Underwater autonomous robot fleets

Inspired by the coordination of bird flocks and fish schools, oceanographers will launch this month an entire fleet of undersea robots in Monterey Bay, California. These underwater robots will work together without human input. And we might see one day self-choreographed robotic teams guiding military operations at sea or exploring other planets
Written by Roland Piquepaille, Inactive on

Inspired by the coordination of bird flocks and fish schools, oceanographers will launch this month an entire fleet of undersea robots in Monterey Bay, California. These underwater robots will work together without human input. The goal of this program is to make detailed and efficient observations of the ocean, but it also has larger implications. For example, "it may lead to the development of robot fleets that forecast ocean conditions and better protect endangered marine animals, track oil spills, and guide military operations at sea." And the researchers think that self-choreographed robotic teams might even explore other planets. Read more...

This experiment is one critical part of the three-year program known as Adaptive Sampling and Prediction (ASAP), led by Naomi Ehrich Leonard of Princeton University and Steven Ramp of the Naval Postgraduate School.

Before going further, below is an image describing the Autonomous Oceanographic Sampling Network (AOSN) of Princeton University, which is a coordinated group of sensor platforms capable of collecting oceanographic data in an optimized manner. Some of these sensor platforms included Autonomous Underwater Vehicles (AUVs) (Credit: Princeton University).

The Autonomous Oceanographic Sampling Network

Now, let's look at the Princeton University news release mentioned above.

During the experiment, the ASAP system will determine what paths the underwater robots should follow to take the most information-rich samples, or measurements, of ocean activity. As the ocean changes, automated computer programs will update the sampling strategy under the supervision of the ASAP team. Most of the scientists will not be on site during the actual field experiment.
The team will collaborate while the experiment is ongoing through a virtual control room, something like a chat room for the ASAP scientists. The researchers will gather online in the virtual control room to share observations and make important decisions about necessary changes to the field operation as it is under way.

This program is using several kinds of underwater robots, or gliders, which will independently measure the ocean's temperature, salinity and other variables.

Two types of gliders will be deployed -- Spray gliders and Slocum gliders. The Slocum gliders belong to David Fratantoni of the Woods Hole Oceanographic Institution; the Spray gliders to Russ Davis of the Scripps Institution of Oceanography.

Here is a picture of two of these Slocum gliders before launch. When these gliders, manufactured by Webb Research Corporation, are on the surface, the Princeton Dynamical Control Systems Lab (DCSL) communicates to the vehicles during ocean experiments via Iridium satellite phones. When the gliders submerge, they follow prescribed trajectories at approximately one kilometer per hour (Credit: Princeton University).

Slocum gliders before launch

This image, as well as the one above, has been extracted from this paper published by Princeton University (PDF format, 1 page, 2.51 MB)

And here is a picture of Spray, which has been developed by Scripps and Woods Hole scientists (Credit: Scripps Institution of Oceanography).

The Spray underwater robot

Here is a last word about the algorithms developed to allow the gliders to self-choreograph their movements.

On a day-to-day basis the control algorithms allow the gliders to make decisions independently about how to alter their course -- without any input from humans. This day-to-day autonomy enables the gliders to move according to the organized patterns, even as they are buffeted by strong currents.
As the ocean changes and new features are detected in the measurements and the forecasts, the ASAP team will reorganize the patterns to help guide the gliders toward ocean features of interest such as eddies and thermal fronts. This process, called "adaptive sampling," is expected to dramatically improve our knowledge of the ocean and our ability to predict its chaotic behavior.

So will we soon see robotic ballets under the sea -- and even in space? Let's wait until the end of the month to see if this experiment is a success.

Sources: Princeton University news release, via EurekAlert!, August 1, 2006; and various web sites

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