Journal of Aerospace System Engineering (항공우주시스템공학회지)

The Society for Aerospace System Engineering (항공우주시스템공학회)
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Optimal positioning of reaction wheel assemblies of optical observation satellite for minimizing image quality degradation

광학관측위성의 영상품질열화 최소화를 위한 반작용휠 최적위치 선정

  • Received : 2018.07.30
  • Accepted : 2018.11.29
  • Published : 2018.12.31
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Abstract

This paper describes how to find out the optimum position of the reaction wheel assembly (RWA) to minimize image quality degradation through the integrated system jitter prediction combining the micro-vibration test with finite element analysis considering optical coefficients. Micro-vibration generated from RWA that is widely used for satellite maneuver, is one of key factors that degrades the quality of satellite image. Due to varying vibration characteristics of each RWA, its accommodation position may affect image quality even though the same company manufactured them. To resolve this issue, an integrated system jitter prediction is conducted with all possible RWA accommodation location, and finally we determine optimal RWA position from the analysis results.

본 논문에서는 반작용휠 미소진동시험 결과 및 유한요소모델 기반 광기계해석 통합모델을 이용해 영상품질저하 예측을 실시하고 해석결과를 바탕으로 기준 회전수에서 영상품질관점에서 최적의 반작용휠 배치조합을 찾는 것을 목적으로 한다. 위성은 적절한 기동성능을 위하여 여러 개의 반작용휠을 장착하는데 반작용휠에서 발생하는 미소진동은 위성영상품질 열화에 원인이 된다. 같은 반작용휠이라도 제조과정상 발생하는 제품의 진동특성차이가 있으며 이를 반영한 반작용휠의 배치설계는 최종 위성영상 성능품질 열화를 최소화시킬 수 있다. 이를 위해 본 연구에서는 모든 반작용휠의 배치상태를 선정하고 이에 따른 영상품질 열화해석을 실시하여 최소의 열화가 일어나는 반작용휠 배치조합을 찾아내었다.

Keywords

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Fig. 1 RWA Accommodation of CAS500-1

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Fig. 2 Flowchart for Jitter Calculation

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Fig. 3 Weighting Factor of Jitter & Drift

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Fig. 4 Test Set-up for Micro-vibrationMeasurement

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Fig. 5 Waterfall Plot of RWA Micro-vibration

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Fig. 6 Frequency Transfer Functions from RWAs to Focal Plane

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Fig. 7 Finite Element Model of CAS500-1 for Modal Test

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Fig. 8 Finite Element Model of CAS500-1 for Jitter Prediction

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Fig. 9 Optical Components of CAS500-1

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Fig. 10 LOS Jitter According to Various RWA Combination

Table 1 Specification of CAS500-1

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Table 2 Summary of Maximum Forces Under 500 Nominal RPM Operation

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Table 3 Summary of Maximum Forces Under -500 Nominal RPM Operation

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Table 4 Summary of Maximum Forces Under 1000 Nominal RPM Operation

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Table 5 Summary of Maximum Forces Under -1000 Nominal RPM Operation

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Table 6 Unitary Check of Optical Coefficients of Payload

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Table 7 Load Case Summary for Each RPM Speed

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Table 8 Jitter Analysis Results of CAS500-1

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