Electrical and Electronic Engineering - Research Publications
Permanent URI for this collection
Search Results
1 - 10 of 123
-
ItemStability properties of reset systems(Elsevier, 2005-01-01)Stability properties for a class of reset systems, such as systems containing a Clegg integrator, are investigated. We present Lyapunov based results for verifying L2 and exponential stability of reset systems. Our results generalize the available results in the literature and can be easily modified to cover Lp stability for arbitrary p ∈ [1;∞]. Several examples illustrate that introducing resets in a linear system may reduce the L2 gain if the reset controller parameters are carefully tuned.
-
ItemNonlinear sampled-data observer design via approximate discrete-time models and emulation(International Federation of Automatic Control, 2005)We study observer design for sampled-data nonlinear systems using two approaches: (i) the observer is designed via an approximate discrete-time model of the plant; (ii) the observer is designed based on the continuous-time plant model and then discretized for sampled-data implementation (emulation). In each case we present Lyapunov conditions under which the observer design guarantees semiglobal practical convergence for the unknown exact discrete-time model. The semiglobal region of attraction is expanded by decreasing the sampling period. The practical convergence set is shrunk by decreasing either the sampling period, or a modelling parameter which refines the accuracy of the approximate model.
-
ItemConditions for uniform boundedness of parameterized discrete-time cascades(ACPA Asian Control Professors' Association, 2004)A framework for controller design of sampled-data nonlinear systems via their approximate discrete-time models has been established recently. Within this framework naturally arises the need to investigate stability properties of parameterized discrete time systems. Further results that guarantee ap propriate stability of the parameterized family of discrete-time systems that is used within this framework have been also established for systems with cascaded structure. A fundamental condition that is required in this framework is uniform boundedness of solutions of the cascade. However, this is difficult to check in general. In this paper we provide a range of sufficient conditions for uniform boundedness that are easier to check. These results further contribute to the toolbox for controller design of sampled-data nonlinear systems via their approximate discrete-time models.
-
ItemL-2 anti-windup for linear dead-time systems(IEEE, 2004-01-01)In this paper, we address and solve the problem of anti-windup augmentation for linear systems with input and output delay. In particular, we give a formal definition of an optimal L2 gain based anti-windup design problem in the global, local, robust and nominal cases. For each of these cases we show that a specific anti-windup compensation structure (which is a generalization of the approach in the Proceedings of the Fourth ECC, Brussels, Belgium, July 1997) is capable of solving the anti-windup problem whenever this solvable. The effectiveness of the proposed scheme is shown on a simple example taken from the literature, in which the plant is a marginally stable linear system
-
Item/spl Lscr//sub 2/ anti-windup for linear dead-time systems(IEEE, 2004)In this paper, we address and solve the problem of anti-windup augmentation for linear systems with input and output delay. In particular, we give a formal definition of the anti-windup construction problem in the global, local, robust and nominal cases. For each of these cases we show that a specific anti-windup compensation structure is capable of solving the anti-windup problem whenever this is solvable. The effectiveness of the proposed scheme is shown on a simple example taken from the literature, in which the plant is a marginally stable linear system.
-
ItemStability of time-varying discrete-time cascades(IFAC, 2002)Stability results for analysis of time-varying discrete-time cascaded systems are presented. Most of these results parallel their continuous-time counterparts although there are some important differences in the proof techniques that are used. More importantly, some fundamental differences between stability properties of discrete-time and continuous-time cascades are pointed out and illustrated via examples.
-
ItemInput to state stability of pulse width modulated control systems(University of Notre Dame, 2002)New results on set stability and input-to-state stability in pulse-width modulated (PWM) control systems with disturbances are presented. The results are based on a recent generalization of two time scale stability theory to di®erential equations with disturbances. In particular, averaging theory for systems with disturbances is used to establish the results. The nonsmooth nature of PWM systems is accommodated by working with upper semicontinuous set-valued maps, locally Lipschitz in°ations of these maps, and locally Lipschitz parameterizations of locally Lipschitz set-valued maps.
-
ItemTwo algorithms arising in analysis of polynomial models(IEEE, 1998)Algorithms for testing observability and forward accessibility of discrete-time polynomial systems are presented. The algorithms are based on symbolic computation packages - the Grobner basis method and QEPCAD. The observability test checks observability of general polynomial systems in finite time. Forward accessibility test is applicable to a large class of polynomial systems and also stops in finite time.
-
ItemOn the use of switched linear controllers for stabilizability of implicit recursive equations(IEEE, 1998-01-01)Stabilizability of implicit recursive equations is investigated. These equations arise naturally in the context of output dead-beat control for systems described by NARMAX models. Due to non-uniqueness of the solutions of these equations a special kind of a constrained stabilizability problem is considered. We take a hybrid switching control approach in testing the existence of a locally stabilizing controller. A method for the design of a stabilizing switching controller is also presented.
-
ItemObservability for simple Wiener and simple Wiener-Hammerstein systems(IEEE, 1998-01-01)Necessary and sufficient conditions for observability are given for the class of simple Wiener-Hammerstein systems. The obtained observability test resembles the well known result for the series connection of two linear systems but it is subtly different. Observability tests that we present are very easy to use.