• 제목/요약/키워드: delay estimation

검색결과 652건 처리시간 0.023초

이산화 오차를 고려한 ZCP 추정방법과 고속 BLDC 센서리스 구동에 관한 연구 (A Study of the ZCP Estimation Methods considering Discretization Error and High Speed BLDC Sensorless Drive)

  • 서은정;손정원;선우명호;이우택
    • 한국자동차공학회논문집
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    • 제22권1호
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    • pp.95-102
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    • 2014
  • This paper presents zero crossing point(ZCP) estimation methods considering discretization error for a high speed brushless DC(BLDC) motor drive. The ZCP is estimated by detecting the change of back-EMF polarity for the BLDC sensorless drive, and the discretization error exist on the estimated ZCP. The discretization error of the ZCP is a cause of the delay of a commutation timing of current and increment of a current ripple factor. Besides a delay of a ZCP estimation brings on the limitation of a speed range for the BLDC sensorless drive. The compensation method based on the error analysis with probability theory for reducing the effects of the discretization error of the ZCP is proposed. Also a ZCP estimation method according to the Back-EMF patterns is proposed to widen the speed range for the BLDC sensorless drive. The proposed methods are verified by the experiment.

2채널 제어 구조를 사용한 양방향 원격조종 시스템의 투명도 구현 (Transparency Implementation for Bilateral Teleoperation System by using Two-channel Control Architecture)

  • 김종현;장평훈;박형순
    • 대한기계학회논문집A
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    • 제27권11호
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    • pp.1967-1978
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    • 2003
  • Transparency has been considered as a performance measure in bilateral teleoperation system. Therefore, many issues of transparency have been studied. This paper investigates the transparency in two-channel control architectures. At first, we show the feasibility using analytic transparency-conditions and present the two classes of two-channel control architecture, which are perfectly transparent under ideal situation. In addition, remedies to problems due to impedance model estimation errors under real situation are introduced. They are as fellows; design guideline of control parameters to reduce the effect of model estimation error effect and introduction of time delay estimation for unknown dynamics. From these analyses, the systematic control scheme, which is stable and well transparent under real implementation, is proposed in two-channel control architecture. Finally, the proposed scheme is applied to a 2 D.O.F master-slave system and the experimental results show the validity of the theoretical work.

순환 지연 다이버시티를 갖는 DRM+ 시스템에서 파일럿 집합 선택을 이용한 정수배 주파수 오차 추정 기법 (Integer Frequency Offset Estimation by Pilot Subset Selection for DRM+ Systems with CDD)

  • 권기원;조용수
    • 한국통신학회논문지
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    • 제36권7C호
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    • pp.481-487
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    • 2011
  • CDD(Cyclic Delay Diversity)는 다중 전송 안테나를 사용하는 OFDM(Orthogonal Frequency Division Multiplexing) 시스템에서 간단히 전송 다이버시티를 얻을 수 있는 기법이다. 그러나 CDD 안테나가 적용된 OFDM 시스템에서 형성되는 채널의 주파수 선택적 특성은 정수배 주파수 옵셋(Integer Frequency Offset)과 FFT(Fast Fourier Transform) 이후의 동기화 기법들의 성능 감쇄를 발생시킨다. 본 논문은 CDD를 갖는 OFDM 기반의 DRM+ 시스템을 위한 향상된 정수배 주파수 옵셋 추정 기법을 제안한다. 제안된 기법에서는 채널의 주파수 특성이 동일한 파일롯 부분 집합을 선택함으로써 CDD에 형성되는 채널의 주파수 선택적 특성에 의한 정수배 주파수 옵셋 추정의 열화 성능을 감소시킨다. 모의실험 결과를 통해 제안된 기법의 정수배 주파수 옵셋 추정 성능이 기존 기법에 비해 향상됨을 보인다.

연속웨이블렛변환을 이용한 평판구조물에서의 충격위치 추정 (Application of a Continuous Wavelet Transform to the Impact Location Estimation in Plate Type Structures)

  • 박진호;이정한;박기용
    • 한국소음진동공학회:학술대회논문집
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    • 한국소음진동공학회 2004년도 추계학술대회논문집
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    • pp.311-316
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    • 2004
  • For the location estimation in the conventional LPMS(Loose Parts Monitoring System), it is popular to employ a group delay among the acoustic sensors installed within a 3 ft range from the impact source. However, there exists inherent error in determining the arrival time differences of the generated wave group among the neighboring sensors. To overcome this problem in this study, the two dimensional approach has been proposed and applied to effectively estimate the arrival time differences by using a continuous wavelet transform which is one of the linear time-frequency analysis methods. The experiment has been performed to both the plate model and the real steam generator in a nuclear power plant. It is expected that the reliability of the location estimation could be enhanced when the proposed time-frequency method is introduced into the LPMS system.

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ANALYSIS OF A DELAY PREY-PREDATOR MODEL WITH DISEASE IN THE PREY SPECIES ONLY

  • Zhou, Xueyong;Shi, Xiangyun;Song, Xinyu
    • 대한수학회지
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    • 제46권4호
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    • pp.713-731
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    • 2009
  • In this paper, a three-dimensional eco-epidemiological model with delay is considered. The stability of the two equilibria, the existence of Hopf bifurcation and the permanence are investigated. It is found that Hopf bifurcation occurs when the delay ${\tau}$ passes though a sequence of critical values. The estimation of the length of delay to preserve stability has also been calculated. Numerical simulation with a hypothetical set of data has been done to support the analytical findings.

An Enhanced Time Delay Observer for Nonlinear Systems

  • Park, Suk-Ho;Chang, Pyung-Hun
    • Transactions on Control, Automation and Systems Engineering
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    • 제2권3호
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    • pp.149-156
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    • 2000
  • Time delay observer (TDO), thanks to the time delay control (TDC) concept, requires little knowledge of a plant model, and hence is easy to design, robust to parameter variation and computationally efficient, yet can reconstruct states rather reliable for nonlinear plant. In this paper, we propose an improved version of TDO that solves two problems inherent in TDO as follows: TDO displays large reconstruction errors due to low-frequency uncertainty and has some restrictions on selecting its gains. By introducing a low pass filter and a state associated with it, we obtain an enhanced time delay observer (ETDO). This observer turns out to have smaller reconstruction errors than those of TDO and not to have any restriction on selecting its gains, thereby solving the problems. Through performance comparison by transfer function and simulation, we validate the analysis results of two observers (TDO and ETDO) and evaluate the performances. Finally, through experiments on BLDC motor system, the analysis results are clearly conformed.

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81미리 조명탄용 신관 KM84A1E1 지연제의 저장수명 예측 연구 (A Study of Storage Life Estimation for Delay System in the Fuse of 81mm Illuminating Projectile)

  • 장일호;김지훈;이우철;백승준;손영갑
    • 품질경영학회지
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    • 제40권3호
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    • pp.270-277
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    • 2012
  • Purpose: In this paper, storage lifetime of delay system in the fuse of 81MM illuminating projectile is estimated. Methods: Accelerated degradation testings of tungsten delay system using both temperature and humidity stresses were performed, and then delay time increase of the systems were analyzed as degradation data based on distribution-based degradation processes. Results: The estimated storage lifetime of detonator is between 11.8 years and 17.6 years with each stress-life relationship. Conclusion: Comparing with field data, storage lifetime of 90% reliability is about 12 years.

평균방법에 근거한 DOA와 지연시간추정에 관한 연구 (A Study on DOA and Delay Time Presumption based on Average Method)

  • 이관형;송우영
    • 한국시뮬레이션학회논문지
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    • 제13권2호
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    • pp.1-12
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    • 2004
  • This paper estimated the arrival angle and electric wave delay time using the space method law and the directions of arrival (DOA) estimation algorithm in case of signal correlation. Space method law is the method used to repress cross correlation before applying the weight value to the receiving signal. The values of the diagonal elements in the correlation matrix were averaged to replace as the diagonal elements value. In the area of wireless communication or mobile communication, there are high correlations in case of low delay time difference in multiple waves. This causes the quality of the communication to drop due to interference with the desired signal elements. This paper estimated the arrival angle and electric wave delay time using the space method law and the MUSIC algorithm. With the arrival angle algorithm, the arrival angle cannot be estimated below 5 in case of signal correlations because the angle resolution capacity decreases accordingly. The super resolution capacity was estimated to determine the arrival angle below 5 in this paper. In addition, the proposed algorithm estimated the short delay time difference to be below 20ns.

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Investigating delay factors in construction industry: A Korean perspective

  • Acharya, Nirmal Kumar;Im, Hae-Man;Lee, Young-Dai
    • 한국건설관리학회논문집
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    • 제7권5호
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    • pp.177-190
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    • 2006
  • Construction projects are facing delay problems. Delays in construction have been immense effect on performance or satisfactory delivery of the project. Delays have been causing project cost overrun as well as it is a source of dispute hence damaging the relationship between the project participants. The purpose of this study was to explore the causes of delay risk through a field survey study. Data were collected from construction professionals working in owner, consultant and contractor organizations. All together 208 questionnaire instruments were used and analyzed by employing statistical tools (SPSS computer program). 19 delay factors were identified by this study, out of which following factors were critical: Frequent interruptions from public (local people, pressure group etc.), changed site condition, failure to provide required construction site, unrealistic project time estimation and design errors.

멀티캐스트 지연변이 문제에 대한 효율적인 코어 선택 추정 알고리즘 (The Algorithm of Efficient Core Selection Estimation for the Multicast Delay Variation Problem and Minimum Delay Variation)

  • 안영진;김문성;추현승
    • 인터넷정보학회논문지
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    • 제8권2호
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    • pp.33-41
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    • 2007
  • 멀티캐스트 기술이 발전함에 따라 멀티캐스트 라우팅을 지원하는 실시간 그룹 어플리케이션들이 정점 증가하고 있으며 더욱 중요하게 되어가고 있다. 실시간 어플리케이션의 가장 중요한 요소 중의 하나는 지연변이 문제가 있으며 이는 DVBMT(Delay- and delay Variation-Bounded Multicast Tree) 문제로 잘 알려져 있다. DVBMT 문제란 제한된 시간 내에 종단간의 지연과 지연변이를 만족시키는 것을 뜻한다. DVBMT는 NP-Complete 문제로 알려져 있으며, 이를 풀기 위한 시도로 DVMA(Delay Variation Multicast Algorithm), DDVCA(Delay and Delay Variation Constratint Algorithm) 등이 제안된 바 있다. 본 논문에서는 이러한 알고리즘보다 더욱 효율적인 알고리즘을 제안한다. 성능평가를 통한 본 알고리즘의 효율성은 DDVCA보다 더욱 높은 것으로 평가되었으며 그 효율 정도는 $9%{\sim}29%$ 성능향상을 보인다. 본 논문의 시간복잡도는 DDVCA와 같은 $O(mn^2)$M이다.

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