I design machines all day, so of course I’m gonna build robots at night. That’s where the OpenROV v2.6 kit from OpenROV comes in. I bought the kit online and I’m most of the way through assembly, so I wanted to put up an intro to where I’m going with the kit, what I want to accomplish, modify, etc. So, here goes the goals, current progress, and my thoughts so far.
- 1. Build and Deploy an Underwater Robot
- I know, simple, right? I haven’t completed a robotics project all on my own ever, in fact I haven’t done a mechanical project solo and had it work out since I can remember. So, this is a big step for me in following through and not letting things like scope creep, low attention span, or a social life get in the way of my robotics.
- 2. Smack Some Sense Into It
- The OpenROV kit comes with a camera and very little other sensing built in, as far as I can tell. I bought the extra IMU/Depth sensor module to go with it, and the first step is to get that integrated in the machine. From there the trick will be to find sensors I can use reliably underwater, and start to give the ROV an idea of where it is and what’s going on in the world around.
- 3. MOOSify it
- I don’t know how much autonomy I can build into the ROV using the existing software structure, so this step may change a little, but the idea is to get MOOS-IvP, a robot program architecture and autonomous helm, working on the machine so that it can use the already huge library of MOOSApps available for autonomous underwater vehicles. I’m partial to MOOS over LCM or ROS because the IvP Helm is only available on MOOS and it’s something I’m already familiar with. Maybe the next ‘bot I make will run ROS, who knows.
I got the kit a couple of weeks ago, opened it up and spread everything out to take a look at the parts. The shell makes for a pretty cool shape, and I like all the clear acrylic in the build. I’ve seen a lot of PVC-pipe ROV’s and there’s a lot of pain involved mounting anything other than PVC pipe to PVC pipe. Plus, I would expect nothing less than laser-cut parts from a small Bay Area group like OpenROV. The other parts look pretty standard, some tubing and o-rings, but the thing that really caught my eye is the brushless motors they included for thrusters. Spending some time on the site, it looks like they use the motors flooded, meaning that the coils and everything are exposed to salt water. Honestly this makes sense, because the coils are enameled wire and therefore should be protected against corrosion and arcing, and there’s no pesky commutator to make for crazy through-water electrical badness.Building up the structure and waterproofing the motors went smoothly, though I had to buy a nicer soldering iron to deal with the smaller wire sizes. (Aside: RadioShack is still selling great electronics tinkering tools for pretty cheap. Who knew?) I halted there after step 20 or so, because I didn’t have the right applicator for the acrylic weld solution, I was using the brush type instead of the needle bottle type. I paused, took the time to buy the correct applicator, some batteries and chargers as recommended by the site, and the right type of epoxy instead of the Home Depot random kind I’d picked up. From there I started using the helpful spreadsheet made up by a teacher on the site, for managing a group of students. I added the step numbers beside the step titles because I was using the instructions offline. (Don’t get me started on my apartment’s internet issues) Doing that let me knock out the battery tubes and wire routing before my applicator came, and once that was in I could build up the electronics tube and the board stack/camera mount before the epoxy arrived in the middle of last week. I haven’t worked on it since then, but my next step is to do all the epoxy potting in one swoop, and then move on to hooking up all the electrons!Thanks for getting through a long post, here’s a nice picture of Chicago for you!