• Title/Summary/Keyword: Nonlinear systems

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Application of Volterra Functional Series to the Analysis of Nonlinear Systems Represented by Nonlinear Differential Equations (비선형 미분방정식으로 표현되는 비선형 시스템의 해석을 위한 볼테리 시리즈의 응용)

  • Sung, Dan-Keun
    • Journal of the Korean Institute of Telematics and Electronics
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    • v.25 no.3
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    • pp.315-321
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    • 1988
  • The input-output relation for nonlinear systems can e explicitly represented by the volterra functional series and it is characterized by the Volterra kernels. A block diagram reduction method is proposed to determine the Volterra kernels for nonlinear differential equations and is compared with the direct substitution techniques. The former method can significantly reduce the computational complexity. A degree of nonlinearity is defined and analyzed for the analysis of nonlinear systems.

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A NEW APPROACH TO EXPONENTIAL STABILITY ANALYSIS OF NONLINEAR SYSTEMS

  • WAN ANHUA
    • Journal of applied mathematics & informatics
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    • v.19 no.1_2
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    • pp.345-351
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    • 2005
  • An effective method for analyzing the stability of nonlinear systems is developed. After introducing a novel concept named the point- wise generalized Dahlquist constant for any mapping and presenting its useful properties, we show that the point-wise generalized Dahlquist constant is sufficient for characterizing the exponential stability of nonlinear systems.

Anti-shock Controller Design for Optical Disk Drive Systems with a Nonlinear Controller (광디스크 드라이브 시스템을 위한 비선형 Anti-shock 제어기 설계)

  • Baek Jong-Shik;Chung Chung Choo
    • Journal of Institute of Control, Robotics and Systems
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    • v.11 no.9
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    • pp.741-749
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    • 2005
  • This paper presents a nonlinear controller design for optical disk drive systems to improve anti-shock performance. The nonlinear anti-shock controller is added parallel to the original linear servo control loop. In the previous work, a dead-zone nonlinear element is used for the nonlinear controller and a PID control method is used for the linear controller. Although this parallel structure of the controller improves anti-shock performance, it has a narrow stability bound. In this paper, the dead-zone with saturation nonlinear element is proposed for the nonlinear controller. Since this nonlinear element improves stability margin, we can use higher slope gain of dead-zone than that of nonlinear controller using dead-zone only. In the linear controller design, it is shown that the lead-lag control has an improved stability margin over PID control. Numerical simulation results and experimental results show that the proposed method can get better performance to the external shock than previously proposed methods.

HIGH-ORDER NEWTON-KRYLOV METHODS TO SOLVE SYSTEMS OF NONLINEAR EQUATIONS

  • Darvishi, M.T.;Shin, Byeong-Chun
    • Journal of the Korean Society for Industrial and Applied Mathematics
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    • v.15 no.1
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    • pp.19-30
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    • 2011
  • In [21], we compared the Newton-Krylov method and some high-order methods to solve nonlinear systems. In this paper, we propose high-order Newton-Krylov methods combining the Newton-Krylov method with some high-order iterative methods to solve systems of nonlinear equations. We provide some numerical experiments including comparisons of CPU time and iteration numbers of the proposed high-order Newton-Krylov methods for several nonlinear systems.

A formal linearization of nonlinear systems based on the discrete-fourier transform

  • Takata, Hitoshi;Komatsu, Kazuo
    • 제어로봇시스템학회:학술대회논문집
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    • 1991.10b
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    • pp.1823-1827
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    • 1991
  • The problem regarding nonlinear systems has come to occupy an important position. In order to solve a nonlinear problem we have methods of linearization which are developed through linear approximation to adapt linear system theories. In this paper we present a formal linearization of nonlinear systems based on the discrete-Fourier transform (D.F.T.).

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ON ASYMPTOTIC PROPERTY IN VARIATION FOR NONLINEAR DIFFERENTIAL SYSTEMS

  • Choi, Sung Kyu;Im, Dong Man;Koo, Namjip
    • Journal of the Chungcheong Mathematical Society
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    • v.22 no.3
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    • pp.545-556
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    • 2009
  • We show that two notions of asymptotic equilibrium and asymptotic equilibrium in variation for nonlinear differential systems are equivalent via $t_{\infty}$-similarity of associated variational systems. Moreover, we study the asymptotic equivalence between nonlinear system and its variational system.

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A Study on the Deadbeat Response Attribute of Nonlinear Systems (비선형시스템의 데드비트응답 특성 연구)

  • Song, Ja-Youn
    • Proceedings of the KIEE Conference
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    • 2001.07d
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    • pp.1993-1995
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    • 2001
  • The subject of nonlinear control is an important area of automatic control. The behavior of nonlinear systems is much more complex. If the operating range of a control system is small, and if the involved nonlinearities are smooth, then the control system may be resonably approximated by a set of linear differential equations. This paper presents the deadbeat response attribute of some nonlinear systems, e.g., magnetic levitation, pendulum, van der pol oscillator etc.. The studied results through the computer simulation are shown a promising attribute of deadbeat response that the outputs of the systems are reached relatively fast the steady state.

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[ $H_{\infty}$ ] Control for a Class of Singularly Perturbed Nonlinear Systems via Successive Galerkin Approximation

  • Kim, Young-Joong;Lim, Myo-Taeg
    • International Journal of Control, Automation, and Systems
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    • v.5 no.5
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    • pp.501-507
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    • 2007
  • This paper presents a new algorithm for the closed-loop $H_{\infty}$ control of a class of singularly perturbed nonlinear systems with an exogenous disturbance, using the successive Galerkin approximation (SGA). The singularly perturbed nonlinear system is decomposed into two subsystems of a slow-time scale and a fast-time scale in the spirit of the general theory of singular perturbation. Two $H_{\infty}$ control laws are obtained to each subsystem by using the SGA method. The composite control law that consists of two $H_{\infty}$ control laws of each subsystem is designed. One of the purposes of this paper is to design the closed-loop $H_{\infty}$ composite control law for the singularly perturbed nonlinear systems via the SGA method. The other is to reduce the computational complexity when the SGA method is applied to the high order systems.

Design of an Augmented Automatic Choosing Control via Hamiltonian and GA for a class of Nonlinear Systems with Constrained Input

  • Nakamura, Masatoshi;Zhang, Tao
    • 제어로봇시스템학회:학술대회논문집
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    • 2002.10a
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    • pp.76.3-76
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    • 2002
  • The purpose of this paper is to present a new nonlinear feedback control called AACC (Augmented automatic choosing control) for nonlinear systems. Generally, it is easy to design the optimal control laws for linear systems, but it is not so for nonlinear systems, though they have been studied for many years. One of most popular and practical nonlinear control laws is synthesized by applying a linearization method by Taylor expansion truncated at the first order and the linear optimal control method. This is only effective in a small region around the steady state point or in almost linear systems. Controllers based on a change of coordinates in differential geometry are effective in wider...

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Wavelet Neural Network Based Indirect Adaptive Control of Chaotic Nonlinear Systems

  • Choi, Yoon-Ho;Choi, Jong-Tae;Park, Jin-Bae
    • Journal of the Korean Institute of Intelligent Systems
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    • v.14 no.1
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    • pp.118-124
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    • 2004
  • In this paper, we present a indirect adaptive control method using a wavelet neural network (WNN) for the control of chaotic nonlinear systems without precise mathematical models. The proposed indirect adaptive control method includes the off-line identification and on-line control procedure for chaotic nonlinear systems. In the off-line identification procedure, the WNN based identification model identifies the chaotic nonlinear system by using the serial-parallel identification structure and is trained by the gradient-descent method. And, in the on-line control procedure, a WNN controller is designed by using the off-line identification model and is trained by the error back-propagation algorithm. Finally, the effectiveness and feasibility of the proposed control method is demonstrated with applications to the chaotic nonlinear systems.