アナログ式太陽センサの精度向上および太陽ベクトル決定のためのデータ処理法
| Autor: | Faizullin, Dmytro |
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| Jazyk: | angličtina |
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| Popis: | 1 Introduction||2 Sun sensor design and methods for improving sun vector determination||3 Pre-processing of in-orbit sensors data HOYU-IV AODS||4 Attitude estimation and propagation for sun vector determination||5 Conclusion HORYU-IV is a nanosatellite of Kyushu Institute of Technology (Kyutech), which was successfully launched on February 17, 2016. The satellite is a passively stabilized with the help of permanent magnets and a hysteresis dumper. HORYU-IV is equipped with pinhole sun sensors, GPS and gyro sensors. The sun sensor was originally designed by Kyutech. This sensor has a round-shaped hole and uses commercial off-the-shelf silicon photodiode, which consists of four small sensitive elements arranged close to each other. Incident light, focused through a pinhole, produces a spot on four diodes. Each diode’s output is a current proportional to the amount of light. Methods for calculation of a sun vector use analogue outputs from this type of sensors. This study introduces a polynomial equation to describe dependencies between sensor outputs. This treatment increases a field of view (FOV) with high accuracy (0.1 deg) twice as much as the linear one. Taking into account dead spaces between photodiodes is also considered. An ideal model of the sensor and 6 real sun sensors with different configurations (diameter of a pin hole and distance from a hole to photodiodes are varied) are made to verify the improvement by the proposed methods. The sensor is not able to detect a sun light continuously because of limited FOV. That is why a sun vector should be calculated with use of solar-cell output on the panel. As the measured currents obtained from the solar panel depend on the satellite’s power consumptions, the direct calculation of a sun vector gives poor accuracy. The satellite uses a MEMS gyro to detect attitude motions. Three parameters are used to adjust the sensor: gain, offset and temperature coefficient. Comparison between ground test and the in-orbit data showed that the sets of parameters have different values. This means that the gyro sensor needs on-board calibration. This dissertation proposes improvement of analog sun sensor accuracy as well as data processing for sun vector determination with the use of Extended Kalman Filter, outputs of the quadrant sun sensors, solar-panel currents and an uncalibrated gyro. 九州工業大学博士学位論文 学位記番号:工博甲第444号 学位授与年月日:平成29年9月22日 平成29年度 |
| Databáze: | OpenAIRE |
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