Open-Source Mini Sub Can Be Made On the Cheap 62
An anonymous reader writes "Eric Stackpole is a NASA engineer and avid outdoorsman. He is the chief designer of a cheap, portable underwater ROV that could change the way we explore our oceans. And he wants to make it so cheap and easy to build that anyone can do it. The device in question is the OpenROV, a small, lasercut contraption powered by several C-cells, a small, cheap computer and a webcam. Right now the price per vehicle is around $500-$600, As with all open source hardware projects, further development will likely drastically reduce the price. Or you can buy a kit for $750 and support the project, once the Kickstarter gets going."
Re:As a Columbian cocaine importer... (Score:4, Interesting)
I am very grateful for this US Coastguard evading tech....
Really? "OpenROV 2.2 is 300mm long, 200mm wide, and 150mm tall. It displaces approximately 2.5kg of water and has a theoretical depth capability of approximately 100m." Yep... So much better than just driving across the border...
Cost (Score:3, Interesting)
My gut tells me that it could be done cheaper (probably $300 or so), but the price estimate for parts looks reasonable. The electronics cost around $200, the propulsion system around $125, and the frame about $100.
On a side note, the design is to be neutrally buoyant. I don't necessarily agree with this. A slight negative buoyancy is beneficial to submarines because they can more easily fine tune and control their depth with their propulsion system. Maintaining a constant depth with a neutral buoyancy will result in hunting (up, down, up, down, ...). With a negative buoyancy the motor would constantly operate at slow speed giving greater control.
Increased depth? (Score:5, Interesting)
I wonder how much increased depth the chassis could sustain from purging all air and filling it with mineral oil. The hydrostatic properties should make it structurally stronger, but could be an issue for the webcam optics. Alternately everything could be water proof coated and skip the sealed cylinder altogether. I'm pretty sure several layers of enamel or rubberized undercoating would sufficiently work for the home builder on the circuit boards and wire contacts. Old school would just be resin back fill everywhere, and that has worked for years.
Any sort of flooded arrangement would need pretty careful camera selection as one would be best served by a fully sealed unit that could handle the pressure at depth. Too many cheap webcams have nearly exposed CCD arrays or are vented cases for mics. Cameras sourced from cell phones are probably the most solid bet.
I would ditch the C-cells entirely and use relatively cheap LiPo batteries made for remote control aircraft for increased time and power. If he is using Cat 5/6, he should be able to dump power in though there reasonably easily as well.
Also, the new camera add-on for the Raspberry-Pi sounds like a potentially more compelling combination. I'm curious what manner of motor control he is using. Arduino would work fine with a Raspberry-Pi and is vastly cheaper than RC servo and motor controls, though at that point it might be just as easy to go completely Arduino and skip the PC brains. I do have to say the price point sounds a bit high, but I am guessing most of that is the custom plastic and steel molding and mill work. Fiberglass or even carbon fiber should be cheaper because you just need molds and cutting patterns or dies. Building everything for sub 200-psi pressure should be pretty easy.
Wires are a leak point (Score:3, Interesting)
It is a shocker that any wire that is exposed to water, even very shallow water, will eventually allow that water to creep along the copper underneath the wire insulation. Getting gear to be truly water proof is always more difficult than one would think. I believe there are some electronic watches that are filled with silicon oil to resist water intrusion.
Re:As a Columbian cocaine importer... (Score:5, Interesting)