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Automatic Control, IEEE Transactions on

Issue 7 • Date Aug. 2008

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Displaying Results 1 - 25 of 35
  • Table of contents

    Publication Year: 2008 , Page(s): C1 - C4
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    Freely Available from IEEE
  • IEEE Transactions on Automatic Control publication information

    Publication Year: 2008 , Page(s): C2
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    Freely Available from IEEE
  • Scanning the issue

    Publication Year: 2008 , Page(s): 1573 - 1574
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  • Adaptive Boundary Control for Unstable Parabolic PDEs—Part I: Lyapunov Design

    Publication Year: 2008 , Page(s): 1575 - 1591
    Cited by:  Papers (46)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (695 KB) |  | HTML iconHTML  

    We develop adaptive controllers for parabolic partial differential equations (PDEs) controlled from a boundary and containing unknown destabilizing parameters affecting the interior of the domain. These are the first adaptive controllers for unstable PDEs without relative degree limitations, open-loop stability assumptions, or domain-wide actuation. It is the first necessary step towards developing adaptive controllers for physical systems such as fluid, thermal, and chemical dynamics, where actuation can be only applied non-intrusively, the dynamics are unstable, and the parameters, such as the Reynolds, Rayleigh, Prandtl, or Peclet numbers are unknown because they vary with operating conditions. Our method builds upon our explicitly parametrized control formulae to avoid solving Riccati or Bezout equations at each time step. Most of the designs we present are state feedback but we present two benchmark designs with output feedback which have infinite relative degree. View full abstract»

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  • Optimal Nonblocking Directed Control of Discrete Event Systems

    Publication Year: 2008 , Page(s): 1592 - 1603
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (973 KB) |  | HTML iconHTML  

    For the control of discrete event systems, the notion of directed control refines that of supervisory control. A directed controller is one that selects at most one controllable event to be enabled at any state (without disabling any uncontrollable event), which is in fact how a discrete event control is implemented. In contrast, a supervisory controller computes a maximal allowable set of controllable events at each state, leaving undecided exactly which controllable event should be enabled. In previous works, we developed a framework for the computation of optimal directed controllers and a polynomial synthesis algorithm for acyclic plants. In this paper, we present a novel synthesis approach for general plants, i.e., plants with or without cycles, thus providing a complete solution to the optimal directed control problem. The complexity of the approach remains polynomial in the size of plant. View full abstract»

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  • Feedback Control in the Presence of Noisy Channels: “Bode-Like” Fundamental Limitations of Performance

    Publication Year: 2008 , Page(s): 1604 - 1615
    Cited by:  Papers (64)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (419 KB) |  | HTML iconHTML  

    This paper addresses fundamental limitations of feedback using information theoretic conservation laws and flux arguments. The paper has two parts. In the first part, we derive a conservation law dictating that causal feedback cannot reduce the differential entropy inserted in the loop by external sources. An interpretation of this result is that the total randomness induced by disturbances, as measured by differential entropy, cannot be reduced by causal feedback; it can only be re-allocated in time or in frequency (if well defined). Under asymptotic stationarity assumptions, this result has a spectral representation which constitutes an extension of Bode's inequality for arbitrary feedback. Our proofs make clear the role of causality, as well as how stability assumptions impact the final result. In the second part, we derive an inequality unveiling that the feedback loop must be able to convey information originating from two independent sources: 1) initial states of the physical plant; 2) exogenous disturbance signals. By using such principle, we construct a variety of information rate (information flux) inequalities. Furthermore, we derive a universal performance bound which is parameterized solely by the feedback capacity and the parameters of the plant. The latter is a new fundamental limitation, which is different from Bode's classical result, indicating that finite feedback capacity brings a new type of performance bound. View full abstract»

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  • Optimal Control of Spatially Distributed Systems

    Publication Year: 2008 , Page(s): 1616 - 1629
    Cited by:  Papers (36)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (682 KB) |  | HTML iconHTML  

    In this paper, we study the structural properties of optimal control of spatially distributed systems. Such systems consist of an infinite collection of possibly heterogeneous linear control systems that are spatially interconnected via certain distant-dependent coupling functions over arbitrary graphs. We study the structural properties of optimal control problems with infinite-horizon linear quadratic criteria, by analyzing the spatial structure of the solution to the corresponding operator Lyapunov and Riccati equations. The key idea of the paper is the introduction of a special class of operators called spatially decaying (SD). These operators are a generalization of translation invariant operators used in the study of spatially invariant systems. We prove that given a control system with a state-space representation consisting of SD operators, the solution of operator Lyapunov and Riccati equations are SD. Furthermore, we show that the kernel of the optimal state feedback for each subsystem decays in the spatial domain, with the type of decay (e.g., exponential, polynomial or logarithmic) depending on the type of coupling between subsystems. View full abstract»

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  • Generalized Lyapunov Equation Approach to State-Dependent Stochastic Stabilization/Detectability Criterion

    Publication Year: 2008 , Page(s): 1630 - 1642
    Cited by:  Papers (39)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (505 KB) |  | HTML iconHTML  

    In this paper, the generalized Lyapunov equation approach is used to study stochastic stabilization/detectability with state-multiplicative noise. Some practical test criteria for stochastic stabilization and detectability, such as stochastic Popov-Belevitch-Hautus criterion for exact detectability, are obtained. Moreover, useful properties of the generalized Lyapunov equation are derived based on critical stability and exact detectability introduced in this paper. As applications, first, the stochastic linear quadratic regulator as well as the related generalized algebraic Riccati equation are discussed extensively. Second, the infinite horizon stochastic H 2/H infin control with state- and control-dependent noise is also investigated, which extends and improves the recently published results. View full abstract»

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  • Asymptotically Optimal Decentralized Control for Large Population Stochastic Multiagent Systems

    Publication Year: 2008 , Page(s): 1643 - 1660
    Cited by:  Papers (26)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (646 KB) |  | HTML iconHTML  

    The interaction of interest-coupled decision-makers and the uncertainty of individual behavior are prominent characteristics of multiagent systems (MAS). How to break through the framework of conventional control theory, which aims at single decision-maker and single decision objective, and to extend the methodology and tools in the stochastic adaptive control theory to analyze MAS are of great significance. In this paper, a preliminary exploration is made in this direction, and the decentralized control problem is considered for large population stochastic MAS with coupled cost functions. Different from the deterministic discounted costs in the existing differential game models, a time-averaged stochastic cost function is adopted for each agent. The decentralized control law is constructed based on the state aggregation method and tracking-like quadratic optimal control. By using probability limit theory, the stability and optimality of the closed-loop system are analyzed. The main contributions of this paper include the following points. 1) The concepts of asymptotic Nash-equilibrium in probability and almost surely, respectively, are introduced and the relationship between these concepts is illuminated, which provide necessary tools for analyzing the optimality of the decentralized control laws. 2) The closed-loop system is shown to be almost surely uniformly stable, and bounded independently of the number of agents N . 3) The population state average (PSA) is shown to converge to the infinite population mean (IPM) trajectory in the sense of both L2-norm and time average almost surely, as N increases to infinity. 4) The decentralized control law is designed and shown to be almost surely asymptotically optimal; the cost of each agent based on local measurements converges to that based on global measurements almost surely, as N increases to infinity. View full abstract»

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  • An Iterative Identification Method for Linear Continuous-Time Systems

    Publication Year: 2008 , Page(s): 1661 - 1669
    Cited by:  Papers (6)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (590 KB) |  | HTML iconHTML  

    This paper presents a novel approach for the identification of continuous-time systems directly from sampled I/O data based on trial iterations. The method achieves identification through iterative learning control (ILC) concepts in the presence of heavy measurement noise. The robustness against measurement noise is achieved through 1) projection of continuous-time I/O signals onto a finite dimensional parameter space and 2) Kalman filter type noise reduction. In addition, an alternative simpler method is given with some robustness analysis. The effectiveness of the method is demonstrated through numerical examples for a nonminimum phase plant. View full abstract»

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  • Necessary and Sufficient Conditions for Dynamical Structure Reconstruction of LTI Networks

    Publication Year: 2008 , Page(s): 1670 - 1674
    Cited by:  Papers (17)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (162 KB) |  | HTML iconHTML  

    This paper formulates and solves the network reconstruction problem for linear time-invariant systems. The problem is motivated from a variety of disciplines, but it has recently received considerable attention from the systems biology community in the study of chemical reaction networks. Here, we demonstrate that even when a transfer function can be identified perfectly from input-output data, not even Boolean reconstruction is possible, in general, without more information about the system. We then completely characterize this additional information that is essential for dynamical reconstruction without appeal to ad-hoc assumptions about the network, such as sparsity or minimality. View full abstract»

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  • On Inexact LPV Control Design of Continuous–Time Polytopic Systems

    Publication Year: 2008 , Page(s): 1674 - 1678
    Cited by:  Papers (24)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (215 KB) |  | HTML iconHTML  

    Robust dynamic output design most often relies on nonconvex problems. This is precisely the case with linear parameter-varying (LPV) control when the measured varying parameters do not exactly fit the real ones. This paper provides a solution in the convex programming framework with the use of linear matrix inequality (LMI) solvers in the case of polytopic parameter dependence. A bounded uncertainty set is defined from the difference between the measured and the true parameters from which LMI stabilization and performance conditions are obtained after bounding. As a desired property, the proposed conditions reduce to the classical LPV ones whenever the true parameters are available for control synthesis. View full abstract»

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  • Nonlinear Stabilization of Shock-Like Unstable Equilibria in the Viscous Burgers PDE

    Publication Year: 2008 , Page(s): 1678 - 1683
    Cited by:  Papers (6)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (468 KB) |  | HTML iconHTML  

    We stabilize the unstable ldquoshock-likerdquo equilibrium profiles of the viscous Burgers equation using control at the boundaries. These equilibria are not stabilizable (even locally) using the standard ldquoradiation feedback boundary conditions.rdquo Using a nonlinear spatially-scaled transformation (that employs three ingredients, of which one is the Hopf-Cole nonlinear integral transformation) and linear backstepping, we design an explicit nonlinear full-state control law that achieves exponential stability, with a region of attraction for which we give an estimate. The region of attraction is not the entire state space since the Burgers PDE is known not to be globally controllable. View full abstract»

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  • On Compensating Long Actuator Delays in Nonlinear Control

    Publication Year: 2008 , Page(s): 1684 - 1688
    Cited by:  Papers (19)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (197 KB) |  | HTML iconHTML  

    We are interested in finite-escape open-loop unstable plants that are globally stabilizable in the absence of actuator delay but require controller redesign in the presence of delay. The simplest such plant is Z(t) = Z(t)2 + U(t - D), where D is actuator delay of arbitrary length. For this system we present a control law that compensates the delay and achieves feedback linearization (of the entire ODE+delay infinite-dimensional cascade). However, even though exponential stability is achieved, the result is not global because the plant can have a finite escape with an initial condition Z(0) ges 1/D before the feedback control "reaches" it at t = D. We prove a stability result whose region of attraction is essentially Z(0) < 1/ D and for which we derive an asymptotic stability bound in terms of the system norm Z(t)2 + intt t-D U(thetas)2dthetas. View full abstract»

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  • On the Liveness of Guidepath-Based, Zone-Controlled Dynamically Routed, Closed Traffic Systems

    Publication Year: 2008 , Page(s): 1689 - 1695
    Cited by:  Papers (8)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (283 KB) |  | HTML iconHTML  

    Zone-controlled, guidepath-based, dynamically routed, closed traffic systems constitute the modelling abstraction for a large set of industrial and public transport systems. An important requirement for the traffic flow of these systems is that the vehicles maintain their ability to access every location in the underlying guidepath-network, throughout the entire, presumably infinite, length of the system operation. States in which the system preserves the aforementioned property are said to be live. This work provides a structural characterization of state liveness that: (i) enables the identification of live states while foregoing an extensive enumeration of the underlying behavioral space and (ii) facilitates the design of computationally efficient liveness-enforcing supervisors. View full abstract»

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  • Robust H_{\infty } Control for Nonlinear Stochastic Systems: A Sliding-Mode Approach

    Publication Year: 2008 , Page(s): 1695 - 1701
    Cited by:  Papers (20)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (336 KB) |  | HTML iconHTML  

    This paper considers the sliding-mode control for nonlinear stochastic systems modeled by Ito stochastic differential equations. It is noted that there exist state and exogenous disturbance-dependent noise in the controlled systems. By utilizing H infin disturbance attenuation technique, a novel sliding-mode control method is proposed such that the resultant system is asymptotically stable in probability with a prescribed H infin performance. Sufficient conditions for the solvability of these problems are derived via nonlinear Hamilton-Jacobi (HJ)-type inequalities. Moreover, it is shown that for a class of special nonlinear stochastic systems, the H infin-sliding-mode control design can be obtained by solving linear matrix inequalities (LMIs). Finally, a numerical simulation example is given. View full abstract»

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  • Switched Controllability via Bumpless Transfer Input and Constrained Switching

    Publication Year: 2008 , Page(s): 1702 - 1706
    Cited by:  Papers (5)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (600 KB) |  | HTML iconHTML  

    In this note, we investigate the controllability of linear hybrid systems via bumpless transfer input and constrained switching. By bumpless transfer input, we mean that the control input signals are as close as possible at switching times. By constrained switching, we mean that the switching index sequence is cyclic and the switching time sequence is possibly with pre-assigned duration intervals. While the problem is well motivated in several practical situations, it is also theoretically interesting. A complete criterion for controllability is presented, and a computational procedure is developed for finding a switching signal and a control input to achieve the controllability. View full abstract»

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  • Stability of Networked Control Systems Under a Multiple-Packet Transmission Policy

    Publication Year: 2008 , Page(s): 1706 - 1711
    Cited by:  Papers (27)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (233 KB) |  | HTML iconHTML  

    This paper is concerned with stability analysis of discrete-time networked control systems subject to packet loss under a multiple-packet transmission policy with the packet dropping probability of the communication channel bounded from above. Necessary and sufficient conditions for stability are obtained. In addition, the packet dropping margin as a measure of stability robustness of a system against packet loss is defined and its formula is derived. A design method is proposed for enhancing stability robustness subject to the constraint of a set of prescribed nominal closed-loop poles. View full abstract»

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  • Disturbance Attenuation of Feedforward Systems With Dynamic Uncertainty

    Publication Year: 2008 , Page(s): 1711 - 1717
    Cited by:  Papers (10)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (389 KB) |  | HTML iconHTML  

    This paper studies the disturbance attenuation problem of a class of nonlinear systems in feedforward form that is subject to both dynamic uncertainty and disturbance. When the disturbance vanishes, the equilibrium of the closed-loop system is globally asymptotically stable. Two versions of small gain theorem with restrictions are employed to establish the global attractiveness and local stability of the closed-loop system at the equilibrium respectively. View full abstract»

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  • Razumikhin-Type Theorems on Stability of Neutral Stochastic Functional Differential Equations

    Publication Year: 2008 , Page(s): 1718 - 1723
    Cited by:  Papers (9)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (272 KB) |  | HTML iconHTML  

    Recently, Mao (1995) initiated the study of exponential stability of neutral stochastic functional differential equations (NSFDEs) and employed the Razumikhin techniques to investigated the stability problem of NSFDEs. However, the importance of general asymptotic stability has not been considered. This paper studies Razumikhin-type theorems on general pth moment asymptotic stability of NSFDEs. The theorems established in this paper work for some cases to which the existing results cannot be applied. View full abstract»

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  • Stability-Preserving Rational Approximation Subject to Interpolation Constraints

    Publication Year: 2008 , Page(s): 1724 - 1730
    Cited by:  Papers (6)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (704 KB) |  | HTML iconHTML  

    A quite comprehensive theory of analytic interpolation with degree constraint, dealing with rational analytic interpolants with an a priori bound, has been developed in recent years. In this paper, we consider the limit case when this bound is removed, and only stable interpolants with a prescribed maximum degree are sought. This leads to weighted H 2 minimization, where the interpolants are parameterized by the weights. The inverse problem of determining the weight given a desired interpolant profile is considered, and a rational approximation procedure based on the theory is proposed. This provides a tool for tuning the solution to specifications. The basic idea could also be applied to the case with bounded analytic interpolants. View full abstract»

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  • Optimal Model Predictive Control of Timed Continuous Petri Nets

    Publication Year: 2008 , Page(s): 1731 - 1735
    Cited by:  Papers (14)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (220 KB) |  | HTML iconHTML  

    This paper addresses the optimal control problem of timed continuous Petri nets under infinite servers semantics. In particular, our goal is to find a control input optimizing a certain cost function that permits the evolution from an initial marking (state) to a desired steady-state. The solution we propose is based on a particular discrete-time representation of the controlled continuous Petri net system, as a certain linear constrained system. An upper bound on the sample period is given in order to preserve important information of the timed continuous net, in particular the positiveness of the markings. The reachability space of the sampled system in relation to autonomous continuous Petri nets is also studied. Based on the resulting linear constrained model, the optimal control problem is studied through model predictive control (MPC). Implicit and explicit procedures are presented together with a comparison between the two schemes. Stability of the closed-loop system is also studied. View full abstract»

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  • Hybrid Output Feedback Stabilization for LTI Systems With Single Output

    Publication Year: 2008 , Page(s): 1736 - 1740
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (301 KB) |  | HTML iconHTML  

    This note presents a hybrid control scheme for a class of continuous-time LTI systems that cannot be stabilized by a single static output feedback (SOF) controller. The main idea here is to design multiple SOF gains and proper logic rules that orchestrate switching among these gains so as to achieve the global stability. One challenge, however, is that the switching logic should be in the output feedback form as well. This may seriously restrict the possible choices of switching surfaces, especially when the output is just a scalar. To overcome this difficulty, a multirate sampling control scheme is proposed. Under this framework, a hybrid output feedback stabilizing controller is designed, and sufficient controller synthesis conditions are proposed as linear matrix inequalities based on multiple Lyapunov function theorems. The note concludes with a discussion on possible extensions and future research topics. View full abstract»

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  • Adaptive Synchronization for Generalized Lorenz Systems

    Publication Year: 2008 , Page(s): 1740 - 1746
    Cited by:  Papers (14)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (308 KB) |  | HTML iconHTML  

    In literature it is conjectured that the states of the generalized Lorenz system with an unknown parameter can not be estimated by adaptive observers. In this paper we show that this unknown parameter and the states can actually be estimated simultaneously by some kind of adaptive observer. The proof is obtained by constructing some exponential observer to achieve chaotic synchronization for the generalized Lorenz system. The result implies that more work needs to be done to apply generalized Lorenz system in secure communication. View full abstract»

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  • Receding Horizon Controls for Input-Delayed Systems

    Publication Year: 2008 , Page(s): 1746 - 1752
    Cited by:  Papers (7)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (271 KB) |  | HTML iconHTML  

    This paper presents a receding horizon control (RHC) for an unconstrained input-delayed system. To begin with, we derive a finite horizon optimal control for a quadratic cost function including two final weighting terms. The RHC is easily obtained by changing the initial and final times of the finite horizon optimal control. A linear matrix inequality (LMI) condition on two final weighting matrices is proposed to meet the cost monotonicity, under which the optimal cost on the horizon is monotonically nonincreasing with time and hence the asymptotical stability is guaranteed only if an observability condition is met. It is shown through simulation that the proposed RHC stabilizes the input-delayed system effectively and its performance can be tuned by adjusting weighting matrices with respect to the state and the input. 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

Full Aims & Scope

Meet Our Editors

Editor-in-Chief
P. J. Antsaklis
Dept. Electrical Engineering
University of Notre Dame