Good source for motors: rechargeable power drills. Small ones can be had for 5-10 euro. They even come with NiCd cells and a charger. I bought some and they have a 3:1 gearbax, wich seems ideal for most boat propellors. They're not waterproof, evidently.I am building a land prototype first, wich will be wireless. Underwater, you can forget about wireless comms, I think. Hance, GPS will probably not function, unless you are really close to the surface.Sure, underwater modems exist, but they only offer a few hundred bits/sec...I really hope someone here will prove me wrong about underwater comms, tho :-)
Here's a quick primer on how to program an Arduino over a wireless connection.Now, we can put an Arduino on the ceiling, underwater, up a tree, stuffed in a turkey or what have you and still be able to change and improve its behavior. In fact, by adding an XPort or WiPort to the XBee, we can extend the connection over the Internet, and program anything from pretty much anywhere.
For a sub, a ballast system would be needed, and if I were lucky enough to be working on such a project, I'd also need to be working on a solution.
For sure. I'd love to see a more efficient way of doing it too. A common problem is that sometimes devices requires a larger voltage than the board delivers. Plus you don't want the options narrowed because of those limitations. Since relays are cheap as are the 595's, until there's a better option, that would be my immediate choice. You could pulse the motor to manage speed, which is actually quite ingenious when you think about it. I don't think pulsing would be inefficient either. An object of neutral buoyancy also wouldn't need to conform to any particular shape. You could use a ping pong ball, for example, attached to shaft attached to two rotary encoders to determine the objects tilt for staying flat in the water, and using thrusters for making corrections. The ROV could be the shaped like a ball, hypothetically. Once I'm over my current back log of work, and other projects I'm working on, I'd definitely like to put all that to the test.