• Title/Summary/Keyword: Multi-axis Errors

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Evaluation Method of the Multi-axis Errors for Machining Centers (머시닝센터의 다축오차 평가 방법)

  • Hwang, Joo-Ho;Shim, Jong-Youp;Ko, Tae-Jo
    • Journal of the Korean Society for Precision Engineering
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    • v.28 no.8
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    • pp.904-914
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    • 2011
  • The volumetric errors of CNC machining centers are determined by 21 errors, including 3 linear errors, 6 straightness errors, 3 perpendicular errors, 9 angular errors and non-rigid body errors of the machine tool. It is very time consuming and hard to measure all of these errors in which laser interferometer and other parts are used directly. Hence, as many as 21 separate setups and measurements are needed for the linear, straightness, angular and perpendicular errors. In case of the 5-axis machining centers, two more rotary tables are used. It can make 35 error sources of the movement. Therefore, the measured errors of multi movements of the 5-axis tables are very complicated, even if the relative measured errors are measured. This paper describes the methods, those analyze the error sources of the machining centers. Those are based on shifted diagonal measurements method (SDM), R-test and Double ball bar. In case, the angular errors of machine are small enough comparing with others, twelve errors including three linear position errors, six straightness errors and three perpendicular errors can be calculated by using SDM. To confirm the proposed method, SDM was applied to measuring 3 axes of machine tools and compared with directly measurement of each errors. In addition, the methods for measuring relative errors of multi-axis analysis methods using R-test and Double Ball Bar are introduced in this paper.

Development of a Multi-joint Robot Manipulator for Robot Milking System (로봇 착유시스템을 위한 다관절 매니퓰레이터 개발)

  • Kim W.;Lee D. W.
    • Journal of Biosystems Engineering
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    • v.30 no.5 s.112
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    • pp.293-298
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    • 2005
  • The purpose of this study was the development of a multi-joint robot manipulator for milking robot system. The multi-joint robot manipulator was controlled by 5 drivers with driver controller through the position information obtained from the image processing system. The robot manipulator to automatically attach each teat cup to the teats of a milking cow was developed and it's motion was accurately measured with error rate. Results were as follows. 1. Maximum errors in position accuracy were 4mm along X-axis, 4.5mm along Y-axis and 0.9mm along Z-axis. Absolute distance errors were maximum 4.8mm, minimum 2.7mm, and average 3.6mm. 2. Errors of repeatability were maximum 3.0mm along X-axis, 3.0mm along Y-axis, and 0.5mm along Z-axis. Distance error values were maximum 3.2mm, minimum 2.2mm, and average 2.5mm. It is envisaged that multi-joint robot manipulator can be applicate to milking robot system being developed in consideration of the experiment results.

Estimation and Evaluation of Volumetric Position Errors for Multi-axis Machine Tools (다축공작기계의 공간오차 예측 및 검증)

  • Hwang, Jooho;Nguyen, Ngoc Cao;Bui, Chin Ba;Park, Chun-Hong
    • Journal of the Korean Society of Manufacturing Technology Engineers
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    • v.23 no.1
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    • pp.1-6
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    • 2014
  • This paper describes a method of estimating and evaluating the volumetric errors of multi-axis machine tools. The estimation method is based on a generic model that was developed from conventional kinematic error models for the geometric and thermal errors to help predict the volumetric error easily in various configurations. To demonstrate the advantages of the model, an application in the early stages of a five-axis machine tool design is presented as an example. The model was experimentally evaluated for a four-axis machine tool by using the data from ISO230-6 and R-test measurements to compare the estimated and measured volumetric errors.

Development of the Calibration Algorithm of 3 Axis Vector Sensor Using Ellipsoid (타원체를 이용한 3축 센서의 실시간 보정 알고리듬 개발)

  • Hwang, Jung Moon;Kim, Jung Han
    • Journal of the Korean Society for Precision Engineering
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    • v.32 no.7
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    • pp.643-651
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    • 2015
  • Multi-axis magnetic and accelerometer sensor are widely used in consumer product such as smart phones. The vector output of multi-axis sensors have errors on each axis such as offset error, scale error, non-orthogonality. These errors cause many problems on the performance of the applications. In this paper, we designed the effective inline compensation algorithm for calibrating of 3 axis sensors using ellipsoid for mass production of multi-axis sensors. The outputs with those kinds of errors can be modeled by ellipsoid, and the proposed algorithm makes sequential mappings of the virtual ellipsoid to perfect sphere which is calibrated function of the sensor on three-dimensional space. The proposed calibrating process composed of four main stages and is very straightforward and effective. In addition, another imperfection of the sensor such as the drift from temperature can be easily inserted in each mapping stage. Numerical simulation and experimental results shows great performance of the proposed compensation algorithm.

Development of Computer Aided System for Error Assessoment for Multi-axis Machine Tools using the Double Ball Bar (기구볼바를 이용한 공작기계의 오차평가 시스템 개발)

  • 문준희;박희재;주종남
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 1994.10a
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    • pp.336-342
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    • 1994
  • This paper presents an useful technique for assessing the volumetric error in multi_axis machine tools using the kinematic double ball bar and 3 dimensional spherical contouring. The developed system proposes the 3 dimensional spherical contour for the error analysis. The developed system input the measured radial data, analysing the volumetric errors such as positional, strightness, angle, and squareness errors, etc. The developed system has been tested in a practical machine tool, and showed high

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Accuracy Evaluation and Enhancement of Machine Tools Using a Kinematic Ball Bar (기구볼바를 이용한 가공기계의 정밀도 평가 및 향상 기술 개발)

  • Moon, J.H.;Pahk, H.J.;Chu, C.N.
    • Journal of the Korean Society for Precision Engineering
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    • v.13 no.6
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    • pp.114-121
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    • 1996
  • This paper presents an useful technique for assessing the volumetric errors in multi-axis machine tools using the kinematic double ball bar. This system has been developed based on the volumetric error map which describes the 3 dimensional errors of machine tools. The developed system inputs the measured radial data of 3 different planes, respectively XY,YZ,ZX, analysing the volumetric errors such as positional. straightness, angle, and squareness errors, etc. The developed system has been tested in a practical machine tool, and showed high potential for the error assessment of multi-axis machine tools.

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Signal Processing Method for Noise Reduction of Multi-Axis Force Sensors (다축힘센서의 노이즈신호 개선을 위한 신호처리 방법)

  • 김용찬;강철구;남현도
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 2003.06a
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    • pp.1026-1029
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    • 2003
  • There are always some errors in force sensing of multi-axis force sensors that aggravate sensor performance. Error sources may be classified mainly in two groups. One is structural error due to inaccuracy of sensor body, and the other is error due to noise signals existing in the sensed information. This paper presents a brief review about the principle of multi-axis force sensors, and then a method that can reduce the effect of noise signals. The method is to read digital signals in computer instead of analog voltage signals. We can eliminate the bad effect of electromagnetic waves emitted from computer and of 60 Hz noise emitted from AC source by the proposed method. The proposed method is investigated through experimental demonstration. The experimental results show the proposed method improves the sensor performance significantly.

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