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Automatic Control, IEEE Transactions on

Issue 5 • Date May 1993

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Displaying Results 1 - 25 of 26
  • Comments on "Observability of discrete event dynamic systems" by C. M. Ozveren and A.S. Willsky

    Publication Year: 1993
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (104 KB)  

    It is pointed out that the algorithm introduced in the above-titled work (see ibid., vol.35, no.7, p.797-806, July 1990) to compute the maximal set of indistinguishable state pairs is incorrect under the given definition of the automation O/sub p/. It is suggested that to remove the difficulty, either the definition of O/sub p/ or the algorithm itself should be modified.<> View full abstract»

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  • Comments on "Conditions for stable zeros of sampled systems" by M. Ishitobi

    Publication Year: 1993 , Page(s): 830 - 831
    Cited by:  Papers (5)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (186 KB)  

    The commenter argues that the result of the above-titled work (see ibid., vol.37, no.10, p.1558-1561, Oct. 1992) is incorrect. It is pointed out that when sampling a continuous-time system G(s) using zero-order hold, the zeros of the resulting discrete-time system H(z) become complicated functions of the sampling interval T. The system G(s) has unstable continuous-time zeros, s=0.1+or-i. The zeros of the corresponding sampled system start for small T from a double zero at z=1 as exp(T(0.1+or-i)), i.e., on the unstable side. For T>1.067 . . . the zeros become stable. The criterion function of the above-titled work, F(T)=G*(j omega /sub s//2)=H(-1)T/2, is, however, positive for all T, indicating only stable zeros. The zero-locus crosses the unit circle at complex values.<> View full abstract»

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  • Comments, with reply, on "Optimal rejection of persistent disturbances, robust stability, and mixed sensitivity minimization" by M. A. Dahleh and J. B. Pearson

    Publication Year: 1993
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (99 KB)  

    The commenters point out that the sufficient condition for robust stability given in the above-titled work (see ibid., vol.33, no.8, p.722-731, Aug. 1988) should be modified. In their reply, the authors agree with the commenters and describe the assumptions which led to the omission.<> View full abstract»

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  • Identification of ARX-models subject to missing data

    Publication Year: 1993 , Page(s): 813 - 819
    Cited by:  Papers (28)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (556 KB)  

    Parameter estimation when the measurement information may be incomplete is discussed. An ARX model is used as a basic system representation. The presentation covers both missing output and missing input. First reconstruction of the missing values is discussed. The reconstruction is based on a state-space formulation of the system, and is performed using Kalman filtering or fixed-interval smoothing formulas. Several approaches to the identification problem are presented, including a new method based on the EM (expectation maximization) algorithm. The different approaches are tested and compared using Monte Carlo simulations. The choice of method is always a tradeoff between estimation accuracy and computational complexity. According to the simulations the gain in accuracy using the EM method can be considerable if many data are missing View full abstract»

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  • Optimal stochastic control for performance- and stability-robustness

    Publication Year: 1993 , Page(s): 757 - 760
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (368 KB)  

    A design method for discrete-time control systems that maintain stability with minimum performance degradation in the presence of a variety of deterministic and stochastic perturbation/disturbances is presented. Deterministic perturbation and modeling errors are represented by maximum deviations from a nominal linear discrete-time system, and stochastic perturbations are modeled by generalization of the sector-bound nonlinearity concept to the stochastic case. Based on the given bounds on deterministic and stochastic perturbations an upper bound on the quadratic performance index, which is useful in assessing the performance deterioration according to the feedback gain used, is found. Then the optimal feedback gain which minimizes this bound on the performance index is derived. In the time-invariant case the existence of a stabilizing property of the bound-optimal controller, which is obtained by minimizing an average cost per stage, is shown View full abstract»

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  • Nonholonomic motion planning: steering using sinusoids

    Publication Year: 1993 , Page(s): 700 - 716
    Cited by:  Papers (482)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1356 KB)  

    Methods for steering systems with nonholonomic c·onstraints between arbitrary configurations are investigated. Suboptimal trajectories are derived for systems that are not in canonical form. Systems in which it takes more than one level of bracketing to achieve controllability are considered. The trajectories use sinusoids at integrally related frequencies to achieve motion at a given bracketing level. A class of systems that can be steered using sinusoids (claimed systems) is defined. Conditions under which a class of two-input systems can be converted into this form are given View full abstract»

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  • One-step extension approach to optimal Hankel-norm approximation and H-optimization problems

    Publication Year: 1993 , Page(s): 674 - 688
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (968 KB)  

    A methodology is presented for Hankel approximation and H -optimization problems that is based on a new formulation of a one-step extension problem which is solved by the Sarason interpolation theorem. The parameterization of all optimal Hankel approximants for multivariable systems is given in terms of the eigenvalue decomposition of an Hermitian matrix composed directly from the coefficients of a given transfer function matrix φ. Rather than starting with the state-space realization of φ, the authors use polynomial coefficients of φ as input data. In terms of these data, a natural basis is given for the finite dimensional Sarason model space and all computations involve only manipulations with finite matrices View full abstract»

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  • A stable indirect adaptive control scheme for first-order plants with no prior knowledge on the parameters

    Publication Year: 1993 , Page(s): 766 - 770
    Cited by:  Papers (8)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (504 KB)  

    An indirect adaptive control scheme for a first-order linear time-invariant plant with unknown parameters is presented and analyzed. The scheme requires a priori knowledge of the sign or bounds of the plant parameters. A discontinuous control law, involving the use of probing, is utilized to avoid any singularities caused by the lack of stabilizability of the estimated model. The scheme guarantees signal boundedness and zero residual tracking error View full abstract»

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  • Stabilization via static output feedback

    Publication Year: 1993 , Page(s): 764 - 765
    Cited by:  Papers (43)
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    Necessary and sufficient conditions for the existence of a stabilizing static output feedback gain matrix are presented. It is shown that any such gain matrix is the solution of some linear quadratic control problem where the cost functional has a suitable cross term View full abstract»

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  • An algorithm computing the general entry of the nth Kronecker power of a matrix

    Publication Year: 1993 , Page(s): 828 - 830
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (208 KB)  

    The number of distinct entries among the m2n entries of the nth Kronecker power of an m×m matrix is derived. An algorithm to find the value of each entry of the Kronecker power is presented View full abstract»

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  • Optimization based job shop scheduling

    Publication Year: 1993 , Page(s): 808 - 813
    Cited by:  Papers (3)  |  Patents (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (640 KB)  

    A generalized job shop scheduling problem is defined in detail. The proposed factory description is sufficiently realistic to model the routing and sequencing decisions made in a real manufacturing plant. An optimization problem is posed, permitting the use of very general cost functions. A variation of the method of simulated annealing is proposed as a tool for the solution of the optimization problem. A novel technique for embedding the space of feasible schedules into a permutation group is used to define a neighborhood structure for the simulated annealing process. This technique has algorithmic advantages over working directly in the space of schedules. These ideas were used in the design and implementative of a scheduling software system. A brief description of the software system, called ABES for Annealing Based Experiment in Scheduling, and comments on its effectiveness are presented View full abstract»

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  • Least squares methods for H control-oriented system identification

    Publication Year: 1993 , Page(s): 819 - 826
    Cited by:  Papers (14)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (716 KB)  

    A series of system identification algorithms that yield identified models which are compatible with current robust controller design methodologies is presented. These algorithms are applicable to a broad class of stable, distributed, linear, shift-invariant plants. The a priori information necessary for their application consists of a lower bound on the relative stability of the unknown plant, an upper bound on a certain gain associated with the unknown plant, and an upper bound on the noise level. The a posteriori data information consists of a finite number of corrugated point frequency response estimates of the unknown plant. The extent to which certain standard Hilbert-space or least-squares method are applicable to the H system identification problem considered is examined. Results are established that connect the H2 error of the least-squares methods to the H error needed for control-oriented system identification View full abstract»

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  • A system-theoretic appropriate realization of the empty matrix concept

    Publication Year: 1993 , Page(s): 771 - 775
    Cited by:  Papers (4)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (432 KB)  

    An algebraic realization of the empty matrix concept that is appropriate for system-theoretic applications is proposed. The utility of the realization of the empty matrix concept and the deficiencies of the current MATLAB realization of this concept are demonstrated using examples. These examples fully delineate how the empty matrix concept can be utilized to transparently handle static and for single-vector-input, single-vector-output systems within the more general context of dynamic, two-vector-input, two-vector-output systems View full abstract»

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  • Repeatable generalized inverse control strategies for kinematically redundant manipulators

    Publication Year: 1993 , Page(s): 689 - 699
    Cited by:  Papers (13)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (856 KB)  

    The issue of generating a repeatable control strategy which possesses the desirable physical properties of a particular generalized inverse is addressed. The technique described is fully general and only requires a knowledge of the associated mill space of the desired inverse. While an analytical representation of the null vector is desirable, ultimately the calculations are done numerically so that a numerical knowledge of the associated full vector is sufficient. This method first characterizes repeatable strategies using a set of orthonormal basis functions to describe the null space of these transformations. The optimal repeatable inverse is then obtained by projecting the null space of the desired generalized inverse onto each of these basis functions. The resulting inverse is guaranteed to be the closest repeatable inverse to the desired inverse, in an integral norm sense, from the set of all inverses spanned by the selected basis functions. This technique is illustrated for a planar, three-degree-of-freedom manipulator and a seven-degree-of-freedom spatial manipulator View full abstract»

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  • Minimization of the L-induced norm for sampled-data systems

    Publication Year: 1993
    Cited by:  Papers (12)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1200 KB)  

    It is shown that given any degree of accuracy, there exists a standard discrete-time l1 problem that can be determined a priori whose solution yields a controller that is almost optimal in terms of the hybrid L-induced norm. This is accomplished by first converting the hybrid system into an equivalent infinite-dimensional discrete-time system using the lifting technique in continuous time, and then approximating the infinite-dimensional parts of the system which model the intersample dynamics. A thorough analysis of the approximation procedure is presented, and it is shown that it is convergent at the rate of 1/n . Explicit bounds that are independent of the controller are obtained to characterize the approximation. It is also shown that the geometry of the induced norm for the sampled-data problem is different from that of the standard l1 norm, and hence there might not exist a linear isometry that maps the sampled-data problem exactly to a standard discrete-time problem View full abstract»

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  • To stabilize an interval plant family it suffices to simultaneously stabilize sixty-four polynomials

    Publication Year: 1993 , Page(s): 760 - 764
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (444 KB)  

    It is shown that stability of three specific polynomial families can be deduced from the stability of a finite number of polynomials. These polynomial families are the characteristic polynomials of unity feedback loops with the controller in the forward path, and where the plant includes a specific form of parameter uncertainty. For the first polynomial family, the plant has parameter uncertainty in the even or odd terms of the numerator or denominator polynomial. For the second polynomial family the plant has a numerator or denominator which is an interval polynomial. For the third polynomial family, the plant is interval. Because of the structure of these results it is shown that they lead to robust stabilization results. Two examples are included. The approach employed here was developed for plants with affine uncertainty. It is demonstrated that considerable simplification results if the plants under investigation are interval View full abstract»

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  • Necessary and sufficient conditions of stability: a multiloop generalization of the circle criterion

    Publication Year: 1993 , Page(s): 753 - 756
    Cited by:  Papers (33)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (292 KB)  

    A linear time-invariant system with a vector output and a vector input is described. This system is closed by an uncertain (nonlinear, time-varying) feedback. The only information on this feedback is given by several integral quadratic inequalities, i.e. the uncertainties under consideration generalize the so-called conic nonlinearities. Necessary and sufficient frequency-domain conditions of stability are obtained. An advanced version of the S-procedure losslessness theorem and some other tools of the absolute stability theory are used View full abstract»

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  • Comparative study of finite wordlength effects in shift and delta operator parameterizations

    Publication Year: 1993 , Page(s): 803 - 807
    Cited by:  Papers (30)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (428 KB)  

    The sensitivity of the transfer function to finite-wordlength-effect errors in the implementation of the coefficients of both shift operator and delta operator parameterizations is analyzed. The relationships between optimal realization sets in shift and delta operator are established. It is shown that the optimal realization in delta operator parameterizations have better performance than those in their shift operator counterparts when the poles of the systems are clustered around z=+1. A numerical example is given View full abstract»

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  • Computational observer design techniques for linear systems with unknown inputs using the concept of transmission zeros

    Publication Year: 1993 , Page(s): 790 - 794
    Cited by:  Papers (9)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (404 KB)  

    Computational observer design techniques for linear systems subject to unknown inputs are presented. Complete and intuitive geometric conditions for the solution of the problem which result in design matrix equations are provided. These design equations are solved in a computationally efficient way. The synthesis of the reduced-order observer takes full advantage of the concept of transmission zeros. In particular, the necessary and sufficient conditions obtained are given in terms of the transmission zeros of the triple (A,D, C) View full abstract»

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  • Robust stability and performance via fixed-order dynamic compensation: the discrete-time case

    Publication Year: 1993 , Page(s): 776 - 782
    Cited by:  Papers (7)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (564 KB)  

    A discrete-time feedback-control-design problem involving parametric uncertainty is considered. A quadratic bound suggested by recent work on discrete-time state-space H theory is utilized in conjunction with the guaranteed cost approach to guarantee robust stability with a robust performance bound. The principal result involves sufficient conditions for characterizing robust full- and reduced-order controllers with a worst case H 1 performance bound View full abstract»

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  • Systems with structured uncertainty: relations between quadratic and robust stability

    Publication Year: 1993 , Page(s): 799 - 803
    Cited by:  Papers (18)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (484 KB)  

    The relation between the notions of robust stability and quadratic stability for uncertain systems with structured uncertainty due to both real and complex parameter variations is discussed. Examples are presented to demonstrate that for systems containing at least two uncertain blocks, the notions of robust stability for complex parameter variations and quadratic stability for real parameter variations are not equivalent. A byproduct of these examples is that, for this class of systems, quadratic stability for real perturbations need not imply quadratic stability for complex perturbations. This is in stark contrast with the situation in the case of unstructured uncertainty, for which it is known that quadratic stability for either real or complex perturbations is equivalent to robust stability for complex perturbations, and thus equivalent to a small gain condition on the transfer matrix that the perturbation experiences View full abstract»

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  • Computations of limit cycles via higher-order harmonic balance approximation

    Publication Year: 1993 , Page(s): 782 - 790
    Cited by:  Papers (6)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (668 KB)  

    The detection of limit cycles arising from Hopf bifurcation phenomena by applying the harmonic balance method with different higher-order approximations is discussed. The results are presented using a graphical procedure that indicates clearly how the predictions of amplitude and frequency of a periodic solution can be improved by using higher and higher order approximations. Complete and explicit formulas for eighth-order harmonic balance approximation are provided View full abstract»

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  • Duality theory for MIMO robust disturbance rejection

    Publication Year: 1993 , Page(s): 743 - 752
    Cited by:  Papers (21)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (728 KB)  

    Banach space duality theory is used to characterize the solutions of a nonstandard H optimization problem which is shown to be allpass in general and unique in the single-input single-output (SISO) ease. The theory leads to a numerical solution of duality and convex optimization, which is applied to an example. For a limiting case of sharp cutoff filters, an explicit solution of the optimal robust disturbance attenuation problem (ORDAP) resembling the two arc theorem of complex analysis is derived View full abstract»

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  • A stochastic estimation algorithm with observation averaging

    Publication Year: 1993 , Page(s): 794 - 798
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (392 KB)  

    An algorithm for the constrained problem of estimating the regression coefficients is presented. The algorithm is based on the idea of direct averaging of the observations in order to estimate the search direction. It is shown that if the true parameter belongs to the permitted set, then the algorithm delivers asymptotically optimal estimates of the parameter. Finite convergence of the method is proved when the true parameter lies outside the permitted set View full abstract»

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  • Relative sufficiency

    Publication Year: 1993 , Page(s): 826 - 828
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (260 KB)  

    By the classical definition of a sufficient statistic, either a statistic is or is not sufficient. A measure called relative sufficiency, by which the degree of sufficiency can be defined for the problem of random parameter estimation is presented. It is shown that relative sufficiency is equivalent to the Kullback-Leibler information measure. Its calculation and interpretation are illustrated for the estimation of a scalar random variable 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