Hi all, I'm looking to build a 1000ft capable ROV to help assist a full scale homebuilt submarine in tests later this year. My initial thought is to use a 150 Cu ft welding tank as a pressure vessel, with an acrylic windows and brushless FPV motors for propulsion. Any and all suggestions are appreciated. My biggest hurdles coming into this as an extremely inexperienced builder are tether (How well does ethernet work at depth/length) and motor controllers/ESC's. What electronic hardware would I need to use to control axes of motion, or would I need to custom build one for the task? I have access to a full machine shop so fabrication should be possible for most material. I hope to put together a CAD model after this discussion and then move to prototyping. Using the pressure vessel calculator from PSUBS I seem to be able to get 3k ft of depth out of the main vessel, so my primary concern depth-wise is tether length and pass-throughs for lights tether electronics etc. What method have you guys found to work best?
Thanks,
Keaton
looking for advice on attempting a 1000ft capable ROV
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Keaton Hare
- Posts: 4
- Joined: Mar 12th, 2023, 8:42 pm
Re: looking for advice on attempting a 1000ft capable ROV
Remember Mr. Newton. That 150 cu ft tank is really heavy, and will take alot of thrust to get moving, and alot again to stop, turn, etc.
I bought 3/8" wall, 8" dia, 4' long aluminum pipe from onlinemetals.com , cut and welded rings on either end. Then i used a dished aluminum end cap for the back end, with all my penetrators going through, and a 1/2" wall 8" acrylic hemisphere i had custom-blown from https://plastic-domes-spheres.com/ . My thruster ESC heat sinks were reshaped and are spring-pressed against the inside curve of the aluminum pipe, keeping them cool. I have two more pipes with 12vdc 10ah SLA batteries inside, series to 24v, pararell to 200ah. I am in the process of building new packs with Li-iron-phosphate batteries. Since my ROV is the size of a 10 cu ft chest freezer, i used brushless drills (handles cut off, body filled with mineral oil) turning 8" symmetrical aluminum ducted props as thrusters. Bearings are replaced with ceramic, stator/magnets coated with thinned epoxy resin.
I put a 78x optical zoom Panasonic SDR-T55 camcorder (used on eBay for aprox $50) on a pan-tilt gimbal inside the dome. I use a servo to move the zoom toggle. The composite video out goes to an 8-camera security-system DVR board inside the WTC (water-tight-container). That is connected to an ethernet switch, which is then connected to the eKL ethernet over coax unit. The ROV controller is also connected through the switch. I potted cheap $16 Eachine FPV microcams in clear casting epoxy, they mount externally and give me views in all directions.
I built two 9-dof manipulators (driven by regular metal-gear servos filled with mineral oil to keep the water out while taking the pressure at depth) so i could grab stuff. Because one camera gives no depth perception, i have microcams mounted on each manipulator's wrist, so I can look back and forth between screens and judge grab angles. Inside the dark pontoon boat cabin i have a cheap $100 1080p led projector displaying the 8 camera feeds onto a 120" screen.
I have a homemade headtracker on a headband so when i move my head, the Panasonic camera follows my head movements. Two Virpil Constellation Alpha joysticks (3D printed and DIY) connected to multi-axis gimbals allow control of the manipulators. The joysticks are suspended from the ceiling by dacron line with counterweights to reduce arm fatigue.
My original control interface was a Raspberry Pi 3B with a Pixhawk controller (Blue Robotics), but i am in the process of upgrading to their new Navigator Flight Controller.
I bought 3/8" wall, 8" dia, 4' long aluminum pipe from onlinemetals.com , cut and welded rings on either end. Then i used a dished aluminum end cap for the back end, with all my penetrators going through, and a 1/2" wall 8" acrylic hemisphere i had custom-blown from https://plastic-domes-spheres.com/ . My thruster ESC heat sinks were reshaped and are spring-pressed against the inside curve of the aluminum pipe, keeping them cool. I have two more pipes with 12vdc 10ah SLA batteries inside, series to 24v, pararell to 200ah. I am in the process of building new packs with Li-iron-phosphate batteries. Since my ROV is the size of a 10 cu ft chest freezer, i used brushless drills (handles cut off, body filled with mineral oil) turning 8" symmetrical aluminum ducted props as thrusters. Bearings are replaced with ceramic, stator/magnets coated with thinned epoxy resin.
I put a 78x optical zoom Panasonic SDR-T55 camcorder (used on eBay for aprox $50) on a pan-tilt gimbal inside the dome. I use a servo to move the zoom toggle. The composite video out goes to an 8-camera security-system DVR board inside the WTC (water-tight-container). That is connected to an ethernet switch, which is then connected to the eKL ethernet over coax unit. The ROV controller is also connected through the switch. I potted cheap $16 Eachine FPV microcams in clear casting epoxy, they mount externally and give me views in all directions.
I built two 9-dof manipulators (driven by regular metal-gear servos filled with mineral oil to keep the water out while taking the pressure at depth) so i could grab stuff. Because one camera gives no depth perception, i have microcams mounted on each manipulator's wrist, so I can look back and forth between screens and judge grab angles. Inside the dark pontoon boat cabin i have a cheap $100 1080p led projector displaying the 8 camera feeds onto a 120" screen.
I have a homemade headtracker on a headband so when i move my head, the Panasonic camera follows my head movements. Two Virpil Constellation Alpha joysticks (3D printed and DIY) connected to multi-axis gimbals allow control of the manipulators. The joysticks are suspended from the ceiling by dacron line with counterweights to reduce arm fatigue.
My original control interface was a Raspberry Pi 3B with a Pixhawk controller (Blue Robotics), but i am in the process of upgrading to their new Navigator Flight Controller.
Re: looking for advice on attempting a 1000ft capable ROV
Hey Oddmar - would you share some pics of your build? It sounds interesting.
I've taken a similar path in that I use 125mm dia aluminium tube to house the electronics (approx 300mm in length) with custom blown 6mm acrylic dome. I made up flanges for each end that are self sealing and used epoxy glue to attach them the flanges have a large o-ring seal for both the end plate and dome.
The Li Ion battery is housed in a similar but smaller dia housing.
I currently have about 200m of neutral buoyancy tether cable to play with but will be upgrading or build a new unit with fibre optic
My rig is rated to 600m.
I've taken a similar path in that I use 125mm dia aluminium tube to house the electronics (approx 300mm in length) with custom blown 6mm acrylic dome. I made up flanges for each end that are self sealing and used epoxy glue to attach them the flanges have a large o-ring seal for both the end plate and dome.
The Li Ion battery is housed in a similar but smaller dia housing.
I currently have about 200m of neutral buoyancy tether cable to play with but will be upgrading or build a new unit with fibre optic
My rig is rated to 600m.