Successive Packet Losses Research Articles

Leader-Following Sampled-Data Consensus of Multiagent Systems With Successive Packet Losses and Stochastic Sampling.

In practical applications, sampled-data systems are often affected by unforeseen physical constraints that cause the sampling interval to deviate from the expected value and fluctuate according to a certain probability distribution. This probability distribution can be determined in advance through statistical analysis. Taking into account this stochastic sampling interval, this article focuses on addressing the leader-following sampled-data consensus problem for linear multiagent systems (MASs) with successive packet losses. First, the relationship of the equivalent sampling interval between two successive update instants is established, taking into account the double randomness introduced by both SPLs and stochastic sampling. Then, the equivalent discrete-time MAS is obtained, and the overall leader-following consensus problem is formulated as a stochastic stability problem of the equivalent system by incorporating the sampled-data consensus protocol and properties of the Laplacian matrix. Based on the equivalent the discrete-time system, a consensus criterion is derived under a directed graph by using the Lyapunov theory and leveraging a vectorization technique. By the introduction of a matrix reconstruction approach, the mathematical expectation of a product of three matrices, including the system matrix and its transpose, can be determined. Then, the consensus protocol gain is designed. Finally, an example is provided to validate our theoretical results.

Sampled-Data H∞ Dynamic Output-Feedback Control for NCSs With Successive Packet Losses and Stochastic Sampling.

The problem of sampled-data H∞ dynamic output-feedback control for networked control systems with successive packet losses (SPLs) and stochastic sampling is investigated in this article. The aim of using sampled-data control techniques is to alleviate network congestion. SPLs that occur in the sensor-to-controller (S-C) and controller-to-actuator (C-A) channels are modeled using a packet loss model. Additionally, it is assumed that stochastic sampling follows a Bernoulli distribution. A model is established to capture the stochastic characteristics of both the SPL model and stochastic sampling. This model is crucial as it allows us to determine the probability distribution of the sampling interval between successive update instants, which is essential for stability analysis. An exponential mean-square stability condition for the constructed equivalent discrete-time stochastic system, which also guarantees the prescribed H∞ performance, is established by incorporating probability theory. The desired controller is designed using a step-by-step synthesis approach, which may offer lower design conservatism compared to some existing methods. Finally, our designed approach using a networked F-404 engine system model is validated and its merits relative to existing results are discussed. The proposed method is finally validated by employing a networked model of the F-404 engine system. Furthermore, the advantages of our method are presented in comparison to previous results.

Quantized Sampled-Data Stabilization for Nonlinear NCSs Subject to Successive Packet Losses and Probabilistic Sampling

Quantized Sampled-Data Stabilization for Nonlinear NCSs Subject to Successive Packet Losses and Probabilistic Sampling

Hybrid Event-Triggered Cooperative Output Regulation of Multiagent Systems With Unreliable Communication Link.

This article studies the event-triggered cooperative output regulation problem of heterogeneous multiagent systems with external disturbances and unreliable communication link (i.e., packet losses occur intermittently). A novel hybrid event-triggering mechanism (ETM) is proposed, which imposes a strictly positive lower bound for triggering intervals, and an internal variable with jump dynamics is introduced to design triggering condition. A hybrid model is constructed to describe the closed-loop system with both flow and jump dynamics. Then, based on the hybrid model, Lyapunov-based consensus analysis, hybrid ETM design, and robust performance analysis results are developed. Compared with the existing results, the minimum triggering interval (MTI) can be prespecified, and Zeno behavior is ensured to be excluded no matter there exist disturbances or not, which is useful for control implementation. Besides, the packet losses are allowed to be nonidentical, that covers identical packet losses as a special case. Moreover, the tradeoff between MTI and the number of maximum-allowable successive packet losses is explicitly given. Finally, simulation results are provided to show the effectiveness of the proposed method.

Security Control of Sampled-Data T–S Fuzzy Systems Subject to Cyberattacks and Successive Packet Losses

This article investigates the security control problem of sampled-data Takagi–Sugeno (T–S) fuzzy systems subject to cyberattacks and successive packet losses. The cyberattack considered in this article is a stochastic deception attack. The packet losses under consideration occur in the sensor-to-controller and controller-to-actor channels, both of which are modeled as two independent Bernoulli processes. On this basis, a novel successive packet loss modeling method is proposed with some basic assumptions. By the exact discrete-time model approach, a discretized sampled-data T–S fuzzy model is first established by considering the probability characteristic of the deception attacks and successive packet losses in a unified framework. Based on the established mode, the sufficient conditions to guarantee the security degree are derived by the Lyapunov function approach. Furthermore, the fuzzy security controller is designed in view of linear matrix inequalities. Finally, a benchmark example is given to show the validity of the proposed approach.

A Hybrid Systems Approach to Event-Triggered Consensus of Multiagent Systems With Packet Losses

This article addresses the event-triggered consensus problem of multiagent systems (MASs) with packet losses. The packet losses are not restricted to be identical, and a hybrid systems framework is proposed to handle the considered problem with or without leader in a unified framework. Distributed control law is constructed based on an estimator, whose dynamics are related to whether packet losses occur. A novel hybrid event-triggering mechanism (ETM) is proposed, and a lower bound of the interevent times is enforced to guarantee Zeno-freeness. For stability analysis, a unified hybrid model is constructed to describe the dynamics of MAS with or without leader. In accordance to this model, how to design the hybrid ETM and consensus analysis are formally developed, and the maximum allowable successive packet losses can be explicitly computed. Moreover, even if there exist nonlinearities and disturbances in system dynamics, and the leader has nonzero input, the proposed method can still be applied. Finally, examples are provided to illustrate the superiority of the proposed method.

Stabilization Analysis for Linear Disturbed Event-Triggered Control System With Packet Losses

Based on an event-triggered control strategy, the stabilization of a linear system with disturbance is the purpose of this article. In this article, we first introduce a newfangled event-triggered control with a linear diffusive term and discontinuous sign term. Then, a class of event-triggered conditions, whose threshold contains a constant term and a sampled state term, is provided for guaranteeing the stability of a disturbed linear system. The event could be directly triggered to change the control information by violating the event-triggered condition when packet losses during control information transmission are defaulting. This means that event-triggered control can markedly economize on resource waste and communication cost. In addition, the interexecution time, which is determined by the event-triggered condition, is proved to have a uniform positive lower bound to guarantee that Zeno behavior does not occur. In the presence of packet losses, we estimate the maximum allowable number of successive packet losses to maintain the desired performance of the system. Finally, the validity of the theoretical results is substantiated by an example.

Synchronization of Complex Dynamical Networks Subject to Noisy Sampling Interval and Packet Loss.

This article focuses on the sampled-data synchronization issue for a class of complex dynamical networks (CDNs) subject to noisy sampling intervals and successive packet losses. The sampling intervals are subject to noisy perturbations, and categorical distribution is used to characterize the sampling errors of noisy sampling intervals. By means of the input delay approach, the CDN under consideration is first converted into a delay system with delayed input subject to dual randomness and probability distribution characteristic. To verify the probability distribution characteristic of the delayed input, a novel characterization method is proposed, which is not the same as that of some existing literature. Based on this, a unified framework is then established. By recurring to the techniques of stochastic analysis, a probability-distribution-dependent controller is designed to guarantee the mean-square exponential synchronization of the error dynamical network. Subsequently, a special model is considered where only the lower and upper bounds of delayed input are utilized. Finally, to verify the analysis results and testify the effectiveness and superiority of the designed synchronization algorithm, a numerical example and an example using Chua's circuit are given.

Robust LFC of Power Systems With Wind Power Under Packet Losses and Communication Delays

Network-induced packet losses and communication delays, as well as load fluctuations and uncertain wind power have a negative effect on the frequency regulation of power system. This paper is concerned with designing a robust load frequency control (LFC) scheme for a multi-area power system penetrated by wind power via sampled-data control. Firstly, considering the effects of the inertia reduction, packet losses, communication delays and measurement noise, a decentralized aperiodic sampled-data LFC model with time delay is constructed, where the maximum sampling interval is characterized by limiting the maximum count of successive packet losses (MCSPL). Secondly, by applying Lyapunov theory and linear matrix inequality technique, a new exponential stability condition for the modeled LFC system with given controller is proposed based on a combination method of Lyapunov-Krasovskii functional and loop function, which is dependent on delay and MCSPL. It can be used to find the delay margin and allowable MCSPL of the LFC system. Thirdly, based on the <inline-formula> <tex-math notation="LaTeX">$\mathcal {L}_{2}$ </tex-math></inline-formula>-gain performance condition developed by the stability condition above, a design method of robust PI-type controller is proposed by maximizing an exponential decay rate (EDR). The larger EDR, the faster frequency response speed to cope with the effect of inertia reduction, but the worse robustness to load fluctuations, packet losses and delays, and vice versa. Finally, case studies are carried out by a one-area power system and a three-area power system with wind power. By comparing with the existing LFC schemes, simulation results show that the proposed LFC scheme for the tested system is more effective and has better robustness.

Sampled-Data Leaderless and Leader-Following Consensus of Multiagent Systems Under Nonidentical Packet Losses

In this work, the leaderless and leader-following consensus problems are investigated for multiagent systems (MAS) with asynchronous sampling mechanism and nonidentical packet losses. First, distributed sampled-data control protocols are proposed based on estimators, the estimator's state is updated according to whether packet losses occur in certain communication channel. Then, by defining appropriate consensus error variables and by means of internal auxiliary variables, a unified hybrid model consisting of flow dynamics and jump dynamics is constructed for both leaderless and leader-following MAS, such that leaderless and leader-following consensus of MAS can be dealt with in a unified framework. Based on this model, a hybrid system approach is proposed for stability analysis and linear matrix inequality based stability conditions are derived. The interaction relationship among sampling period, the number of successive packet losses, and design parameters is explicitly characterized. The effectiveness of the proposed method is illustrated via numerical simulation.

Output regulation for networked switched systems with alternate event-triggered control under transmission delays and packet losses

This paper is concerned with the event-triggered output regulation problem for a class of linear networked switched systems (NSSs). A mode-dependent alternate event-triggered mechanism (AETM) is integrated into the NSSs with transmission delays and packet losses for the first time based on continuous detection and periodic sampling, and a joint-designed switching signal with the triggering information is presented. Under transmission delays and packet losses, a series of resultant error feedback controllers are synthesized in four cases based on the relationships between switching instants and event-triggered instants. Then, a criterion ensuring asynchronous output regulation performance is formed with transmission delays by the input delay method. With the presence of packet losses, a set of sufficient conditions is also dedicated to the proposed control issue by adding the restraint in the number of successive packet losses associated with a modified AETM. Eventually, a comparison and an F-18 aircraft model reveal the effectiveness of the obtained results in the simulation.

Formula omitted]-gain analysis for dynamic event-triggered networked control systems with packet losses and quantization

The problem of event-triggered output feedback control for networked control systems (NCSs) with packet losses and quantization is addressed. A new dynamic quantization scheme is proposed to prevent saturation of the quantizer in the presence of external disturbances, and using the emulation-based approach, we show how to design the event-triggering conditions to guarantee the L2-gain performance of the overall system. To cope with the successive packet losses and the dynamic quantization, the NCS is embedded into a hybrid dynamical system, which is capable of describing these dynamics. Then, a novel Lyapunov function type is constructed to analyze the L2-gain performance with the quantization and packet dropout effects. Furthermore, owing to the proposed method, the Zeno phenomenon resulting from the transmission instants and updates of quantizer are prevented by introducing a minimum inter-event time. Finally, a numerical simulation is introduced to demonstrate the feasibility of the proposed design approach.

A discretization approach to sampled‐data stabilization of networked systems with successive packet losses

AbstractThis article is concerned with the stabilization problem for a class of networked systems subject to successive packet losses. Different from the input delay approach used in some existing literature, the continuous‐time system under consideration is first converted into a discrete‐time stochastic system with system matrices subject to stochastic characteristic. In order to deal with the difficulties in the calculations of mathematical expectations of both matrix exponential and integral of matrix exponential function, the upper bound of successive packet losses and packet drop rate are assumed to be known and then the probabilities of the number of successive packet losses taking each value in a bounded set are calculated. Based on this, stability criteria are derived by recurring to the law of total expectation, which guarantee the exponential mean‐square stability of resulting closed‐loop discrete‐time stochastic system with a prescribed H∞ performance. Moreover, a controller design procedure is then proposed. Finally, to verify the analysis results and testify the effectiveness and applicability of the designed algorithm, a numerical simulation example is given.

A New Approach to Characterize Successive Packet Losses in Stochastic Networked Systems

In this paper, we discuss the modeling and stabilization problems for a class of discrete-time stochastic networked systems (DSNSs) subject to successive packet losses. The system under consideration is transformed into a stochastic one with bounded stochastic delay. Considering that the stochastic delay is characterized by nonuniform distribution, a new equivalent model is then constructed that enables the DSNS’s controller design to benefit from knowing the probability characteristic of packet losses. Specially, to verify this feature, the probabilities of the delay can be explicitly obtained by utilizing the formula of total probability, which is critical to model transformation and analyze practical problems that exist in DSNSs. Based on the proposed model, sufficient conditions are established under which the globally mean-square asymptotic stability of resulting stochastic delay closed-loop system is guaranteed, and a delay-distribution-dependent design procedure is then proposed. A numerical example with simulation is provided to validate the analytical results and demonstrate the effectiveness of the design procedure.

Asynchronous distributed localization in networks with communication delays and packet losses

This paper studies the problem of determining sensor locations in a large sensor network using only relative distance (range) measurement. Based on the barycentric coordinate representation, we propose a totally asynchronous distributed algorithm under DILOC framework due to independence of sensor update instants and unreliable networks with communication delays and packet losses. Through modeling the asynchronous algorithm as a linear difference equation with time-varying delays, we prove that the location estimates of sensors are globally convergent to the true coordinates if: (1) time interval between any two consecutive update instants is bounded from below and above, (2) communication delays and successive packet losses between sensors are finite. Simulation examples are provided to demonstrate the effectiveness of the theoretical result.

Event-triggered control of discrete-time switched linear systems with packet losses

The event-triggered control problem for discrete-time switched linear systems with packet losses is addressed in this paper. It is assumed that, at each event-triggered instant transmitted successfully, the controller can only access the transmitted information of system state and mode. In both cases of packet losses and no packet losses, mode dependent event-triggered transmission schemes are proposed. And the closed-loop system is modeled as a switched system with augmented switching signal. Then, based on the multiple Lyapunov function method, in the case of packet losses, exponential stability conditions are given with constraint of the maximum allowable number of successive packet losses, and design methods for state feedback controller gains and mode dependent event-triggered parameters are obtained. Finally, the effectiveness and improvement of the proposed approach are illustrated by a numerical example.

Adaptive event-triggered control of a class of nonlinear networked systems

This paper investigates an adaptive event-triggered communication scheme (AETCS) for a class of networked Takagi–Sugeno (T–S) fuzzy control systems. The threshold of event-triggering condition has great influence on the maximum allowable number of successive packet losses. Different from the conventional method, the threshold, in this study, is dependent on a novel adaptive law which can be achieved on-line rather than a predefined constant, since the threshold with fixed value is hard to suit the variation of the system. The stability and stabilization criteria are derived by using a new Lyapunov function. Finally, an example is provided to demonstrate the design method.

Asynchronous event-triggered control of multi-agent systems with Sigma–Delta quantizer and packet losses

This paper investigates the consensus problem for event-triggered multi-agent systems (MAS) subject to external disturbances, time delays and packet losses as well as Sigma–Delta (ΣΔ) quantizer who has a finite number of quantization level simultaneously. Firstly, we transform this problem into a robust H∞ control by defining an appropriate controlled output. Secondly, we give a criteria to judge the consensusability of asynchronous event-triggered MAS and present a sufficient condition in terms of matrix inequalities to get the state feedback controller׳s parameters. Moreover, the maximal allowable number of successive packet losses is also given, and the algorithm designed here has made considerable contributions to save communication resources. Finally, numerical examples are given to show the effectiveness of the proposed consensus protocol.

Event-triggered control for networked control systems with quantization and packet losses

Problems of the quantized stabilization for event-triggered networked control systems (NCSs) with packet losses are addressed. To reduce the communication resources in NCSs, event-triggering scheme is adopted and designed. A NCS model is proposed which considers quantization, plant uncertainty, event-triggering scheme and packet losses simultaneously. Sufficient conditions for the stabilization and control design are derived using the Lyapunov functional approach and control synthesis of event-triggered networked control systems are established in terms of linear matrix inequalities. Moreover, the maximal allowable number of successive packet losses in NCS is estimated. A numerical example is given to illustrate the effectiveness of the proposed method.

Packet-Level Layer-Based Interleaving Unequal Forward Error Correction (LIU-FEC) for Robust Wireless Scalable Video Transmission

To improve the error resilience and video quality over wireless networks, we propose a novel packet-level layer-based interleaving unequal forward error correction (LIU-FEC) method. First, a scalable layer-based interleaving architecture is proposed for improving the efficiency of FEC from successive packet losses in variable channel conditions. The interleaved transmission across different scalable layers can efficiently disperse the consecutive packet losses into different scalable layers. Second, a closed form FEC assignment solution is proposed for minimizing video quality degradation using simple layer-based error propagation metric in hierarchical prediction structure. The simulation results show that the proposed algorithm offers higher PSNR values in various channel status, compared to the conventional FEC algorithm.