Thursday, August 23, 2012

AUV Boot Camp - Part 1

This past week, the CSHEL team headed up to New Castle, New Hampshire for AUV Boot Camp, a weeklong workshop where scientists and professionals from around the world gather to develop and improve AUV methods. As an intern, I didn't know what to expect besides that I would be surrounded by a lot of really experienced people interconnected by their interest and use of autonomous underwater vehicles. In lieu of my very limited knowledge of AUVs, I knew this would be the perfect opportunity for me to observe marine scientists and engineers in their element and learn a bit more about AUVs along the way.

Our AUV sitting outside the Boot Camp tent at the UNH pier.

Our first day consisted of some general discussion regarding the upcoming week. We ran through some NOAA documents that specified proper methods for creating navigation-grade hydrographic maps, since that is one of our primary objectives this week. It was really interesting to listen to this group of 20 some-odd people bounce ideas off each other, each contributing things from their respective skill set. We heard from Brian Calder, CCOM research associate professor, about uncertainty for multi beam echo sounders (which I learned is abbreviated as MBES) for parameters like depth, sound speed, and others. It is surprising how much uncertainty there is in most of the factors we're dealing with. Therefore it takes some effort to minimize that variability and acknowledge it during data processing.

Brian leading a discussion on MBES uncertainty.

The day ended with a delicious cookout, highlighted by copious amounts of lobster and a noteworthy sunset.

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Day two brought our first offshore campaign in the Portsmouth Harbor and beyond. Two small groups of participants spent a half day each on the R/V Orion with "Tom-squared", as I have heard people here fondly refer to the two same-named boat captains as. In continuation of the previous day's discussions, the purpose of the mission was a patch test to resolve the latency between the two transducers.  

Carter deploying the AUV.

Trevor working onboard.

The rest of us back onshore split into groups and brainstormed the contributing sensors and environmental variables that make up horizontal or vertical uncertainty. My group, assigned to horizontal uncertainty, made a pretty good list. For sensors, you have the GPS, INS, DVL, depth and temperature sensors, Geoswath (bathymetric sensor), and sound velocimeter. Environmentally, the sea state and swell action, tides, seabed type, sound speed and temperature variation, bathymetric pressure, and others can all cause uncertainty. As I listened, I realized that basically every sensor and environmental variable can cause vertical uncertainty, so quantifying those adjustments are essential to an accurate data set. After discussion, each group presented their notes and as a whole, we brainstormed how these variables can be kept to a minimum.

On day three, Justin and I rose early to head out on the boat with Adam Skarke, a previous PhD candidate at UD now with NOAA's Office of Exploration. My sleepiness melted away as we puttered over the smooth, still water, enjoying the morning sun and perfect conditions. Our three hour campaign had a long lawnmower pattern with three short lines cutting perpendicularly across, for the purpose of observing navigational drift. This drift occurs because the AUV loses its connection to a GPS once it submerges, and then must utilize a different positioning system. Once the vehicle returned, we sent it out again for a short mission to run a line 500 meters out and then back on the same line. Unfortunately, it aborted its mission as the single battery had dropped to only 10%. However, our trip was still successful and we returned to the shore with good data and fresh sunburns.

We deployed a Seabird CTD with two attached Castaway CTDs. We will compare the data from the Castaways to the Seabird later.

We've done a lot so far, but we have much more ahead. Stay tuned for the second half of AUV Boot Camp! 

Danielle Ferraro

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