Why autonomous gliders are the hot new ocean technology
This month's edition of Spectrum contains a wonderful article Erico put together about a subject near and dear to my heart: gliders. Gliders are a type of autonomous underwater vehicle (AUV) that is driven by a variable buoyancy system instead of a traditional propeller.
This diagram (which you'll also see in the Spectrum article) shows how the glider uses a variable buoyancy system and actuated battery packs to glide through the ocean
Back in February I talked about a thermally-driven prototype that Webb Research has developed, but the big news right now is how traditional gliders are being snapped up by defense contracting companies iRobot, Teledyne, and of course, Bluefin. (disclaimer for those who didn't read the About section: I work for Bluefin, but even if I didn't I'd think glider technology in general is just, as they say, the bee's knees) The major impetus for acquiring this IP lately is a big Navy contract that's due to be awarded soon. Erico's article describes the differences between the different glider designs and some of the challenges in meeting the next generation of evaluation and procurement system requirements:
Up to this point, however, AUVs have been a cottage industry. â''The challenge now is making the transition from this very hands-on build-and-test kind of manufacturing to commercial production mode,â'' says Tom Curtin.
And even though their original designs are alike, their makers boast of unique capabilities. iRobot claims the Seaglider has the longest range and battery lifetime, being the first glider to complete a mission of more than 3750 kilometers and lasting six months. Bluefin, which is also supplying an offshore oil and gas contractor, says the Spray glider can go about 50 percent deeperâ''1500 metersâ''than its competitors and has more durable sensors. And Teledyne says the Slocum's rudder gives it better shallow-water maneuverability and that a new system that harvests energy from temperature variations in the water could allow its gliders to stay at sea for years at a time.
Though most of my time in the working world has been spent on powerful propeller-driven AUVs, I can't help but admire the simplicity and elegance of the glider design. It has a very different history from traditional AUVs; AUV technology spun off of towed array systems for surveying -- a short-duration, high-power system -- whereas the gliders spun off of ocean monitoring float technology -- long-duration, low-power. With these very different pedigrees, it's interesting to watch them converge now as supplementary parts of the Navy's existing Unmanned Underwater Vehicle programs.