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Automatic Control, IEEE Transactions on

Issue 4 • Date April 2004

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Displaying Results 1 - 25 of 28
  • Table of contents

    Publication Year: 2004 , Page(s): c1 - c4
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  • IEEE Transactions on Automatic Control publication information

    Publication Year: 2004 , Page(s): c2
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  • Scanning the issue

    Publication Year: 2004 , Page(s): 469
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  • Uniform stability of switched linear systems: extensions of LaSalle's Invariance Principle

    Publication Year: 2004 , Page(s): 470 - 482
    Cited by:  Papers (204)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (352 KB) |  | HTML iconHTML  

    This paper addresses the uniform stability of switched linear systems, where uniformity refers to the convergence rate of the multiple solutions that one obtains as the switching signal ranges over a given set. We provide a collection of results that can be viewed as extensions of LaSalle's Invariance Principle to certain classes of switched linear systems. Using these results one can deduce asymptotic stability using multiple Lyapunov functions whose Lie derivatives are only negative semidefinite. Depending on the regularity assumptions placed on the switching signals, one may be able to conclude just asymptotic stability or (uniform) exponential stability. We show by counter-example that the results obtained are tight. View full abstract»

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  • Inner-outer factorization for nonlinear noninvertible systems

    Publication Year: 2004 , Page(s): 483 - 492
    Cited by:  Papers (7)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (280 KB) |  | HTML iconHTML  

    This paper considers inner-outer factorization of asymptotically stable nonlinear state space systems in continuous time that are noninvertible. Our approach will be via a nonlinear analogue of spectral factorization which concentrates on first finding the outer factor instead of the inner factor. An application of the main result to control of nonminimum phase nonlinear systems is indicated. View full abstract»

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  • Potential-based online policy iteration algorithms for Markov decision processes

    Publication Year: 2004 , Page(s): 493 - 505
    Cited by:  Papers (16)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (360 KB) |  | HTML iconHTML  

    Performance potentials play a crucial role in performance sensitivity analysis and policy iteration of Markov decision processes. The potentials can be estimated on a single sample path of a Markov process. In this paper, we propose two potential-based online policy iteration algorithms for performance optimization of Markov systems. The algorithms are based on online estimation of potentials and stochastic approximation. We prove that with these two algorithms the optimal policy can be attained after a finite number of iterations. A simulation example is given to illustrate the main ideas and the convergence rates of the algorithms. View full abstract»

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  • Local equilibrium controllability of multibody systems controlled via shape change

    Publication Year: 2004 , Page(s): 506 - 520
    Cited by:  Papers (7)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (400 KB)  

    We study local equilibrium controllability of shape controlled multibody systems. The multibody systems are defined on a trivial principal fiber bundle by a Lagrangian that characterizes the base body motion and shape dynamics. A potential dependent on an advected parameter, e.g., uniform gravitational potential, is considered. This potential breaks base body symmetries, but a symmetry subgroup is assumed to exist. Symmetric product formulas are derived and important properties are obtained for symmetric products of horizontal shape control vector fields and a potential vector field that is dependent on an advected parameter. Based on these properties, sufficient conditions for local equilibrium controllability and local fiber equilibrium controllability are developed. These results are applied to two classes of shape controlled multibody systems in a uniform gravitational field: multibody attitude systems and neutrally buoyant multibody underwater vehicles. View full abstract»

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  • Stability and instability matrices for linear evolution variational inequalities

    Publication Year: 2004 , Page(s): 521 - 534
    Cited by:  Papers (10)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (392 KB) |  | HTML iconHTML  

    This paper deals with the characterization of the stability and instability matrices for a class of unilaterally constrained dynamical systems, represented as linear evolution variational inequalities (LEVI). Such systems can also be seen as a sort of differential inclusion, or (in special cases) as linear complementarity systems, which in turn are a class of hybrid dynamical systems. Examples show that the stability of the unconstrained system and that of the constrained system, may drastically differ. Various criteria are proposed to characterize the stability or the instability of LEVI. View full abstract»

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  • Absolute stability with a generalized sector condition

    Publication Year: 2004 , Page(s): 535 - 548
    Cited by:  Papers (35)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (424 KB) |  | HTML iconHTML  

    This paper generalizes the linear sector in the classical absolute stability theory to a sector bounded by concave/convex functions. This generalization allows more flexible or more specific description of the nonlinearity and will thus reduce the conservatism in the estimation of the domain of attraction. We introduce the notions of generalized sector and absolute contractive invariance for estimating the domain of attraction of the origin. Necessary and sufficient conditions are identified under which an ellipsoid is absolutely contractively invariant. In the case that the sector is bounded by piecewise linear concave/convex functions, these conditions can be exactly stated as linear matrix inequalities. Moreover, if we have a set of absolutely contractively invariant (ACI) ellipsoids, then their convex hull is also ACI and inside the domain of attraction. We also present optimization technique to maximize the absolutely contractively invariant ellipsoids for the purpose of estimating the domain of attraction. The effectiveness of the proposed method is illustrated with examples. View full abstract»

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  • A unifying framework for global regulation via nonlinear output feedback: from ISS to iISS

    Publication Year: 2004 , Page(s): 549 - 562
    Cited by:  Papers (56)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (360 KB) |  | HTML iconHTML  

    This paper presents a unifying framework for the problem of robust global regulation via output feedback for nonlinear systems with integral input-to-state stable inverse dynamics, subject to possibly unknown control direction. The contribution of the paper is two-fold. Firstly, we consider the problem of global regulation, instead of global asymptotic stabilization (GAS), for systems with generalized dynamic uncertainties. It is shown by an elementary example that GAS is not solvable using conventional smooth output feedback. Secondly, we reduce the stability requirements for the disturbance and demand relaxed assumptions for the system. Using our framework, most of the known classes of output feedback form systems are broadened in several directions: unmeasured states and unknown parameters can appear nonlinearly, restrictive matching and growth assumptions are removed, the dynamic uncertainty satisfies the weaker condition of Sontag's integral input-to-state stability, and the sign of high-frequency gain may be unknown. A constructive strategy is proposed to design a dynamic output feedback control law, that drives the state to the origin while keeping all other closed-loop signals bounded. View full abstract»

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  • Nonlinear H controllers for electromagnetic suspension systems

    Publication Year: 2004 , Page(s): 563 - 568
    Cited by:  Papers (10)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (384 KB)  

    This note presents a unified framework to derive nonlinear H state and output feedback controllers for magnetically levitated (Maglev) vehicles with controlled dc electromagnets, referred to as electromagnetic suspension systems. The theoretical exposition, based on the Taylor series expansion solution to the Hamilton-Jacobi-Isaacs inequality, is followed by an assessment of some of the practical issues in realizing the nonlinear controllers with a digital signal processor and embedded hardware. A select set of experimental results from a single-degree-of-freedom suspension system is included to highlight the effectiveness of the proposed nonlinear stateand output-feedback H controllers to suppress guideway-induced disturbances. View full abstract»

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  • Robust stability and stabilization of discrete singular systems: an equivalent characterization

    Publication Year: 2004 , Page(s): 568 - 574
    Cited by:  Papers (134)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (240 KB)  

    This note deals with the problems of robust stability and stabilization for uncertain discrete-time singular systems. The parameter uncertainties are assumed to be time-invariant and norm-bounded appearing in both the state and input matrices. A new necessary and sufficient condition for a discrete-time singular system to be regular, causal and stable is proposed in terms of a strict linear matrix inequality (LMI). Based on this, the concepts of generalized quadratic stability and generalized quadratic stabilization for uncertain discrete-time singular systems are introduced. Necessary and sufficient conditions for generalized quadratic stability and generalized quadratic stabilization are obtained in terms of a strict LMI and a set of matrix inequalities, respectively. With these conditions, the problems of robust stability and robust stabilization are solved. An explicit expression of a desired state feedback controller is also given, which involves no matrix decomposition. Finally, an illustrative example is provided to demonstrate the applicability of the proposed approach. View full abstract»

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  • Quadratic stability of a class of switched nonlinear systems

    Publication Year: 2004 , Page(s): 574 - 578
    Cited by:  Papers (110)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (208 KB)  

    Quadratic stability of a class of switched nonlinear systems is studied in this note. We first transform quadratic stability problem into an equivalent nonlinear programming problem. Then, we derive a necessary and sufficient condition for quadratic stability of this class of switched systems by using Karush-Kuhn-Tucker condition for nonlinear programming problems. The necessary and sufficient condition is given in terms of the strict completeness of a certain set of functions on a subset of the state space, which is much easier to check. View full abstract»

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  • A new periodic adaptive control approach for time-varying parameters with known periodicity

    Publication Year: 2004 , Page(s): 579 - 583
    Cited by:  Papers (54)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (216 KB)  

    A new adaptive control approach is proposed to deal with nonlinear systems with a class of time-varying parametric uncertainties, which are in an unknown compact set, periodic, nonvanishing, rapid time-varying, and the only prior knowledge is the periodicity. Unlike most continuous time adaptation laws which are of differential types, in this work a periodic type adaptation law is introduced for continuous time systems. The new adaptive controller updates the parameters and the control signal periodically in a pointwise manner over one entire period, in the sequel achieves the asymptotic tracking convergence. View full abstract»

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  • Output tracking for nonlinear stochastic systems by iterative learning control

    Publication Year: 2004 , Page(s): 583 - 588
    Cited by:  Papers (29)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (264 KB)  

    An iterative learning control (ILC) algorithm, which in essence is a stochastic approximation algorithm, is proposed for output tracking for nonlinear stochastic systems with unknown dynamics and unknown noise statistics. The nonlinear function of the system dynamics is allowed to grow up as fast as a polynomial of any degree, but the system is linear with respect to control. It is proved that the ILC generated by the algorithm a.s. converges to the optimal one at each time t∈[0,1,...,N] and the output tracking error is asymptotically minimized in the mean square sense as the number of iterates tends to infinity, although the convergence rate is rather slow. The only information used in the algorithm is the noisy observation of the system output and the reference signal yd(t). When the system state equation is free of noise and the system output is realizable, then the exact state tracking is asymptotically achieved and the tracking error is purely due to the observation noise. View full abstract»

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  • Elementary proof of controller parametrization without coprime factorizability

    Publication Year: 2004 , Page(s): 589 - 592
    Cited by:  Papers (4)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (176 KB)  

    Recently, a controller parametrization method without coprime factorizability was presented by Mori. In this note, we present this method using elementary matrix operations. Unlike in the earlier paper, good knowledge of commutative algebra and module theory is not required. View full abstract»

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  • A simultaneous perturbation stochastic approximation-based actor-critic algorithm for Markov decision processes

    Publication Year: 2004 , Page(s): 592 - 598
    Cited by:  Papers (12)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (360 KB)  

    A two-timescale simulation-based actor-critic algorithm for solution of infinite horizon Markov decision processes with finite state and compact action spaces under the discounted cost criterion is proposed. The algorithm does gradient search on the slower timescale in the space of deterministic policies and uses simultaneous perturbation stochastic approximation-based estimates. On the faster scale, the value function corresponding to a given stationary policy is updated and averaged over a fixed number of epochs (for enhanced performance). The proof of convergence to a locally optimal policy is presented. Finally, numerical experiments using the proposed algorithm on flow control in a bottleneck link using a continuous time queueing model are shown. View full abstract»

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  • On the solvability of extended Riccati equations

    Publication Year: 2004 , Page(s): 598 - 602
    Cited by:  Papers (4)
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    The Kalman-Yakubovich-Popov lemma, which gives necessary and sufficient conditions for solvability of matrix Lur'e-Riccati equations, is a milestone in modern control theory. There are, however, important and general extensions of this lemma that have not been studied yet. Starting with the absolute stability theory with semidefinite frequency domain function, we generalize here this lemma to the sign indefinite case-a research that is motivated by new problems on passivity and H control theory. View full abstract»

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  • An analysis and design method for uncertain variable structure systems with bounded controllers

    Publication Year: 2004 , Page(s): 602 - 607
    Cited by:  Papers (10)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (224 KB)  

    We present a method for estimating the asymptotic stability region(ASR) of uncertain variable structure systems with bounded switching feedback controllers. Using linear matrix inequalities(LMIs) we estimate the ASR and we show the exponential stability of the closed-loop control system in the estimated ASR. We also give a simple LMI-based method for designing switching surfaces that will make the estimated ASR big. Finally, we give numerical examples in order to show the effectiveness of our method. View full abstract»

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  • How should an autonomous vehicle overtake a slower moving vehicle: design and analysis of an optimal trajectory

    Publication Year: 2004 , Page(s): 607 - 610
    Cited by:  Papers (18)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (176 KB)  

    Over the past few years, there has been much research on various aspects of control of autonomous vehicles. However, it seems that the problem of overtaking a slower moving vehicle has been somewhat neglected. This note deals with the three-phase overtaking maneuver and with designing a smooth and ergonomic optimal lane-change trajectory to be used under normal conditions. It is shown that the absolute shape, size, and time of the first-phase trajectory do not depend on the velocity of the leading, slower moving vehicle. Only the absolute point for initiating the diversion is affected. The relatively simple mathematical model for each lane-change trajectory is based on minimizing the total kinetic energy during the maneuver, superimposed on a "minimum-jerk trajectory." For high enough initial velocities, explicit formulas are obtained for the optimal distance and the optimal time of the maneuver. It is also shown that the total time is bounded from above and below, regardless of the velocity. By using the results of the suggested model, an autonomous vehicle, equipped with appropriate sensors, can estimate the best time and place to begin and end the overtaking and its total time and distance. This may help to make a decision whether to overtake or not. View full abstract»

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  • Adaptive robust tracking and model following of uncertain dynamical systems with multiple time delays

    Publication Year: 2004 , Page(s): 611 - 616
    Cited by:  Papers (56)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (256 KB)  

    The problem of robust tracking and model following is considered for a class of linear systems with multiple delayed state perturbations, time-varying uncertain parameters, and disturbance. In this note, it is assumed that the upper bounds of the delayed state perturbations, uncertainties, and external disturbances, are unknown. An improved adaptation law with σ-modification is proposed to estimate such unknown bounds, and on the basis of the updated values of these unknown bounds, a class of continuous memoryless state feedback controllers is constructed for robust tracking of dynamical signals. The proposed adaptive robust tracking controller can guarantee that the tracking error decreases asymptotically to zero in the presence of multiple delayed state perturbations, time-varying uncertain parameters, and disturbance. In addition, it is also shown that this improved adaptation law with σ-modification can be applied to the general adaptive control problems to obtain some more exact control results. Finally, a numerical example is given to demonstrate the validity of the results. View full abstract»

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  • Performance analysis of evolutionary optimization with cumulative step length adaptation

    Publication Year: 2004 , Page(s): 617 - 622
    Cited by:  Papers (9)  |  Patents (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (256 KB)  

    Iterative algorithms for continuous numerical optimization typically need to adapt their step lengths in the course of the search. While some strategies employ fixed schedules, others attempt to adapt dynamically in response to the outcome of trial steps or the history of the search process. Evolutionary algorithms are of the latter kind. A control strategy that is commonly used in evolution strategies is the cumulative step length adaptation approach. This paper presents a theoretical analysis of that adaptation strategy. The analysis includes the practically relevant case of noise interfering in the optimization process. Recommendations are made with respect to choosing appropriate population sizes. View full abstract»

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  • Local control strategies for groups of mobile autonomous agents

    Publication Year: 2004 , Page(s): 622 - 629
    Cited by:  Papers (330)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (408 KB)  

    The problem of achieving a specified formation among a group of mobile autonomous agents by distributed control is studied. If convergence to a point is feasible, then more general formations are achievable too, so the focus is on convergence to a point (the agreement problem). Three formation strategies are studied and convergence is proved under certain conditions. Also, motivated by the question of whether collisions occur, formation evolution is studied. View full abstract»

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  • Comments on "Robust iterative learning control design is straightforward for uncertain LTI systems satisfying the robust performance condition"

    Publication Year: 2004 , Page(s): 629 - 630
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (80 KB)  

    For original paper see ibid., vol.48, p.101-6 (2003). The article comments on the result of the above paper. The authors of the original paper showed that Theorem 1 is only the sufficient condition of the convergence in the sense of the L2-norm. In this note, Theorem 1 is proved to be the not only sufficient but also necessary condition using some mathematical manipulation. View full abstract»

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  • Comments on "feedback control logic for forbidden-state problems of marked graphs: application to a real manufacturing system"

    Publication Year: 2004
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    The AIP manufacturing testbed discussed by Ghaffari et al. (see ibid., vol. 48, p.18-29, 2003) was previously treated using automaton-based [as distinct from Petri net (PN)-based] supervisory control theory (SCT). Problems of this general type have been transcribed from the PN literature, sometimes greatly enlarged, converted into SCT format, and solved using integer-decision-diagram (IDD) techniques with only modest expenditure of time and memory. Thus it is substantially misleading to state, that "the AIP control problem would require huge processing time and memory if addressed with the Ramadge-Wonham [SCT] approach." In contrast to the restriction in Ghaffari et al. (2003) to "marked graphs", no prior structural restrictions other than finiteness of the state set (or boundedness in the case of PNs) were placed on the models of system components. View full abstract»

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