Smaller Lidars Could Enable UAVs to Look Underwater
A green laser shines through water at GTRI during testing. Photo: Georgia Institute of Technology
A team at Georgia Tech Research Institute designed a new approach for bathymetric lidars, which are devices that use lasers to scan beneath surface water, that are much smaller and more efficient than current systems.
These smaller lidars could be used on UAVs to reduce the dependency on manned aircraft to acquire undersea imagery from the current 600-pound units.
The team has tested a lightweight bathymetric lidar in the lab with successful results. They have also designed a mid-size lidar aimed at deployment onto unmanned helicopters that is half the size and weight of current models, according to a press release.
In the lab, the team flew the lidar over a pool using a crane setup and fired 10,000 laser beams per second into the water. When the laser hits the water, light refracts and photons are scattered, making it difficult to sort through noise and achieve an accurate image.
“In our laboratory tests, we’re computing about 37 million points per second — which is exceptionally fast,” says Grady Tuell, lead scientist on the project. “The key is we’re using FPGAs [field-programmable gate arrays] to do the necessary signal conditioning and signal processing, and we’re doing it at exactly the time that we convert from an analog to a digital signal.”
This processing is adapted to the environment to get the best data from each returning signal.
Eventually, the aim is to develop bathymetric lidars that can fly on small UAS with payload of 30 pounds or less. Signal processing would be done on the aircraft and only essential data would be transmitted to the ground station.
“We’ve provided a prototype that demonstrates the key technology, and we’ve completed a design for a mid-size design,” says Tuell. “In the future, we believe small bathymetric lidars will perform military tasks and also civilian tasks, such as county-level mapping, with increased convenience and at greatly reduced cost.”
