基于视觉导航的自主小行星弱引力场测量方法

Autonomous Asteroid Weak Gravity Field Measurement Method Based on Visual Navigation

针对国际上小行星探测任务中百米量级内不规则小行星的弱引力场确定问题,提出了一种无绕飞轨道的基于视觉导航的引力场测量方法.在完成三维重构后,利用探测器上的光学导航相机每隔一段时间对小行星表面拍照,匹配和识别至少3个非共线的特征点,并测量对应特征点在相机测量系下的视线方向.在完成飞行过程后,通过加权最小二乘批处理算法处理探测器飞行轨迹下的测量数据来估计小行星引力常数和球谐系数,还分析了探测器飞行轨迹的规划问题,分析表明飞行轨迹应根据小行星的形状和质量分布进行规划.最后,对提出的方法进行了仿真验证,结果表明根据该方法通过探测器较少的飞行轨迹即可精确测量出小行星全局引力信息,具有一定的工程实用性.

In order to determine the weak gravity field of irregular asteroids with 100 meters in international asteroid exploration mission,a gravity field measurement method based on visual navigation is proposed in this paper.Firstly,after completing three-dimensional reconstruction,the optical navigation camera on the probe is used to measure three non-collinear feature points of the known positions at intervals to obtain image information.Then the asteroid gravity constant and spherical harmonic coefficients are estimated by weighted least squares batch processing algorithm,which processes the measured data under the probe flight trajectories.Meanwhile,the flight trajectory planning of the probe is also analyzed,which shows that the flight path should be planned with the shape and mass distribution of the asteroid.Finally,the simulation results show that the proposed method can effectively measure the global gravity information of the asteroid in fewer flight paths.