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Automatic Control, IEEE Transactions on

Issue 4 • Date April 1989

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Displaying Results 1 - 22 of 22
  • Comments on the robust stability analysis of adaptive controllers using normalizations

    Publication Year: 1989 , Page(s): 478 - 479
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (177 KB)  

    Some results on robustness to unmodeled dynamics of adaptive controllers using normalization factors are analyzed. It is shown that the proofs given by various authors fail to establish that the proposed adaptive controllers provide a nonvanishing robustness margin for the class of unmodeled dynamics considered.<> View full abstract»

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  • Comments on "Discrete optimal control with eigenvalue assigned inside a circular region

    Publication Year: 1989 , Page(s): 479 - 480
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (163 KB)  

    The commenters claim that the perturbation bound for the stability of a linear optimal system derived in the paper by T.T. Lee et al. (see ibid., vol.AC-31, p.958-62 (1986)) is incorrect. The source of the error is identified and a corrected result is given. Furthermore, it is pointed out that an even more fundamental problem exists before the derivation process is started. A remedy is suggested.<> View full abstract»

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  • On optimal control law implementations for exponential performance index

    Publication Year: 1989 , Page(s): 468 - 469
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (180 KB)  

    An alternate implementation is established, under certain conditions, for previously obtained solution to the linear-exponential-Gaussian stochastic optimal control problem. The implementation allows the current control to be specified without using future values of the measurement process parameters, which are often unavailable in practice View full abstract»

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  • Instability of a decoupled Kalman tracking filter

    Publication Year: 1989 , Page(s): 469 - 471
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (248 KB)  

    The performance of a decoupled Kalman tracking filter is studied by means of a suboptimal covariance analysis. Analytical and numerical results are presented that demonstrate filter instability over a range of target-sensor line-of-sight (LOS) rates. The instability is shown to occur only when the ratio of the decoupled filter gains exceeds a specific threshold value View full abstract»

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  • An alternative proof of Kharitonov's theorem

    Publication Year: 1989 , Page(s): 448 - 450
    Cited by:  Papers (29)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (212 KB)  

    An alternative proof is presented of Kharitonov's theorem for real polynomials. The proof shows that if an unstable root exists in the interval family, then another unstable root must also show up in what is called the Kharitonov plane, which is delimited by the four Kharitonov polynomials. This fact is proved by using a simple lemma dealing with convex combinations of polynomials. Then a well-known result is utilized to prove that when the four Kharitonov polynomials are stable, the Kharitonov plane must also be stable, and this contradiction proves the theorem View full abstract»

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  • Kinematics and control of multifingered hands with rolling contact

    Publication Year: 1989 , Page(s): 398 - 404
    Cited by:  Papers (109)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (600 KB)  

    The kinematics of rolling contact are derived for two surfaces of arbitrary shape rolling on each other. The kinematic equations are applied to a multifingered hand manipulating some object of arbitrary shape in three dimensions, and a scheme is presented for the control of such a hand which is a generalization of the computed torque method of control of robot manipulators. In implementing the control, it is required that all applied forces lie within the friction cone of the object so that sliding does not occur. The theory has been validated by dynamic graphical simulations of the resulting closed-loop system for several examples View full abstract»

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  • A tracking filter for maneuvering sources

    Publication Year: 1989 , Page(s): 471 - 475
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (412 KB)  

    An adaptive filter that is based on the Pontryagin minimum principle and the method of invariant imbedding is introduced and applied to the problem of tracking maneuvering sources. The major advantages of this approach are: (1) no model for the target dynamics is required, and (2) the signal-to-noise ratio of the observation and stations need to be known. The performance of the proposed approach (with unknown system dynamics) is compared to that of the extended Kalman filter (with known system dynamics) for the maneuvering reentry vehicle. Examples are given for different target scenarios View full abstract»

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  • Robustness consideration in reduced-order controllers

    Publication Year: 1989 , Page(s): 457 - 459
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (340 KB)  

    The problem of robustness in the design of restricted complexity controllers is addressed. Starting from a full-order regulator, robustness considerations are incorporated into the controller reduction problem in order to produce an priori bound over the admissible degrees of approximation between the high-order and the low-order controllers. An example application is given to show the usefulness of the proposed methodology View full abstract»

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  • Stability of x(t)=Ax(t)+Bx (t-τ)

    Publication Year: 1989 , Page(s): 460 - 462
    Cited by:  Papers (55)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (236 KB)  

    A stability criterion for linear time-delay systems described by a differential difference equation of the form dx(t)=Ax(t)+Bx(t -τ) is proposed. The result obtained includes information on the size of the delay and therefore can be a delay-dependent stability condition. Its relation to existing delay-independent stability criteria is also discussed View full abstract»

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  • Adaptive regulation of nonlinear systems with unmodeled dynamics

    Publication Year: 1989 , Page(s): 405 - 412
    Cited by:  Papers (145)  |  Patents (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (732 KB)  

    A feedback linearization design is presented which includes unknown parameters and unmodeled dynamics. An adaptive update law which counteracts the effects of unknown parameters is shown to be robust to the unmodeled dynamics. The proposed design methodology is based on a conceptually simple stability analysis. Conditions are given for global stability of an adaptive control law designed for the reduced-order model of a class of nonlinear plants. In the presence of unmodeled dynamics, the regulation property is preserved in a stability region. The size of the region is estimated using bounds that not only prove robustness, but also allow a comparison between adaptive and nonadaptive nonlinear controls View full abstract»

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  • Admissible additive perturbations

    Publication Year: 1989 , Page(s): 476 - 478
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (220 KB)  

    For the general feedback system with two-input, two-output plant and compensator, the class of all admissible additive perturbations of the plant which do not destabilize the closed loop is established View full abstract»

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  • On the determination of the zeros of a SISO system

    Publication Year: 1989 , Page(s): 475 - 476
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (148 KB)  

    A formula to find the zeros of a SISO (single-input-single-output) system, as eigenvalues of a certain matrix M, from state-space description is presented. Since the numerical computation of eigenvalues can be very accurate, the formula provides a way to determine accurately the zeros of a high-order SISO system View full abstract»

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  • Smooth stabilization implies coprime factorization

    Publication Year: 1989 , Page(s): 435 - 443
    Cited by:  Papers (558)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (736 KB)  

    It is shown that coprime right factorizations exist for the input-to-state mapping of a continuous-time nonlinear system provided that the smooth feedback stabilization problem is solvable for this system. It follows that feedback linearizable systems admit such fabrications. In order to establish the result, a Lyapunov-theoretic definition is proposed for bounded-input-bounded-output stability. The notion of stability studied in the state-space nonlinear control literature is related to a notion of stability under bounded control perturbations analogous to those studied in operator-theoretic approaches to systems; in particular it is proved that smooth stabilization implies smooth input-to-state stabilization View full abstract»

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  • Decentralized adaptive control: structural conditions for stability

    Publication Year: 1989 , Page(s): 413 - 426
    Cited by:  Papers (134)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (940 KB)  

    Decentralized adaptive control schemes are presented for a class of large-scale interconnected systems. These schemes have the advantage that in addition to the standard assumption about the uncertainty of the subsystems, the strength of interconnection is assumed unknown. Provided certain structural constraints are satisfied, the adaptation gains automatically adjust to levels that assure stability of the overall system. Simulations of a spring-coupled dual pendulum showed that for high interconnection strengths, the proposed algorithm exhibits better tracking performance than existing algorithms View full abstract»

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  • Stability of fast periodic systems with time lags

    Publication Year: 1989 , Page(s): 462 - 465
    Cited by:  Papers (4)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (316 KB)  

    The stability criterion of R. Bellman et al. (1985) for fast periodic linear systems is extended to systems with time delays. Applying the results of J. Hale (1966), the asymptotic stability criterion for a class of time-lag systems is derived. A comparison to a nondelay case is made, and it is demonstrated that small delays can significantly affect the stability properties of this class of systems View full abstract»

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  • Balancing transformations for unstable nonminimal linear systems

    Publication Year: 1989 , Page(s): 455 - 457
    Cited by:  Papers (10)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (316 KB)  

    It is shown that an unstable nonminimal continuous (discrete) realization (A, B, C) can be transformed via a similarity transformation into a balanced one if and only if the product of the controllability, observability Gramians is similar to a real diagonal matrix Λ. If, in addition, the eigenvalues of A , say λ, satisfy the relation λij≠0(λiλj≠1) then the matrix Λ will always be positive semidefinite, and a balanced realization with its minimal part in the internally balanced form can always be obtained View full abstract»

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  • Frequency response algorithms for H optimization with time domain constraints

    Publication Year: 1989 , Page(s): 427 - 434
    Cited by:  Papers (22)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (808 KB)  

    A very broad framework for control system design is considered that encompasses frequency-response methodologies for H optimization that solve various aspects of the control design problem and that are less well known that state-space methods. The focus is on linear programming, Lawson's algorithm, and Trefethen's algorithm. A modified Lawson's algorithm is proposed and related to Trefethan's method. The modified algorithm is shown to be significantly faster than linear programming and Lawson's algorithm. It is also shown how to extend the modified Lawson's algorithm so as to handle time-domain constraints in addition to frequency-domain specifications, which distinguishes it from other H optimization methods. Some steps are taken toward dealing with time domain constraints within an H optimization framework View full abstract»

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  • A control-oriented model for cylinder pressure in internal combustion engines

    Publication Year: 1989 , Page(s): 386 - 397
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1076 KB)  

    The cylinder-pressure modeling problem is formulated and a perturbation solution is presented. Control-oriented perturbation models (COPMs) for cylinder pressure in spark-ignited internation combustion engines are novel in that the smallest regions of realistic interest already include nonlinear effects which may be neglected, so linear perturbation is not adequate. Moreover, the crank angle frame of reference leads to a perturbation on the independent variable as well. These features require higher order local representations of vector-valued functions of several vector-valued variables, in a form suitable for computation. A COPM for cylinder pressure in a 1.8-L Opel Family II engine, with inputs of spark advance and air-fuel ratio, demonstrates that increased accuracy and consistency result from the increasing model degree made possible with these models View full abstract»

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  • Geometric structure and feedback in singular systems

    Publication Year: 1989 , Page(s): 450 - 455
    Cited by:  Papers (11)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (480 KB)  

    The output-nulling (A, E, R(B))-invariant subspaces are defined for singular systems, rigorously justifying the name and demonstrating that special cases of these geometric objects are the familiar subspace of admissible conditions and the supremal (A, E, R(B ))-invariant subspace. A novel singular-system-structure algorithm is used to compute them by numerically efficient means. Their importance for describing the possible closed-loop geometric structure in terms of the open-loop geometric structure is shown. An approach to spectrum assignment in singular systems that is based on a generalized Lyapunov equation is introduced. The equation is used to compute feedback gains to place poles and assign various closed-loop invariant subspaces while guaranteeing closed-loop regularity View full abstract»

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  • A fast algorithm for the division of two polynomial matrices

    Publication Year: 1989 , Page(s): 446 - 448
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (224 KB)  

    A modification of the algorithm shown by Q.G. Wang and C.H. Zhou (see ibid., vol.AC-31, p.165-6, 1968) is presented. The performance of their algorithm is improved by the use of convolutions and therefore of FFT techniques. The present method is based on the fast inversion of block triangular Toeplitz matrices, and it is amenable to parallel implementation View full abstract»

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  • Multifrequency Pade approximation via Jordan continued-fraction expansion

    Publication Year: 1989 , Page(s): 444 - 446
    Cited by:  Papers (9)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (188 KB)  

    The multifrequency Pade approximation of transfer functions is performed via the Jordan-type continued-fraction expansion. An efficient algorithm that requires no complex algebra is derived for expanding a transfer function into a Jordan continued fraction about arbitrary points sjωj on the imaginary axis of the s-plane. Also derived is a forward inversion algorithm for inverting a multifrequency Jordan continued-fraction expansion into a rational form. The algorithms presented are amenable for obtaining a family of frequency-response matched models of different orders for a high-order transfer function via a single set of computations View full abstract»

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  • The recursive algorithm for the optimal static output feedback control problem of linear singularity perturbed systems

    Publication Year: 1989 , Page(s): 465 - 468
    Cited by:  Papers (6)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (324 KB)  

    A recursive algorithm is developed for solving the algebraic equations comprising the solution of the optimal static output feedback control problem of singularly perturbed linear systems. The algorithm is very efficient from the numerical point of view, since only low-order systems are involved in algebraic calculations and the required solution can be easily obtained up to an arbitrary order of accuracy, that is O(εk) where ε is a small perturbation parameter. The real-world example demonstrates the failure of O(ε) theory used so far in the study of this problem and the necessity for the existence of O(εk) theory 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