Stability Of Networked Control Systems Research Articles

Emulation-based stabilization for networked control systems with stochastic channels

This paper studies the stabilization problem of networked control systems (NCSs) with random packet dropouts caused by stochastic channels. To describe the effects of stochastic channels on the information transmission, the transmission times are assumed to be deterministic, whereas the packet transmission is assumed to be random. We first propose a stochastic scheduling protocol to model random packet dropouts, and address the properties of the proposed stochastic scheduling protocol. The proposed scheduling protocol provides a unified modelling framework for a general class of random packet dropouts due to different stochastic channels. Next, the proposed scheduling protocol is embedded into the closed-loop system, which leads to a stochastic hybrid model for NCSs with random packet dropouts. Based on this stochastic hybrid model, we follow the emulation approach to establish sufficient conditions to guarantee uniform global asymptotical stability in probability. In particular, an upper bound on the maximally allowable transmission interval is derived explicitly for all stochastic protocols satisfying Lyapunov conditions that guarantee uniform global asymptotic stability in probability. Finally, two numerical examples are presented to demonstrate the derived results.

Sampled-data stabilization for networked control systems under deception attack and the transmission delay

For the stability analysis and stabilization synthesis problems, this paper considers networked control systems (NCSs) with the transmission delay and the deception attack under aperiodic samplings, where the deception attack and its activation function are represented as a sector bound function and a random variable with Bernoulli distribution, respectively. This paper proposes the stability and stabilization criteria for the NCSs by constructing Lyapunov–Krasovskii (L–K) functionals with continuous functionals and looped-functionals. Compared with the literature, the proposed continuous functionals take into account the mixed delay including the transmission delay and the maximum allowable sampling interval, as well as the augmented vector and integral terms. Also, the proposed looped-functionals construct two augmented vectors with integral vectors that are zeros at t=tk and t=tk+1, respectively. By utilizing these two augmented vectors, the looped-functionals fully utilize the sampling patterns compared with the literature. Based on the proposed L–K functionals, this paper derives not only the stability criterion for the NCSs with the transmission delay, but also the stabilization criterion for the NCSs with the transmission delay and the deception attack in terms of linear matrix inequalities (LMIs), respectively. Numerical example demonstrates the validity of the proposed approach.

Dynamic quantization‐driven stability of networked control systems under DoS attacks

AbstractThis paper focuses on the stability problem of networked control systems (NCSs) under denial‐of‐service (DoS) attacks and bandwidth limitation. Firstly, the periodic dynamic quantization mechanism is extended to insecure systems, and a periodic‐like quantization strategy is proposed. Due to the designable period, such mechanism allows a trade‐off between better system performance and less energy consumption. With finite quantization levels, a reasonable parametric design is given to avoid quantizer saturation under general energy‐constrained DoS attacks. Secondly, a suitable quantized controller is designed for the system affected by DoS attacks. The relationship between the quantized controller and the DoS attacks is analyzed, and the criterion for NCSs achieving global asymptotic stability is derived. Finally, two numerical examples are given to verify the correctness of the theoretical result.

Resilient control for networked control systems with dynamic quantization and DoS attacks

AbstractIn this article, the resilient control for networked control systems in the presence of denial‐of‐service (DoS) attacks is investigated in a sampled‐data and dynamic quantization scheme. A novel dynamic quantization strategy is designed for signal transmissions from encoding systems to decoding systems, in which the quantized states are transmitted through networks with a risk of DoS attacks. An estimator is introduced to the design of control laws. Some sufficient conditions in terms of quantization levels, DoS attack duration and frequencies are given for the asymptotic stability of networked control systems. Furthermore, an event‐triggered communication scheme is designed for signal transmissions in control channels to reduce network resource consumption. The Zeno behavior is excluded in the designed event‐triggered communication scheme. The quantization levels can be adaptively adjusted according to real‐time situations. Finally, the effectiveness of the proposed strategy is illustrated by simulations.

Security event‐triggered control for uncertain NCSs against multi‐channel optimal jamming attacks

AbstractThis article proposes an event‐triggering mechanism (ETM)‐based security control strategy for an uncertain networked control system (NCS) to cope with jamming attacks on multiple transmission channels. A structure of the system control block for the attacked uncertain NCS is constructed and a virtual system is designed to cope with the mismatched parametric uncertainty and derive both the optimal control gain and the virtual control gain. Under multiple wireless channels jamming attack, an optimal jamming attack strategy that maximizes the attack power from the attacker's point of view is engineered. Furthermore, an ETM‐based control strategy with jamming parameters is designed to ensure the input‐to‐state stability of NCS under uncertainty and jamming attacks. Finally, the numerical simulation results show the effectiveness of the control algorithm in this article.

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

This paper is concerned with the stabilization of networked control systems (NCSs) under multi-packet transmission and denial of service (DoS) attacks. To deal with node congestions and DoS attacks, a jump-like try-once-discard (TOD) protocol is first proposed to orchestrate the priority of normal nodes and the attacked nodes over the network. Compared with the existing TOD scheduling, the proposed scheduling scheme has the advantage of jumping out the attacked nodes by designing node weighting matrices. To reduce the effects of DoS attacks, an attack-model-independent impulsive closed-loop model is well established, which couples the effects of the proposed protocol and DoS attacks in a unified framework. Then, a sufficient attack-model-independent stabilization criterion is derived. Compared with the existing attack-model-dependent methods, the desired dynamic output feedback performance is well guaranteed under multi-channel time-varying DoS attacks. Finally, an illustrative example is used to verify the effectiveness of proposed method.

Networked control system stability analysis of pipeline system with networked-induced delay

This paper presents the design of Networked Control Systems (NCS) for pipeline systems. NCS plays an important role in controlling and monitoring large-scale systems such as pipeline systems. To implement the NCS, one must derive the pipe model and consider the network communication constraints. Here, the pipeline model is divided into two sections for simplicity. For example, in a long pipeline system, one can use a higher number of sections in order to give a better result for the analysis. Then let’s consider a networked-induced delay as the network communication constraint. The discretize pipe dynamics model is derived to support the NCS scheme in the pipeline system. The stability analysis of the proposed NCS is derived by taking into account the small and the large networked-induced delay. Then the optimal LQR control is designed for both stabilizing and tracking. The stability region of the pipeline system in the NCS scheme with networked-induced delay is derived and depicted to provide stability information. The design of the proposed controller under network constraint (networked-induced delay) must consider the stability plot that is divided into the stable region and unstable region. In this research, let’s assume that it is possible to measure the exact time delay and then consider the allowable sampling time for the controller. The proposed controller is designed by considering the NCS scheme with time delay both for regulator and tracking problems. By using the proposed controller, the pipeline system can be controlled in the presence of network-induced delay, which commonly occurs in a distributed system. The simulation verifies the stability analysis of the proposed optimal control for the pipeline systems with the NCS scheme under networked induced delay

Stability of networked control systems: A Lyapunov–Krasovskii functional plus approach

This paper is concerned with stability for networked control systems with a transmission delay and data packet dropouts. A hybrid model is formulated for the networked control systems to separate the constant delay and data packet dropouts, and a stability theorem is established for the hybrid model. Based on the stability theorem, a Lyapunov–Krasovskii functional plus (LKFP) approach is proposed to revolutionize the normal Lyapunov–Krasovskii functional approach. By fully employing the system information to construct an LKFP and by exploiting integral equations of the hybrid model to deal with the derivative of the LKFP, new stability results are obtained. Finally, numerical examples illustrate that the stability results are of less conservatism than some existing ones.

Dynamic output feedback robust [formula omitted] control of networked control systems with time-Varying delays via T-S fuzzy models

This paper addresses the problem of robust stabilization for networked control systems (NCS) where the stochastic behavior of the network does not allow correct and complete transmission of data to both the actuators and the controller. The objective is to model the NCS using Takagi-Sugeno (T-S) fuzzy systems with uncertainties and external disturbances and to design a time-varying delay fuzzy controller such that the closed-loop system is robustly exponentially stable with a prescribed decay rate. Sufficient conditions are derived using the delay-dependent Lyapunov-Krasovskii functional with a robust H∞ controller in terms of linear matrix inequalities (LMIs). Accordingly, desired fuzzy controllers are designed by using feasible solutions to the obtained LMIs. The proposed fuzzy controller can keep the T-S fuzzy system stable in the presence of time-varying delay, uncertainties, and external disturbance. Two numerical examples with different conditions on parameters are provided to illustrate the performance and robustness of the proposed approach.

Relaxed stability analysis and sampled-data controller design for networked control systems with network-induced delays

This paper is devoted to the stability analysis and sampled-data controller design problem for networked control systems subject to network-induced delays. The objective is to provide relaxed conditions in terms of linear matrix inequalities. Indeed, reducing the conservatism of such conditions allows to maximize the admissible range of the network-induced delays. To do so, an augmented Lyapunov–Krasovskii functional is proposed, which involves a novel augmented state vector to include as much as possible the information from the time-varying network-induced delay into the stability conditions, together with the use of extended Wirtinger-based inequalities, an extended reciprocal convexity approach and the Finsler’s lemma. Then, declined from the proposed stability conditions, new relaxed delay-dependent conditions for the design of networked sampled-data controllers are proposed. These allow to obtain simultaneously the controller gains and the maximal allowable bound of the network-induced delays with regards to its lower bound. Three illustrative examples are provided to show the effectiveness of the proposed networked control systems stability and controller design conditions, as well as to highlight the so raised conservatism improvements regarding the previous relevant results from the literature.

Decentralized dynamic event‐triggered control for networked control systems under unreliable communication network and actuator saturation

AbstractIn this paper, the stochastic stability of networked control systems (NCSs) with nonlinear perturbation and parameter uncertainties is studied. A decentralized dynamic event triggering scheme (DDETS) is introduced to reduce energy consumption and network transmission burden. Each channel can decide whether to transmit signals sampled by corresponding sensors through this mechanism. Due to the unreliability of communication network, a new mathematical model of NCSs based on multi‐channel fading and hybrid cyber attacks is established, and the actuator is constrained by saturation. A sufficient condition for stochastic stability based on static controller is derived through Lyapunov stability theory, and two numerical examples are given to demonstrate the effectiveness of the method.

Output‐based event‐triggered control of networked systems subject to bilateral packet dropouts

In this paper, an output‐based event‐triggered control problem of discrete‐time networked control systems (NCSs) subject to bilateral packet dropouts is investigated. In view of stochastic sequences of packet dropouts in the measurement channels (from sensors to controller) and the control channels (from controller to actuators), the NCS is converted into a closed‐loop stochastic parameter system. In the aid of a Lyapunov functional based on stochastic variables, the sufficient conditions on design of a dynamic output feedback control law and bilateral event‐triggering conditions are derived to guarantee the exponentially mean‐square stability for NCSs. Furthermore, an improved iterative algorithm is given to obtain the output‐based control law and event‐triggering parameters from a set of nonconvex inequalities. Finally, a numerical example and the corresponding simulation results are given to illustrate the validity and applicability of the developed techniques.

Strong γc - γcl H∞ Stabilization for Networked Control System Based on Lyapunov Function and DoS Attacks

This paper is concerned with the strong γc - γcl H∞ stabilization for networked control system under DoS attacks with limited communication bandwidths. The quantizer is employed to the network transmission channel from sensor-to-controller in order to reduce the unnecessary data transmissions. In the network environment, it is assumed that there exist DoS attacks in the transmission channel from controller-to-actuator. By describing DoS attacks as the probability models subject to the Bernoulli distribution, the network control system is modeled as the system with random parameters. With this model, a dynamic output feedback controller is designed, which satisfies the given H∞ bound norm γc . Under the action of the controller, the closed-loop system is exponential stable in the mean-square sense and satisfies H∞ bound norm γcl . Especially, a Lyapunov function based on quantization error and attack probability is proposed in the stability analysis. Finally, the effectiveness of the proposed method is verified by a simulation example.

Event-triggered stabilization for networked control systems under random occurring deception attacks.

This paper copes with event-triggered stabilization for networked control systems subject to deception attacks. A new switched event-triggered scheme (ETS) is designed by introducing a term regarding the last triggering moment in the trigger condition. This increases the difficulty of triggering, thus reducing trigger times compared to some existing ETSs. Furthermore, to cater for actual deception attack behavior, the occurrence of deception attacks is assumed to be a time-dependent stochastic variable that obeys the Bernoulli distribution with probability uncertainty. By means of a piecewise-defined Lyapunov function, a sufficient condition is developed to assure that the close-loop system under deception attacks is exponentially stable in regards to mean square. On the basis of this, a joint design of the desired trigger and feedback-gain matrices is presented. Finally, a simulation example is given to confirm the validity of the design method.

On Stability of Network Control Systems with Switching Transmission Probabilities

The paper addresses modeling, stability analysis, and control of a class of networked control systems, in which the communication network, and thus the probability for successful transmission of sensor data, varies over time. This variation is modeled probabilistically by Markov chains with time-varying transition probabilities. The offline synthesis of output feedback controllers for this system class is addressed with focus on criteria for mean square stability.

Event-triggered fuzzy control for nonlinear time-delay system with full-state constraints and unknown hysteresis

This article considers the nonlinear time-delay system with full-state constrains and actuator hysteresis. Compared with the previous research on input hysteresis phenomenon, all states in the system are required to be constrained in a bounded compact set and the direction of hysteresis is unknown. Thus, the system is difficult to be stabilized and get perfect error tracking performance, and the design procedure is more complicated. By combining barrier Lyapunov functions (BLFs) and Nussbaum functions, a new virtual controller is designed, which combines the properties of Nussbaum function with fuzzy logic systems (FLSs). Furthermore, considering that the rate-dependent characteristic of actuator hysteresis will adversely affect the stability of networked control systems (NCSs), a first-order filter is used to solve the problem, but it brings challenges to the design of Lyapunov–Krasovskii functions (KLFs). Thus, a new LKFs is constructed to compensate for the adverse effects of state delay on the nonlinear system. What’s more, this article propose event-triggered technique to solve the coupling effect of the system communication resource constrains. The proposed adaptive control strategy ensures the boundedness of all signals and does not violate the state constraints, and the controller avoids Zeno behavior, and the tracking error fluctuates around zero in a predetermined compression range. Finally, two simulations results verify the effectiveness of the adaptive control strategy.

Reducing Conservatism in Analysis of Networked Control Systems Using Order Constraints

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.

Stability analysis of networked control systems under DoS attacks in frequency domain via game theory strategy

In this paper, the stability analysis of networked control systems (NCSs) under Denial-of-Service (DoS) attacks is studied. Firstly, the stability analysis for NCSs free of DoS attacks is investigated. Considering the DoS attacks, the game theory is introduced to establish the non-cooperative game between defender and attacker of NCSs. At the same time, the stability of NCSs is analysed in frequency domain, and the signal-to-noise ratio (SNR) expression is given by using spectral decomposition technique and Nash equilibrium (NE) strategy. The packet dropout phenomenon caused by DoS attacks is described by Bernoulli distribution. By virtue of the NE strategy, the stability of NCSs can be optimised. In the obtained results, the influence of the traditional constraints and DoS attacks is illustrated. Finally, some numerical examples are given to show the effectiveness of the derived theoretical results.

Hierarchical type stability and stabilization of networked control systems with event-triggered mechanism via canonical Bessel–Legendre inequalities

This paper is studied with the hierarchical type stability and stabilization of networked control systems (NCSs) with event-triggered mechanism (ETM). In the cause of reducing the amount of data transmission and saving the limited network bandwidth, ETM is introduced into NCSs, and the closed-loop time-delay NCSs model with ETM is presented. An improved Lyapunov–Krasovskii functional (LKF), containing delay-product-type terms and being appropriate for the canonical BesselLegendre inequality (BLI), is first constructed. Then, by utilizing the canonical BLI and the extended reciprocally convex matrix inequality (ERCMI) to deal with the single integral terms of the derivative of LKF, a sufficient condition on asymptotically stable is derived for NCSs. Based on above N-dependent stability criteria, a co-design method is developed, which can be capable of calculating the control gain of controller and the weighting matrix of the ETM. Finally, the feasibility and superiority of the results are verified by two examples.

Design of Networked Secure and Real-Time Control Based on Blockchain Techniques

The security of data propagation is a critical challengefor the widespread use of networked control systems (NCSs), while the conventional strategies based on estimation techniques cannot solve this issue well. Furthermore, the contradiction between the security and the real-time nature of the control method has not been settled yet. The aim of this article is to propose a novel real-time control method empowered by blockchain technologies to resolve the security problems of NCSs under potential cyberattacks. To facilitate the analysis of blockchain-assisted NCSs, a cyber-authentic-physical system (CAPS) framework is proposed. One of the significant features of the CAPS is that the defense of NCSs against attacks is built by introducing a blockchain protocol. Theoretical analysis reveals the relationship among the scale of the peer-to-peer network, the security of the CAPS, and the latency of NCSs, as well as clarifies the impact of the introduction of the blockchain mechanism on the performance of NCSs. With the networked secure control mechanism designed in this article, the security and stability of NCSs can be achieved simultaneously, and their sufficient conditions are also given. Finally, simulations and practical experiments are presented to show the efficacy of the suggested secure control strategy.