Underwater Robots for Everyone

Dirak writes "A small 112-pound ocean glider named Spray is the first autonomous underwater vehicle to cross the Gulf Stream underwater. Launched September 11, 2004, it has been slowly making 12 miles per day measuring various properties of the ocean. Spray spent 15 minutes three times a day on the surface to relay its position and information about ocean conditions and then glided back down to 3,300-feet depth ." And reader RoboFreak writes "Two Computer Science students at Brigham Young University-Hawaii have developed a Low Cost Autonomous Underwater Vehicle. The students also entered their robot, LUV, in the AUVSI and ONR's 7th International Autonomous Underwater Vehicle Competition at San Diego, CA and competed against top Ivy-League teams. Their robot received recognition in the form of an award at this competition. This robot was designed with a budget of only about $600 and seems to be the cheapest AUV around. One of the AUV designers' interview conducted by Amit Kr Chanda of The Times of India is available here."

Comments

CUAUV

[Anonymous Coward]

cornell university has a student team that competes in the same AUVSI competition, and has a pretty sweet vehicle. designed almost exclusively by engineering undergrads, with no faculty intervention, and a lot of the components and boards are designed in-house. cool sensors, cool computers, and it all runs gentoo!

Re:CUAUV

[doopokko]

I'm the captain of the only high school team that competes in this competition. The BYU sub placed 17th out of 18 teams, and we placed 8th. However, the BYU sub cost aproximiately 1/50th as much as ours to build. We've got a lot to learn from these guys about dollar-efficiency.

More Details

[OctaneZ]

This was actually our third attempt to make it from Nantucket to Bermuda, the first two launches unfortunately ran into technical problems very early into the mission.

You can see the data it sent back over the IRIDIUM phone network every seven hours at these pages:
WHOI Instument page about the SPRAY glider
Our real-time plots page

Make sure you check out the plot of velocities when it got caught in the gulf stream

Also particularly interesting are the Continuous Temperature plot
and the Continuous Salinity (salt content) profile.

And you can also view the path it took to Bermuda

We hope to launch it again early next year, possibly for a roundtrip around Bermuda.

Re:The design is astounding

[OctaneZ]

The pump actually pumps vegetable oil from an internal bladder to an external one; this active pumping is required because we pull a vaccuum on the hull which holds the electonics and internal oil resevoir. The glider is then ballasted for ~1000m, so no energy unput is needed to reach the bootom depth, then after hitting the bottom, the pump turns on, increases the volume of the unit (the mass stays the same) thus decreasing the density, and we begin to float up, ascent is then contolled by draining and expanding the external bladders as neccessary to assure a constant gradual ascent to the surface.
At the surface we then rotate one of the battery packs 90 from center to aim the GPS receiver and IRIDIUM antenna which are embedded in the wings at the sky. really a neat design. The pitch of the vehicle is controlled by moving the second battery pack for and aft within the housing, to create the proper atittude.

Press Release on the SPRAY glider

[OctaneZ]

There is actually an informative and readable press release about the glider in general and the mission it just finished.

Re:Why is the oil sac on the back?

[OctaneZ]

The oil sac basically allows you to change the volume of the glider without changing the mass, by pumping the oil (think hydraulic/vegetable rather than petroleum) into the external bladder you effectively decrease the density of the instrument allowing it to rise. The pitch of the device can be controlled by moving one of the two battery packs for and aft to maintain whatever attitude is needed to create "lift" from the wings.

Solidworks

[xtal]

Autocad is no longer the gorilla it used to be. Solidworks is eating their lunch, at least from what I have seen, although it is unfortunate neither one of them has embraced OSX so I can justify one of those pretty machines.

A solid modelling open source program of comparable quality would make real difference to small manufacturing companies. I am suprised nothing like this has appeared already, actually.

Re:So why is the buoyancy changed?

[tylernt]

I changes the volume. If you consider a filled oxygen tank, the sucker is heavy and will sink like a rock. Use the oxygen inside of that tank to inflate a baloon, and it will shoot to the surface.

Yes, the mass stays the same. But that doesn't matter when it comes to buoyancy. The mass-to-volume ratio is the determining factor. May seem counterintuitive, but it works.