This spring I’m trying to build a ROV for me and the kids to play with in the summer. I’m trying to make it as small as possible so it’s easy to carry and bring along.
Instead of feeding power down the tether I use a 12V 1.2Ah lead acid battery as the power source and ballast. There will be a webcam onboard and the only signals going down the tether is serial signals to control the motors and video signals up to my laptop.
The control box contains an Arduino and two thumb joystick. The Arduino translates the joystick input and sends serial information down to the serial motor controller http://www.pololu.com/catalog/product/1110 . Sins I have 3 motors I had to daisy chain two boards.
The hardest part to get built is the stuffing box. Luckily my brother has contacts that could machine them for me and they came out great.
Still waiting for the USB webcam to arrive and can’t do much testing before it has been mounted. When everything is assembled and found working (and balaced) I will coat the ROW with Plasti Dip to seal everything. http://www.plastidip.com/home_solutions/Plasti_Dip
Project update: 23/5-2010
Problem 1
With all installed the ROV has a negative buoyancy.
Remedy: Buy more 40mm PP tube and extend the connection joints. Some wiring also has to be lengthened.
Problem 2
My 35mm propellers at 1000RPM is not giving me enough thrust. So I will be ordering some new 3-blade 52mm ones and hope that they will give me some more thrust.
Problem 3
With my 15m of cable the USB webcam is not giving me an image. The pc recognizes the device but the cable (a CAT5) is probably too long and I’m running into some sync issues.
I found some USB to CAT5 extenders that might help.
http://cgi.ebay.com/USB-Cat5-e-Cat6-RJ45-Convert-Cord-EXTENDER-CABLE-Laptop-/280359081164?cmd=ViewItem&pt=LH_DefaultDomain_0&hash=item4146b414cc
I need to hack them in order to make them fit into my tube and control box.
Has any of you any experience with USB to CAT5 extenders?
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Project update: 10/8/2011
This project has been on the backburner for over a year. I was about to scrap the whole project but my brother convinced me to have another go at it. So now I’ve pretty much ripped the whole thing apart. Thrown away my control box and started over.
So this is my new approach;
Using a USB based webcam didn’t work. So I have ordered a cheap CCD camera of eBay, together with a 7” LCD monitor. This is probably a good think as I can mount the joystick and monitor in a bigger box and there will be no need for a PC.
I have got the new propellers and rebuilt the shafts. It looks better but has yet to be tested.
One of my main problems was how to get a waterproof connection from the tether cable through my PP plastic plumbing parts. And mounting it on a round pipe made it even worse (PP plastic is almost un-gluable). So my solution became to add a 45deg t-fitting on the motors. That gave me a flat fitting with a regular garden hose adapter. These adapters come in and variety of different materials and will be much easier to work with.
I’m still not certain that this ROV will ever work, but I have a better gut feeling about this design than the last one.
The image shows most of the parts assembled and nearly all the of the wires.
My plan is to have the video signal and power in on the left side and the serial, error, and reset on the right hand side. They will be joined into a CAT-5 cable going to the surface.
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Mounting the thumb joysticks
Inside the control box
The frame
Battery in place
The main structure is mad from 40mm PP- pipefittings
The serial motor controllers and voltage regulator
Not much room
The stuffing box
Fill up with grease
Stuffing box assembled (updated: 19-05-2010)
And finaly mounted
