• Title/Summary/Keyword: Motion Compensation

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Design of Disturbance Observer Based on Structural Analysis (구조적 분석에 기초한 외란관측기의 설계)

  • 김봉근
    • Journal of Institute of Control, Robotics and Systems
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    • v.10 no.3
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    • pp.225-231
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    • 2004
  • Disturbance observer (DOB) has been studied extensively and applied to many motion control fields during the last decades, but relatively few studies have been devoted to the development of analytic, systematic design methods for DOB itself, This paper thus aims to provide an analytic, systematic design method for DOB. To do this, DOB is structurally analyzed and the generalized disturbance compensation framework named robust internal-loop compensator (RIC) is introduced. Through this, the inherent equivalence between DOB and RIC is found, and the mixed sensitivity optimization problem of DOB is solved. Q-filter design is completely separated from the mixed sensitivity optimization problems of DOB although the proposed method has implicit .elation with Q-filter. Also, although the Q-fille. is separately designed with sensitivity function, the proposed DOB framework has the exactly same characteristic as the original DOB.

Multiresolution Motion Compensation in the Wavelet Domain (웨이블릿 영역에서의 다중해상도 움직임 보상 방법)

  • 김종태;양창모;임동근;호요성
    • Proceedings of the IEEK Conference
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    • 2001.09a
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    • pp.349-352
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    • 2001
  • 일반적인 동영상 압축 부호화 방법에서 시간적 중복 정보를 줄이기 위해 움직임 예측과 움직임 보상 방법을 이용한다. 웨이블릿 변환을 이용한 동영상 압축 부호화 기법 중에는 기존의 공간 영역에서의 움직임을 예측하는 대신에 웨이블릿 변환 영역에서 움직임을 예측하기도 한다. 이러한 방법은 움직임 예측 시간을 줄이는 장점이 있지만, 웨이블릿 변환에서 추림(Desimation)하는 과정에서 천이-변동 문제 (Shift-Variant Problem)를 일으켜 좋지 않은 성능을 나타낸다. 본 논문에서는 웨이블릿 영역에서의 다중 해상도 움직임 예측에서 천이-변동 문제를 해결하기 위한 새로운 움직임 예측과 움직임 보상 방법을 제안한다. 제안된 방법은, 기존의 공간 영역에서의 블록 정합 방법과 비교하여, 더 높은 화질을 나타낼 뿐 아니라, 주관적 화질에도 개선된 결과를 보인다.

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Boundary Strength based Adaptive Interpolation Filter (경계 강도 기반의 적응적 보간 필터)

  • Song, Yunseok;Choi, Jung-Ah;Ho, Yo-Sung
    • Proceedings of the Korean Society of Broadcast Engineers Conference
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    • 2014.06a
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    • pp.26-27
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    • 2014
  • This paper presents an adaptive interpolation filtering scheme for the High Efficiency Video Coding (HEVC) standard. In regards to interpolation for motion estimation and compensation, the conventional HEVC employs 8-tap and 4-tap filters for luma and chroma samples, respectively. Coefficients in such filters are determined by discrete cosine transform (DCT). In the proposed scheme, boundary strength values are stored after the execution of the deblocking filter. For each block, the sum of boundary strength values is calculated to indicate whether its region is complex or simple. Consequently, based on the region classification, 12-tap and 8-tap interpolation filters are used for complex and simple regions, respectively. This process is applied to luma sample interpolation only. Simulation results show 1.8% average BD-rate reduction compared to the conventional method.

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Ultra-Precision Machining Using Fast Tool Servo and On-Machine Form Measurement of Large Aspheric Mirrors (Fast Tool Servo를 이용한 대구경 반사경의 초정밀 가공 및 기상 형상 측정)

  • 김의중;송승훈;김민기;김태형
    • Journal of the Korean Society for Precision Engineering
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    • v.17 no.4
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    • pp.129-134
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    • 2000
  • This paper presents the development of ultra-precision machining process of large aspheric aluminum mirrors with a maximum diameter of 620 mm. An ultra-precision machine, "Nanoturn60", developed by Daewoo Heavy Industries Ltd. is used for machining and motion errors of the machine are compensated by using the FTS developed by IAE(Institue for Advanced Engineering) during the machining process. To check the form accuracy of machined aspheric surfaces, on-machine form measurement system is developed. This measurement system consists of air bearing touch probe, straight edge, and laser sensor. With in-process error compensation by FTS(Fast Tool Servo), aspheric mirrors with the from accuracy of submicron order are obtained. obtained.

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Investigation of Sensor Models for Precise Geolocation of GOES-9 Images

  • Hur Dongseok;Lee Tae-Yoon;Kim Taejung
    • Proceedings of the KSRS Conference
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    • 2005.10a
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    • pp.91-94
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    • 2005
  • A numerical formula that presents relationship between a point of a satellite image and its ground position is called a sensor model. For precise geolocation of satellite images, we need an error-free sensor model. However, the sensor model based on GOES ephemeris data has some error, in particular after Image Motion Compensation (IMC) mechanism has been turned off. To solve this problem, we investigate three sensor models: Collinearity model, Direct Linear Transform (DLT) model and Orbit-based model. We apply matching between GOES images and global coastline database and use successful results as control points. With control points we improve the initial image geolocation accuracy using the three models. We compare results from three sensor models that are applied to GOES-9 images. As a result, a suitable sensor model for precise geolocation of GOES-9 images is proposed.

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A Study on PC-NC Based Aspherical Lens Polishing System with Minimum Translation Mechanism (최소 이송 기구를 갖는 PC-NC 기반의 비구면 렌즈 연마 장치에 관한 연구)

  • Yang, Min-Yang;Lee, Ho-Cheol
    • Journal of the Korean Society for Precision Engineering
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    • v.18 no.7
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    • pp.65-71
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    • 2001
  • The development process of the polishing system for the aspherical lens mold for opto-electronics industry is described. The system uses the method that polishing tool is scanned on the surface under PC-NC control for the aspherical lens mold. The two axes interpolation of the minimum translation mechanism is applied to give uniform working condition by motion analysis. An aspherical surface is divided into multiple sections and each dwell time is calculated from the polishing rate model based on the Preston equation. As result of form error compensation experiment, initial form error is decreased about 25% while an average value of surface roughness is also reduced successfully from 180nm to 19nm.

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Development of Servo-system for Straightness Improvement of Linear Motor Stage (리니어모터 스테이지 진직도 향상을 위한 서보 시스템 개발)

  • 강민식;최정덕
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 2004.10a
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    • pp.530-536
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    • 2004
  • In this paper a servo-system is developed to improve straightness of linear motor stages. When a linear motor stage is used for high-precision linear motion systems, high precision straightness accuracy is necessary to meet the required position accuracy. In such cases, machining and assembling cost increases to improve the straightness accuracy. An electro-magnetic actuator which is relatively cost effective than any other conventional servo-systems is suggested to compensate the fixed straightness error. To overcome the compensation error due to the friction, a sliding mode control is applied. The effectiveness of the suggested mechanism and the control performance are illustrated along with some experimental results.

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Study on Gravitational Torque Estimation and Compensation in Electrically Driven Satellite Antenna System (전기식으로 구동하는 위성안테나 시스템의 중력토크 추정 및 보상에 관한 연구)

  • Kim, Gwang Tae
    • Journal of the Korean Society for Precision Engineering
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    • v.33 no.10
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    • pp.789-796
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    • 2016
  • The weight of an antenna system pointing satellite on the mobile platform is restricted by the weight limit of the mobile platform. The maximum power of the actuator driving the antenna system is thus limited because a high power actuator needs a heavier weight. Thus, a drive system is designed to have a low torque requirement by reducing the gravitational torque depending on gravity or acceleration of the mobile platform, including vibration, shock, and accelerated motion. To reduce the gravitational torque, the mathematical model of the gravitational torque is preferentially obtained. However, the method to directly estimate the mathematical model in an antenna system has not previously been reported. In this paper, a method is proposed to estimate the gravitational torque as a mathematical model in the antenna system. Additionally, a method is also proposed to calculate the optimal weight of the balancing weight to compensate for the gravitational torque.

Development of Laser Diode Tester and Position Compensation using Feedback with Machine Vision (Laser Diode Tester 개발과 비젼 피드백을 이용한 위치 보정)

  • 김재희;유철우;박상민;유범상
    • Transactions of the Korean Society of Machine Tool Engineers
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    • v.13 no.4
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    • pp.30-36
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    • 2004
  • The development of LD(Laser Diode) tester and its control system based on the graphical programming language(LabVIEW) is addressed. The ill tester is used to check the optic power and the optic spectrum of the LD Chip. The emitter size of LD chip and the diameter of the Detector(optic fiber and photo diode) are very small, therefore the test device needs high accuracy. But each motion part of the test device could not accomplish high accuracy due to the limit of the mechanical performance. So, an image processing with machine vision is proposed to compensate for the error. By adopting our method we can reduce the error of position within $\pm$5$\mu\textrm{m}$.

Implementation of a Variable-sized Block Motion Compensation Module for 249-Mpixels/sec Hardware HEVC Decoders (249 Mpixels/sec 하드웨어 HEVC 디코더의 가변 크기 블록 움직임 보상 모듈 구현)

  • Cho, Seunghyun;Byun, Kyungjin;Eum, Nak-Woong
    • Proceedings of the Korean Society of Broadcast Engineers Conference
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    • 2014.11a
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    • pp.4-6
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    • 2014
  • 본 논문에서는 하드웨어 HEVC 디코더의 움직임 보상 모듈의 구조를 제안한다. 제안된 구조를 갖는 움직임 보상 모듈은 하드웨어 처리 싸이클 수와 내부메모리 크기를 감소시키기 위해 하나의 코딩 유닛을 그보다 작은 여러 개의 블록으로 분할하여 처리할 수 있다. 제안된 움직임 보상 구조는 캐시를 통해 외부 메모리에 접근하여 참조 픽쳐를 로딩하는 단계와 보간 필터를 거쳐 예측 샘플을 생성하는 단계로 내부-파이프라인을 구성하며 코딩 유닛의 크기에 따라 내부-파이프라인에서 처리할 블록의 크기를 결정한다. 본 논문에서는 코딩 유닛 분할의 기준이 되는 블록 크기를 결정하기 위한 절충사항에 대해서도 논의한다. 제안된 구조의 효율성을 판단하기 위해 구현된 움직임 보상 모듈을 RTL 시뮬레이션 및 FPGA 보드 검증을 통해 테스트 하였으며, SoC 로 제작될 경우 초당 249 Mpixel 을 처리하여 4K-UHD 시퀀스의 실시간 디코딩이 가능한 것으로 판단되었다.

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