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Automatic Control, IEEE Transactions on

Issue 6 • Date June 1987

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Displaying Results 1 - 25 of 25
  • [Front cover and table of contents]

    Publication Year: 1987 , Page(s): 0
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    Freely Available from IEEE
  • Scanning the issue

    Publication Year: 1987 , Page(s): 465
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    Freely Available from IEEE
  • Editorial: Give us a break

    Publication Year: 1987 , Page(s): 466
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    Freely Available from IEEE
  • Introduction to system science

    Publication Year: 1987 , Page(s): 560
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    Freely Available from IEEE
  • [Back cover]

    Publication Year: 1987 , Page(s): 0
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    Freely Available from IEEE
  • State-space measures for stability robustness

    Publication Year: 1987 , Page(s): 509 - 512
    Cited by:  Papers (16)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (464 KB)  

    Stability robustness measures for a perturbed linear feedback system are derived based on state-space models of the system. The system may be a continuous-time or discrete-time system. The perturbations are modeled as additive perturbation matrices. Necessary and sufficient conditions for the stability of the perturbed closed-loop system for all perturbations of norm bounded by some positive number are obtained. The destabilizing perturbations of minimal norm are characterized. It is shown by an example that there are cases when the destabilizing perturbations of minimal norm are all complex. The results are expressed in terms of induced operator norms. These are later specialized to the Euclidean norm and expressed in terms of singular values. A simple example is also included to illustrate an application of the results of this note. View full abstract»

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  • An Lerror bound for the phase approximation problem

    Publication Year: 1987 , Page(s): 517 - 518
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (216 KB)  

    Given a random process spectral factor w(\cdot) , the phase approximation algorithm, initiated by Jonckheere and Helton [1], constructs a reduced-order spectral factor \hat{w}(\cdot) such that \parallel w/w^{\ast }-\hat{w}/ \hat{w}^{\ast }\parallel is small in the Hankel-norm sense. In this note, we derive the L^{\infty } error bound \parallel w/w^{\ast } - \hat{w}/\hat{w}^{\ast }\parallel_{\infty } \leq 4(\sigma _{k+1} + ... +\sigma _{N}) , where the σ's are the canonical correlation coefficients. A similar result holds in the multivariable case. View full abstract»

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  • Consistent estimation of the order of stochastic control systems

    Publication Year: 1987 , Page(s): 531 - 535
    Cited by:  Papers (7)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (368 KB)  

    A consistent estimate of the order of feedback control systems with unknown matrix coefficients estimated by the least-squares method is derived by minimizing a modified version of the Bayesian information criterion. View full abstract»

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  • On stochastic model reduction

    Publication Year: 1987 , Page(s): 530 - 531
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    In a recent paper by Zhou and Khargonekar [2], an example seemed to indicate that the stochastic model reduction procedure of Jonckheere and Helton [1] falls short of what could actually be achieved. In this note, we show that a variant of the algorithm of Jonckheere and Helton, already proposed in the original manuscript [1, Sect. IV.C], yields results competitive with those of Zhou and Khargonekar [2]. View full abstract»

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  • Feedback control and classification of generalized linear systems

    Publication Year: 1987 , Page(s): 483 - 494
    Cited by:  Papers (15)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1328 KB)  

    We present a unified theory of control synthesis for generalized linear (i.e., descriptor) systems using constant-ratio proportional and derivative (CRPD) feedback. Our framework includes the theory of static state feedback and output feedback for regular state-space systems as a special case. The main elements of this theory include 1) a covering of the space of all systems, both regular and singular, by a family of open and dense subsets indexed by the unit circle; 2) a group of transformations which may be viewed as symmetries of the cover; 3) an admissible class of feedback transformations on each subset which is specifically adapted to that subset. We obtain a general procedure of control synthesis of CRPD feedback for generalized linear systems which uses the symmetry transformations to systematically reduce each synthesis problem to an ordinary static-state feedback (or output feedback) synthesis problem for a corresponding regular system. We apply this approach to obtain natural generalizations of the disturbance decoupling theorem, the pole assignment theorem, and the Brunovsky classification theorem. View full abstract»

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  • Fitting noncausal autoregressive signal plus noise models to noisy non-Gaussian linear processes

    Publication Year: 1987 , Page(s): 547 - 552
    Cited by:  Papers (26)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (656 KB)  

    The problem of estimating the parameters of a noncausal autoregressive signal model from noisy observations is considered. The signal is assumed to be non-Gaussian. The measurement noise is allowed to be non-Gaussian. Two techniques that use both autocorrelations and third-order autocumulants of the data are presented for parameter estimation. Knowledge of the probability distribution of the driving noise is not required. Several simulation examples are presented to illustrate the two methods. The problem of model order selection is also addressed. View full abstract»

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  • Loop recovery and robust state estimate feedback designs

    Publication Year: 1987 , Page(s): 512 - 517
    Cited by:  Papers (10)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (616 KB)  

    The loop recovery technique has been generalized for nonminimum-phase plants in the following sense. The open-loop properties of certain partial state feedback designs are recovered in a state estimation feedback controller design involving the addition of fictitious plant noise. The partial state is the state of a minimum-phase factor in a minimum-phase, all-pass factored form model. Of course, robust designs are expected only when these are achieved for the case of partial state feedback of only the minimum-phase factor states. This may not always be possible. For the case of minimum-phase plants, known designs and theory are recovered as a special case. The theory and designs of this note generalize to include frequency shaping of both the control objectives and the loop recovery. View full abstract»

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  • Ripple-free deadbeat control for sampled-data systems

    Publication Year: 1987 , Page(s): 474 - 482
    Cited by:  Papers (25)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (760 KB)  

    In this paper the ripple-free deadbeat control problem for sampled-data systems is considered. This control objective is to settle the error to zero for all time after some finite settling time, in other words to eliminate the ripples between the sampling instants in deadbeat control of sampled-data systems. The necessary and sufficient conditions to solve this problem are derived and related to the system type, and a method of constructing the ripple-free deadbeat control system is presented. View full abstract»

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  • An efficient algorithm for reducing transfer functions to coprime forms

    Publication Year: 1987 , Page(s): 521 - 523
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (200 KB)  

    A very simple and efficient algorithm is formulated for reducing any transfer function to its coprime form without long divisions. View full abstract»

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  • Performance measures for control computers

    Publication Year: 1987 , Page(s): 467 - 473
    Cited by:  Papers (17)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (896 KB)  

    As real-time systems become more complex, the problem of controlling them safely becomes more difficult. When computers are in control of time-critical systems such as aircraft, nuclear reactors, and life-support systems, they must meet stringent performance requirements. However, these requirements cannot be properly stated without appropriate performance measures. We review and analyze such measures in this paper. View full abstract»

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  • Direct globally convergent adaptive regulation of stable multivariable plants

    Publication Year: 1987 , Page(s): 543 - 547
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (536 KB)  

    A simple globally convergent direct methodology for adaptive regulation of stable plants, assuming convergence of the parameters, is presented. The development is strictly in terms of the input-output representations and is based on the stable coprime factorization approach [14]. View full abstract»

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  • Modal decoupling insensitivity

    Publication Year: 1987 , Page(s): 524 - 526
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (240 KB)  

    This note deals with the design of an output feedback control system such that selected closed-loop eigenvalues are insensitive, while the corresponding eigenvectors preserve a prescribed decoupling under parameter variation. This results in restricting specified elements of an eigenvector to be insensitive, rather than the entire eigenvector. This requirement is henceforth referred to as modal decoupling insensitivity. Sufficient conditions for modal decoupling insensitivity are derived. These conditions offer the advantage of increased flexibility in eigenvector assignment, but the constraint on the feedback matrix is more restrictive. A numerical example is presented to illustrate the design procedure. View full abstract»

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  • Inverse of polynomial matrices in the irreducible form

    Publication Year: 1987 , Page(s): 507 - 509
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (304 KB)  

    An algorithm is developed for finding the inverse of polynomial matrices in the irreducible form. The computational method involves the use of the left (right) matrix division method and the determination of linearly dependent vectors of the remainders. The obtained transfer function matrix has no nontrivial common factor between the elements of the numerator polynomial matrix and the denominator polynomial. View full abstract»

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  • Stochastic teams with nonclassical information revisited: When is an affine law optimal?

    Publication Year: 1987 , Page(s): 554 - 559
    Cited by:  Papers (31)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (504 KB)  

    In this note we consider a parameterized family of two-stage stochastic control problems with nonclassical information patterns, which includes the well-known 1968 counterexample of Witsenhausen. We show that whenever the performance index does not contain a product term between the decision variables, the optimal solution is linear in the observation variables. The parameter space can be partitioned into two regions in one of which the optimal solution is linear, whereas in the other it is inherently nonlinear. Extensive computations using two-point piecewise constant policies and linear plus piecewise constant policies provide numerical evidence that nonlinear policies may indeed outperform linear policies when the product term is present. View full abstract»

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  • Optimal model matching control systems: Minmax approach

    Publication Year: 1987 , Page(s): 518 - 521
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (384 KB)  

    In this note, the optimal interpolation theory is applied to deal with the model matching control problem. With this approach, we construct a best approximate model matching control in the sense of an H^{\infty } -norm. This approximation is constructed for the imperfect model matching case; perfect model matching results whenever it is possible. View full abstract»

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  • Global stability proofs for continuous-time indirect adaptive control schemes

    Publication Year: 1987 , Page(s): 537 - 543
    Cited by:  Papers (19)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (672 KB)  

    This note presents a general stability proof for continuous-time adaptive control, with very general assumptions on the identifier and controller. We show that if the exogenous input signal is rich enough, then both the identifier and the controller converge to their "true" values. Applications of the proof to pole placement design and design based on the factorization approach are discussed. View full abstract»

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  • Analysis of singular systems using orthogonal functions

    Publication Year: 1987 , Page(s): 527 - 530
    Cited by:  Papers (16)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (456 KB)  

    The use of orthogonal functions to analyze singular systems is investigated. It is shown that the differential-algebraic system equation may be converted to an algebraic generalized Lyapunov equation that can be solved for the coefficients of x(t) in terms of the orthogonal basis functions. This generalized Lyapunov equation may be considered as a "discrete" equation on the slow subspace of the system, and as a "continuous" equation on its fast subspace. Necessary and sufficient conditions for the existence of a unique solution are given in terms of the relative spectrum of the system. A generalized Bartels/Stewart algorithm based on the QZ algorithm is presented for its efficient solution. Relations are drawn with the invariant subspaces of the system. View full abstract»

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  • On bang-bang solutions of stochastic differential games

    Publication Year: 1987 , Page(s): 535 - 537
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    We consider two classes of scalar stochastic differential games with hard constraints on controls. The solutions are found to be bang-bang, by extending a technique developed earlier for stochastic optimal control problems. View full abstract»

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  • Robust stability with structured real parameter perturbations

    Publication Year: 1987 , Page(s): 495 - 506
    Cited by:  Papers (66)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1000 KB)  

    This paper considers the problem of robust stabilization of a linear time-invariant system subject to variations of a real parameter vector. For a given controller the radius of the largest stability hypersphere in this parameter space is calculated. This radius is a measure of the stability margin of the closed-loop system. The results developed are applicable to all systems where the closed-loop characteristic polynomial coefficients are linear functions of the parameters of interest. In particular, this always occurs for single-input (multioutput) or single-output (multiinput) systems where the transfer function coefficients are linear or affine functions of the parameters. Many problems with transfer function coefficients which are nonlinear functions of physical parameters can be cast into this mathematical framework by suitable weighting and redefinition of functions of physical parameters as new parameters. The largest stability hyperellipsoid for the case of weighted perturbations and a stability polytope in parameter space are also determined. Based on these calculations a design procedure is proposed to robustify a given stabilizing controller. This algorithm iteratively enlarges the stability hypersphere or hyperellipsoid in parameter space and can be used to design a controller Io stabilize a plant subject to given ranges of parameter excursions. These results are illustrated by an example. View full abstract»

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  • A Chi-square test for fault-detection in Kalman filters

    Publication Year: 1987 , Page(s): 552 - 554
    Cited by:  Papers (18)  |  Patents (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (312 KB)  

    A test for real-time detection of soft failures in navigation systems using Kalman filters has been proposed by Kerr. The test is based on the overlap between the confidence regions associated with two estimates, one obtained from a Kalman filter using on-line measurements, and the other based solely on a priori information. An alternate computational technique is presented which is based on constructing a chi-square test statistic from the difference between the two estimates and comparing it to a precomputed threshold. The chi-square test avoids the iterative computations required by the two-ellipsoid method for dimensions of two and higher. 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