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Automatic Control, IEEE Transactions on

Issue 10 • Date Oct. 1993

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Displaying Results 1 - 25 of 29
  • Comments, with reply, on "Robust stability of an interval plant with respect to a convex region in the complex plane" by J. Shaw and J. Jayasuriya

    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (123 KB)  

    The commenter points out that the results of J. Shaw and J. Jayasuriya (ibid., vol.38, no.2, pp.284-287, Feb.1993) were published by F.J. Kraus and W. Truol (Int. J. Contr., vol.52, no.4, pp.967-983, 1991) for robust stability of polynomial families with affline linear parameter dependence. The authors agree with the commenter and point out that their own results derive from a paper they submitted for publication in 1990, but which has not yet been printed, which contained arguments similar to those of the commenters.<> View full abstract»

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  • Comments on "Comments on "Stability analysis of a family of matrices" by J.H. Kim and Z. Bien

    Page(s): 1607 - 1608
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    A flaw is pointed out in the proof of a necessary and sufficient condition for robust stability of a polytope of matrices given by J.H. Kim and Z. Bien (ibid., vol.387, no.9, pp.1470-1472, Sep. 1992), in their comments on a paper by the present authors (ibid., vol.35, no.11, pp.1257-1259, Nov. 1190). Hence, the necessary condition as proposed may not be correct.<> View full abstract»

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  • Adaptive asymptotic tracking of repetitive signals-a frequency domain approach

    Page(s): 1572 - 1579
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    The problem of designing an adaptive tracking controller for repetitive signals is considered. It is assumed that the controlled plant is linear time-invariant (LTI) and that its steady-state behavior can be described by its frequency response. The proposed controller, being able to identify the gain and phase of a plant at selected frequencies, adjusts the input/output (I/O) map at frequencies contained in the reference signal so as to achieve zero steady-state errors. Hence, no structural knowledge of the plant is needed. However, the proposed controller does not alter the transient property of the plant, e.g., locations of poles. The transient property can be improved by adding feedback control action. A combination of the adaptive controller and a feedback LTI controller is studied View full abstract»

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  • Nonlinear speed observer for the PM stepper motor

    Page(s): 1584 - 1588
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    A nonlinear observer for the permanent magnet (PM) stepper motor is considered. Specifically, the method of A.J. Krener and W. Respondek (1985) is used to construct a nontrivial full-order speed observer that has linear error dynamics. The procedure is validated by experimental results. Reduced-order observers are constructed by inspection View full abstract»

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  • Geometric structures of stable state feedback systems

    Page(s): 1579 - 1583
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    A parameterization of the set of all stabilizing state-feedback gains is given, and the geometric structure of the set of stable state-feedback systems in the set of stable matrices is exploited. Some spectral properties related to this structure are derived. The results give not only fundamental guidelines for designing state-feedback gains using this parameterization but also a new approach to analyzing structures of linear stable systems View full abstract»

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  • Dynamic feedback linearization of the induction motor

    Page(s): 1588 - 1594
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    Dynamic state feedback is used to achieve feedback linearization of the induction motor. It is shown that the sixth-order nonlinear dynamical model of the induction motor consisting of rotor speed, two stator currents, two rotor fluxes and an integrator in the feedback controller can be made equivalent to two third-order decoupled linear systems by nonlinear state feedback through the stator input voltages. It is further shown that a nonsingular dynamic feedback linearizing transformation exists as long as the (electromagnetic) torque put out by the motor is nonzero View full abstract»

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  • Parameter estimation of systems subject to random state changes

    Page(s): 1532 - 1536
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    Parameter estimation for a linear regression model subject to abrupt random state changes is formulated as an optimization problem. An identification algorithm comprising state regime classification and parameter identification is developed. The samples of the system are first partitioned into different groups called clusters, corresponding to different states. The standard linear-least-square method is then used to identify the parameters. The cluster control is a matrix of predetermined rank and can be computed by the singular-value-decomposition algorithm. Two iterative algorithms that ensure the decrease of the objective function are then proposed. An example is given to show the effectiveness of the method View full abstract»

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  • Robust stabilization of sampled-data systems to structured LTI perturbations

    Page(s): 1497 - 1508
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    Sampled-data systems with stable, structured, LTI (linear time-invariant) perturbations in the half-plane algebra applied to the continuous-time plant are considered. Necessary and sufficient conditions are derived for robust L2 stability of such systems. An example is provided to illustrate the results, which shows that the small gain theorem can be an extremely conservative robustness test in this sampled-data context View full abstract»

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  • On continuity/discontinuity in robustness indicators

    Page(s): 1551 - 1553
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    Continuity/discontinuity of robustness indicators is reviewed. For the case of real or mixed uncertainty, a regularization of a conservative bound to the robustness margin is proposed, and its properties are discussed. In the case of polynomial families with affine dependency on the uncertainty, a regularization of the robustness margin results View full abstract»

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  • On variable structure output feedback controllers for uncertain dynamic systems

    Page(s): 1509 - 1512
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    A class of variable structure output feedback controllers for uncertain dynamic systems with bounded uncertainties is proposed. No statistical information about the uncertain elements is assumed. A variable structure systems approach and a geometric approach to the analysis and synthesis of system zeros are employed in the synthesis of the proposed controllers View full abstract»

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  • The stability of constrained receding horizon control

    Page(s): 1512 - 1516
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    An infinite horizon controller that allows incorporation of input and state constraints in a receding horizon feedback strategy is developed. For both stable and unstable linear plants, feasibility of the contraints guarantees nominal closed-loop stability for all choices of the tuning parameters in the control law. The constraints' feasibility can be checked efficiently with a linear program. It is always possible to remove state constraints in the early portion of the infinite horizon to make them feasible. The controller's implementation requires only the solution of finite-dimensional quadratic programs View full abstract»

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  • Stick slip and control in low-speed motion

    Page(s): 1483 - 1496
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1068 KB)  

    Dimensional and perturbation analysis are applied to the problem of stick slip encountered during the motion of machines. The friction model studied is motivated by current tribological results and is appropriate for lubricated metal contacts. The friction model incorporates Coulomb, viscous, and Stribeck friction with frictional memory and rising static friction. Through dimensional analysis an exact model of the nonlinear system can be formed using five parameters rather than ten, greatly facilitating study and explicitly revealing the interaction of parameters. By converting the system of differential equations into a set of integrations, the perturbation technique makes approximate analysis possible where only numerical techniques had been available before. The analysis predicts the onset of stick slip as a function of plant and controller parameters; these results are compared with experimental data View full abstract»

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  • Regulator problem for linear continuous-time systems with nonsymmetrical constrained control

    Page(s): 1556 - 1560
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (408 KB)  

    The regulator problem is studied for linear continuous-time systems with nonsymmetrical constrained control. Necessary and sufficient conditions allowing the largest nonsymmetrical polyhedral positively invariant domain w.r.t. the system in the closed loop to be obtained are given. The case of symmetrical constrained control is obtained as a particular case View full abstract»

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  • Reference model selection and adaptive control for induction motor drives

    Page(s): 1594 - 1600
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (408 KB)  

    An adaptive model-following speed controller for induction motor drives is proposed and implemented. This adaptive controller is easy to implement since, for the controlled plant, only the output signal is fed back. In order to choose a reference model with the desired drive dynamic behavior, a two-degree-of-freedom (2-DOF) controller is designed, using a systematic procedure based on the prescribed drive specifications. The reference model of the adaptive system is chosen as the transfer function of the controlled drive system by the 2-DOF controller in the nominal case. An adaptation signal is augmented to let the prescribed specifications be maintained under a wide range of operating conditions View full abstract»

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  • Uniform approximation and the circle criterion

    Page(s): 1450 - 1458
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    The input-output maps G of causal time-invariant systems are considered, and a complete characterization of those maps that can be uniformly approximated by the maps of certain simple structures is given. The criterion is that G must satisfy certain continuity and approximately-finite-memory conditions. It is proved that the conditions are satisfied by the input-output maps of control systems of a familiar type containing a sector nonlinearity for which the circle condition for stability is met. In particular, this shows that such feedback systems, with inputs drawn from a certain large set of bounded functions, possess arbitrarily good finite Volterra-series (or radial-basis-function) approximations View full abstract»

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  • A new characterization for multivariate Gaussian reciprocal processes

    Page(s): 1601 - 1602
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    Established a new necessary and sufficient condition for a multivariate Gaussian random process to be reciprocal. This result is then used to prove that the state vector of a two-point boundary value system is reciprocal. The authors do not impose any nonsingularity conditions on the covariance function of the state vector View full abstract»

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  • A new tabular form for determining root distribution of a complex polynomial with respect to the imaginary axis

    Page(s): 1536 - 1541
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    The original Routh table dealing with real polynomials is further investigated for complex polynomials. A tabular form for determining root distribution of a complex polynomial with respect to the imaginary axis is developed, and modified procedures for directly treating singularities in the array are proposed. Also, procedures are developed for determining the respective orders of simple and/or repeated roots lying on the imaginary axis. Conditional stability and instability can be distinguished from each other by the criteria developed here View full abstract»

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  • Optimal service control of a station connected with two parallel substations

    Page(s): 1567 - 1572
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    The optimization problem is studied for a queueing network consisting of one station and two parallel subordinate stations. After service completion at the first station, the job is divided into two subjobs and each of them enters one of the subordinate stations. The service rate at the first station is controlled in order to minimize the expected total discounted cost or the long-run average expected cost View full abstract»

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  • Minimization of the maximum peak-to-peak gain: the general multiblock problem

    Page(s): 1459 - 1482
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    A comprehensive study of the general l1-optimal multiblock problem and a new linear programming algorithm for computing suboptimal controllers are presented. By formulating the interpolation conditions in a concise and natural way, the general theory is developed in simpler terms and with a minimum number of assumptions. In addition, further insight is gained into the structure of the optimal solution, and different classes of multiblock problems are distinguished. This leads to a conceptually attractive, iterative method for finding approximate solutions View full abstract»

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  • On nonachievable frequency domain specifications in SISO feedback control systems

    Page(s): 1530 - 1532
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    It is shown how bounds on the sensitivity function and the complementary sensitivity function which are not simultaneously achievable by any stabilizing controller can be computed by means of the H approach. This allows evaluation of a given synthesis in terms of its distance from nonachievable specifications and provides information about design tradeoffs View full abstract»

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  • On the computation of the Gram matrix in time domain and its application

    Page(s): 1516 - 1520
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    The Gram matrix of the system involves evaluation of the scalar product of repeated integrals and has formerly been computed in frequency domain. A time domain method for evaluation of the Gram matrix is presented. It is based on new properties of the Gram matrix, derived here. A model reduction algorithm based on these properties is presented. The method is illustrated by a numerical example View full abstract»

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  • Exact and inexact LQG model matching problems

    Page(s): 1545 - 1550
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (460 KB)  

    The design of discrete-time LQG (linear-quadratic-Gaussian) controllers that yield closed-loop systems that match a provided model is addressed. The solution is in the form of a two-degree-of-freedom controller having feedback and feedforward paths that independently provide the optimal actions for disturbance rejection and model matching. Exact and approximate model matching cases are discussed in a unified fashion View full abstract»

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  • A new algorithm for constructing approximate transformations for nonlinear systems

    Page(s): 1553 - 1556
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (360 KB)  

    An algorithm is provided for constructing an approximating transformation for a feedback linearizable system, and for a system that is not feedback linearizable. Instead of approximating the given nonlinear system, the authors approximate the transformation in a proper sense. They assume that the lead variables of a transformation have a certain form with unknown parameters, substitute these variables into the required equations, and determine the unknown parameters through linear algebraic equations. There is a tremendous savings in terms of number of equations and unknowns, and it is sometimes possible to find exact (or best possible) transformations in a surprisingly small number of steps View full abstract»

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  • Transient behavior analysis of vibrationally controlled nonlinear parabolic systems with Neumann boundary conditions

    Page(s): 1603 - 1607
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    The transient behavior of vibrationally controlled distributed parameter systems governed by parabolic partial differential equations (PDEs) with Neumann boundary conditions is analyzed. The analysis uses a certain mapping and a time-invariant PDE whose trajectories under this mapping yield the approximate moving averages along the trajectories of the vibrationally controlled system. This approach considerably enhances the understanding of the behavior of vibrationally controlled distributed-parameter systems and facilitates a selection of the parameters of stabilizing vibrations that ensure transient behavior with more desirable properties View full abstract»

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  • Optimal periodic control implemented as a generalized sampled-data hold output feedback control

    Page(s): 1560 - 1563
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    A method for converting analog linear quadratic regulation control to a generalized sampled-data hold output-feedback control for a linear periodic system or a linear time-variant system is presented. It is shown that by using such a conversion, one can implement the optimal periodic control scheme in the presence of incomplete and delayed state measurements 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