Bathymeteric Lidar

For my first blog post, I am reviewing an article on a new Light Detection and Ranging (lidar) system.  Lidar has been used in all major unmanned systems, ranging from UGVs to satellites.  The article is titled, “Smaller Lidars Could Allow UAVs to Conduct Underwater Scans”, and was posted by Product Design and Development.   

The Georgia Technical Research Institute (GTRI) has designed a new bathymeteric lidar system that may allow unmanned aircraft to conduct improved underwater scans.  Bathymetric lidars transmit an infrared and green spectrum light wave.  The infrared band is quickly absorbed and detects the waters surface while the green band penetrates the water.  

The issue in current bathymetric systems is that the water causes refraction when computing the path of the light.  This makes bathymetric systems less accurate as water depth is increased.  To solve this problem, GTRI researchers have devised a new approach called total propagated uncertainty (TPU). 

The TPU implements rapid computing Field Programmable Gate Arrays (FPGAs) to propagate errors from the individual lidar measurements.  This provides better water penetration imagery.  Professor Grady Tuell, the projects principle research scientist stated,  “In our laboratory tests, we’re computing about 37 million points per second – which is exceptionally fast for a lidar system and gives us a great deal of information about the sea floor in a very short period of time”.  He further explains, “The key is we’re using FPGAs to do the necessary signal conditioning and signal processing, and we’re doing it at exactly the time that we convert from an analog signal to a digital signal.”  FPGAs are traditionally used for fixed-point digital signal processing.  TPU offers competing levels of floating-point processing thus improving imagery.

The lidar system weighs approximately 30 pounds, allowing it to be flown from small UASs.  The new bathymetric lidar will have many military applications, but it will also be a benefit to the civilian sector.  Mapping of the sea floor can assist in search and rescue operations, searching for oil, tracking whales, observing geological processes, and much more. 

Reference:

Product Design and Development (2014). Smaller Lidars Could Allow UAVs to Conduct Underwater Scans. [ONLINE] Available at: http://www.pddnet.com/news/2014/12/smaller-lidars-could-allow-uavs-conduct-underwater-scans. [Last Accessed 16 January 2014].