Successive Packet Dropouts Research Articles

Dynamic Periodic Event-Triggered Control for Networked Control Systems Under Packet Dropouts

This article presents a co-design method of dynamic periodic event-triggering mechanism (DPETM) and output-based control law for networked control systems (NCSs) subject to inevitable imperfections such as limited network resources, exogenous disturbances and successive packet dropouts. The developed DPETM has the potential to make full use of scarce network resources compared to the periodic sampled-data control on the one hand, and is natural for practical digital platforms instead of a discretized version of continuous event-triggered control (CETC) one the other hand. In this paper, the whole closed-loop system is modeled a unified hybrid system by incorporating bilateral DPETM, successive packet dropouts effects and external disturbances, and an improved hybrid Lyapunov function is constructed for stability analysis. Based on the hybrid framework, some sufficient conditions are presented to guarantee <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\mathcal{L}_2$</tex-math> </inline-formula> -stability of the system while tolerating a maximum allowable number of successive packet dropouts (MANSD). Furthermore, new linear matrix inequality (LMI) conditions for co-design of control law and triggering strategy are derived by introducing some constraints with the free variables and a modified Young’s inequality. In addition, this paper considers two scenarios relating to whether an acknowledgment scheme is employed or not. Finally, the effectiveness of the proposed method is verified by two illustrated examples and comparative studies. <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">Note to Practitioners</i> —With the increasing requirement for reducing unnecessary waste of communication resources in modern industries, it is necessary to consider an alternative paradigm of the time-triggered control. In many digital control applications such as smart power grid, vehicle and remote surgery, the control tasks are often executed periodically, which makes it difficult for the theoretical results of CETC to be directly applied to practical digital platforms. The DPETM proposed in this paper, which only verifies the triggering conditions periodically at each sampling instant, is more suitable for practical digital platforms such as time-sliced embedded architectures compared to CETC. This paper investigates the stability problem for NCSs with DPETM subject to packet dropouts. Different from most of the existing literature on randomness of packet loss, this paper focuses on impact of the continuity of packet dropouts on system performance. Based on the hybrid framework and the Lyapunov approach, a co-design methodology of triggering condition and control law is proposed to ensure that the system satisfies the desired performance and can admit a MANSD.

Output-Based Dynamic Event-Triggered Control for Networked Control Systems With Delays and Packet Losses Without Acknowledgements

Event-triggered control (ETC) has been proposed in the networked control systems (NCSs) literature to reduce the need of data transmissions, and the main focus has been on the design of ETC mechanisms with a guaranteed positive minimum of inter-event time (MIET) and hence avoiding Zeno phenomena. In this paper, we propose a design of an aperiodic ETC mechanism for general nonlinear NCSs. In our setup, the communication network could introduce variable transmission delays, while data packets could get lost without acknowledgements. For this, we first introduce auxiliary variables dependent upon the transmission situations to capture the relationship between the number of successive packet dropouts, MIETs, transmission delays and the number of successful packets being transmitted. Meanwhile, by designing appropriate jump rules of these variables, the changing process of the network-induced errors can be tracked. Then, we present a novel output-based dynamic ETC strategy that can simultaneously guarantee a finite <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$L_{p}$</tex-math></inline-formula> -gain and a strictly positive lower bound despite the presence of packet losses and transmission delays. In particular, the mandatory limit of short delays can be avoided, and the transmission delays exceeding the positive MIETs are allowed. Finally, a numerical example is given to verify the correctness and effectiveness of the proposed control approach.

Periodic event-triggered dynamic output feedback control for networked control systems subject to packet dropouts

This paper proposes a co-design method of dynamic output feedback control law and periodic event-triggered control (PETC) strategy to tolerate a maximum allowable number of successive packet dropouts (MANSDs) in networked control systems (NCSs). For the purpose of striking a balance between saving limited communication resources and reducing complexity of the transmission implementation, we present the periodic event-triggering mechanism (PETM), in which the triggering conditions only needs to be monitored at each event-verifying instant. In NCSs, packets often suffer from some interference in network transmission, such as packet losses. For packet dropouts, we introduce a dropout variable and model the whole closed-loop systems as a hybrid system. Furthermore, some stability conditions for co-design are given by a novel Lyapunov function and stability theorems of hybrid systems, and the explicit designs parameters of controller and triggering conditions are presented to ensure L2 stability. Finally, two illustrated examples are given to show the effectiveness of the proposed design methods.

Data‐driven control for networked systems with multiple packet dropouts

AbstractThis paper investigates data‐driven control for a class of networked control systems with multiple packet dropouts and unknown system parameters. Here, multiple packet dropouts occur randomly in the controller‐to‐actuator (C/A) and sensor‐to‐controller (S/C) channels, where successive packet dropouts are limited by known upper bounds. By introducing the summation inequality, a model‐based mean‐square asymptotic stability condition is established for the closed‐loop networked control system with the potential to migrate to a data‐driven solution. Then, the data‐driven mean‐square asymptotic stability condition for the closed‐loop system is presented by merging the model‐based stability condition with noisy data‐parameterized representations. On this basis, the data‐driven controller gain design approaches for combining unknown and known input gain matrices are presented in turn. Finally, two simulation examples are provided to show the applicability of the developed approaches.

Variance-constrained Distributed H∞ Filtering for Nonlinear Systems with Successive Packet Dropouts Over Wireless Sensor Networks

Variance-constrained Distributed H∞ Filtering for Nonlinear Systems with Successive Packet Dropouts Over Wireless Sensor Networks

Stabilization of Sampled-Data Systems With Noisy Sampling Intervals and Packet Dropouts via a Discrete-Time Approach

In real-world applications, sampled-data systems are often subject to undesirable physical constraints, which results in noisy sampling intervals that fluctuate around an ideal sampling period based on certain probability distribution. In the presence of noisy sampling intervals, this article is concerned with the stabilization problem for a class of sampled-data systems with successive packet dropouts. First, the relationship between two adjacent update times of zero-order hold is established. Then, by discrete-time approach, an equivalent discrete-time stochastic system is introduced. By the law of total expectation, together with confluent Vandermonde matrix, convolution formula, and Kronecker product operation, the mathematical expectation of a product of three matrices, including the system matrix and its transpose, is calculated. Based on this, a stabilization controller is designed such that the closed-loop system is stochastically stable. Finally, an illustrative example is provided to verify the effectiveness of the proposed design approach.

A Hybrid Controller for DOS-Resilient String-Stable Vehicle Platoons

This paper deals with the design of resilient Cooperative Adaptive Cruise Control (CACC) for homogeneous vehicle platoons in which communication is vulnerable to Denial-of-Service (DOS) attacks. We consider DOS attacks as consecutive packet dropouts. We present a controller tuning procedure based on linear matrix inequalities (LMI) that maximizes the resiliency to DOS attacks, while guaranteeing performance and string stability. The design procedure returns controller gains and gives a lower bound on the maximum allowable number of successive packet dropouts. A numerical example is employed to illustrate the effectiveness of the proposed approach.

Uniform Quantized Synchronization for Chaotic Neural Networks with Successive Packet Dropouts

AbstractIn this paper, the problem of uniform quantized synchronization is investigated for chaotic neural networks with packet dropouts. By means of the stochastic analysis approach and inequality technique, sufficient conditions are derived under which the synchronization error system is exponentially ultimately bounded in mean square. Finally, a numerical example is provided to validate the feasibility and effectiveness of the proposed results.

Event-triggered resilient filtering with stochastic uncertainties and successive packet dropouts via variance-constrained approach

In this paper, we discuss the event-triggered resilient filtering problem for a class of time-varying systems subject to stochastic uncertainties and successive packet dropouts. The event-triggered mechanism is employed with hope to reduce the communication burden and save network resources. The stochastic uncertainties are considered to describe the modelling errors and the phenomenon of successive packet dropouts is characterized by a random variable obeying the Bernoulli distribution. The aim of the paper is to provide a resilient event-based filtering approach for addressed time-varying systems such that, for all stochastic uncertainties, successive packet dropouts and filter gain perturbation, an optimized upper bound of the filtering error covariance is obtained by designing the filter gain. Finally, simulations are provided to demonstrate the effectiveness of the proposed robust optimal filtering strategy.

Event-triggered control systems under packet losses

Networked control systems (NCSs) offer many benefits in terms of increased flexibility and maintainability but might also suffer from inevitable imperfections such as packet dropouts and limited communications resources. In this paper, (static and dynamic) event-triggered control (ETC) strategies are proposed that aim at reducing the utilization of communication resources while guaranteeing desired stability and performance criteria and a strictly positive lower bound on the inter-event times despite the presence of packet losses. For the packet losses, we consider both configurations with an acknowledgement scheme (as, e.g., in the transmission control protocol (TCP)) and without an acknowledgement scheme (as, e.g., in the user diagram protocol (UDP)). The proposed design methodology will be illustrated by means of a numerical example which reveals tradeoffs between the maximum allowable number of successive packet dropouts, (minimum and average) inter-event times and Lp-gains of the closed-loop NCS.

Finite-horizon H∞ filtering for switched time-varying stochastic systems with random sensor nonlinearities and packet dropouts

This paper is concerned with the finite-horizon H∞ filtering problem for a class of switched time-varying systems with state-dependent stochastic disturbances. The system outputs are subject to randomly occurring sensor nonlinearities and successive packet dropouts. Attention is focused on the design of a mode-dependent asynchronous time-varying filter such that the prescribed weighted H∞ performance requirement can be achieved under the average dwell-time switching. By utilizing the piecewise function approach and stochastic analysis technique, sufficient conditions are first established to ensure the existence of the desired finite-horizon asynchronous H∞ filter. Then, the explicit characterization of the filter gains is presented in terms of the solutions to certain recursive linear matrix inequalities. Finally, the effectiveness of the proposed filtering scheme is illustrated via a simulation example.

Distributed state estimation for periodic systems with sensor nonlinearities and successive packet dropouts

In this paper, distributed state estimators are designed for periodic systems with sensor nonlinearities and successive packet dropouts. In consideration of large quantity of sensor work in harsh environment, the sensor nonlinearities are considered. By using the Bernoulli processes, a new model is introduced to describe the randomly occurred packet dropouts in transmission of neighbors’ information. In terms of property of periodic systems, N-periodic distributed state estimators are proposed to estimate the target plant. Then sufficient conditions are established to ensure that the augmented estimation error system is globally asymptotically stable with the prescribed l2−l∞ performance index γ in average sense. Finally, a numerical example is utilized to illustrate the effectiveness of the proposed new method.

RobustH∞control for networked systems with transmission delays and successive packet dropouts under stochastic sampling

Summary This paper is concerned with the H∞ performance analysis for networked control systems with transmission delays and successive packet dropouts under stochastic sampling. The parameter uncertainties are time-varying norm-bounded and appear in both the state and input matrices. If packet loss is considered the same as time delay, when models the networked control systems with successive packet dropouts and delays as ordinary linear system with input-delay approach, due to sampling period is stochastic, then the delay caused by packet losses is a stochastic variable, which leads to difficulties in the stability analysis of the considered system. However, if we can transform the system with stochastic delay into a continuous system with stochastic parameter, we can solve the problem. In this paper, by assuming that the network packet loss rate and employing the information of probabilistic distribution of the time delays, the stochastic sampling system is transformed into a continuous-time model with stochastic variable, which satisfies a Bernoulli distribution. By linear matrix inequality approach, sufficient conditions are obtained, which guarantee the robust mean-square exponential stability of the system with an H∞ performance. What's more, an H∞ controller design procedure is then proposed, and a less conservative result is obtained by taking the probability into consideration. Finally, a numerical simulation example is employed to show the effectiveness of the obtained results. Copyright © 2016 John Wiley & Sons, Ltd.

Output-Feedback Control for Nonlinear Stochastic Systems With Successive Packet Dropouts and Uniform Quantization Effects

In this paper, the dynamic output-feedback control problem is studied for a class of discrete-time nonlinear stochastic systems with successive packet dropouts and uniform quantization effects. The stochastic system under investigation involves state-, control-, and disturbance-dependent noises (also called ( ${x}$ , ${u}$ , ${v}$ )-dependent noises) that bring in substantial difficulties in the stability analysis. The phenomenon of successive packet dropouts is governed by a binary switching random sequence. The measurement output is subject to the uniform quantization which results in the norm-bounded disturbances, and the concept of input-to-state stability in probability is introduced to deal with this kind of disturbances. In virtue of intensive stochastic analysis, several sufficient conditions are established to guarantee that the closed-loop system is input-to-state stable in probability under the effects of probabilistic packet dropouts as well as uniform quantizations. As an easy consequence, the design problem with linear output-feedback controllers is discussed for the benefits of practical applications and some simplified conditions are derived. Finally, a numerical example is presented to illustrate the effectiveness of the proposed method.

Fault detection for switched positive systems under successive packet dropouts with application to the Leslie matrix model

SummaryIn this paper, the problem of fault detection filter design is dealt with for a class of switched positive systems with packet dropouts on the channel between the sensors and the filters. The phenomena of packet dropouts are governed by a Bernoulli process, and a stochastic switched positive system is established based on the augmented states of the plants and filters. Two criteria are developed to evaluate the performance of the fault detection for the system under investigation. Sufficient conditions are established on the existence of the desired filters for the mean‐square stability with an L1 disturbance attenuation level, and an index for the L− fault sensitivity is also derived through constructing a switched Lyapunov function in term of linear programming. Two illustrative examples, one of which is concerned with the Leslie matrix model, are provided to show the effectiveness and applicability of the proposed results. Copyright © 2015 John Wiley &amp; Sons, Ltd.

Observer-based [formula omitted] fuzzy control for nonlinear stochastic systems with multiplicative noise and successive packet dropouts

In this paper, the observer-based H∞ control problem is investigated for a class of T–S fuzzy nonlinear stochastic systems with multiplicative noise and successive packet dropouts. The stochastic system under study is subject to state- and disturbance-dependent noises, and the successive packet dropouts are assumed to obey the Bernoulli random binary distribution. By employing the stochastic analysis approach, a sufficient condition is derived such that the closed-loop system is stochastically stable, and the prescribed H∞ disturbance-rejection-attenuation performance is also achieved. Moreover, the observer-based H∞ fuzzy controller design method is proposed in terms of linear matrix inequalities for the systems with successive packet dropouts. Finally, a numerical example is exploited to demonstrate the effectiveness of the obtained results.

Robust H ∞ state feedback control of NCSs with Poisson noise and successive packet dropouts

This paper examines various constraints of networked control systems (NCSs) such as network-induced random delays, successive packet dropouts and Poisson noise. Time delays are represented as modes of Markov chain and successive packet dropouts are modeled using Poisson probability distribution. For each delay-mode, a separate Poisson distribution is used with the help of an indicator function. Poisson noise is incorporated in the design to cater sudden network link failures and power shutdowns. After modeling these constraints, a stability criterion is proposed by using Lyapunov-Krasovskii functional. On the basis of the stability criteria, sufficient conditions for the existence of a robust H ∞ state feedback controller are given in terms of bilinear matrix inequalities (BMIs). Later, BMIs are converted into quasi-convex linear matrix inequalities (LMIs) and are solved by using a cone complementarity linearizing algorithm. The effectiveness of the proposed scheme is elaborated with the help of two simulation examples. Moreover, the effects of successive packet dropouts and Poisson noise on H ∞ performance are analyzed.

H∞fault estimation with randomly occurring uncertainties, quantization effects and successive packet dropouts: The finite-horizon case

In this paper, the finite-horizon H∞ fault estimation problem is investigated for a class of uncertain nonlinear time-varying systems subject to multiple stochastic delays. The randomly occurring uncertainties (ROUs) enter into the system due to the random fluctuations of network conditions. The measured output is quantized by a logarithmic quantizer before being transmitted to the fault estimator. Also, successive packet dropouts (SPDs) happen when the quantized signals are transmitted through an unreliable network medium. Three mutually independent sets of Bernoulli-distributed white sequences are introduced to govern the multiple stochastic delays, ROUs and SPDs. By employing the stochastic analysis approach, some sufficient conditions are established for the desired finite-horizon fault estimator to achieve the specified H∞ performance. The time-varying parameters of the fault estimator are obtained by solving a set of recursive linear matrix inequalities. Finally, an illustrative numerical example is provided to show the effectiveness of the proposed fault estimation approach. Copyright © 2014 John Wiley & Sons, Ltd.

H∞ fault estimation with randomly occurring uncertainties, quantization effects and successive packet dropouts: The finite-horizon case

Summary In this paper, the finite-horizon H∞ fault estimation problem is investigated for a class of uncertain nonlinear time-varying systems subject to multiple stochastic delays. The randomly occurring uncertainties (ROUs) enter into the system due to the random fluctuations of network conditions. The measured output is quantized by a logarithmic quantizer before being transmitted to the fault estimator. Also, successive packet dropouts (SPDs) happen when the quantized signals are transmitted through an unreliable network medium. Three mutually independent sets of Bernoulli-distributed white sequences are introduced to govern the multiple stochastic delays, ROUs and SPDs. By employing the stochastic analysis approach, some sufficient conditions are established for the desired finite-horizon fault estimator to achieve the specified H∞ performance. The time-varying parameters of the fault estimator are obtained by solving a set of recursive linear matrix inequalities. Finally, an illustrative numerical example is provided to show the effectiveness of the proposed fault estimation approach. Copyright © 2014 John Wiley & Sons, Ltd.

Robust state estimation for discrete-time neural networks with mixed time-delays, linear fractional uncertainties and successive packet dropouts

This paper is concerned with the robust state estimation problem for a class of discrete-time delayed neural networks with linear fractional uncertainties (LFUs) and successive packet dropouts (SPDs). The mixed time delays (MTDs) consisting of both discrete time-delays and infinite distributed delays enter into the model of the addressed neural networks. A Bernoulli distributed white sequence with a known conditional probability is introduced to govern the random occurrence of the SPDs. The main purpose of the problem under consideration is to design a state estimator such that the dynamics of the estimation error is globally asymptotically stable in the mean square. By using stochastic analysis and Lyapunov stability theory, the desired state estimator is designed to be robust against LFUs and SPDs. Finally, a simulation example is provided to show the effectiveness of the proposed state estimator design scheme.