• 한국정밀공학회지
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• 제10권2호
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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.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2004년도 ICCAS
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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.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2013년도 춘계학술대회 논문집
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• pp.113-114
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• 2013

• Journal of Mechanical Science and Technology
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• 제20권3호
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• pp.345-357
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• 2006

By employing the concept of equivalent linkage, this paper presents an analytical method for analyzing the mechanical errors of disk cam mechanisms with a flat-faced follower. The resulting error equations do not really involve the location of the curvature center of the cam profile, and locating the curvature center of the cam profile is not essential. The resulting errors are significantly affected by the pressure angle, and the smaller pressure angle will result in the smaller mechanical error. In the worst case, owing to the joined effects of various design parameters, the accuracy of the follower motion may degrade considerably. For the oscillating follower case, all acceleration error functions have a sudden change at every beginning and at every end of the motion even though the theoretical follower displacement is cycloidal motion.

• ETRI Journal
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• 제28권5호
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• pp.574-582
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• 2006

In this paper, a new error concealment algorithm is proposed for the H.264 standard. The algorithm consists of two processes. The first process uses a fuzzy logic method to select the size type of lost blocks. The motion vector of a lost block is calculated from the current frame, if the motion vectors of the neighboring blocks surrounding the lost block are discontinuous. Otherwise, the size type of the lost block can be determined from the preceding frame. The second process is an error concealment algorithm via a proposed adapted multiple-reference-frames selection for finding the lost motion vector. The adapted multiple-reference-frames selection is based on the motion estimation analysis of H.264 coding so that the number of searched frames can be reduced. Therefore the most accurate mode of the lost block can be determined with much less computation time in the selection of the lost motion vector. Experimental results show that the proposed algorithm achieves from 0.5 to 4.52 dB improvement when compared to the method in VM 9.0.

• 한국융합학회논문지
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• 제11권2호
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• pp.271-279
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• 2020

스쿼트와 런지운동은 다양한 프리웨이트운동 중 몸통과 하체강화를 위한 중요한 운동으로 운동자세에 대한 이론적 근거 및 운동기준 동작의 확립을 통해 안전하고 효과적인 운동이 이루어져야 한다. 따라서 옵티멀 운동동작을 통한 부상 예방과 오류 동작에 대한 과학적 대응방안을 마련하기 위해 운동모형의 개발이 필요한 현실이며 이러한 목적으로 오류동작에 따른 자세교정을 위해 다양한 보조기구를 활용하는 방법이 효과적이다. 본 논문에서는 프리웨이트운동의 동적분석을 위해 지면반발력에 대응한 로드셀을 이용한 4포인트 하중검출을 통해 동적동작에 기반한 운동모형 분석시스템을 개발하고자 한다. 프리웨이트운동의 모형개발을 위해 동적 움직임을 단순화하여 구분동작에 따른 운동 모델링을 확립하고 동적인 동작분석을 통해 오류동작을 분석하고 보정하기 위한 수치정량화 데이터를 확보하였고 이를 활용할 수 있는 분석방법에 대한 타당성을 검증하였다.

• 한국정밀공학회지
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• 제30권6호
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• pp.607-614
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• 2013

In this study, effect of the sensor gain error is theoretically analyzed and simulated when mixed sequential two-prove method(MTPM) is applied for the precision measurement of straightness error of a linear motion table. According to the theoretical analysis, difference of the gain errors between two displacement sensors increases measurement error dramatically and alignment error of the straightedge is also amplified by the sensor gain difference. On the other hand, if the gain errors of the two sensors are identical, most of error terms are cancelled out and the alignment error doesn't give any influence on the measurement error. Also the measurement error of the straightness error is minimized compared with that of the straightedge's form error owing to close relationship between straightness error and angular motion error of the table in the error terms.

• International Journal of Precision Engineering and Manufacturing
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• 제6권2호
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• pp.55-60
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• 2005

In order to develop the hydrostatic guideways driven by a core less linear motor for ultra precision machine tools, a prototype of guideway is designed and tested. A coreless linear DC motor with a continuous force of 156 N and a laser scale with a resolution of 0.01 ㎛ are used in the system. Experimental analysis on the static stiffness, motion errors, positioning error and its repeatability, micro step response and velocity variation of the guideway are performed. The guideway shows infinite stiffness within 50 N applied load in the feed direction, and by the motion error compensation method using the Active Controlled Capillary, 0.08 ㎛ linear motion error and 0.1 arcsec angular motion error are acquired. The guideway also reveals 0.21 ㎛ positioning error and 0.09 ㎛ repeatability, and it shows stable responses following a 0.01 ㎛ resolution step command. The velocity variation of feeding system is less than 0.6 ％. From these results, it is estimated that the hydrostatic guideway driven by a coreless linear motor is very useful for the ultra precision machine tools.

• 한국자동차공학회논문집
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• 제5권1호
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• pp.69-78
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• 1997

Main sources of the vibration in gear driving system are transmission error and backlash. Transmission error is the difference of the rotation between driving and driven gear due to tooth deformation and profile error. Vibro-impacts induced by backlash between meshing gears lead to excessive vibration and noise in many geared rotation systems. Nonlinear dynamic characteristics of the gear driving system due to transmi- ssion error and backlash are investigated. Transmission error is calculated for spur gear. Nonlinear equation of motion for the gear driving system is developed with the calculated transmission error and backlash. Numerical analysis of the equation and the experimental results show the existence of meshing frequency, superharmonic compon- ents. Instability of the gear driving motion is found on the basis of Mathieu equation. Rattle vibration due to backlash is also discussed on the basis if nonlinear jump phenomenon.

• 소음진동
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• 제10권4호
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• pp.584-595
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• 2000

We design a new actuator for high density optical device in order to control the radial tilting motion. The newly designed actuator makes it possible to control the tilting motion actively, while the coventional actuator compress tilting motion with passive spring. First of all, We present 3-dimensional modeling of actuator and accomplish the modal analysis and magnetic analysis of actuator. Due to these results, a new designed actuator has performance of high sensitivity and high second resonance frequency. Secondly, We present the 3-DOF dynamic modeling of the 4-wire spring type actuator. sensitivity analysis is performed to consider the assembling error, such as the difference of mass center and force center. From these results, the sensitivities of rotation due to the assembly error are revealed and design criteria of rotation is presented. And experimental results of a newly designed actuator are presented and compared with theoretical results. Finally, We propose a dynamic tilt compensation and high acceleration actuator for high density optical storage devices.