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Nonlinear Control (nonlinear + control)

Distribution by Scientific Domains

Engineering	81%

Kinds of Nonlinear Control

robust nonlinear control

Terms modified by Nonlinear Control

nonlinear control system

Selected Abstracts

Central suboptimal H, filter design for nonlinear polynomial systems

INTERNATIONAL JOURNAL OF ADAPTIVE CONTROL AND SIGNAL PROCESSING, Issue 10 2009
Michael Basin
Abstract This paper presents the central finite-dimensional H, filter for nonlinear polynomial systems, which is suboptimal for a given threshold , with respect to a modified Bolza,Meyer quadratic criterion including the attenuation control term with the opposite sign. In contrast to the previously obtained results, the paper reduces the original H, filtering problem to the corresponding optimal H2 filtering problem, using the technique proposed in (IEEE Trans. Automat. Control 1989; 34:831,847). The paper presents the central suboptimal H, filter for the general case of nonlinear polynomial systems based on the optimal H2 filter given in (Int. J. Robust Nonlinear Control 2006; 16:287,298). The central suboptimal H, filter is also derived in a closed finite-dimensional form for third (and less) degree polynomial system states. Numerical simulations are conducted to verify performance of the designed central suboptimal filter for nonlinear polynomial systems against the central suboptimal H, filter available for the corresponding linearized system. Copyright © 2008 John Wiley & Sons, Ltd. [source]

Robust adaptive fuzzy semi-decentralized control for a class of large-scale nonlinear systems using input,output linearization concept

INTERNATIONAL JOURNAL OF ROBUST AND NONLINEAR CONTROL, Issue 1 2010
H. Yousef
Abstract Stable direct and indirect adaptive fuzzy controllers based on input,output linearization concept are presented for a class of interconnected nonlinear systems with unknown nonlinear subsystems and interconnections. The interconnected nonlinear systems are represented not only in the canonical forms as in Yousef et al. (Int. J. Robust Nonlinear Control 2006; 16: 687,708) but also in the general forms. Hybrid adaptive fuzzy robust tracking control schemes that are based on a combination of an H, tracking theory and fuzzy control design are developed. In the proposed control schemes, all the states and signals are bounded and an H, tracking control performance is guaranteed without imposing any constraints or assumptions about the interconnections. Extensive simulation on the tracking of a two-link rigid robot manipulator and a numerical example verify the effectiveness of the proposed algorithms. Copyright © 2009 John Wiley & Sons, Ltd. [source]

A combined first-/second-order sliding-mode technique in the control of a jet-propelled vehicle

INTERNATIONAL JOURNAL OF ROBUST AND NONLINEAR CONTROL, Issue 4-5 2008
G. Bartolini
Abstract This note concerns the design and practical implementation of a position/attitude sliding-mode controller for a surface vessel prototype. The prototype is equipped with a special, recently patented (Italian Patent, 2005), propulsion system based on hydro-jets with adjustable output section. The sliding-mode control design is based on the combination between three instances of a second-order sliding-mode velocity observer (Automatica 1998; 34:379,384) and a simplex-based sliding-mode controller (Int. J. Robust Nonlinear Control 1997; 7(4):321,335). We first describe the structure and the working principle of the prototype. Then, we detail the derivation of the motion observer/controller. Finally, we discuss the major implementation issues and show some experimental results. Copyright © 2007 John Wiley & Sons, Ltd. [source]

Adaptive backstepping integral control of a small-scale helicopter for airdrop missions,

ASIAN JOURNAL OF CONTROL, Issue 4 2010
Chi-Tai Lee
Abstract This paper presents an adaptive Lyapunov-based controller with integral action for small-scale helicopters carrying out airdrop missions. The proposed controller is designed via adaptive backstepping. Unlike the approximate modeling approaches, where the coupling effect of the helicopter is neglected, the proposed method is developed according to a complete dynamic model such that the closed-loop helicopter system is guaranteed to be globally ultimately bounded. Two numerical simulations with airdrops are conducted to exemplify the merits of the proposed controller. Through simulation results, the proposed control method is shown to outperform the well-known controller in Mahony and Hamel, Int. J. Robust Nonlinear Control, Vol. 14, No. (12), pp. 1035,1059 (2004). Copyright © 2010 John Wiley and Sons Asia Pte Ltd and Chinese Automatic Control Society [source]

Nonlinear control of power converters: a new adaptive backstepping approach,

ASIAN JOURNAL OF CONTROL, Issue 6 2009
Jun Fu
Abstract This paper proposes a new backstepping approach to nonlinear control of power converters which is attracting considerable attention in both theoretical research and practical applications. The main difference between the proposed algorithm and the existing classical adaptive backstepping method in the literature is that the adaptation mechanism does not follow the certainty-equivalence principle. Copyright © 2009 John Wiley and Sons Asia Pte Ltd and Chinese Automatic Control Society [source]

Nonlinear controls for a class of discrete-time bilinear systems

INTERNATIONAL JOURNAL OF ROBUST AND NONLINEAR CONTROL, Issue 11 2003
Min-Shin Chen
Abstract For a discrete-time neutrally stable bilinear system, a nonlinear state feedback control based on the passivity design has been proposed to stabilize the system globally and asymptotically. This paper shows that the decay rate resulting from the passivity control is not exponential, and the system's response speed becomes very sluggish asymptotically. A ,normalized' nonlinear control is therefore proposed to achieve exponential stability. The new exponentially stabilizing control not only improves the system's response speed, but also enhances the system's robustness against small parametric perturbations. Copyright © 2003 John Wiley & Sons, Ltd. [source]

Flexible models with evolving structure

INTERNATIONAL JOURNAL OF INTELLIGENT SYSTEMS, Issue 4 2004
Plamen P. Angelov
A type of flexible model in the form of a neural network (NN) with evolving structure is discussed in this study. We refer to models with amorphous structure as flexible models. There is a close link between different types of flexible models: fuzzy models, fuzzy NN, and general regression models. All of them are proven universal approximators and some of them [Takagi-Sugeno fuzzy model with singleton outputs and radial-basis function] are interchangeable. The evolving NN (eNN) considered here makes use of the recently introduced on-line approach to identification of Takagi-Sugeno fuzzy models with evolving structure (eTS). Both TS and eNN differ from the other model schemes by their gradually evolving structure as opposed to the fixed structure models, in which only parameters are subject to optimization or adaptation. The learning algorithm is incremental and combines unsupervised on-line recursive clustering and supervised recursive on-line output parameter estimation. eNN has potential in modeling, control (if combined with the indirect learning mechanism), fault detection and diagnostics etc. Its computational efficiency is based on the noniterative and recursive procedure, which combines the Kalman filter with proper initializations and on-line unsupervised clustering. The eNN has been tested with data from a real air-conditioning installation. Applications to real-time adaptive nonlinear control, fault detection and diagnostics, performance analysis, time-series forecasting, knowledge extraction and accumulation, are possible directions of their use in future research. © 2004 Wiley Periodicals, Inc. [source]

Robust tracking control for a class of MIMO nonlinear systems with measurable output feedback

INTERNATIONAL JOURNAL OF ROBUST AND NONLINEAR CONTROL, Issue 1 2008
Ya-Jun Pan
Abstract This paper proposes a robust output feedback controller for a class of nonlinear systems to track a desired trajectory. Our main goal is to ensure the global input-to-state stability (ISS) property of the tracking error nonlinear dynamics with respect to the unknown structural system uncertainties and external disturbances. Our approach consists of constructing a nonlinear observer to reconstruct the unavailable states, and then designing a discontinuous controller using a back-stepping like design procedure to ensure the ISS property. The observer design is realized through state transformation and there is only one parameter to be determined. Through solving a Hamilton,Jacoby inequality, the nonlinear control law for the first subsystem specifies a nonlinear switching surface. By virtue of nonlinear control for the first subsystem, the resulting sliding manifold in the sliding phase possesses the desired ISS property and to certain extent the optimality. Associated with the new switching surface, the sliding mode control is applied to the second subsystem to accomplish the tracking task. As a result, the tracking error is bounded and the ISS property of the whole system can be ensured while the internal stability is also achieved. Finally, an example is presented to show the effectiveness of the proposed scheme. Copyright © 2007 John Wiley & Sons, Ltd. [source]

Modelling, identification, and control of a spherical particle trapped in an optical tweezer

INTERNATIONAL JOURNAL OF ROBUST AND NONLINEAR CONTROL, Issue 16 2005
A. Ranaweera
Abstract We provide an introduction to modelling, identification, and control of a spherical particle trapped in an optical tweezer. The main purpose is to analyse the properties of an optical tweezer from a control systems point of view. By representing the non-inertial dynamics of a trapped particle using a stochastic differential equation, we discuss probability distributions and compute first mean exit times. Within the linear trapping region, experimentally measured mean passage times for a 9.6-µm diameter polystyrene bead show close agreement with theoretical calculations. We apply a recursive least squares method to a trapped 9.6-µm diameter polystyrene bead to study the possibility of obtaining faster calibrations of characteristic frequency. We also compare the performance of proportional control, LQG control, and nonlinear control to reduce fluctuations in particle position due to thermal noise. Assuming a cubic trapping force, we use computer simulations to demonstrate that the nonlinear controller can reduce position variance by a factor of 65 for a 1-µm diameter polystyrene bead under typical conditions. Copyright © 2005 John Wiley & Sons, Ltd. [source]

Nonlinear controls for a class of discrete-time bilinear systems

Some results in nonlinear QFT

INTERNATIONAL JOURNAL OF ROBUST AND NONLINEAR CONTROL, Issue 2 2001
A. Baños
Abstract Nonlinear QFT (quantitative feedback theory) is a technique for solving the problem of robust control of an uncertain nonlinear plant by replacing the uncertain nonlinear plant with an ,equivalent' family of linear plants. The problem is then finding a linear QFT controller for this family of linear plants. While this approach is clearly limited, it follows in a long tradition of linearization approaches to nonlinear control (describing functions, extended linearization, etc.) which have been found to be quite effective in a wide range of applications. In recent work, the authors have developed an alternative function space method for the derivation and validation of nonlinear QFT that has clarified and simplified several important features of this approach. In particular, single validation conditions are identified for evaluating the linear equivalent family, and as a result, the nonlinear QFT problem is reduced to a linear equivalent problem decoupled from the linear QFT formalism. In this paper, we review this earlier work and use it in the development of (1) new results on the existence of nonlinear QFT solutions to robust control problems, and (2) new techniques for the circumvention of problems encountered in the application of this approach. Copyright © 2001 John Wiley & Sons, Ltd. [source]

Fault-tolerant control of process systems using communication networks

AICHE JOURNAL, Issue 6 2005
Nael H. El-Farra
Abstract A methodology for the design of fault-tolerant control systems for chemical plants with distributed interconnected processing units is presented. Bringing together tools from Lyapunov-based nonlinear control and hybrid systems theory, the approach is based on a hierarchical architecture that integrates lower-level feedback control of the individual units with upper-level logic-based supervisory control over communication networks. The local control system for each unit consists of a family of control configurations for each of which a stabilizing feedback controller is designed and the stability region is explicitly characterized. The actuators and sensors of each configuration are connected, via a local communication network, to a local supervisor that orchestrates switching between the constituent configurations, on the basis of the stability regions, in the event of failures. The local supervisors communicate, through a plant-wide communication network, with a plant supervisor responsible for monitoring the different units and coordinating their responses in a way that minimizes the propagation of failure effects. The communication logic is designed to ensure efficient transmission of information between units, while also respecting the inherent limitations in network resources by minimizing unnecessary network usage and accounting explicitly for the effects of possible delays due to fault-detection, control computations, network communication and actuator activation. The proposed approach provides explicit guidelines for managing the various interplays between the coupled tasks of feedback control, fault-tolerance and communication. The efficacy of the proposed approach is demonstrated through chemical process examples. © 2005 American Institute of Chemical Engineers AIChE J, 2005 [source]

Backstepping-based cascade control scheme for batch distillation columns

AICHE JOURNAL, Issue 9 2004
Rosendo Monroy-Loperena
Abstract Nonstationary dynamics, finite-time operation, large thermodynamical uncertainty and delayed composition measurements make the control of batch distillation processes a challenging and interesting problem. In this paper, a cascade control design to regulate the overhead composition of a batch distillation column is presented. The controller is designed within the framework of robust nonlinear control with modeling error compensation techniques in conjunction with a backstepping approach. The result is a cascade controller with a master loop that, driven by the composition regulation error, produces a time-varying set point for the temperature in a certain tray; and with a secondary controller that manipulates the internal reflux ratio to track the time-varying set point determined by the master composition loop. How to extend the controller design to have multiple slave temperature controllers, to improve the regulation of the overhead composition in a batch distillation column, is also presented. The proposed control approach is illustrated by numerical simulations on a full dynamical model. © 2004 American Institute of Chemical Engineers AIChE J, 50: 2113,2129, 2004 [source]

Nonlinear Modeling and Tracking Control of a Hydraulic Rotary Vane Actuator

PROCEEDINGS IN APPLIED MATHEMATICS & MECHANICS, Issue 1 2005
Frank Heidtmann
Rotary vane actuators as rotational drives provide rotational movements directly because they are constructed as a joint and actuator in one. So it is possible to pass on the disadvantageous transmission kinematics used with the so far usual differential cylinders at the arms of large manipulators. However, the use of hydraulic rotary vane actuators is associated with high internal oil leakage and/or high friction. Therefore, a nonlinear dynamic model for such an actuator, driving a rigid robot arm, as well as its nonlinear control are derived. To achieve tracking control a model based control law is set up using fundamental linear differential equations for the tracking error. The control law is implemented and tested on a testbed, the produced experimental results are presented. The same control algorithm can also be used to realize nonlinear disturbance attenuation for hydraulic rotary vane actuators via tracking control. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

Nonlinear control of power converters: a new adaptive backstepping approach,

Nonlinear Control VIA Generalized Feedback Linearization Using Neural Networks

ASIAN JOURNAL OF CONTROL, Issue 2 2001
Graham C. Goodwin
ABSTRACT A novel approach to nonlinear control, called Generalized Feedback Linearization (GFL), is presented. This new strategy overcomes one important drawback of the well known Feedback Linearization strategy, in the sense that it is able to handle a broader class of nonlinear systems, namely those having unstable zero dynamics. It is shown that the use of a nonlinear predictor for the system output is a key feature in the derivation of the control strategy. For certain types of systems this predictor can be found as a nonlinear function of the system input and output, allowing an output feedback control solution. The use of Artificial Neural Networks (ANN) to directly parameterize the predictor of the controlled variable when an explicit model for the system is not available, is investigated via computer simulations. This approach is based on the functional approximation capability of multi layer ANN. [source]