• Title/Summary/Keyword: Open Loop

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Design formulas for vibration control of taut cables using passive MR dampers

  • Duan, Yuanfeng;Ni, Yi-Qing;Zhang, Hongmei;Spencer, Billie.F. Jr.;Ko, Jan-Ming;Fang, Yi
    • Smart Structures and Systems
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    • v.23 no.6
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    • pp.521-536
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    • 2019
  • Using magnetorheological (MR) dampers in multiswitch open-loop control mode has been shown to be cost-effective for cable vibration mitigation. In this paper, a method for analyzing the damping performance of taut cables incorporating MR dampers in open-loop control mode is developed considering the effects of damping coefficient, damper stiffness, damper mass, and stiffness of the damper support. Making use of a three-element model of MR dampers and complex modal analysis, both numerical and asymptotic solutions are obtained. An analytical expression is obtained from the asymptotic solution to evaluate the equivalent damping ratio of the cable-damper system in the open-loop control mode. The individual and combined effects of the damping coefficient, damper stiffness, damper mass and stiffness of damper support on vibration control effectiveness are investigated in detail. The main thrust of the present study is to derive a general formula explicitly relating the normalized system damping ratio and the normalized damper parameters in consideration of all concerned effects, which can be easily used for the design of MR dampers to achieve optimal open-loop vibration control of taut cables.

Handling Deflection Limit in Open-Loop-Onset-Point PIO Analysis (Open-Loop-Onset-Point PIO 해석의 변위한계)

  • Park, Sang-Hyuk
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.38 no.2
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    • pp.135-140
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    • 2010
  • A new treatment is proposed to handle a deflection limit in the open-loop-onset-point (OLOP), which is commonly used in the prediction of pilot in-the-loop oscillation (PIO) due to a rate saturation. The new approach is motivated by the frequency response of a stand-alone actuator in that, unlike the suggestion by the original OLOP procedure, the rate limit onset is not delayed to a higher frequency by a deflection limit. Indeed, if a feedback control loop is closed, the rate limit onset can be shifted to a lower frequency since the controller tends to react with larger commands when deflection limited. The amplitude of the command at this onset frequency is combined with the deflection limit to estimate the associated gain reduction in the open-loop-onset-point in the final step of the OLOP process. The comparison of the new approach with the previous method reveals that an inaccurate optimism which can occur in the previous method is corrected by the proposed treatment.

Vibration Localization of Open Loop Repeated Structures (개방형 반복구조물의 진동국부화)

  • 하동진;유홍희
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2003.05a
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    • pp.489-494
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    • 2003
  • Vibration localization characteristics of open loop repeated structures with mistuning are investigated in this paper. Mistuning of a periodic structure often creates significant non-uniformity in vibration responses. As a result of the localization, critical fatigue problems often occur in repeated structures. Therefore, it is of great importance to predict the vibration response of the mistuned repeated structures accurately. In this paper, a simplified model for the open-loop repeated structure is introduced and dimensionless parameters which influence the localization characteristics are identified. The effects of the parameters on the localization characteristics are investigated through numerical study.

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Performance Analysis of the Optoelectronic Oscillator using the Direct Modulation Laser (레이저 직접 변조를 이용한 광전 발진기의 성능 분석)

  • Cho, Jun-Hyung;Heo, Seo-Weon;Sung, Hyuk-Kee
    • Journal of the Korea Institute of Information and Communication Engineering
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    • v.18 no.8
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    • pp.2029-2036
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    • 2014
  • The performance analysis of optoelectronic oscillator(OEO) based on a directly modulated semiconductor laser was theoretically achieved. First, the analysis was performed on the open response of the key components that constitute the OEO loop. Using the results, we simulated the open-loop characteristics of the OEO loop. By combining oscillation conditions of loop oscillator in addition to the open-loop magnitude and phase responses, theoretical performance analysis such as OEO's oscillation frequency, spurious tones and phase noise was successfully completed.

A Study on Startup-Characteristic of Sensorless Controlled IPMSM Employing Sliding Mode Observer (슬라이딩 모드 관측기를 이용한 IPMSM의 센서리스 제어의 기동특성에 관한 연구)

  • Kim, Sang-Hun;Kwon, Soon-Jae;Kim, Marn-Go;Jung, Young-Seok
    • The Transactions of the Korean Institute of Power Electronics
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    • v.16 no.1
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    • pp.38-43
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    • 2011
  • This paper presents the improvement of start-up characteristic of sensorless controlled IPMSM(Interior Permanent Magnet Synchronous Motor) with SMO(Sliding Mode Observer). It is difficult to utilize the rotor position information at starting point for the back EMF estimation based sensorless control. For this reason, open loop control is normally used during start-up period. However, changing from open loop to closed loop control might bring a problem on the transient characteristics for difference load conditions. To solve this problem, we add another rotor angle controller. Simulation results and experimental results are presented to verify proposed method.

A Study on the Effect of the Magnetic Flux Feedback on Open Loop Characteristics in a Magnetic Suspension System (자기부상 시스템에서 자속 궤환이 Open-Loop 특성에 미치는 영향에 대한 연구)

  • Kim, Yong-Kyu;Lee, Jun-Ho
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2006.11a
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    • pp.181-186
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    • 2006
  • 본 논문에서는 자속 궤환을 포함하는 자기부상 시스템의 open-loop 특성에 대해서 다룬다. 훌륭한 외란 억제 특성을 포함하고 파라메타 변동에 대해서 둔감한 제어기를 설계하기 위해서 자속 궤환을 이용하는 것이 효과적일 수 있다. 적절한 센서에 의해서 측정 가능한 자속은 전류와 공극의 시간 변화에 대해서 선형적인 관계를 가지고 있으며, 자속의 궤한은 자기 부상시스템이 본질적으로 갖고 있는 전기적 엑츄에이터와 기계적 플랜트 사이의 간섭에 의해서 발생하는 비선형성을 감소시키는 역할을 한다. 모의시험 결과를 통해서 자속의 궤환이 자기부상 시스템의 부하변동에 대해서 open-loop 성능 향상에 효과적임을 보인다.

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A Study on the Open Loop Characteristics of a Magnetic Suspension System Including Magnetic Flux Feedback (자속 궤환을 포함하는 자기부상 시스템의 Open-Loop 특성에 대한 연구)

  • Lee Jun-Ho;Yun Yong-Ki;Kim Yong-Kyu
    • Journal of the Korean Society for Railway
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    • v.9 no.4 s.35
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    • pp.455-460
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    • 2006
  • 본 논문에서는 자속 궤환을 포함하는 자기부상 시스템의 open-loop 특성에 대해서 다룬다. 훌륭한 외란 억제 특성을 포함하고 파라메타 변동에 대해서 둔감한 제어기를 설계하기 위해서 자속 궤환을 이용하는 것이 효과적일 수 있다. 적절한 센서에 의해서 측정 가능한 자속은 전류와 공극의 시간 변화에 대해서 선형적인 관계를 가지고 있으며, 자속의 궤한은 자기 부상시스템이 본질적으로 갖고 있는 전기적 엑츄에이터와 기계적 플랜트 사이의 간섭에 의해서 발생하는 비선형성을 감소시키는 역할을 한다. 모의시험 결과를 통해서 자속의 궤환이 자기부상 시스템의 부하변동에 대해서 Open-loop 성능 향상에 효과적임을 보인다.

The Implementation of Train Diagram Modeling in the Open-loop Metro Line (Open-loop Metro Line에서의 열차 운전도 모델링의 구현)

  • Hong, H.S.;Yoo, K.K.;Lee, T.S.;Moon, Y.H.
    • Proceedings of the KIEE Conference
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    • 1995.11a
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    • pp.527-530
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    • 1995
  • In this paper, traffic modeling and control design was considered to analyze and improve the stability of train diagram in the open-loop Metro line. A complete discrete-event traffic model describing the natural instability of open-loop metro line is analyzed. The traffic stability properties are introduced and easy-to-implement state feed back traffic control algorithms are designed, which satisfied with system stability.

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An Effect of Car Performance Influenced to Absorbing Resistane of Air-cleaner Filter for the L. P. G Vehicle of Open Loop Fuel System (Open Loop 연료공급계의 L. P. G 차량에서 공기청정기 필터의 흡기저항이 차량성능에 미치는 영향)

  • Shin, Yong-Wha;Kim, Ki-Hyung;Jung, Jong-An
    • Journal of the Korean Society of Safety
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    • v.10 no.4
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    • pp.36-46
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    • 1995
  • The interest and purpose of this study is to control of air-fuel ratio and develop control device of a spark ignition LPG engine with adopting open loop fuel system. The air-fuel ratio is derived by considering airflow resistane of air cleaner element. The result shows that air-fuel ratio becomes more and more rich when airflow resistance increases. Experiments about the influence of airflow resistance on the engine performance, drivability and emissions are performed. Therefore, it is known that open-loop fuel system depends on the absorbing resistance of air-cleaner.

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Vibration Localization of Open Loop Repeated Structures (개방형 반복구조물의 진동국부화)

  • Ha, Dong-Jin;Yoo, Hong-Hee
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.13 no.12
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    • pp.911-917
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    • 2003
  • Vibration localization characteristics of open loop repeated mistuned structures are investigated. The mistuning often creates significant response discrepancies among subcomponents of the repeated structures. As a result of the discrepancies, critical fatigue problems often occur in repeated structures. Therefore. it is of great importance to predict the vibration response of the mistuned repeated structures accurately in this Paper, a simplified model for an open-loop repeated structure is introduced and dimensionless parameters that influence the localization characteristics are identified. The effects of the parameters on the localization characteristics are investigated through numerical study.