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Automatic Control, IEEE Transactions on

Issue 5 • Date May 1994

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Displaying Results 1 - 25 of 47
  • Comments on "Block multirate input-output model for sampled-data control systems"

    Publication Year: 1994 , Page(s): 1145 - 1147
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (295 KB)  

    In the above paper, Albertos (1990) presents a modeling technique to model linear, time-invariant systems with synchronous sampling. The model is derived from both the discrete transfer function and state-space representation of a given system and yields two similar expressions. Albertos equates the two in Lemma 2.1; there is, however, an inconsistency in Lemma 2.1, and this is discussed further.<> View full abstract»

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  • Comments on "Two necessary conditions for a complex polynomial to be strictly Hurwitz and their applications in robust stability analysis" [with reply]

    Publication Year: 1994 , Page(s): 1147 - 1148
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    In the original paper, Y. Q. Shi, K. K. Yen, and C. M. Chen (IEEE Trans. Automat. Contr., vol. 38, no. 1, p. 125-8, 1993) present two simple necessary conditions for a polynomial with complex coefficients to be strictly Hurwitz. They claim that this is an extension and refinement of a result of Xie and Xie (1988). Polyak and Tsypkin comment that the second condition is well known and that the first one is a direct corollary of Newton's test for a polynomial to have only real roots. The original authors express their appreciation for certain points but state that their intention was to point out two conditions for use in stability analysis.<> View full abstract»

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  • Comments on "Stabilization via static output feedback

    Publication Year: 1994
    Cited by:  Papers (4)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (79 KB)  

    In the above paper (Trofino-Neto and Kucera, 1993) the proof given for theorem (3.1) is inconsistent; in this note a modified proof is suggested.<> View full abstract»

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  • Modeling and control of a floating platform

    Publication Year: 1994 , Page(s): 1075 - 1078
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (340 KB)  

    A platform with a rotating crane resting on three adjustable floats in a tub has been built on laboratory scale. Controller design is studied to prevent the platform from leaning due to crane movements. The system dynamics can be described primarily by a simple sixth order linear model. Model errors are then due mainly to unmodeled effects of waves that are essentially linear transfers. It is precisely under these conditions that H design should perform well. Actual design and tests show that H controllers do not substantially outperform LQG designs combined with feedforward controllers, but the combination of both feedforward and feedback controllers can easily be obtained by H design techniques View full abstract»

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  • Vibrational control of nonlinear time lag systems with bounded delay: averaging theory, stabilizability, and transient behavior

    Publication Year: 1994 , Page(s): 898 - 912
    Cited by:  Papers (24)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1168 KB)  

    This paper develops the theory of vibrational control of nonlinear time lag systems with arbitrarily large but bounded delay. Averaging theory for fast oscillating, differential delay equations is presented and then applied to vibrational control. Conditions are given which ensure the existence of parametric vibrations that stabilize nonlinear time lag systems. Transient behavior is also discussed. Illustrative examples are given which show 1) the feasibility of the theory to important applications and 2) the differences in the theory presented and the existing known theory for vibrational control of ordinary differential equations View full abstract»

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  • H control of discrete-time uncertain systems

    Publication Year: 1994 , Page(s): 1072 - 1075
    Cited by:  Papers (12)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (368 KB)  

    This paper considers H control problems involving discrete-time uncertain linear systems. The uncertainty is supposed to belong to convex-bounded domains, and no additional assumptions are made (as, for instance, matching conditions). Two H guaranteed cost control problems are solved. The first one concerns the determination of a state feedback gain (if one exists) in such way the H norm of a certain transfer function remains bounded by a prespecified H level for all possible models. The second one includes this bound as an additional variable to be minimized to achieve the smallest feasible limiting bound. The results follow from the simple geometry of those problems which are shown to be convex in the particular parametric space under consideration. An example illustrates the theory View full abstract»

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  • Stability, queue length, and delay of deterministic and stochastic queueing networks

    Publication Year: 1994 , Page(s): 913 - 931
    Cited by:  Papers (259)  |  Patents (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1600 KB)  

    We present two types of stability problems: 1) conditions for queueing networks that render bounded queue lengths and bounded delay for customers, and 2) conditions for queueing networks in which the queue length distribution of a queue has an exponential tail with rate θ. To answer these two types of stability problems, we introduce two new notions of traffic characterization: minimum envelope rate (MER) and MER with respect to θ. We also develop a set of rules for network operations such as superposition, input-output relation of a single queue, and routing. Specifically, we show that: 1) the MER of a superposition process is less than or equal to the sum of the MER of each process, 2) a queue is stable in the sense of bounded queue length if the MER of the input traffic is smaller than the capacity, 3) the MER of a departure process from a stable queue is less than or equal to that of the input process, and 4) the MER of a routed process from a departure process is less than or equal to the MER of the departure process multiplied by the MER of the routing process. Similar results hold for MER with respect to θ under a further assumption of independence. For single class networks with nonfeedforward routing, we provide a new method to show that similar stability results hold for such networks under the first come, first served policy. Moreover, when restricting to the family of two-state Markov modulated arrival processes, the notion of MER with respect to θ is shown to be equivalent to the recently developed notion of effective bandwidth in communication networks View full abstract»

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  • Consistency of a pair of generalized Sylvester equations

    Publication Year: 1994 , Page(s): 1014 - 1016
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (244 KB)  

    A necessary and sufficient condition is given for the existence of a simultaneous solution of a pair of generalized Sylvester equations. An auxiliary result deals with constant solutions of Sylvester equations with polynomial matrices View full abstract»

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  • A normality theorem for decentralized control of discrete-event systems

    Publication Year: 1994 , Page(s): 1089 - 1093
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (440 KB)  

    Derives a necessary condition, formulated as a normality theorem, for decentralized control of discrete event systems. The result is of practical interest since it can be tested to determine whether decentralization is possible. This result is applied to the classical coordination problem of the “dining philosophers” for illustrative purposes View full abstract»

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  • A family of norms for system identification problems

    Publication Year: 1994 , Page(s): 1027 - 1031
    Cited by:  Papers (6)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (452 KB)  

    Introduces a family of norms that may prove useful in system identification problems. The important property of the new norm is that for a given sequence, its value in the limit will converge to the supremum over all frequencies of the spectrum of the sequence. Using this property, a procedure is outlined to approximately minimize the weighted L norm of the frequency response estimation error. In addition, a test for checking the whiteness of a given sequence is proposed View full abstract»

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  • On the elastic mode estimation aspect of a class of multibody flexible systems

    Publication Year: 1994 , Page(s): 1016 - 1020
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (416 KB)  

    An investigation pertaining to estimation of the elastic generalized coordinates for a given class of flexible structures is presented. To begin with, a model for studying nonlinear dynamics of the structure is described. The governing equations of motion are obtained using the Lagrangian procedure with modal discretization. Next, deformations caused by rapid slewing maneuvers are estimated using the least square estimation approach. As an alternative, a procedure based on the operator spline technique is proposed and its potential assessed. It is motivated by the need for achieving an on-line estimation procedure permitting real time control. Finally, a comparative performance study of the two procedures is undertaken using a simplified model of the flexible system View full abstract»

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  • Stationarity and reciprocity in stochastic multipoint boundary value systems

    Publication Year: 1994 , Page(s): 1114 - 1116
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (252 KB)  

    Investigates certain statistical properties of the state vector in a stochastic multipoint boundary value system. The authors give necessary and sufficient conditions for the state vector to be stationary, and prove that the state vector is locally reciprocal View full abstract»

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  • Computational complexity of μ calculation

    Publication Year: 1994 , Page(s): 1000 - 1002
    Cited by:  Papers (75)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (280 KB)  

    The structured singular value μ measures the robustness of uncertain systems. Numerous researchers over the last decade have worked on developing efficient methods for computing μ. This paper considers the complexity of calculating μ with general mixed real/complex uncertainty in the framework of combinatorial complexity theory. In particular, it is proved that the μ recognition problem with either pure real or mixed real/complex uncertainty is NP-hard. This strongly suggests that it is futile to pursue exact methods for calculating μ of general systems with pure real or mixed uncertainty for other than small problems View full abstract»

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  • Distributed algorithms with random processor failures

    Publication Year: 1994 , Page(s): 1032 - 1036
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (408 KB)  

    Examines a distributed algorithm where the processors may fail in a random fashion. This results in a model with random communication delays. Convergence conditions are derived. Extensions of the analysis and results to cases where the random processor failures are perceived and corrected within random time intervals are possible. For the sake of simplicity, the analysis is presented for a two processor model for solving a system of linear equations View full abstract»

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  • Robust stability of discrete-time systems under parametric perturbations

    Publication Year: 1994 , Page(s): 991 - 995
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (384 KB)  

    Stability robustness analysis of a system under parametric perturbations is concerned with characterizing a region in the parameter space in which the system remains stable. In this paper, two methods are presented to estimate the stability robustness region of a linear, time-invariant, discrete-time system under multiparameter additive perturbations. An inherent difficulty, which originates from the nonlinear appearance of the perturbation parameters in the inequalities defining the robustness region, is resolved by transforming the problem to stability of a higher order continuous-time system. This allows for application of the available results on stability robustness of continuous-time systems to discrete-time systems. The results are also applied to stability analysis of discrete-time interconnected systems, where the interconnections are treated as perturbations on decoupled stable subsystems View full abstract»

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  • Constrained optimization in Hilbert space and a generalized dual quasi-Newton algorithm for state-constrained optimal control problems

    Publication Year: 1994 , Page(s): 982 - 986
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (392 KB)  

    Studies a modified Newton method for constrained optimization in Hilbert space, and generalizes the dual quasi-Newton algorithm to Hilbert space. A new algorithm for solving state-constrained optimal control problems is proposed by applying the generalized dual quasi-Newton method View full abstract»

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  • Optimization in a class of priority-discarding policies for finite queues

    Publication Year: 1994 , Page(s): 1020 - 1024
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (436 KB)  

    Considers an optimization problem for finite queues governed by priority-discarding control policies. The author develops an analytical model for systems that defer discarding decisions until service completion instants, but then may expel any waiting jobs. Using stochastic dynamic programming techniques, the author obtains closed-form optimization results for systems constrained to retain at most one job. Numerical performance examples are included View full abstract»

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  • Approximate solution of large sparse Lyapunov equations

    Publication Year: 1994 , Page(s): 1110 - 1114
    Cited by:  Papers (9)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (500 KB)  

    Describes a simple method for efficiently estimating the dominant eigenvalues and eigenvectors of the solution to a Lyapunov equation, without first solving the equation explicitly. The method is based on the power method and matrix-vector multiplications and is particularly suitable for problems where those multiplications can be done efficiently, such as where the coefficient matrices are large and sparse or low-rank. The same idea is directly applicable to balanced-truncation order reduction of linear systems View full abstract»

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  • Avoiding stick-slip through PD control

    Publication Year: 1994 , Page(s): 1094 - 1097
    Cited by:  Papers (35)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (368 KB)  

    Addresses the question of how to achieve steady motion at very low velocities using proportional-derivative (PD) control. Most prior work in control has used friction models which depend only on the current value of velocity. This type of analysis indicates that stick-slip can be avoided only through velocity feedback. The tribology literature, however, indicates that friction also depends on the history of motion. By including this dependence, a second regime of stable motion is revealed which is associated with position feedback gains above a critical value. Two experimentally-based dynamic friction models are compared using a linearized stability analysis. In accord with experiment, a state variable friction model exhibits asymptotically stable motion for any system stiffness (position feedback gain) exceeding a critical value. This property is not exhibited by a time-lag friction model View full abstract»

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  • Achievable closed-loop properties of systems under decentralized control: conditions involving the steady-state gain

    Publication Year: 1994 , Page(s): 932 - 943
    Cited by:  Papers (43)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1092 KB)  

    The question of the existence of decentralized controllers for open-loop stable multivariable systems which provide particular closed-loop properties is investigated. In particular, we study the existence of decentralized controllers which provide integral action (Type I closed-loop performance) and also demonstrate one or more of: unconditional stability, integrity with respect to actuator and sensor failure, and decentralized unconditional stability. Necessary, sufficient, and, in some cases, necessary and sufficient conditions on the open-loop steady-state gain are derived such that there exists a controller which provides these desired closed-loop characteristics. These results provide the basis for a systematic approach to control structure selection for decentralized controller design View full abstract»

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  • Dissipative controller designs for second-order dynamic systems

    Publication Year: 1994 , Page(s): 1056 - 1063
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (620 KB)  

    The passivity theorem may be used to design robust controllers for structures with positive transfer functions. This paper extends this result to more general configurations using dissipative system theory. A stability theorem for robust control of structures with displacement sensors is given and applied to several common classes of controllers View full abstract»

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  • A matrix pencil based numerical method for the computation of the GCD of polynomials

    Publication Year: 1994 , Page(s): 977 - 981
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (364 KB)  

    The paper presents a new numerical method for the computation of the greatest common divisor (GCD) of an m-set of polynomials of R[s], P m,d, of maximal degree d. It is based on a previously proposed theoretical procedure (Karcanias, 1989) that characterizes the GCD of Pm,d as the output decoupling zero polynomial of a linear system S(Aˆ,Cˆ) that may be associated with Pm,d . The computation of the GCD is thus reduced to finding the finite zeros of the pencil sW-AW, where W is the unobservable subspace of S(Aˆ,Cˆ). If k=dim W, the GCD is determined as any nonzero entry of the kth compound Ck(sW-AˆW). The method defines the exact degree of GCD, works satisfactorily with any number of polynomials and evaluates successfully approximate solutions View full abstract»

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  • Sampled-data controller design for uncertain systems

    Publication Year: 1994 , Page(s): 1036 - 1042
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (508 KB)  

    Presents a sampled-data controller design methodology for uncertain systems. A continuous system with bounded time-varying uncertainty is sampled at intervals of length T. The controller is designed using a Riccati equation approach by neglecting O(T2) uncertainty terms in the discretized system. Stability is verified for this choice of T with the U(T2) terms included. If there exists a stabilizing continuous controller, then there also exists a stabilizing sampled-data controller for a sufficiently small choice of T View full abstract»

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  • On the general solution of the state deadbeat control problem

    Publication Year: 1994 , Page(s): 1002 - 1006
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (380 KB)  

    In this note, the state deadbeat control problem is considered. It is shown that, after appropriate change of basis of input and state spaces, the general solution of the state deadbeat control problem can be expressed completely by the rows of the powers of system matrix. This result yields a very simple procedure for the calculation of a state feedback deadbeat control gain. It also provides the number of free parameters which could be used for further design purposes. The results are illustrated by an example at the end of the note View full abstract»

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  • On-line estimation of dynamic shock-error models based on the Kullback Leibler information measure

    Publication Year: 1994 , Page(s): 1129 - 1135
    Cited by:  Papers (8)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (536 KB)  

    Develops two sequential or “on-line” estimation schemes in the time domain for dynamic shock-error models which are special cases of errors-in-variables models. The author's approach utilizes a state-space representation of the model, Kalman filtering techniques, and on-line algorithms. The first on-line algorithm is based on the expectation-maximization algorithm and uses a recursive Gauss-Newton scheme to maximize the Kullback Leibler information measure. The second on-line algorithm the author proposes is a gradient-based scheme and uses stochastic approximations to maximize the log likelihood. In comparison to the off-line maximum likelihood estimation scheme used in Ghosh (1989), the author's on-line algorithms have significantly reduced computational costs and negligible memory requirements. Simulations illustrate the satisfactory performance of the algorithms in estimating errors-in-variables systems with parameters that vary slowly with time or undergo infrequent jump changes 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