• Title/Summary/Keyword: Error Sources

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A Study on Enhancement of the Position Accuracy of a Linear Motor (리니어 모터의 위치 정밀도 향상에 관한 연구)

  • 민경석;오준모;최우천
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 2003.06a
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    • pp.1828-1831
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    • 2003
  • There are various sources causing a position error in a linear motor. This paper focuses on error sources from rotational motions of a table and friction. Rotational errors occur due to imperfections during manufacturing and/or assembly of guide ways, and cause a position error at locations of interest. Friction is another factor deteriorating the position error due to its highly nonlinear behavior. The position error of the linear motor was about 20∼30$\mu\textrm{m}$. After compensating the position errors due to rotational error motions and friction. the remaining errors become about 6~8$\mu\textrm{m}$ and 2~3$\mu\textrm{m}$, respectively. It is shown that the positional accuracy of a linear can be greatly improved by compensating the two error sources.

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Optical Error Analyses in AQuaKET - Intensity variation, Diffraction, and Parallax

  • Kim, Young-Soo
    • Bulletin of the Korean Space Science Society
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    • 2003.10a
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    • pp.27-27
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    • 2003
  • The Automated Quantitative Knife-Edge Test (AQuaKET) method was developed for testing the surface profiles of large optics with high accuracy. Testing with the required accuracy of very large telescope is not an easy job to achieve, as it is a nano-technology. There are lots of possible error sources which can occur during the measurements and in the data processing of the AQuaKET. The error sources can be categorized into 5 areas: optics, mechanics, electronics, numerical processes, and system. In this paper, possible error sources in Optics are discussed, which are intensity variation of the light source, diffraction effects, and parallax effect. In this talk, those possible error sources in optics are presented and discussed.

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Effect of U-Joint Errors Analysis for a Cubic Parallel Device (육면형 병렬기구에서의 유니버설 조인트 오차의 영향)

  • Lim, Seung-Reung;Choi, Woo-Chun
    • Proceedings of the KSME Conference
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    • 2000.11a
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    • pp.789-794
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    • 2000
  • This study proposes an error analysis for a cubic parallel device. There are many sources of errors in the device. An error analysis is presented based on an error model formed from the relation between the universal joint error of the cubic parallel manipulator and the end effector accuracy. The analysis shows that the method can be used in evaluating the accuracy of a parallel device.

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Evaluation of Geometric Error Sources for Terrestrial Laser Scanner

  • Lee, Ji Sang;Hong, Seung Hwan;Park, Il Suk;Cho, Hyoung Sig;Sohn, Hong Gyoo
    • Journal of Korean Society for Geospatial Information Science
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    • v.24 no.2
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    • pp.79-87
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    • 2016
  • As 3D geospatial information is demanded, terrestrial laser scanners which can obtain 3D model of objects have been applied in various fields such as Building Information Modeling (BIM), structural analysis, and disaster management. To acquire precise data, performance evaluation of a terrestrial laser scanner must be conducted. While existing 3D surveying equipment like a total station has a standard method for performance evaluation, a terrestrial laser scanner evaluation technique for users is not established. This paper categorizes and analyzes error sources which generally occur in terrestrial laser scanning. In addition to the prior researches about categorizing error sources of terrestrial Laser scanning, this paper evaluates the error sources by the actual field tests for the smooth in-situ applications.The error factors in terrestrial laser scanning are categorized into interior error caused by mechanical errors in a terrestrial laser scanner and exterior errors affected by scanning geometry and target property. Each error sources were evaluated by simulation and actual experiments. The 3D coordinates of observed target can be distortedby the biases in distance and rotation measurement in scanning system. In particular, the exterior factors caused significant geometric errors in observed point cloud. The noise points can be generated by steep incidence angle, mixed-pixel and crosstalk. In using terrestrial laser scanner, elaborate scanning plan and proper post processing are required to obtain valid and accurate 3D spatial information.

Identification of motion error sources in NC machine tools by a circular interpolation test (원호보간시험에 의한 수치제어 공작기계의 운동오차원인 진단에 관한 연구)

  • Hong, Seong-Wook;Shin, Young-Jae;Lee, Hu-Sang
    • Journal of the Korean Society for Precision Engineering
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    • v.10 no.2
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    • pp.126-137
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    • 1993
  • This paper presents an efficient method for the identification of motion error sources in NC machine tools by making use of the circular interpolation test, which is often used in estimating the motion accuracy of NC machine tools. Mathematical formulae are described for motion errors due to various kinds of error sources. Two identification formulae are proposed: one is based on the frequency analysis and the other is formulated with the weithted residual method. Motion error signal is classified into two patterns, mean errors(mean of CW and CCW test signals from mean errors). The sources of the mean errors are identified by using the frequency analysis technique and the sources of the deviation errors by the weighted residual formulaltion. A menu driven, user oriented, computer program is written to realize the full steps of the proposed identificationprocedure. Then, the identification method is applied to two NC machine tools.

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Analysis of Effect of Phase Error Sources of Polarization Components in Incoherent Triangular Holography

  • Kim, Soo-Gil
    • Journal of the Optical Society of Korea
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    • v.16 no.3
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    • pp.256-262
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    • 2012
  • We derive the point-spread function of the reconstructed image from a point-source complex hologram, which includes phase error caused by polarization components, in the longitudinal direction of the point-spread function and analyze the effect of the error sources of polarization components having influence on image reconstruction of a point-source complex hologram in incoherent triangular holography.

Accurate Calibration of Kinematic Parameters for Two Wheel Differential Drive Robots by Considering the Coupled Effect of Error Sources (이륜차동구동형로봇의 복합오차를 고려한 기구학적 파라미터 정밀보정기법)

  • Lee, Kooktae;Jung, Changbae;Jung, Daun;Chung, Woojin
    • The Journal of Korea Robotics Society
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    • v.9 no.1
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    • pp.39-47
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    • 2014
  • Odometry using wheel encoders is one of the fundamental techniques for the pose estimation of wheeled mobile robots. However, odometry has a drawback that the position errors are accumulated when the travel distance increases. Therefore, position errors are required to be reduced using appropriate calibration schemes. The UMBmark method is the one of the widely used calibration schemes for two wheel differential drive robots. In UMBmark method, it is assumed that odometry error sources are independent. However, there is coupled effect of odometry error sources. In this paper, a new calibration scheme by considering the coupled effect of error sources is proposed. We also propose the test track design for the proposed calibration scheme. The numerical simulation and experimental results show that the odometry accuracy can be improved by the proposed calibration scheme.

Development of an NC Machine Performance Test and Calibration System (수치제어 공작기계의 위치오차 측정 및 보정시스템 개발)

  • 이상윤;박준호;조선휘;김문상
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.17 no.6
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    • pp.1431-1440
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    • 1993
  • This paper presents a new NC machine performance test and calibration system. In order to measure NC machine erros in simpler, and less time-comsuming way, some indirect measuring systems such as circular disk system and double ball bar system have been developed instead of laser interferometer. But these indirect measuring systems have shown their limits in identifying each of NC machine error sources in absolute numerical value. Therefore, we developed an unique NC machine error measurement system which provides a simple measuring process like other conventional indirect methods and still can indentify each of NC machine error sources in absolute numerical value.

A Study on the Uncertainty of MVRS (포구속도측정레이더의 불확도에 관한 연구)

  • Park, Yong-Suk;Choi, Ju-Ho
    • Journal of the Korea Institute of Military Science and Technology
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    • v.10 no.1
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    • pp.94-100
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    • 2007
  • MVRS's measuring principles are based on the Doppler principle. It measures the velocities near the muzzle using the doppler signal output from the antenna and then predicts the velocity of the bullet leaving the muzzle by performing the regression analysis on previous measured velocities. There are a number of error sources when calculating the muzzle velocity. Antenna has long term frequency stability error and the doppler signal from the antenna has noise. These two error sources influence the accuracy of estimated velocities from the doppler signal. Estimated velocity errors result in the random error of data statistics. And when performing a regression analysis these random error components are transferred to the fitting error component. This study also analyzed the error components according to the hardware limitations of MVRS-700 and the signal processing method, and presented the calculated uncertainty of muzzle velocity.

Quantification of Acoustic Pressure Estimation Error due to Sensor and Position Mismatch in Planar Acoustic Holography (평면 음향 홀로그래피에서 센서간 특성 차이와 측정 위치의 부정확성에 의한 음압 추정 오차의 정량화)

  • 남경욱;김양한
    • Journal of KSNVE
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    • v.8 no.6
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    • pp.1023-1029
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    • 1998
  • When one attempts to construct a hologram. one finds that there are many sources of measurement errors. These errors are even amplified if one predicts the pressures close to the sources. The pressure estimation errors depend on the following parameters: the measurement spacing on the hologram plane. the prediction spacing on the prediction plane. and the distance between the hologram and the prediction plane. This raper analyzes quantitatively the errors when these are distributed irregularly on the hologram plane The sensor mismatch and inaccurate measurement location. position mismatch. are mainly addressed. In these cases. one can assume that the measurement is a sample of many measurement events. The bias and random error are derived theoretically. Then the relationship between the random error amplification ratio and the parameters mentioned above is examined quantitatively in terms of energy.

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