• Title/Summary/Keyword: motion error compensation

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Adaptive Force Ripple Compensation and Precision Tracking Control of High Precision Linear Motor System (초정밀 선형 모터 시스템의 적응형 힘리플 보상과 정밀 트랙킹 제어)

  • Choi Young-Man;Gweon Dae-Gab;Lee Moon G.
    • Journal of the Korean Society for Precision Engineering
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    • v.22 no.12 s.177
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    • pp.51-60
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    • 2005
  • This paper describes a robust control scheme for high-speed and long stroke scanning motion of high precision linear motor system consisting of linear motor, air bearing guide and position measurement system using heterodyne interferometer. Nowadays, semiconductor process and inspection of wafer or LCD need high speed and long travel length for their high throughput and extremely small velocity fluctuations or tracking errors. In order to satisfy these conditions, linear motor system are widely used because they have large thrust force and do not need motion conversion mechanisms such as ball screw, rack & pinion or capstan with which the system are burdened. However linear motors have a problem called force ripple. Force ripple deteriorates the tracking performances and makes periodic position errors. So, force ripple must be compensated. To maximize the tracking performance of linear motor system, we propose the control scheme which is composed of a robust control method, Time Delay Controller (TDC) and a feedforward control method, Zero Phase Error Tracking Control (ZPETC) for accurate tracking a given trajectory and an adaptive force ripple compensation (AFC) algorithm fur estimating and compensating force ripple. The adaptive ripple compensation is continuously refined on the basis of tracking error. Computer simulation results based on modeled parameters verify the effectiveness of the proposed control scheme for high-speed, long stroke and high precision scanning motion and show that the proposed control scheme can achieve a sup error tracking performance in comparison to conventional TDC control.

Compensation of Errors on Car Black Box Records and Trajectory Reconstruction Analysis (자동차 블랙박스 기록 오차 보정과 경로 재구성 해석)

  • Yang, Kyoung-Soo;Lee, Won-Hee;Han, In-Hwan
    • Transactions of the Korean Society of Automotive Engineers
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    • v.12 no.6
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    • pp.182-190
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    • 2004
  • This paper presents reconstruction analysis of vehicle trajectory using records of a developed black box, and results of validation tests. For reconstruction of vehicle trajectory, the black box records the longitudinal and lateral accelerations and yaw-rate of vehicle during a pre-defined time period before and after the accident. One 2-axis accelerometer is used for measuring accelerations, and one vibrating structure type gyroscope is used for measuring yaw-rate of vehicle. The vehicle's planar trajectory can be reconstructed by integrating twice accelerations along longitudinal and lateral directions with yaw-rate values. However, there may be many kinds of errors in sensor measurements. The causes of errors are as follows: mis-alignment, low frequency offset drift, high frequency noise, and projecting 3-dimensional motion into 2-dimensional motion. Therefore, some procedures are taken for error compensation. In order to evaluate the reliability and the accuracy of trajectory reconstruction results, the black box was mounted on a passenger car. The vehicle was driven and tested along various specified lanes. Through the tests, the accuracy and usefulness of the reconstruction analysis have been validated.

Development of a Hydrostatic Guideway Driven by the Linear Motor (리니어모터를 이용한 초정밀 유정압안내면 개발)

  • 박천홍;오윤진;황주호;이득우
    • Journal of the Korean Society for Precision Engineering
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    • v.21 no.6
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    • pp.139-144
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    • 2004
  • In order to discuss the availability of hydrostatic guideways driven by the coreless linear motor to ultra precision machine tools, a prototype of guideway is designed and tested in this research. A coreless linear DC motor with the continuous force of 156 N and a laser scale with the resolution of 0.01 ${\mu}{\textrm}{m}$ are used as the feeding system. The experiments are performed on the static stuffiness, motion accuracy, positioning accuracy, microstep response and variation of velocity. The guideway has the infinite axial stillness within 50 N of applied load, and by the motion error compensation method using the Active Controlled Capillary, 0.08 ${\mu}{\textrm}{m}$ of linear motion error and 0.1 arcsec of angular motion error are acquired. The guideway also has 0.21 ${\mu}{\textrm}{m}$ of positioning error and 0.09 ${\mu}{\textrm}{m}$ of repeatability, and it shows the stable response against the 0.01 ${\mu}{\textrm}{m}$ resolution step command. The velocity variation of feeding system is less than 0.6 %. From these results, it is confirmed that the hydrostatic guideway driven by the coreless linear motor is very useful fur the ultra precision machine tools.

Adaptive spatio-temporal deinterlacting algorithm based on bi-directional motion compensation (양방향 움직임 기반의 시공간 적응형 디인터레이싱 기법)

  • Lee, Sung-Gyu;Lee, Dong-Ho
    • Journal of the Institute of Electronics Engineers of Korea SP
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    • v.39 no.4
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    • pp.418-428
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    • 2002
  • In this paper, we propose a motion-adaptive de-interlacing method using motion compensated interpolation. In a conventional motion compensated method, a simple pre-filter such as line averaging is applied to interpolate missing lines before the motion estimation. However, this method causes interpolation error because of inaccurate motion estimation and compensation. In the proposed method, EBMF(Edge Based Median Filter) as a pre-filter is applied, and new matching method, which uses two same-parity fields and opposite-parity field as references, is proposed. For further improvement, motion correction filter is proposed to reduce the interpolation error caused by incorrect motion. Simulation results show that the proposed method provides better performance than existing methods.

Precision Measurement System forBall Screw Pitch Error (볼스크류 전구간 피치오차 측정시스템)

  • 박희재;김인기
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 1993.10a
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    • pp.279-285
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    • 1993
  • This paper presents a precision automatic measuring system for ball screw Pitch. Ball screw is mounted on a precision indexing table, and the ball screw pitch is measured via magnetic scale, where the indexing and measurement are performed by a PC. For precision indexing of ball screw, direct driven motor is coupled to the designed dead and live centers; the performance of the centers are assessed with a precision master sylinder,such as radial motion,tilt motion, and axial motions. An error compensation model is constructed for the measurement system of ball screw pitch, where the error motions of indexing system as well as the scale measurement system are combined to give the measurement error for the ball screw. The developed system proposes an automated precision measurement system for manufacturers and users of ball screw.

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A High-Resolution Image Reconstruction Method Utilizing Automatic Input Image Selection from Low-Resolution Video (저해상도 동영상에서의 자동화된 입력영상 선별을 이용한 고해상도 영상 복원 방법)

  • Kim Sung-Deuk
    • Journal of the Institute of Electronics Engineers of Korea SP
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    • v.43 no.2 s.308
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    • pp.12-18
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    • 2006
  • This paper presents a method to extract a good high-resolution image from a low-resolution video in an automatic manner. Since a high-resolution image reconstruction method utilizing several low-resolution input images works better than a conventional interpolation method utilizing single low-resolution input image only if the input images are well registered onto a common high-resolution grid, low-resolution input images should be carefully chosen so that the registration errors can be carefully considered. In this paper, the statistics obtained from the motion-compensated low-resolution images are utilized to evaluate the feasibility of the input image candidates. Maximum motion-compensation error is estimated from the high-resolution image observation model. U the motion-compensation error of the input image candidate is greater than the estimated maximum motion-compensation error, the input image candidate is discarded. The number of good input image candidates and the statistics of the motion-compensation errors are used to choose final input images. The final input images chosen from the input image selection block are given to the following high-resolution image reconstruction block. It is expected that the proposed method is utilized to extract a good high-resolution image efficiently from a low-resolution video without any user intervention.

Frame Error Concealment Using Pixel Correlation in Overlapped Motion Compensation Regions

  • Duong, Dinh Trieu;Choi, Byeong-Doo;Hwang, Min-Cheol;Ko, Sung-Jea
    • ETRI Journal
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    • v.31 no.1
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    • pp.21-30
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    • 2009
  • In low bit-rate video transmission, the payload of a single packet can often contain a whole coded frame due to the high compression ratio in both spatial and temporal domains of most modern video coders. Thus, the loss of a single packet not only causes the loss of a whole frame, but also produces error propagation into subsequent frames. In this paper, we propose a novel whole frame error concealment algorithm which reconstructs the first of the subsequent frames instead of the current lost frame to suppress the effects of error propagation. In the proposed algorithm, we impose a constraint which uses side match distortion (SMD) and overlapped region difference (ORD) to estimate motion vectors between the target reconstructed frame and its reference frame. SMD measures the spatial smoothness connection between a block and its neighboring blocks. ORD is defined as the difference between the correlated pixels which are predicted from one reference pixel. Experimental results show that the proposed algorithm effectively suppresses error propagation and significantly outperforms other conventional techniques in terms of both peak signal-to-noise ratio performance and subjective visual quality.

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Development of the Precise Multi-Position Alignment Method using a Pitch Motion (피치운동을 이용한 정밀 다위치 정렬기법 개발)

  • Lee, Jung-Shin
    • Journal of the Korea Institute of Military Science and Technology
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    • v.13 no.4
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    • pp.708-715
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    • 2010
  • In Strapdown Inertial Navigation System, alignment accuracy is the most important factor to determine the performance of navigation. However by an existing self-alignment method, it takes a long time to acquire the alignment accuracy that we want. So, to attain the desired alignment accuracy in as little as $\bigcirc$ minutes, we have developed the precise multi-position alignment method. In this paper, it is proposed a inertial measurement matching transfer alignment method among alignment methods to minimize the alignment error in a short time. It is based on a mixed velocity-DCM matching method be suitable to the operating environment of vertical launching system. The compensation methods to reduce misalign error, especially azimuth angle error incurred by measurement time-delay error and body flexure error are analyzed and evaluated with simulation. This simulation results are finally confirmed by experimentations using FMS(Flight Motion Simulator) in Lab and the integration test to follow the fire control mission.

Design of In-Motion Alignment System of SDINS using Robust EKF

  • Hong, Hyun-Su;Lee, Jang-Gyu;Park, Chan-Gook
    • 제어로봇시스템학회:학술대회논문집
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    • 2001.10a
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    • pp.177.3-177
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    • 2001
  • In this paper, the design of the in-motion alignment system of Strapdown Inertial Navigation System(SDINS) using Robust Extended Kalman Filter(REKF) is presented. The compensation of errors in the aided navigation system is accomplished by the indirect feedback filtering. The performance of the aided navigation algorithm is very sensitive to the accuracy of the initial estimate, which is the characteristic of the EKF. Unfortunately, the initial attitude error can be very large during the in-motion alignment. To overcome the in-motion alignment under large initial attitude error problem, the REKF using linear robust filtering technique is proposed. The linear robust H$_2$ filter can be adopted for nonlinear ...

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Evaluation and Analysis of Dynamic Characteristics in Tilt Actuator for High Density Optical Storage Devices (고밀도 광저장 기기용 틸트 액추에이터 동특성 분석 및 평가)

  • 김석중;이용훈;최한국
    • Journal of KSNVE
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    • v.10 no.4
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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.

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