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Automatic Control, IEEE Transactions on

Issue 9 • Date Sept. 1992

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Displaying Results 1 - 25 of 31
  • Comments on "Stability analysis of a family of matrices" by Y.K. Foo and Y.C. Soh

    Publication Year: 1992 , Page(s): 1470 - 1472
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (136 KB)  

    The robust stability problem of a convex hull of a finite number of matrices was treated in the above-titled paper by Y.K. Foo and Y.C. Soh (ibid., vol.35, no.11, p.1257-9, Nov. 1990), and a sufficient condition was presented. The commenters give another sufficient condition and show, using an example, that their condition can be less conservative than the result. They also give a necessary and sufficient condition for the robust stability problems treated by Foo and Soh.<> View full abstract»

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  • Fractal system as represented by singularity function

    Publication Year: 1992 , Page(s): 1465 - 1470
    Cited by:  Papers (96)  |  Patents (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (376 KB)  

    A fractional slope on the log log Bode plot has been observed in characterizing a certain type of physical phenomenon and has been called the fractal system or the fractional power pole. In order to represent and study its dynamical behavior, a singularity function method is presented which consists of cascaded branches of a number of pole-zero (negative real) pairs or simple RC section. The distribution spectrum of the system can also be easily calculated, and its accuracy depends on a prescribed error specified in the beginning. The method is then extended to a multiple-fractal system which consists of a number of fractional power poles. The result can be simulated by a combination of singularity functions, each representing a single-fractal system View full abstract»

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  • The exact slow-fast decomposition of the algebraic Ricatti equation of singularly perturbed systems

    Publication Year: 1992 , Page(s): 1456 - 1459
    Cited by:  Papers (15)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (264 KB)  

    The algebraic Riccati equation for singularly perturbed control systems is completely and exactly decomposed into two reduced-order algebraic Riccati equations corresponding to the slow and fast time scales. The pure-slow and pure-fast algebraic Riccati equations are asymmetric ones, but their O(ε) perturbations are symmetric. It is shown that the Newton method is very efficient for solving the obtained asymmetric algebraic Riccati equations. The method presented is very suitable for parallel computations. Due to the complete and exact decomposition of the Riccati equation, this procedure might produce new insight into the two-time-scale optimal filtering and control problems View full abstract»

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  • An extreme point result of robust stability of a diamond of polynomials

    Publication Year: 1992 , Page(s): 1460 - 1462
    Cited by:  Papers (17)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (256 KB)  

    It is shown that a family of polynomials with real coefficients lying in a diamond is Hurwitz if and only if eight distinguished extreme polynomials are Hurwitz. For the case of complex coefficients, it is shown by a counterexample that no analogous extreme point result holds View full abstract»

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  • Optimal controllers for finite wordlength implementation

    Publication Year: 1992 , Page(s): 1294 - 1304
    Cited by:  Papers (32)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (880 KB)  

    When a controller is implemented by a digital computer with A/D and D/A conversion, numerical errors can severely affect the performance of the control system. There exist realizations of a given controller transfer function exhibiting arbitrarily large effects from computational errors. Assuming sufficient excitation of the system, the problem of designing an optimal controller in the presence of both external disturbances and internal roundoff errors is solved. The results reduce to the standard LQG controller when infinite-precision computation is used. For finite precision, however, the separation principle does not hold. A penalty is also added to the cost function to penalize the sum of the wordlengths used to compute the fractional part of each state variable of the controller. This sum can be used to represent the lower bound on computer memory needed for controller synthesis. It measures controller complexity and is minimized (penalized) here View full abstract»

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  • The solution of a partially observed stochastic optimal control problem in terms of predicted miss

    Publication Year: 1992 , Page(s): 1462 - 1464
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (220 KB)  

    The explicit solution of a partially observed LQ problem driven by a combination of a Wiener process and an unobserved finite-state jump Markov process is given. Applications of the model include guidance problems, where the jump Markov process models evasive maneuvers (acceleration values) of the target, or systems subject to a sequence of failures that can be modeled by a jump Markov process View full abstract»

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  • An improved result on the stability analysis of nonlinear systems

    Publication Year: 1992 , Page(s): 1425 - 1431
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (572 KB)  

    An improved approach for stability analysis of nonlinear systems that works when traditional methods do not is proposed. The complex, possibly higher-dimensional nonlinear system is viewed as being composed of several isolated but interconnected subsystems. The proposed approach divides the complicated stability analysis job into two simpler jobs: analyzing the stability of each isolated subsystem and studying the properties of the interconnections. It is assumed that the interconnections can be bounded by a function of the norm of the state variables. This allows for more general interconnections than other approaches. Examples and computer simulations show that the approach can give results even when the problem is not tractable by other standard techniques. The method is applied to mobile robots View full abstract»

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  • Optimal routing and buffer allocation for a class of finite capacity queueing systems

    Publication Year: 1992 , Page(s): 1446 - 1451
    Cited by:  Papers (10)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (588 KB)  

    The problem of routing jobs to K parallel queues with identical exponential servers and unequal finite buffer capacities is considered. Routing decisions are taken by a controller which has buffering space available to it and may delay routing of a customer to a queue. Using ideas from weak majorization, it is shown that the shorter nonfull queue delayed (SNQD) policy minimizes both the total number of customers in the system at any time and the number of customers that are rejected by that time. The SNQD policy always delays routing decisions as long as all servers are busy. Only when all the buffers at the controller are occupied is a customer routed to the queue with the shortest queue length that is not at capacity. Moreover, it is shown that, if a fixed number of buffers is to be distributed among the K queues, then the optimal allocation scheme is the one in which the difference between the maximum and minimum queue capacities is minimized, i.e. becomes either 0 or 1 View full abstract»

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  • An approximation method for the nonlinear servomechanism problem

    Publication Year: 1992 , Page(s): 1395 - 1398
    Cited by:  Papers (58)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (300 KB)  

    An analysis of the nonlinear servomechanism problem by the authors (1992) is shown to lead naturally to a straightforward and practical method for solving the problem in an approximate sense. The results are based on a kth-order approximate solution for the plant zero-error manifold, and corresponding control law constructions are shown to yield kth-order asymptotic tracking and disturbance rejection properties for the closed-loop system. The approach is illustrated by application to the ball and beam system View full abstract»

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  • Kalman filtering and Riccati equations for descriptor systems

    Publication Year: 1992 , Page(s): 1325 - 1342
    Cited by:  Papers (66)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1340 KB)  

    A general formulation of a discrete-time filtering problem for descriptor systems is considered. It is shown that the nature of descriptor systems leads directly to the need to examine singular estimation problems. Using a dual approach to estimation, the authors derive a so-called 3-block form for the optimal filter and a corresponding 3-block Riccati equation for a general class of time-varying descriptor models which need not represent a well-posed system in that the dynamics may be either over or under constrained. Specializing in the time-invariant case, they examine the asymptotic properties of the 3-block filter, and in particular analyze in detail the resulting 3-block algebraic Riccati equation. The noncausal nature of discrete-time descriptor dynamics implies that future dynamics may provide some information about the present state. A modified form for the descriptor Kalman filter that takes this information into account is presented View full abstract»

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  • Applications of hysteresis switching in parameter adaptive control

    Publication Year: 1992 , Page(s): 1343 - 1354
    Cited by:  Papers (111)  |  Patents (9)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (984 KB)  

    The hysteresis switching algorithm of R.H. Middleton et al. (ibid., vol.33, no.1, p.50-8, Jan. 1988) is reexamined in a broader context. To demonstrate its utility, the algorithm is applied to various families of identifier-based parameterized controllers of both the direct and indirect control types. Application to the direct control type results in a model reference adaptive controller capable of stabilizing, without excitation, any SISO process which can be modeled by a minimum phase linear system whose transfer function has relative and McMillan degrees not exceeding prescribing integers m and n, respectively. It is shown that such processes can also be adaptively stabilized with indirect adaptive controllers and hysteresis switching. A simple numerical example involving a non-minimum-phase process model is used to illustrate how hysteresis switching might be applied to implicitly tuned parameterized controllers to realize an adaptive controller with capabilities which might prove very difficult, if not impossible, to achieve without hysteresis switching or some other form of discontinuous control View full abstract»

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  • A two-player game model of power cogeneration in New England

    Publication Year: 1992 , Page(s): 1451 - 1456
    Cited by:  Papers (11)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (596 KB)  

    The interaction between a utility company and electricity cogenerators is modeled via a game-theoretic, systems analysis approach, under the assumption of asymmetric pricing of electricity purchased or sold by the cogenerators. The pricing scheme is derived from the PURPA legislation prevailing in the US and is compared to an efficient operation of the global system. An adaptation of a successive approximation algorithm is developed and applied to the case of New England. The results are presented for three scenarios which simulate the status quo, the PURPA situation, and the ideal cooperative optimum View full abstract»

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  • On conditions guaranteeing two polynomial matrices possess identical zero structures

    Publication Year: 1992 , Page(s): 1383 - 1386
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (392 KB)  

    Some sufficient conditions for two polynomial matrices to simultaneously possess identical finite and infinite zero structures are developed. A special case of this problem, that of obtaining conditions under which a polynomial matrix has no infinite zeros, is also considered and certain connections with previous work are established View full abstract»

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  • Robust control of a class of nonlinear uncertain systems

    Publication Year: 1992 , Page(s): 1437 - 1442
    Cited by:  Papers (13)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (436 KB)  

    Robust control of a general class of uncertain nonlinear systems is investigated. The class of nonlinear systems includes many physical systems as special cases and has an important feature that the uncertainties in the system do not satisfy the matching conditions. Several robust control laws are proposed to make the system stable in the sense of either asymptotic stability or uniformly ultimately bounded stability. The results require no knowledge about the structure of the uncertainties. Although the uncertainties are assumed to be bounded in the Euclidean norm by a polynomial-type bounding function, there is no size restriction imposed on the bounding functions of the uncertainties. The extension to the trajectory tracking problem is also discussed View full abstract»

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  • Robustness bounds for LQ regulators

    Publication Year: 1992 , Page(s): 1373 - 1377
    Cited by:  Papers (4)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (456 KB)  

    A robustification procedure for LQ state feedback design is presented. Such a procedure consists of choosing the state and input weighting matrices according to the kind of uncertainties on the system. Both structured and norm-bounded additive uncertainties are addressed, and upper bounds for the uncertainties that do not destabilize the closed-loop system are presented. Connections with the quadratic stabilizability problem are established View full abstract»

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  • Cost translation and a lifting approach to the multirate LQG problem

    Publication Year: 1992 , Page(s): 1411 - 1415
    Cited by:  Papers (15)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (416 KB)  

    It is shown how to translate an instance of a multirate sampled-data LQG problem into an equivalent, modified, single-rate, shift-invariant problem via a lifting isomorphism approach. Using this approach, one can solve the multirate LQG problem without using periodic system theory or solving periodic Riccati equations and without suffering any increases in state dimension. This translation procedure shows the correct way to translate RMS noise specification to the lifted domain for a multirate Q-design computer-aided-design package View full abstract»

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  • Robust adaptive systems and self stabilization

    Publication Year: 1992 , Page(s): 1355 - 1369
    Cited by:  Papers (8)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1068 KB)  

    A methodology for the global stability analysis and, consequently, for the design of robust deterministic and stochastic adaptive control, filtering, and prediction is introduced. The methodology represents a mathematical formalization of the self-stabilization mechanism which is a natural characteristic of every properly designed adaptive system. The underlying idea is the construction of a suitable Lyapunov function for different periods of adaptation. The effectiveness of the proposed approach is demonstrated by solving the robust deterministic and stochastic adaptive control problems. It is shown that very small algorithm gains may produce very large signals in the adaptive loop, which are unacceptable for practical applications. The intensity of the admissible unmodeled dynamics does not depend on the algorithm gain, and it is specified in terms of the corresponding H norm. In order to establish goal stability, persistency exciting conditions are not required in the present results View full abstract»

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  • A new algorithm for finite spectrum assignment of single-input systems with time delay

    Publication Year: 1992 , Page(s): 1377 - 1383
    Cited by:  Papers (11)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (448 KB)  

    Finite spectrum assignment for time-delay systems is the elimination of delay operators from the characteristic function of the closed-loop system and the arbitrary assignment of poles. The control consists of polynomials in the delay operator and finite Laplace transforms. An algorithm for computing the control matrix is presented. In particular, the control matrix over rational functions of a delay operator is computed and expanded to partial fractions. Partial fractions are systematically transformed to finite Laplace transforms View full abstract»

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  • Disturbance attenuation and H-control via measurement feedback in nonlinear systems

    Publication Year: 1992 , Page(s): 1283 - 1293
    Cited by:  Papers (257)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (836 KB)  

    A solution to the problem of disturbance attenuation via measurement feedback with internal stability is presented for an affine nonlinear system. It is shown that the concept of disturbance attenuation, in the sense of truncated L2 norms, can be given an interpretation in terms of the response to periodic inputs in the sense of RMS amplitude, even in the nonlinear setup. In the case of state feedback, a family of controllers is also provided. The proofs of all these results are simple and provide deeper insight even in the analysis of the corresponding linear control problem View full abstract»

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  • Static realization of dynamic precompensators

    Publication Year: 1992 , Page(s): 1391 - 1394
    Cited by:  Papers (6)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (340 KB)  

    The problem of static realization of dynamic precompensators on a controllable pair (A,B) is considered. Necessary and sufficient conditions for the solution of this problem in the general case are given. These conditions are constructive, and they apply not only to invertible precompensators but also to those which are only left invertible View full abstract»

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  • Algorithms for singularly perturbed limiting average Markov control problems

    Publication Year: 1992 , Page(s): 1421 - 1425
    Cited by:  Papers (11)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (428 KB)  

    A singularly perturbed Markov decision process with the limiting average reward criterion is considered. It is assumed that the underlying process is composed of n separate irreducible processes, and that the small perturbation is such that it unites these processes into a single irreducible process. Two algorithms for the solution of the underlying limit Markov control problem are presented. The first of these is a linear program possessing the Wolfe-Dantzig structure inherited from the ergodic `nearly decomposable' assumption in the model. The second is an aggregation-disaggregation policy improvement algorithm View full abstract»

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  • Distributed detection with consulting sensors and communication cost

    Publication Year: 1992 , Page(s): 1398 - 1405
    Cited by:  Papers (8)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (688 KB)  

    The problem of distributed detection with consulting sensors in the presence of communication cost associated with any exchange of information (consultation) between sensors is considered. The system considered has two sensors, S1 and S2; S1 is the primary sensor responsible for the final decision u0 , and S2 is a consulting sensor capable of relaying its decision u2 to S1 when requested by S 1. The final decision u0 is either based on the raw data available to S1 only, or, under certain request conditions, also takes into account the decision u2 of sensor S2. Random and nonrandom request schemes are analyzed and numerical results are presented and compared for Gaussian and slow-fading Rayleigh channels. For each decision-making scheme, an associated optimization problem is formulated whose solution is shown to satisfy certain set design criteria that the authors consider essential for sensor fusion View full abstract»

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  • Theory for automatic learning under partially observed Markov-dependent noise

    Publication Year: 1992 , Page(s): 1316 - 1324
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (776 KB)  

    A vigorous branch of automatic learning is directed at the task of locating a global minimum of an unknown multimodal function f(θ) on the basis of noisy observations L(θ(i))=f(θ(i))+W (θ(i)) taken at sequentially-chosen control points {θ(i)}. In all preceding convergence deviations known to the authors, the noise is postulated to depend on the past only through control selection. Here they allow the observation noise sequence to be stochastically dependent, in particular, a function of an unknown underlying Markov decision process, the observations being the stagewise losses. In a sense, in order to be made precise, the algorithm offered is shown to attain asymptotically optimal performance, and rates are assured. A motivating example from queueing theory is offered, and connections with classical problems of Markov control theory and other disciplines are mentioned View full abstract»

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  • Passivity and global stabilization of cascaded nonlinear systems

    Publication Year: 1992 , Page(s): 1386 - 1388
    Cited by:  Papers (24)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (228 KB)  

    An alternative stability analysis is presented for recent results on global stabilization of a nonlinear system in cascade with a linear system. The analysis is carried out using passivity arguments. The relationship between passivity and an important class of Lyapunov function is also presented View full abstract»

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  • Cyclomonotonicity and stabilizability properties of solutions of the difference periodic Riccati equation

    Publication Year: 1992 , Page(s): 1405 - 1410
    Cited by:  Papers (5)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (556 KB)  

    The Kalman filter associated with a discrete-time linear T-periodic system is tested. The problem considered is that of selecting an initial covariance matrix such that the periodic filter based on the first T values of the Kalman filter gain is stabilizing. Sufficient conditions are given that hinge on the cyclomonotonicity of the solution of the periodic Riccati equation. Potential applications are found in filter design, quasi-linearization techniques for the periodic Riccati equation, and the design of receding-horizon control strategies for periodic and multirate systems. When specialized to time-invariant systems, the results give rise to new sufficient conditions for the cyclomonotonicity of the solutions of the time-invariant Riccati equation and the existence of periodic stabilizing feedback 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