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Automatic Control, IEEE Transactions on

Issue 8 • Date Aug. 1999

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Displaying Results 1 - 25 of 28
  • Comments on "Robust stability of linear systems with delayed perturbations" [with reply]

    Publication Year: 1999 , Page(s): 1582 - 1583
    Cited by:  Papers (5)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (72 KB)  

    This paper comments on the result of the paper by Kim (ibid. vol.41 (1996)). The estimate of the stability robustness of linear time-delay systems in that paper is compared with the one which is solved in a Riccati matrix inequality framework. In reply, Kim acknowledge that his result needs the selection of a matrix Q and a scalar /spl alpha/ which maximize the bound /spl eta//sub k0/(Q, /spl alpha/). The result proposed by Ooba-Funahashi, that does not need this selection, is summarized. View full abstract»

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  • Comments on "Robust stability of linear systems with delayed perturbations"

    Publication Year: 1999
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (26 KB)  

    The paper points out that in Kim (1996), the concavity of the function is falsely defined, so the proof in the appendix in the paper is wrong. A corrected version of the proof is provided. View full abstract»

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  • Comments on "Stabilization and estimation for perturbed discrete time-delay large scale systems

    Publication Year: 1999
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (27 KB)  

    In the above-mentioned paper (Wang and Mau, 1997), the authors have developed a criterion to guarantee the robust stabilization and state estimation of a class of discrete-time interconnected systems. They have claimed that the developed criterion is independent of the time delay and that the unknown delay is constant but unknown. This paper highlights an error in the paper which can only be remedied by stating that the delay factor is a known constant. View full abstract»

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  • Correction to "Simultaneous stabilization via static output feedback and state feedback"

    Publication Year: 1999 , Page(s): 1632
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (27 KB)  

    In the above-mentioned paper (ibiid., vol. 44, pp. 1277??1282, June 1999), the address for the first author was listed incorrectly. The appropriate contact information appears herein. View full abstract»

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  • Singularity for static-state feedback linearizable bilinear systems

    Publication Year: 1999 , Page(s): 1559 - 1564
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (236 KB)  

    This paper deals with the problem of singularities for a class of static-state feedback linearizable bilinear systems. For this class of nonlinear systems, the decoupling matrix is singular on an algebraic surface (which contains the origin), and this relates the static state feedback linearization to the difficult problem of the completeness of the trajectories of the closed-loop system and/or the boundedness of the feedback laws. In this work, we give a sufficient condition under which all the trajectories of the closed-loop system are complete and the used feedback law is bounded on each of these trajectories View full abstract»

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  • Bezout factors and L1-optimal controllers for delay systems using a two-parameter compensator scheme

    Publication Year: 1999 , Page(s): 1512 - 1521
    Cited by:  Papers (13)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (328 KB)  

    The authors consider the simultaneous problem of optimal robust stabilization and optimal tracking for single-input/single-output (SISO) systems in an L-setting using a two-parameter compensator scheme. Optimal robustness is linked to the work done by Georgiou and Smith (1992) in the L2-setting. Optimal tracking involves the resolution of L1-optimization problems. The authors consider in particular the robust control of delay systems. They determine explicit expressions of the Bezout factors for general delay systems which are in the Callier-Desoer class ℬˆ(0). Finally, they solve several general L1-optimization problems and give an algorithm to solve the optimal robust control problem for a large class of delay systems View full abstract»

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  • Robustness with respect to disturbance model uncertainty-analysis and design

    Publication Year: 1999 , Page(s): 1556 - 1559
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (152 KB)  

    Motivated by an aircraft control problem where the airplane encounters turbulence with uncertain characteristics, this paper studies the analysis and design of controllers that are robust with respect to uncertainty in the disturbance intensity and bandwidth, where disturbance rejection is measured by the output variance View full abstract»

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  • Robust synthesis of feedforward compensators

    Publication Year: 1999 , Page(s): 1578 - 1582
    Cited by:  Papers (33)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (184 KB)  

    The design of a feedforward compensator for robust ℋ or ℋ2 performance under structured uncertainty is considered. For linear time-invariant uncertainty, a convex method based on linear matrix inequalities (LMIs) across the frequency variable is given. For nonlinear or time-varying perturbations and ℋ performance, the design problem is reduced exactly to a state-space LMI, and extensions to ℋ2 performance are discussed. An example illustrates the application of these techniques to two-degree-of-freedom control design View full abstract»

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  • Steering policies for controlled Markov chains under a recurrence condition

    Publication Year: 1999 , Page(s): 1583 - 1587
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (192 KB)  

    The authors consider the class of steering policies for controlled Markov chains under a recurrence condition. A steering policy is defined as one adaptively alternating between two stationary policies in order to track a sample average cost to a desired value. Convergence of the sample average costs is derived via direct sample path arguments, and the performance of the steering policy is discussed. Steering policies are motivated by, and particularly useful in, the discussion of constrained Markov chains with a single constraint View full abstract»

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  • Robust tuning of dead-time compensators for processes with an integrator and long dead-time

    Publication Year: 1999 , Page(s): 1597 - 1603
    Cited by:  Papers (28)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (196 KB)  

    Presents a simple criterion for tuning a dead time compensator for plants with an integrator and long dead time. The criterion is based on the definition of a closed-loop performance and considers that the model of the process is not precisely known. Using an estimation of the dead time and velocity gain of the plant, the proposed control law has only one tuning parameter that determines the closed-loop performance and robustness. By tuning this parameter it is possible to attain some robust performance specifications. In order to compare the proposed criterion with previous algorithms proposed in the literature, a comparative analysis of robustness is presented. Some simulation examples demonstrate the good properties of the proposed compensator View full abstract»

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  • Semiglobal L2 performance bounds for disturbance attenuation in nonlinear systems

    Publication Year: 1999 , Page(s): 1535 - 1545
    Cited by:  Papers (23)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (296 KB)  

    This paper addresses the problem of disturbance attenuation (in the sense of L2-gain), with internal stability and no cost on the control input, for nonlinear systems, when the problem of almost disturbance decoupling is not solvable, i.e., when the least achievable attenuation level between disturbance and regulated output is nonzero. Two different approaches are provided, which facilitate the estimation of an upper bound for such a value View full abstract»

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  • Stability condition of a class of nonlinear feedback systems: reduction to a convex problem

    Publication Year: 1999 , Page(s): 1573 - 1577
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (196 KB)  

    This paper gives a new criterion for input-output stability of a class of nonlinear feedback systems, roughly speaking, it is most useful in such a practical situation where the nonlinearity in the system is “almost time-invariant and memoryless” but with “slight time-variations and dynamics”. It involves two free parameters and contains the circle criterion and the Popov criterion as special cases. In fact, it extends these two famous criteria in such a way that the conservatism of the circle criterion can be reduced when the time-variations and dynamics of the nonlinearity are “relatively small”. It is also shown that the existence of the free parameters that fulfil the stability condition can be checked exactly by reducing it to a convex problem in the frequency domain View full abstract»

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  • Kalman filtering for continuous-time uncertain systems with Markovian jumping parameters

    Publication Year: 1999 , Page(s): 1592 - 1597
    Cited by:  Papers (136)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (192 KB)  

    Studies the problem of Kalman filtering for a class of uncertain linear continuous-time systems with Markovian jumping parameters. The system under consideration is subjected to time-varying norm-bounded parameter uncertainties in the state and measurement equations. Stochastic quadratic stability of the above system is analyzed. A state estimator is designed such that the covariance of the estimation error is guaranteed to be within a certain bound for all admissible uncertainties, which is in terms of solutions of two sets of coupled algebraic Riccati equations View full abstract»

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  • A new approach for analysis and synthesis of time-varying systems

    Publication Year: 1999 , Page(s): 1486 - 1497
    Cited by:  Papers (73)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (288 KB)  

    In this paper new techniques are developed for the analysis of linear time-varying (LTV) systems. These lead to a formally simple treatment of robust control problems for LTV systems, allowing methods more usually restricted to time invariant systems to be employed in the time-varying case. As an illustration of this methodology, the so-called H synthesis problem is solved for LTV systems View full abstract»

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  • A strong tracking extended Kalman observer for nonlinear discrete-time systems

    Publication Year: 1999 , Page(s): 1550 - 1556
    Cited by:  Papers (65)  |  Patents (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (212 KB)  

    The authors show how the extended Kalman filter, used as an observer for nonlinear discrete-time systems or extended Kalman observer (EKO), becomes a useful state estimator when the arbitrary matrices, namely Rk and Qk, are adequately chosen. As a first step, we use the linearization technique given by Boutayed et al. (1997), which consists of introducing unknown diagonal matrices to take the approximation errors into account. It is shown that the decreasing Lyapunov function condition leads to a linear matrix inequality (LMI) problem, which points out the connection between a good convergence behavior of the EKO and the instrumental matrices Rk and Q k. In order to satisfy the obtained LMI, a particular design of Qk is given. High performances of the proposed technique are shown through numerical examples under the worst conditions View full abstract»

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  • Some discrete-time counterparts to extreme point results for robust stability of a diamond of polynomials

    Publication Year: 1999 , Page(s): 1613 - 1615
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (124 KB)  

    The main result of the paper is that a family of polynomials with roughly half of all the real coefficients lying in a diamond is robustly Schur stable if and only if all the extreme polynomials are Schur stable. This special polynomial family is called a degenerate diamond of polynomials. In addition, we obtain the extreme point result for robust Schur stability of a so-called simplex degenerate diamond polynomial family View full abstract»

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  • New conditions for the convergence of H filters and predictors

    Publication Year: 1999 , Page(s): 1564 - 1568
    Cited by:  Papers (7)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (164 KB)  

    The finite-horizon H filtering and prediction problems in the discrete-time case admit solutions only if a suitable difference Riccati equation is solved by a matrix sequence satisfying “feasibility” conditions. In this work, sufficient conditions ensuring the existence of filters and predictors over an arbitrarily long time interval are derived. Moreover, it is shown that, under these conditions, finite horizon estimators tend to stable stationary ones as the time horizon increases View full abstract»

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  • Performance analysis for a changepoint problem

    Publication Year: 1999 , Page(s): 1628 - 1632
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (176 KB)  

    Nonlinear stochastic differential equations are used to model a version of the changepoint problem. State estimates of the minimum mean-square-error-type are used in likelihood-ratio tests to detect the time of change. System performance is evaluated by deriving theoretical expressions for the false alarm probability and a special case of the miss error probability. The approach uses a Fokker-Planck equation View full abstract»

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  • Performance of periodically time-varying controllers for sampled data control

    Publication Year: 1999 , Page(s): 1607 - 1611
    Cited by:  Papers (5)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (168 KB)  

    Analyzes performance of periodically time-varying sampled data controllers for Lp deterministic and uniform disturbance rejection. For a given linear periodic sampled data controller controlling a linear time-invariant continuous-time plant, it is shown that a linear time-invariant controller can be found to give better L p sampled data control than the time-varying controller. The performance analysis is in time domain using convexity properties of the Lp signal space View full abstract»

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  • On the static assignment to parallel servers

    Publication Year: 1999 , Page(s): 1588 - 1592
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (180 KB)  

    The authors study the static assignment to M parallel, exponential, heterogeneous servers. Blocked customers are lost, while the objective is to minimize the average number of blocked customers. The problem is formulated as a stochastic control problem with partial observation, and an equivalent full observation problem is formulated. Numerical experiments are conducted and the structure of the optimal policies is studied View full abstract»

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  • An interlaced extended Kalman filter

    Publication Year: 1999 , Page(s): 1546 - 1549
    Cited by:  Papers (12)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (124 KB)  

    An estimation algorithm for a class of discrete time nonlinear systems is proposed. The system structure we deal with is partitionable into in subsystems, each affine w.r.t. the corresponding part of the state vector. The algorithm consists of a bank of m interlaced Kalman filters, and each of them estimates a part of the state, considering the remaining parts as known time-varying parameters whose values are evaluated by the other filters at the previous step. The procedure neglects the subsystem coupling terms in the covariance matrix of the state estimation error and counteracts the errors so introduced by suitably “increasing” the noise covariance matrices. Comparisons through numerical simulations with the extended Kalman filter and its modified versions proposed in the literature illustrate the good trade-off provided by the algorithm between the reduction of the computational load and the estimation accuracy View full abstract»

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  • Existence of solutions to a class of nonlinear convergent chattering-free sliding mode control systems

    Publication Year: 1999 , Page(s): 1620 - 1624
    Cited by:  Papers (9)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (164 KB)  

    Sliding mode control is a nonlinear control technique, which is robust against some classes of uncertainties and disturbances. However, this control produces chattering which can cause instability due to unmodeled dynamics and can also cause damage to actuators or the plant. There are essentially two ways to counter the chattering phenomenon. One way is to use higher order sliding mode, and the other way is to add a boundary layer around the switching surface and use continuous control inside the boundary. The problem with the first method is that the derivative of a certain state variable is not available for measurement, and therefore methods have to be used to observe that variable. In the second method, it is important that the trajectories inside the boundary layer do not try to come outside the boundary after entering the boundary layer. Control laws producing chattering-free sliding mode using a boundary layer have been proposed and the existence of solutions to the system using these control laws are presented View full abstract»

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  • Robust disturbance-rejection problems for linear ω-periodic discrete-time systems

    Publication Year: 1999 , Page(s): 1615 - 1620
    Cited by:  Papers (4)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (224 KB)  

    Two robust disturbance-rejection problems with state feedback and with incomplete-state feedback for linear ω-periodic discrete-time systems are studied in the framework of the so-called geometric approach. Also, some necessary conditions and/or sufficient conditions for the problems to be solvable are presented View full abstract»

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  • On the modified Smith predictor for controlling a process with an integrator and long dead-time

    Publication Year: 1999 , Page(s): 1603 - 1606
    Cited by:  Papers (56)  |  Patents (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (136 KB)  

    A dead-time compensator for controlling higher-order processes with integral action and long dead-time is proposed. Tuning formulas are derived. If the velocity gain and the dead-time are estimated experimentally, only one parameter, the time constant defining the speed of the closed-loop setpoint response, has to be tuned manually. The same setpoint response is obtained as in the modified Smith predictor, while the load disturbance rejection is considerably faster View full abstract»

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  • Modeling of normalized coprime factors with ν-metric uncertainty

    Publication Year: 1999 , Page(s): 1498 - 1511
    Cited by:  Papers (4)  |  Patents (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (392 KB)  

    Modeling of uncertain systems with normalized coprime factor description is investigated, where the experimental data is given by a finite set of frequency response measurement samples of the open loop plant that is linear, time-invariant, and possibly infinite-dimensional. The objective is not only to identify the nominal model but also to quantify the modeling error with sup-norm bounds in frequency domain. The uncertainty to be identified and quantified is chosen as the ν-metric, proposed by Vinnicombe (1993), because of its compatibility with H-based robust control. An algorithm is developed to model the normalized coprime factors of the given plant using techniques of discrete Fourier analysis and balanced stochastic truncation and is shown to be robust in the presence of the worst case noise. Upper bounds are derived for the associated modeling error based on the minimum a priori information of the underlying model set and of the noise level in the measurement data. A simulation example is used to illustrate the effectiveness of the proposed algorithm 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