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激光雷达是飞行器软着陆的重要辅助手段,在飞行器降落过程中它可以实时、精确、快速地确定星体表面局部区域的特征地形。但是,在扫描成像过程中它的载荷平台会有微小的震动,这种非平衡状态会导致由激光雷达获取的点云图像发生一定的畸变。结合激光雷达成像原理和误差传播理论分析了平台稳定性对三维激光雷达成像的影响,研究了在不同扫描周期内三维激光雷达图像变形。实验结果表明,除了受到仪器本身测量精度的影响之外,激光雷达获取图像质量还与扫描时间、成像区域密切相关。利用高分辨率的星载测时与测姿装置可以修正系统性的地形畸变,但是仪器误差也会引入到纠正后的图像之中。按照现有的平台姿态测量水平,控制激光雷达成像时间是它辅助导航着陆能否成功的关键。
Lidar is an important assistant for aircraft soft landing. It can determine the characteristic terrain in the local area of the star surface in real time, accurately and quickly during landing. However, there is slight vibration on the loading platform during scanning imaging, which leads to a certain distortion of the point cloud image acquired by the laser radar. Based on the principle of laser radar imaging and error propagation, the influence of platform stability on 3D lidar imaging is analyzed. The 3D image deformation of 3D laser radar is studied in different scanning cycles. Experimental results show that, in addition to the measurement accuracy of the instrument itself, the image quality obtained by laser radar is closely related to the scanning time and imaging area. The use of high-resolution spaceborne time-measurement and attitude-measuring devices corrects for systematic topographic distortions, but instrumental errors can also be introduced into the corrected image. According to the existing attitude measurement platform, controlling the time of laser radar imaging is the key to its successful navigation aids landing.