Wang Donghong, Chen Xingfeng, Liu Jun, Liu Zongqi, Zheng Fengjie, Zhao Limin, Li Jiaguo, Mi Xiaofei
Beijing Institute of Tracking and Telecommunications Technology, Beijing 100094, China.
Aerospace Information Research Institute, Chinese Academy of Sciences, Beijing 100094, China.
Sensors (Basel). 2022 Sep 28;22(19):7366. doi: 10.3390/s22197366.
Chang'E-3 is China's first soft landing mission on an extraterrestrial celestial body. The laser Three-Dimensional Imaging (TDI) sensor is one of the key payloads of the Chang'E-3 lander. Its main task is to provide accurate 3D lunar surface information of the target landing area in real time for the selection of safe landing sites. Here, a simplified positioning model was constructed, to meet the accuracy and processing timeline requirements of the TDI sensor of Chang'E-3. By analyzing the influence of TDI intrinsic parameters, a permanent outdoor calibration field based on flat plates was specially designed and constructed, and a robust solution of the geometric calibration adjustment was realized by introducing virtual observation equations for unknowns. The geometric calibration and its absolute and relative positioning accuracy verification were carried out using multi-measurement and multi-angle imaging data. The results show that the error of TDI intrinsic parameters will produce a false obstacle with a maximum height of about 1.4 m on the plane, which will cause the obstacle avoidance system of Chang'E-3 to fail to find a suitable landing area or find a false flat area. Furthermore, the intrinsic parameters of the TDI have good stability and the accuracy of the reconstructed three-dimensional surface can reach about 4 cm after error calibration, which provides a reliable terrain guarantee for the autonomous obstacle avoidance of the Chang'E-3 lander.
嫦娥三号是中国首次在外天体软着陆的任务。激光三维成像（TDI）传感器是嫦娥三号着陆器的关键载荷之一。其主要任务是实时提供目标着陆区域精确的月球表面三维信息，以供选择安全着陆点。在此，构建了一个简化定位模型，以满足嫦娥三号TDI传感器的精度和处理时间要求。通过分析TDI内部参数的影响，专门设计并构建了基于平板的永久性室外校准场，并通过引入未知量的虚拟观测方程实现了几何校准调整的稳健解。利用多测量和多角度成像数据进行了几何校准及其绝对和相对定位精度验证。结果表明，TDI内部参数的误差会在平面上产生最大高度约为1.4米的虚假障碍物，这将导致嫦娥三号的避障系统无法找到合适的着陆区域或找到虚假的平坦区域。此外，TDI的内部参数具有良好的稳定性，误差校准后重建三维表面的精度可达约4厘米，这为嫦娥三号着陆器的自主避障提供了可靠的地形保障。
