Florianópolis, Brazil


Florianópolis, Brazil
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Picinin D.,Jr. | Farines J.-M.,DAS CTC UFSC | Santos C.A.S.,Federal University of Bahia
WebMedia 2011 - XVII Brazilian Symposium on Multimedia and the Web, co-located with XXV Brazilian Symposium on Database, SBBD 2011 | Year: 2011

This paper proposes an Model-Driven Engineering approach for modeling and veri-ficating of interactive multimedia applications. The approach introduces a toolchain based on FIACRE language, that is used both as the target language of model transformation engines from NCL multimedia model, and as the source language of compilers into the targeted verification toolbox Tina. The paper illustrates the proposed approach with a case study of a NCL-based interactive TV application.

Jungers M.,University of Lorraine | Castelan E.B.,DAS CTC UFSC | Tarbouriech S.,CNRS | Daafouz J.,University of Lorraine
Nonlinear Analysis: Hybrid Systems | Year: 2011

The paper addresses two control problems of discrete-time switching systems subject to modal nonlinearities satisfying sector conditions, actuator saturations and additive L2-bounded disturbances. Such switching systems consist of a finite family of discrete-time processes that are supervised by logical decision-making algorithms. Conditions based on LMIs are provided for synthesizing the control gains and for obtaining regions of absolute λ-contractivity as large as possible or for obtaining a L2-gain as small as possible. A numerical example illustrates the proposed approaches. © 2010 Elsevier Ltd.

Gomes Da Silva Jr. J.M.,Federal University of Rio Grande do Sul | Castelan E.B.,DAS CTC UFSC | Corso J.,CCT UDESC | Eckhard D.,Federal University of Rio Grande do Sul
Journal of the Franklin Institute | Year: 2013

In the present work a systematic methodology for computing dynamic output stabilizing feedback control laws for nonlinear systems subject to saturating inputs is presented. In particular, the class of Lur'e type nonlinear systems is considered. Based on absolute stability tools and a modified sector condition to take into account input saturation effects, an LMI framework is proposed to design the controller. Asymptotic as well as input-to-state and input-to-output (in a L2 sense) stabilization problems are addressed both in regional (local) and global contexts. The controller structure is composed of a linear part, an anti-windup loop and a term associated to the output of the dynamic nonlinearity. Convex optimization problems are proposed to compute the controller considering different optimization criteria. A numerical example illustrates the potentialities of the methodology. © 2013 The Franklin Institute.

Louis J.,Nancy Research Center for Automatic Control | Jungers M.,Nancy Research Center for Automatic Control | Daafouz J.,Nancy Research Center for Automatic Control | Daafouz J.,Institut Universitaire de France | Castelan E.B.,DAS CTC UFSC
IFAC Proceedings Volumes (IFAC-PapersOnline) | Year: 2015

This paper deals with discrete-time switched Lur'e systems including an additional saturated input and a bounded energy disturbance. Two control design issues are investigated related to the L2-induced gain and the rejection of disturbance. An common optimization problem under LMI conditions and differing from the cost function to optimize, is provided to offer a solution to the both problems. The main approach is to upper bound a criterion with a suitable Lur'e type Lyapunov function. Numerical examples are given to underline the efficiency of our approach and to allow a discussion with the literature. © 2015, IFAC Hosting by Elsevier Ltd.

Jungers M.,University of Lorraine | Jungers M.,Nancy Research Center for Automatic Control | Castelan E.B.,DAS CTC UFSC | Moraes V.M.,DAS CTC UFSC | Moreno U.F.,DAS CTC UFSC
Automatica | Year: 2013

The stabilization of a network controlled system including a global time-varying delay is investigated in this note. This delay is considered to be unknown but it is assumed that a bounded error estimate is available. The exponential uncertainty induced by the time-varying delay is decomposed into the sum of a polytopic term and an uncertain bounded term. Sufficient conditions to design a dynamic output feedback controller depending on an estimate of the time-varying delay are proposed as linear matrix inequalities. An illustration shows how our methodology enlarges the design techniques of the literature. © 2012 Elsevier Ltd. All rights reserved.

Jungers M.,University of Lorraine | Jungers M.,Nancy Research Center for Automatic Control | Abou-Kandil H.,Ecole Normale Superieure de Cachan | Castelan E.B.,DAS CTC UFSC | De Pieri E.R.,DAS CTC UFSC
Automatica | Year: 2013

This paper investigates the problems of non-uniform pole shifting or pole homothety in multivariable linear systems by using a gametheoretic approach and more specifically a particular Nash strategy with an open-loop information structure for a game including a time preference rate in the quadratic criteria. Such a result is possible due to properties of non-symmetric Algebraic Riccati equations associated with an open-loop Nash strategy. Numerical examples allow to illustrate the efficiency of the proposed approach. © 2012 Elsevier Ltd. All rights reserved.

Dilda V.,DAS CTC UFSC | Jungers M.,University of Lorraine | Jungers M.,Nancy Research Center for Automatic Control | Castelan E.B.,DAS CTC UFSC
International Journal of Robust and Nonlinear Control | Year: 2015

The presence of the dead-zone nonlinearity is common in many physical systems and in general degrades the control systems performance or stability. This note considers an interconnection between a continuous time multiple-input linear system and a dead-zone nonlinearity associated with a state feedback. The issue of analyzing the property of uniform ultimate boundedness (UUB) of a system and the issue of designing a control under UUB constraint are studied. Firstly, the dead-zone is replaced via a linear transformation introducing the saturation. Secondly, we improve the size of the UUB area that can be found in the literature, by expressing the saturation in terms of parametrized piecewise affine bounds. This allows also a link between standard approaches such ones using piecewise affine models or ones considering global cone bounded sector conditions. In the framework of analysis and synthesis, sufficient conditions are obtained by linear matrix inequalities. Illustrative examples are given to spotlight the efficiency of our approach. Copyright © 2014 John Wiley & Sons, Ltd.

Leite V.J.S.,Federal University of Minas Gerais | Castelan E.B.,DAS CTC UFSC | Miranda M.F.,Federal University of Minas Gerais | Viana D.C.,Federal University of Minas Gerais
Proceedings of the 2010 American Control Conference, ACC 2010 | Year: 2010

Convex conditions, proposed as a feasibility test of a set of linear matrix inequalities (LMIs), are given for the design of a partially parameter dependent dynamic output feedback controller for a class of discrete time systems with delayed state. This class concerns the systems with time-varying delay in the state and time varying parameters, both assumed to be available on line. The controller is composed by a classical part, feeding-back the system output and another one where the delayed output of the system is feedback. This last part can be avoided in case of inaccessible delay value, resulting in a more classical control design. Different from other approaches found in the literature, it is used a parameter dependent Lyapunov-Krasovskii functional candidate and a slack matrix variable to reduce the conservatism of the proposed approach. The resulting parameter dependent controller can be obtained on line as a convex combination of some 'vertex' controllers. Numerical examples are presented to illustrated the effectiveness of the proposal. © 2010 AACC.

Jungers M.,University of Lorraine | Castelan E.B.,DAS CTC UFSC
Systems and Control Letters | Year: 2011

This paper deals with the stabilization of a class of nonlinear discrete-time systems under control saturations including time-varying parameter dependency. The control law studied consists of the gain-scheduled feedback of the measured output and of the nonlinearity present in the dynamics of the controlled system. Furthermore, the saturations are taken into account by modeling the nonlinear saturated system through a dead-zone nonlinearity satisfying a modified sector condition. Thus, as for precisely known systems, linear matrix inequality (LMI) stabilization conditions are proposed for such a generic system. These conditions can be cast into convex programming problems for design purposes. An illustrative example stresses the efficiency of the main result. © 2010 Elsevier B.V.

Cavichioli Gonzaga C.A.,University of Lorraine | Jungers M.,University of Lorraine | Daafouz J.,University of Lorraine | Castelan E.B.,DAS CTC UFSC
Proceedings of the IEEE Conference on Decision and Control | Year: 2011

This paper presents a new class of Lur'e type Lyapunov functions for a discrete-time switched system interconnected with a switched nonlinearity satisfying a mode-dependent cone bounded condition. This function includes the mode-dependent nonlinearity, but not its integral. Such a Lyapunov function allows to obtain sufficient conditions in terms of linear matrix inequalities (LMI), for the stability analysis in two different frameworks: global stability analysis for the considered systems and local stability analysis for these systems with an additional saturating input consisting of a switched linear state feedback. In the second case, an optimization problem based on these sufficient conditions is provided to enlarge the estimation of the basin of attraction, which may be composed of non-convex and disconnected sets, because of the presence of the nonlinearities in the Lyapunov function. Some numerical examples are presented to highlight the relevance of the new Lyapunov function and of the proposed method. © 2011 IEEE.

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