The Ulithi ROV belongs to a class of remotely operated underwater vehicles sometimes nicknamed “flying eyeballs.” It is essentially a steerable underwater closed-circuit video camera that allows a pilot on the surface to see on TV monitors what the ROV’s cameras are “seeing” under water and to “fly” the vehicle around by remote control to look at different things.
The Ulithi ROV system
The ROV isn’t just one object, but a complete system of interacting objects. The Ulithi ROV system includes these four major components:
- The ROV itself goes under water and consists of a pair of GoPro Hero2 cameras in custom-machined aluminum pressure-proof housings mounted to a plastic frame along with four SeaBotix thrusters for propulsion. There are high-powered LED video lights to bring out true colors in the dim blue light found at great depths. They also allow the ROV to operate at night. A separate waterproof pressure canister houses the electronics, including aParallax Propeller microcontroller (essentially a tiny computer that serves as the ROV’s brain), Pololu TReX motor controllers, assorted sensors, and other electrical components.
- The Pilot’s Control Console remains on the surface with the human pilot. It features two TV monitors (one for each of the ROV’s cameras). It also has joysticks and buttons used to control the ROV’s movements and some of its accessories, like the cameras and video lights.
- The Tether is basically a communication cable that carries the pilot’s remote-control commands from the surface down to the ROV and relays live video from the ROV’s cameras back to TV monitors sitting in front of the pilot on the surface. The tether is 170 meters (about 560 feet) long and is stored on a big spool with a hand crank to reel it back in.
- The battery box contains two 12-volt SLA batteries and is filled with vegetable oil for pressure compensation. These batteries supply power to the ROV through a 10 meter long cable. This gives the ROV some flexibilty to move around independent of the heavy batteries, but is still close enough to receive most of the battery power without excessive power loss through long wires. The battery box dangles near the end of the tether, where it is attached 10 meters from the ROV.
You can see footage of the ROV’s dives here