31.1.07

DepthX

Diving deep: robot explores waters in central Mexico for life
"Carnegie Mellon’s Robotics Institute recently developed software to be used in a deep-sea exploration project called DepthX.
Deep Phreatic Thermal Explorer (DepthX) is a mission to deploy an autonomous underwater vehicle (AUV) to the bottom of Zacaton Cenote, a sinkhole in central Mexico over 1000 feet deep. Dr. David Wettergreen of Carnegie Mellon’s Robotics Institute developed the robot’s navigational software. Wettergreen’s past research has focused on robotics exloration, but this is his first underwater mission with Carnegie Mellon.
Wettergreen said that the project’s ultimate goal is to study the sinkhole’s underwater environment by collecting water samples while also creating a three-dimensional map of the sinkhole. “We need a vehicle...that can move through complex cave systems without getting lost or trapped,” said Wettergreen.
The vehicle is seven feet in diameter, and it can spin and move in any direction. Also, its buoyancy is very high, and the center of mass is very low, making it ideal for underwater exploration. “It really wants to float upright in the water — it turns out to be extremely stable,” Wettergreen said.
In the DepthX project, Wettergreen helped develop software that enables the robot to map its environment. This particular kind of software is called simultaneous localization and mapping, or SLAM.
Project leader and Pittsburgh native Bill Stone of Stone Aerospace said that in the bottom of Zacaton Cenote, “things get very complicated, very fast.” He said that SLAM is a clever way to determine the vehicle’s location because it allows the vehicle to build a map of its three-dimensional surroundings. The map also includes information on the water’s temperature and salinity levels.
Wettergreen said that previous explorations into Zacatone Cenote have not gone deeper than 30 meters. Nonetheless, these exploration missions have turned up some interesting results. In particular, the water contains low amounts of dissolved oxygen, and the water’s temperature is unusually warm — 90°F. Wettergreen said that DepthX may provide some data that explains these findings. (...)"

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