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Automatic Control, IEEE Transactions on

Issue 11 • Date Nov. 2005

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Displaying Results 1 - 25 of 48
  • Table of contents

    Publication Year: 2005 , Page(s): c1 - c4
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  • IEEE Transactions on Automatic Control publication information

    Publication Year: 2005 , Page(s): c2
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  • Scanning the issue

    Publication Year: 2005 , Page(s): 1637 - 1638
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  • Inverse optimal adaptive control for attitude tracking of spacecraft

    Publication Year: 2005 , Page(s): 1639 - 1654
    Cited by:  Papers (56)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (608 KB) |  | HTML iconHTML  

    The attitude tracking control problem of a rigid spacecraft with external disturbances and an uncertain inertia matrix is addressed using the adaptive control method. The adaptive control laws proposed in this paper are optimal with respect to a family of cost functionals. This is achieved by the inverse optimality approach, without solving the associated Hamilton-Jacobi-Isaacs partial differential (HJIPD) equation directly. The design of the optimal adaptive controllers is separated into two stages by means of integrator backstepping, and a control Lyapunov argument is constructed to show that the inverse optimal adaptive controllers achieve H disturbance attenuation with respect to external disturbances and global asymptotic convergence of tracking errors to zero for disturbances with bounded energy. The convergence of adaptive parameters is also analyzed in terms of invariant manifold. Numerical simulations illustrate the performance of the proposed control algorithms. View full abstract»

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  • Set membership prediction of nonlinear time series

    Publication Year: 2005 , Page(s): 1655 - 1669
    Cited by:  Papers (10)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (696 KB) |  | HTML iconHTML  

    In this paper, a prediction method for nonlinear time series based on a set membership (SM) approach is proposed. The method does not require the choice of the functional form of the model used for prediction, but assumes a bound on the rate of variation of the regression function defining the model. At the contrary, most of the existing prediction methods need the choice of a functional form of the regression function or of state equations (piecewise linear, quadratic, etc.) and this choice is usually the result of heuristic searches. These searches may be quite time consuming, and lead only to approximate model structures, whose errors may be responsible of bad propagation of prediction errors, especially for the multistep ahead prediction. Moreover, the method proposed in this paper assumes only that the noise is bounded, in contrast with statistical approaches, which rely on noise assumptions such as stationarity, ergodicity, uncorrelation, type of distribution, etc. The validity of these assumptions may be difficult to be reliably tested in many applications and is certainly lost in presence of approximate modeling. In the present SM approach, using a result developed in a previous paper, the values of the bounds on the gradient of the regression function and on the noise can be suitably assessed to verify the validity tests. Two almost optimal prediction algorithms are then derived, the second one having improved optimal properties over the first one, at the expense of an increased computational complexity. The method is tested and compared with other literature methods on the well-known Wolf Sunspot Numbers series, widely used in the time series literature as a benchmark test, and on the prediction of vertical dynamics of vehicles with controlled suspensions. A simulation example is also presented to investigate how much conservative the SM approach may be in the most adverse situation where data are generated by a linear autoregressive (AR) model driven by i.i.d. gaussian white noise and the SM prediction is compared with the optimal statistical predictor, which makes use of the exact assumptions. View full abstract»

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  • Predictive control of switched nonlinear systems with scheduled mode transitions

    Publication Year: 2005 , Page(s): 1670 - 1680
    Cited by:  Papers (114)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (464 KB) |  | HTML iconHTML  

    In this work, a predictive control framework is proposed for the constrained stabilization of switched nonlinear systems that transit between their constituent modes at prescribed switching times. The main idea is to design a Lyapunov-based predictive controller for each constituent mode in which the switched system operates and incorporate constraints in the predictive controller design which upon satisfaction ensure that the prescribed transitions between the modes occur in a way that guarantees stability of the switched closed-loop system. This is achieved as follows: For each constituent mode, a Lyapunov-based model predictive controller (MPC) is designed, and an analytic bounded controller, using the same Lyapunov function, is used to explicitly characterize a set of initial conditions for which the MPC, irrespective of the controller parameters, is guaranteed to be feasible, and hence stabilizing. Then, constraints are incorporated in the MPC design which, upon satisfaction, ensure that: 1) the state of the closed-loop system, at the time of the transition, resides in the stability region of the mode that the system is switched into, and 2) the Lyapunov function for each mode is nonincreasing wherever the mode is reactivated, thereby guaranteeing stability. The proposed control method is demonstrated through application to a chemical process example. View full abstract»

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  • A unified approach to controller design for achieving ISS and related properties

    Publication Year: 2005 , Page(s): 1681 - 1697
    Cited by:  Papers (10)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (880 KB) |  | HTML iconHTML  

    A unified approach to the design of controllers achieving various specified input-to-state stability (ISS) like properties is presented. Both full state and measurement feedback cases are considered. Synthesis procedures based on dynamic programming are given using the recently developed results on controller synthesis to achieve uniform l bound. Our results provide a link between the ISS literature and the nonlinear H design literature. View full abstract»

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  • The sector bound approach to quantized feedback control

    Publication Year: 2005 , Page(s): 1698 - 1711
    Cited by:  Papers (309)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (448 KB) |  | HTML iconHTML  

    This paper studies a number of quantized feedback design problems for linear systems. We consider the case where quantizers are static (memoryless). The common aim of these design problems is to stabilize the given system or to achieve certain performance with the coarsest quantization density. Our main discovery is that the classical sector bound approach is nonconservative for studying these design problems. Consequently, we are able to convert many quantized feedback design problems to well-known robust control problems with sector bound uncertainties. In particular, we derive the coarsest quantization densities for stabilization for multiple-input-multiple-output systems in both state feedback and output feedback cases; and we also derive conditions for quantized feedback control for quadratic cost and H performances. View full abstract»

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  • Efficiency loss in a network resource allocation game: the case of elastic supply

    Publication Year: 2005 , Page(s): 1712 - 1724
    Cited by:  Papers (18)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (480 KB) |  | HTML iconHTML  

    We consider a resource allocation problem where individual users wish to send data across a network to maximize their utility, and a cost is incurred at each link that depends on the total rate sent through the link. It is known that as long as users do not anticipate the effect of their actions on prices, a simple proportional pricing mechanism can maximize the sum of users' utilities minus the cost (called aggregate surplus). Continuing previous efforts to quantify the effects of selfish behavior in network pricing mechanisms, we consider the possibility that users anticipate the effect of their actions on link prices. Under the assumption that the links' marginal cost functions are convex, we establish existence of a Nash equilibrium. We show that the aggregate surplus at a Nash equilibrium is no worse than a factor of 4√2-5 times the optimal aggregate surplus; thus, the efficiency loss when users are selfish is no more than approximately 34%. View full abstract»

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  • Controllability of nonlinear time-varying systems: applications to spacecraft attitude control using magnetic actuation

    Publication Year: 2005 , Page(s): 1725 - 1735
    Cited by:  Papers (13)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (368 KB) |  | HTML iconHTML  

    Nonlinear controllability theory is applied to the time-varying attitude dynamics of a magnetically actuated spacecraft in a Keplerian orbit in the geomagnetic field. First, sufficient conditions for accessibility, strong accessibility and controllability of a general time-varying system are presented. These conditions involve application of Lie-algebraic rank conditions to the autonomous extended system obtained by augmenting the state of the original time-varying system by the time variable, and require the rank conditions to be checked only on the complement of a finite union of level sets of a finite number of smooth functions. At each point of each level set, it is sufficient to verify escape conditions involving Lie derivatives of the functions defining the level sets along linear combinations over smooth functions of vector fields in the accessibility algebra. These sufficient conditions are used to show that the attitude dynamics of a spacecraft actuated by three magnetic actuators and subjected to a general time-varying magnetic field are strongly accessible if the magnetic field and its time derivative are linearly independent at every instant. In addition, if the magnetic field is periodic in time, then the attitude dynamics of the spacecraft are controllable. These results are used to show that the attitude dynamics of a spacecraft actuated by three magnetic actuators in a closed Keplerian orbit in a nonrotating dipole approximation of the geomagnetic field are strongly accessible and controllable if the orbital plane does not coincide with the geomagnetic equatorial plane. View full abstract»

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  • Receding-horizon estimation for switching discrete-time linear systems

    Publication Year: 2005 , Page(s): 1736 - 1748
    Cited by:  Papers (35)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (504 KB) |  | HTML iconHTML  

    Receding-horizon state estimation is addressed for a class of discrete-time systems that may switch among different modes taken from a finite set. The system and measurement equations for each mode are assumed to be linear and perfectly known, but the current mode of the system is unknown, the state variables are not perfectly measurable and are affected by disturbances. The system mode is regarded as an unknown discrete state to be estimated together with the continuous state vector. Observability conditions are found to distinguish the system mode in the presence of bounded system and measurement noises. These results allow one to construct an estimator that relies on the combination of the identification of the discrete state with the estimation of the state variables by minimizing a receding-horizon quadratic cost function. The convergence properties of such an estimator are studied, and simulation results are reported to show the effectiveness of the proposed approach. View full abstract»

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  • Adaptive optimization of least-squares tracking algorithms: with applications to adaptive antenna arrays for randomly time-varying mobile communications systems

    Publication Year: 2005 , Page(s): 1749 - 1760
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (560 KB) |  | HTML iconHTML  

    Adaptive antenna arrays are used for reducing the effects of interference and increasing capacity in mobile communications systems. Typical algorithms recursively compute the antenna weights that minimize the weighted error function (at discrete times kh, k=1,2,..., for a sampling interval h) σl=1kαk-l[el(W)]2, where el(W) is a measure of the reception error at time lh with antenna weight vector W, and α<1. The forgetting factor α<1 allows tracking as conditions change and the minimization is used only to get the weights. The average detection error rate depends heavily on the chosen value of α, whose optimal value can change rapidly in time, perhaps significantly in seconds. We add another adaptive loop that tracks the optimal value of α and greatly improves the operation when the environment is randomly time-varying. The additional adaptive loop is based on an approximation to a natural "gradient descent" method. The algorithm is practical and can improve the performance considerably. In terms of average detection error rates and for all of the scenarios tested, the new system tracks the optimal value of α well, and always performs better (sometimes much better) than the original algorithm that uses any fixed value of α. Although the initial motivation arises in adaptive antennas, the method can be used to improve algorithms for tracking parameters of time-varying nonlinear systems, where similar issues are involved. View full abstract»

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  • Selection of the learning gain matrix of an iterative learning control algorithm in presence of measurement noise

    Publication Year: 2005 , Page(s): 1761 - 1774
    Cited by:  Papers (14)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (496 KB) |  | HTML iconHTML  

    Arbitrary high precision output tracking is one of the most desirable control objectives found in industrial applications regardless of measurement errors. The main purpose of this paper is to supply to the iterative learning control (ILC) designer guidelines to select the corresponding learning gain in order to achieve this control objective. For example, if certain conditions are met, then it is necessary for the learning gain to converge to zero in the learning iterative domain. In particular, this paper presents necessary and sufficient conditions for boundedness of trajectories and uniform tracking in presence of measurement noise and a class of random reinitialization errors for a simple ILC algorithm. The system under consideration is a class of discrete-time affine nonlinear systems with arbitrary relative degree and arbitrary number of system inputs and outputs. The state function does not need to satisfy a Lipschitz condition. This work also provides a recursive algorithm that generates the appropriate learning gain functions that meet the arbitrary high precision output tracking objective. The resulting tracking output error is shown to converge to zero at a rate inversely proportional to square root of the number of learning iterations in presence of measurement noise and a class of reinitialization errors. Two illustrative numerical examples are presented. View full abstract»

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  • Virtual Grouping based adaptive actuator failure compensation for MIMO nonlinear systems

    Publication Year: 2005 , Page(s): 1775 - 1780
    Cited by:  Papers (14)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (288 KB) |  | HTML iconHTML  

    A new control design technique called virtual grouping is presented to handle actuator redundancy and failures for multiple-input-mutliple-output (MIMO) systems, enlarging the set of compensable actuator failures. An adaptive compensation scheme is thus developed for a class of nonlinear MIMO systems to ensure closed-loop signal boundedness and asymptotic output tracking despite unknown actuator failures. Simulation results are given to show the effectiveness of the adaptive design. View full abstract»

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  • Global stability analysis of neural networks with multiple time varying delays

    Publication Year: 2005 , Page(s): 1781 - 1785
    Cited by:  Papers (27)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (216 KB) |  | HTML iconHTML  

    In this note, we study the equilibrium and stability properties of neural networks with time varying delays. Our main results give sufficient conditions for the existence, uniqueness and global asymptotic stability of the equilibrium point. The proposed conditions establish the relationships between network parameters of the neural systems and the delay parameters. The obtained results are applicable to all continuous nonmonotonic neuron activation functions and do not require the interconnection matrices to be symmetric. Some examples are also presented to compare our results with the previous results derived in the literature. View full abstract»

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  • Second-order sliding-mode observer for mechanical systems

    Publication Year: 2005 , Page(s): 1785 - 1789
    Cited by:  Papers (180)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (256 KB) |  | HTML iconHTML  

    The super-twisting second-order sliding-mode algorithm is modified in order to design a velocity observer for uncertain mechanical systems. The finite time convergence of the observer is proved. Thus, the observer can be designed independently of the controller. A discrete version of the observer is considered and the corresponding accuracy is estimated. View full abstract»

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  • Maximizing the stability radius of a set of systems under real-time scheduling constraints

    Publication Year: 2005 , Page(s): 1790 - 1795
    Cited by:  Papers (12)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (272 KB) |  | HTML iconHTML  

    We address the problem of synthesising real-time embedded controllers taking into account constraints deriving from the implementation platform, thus exploring the relation between the processor's time (or "attention") devoted to different control tasks and the overall robustness of the resulting design. Assuming a time-triggered model of computation for tasks controlling a set of independent systems and a real-time preemptive scheduling policy managing a single CPU processor board, we deal with two problems: 1) deciding whether a performance specification can be attained on a candidate platform, 2) optimising performance on a platform. The considered performance metric is the minimum stability radius attained over the different feedback loops. View full abstract»

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  • Time domain solution to descriptor variable systems

    Publication Year: 2005 , Page(s): 1796 - 1799
    Cited by:  Papers (7)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (168 KB) |  | HTML iconHTML  

    The time domain solution to the fast subsystem of the descriptor variable system of the form Ex˙=Ax+Bu with E singular is given by Laplace inverse transformation. A new and significant feature of the solution is that it contains impulse terms excited by the values of sufficiently smooth input u and its derivatives at the initial time point. Based on the solution, the notions of consistent initial conditions, classical solutions and impulse-free solutions are discussed perfectly. The impulse controllability is discussed also which admits the same interpretation as the controllability at infinity in frequency domain. View full abstract»

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  • Output regulation of periodic signals for DPS: an infinite-dimensional signal Generator

    Publication Year: 2005 , Page(s): 1799 - 1804
    Cited by:  Papers (9)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (264 KB) |  | HTML iconHTML  

    In this note, we consider output regulation and disturbance rejection of periodic signals via state feedback in the setting of exponentially stabilizable linear infinite-dimensional systems. We show that if an infinite-dimensional exogenous system is generating periodic reference signals, solvability of the state feedback regulation problem is equivalent to solvability of the so called equations. This result allows us to consider asymptotic tracking of periodic reference signals which only have absolutely summable Fourier coefficients, while in related existing work the reference signals are confined to be infinitely smooth. We also discuss solution of the regulator equations and construct the actual feedback law to achieve output regulation in the single-input-single-output (SISO) case: The output regulation problem is solvable if the transfer function of the stabilized plant does not have zeros at the frequencies iωn of the periodic reference signals and if the sequence ([CR(iωn, A+BK)B]-1 ×(Qφn-CR(iωn, A+BK)Pφn)) n∈z∈ln2. A one-dimensional heat equation is used as an illustrative example. View full abstract»

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  • Evolutionary policy iteration for solving Markov decision processes

    Publication Year: 2005 , Page(s): 1804 - 1808
    Cited by:  Papers (16)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (240 KB) |  | HTML iconHTML  

    We propose a novel algorithm called evolutionary policy iteration (EPI) for solving infinite horizon discounted reward Markov decision processes. EPI inherits the spirit of policy iteration but eliminates the need to maximize over the entire action space in the policy improvement step, so it should be most effective for problems with very large action spaces. EPI iteratively generates a "population" or a set of policies such that the performance of the "elite policy" for a population monotonically improves with respect to a defined fitness function. EPI converges with probability one to a population whose elite policy is an optimal policy. EPI is naturally parallelizable and along this discussion, a distributed variant of PI is also studied. View full abstract»

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  • Reduced-complexity nonlinear H control of discrete-time systems

    Publication Year: 2005 , Page(s): 1808 - 1811
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (224 KB) |  | HTML iconHTML  

    In this note, we describe a reduced-complexity solution to the nonlinear H control problem. This reduction applies to systems where some of the states are perfectly known, and is an intermediate problem between full state feedback and the standard measurement feedback problem. The reduction of computational complexity is significant and of practical importance. Online implementation is feasible with 2003 computer technology for a range of practical engineering design problems. View full abstract»

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  • Quasi-continuous high-order sliding-mode controllers

    Publication Year: 2005 , Page(s): 1812 - 1816
    Cited by:  Papers (124)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (240 KB) |  | HTML iconHTML  

    A universal finite-time-convergent controller is developed capable to control the output of any uncertain single-input-single-output system with a known permanent relative degree r. The tracking error σ is steered to zero by means of a control dependent only on σ, σ˙, ..., σ(r-1) and continuous everywhere except the set σ=σ˙=···=σ(r-1)=0. A robust output-feedback controller version provides for the tracking accuracy proportional to the sampling noise magnitude. View full abstract»

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  • Global compensation of unknown sinusoidal disturbances for a class of nonlinear nonminimum phase systems

    Publication Year: 2005 , Page(s): 1816 - 1822
    Cited by:  Papers (11)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (312 KB) |  | HTML iconHTML  

    A class of output feedback stabilizable nonlinear systems with known output dependent nonlinearities and affected by unknown sinusoidal disturbances is considered: Nonminimum phase systems are also allowed. The problem of designing a global output feedback compensator which drives the state of the system exponentially to zero is solved when the disturbance consists of a known number of biased sinusoids with any unknown bias, magnitudes, phases, and frequencies. View full abstract»

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  • An extension of the linear regulator for degenerate diffusions

    Publication Year: 2005 , Page(s): 1822 - 1826
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (240 KB) |  | HTML iconHTML  

    We study an extended stochastic control problem of the linear regulator for degenerate diffusions. We establish the existence of a classical solution of the degenerate Bellman equation by the technique of viscosity solutions, and the optimal policy is shown to exist from the optimality conditions. View full abstract»

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  • Robust stability of quasi-polynomials and the finite inclusions theorem

    Publication Year: 2005 , Page(s): 1826 - 1831
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (304 KB) |  | HTML iconHTML  

    A semianalytic tool for the study of the robust stability of quasi-polynomials of retarded type is presented. The approach is based on graphical methods. The finite Nyquist theorem for polynomials is extended to the case of quasi-polynomials with the help of a novel approach. The finite inclusions theorem for quasi-polynomials is derived. It allows to conclude on the stability of polytopic families of quasi-polynomials from a finite number of testing values. 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