Robots powered by the ocean itself

Two new robotic ‘gliders’ – autonomous underwater vehicles – will be put though their paces off the beaches of California next year.

Two new robotic ‘gliders’ – autonomous underwater vehicles – will be put though their paces off the beaches of Camp Pendelton, CA, from January 21 to February 7 next year.

First off, Webb Research of East Falmouth, MA will deploy its Slocum Glider during the exercise. The Slocum Glider uses a heat engine which draws energy from the ocean thermocline. The work required to change buoyancy results from heat flow from warm surface to cooler deep water, so the vehicle can cycle thousands of times between the surface and some programmed depth.

The long-range deep ocean glider is designed to cruise for five years in a vertical zig-zag from the surface to depths of about 5,000 feet and back. As it does so it measures salinity and temperature, plots currents and eddies, counts microscopic plants, and even records sounds like whale songs. An earlier battery powered model is used to study coastal waters up to 656 feet in depth for up to 30 days at a time.

The other robot – the University of Washington Applied Physics Laboratory’s Seaglider – is propelled by buoyancy control and wing lift to alternately dive and climb along slanting glide paths. It dead reckons underwater between GPS navigation fixes it obtains at the surface, and glides through a sequence of programmed waypoints.

Seaglider has enough range to cross an entire ocean basin in missions that last months, all the while diving and rising between the surface and waters as deep as 3500 feet. It can be launched and recovered manually from a small boat, and so doesn’t rely on ships for its deployment. Seaglider collects high resolution profiles of physical, chemical, and bio-optical properties of the ocean.

Both gliders were developed with support from the US Office of Naval Research (ONR). The ONR is interested in systems like Seaglider and the Slocum Glider because they offer the Navy and Marine Corps potential tools for collecting data about regions of the ocean necessary for mine countermeasures.