• Title/Summary/Keyword: Pointing Accuracy

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Gyrocompass Correction and Pointing Accuracy Improvement of the Ship-Borne Mobile Down Range Antenna for Launcher Telemetry (우주발사체 텔레메트리용 해상 이동형 다운레인지 안테나의 자이로컴퍼스 보정과 포인팅 정확도 향상)

  • Lee, Sun-Ik;Yeom, Kyung-Whan
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.25 no.5
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    • pp.532-541
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    • 2014
  • The ship-borne mobile down range telemetry antenna system having 4.6 m reflector antenna and 3-axis mounting structure at S-band requires the precise pointing accuracy at sea for the launch mission. Using the LEO satellites tracking, a method to determine and verify the antenna pointing and tracking performance, and to find the pointing bias which dominantly contributes to the pointing inaccuracy, is presented. Based upon the tests conducted on the Jeju sea and Pacific sea, the pointing bias is determined and its origin is also identified as the drift of the heading angle of the gyrocompass. The applied systematic correction taking into account the pointing bias, and the achieved improvement of the pointing accuracy are shown. Thanks to the correction, it is presented that this antenna tracked the launcher(KSLV-I) stably within the required pointing accuracy in the following KSLV-I third launch.

Assessment of the Usability of Digital TV Remote Control Pointing Methods (Digital TV 리모컨의 포인팅 방식에 대한 사용성 평가)

  • Cheong, Kyeong-Kyun;Kim, In-Soo;Park, Sung-Kwon;Park, Yong-Jin
    • Journal of Broadcast Engineering
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    • v.16 no.4
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    • pp.657-668
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    • 2011
  • Along with the development of communication technology, DTV is gradually evolving into media that provide diverse services and information. This study is related with remote controls that control DTV interfaces and assessed the usability of remote pointing device. To this end, pointing devices using three different interaction methods that have been attempted recently by the industry were selected to conduct empirical experiments. The usability assessment was conducted centering on the existing directional task on straight tracks presented in ISO 9241-Part 9 and the steering tunnel task on curved tracks proposed in this study. The measurement variables included movement time, accuracy, throughput, subjective satisfaction and user behaviors. Based on the results of the assessment, in the case of movements on straight tracks, the GyroPoint method showed better implementing time but lower accuracy compared to the Hall Mouse and OFN methods while in the case of assessment on curved tracks, all of the GyroPoint method, Hall Mouse and OFN methods showed excellent results on both implementing time and accuracy. Besides, differences in efficiency and subjective satisfaction were shown among individual pointing devices. Based on these results, it is considered that individual pointing methods have different advantageous and disadvantageous characteristics. In this study, the usability of remote control pointing methods was assessed and diagnosed reflecting environments where DTVs are used through assessments considering the aspect of straight tracks along with curved tracks. Among others, this study is considered to be meaningful in that it provides assessment criteria and basic data for the development of remote controls suitable for the evolving DTV environments.

Two-Stage Sliding Mode Controller for Bending Mode Suppression of a Flexible Pointing System (유연성 포인팅 시스템의 진동모드 보상을 위한 2단계 슬라이딩 모드 제어기)

  • 박장현;김경완;이교일;김학성
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 1996.11a
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    • pp.971-976
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    • 1996
  • A flexible pointing system mounted on top of a vehicle suffers from performance degradation due to bending vibrations as the vehicle runs on a bump course. In order to improve the pointing performance, the pointing structure's vibrations should be suppressed. In this paper, a nonlinear controller is designed to control the tip position of the pointing system while actively suppressing the vibrations. To cope with high order dynamics and nonlinearities of the plant and hydraulic actuating system, a two-stage sliding mode controller is devised. The desired actuating pressure is obtained in the first stage and then the in put current In the hydraulic servo system is computed to generate the pressure. The simulation results show the effectiveness of this scheme and improvements in pointing accuracy.

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Analysis of SAR Image Quality Degradation due to Pointing and Stability Error of Synthetic Aperture Radar Satellite (위성체 지향 및 안정화 오차로 인한 영상레이더 위성 영상 품질 저하 해석)

  • Chun, Yong-Sik;Ra, Sung-Woong
    • Journal of Astronomy and Space Sciences
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    • v.25 no.4
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    • pp.445-458
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    • 2008
  • Image chain analysis of synthetic aperture radar (SAR) satellite is one of the primary activities for satellite design because SAR image quality depends on spacecraft bus performance as well as SAR payload. Especially, satellite pointing and stability error make worst effect on the original SAR image quality which is implemented by SAR payload design. In this research, Image chain analysis S/W was developed in order to analyze the SAR image quality degradation due to satellite pointing and stability error. This S/W consists of orbit model, attitude control model, SAR payload model, clutter model, and SAR processor. SAR raw data, which includes total 25 point targets in the scene of $5km{\times}5km$ swath width, was generated and then processed for analysis. High resolution mode (spotlight), of which resolution is 1m, was applied. The results of image chain analysis show that radiometric accuracy is the most degraded due to the pointing error. Therefore, the successful design of attitude control subsystem in spacecraft bus for enhancing the pointing accuracy is most important for image quality.

Design and Implementation of a Real-time Region Pointing System using Arm-Pointing Gesture Interface in a 3D Environment

  • Han, Yun-Sang;Seo, Yung-Ho;Doo, Kyoung-Soo;Choi, Jong-Soo
    • Proceedings of the Korean Society of Broadcast Engineers Conference
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    • 2009.01a
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    • pp.290-293
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    • 2009
  • In this paper, we propose a method to estimate pointing region in real-world from images of cameras. In general, arm-pointing gesture encodes a direction which extends from user's fingertip to target point. In the proposed work, we assume that the pointing ray can be approximated to a straight line which passes through user's face and fingertip. Therefore, the proposed method extracts two end points for the estimation of pointing direction; one from the user's face and another from the user's fingertip region. Then, the pointing direction and its target region are estimated based on the 2D-3D projective mapping between camera images and real-world scene. In order to demonstrate an application of the proposed method, we constructed an ICGS (interactive cinema guiding system) which employs two CCD cameras and a monitor. The accuracy and robustness of the proposed method are also verified on the experimental results of several real video sequences.

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A Study on Improvement of Aiming Ability using Disturbance Measurement in the Ground Military Vehicle (지상무기체계에서의 외란측정을 이용한 정밀 지향성 향상 연구)

  • Yoo, Jin-Ho;Park, Byung-Hun
    • Journal of the Korea Institute of Military Science and Technology
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    • v.10 no.2
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    • pp.12-20
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    • 2007
  • The aiming ability is a key to improve the accuracy performance of the gun pointing system in the ground military vehicle. This paper describes the new detection method of chatter vibration using disturbance acceleration in the pointing structure. In order to analysis the vibration trends of the pointing system occurred while the vehicle driving, acceleration data obtained from vehicle was processed by using data processing algorithm with moving average and Hilbert transform. The specific mode constants of acceleration were obtained from various disturbances. Vehicle velocity, road condition and property of pointing structure were considered as factors which make the change of vibration trend in vehicle dynamics. Finally, back propagation neural networks have been applied to the pattern recognition of the classification of vibration signal in various driving conditions. Results of signal processing were compared with other condition result and analysed.

Control of a Heavy Load Pointing System Using Neural Networks (신경회로망을 이용한 대부하 표적지향 시스템 제어)

  • 김병운;강이석
    • Journal of the Korean Society for Precision Engineering
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    • v.21 no.5
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    • pp.55-63
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    • 2004
  • This paper presents neural network based controller using the feedback error loaming technique for a heavy load pointing system. Also the mathematical model was developed to analyze heavy load pointing system. The control scheme consists of a feedforward neural network controller and a fixed-gain feedback controller. This neural network controller is trained so as to make the output of the feedback controller zero. The proposed controller is compared with the conventional PI controller through simulations, and the results show that the pointing accuracy of the proposed control system are improved against the disturbance induced by vehicle running on the bump course.

DEVELOPMENT OF CONTROL SOFTWARES FOR IMPROVEMENT OF TRACKING EFFICIENCY OF THE 16'' TELESCOPE OF SEOUL NATIONAL UNIVERSITY OBSERVATORY (서울대학교 천문대 16인치 망원경의 추적 성능 향상을 위한 제어 소프트웨어의 개발)

  • JEONG WOONGSEOB;LEE SANG-GAK;PARK SOOJONG
    • Publications of The Korean Astronomical Society
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    • v.14 no.1
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    • pp.47-56
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    • 1999
  • We have improved the control and driving system of 16' reflector at Kwanak Observatory at Seoul National University, by completing encoder unit, and by developing programs for correction of errors resulting from hardware defects. The hardware defects of this telescope system are the large backlash and the nonuniform tracking and pointing. The telescope pointing accuracy for RA is improved to a few arc minutes, and that for DEC is several tens of arc minutes. The guiding error is improved to 0.7 arcsec/minute, allowing up to 3 minutes exposure for CCD imaging under typical seeing conditions at the Observatory.

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User Performance Measures for iTV Remote Control of Pointing Devices (iTV 리모컨 포인팅 디바이스 수행도 측정)

  • Cheong, Kyeong-Kyun;Kim, In-Soo;Park, Sung-Kwon;Park, Yong-Jin
    • The Journal of the Institute of Internet, Broadcasting and Communication
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    • v.11 no.3
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    • pp.145-150
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    • 2011
  • In this study, we assessed the performance of the test remote pointing device that is applicable to interactive TV (iTV). An empirical test was carried out with the pointing devices in three different interface methods that are recently tried in the industry. For the measurement, a directional task was performed on the linear track described in the conventional ISO 9241-Part 9. The measured variables included the movement time, accuracy, throughput and the subjective satisfaction. The result showed that the motion time was better in the device in the GyroPoint method than the other devices, but the accuracy of the GyroPoint device was lower than that of the devices in the Hall Mouse and OFN methods. It was found that the throughput and the subjective satisfaction were dependent upon the individual input devices. Since this study was conducted on the major point devices that are currently tried and analyzed the problems and characteristics, it is assumed that this study will provide useful data for the design of the remote pointing device that is more suitable to the iTV environment.

Pointing Accuracy Analysis of Space Object Laser Tracking System at Geochang Observatory (거창 우주물체 레이저 추적 시스템의 추적마운트 지향 정밀도 분석)

  • Sung, Ki-Pyoung;Lim, Hyung-Chul;Park, Jong-Uk;Choi, Man-Soo;Yu, Sung-Yeol;Park, Eun-Seo;Ryou, Jae-Cheol
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.49 no.11
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    • pp.953-960
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    • 2021
  • Korea Astronomy and Space Science Institute has been verifying the multipurpose laser tracking system with three functions of satellite laser tracking, adaptive optics and space debris laser tracking for not only scientific research but also national space missions. The system employs an optical telescope consisting of a 100 cm primary mirror and an altazimuth mount for fast and precise tracking. The precise pointing and tracking capability in a tracking mount is considered as one of important performance metrics in the fields of automatic tracking and precise application research. So it is required to analyze a mount model for investigating pointing error factors and compensating pointing error. In this study, we investigated various factors causing static pointing errors of tracking mount and analyzed the pointing accuracy of the tracking mount at Geochang observatory by estimating mount parameters based on the least square method.