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Attenuation Level (attenuation + level)

Distribution by Scientific Domains
Engineering93%

Kinds of Attenuation Level

  • disturbance attenuation level
    		•
  • noise attenuation level
    		•
  • prescribed disturbance attenuation level
    		•

    Selected Abstracts

    Stability and H, performance of multiple-delay systems with successive delay components

    INTERNATIONAL JOURNAL OF ADAPTIVE CONTROL AND SIGNAL PROCESSING, Issue 8 2010
    Ge Guo
    Abstract This paper presents a new model for linear time-delay systems with multiple delayed states where each delay contains finite number of successive components with different time-varying properties, referred to as multiple-delay system with successive time-varying delay components (MDSSTDCs). General stability result and H, performance conditions, under which the MDSSTDCs are asymptotically stable with certain H, disturbance attenuation level, are derived by exploiting a general Lyapunov,Krasovskii functional and by making use of novel techniques for time-delay systems. The result is applied to two special types of time-delay systems frequently used in engineering applications and corresponding conditions for stability and H, performance are obtained. Copyright © 2010 John Wiley & Sons, Ltd. [source]

    Multiple input,multiple output adaptive feedback control strategies for the active headrest system: design and real-time implementation

    INTERNATIONAL JOURNAL OF ADAPTIVE CONTROL AND SIGNAL PROCESSING, Issue 10 2003
    Marek Pawelczyk
    Abstract In this article, multiple input,multiple output adaptive feedback control techniques for acoustic noise control in a headrest system are developed. The main goal underlying their design is to provide acoustic comfort to the user, i.e. high noise attenuation level over possibly large areas at the ears. Classical Internal Model Control system does not yield acceptable performance. An approach based on estimates of the residual noise at the ears is then proposed. It is shown that increase in the number of secondary sources to operate for one channel improves the performance. The experiments of tonal noise control are performed on an originally set-up prototype of the active headrest system. The results obtained are illustrated in the promoted form of distribution of zones of quiet. Copyright © 2003 John Wiley & Sons, Ltd. [source]

    Exponential H, filtering for switched linear systems with interval time-varying delay

    INTERNATIONAL JOURNAL OF ROBUST AND NONLINEAR CONTROL, Issue 5 2009
    Dong Wang
    Abstract This paper deals with the problem of exponential H, filtering for a class of continuous-time switched linear system with interval time-varying delay. The time delay under consideration includes two cases: one is that the time delay is differentiable and bounded with a constant delay-derivative bound, whereas the other is that the time delay is continuous and bounded. Switched linear filters are designed to ensure that the filtering error systems under switching signal with average dwell time are exponentially stable with a prescribed H, noise attenuation level. Based on the free-weighting matrix approach and the average dwell technology, delay-dependent sufficient conditions for the existence of such a filter are derived and formulated in terms of linear matrix inequalities (LMIs). By solving that corresponding LMIs, the desired filter parameterized matrices and the minimal average dwell time are obtained. Finally, two numerical examples are presented to demonstrate the effectiveness of the developed results. Copyright © 2008 John Wiley & Sons, Ltd. [source]

    LMI optimization approach to robust H, observer design and static output feedback stabilization for discrete-time nonlinear uncertain systems

    INTERNATIONAL JOURNAL OF ROBUST AND NONLINEAR CONTROL, Issue 3 2009
    Masoud Abbaszadeh
    Abstract A new approach for the design of robust H, observers for a class of Lipschitz nonlinear systems with time-varying uncertainties is proposed based on linear matrix inequalities (LMIs). The admissible Lipschitz constant of the system and the disturbance attenuation level are maximized simultaneously through convex multiobjective optimization. The resulting H, observer guarantees asymptotic stability of the estimation error dynamics and is robust against nonlinear additive uncertainty and time-varying parametric uncertainties. Explicit norm-wise and element-wise bounds on the tolerable nonlinear uncertainty are derived. Also, a new method for the robust output feedback stabilization with H, performance for a class of uncertain nonlinear systems is proposed. Our solution is based on a noniterative LMI optimization and is less restrictive than the existing solutions. The bounds on the nonlinear uncertainty and multiobjective optimization obtained for the observer are also applicable to the proposed static output feedback stabilizing controller. Copyright © 2008 John Wiley & Sons, Ltd. [source]

    A new finite sum inequality approach to delay-dependent H, control of discrete-time systems with time-varying delay

    INTERNATIONAL JOURNAL OF ROBUST AND NONLINEAR CONTROL, Issue 6 2008
    Xian-Ming Zhang
    Abstract This paper deals with delay-dependent H, control for discrete-time systems with time-varying delay. A new finite sum inequality is first established to derive a delay-dependent condition, under which the resulting closed-loop system via a state feedback is asymptotically stable with a prescribed H, noise attenuation level. Then, an iterative algorithm involving convex optimization is proposed to obtain a suboptimal H, controller. Finally, two numerical examples are given to show the effectiveness of the proposed method. Copyright © 2007 John Wiley & Sons, Ltd. [source]

    A further result of the nonlinear mixed H2/H, tracking control problem for robotic systems

    JOURNAL OF FIELD ROBOTICS (FORMERLY JOURNAL OF ROBOTIC SYSTEMS), Issue 1 2002
    C. Q. Huang
    The design objective of a mixed H2/H, control is to find the H2 optimal tracking control law under a prescribed disturbance attenuation level. With the help of the technique of completing the squares, a further result of the mixed H2/H, optimal tracking control problem is presented, by combining it with standard LQ optimal control technique. In this paper, only a nonlinear time-varying Riccati equation is required to solve the problem in the design procedure,instead of two coupled nonlinear time-varying Riccati equations, or two coupled linear algebraic Riccati-Iike equations,with some assumptions made regarding the weighting matrices in the existing results. A closed-form controller for the mixed H2/H, robotic tracking problem is simply constructed with a matrix inequality check. Moreover, it shows that the existing results are the special cases of these results. Finally, detailed comparison is performed by numerical simulation of a two-link robotic manipulator. © 2002 John Wiley & Sons, Inc. [source]

    Spectral shaping of acousto-optic tunable filter: A method to tune the bandwidth, wavelength, and attenuation

    MICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 9 2006
    S. Veeriah
    Abstract In this article, we presented a method, which will allow multiple parameter control of the 3-dB bandwidth, centre-notch wavelength, and attenuation level in a fiber-based acousto-optic tunable filter. The method basically involves the variation of the interaction length, RF frequency, and RF power on a single fiber device, to achieve multiple parameter tuning of the optical filter. © 2006 Wiley Periodicals, Inc. Microwave Opt Technol Lett 48: 1781,1785, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21783 [source]

    Robust sliding mode design for uncertain stochastic systems based on H, control method

    OPTIMAL CONTROL APPLICATIONS AND METHODS, Issue 2 2010
    Yugang Niu
    Abstract In this paper, the design problem of sliding mode control (SMC) is addressed for uncertain stochastic systems modeled by Itô differential equations. There exist the parameter uncertainties in both the state and input matrices, as well as the unmatched external disturbance. The key feature of this work is the integration of SMC method with H, technique such that the robust stochastic stability with a prescribed disturbance attenuation level , can be achieved. A sufficient condition for the existence of the desired sliding mode controller is obtained via linear matrix inequalities. The reachability of the specified sliding surface is proven. Finally, a numerical simulation example is presented to illustrate the proposed method. Copyright © 2009 John Wiley & Sons, Ltd. [source]

    Robust disturbance attenuation for discrete-time active fault tolerant control systems with uncertainties

    OPTIMAL CONTROL APPLICATIONS AND METHODS, Issue 2 2003
    Peng Shi
    Abstract The problems of stochastic stability and stochastic disturbance attenuation for a class of linear discrete-time systems are considered in this paper. The system under study is a state space model possessing two Markovian jump parameters: one is failure process and another is failure detection and isolation scheme. A controller is designed to guarantee the stochastic stability and a disturbance attenuation level. Robustness problems for the above system with norm-bounded parameter uncertainties are also investigated. It is shown that the uncertain system can be robustly stochastically stabilized and have a robust disturbance attenuation level for all admissible perturbations if a set of coupled Riccati inequalities has solutions. A numerical example is given to show the potential of the proposed technique. Copyright © 2003 John Wiley & Sons, Ltd. [source]

    Sampled-data H, control for networked systems with random packet dropouts,

    ASIAN JOURNAL OF CONTROL, Issue 4 2010
    Xiaosheng Fang
    Abstract This paper is concerned with the H, control problem for networked control systems (NCSs) with random packet dropouts. The NCS is modeled as a sampled-data system which involves a continuous plant, a digital controller, an event-driven holder and network channels. In this model, two types of packet dropouts in the sensor-to-controller (S/C) side and controller-to-actuator (C/A) side are both considered, and are described by two mutually independent stochastic variables satisfying the Bernoulli binary distribution. By applying an input/output delay approach, the sampled-data NCS is transformed into a continuous time-delay system with stochastic parameters. An observer-based control scheme is designed such that the closed-loop NCS is stochastically exponentially mean-square stable and the prescribed H, disturbance attenuation level is also achieved. The controller design problem is transformed into a feasibility problem for a set of linear matrix inequalities (LMIs). A numerical example is given to illustrate the effectiveness of the proposed design method. Copyright © 2010 John Wiley and Sons Asia Pte Ltd and Chinese Automatic Control Society [source]

    Delay distribution based robust H, control of networked control systems with uncertainties,

    ASIAN JOURNAL OF CONTROL, Issue 1 2010
    Chen Peng
    Abstract Network induced delay in networked control systems (NCS) is inherently non-uniformly distributed and behaves with multifractal nature. However, such network characteristics have not been well considered in NCS analysis and synthesis. Making use of the information of the statistical distribution of NCS network induced delay, a delay distribution based stochastic model is adopted to link Quality-of-Control and network Quality-of-Service for NCS with uncertainties. From this model together with a tighter bounding technology for cross terms, H, NCS analysis is carried out with significantly improved stability results. Furthermore, a memoryless H, controller is designed to stabilize the NCS and to achieve the prescribed disturbance attenuation level. Numerical examples are given to demonstrate the effectiveness of the proposed method. Copyright © 2009 John Wiley and Sons Asia Pte Ltd and Chinese Automatic Control Society [source]

    Robust decentralized H, control for interconnected descriptor systems with norm-bounded uncertainties,,

    ASIAN JOURNAL OF CONTROL, Issue 1 2009
    Ning Chen
    Abstract This paper considers a robust decentralized H, control problem for interconnected descriptor systems. The uncertainties are assumed to be time-invariant, norm-bounded, and existing in both the system and control input matrices. Our interest is focused on dynamic output feedback. A sufficient condition for an uncertain interconnected descriptor system to be robustly stabilizable H, control with a specified disturbance attenuation level is derived in terms of a nonlinear matrix inequality (NMI). A two-stage homotopy method is employed to solve the NMI iteratively. First, a decentralized controller for the nominal descriptor system is computed by imposing block-diagonal constraints on the coefficient matrices of the controller gradually. Then, the decentralized controller is gradually modified from the nominal descriptor system (without uncertainties) to the original system with uncertainties. On each stage, groups of variables are fixed alternately at the iterations to reduce the NMI to linear matrix inequalities (LMIs). An example is given to show the usefulness of this method. Copyright © 2009 John Wiley and Sons Asia Pte Ltd and Chinese Automatic Control Society [source]

    Robust tracking control design for uncertain robotic systems with persistent bounded disturbances

    ASIAN JOURNAL OF CONTROL, Issue 4 2008
    Chung-Shi Tseng
    Abstract In this study, a robust nonlinear L, - gain tracking control design for uncertain robotic systems is proposed under persistent bounded disturbances. The design objective is that the peak of the tracking error in time domain must be as small as possible under persistent bounded disturbances. Since the nonlinear L, - gain optimal tracking control cannot be solved directly, the nonlinear L, - gain optimal tracking problem is transformed into a nonlinear L, - gain tracking problem by given a prescribed disturbance attenuation level for the L, - gain tracking performance. To guarantee that the L, - gain tracking performance can be achieved for the uncertain robotic systems, a sliding-mode scheme is introduced to eliminate the effect of the parameter uncertainties. By virtue of the skew-symmetric property of the robotic systems, sufficient conditions are developed for solving the robust L, - gain tracking control problems in terms of an algebraic equation instead of a differential equation. The proposed method is simple and the algebraic equation can be solved analytically. Therefore, the proposed robust L, - gain tracking control scheme is suitable for practical control design of uncertain robotic systems. Copyright © 2008 John Wiley and Sons Asia Pte Ltd and Chinese Automatic Control Society [source]

    LMI APPROACH TO ROBUST FILTERING FOR DISCRETE TIME-DELAY SYSTEMS WITH NONLINEAR DISTURBANCES

    ASIAN JOURNAL OF CONTROL, Issue 2 2005
    Huijun Gao
    ABSTRACT This paper investigates the problem of robust filtering for a class of uncertain nonlinear discrete-time systems with multiple state delays. It is assumed that the parameter uncertainties appearing in all the system matrices reside in a polytope, and that the nonlinearities entering into both the state and measurement equations satisfy global Lipschitz conditions. Attention is focused on the design of robust full-order and reduced-order filters guaranteeing a prescribed noise attenuation level in an H, or l2 - l, sense with respect to all energy-bounded noise disturbances for all admissible uncertainties and time delays. Both delay-dependent and independent approaches are developed by using linear matrix inequality (LMI) techniques, which are applicable to systems either with or without a priori information on the size of delays. [source]

    State estimation for time-delay systems with probabilistic sensor gain reductions

    ASIA-PACIFIC JOURNAL OF CHEMICAL ENGINEERING, Issue 6 2008
    Xiao He
    Abstract This paper presents a new state estimation problem for a class of time-delay systems with probabilistic sensor gain faults. The sensor gain reductions are described by a stochastic variable that obeys the uniform distribution in a known interval [,, ,], which is a natural reflection of the probabilistic performance deterioration of sensors when gain reduction faults occur. Attention is focused on the design of a state estimator such that for all possible sensor faults and all external disturbances, the filtering error dynamic is asymptotically mean-square stable as well as fulfils a prescribed disturbance attenuation level. The existence of desired filters is proved to depend on the feasibility of a certain linear matrix inequality (LMI), and a numerical example is given to illustrate the effectiveness of the proposed design approach. Copyright © 2008 Curtin University of Technology and John Wiley & Sons, Ltd. [source]

    Practical implementation of multichannel adaptive filters based on FTF and AP algorithms for active control

    INTERNATIONAL JOURNAL OF ADAPTIVE CONTROL AND SIGNAL PROCESSING, Issue 2-3 2005
    Alberto González
    Abstract In this paper, multichannel affine projection (AP) algorithms and fast transversal filters (FTF) are introduced for active noise control. A comparative practical study of the mentioned algorithms with the filtered-X LMS (F-XLMS) and the recursive least squares (RLS) is presented for multichannel systems. This study is based on simulations using real data and is mainly focused on: their computational cost and memory load, their convergence properties, their stability and their ability to create quiet zones around listener ears. Simulations show that algorithms based on FTF exhibit a good trade-off between computational cost and convergence speed. On the other hand, those based on RLS are slightly faster but they present higher computational load and stability problems in their practical implementation. It has also been observed that algorithms based on low order AP algorithms present less computational cost than the FTF-based ones but a slightly slower convergence speed. Therefore these algorithms show a desirable behaviour and versatility for practical applications. Finally, results obtained in a real-time multichannel system validate the use of AP algorithms in practical applications as an alternative to the classical multichannel F-XLMS since they provide meaningful attenuation levels, lower convergence time and similar computational cost. Additionally, as simulations indicated, AP algorithm performance can be easily improved increasing its projection order and using fast versions. Copyright © 2004 John Wiley & Sons, Ltd. [source]