• Title/Summary/Keyword: rotational error

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Experimental Investigation for Rotational Error Motion Simulation of Inherently Compensated Aerostatic Journal Bearing (자성보상형 공기정압 저널베어링의 회전운동정밀도 시뮬레이션을 위한 실험적 고찰)

  • Shim, Jongyoup;Hwang, Jooho;Park, Chun-Hong
    • Journal of the Korean Society for Precision Engineering
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    • v.32 no.2
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    • pp.135-140
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    • 2015
  • It is an important thing for a designer to simulate and predict the performance of a spindle and a rotary table. In addition to the general performance such as static stiffness, the error motion performance information is beneficial to the designer in many cases. However for an aerostatic bearing the fluid film physical status should be calculated in order to simulate those performances and the calculation time is another obstacle for a simple performance simulation. In this paper the investigation on experiment and simulation is performed in order to find a more effective simulation method for the rotational error motion.

Runout Control of a Magnetically Suspended Grinding Spindle (자기베어링으로 지지된 연삭 스핀들의 런아웃 제어)

  • 노승국;경진호;박종권;최언돈
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 2000.05a
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    • pp.1011-1015
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    • 2000
  • In this paper, the case studies of reducing rotational errors is theoretically done for a grinding spindle with an active magnetic bearing system. The rotational errors acting on the magnetic bearing spindle are due to mass unbalance of rotor, runout, grinding excitation and unmodeled nonlinear dynamics of electromagnets. The adaptive feedforward method based on LMS algorithm is discussed to compensate output and input disturbances, and investigated its effectiveness by numerical simulation. The feedforward control reduced external excitation and rotational error for specified frequency. The interpolation method using impulse function for cancelling the electrical 'uncut is studied. These methods show their effectiveness for the rotational accuracy of the improving magnetic bearing spindle through some simulation results of the rotational error decreased by them.

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A Study on Error Analysis of Dual-Axis Rotational Inertial Navigation System Based on Ring Laser Gyroscope (링레이저 자이로 기반 2축 회전형 관성항법장치 오차해석에 대한 연구)

  • Kim, Cheon-Joong;Yu, Hae-Sung;Lee, In-Seop;Oh, Ju-Hyun;Lee, Sang-Jeong
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.46 no.11
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    • pp.921-933
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    • 2018
  • There is a method to enhance the pure navigation performance of INS(Inertial Navigation System) through the rotation of inertial measurement unit to compensate error sources of inertial sensors each other and that INS using this principle of operation is called rotational INS. In this paper, the exact error analysis of rotational INS based on ring laser gyro considering the coupling effect with gravity and earth rate is performed to evaluate the navigation performance by inertial sensor error sources. And error analysis and performance evaluation result confirmed by modelling and simulation is also proposed in this paper.

Rotational Accuracy Measurement of Scroll Compressor with D-type Sectional Shaft

  • Park, Sang-Shin;Kim, Gyu-Ha;Lee, Jin-Kab
    • Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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    • 2002.10b
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    • pp.125-127
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    • 2002
  • This paper presents the measurement process of the rotational accuracy and the comparison with the theoretical results in the main bearing of scroll compressor. The main bearing is cylindrical oil proceeding bearing, but there are straightly cut used for oil supply. Therefore the roundness error is not a negligible quantity compared with the rotational accuracy. For this reason, three-point method is used in the experiment. The result of three-point method coincides with the theoretical value. So if the theory in this paper is used to the bearing design of scroll compressor, the efforts for testing and designing can be reduced.

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Error in Incremental Encoder Due to Vibration and Its Solution (증분 엔코더에서 발생하는 진동에 의한 에러와 해결방안에 관한 연구)

  • Nam, Yoon-Su;Park, Hae-Kyoon
    • Journal of the Korean Society for Precision Engineering
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    • v.25 no.6
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    • pp.55-61
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    • 2008
  • Incremental encoder is a common choice for measuring the rotational angle of an axis. It produces, however, some measurement errors, if some kinds of rotational vibration are occurred. Even by increasing the number of slits on the circular peripheral, these kinds of error can not be removed. It only decreases the probability of the error being generated by making the magnitude of encoder resolution smaller than that of the axial vibration. This paper investigates the error mechanism of incremental encoder and suggests a digital logic circuit that prevents the measurement error to happen.

Development of a Rotational Torque Calibration System (회전 토크 교정장치 개발에 관한 연구)

  • 김갑순;권영하
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.17 no.10
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    • pp.2646-2653
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    • 1993
  • A rotational torque calibration system is developed to measure rotational torque of power generating systems and to calibrate non-contact rotational torque measurement systems. The maximum capacity of the developed system is 4.5 N-m. It is composed of a DC motor, a DC generator, a control system, a master torque cell, a slip ling/brush set, supporters, a bed etc. The control system is characterized by the closed-loop control with differential intergrator. Rotational torque measurement test and unit response test are conducted to estimate the accuracy of the developed system. It is found that system maintain high consistency and accuracy with the maximum error of 0.25%, Therefore the developed system can be used to measure the rotational torque of power generating systems and to calibrate non-contact rotational torque measurement systems.

Flexure Analysis of Inertial Navigation Systems

  • Kim, Kwang-Jin;Park, Chan-Gook;Park, Jai-Yong
    • 제어로봇시스템학회:학술대회논문집
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    • 2004.08a
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    • pp.1958-1961
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    • 2004
  • Ring Laser Gyroscopes used as navigational sensors inherently experience a lock-in region, where very low rotational rates are not measurable. Most RLG manufacturers use a mechanical dither motor that applies a small oscillatory rotational motion larger than this region to resolve this problem. Any input acceleration that bends this dithering axis causes flexure error, which is a noncommutative error that can not be compensated by simply using integrated gyro sensor output. This paper introduces noncommutative error equations that define attitude errors caused by flexure errors. In this paper, flexure error is classified as sensor level error if the sensing axis coincides with the dithering axis and as system level error if the two axes do not coincide. The relationship between gyro output and the rotation vector is introduced and is used to define the coordinate transformation matrix and angular motion. Equations are derived for both sensor level and system level flexure error analysis. These equations show that RLG based INS attitude error caused by flexure is directly proportional to time, amount of input acceleration and the dynamic frequency of the vehicle.

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Analysis on Influence of Errors for Dual-axis Rotational Inertial Navigation System Performance (2축 회전형 관성항법장치 성능에 영향을 미치는 오차 분석)

  • Minsu Jo;Chanju Park
    • Journal of Advanced Navigation Technology
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    • v.27 no.1
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    • pp.50-56
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    • 2023
  • INS(Inertial Navigation System) calculates navigation information using a vehicle's acceleration and angular velocity without the outside information. However, when navigation is performed for a long time, navigation error gradually diverges and the performance decreases. To enhance INS's performance, the rotation of inertial measurement unit is developed to compensate error sources of inertial sensors, which is called RINS(Rotational Inertial Navigation System). This paper analyzes the influence of several errors for dual-axis RINS and the shows the results using simulation.

A Study on Roughness Characteristic about Rotational Accuracy Variation (스핀들의 회전 정밀도에 따른 표면 거칠기 특성 연구)

  • Park, Ki-Beom;Chung, Won-Jee;Lee, Choon-Man
    • Transactions of the Korean Society of Machine Tool Engineers
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    • v.18 no.1
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    • pp.110-115
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    • 2009
  • In general, the radial error motion of a machine tool spindle system is effected on the accuracy of the parts to be made. This paper presents in milling process an investigation into spindle rotational accuracy effects on surface roughness of processing parts. We experimented the effects on spindle rotational accuracy in milling process by cutting AL 7075 workpiece at various rotational speed. In order to analyze the effects of rotational accuracy on surface roughness, we proposed the method using iSIGHT's RBF Approximation. The proposed method can be used fur anticipating the surface roughness when some spindle rotational accuracy experiments could be done in milling process.