Servo - July 2010

Robytes by Jeff and Jenn Eckert

ROVs Aid BP

The Maxximum ROV from Oceaneering International.

It has been widely reported that robotic submarines were deployed within hours of the BP oil disaster, but details were sketchy. Were they Navy subs? Specially modified UAVs? Well, it turns out that Oceaneering International, Inc. ( www.oceaneering.com), has been offering a variety of products and services geared toward offshore oil exploration and production for years. Included is a line of remotely operated vehicles, eight of which were attempting to awaken the well’s blowout valve as of this writing. And we’re not talking about dainty little tadpoles.

Oceaneering’s Maxximum® model is a dual-manipulator, 300 HP slogger that — with its enhanced thruster configuration — offers nearly a ton and a half of center lift capacity and forward pivoted bollard lift greater than 1,800 lb. It also sports microprocessor-based telemetry and a direct fiber optic link to the console, providing a transmission path for video (eight channels) and data signals. The standard unit is rated for depths of 10,000 ft. Weighing in at 10,750 lb in air, it can carry a payload of up to 1,100 lb. For more indepth coverage on the ROVs used in this effort, check out the article on page 55 of this issue.

motion in an absolute sense, as it actually does suck a little energy out of the environment. But the Sounding Oceanographic Lagrangrian Observer Thermal RECharging (SOLO-TREC) autonomous underwater vehicle uses a clever thermal recharging engine that draws its energy from temperature differences found at different ocean depths.

In a joint effort by NASA’s Jet Propulsion Lab ( jpl.nasa.gov) and the Scripps Institution of Oceanography ( scripps.ucsd.edu), the UAV has already completed more than 300 dives to depths of up to 500 m (1,640 ft). The secret is a set of 10 external tubes that are filled with a waxy phase-change material that alternately expands and melts in warm water, and solidifies and shrinks in cold. This puts pressure on an oil reservoir that drives a hydraulic motor, and the motor produces juice to recharge the sub’s batteries. You get about 1.7 watt-hours ( 6,100 joules) per dive which is enough to run the vehicle’s instruments, communications equipment, a GPS unit, and the buoyancy-control pump. No, it doesn’t produce enough to provide horizontal propulsion, but what do you want for nothing? As you read this, SOLO-TREC has been redeployed on an extended mission that is planned to last months, if not years.