouts by using state feedback control is investigated. The fault detection filter is used as an optimal residual generator that generates the residual signal and also guarantees the sensitivity of residual signal to the faults. To be more specific, a suitable threshold is selected for the residual evaluation function to reduce the error between the sensor faults and the residual signal. Further, by employing a fault detection technique along with output quantization approach, a new set of sufficient conditions is derived to ensure the stochastic stabilization of the addressed system with sensor faults under a predefined $$H_{\infty }$$ performance level. Particularly, by constructing Lyapunov–Krasovskii functional and utilizing extended Wirtinger-based single integral inequality, the required sufficient conditions are derived in terms of linear matrix inequalities for getting the required result. At last, two numerical examples including high alpha research vehicle model are presented to demonstrate the usefulness of our developed results.

We consider a decentralized networked control system (DNCS) consisting of a remote controller and a collection of linear plants, each associated with a local controller. Each local controller directly observes the state of its co-located plant and can inform the remote controller of the plant's state through an unreliable uplink channel. The downlink channels from the remote controller to local controllers were assumed to be perfect. The objective of the local controllers and the remote controller is to cooperatively minimize the infinite horizon time average of expected quadratic cost. The finite horizon version of this problem was solved in our prior work [2]. The optimal strategies in the finite horizon case were shown to be characterized by coupled Riccati recursions. In this paper, we show that if the link failure probabilities are below certain critical thresholds, then the coupled Riccati recursions of the finite horizon solution reach a steady state and the corresponding decentralized strategies are optimal. Above these thresholds, we show that no strategy can achieve finite cost. We exploit a connection between our DNCS Riccati recursions and the coupled Riccati recursions of an auxiliary Markov jump linear system to obtain our results. Our main results in Theorems 1 and 2 explicitly identify the critical thresholds for the link failure probabilities and the optimal decentralized control strategies when all link failure probabilities are below their thresholds., 52 pages, Submitted to IEEE Transactions on Automatic Control

In this paper, the event-triggered H∞ output tracking problem is investigated for networked control systems. In order to reduce the output tracking error as well as to improve network resource utilization, we propose an idea of dynamic compensation controller with the discrete-time event-triggered mechanism, that is, the integral term of tracking error and the state of the reference system are introduced to form states of the augmented system. We first examine the dynamic compensation idea by the H∞ output tracking control problem for linear time-invariant (LTI) systems. Then, we model the closed-loop event-triggered networked control system as a time-delay augmented linear system. By constructing a Lyapunov-Krasovskii functional with the delay fractioning technique, the stability conditions with lower conservatism are derived in the form of the linear matrix inequalities (LMIs). Furthermore, a method is proposed to design the H∞ dynamic compensation controllers and the discrete-time event-triggered mechanisms. Finally, the satellite tracking control problem is used as an example to show that the dynamical compensation idea is effective in reducing the tracking error and that the proposed method in this paper can achieve better performance than that in the existing literature.

This paper focuses on event-triggered controller design problem for a networked control system via a novel integral inequality based on Lyapounov-Krasovskii functional (LKF). Specifically, a new integral inequality is applied to bound integral term, which produces tighter bounds than some existing ones. First, take into account static quantization, a networked control system model with two successive delay components is introduced. Then, using an improved integral inequality, we obtain a less conservative stability condition, which ensures the system is asymptotically stable with a given H ∞ disturbance attention level γ in the form of linear matrix inequality. After that, the desired event-triggered controller is established using congruence conversion approach to minimize unnecessary computation and communication resource usage [9] , [45] . Finally, two simulation examples are provided to illustrate the effectiveness of the proposed new design techniques.

Balancing of load on a networked control system is an important operation in continuous process control. An unbalanced load causes overloading of a network, which results in loss of data or interru...

This paper introduces a discrete-time technique for output feedback tracking control with aperiodic sampling over networks suffering delay and dropout. Introducing the concept of pseudo sampling, N...

This article presents a novel linear active disturbance rejection control (LADRC) scheme based on internal model control (IMC) rules and extended state observer (ESO) for high-performance motion control of servo motor systems with input delay and disturbances. The standard IMC (S-IMC) scheme is employed to tune the control gains of LADRC for a specified set-point tracking, as well as a linear ESO to handle internal and external disturbances based on a nominal model. However, due to the limited bandwidth of the ESO and the input delay in the networked control system (NCS), the effect of disturbances cannot be fully eliminated, which may have a significant impact on the tracking accuracy. To overcome these deficiencies, a two-degree-of-freedom IMC scheme combined with the ESO is introduced to further improve the tracking performance. Moreover, the tracking error dynamics is analyzed through an approximation solution by using sliding variables. The theoretical results show that the uniformly ultimately bounded stability of the system can be guaranteed. Comparative experiments are conducted on a servo motor with NCS and demonstrated the effectiveness of the proposed control approach.

This paper addresses the hybrid-triggered security control design for the networked control system (NCS) under multiple cyber attacks. A hybrid-triggered scheme (HTS) is introduced to mitigate the burden of the network transmission. Besides, a new model of multiple cyber attacks is built by simultaneously considering deception attacks and DoS attacks. In addition, A novel NCS model based on multiple cyber attacks is established with the hybrid-triggered scheme. Then, based on Lyapunov stability theory, criteria for guaranteeing the closed-loop system stability and achieving hybrid-triggered security controller design are derived. Finally, an illustrative example is given to validate the usefulness of the theoretical results.