基于图像的着陆点评估及探测器运动估计方法

针对深空探测任务特点给出了一种基于导航图像的探测器着陆点选择与探测器运 动估计技术。考虑到在着陆初始阶段(探测器高度＞2 km)导航相机所拍摄到的天体表面 近似为平面。这里通过跟踪至少4个平面内的特征点在导航图像序列 中的位置， 利用最小二乘法计算单应矩阵，由该矩阵得到探测器部分相对运动参数。结合激光测距仪给 出的探测器与天体表面之间的距离信息，可以得到全部6自由度参数。安全着陆点的选择与 评估首先利用图像灰度预选出平整的着陆点，再由着陆点对应的单应矩阵和之前获得的帧间 相对运动验证着陆点坡度。蒙特卡洛仿真结果表明，着陆点评估算法能够有效地选取满足平 整和坡度要求的着陆点，运动估计算法实时地对探测器参数进行估计，平移估计相对误 差小于10％，旋转估计误差小于0.23°。

Landing Site Assessment and Probe Motion Estimation Based on Image

This paper proposes a probe motion estimation and landing sites assessment algorithm. Due to the planar surface of landing site, the motion estimation algorithm based on essential matrix is instability. Motion Estimation algorithm from Homography is employed to fix this problem. Homography matrix is calculated by least squares method whit tracking at least 4 feature points through images. To calculate the motion of probe, the distance between probe and surface is also obtained by laser altimeter. The Landing Site is detected by the mean square error of the image intensity. Adding the motion of probe the algorithm determines the gradient of the site. The results of monte carlo simulation show that the proposed algorithm can select the landing site accurately, moreover it can provide the motion estimation of probe with translation estimation relative error under 10% and rotation estimation error under 0.23°.