基于CCD着陆相机的行星软着陆岩石检测与规避方法

An Algorithm of Rock Detection and Avoidance for Planetary Soft Landing Based on CCD Landing Camera

提出了一种基于CCD相机的行星软着陆岩石检测与规避方法。首先,利用多分辨率分析方法对着陆区图像进行快速处理,根据着陆区的光照特性检测出着陆区的岩石,针对着陆过程的时间需求,多灰度阈值分割方法被采用;其次,基于无监督聚类算法对着陆区的岩石进行识别并标记,构建着陆区岩石分布的拓扑图;再次,利用激光测距仪得到的高度信息和着陆相机的参数,计算着陆区岩石拓扑图的实际危险区域面积,从而根据着陆器的需求安全范围和探测任务需要,利用安全着陆点的螺旋式搜索方法选择具有冗余度的安全着陆点;最后,建立着陆器安全规避策略,制导控制着陆器进行安全着陆,通过对安装侧向发动机和利用万向节调节推力方向的主发动机两种情况的仿真,实验结果令人满意。

An algorithm of rock detection and avoidance for soft planetary landing based on CCD landing camera is presented. Firstly,the image of the landing zone is fast processed using the multi-resolution analysis technique. The rocks of the landing zone are detected reliably on the basis of the lighting character of the zone. Segmentation by multi-gray level threshold is applied to meet the requirement of real-time during the landing course. Secondly,the rocks detected are recognized and labeled based on the unsupervised clustering algorithm. The topological diagram of rocks distributed in the landing zone is created. Thirdly,the true hazard area of the landing zone is computed by the height from the laser altimeter and the inner parameters of the landing camera. Then a novel spiral searching method is applied to select the safe landing site with some redundancy,which is required to satisfy the safe bound of the lander and the exploration task. Finally,hazard avoidance strategy of the lander is generated,which guides and controls the lander to maneuver to the new and safe site. Simulation experiments have shown satisfactory results,which are applied to the lander equipped with four side-thrust engines or a host-thrust engine with a gimbal.