||[Jul. 24th, 2009|07:50 pm]
This week I had an inspiration.|
I mean, they would be fish -- but they would also be robots!
What could possibly be cooler than that?
The thought occurred to me when I was thinking about sensible ways of mapping the ocean floor. (It's hard to map the ocean floor, because no light gets down there--even if you bring your own, it doesn't go very far--and only long-wave sonar can go far enough, so the resolution is bad.)
My initial thought was to use some kind of sub with an X-ray discharger and X-ray camera.
Unfortunately, it turns out that X-ray attenuates pretty fast in water, so it would be impossible to take pictures from hundreds of meters above the surface.
But I found an IEEE paper about some experiments with megahertz-frequency radio signals in sea water. They were able to maintain radio contact between portable units that were 70 meters apart.
So here's where the robotic fish come in. If they could be programmed to keep in radio contact--try to stay 40 meters from their neighbors, for example--and otherwise sink toward the bottom, you could have a chain of robotic fish that
(1) know how far they are from their neighbors, which gives you 3-d structure if there are enough neighbors,
(2) is ultimately connected up to some buoys on the surface that get GPS.
In other words, the fish all know where they are when they start to detect ocean floor.
I did some simply calculations. If the fish are trying to keep 40m apart, then each fish on average covers about 1400 square meters of ocean floor, so it would take a few hundred to cover a square kilometer. Hundreds of thousands of fish could cover a larger area, all taking in a little bit of sensor information and relaying it up the chain...
Wouldn't that be cool?
So today I googled around a bit, and found that, sure enough...there's a website devoted to robotic fish, and even better--there really are robotic fish that you can see on the site.
A little more poking around brings an environmental project based on robotic fish and even video of how one moves.