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Automatic Control, IEEE Transactions on

Issue 5 • Date May 2000

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Displaying Results 1 - 25 of 33
  • Comments on "Robustifying nonlinear systems using high-order neural network controllers"

    Publication Year: 2000 , Page(s): 1033 - 1036
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (177 KB)  

    *** PLEASE ASK ME ABOUT THIS (PHILIP) *** In the original paper by G.A. Rovithakis (ibid., vol.44, p.102-8, 1999), a nonlinear dynamical system is considered. The author indicates that Rovithakis overlooked some essential assumptions on the allowable perturbations, that the problem is therefore not well-posed, and that the controller derived is incorrect Rovithakis replies that it is well known that a system of the type considered can in some cases be decomposed into a controllable and an uncontrollable part and that it is obvious that in such a case the controller would apply only to the former. Rovithakis shows that Zhang's other results are incorrect. View full abstract»

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  • Author's reply

    Publication Year: 2000 , Page(s): 1036
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (47 KB)  

    First Page of the Article
    View full abstract»

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  • Random iterative models [Book Reviews]

    Publication Year: 2000 , Page(s): 1037 - 1039
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    Freely Available from IEEE
  • A hybrid genetic algorithm for estimating the optimal time scale of linear systems approximations using Laguerre models

    Publication Year: 2000 , Page(s): 1007 - 1011
    Cited by:  Papers (10)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (136 KB)  

    We deal with the problem of finding the optimal time scale of the truncated Laguerre series using numerical search techniques. We develop a hybrid genetic algorithm (GA) to search the nonlinear, multimodal squared-error function that results from least-squares approximations of the impulse response of causal linear time-invariant stable systems. The hybrid GA incorporates a Newton-Raphson (NR) local optimizer for fast convergence to the global minimum point. The proposed method competes favorably with the pure GA in solution accuracy (the number of function evaluations being the same) and with an established gradient-directed optimization algorithm in number of function evaluations (the solution accuracy being the same) View full abstract»

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  • Stochastic approximation and user adaptation in a competitive resource sharing system

    Publication Year: 2000 , Page(s): 844 - 853
    Cited by:  Papers (5)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (216 KB)  

    This paper is motivated by the work of Altman and Shimkin (1998). Customers arrive at a service center and must choose between two types of service: a channel that is shared by all currently in it and a dedicated line. The mean service cost (or time) for any customer entering the shared resource depends on the decisions of all future arrivals up to the time of departure of that customer, and so has a competitive aspect. The decision rule of each arriving customer is based on its own immediate self-interest, given the available data on the past performance. If the current estimate of the cost for the shared resource equals that of the dedicated line, any decision is possible. The procedure is a type of learning algorithm. The convergence problem is one in asynchronous stochastic approximation, where the ODE may be a differential inclusion. It is shown that, asymptotically, the performance of the learning system is that for the symmetric Nash strategy, despite the allowed arbitrariness and lack of coordination View full abstract»

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  • A two-step adaptive controller for a two-body system

    Publication Year: 2000 , Page(s): 1011 - 1016
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (184 KB)  

    A reduced-order adaptive control scheme using a direct state-feedback control law and an indirect feedforward compensation design is presented for a two-body system with joint flexibility and damping. A detailed stability analysis is given for such a two-step adaptive control design, which ensures closed-loop signal boundedness and asymptotic output tracking View full abstract»

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  • Using scales in the multiobjective approach

    Publication Year: 2000 , Page(s): 973 - 977
    Cited by:  Papers (6)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (156 KB)  

    Scales are used to reduce the conservatism encountered in most multiobjective approaches to control design. The most general case (i.e., matrix scales) results in a nonconvex problem, though the use of scalar scales leads to convex searches in the analysis and state feedback problems. Output feedback synthesis and other extensions are discussed. Numerical examples are provided to show the effectiveness of the suggested approach. The article considers, in particular, H control View full abstract»

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  • Robust and minimum norm pole assignment with periodic state feedback

    Publication Year: 2000 , Page(s): 1017 - 1022
    Cited by:  Papers (24)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (216 KB)  

    A computational approach is proposed to solve the minimum norm or robust pole assignment problem for linear periodic discrete-time systems. The proposed approach uses a periodic Sylvester-equation-based parametrization of the periodic pole assignment problem and exploits the nonuniqueness of the problem by imposing conditions on the norm of the resulting periodic state feedback or on the condition numbers of the periodic eigenvector matrices of the closed-loop system. The solution method relies on using gradient search methods on suitably defined cost functions. Explicit expressions of the gradients of cost functions are derived, and the efficient evaluation of the cost functions and gradients is discussed. Numerical examples illustrate the effectiveness of the proposed approach View full abstract»

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  • Output feedback control of Markov jump linear systems in continuous-time

    Publication Year: 2000 , Page(s): 944 - 949
    Cited by:  Papers (125)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (204 KB)  

    This paper addresses the dynamic output feedback control problem of continuous-time Markovian jump linear systems. The fundamental point in the analysis is an LMI characterization, comprising all dynamical compensators that stabilize the closed-loop system in the mean square sense. The H2 and H-norm control problems are studied, and the H2 and H filtering problems are solved as a by product View full abstract»

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  • Observation control for discrete-continuous stochastic systems

    Publication Year: 2000 , Page(s): 993 - 998
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (220 KB)  

    Presents a theoretical framework for the optimization of observations in partially observable linear discrete-continuous stochastic systems. The problem of achievement of the best quality of estimation with discrete and continuous observations is reduced to a deterministic one with impulse or generalized control. An approach based on the discontinuous time transformation is presented and used to reduce the original optimization problem with impulsive control to the standard one with bounded controls. The existence and description of the optimal generalized observation process are also discussed. The illustrative example of the observations optimal control is presented View full abstract»

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  • An exponentially stable adaptive friction compensator

    Publication Year: 2000 , Page(s): 977 - 980
    Cited by:  Papers (25)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (132 KB)  

    This note presents a novel adaptive compensation scheme for Coulomb friction in a servocontrol system. An adaptive observer for estimating the unknown Coulomb friction coefficient is also derived on the basis of the Lyapunov technique. In addition, a linearizing control law is developed to compensate for the friction force and obtain the tracking objective. The proposed adaptive compensation guarantees an exponential convergence for state errors and parameter error, and known adaptive schemes guarantee only an asymptotic (or stable) convergence. Simulation results demonstrate the effectiveness of the proposed method for a single-mass servocontrol system View full abstract»

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  • Template languages for fault monitoring of timed discrete event processes

    Publication Year: 2000 , Page(s): 868 - 882
    Cited by:  Papers (51)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (424 KB)  

    This paper introduces a new framework for modeling discrete event processes. This framework, called condition templates, allows the modeling of processes in which both single-instance and multiple-instance behaviors are exhibited concurrently. A single-instance behavior corresponds to a trace from a single finite-state process, and a multiple-instance behavior corresponds to the timed interleavings of an unspecified number of identical processes operating at the same time. The template framework allows the modeling of correct operation for systems consisting of concurrent mixtures of both single and multiple-instance behaviors. This representation can then be used in online fault monitoring for confirming the correct operation of a system. We compare the class of timed languages representable by template models with classes of timed languages from timed automata models. It is shown that templates are able to model timed languages corresponding to single and multiple-instance behaviors and combinations thereof. Templates can thus represent languages that could not be represented or monitored using timed automata alone View full abstract»

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  • Existence and design of functional observers for linear systems

    Publication Year: 2000 , Page(s): 940 - 943
    Cited by:  Papers (49)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (112 KB)  

    This paper presents straightforward derivations of the functional observers design for linear time-invariant multivariable systems. The order of these observers is equal to the dimension τ of the vector to be estimated. Necessary and sufficient conditions for the existence and stability of these observers are given. Illustrative examples are included View full abstract»

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  • Maximum likelihood parameter estimation from incomplete data via the sensitivity equations: the continuous-time case

    Publication Year: 2000 , Page(s): 928 - 934
    Cited by:  Papers (21)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (304 KB)  

    This paper deals with maximum likelihood (ML) parameter estimation of continuous-time nonlinear partially observed stochastic systems, via the expectation maximization (EM) algorithm. It is shown that the EM algorithm can be executed efficiently, provided the unnormalized conditional density of nonlinear filtering is either explicitly solvable or numerically implemented. The methodology exploits the relationships between incomplete and complete data, log-likelihood and its gradient View full abstract»

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  • Optimal adaptive control for estimation of parameters of ARX models

    Publication Year: 2000 , Page(s): 964 - 968
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (208 KB)  

    The objective of this paper is to find an adaptive control strategy which would enable us to estimate the parameters of the ARX model as accurately as possible while keeping the output of the system below a specified level of variability. It turns out that this optimal experiment design problem can be solved by using the Astrom-Wittenmark self-tuning tracker (1973) with a specific choice of the reference signal View full abstract»

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  • Virtual reference direct design method: an off-line approach to data-based control system design

    Publication Year: 2000 , Page(s): 954 - 959
    Cited by:  Papers (24)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (212 KB)  

    This paper presents a direct model-reference approach to the off-line design of linear controllers, suited to deal with plants described by a single set of open-loop I/O measurements only. The method is direct inasmuch as the controller parameters are directly estimated with no preliminary identification of any model to describe the plant. The design can be carried out off-line and, in the present formulation, leads to a nonadaptive controller. The basic idea is that of interpreting the open-loop I/O measurements of the plant as closed-loop data produced by a “virtual” reference signal that can be computed by backpropagating the measured output of the plant through the reference model; thus, the controller design reduces to a standard identification problem, in which the “output” signal to be matched is the measured input of the plant. Both a deterministic (noise-free) and a stochastic setting, are considered View full abstract»

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  • Exponential stabilization of a class of unstable bilinear systems

    Publication Year: 2000 , Page(s): 989 - 992
    Cited by:  Papers (15)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (136 KB)  

    Considers the control design of bilinear systems with multiplicative control inputs. Previous control designs for such systems normally assume that the open-loop bilinear system is (neutrally) stable. In this paper, a nonlinear control design is proposed for open-loop unstable bilinear systems. The new control stabilizes the bilinear system globally and exponentially if a sufficient stability condition, which can be checked by off-line computer simulations in advance of the control, is satisfied View full abstract»

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  • A generalized chain-scattering representation and its algebraic system properties

    Publication Year: 2000 , Page(s): 1002 - 1007
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (188 KB)  

    Presents a generalization of the chain-scattering representation to the case of general plants. Through the notion of input-output consistency, the conditions under which the generalized chain-scattering representation (GCSR) and the dual-generalized chain-scattering representation (DGCSR) exist are proposed. The generalized chain-scattering matrices are formulated into a general parameterized form by using the generalized inverse of matrices. Some algebraic system properties, such as the cascade structure property, the symmetry (duality) of the GCSR's and DGCSR's, are studied View full abstract»

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  • Nonlinear repetitive control

    Publication Year: 2000 , Page(s): 949 - 954
    Cited by:  Papers (54)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (196 KB)  

    Repetitive controllers are generally applied to reject periodic disturbances and to track periodic reference signals with a known period. Their design is based on the internal model principle, proposed by Francis and Wonham (1975). This paper describes a new finite-dimensional SISO repetitive controller for two different classes of nonlinear plants. Simulation results show asymptotic tracking of the periodic reference signal by the proposed repetitive controller in closed loop up to the Nth harmonic frequency. A proof of robustness of the repetitive control system to small nonlinearities, like actuator nonlinearities, is provided View full abstract»

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  • On the design of a nonlinear adaptive variable structure derivative estimator

    Publication Year: 2000 , Page(s): 1028 - 1033
    Cited by:  Papers (11)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (216 KB)  

    Develops a derivative estimator using variable structure system (VSS) and adaptive techniques. The proposed nonlinear adaptive variable structure derivative estimator requires little knowledge about the observed signal source and is able to handle the observed signals that are the outputs of either linear or nonlinear dynamic systems with uncertainties. In the absence of system noise, the uniform boundedness of the proposed derivative estimation is guaranteed by means of the adaptive control approach. By virtue of VSS, the new derivative estimator is capable of adapting itself to the noise environment, especially the unpredictable changes in system noise View full abstract»

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  • A receding horizon generalization of pointwise min-norm controllers

    Publication Year: 2000 , Page(s): 898 - 909
    Cited by:  Papers (56)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (300 KB)  

    Control Lyapunov functions (CLFs) are used in conjunction with receding horizon control to develop a new class of receding horizon control schemes. In the process, strong connections between the seemingly disparate approaches are revealed, leading to a unified picture that ties together the notions of pointwise min-norm, receding horizon, and optimal control. This framework is used to develop a CLF based receding horizon scheme, of which a special case provides an appropriate extension of Sontag's formula. The scheme is first presented as an idealized continuous-time receding horizon control law. The issue of implementation under discrete-time sampling is then discussed as a modification. These schemes are shown to possess a number of desirable theoretical and implementation properties. An example is provided, demonstrating their application to a nonlinear control problem. Finally, stronger connections to both optimal and pointwise min-norm control are proved View full abstract»

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  • Computing efforts allocation for ordinal optimization and discrete event simulation

    Publication Year: 2000 , Page(s): 960 - 964
    Cited by:  Papers (40)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (184 KB)  

    Ordinal optimization has emerged as an efficient technique for simulation and optimization. Exponential convergence rates can be achieved in many cases. In this paper, we present a new approach that can further enhance the efficiency of ordinal optimization. Our approach intelligently determines the optimal number of simulation replications (or samples) and significantly reduces the total simulation cost. Numerical illustrations are included. The results indicate that our approach can obtain an additional 74% computation time reduction above and beyond the reduction obtained through the use of ordinal optimization for a 10-design example View full abstract»

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  • A state observer for nonlinear systems and its application to ball and beam system

    Publication Year: 2000 , Page(s): 968 - 973
    Cited by:  Papers (18)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (212 KB)  

    In this paper, we present a state observer for single-input/single-output nonlinear systems which fail to have well defined relative degree. It is shown that there exists a local state observer for a nonlinear system if it has robust relative degree n. The proposed observer utilizes the coordinate change which transforms a system into an approximate normal form. The proposed method is applied to a ball and beam system, and simulation results show that substantial improvement in the performance was achieved compared with other local observers View full abstract»

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  • Gaussian filters for nonlinear filtering problems

    Publication Year: 2000 , Page(s): 910 - 927
    Cited by:  Papers (249)  |  Patents (6)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (432 KB)  

    We develop and analyze real-time and accurate filters for nonlinear filtering problems based on the Gaussian distributions. We present the systematic formulation of Gaussian filters and develop efficient and accurate numerical integration of the optimal filter. We also discuss the mixed Gaussian filters in which the conditional probability density is approximated by the sum of Gaussian distributions. A new update rule of weights for Gaussian sum filters is proposed. Our numerical tests demonstrate that new filters significantly improve the extended Kalman filter with no additional cost, and the new Gaussian sum filter has a nearly optimal performance View full abstract»

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  • Control system design for mechanical systems using contraction theory

    Publication Year: 2000 , Page(s): 984 - 989
    Cited by:  Papers (22)  |  Patents (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (208 KB)  

    Contraction theory is a control system tool based on an exact differential analysis of convergence. After establishing new combination properties of contracting systems, the paper derives new controller and observer designs for mechanical systems such as aircraft and underwater vehicles. The classical nonlinear strap down algorithm is also shown to be marginally contracting. The relative simplicity of the approach stems from its effective exploitation of the systems' structural specificities 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