Home

Iasson Karafyllis

  1. Global stabilization of nonlinear systems based on vector control lyapunov functions.

    Fri, 01/13/2012 - 15:01 — SomNambul
    Authors: Iasson Karafyllis, Zhong-Ping Jiang
    Subjects: Optimization and Control
    Abstract

    This paper studies the use of vector Lyapunov functions for the design of
    globally stabilizing feedback laws for nonlinear systems. Recent results on
    vector Lyapunov functions are utilized. The main result of the paper shows that
    the existence of a vector control Lyapunov function is a necessary and
    sufficient condition for the existence of a smooth globally stabilizing
    feedback. Applications to nonlinear systems are provided: simple and easily
    checkable sufficient conditions are proposed to guarantee the existence of a
    smooth globally stabilizing feedback law.

  2. Global Exponential Observers for Two Classes of Nonlinear Systems.

    Fri, 11/04/2011 - 15:01 — SomNambul
    Authors: Iasson Karafyllis, Costas Kravaris
    Subjects: Optimization and Control
    Abstract

    This paper develops sufficient conditions for the existence of global
    exponential observers for two classes of nonlinear systems: (i) the class of
    systems with a globally asymptotically stable compact set, and (ii) the class
    of systems that evolve on an open set. In the first class, the derived
    continuous-time observer also leads to the construction of a robust global
    sampled-data exponential observer, under additional conditions.

  3. A Short Note for the Robustness Properties of Hybrid Dead-Beat Observers.

    Mon, 02/21/2011 - 16:01 — SomNambul
    Authors: Iasson Karafyllis, Zhong-Ping Jiang
    Subjects: Optimization and Control
    Abstract

    A discussion of the robustness properties of the proposed observer with
    respect to measurement errors is provided for the recently proposed full-order
    and reduced-order, hybrid, dead-beat observer for a class of nonlinear systems,
    linear in the unmeasured states.

  4. Reduced Order Dead-Beat Observers for a Bioreactor.

    Mon, 06/28/2010 - 15:01 — SomNambul
    Authors: Iasson Karafyllis, Zhong-Ping Jiang
    Subjects: Optimization and Control
    Abstract

    This paper studies the strong observability property and the reduced-order
    dead-beat observer design problem for a continuous bioreactor. New
    relationships between coexistence and strong observability, and checkable
    sufficient conditions for strong observability, are established for a chemostat
    with two competing microbial species. Furthermore, the dynamic output feedback
    stabilization problem is solved for the case of one species.

  5. New Results in Trajectory-Based Small-Gain with Application to the Stabilization of a Chemostat.

    Thu, 02/25/2010 - 16:01 — SomNambul
    Authors: Iasson Karafyllis, Zhong-Ping Jiang
    Subjects: Optimization and Control
    Abstract

    New trajectory-based small-gain results are obtained for nonlinear feedback
    systems under relaxed assumptions. Specifically, during a transient period, the
    solutions of the feedback system may not satisfy some key inequalities that
    previous small-gain results usually utilize to prove stability properties. The
    results allow the application of the small-gain perspective to various systems
    which satisfy less demanding stability notions than the Input-to-Output
    Stability property.

  6. Nash Equilibrium and Robust Stability in Dynamic Games: A Small-Gain Perspective.

    Tue, 01/12/2010 - 16:01 — SomNambul
    Authors: Iasson Karafyllis, Zhong-Ping Jiang, George Athanasiou
    Subjects: Dynamical Systems
    Abstract

    This paper develops a novel methodology to study robust stability properties
    of Nash equilibrium points in dynamic games. Small-gain techniques in modern
    mathematical control theory are used for the first time to derive conditions
    guaranteeing uniqueness and global asymptotic stability of Nash equilibrium
    point for economic models described by functional difference equations.
    Specification to a Cournot oligopoly game is studied in detail to demonstrate
    the power of the proposed methodology.

  7. Stabilization by Means of Approximate Predictors for Systems with Delayed Input.

    Wed, 10/21/2009 - 14:15 — SomNambul
    Authors: Iasson Karafyllis
    Subjects: Optimization and Control
    Abstract

    Sufficient conditions for global stabilization of nonlinear systems with
    delayed input by means of approximate predictors are presented. An approximate
    predictor is a mapping which approximates the exact values of the stabilizing
    input for the corresponding system with no delay. A systematic procedure for
    the construction of approximate predictors is provided for globally Lipschitz
    systems. The resulting stabilizing feedback can be implemented by means of a
    dynamic distributed delay feedback law. Illustrating examples show the
    efficiency of the proposed control strategy.

  8. Stabilization by Means of Approximate Predictors for Systems with Delayed Input.

    Wed, 10/21/2009 - 14:15 — SomNambul
    Authors: Iasson Karafyllis
    Subjects: Optimization and Control
    Abstract

    Sufficient conditions for global stabilization of nonlinear systems with
    delayed input by means of approximate predictors are presented. An approximate
    predictor is a mapping which approximates the exact values of the stabilizing
    input for the corresponding system with no delay. A systematic procedure for
    the construction of approximate predictors is provided for globally Lipschitz
    systems. The resulting stabilizing feedback can be implemented by means of a
    dynamic distributed delay feedback law. Illustrating examples show the
    efficiency of the proposed control strategy.

Math-arch

Syndicate content