Abstract: 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.

Key words: soft landing, multi-resolution analysis, targets detection and recognition, hazard avoidance, landing site