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Automatic Control, IEEE Transactions on

Issue 10 • Date Oct. 1996

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Displaying Results 1 - 23 of 23
  • Comments on "Dynamic compensation method for multivariable control systems with saturating actuators" [with reply]

    Page(s): 1549 - 1551
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (259 KB)  

    The commenters state that compared to existing methods for windup prevention, the one presented in the above-mentioned paper (Park and Choi,1995) requires additional dynamic elements and already fails in a very simple application. The authors reply to the points raised by the commenters. View full abstract»

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  • Lessons in Estimation Theory for Signal Processing, Communications, and Control [Book Reviews]

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    Freely Available from IEEE
  • Structured singular values with nondiagonal structures. I. Characterizations

    Page(s): 1507 - 1511
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (472 KB)  

    The purpose of this two-part series is to provide a robustness analysis framework for a class of problems with highly structured modeling uncertainties. This framework is more general than that of the usual block, diagonally structured uncertainties, and it corresponds to a structure consisting of block-by-block matrix perturbations. We study the structured singular value with respect to this structure, and we establish a number of novel results for this notion. This paper contains a study on the properties of the structured singular value. We give an alternative characterization of this notion as the solution of a smooth optimization problem. Furthermore, we show that under a certain circumstance the structured singular value reduces to a vector-induced matrix norm View full abstract»

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  • Structured singular values with nondiagonal structures. II. Computation

    Page(s): 1511 - 1516
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (528 KB)  

    In part I we introduced a robust stability measure-termed generalized structured singular value. In part II we address computational issues pertaining to this notion. Our main contribution is a computational method which would render the computation of the generalized structured singular value both more efficient and potentially more accurate. As in the computation of the usual structured singular value, the key in our method is to compute an upper norm bound scaled via a similarity transformation. It is shown that this bound is as tight as those obtained elsewhere and that it can be computed considerably more efficiently. Furthermore, it is shown that this bound is actually equal to the generalized structured singular value when the uncertainty has four blocks View full abstract»

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  • General framework for asymptotic properties of generalized weighted nonlinear least-squares estimators with deterministic and stochastic weighting

    Page(s): 1501 - 1507
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (656 KB)  

    This paper studies the asymptotic properties (strong consistency, convergence rate, asymptotic normality) of a generalized weighted nonlinear least-squares estimator under weak noise assumptions. Both deterministic and stochastic weighting are handled and the presence of model errors is considered. For particular models, estimators, and noise assumptions the general framework boils down to known time and frequency-domain estimators View full abstract»

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  • An algorithm for real-time failure detection in Kalman filters

    Page(s): 1537 - 1539
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (276 KB)  

    An algorithm is presented for solving the problem of real-time failure detection in dynamic systems using Kalman filters. We give a geometric solution to derive a test decision based on the overlap between the confidence regions associated with two estimates: one obtained using on-line measurements and the other based on a priori information. The implementation of a necessary and sufficient condition is shown to result in a scalar test. The advantage compared to standard techniques is a significantly lower computational burden View full abstract»

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  • Globally convergent algorithms for robust pole assignment by state feedback

    Page(s): 1432 - 1452
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1696 KB)  

    It is observed that an algorithm proposed in 1985 by Kautsky, Nichols, and Van Dooren (KNV) amounts to maximizing, at each iteration, the determinant of the candidate closed-loop eigenvector matrix X with respect to one of its columns (with unit-length constraint), subject to the constraint that it remains an achievable closed-loop eigenvector matrix. This interpretation is used to prove convergence of the KNV algorithm. It is then shown that a more efficient algorithm is obtained if det (X) is concurrently maximized with respect to two columns of X, and such a scheme is easily extended to the case where the eigenvalues to be assigned include complex conjugate pairs. Variations exploiting the availability of multiple processors are suggested. Convergence properties of the proposed algorithms are established. Their superiority is demonstrated numerically View full abstract»

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  • Model reduction of multidimensional and uncertain systems

    Page(s): 1466 - 1477
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    Model reduction methods are presented for systems represented by a linear fractional transformation on a repeated scalar uncertainty structure. These methods involve a complete generalization of balanced realizations, balanced Gramians, and balanced truncation model reduction with guaranteed error bounds, based on solutions to a pair of linear matrix inequalities which generalize Lyapunov equations. The resulting reduction methods immediately apply to uncertainty simplification and state order reduction in the case of uncertain systems but also may be interpreted as state order reduction for multidimensional systems View full abstract»

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  • Global regulation of a planar robot arm striking a surface

    Page(s): 1517 - 1521
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (452 KB)  

    Considers the problem of modeling and controlling the impact of a two-degree-of-freedom planar robot arm against an infinitely rigid and massive surface. For this case study, the basic equations describing the motion of the robot arm are derived for noncontact and contact conditions. A control scheme is proposed on the basis of a reduced-order observer that is able to asymptotically estimate the impact-induced forces and to allow their asymptotic compensation when the robot arm is in contact with the surface. The resulting control system ensures the global asymptotic regulation of the position of the arm with an assigned impact-induced force. The case study is completed by a simulation test View full abstract»

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  • A note on closed-loop balanced truncation

    Page(s): 1498 - 1500
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    Closed-loop balanced truncation is a model reduction method that aims at preserving the closed-loop properties of the original controller. We show that this method is equivalent to frequency-weighted balanced truncation with certain weighting and that for observer-based controllers, a significant amount of computation can be saved because of the observer-state feedback structure of the controller View full abstract»

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  • Minimal dimensional linear filters for discrete-time Markov processes with finite state space

    Page(s): 1545 - 1549
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (372 KB)  

    We consider a filtering problem for a discrete-time Markov process with k states observed in white Gaussian noise. It is known that in this situation the best linear estimate is given by a k-dimensional Kalman filter, and in some cases the dimension of such a filter can be reduced. Here, using a backward semimartingale description of the process and results from stochastic realization theory, we provide an algorithm for the construction of the minimal dimensional linear filter View full abstract»

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  • A set-based approach for white noise modeling

    Page(s): 1453 - 1465
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1092 KB)  

    This paper provides a new framework for analyzing white noise disturbances in linear systems; rather than the usual stochastic approach, noise signals are described as elements in sets, and their effect is analyzed from a worst-case perspective. The paper studies how these sets must be chosen to have adequate properties for system response in the worst-case, statistics consistent with the stochastic point of view, and simple descriptions that allow for tractable worst-case analysis. The method is demonstrated by considering its implications in two problems: rejection of white noise signals in the presence of system uncertainty and worst-case system identification View full abstract»

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  • Decentralized control of multirate systems subject to arbitrary exogenous signals

    Page(s): 1540 - 1544
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (380 KB)  

    This paper considers the design of decentralized digital control systems where the outputs are measured with different rates or at different times, whereas the inputs are updated all together. Specifically, a solution is given to the problem of asymptotically zeroing the system error when the exogenous signals coincide with the free motions of any unstable system. The proposed controller is constituted by a time-invariant internal model of the exogenous signals and a decentralized periodic stabilizer View full abstract»

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  • Continuous-time deadbeat control for sampled-data systems

    Page(s): 1478 - 1481
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (232 KB)  

    In this paper, the continuous-time deadbeat control problem for the sampled-data systems is considered. We derived the class of all controllers that achieve the continuous-time deadbeat control View full abstract»

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  • Continuous least-squares observers with applications

    Page(s): 1530 - 1537
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (656 KB)  

    A wide class of continuous least-squares (LS) observers is treated in a common framework provided by the pseudodifferential operator paradigm. It is shown that for the operators whose symbols satisfy certain conditions, the continuous LS observer always exists, providing observability of the plant. The general result is illustrated by an LS observer stemming from a sliding-window convolution operator. Applications to state feedback control and fault detection are discussed View full abstract»

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  • Supervisory control of families of linear set-point controllers Part I. Exact matching

    Page(s): 1413 - 1431
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    This paper describes a simple “high-level” controller called a “supervisor” which is capable of switching into feedback with a SISO process, a sequence of linear positioning or set-point controllers from a family of candidate controllers so as to cause the output of the process to approach and track a constant reference input. The process is assumed to be modeled by a SISO linear system whose transfer function is in the union of a number of subclasses, each subclass being small enough so that one of the candidate controllers would solve the positioning problem if the transfer function of the process were to be one of the subclasses' members. Each subclass contains a “nominal process model transfer function” about which the subclass is centred. It is shown that in the absence of unmodeled process dynamics, the proposed supervisor can successfully perform its function even if process disturbances are present, provided they are bounded and constant View full abstract»

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  • Infinite horizon stable predictive control

    Page(s): 1522 - 1527
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (464 KB)  

    Terminal constraints guarantee the stability of predicted trajectories and form the basis of predictive control algorithms with guaranteed stability. Earlier work in the literature uses terminal constraints which define sufficient but not necessary conditions for the stability of predicted trajectories. In this paper we deploy conditions which are both necessary and sufficient and hence release more degrees of freedom for optimizing performance and/or meeting constraints. Also an alternative means of computing the implied infinite horizon GPC cost, avoiding the need for solving a Lyapunov equation, is presented View full abstract»

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  • Asymptotic regulation of minimum phase nonlinear systems using output feedback

    Page(s): 1402 - 1412
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (872 KB)  

    We consider a single-input/single-output (SISO) nonlinear system which has a well-defined normal form with asymptotically stable zero dynamics. We allow the system's equation to depend on constant uncertain parameters and disturbance inputs which do not change the relative degree. Our goal is to design an output feedback controller which regulates the output to a constant reference. The integral of the regulation error is augmented to the system equation, and a robust output feedback controller is designed to bring the state of the closed-loop system to a positively invariant set. Once inside this set, the trajectories approach a unique equilibrium point at which the regulation error is zero. We give regional as well as semiglobal results View full abstract»

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  • A revisit to the gain and phase margins of linear quadratic regulators

    Page(s): 1527 - 1530
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    In this paper, we revisit the well-known robustness properties of the linear quadratic regulator (LQR), namely, the guaranteed gain margin of -6 to +∞ dB and phase margin of -60° to +60° for single-input systems. We caution that these guaranteed margins need to be carefully interpreted. More specifically, we show via examples that an LQR may have a very small margin with respect to the variations of the gain and/or phase of the open-loop plant. Such a situation occurs in most practical systems, where the set of measurable state variables cannot be arbitrarily selected. Therefore the lack of robustness of the LQR can be very popular and deserves attention View full abstract»

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  • A note on robust pole assignment for periodic systems

    Page(s): 1493 - 1497
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    In this note a robust pole assignment algorithm is proposed for linear periodic discrete-time systems with time-varying dimensions of the state and/or input spaces. The algorithm deduces a periodic state feedback law by the minimization of the condition numbers of the eigenvector matrices of the closed-loop system. Numerical examples are provided to show the performances of the algorithm View full abstract»

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  • Parameter convergence of a new class of adaptive controllers

    Page(s): 1489 - 1493
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (460 KB)  

    A new class of adaptive control schemes for minimum-phase linear time invariant (LTI) systems has recently been developed using nonlinear design techniques which guarantee improved transient performance in addition to closed-loop stability and asymptotic tracking. In this paper we establish the parameter convergence properties of this new class of schemes in the presence of persistently exciting signals and compare them with the properties of the traditional adaptive controllers. We show that the new class of adaptive controllers has stronger parameter convergence properties in the presence of overparameterization View full abstract»

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  • Analytic expressions of transfer function responses and choice of numerator coefficients (zeros)

    Page(s): 1482 - 1488
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (528 KB)  

    General analytic expressions of transfer function responses are derived in this paper. The analytic forms include the numerator coefficients of the transfer function, a Vandermonde-like matrix, and a vector containing the transfer function eigenresponses, the latter two only depending on the eigenvalues. Several characteristics of basic transient responses are derived, e.g., their exact number of zeros. An upper bound on the number of extrema of the step response is obtained. An algorithm is suggested for the selection of the numerator coefficients, assuming fixed eigenvalues, using the derived characteristics of the basic transient responses, effectively leading to a suboptimal choice. Furthermore, the analytic formulas are used to calculate the numerator coefficients optimally, by minimizing the step transient, the ramp transient, the parabolic transient, etc. Simulations are presented indicating the properties of the basic transient responses and the transfer function response properties based on optimal and suboptimal choices of the numerator coefficients 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