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Automatic Control, IEEE Transactions on

Issue 3 • Date March 1994

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Displaying Results 1 - 25 of 50
  • Comments on "Robust adaptive regulation with minimal prior knowledge"

    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (135 KB)  

    The author comments on the paper by F. Giri et al. (see ibid., vol.37, no.3, p.305-15, 1992). The author argues that there is a circularity in the argument of the paper and that therefore, the correctness of the results of the paper is ambiguous.<> View full abstract»

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  • Comments on "The attitude control problem"

    Page(s): 699 - 700
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    The commenter refers to above paper by Wen and Kreutz-Delgado (ibid. vol.36, no.10, p.1148-62 (1991)), and points out that there are some errors in the proof of Theorem 1. As a result of this, the final expression in Theorem 1 and 2, together with the table in Theorem 2 should be modified.<> View full abstract»

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  • Stability analysis for manufacturing systems with unreliable machines and random inputs

    Page(s): 681 - 686
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (480 KB)  

    The manufacturing system considered in the paper consists of possibly unreliable machines, whose inputs may be random and may be in batches. The key assumption on the system is that events of unsatisfactory processing independently occur at all machines. We derive a set of inequalities relating processing rates with probabilities of successful processing at unreliable machines. It is shown that the manufacturing system with a clear-a-fraction-of-work-load (CFWL) scheduling policy applied is stable if these inequalities are satisfied simultaneously; by CFWL policy we mean the policy that chooses any part-type with a work load exceeding a certain portion of the total one for the next run View full abstract»

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  • On some LP problems for performance evaluation of timed marked graphs

    Page(s): 696 - 698
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    Three linear programming (LP) formulations are known for performance evaluation of timed marked graphs. Two of these are dual. This paper shows that the third problem is isomorphic to one of the dual problems. An illustrative example is also given View full abstract»

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  • The discrete-time Riccati equation related to the H control problem

    Page(s): 686 - 691
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (512 KB)  

    The H control problem has been solved recently with the use of discrete-time algebraic Riccati equations. In this paper, we investigate this Riccati equation. We derive recursive methods to find the stabilizing solution of this Riccati equation. Moreover, we derive several properties of the class of positive semi-definite solutions of this equation. View full abstract»

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  • Diverse bounds for the eigenvalues of the continuous algebraic Riccati equation

    Page(s): 532 - 534
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    Summation bounds for the eigenvalues of A'P+PA are presented. Here matrices A,P∈Rn×n, P is positive definite and A'=transpose of A. These bounds are employed to derive new upper bounds for summations of eigenvalues of the solution of the continuous algebraic Riccati equation View full abstract»

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  • Structural properties of optimal production controllers in failure-prone manufacturing systems

    Page(s): 640 - 643
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (428 KB)  

    A failure-prone manufacturing system with one part-type and multiple machine states is considered. Each machine state has a given production capacity but is associated with several possible failure stages. Although transition times between failure stages are assumed exponential, the existence of multiple stages within each machine state allows failure times to have a distribution more general than the exponential distribution. For such a system, it is shown that the well-known hedging point policy minimizes inventory and backlog costs for a constant demand rate. The value of the optimal hedging points is now a function of failure stage as well as machine state. By ordering machine states according to increasing distance from the zero capacity state and failure stages according to distance from the capacity reduction transition, we show that hedging points increase monotonically when the machine state number decreases or the stage number increases. This can be intuitively interpreted as follows: the closer to the zero capacity state the system is, the larger the hedging point should be. This structural property of the optimal control is very useful in searching for the optimal control or designing near-optimal controls View full abstract»

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  • Multi-channel output gain margin improvement using generalized sampled-data hold functions

    Page(s): 657 - 661
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (412 KB)  

    This paper considers the multichannel gain margin problem for linear time-invariant continuous-time multi-input multi-output plants controlled by memoryless generalized sampled-data hold functions (GSHF). It is proved that arbitrarily large output gain margins can be achieved by suitable selection of the sampling time and the hold function. We use state space methods and give a constructive design procedure. The controller we use is memoryless in the sense that the discrete-time closed-loop system has the same McMillan degree as the open-loop continuous-time plant View full abstract»

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  • On the novel approach to the design of unknown input observers

    Page(s): 698 - 699
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    In the papers, a new method to design unknown input observer and its existence conditions are presented. We show that such conditions are equivalent to those generally adopted for unknown inputs observers View full abstract»

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  • Structural properties of multirate sampled-data systems

    Page(s): 692 - 696
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (472 KB)  

    A complete analysis of the structural properties of multirate sampled-data systems is considered in this paper. Necessary and sufficient conditions for the reachability, controllability and stabilizability and for the dual notions are given in terms of simple rank tests. These results obtained by the structural theory of periodic systems, generalize to the multirate case the well-known conditions of the single-rate case View full abstract»

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  • Fast parallel recursive aggregation methods for simulation of dynamical systems

    Page(s): 534 - 540
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (620 KB)  

    A novel recursive aggregation algorithm for numerical simulations of dynamic systems is proposed and analyzed. The algorithm exploits a special structure of the linear equation problem resulting from the discretization of the dynamic system and an aggregation/disaggregation procedure. The algorithm has a time complexity of (I(q)+2M(q)+3)logN for solving linear systems with q states for N discrete time instants, using O(q3N) processors, where I(q) is the parallel time complexity for inverting a q×q matrix, M(q) is the parallel time complexity for matrix multiplication of two q×q matrices. The competing parallel cyclic reduction method for the same problem has a time complexity of (I(q)+3M(q)+4)logN. Thus, the proposed algorithm has a definite speed advantage over the cyclic reduction method. An approximation technique for the unknown boundary conditions in boundary value problems is also proposed. The algorithm was implemented to simulate some dynamical (stable and unstable) systems, and the numerical results show that the accumulation of roundoff errors is insignificant as compared to the discretization errors View full abstract»

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  • An autonomous vision-based mobile robot

    Page(s): 493 - 502
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (984 KB)  

    This paper describes the theoretical development and experimental implementation of a complete navigation procedure for use in an autonomous mobile robot for structured environments. Estimates of the vehicle's position and orientation are based on the rapid observation of visual cues located at discrete positions within the environment. The extended Kalman filter is used to combine these visual observations with sensed wheel rotations to produce optimal estimates continuously. The complete estimation procedure, as well as the control algorithm, developed are time independent. A naturally suitable quantity involving wheel rotations is used as the independent variable. One consequence of this choice is that the vehicle speed can be specified independently of the estimation and control algorithms. Reference paths are “taught” by manually leading the vehicle through the desired path. Estimates produced by the extended Kalman filter during this teaching session are then used to represent the geometry of the path. The tracking of taught reference paths is accomplished by controlling the position and orientation of the vehicle relative to the reference path. Time-independence path tracking has necessitated the development of a novel, geometry-based means for advancing along the reference path View full abstract»

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  • Least absolute values estimation: computational aspects

    Page(s): 626 - 630
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (428 KB)  

    A problem that often arises in system identification, the problem of robust parametric estimation, is addressed. A high efficient technique is developed for the recurrent LAV estimation. Due to the direct minimization algorithm, the proposed technique requires half as many independent variables as compared to the simplex method of linear programming, most commonly applied for the LAV estimation. The computational realization is based on the finite iterative scheme View full abstract»

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  • The solution of diagonal decoupling problem by dynamic output feedback and constant precompensator: the general case

    Page(s): 503 - 511
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (712 KB)  

    In this paper, the solution to diagonal decoupling problem via dynamic output feedback and constant precompensator is presented in the general case. The literature contains a number of particular solutions for this problem. These solutions are valid, for instance, for square transfer matrices or they employ restricted dynamic output feedback schemes. Here, we start with a nonsquare transfer matrix and consider a dynamic output feedback scheme where there is a proper compensator in the feedback loop accompanied by a constant gain (precompensator) in the feedforward path. In this respect, the problem being considered is the dynamic output feedback version of the well-known Morgan's problem. The approach taken involves the characterization of open-loop diagonalizers which admit a dynamic output feedback realization. The key concepts involved in the solution are the generalized version of diagonal causality degree dominance and the set of attainable infinite zero orders. An example is also included to illustrate the main result View full abstract»

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  • Analytic first and second derivatives for the recursive prediction error algorithm's log likelihood function

    Page(s): 662 - 664
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    This note improves on a method for computing analytic derivatives of the likelihood function of a discrete, linear, time invariant Gaussian state-space system and extends it to handle correlation between the state transition and measurement noise terms and to compute the analytic Hessian matrix View full abstract»

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  • A note on a necessary condition for output regulation

    Page(s): 558 - 559
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    Known schemes for output regulation imply the existence of invariant sets union of orbits solving the exact tracking problem. This necessary condition is exploited on the basis of the limit set concept and shown to hold for a quite general class of control systems and regulator problems View full abstract»

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  • Stabilizing I-O receding horizon control of CARMA plants

    Page(s): 614 - 618
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    Stabilizing input-output receding horizon control (SIORHC) yields dynamic feedback compensators capable of stabilizing any stabilizable linear plant under sharp conditions. The guaranteed stabilizing property is insured by using output terminal constraints in addition to input terminal constraints. This note extends previous SIORHC results to CARMA plants View full abstract»

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  • Extended Chandrasekhar recursions

    Page(s): 619 - 623
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (444 KB)  

    We extend the discrete-time Chandrasekhar recursions for least-squares estimation in constant parameter state-space models to a class of structured time-variant state-space models, special cases of which often arise in adaptive filtering. It can be shown that the much studied exponentially weighted recursive least-squares filtering problem can be reformulated as an estimation problem for a state-space model having this special time-variant structure. Other applications arise in the multichannel and multidimensional adaptive filtering context View full abstract»

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  • An iterative algorithm for pole placement by output feedback

    Page(s): 565 - 568
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    An iterative algorithm is proposed for solving the pole assignment by output feedback problem for an nth-order l-input m-output linear system. The algorithm uses a full rank feedback gain matrix and requires only linear equations of low dimension to be solved at each iteration. Application of the proposed algorithm allows all n closed-loop poles to be almost exactly assigned provided that the iterations converge so that deviations of the resulting closed-loop poles from the respective desired values become less than some user-specified tolerance, and m×t⩾n. Examples are provided to illustrate the applicability of the proposed method View full abstract»

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  • Absolute stability of systems with parametric uncertainty and nonlinear feedback

    Page(s): 664 - 668
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    This paper gives an extension of the absolute stability analysis of systems whose forward path contains a linear time-invariant subsystem with uncertain coefficients and whose feedback path contains a conic nonlinearity. The results provide a simple frequency domain interpretation of stability that can be of importance in compensator design and robust stability analysis in nonlinear systems View full abstract»

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  • Force/position regulation of compliant robot manipulators

    Page(s): 647 - 652
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    Stable force/position regulation of robot manipulators in contact with an elastically compliant surface is discussed in this work. The controller consists of a PD action on the position loop, a PI action on the force loop, together with gravity compensation and desired contact force feedforward. Asymptotic stability of the system in the neighborhood of the equilibrium state is proven via the classical Lyapunov method with LaSalle invariant set theorem. A modification of the Lyapunov function leads to deriving an exponential stability result. Numerical case studies are developed for an industrial manipulator View full abstract»

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  • System characterization of positive real conditions

    Page(s): 540 - 544
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (424 KB)  

    Necessary and sufficient conditions for positive realness in terms of state-space matrices are presented under the assumption of complete controllability and complete observability of square systems with independent inputs. By a particular transform of these conditions, a direct algorithm for testing positive realness is determined that requires only checking a set of simple algebraic conditions. This provides an alternative procedure to the positive real lemma and to the s-domain inequalities. Based on this algorithm, a synthesis of a positive real system via output feedback is presented View full abstract»

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  • On undershoot in SISO systems

    Page(s): 578 - 581
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    We show that the step response of an asymptotically stable strictly proper nonminimum phase continuous time system with m1 real open right half plane zeros, no conjugate complex zeros and poles, and with real open left half plane zeros and poles satisfying a given “bracketing” condition, exhibits undershoot exactly int m1+½ times. Both qualitative and quantitative arguments are also introduced to highlight the main issues under discussion. Simple examples are given to illustrate and complement the main result of this paper View full abstract»

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  • Solution approximation in infinite horizon linear quadratic control

    Page(s): 596 - 601
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (564 KB)  

    We consider the problem of choosing a discounted-cost minimizing infinite-stage control sequence under nonstationary positive semidefinite quadratic costs and linear constraints. Specific cases include the nonstationary LQ tracker and regulator problems. We show that the optimal costs for finite-stage approximating problems converge to the optimal infinite-stage cost as the number of stages grows to infinity. Under a state reachability condition, we show that the set unions of all controls optimal to all feasible states for the finite-stage approximating problems converge to the set of infinite-stage optimal controls. A tie-breaking rule is provided that selects finite-stage optimal controls so as to force convergence to an infinite horizon optimal control View full abstract»

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  • Spectral and inner-outer factorizations through the constrained Riccati equation

    Page(s): 677 - 681
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    The topic of the paper is the spectral factorization problem for a proper rational matrix function of constant rank, but not necessarily maximal, on the extended imaginary axis. The problem is reduced to the computation of the stabilizing solution of a so-called constrained Riccati equation. The proof of the main result suggests a Schur-like algorithm applied to a singular matrix pencil 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