Improvement of batch TRN using mean removal and two step search method for lunar lander

In this paper, to reduce batch process TRN (Terrain Relative Navigation) correlation problem caused by large position errors and for the improvement of computational effort, MRT (Mean Removal technique) and two step search methods are applied for lunar lander. MRT is the method subtracting the mean of both the measurement and DEM profile is applied. And two step search is the method using overall coarse and partially fine DEM. To meet position accuracy for precise lunar landing, a lunar navigation is operated by combination of INS (Inertial Navigation System) and TRN using altimeter, LIDAR etc. Until altimeter and LIDAR are operated, kilometers of cumulative errors caused by INS with time occur. Since these position errors induce bad correlation with measured terrain height profile and DEM (Digital Elevation Map) profile and cause wrong position fix, TRN considering large position error should be studied. By using MRT and two step search method, improvement of TRN position correction is shown in simulation.