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Automatic Control, IEEE Transactions on

Issue 5 • Date October 1982

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Displaying Results 1 - 25 of 31
  • [Front cover and table of contents]

    Page(s): 0
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    Freely Available from IEEE
  • Announcement: Manuscript submission for papers

    Page(s): 1013
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    Freely Available from IEEE
  • Comments on "On the application of matrix generalized inverses to the design of observers for time-varying and time-invariant linear systems"

    Page(s): 1137 - 1138
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    In this discussion, several comments on the eigenvalue assignment algorithm in the above paper are made for the purpose of better illustration and clarity. View full abstract»

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  • Comments on the Wong and Polak minimax approach to accuracy optimization of instrumental variable methods

    Page(s): 1138 - 1139
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    Optimizing the accuracy of instrumental variable (IV) estimates on a minimax basis is discussed. Some flaws in an earlier approach of this kind are pointed out. It is indicated that the minimax approach to accuracy optimization of IV estimates, although conceptually attractive, will, in general, lead to intractable problems. View full abstract»

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  • Author's reply

    Page(s): 1138
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    First Page of the Article
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  • Comments on "Instability of optimal-aim control"

    Page(s): 1139 - 1140
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    This note discusses the conclusions of the above paper on the instability of optimal-aim strategies relative to controllable linear systems. Contrary to these conclusions, it is proved that under fully implemented optimal-aim strategies, all controllable linear systems are stabilized. View full abstract»

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  • Author's reply

    Page(s): 1139
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    First Page of the Article
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  • Author's reply

    Page(s): 1140
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    First Page of the Article
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  • [Back cover]

    Page(s): 0
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    Freely Available from IEEE
  • A duality theorem for max-min control problems

    Page(s): 1129 - 1131
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    Given an optimal control problem of the minimax type, we propose another problem which is called dual to the original one. It is shown that under certain conditions, their extreme values are equal. View full abstract»

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  • The computer-controlled stabilization of a noisy two-dimensional hyperbolic system

    Page(s): 1033 - 1043
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    The computer-controlled stabilization of a noisy two-dimensional hyperbolic system is described. A meter-square flexible wire mesh, suspended vertically in tension by rigid boundaries, supported transverse deflections about a planar equilibrium which were destabilized by the application of a transverse electrostatic bias. The number of open-loop unstable deflection modes was adjustable with bias strength. Using information from up to nine electrostatic deflection sensors, a minicomputer manipulated nine electrostatic deflection actuators so as to stabilize the mesh. Linear-quadratic-Gaussian control laws, based upon a truncated normal mode system description and modified to include rate-limited deflection integration, were implemented throughout. Experiments are reported in which the open-loop system stability, the number and location of actuators and sensors used, and the computer sampling rate were variable. Three open-loop unstable modes were stabilized at an electrostatic bias pressure nearly three times that required to initially destabilize the mesh. The limits of this stability, regime and the resulting mesh surface tolerances were found to be consistent with theory. Spillover was experimentally observed to be a predictable cause of mesh deflection destabilization. View full abstract»

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  • On the design of optimal regulators using time-multiplied performance index with prescribed closed-loop eigenvalues

    Page(s): 1128 - 1129
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    In this paper, an algorithm is developed to compute an optimal constant state feedback in a linear multivariable system yielding prescribed closed-loop eigenvalues and minimizing, in an average sense, a given time-multiplied quadratic performance index. An example is worked out to reveal the contradiction of the conclusions in [1]-[3] concerning the effect of that performance index on the transient response of the control system. View full abstract»

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  • Constrained output feedback for large discrete-time systems

    Page(s): 1119 - 1122
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    This paper discusses the optimal control of large systems in which the costs of intersubsystem communication are significant. A method is presented for determination of the relative benefits of implementation of any of the intersubsystem links. Given the links to be used, two recursive algorithms have been presented for the determination of optimal output feedback gains. The first method shows computational advantage when only a few links are implemented, and the second when nearly full information exchange is available. View full abstract»

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  • Almost invariant subspaces: An approach to high gain feedback design--Part II: Almost conditionally invariant subspaces

    Page(s): 1071 - 1085
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    In Part I of this paper, almost controlled invariant subspaces were studied. In this part we will consider their duals, the almost conditionally invariant subspaces. These concepts give immediately by dualization of the almost disturbance decoupling control by state feedback the solution of the almost disturbance decoupled estimation problem. Finally, we consider the problem of approximate disturbance decoupling by measurement feedback and it is shown that this problem is solvable to any arbitrary degree of accuracy if and only if: 1) almost disturbance decoupling by state feedback, and 2) almost disturbance decoupled estimation of the to-be-controlled output are both possible. View full abstract»

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  • A finitely convergent algorithm for convex inequalities

    Page(s): 1126 - 1127
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    In engineering design problems, it is often necessary to find a solution to a system of nonlinear inequalities in which the functions involved are not necessarily differentiable. In this paper, assuming convexity of the functions, an algorithm is presented for solving such systems of inequalities in a finite number of iterations. View full abstract»

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  • The range error test in the structural identification of linear multivariable systems

    Page(s): 1044 - 1054
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    Among the approaches that have been proposed in recent years for the identification of discrete-time linear multivariable systems, very efficient procedures are based on the introduction of a set of input-output canonical models and on the separate determination of the process structure (structural identification) and parameters (parametric identification). This paper introduces a new simple test which allows us to perform the structural identification without the drawbacks usually associated with singularity tests. The proposed test gives an a priori prediction of the model performance in order to avoid trial and error procedures in the determination of a suitable structure for the process to be identified. View full abstract»

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  • Graph-theoretic approach to controllability and localizability of decentralized control systems

    Page(s): 1096 - 1108
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    The controllability and the localizability problems are considered under the decentralized information structure using some concepts from graph theory. First of all, the information structure graph is introduced for a decentralized control system based upon local output controllability, matrices between stations when a local output feedback law is applied, and some invariant properties of the graph with respect to local output feedback laws are driven. Then by using these results, necessary and sufficient conditions of controllability under decentralized information structure are obtained. Also obtained are several conditions for localizability, of decentralized control systems, which is newly introduced in the present paper as an extended concept of a class of disturbance localization and decoupling for centralized systems. View full abstract»

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  • Further comments on "On parameter and structural identifiability: Nonunique observability/reconstructibility for identifiable systems, other ambiguities, and new definitions"

    Page(s): 1136 - 1137
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    Some disadvantages of the proposed identifiability definitions are shown and relationships with the classical terminology are discussed. View full abstract»

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  • Stability of a matrix polynomial in discrete systems

    Page(s): 1122 - 1124
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    Two sufficient conditions that the determinant of a nonsingular real (m times m) matrix polynomial ofnth order has all its roots inside the unit circle have been obtained. These conditions are represented in terms of rational functions of the coefficient matrices. Therefore, these conditions do not require the computation of the determinant polynomial. The first condition is given in terms of the positive definiteness of an (mn times mn) symmetric matrix, while the second condition is expressed by the positive definiteness of an (m times m) Hermitian matrix which is a function ofz, |z| leq 1. The first condition implies the second, and hence is more restrictive than the second. View full abstract»

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  • Sharpness relation and decidable fuzzy sets

    Page(s): 1113
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    The concept of "decidability" for fuzzy sets is defined. We prove that there exist fuzzy sets which do not have a decidable "sharpened" version and fuzzy, sets which are not "sharpened" versions of decidable fuzzy sets. View full abstract»

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  • Algebraic design techniques for reliable stabilization

    Page(s): 1085 - 1095
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    In this paper we study two problems in feedback stabilization. The first is the simultaneous stabilization problem, which can be stated as follows. Given plantsG_{0}, G_{1},..., G_{l}, does there exist a single compensatorCthat stabilizes all of them? The second is that of stabilization by a stable compensator, or more generally, a "least unstable" compensator. Given a plantG, we would like to know whether or not there exists a stable compensatorCthat stabilizesG; if not, what is the smallest number of right half-place poles (counted according to their McMillan degree) that any stabilizing compensator must have? We show that the two problems are equivalent in the following sense. The problem of simultaneously stabilizingl + 1plants can be reduced to the problem of simultaneously stabilizinglplants using a stable compensator, which in turn can be stated as the following purely algebraic problem. Given2lmatricesA_{1}, ..., A_{l}, B_{1}, ..., B_{l}, whereA_{i}, B_{i}are right-coprime for alli, does there exist a matrixMsuch thatA_{i} + MB_{i}, is unimodular for alli?Conversely, the problem of simultaneously stabilizinglplants using a stable compensator can be formulated as one of simultaneously stabilizingl + 1plants. The problem of determining whether or not there exists anMsuch thatA + BMis unimodular, given a right-coprime pair (A, B), turns out to be a special case of a question concerning a matrix division algorithm in a proper Euclidean domain. We give an answer to this question, and we believe this result might be of some independent interest. We show that, given twon times mplantsG_{0} and G_{1}we can generically stabilize them simultaneously provided eithernormis greater than one. In contrast, simultaneous stabilizability, of two single-input-single-output plants, g0and g1, is not generic. View full abstract»

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  • Self-tuning regulator design for adaptive control of aircraft wing/store flutter

    Page(s): 1014 - 1023
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    The application of the self-tuning regulator concept to adaptively control aircraft wing/store flutter instability is described. A simple design based on a reduced-order aircraft model has been successfully tested on a high-order simulation of an advanced aircraft, and performance was found to be comparable to another design using on-line maximum likelihood identification of plant parameters. The main advantage of the self-tuning regulator is its simplicity, while the main disadvantage is the inadequacy of prior performance guarantees. View full abstract»

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  • Identifiability of time-varying parameters in a class of linear dynamical systems

    Page(s): 1114 - 1116
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    This paper deals with the problem of determining time-varying parameters in a system described by a linear differential equation from noise-free observations of input/output signals. For the special case of periodically varying parameters, two identifiability questions are discussed: 1) how to check whether the available experimental data allow unique determination of system parameters, and 2) how to design the experiment to accomplish this with a priori knowledge. Necessary and sufficient conditions for identifiability are obtained. View full abstract»

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  • On the good use of the spectral radius of a matrix

    Page(s): 1134 - 1135
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    In a recent correspondence [1], attention was called to the "misuse" of spectral radius of system matrices in stability, analysis. An assertion made in [1] is elaborated on more precisely in this note. In addition, we present some interesting stability results for "slowly varying" linear systems, highlighting the crucial role played by the spectral radius in convergence analysis. View full abstract»

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  • An algorithm to determine if two matrices have common eigenvalues

    Page(s): 1131 - 1133
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    Given two real lower Hessenberg matricesAandBof ordernandm (m leq n), respectively, a symmetric matrix of ordernis constructed such that wheneverSis nonsingular,AandBdo not have an eigenvalue in common. WhenSis singular, its nullity, is the same as the number of common eigenvalues betweenAandB. A well-known classical result on the relative primeness of two polynomials and the associated Bezoutian matrix is included as a special case. 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