Cool Autonomous Robots Traversing our Oceans

Oceans cover 75% of the surface of the Earth and represent vast unexplored regions of our world.  That is changing rapidly as today there are over 400 autonomous robot submarines (ocean gliders) traveling under and across our oceans exploring and gathering data - sounds, temperatures, currents, images.

Excerpt from The Economist (full article):

Sea gliders are propelled by buoyancy engines. These are devices that pump oil in and out of an external bladder which, because it deflates when it is empty, means that the craft's density changes as well. This causes the glider to ascend or sink accordingly, but because it has wings some of that vertical force is translated into horizontal movement. Such movement is slow (the top speed of most gliders is about half a knot), but the process is extremely efficient. That means gliders can be sent on long missions. In 2009, for example, a glider called Scarlet Knight, operated by Rutgers University, in New Jersey, crossed the Atlantic on a single battery charge, though it took seven months to do so.

Image from Seaglider:

Other images from Google.

Some of the ocean gliders rise to the surface periodically and transmit their accumulated data to satellites, then resume their treks.  Many are battery powered but consume so little power that they can travel for thousands of miles before draining their energy reserves. Others have solar cells that allow them to periodically recharge at the surface and continue on their treks indefinitely.

Liquid Robotic's robots trek at the oceans' surfaces and use wavepower for propulsion.  One of these, PacX, just set a record, on Dec 6, 2012, of longest distance travelled by an unmanned vehicle (press release).  This from Liquid Robotic's website:

Wave motion is greatest at the water’s surface, decreasing rapidly with increasing depth. The Wave Glider’s unique two-part architecture exploits this difference in motion to provide forward thrust.

A rising wave lifts the Float, causing the tethered Sub to rise. The articulated wings on the Sub are pressed down and the upward motion of the Sub becomes an up-and-forward motion, in turn pulling the Float forward and off the wave. This causes the Sub to drop, the wings pivot up, and the Sub moves down-and-forward. This process is repeated again and again as long as there is wave motion on the surface, even the smallest amount.

This photo of a Waveglider is from Treehugger.

 A versatile platform, the Wave Glider is equipped with GPS and sophisticated computers for navigation and payload control, with satellite communication systems, and with state-of-the-art ocean sensors to monitor and measure the environment around it. The power needed to operate the sensors and computers is provided by solar panels.

More on the Wave Gliders (from Singularity University):

Dubbed Wave Gliders, the surfboard-sized robots have titanium-framed fiberglass bodies that encapsulate terabytes of flash memory, a dual-core ARM processor that runs on open Linux software, a GPS unit, a battery pack and wireless and satellite communications with which to receive commands and beam back data.