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Automatic Control, IEEE Transactions on

Issue 3 • Date March 1997

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Displaying Results 1 - 22 of 22
  • Comments on "A new controller design for a flexible one link manipulator"

    Publication Year: 1997 , Page(s): 425 - 429
    Cited by:  Papers (4)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (155 KB)  

    In the original paper of W.T. Qian and C.C.H. Ma (ibid., vol. 37, p. 132-7, 1992), a variable structure sliding mode controller (VSSMC) design for the tip position control of a flexible one-link manipulator has been presented, where a switching line constructed from the tip position and its derivative was employed for the design. The claim was that if the slope of this line is chosen positive and the system variables are made to stay on this line, they will converge to zero exponentially, thus yielding a stable system in sliding mode (SM). The purpose of this comment is to show that the choice of a positive constant as the slope for this switching line will not guarantee the stability of the system in SM because, in view of the functional relationship of the tip position with the generalized coordinates of the system through the mode shape functions, what is presented as a switching line is in fact a switching hypersurface. Hence, the stability of the system in SM is guaranteed only if the motion on this hypersurface is asymptotically stable. A positive value for the slope of the switching line employed by Qian and Ma will not guarantee this stability because variations in the mode shape functions due to varying payload conditions or other disturbances at the tip will lead to a varying switching surface. These variations can be such that the resulting sliding motion becomes unstable. Also, the varying switching surface implies that the controller will fail to maintain sliding mode motion. View full abstract»

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  • Comments on "An improved Razumikhin-type theorem and its applications" [with reply]

    Publication Year: 1997 , Page(s): 429 - 430
    Cited by:  Papers (4)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (62 KB)  

    Xu and Liu (see ibid., vol.39, no.4, p.839-41, 1994) tried to improve the well-known Razumikhin theorem on the stability of differential functional equations. The commenter states that, the proof of their main result contains an error, so the results may not be correct. In reply Bugong Xu gives a corrected result. View full abstract»

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  • Author's reply

    Publication Year: 1997 , Page(s): 430
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (35 KB)  

    First Page of the Article
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  • Correction to "Connections Between Local Stability in Lyapunov and Input/Ouput Senses"

    Publication Year: 1997 , Page(s): 433
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (23 KB)  

    First Page of the Article
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  • Linear Matrix Inequalities in System and Control Theory [Book Reviews]

    Publication Year: 1997 , Page(s): 434 - 435
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    Freely Available from IEEE
  • Stable scheduling policies for flexible manufacturing systems

    Publication Year: 1997 , Page(s): 420 - 425
    Cited by:  Papers (5)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (284 KB)  

    In this brief note we provide a new analysis of the transient behavior of the clear-a-fraction policy of Perkins and Kumar (1989). In addition, we show that a new “clear-average-oldest-buffer” policy and a “random part selection” policy (of which “first-come-first-served” is a special case) are stable. Finally, we introduce a stable and efficient “stream modifier” that can be used to obtain network level stability results View full abstract»

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  • New results on output-feedback variable structure model-reference adaptive control: design and stability analysis

    Publication Year: 1997 , Page(s): 386 - 393
    Cited by:  Papers (38)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (376 KB)  

    The variable structure model-reference adaptive control(VS-MRAC) redesign and stability analysis, presented previously by the authors (1993) for the case of plants with relative degree n*⩽2, is generalized to the case of arbitrary n*⩾1. This paper presents a complete stability analysis in the general case. The redesign is based on the explicit consideration of input disturbances which may include the disturbance originated by the uncertainty of the plant high-frequency gain. This leads to a considerably simpler and less restrictive stability analysis as well as to a systematic controller design for external disturbance rejection. The overall error system is globally exponentially stable with respect to a small residual set. Robustness to unmodeled dynamics is also discussed View full abstract»

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  • Bounded feedback stabilization and global separation principle of distributed parameter systems

    Publication Year: 1997 , Page(s): 414 - 419
    Cited by:  Papers (7)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (224 KB)  

    We show that the infinite-dimensional system Σ:x˙(t)=Ax(t)+Bu(t), x0 ε H is globally strongly asymptotically stabilizable by an arbitrarily small smooth feedback. Here, the operator A is the infinitesimal generator of a C0 semigroup of contractions etA on real Hilbert space H and B is a bounded linear operator mapping a Hilbert space of controls U into H. An explicit smooth feedback control law is given. Further, we identify the class of perturbations for which the system is still stabilizable by the same feedback law as for the nominal system. Based on these results and some differential Lyapunov operator equations, we then establish a global separation principle for the system Σ with a Kalman-like observer. Finally, these results are illustrated via an example dealing with the wave equation View full abstract»

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  • A new general sufficient condition for almost sure stability of jump linear systems

    Publication Year: 1997 , Page(s): 378 - 382
    Cited by:  Papers (30)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (208 KB)  

    In this paper, we study the almost sure stability of discrete time jump linear systems with a finite-state Markov-form process. A general condition for almost sure stability, which is a necessary and sufficient condition for (scalar) one-dimensional systems, is derived. Many simpler testable sufficient conditions for almost sure stability are derived from this sufficient condition View full abstract»

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  • Sign and stability of equilibria in quasi-monotone positive nonlinear systems

    Publication Year: 1997 , Page(s): 403 - 407
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (180 KB)  

    The paper deals with the problem of finding the extension of a well-established connection between sign and stability of nontrivial equilibria in positive linear systems to the class of quasi-monotone positive nonlinear systems. The mathematical framework to provide the sufficient conditions guaranteeing such a relationship is the stability theory for nonlinear systems, especially the comparison principles and the method of vector Lyapunov functions. As an illustration of our results we present an example of a double-effect evaporator to study the sign-stability property of its only equilibrium point View full abstract»

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  • A small-gain control method for nonlinear cascaded systems with dynamic uncertainties

    Publication Year: 1997 , Page(s): 292 - 308
    Cited by:  Papers (126)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (936 KB)  

    Some robust control problems for a class of nonlinear cascaded systems in the presence of state and input driven unmeasured dynamics are analyzed. A stepwise constructive control methodology is proposed on the basis of the nonlinear small-gain theorem. The flexibility of the approach in tackling dynamic uncertainties is illustrated by demonstrating that several results for special classes of cascaded systems, considered previously in the literature, may be viewed as special instances of the present results View full abstract»

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  • On adaptive boundary control for stochastic parabolic systems with unknown potential coefficient

    Publication Year: 1997 , Page(s): 350 - 363
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (880 KB)  

    An adaptive boundary control problem for a stochastic heat diffusion equation is studied. The considered system contains an unknown potential coefficient which is a function of the spatial variables. The estimation algorithm for the unknown potential coefficient is proposed by using the stochastic approximation technique. After showing the strong consistency of the estimated parameter, the cost for the adaptive control scheme presented here is shown to converge to the optimal ergodic cost. Finally some numerical examples are shown View full abstract»

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  • Scheduling multiple part-types in an unreliable single-machine manufacturing system

    Publication Year: 1997 , Page(s): 364 - 377
    Cited by:  Papers (20)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (600 KB)  

    Quadratic approximations to the differential cost-to-go function, which yield linear switching curves, have been extensively studied in the literature. In this paper, we provide solutions to the partial differential equations associated with the components of the steady-state probability density function of the buffer levels for two part-type, single-machine flexible manufacturing systems under a linear switching curve (LSC) policy. When there are more than two part-types, we derive the probability density function, under a prioritized hedging point (PHP) policy by decomposing the multiple part-type problem into a sequence of two part-type problems. The analytic expression for the steady-state probability density function is independent of the cost function. Therefore, for average cost functions, we can compute the optimal PHP policy or the more general optimal LSC policy for two part-type problems View full abstract»

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  • Addendum to “A new minimum-time control law for a one-mode model of a flexible slewing structure”

    Publication Year: 1997 , Page(s): 431 - 433
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (88 KB)  

    In a previous article by Barbieri et al. (ibid., vol.38, p.142-6 (1993)) a set of five conditions were given to characterize the switching hypersurface of the minimum-time, single-axis controller for an undamped, one-mode model of a flexible slewing structure. The purpose of this paper is to show that the five conditions have been found to be reducible to three. This oversight is repaired, and a new plot of the three conditions in a two-dimensional plane is isolated to easily identify the switching strategy in real-time View full abstract»

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  • Calculation of the minimal dimension kth-order robust servoregulator

    Publication Year: 1997 , Page(s): 382 - 386
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (180 KB)  

    The design of a minimal dimension kth-order robust servoregulator requires calculation of the minimal polynomial of a class of matrices defined by the given exosystem. A characterization of the minimal polynomial of this class of matrices was given in Huang (1992) when the given exosystem is semisimple. This paper further provides a characterization of this class of matrices in the general case. This result leads to a straightforward and efficient procedure to calculate the minimal dimension kth-order robust servoregulator View full abstract»

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  • A new order estimation technique for time series modeling

    Publication Year: 1997 , Page(s): 400 - 403
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (140 KB)  

    A new approach to estimating the order of the autoregressive moving average model is proposed, which is based on the approximate stochastic realization introduced in Davis and Fotopoulos (1991). The present approach is attractive because overparameterization-a very common problem in order determination-is avoided successfully. Simulation results are included to illustrate the effectiveness of the proposed order estimation approach View full abstract»

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  • Capacity allocation under noncooperative routing

    Publication Year: 1997 , Page(s): 309 - 325
    Cited by:  Papers (38)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (904 KB)  

    The capacity allocation problem in a network that is to be shared by noncooperative users is considered. Each user decides independently upon its routing strategy so as to optimize its individual performance objective. The operating points of the network are the Nash equilibria of the underlying routing game,. The network designer aims to allocate link capacities, so that the resulting Nash equilibria are efficient, according to some systemwide performance criterion. In general, the solution of such design problems is complex and at times counterintuitive, since adding link capacity might lead to degradation of user performance. For systems of parallel links, we show that such paradoxes do not occur and that the capacity allocation problem has a simple and intuitive optimal solution that coincides with the solution in the single-user case View full abstract»

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  • A remark on the stabilization of partially linear composite systems

    Publication Year: 1997 , Page(s): 411 - 414
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (148 KB)  

    We study global stabilization, by means of smooth state feedback, of partially linear composite systems. We show how to compute the stabilizing feedback thanks to a weak Lyapunov function for a nonlinear subsystem instead of a strict one View full abstract»

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  • Nonlinear control of constrained linear systems via predictive reference management

    Publication Year: 1997 , Page(s): 340 - 349
    Cited by:  Papers (163)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (532 KB)  

    A method based on conceptual tools of predictive control is described for solving set-point tracking problems wherein pointwise-in-time input and/or state inequality constraints are present. It consists of adding to a primal compensated system a nonlinear device, called command governor (CG), whose action is based on the current state, set-point, and prescribed constraints. The CG selects at any time a virtual sequence among a family of linearly parameterized command sequences, by solving a convex constrained quadratic optimization problem, and feeds the primal system according to a receding horizon control philosophy. The overall system is proved to fulfill the constraints, be asymptotically stable, and exhibit an offset-free tracking behavior, provided that an admissibility condition on the initial state is satisfied. Though the CG can be tailored for the application at hand by appropriately choosing the available design knobs, the required online computational load for the usual case of affine constraints is well tempered by the related relatively simple convex quadratic programming problem View full abstract»

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  • On interconnections, control, and feedback

    Publication Year: 1997 , Page(s): 326 - 339
    Cited by:  Papers (115)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (636 KB)  

    The purpose of this paper is to study interconnections and control of dynamical systems in a behavioral context. We start with an extensive physical example which serves to illustrate that the familiar input-output feedback loop structure is not as universal as we have been taught to believe. This leads to a formulation of control problems in terms of interconnections. Subsequently, we study interconnections of linear time-invariant systems from this vantage point. Let us mention two of the results obtained. The first one states that any polynomial can be achieved as the characteristic polynomial of the interconnection with a given plant, provided the plant is not autonomous. The second result states that any subsystem of a controllable system can be implemented by means of a singular feedback control law. These results yield pole placement and stabilization of controllable plants as a special case. These ideas are finally applied to the stabilization of a nonlinear system around an operating point View full abstract»

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  • Robust control design for nonlinear uncertain systems with an unknown time-varying control direction

    Publication Year: 1997 , Page(s): 393 - 399
    Cited by:  Papers (13)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (212 KB)  

    A continuous robust control design approach is proposed for first-order nonlinear systems whose dynamics contain both nonlinear uncertainty and an unknown time-varying control direction. The so-called control direction is the multiplier of the control term in the dynamic equation, and it effectively represents the direction of motion under any given control. A nonlinear robust control is designed to online and continuously identify sign changes of the unknown control direction and to guarantee stability of uniform ultimate boundedness. The proposed robust control design requires only three conditions: the nominal system is stable, the control direction is smooth, and the uncertainty in the system is bounded by a known function. The necessity of these conditions is established in this paper. Continuity of the proposed robust control is achieved by using a so-called shifting law that changes smoothly the sign of robust control and tracks the change of the unknown control direction. Analysis and design is shown by using Lyapunov's direct method View full abstract»

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  • New estimates for solutions of Lyapunov equations

    Publication Year: 1997 , Page(s): 408 - 411
    Cited by:  Papers (12)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (148 KB)  

    Results for estimating the solution of differential and algebraic Lyapunov matrix equations are obtained, and some of the well-known results are generalized 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