• Title/Summary/Keyword: fuzzy modeling

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Fuzzy Output-Tracking Control for Uncertain Nonlinear Systems (불확실 비선형 시스템을 위한 퍼지 출력 추종 제어)

  • Lee, Ho-Jae;Joom, Young-Hoo;Park, Jin-Ba
    • Journal of the Korean Institute of Intelligent Systems
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    • v.15 no.2
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    • pp.185-190
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    • 2005
  • A systematic output tracking control design technique for robust control of Takagi-Sugeno (T-S) fuzzy systems with norm bounded uncertainties is developed. The uncertain T-S fuzzy system is first represented as a set of uncertain local linear systems. The tracking problem is then converted into the stabilization problem for a set of uncertain local linear systems thereby leading to a more feasible controller design procedure. A sufficient condition for robust asymptotic output tracking is derived in terms of a set of linear matrix inequalities. A stability condition on the traversing time instances is also established. The output tracking control simulation for a flexible-joint robot-arm model is demonstrated, to convincingly show the effectiveness of the proposed system modeling and controller design.

A Novel Algorithm for Fault Classification in Transmission Lines Using a Combined Adaptive Network and Fuzzy Inference System

  • Yeo, Sang-Min;Kim, Chun-Hwan
    • KIEE International Transactions on Power Engineering
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    • v.3A no.4
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    • pp.191-197
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    • 2003
  • Accurate detection and classification of faults on transmission lines is vitally important. In this respect, many different types of faults occur, such as inter alia low impedance faults (LIF) and high impedance faults (HIF). The latter in particular pose difficulties for the commonly employed conventional overcurrent and distance relays, and if undetected, can cause damage to expensive equipment, threaten life and cause fire hazards. Although HIFs are far less common than LIFs, it is imperative that any protection device should be able to satisfactorily deal with both HIFs and LIFs. Because of the randomness and asymmetric characteristics of HIFs, their modeling is difficult and numerous papers relating to various HIF models have been published. In this paper, the model of HIFs in transmission lines is accomplished using the characteristics of a ZnO arrester, which is then implemented within the overall transmission system model based on the electromagnetic transients program (EMTP). This paper proposes an algorithm for fault detection and classification for both LIFs and HIFs using Adaptive Network-based Fuzzy Inference System (ANFIS). The inputs into ANFIS are current signals only based on Root-Mean-Square (RMS) values of 3-phase currents and zero sequence current. The performance of the proposed algorithm is tested on a typical 154 kV Korean transmission line system under various fault conditions. Test results demonstrate that the ANFIS can detect and classify faults including LIFs and HIFs accurately within half a cycle.

A fuzzy logic Controller design for Maximum Power Extraction of variable speed Wind Energy Conversion System (가변 풍력발전 시스템의 최대출력 제어를 위한 Fuzzy 제어기 설계)

  • Kim, Jae-Gon;Kim, Byung-Yoon;Huh, Uk-Youl
    • Proceedings of the KIEE Conference
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    • 2004.07d
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    • pp.2307-2309
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    • 2004
  • This paper presents a modeling and simulation of a fuzzy controller for maximum power extraction of a grid-connected wind energy conversion system with a link of a rectifier and an inverter. It discusses the maximum power control algorithm for a wind turbine and proposes, in a graphical form, the relationships of wind turbine output, rotor speed, power coefficient, tip-speed ratio with wind speed when the wind turbine is operated under the maximum power control. The control objective is to always extract maximum power from wind and transfer the power to the utility by controlling both the pitch angle of the wind turbine blades and the inverter firing angle. Pitch control method is mechanically complicated, but the control performance is better than that of the stall regulation method. The simulation results performed on MATLAB will show the variation of generator's rotor angle and rotor speed, pitch angle, and generator output.

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Design of an Automatic constructed Fuzzy Adaptive Controller(ACFAC) for the Flexible Manipulator (유연 로봇 매니퓰레이터의 자동 구축 퍼지 적응 제어기 설계)

  • 이기성;조현철
    • Journal of the Korean Institute of Intelligent Systems
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    • v.8 no.2
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    • pp.106-116
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    • 1998
  • A position control algorithm of a flexible manipulator is studied. The proposed algorithm is based on an ACFAC(Automatic Constructed Fuzzy Adaptive Controller) system based on the neural network learning algorithms. The proposed system learns membership functions for input variables using unsupervised competitive learning algorithm and output information using supervised outstar learning algorithm. ACFAC does not need a dynamic modeling of the flexible manipulator. An ACFAC is designed that the end point of the flexible manipulator tracks the desired trajectory. The control input to the process is determined by error, velocity and variation of error. Simulation and experiment results show a robustness of ACFAC compared with the PID control and neural network algorithms.

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Neuro-fuzzy and artificial neural networks modeling of uniform temperature effects of symmetric parabolic haunched beams

  • Yuksel, S. Bahadir;Yarar, Alpaslan
    • Structural Engineering and Mechanics
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    • v.56 no.5
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    • pp.787-796
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    • 2015
  • When the temperature of a structure varies, there is a tendency to produce changes in the shape of the structure. The resulting actions may be of considerable importance in the analysis of the structures having non-prismatic members. The computation of design forces for the non-prismatic beams having symmetrical parabolic haunches (NBSPH) is fairly difficult because of the parabolic change of the cross section. Due to their non-prismatic geometrical configuration, their assessment, particularly the computation of fixed-end horizontal forces and fixed-end moments becomes a complex problem. In this study, the efficiency of the Artificial Neural Networks (ANN) and Adaptive Neuro Fuzzy Inference Systems (ANFIS) in predicting the design forces and the design moments of the NBSPH due to temperature changes was investigated. Previously obtained finite element analyses results in the literature were used to train and test the ANN and ANFIS models. The performances of the different models were evaluated by comparing the corresponding values of mean squared errors (MSE) and decisive coefficients ($R^2$). In addition to this, the comparison of ANN and ANFIS with traditional methods was made by setting up Linear-regression (LR) model.

Data-driven SIRMs-connected FIS for prediction of external tendon stress

  • Lau, See Hung;Ng, Chee Khoon;Tay, Kai Meng
    • Computers and Concrete
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    • v.15 no.1
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    • pp.55-71
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    • 2015
  • This paper presents a novel harmony search (HS)-based data-driven single input rule modules (SIRMs)-connected fuzzy inference system (FIS) for the prediction of stress in externally prestressed tendon. The proposed method attempts to extract causal relationship of a system from an input-output pairs of data even without knowing the complete physical knowledge of the system. The monotonicity property is then exploited as an additional qualitative information to obtain a meaningful SIRMs-connected FIS model. This method is then validated using results from test data of the literature. Several parameters, such as initial tendon depth to beam ratio; deviators spacing to the initial tendon depth ratio; and distance of a concentrated load from the nearest support to the effective beam span are considered. A computer simulation for estimating the stress increase in externally prestressed tendon, ${\Delta}f_{ps}$, is then reported. The contributions of this paper is two folds; (i) it contributes towards a new monotonicity-preserving data-driven FIS model in fuzzy modeling and (ii) it provides a novel solution for estimating the ${\Delta}f_{ps}$ even without a complete physical knowledge of unbonded tendons.

Fuzzy-PI controller for molten steel level of continuous casting process (연속 주조의 용강 높이 제어를 위한 퍼지-PI 제어기)

  • Joo, Moon-G.;Kim, Do-E.;Kim, Ho-K.;Kim, Jong-M.
    • Journal of the Korean Institute of Intelligent Systems
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    • v.18 no.4
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    • pp.488-493
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    • 2008
  • A mathematical model of molten steel level for continuous casting process is presented, where the molten steel level, input and output flow in the mold, the relation between stopper position and input flow etc. are considered. The mathematical model is implemented and simulated by using MATLAB. Comparing the result of molten steel level from the simulator with that of real plant, the performance of the model is shown to be reasonable. By using this simulator, it is shown that PI controller with variable P gain, adjusted by fuzzy logic system, has better control result than conventional PI controller.

Suitability Analysis of Eco-corridor for Korean Water Deer (Hydropotes Inermis) based on GIS and Fuzzy Function - A Case Study of Chuncheon City - (GIS와 퍼지함수(Fuzzy function)를 활용한 고라니의 생태통로 적지분석 - 춘천시를 대상으로 -)

  • Lee, Do-Hyung;Kil, Sung-Ho;Jeon, Seong-Woo
    • Journal of KIBIM
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    • v.8 no.4
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    • pp.72-79
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    • 2018
  • Rapid developments around the world have resulted in urban expansion, habitat destruction, habitat fragmentation, and pollution problems, which are the main reasons for the decline in biological diversity. The United Nations warns that many animals and plants will die out in the near future if this continues. This study was performed to propose a map of eco-corridor suitability analysis of Korean water deer(Hydropotes Inermis) to enhance biodiversity in Chuncheon city. Eight factors affecting habitat suitability were elevation, aspect, slope, forest type, distance to the road, distance to the stream, land use and green connectivity. Previous study analysis on the mobility behaviour of the Korean water deer(Hydropotes Inermis) produced a habitat suitability map by determining the threshold and assigning a value between 0 and 1 depending on the habitat suitability using the fuzzy function. A method of analysis was proposed for a number of eco-corridor through comparative analysis of the data from the produced habitat suitability map and the road-kill point. The previous studies were focused on Backdudaegan region and national parks except for urban cities. The potential habitat map of Korean water deer could be helpful as a way to prevent habitat disconnection and increase species diversity in urban areas.

Decentralized Dynamic Output Feedback Controller for Discrete-time Nonlinear Interconnected Systems via T-S Fuzzy Models (이산 시간 비선형 상호 결합 시스템의 T-S 퍼지 모델을 위한 분산 동적 출력 궤한 제어기 설계)

  • Gu, Geun-Beom;Ju, Yeong-Hun;Park, Jin-Bae
    • Proceedings of the Korean Institute of Intelligent Systems Conference
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    • 2007.11a
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    • pp.374-377
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    • 2007
  • 본 논문은 Takagi-Sugeno (T-S) 퍼지 모델을 이용하여 이산 시간에서의 비선형 상호 결합 시스템에 대한 분산 동적 출력 궤한 제어기를 제시한다. 이산시간 비선형 상호 결합 시스템의 각 하위 시스템에 대한 T-S 퍼지 모델링을 한 후, 각각에 대해 동적 출력 궤한 제어기를 설계한다. 제어가 된 폐루프 하위 시스템들로 전체 시스템의 평형점이 안정화되는 선형 행렬 부등식 (LMI)을 구하고, 부등식을 이용하여 동적 출력 궤한 제어기의 이득값을 구한다. 마지막으로 모의실험을 통해 분산 동적 출력 궤한 제어기의 효용성을 확인한다.

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Fuzzy neural network modeling using hyper elliptic gaussian membership functions (초타원 가우시안 소속함수를 사용한 퍼지신경망 모델링)

  • 권오국;주영훈;박진배
    • 제어로봇시스템학회:학술대회논문집
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    • 1997.10a
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    • pp.442-445
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    • 1997
  • We present a hybrid self-tuning method of fuzzy inference systems with hyper elliptic Gaussian membership functions using genetic algorithm(GA) and back-propagation algorithm. The proposed self-tuning method has two phases : one is the coarse tuning process based on GA and the other is the fine tuning process based on back-propagation. But the parameters which is obtained by a GA are near optimal solutions. In order to solve the problem in GA applications, it uses a back-propagation algorithm, which is one of learning algorithms in neural networks, to finely tune the parameters obtained by a GA. We provide Box-Jenkins time series to evaluate the advantage and effectiveness of the proposed approach and compare with the conventional method.

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