By Topic

Automatic Control, IEEE Transactions on

Issue 4 • Date April 1985

Filter Results

Displaying Results 1 - 19 of 19
  • [Front cover and table of contents]

    Page(s): 0
    Save to Project icon | Request Permissions | PDF file iconPDF (164 KB)  
    Freely Available from IEEE
  • In memoriam: Howard Elliot (1952-1984)

    Page(s): 321
    Save to Project icon | Request Permissions | PDF file iconPDF (159 KB)  
    Freely Available from IEEE
  • Full text access may be available. Click article title to sign in or learn about subscription options.
  • [Back cover]

    Page(s): 0
    Save to Project icon | Request Permissions | PDF file iconPDF (129 KB)  
    Freely Available from IEEE
  • On the robustness of multivariable linear feedback systems

    Page(s): 401 - 404
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (376 KB)  

    One of the useful indicators of the robustness of a multivariable linear feedback system is the largest singular value of the nominal closed-loop transfer matrix. It is shown that while comparing different, not necessarily diagonal, closed-loop transfer matrices which have the same diagonal elements, the diagonal closed-loop transfer matrix has the greatest robustness. For plants with not "too" large parameter uncertainty, this result also guarantees the maximization of disturbance rejection, and the minimization of the control signal "power" at the plant's input. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Control constraints, abnormality, and improved performance by periodic control

    Page(s): 367 - 376
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (968 KB)  

    Second-order conditions for steady-state optimality and nonoptimality in a periodic control problem are presented. The main result is a generalization of the π test, a second-order sufficient condition for improved performance by periodic control. Earlier results are generalized in two distinct ways: 1) the control constraint set is only assumed to be convex (and, hence, possibly nonopen) thus allowing the optimal steady-slate control to be an element of the control constraint set boundary; and 2) auxiliary normality conditions are eliminated. Proofs of the results are based upon second-order necessary, conditions for nonlinear programming and optimal control obtained recently in [43] and [44]. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • On the informational properties of the Nash solution of LQG dynamic games

    Page(s): 377 - 385
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (856 KB)  

    TheM-person,N-stage discrete-time LQG Nash game is considered. The players use strategies that are linear functions of the current estimate of the state, generated by a Kalman filter. We study the impact of improvements of the information on the costs of the players. For certain classes of such problems, we show that better information is beneficial to all the players if the number of stages, or the number of players, is larger than some bounds, and which bounds are given explicitly in terms of the coefficient matrices. Related properties of the two-person zero-sum game are also investigated. It is shown that under certain conditions, better information is beneficial to the player who has better maneuverability while the saddle-point cost is independent of the information if both players have the same maneuverability. Conditions guaranteeing the uniform boundedness of the solutions of the coupled Riccati equations which arise in such games are also given. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Application of balanced realizations to power system equivalents

    Page(s): 414 - 416
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (344 KB)  

    An algorithm is presented to accurately estimate the feasible order reduction of dynamic models used in power system analysis. Order estimates obtained by balancing a linear model of the power system are used to determine the proper aggregation level of power system models derived from modal-coherency analysis. Test results for the 39 bus New England system are presented. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Adaptive control with the stochastic approximation algorithm: Geometry and convergence

    Page(s): 330 - 338
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (832 KB)  

    New geometric properties possessed by the sequence of parameter estimates are exhibited, which yield valuable insight into the behavior of the stochastic approximation based algorithm as it is used in minimum variance adaptive control. In particular, these geometric properties, together with certain probabilistic arguments, prove that if the system does not have a reduced-order minimum variance controller, then the parameter estimates converge to a random multiple of the true parameter. An explicit expression for the limiting parameter estimate is also available. With strictly positive probability, the limiting parameter estimate is not the true parameter, and in some cases differs from the true parameter with probability one. If the system possesses reduced-order minimum variance controllers, then convergence to a minimum variance controller in a Cesaro sense is shown. The geometry of the limit set is described. Sufficient conditions are also given for some of these results to hold for parameter estimation schemes other than stochastic approximation. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Global stability of adaptive pole placement algorithms

    Page(s): 348 - 356
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (800 KB)  

    This paper presents direct and indirect adaptive control schemes for assigning the closed-loop poles of a single-input, single-output system in both the continuous- and discrete-time cases. The resulting closed-loop system is shown to be globally stable when driven by an external reference signal consisting of a sum of sinusoids. In particular, persistent excitation of the potentially unbounded closed-loop input-output data, and hence convergence of a sequential least-squares identification algorithm is proved. The results are applicable to standard sequential least squares, and least squares with covariance reset. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Error models for stable hybrid adaptive systems

    Page(s): 339 - 347
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (888 KB)  

    This paper presents several stable adaptive algorithms for the control of hybrid and discrete systems in which the control parameters are adjusted at rates slower than those at which the systems operate. Continuous algorithms of an integral type, recently suggested in the literature [5] are also shown to belong to this class. From a practical standpoint, the infrequent adjustment of the control parameters makes for more robust adaptive control while from a theoretical point of view, the algorithms are attractive since they provide a unified framework for the design of continuous, hybrid, and discrete adaptive systems. Simulation results are included to indicate the type of responses that can be expected using the different algorithms. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • A simplified derivation of the Zeheb-Walach 2-D stability test with applications to time-delay systems

    Page(s): 411 - 414
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (424 KB)  

    Zeheb and Walach gave a stability test forN-Dsystems. For 2-D systems, a simpler derivation is presented here using the results of DeCarlo et al. It is then shown how the method may also be used to test for stability (independent of delay) of retarded time-delay systems. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Reachability and controllability of discrete-time linear periodic systems

    Page(s): 399 - 401
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (320 KB)  

    In this paper, we consider discrete-time linear systems with periodic coefficients. Two necessary and sufficient conditions for complete controllability and reachability are given. The conditions are stated in terms of the reachability Gramian and hold for both reversible and nonreversible systems. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • On the determination of a diagonal solution of the Lyapunov equation

    Page(s): 404 - 406
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (312 KB)  

    In this note, for a given matrixA, the solution of the Lyapanov equationA'P+ PA + Q = 0, consideringPdiagonal or bothPandQdiagonal matrices, is investigated. For this purpose a simple algorithm based on nonlinear programming is presented. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Estimation of variable coefficients in parabolic distributed systems

    Page(s): 386 - 398
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1416 KB)  

    We present techniques based on cubic spline approximations for estimating coefficients (e.g., diffusion, convector velocity, etc.) depending on time and the spatial variable in parabolic distributed systems such as those that arise in transport models. Convergence results and a summary of numerical performance of the resulting algorithms are given. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • A new general Routh-like algorithm to determine the number of RHP roots of a real or complex polynomial

    Page(s): 406 - 409
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (448 KB)  

    A new Routh-like algorithm for determining the number of right-half plane (RHP) roots of a polynomial with real or complex coefficients is given. It includes the Routh algorithm for real polynomials as a special case. Moreover, the algorithm also applies directly to the singular case wherein the leading coefficient of a row, but not the entire row, vanishes, needing far fewer computations than the heuristicepsilon- method about which there was a vigorous discussion in these TRANSACTIONS a few years ago, and further not requiring investigation of an auxiliary polynomial. The algorithm is illustrated by a few examples. The proof of the algorithm is based on the Principle of the Argument, and thus also constitutes a simple proof of the Routh algorithm in the regular case. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • A unified method for evaluating real-time computer controllers and its application

    Page(s): 357 - 366
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1176 KB)  

    A computer-controlled system is a synergistic coupling of the controlled process and the controller computer. We have defined new performance measures for real-time controller computers based on this coupling. We present a systematic study of a typical critical controlled process in the context of new performance measures that express the performance of both controlled processes and controller computers (taken as a unit) on the basis of a single variable: controller response time. Controller response time is a function of current system state, system failure rate, electrical and/or magnetic interference, etc., and is therefore a random variable. Control overhead is expressed as monotonically nondecreasing function of the response time and the system suffers catastrophic failure, or dynamic failure, if the response time for a control task exceeds the corresponding system hard deadline, if any. The controlled-process chosen for study is an aircraft in the final stages of descent, just prior to landing. Control constraints are particularly severe during this period, and great care must be taken in the design of controllers that handle this process. First, the performance measures for the controller are presented. Second, control algorithms for solving the landing problem are discussed, and finally the impact of our performance measures on the problem is analyzed, showing that the performance measures and the associated estimation method have potential use for designing and/or evaluating real-time controllers and controlled process. In common with all other control techniques, the computational complexity involved in obtaining these measures is susceptible to the curse of dimensionality. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Stabilization of two-dimensional systems

    Page(s): 409 - 411
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (320 KB)  

    Several new results on stabilization of discrete two-dimensional Systems are presented. If the horizontal (or vertical) part of the system in the Roesser model is controllable, then the stabilizability question is the same as that for a related discrete delay system. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Adaptive control of left ventricular bypass assist devices

    Page(s): 322 - 329
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (736 KB)  

    This paper presents a computer-based adaptive control system for left ventricular bypass assist devices consisting of air driven diaphragm pumps. The system provides for 1) synchronization of pumping with ECG signals and 2) control of atrial pressure at desired levels. The system design includes an adaptive control algorithm which is a self-tuning PID-controller based on pole placement. The performance of the system has been demonstrated by in vitro experiments_ on a mock circulatory system. When there is an increase in atrial pressure, the system responds with an increase in stroke volume. Following major changes in the circulatory system, the control algorithm retunes itself and restores the system to the desired state. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.

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

Full Aims & Scope

Meet Our Editors

Editor-in-Chief
P. J. Antsaklis
Dept. Electrical Engineering
University of Notre Dame