As I've mentioned before, I work for a company called Bluefin Robotics located in Cambridge, Massachusetts. I haven't really talked about our technology, but we just recently got a contract for the next generation of one of our coolest vehicles, and I really like talking about this one, so on to... the HAUV!
The Hovering Autonomous Underwater Vehicle started out as a joint project between Bluefin and MIT. It's a significant departure from our other vehicles, which are torpedo-shaped with propellers on the back. HAUV is more or less a box, not needing to be quite as hydrodynamic as its siblings, and as such has occasionally earned nicknames such as "Spongebob" in the Bluefin lab.
The HAUV is run by a main electronics housing (the brains) and a 1.5 kWh subsea battery that we make. It moves thanks to eight fancy hubless thrusters arranged to allow a full six degrees of freedom: X, Y, Z, roll, pitch, and yaw. To navigate it uses a Doppler Velocity Log (DVL), which provides the computer with velocity along the hull; an inertial measurement unit to measure orientation in space (or water!); a compass; and a GPS antenna to achieve a position lock when it's on the surface. Its payload is a Dual-frequency Identification Sonar (DIDSON), located on the front of the vehicle next to the DVL, which provides imagery of the ship hull that looks a lot like a blue ultrasound. The Soundmetrics website (linked above) shows what some of that imagery can look like.
HAUV communicates with an operator via a fiberoptic cable that runs between the vehicle and the ship, but the cable is there for transmission of sonar data, not for active control from the operator (though the operator can upload new sortie commands via the link). This is different from our other vehicles, which are not tethered in any way and instead communicate via acoustic link underwater or via Iridium satellite or an RF link on the surface (depending on distance from the ship).
So what is this all for? Hull inspection, basically. Plop this little guy in the water next to a ship and it can go to town taking images of the hull. If it sees something suspicious, the Navy or Coast Guard can send down a diver to check it out and dispose of it as appropriate. Port security is a big deal these days, so there could be a lot of work for the HAUV.