卫星偏流角的矢量计算方法研究

Study on a Vector Algorithm of Satellite Drift Angle

对一种近地圆轨道遥感卫星偏流角的矢量计算方法进行了研究。基于考虑地球自转时偏流角的定义和相关坐标系,将计算偏流角用的速度矢量分解为数个速度的矢量和,由坐标系转换关系,根据卫星地面物点定位信息确定其相对速度,推导出卫星本体坐标系中偏流角的计算公式。算法的基本运算无需求导,可有效避免求导过程中牵连速度计算,具有模型准确、计算简便、结果精确、物理意义清晰、排查错误容易等优点。在不同三轴姿态角、载荷视物前向角和侧向角条件下进行了数学仿真计算,结果发现计算结果与偏流角定义相符,卫星偏流角随星下点地理纬度和纬度幅角的变化分别为封闭类圆和1/2周期的类正弦曲线,而视物前向角、侧向角,滚动角,俯仰角对偏流角的影响较小。该计算方法已用于高分五号(GF-5)卫星的星上偏流角计算软件。

A vector algorithm of drift angle for remote-sensing satellite on close circular orbit was studied in this paper.The velocity vector used in computation of drift angle was divided into vector addition of several velocities based on the drift angle definition with the consideration of the earth spin and relative coordinate system.The relative velocity of object point on the ground was determined by the position information of the object point according to the coordinate transformation.The computation formal of the drift angle in the body-system of the satellite were derived.The derivation was not needed in the essential calculation of the algorithm and the derivation computation of the transport velocity was avoided,which had advantages that the mode was accurate,the computation was simple,the result was exact,the physical meaning was clear and the error finding was easy.The numerical simulation was made under the various attitude,forward angle and direction finding angle.It was showed that the computation result was coincidence with the definition of the drift angle.The drift angles were closed similar round curve and similar sinusoidal curve with 1/2cycle which were changing with the latitude of point under satellite and argument of latitude respectively.The influences of the forward angle,lateral angle,roll angle and pitch angle on the drift angle were small.The algorithm had been applied in the software in GF-5satellite.