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Automatic Control, IEEE Transactions on

Issue 7 • Date July 1992

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Displaying Results 1 - 25 of 35
  • Comments on "A new and simple algorithm for sliding mode trajectory control of robot arm" by Y.F. Chen, et al

    Publication Year: 1992
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (74 KB)  

    Using the approach presented in the above-titled work (ibid., vol.35, p.828-828, July 1990). The commenter provides simplifications to the control algorithm presented there as well as yielding stronger stability conditions.<> View full abstract»

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  • Difference and differential Riccati equations: a note on the convergence to the strong solution

    Publication Year: 1992 , Page(s): 1055 - 1057
    Cited by:  Papers (7)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (280 KB)  

    The convergence of the solutions of the differential difference Riccati equations to the strong solution of the corresponding algebraic Riccati equation (ARE) is addressed. Detectability only is required in the analysis, and no assumption is made on the eigenvalues on the real imaginary axis (on the unit circle, in the discrete-time case). In particular, from the results, it follows that under the sole assumption of detectability, a positive definite initial condition guarantees convergence to the strong solution, even in the presence of unreachable eigenvalues on the imaginary axis or on the unit circle View full abstract»

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  • Estimating model variance in the case of undermodeling

    Publication Year: 1992 , Page(s): 1004 - 1008
    Cited by:  Papers (13)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (412 KB)  

    A reliable quality estimate of a given model is a prerequisite for any reasonable use of the model. The model error consists of two different contributions: the bias error and the random error. In this contribution, it is shown that the size (variance) of the random error can be reliably estimated in the case where a true system description cannot be achieved in the model structure used. This consistent error estimate can differ considerably from the conventionally used variance estimate, which could thus be misleading View full abstract»

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  • Lower bounds for the solution of the discrete algebraic Lyapunov equation

    Publication Year: 1992 , Page(s): 1017 - 1018
    Cited by:  Papers (5)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (156 KB)  

    Lower bounds for the determinant and for the trace of the matrix solution of the discrete algebraic Lyapunov equation are presented. The determinant is tighter than bounds in the literature, and the trace supplements them View full abstract»

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  • Fast computation of the largest stability radius for a two-parameter linear system

    Publication Year: 1992 , Page(s): 1033 - 1037
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (440 KB)  

    The author describes a fast algorithm to compute the minimum distance to instability, or parameter margin, for a linear time-invariant system subject to rational variations in two real parameters. Both the l and the Euclidean norms are considered for measuring parameter deviations View full abstract»

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  • Control-relevant prefiltering: a systematic design approach and case study

    Publication Year: 1992 , Page(s): 964 - 974
    Cited by:  Papers (19)  |  Patents (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (892 KB)  

    The authors examine the use of control-relevant prefiltering applied to parameter estimation using prediction-error methods. The prefiltering step ensures that the estimated model retains those plant characteristics that are most significant with regards to the user's control requirements. They describe how to systematically build the prefilter in terms of the estimated model structure, the desired closed-loop speed-of-response, and the setpoint/disturbance characteristics of the control problem. Two implementation algorithms are presented which are applied to the plant data obtained from a distillation column. The results show that substantial improvements are obtained from control-relevant prefiltering in output error and partial least-squares estimation, while some caution must be exercised when applied to FIR and low-order ARX estimation View full abstract»

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  • Norm based robust control of state-constrained discrete-time linear systems

    Publication Year: 1992 , Page(s): 1057 - 1062
    Cited by:  Papers (5)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (500 KB)  

    The author presents a theoretical framework for analyzing the stability properties of constrained discrete-time systems in the presence of uncertainty, and it is shown that this formalism provides a unifying approach, including as a particular case the well-known technique of estimating robustness bounds from the solution of a Lyapunov equation. These results are applied to the problem of designing feedback controllers capable of stabilizing a family of systems, while at the same time satisfying state-space constraints View full abstract»

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  • Robust noniterative synthesis of ill-conditioned plants

    Publication Year: 1992 , Page(s): 1080 - 1083
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (280 KB)  

    Ill-conditioned plants with delays are generally difficult to control. Skogestad, Morari and Doyle (1988) applied the μ method to achieve synthesis and analysis of such a problem. An alternative synthesis using the Horowitz method for MIMO uncertain feedback systems is applied to the same example. An economical bandwidth solution was achieved without iterations. Design details and simulations are presented View full abstract»

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  • Nonlinear Morgan's problem: case of (p+1) inputs and p outputs

    Publication Year: 1992 , Page(s): 1067 - 1072
    Cited by:  Papers (4)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (484 KB)  

    Noninvertible static state feedback solutions of the row-by-row decoupling problem are investigated for the class of nonlinear systems having one more input component than output components. The analysis involves a combination of geometric and algebraic tools, but notably avoids the use of (regular or degenerate) controllability distribution (subspaces), the main tools used to date for the class of linear systems. The main idea is finding within the system a chain of integrators that may be attached to one of the inputs in order to appropriately modify the system's structure at infinity View full abstract»

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  • Subsystem interconnection and near optimum control of discrete balanced systems

    Publication Year: 1992 , Page(s): 1026 - 1033
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (616 KB)  

    The relationship between subsystem interconnection of discrete balanced systems and the Hankel singular values is explored. Upper bounds on the spectral norm of the submatrices of the discrete balanced representation are derived by approximating the matrix Riccati equation by its power series expansion with respect to two scalar parameters related to the Hankel singular values. For diagonalizable symmetric discrete-time systems, the relation between the eigenvalues of the subsystems and the eigenvalues of the overall system is explored. It is shown that an upper bound on the distance between corresponding eigenvalues in these two sets is related to the ratio of the Hankel singular values View full abstract»

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  • Stabilization on zero-error manifolds and the nonlinear servomechanism problem

    Publication Year: 1992 , Page(s): 1009 - 1013
    Cited by:  Papers (75)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (396 KB)  

    The extended-linearization methodology is applied to the nonlinear servomechanism problem for the case of time-varying exogenous signals. This yields a novel approach to establishing exponential manifold, known as the zero-error manifold. Advantages of the approach are that the underlying theory is relatively simple, and that a requirement of small derivatives for the exogenous signals is used rather than a requirement that the exogenous signals remain small. Thus certain cases of unbounded exogenous signals can be treated. A transmission zero condition for existence of the requisite zero-error manifold is given View full abstract»

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  • Discrete-time entropy formulation of optimal and adaptive control problems

    Publication Year: 1992 , Page(s): 1083 - 1088
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (396 KB)  

    The discrete-time version of the entropy formulation of optimal control of problems developed by G.N. Saridis (1988) is discussed. Given a dynamical system, the uncertainty in the selection of the control is characterized by the probability distribution (density) function which maximizes the total entropy. The equivalence between the optimal control problem and the optimal entropy problem is established, and the total entropy is decomposed into a term associated with the certainty equivalent control law, the entropy of estimation, and the so-called equivocation of the active transmission of information from the controller to the estimator. This provides a useful framework for studying the certainty equivalent and adaptive control laws View full abstract»

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  • Feedback stabilization of linear diffusion systems with periodically scanning sensors

    Publication Year: 1992 , Page(s): 1019 - 1022
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (308 KB)  

    The feedback stabilization of linear diffusion systems with periodically scanning sensors is considered. The control inputs to the system are given by the feedback of the Sakawa-type observer output. In this case, since the output operator becomes time-periodic, the characteristic multiplier assignment is used to design the observer, and the bounded perturbation theorem of the evolution operators is used to prove the closed-loop stability View full abstract»

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  • Adaptive control of a simple time-varying system

    Publication Year: 1992 , Page(s): 1037 - 1040
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (300 KB)  

    Adaptive control of a first-order randomly varying stochastic process is considered. Several authors have treated this problem using either ergodic theory for Markov processes or martingale limit theorems. In both cases some initial variance calculations and bounds evaluations must be performed in order to apply these techniques and establish the sample path results generally considered in adaptive control. These prior calculations are performed in the more general case where the single parameter follows a random walk and for an identification algorithm requiring no a priori knowledge of noise characteristics View full abstract»

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  • A control-relevant identification strategy for GPC

    Publication Year: 1992 , Page(s): 975 - 980
    Cited by:  Papers (21)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (500 KB)  

    The question of a suitable control-relevant identification strategy for a class of long-range predictive controllers is addressed. It is shown that under certain conditions the best process model for predictive control is that which is estimated using an identification objective function that is a dual of the control objective function. The resulting nonlinear least squares calculation is asymptotically equal to a standard recursive least squares with an appropriate (model and controller-dependent) FIR data prefilter. Experimental results demonstrate the validity and practicality of the proposed estimation law View full abstract»

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  • Identification of linearly overparametrized nonlinear systems

    Publication Year: 1992 , Page(s): 1073 - 1078
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (396 KB)  

    Often, a dynamical model is nonlinear in the unknown parameters, but it can be transformed into an overparametrized linear regression model, where the components of the overparametrization vector are nonlinear functions of the smaller number of unknown parameters. An algorithm that directly identifies the unknown parameters is presented, and the authors characterize the convergence domains under two different sets of assumptions on the excitation of the signals. The corresponding convergence rates are computed View full abstract»

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  • Relative-error H identification from autocorrelation data-a stochastic realization method

    Publication Year: 1992 , Page(s): 1000 - 1004
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (444 KB)  

    A variant of the balanced stochastic truncation (BST) method for approximated realization of power spectrum matrices is shown to form the basis for an identification procedure that is well-suited to the task of determining relative-error-bounded approximate plant models for use in control design from input-output cross correlation data. Central to the theory is a novel L-norm bound on the relative-error between an exact realization of the data and BST approximate realization View full abstract»

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  • Hard frequency-domain model error bounds from least-squares like identification techniques

    Publication Year: 1992 , Page(s): 900 - 912
    Cited by:  Papers (55)  |  Patents (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1088 KB)  

    The problem of deriving so-called hard-error bounds for estimated transfer functions is addressed. A hard bound is one that is sure to be satisfied, i.e. the true system Nyquist plot will be confined with certainty to a given region, provided that the underlying assumptions are satisfied. By blending a priori knowledge and information obtained from measured data, it is shown how the uncertainty of transfer function estimates can be quantified. The emphasis is on errors due to model mismatch. The effects of unmodeled dynamics can be considered as bounded disturbances. Hence, techniques from set membership identification can be applied to this problem. The approach taken corresponds to weighted least-squares estimation, and provides hard frequency-domain transfer function error bounds. The main assumptions used in the current contribution are: that the measurement errors are bounded, that the true system is indeed linear with a certain degree of stability, and that there is some knowledge about the shape of the true frequency response View full abstract»

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  • Accurate identification for control: the necessity of an iterative scheme

    Publication Year: 1992 , Page(s): 991 - 994
    Cited by:  Papers (47)  |  Patents (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (392 KB)  

    If approximate identification and model-based control design are used to accomplish a high-performance control system, then the two procedures must be treated as a joint problem. Solving this joint problem by means of separate identification and control design procedures practically entails an iterative scheme. A frequency-response identification technique and a robust control design method are used to set up such an iterative scheme. Each identification step uses the previously designed controller to obtain new data from the plant. The associated identification problem has been solved by means of a coprime factorization of the unknown plant. The technique's utility is illustrated by an example View full abstract»

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  • Local convergence analysis of conjugate gradient methods for solving algebraic Riccati equations

    Publication Year: 1992 , Page(s): 1062 - 1067
    Cited by:  Papers (4)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (544 KB)  

    Necessary and sufficient conditions are given for local convergence of the conjugate gradient (CG) method for solving symmetric and nonsymmetric algebraic Riccati equations. For these problems, the Frobenius norm of the residual matrix is minimized via the CG method, and convergence in a neighborhood of the solution is predicated on the positive definiteness of the associated Hessian matrix. For the nonsymmetric case, the Hessian eigenvalues are determined by the squares of the singular values of the closed-loop Sylvester operator. In the symmetric case, the Hessian eigenvalues are closely related to the squares of the closed-loop Lyapunov singular values. In particular, the Hessian is positive definite if and only if the associated operator is nonsingular. The invertibility of these operators can be expressed as a noncancellation condition on the eigenvalues of the closed-loop matrices View full abstract»

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  • A new perspective for discrete-time models of a continuous-time system

    Publication Year: 1992 , Page(s): 1013 - 1017
    Cited by:  Papers (19)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (356 KB)  

    Various discrete-time models of a continuous-time system are given an interpretation in terms of the system structures and the hold device. This concept provides a novel perspective of various discrete-time models and a simple way to understand the relationships which exist among those models, but which are not easily visualized without the proposed interpretation. This interpretation of discrete-time models also allows the creation of new types of models. Tables of discrete-time models, including the newly developed ones, are provided View full abstract»

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  • A criterion for joint optimization of identification and robust control

    Publication Year: 1992 , Page(s): 986 - 991
    Cited by:  Papers (27)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (544 KB)  

    A criterion for system identification is developed that is consistent with the intended use of the fitted model for modern robust control synthesis. Specifically, a joint optimization problem is posed which simultaneously solves the plant model estimate and control design, so as to optimize robust performance over the set of plants consistent with a specified experimental data set View full abstract»

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  • Approximation by regular input-output maps

    Publication Year: 1992 , Page(s): 1052 - 1055
    Cited by:  Papers (7)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (376 KB)  

    The authors study approximate dynamic input-output linearization, in the sense of J. Hauser et al. (1989), for multiinput multioutput (MIMO) nonlinear systems which exhibit singularities in the dynamic extension process View full abstract»

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  • Memoryless stabilization of uncertain linear systems including time-varying state delays

    Publication Year: 1992 , Page(s): 1022 - 1026
    Cited by:  Papers (63)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (432 KB)  

    The problem of stabilizing a class of uncertain time-delay systems via memoryless linear feedback is examined. The systems under consideration are linear systems with time-varying state delays. They also contain uncertain parameters (possibly time-varying) whose values are known only to within a prescribed compact bounding set. The main contribution given is to enlarge the class of time-delay systems for which one can construct a stabilizing memoryless linear feedback controller. Within this framework, a novel notion of robust memoryless stabilizability is first introduced via the method of Lyapunov functionals. Then a sufficient condition for the stabilizability is proposed. It is shown that solvability of a parameterized Riccati equation can be used to determine whether the time-delay system satisfies the sufficient condition. If there exists a positive definite symmetric solution satisfying the Riccati equation, a suitable memoryless linear feedback law can be derived View full abstract»

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  • Linear and nonlinear algorithms for identification in H with error bounds

    Publication Year: 1992 , Page(s): 953 - 963
    Cited by:  Papers (61)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (868 KB)  

    A linear algorithm and a nonlinear algorithm for the problem of system identification in H posed by Helmicki et al. (1990) for discrete-time systems are presented. The authors derive some error bounds for the linear algorithm which indicate that it is not robustly convergent. However, the worst-case identification error is shown to grow as log(n), where n is the model order. A robustly convergent nonlinear algorithm is derived, and bounds on the worst-case identification error (in the H norm) are obtained 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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Meet Our Editors

Editor-in-Chief
P. J. Antsaklis
Dept. Electrical Engineering
University of Notre Dame