Terrain Relative Navigation (TRN) and Dual LIDAR-based Navigation

 

from Prof. Dr. ir. Maarten Uijt de Haag, he introduces pros and cons of using

dual LIDAR

Andrew Johnson's presentation:

 

this TRN has been in use since Mars MSL mission in 2011, and advance further  in Mars 2020

 The Mars 2020 mission is facing the most challenging landing yet on the Red Planet. It will touch down on Feb. 18, 2021, in Jezero Crater, a 28-mile-wide (45-kilometer-wide) expanse full of steep cliffs, boulder fields and other things that could boobytrap the landing. A new technology called Terrain Relative Navigation (TRN) will allow the spacecraft to avoid hazards autonomously.

This improves the landing accuracy from previous 1 to 2 km to now less than 60 m 

The Lander Vision System (LVS) for M2020  is representative of the current state of the art in map-relative localization for TRN. Orbital reconnaissance imagery of Mars is available with a resolution of 30 cm/pixel from the HiRISE camera; this is processed into maps at two resolutions, 12 and 6 m/pixel, for coarse and fine localization processes, respectively. Map-relative localization uses onboard altitude and attitude knowledge to project descent images onto the ground plane and to resample them with the orientation and pixel scale of the prior map. The resampled descent images are then registered to the map using traditional template matching techniques that conduct a 2-D search for the best match position. The orbital and descent cameras have similar spectral responses and lighting conditions, so template matching uses simple algorithms based on normalized cross correlation (NCC). This processing pipeline is implemented in a field programmable gate array (FPGA) coprocessor to provide the necessary low latency output. LVS includes two matching modes . In coarse matching mode, descent image templates of 128x128 pixels are correlated against 1024x1024 search windows in the map using a frequency domain correlator implementation. In fine matching mode, 15x15 pixel templates from descent images
are matched in 100x100 pixel map search windows using a spatial domain correlator implementation. LVS achieves a position error <40 m relative to the map.

 Osiris Rex's Natural Feature Tracking (NFT)

  

SPLICE in Human Lunar landing missions, coherent doppler Lidar

Report of the Mars 2020 Science Definition Team p69-71

Lidar based approach to TRN for precise lunar landing

TRN for guided descent to Titan