Custom ROV build for ocean science

[vegards (Vegard Stürzinger)]

Hello!
Its been a long time since i have posted here, i was building a BlueROV1 back in the days when that was new. I didnt finish it as i switched jobs. However now i am back, slightly more grown up and i have learned a bunch of new skills like CAD and 3D printing. I work as a biologist in the European arctic for a Norwegian governmental institute. We do mostly monitoring so there is little time to develop new methods for sample collection etc. We do go on longer research expeditions to the Arctic Ocean and we work alot around the Svalbard islands. I started some engineering studies, which is where i learn CAD which i found highly enjoyable.

My project now is to build a custom ROV that is modular/adaptable for different task, without growing too large or heavy. I managed to source a good set of used enclosures (4" and 3") and 8 thrusters with ESCs here in Norway.

My custom ROV frame design is largely inspired by the BR2 but i made it a bit larger and symmetrical so that i can switch the orientation upside down (depending if i want to work towards sea ice or towards the bottom). The H frame will be connected with 2020 aluminium profiles and there will be one HDPE plate for the surge/sway thruster mount and the trays for the enclosures. The space above the 4" enclosure is thought to be space for payload which will be custom made for this ROV. The 4" enclosure is supposed to have a dome, and the 3" is not, but they were the ones i could find in the onshape library, so they are more illustrative, i have also not yet designed the clamps for the enclosure trays.

Here are a few images from the CAD assembly:

For transport i want to dissasemble the outside thrusters so that they are protected, i am considering to design some thuster guards.

The first two payloads i am considering are a suction pump to collect samples in a tube that is lined with 20 micron mesh at one end to collect algae samples and whatnot. The second payload would be a stereo camera if i have time before the next expedition.

I would appreciate some input and design ideas before i send the CAD files for CNC machining. I am as of now limited to 100m tether which i managed to source from a broken ROV.

I hope you find this build interesting!

[tony-white]

Hi @vegards

Very cool! By onshape library, so you just mean searching the public files? Keep in mind that all product pages have 3d models so it’s easy to download a part and import into any CAD software!

It’s possible to 3D print clamps that are only one piece, but aluminum two piece ones from the store are the most robust option. Newer thrusters have a single M8 mounting point in addition to the usual 4 smaller ones, that may be better to use if you want to quickly remove some thrusters for transport.

I’ve generally found t-slot to be heavy and far stronger than necessary for an ROV frame, but the flexibility in mounting points is undeniable. Tough to find hardware that doesn’t corrode though, definitely consider using zincs to protect things!

Finally keep in mind that when you add buoyancy foam, you ideally want to keep drag symmetrical around your horizontal forces. It’s impossible to avoid some imbalance with this layout, which the BROV2 has as well, but you’ll have a more efficient vehicle if it’s well balanced and doesn’t pitch when accelerating in manual mode.

Best of luck!

[vegards (Vegard Stürzinger)]

Hi Tony,

Thank you for your reply! I used to download the files when i was trying out fusion360, the public library was mostly out of convenience. I just wanted to check for fit on the frame i am designing. The thrusters i bought second hand sadly don’t have the center m5 bolt but i would prefer that. I have ordered some zinc anodes to hinder corrosion.

I will have to read a bit about the best way to balance the vehicle when adding the foam. I do appreciate the warning, it gives me chance to make friendly design choices!