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Automatic Control, IEEE Transactions on

Issue 5 • Date October 1976

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Displaying Results 1 - 25 of 53
  • [Front cover and table of contents]

    Publication Year: 1976 , Page(s): 0
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    Freely Available from IEEE
  • Comments on "Cooperative games and vector-valued criteria problems"

    Publication Year: 1976 , Page(s): 806 - 807
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    A theorem in the above paper,[1] giving sufficient conditions for the local Pareto optimality, is shown to be incorrect by a counter-example and a revision of its proof. Moreover, an alternative formulation of this theorem is suggested. View full abstract»

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  • Author's reply

    Publication Year: 1976 , Page(s): 807 - 808
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    First Page of the Article
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  • [Back cover]

    Publication Year: 1976 , Page(s): 0
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    Freely Available from IEEE
  • Computational experience with the solution of the matrix Lyapunov equation

    Publication Year: 1976 , Page(s): 799 - 800
    Cited by:  Papers (8)
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    This correspondence presents a comparative study of three methods for the numerical solution of the matrix Lyapunov equation. The test case is a 24th-order system with highly underdamped eigenvalues and a rather high degree of stiffness. The conclusions favor a method by Bartels and Stewart based on a reduction to Schur form of the A matrix. View full abstract»

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  • More on the conjecture by Šiljak

    Publication Year: 1976 , Page(s): 805 - 806
    Cited by:  Papers (1)
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    Let \tilde{a} be a special class of matrices with complex elements. This correspondence considers the properties of any A \in \tilde{a} which will guarantee that if G = - (A*H + HA) , then for any given Hermitian positive definite matrix H , there exists a unique nonsingular Hermitian matrix G . Properties of the eigenvalues of A and G are established. View full abstract»

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  • A decomposition of near-optimum regulators for systems with slow and fast modes

    Publication Year: 1976 , Page(s): 701 - 705
    Cited by:  Papers (93)
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    For systems with slow and fast subsystems a near-optimum state regulator is composed of two subsystem regulators. Conditions for complete separation of slow and fast regulator designs are formulated. A second-order approximation of the optimal performance is achieved without the knowledge of the small singular perturbation parameter. View full abstract»

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  • Zeros of the system matrix

    Publication Year: 1976 , Page(s): 795 - 797
    Cited by:  Papers (4)
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    This note provides an easy characterization of the zeros of the system matrix in terms of a strong version of system reachability and observabillty. Interpreted in abstract terms, it yields Wonham and Morse's characterization of zero. The results hold for systems defined over an arbitrary field. View full abstract»

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  • On the optimality of nonlinear designs in the control of linear decentralized systems

    Publication Year: 1976 , Page(s): 797
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    The purpose of this note is to point out the fact that in the decentralized optimum control of linear deterministic systems with instantaneous output feedback one might have nonlinear designs that are superior to the best linear ones. View full abstract»

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  • Modelling linear systems for pulsewidth-modulated control

    Publication Year: 1976 , Page(s): 739 - 746
    Cited by:  Papers (1)
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    An approximate linear model is developed for a linear process in which the control signal can assume only two values, U_{\max } and U_{\min} , and which is controlled by varying the fraction δnof a sampling cycle of duration T that the control is at U_{\max } . The dynamic equations are of the form w_{n+1} = \Phi (T)w_{n} + \bar{\Gamma }(T)r_{n} where wnis related to the average state xnover one cycle, and r_{n} = \delta _{n} - \delta _{s} where δsis the steady-state value of δnrequired to maintain a desired average state xd. The system error e(nT) at sampling intervals is related to these variables by an equation of the form e(nT) = M_{1}w_{n} + M_{2}\delta _{s} + M_{3}b , where b is a bias vector. These relations may be used to design a linear control system by well-known techniques for discrete-time systems. The method is illustrated by the design of a third-order process which could represent a temperature control problem. Simulation results are given for a design that includes a Kalman filter for estimating the inaccessible states. View full abstract»

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  • Partitioned Ricatti solutions and integration-free doubling algorithms

    Publication Year: 1976 , Page(s): 677 - 689
    Cited by:  Papers (13)
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    Generalized partitioned solutions (GPS) of Riccati equations (RE) are presented in terms of forward and backward time differential equations that are theoretically interesting, possibly computationally advantageous, as well as provide interesting interpretations of these resuits, e.g., in terms of generalized partial observability and controllability matrices. The GPS are the natural framework for the effective change of initial conditions, and the transformation of backward RE to forward RE and vice-versa. The GPS are given in terms of families of forward or backward RE, and constitute generalizations to time-varying RE of well-known solution algorithms such as the X - Y or Chandrasekhar algorithms. Most importantly, based on the GPS, computationally effective algorithms are obtained for the numerical solution of RE. These partitioned numerical algorithms (PNA) have a decomposed or "partitioned" structure, namely, they are given exactly in terms of a set of elemental solutions which are completely decoupled, and as such computable in either a parallel or serial processing mode. Further, the overall solution is given exactly in terms of a simple recursive operation on the elemental solutions. Finally, the PNA for a large class of RE, namely those with periodic or constant matrices, are completely integration-free, other than for a subinterval of the total computation interval, whose length, moreover, can be chosen arbitrarily. Also based on the GPS, a computationally attractive numerical algorithm is obtained for the computation of the steady-state solution of time-invariant RE. This algorithm results from doubling the length of the partitioning interval, and straightforward use of the GPS. The resulting "doubling" PNA is fast and is also essentially, integration-free requiring integration only in an initial subinterval, whose length is arbitrary, and subsequently consisting of simple iterative operations at the end of each time-interval which is twice as long as the interval in the previous iterations, i.e., doubling. View full abstract»

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  • Min-max quadratic cost control of systems described by approximate models

    Publication Year: 1976 , Page(s): 651 - 659
    Cited by:  Papers (1)  |  Patents (1)
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    This paper considers the design of output regulators with the use of approximate models. The measure of the approximation between process and model outputs is represented by a bound in norm of the output error signals and it requires the computation of two numbers. The design is achieved with a rain-max approach where control and error signals are the two antagonists. The min-max solution is obtained as a linear function of the model state (open-loop solution). It is shown that no dosed-loop controls can improve the open-loop min-max performance. Conditions are given so as to preserve the min-max performance by means of proportional feedback of the system's output. In this case the min-max feedback law is obtained (closed-loop solution). View full abstract»

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  • Finite regions of attraction for multinonlinear systems and its application to the power system stability problem

    Publication Year: 1976 , Page(s): 716 - 721
    Cited by:  Papers (4)
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    In this short paper, regions of attraction for multinonlinear systems are obtained using the sector violation information of the nonlinearities when the system is cast in the Lure'-Popov form. An explicit expression for this domain is obtained. The results are applied to a 3-machine power system for estimating the stability region. View full abstract»

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  • Inners and stability of dynamic systems

    Publication Year: 1976 , Page(s): 809 - 810
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    First Page of the Article
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  • On a class of minimum energy controls related to spline functions

    Publication Year: 1976 , Page(s): 725 - 727
    Cited by:  Papers (1)
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    The problem of determining a minimum energy control for a dynamically interconnected set of p single input-single output finite-dimensional linear time-varying dynamical systems, for which the outputs are constrained to assume prescribed values at different points in time, is considered. It is shown that the solution (optimal controller) is obtained by performing a linear operation on an appropriate vector-valued generalized interpolating spline. View full abstract»

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  • Generalized Chandrasekhar algorithms: Time-varying models

    Publication Year: 1976 , Page(s): 728 - 732
    Cited by:  Papers (8)
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    The Riccati equation (RE) plays a fundamental role in optimal control theory, linear estimation, radiative transfer, neutron transport theory, etc. Its effective, numerical solution constitutes the integral prerequisite to the solution of important problems in the above and related fields. A computationally advantageous approach to the solution of matrix Re's is the so-called x-y or Chandrasekhar algorithm through which the matrix RE is replaced by two coupled differential equations of lesser dimensionality. These previous Chandrasekhar algorithms were, however, restricted to the case of time-invariant models. In this short paper, generalized x-y or Chandrasekhar algorithms are presented that are applicable to time-varying models as well as time-invariant ones. Backward and forward time differentiations are introduced that readily yield the generalized Chandrasekhar algorithms as well as provide several interesting interpretations of these results. Furthermore, the possible computational advantages, as well as the theoretical significance of the generalized Chandrasekhar algorithms are explored. View full abstract»

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  • Fault detection in digital filter systems

    Publication Year: 1976 , Page(s): 800 - 802
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    The use of a parameter identification procedure to detect faults in hardware used to implement a broad class of linear algorithms defined as digital filters is presented. Using the filter coefficient estimates produced by the identifier, a method of measuring the acceptability of the filtering algorithm is suggested and a numerical example is given. View full abstract»

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  • On the matrix Riccati equation for linear systems with random gain

    Publication Year: 1976 , Page(s): 770 - 771
    Cited by:  Papers (21)
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    Considered is the asymptotic property of the discrete-time matrix Riccati equation arising in the optimal control of linear systems with a random gain. The instability and stability conditions are derived in terms of the degree of stability of the state transition matrix. View full abstract»

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  • Optimal phase demodulation

    Publication Year: 1976 , Page(s): 732 - 737
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    A new realization method for synthesis of the optimal cyclic loss nonlinear filter using a third generation digital computer is proposed. This method consists of carrying a finite set of Fourier coefficients of the conditional density of signal given the observations, and updating these coefficients to determine the Fourier coefficients of the a posteriori density when new observations are obtained. The filtering problem considered is that of phase demodulation. Monte Carlo evaluation of performance of this Fourier filter is given and compared with previous methods. Further, the accuracy and estimate computation time of this method are determined and compared with other methods. View full abstract»

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  • Weak and strong feedback free processes

    Publication Year: 1976 , Page(s): 737 - 739
    Cited by:  Papers (5)
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    A class of feedback free processes [1]-[3] is introduced called the class of strong feedback free processes. Equivalent formulations of the strong feedback free (SFF) property are given and compared with equivalent formulations of the earlier definition [1]-[3] of feedback free processes. These latter processes are now termed weak feedback free (WFF) processes. Applications to a simulation experiment and an econometric example are briefly discussed. View full abstract»

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  • On some z -transform formulas

    Publication Year: 1976 , Page(s): 785 - 786
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    Given the z -transform F(z) of f(t) , a formula for computing the z =transform of t^{n}f(t) is established. Based on this result, a new formula for the z -transform of tkis given. View full abstract»

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  • A class of controllable nonlinear systems

    Publication Year: 1976 , Page(s): 787 - 789
    Cited by:  Papers (4)
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    Sufficient conditions for global and local controllability of the nonlinear system frac{d}{dt}x(t) = A(t,x(t), u(t))x(t) + B(t)u(t) + f(t,x(t), u(t)) and its perturbed system are given. These conditions extend some previous results through the removal of certain boundedness conditions involving the functions ( A,f ) and their partial derivatives. View full abstract»

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  • A linear-quadratic-Gaussian control problem with innovations-feedthrough solution

    Publication Year: 1976 , Page(s): 721 - 725
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    The structure of the separation-theorem solution to the standard linear-quadratic-Gaussian (LQG) control problem does not involve direct output feedback as a consequence of the form of the performance index. It is shown here that the performance index may be generalized in a natural fashion so that the optimal control law involves output feedback [or equivalently, innovations feedthrough (IF)]. Applications where this formulation may be advantageous are indicated through an examination of properties of the IF control law. View full abstract»

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  • A model-referenced controller for stabilizing large transient swings in power systems

    Publication Year: 1976 , Page(s): 746 - 750
    Cited by:  Papers (7)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (528 KB)  

    This short paper deals with a control strategy which is considered reasonable for on-line stabilization of the large transient swings that occur in power systems following a major system disturbance. The strategy is compared to other similar strategies both in terms of philosophy and physical application. The example shows the benefit of on-line coordinated application of a dynamic brake and network switching to the transient stability problem when control decisions are implemented using a proper coordinating control strategy. View full abstract»

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  • Multiple-objective problems: Pareto-optimal solutions by method of proper equality constraints

    Publication Year: 1976 , Page(s): 641 - 650
    Cited by:  Papers (27)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1104 KB)  

    The method of proper equality constraints for obtaining the set P of all Pareto-optimal solutions of a general multiple-objective problem and the set M of all performance index vectors attainable by the Pareto-optimal solutions is presented in this paper. These sets are very useful for those designers, performance analyzers, control agents, and decision makers who are faced with multiple objectives to make appropriate compromises, tradeoffs or choices. That this method is effective for general applications is clearly demonstrated by examples with various kinds of complexity. New necessary and sufficient conditions for Pareto optimality, local Pareto optimality, and local maximal index vectors are also presented. These conditions and the method are useful for both computation and analysis. New observations on a generalized classical Pareto-optimum problem are thereby obtained. 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