Overview

A remotely operated vehicle (ROV) is used to explore underwater environments. For example, they were used extensively during the BP oil spill since the wellhead was too deep for divers. I built a simple ROV for the challenge of it, and to explore areas without getting into scuba gear. Below is some video of what I've seen and tips on how you could build your own. 

 This video clip was taken on a ROV dive around Monterey Bay, California. You can see a surprised otter, fish and other wildlife. The water is quite cold, and it's therefore nice to be able to see the wildlife without getting cold doing a scuba dive 
 

 
 Summary of the ROV: A video camera with lights mounted on a compact, powerful thruster system.  Maximum depth: 100 ft (tested to 60 ft so far).  Relative inexpensive to build since most of the components came from local hardware and electronic stores. 

The driver sits on the surface and uses controls to steer.  There is a camera in the middle of the ROV that transmits the video up the tether to the surface (where there is a viewing screen).  














 
 
Structure: PVC pipes and joints were used to construct a simple frame.  Plumbing adapters and zipties were used to mount the various elements.  

Small holes are drilled in many PVC pieces to help drainage and remove air pockets.  

The case is placed on the top due to buoyancy.   


Camera System
: Built using a board camera with video baluns (from supercircuits.com) in a waterproof enclosure (useful tips on waterproofing here).  This configuration allows longer range (up to 150 feet) with a re-usable television and the abilty to upgrade the camera as needed. Signal can be split to go to a second camera (camcorder, etc.). 

Selected camera is color in sufficient light, but switches to black/white in low light (and can see in infrared)

Video can be recorded with an adapter and DVR or a video camera with input (like this one).  In my configuration, recording is done on my laptop (have an adapter and software from Elgato) 

Camera and thrusters need to be on separate 12V batteries (otherwise interference). Read more about how the camera system was built here.

Lighting: LED spotlight and infrared spotlight were waterproofed using the same process as the camera. 




 
 
 A viewing port to help see the television in strong daylight was created with corrugated plastic.

The television was mounted on a camera tripod to make viewing easier.

Having a television viewer is better than a laptop, but in a more-affluent world I would use video goggles.

 

 
Thrusters
:  Thrusters are 750 gph bilge pumps with propellers adapted.  There are four thrusters total (2 for up/down, 1 for left side, 1 for right side).  Left/right thrusters were placed within housings to direct the thrust better and to protect the propellers from tangling.

There was a lot of excess wiring since I wanted flexibility to re-configure the thruster system on different structures.







 


 Control:  Control system was made by using a Vellman K8023 10 Channel 2 Wire Remote Control Kit and relays

 Control system was housed in a Otter waterpoof box  (holes drilled in one side, wires run inside, and then sealed with more than an inch of potting epoxy).  In retrospect, I should have gotten the clear box (easier to inspect). I should have also sealed the wires like this.


I used simple toggle switches.  I think they're called (on)-off - (on) switches for the thrusters.

Having the right and left thrusters on different switches (as opposed to a single joystick), is good since it allows you to spin better (one thruster full forward, the other full back).   Basically, you drive the ROV like a tank.

I have two up/down thrusters that are on the same switch (so didn't need to use an additional channel on it).(picture shows before potting epoxy was used to seal the holes)




 
 
Power:  the thrusters and lights are powered by a 12V battery on the surface.  The camera system is powered by another 12V battery which is also on the surface. 

Ten AA batteries were used to power the control system on-board (the control system was losing power when thrusters engaged), and provide ballast.


 
 


Tether: 100 ft long, with two 14-gauge wires provide power, one ethernet for the camera, and two 18-gauge control wires.

Tethers are annoying. I wish I could get a fiber optic system with on-board batteries.

The next time I do something like this, I will buy a custom neutrally buoyant tether from Storm Cables, Falmat or South Bay.







 
 To give the tether buoyancy, I bought some fishing floats from Memphis Net and Twine.
and spaced them evenly along the tether so that the line was neutrally buoyant (about every 5 feet). 

I bought the FL250.  I should have bought smaller floats so the gaps between them were smaller (there was some sagging of the line). 

You can also buy custom-made, neutrally buoyant tethers. 

 
 Completely disassembles for easy transport (whole system fits in a single piece of carry-on luggage).

No screwdrivers or other tools needed for re-assembly.




 

Taking it for a test drive in the Mekong River (near Luang Prabang, Laos).

The tether wasn't fully assembled, so I fed it out while Bryce drove. 



Not yet implemented:  
  • Direction/Compass: exploring options here.  I wish I had incorporated these, since it's difficult to navigate underwater without knowing depth and direction. The trick is to use something called an OSD to overlay the information on depth and other information (see OSD here). Here is a possible depth gauge. 
  • Claw/Manipulator: Grip from Trossen Robotics or Jameco. Powered by a waterproofed gearhead motor. 

Please email greennomad  at gmail.com with any questions you might have about this.  

Additional References





















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