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Automatic Control, IEEE Transactions on

Issue 11 • Date Nov. 2001

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Displaying Results 1 - 25 of 27
  • Scanning the issue

    Publication Year: 2001 , Page(s): 1681
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    Freely Available from IEEE
  • Comments on "Parameterization of stabilizing compensators by using reduced-order observers"

    Publication Year: 2001 , Page(s): 1840 - 1842
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (112 KB) |  | HTML iconHTML  

    A counterexample of the above mentioned paper (Fujimori, IEEE Trans. Automat. Contr., vol. 38, p. 1435-39, 1993) is given. It is shown that the parameterization of all proper compensators internally stabilizing the plant is incomplete. Modified parameterization of all proper stabilizing compensators is also presented. View full abstract»

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  • Comments on "An unstable plant with no poles"

    Publication Year: 2001
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (35 KB) |  | HTML iconHTML  

    In the above paper (MacCluer, IEEE Trans. Automat. Contr., vol. 45, p. 1575-76, 2000), it was shown by way of an example that there exist bounded-input-bounded-output (BIBO) unstable linear systems whose transfer functions are analytic in the finite plane. We note that this result could easily be shown by using some examples already present in the literature. View full abstract»

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  • Comments on "An exponentially stable adaptive friction compensator"

    Publication Year: 2001 , Page(s): 1844 - 1845
    Cited by:  Papers (9)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (73 KB) |  | HTML iconHTML  

    This note points out a technique error in the above paper (Liao and Chien, IEEE Trans. Automat. Contr., Vol. 45, p. 977-80, 2000). It is shown that without persistence of excitation (PE) of the system signals, the estimated Coulomb friction parameter cannot be guaranteed to converge to its true value. An analysis is provided for the PE condition of parameter asymptotic convergence. View full abstract»

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  • Stochastic controls: Hamiltonian systems and HJB equations [Book Reviews]

    Publication Year: 2001 , Page(s): 1846
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    Freely Available from IEEE
  • Robust H filtering of stationary continuous-time linear systems with stochastic uncertainties

    Publication Year: 2001 , Page(s): 1788 - 1793
    Cited by:  Papers (70)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (228 KB)  

    The problem of applying H filters on stationary, continuous-time, linear systems with stochastic uncertainties in the state-space signal model is addressed. These uncertainties are modeled via white noise processes. The relevant cost function is the expected value of the standard H performance index with respect to the uncertain parameters. The solution is obtained via a stochastic bounded real lemma that results in a modified Riccati inequality. This inequality is expressed in the form of a linear matrix inequality whose solution provides the filter parameters. The method proposed is also applied to the case where, in addition to the stochastic uncertainty, other deterministic parameters of the system are not perfectly known and are assumed to lie in a given polytope. The problem of mixed H2 /H filtering for the above system is also treated. The theory developed is demonstrated by a practical example View full abstract»

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  • A note on input-to-state stability and averaging of systems with inputs

    Publication Year: 2001 , Page(s): 1760 - 1765
    Cited by:  Papers (6)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (243 KB) |  | HTML iconHTML  

    Two different definitions of an average for time-varying systems with inputs and a small parameter that were recently introduced in the literature are considered: "strong" and "weak" averages. It is shown that if the strong average is input-to-state stable (ISS), then the solutions of the actual system satisfy an integral bound in a semiglobal practical sense. The integral bound that we prove can be viewed as a generalization of the notion of finite-gain L2 stability, that was recently introduced in the literature. A similar result is proved for weak averages but the class of inputs for which the integral bound holds is smaller (Lipschitz inputs) than in the case of strong averages (measurable inputs) View full abstract»

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  • Optimal minimal-order least-squares estimators via the general two-stage Kalman filter

    Publication Year: 2001 , Page(s): 1772 - 1776
    Cited by:  Papers (6)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (140 KB) |  | HTML iconHTML  

    A direct derivation of the optimal minimal-order least squares estimator is presented using the general two-stage Kalman filter. Using this new result, the reduced-order estimators of O'Reilly (1982) and Fairman and Luk (1985) are readily shown to be equivalent. A practical implementation issue to consider these two estimators is also addressed View full abstract»

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  • The locally definable property of the product control structure

    Publication Year: 2001 , Page(s): 1794 - 1797
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (131 KB) |  | HTML iconHTML  

    In this paper, the control structures and control technologies in decentralized discrete event control system are investigated. It shows that if the control structures on two local systems are standard and locally definable, so is the product control structure. Furthermore, a control technology associated with the product control structure is also given View full abstract»

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  • Adaptive regulator for discrete-time nonlinear nonparametric systems

    Publication Year: 2001 , Page(s): 1836 - 1840
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (184 KB) |  | HTML iconHTML  

    A direct adaptive regulator for nonlinear nonparametric systems with measurement corrupted by noise is proposed. Under reasonable conditions the state of the closed-loop system is adaptively regulated so that it converges to zero as time tends to infinity. An illustrative example, being an affine nonlinear system, with all imposed conditions satisfied is given. The method of proof is based on stochastic approximation techniques View full abstract»

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  • Learning with prior information

    Publication Year: 2001 , Page(s): 1682 - 1695
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (341 KB) |  | HTML iconHTML  

    A notion of learnability is introduced, referred to as learnability with prior information (w.p.i.). This notion is weaker than the standard notion of probably approximately correct (PAC) learnability. A property called "dispersability" is introduced, and it is shown that dispersability plays a key role in the study of learnability w.p.i. Specifically, dispersability of a function class is always a sufficient condition for the function class to be learnable; moreover, in the case of concept classes, dispersability is also a necessary condition for learnability w.p.i. Thus in the case of learnability w.p.i., the dispersability property plays a role similar to the finite metric entropy condition in the case of PAC learnability with a fixed distribution. Next, the notion of learnability w.p.i. is extended to the distribution-free (d.f.) situation, and it is shown that a property called d.f. dispersability is always a sufficient condition for d.f. learnability w.p.i., and is also a necessary condition for d.f. learnability in the case of concept classes. The approach to learning introduced in the paper is believed to be significant in all problems where a nonlinear system has to be designed based on data. This includes direct inverse control and system identification View full abstract»

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  • On quadratic stability of systems with structured uncertainty

    Publication Year: 2001 , Page(s): 1799 - 1805
    Cited by:  Papers (8)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (237 KB) |  | HTML iconHTML  

    This paper considers the problem of stability robustness with respect to a class of nonlinear time-varying perturbations which are bounded in a component-wise rather than aggregated manner. A family of robustness bounds is parameterized in terms of a non-singular symmetric matrix. It is shown that the problem of computing the largest robustness bound over the set of non-singular symmetric matrices can be approximated by a smooth minimization problem over a compact set. A convergent algorithm for computing an optimal robustness bound is proposed in the form of a gradient flow View full abstract»

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  • Simple robust output-feedback controller for uncertain nonlinear systems

    Publication Year: 2001 , Page(s): 1765 - 1772
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (273 KB) |  | HTML iconHTML  

    A robust output-feedback controller is designed by using an observer plus backstepping procedure to solve the tracking problems of a class of uncertain nonlinear systems. In the design procedure, three techniques are applied: a) a single filter whose dynamic order is the same as the system order is constructed; b) a normalization signal is introduced; c) positive nonlinear functions that are used to generate the normalization signal and to construct nonlinear damping terms can be chosen freely. The designed controller has a very simple structure and can be applied to track much broader classes of reference signals. It can guarantee the global boundness of all closed-loop signals and make the output tracking error arbitrarily small. Technique c) may provide the designer with the possibility to find a better choice of positive nonlinear functions for our controller to achieve similar tracking performance with less control effort View full abstract»

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  • Design of fault diagnosis filters and fault-tolerant control for a class of nonlinear systems

    Publication Year: 2001 , Page(s): 1805 - 1810
    Cited by:  Papers (46)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (244 KB) |  | HTML iconHTML  

    This paper presents a set of algorithms for fault diagnosis and fault tolerant control strategy for affine nonlinear systems subjected to an unknown time-varying fault vector. First, the design of fault diagnosis filter is performed using nonlinear observer techniques, where the system is decoupled through a nonlinear transformation and an observer is used to generate the required residual signal. By introducing an extra input to the observer, a direct estimation of the time-varying fault is obtained when the residual is controlled, by this extra input, to zero. The stability analysis of this observer is proved and some relevant sufficient conditions are obtained. Using the estimated fault vector, a fault tolerant controller is established which guarantees the stability of the closed loop system. The proposed algorithm is applied to a combined pH and consistency control system of a pilot paper machine, where simulations are performed to show the effectiveness of the proposed approach View full abstract»

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  • A polynomial approach to nonlinear system controllability

    Publication Year: 2001 , Page(s): 1782 - 1788
    Cited by:  Papers (17)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (225 KB) |  | HTML iconHTML  

    Uses a polynomial approach to present a necessary and sufficient condition for local controllability of single-input-single-output (SISO) nonlinear systems. The condition is presented in terms of common factors of a noncommutative polynomial expression. This result exposes controllability properties of a nonlinear system in the input-output framework, and gives a computable procedure for examining nonlinear system controllability using computer algebra View full abstract»

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  • Output feedback sampled-data control of nonlinear systems using high-gain observers

    Publication Year: 2001 , Page(s): 1712 - 1725
    Cited by:  Papers (45)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (355 KB) |  | HTML iconHTML  

    This paper studies sampled-data control of nonlinear systems using high-gain observers. The observer is designed in continuous time, then discretized using three different discretization methods. Closed-loop analysis shows that the sampled-data controller recovers the performance of the continuous time controller as the sampling frequency and observer gain become sufficiently large. The theory is illustrated by experimental results View full abstract»

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  • Stability-constrained model predictive control

    Publication Year: 2001 , Page(s): 1816 - 1820
    Cited by:  Papers (7)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (143 KB) |  | HTML iconHTML  

    This paper presents a new approach to guaranteeing stability of model predictive control (MPC). A stability constraint is computed and propagated forward at each stage as a constraint on the magnitude of the predicted state vector for a state-space controllable-form realization. It is shown that asymptotic stability is guaranteed for the case of constrained multi-input linear time-invariant systems under full-state measurement or with state estimation for any prediction horizon and any optimization objective function View full abstract»

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  • Plant with integrator: an example of reset control overcoming limitations of linear feedback

    Publication Year: 2001 , Page(s): 1797 - 1799
    Cited by:  Papers (57)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (75 KB) |  | HTML iconHTML  

    The purpose of this paper is twofold: 1) to give conditions under which linear feedback control of a plant containing integrator must overshoot; and 2) to give an example of reset control that does not overshoot under such constraints View full abstract»

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  • Stochastic algorithms for exact and approximate feasibility of robust LMIs

    Publication Year: 2001 , Page(s): 1755 - 1759
    Cited by:  Papers (63)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (173 KB) |  | HTML iconHTML  

    In this note, we discuss fast randomized algorithms for determining an admissible solution for robust linear matrix inequalities (LMIs) of the form F(x,Δ)⩽0, where x is the optimization variable and Δ is the uncertainty, which belongs to a given set Δ. The proposed algorithms are based on uncertainty randomization: the first algorithm finds a robust solution in a finite number of iterations with probability one, if a strong feasibility condition holds. In case no robust solution exists, the second algorithm computes an approximate solution which minimizes the expected value of a suitably selected feasibility indicator function. The theory is illustrated by examples of application to uncertain linear inequalities and quadratic stability of interval matrices View full abstract»

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  • Stability of adaptively stabilized stochastic systems

    Publication Year: 2001 , Page(s): 1832 - 1836
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (173 KB) |  | HTML iconHTML  

    Stochastic adaptive stabilization usually leads to the boundedness of the average of squared output of the stabilized system, but gives no conclusion on stability of the resulting system. This paper proves that adaptively stabilized stochastic system in its steady state is truly stable in the conventional sense View full abstract»

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  • Control of mobile platforms using a virtual vehicle approach

    Publication Year: 2001 , Page(s): 1777 - 1782
    Cited by:  Papers (77)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (184 KB) |  | HTML iconHTML  

    Two model independent solutions to the problem of controlling wheel-based mobile platforms are proposed. These two algorithms are based on a so called virtual vehicle approach, where the motion of the reference point on the desired trajectory is governed by a differential equation containing error feedback. This, combined with the fact that the proven stable control algorithms are basically proportional regulators with arbitrary positive gains, make the solutions robust with respect to errors and disturbances, as demonstrated by the experimental results View full abstract»

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  • Stability enhancement by boundary control in 2-D channel flow

    Publication Year: 2001 , Page(s): 1696 - 1711
    Cited by:  Papers (24)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (569 KB) |  | HTML iconHTML  

    In this paper, we stabilize the parabolic equilibrium profile in a two-dimensional (2-D) channel flow using actuators and sensors only at the wall. The control of channel flow was previously considered by Speyer and coworkers, and Bewley and coworkers, who derived feedback laws based on linear optimal control, and implemented by wall-normal actuation. With an objective to achieve global Lyapunov stabilization, we arrive at a feedback law using tangential actuation (using teamed pairs of synthetic jets or rotating disks) and only local measurements of wall shear stress, allowing to embed the feedback in microelectromechanical systems (MEMS) hardware, without need for wiring. This feedback is shown to guarantee global stability in at least H2 norm, which by Sobolev's embedding theorem implies continuity in space and time of both the flow field and the control (as well as their convergence to the desired steady state). The theoretical results are limited to low values of Reynolds number, however, we present simulations that demonstrate the effectiveness of the proposed feedback for values five order of magnitude higher View full abstract»

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  • Robust synthesis in 1: a globally optimal solution

    Publication Year: 2001 , Page(s): 1744 - 1754
    Cited by:  Papers (17)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (306 KB)  

    In this paper, a method to synthesize controllers that achieve globally optimal robust performance within any prespecified tolerance, against structured norm-bounded time-varying and/or nonlinear uncertainty is developed. The performance measure considered is the infinity to infinity induced norm of a system's transfer function. The method developed utilizes linear relaxation techniques to solve the infinite dimensional nonconvex problem via finite dimensional linear programming problems View full abstract»

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  • Global stabilization for nonlinear uncertain systems with unmodeled actuator dynamics

    Publication Year: 2001 , Page(s): 1826 - 1832
    Cited by:  Papers (21)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (232 KB)  

    Second-order sliding-mode control (2-SMC) algorithms are analyzed to assess their global convergence properties. While standard first-order sliding-mode control (1-SMC) algorithms derive their effectiveness from the global solution of the well known "reaching condition" ss˙⩽-k2|s| (s=0 being the actual sliding manifold), 2-SMC is based on more complex differential inequalities, for which a global solution could not exist. The approach presented introduces a suitable commutation logic (based on an online simple predictor) that prevents an uncontrollable growth of the uncertainties. Due to this new commutation logic, the global convergence of the state trajectory to the designed sliding manifold is ensured View full abstract»

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  • Model matching for finite-state machines

    Publication Year: 2001 , Page(s): 1726 - 1743
    Cited by:  Papers (19)  |  Patents (4)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (445 KB) |  | HTML iconHTML  

    The problem of model matching for finite state machines (FSMs) consists of finding a controller for a given open-loop system so that the resulting closed-loop system matches a desired input-output behavior. In this paper, a set of model matching problems is addressed: strong model matching (where the reference model and the plant are deterministic FSMs and the initial conditions are fixed), strong model matching with measurable disturbances (where disturbances are present in the plant), and strong model matching with nondeterministic reference model (where any behavior out of those in the reference model has to be matched by the closed-loop system). Necessary and sufficient conditions for the existence of controllers for all these problems are given. A characterization of all feasible control laws is derived and an efficient synthesis procedure is proposed. Further, the well-known supervisory control problem for discrete-event dynamical systems (DEDSs) formulated in its basic form is shown to be solvable as a strong model matching problem with measurable disturbances and nondeterministic reference model 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