Asynchronous Sampled-data Research Articles

Fuzzy adaptive asynchronous sampled-data consensus control for nonlinear multi-agent systems under DoS attacks

This article investigates the problem of fuzzy adaptive resilient asynchronous sampled-data consensus control (SDCC) for a class of uncertain nonlinear strict-feedback multi-agent systems (MASs) under denial-of-service (DoS) attacks and with a directed graph. Firstly, the upper bounds on the sampling intervals and a distributed sampled-data observer are proposed to estimate the leader's output and its high-order derivatives under DoS attacks. Then, the sufficient conditions to ensure the asymptotic convergence of the designed distributed sampled-data observer are established. Based on the distributed sampled-data observer and backstepping control design technique, a distributed fuzzy adaptive resilient control algorithm is developed. It is proved that the proposed control scheme can guarantee that the controlled MASs are stable, and the consensus errors converge to a small neighbourhood of zero. Finally, a simulation example on heterogeneous vehicular platoons verifies the feasibility of the proposed control scheme.

Stability and Performance of Asynchronous Sampled-Data Interconnected Systems: An Integral Approach

In this paper, we focus on the stability of asynchronous sampled-data interconnected systems and the evaluation of how asynchronous sampling and time delays degrade the <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> gains from exogenous inputs to controlled outputs. To judge the stability and evaluate the performance of systems, an integral approach is proposed and it combines a revised form of ISS (input-to-state stability) Lyapunov conditions with an integral description of bounded measurement errors. Practical procedures for the application of the approach are further presented. In the case with shared sampling periods, a time-translation approach is introduced to investigate the relationship between asynchronous sampling and time delays.

Asynchronous Sampled-Data Controller Design for Switched Markov Jump Systems and Its Applications

This article is dedicated to design asynchronous aperiodic sampled-data controller for a class of Markov jump systems with switching transition rate. The sampling controller corresponding switching transition rate matrix mode is not synchronized with the system corresponding switching transition rate matrix mode due to the possible switching of the transfer rate matrix in the sampling interval. With the help of T–S fuzzy models, the state-space representation of the system is turned into a fuzzy Itô stochastic switched Markov jump systems. By constructing novel Lyapunov functionals, mean square exponential stability criteria, and dissipativity criteria are presented. Furthermore, an asynchronous aperiodic sampled-data controller is designed for fuzzy Itô stochastic Markov jump systems. At last, by fuzzing the nonlinear tunnel diode circuit model and nonlinear mass-spring-damper mechanical model, the effectiveness and lower conservativeness of the proposed method are illustrated.

Novel Equalities for Stability Analysis of Asynchronous Sampled-Data Systems

This paper is concerned with the stability analysis problems of asynchronous sampled-data systems with use of a input-delay approach, where a sampled-data system can be reformulated into a time-delay system having incremental delays. For these systems, this paper introduces a new looped-functional to utilize both integral states and their interval-normalized ones. Utilization of these two types of integral state variables in a construction of stability conditions has been effective in reducing the conservatism. Further, generalized equalities are proposed for the case utilizing these two types of integral states. The sampled-data system formulation consists of a sampled state, a system state and its derivative. Here, the sampled state between two consecutive sampling instants is a constant value and thus can be eliminated by an integration with Legendre polynomials of positive degrees. Consequently, the system formulation turns into the equalities consisting of state variables, sampled-state variables, integral state variables and their interval-normalized ones without additional slack matrices. Based on the proposed equalities, a large computational burden can be reduced while reducing the conservatism. The effectiveness of the proposed approaches is demonstrated via three numerical examples for the stability analysis of asynchronous sampled-data systems.

Distributed Tracking in Heterogeneous Networks With Asynchronous Sampled-Data Control

This article investigates distributed coordinated tracking problems of networked heterogeneous systems. Based on asynchronous sampling information, distributed sampled-data protocols are employed to realize leader-following synchronization and containment tracking in networked heterogeneous systems. In asynchronous sampled-data protocols, each node has different sampling instants with other nodes and only samples itself information at its own sampling instants. By utilizing the input-delay approach and Lyapunove–Krasovskii functional approach, some sufficient conditions for guaranteeing the coordinated tracking are presented. First, quasi-synchronization criteria are obtained for networked heterogeneous oscillator systems with a dynamic leader over the directed graph. Second, in the presence of multiple heterogeneous leaders for networked heterogeneous systems, sufficient conditions of quasi-containment tracking are derived. In a word, all followers can converge into a bounded level of convex hull spanned by the leader(s). The upper bounds of tracking errors are estimated for both quasi-synchronization and quasi-containment tracking. Finally, two numerical examples are given to verify the theoretical results.

Leader-Following Consensus for Linear Multiagent Systems via Asynchronous Sampled-Data Control

In this article, we consider the sampled-data leader-following consensus problem for a class of general linear multiagent systems over both static directed networks and switching directed networks. A distributed asynchronous sampled-data state feedback control law is proposed. We show by Lyapunov analysis that the problem can be solved by the proposed control law as long as the sampling periods of all agents are smaller than a given threshold, which can be explicitly calculated. An example is given to illustrate the effectiveness of our approach.

Robustness Analysis of Asynchronous Sampled-Data Multiagent Networks With Time-Varying Delays

In this paper, we study the simultaneous stability problem of a finite number of locally interconnected linear subsystems under practical constraints, including asynchronous and aperiodic sampling, time-varying delays, and measurement errors. We establish a new Lyapunov-based stability result for such a decentralized system. This system has a particular simple structure of interconnections, but it captures some key characteristics of a large class of intermediate models derived from the consensus analysis of multiagent systems. The asynchrony of aperiodic sampling and the existence of measurement errors allow the utilization of some kinds of quantizing devices, such as Logarithmic quantizers, in the process of data sampling, and allow the introduction of a period of dwell time after each update of state measurement to eliminate the Zeno behavior of events in event-based control. The stability result is applicable to the estimation of the maximum allowable intersampling periods and time delays based on individual dynamics and coupling structures in the scenarios of consensus control via asynchronous sampling of relative states and asynchronous broadcasting of self-sampled states, respectively.

Distributed optimization of multi-agent systems with delayed sampled-data

Abstract In this paper, we study the distributed optimization problem of multi-agent systems with delayed sampled-data, where the interconnected topology is directed, weighted-balanced and strongly connected, and also local cost functions are strongly convex with globally Lipschitz gradients. Based on synchronous and asynchronous sampled-data, we construct two respective algorithms. Our main results, sufficient conditions for the convergence to an optimal solution, are obtained under assumption that all design parameters are chosen properly. We also present one example to validate our theoretical results.

Asynchronous sampled-data approach for event-triggered systems

ABSTRACTWhile aperiodically triggered network control systems save a considerable amount of communication bandwidth, they also pose challenges such as coupling between control and event-condition design, optimisation of the available resources such as control, communication and computation power, and time-delays due to computation and communication network. With this motivation, the paper presents separate designs of control and event-triggering mechanism, thus simplifying the overall analysis, asynchronous linear quadratic Gaussian controller which tackles delays and aperiodic nature of transmissions, and a novel event mechanism which compares the cost of the aperiodic system against a reference periodic implementation. The proposed scheme is simulated on a linearised wind turbine model for pitch angle control and the results show significant improvement against the periodic counterpart.

Formula omitted]∞ and LQG control of asynchronous sampled-data systems

A class of dual-rate sampled-data systems is considered, where the sampling rate is asynchronously related to the rate at which the hold element is operating. Such asynchronous sampled-data systems are aperiodic, and hence the lifting technique, which is used to represent synchronous sampled-data systems as single-rate discrete systems, cannot be applied to the asynchronous case. In this study, optimal H ∞ and LQG controllers for asynchronous sampled-data systems are derived using a two-Riccati equation approach, which does not rely on the lifting method. A distribution theorem is used to evaluate the optimal stationary performance levels in the two cases.

Optimal H∞ and LQG Control of Asynchronous Sampled Data Systems

A class of dual-rate sampled-data systems is considered, where the sampling rate is asynchronously related to the rate at which the hold element is operating- Such asynchronous sampled-data systems are aperiodic, and hence the lifting technique, which is used to represent synchronous sampled-data systems as single-rate discrete systems, cannot be applied to the asynchronous case. In this study optimal H∞ and LQG controllers for asynchronous sampled-data systems are derived using a two-Riccati equation approach which does not rely on the lifting method. A distribution theorem is used to evaluate the optimal stationary performance levels in the two cases.