• 제목/요약/키워드: nonlinearities

검색결과 671건 처리시간 0.03초

다변수 Hammerstein 공정의 순차 확인법 (Sequential Loop Closing Identification of Hammerstein Models for Multiple-Input Multiple-Output Processes)

  • 박호철;구도균;이문용;이지태
    • 제어로봇시스템학회논문지
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    • 제10권12호
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    • pp.1280-1286
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    • 2004
  • A lot of industrial chemical processes contain certain input nonlinearities even though they are controlled by several linear controllers. Here we investigate a sequential loop closing identification method for MIMO Hammerstein nonlinear processes with diagonal nonlinearities. The proposed method separates the identification of the nonlinear static function from that of the linear subsystem by using a relay feedback test and a triangular type signal test. From 2 n activations for n n MIMO nonlinear processes, we sequentially identify the whole range of the nonlinear static function as well as the transfer function matrix of the linear subsystem.

Robust High Gain Adaptive Output Feedback Control for Nonlinear Systems with Uncertain Nonlinearities in Control Input Term

  • Michino, Ryuji;Mizumoto, Ikuro;Iwai, Zenta;Kumon, Makoto
    • International Journal of Control, Automation, and Systems
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    • 제1권1호
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    • pp.19-27
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    • 2003
  • It is well known that one can easily design a high-gain adaptive output feedback control for a class of nonlinear systems which satisfy a certain condition called output feedback exponential passivity (OFEP). The designed high-gain adaptive controller has simple structure and high robustness with regard to bounded disturbances and unknown order of the controlled system. However, from the viewpoint of practical application, it is important to consider a robust control scheme for controlled systems for which some of the assumptions of output feedback stabilization are not valid. In this paper, we design a robust high-gain adaptive output feedback control for the OFEP nonlinear systems with uncertain nonlinearities and/or disturbances. The effectiveness of the proposed method is shown by numerical simulations.

Neuro-controller for a XY Positioning Table

  • Jang, Jun-Oh
    • 제어로봇시스템학회:학술대회논문집
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    • 제어로봇시스템학회 2003년도 ICCAS
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    • pp.581-586
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    • 2003
  • This paper presents control designs using neural networks (NN) for a XY positioning table. The proposed neurocontroller is composed of an outer PD tracking loop for stabilization of the fast flexible-mode dynamics and an NN inner loop used to compensate for the system nonlinearities. A tuning algorithm is given for the NN weights, so that the NN compensation scheme becomes adaptive, guaranteeing small tracking errors and bounded weight estimates. Formal nonlinear stability proofs are given to show that the tracking error is small. The proposed neuro-controller is implemented and tested on an IBM PC-based XY positioning table, and is applicable to many precision XY tables. The algorithm, simulation, and experimental results are described. The experimental results are shown to be superior to those of conventional control.

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고출력증폭기의 비선형성 보정을 위한 비선형 적응 Predistorter (A Nonlinear Adaptive Predistorter for the Compensation of Nonlinearities in High Power Amplifier)

  • 임용훈;서정태;윤대희;서광락;소용수
    • 전자공학회논문지B
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    • 제31B권7호
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    • pp.16-25
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    • 1994
  • The major reason that reduces the performance of satellite communication channels is known as the nonlinearities of high power amplifiers(HPA's) which are usually modeled by memoryless nonlinear systems, in the channels. This paper proposes a nonlinear adaptive predistorter,which predistorts the input symbols such that the symbol passing through the nonlinear HPA preserves the desired constellation, and derives the region of convergence for the predistorter. The predistorter has capability of coping adaptively with any time-varying environment such as changes of operating points if HPA since the coefficients of the predistorter which has a form of truncated Tayler series are obtained by recursive optimization procedure utilizing QAM data sequence directely. Simulation results show that the proposed one with 16 QAM input has better performance than the conventional fixed predistorter with the same input.

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4차 모멘트를 이용한 비선형성의 탐색 (Detection of Nonlinearity Using a Fourth Moment)

  • 장한기;김광준
    • 소음진동
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    • 제4권3호
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    • pp.307-318
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    • 1994
  • Existence of any nonlinearity in responses of a nonlinear system is tested using a kurtosis or a fourth moment which has been widely used to characterize signal patterns. By inputting a harmonic signal to a system and investigating the distortions of an output signal from a harmonic pattern, which are due to violations of proportionality between the input and the output, it is judged whether the output is generated from a nonlinear system or not. Through applying the method presented in this work to simulation studies on detections of nonlinearities of a single degree of freedom system, in which three kinds of nonlinearities are treated as restoring force terms, feasibilities of the method are shown and the range of both frequency and input amplitude, in which the system generates nonlinear responses, is determined.

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2지역 전력계통의 부하주파수 제어를 위한 적응 뉴로 퍼지추론 보상기 설계 (Design of an Adaptive Neuro-Fuzzy Inference Precompensator for Load Frequency Control of Two-Area Power Systems)

  • 정형환;정문규;한길만
    • Journal of Advanced Marine Engineering and Technology
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    • 제24권2호
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    • pp.72-81
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    • 2000
  • In this paper, we design an adaptive neuro-fuzzy inference system(ANFIS) precompensator for load frequency control of 2-area power systems. While proportional integral derivative (PID) controllers are used in power systems, they may have some problems because of high nonlinearities of the power systems. So, a neuro-fuzzy-based precompensation scheme is incorporated with a convectional PID controller to obtain robustness to the nonlinearities. The proposed precompensation technique can be easily implemented by adding a precompensator to an existing PID controller. The applied neruo-fuzzy inference system precompensator uses a hybrid learning algorithm. This algorithm is to use both a gradient descent method to optimize the premise parameters and a least squares method to solve for the consequent parameters. Simulation results show that the proposed control technique is superior to a conventional Ziegler-Nichols PID controller in dynamic responses about load disturbances.

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접는 미사일 조종날개의 비선형 동특성 (Nonlinear Dynamic Characteristics of Deployable Missile Control Fin)

  • 김대관;배재성;이인;신영석;이열화
    • 한국소음진동공학회논문집
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    • 제12권10호
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    • pp.808-815
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    • 2002
  • The nonlinear characteristics for hinge of a deployable missile control fin are investigated experimentally. The nonlinearity is caused by a worn or loose hinge and manufacturing tolerance and cannot be eliminated completely. The structural nonlinearity has an effect on the static and dynamic characteristics of the control fin. Therefore, it is necessary to establish the accurate nonlinear model for the hinge of the control fin. In the present study the existence of nonlinearities in the hinge is confirmed from the frequency response experiments such as tip random excitation and base sine sweep. Using the system identification method. especially, ″Force-state Mapping Technique″, the types of nonlinearities are identified and the nonlinear hinge model of the control fin is established.

루에 동적 시스템을 위한 샘플데이타 제어 (Sampled-data Control for Lur'e Dynamical Systems)

  • 유아연;이상문
    • 전기학회논문지
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    • 제63권2호
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    • pp.261-265
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    • 2014
  • This paper studies the problem of the sampled-data control for Lur'e system with nonlinearities. The nonlinearities are expressed as convex combinations of sector and slope bounds. It is assumed that the sampling periods are arbitrarily varying but bounded. By constructing a new augmented Lyapunov-Krasovskii functional which have an augmented quadratic form with states as well as the nonlinear function, the stabilizing sampled-data controller gains are obtained by solving a set of linear matrix inequalities. The effectiveness of the developed method is demonstrated by numerical simulations.

고차스펙트럼의 기계적 시스템 적용 연구, (1) -바이스펙트럼과 2차 위상결합 해석- (Higher Order Spectra and Their Application to Mechanical Systems (I)-Bispectrum and Anlaysis of QPC-)

  • 이준서;차경옥
    • 한국자동차공학회논문집
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    • 제7권7호
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    • pp.278-285
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    • 1999
  • This paper is concerned with the development of useful engineering techniques to detect and anlayse nonlinearities in mechanical systems. The methods developed are based on the concepts of higher order spectra. The study of higher order statistics has been dominated by work on the bispectrum. The bispectrum can be viewed as a decomposition of the third moment(skewness) of a quadratic phase coupling(QPC) can be analyzed by bicoherence function. Finally, the application of these techiques to data from actual mechanical systems will be performed insecond report.

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EXISTENCE AND MULTIPLICITY OF SOLUTIONS FOR KIRCHHOFF-SCHRÖDINGER-POISSON SYSTEM WITH CONCAVE AND CONVEX NONLINEARITIES

  • Che, Guofeng;Chen, Haibo
    • 대한수학회지
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    • 제57권6호
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    • pp.1551-1571
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    • 2020
  • This paper is concerned with the following Kirchhoff-Schrödinger-Poisson system $$\begin{cases} -(a+b{\displaystyle\smashmargin{2}\int\nolimits_{\mathbb{R}^3}}{\mid}{\nabla}u{\mid}^2dx){\Delta}u+V(x)u+{\mu}{\phi}u={\lambda}f(x){\mid}u{\mid}^{p-2}u+g(x){\mid}u{\mid}^{p-2}u,&{\text{ in }}{\mathbb{R}}^3,\\-{\Delta}{\phi}={\mu}{\mid}u{\mid}^2,&{\text{ in }}{\mathbb{R}}^3, \end{cases}$$ where a > 0, b, µ ≥ 0, p ∈ (1, 2), q ∈ [4, 6) and λ > 0 is a parameter. Under some suitable assumptions on V (x), f(x) and g(x), we prove that the above system has at least two different nontrivial solutions via the Ekeland's variational principle and the Mountain Pass Theorem in critical point theory. Some recent results from the literature are improved and extended.