ROV update

It's been a while since I first posted about my plans to build an ROV, and I've been quite silent about it since then, but progress has been slowly happening. I'm hoping to get a chance to do a lot of construction work done in the next week or two and I'll make sure to post pictures of as many stages in the building process as I can. I have the majority of the frame cemented together now, and it turned out much better than I'd hoped. PVC pipe and the standard fittings for it obviously aren't intended to be used to build complicated, precision structures, and I'd worried that I'd be left with something a little bit wonky, but it turned out great. Both the top and bottom parts of the frame are almost perfectly square, are the same size as each other, and really quite tough. I've bought a single 450 GPH bilge pump to "test the waters" with (buh duhm kssh!) and I hope to be able to post a YouTube video of a simple bathtub test soon.

During the time I've actually been working on the frame, I've been thinking about the (to me) more interesting and exciting stuff, like control. My original plan had been to keep things extremely simple, and just control the thruster pumps using a block of relays which I sent signals to directly from a control unit on the surface over some ethernet cable. However, I've been doing a lot of reading lately on the Arduino boards and how to do all kinds of things with them. They are much, much easier to understand and work with than I ever expected and I pretty much can't wait to buy one and start playing with it. So I think I'll put an Arduino onboard my ROV from the start - to begin with I'll just use it to control the pump relays, but I think I'll pretty quickly want to start attaching devices to it for navigation and recording data on things like temperature and water pressure.

One really nice thing about using an Arduino for control is that I can put an ethernet shield on it and then control the ROV directly from a laptop, rather than having to wire up a box of joysticks and/or buttons to do control. I had intended to have a laptop present for ROV sessions anyway (to display camera footage), so this actually reduces the amount of work involved to some extent. Furthermore, if I can find a cheap IP camera to use instead of a USB webcam, and I can find a very small ethernet hub or switch (this page suggests it may actually be easy to build such a thing using nothing more than some diodes!) I can get away with the one ethernet cable for control and video. My original plan had been to have one cable for talking to the relays and a separate one for video, which would carry the signal from a USB webcam using an ethernet-USB extender. Cutting down the number of cables in the tether will reduce cost and increase speed and maneuvarability, which are both good things.