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Automatic Control, IEEE Transactions on

Issue 5 • Date May 2003

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Displaying Results 1 - 25 of 32
  • Comments on "Robust stabilization of a class of time-delay nonlinear systems"

    Publication Year: 2003
    Cited by:  Papers (9)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (199 KB) |  | HTML iconHTML  

    In this paper, we point out an error in the above paper by Nguang (ibid. vol.45 (2000)), which shows that the main result of the paper cannot stand. In the paper, the Nguang considers the problem of robust stabilization of a class of triangular nonlinear system, and develops an iterative procedure of constructing a stabilization controller based on the constructive use of appropriate Lyapunov-Krasovskii functions. However, we show in this note that there is an error in the paper, which leads to the failure of the iterative procedure, so the conclusion cannot stand. View full abstract»

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  • Comments on "Robust stabilization of a class of time-delay nonlinear systems"

    Publication Year: 2003
    Cited by:  Papers (5)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (173 KB) |  | HTML iconHTML  

    The purpose of the above paper by Nguang (ibid. vol.45 (2000)) is to construct a robust memoryless state feedback controller for a class of uncertain time-delay systems with lower triangular structure, namely, strict feedback structure. However, there are some mistakes in the paper. The purpose of this note is to point out the mistakes and propose some suggestions to correct the mistakes. For simplicity, all the symbols in this note are the same as those in original paper. View full abstract»

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  • List of reviewers for 2002

    Publication Year: 2003 , Page(s): 909 - 913
    Save to Project icon | Request Permissions | PDF file iconPDF (150 KB)  
    Freely Available from IEEE
  • Set simulations for quadratic systems

    Publication Year: 2003 , Page(s): 800 - 805
    Cited by:  Papers (5)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (375 KB) |  | HTML iconHTML  

    In this paper, we study the problem of propagating in time a bounding set for the state of a class of nonlinear quadratic systems. The sequence of bounding sets is called the set simulation of the system, and conveys useful information about the stability and qualitative behavior of the possible time responses of the system. Numerically, efficient recursive algorithms are presented for the specific cases when the bounding sets are orthotopes or ellipsoids. View full abstract»

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  • Reconfigurable fault-tolerant control using GIMC structure

    Publication Year: 2003 , Page(s): 832 - 839
    Cited by:  Papers (22)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (491 KB) |  | HTML iconHTML  

    In this note, a fault-tolerant control strategy is proposed from a robust control perspective by applying the recently introduced generalized internal model control architecture. This fault-tolerant control design consists of two parts: a nominal performance controller and a robustness controller, and works in such way that when a sensor failure is detected, the controller structure is reconfigured by adding a robustness loop to compensate the fault. This note shows how to design such controllers for a single-input two-output gyroscope system so that the performance with the nominal controller may be maintained in the case of sensor failure and/or model uncertainties. View full abstract»

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  • Decentralized control design for large-scale systems with strong interconnections using neural networks

    Publication Year: 2003 , Page(s): 805 - 810
    Cited by:  Papers (53)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (334 KB) |  | HTML iconHTML  

    We propose a decentralized neural network (NN) controller for a class of large-scale nonlinear systems with the strong interconnections. The NNs are used to approximate the unknown subsystems and interconnections. Due to the functional approximation capabilities of NNs, the additional precautions are not required to be made for avoiding the possible control singularity problems. Semiglobal asymptotic stability results are obtained and the tracking error converges to zero. Furthermore, the issue of transient performance of the subsystems is also addressed under an analytical framework. View full abstract»

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  • Decentralized relay-based multivariable process identification in the frequency domain

    Publication Year: 2003 , Page(s): 873 - 878
    Cited by:  Papers (10)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (305 KB) |  | HTML iconHTML  

    In this paper, a modified decentralized relay test is designed for multivariable processes, and then, a new method is proposed to identify the frequency response matrix at multiple points based on the test. In the modified decentralized relay test, only very first periods of oscillating inputs are implemented, so that the unsymmetrical two-sided pulse signals are produced automatically. The two-sided pulse waveform contains enough continuous spectrum over the important frequency range so that the frequency response matrix of interest can be obtained by using Fourier analysis without prior knowledge of the processes. Simulation examples are given to show both effectiveness and practicality of the identification method for a wide range of multivariable processes. View full abstract»

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  • A unified closed-loop stability measure for finite-precision digital controller realizations implemented in different representation schemes

    Publication Year: 2003 , Page(s): 816 - 822
    Cited by:  Papers (6)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (492 KB) |  | HTML iconHTML  

    A computationally tractable unified finite word length closed-loop stability measure is derived which is applicable to fixed-point, floating-point and block-floating-point representation schemes. Both the dynamic range and precision of an arithmetic scheme are considered in this new unified measure. For each arithmetic scheme, the optimal controller realization problem is defined and a numerical optimization approach is adopted to solve it. Numerical examples are used to illustrate the design procedure and to compare the optimal controller realizations in different representation schemes. View full abstract»

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  • S-modular games and power control in wireless networks

    Publication Year: 2003 , Page(s): 839 - 842
    Cited by:  Papers (88)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (250 KB) |  | HTML iconHTML  

    This note shows how centralized or distributed power control algorithms in wireless communications can be viewed as S-modular games coupled policy sets (coupling is due to the fact that the set of powers of a mobile that satisfy the signal-to-interference ratio constraints depends on powers used by other mobiles). This sheds a new light on convergence properties of existing synchronous and asynchronous algorithms, and allows us to establish new convergence results of power control algorithms. Furthermore, known properties of power control algorithms allow us to extend the theory of S-modular games and obtain conditions for the uniqueness of the equilibrium and convergence of best response algorithms independently of the initial state. View full abstract»

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  • The no free lunch theorems: complexity and security

    Publication Year: 2003 , Page(s): 783 - 793
    Cited by:  Papers (12)  |  Patents (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (428 KB) |  | HTML iconHTML  

    One of the main challenges for decision scientists in the 21st century will be managing systems of ever increasing complexity. As systems like electrical power grids, computer networks, and the software that controls it all grow increasingly complex, fragility, bugs, and security flaws are becoming increasingly prevalent and problematic. It is natural then to ask what consequences this growing complexity has on our ability to manage these systems. In this paper, we take a first step toward addressing this question with the development of the fundamental matrix, a framework for analyzing the broad qualitative nature of decision making. With the fundamental matrix we explain in a qualitative way many theorems and known results about optimization, complexity, and security. The simplicity of the explanations leads to new insights toward potential research directions. Like other "theories" dealing with broad fundamental properties, however, the fundamental matrix has certain limitations that make it largely descriptive. Thus, instead of claiming the last words our goal is to stimulate a dialog and debate that may one day lead to a prescriptive science of complexity. View full abstract»

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  • Approximate explicit constrained linear model predictive control via orthogonal search tree

    Publication Year: 2003 , Page(s): 810 - 815
    Cited by:  Papers (67)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1527 KB) |  | HTML iconHTML  

    Solutions to constrained linear model predictive control problems can be precomputed off-line in an explicit form as a piecewise linear state feedback on a polyhedral partition of the state-space, avoiding real-time optimization. We suggest an algorithm that can determine an approximate explicit piecewise linear state feedback by imposing an orthogonal search tree structure on the partition. This leads to a real-time computational complexity that is logarithmic in the number of regions in the partition, and the algorithm yields guarantees on the suboptimality, asymptotic stability and constraint fulfillment. View full abstract»

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  • Local stabilization of linear systems under amplitude and rate saturating actuators

    Publication Year: 2003 , Page(s): 842 - 847
    Cited by:  Papers (23)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (355 KB) |  | HTML iconHTML  

    This note addresses the problem of local stabilization of linear systems subject to control amplitude and rate saturation. Considering the actuator represented by a first-order system subject to input and state saturation, a condition for the stabilization of an a priori given set of admissible initial states is formulated from certain saturation nonlinearities representation and quadratic stability results. From this condition, an algorithm based on the iterative solution of linear matrix inequalities-based problems is proposed in order to compute the control law. View full abstract»

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  • Parameter dependent stability and stabilization of uncertain time-delay systems

    Publication Year: 2003 , Page(s): 861 - 866
    Cited by:  Papers (59)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (317 KB) |  | HTML iconHTML  

    A new robust delay dependent stability test is introduced that determines the asymptotic stability of linear systems with state delays. The parameters of the system are not exactly given. They are known to reside in a given polytope. The test provides an efficient sufficient condition for the stability of the system over the uncertainty polytope. This condition is parameter dependent and it therefore improves previous results that were derived using a single Lyapunov-Krasovskii functional. The stability test is readily extended to provide a criterion for robust stabilization via state-feedback. View full abstract»

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  • On the global stability of delayed neural networks

    Publication Year: 2003 , Page(s): 794 - 797
    Cited by:  Papers (32)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (308 KB) |  | HTML iconHTML  

    Lyapunov functional methods, combining with some inequality techniques, are employed to study the global asymptotic stability of delayed neural networks. Without assuming Lipschitz conditions on the activation functions, a new sufficient condition is established. Such criteria allows us to include non-Lipschitzian activation functions in the design of delayed neural networks. The result presented here is also discussed from the point of view of its relationship to some previous results. View full abstract»

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  • On gain adaptation in adaptive control

    Publication Year: 2003 , Page(s): 895 - 899
    Cited by:  Papers (24)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (390 KB) |  | HTML iconHTML  

    The adaptive high-gain output feedback strategy u(t)=-k(t)y(t), (d/dt)k(t)=||y(t)||2 is well established in the context of linear, minimum-phase, m-input m-output systems (A, B, C) with the property that spec(CB)⊂C+; the strategy applied to any such linear system achieves the performance objectives of: 1) global attractivity of the zero state; and 2) convergence of the adapting gain to a finite limit. Here, these results are generalized in three aspects. First, the class of systems is enlarged to a class Nh(μ), encompassing nonlinear systems modeled by functional differential equations, where the parameter h≥0 quantifies system memory and the continuous function μ:[0,∞)→[0,∞), with μ(0)=0, relates to the allowable system nonlinearities. Next, the linear control law is replaced by u(t)=-k(t)[y(t)+μ(||y(t)||)/||y(t)||]y(t), wherein the additional nonlinear term counteracts the system nonlinearities. Then, the quadratic adaptation law is replaced by the law (d/dt)k(t)=ψ(||y(t)||), where the continuous function ψ satisfies certain growth conditions determined by μ (in particular cases, e.g., linear systems, a bounded function ψ is admissible). The above performance objectives 1) and 2) are shown to persist in the generalized framework. View full abstract»

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  • A game-theoretic approach to decision in FDI

    Publication Year: 2003 , Page(s): 853 - 858
    Cited by:  Papers (7)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (355 KB) |  | HTML iconHTML  

    Fault detection and isolation in dynamic systems rises decision problems in the presence of nuisance parameters (unknown initial states, unknown inputs, uncertain parameters). The strict decoupling strategy proposed in control approaches may sometimes fail to be applicable, while statistical decision rules can only be proven to be asymptotically optimal under special assumptions on the faults. In this note, a game-theoretic problem formulation, which is not purely geometrical and not purely statistical, is proposed and solutions are characterized under some reasonable assumptions. View full abstract»

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  • On quadratic Lyapunov functions

    Publication Year: 2003 , Page(s): 885 - 890
    Cited by:  Papers (77)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (391 KB) |  | HTML iconHTML  

    A topological structure, as a subset of [0,2π)L×R+n-1, is proposed for the set of quadratic Lyapunov functions (QLFs) of a given stable linear system. A necessary and sufficient condition for the existence of a common QLF of a finite set of stable matrices is obtained as the positivity of a certain integral. The structure and the conditions are considerably simplified for planar systems. It is also proved that a set of block upper triangular matrices share a common QLF, if each set of diagonal blocks share a common QLF. View full abstract»

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  • Sufficient conditions for parameter convergence in linearizable systems

    Publication Year: 2003 , Page(s): 878 - 880
    Cited by:  Papers (6)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (241 KB) |  | HTML iconHTML  

    The major drawback of the adaptive compensation design in the previous paper (2002) in terms of parameter identification is that the criterion for parameter convergence cannot be checked in advance. The purpose of this paper aims at circumventing such difficulties by providing a priori verifiable sufficient conditions that guarantee the asymptotic stability of the parametric equilibrium. View full abstract»

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  • Stabilization of discrete-time systems by first-order controllers

    Publication Year: 2003 , Page(s): 858 - 860
    Cited by:  Papers (16)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (445 KB) |  | HTML iconHTML  

    In this note, we consider the problem of stabilizing a given but arbitrary linear time invariant discrete-time system with transfer function P(z), by a first-order discrete-time feedback controller C(z)=(zx1+x2)/(z+x3). The complete set of stabilizing controllers is determined in the controller parameter space [x1, x2, x3]. The solution involves the Chebyshev representation of the characteristic equation on the unit circle. The set is shown to be computable explicitly, for fixed x3 by solving linear equations involving the Chebyshev polynomials in closed form, and the three-dimensional set is recovered by sweeping over the scalar parameter x3. This result gives a constructive solution of: 1) the problem of "first-order stabilizability" of a given plant; 2) simultaneous stabilization of a set of plants Pi(z); and 3) stable or minimum phase first-order stabilization of a plant. The solution is facilitated by the fact that it is based on linear equations and the intersection of sets can be found by adding more equations. In each case, the complete set of solutions is found and this feature is essential and important for imposing further design requirements. Illustrative examples are included. View full abstract»

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  • Solving the scalar feedback Nash algebraic Riccati equations: an eigenvector approach

    Publication Year: 2003 , Page(s): 847 - 852
    Cited by:  Papers (6)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (348 KB) |  | HTML iconHTML  

    In this note, we present an algorithm to compute all solutions of the scalar algebraic Riccati equations that play an important role in finding feedback Nash equilibria of the scalar N-player linear-quadratic differential game. We show that all appropriate solutions can be obtained by analyzing the eigenstructure of a related matrix. View full abstract»

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  • On the synthesis of controllers for a non-overshooting step response

    Publication Year: 2003 , Page(s): 797 - 800
    Cited by:  Papers (21)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (242 KB) |  | HTML iconHTML  

    In this paper, we show how a two-parameter compensator can always be designed for any linear time-invariant plant, that does not have a zero at the origin, to render its step response non-overshooting. View full abstract»

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  • Robust adaptive control for a class of MIMO nonlinear systems with guaranteed error bounds

    Publication Year: 2003 , Page(s): 728 - 742
    Cited by:  Papers (44)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1381 KB) |  | HTML iconHTML  

    The design of stabilizing controllers for multiple-input-multiple-output (MIMO) nonlinear plants with unknown nonlinearities is a challenging problem. The high dimensionality coupled with the inability to identify the nonlinearities online or offline accurately motivates the design of stabilizing controllers based on approximations or on approximate estimates of the plant nonlinearities that are simple enough to be generated in real time. The price paid in such case, could be lack of theoretical guarantees for global stability, and nonzero tracking or regulation error at steady state. In this paper, a nonlinear robust adaptive control algorithm is designed and analyzed for a class of MIMO nonlinear systems with unknown nonlinearities. The proposed control scheme provides a general approach to bypass the stabilizability problem where the estimated plant becomes uncontrollable without any restrictive assumptions. The controller is continuous and guarantees closed-loop semi-global stability and convergence of the tracking error to a small residual set. The size of the tracking error at steady state can be specified a priori and guaranteed by choosing certain design parameters. A procedure for choosing these parameters is presented. The properties of the proposed control algorithm are demonstrated using simulations. View full abstract»

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  • Less conservative conditions for asymptotic stability of impulsive control systems

    Publication Year: 2003 , Page(s): 829 - 831
    Cited by:  Papers (63)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (269 KB) |  | HTML iconHTML  

    This note studies the stability of impulsive control systems. A new comparison theorem for asymptotic stability of impulsive differential system is presented. Based on the new result, we derive some less conservative conditions for asymptotic stability of impulsive control systems with impulses at fixed times and the results are used to design impulsive control for a class of nonlinear systems. The class of nonlinear systems considered is also enlarged. View full abstract»

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  • Yet another H discretization

    Publication Year: 2003 , Page(s): 891 - 894
    Cited by:  Papers (7)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (275 KB) |  | HTML iconHTML  

    A new approach to the conversion of the sampled-data H problem to an equivalent pure discrete-time, lumped-variables counterpart, is presented. The approach is independent of controller causality constraints. In particular, it is applicable to problems, such as preview tracking and fixed-lag smoothing, where existing reduction methods fail. We demonstrate this by presenting a way to solve the open problem no. 51 from the book Open Problems in Mathematical Systems and Control Theory. View full abstract»

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  • Robust H filtering for uncertain Markovian jump systems with mode-dependent time delays

    Publication Year: 2003 , Page(s): 900 - 907
    Cited by:  Papers (163)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (434 KB) |  | HTML iconHTML  

    This paper considers the problem of robust H filtering for uncertain Markovian jump linear systems with time-delays which are time-varying and depend on the system mode. The parameter uncertainties are time-varying norm-bounded. The aim of this problem is to design a Markovian jump linear filter that ensures robust exponential mean-square stability of the filtering error system and a prescribed L2- induced gain from the noise signals to the estimation error, for all admissible uncertainties. A sufficient condition for the solvability of this problem is obtained. The desired filter can be constructed by solving a set of linear matrix inequalities. An illustrative numerical example is provided to demonstrate the effectiveness of the proposed approach. View full abstract»

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Aims & Scope

In the IEEE Transactions on Automatic Control, the IEEE Control Systems Society publishes high-quality papers on the theory, design, and applications of control engineering.  Two types of contributions are regularly considered

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Meet Our Editors

Editor-in-Chief
P. J. Antsaklis
Dept. Electrical Engineering
University of Notre Dame