基于星敏感器的卫星对地定姿误差分析

风云三号气象卫星上携带的一台星敏感器解算出的卫星对地姿态呈现出非正常的幅值约为0.15°的正弦周期性偏差。为解决上述问题,分析了影响卫星对地姿态的误差因素,对星敏感器本身的主点偏差、焦距误差、光轴不垂直、CCD面旋转、星表位置误差等对卫星对地姿态误差的影响规律进行了仿真和分析。结果表明:对于CCD为512×512、象元大小为17μm、视场为16°×16°、安装方位角、高角分别为107°、29°的星敏感器而言,主点偏差5像素,会对卫星对地姿态带来最大约为0.17°的固定系统偏差;焦距误差0.1mm、光轴不垂直0.1°、CCD面旋转0.1°等对卫星对地姿态的影响较小,误差不超过30";星表中恒星位置在不加岁差、章动修正的情况下,会造成卫星对地三轴姿态误差呈正弦周期性变化,且周期与卫星轨道周期一致。风云三号气象卫星的对地姿态周期性偏差现象是由于星敏感器的星表恒星位置未进行岁差、章动等修正引起的。

Error Analysis of Attitude Determination by Star Sensors on Satellites

FY-3 Meteorological Satellite has been launched in Nov.2011,data on-orbit showed that satellite attitude error based on a star sensors is sinusoidal curve with 0.15° amplitude.So,error factors that affect satellite attitude accuracy were analyzed,and a computer simulation method was brought forward.Some error factors influencing the satellite attitude accuracy,such as principle point offset,focal length uncertainty,tilt and roll of the focal plane and position error of stars,were presented and simulated in detail.Simulation shows that,for a star sensor with 512×512 CCD,17μm pixel size,16°×16° FOV,azimuth angle 107° and elevation angle 29°,satellite attitude error is about 0.17° fixed system bias error with 5 pixel principle point offset,and that satellite attitude error is less than 30″ with focal length uncertainty 0.1mm,tilt or roll of the focal plane 0.1°.Without regard to the correction of stellar precession and nutation,the satellite attitude can induce the sinusoidal periodicity error,and the cycle is consistent with the orbit period.Sinusoidal bias phenomenon of FY-3 Satellite attitude is arisen from star coordinates error of the star catalog without precession and nutation correction.