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Automatic Control, IEEE Transactions on

Issue 11 • Date November 1986

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

    Page(s): 0
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    Freely Available from IEEE
  • Scanning the issue

    Page(s): 993
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    Freely Available from IEEE
  • Editorial: The papers are here?

    Page(s): 994
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  • Comments on "Robust jump linear quadratic control: A mode stabilizing solution"

    Page(s): 1079 - 1081
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    In the above paper an optimal control problem with discounting was proposed to achieve closed-loop mode stabilization for linear systems with jump parameters. The paper used the unstated hypothesis that the diagonal entries of the generator of the jump process are equal. This correspondence discusses the situation in the general case. View full abstract»

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  • Comments on "Exact control of linear systems with multiple control"

    Page(s): 1081 - 1083
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    This note is concerned with piecewise constant controls. In order to supplement the above-mentioned paper sufficient conditions for the existence of a piecewise constant control are provided. Moreover, although for ann-dimensional control system the switching times for the piecewise constant control cannot he chosen arbitrarily, it is shown that the switching times can be chosen as close as we wish to any preassigned collection ofntime points. The proof of the main result is constructive and it provides an algorithm for the design of a piecewise constant control. View full abstract»

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  • Author's reply

    Page(s): 1081
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    First Page of the Article
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  • Comments on "An iterative method for generalized complementarity problems"

    Page(s): 1083 - 1084
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    In an earlier paper, the author proposed an iterative method for generalized complementarity problems with Lipschitz continuous and strongly monotone functions. Here we show that a slightly modified method can be developed to solve a generalized complementarity problem with a Lipschitz continuous, pseudomonotone, and integrable function. View full abstract»

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  • Control system synthesis [Book Reviews]

    Page(s): 1085
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    Freely Available from IEEE
  • [Back cover]

    Page(s): 0
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    Freely Available from IEEE
  • A computational algorithm for pole assignment of linear multiinput systems

    Page(s): 1044 - 1047
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    An efficient computational algorithm for pole assignment of linear multiinput systems is proposed. A preliminary stage of the algorithm is a reduction of the system matrices into orthogonal canonical form. The gain matrix elements are then found by orthogonal transformation of the closed-loop system matrix into upper quasi-triangular form whose diagonal blocks correspond to the desired poles. The algorithm is numerically stable, the computed gain matrix being exact for a system with slightly perturbed matrices. It works equally well with real and complex, distinct, and multiple poles and is applicable to ill-conditioned and high-order problems. View full abstract»

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  • An asymptotically efficient ARMA estimator based on sample covariances

    Page(s): 1068 - 1071
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    An asymptotically efficient autoregressive moving-average (ARMA) spectral estimator is presented, based on the sample covariances of observed time series. The estimate of the autoregressive (AR) part is shown to be identical to the optimal instrumental variable (IV) estimator in [7] although derived here using a different approach. The moving-average (MA) spectral parameter estimate is new. View full abstract»

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  • Improved finite word length characteristics in digital control using delta operators

    Page(s): 1015 - 1021
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    This paper examines some of the consequences of finite word lengths in digital control. It is shown that, in many cases of practical importance, the usual shift operator formulation is inferior to an alternative formulation which we designate the delta operator approach. This latter approach is shown to give better coefficient representation and less roundoff noise in many cases. We thus argue that the shift operator and its associatedZ-transform can be replaced by delta operators and their associated transform which we designate a Δ-transform. An added advantage of this approach is that discrete designs and transforms converge to their continuous-time counterparts as the sampling rate is increased. View full abstract»

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  • A robust direct adaptive controller

    Page(s): 1033 - 1043
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    This paper proposes a new direct adaptive control algorithm which is robust with respect to additive and multiplicative plant unmodeled dynamics. The algorithm is designed based on the reduced-order plant, which is assumed to be minimum phase and of known order and relative degree, but is analyzed with respect to the overall plant which, due to the unmodeled dynamics, may be nonminimum phase and of unknown order and relative degree. It is shown that if the unmodeled dynamics are sufficiently small in the low-frequency range, then the algorithm guarantees boundedness of all signals in the adaptive loop and "small" residual tracking errors for any bounded initial conditions. In the absence of unmodeled dynamics, the residual tracking error is shown to be zero. View full abstract»

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  • An adaptation algorithm for parallel model reference adaptive bilinear systems

    Page(s): 1071 - 1073
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    An adaptation algorithm is presented for parallel model reference adaptive bilinear systems. The output error converges asymptotically to zero and the parameter estimates are bounded for stable reference models. The convergence criterion depends only upon the input sequence and a priori estimates of the maximum parameter values. A passivity condition, which is generally difficult to verify, is not required. View full abstract»

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  • Application of modem synthesis to aircraft control: Three case studies

    Page(s): 995 - 1014
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    The role of feedback control in the solution of aircraft stability and control problems is discussed. It is argued that this role is becoming more and more important and is a key to meeting performance objectives for new aircraft. As a consequence, the control engineer must develop control laws for applications with many, sometimes conflicting, control objectives and stringent safely requirements. In the past, predominantly classical synthesis techniques have been used in industry to develop control laws for aircraft. However, the so-called modern synthesis techniques that are claimed to improve quality and reduce development cost are having increased practical use in industry. Modern synthesis techniques thai offer significant promise of practical applications are discussed briefly, and three case studies of their application to aircraft control problems are presented. The first example involves the redesign of an autopilot control law to improve stability and reduce sensitivity to plant parameter variations. A much improved control law was developed, flight tested, and implemented in the autopilot of the Boeing 767 commercial transport airplane. The second and third examples address the development of control laws for aircraft that rely extensively on feedback control to furnish satisfactory stability and control characteristics. These two applications are typical of the next generation of transport aircraft that will rely extensively on feedback control to improve fuel efficiency. The control laws gave the airplane flight characteristics that are Superior to those of current airplanes. The solutions presented could have been obtained using classical synthesis techniques. However, the modern approach reduced the number of design iterations required and appeared to produce belier control laws for a given level of practical experience of the control engineer. In our opinion, this approach to control law synthesis will play an increasingly important role in control design for present and future aircraft. Implemented in a user-friendly engineering workstation environment, these techniques offer improvement in quality and reduction in development cost, and for some applications, particularly to future high-performance aircraft, only the modern multiloop synthe- sis techniques will offer practical and cost-effective solutions. View full abstract»

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  • Stabilizing uncertain systems: Recovering full state feedback performance via an observer

    Page(s): 1050 - 1053
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    This note is concerned with the stabilization of uncertain systems via output feedback. The principal result demonstrates that if an uncertain system can be stabilized via linear static state feedback, then one can stabilize uncertain systems via observer-based feedback which are "arbitrarily close" to the original system. Most importantly, these results are achieved under relatively weak assumptions. View full abstract»

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  • Reduced-order performance of adaptive control systems

    Page(s): 1076 - 1079
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    Performance and stability behavior of discrete adaptive systems in the presence of fast parasitics are examined. When the parasitics are locally bounded, it is shown that sufficiently general input sequences yield a bounded response within a closed region. In the general case, it is established that a region of attraction exists from which all sequences converge to a target set which contains the equilibrium for exact adaptive tracking. View full abstract»

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  • Dynamic path planning for a mobile automaton with limited information on the environment

    Page(s): 1058 - 1063
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    The problem of path planning is studied for the case of a mobile robot moving in an environment filled with obstacles whose shape and positions are not known. Under the accepted model, the automaton knows its own and the target coordinates, and has a "sensory" feedback which provides it with local information on its immediate surroundings. Ibis information is shown to be sufficient to guarantee reaching a global objective (the target), while generating reasonable (if not optimal) paths. A lower bound on the length of paths generated by any algorithm operating with uncertainty is formulated, and two nonheuristic path planning algorithms are described. In the algorithms, motion planning is done continuously (dynamically), based on the automaton's current position and on its feedback. The effect of additional sources of information (e.g., from a vision sensor) on the outlined approach is discussed. View full abstract»

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  • Zeros of discrete-time linear periodic systems

    Page(s): 1057 - 1058
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    In this note the concept of zero for linear discrete-time SISO periodic systems is discussed. The definition is based on a time-invariant MIMO equivalent representation. An input-output characterization of the zeros is provided which extends a well-known property for time-invariant systems. View full abstract»

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  • The parallel implementation of a cascade adaptive identification algorithm

    Page(s): 1074 - 1076
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    This note presents a new method of parameter estimation, called cascading, for use in adaptive control. The algorithm is shown to be superior to a simple recursive least-squares estimator especially for a system characterized by noisy measurements. The algorithm can be implemented easily on a parallel processor such as ORAC [1], [2] or any sequential processor. When the algorithm is implemented on a parallel processor such as ORAC the real time used to compute the parameter estimates is of the same order as a recursive least-squares estimator. View full abstract»

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  • A sufficient condition of output feedback stabilization of uncertain systems

    Page(s): 1055 - 1057
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    A sufficient condition is derived for the existence of an output constant gain feedback controller which stabilizes a single-input single-output dynamical system with a linear nominal part and matched uncertainties. The sufficient condition is significantly less restrictive than a recently derived one [1]. If such a controller exists, it may readily be computed. View full abstract»

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  • Stability and control of a class of compartmental systems with application to cell proliferation and cancer therapy

    Page(s): 1022 - 1032
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    This paper concerns a systematic application of a variety of concepts and tools of control theory to the study of the stability and control of a class of compartmental systems arising in several application areas where population kinetics are of significant importance. To provide a focus to the development, the specific area of cell proliferation kinetics is selected for detailed study. A multicompartmental model which portrays the progression of a population of cells through the different phases of the ceil cycle is developed and a model reference adaptive algorithm for estimating model parameters is presented. An exponential stability framework is developed for quantifying the control effects of an administered drug protocol and is used to design efficient treatment strategies for cancer chemotherapy by application of optimization concepts. Since the toxic effects of anticancer drugs on the normal cell populations of the body are the bottlenecks in successful chemotherapy, determination of dosing strategies that minimize toxicity while maximizing the therapeutic effects are of great importance. A mathematical formulation of this problem leads to the optimization of bilinear systems under exponential stability constraints for which a solution procedure is presented. View full abstract»

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  • An improvement on Routh approximation technique

    Page(s): 1047 - 1050
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    A modification of the Routh approximant is introduced which results in a considerable improvement over the conventional Routh approximation technique. Since some amount of arbitrariness is available in the time moment expressions of the conventional Routh approximant, it can be utilized to minimize the step response error while preserving the stability and moment matching property of the conventional Routh approximant. A numerical example illustrates the procedure. View full abstract»

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  • Nonlinear filtering for systems with random structure

    Page(s): 1064 - 1068
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    This note studies the nonlinear filtering problem for a linear system with random structure governed by a finite state Markov process. A characterization of the optimal mean-square filter is derived and some suboptimal filter approximations are presented. View full abstract»

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  • On dual zero spaces and inverse systems

    Page(s): 1053 - 1055
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    Control system response possibilities for a finite-dimensional, linear, time-invariant plant are governed by an interaction between the possible plant transfer function inverses, when they exist, and the closed-loop response maps themselves. Possible minimal state spaces for such inverses are comprised algebraically of a space of plant zeros and a variable space of poles, with the latter having a characterization dependent upon whether the inverse is left or right. In this note, we unify the study of state spaces for left and right inverse systems by defining a dual zero space. The dualization is natural and extends to both the state space and the variable pole space. 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

Full Aims & Scope

Meet Our Editors

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