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Automatic Control, IEEE Transactions on

Issue 12 • Date Dec. 2001

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Displaying Results 1 - 25 of 38
  • Comments on "Output feedback stabilization for uncertain systems: constrained Riccati approach"

    Publication Year: 2001
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (58 KB) |  | HTML iconHTML  

    For original paper, by Cheng, see ibid., vol.43, p.81-4 (1998). In that paper, a sufficient condition for the static output feedback stabilization of uncertain systems with mismatched uncertainties has been derived under the assumption that rank(B)/spl les/rank(C) where B and C are the input matrix and the output matrix respectively. In this note, we show that the sufficient condition of the original paper is not solvable if rank(B) View full abstract»

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  • Comments on "Output feedback stabilization for uncertain systems: constrained Riccati approach"

    Publication Year: 2001
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (45 KB) |  | HTML iconHTML  

    For original paper, by Cheng, see ibid., vol.43, p.81-4 (1998). In the above paper, the constrained Riccati problem (CRP) has been proposed to deal with mismatched uncertainty by extending the concept of the constrained Lyapunov problem. In this note, we show the solvability condition for the CRP only gives a solution for the class of square systems not for the nonsquare systems. View full abstract»

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  • Fixed interval smoothing for state-space models [Book Review]

    Publication Year: 2001 , Page(s): 2046 - 2047
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    Freely Available from IEEE
  • Author index

    Publication Year: 2001 , Page(s): 2049 - 2057
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    Freely Available from IEEE
  • Subject index

    Publication Year: 2001 , Page(s): 2057 - 2080
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    Freely Available from IEEE
  • Robust H control of distributed delay systems with application to combustion control

    Publication Year: 2001 , Page(s): 1930 - 1935
    Cited by:  Papers (98)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (198 KB) |  | HTML iconHTML  

    The article is concerned with the H analysis and synthesis of linear distributed delay systems. An efficient stability and L2-gain criterion is established. It is based on a recent approach to the analysis and design of linear time delay systems which represents the system in an equivalent descriptor form. The obtained criterion is used to derive an efficient state-feedback control design which stabilizes the distributed delay system and achieves a guaranteed disturbance attenuation level in spite of a polytopic uncertainty in the system parameters. The new method is applied to the robust stabilization and control of combustion in rocket motor chambers View full abstract»

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  • Stabilization and controllability for the transmission wave equation

    Publication Year: 2001 , Page(s): 1900 - 1907
    Cited by:  Papers (5)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (282 KB) |  | HTML iconHTML  

    We address the problem of control of the transmission wave equation. In particular, we consider the case where, due to total internal reflection of waves at the interface, the system may not be controlled from exterior boundaries. We show that such a system can be controlled by introducing both boundary control along the exterior boundary and distributed control near the transmission boundary and give a physical explanation why the additional control near the transmission boundary might be needed for some domains View full abstract»

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  • On the convergence rate of ordinal comparisons of random variables

    Publication Year: 2001 , Page(s): 1950 - 1954
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (147 KB) |  | HTML iconHTML  

    The asymptotic exponential convergence rate of ordinal comparisons follows from well-known results in large deviations theory, where the critical condition is the existence of a finite moment generating function. In this note, we show that this is both a necessary and sufficient condition, and also show how one can recover the exponential convergence rate in cases where the moment generating function is not finite. In particular, by working with appropriately truncated versions of the original random variables, the exponential convergence rate can be recovered View full abstract»

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  • A matrix method for determining the imaginary axis eigenvalues of a delay system

    Publication Year: 2001 , Page(s): 2008 - 2012
    Cited by:  Papers (16)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (199 KB) |  | HTML iconHTML  

    The author considers autonomous neutral or retarded matrix delay differential systems. The imaginary axis eigenvalues of such a system are shown to be contained in the set of generalized eigenvalues of an associated matrix pair. If the system is not a singular neutral system, one can replace generalized eigenvalues by the eigenvalues of a single matrix. We also show in both the neutral and retarded cases that system pure imaginary eigenvalues are limited to the values at which an associated second degree matrix polynomial becomes singular. Associated system eigenvectors are also eigenvectors of this matrix polynomial. Examples are given in which the matrix, the matrix pair, and the matrix polynomial are used for stability analysis View full abstract»

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  • Sliding mode observer for nonlinear uncertain systems

    Publication Year: 2001 , Page(s): 2012 - 2017
    Cited by:  Papers (78)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (182 KB) |  | HTML iconHTML  

    A new sliding mode observer for a class of nonlinear uncertain systems is proposed in this article. The proposed sliding mode observer works under much less conservative conditions than previous nonlinear unknown input observers. Also, a functional version of the observer is proposed in certain cases where it may not be possible to design an observer capable of estimating the entire state of the system View full abstract»

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  • Relaxed persistency of excitation for uniform asymptotic stability

    Publication Year: 2001 , Page(s): 1874 - 1886
    Cited by:  Papers (51)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (413 KB) |  | HTML iconHTML  

    The persistency of excitation property is crucial for the stability analysis of parameter identification algorithms and adaptive control loops. We propose a relaxed definition of persistency of excitation and we use it to establish uniform global asymptotic stability (UGAS) for a large class of nonlinear, time-varying systems. Our relaxed definition is conceptually equivalent to the definition introduced in Loria et al. (1999), but is easier to verify. It is useful for stability analysis of nonlinear systems that arise, for example, in nonlinear adaptive control, stabilization of nonholonomic systems, and tracking control. Our proof of UGAS relies on some integral characterizations of UGAS established in Teel et al. (2000). These characterizations also streamline the proof of UGAS in the presence of (uniform) classical persistency of excitation View full abstract»

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  • Continuous-time analysis, eigenstructure assignment, and H2 synthesis with enhanced linear matrix inequalities (LMI) characterizations

    Publication Year: 2001 , Page(s): 1941 - 1946
    Cited by:  Papers (126)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (163 KB) |  | HTML iconHTML  

    This note describes a new framework for the analysis and synthesis of control systems, which constitutes a genuine continuous-time extension of results that are only available in discrete time. In contrast to earlier results the proposed methods involve a specific transformation on the Lyapunov variables and a reciprocal variant of the projection lemma, in addition to the classical linearizing transformations on the controller data. For a wide range of problems including robust analysis and synthesis, multichannel H2 stateand output-feedback syntheses, the approach leads to potentially less conservative linear matrix inequality (LMI) characterizations. This comes from the fact that the technical restriction of using a single Lyapunov function is to some extent ruled out in this new approach. Moreover, the approach offers new potentials for problems that cannot be handled using earlier techniques. An important instance is the eigenstructure assignment problem blended with Lyapunov-type constraints which is given a simple and tractable formulation View full abstract»

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  • Further results for systems with repeated scalar nonlinearities

    Publication Year: 2001 , Page(s): 2031 - 2035
    Cited by:  Papers (7)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (158 KB) |  | HTML iconHTML  

    A class of nonlinear systems described by a discrete-time state-equation containing a repeated scalar nonlinearity is considered. This paper sharpens several previous results on the performance synthesis and model reduction for such systems. Extensions to the case that the nonlinearity is not an odd function are also discussed View full abstract»

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  • New bounded real lemma representations for time-delay systems and their applications

    Publication Year: 2001 , Page(s): 1973 - 1979
    Cited by:  Papers (48)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (237 KB) |  | HTML iconHTML  

    New delay-dependent/delay-independent bounded real criteria are derived for linear continuous-time systems with delay in the dynamics and in the objective function. A sufficient condition for the system to possess a H-norm that is less than a prescribed level, is given in terms of a linear matrix inequality (LMI). The proposed criteria are less conservative than other existing criteria since they are based on an augmented model that is equivalent to the original system and since they require bounds for fewer terms. We apply the new bounded real criteria to state-feedback H control. The advantage of the new criteria is demonstrated by four examples. The first two compare our results with those obtained in the literature for the bounded real lemma and the other two examples treat the state-feedback control problem and compare our result with recently published designs View full abstract»

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  • A robust state observer scheme

    Publication Year: 2001 , Page(s): 1958 - 1963
    Cited by:  Papers (33)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (163 KB) |  | HTML iconHTML  

    This note proposes a new approach to robust state observer construction. The scheme is derived by including an extra term and adopting the Lyapunov stability theorem, and requires the solution of an algebraic Riccati equation. The scheme is implemented in a gas-fired furnace system example. Satisfactory results have been obtained, though in general special attention need be paid to some numerical issues in implementing the scheme View full abstract»

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  • A note on optimality conditions for continuous-time Markov decision processes with average cost criterion

    Publication Year: 2001 , Page(s): 1984 - 1989
    Cited by:  Papers (16)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (223 KB) |  | HTML iconHTML  

    This note deals with continuous-time Markov decision processes with a denumerable state space and the average cost criterion. The transition rates are allowed to be unbounded, and the action set is a Borel space. We give a new set of conditions under which the existence of optimal stationary policies is ensured by using the optimality inequality. Our results are illustrated with a controlled queueing model. Moreover, we use an example to show that our conditions do not imply the existence of a solution to the optimality equations in the previous literature View full abstract»

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  • Banded matrix fraction representation of triangular input normal pairs

    Publication Year: 2001 , Page(s): 2018 - 2022
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (192 KB) |  | HTML iconHTML  

    An input pair (A, B) is triangular input normal if and only if A is triangular and AA* + BB* = In, where In is the identity matrix. Input normal pairs generate an orthonormal basis for the impulse response. Every input pair may be transformed to a triangular input normal pair. A new system representation is given: (A, B) is triangular normal and A is a matrix fraction, A = M-1 N, where M and N are triangular matrices of low bandwidth. For single input pairs, M and N are bidiagonal and an explicit parameterization is given in terms of the eigenvalues of A. This band fraction structure allows for fast updates of state space systems and fast system identification. When A has only real eigenvalues, one state advance requires 3n multiplications for the single input case View full abstract»

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  • A case study for the open question: disturbance decoupling problem for singular systems by output feedback

    Publication Year: 2001 , Page(s): 1924 - 1930
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (224 KB)  

    We study the disturbance decoupling problem for singular systems Ex˙=Ax+Bu+Gd, y=Cx, z=Hx with left invertibility. We give necessary and sufficient conditions for the existence of a solution to the disturbance decoupling problem with or without stability by output feedback that also makes the resulting closed-loop system regular and/or of index at most one. All results are proved based on a condensed form that can be computed using orthogonal transformations, i.e., can be computed in a numerically stable way View full abstract»

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  • H strong stabilization

    Publication Year: 2001 , Page(s): 1968 - 1972
    Cited by:  Papers (37)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (150 KB) |  | HTML iconHTML  

    This note presents a technique for designing stable H controllers. Similar to some methods in the existing literature, the proposed method also uses the parameterization of all suboptimal H controllers so that the stable H design problem can be (conservatively) converted into another 2-block standard H problem. However, a weighting function is introduced in this method to alleviate the conservativeness of the previous formulations. It is further shown that the resulting high-order controller can be significantly reduced by a two-step reduction algorithm. Numerical examples are presented to demonstrate the effectiveness of the proposed method View full abstract»

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  • Asymptotic variance expressions for estimated frequency functions

    Publication Year: 2001 , Page(s): 1887 - 1899
    Cited by:  Papers (7)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (360 KB) |  | HTML iconHTML  

    Expressions for the variance of an estimated frequency function are necessary for many issues in model validation and experiment design. A general result is that a simple expression for this variance can be obtained asymptotically as the model order tends to infinity. This expression shows that the variance is inversely proportional to the signal-to-noise ratio frequency by frequency. Still, for low order models the actual variance may be quite different. We derive an exact expression for the variance, which is not asymptotic in the model order. This expression applies to a restricted class of models: AR-models, as well as fixed pole models with a polynomial noise model. It brings out the character of the simple approximation and the convergence rate to the limit as the model order increases. It also provides nonasymptotic lower bounds for the general case. The calculations are illustrated by numerical examples View full abstract»

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  • Some adaptive control problems which convert to a "classical" problem in several complex variables

    Publication Year: 2001 , Page(s): 2038 - 2043
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (231 KB) |  | HTML iconHTML  

    We discuss the equivalence of bi-H control problems to certain problems of approximation and interpolation by analytic functions in several complex variables. In bi-H control, the goal is to perform H control design for a plant where part of it is known and a stable subsystem δ is not known, i.e. the response at "frequency" s is P(s, δ(s)). We assume that once our system is running, we can identify δ online. Thus the problem is to design a function K off-line that uses this information to produce a H controller via the formula K(s, δ(s)). The controller should yield a closed loop system with H gain at most γ no matter which δ occurs. This is a frequency domain problem. The article shows how several bi-H control problems convert to two complex variable interpolation problems. These precisely generalize the classical (one complex variable) interpolation (AAK-commutant lifting) problems which lay at the core of H control. These problems are hard, but the last decade has seen substantial success on them in the operator theory community. In the most ideal of bi-H cases these lead to a necessary and sufficient treatment of the control problem View full abstract»

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  • Local observability of nonlinear differential-algebraic equations (DAEs) from the linearization along a trajectory

    Publication Year: 2001 , Page(s): 1947 - 1950
    Cited by:  Papers (4)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (128 KB) |  | HTML iconHTML  

    The main results of this note establish sufficient rank conditions for local observability of nonlinear differential-algebraic equations (DAE) systems near a known trajectory associated with a given control. Verification of the observability rank condition is addressed, and the relationship with previous work on observability of DAE is indicated View full abstract»

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  • On the consistency between an LFT described model set and frequency domain data

    Publication Year: 2001 , Page(s): 2001 - 2007
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (252 KB) |  | HTML iconHTML  

    The main objective of this technical note is to derive a simple necessary and sufficient condition for a linear fractional transformation (LFT) perturbed model set being consistent with frequency domain plant input-output data. Only discrete-time models and unstructured modeling errors are dealt with. Compared with the available results in which the eigenvalues of a matrix are involved, this condition is related only to the Euclidean norms of two vectors. Moreover, these vectors linearly depend on measurement errors. Some of its applications to model set validation have been briefly discussed. Based on this condition, an almost analytic solution has been established for model set validation under a deterministic framework when the measurement errors are energy bounded. Numerical simulations show that this consistency condition can lead to a significant computation cost reduction View full abstract»

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  • Robust stabilization of large space structures via displacement feedback

    Publication Year: 2001 , Page(s): 1993 - 1996
    Cited by:  Papers (20)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (119 KB) |  | HTML iconHTML  

    It has been known that static velocity and displacement feedback with collocated sensors and actuators can stabilize large space structures robustly against "any" uncertainty in mass, damping, and stiffness, independently of the number of flexible modes. The authors present dynamic displacement feedback which can achieve such robust stabilization. The proposed control law can be implemented in a decentralized scheme straightforwardly View full abstract»

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  • Nonlinear adaptive controller with integral action

    Publication Year: 2001 , Page(s): 2035 - 2037
    Cited by:  Papers (4)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (98 KB) |  | HTML iconHTML  

    This note reveals a new significant property of the adaptive controller design technique proposed by Krstic, Kanellakopoulos and Kokotovic (1994). Namely, it is shown that with the use of special plant model parametrization the standard backstepping design results in an adaptive controller with integral action. The latter means that the controller completely rejects constant input disturbances. It is shown that the revealed property can be extended to nonlinear and nonadaptive cases 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