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Automatic Control, IEEE Transactions on

Issue 8 • Date Aug. 1996

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Displaying Results 1 - 21 of 21
  • Comments on consistency of quadratic forms

    Publication Year: 1996 , Page(s): 1215 - 1216
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (229 KB)  

    A remark related to earlier papers (Cheng and Martin, 1995, Geromel et al., 1988, Trofino-Neto and Kucera, 1993) is made with an extension. View full abstract»

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  • Stochastic Processes, Estimation, and Control: The Entropy Approach [Book Reviews]

    Publication Year: 1996
    Save to Project icon | Request Permissions | PDF file iconPDF (193 KB)  
    Freely Available from IEEE
  • Robust speed control of induction motors using position and current measurements

    Publication Year: 1996 , Page(s): 1216 - 1220
    Cited by:  Papers (30)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (448 KB)  

    A nonlinear robust output feedback control is designed for a sixth-order model of an induction motor. The control uses only measurement of the rotor position and stator currents. It contains two observers, a second-order observer to estimate the rotor flux from the stator current and a third-order high-gain observer to estimate the rotor speed and acceleration from its position. The control is robust to uncertainties in the rotor and stator resistances, and a bounded time-varying load torque. It guarantees that the speed tracking error can be made arbitrarily small by choice of certain design parameters. Moreover, when the speed reference and load torque are constant, it ensures asymptotic regulation. Simulation results agree well with the analysis View full abstract»

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  • Robust performance of periodic systems

    Publication Year: 1996 , Page(s): 1146 - 1159
    Cited by:  Papers (8)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1176 KB)  

    Robust performance of sampled-data systems to structured periodic and quasi-periodic uncertainty is considered, and necessary and sufficient conditions are derived, The conditions are finite dimensional, and explicitly computing them is investigated; the results are illustrated with an example. This work is readily extended to yield exact and finite dimensional robust performance conditions for structured arbitrary time-varying uncertainty View full abstract»

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  • Sufficient conditions of optimality for stochastic systems with controllable diffusions

    Publication Year: 1996 , Page(s): 1176 - 1179
    Cited by:  Papers (12)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (360 KB)  

    This paper studies optimal controls for systems governed by Ito's stochastic differential equations. Both the drift and diffusion terms of the equations are allowed to depend on controls, and the systems are allowed to be degenerate. It is shown that the necessary conditions of optimality, namely, the maximum conditions in terms of the “ℋ-function” (which is a generalization of the usual Hamiltonian and is quadratic with respect to the diffusion coefficients), along with some convexity conditions, constitute sufficient conditions of optimality for such controlled systems View full abstract»

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  • On the pseudoboundary of unstable polytopes of polynomials

    Publication Year: 1996 , Page(s): 1188 - 1190
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (300 KB)  

    The pseudoboundary of a polytope is defined to be the set of all polynomials in the polytope each of which has at least one zero on the imaginary axis. It is proven that a “section” of the pseudoboundary corresponding to any frequency “ω0” is itself a polytope whose vertices lie in the exposed two-dimensional faces of the given polytope. A simple algorithm is proposed to generate all the vertex polynomials of any section of the pseudoboundary of a polytope. An illustrative example is given View full abstract»

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  • An improved, chattering free, VSC scheme for uncertain dynamical systems

    Publication Year: 1996 , Page(s): 1220 - 1226
    Cited by:  Papers (40)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (480 KB)  

    A control strategy proposed by the authors in previous works to reduce the effect of chattering led to the solution of a differential inequality involving the first and second derivatives of the control signal and a parameter for a first-order observer. The analysis was carried out assuming this parameter to be constant. In the present paper, this assumption is removed, thus allowing the solution of the differential inequality to be a function of a piecewise continuous first derivative of the control signal, without need for assuming a priori knowledge of bounds to the plant trajectories View full abstract»

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  • Optimal policies for the “yield learning” problem in manufacturing systems

    Publication Year: 1996 , Page(s): 1210 - 1213
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (396 KB)  

    The yield learning problem encountered in many manufacturing systems involves controlling the production rate of a process so as to maximize cumulative rewards over some time interval. Because yield improvement occurs as a result of discrete events coinciding with lot processing completions, a basic tradeoff arises as high production rates increase rewards for a given yield but also cause longer average lot lead times which delay the events that trigger yield improvement. We show that in some cases simple bang-bang solutions can be obtained for this problem through standard optimal control techniques View full abstract»

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  • High-level primitives for recursive maximum likelihood estimation

    Publication Year: 1996 , Page(s): 1125 - 1145
    Cited by:  Papers (8)  |  Patents (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (2052 KB)  

    This paper proposes a high-level language constituted of a small number of primitives and macros for describing recursive maximum likelihood (ML) estimation algorithms. This language is applicable to estimation problems involving linear Gaussian models or processes taking values in a finite set. The use of high-level primitives allows the development of highly modular ML estimation algorithms based on simple numerical building blocks. The primitives, which correspond to the combination of different measurements, the extraction of sufficient statistics, and the conversion of the status of a variable from unknown to observed, or vice versa, are first defined for linear Gaussian relations specifying mixed deterministic/stochastic information about the system variables. These primitives are used to define other macros and are illustrated by deriving new filtering and smoothing algorithms for linear descriptor systems. The primitives are then extended to finite state processes and used to implement the Viterbi ML state sequence estimator for a hidden Markov model View full abstract»

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  • Bounded-input bounded-output stability of a damped nonlinear string

    Publication Year: 1996 , Page(s): 1179 - 1182
    Cited by:  Papers (7)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (368 KB)  

    In this paper, we prove that the displacement of a damped nonlinear string under bounded distributed forces is bounded. The proof is achieved by showing that an energy-like (Lyapunov) function corresponding to the string is bounded View full abstract»

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  • Nonblocking supervisory control of nondeterministic systems via prioritized synchronization

    Publication Year: 1996 , Page(s): 1160 - 1175
    Cited by:  Papers (29)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1616 KB)  

    Shayman and Kumar (1995) showed that supervisory control of nondeterministic discrete-event systems, in the presence of driven events, can be achieved using prioritized synchronous composition as a mechanism of control, and trajectory models as a modeling formalism, first introduced by Heymann (1990). The specifications considered in this earlier work were given by prefix-closed languages. In this paper, we extend this work to include markings so that nonclosed specifications and issues such as blocking can be addressed. It is shown that the usual notion of nonblocking, called language model nonblocking, may not be adequate in the setting of nondeterministic systems, and a stronger notion, called trajectory model nonblocking, is introduced. Necessary and sufficient conditions for the existence of language model nonblocking as well as trajectory model nonblocking supervisors are obtained for nondeterministic systems in the presence of driven events in terms of extended controllability and relative-closure conditions and a new condition called the trajectory-closure condition View full abstract»

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  • On the exponentiality of stochastic linear systems under the max-plus algebra

    Publication Year: 1996 , Page(s): 1182 - 1188
    Cited by:  Papers (10)  |  Patents (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (648 KB)  

    Considers stochastic linear systems under the max-plus algebra. For such a system, the states are governed by the recursive equation X n=An⊗Xn-1⊕Un with the initial condition condition X0=x0. By transforming the linear system under the max-plus algebra into a sublinear system under the usual algebra, we establish various exponential upper bounds for the tail distributions of the states Xn under the independently identically distributed (i.i.d.) assumption on {(An,Un)1n⩾1} and a couple of regularity conditions on (A1,U1) and the initial condition x0. These upper bounds are related to the spectral radius (or the Perron-Frobenius eigenvalue) of the nonnegative matrix in which each element is the moment generating function of the corresponding element in the state-feedback matrix A1. In particular, we have Kingman's upper bound for GI/GI/1 queue when the system is one-dimensional. We also show that some of these upper bounds can be achieved if A1 is lower triangular. These bounds are applied to some commonly used systems to derive new results or strengthen known results View full abstract»

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  • A modified Smith predictor for controlling a process with an integrator and long dead-time

    Publication Year: 1996 , Page(s): 1199 - 1203
    Cited by:  Papers (83)  |  Patents (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (340 KB)  

    A modification of the Smith predictor for controlling higher-order processes with integral action and long dead-time is proposed. The controller has a quite simple structure which is obtained based on the model consisting of an ideal integrator and dead-time and which includes only three tuning parameters: the dead-time, velocity gain of the model, and the desired time constant of the first-order closed-loop setpoint response. By adjusting these three parameters, high performance can be obtained both for the setpoint response and for the load disturbance rejection View full abstract»

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  • A lower bound for the correct subset-selection probability and its application to discrete-event system simulations

    Publication Year: 1996 , Page(s): 1227 - 1231
    Cited by:  Papers (61)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (480 KB)  

    Ordinal optimization concentrates on finding a subset of good designs, by approximately evaluating a parallel set of designs, and reduces the required simulation time dramatically for discrete-event simulation and optimization. The estimation of the confidence probability (CP) that the selected designs contain at least one good design is crucial to ordinal optimization. However, it is very difficult to estimate this probability in DES simulation, especially for complicated DES with large number of designs. This paper proposes two simple lower bounds for quantifying the confidence probability. Numerical testing is presented View full abstract»

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  • An improved log-likelihood gradient for continuous-time stochastic systems with deterministic input

    Publication Year: 1996 , Page(s): 1207 - 1210
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (332 KB)  

    Using a covariance operator approach, we derive an explicit expression for the log-likelihood ratio gradient for system parameter estimation for continuous-time stochastic systems with deterministic inputs. The gradient formula includes the smoother estimates and derivatives of system matrices with no derivatives of estimates or covariance matrices. A deterministic input is also permitted, and the state noise covariance is not required to be nonsingular. Stable numerical techniques to calculate the gradient are also discussed View full abstract»

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  • Arbitrary robust eigenvalue placement by a static-state feedback

    Publication Year: 1996 , Page(s): 1214 - 1215
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (192 KB)  

    It is demonstrated that robust eigenvalue placement in the disk of an arbitrary radius r centered at -2r can be achieved by a static-state feedback for systems with so-called matched perturbations of uncertain parameters in the state coefficient matrix A (i.e. with perturbations of A in the range of the input matrix B). This implies, in particular, that such systems can be robustly stabilized with an arbitrarily fixed degree of exponential decay, and thus it extends previously known results on robust stabilization without eigenvalue placement conditions. This result is in sharp contrast with the case of general perturbations in either A or B or both, where there are limits for the degree of exponential stabilizability which depend on the size of perturbations View full abstract»

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  • Distributively controlling two robots handling an object in the task space without any communication

    Publication Year: 1996 , Page(s): 1193 - 1198
    Cited by:  Papers (30)  |  Patents (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (504 KB)  

    Two distributed cooperation controllers are presented for trajectory tracking of two manipulators which are cooperatively handling an object. The controllers control the positions of the robots distributively by using the trajectory error of the object in the task space. In the first controller, the internal force between the object and a manipulator is controlled only by a feedforward of the desired force. The second controller uses a force feedback. No communication is required between the manipulators in both the controllers. Their globally and exponentially asymptotic stabilities are guaranteed by Lyapunov functions View full abstract»

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  • Equivalence between positive real and norm-bounded uncertainty

    Publication Year: 1996 , Page(s): 1190 - 1193
    Cited by:  Papers (4)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (384 KB)  

    This paper focuses on a linear time-invariant system with positive real uncertainty and shows an equivalence between positive real and norm-bounded uncertainty resulting in transformation of a proper transfer function with positive real uncertainty directly to a strictly proper transfer function with norm-bounded uncertainty which is different from the result obtained by using bilinear transform. This paper also shows a secondary result, relations between the quadratic and robust stability of a system with positive real uncertainty View full abstract»

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  • First- and second-derivative estimators for cyclic closed-queueing networks

    Publication Year: 1996 , Page(s): 1106 - 1124
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1492 KB)  

    We consider a cyclic closed-queueing network with arbitrary service time distributions and derive first- and second-derivative estimators of some finite horizon performance metrics with respect to a parameter of any one of the service distributions. Our approach is based on observing a single sample path of this system and evaluating first- and second-order effects on departure times as a result of the parameter perturbation. We then define an estimator as a conditional expectation over appropriate observable quantities, using smoothed perturbation analysis techniques. This process recovers the first-derivative estimator along the way and gives new insights into event order change phenomena which are of higher order. Despite the complexity of the analysis, the final algorithms we obtain are relatively simple. Further, we show that our estimators are unbiased and include some numerical examples. We also show the use of our estimators in obtaining approximations of the entire system response surface as a function of system parameters View full abstract»

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  • Continuous-time control model validation using finite experimental data

    Publication Year: 1996 , Page(s): 1094 - 1105
    Cited by:  Papers (25)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1012 KB)  

    The application of robust control theory requires models containing unknown, bounded perturbations and unknown, bounded input signals. Model validation is a means of assessing the applicability of a given model with respect to experimental data. This paper develops a theoretical framework, and a computational solution, for the model validation problem in the case where the model, including unknown perturbations and signals, is given in the continuous time domain, yet the experimental datum is a finite, sampled signal. The continuous nature of the unknown components is treated directly with a sampled data lifting theory. This gives results which are valid for any sample period and any datum length. Explicit calculation of whether sufficient data for invalidation has been obtained arises naturally in this framework. A common class of robust control models is treated and leads to a convex matrix optimization problem. A simulation example illustrates the approach View full abstract»

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  • Semiglobal stabilization of linear discrete-time systems subject to input saturation, via linear feedback-an ARE-based approach

    Publication Year: 1996 , Page(s): 1203 - 1207
    Cited by:  Papers (39)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (492 KB)  

    We revisit the problem of semiglobal stabilization of linear discrete-time systems subject to input saturation and give an algebraic Riccati equation (ARE)-based approach to the proof of a fact established earlier (Lin and Saberi, 1995), i.e. a linear discrete-time system subject to input saturation is semiglobally stabilizable via linear feedback as long as the linear system in the absence of the saturation is stabilizable and detectable and all its open-loop poles are located inside or on the unit circle. Moreover, we drastically relax the requirements on the characteristic of the saturation elements as imposed in the earlier work 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