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High-gain Observer (high-gain + observer)
Selected AbstractsDual high-gain-based adaptive output-feedback control for a class of nonlinear systems,INTERNATIONAL JOURNAL OF ADAPTIVE CONTROL AND SIGNAL PROCESSING, Issue 1 2008P. Krishnamurthy Abstract We propose an adaptive output-feedback controller for a general class of nonlinear triangular (strict-feedback-like) systems. The design is based on our recent results on a new high-gain control design approach utilizing a dual high-gain observer and controller architecture with a dynamic scaling. The technique provides strong robustness properties and allows the system class to contain unknown functions dependent on all states and involving unknown parameters (with no magnitude bounds required). Unlike our earlier result on this problem where a time-varying design of the high-gain scaling parameter was utilized, the technique proposed here achieves an autonomous dynamic controller by introducing a novel design of the observer, the scaling parameter, and the adaptation parameter. This provides a time-invariant dynamic output-feedback globally asymptotically stabilizing solution for the benchmark open problem proposed in our earlier work with no magnitude bounds or sign information on the unknown parameter being necessary. Copyright © 2007 John Wiley & Sons, Ltd. [source] Global stabilization of uncertain stochastic nonlinear time-delay systems by output feedbackINTERNATIONAL JOURNAL OF ROBUST AND NONLINEAR CONTROL, Issue 9 2008Peng Cui Abstract Constructive control techniques have been proposed for controlling strict feedback (lower triangular form) stochastic nonlinear systems with a time-varying time delay in the state. The uncertain nonlinearities are assumed to be bounded by polynomial functions of the outputs multiplied by unmeasured states or delayed states. The delay-independent output feedback controller making the closed-loop system globally asymptotically stable is explicitly constructed by using a linear dynamic high-gain observer in combination with a linear dynamic high-gain controller. A simulation example is given to demonstrate the effectiveness of the proposed design procedure. Copyright © 2007 John Wiley & Sons, Ltd. [source] A global observer for autonomous systems with bounded trajectoriesINTERNATIONAL JOURNAL OF ROBUST AND NONLINEAR CONTROL, Issue 12 2007Hao Lei The problem of global observer design for autonomous systems is investigated in this paper. A constructive approach is presented for the explicit design of global observers for completely observable systems whose solution trajectories are bounded from any initial condition. Since the bound of a solution trajectory depends on the initial condition and is therefore not known a priori, the idea of universal control is employed to tune the observer gains on-line, achieving global asymptotic convergence of the proposed high-gain observer. Copyright © 2007 John Wiley & Sons, Ltd. [source] Decentralized nonlinear robust control of UAVs in close formationINTERNATIONAL JOURNAL OF ROBUST AND NONLINEAR CONTROL, Issue 11 2003Sahjendra N. Singh Abstract This paper treats the design of a decentralized nonlinear robust control system for formation flying of multiple unmanned aerial vehicles (UAVs). In close formation, it is assumed that vortex of any UAV affects the motion of all the UAVs behind it. The forces produced by these vortices are complex functions of relative position co-ordinates of the UAVs. In this paper, these forces are treated as unknown functions, which cannot be parameterized. Since the system is not invertible in the wind axes system, a simplified co-ordinate system obtained from the wind axes system for which the velocity roll (bank angle) is zero, is considered for the design of the control system. A nonlinear robust control system for the separation trajectory control of the wing aircraft in the simplified wind coordinate system is derived. Uncertain functions and unmeasured variables are estimated using a high-gain observer for the synthesis of the control system. Each wing UAV synthesizes its control law using its own state variables and the relative position of the preceding UAV with respect to the wing UAV. Thus the control system is decentralized since each UAV has to communicate (depending on sensors for position measurement) with at most one (preceding) UAV, and no data transmission from the remaining vehicles is required. Simulation results for two UAVs are presented which show precise separation trajectory control of each wing UAV in spite of the presence of unknown and unstructured vortex forces, while the lead aircraft maneuvers. Furthermore, these results confirm that when the wing aircraft is positioned properly in the vortex of the lead aircraft, it experiences reduction in its required flight power. Copyright © 2003 John Wiley & Sons, Ltd. [source] Output feedback stabilization of constrained systems with nonlinear predictive controlINTERNATIONAL JOURNAL OF ROBUST AND NONLINEAR CONTROL, Issue 3-4 2003Rolf Findeisen Abstract We present an output feedback stabilization scheme for uniformly completely observable nonlinear MIMO systems combining nonlinear model predictive control (NMPC) and high-gain observers. The control signal is recalculated at discrete sampling instants by an NMPC controller using a system model for the predictions. The state information necessary for the prediction is provided by a continuous time high-gain observer. The resulting ,optimal' control signal is open-loop implemented until the next sampling instant. With the proposed scheme semi-global practical stability is achieved. That is, for initial conditions in any compact set contained in the region of attraction of the NMPC state feedback controller, the system states will enter any small set containing the origin, if the high-gain observers is sufficiently fast and the sampling time is small enough. In principle the proposed approach can be used for a variety of state feedback NMPC schemes. Copyright © 2003 John Wiley & Sons, Ltd. [source] A lab-scale reaction calorimeter for olefin polymerizationTHE CANADIAN JOURNAL OF CHEMICAL ENGINEERING, Issue 5 2010Virginie F. Tisse A reaction calorimeter was built to follow slurry-phase polymerizations of ethylene using different types of supported catalysts. It was shown that heat flow calorimetry, employing a high-gain observer for the evaluation of the initial conditions was an extremely useful tool for the measurement of on-line reaction rates, and a study of the influence of different parameters such as the stirring rate or solid content in real time. It was shown that if one uses solid contents under 30% (volume) then it is not necessary to account for the influence of this quantity on the overall heat transfer coefficient. Un calorimètre de réaction a été construit pour le suivi des polymérisations des phases de suspension de l'éthylène utilisant différents types de catalyseurs adaptés. Il a été démontré que la calorimétrie du flux thermique, utilisant un observateur à gain élevé pour l'évaluation des conditions initiales s'est avérée un outil extrêmement utile pour mesurer les taux de réaction en ligne, et pour l'étude en temps réel de l'influence de différents paramètres tels que la vitesse d'agitation ou le contenu en matière solide. Il a été démontré que si l'on utilise la matière solide en dessous de 30% (en termes de volume), alors il n'est pas nécessaire de prendre en compte l'influence de cette quantité sur le coefficient global de transfert thermique. Can. J. Chem. Eng. © 2010 Canadian Society for Chemical Engineering [source] Experimental validation of a high-gain observer for composition estimation in an ethanol,water distillation columnASIA-PACIFIC JOURNAL OF CHEMICAL ENGINEERING, Issue 6 2009A. C. Téllez-Anguiano Abstract In this paper a high-gain observer used to estimate the product compositions in a distillation column for a non-ideal mixture (ethanol,water) through the tray temperature measurements is presented. The design of this observer is based on a simplified mathematical model. One of the main advantages of this observer is its constant gain, therefore its tuning depends only on choosing a few constant parameters satisfying some simple algebraic inequalities. The effectiveness of the proposed method is demonstrated through on-line experiments in a distillation pilot plant. Copyright © 2009 Curtin University of Technology and John Wiley & Sons, Ltd. [source] Output feedback stabilization of constrained systems with nonlinear predictive controlINTERNATIONAL JOURNAL OF ROBUST AND NONLINEAR CONTROL, Issue 3-4 2003Rolf Findeisen Abstract We present an output feedback stabilization scheme for uniformly completely observable nonlinear MIMO systems combining nonlinear model predictive control (NMPC) and high-gain observers. The control signal is recalculated at discrete sampling instants by an NMPC controller using a system model for the predictions. The state information necessary for the prediction is provided by a continuous time high-gain observer. The resulting ,optimal' control signal is open-loop implemented until the next sampling instant. With the proposed scheme semi-global practical stability is achieved. That is, for initial conditions in any compact set contained in the region of attraction of the NMPC state feedback controller, the system states will enter any small set containing the origin, if the high-gain observers is sufficiently fast and the sampling time is small enough. In principle the proposed approach can be used for a variety of state feedback NMPC schemes. Copyright © 2003 John Wiley & Sons, Ltd. [source] | |||||||||||||