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Automatic Control, IEEE Transactions on

Issue 4 • Date April 1997

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Displaying Results 1 - 22 of 22
  • Correction to "Absolute Stability Criteria for Multiple Slope-Restricted Monotonic Nonlinearities"

    Publication Year: 1997 , Page(s): 591
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (20 KB)  

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  • Dynamics and convergence rate of ordinal comparison of stochastic discrete-event systems

    Publication Year: 1997 , Page(s): 586 - 590
    Cited by:  Papers (14)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (228 KB)  

    This paper addresses ordinal comparison in the simulation of discrete-event systems. It examines dynamic behaviors of ordinal comparison in a fairly general framework. It proves that for regenerative systems, the probability of obtaining a desired solution using ordinal comparison approaches converges at exponential rate, while the variances of the performance measures converge at best at rate O(1/t 2), where t is the simulation time. Heuristic arguments are provided to explain that exponential convergence holds for general systems View full abstract»

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  • Certain nonlinear partially observable stochastic optimal control problems with explicit control laws equivalent to LEQG/LQG problems

    Publication Year: 1997 , Page(s): 482 - 497
    Cited by:  Papers (20)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1060 KB)  

    This paper is concerned with partially observed stochastic optimal control problems when nonlinearities enter the dynamics of the unobservable state and the observations as gradients of potential functions. Explicit representations for the information state are derived in terms of a finite number of sufficient statistics. Consequently, the partially observed problem is recast as one of complete information with a new state generated by a modified version of the Kalman filter. When the terminal cost is quadratic in the unobservable state and includes the integral of the nonlinearities, the optimal control laws are explicitly computed, similar to linear-exponential-quadratic-Gaussian (LEQG) and linear-quadratic-Gaussian (LQG) tracking problems. The results are applicable to filtering and control of Hamiltonian systems View full abstract»

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  • Supervisory control using failure semantics and partial specifications

    Publication Year: 1997 , Page(s): 498 - 510
    Cited by:  Papers (24)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (696 KB)  

    A framework is presented for the supervisory control of nondeterministic discrete-event systems based on failure semantics. It guarantees deadlock-free behavior under all circumstances, it allows for powerful specifications, it forms a sound basis for modular control, and it can handle nondeterminism without extra effort. A synthesis method to generate the least restrictive supervisor is presented. The control problem with partial specification is formulated, and it is shown that this control problem can be rewritten to a control problem with full specification. Special care has to be taken for traces with an unbounded internal extension (divergence). A condition, denoted bounded recurrence, is introduced to handle these traces. It is shown that the external behavior of the controlled system is not restricted by this condition View full abstract»

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  • New results on the separation of matrix eigenvalues and the clustering of matrix elements

    Publication Year: 1997 , Page(s): 564 - 567
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (160 KB)  

    The problem of separation of matrix eigenvalues is considered in this paper. Necessary and sufficient conditions are given for a matrix to have all eigenvalues contained in an open set defined on the complex plane by a separable polynomial γ(z1, z2). The problem of clustering of matrix elements is also considered. In this case, a set of matrices is identified, having all eigenvalues in a given subset of the complex plane. The presented results can be useful in both robust stability analysis and the design of control systems View full abstract»

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  • Sensitivity analysis of the feedback synthesis problem

    Publication Year: 1997 , Page(s): 568 - 573
    Cited by:  Papers (5)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (316 KB)  

    Sensitivity analysis of the feedback synthesis problem (FSP) for linear multivariable systems is presented. Both local linear and nonlocal nonlinear perturbation bounds are derived using the Schur form of the closed-loop state matrix. Condition numbers for the general FSP and the pole assignment problem in particular are given. Restrictions are imposed only on the degrees of the invariant polynomials of the closed-loop matrix but not on its spectrum View full abstract»

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  • Stability of discrete-time matrix polynomials

    Publication Year: 1997 , Page(s): 538 - 542
    Cited by:  Papers (4)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (184 KB)  

    This paper derives conditions for the stability of discrete-time systems that can be modeled by a vector difference equation, where the variables are m×1 vectors and the coefficients are m×m matrices. Stability of the system is related to the locations of the roots of the determinant of a real m×m matrix polynomial of nth order. In this case, sufficient conditions for the system to be stable are derived. The conditions are imposed on the ∞-norm of two matrices constructed from the coefficient matrices and do not require the computation of the determinant polynomial. The conditions are the extensions of one of the Jury sufficient conditions for a scalar polynomial. An example is used to illustrate the application of the sufficient conditions View full abstract»

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  • Convergence of the DRE solution to the ARE strong solution

    Publication Year: 1997 , Page(s): 573 - 578
    Cited by:  Papers (8)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (240 KB)  

    In this paper, we use the boundary solutions to a linear matrix inequality (LMI) associated with Kalman filtering to investigate the convergence of the solution of a differential Riccati equation (DRE) to the so-called strong solution of an algebraic Riccati equation (ARE). We furthermore extend our results to Kalman filtering with indefinite input noise covariances View full abstract»

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  • Noninteracting control of descriptor systems involving disturbances

    Publication Year: 1997 , Page(s): 542 - 548
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (292 KB)  

    For m-input p-output descriptor systems involving disturbances, it is proven that if the problem of disturbance rejection is solvable via static-state feedback and the input-output transfer function matrix is right invertible, there always exists a static-state feedback control law yielding, simultaneously to disturbance rejection, a triangular input-output relation. The structural properties of the closed-loop system (stability, pole assignment, etc.) are extensively studied View full abstract»

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  • Tight bounds for the trace of a matrix product

    Publication Year: 1997 , Page(s): 578 - 581
    Cited by:  Papers (8)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (164 KB)  

    We propose a family of new upper and lower bounds for the trace of the matrix product AB when A, or B is symmetric. Those bounds depend on a scalar parameter, and both converge monotonically to tr(AB) when this parameter vanishes, thus providing arbitrary close approximations. Even large values of the parameter yield very good bounds View full abstract»

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  • Pade approximants for the transient optimization of hedging control policies in manufacturing

    Publication Year: 1997 , Page(s): 440 - 457
    Cited by:  Papers (5)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (928 KB)  

    Part production is considered over a finite horizon in a single-part multiple-failure mode manufacturing system. When the rate of demand for parts is constant, for Markovian machine-mode dynamics and for convex running cost functions associated with part inventories or backlogs, it is known that optimal part-production policies are of the so-called hedging type. For the infinite-horizon case, such policies are characterized by a set of constant critical machine-mode dependent inventory levels that must be aimed at and maintained whenever possible. For the finite-horizon (transient) case, the critical levels still exist, but they are now time-varying and in general very difficult to characterize. Thus, in an attempt to render the problem tractable, transient production optimization is sought within the (suboptimal) class of time-invariant hedging control policies, a renewal equation is developed for the cost functional over finite horizon under an arbitrary time-invariant hedging control policy View full abstract»

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  • Robust decoupling of discrete systems using ℒ1 optimization

    Publication Year: 1997 , Page(s): 549 - 553
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (232 KB)  

    We address a control design problem related to decoupling, namely robust decoupling. The idea of robust decoupling is defined and shown to be equivalent to robust performance of a Hadamard-weighted L1 performance measure. A necessary and sufficient condition to determine if a compensator satisfies robust performance of a Hadamard-weighted L1 performance measure in the presence of structured uncertainty is given. This condition can be used to determine if a compensator robustly decouples a plant. Finally, an iterative scheme for synthesizing a robust decoupling controller is discussed View full abstract»

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  • Two examples of ill-posedness with respect to time delays revisited

    Publication Year: 1997 , Page(s): 511 - 515
    Cited by:  Papers (14)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (192 KB)  

    We revisit two examples of elastic control systems which are stabilized by boundary feedback and then destabilized when time delays occur in the feedback. In the first example, a wave equation with a feedback gain greater than or equal to one, arbitrary divergence rates are obtained for small time delays. In the second example, a Euler-Bernoulli beam, any time delay results in an arbitrary divergence rate View full abstract»

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  • Time-varying exponential stabilization of a rigid spacecraft with two control torques

    Publication Year: 1997 , Page(s): 528 - 534
    Cited by:  Papers (52)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (264 KB)  

    Rigid body models with two controls cannot be locally asymptotically stabilized by continuous feedbacks which are functions of the state only. This impossibility no longer holds when the feedback is also a function of time, and time-varying asymptotically stabilizing feedbacks have already been proposed. However, due to the smoothness of the feedbacks, the convergence rate is only polynomial. In this paper, exponential convergence is obtained by considering time-varying feedbacks which are only continuous View full abstract»

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  • The contact problem for linear continuous-time dynamical systems: a geometric approach

    Publication Year: 1997 , Page(s): 458 - 472
    Cited by:  Papers (15)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (772 KB)  

    In this paper linear time-invariant dynamical systems described by a combination of differential equalities and static inequalities in state-space formulation are investigated. Of special interest is the contact problem: the effect of the boundary of the constraint set on the behavior of the system. This effect is studied by dividing the state-space in a number of disjunct subsets. It is shown that these subsets are invariant under linear state feedback. In our framework, a specific place is reserved for modeling the laws of collision, i.e., physical modeling, which are regarded as external factors. Our main results are a system theoretical framework in which we describe what happens upon contact and a definition of the constrained state-space system in terms of its restricted behavior. The results presented here can be considered as an extension for restricted linear systems of the classic positive invariance theory for linear systems View full abstract»

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  • Robust adaptive sampled-data control of a class of systems under structured nonlinear perturbations

    Publication Year: 1997 , Page(s): 553 - 558
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (248 KB)  

    A robust adaptive sampled-data feedback stabilization scheme is presented for a class of systems with nonlinear additive perturbations. The proposed controller generates a control input by using high-gain static or dynamic feedback from nonuniform sampled values of the output. A simple adaptation rule adjusts the gain and the sampling period of the controller View full abstract»

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  • An approximate nonlinear observer with polynomial coordinate transformation maps

    Publication Year: 1997 , Page(s): 522 - 527
    Cited by:  Papers (8)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (292 KB)  

    The state equivalence condition to the nonlinear observer form is stated in terms of the exactness of one-form. Using the definition of the approximate closedness, we relax the equivalence condition, thereby obtaining a necessary and sufficient condition for the approximate observer error linearizability. This approximate observer theory extends the realm of applications. Another great advantage of this approximation method is that the coordinate transformation is directly obtainable as vectors of polynomials, while it is, in general, not possible with the existing method, View full abstract»

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  • A systematic approach to adaptive observer synthesis for nonlinear systems

    Publication Year: 1997 , Page(s): 534 - 537
    Cited by:  Papers (82)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (144 KB)  

    Geometric techniques of controller design for nonlinear systems have enjoyed great success. A serious shortcoming, however, has been the need for access to full-state feedback. This paper addresses the issue of state estimation from limited sensor measurements in the presence of parameter uncertainty. An adaptive nonlinear observer is suggested for Lipschitz nonlinear systems, and the stability of this observer is shown to be related to finding solutions to a quadratic inequality involving two variables. A coordinate transformation is used to reformulate this inequality as a linear matrix inequality. A systematic algorithm is presented, which checks for feasibility of a solution to the quadratic inequality and yields an observer whenever the solution is feasible. The state estimation errors then are guaranteed to converge to zero asymptotically. The convergence of the parameters, however, is determined by a persistence-of-excitation-type constraint View full abstract»

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  • A unifying construction of orthonormal bases for system identification

    Publication Year: 1997 , Page(s): 515 - 521
    Cited by:  Papers (147)  |  Patents (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (304 KB)  

    This paper develops a general and very simple construction for complete orthonormal bases for system identification. This construction provides a unifying formulation of many previously studied orthonormal bases since the common FIR and recently popular Laguerre and two-parameter Kautz model structures are restrictive special cases of the construction presented here. However, in contrast to these special cases, the basis vectors in the unifying construction of this paper can have arbitrary placement of pole position according to the prior information the user wishes to inject. Results characterizing the completeness of the bases and the accuracy properties of models estimated using the bases are provided View full abstract»

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  • Point-to-point regulation of a robot with flexible joints including electrical effects of actuator dynamics

    Publication Year: 1997 , Page(s): 559 - 564
    Cited by:  Papers (12)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (232 KB)  

    This paper considers the set-point tracking problem in rigid and flexible-joint robots when both the mechanical as well as the electrical effects of the actuator dynamics are taken into account. The suggested controllers are based on state and output feedbacks. The current approach demonstrates that for every given desired operating point, linear state and output feedbacks with constant feedforwards can be constructed such that the closed-loop system is globally asymptotically stable View full abstract»

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  • Robust feedback stabilization of chemical reactors

    Publication Year: 1997 , Page(s): 473 - 481
    Cited by:  Papers (33)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (388 KB)  

    This paper deals with the temperature stabilization of a large class of continuously stirred tank chemical reactors. We design state feedback controllers, and we show their ability to globally stabilize the temperature at an arbitrary set point in spite of uncertainties on the kinetics. Furthermore, it is also shown that these controllers can handle input constraints along the closed-loop trajectories in some instances. For the implementation purpose, we design a robust state observer for the case of partial state measurement, and we prove that its incorporation in the feedback loops does not impair the nominal stabilization properties of the controllers View full abstract»

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  • Convergence analysis of the extended Kalman filter used as an observer for nonlinear deterministic discrete-time systems

    Publication Year: 1997 , Page(s): 581 - 586
    Cited by:  Papers (84)  |  Patents (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (212 KB)  

    In this paper, convergence analysis of the extended Kalman filter (EKF), when used as an observer for nonlinear deterministic discrete-time systems, is presented. Based on a new formulation of the first-order linearization technique, sufficient conditions to ensure local asymptotic convergence are established. Furthermore, it is shown that the design of the arbitrary matrix plays an important role in enlarging the domain of attraction and then improving the convergence of the modified EKF significantly. The efficiency of this approach, compared to the classical version of the EKF, is shown through a nonlinear identification problem as well as a state and parameter estimation of nonlinear discrete-time systems 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