Optimal Landing Zone Selection and Online Trajectory Programming Method for Lunar Lander

Abstract

To achieve a safe landing on the lunar surface with complex terrain, online landing zone selection is required. A DEM-based landing zone selection technique is proposed. The method firstly obtains several candidate landing zones by analyzing the gradient and variance information from the DEM, and then selects the integrated candidate landing zone by the overlap ratio. Finally, the optimal trajectory programming is carried out with the current state of the lander as the initial value and each integrated candidate landing zone as the final position, and the optimal landing zone is selected by comparing the required fuel to each landing zone. Compared with the classical DEM-based online landing site selection technique, the proposed method does not perform terrain reconstruction, responds quickly, and achieves real-time performance, and it also reduces fuel consumption, provides residual fuel for the subsequent landing phase, and increases the reliability of the landing process. Simulation results show that the proposed method is able to select several candidate landing zones in complex terrain, meanwhile, it is capable of achieving the optimal trajectory programming with the target of these several candidate landing zones, and finally, the optimal landing zone is selected by comparing the fuel consumption of each path.