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PRISM ROV

Failing my way to an underwater robot

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The goal of this project is the development of a cheap DIY remotely-operated vehicle (ROV). So far, I haven't got there, but each design iteration does better than the last.

Of all of my projects, this one is definitely the oldest. I started working on my first ROV in October 2012, back when I knew very little about electronics and nothing about programming. I was motivated by the challenge - designing an ROV is no simple task - and by the potential for discovery that it offered. This project started with the simple objective of building something, but it has grown since then to include a whole suite of vehicles, probes, and concepts.


The things I've learned from building ROVs have helped me with almost every other project I've worked on. Whether it's an electronics skills, programming technique, or project management structure, I can often trace its origins back to this project. I haven't yet built a properly useful ROV, but each iteration of this project teaches me something new for the next attempt. Every failed test flight has taught me something valuable and, because of this, every test flight lasts a little longer than the one before it. So, with that, lets meet the iterations of failed ROVs.

Version 0 (Early 2017)

Version 1 (Summer 2018)

  • History: ROV Version 1 (Summer 2018)

    Alex04/30/2020 at 22:22 0 comments


    The successor to Version 0, Version 1 was supposed to be a much more capable vehicle and it came with a radically new design. Version 1 was supposed to be the first of what I called 'lander' type designs: everything would be mounted to a lower structure, which could theoretically double as a landing pad/foot if the vehicle were ever to settle on the seafloor.

    This was also the first ROV to use 3D printed parts and Blue Robotics parts. I realized that, after Version 0, I would need to get some proper ROV hardware, so I purchased an enclosure and electronics tray from Blue Robotics. This enclosure made a world of difference - there was still the occasional leak, but it was so much more reliable. The electronics tray also made it so much easier to maintain the vehicle - gone were the days of haphazardly stuffing electronics into a PVC tube. As the for the 3D-printed parts, I realized that I would need some better hardware moving forwards, so I got my printer into gear creating thruster brackets.

    Speaking of thrusters, you may notice the lack of up-thrusters. See, in my zeal for 3D-printed parts, I had designed a cool new compound thruster block that would give me way more degrees of freedom and allow me to mount the bilge pumps somewhere else on the vehicle. The only extra step was to connect the thrusters to the blocks with some tubing. Problem was, I couldn't quite make that work - the tubing would kink or the blocks weren't the right shape or something else would go wrong and leave the vehicle unable to maneuver. So, as a backup plan, I decided the ROV would not have up-thrusters - it would just be positively buoyant. When I wanted to descend, I would simply run the down-thrusters and then pulse them to maintain my depth. Unfortunately, this didn't really work.

    Aside from the thrusters and the new enclosure, a lot of stuff was the same. The outboard tubes still housed lantern batteries and the thrusters were still controlled by a Raspberry Pi. I made some software improvements to account for the new thruster design and the fact that my camera now had a pitch servo (yay!), but it was largely the same vehicle.

    Version 1, unfortunately also didn't work. It worked better than Version 0 and made it as far as bathtub tests, but it wasn't able to stay afloat when taken out to open water (the quarry by my house). Turns out, the wood plank I used absorbed water (who would've guessed?!) and caused the vehicle to sink. All of my careful ballast adjustments had been for nought which was a shame, because the ballast was really hard to adjust on this vehicle. Version 1 also suffered from leak problems and trim problems, so it seemed that the battery tubes would be the main focus for the next vehicle.

    One good thing about Version 1: it looked really cool during maintenance.

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