Search

This work addresses the output feedback stabilisation problem for a class of linear single-input single-output systems subject to I/O network delays. More precisely, we are interested in the characterisation of the set of delay and gain parameters guaranteeing the stability of the closed-loop system. To perform such an analysis, we adopt aneigenvalue perturbationbased approach. Various illustrative numerical examples complete the presentation. [ABSTRACT FROM PUBLISHER]

This article deals with the robust control design problem for linear time invariant systems affected by variable feedback delay. Constraints on the system state are considered in the system description. The starting point is the construction of a predictive control law which guarantees the existence of a nonempty robust positive invariant (RPI) set with respect to the closed-loop dynamics. Subsequently, an iterative algorithm is proposed in order to obtain an approximation of the maximal RPI set. The problem can be treated in the framework of piecewise affine systems due to the explicit formulations of the control law obtained via multiparametric programming. [ABSTRACT FROM AUTHOR]

This article addresses three stability problems related to networked-control systems (NCSs) with periodic scheduling, where control systems may have multiple samplings in a hyperperiod (a hyperperiod is a periodically repeated scheduling sequence for all tasks in an NCS). As expected, the analysis of a system with multiple samplings is much richer than the case with single sampling. For example, a system with two samplings may be stable (unstable) even if it is unstable (stable) when sampled by either sampling. In this context, it is important to understand how network-induced delays and multiple samplings affect the system's stability. In this article, three particular stability problems involving constant and/or time-varying parameters are investigated, and the corresponding stability regions are derived. Numerical examples and various discussions complete the presentation. [ABSTRACT FROM AUTHOR]

This article focuses on the stabilisation problem of fluid-flow delay models of transmission control protocol/active queue management (TCP/AQM) networks by using a proportional-integral (PI) controller as AQM strategy. More precisely, the complete set of PI controllers that exponentially stabilises the corresponding linear time-delay system is derived. Using the particular geometric properties of this set of the controller parameters, the issues of robustness to uncertainty in the network parameters and to perturbation in the controller coefficients are addressed. Then, a methodology to compute a non-fragile PI AQM controller is provided. Finally, exponential estimates for the closed-loop system solutions, allowing to evaluate the performance of the corresponding PI-controlled closed-loop system, are proposed by using a Lyapunov-Krasovskii functional approach. An illustrative example completes the presentation. [ABSTRACT FROM AUTHOR]

In this paper, we propose a synchronization scheme to achieve a high level of consistency in peer-to-peer-based shared virtual environments (SVEs), as well as to display natural and realistic motions of virtual objects, in collaborative haptic tasks. The synchronization scheme utilizes an advanced feedback controller to compensate for the state error between geographically separated sites with a significant amount of time delay. It is designed using the mathematical model of a two-user SVE manipulating a freely moving object represented as a mass with damping resistance, with a haptic interface. Thanks to feedback control theory of time delay systems, the controller is shown to result in closed-loop stability and is be robust to perturbations in the time delay. Together with the synchronization control, a recovery filter is also designed and integrated so as to preserve the natural behavior of the synchronized object, which is, otherwise, affected by the feedback control action. In addition to verifying the theoretical results, two experiments using real Internet and local area network communications are carried out. These tests clearly support the validity of the analyses and demonstrate the applicability of the synchronization scheme. [ABSTRACT FROM AUTHOR]

The stability problem for systems with distributed delay is considered using discretized Lyapunov functional. The coefficients associated with the distributed delay are assumed to be piecewise constant, and the discretization mesh may be non-uniform. The resulting stability criteria are written in the form of linear matrix inequality. Numerical examples are also provided to illustrate the effectiveness of the method. The basic idea can be extended to a more general setting with more involved formulation. [ABSTRACT FROM AUTHOR]

This paper focuses on the stability analysis of a class of neutral linear systems. Some sufficient delay-dependent stability conditions are derived in terms of an appropriate model transformation of the original system, transformation similar to the one used in the retarded case. The analysis makes use of an appropriate construction of a degenerate Lyapunov-Krasovskii functional. Several computational schemes and frequency-domain interpretations, as well as an example are also presented. [ABSTRACT FROM AUTHOR]

This paper focuses on 'mixed' delay-independent/delay-dependent asymptotic stability problems of a class of linear systems described by delay-differential equations involving several constant but unknown delays. We give some sufficient conditions for characterizing unbounded stability regions in the delays parameter space. The proposed approach makes use of some appropriate Liapunov-Krasovskii functionals, and the results obtained are expressed in terms of matrix inequalities. We also discuss several ways to construct such analytic functionals. These results allow us to recover (or to improve) as limit cases previous delay-independent or/and delay-dependent conditions from the control literature. [ABSTRACT FROM AUTHOR]