• Title/Summary/Keyword: system uncertainty

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Sliding Mode Control of the Vehicle ABS with a Disturbance Observer for Model Uncertainties (모델 불확실성에 대한 외란 관측기를 가진 차량 ABS의 슬라이딩 모드 제어)

  • Hwang Jin-Kwon;Song Chul-Ki
    • Journal of the Korean Society for Precision Engineering
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    • v.23 no.4 s.181
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    • pp.44-51
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    • 2006
  • This paper addresses sliding mode control of the anti-lock braking system (ABS) with a disturbance observer for model uncertainties such as vehicle parameter variation, un-modeled dynamics, and external disturbances. By using a nominal vehicle model, a sliding mode controller is designed to achieve a desired wheel slip ratio for ABS control. To compensate the model uncertainties, a disturbance observer is introduced with the help of a transfer function of a hydraulic brake dynamics. A proposed sliding mode controller with a disturbance observer is evaluated through simulations for model uncertainties. The simulation results show that the disturbance observer can enhance performances of sliding mode control for ABS.

Design of Electric Power Load Forecasting Model based on IT2TSK FLS (IT2TSK 퍼지논리 기반 전력부하 예측 모델 설계에 관한 연구)

  • Bang, Young-Keun;Shim, Jae-Sun
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.64 no.7
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    • pp.1088-1095
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    • 2015
  • In most cases, the use of electric power is associated with the economic scale of a nation closely. Thus, the electric power load forecasting plays an important role for the national economic plan. This paper deals with the design method for the electric power load forecasting system. In this paper, RCR-MA data processing, which can make the complex properties of the original data form simple, is proposed. Next, IT2TSK FLS, which can reflect the uncertainty of data more than T1TSK FLS, is applied. Consequently, the structural advantage of the proposed system can improve the forecasting accuracy, and is verified by using two types of electric power data.

Takagi-Sugeno Fuzzy Model-Based Approach to Robust Control of Boost DC-DC Converters

  • Seo, Sang-Wha;Choi, Han Ho;Kim, Yong
    • Journal of Electrical Engineering and Technology
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    • v.10 no.3
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    • pp.925-934
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    • 2015
  • This paper considers the robust controller design problem for a boost DC-DC converter. Based on the Takagi-Sugeno fuzzy model-based approach, a fuzzy controller as well as a fuzzy load conductance observer are designed. Sufficient conditions for the existence of the controller and the observer are derived using Linear Matrix Inequalities (LMIs). LMI parameterizations of the gain matrices are obtained. Additionally, LMI conditions for the existence of the fuzzy controller and the fuzzy load observer guaranteeing α-stability, quadratic performance are derived. The exponential stability of the augmented fuzzy observer-controller system is shown. It is also shown that the fuzzy load observer and the fuzzy controller can be designed independently. Finally, the effectiveness of the proposed method is verified via experimental and simulation results under various conditions.

Reliability Evaluation of a Distribution System with wind Turbine Generators Based on the Switch-section Partitioning Method

  • Wu, Hongbin;Guo, Jinjin;Ding, Ming
    • Journal of Electrical Engineering and Technology
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    • v.11 no.3
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    • pp.575-584
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    • 2016
  • Considering the randomness and uncertainty of wind power, a reliability model of WTGs is established based on the combination of the Weibull distribution and the Markov chain. To analyze the failure mode quickly, we use the switch-section partitioning method. After defining the first-level load zone node, we can obtain the supply power sets of the first-level load zone nodes with each WTG. Based on the supply sets, we propose the dynamic division strategy of island operation. By adopting the fault analysis method with the attributes defined in the switch-section, we evaluate the reliability of the distribution network with WTGs using a sequential Monte Carlo simulation method. Finally, using the IEEE RBTS Bus6 test system, we demonstrate the efficacy of the proposed model and method by comparing different schemes to access the WTGs.

Evaluation Technique for Ratio Error of Current Transformer Comparator (전류변성기 비교기의 비오차 평가 기술)

  • Kim, Yoon-Hyoung;Han, Sang-Gil;Jung, Jae-Kap;Han, Sang-Ok
    • The Transactions of the Korean Institute of Electrical Engineers P
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    • v.57 no.3
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    • pp.291-295
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    • 2008
  • We have developed an evaluation technique for ratio errors of current transformer (CT) comparator by using the precise standard capacitors. By applying this technique for equivalent circuit of CT comparator evaluation system, we can obtain the calculated and measured ratio errors in the CT comparator. Thus we can evaluate ratio errors of CT comparator by comparing the calculated and measured ratio errors. Because this method requires only the standard capacitors, it is simple and easy method to reliability and accuracy maintenance of CT comparator. The method was applied to CT comparator under test with the ratio error ranges of $0{\sim}{\pm}10%$. The ratio error of the CT comparator under test theoretically obtained in this method are consistent with that measured for same CT comparator under test by using wide ratio error CT within an estimated expanded uncertainty (k = 2) in the overall ratio error ranges.

Development a Knowledge-based Medical Diagnosing System for Thyroid Disorders (갑상선 질환의 진단을 위한 지식기반 의료진단 시스템의 개발)

  • Cho, Kwun-Ik;Kim, Soung-Hie;Noh, Jae-Bum
    • IE interfaces
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    • v.3 no.2
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    • pp.1-11
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    • 1990
  • In this study, we will present a knowledge-based consulting system, called THYCONS, for diagnosing thyroid disorders. It has been developed to make the knowledge and expertise of the human expert more widely available, therefore achieving a high-quality diagnosis. Frames will be used to represent the medical knowledge of thyroid disorders, and several rules are attached in each slot of a frame. The uncertainty of diagnostic processes is manipulated by the subjective Bayesian method under the assumption that the pieces of evidence are conditionally independent. Searching for the group of diagnostic tests to be carried out and their optimum sequences will be established in order to infer a more correct diagnosis on the basis of maximum information gain with cost and time restrictions. Additionally. differential diagnosis will be carried out based on the information gained.

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Wind-induced fragility assessment of protruding sign structures

  • Sim, Viriyavudh;Jung, WooYoung
    • Wind and Structures
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    • v.31 no.5
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    • pp.381-392
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    • 2020
  • Despite that the failure of sign structure may not have disastrous consequence, its sheer number still ensures the need for rigorous safety standard to regulate their maintenance and construction. During its service life, a sign structure is subject to extensive wind load, sometimes well over its permissible design load. A fragility analysis of a sign structure offers a tool for rational decision making and safety evaluation by using a probabilistic framework to consider the various sources of uncertainty that affect its performance. Wind fragility analysis was used to determine the performance of sign structure based on the performance of its connection components. In this study, basic wind fragility concepts and data required to support the fragility analysis of the sign structure such as sign panel's parameters, connection component's parameters, as well as wind load parameters were presented. Fragility and compound fragility analysis showed disparity between connection component. Additionally, reinforcement of the connection system was introduced as an example of the utilization of wind fragility results in the retrofit decision making.

Development and validation of strip bending tester for measuring mechanical properties of freestanding thin films (자유지지 박막의 기계적 물성 측정을 위한 띠굽힘시험기의 개발 및 검증)

  • Park, Jung-Min;Kim, Jae-Hyun;Lee, Hak-Joo
    • Proceedings of the KSME Conference
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    • 2008.11a
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    • pp.49-55
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    • 2008
  • Strip bending test has been frequently utilized to measure the mechanical properties of freestanding thin films in substitute for the micro-tensile test. However, in spite of its simplicity and reliability, strip bending test has a few problems, for example, the measurement of strain and the calculation of stress at zero strain. In this study, these problems are precisely reviewed and proved. Upon this review, strip bending tester has been developed, which uses the confocal laser displacement meter to measure the deformed configuration of the specimen and the possibility and limitation of this testing system is carefully investigated including the estimation of uncertainty of the measurement of strain. Finally, to prevent errors and to improve the accuracy of this testing system, the shape of the specimen has been carefully studied and is proposed.

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Design of Checklist for Improvement of Reliability of Uncertainty and Variability Environment (불확실성 및 가변성 환경의 신뢰성 향상을 위한 체크리스트 설계)

  • Lee, Eun-Ser
    • KIPS Transactions on Software and Data Engineering
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    • v.3 no.10
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    • pp.389-396
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    • 2014
  • There are many defects when we're working on a project. Especially, if we don't have experience in similar field, defects have a strong influence on the system entirely. Therefore, management of risk such like defects is important the factor for success of project. Finally, efficient management of risk can guarantee handling problems such like fault tolerancy, unexpected quality and delay of schedule. In this paper, we propose checkpoint for improvement of reliability and are willing to improve the reliability of an entire system using it.

Nonlinear Control for A Robot Manipulator (로봇 매니퓰레이터에 대한 비선형 제어)

  • 이종용;이상효
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.17 no.12
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    • pp.1333-1342
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    • 1992
  • This paper deals with a robot manipulator having actuator which is described by equation $D(q)\ddot{q}=u-P(q\;\dot{q},\;\ddot{q})$ where u(t) is a control input. We employ two steps of controller design procedures. First, a global linearization is performed to yield a decoupled controllable linear system. Then a controller is designed for this linear system. We provide a rigorous analysis of the effect of uncertainty of the dynamics, which we study using robustness results in time domain based on a Lyapunov equation and the total stability theorem. Using this approach we simulate the performance of controller of a robot manipulator.

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