Now, how a about a working obstacle tracking sonar
small enough to fit in the rov or the model ?

“Just have a separate system act as a watchdog, blowing an airbag with a cartridge of compressed gas if no signal is received for a few minutes.”

The Trieste had one of the most elegant ‘hacks’ I’ve ever seen to address this problem. It powered big electromagnets that held a large mass of iron shot to the vehicle for ballast. If the vehicle lost power, the electromagnets can’t help but die, the shot drops, and it becomes positively buoyant.

http://en.wikipedia.org/wiki/Bathyscaphe_Trieste

This ROV looks to be about the same as what most of the high school teams had. The ROV competition is usually in a pretty shallow tank or pool so bilge pump motors work great. Most teams used cheap $50 underwater cameras you can get off ebay that are good for 66 ft. Teams from our province had some help getting standard and have slightly nicer cameras from lights camera action. Most teams simply use DTDP switches on the surface to control the motors. But alot of teams have been using PWM motor controllers.

I taught my students how to built a microcontoller(Atmega32) based control system using motor control boards from pololu. It connected to a usb joystick(xbox controller) through a laptop running vb(didn’t have time to teach them something better). The first year they built an oil filed enclosure for the electronics but it was nothing but trouble(leaking oil and it was heavy). So this year I kinda insisted that they keep the electronics on the surface. We had a 33foot tether donated to us with 5 18ga pairs, 1 22ga pair and a 75ohm coax.

They cleaned up at the regional competition but had trouble with the temperature probe at the worlds. Leakage currents were throwing the temperature readings way off. After 3 hours of tracking down cracks in epoxy covering the solder connections they made a second attempt at the mission. They got a perfect temperature reading and then they lost video. They assumed the break in the video was underwater where they had been working on the wiring all afternoon to fix the temperature probe issues. I figured out later that the wire cracked off at the surface on one of the two video outputs. They didn’t even try the other output assuming the problem was under water.

He’s going to be disappointed – the FM radios penetrate about 5 feet well, IIRC. He’s going to have to tether it for any useful range.

Here is one I helped a team make.
http://pnta.org/engineering/showmedia.php?id=336
http://pnta.org/engineering/showmedia.php?id=344

Which frequency is used to which RC models varies, but it’s probably 27 or 40MHz, which means a wavelength of 7.5 or 11.2 meters, which is already a bit impractical for using optimized antennas.

Retrieval of a failed sub shouldn’t be that hard, provided it can float up to the surface freely. Just have a separate system act as a watchdog, blowing an airbag with a cartridge of compressed gas if no signal is received for a few minutes. Now if something fails, just turn off your transmitter and wait. If the sub is inside a cave, shipwreck or whatever, retrieval would be a bit more difficult.

That mean RF, a tether, ir, what have you.

My question is how far the RF is going to penetrate water.
that’s the main reason why tethers are used.
well…maybe that and getting your rov back. ;)

That mean RF, a tether, ir, what have you.

My question is how far the RF is going to penetrate water.
that’s the main reason why tethers are used.
well…maybe that andd getting your rov back. ;)