在轨航天器空间几何遮挡算法

Space Shading Algorithm for On-orbit Spacecraft

航天器空间几何遮挡算法是空间碎片风险评估的关键环节,遮挡算法的正确性对评估精度影响显著。针对空间碎片碰撞风险评估中航天器几何遮挡问题,基于计算机图形学Roberts算法和Z缓冲器算法,建立了一种算法简单、精度高、通用性强的几何遮挡处理方法及算法实现。针对航天器结构比较复杂的特点,提出了先对航天器实现舱段分解,在消除被遮挡面后,再进行合并的遮挡处理原则,并建立了航天器结构空间几何遮挡理论模型及算法流程。采用该算法对IADC规定的简单航天器标准工况进行了遮挡处理分析,得出了遮挡处理后不同方向下航天器的暴露面积。结果表明,不同方向下的航天器暴露面积是不同的,遮挡处理后IADC规定的简单航天器最小暴露面积仅为原来的38.91%,最大也只有原来的55.27%。可见,在不同运行姿态下,航天器暴露面积差别很大,改变航天器飞行路线及运行姿态可有效减少空间碎片的碰撞风险。

Space shading algorithm for spacecraft is the key link of Meteoroid and Orbital Debris（M/OD） risk assessment.The analysis precision of M/OD risk assessment is mostly dependent on the accuracy of space shading algorithm.The M/OD risk assessment plays a very important role in shielding design and in-orbit safety for spacecraft.For the spacecraft shading problem in orbital debris risk assessment, based on Roberts algorithm and Z-buffer algorithm, a shading algorithm is proposed, which is simple in computation, accurate in results and versatile in applications.Spacecraft structures are often very complex, therefore, in the algorithm, a decomposition of the structure and a related shading are made before a combination operation.The shading of simple spacecraft specified by IADC is analyzed.The exposed areas of spacecraft and each finite element in different yawing directions are obtained.The exposed area of the simple spacecraft is different in different directions.The minimum and maximum exposed areas after shadingare 38.91% and 55.27% of the exposed area of the simple spacecraft before shading, which shows that the exposed area of spacecraft has great different in different flight attitude.And changes in spacecraft mission operations, flight rules, and flight planning can reduce meteoroid and debris risks.