Hard to believe my first little lego baby (read: blue rectangular accelerometer unit) was deployed just about a week ago! I thought I would take a minute to talk a little more about the accelerometers themselves and some of the things we hope to decipher from them. Acceleration in short is the rate at which an object (or seal head) changes speed – think of that feeling as you press the gas pedal down on your car as you move from 0 to 60 mph where you only feel the change in speed, rather than the full force of 60 mph (unless you have no windscreen). Anyways, we are more or less using these tiny devices to look at these changes in position of the individual’s head relative to this force of movement to derive behaviour.
How you ask? Well, its everyone’s favorite…MATH(S) TIME! Sampling at a rate of, say, 20 Hertz (s-1) means that we are taking measures of acceleration at the individuals head every 0.05 seconds, or 20 samples per second. Now, we do this in not one, but three axes to get all three dimensions of movement, or 60 data points per second. Now, take that and do some fun unit conversions from minutes to hours to days over an 8 day period and you get…A LOT of data (double points if you actually do the math(s)! I will send you a consolation prize…probably).
We also have to take into account the effects of gravity – which can tell us how the individual was oriented. For example, if an animal is laying with its head to the side, we might see a steady bit of acceleration in the Y-axis. The acceleration due to gravity (~9.8 m/s2 or 1g) keeps us all firmly planted on the ground – so no seals in space (though I could see a Muppets spin off of “SEALS IN SPAAAACCCEE!”).
Why did I just drag you through that math(s) and physics lesson? Well, mostly because I think it’s a cool application of all that stuff you learned in school and had no realistic context for. But also for the fun and excitement that….
The first accelerometer is BACK safe and sound!
After a good bit of downloading of data – those of you playing the home math(s) game know what I’m talking about painfully well – and a few hours of un-condensing the data, I present to you a 5 minute clip in the graph above of the day in the life of a seal! Cool, huh? Now, this is fresh off the tag and hasn’t really been corrected for anything at all, but I think it shows some promise for the rest of my PhD (Yay, data! So, so, so very much of it…).
Now since we have been spending most of every day watching these animals, its now up to me to match up the acceleration signals with the video footage and try to teach a machine learning program to pick out signatures of behaviour and streamline the process so we can answer even more questions on behaviour.
First order of business when I return is to purchase an industrial size coffee maker for my personal use in the lab (former lab mates read: ‘The Thesis Maker’). Lots of programming and coding to come! Now back to observations and mayhem. And by mayhem, I mean backing up data.