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Automatic Control, IEEE Transactions on

Issue 6 • Date Jun 1989

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Displaying Results 1 - 22 of 22
  • The relationship between real poles and real zeros in SISO sampled data systems

    Page(s): 632 - 635
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (304 KB)  

    A relationship between real poles and real zeros of SISO (single-input, single-output) sampled data systems is presented, which is independent of the sampling period. The relation is stated in terms of a parity property involving the number of real zeros between any two real poles. This property allows the investigation of conditions for the preservation of stable or unstable zeros under sampling. A sufficient condition for stability of a sampled system with a continuous-time plant having all real zeros, and a sufficient condition for instability of a two-sampled system with an unstable plant is developed View full abstract»

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  • Recursive inversion of externally defined linear systems by FIR filters

    Page(s): 635 - 637
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (240 KB)  

    The approximate inversion of an internally unknown linear system, given by its impulse response sequence, by an inverse system having a finite impulse response, is considered. The recursive least-squares procedure is shown to have an exact initialization based on the triangular Toeplitz structure of the matrix involved. The proposed approach also suggests solutions to the problem of system identification and compensation View full abstract»

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  • Structured singular value analysis of multidimensional system stability

    Page(s): 638 - 639
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    Structured singular value computations are being developed for analysis of robustness of multivariable control systems. It is shown that the same computational tools can be used to test the stability of multidimensional systems View full abstract»

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  • Quantizer effects on steady-state error specifications of digital feedback control systems

    Page(s): 651 - 654
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (316 KB)  

    Suppose that for a linear, time-invariant, single-input single-output (SISO) plant a digital dynamic controller has been designed so that the corresponding discrete-time linear feedback control system will satisfy certain specified steady-state error criteria (e.g., the output v˜(kT) will follow the input r (kT) within a certain given error bound). Corresponding to this idealized linear system, the digital implementation of the dynamic controller will result in a nonlinear feedback control system. To what extent the resulting nonlinear digital feedback control system satisfies the steady-state-error criteria of the original idealized linear prototype feedback control system is investigated. Digital controller implementations which use fixed-point arithmetic or floating-point arithmetic are considered. Designs which are well scaled are assumed, i.e., overflow nonlinearities in digital controllers are not addressed View full abstract»

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  • A general theory for the Wiener-Hopf design of multivariable control systems

    Page(s): 619 - 626
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (660 KB)  

    Multivariable control system design in a quadratic cost setting is treated for a completely general configuration. The class of all controllers is determined for which the general configuration is internally asymptotically stable and a quadratic cost functional is finite. This controller class is parameterized in terms of an arbitrary real rational strictly-proper matrix Z(s), which is analytic in the closed right-hand side of the s-plane. The choice Z≡0 gives the controller which minimizes the quadratic cost functional View full abstract»

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  • A fuzzy transient stability index in power system security evaluation

    Page(s): 662 - 666
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (516 KB)  

    A transient stability index is described for the online security evaluation of electric power systems by providing a measure for their level of security. A technique for constructing this index is developed, applying the principles of pattern recognition and fuzzy sets theory while the stability determination is based on the initial fault-on accelerations of machine rotors. The analysis of two sample transmission systems is presented to illustrate the application of the developed index View full abstract»

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  • Further remarks on potentially global stabilizability

    Page(s): 637 - 639
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (168 KB)  

    Given a control system with a nonlinear drift term, it is proved that a linear-like criterion for almost-global stabilizability can be stated, at least for control systems of the form x'=f( x)+Bu, where f is a polynomial but not necessarily homogeneous vector field. These stability criteria also allow for the control of the size of the region of attraction View full abstract»

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  • Output deadbeat control discrete-time multivariate systems

    Page(s): 644 - 648
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (392 KB)  

    An algorithm is presented to compute output deadbeat controls for linear multivariable systems. The algorithm, based on quadratic optimization with no cost on control (cheap control), is numerically stable and covers the most general cases. The resulting controls are internally stable and are shown to drive the outputs of the system to zero in minimum time using state feedback. The central part of the algorithm is the construction of the nonunique state-cost matrix. Two alternatives are presented having different complexities and resulting in solutions having different properties View full abstract»

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  • Switching curve deformation in a time-optimal closed-loop system

    Page(s): 654 - 656
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (264 KB)  

    The dynamics of a closed-loop system resulting from the solution of a time-optimal problem of a two-dimensional differential inclusion are discussed. It is shown that internal uncertainties (such as variations in resistances or parameter changes) cause trajectories of the closed-loop motion to (1) spiral convergently around the target and reach it in a finite time; (2) spiral divergently around the target and reach a limit curve; and (3) reach the target in a finite time in a sliding mode. Some suggestion for practical applications are given View full abstract»

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  • A modification of the Nevanlinna algorithm on the solution of the Hm×n-optimization problem

    Page(s): 627 - 629
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    A modification of the Nevanlinna algorithm is presented for the solution of the Hm×m-optimization problem. This is an essential modification when the Nevanlinna algorithm is applied to find the extremal function of the matrix H interpolation problem which deals with the case that the interpolation points have multiplicities. For the computation of the minimal H-norm, a pure matrices computational algorithm is used where the formulation is solely in terms of the coefficients of the inner function View full abstract»

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  • Multirate sampled-data control of two-time-scale systems

    Page(s): 642 - 644
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (244 KB)  

    Two-time-scale decoupling is adopted to obtain slow and fast subsystems. Based on these subsystems, a multirate composite control strategy is derived. It is shown how a recently presented multirate scheme can be modified to handle slow, nonzero mean disturbances, by introducing time incremental models. The improvements with the given multirate control law are illustrated by an example View full abstract»

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  • Measures of controllability and observability and residues

    Page(s): 648 - 650
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (232 KB)  

    The relationship between two measures of controllability and observability is derived, given a linear time-invariant system. Both of the measures are based on angles between various subspaces of the state space. It is shown that these measures can be used to bound the norm of the residues of the transfer function View full abstract»

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  • Numerical algorithms for eigenvalue assignment by constant and dynamic output feedback

    Page(s): 579 - 588
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (956 KB)  

    Algorithms are proposed for eigenvalue assignment (EVA) by constant as well as dynamic output feedback. The main algorithm is developed for single-input, multioutput systems and the results are then extended to multiinput, multioutput systems. In computing the feedback, use is made of the fact that the closed-loop eigenvalues can almost always be assigned arbitrarily close to the desired locations in the complex plane, provided the system satisfies the condition m+ p>n, where m, p, and n are , respectively, the number of inputs, outputs and states of the system. The EVA problem has been treated as a converse of the algebraic eigenvalue problem. The proposed algorithms are based on the implicitly shifted QR algorithm for solving the algebraic eigenvalue problem. The performance of the algorithms is illustrated by several numerical examples View full abstract»

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  • The square-root overdetermined recursive instrumental variable algorithm

    Page(s): 656 - 658
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (228 KB)  

    A square-root version of the overdetermined recursive instrumental variable (ORIV) algorithm is derived. This version improves the numerical stability of the algorithm, and avoids the problem of positive-definiteness of the inverse covariance matrix. The algorithm uses square-root arrays, and both orthogonal and hyperbolic rotations, as necessitated by the nature of the ORIV algorithm View full abstract»

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  • Strict Hurwitz property of polynomials under coefficient perturbation

    Page(s): 629 - 632
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (276 KB)  

    A simple procedure for computing the allowable interval coefficient perturbations of a strictly stable polynomial is presented. The amount of computations involved is very little, while the procedure is able to handle the case where the relative uncertainty of the polynomial coefficients are not known. It can also handle the case of linearly dependent parameter uncertainties. The procedure can also be modified to treat the case of simple nonlinear dependent parameter uncertainties. The details of the modified procedure will depend on the nature of the nonlinearity View full abstract»

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  • Least-squares output estimation with multirate sampling

    Page(s): 669 - 672
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (268 KB)  

    A least-squares output estimation algorithm is presented for applications where the output is sampled at a slower rate than the input. Given the sequence {u(kT), y(kJT )k=1,2,...}, where J is a positive integer and T is the basic sampling period, it is proven that the output estimation error converges to zero for instants at or between the output measurement instants. The assumptions required are essentially the same as for the case with equal sampling rates, i.e., for J=1. Simulation examples show excellent output estimation, based on measured y(kJT) with J=8 View full abstract»

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  • An adaptive controller which provides Lyapunov stability

    Page(s): 599 - 609
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    An adaptive controller that can provide exponential Lyapunov stability for an unknown linear time-invariant (LTI) system is presented. The only required a priori information about the plant is that the order of an LTI stabilizing compensator be known, although this can be reduced to assuming only that the plant is stabilizable and detectable at the expense of using a more complicated controller. This result extends the work of M. Fu and B.R. Barmish (see ibid., vol.AC-31, p.1097-1103, Dec. 1986) in which it is shown that there exists an adaptive controller which provides exponential Lyapunov stability if it is assumed that an upper bound on the plant order is known and that the plant lies in a known compact set; it shows that adaptive stabilization is possible under very mild assumptions without large state deviations View full abstract»

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  • Decomposition of 2-D linear systems into 1-D systems in the frequency domain

    Page(s): 639 - 641
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (212 KB)  

    A method is presented for the decomposition of the frequency domain of 2-D linear systems into two equivalent 1-D systems having dynamics in different directions and connected by a feedback system. It is shown that under some assumptions the decomposition problem can be reduced to finding a realizable solution to the matrix polynomial equation X(z1)P(z2 )+Q(z1)Y(z2 )=D(z1, z2). A procedure for finding a realizable solution X(z1 ), Y(z2) to the equation is given View full abstract»

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  • Approximation of infinite-dimensional systems

    Page(s): 610 - 618
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    A Fourier series-based method for approximation of stable infinite-dimensional linear time-invariant system models is discussed. The basic idea is to compute the Fourier series coefficients of the associated transfer function Td(Z) and then take a high-order partial sum. Two results on H convergence and associated error bounds of the partial sum approximation are established. It is shown that the Fourier coefficients can be replaced by the discrete Fourier transform coefficients while maintaining H convergence. Thus, a fast Fourier transform algorithm can be used to compute the high-order approximation. This high-order finite-dimensional approximation can then be reduced using balanced truncation or optimal Hankel approximation leading to the final finite-dimensional approximation to the original infinite-dimensional model. This model has been tested on several transfer functions of the time-delay type with promising results View full abstract»

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  • Adaptive aggregation methods for infinite horizon dynamic programming

    Page(s): 589 - 598
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (916 KB)  

    A class of iterative aggregation algorithms for solving infinite horizon dynamic programming problems is proposed. The idea is to interject aggregation iterations in the course of the usual successive approximation method. An important feature that sets this method apart from earlier ones is that the aggregate groups of states change adaptively from one aggregation iteration to the next, depending on the progress of the computation. This allows acceleration of convergence in difficult problems involving multiple-ergodic classes for which methods using fixed groups of aggregate states are ineffective. No knowledge of special problem structure is utilized by the algorithms View full abstract»

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  • A hierarchical approach to bargaining in power pool management

    Page(s): 666 - 669
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (348 KB)  

    Co-operative operation of an electric power pool is considered. A three-level dynamic hierarchical decomposition approach to determine the intrapool power exchanges over time is proposed. The approach results in independent operation of the electric utilities. To guarantee both fair division of the cost savings achieved and feasible intrapool energy exchanges, the utilities are coordinated in the form of electric power prices View full abstract»

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  • A stopping rule for least-squares identification

    Page(s): 659 - 662
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (268 KB)  

    A stopping rule for least-squares identification is developed. The stopping rule is determined by the construction of a confidence ellipsoid. For any predetermined estimation error ε>0, if the iterates are inside of an ellipsoidal confidence region with volume less than or equal to εr, then the recursive online algorithm will be terminated with high probability 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