• Title/Summary/Keyword: Pointing Performance

Search Result 165, Processing Time 0.025 seconds

A Study on Vibration Reduction Timing Selection in the Mobile Pointing System (기동장비용 지향구조물의 진동 감소 상태선정 연구)

  • Yoo, Jin-Ho;Lee, Dong-Ju
    • Transactions of the Korean Society of Machine Tool Engineers
    • /
    • v.16 no.2
    • /
    • pp.112-119
    • /
    • 2007
  • In order to predict vibration trends occurred during vehicle drive, acceleration data was processed by using data processing algorithm with moving average and Hilbert transform. Specific mode constants of acceleration were obtained under various disturbance. Vehicle velocity, road condition, property of pointing structure were considered as factors which make change of vibration trend in vehicle dynamics. Results of signal processing were compared and analysed. Advanced performance of the timing selection algorithm from this study was verified by using simple equipment comparing with the deflection measurement laser system(Muzzle Reference System).

Test of a UAV Tracking Antenna System Using GPS (GPS를 이용한 무인항공기 추적안테나 시스템 시험)

  • Roh, Min-Shik;Lee, Dae-Woo;Cho, Kyeum-Rae
    • Journal of the Korean Society for Aeronautical & Space Sciences
    • /
    • v.35 no.2
    • /
    • pp.171-176
    • /
    • 2007
  • The tracking antenna must always point to track moving vehicle for data link. In this paper, we determine pointing angle from the geometric relationship of antenna and UAV(Unmaned Aerial Vehicle) to let an antenna be toward a moving vehicle. The pointing angle of antenna is set through GPS measurement data installed in antenna and UAV. We verify the performance of this system from the fixing a camcoder on the antenna.

PRELIMINARY COMS AOCS DESIGN FOR OPTIMAL OPTICAL PAYLOADS OPERATIONS

  • Park, Young-Woong;Park, Keun-Joo;Lee, Hun-Hei;Ju, Gwang-Hyuk;Park, Bong-Kyu
    • Proceedings of the KSRS Conference
    • /
    • v.1
    • /
    • pp.290-293
    • /
    • 2006
  • COMS (Communication, Ocean and Meteorological Satellite) shall be operated with two remote sensing payloads, MI (Meteorological Imager) and GOCI (Geostationary Ocean Color Imager). Since both payloads have rotating mechanisms, the dynamic coupling between two payloads is very important considering the pointing stability during GOCI operation. In addition, COMS adopts a single solar wing to improve the image quality, which leads to the unbalanced solar pressure torque in COMS. As a result, the off-loading of the wheel momentum needs to be performed regularly (2 times per day). Since the frequent off-loading could affect MI/GOCI imaging performance, another suboptimal off-loading time needs to be considered to meet the AOCS design requirements of COMS while having margin enough in the number of thruster actuations. In this paper, preliminary analysis results on the pointing stability and the wheel off-loading time selection with respect to MI/GOCI operations are presented.

  • PDF

Ground Experiment of Spacecraft Attitude Control Using Hardware Testbed

  • Oh, Choong-Suk;Bang, Hyo-Choong
    • International Journal of Aeronautical and Space Sciences
    • /
    • v.4 no.1
    • /
    • pp.75-87
    • /
    • 2003
  • The primary objective of this study is to demonstrate ground-based experiment for the attitude control of spacecraft. A two-axis rotational simulator with a flexible ann is constructed with on-off air thrusters as actuators. The simulator is also equipped with payload pointing capability by simultaneous thruster and DC servo motor actuation. The azimuth angle is controlled by on-off thruster command while the payload elevation angle is controlled by a servo-motor. A thruster modulation technique PWM(Pulse Width Modulation) employing a time-optimal switching function plus integral error control is proposed. An optical camera is used for the purpose of pointing as well as on-board rate sensor calibration. Attitude control performance based upon the new closed-loop control law is demonstrated by ground experiment. The modified switching function turns out to be effective with improved pointing performance under external disturbance. The rate sensor calibration technique by Kalman Filter algorithm led to reduction of attitude error caused by the bias in the rate sensor output.

다목적실용위성 1호 Maneuver Mode에서의 지상관제 DATA 분석

  • Suk, Byong-Suk
    • Aerospace Engineering and Technology
    • /
    • v.1 no.1
    • /
    • pp.65-71
    • /
    • 2002
  • KOMPSAT-1 AOCS mode divided into three major mode like Sun, Maneuver, Science Mode. The Maneuver mode consist of attitude hold and Δ-V Burn submode. This paper focus on the analysis of AOCS Maneuver Mode characteristics based on on-orbit playback data. The nadir pointing performance of attitude hold submode and the process for Δ-V Burn firing with plus/ minus 90 degree pitch/ roll maneuvering was verified. And also verified that the on-orbit performance meets the AOCS subsystem specification as designed.

  • PDF

Variation of Psychophysiological Characteristics Related with Human Errors during a Simple Pointing Task (단순 지적과업 중 인간과오 관련 심리생리학적 특성의 변화)

  • Lim, Hyeon-Kyo
    • Journal of the Korean Society of Safety
    • /
    • v.24 no.3
    • /
    • pp.71-78
    • /
    • 2009
  • During a learning process, a human being is assumed to experience knowledge-based behaviors, rule-based behaviors, and skill-based behaviors sequentially if Rasmussen was right. If any psycho-physiological symptom to those different levels can be obtained, it can be useful as a measure whether a human being is fully trained and has gotten a skill in his work. Therefore, this study aimed to draw relationships between human performance measures and psycho-physiological measures while committing a computer-simulated pointing task by utilizing the power spectrum technique of EEG data, especially with the ratio of relative beta-to-alpha band power. The result showed that, during correct responses, the ratio came to stabilize as all the performance data went stable. However, response time was not a simple linear function of task difficulty level only, but a joint function of task characteristics as well as behavior levels. Comparing relative band power ratios from errors and correct responses, activated states of one's brain could be explained, and characteristics of the task could understood. To tell that of pointing task, correlations around C3, C4, P3, P4 and 01, 02 area were significant and high in correct response cases whereas most correlation coefficients went down in error cases standing for imbalance of psycho-motor functions. Though task difficulty was the only one factor that could influence on relative band power ratio with statistical significance, it should be comprehended to mean a different way of expression indicating task characteristics since at least error-some situation could be explained with the help of relative band power ratio that absolute band power failed.

A Study on the Validation of Tracking Performance of a Big Parabola Antenna System (대형 접시형 안테나 추적성능 검증에 관한 연구)

  • Oh, Chang-Yul;Oh, Seung-Hyeub
    • The Journal of the Institute of Internet, Broadcasting and Communication
    • /
    • v.10 no.5
    • /
    • pp.77-82
    • /
    • 2010
  • The tracking performance of the big tracking antenna system using Radio Frequency is very important for the tracking and position measuring for the flight vehicle, but the precise measuring of the tracking performance is not easy, especially for the big antenna system such as ground telemetry antenna or tracking radar in space application because it's characteristics could be different in accordance with the antenna direction. In this paper, the error factors impacting on the tracking performance (pointing accuracy and tracking accuracy) and the ranges of each factor are reviewed, and the simple and efficient method to measure the tracking performance is introduced which using low earth orbit as the signal source. Finally, the measurement results for the telemetry ground antenna in NARO Space Center are reviewed.

Performance Evaluation of Hybrid Vibration Isolator using FxLMS algorithm (FxLMS 알고리즘을 적용한 하이브리드 미소진동 절연장치의 절연성능 평가)

  • Lee, Dae-Oen;Park, Geeyong;Han, Jae-Hung
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
    • /
    • 2014.10a
    • /
    • pp.173-174
    • /
    • 2014
  • Vibration disturbances generated by reaction wheels may cause serious problems in high precision pointing spacecraft missions. Implementation of vibration isolator is a practical solution to meet the high pointing stability requirement placed on precision payloads. In this paper, development of hybrid vibration isolator that combines passive and active component is described. Vibration isolation performance of the developed isolator is evaluated using reaction wheel disturbance model. Hybrid isolation results obtained using FxLMS algorithm show clear improvement compared to the results obtained using only passive means.

  • PDF

다목적실용위성 1호 태양지향모드에서의 연료 절감을 위한 퍼지제어기 설계

  • Choi, Hong-Taek;Han, Jung-Youp
    • Aerospace Engineering and Technology
    • /
    • v.1 no.1
    • /
    • pp.97-105
    • /
    • 2002
  • The mission life of a satellite determines the amount of fuel required on-board, while the total mass requirement limits the fuel to be loaded. Hence, for the design of thruster control loop, not only the satellite pointing accuracy but the saving of fuel is to be considered. In this paper, a two-step fuzzy controller is proposed for the thruster control loop to save fuel consumption. This approach combines requirements for pointing control accuracy with minimum fuel consumption into a fuzzy controller design. To demonstrate this approach, we have designed a fuzzy controller for the Sun Pointing Mode of KOMPSAT-1. The performance of this fuzzy controller design is compared with that of PD controller used for KOMPSAT-1.

  • PDF

REQUIREMENTS AND FEASIBILITY STUDY OF FPC-G FINE GUIDING IN SPACE INFRARED TELESCOPE, SPICA (대형 적외선 우주망원경 SPICA/FPC-G의 정밀 별추적 요구사항과 타당성 연구)

  • Jeong, Woong-Seob;Lee, Dae-Hee;Pyo, Jeonghyun;Moon, Bongkon;Park, Sung-Joon;Ree, Chang Hee;Park, Youngsik;Han, Wonyong;Nam, Ukwon;Matsumoto, Toshio
    • Publications of The Korean Astronomical Society
    • /
    • v.27 no.5
    • /
    • pp.391-397
    • /
    • 2012
  • The SPICA (SPace Infrared Telescope for Cosmology & Astrophysics) project is a next-generation infrared space telescope optimized for mid- and far-infrared observation with a cryogenically cooled 3m-class telescope. It will achieve the high resolution as well as the unprecedented sensitivity from mid to far-infrared range. The FPC (Focal Plane Camera) proposed by KASI as an international collaboration is a near-infrared instrument. The FPC-S and FPC-G are responsible for the scientific observation in the near-infrared and the fine guiding, respectively. The FPC-G will significantly reduce pointing error down to below 0.075 arcsec through the observation of guiding stars in the focal plane. We analyzed the pointing requirement from the focal plane instruments as well as the error factors affecting the pointing stability. We also obtained the expected performance in operation modes. We concluded that the FPC-G can achieve the pointing stability below 0.075 arcsec which is the requirement from the focal plane instruments.