Laboratorio Nacional Of Computacao Cientifica Lncc Mcti

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Laboratorio Nacional Of Computacao Cientifica Lncc Mcti

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Coutinho D.,Federal University of Santa Catarina | De Souza C.E.,Laboratorio Nacional Of Computacao Cientifica Lncc Mcti
International Journal of Robust and Nonlinear Control | Year: 2013

This paper proposes a linear matrix inequality based method for the estimation of domain of attraction for a class of discrete-time nonlinear systems subject to uncertain constant parameters. Recursive algebraic representations of the system dynamics and of the Lyapunov stability conditions are applied to obtain convex conditions which guarantee the system robust local stability while providing an estimate of the domain of attraction. A large class of discrete-time nonlinear systems and of Lyapunov functions can be embedded in the proposed methodology including the whole class of regular rational functions of the system state variable and uncertain parameters. Numerical examples illustrate the application of the proposed method. Copyright © 2012 John Wiley & Sons, Ltd. Copyright © 2012 John Wiley & Sons, Ltd.


De Souza C.E.,Laboratorio Nacional Of Computacao Cientifica Lncc Mcti | Coutinho D.,Federal University of Santa Catarina
IFAC Proceedings Volumes (IFAC-PapersOnline) | Year: 2014

This paper addresses the synthesis of delay-dependent local stabilizing controllers for, possibly open-loop unstable, nonlinear quadratic systems with a varying time-delay in the state. We develop methods for designing static nonlinear quadratic state feedback controllers that guarantee the local asymptotic stability of the closed-loop system zero equilibrium point in some polytopic region of the state-space while ensuring a region of stability inside this polytope. Control designs based on either the Razumikhin or the Lyapunov-Krasovskii approaches are considered. The proposed designs are delay-dependent and are formulated in terms of linear matrix inequalities. A numerical example is presented to illustrate the application of the stabilization methods. © IFAC.


De Souza C.E.,Laboratorio Nacional Of Computacao Cientifica Lncc Mcti | Coutinho D.,Federal University of Santa Catarina
IFAC Proceedings Volumes (IFAC-PapersOnline) | Year: 2014

This paper investigates the problem of local stabilization of Markov jump nonlinear quadratic systems. A method is presented for the synthesis of a static nonlinear quadratic state feedback control law that ensures the local exponential mean square stability of the zero equilibrium point of the closed-loop system in some polytopic region of the state-space with a guaranteed region of stability inside this polytope. The proposed control design is tailored in terms of linear matrix inequalities together with convex optimization to achieve an enlarged stability region. A numerical example is presented to illustrate the application of the stabilization method. © IFAC.


Barbosa K.A.,University of Santiago de Chile | De Souza C.E.,Laboratorio Nacional Of Computacao Cientifica Lncc Mcti | Coutinho D.,Federal University of Santa Catarina
Proceedings of the IEEE Conference on Decision and Control | Year: 2012

This paper deals with the problem of admissibility analysis (i.e. regularity, causality and exponential stability) of discrete-time linear descriptor systems with uncertain time-varying parameters. The parameters enter affinely into the state matrix of the system state-space model, and their admissible values and variations are assumed to belong to given intervals. First, necessary and sufficient admissibility conditions for uncertainty-free discrete linear time-varying descriptor systems are presented. Next, strict LMI conditions based on parameter-dependent Lyapunov functions are proposed to ensure robust admissibility of uncertain descriptor systems. Both the cases of Lyapunov functions with affine and quadratic dependence on the system uncertain parameters are considered. The robust admissibility analysis methods incorporate information on available bounds on both the admissible values and variation of the uncertain parameters. Numerical examples are presented to demonstrate the potentials of the proposed methods. © 2012 IEEE.


Maestrelli R.,Federal University of Santa Catarina | Coutinho D.,Federal University of Santa Catarina | De Souza C.E.,Laboratorio Nacional Of Computacao Cientifica Lncc Mcti
Proceedings of the IEEE Conference on Decision and Control | Year: 2012

This paper analyzes the stability of input and output quantized discrete-time linear control systems considering static finite-level logarithmic quantizers. The sector bound approach together with a relaxed stability notion are applied to derive LMI based conditions for estimating a set of initial conditions and its attractor assuming that the controller and quantizers are known a priori. These conditions ensure that all state trajectories belonging to the first set will enter the attractor in a finite time and remains inside it. A numerical example is presented to illustrate the application of the derived results. © 2012 IEEE.


de Souza C.E.,Laboratorio Nacional Of Computacao Cientifica Lncc Mcti | Coutinho D.,Federal University of Santa Catarina | Kinnaert M.,Free University of Colombia
Automatica | Year: 2016

This paper deals with mean square state estimation over sensor networks with a fixed topology. Attention is focused on designing local stationary state estimators with a general structure while accounting for the network communication topology. Two estimator design approaches are proposed. One is based on the observability Gramian, and the other on the controllability Gramian. The computation of the estimator state-space matrices is recast as off-line convex optimization problems and requires the system asymptotic stability and global knowledge of the network topology. Convergence of the estimation error variance is ensured at each network node and a guaranteed performance in the mean square sense is achieved. The proposed approaches are also extended for designing robust filters to handle polytopic-type parameter uncertainty. © 2016 Elsevier Ltd


De Souza C.E.,Laboratorio Nacional Of Computacao Cientifica Lncc Mcti | Coutinho D.,Federal University of Santa Catarina
Automatica | Year: 2014

This paper deals with the problems of robust stability analysis and robust control of linear discrete-time periodic systems with a delayed state and subject to polytopic-type parameter uncertainty in the state-space matrices. A robust stability criterion independent of the time-delay length as well as a delay-dependent criterion is proposed, where the former applies to the case of a constant time-delay and the latter allows for a time-varying delay lying in a given interval. The developed robust stability criteria are based on affinely uncertainty-dependent Lyapunov-Krasovskii functionals and are given in terms of linear matrix inequalities. These stability conditions are then applied to solve the problems of robust stabilization and robust H∞ control via static periodic state feedback. Numerical examples illustrate the potentials of the proposed robust stability and control methods. © 2013 Elsevier Ltd. All rights reserved.


De Souza C.E.,Laboratorio Nacional Of Computacao Cientifica Lncc Mcti | Coutinho D.,Federal University of Santa Catarina | Gomes da Silva J.M.,Federal University of Rio Grande do Sul
International Journal of Robust and Nonlinear Control | Year: 2015

This paper addresses the problems of local stabilization and control of open-loop unstable discrete-time quadratic systems subject to persistent magnitude bounded disturbances and actuator saturation. Firstly, for some polytopic region of the state-space containing the origin, a method is derived to design a static nonlinear state feedback control law that achieves local input-to-state stabilization with a guaranteed stability region under nonzero initial conditions and persistent bounded disturbances. Secondly, the stabilization method is extended to deliver an optimized upper bound on the ℓ-induced norm of the closed-loop system for a given set of persistent bounded disturbances. Thirdly, the stabilization and ℓ designs are adapted to cope with actuator saturation by means of a generalized sector bound constraint. The proposed controller designs are tailored via a finite set of state-dependent linear matrix inequalities. Numerical examples are presented to illustrate the potentials of the proposed control design methods. Copyright © 2014 John Wiley & Sons, Ltd.


De Souza C.E.,Laboratorio Nacional Of Computacao Cientifica Lncc Mcti | Osowsky J.,Laboratorio Nacional Of Computacao Cientifica Lncc Mcti
Automatica | Year: 2013

This paper is concerned with gain-scheduled control of two-dimensional discrete-time linear parameter-varying systems described by a Roesser state-space model with matrices depending affinely on time-varying scheduling parameters. The parameter admissible values and variations are assumed to belong to given intervals. Linear matrix inequality based methods are devised for designing static state feedback gain-scheduled controllers with either an H ∞ or quadratic regulator-type performance. The control designs build on quadratically parameter-dependent Lyapunov functions and allow for incorporating information on available bounds on the parameters variation. The proposed controller gain can be independent, affine, quadratic, or a matrix fraction of quadratic polynomial matrices in the scheduling parameters. © 2012 Elsevier Ltd. All rights reserved.


Giusti S.M.,CONICET | Novotny A.A.,Laboratorio Nacional Of Computacao Cientifica Lncc Mcti
Mechanics Research Communications | Year: 2012

The topological derivative measures the sensitivity of a given shape functional with respect to an infinitesimal singular domain perturbation. According to the literature, the topological derivative has been fully developed for a wide range of physical phenomenon modeled by partial differential equations, considering homogeneous and isotropic constitutive behavior. In fact, only a few works dealing with heterogeneous and anisotropic material behavior can be found in the literature, and, in general, the derived formulas are given in an abstract form. In this work, we derive the topological derivative in its closed form for the total potential energy associated to an anisotropic and heterogeneous heat diffusion problem, when a small circular inclusion of the same nature of the bulk phase is introduced at an arbitrary point of the domain. In addition, we provide a full mathematical justification for the derived formula and develop precise estimates for the remainders of the topological asymptotic expansion. Finally, the influence of the heterogeneity and anisotropy are shown through some numerical examples of heat conductor topology optimization. © 2012 Elsevier Ltd. All rights reserved.

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