August 27, 2010

*Special* "Datalogging" a rolling tube

Hell0 everyone,

I'm here with a special presentation of my own!  I have created a datalog situation, where I roll in a pipe (or tube/barrel), and the NXT (with a HiTechnic Accelerometer sensor on it) records the 3 different axis.

[caption id="attachment_384" align="alignleft" width="754" caption="(click to enlarge)"][/caption]

There is lots of info we can pick up from this graph.  First, we can see that, the X and Z axis are going crazy, but the Y axis is staying, relatively, in the same spot.  Why?  Because I positioned my NXT upwards (meaning, I had the accelerometer sensor facing forward, so the Y axis was pointing left/right [ends of the barrel]), so the Y axis didn't show much data, because it wasn't used very much in this test.  But, if I had positioned my NXT, so that the Accelerometer sensor was pointing left/right (ends of barrel), the Y axis would show more change. We can also pick up from this "Rolling......" segment if the fact that each spike, is 1 revolution for the barrel. So, if you count the X spikes, you will see that there are 14 spikes. So, 14 spikes = 14 revolutions, which you will see in the video.

The second thing we can pick up from this graph, we can see the highest (or, in the X axis state, lowest) point in the axis lines: Z: 459 (~2.25 G's), X: -444 (~-2.25 G's), Y: 332 (~1.5 G's).

Third thing, right after the "Rolling......" part of the graph, you see a bunch of jumps and spikes in the Z axis.  That's because, if you see the video, you will see that I ran down a hill, and into some rocks, so those spikes, are the bumpy rocks and the hill.

Last thing you can pick up from this graph, you can see different jumps in the graph, and therefore, know what's happening.  For instance: the constant up and down movements made by the X and Z axis in the middle of the graph, are made from me rolling.  And, near the end, where the Z and X axis curve a bit, and the Y axis jumps, that's where, at the end of the "ride", it went slowly from upside-down to rightside-up.

I have also calculated the speed at which the barrel was going: ~10ft/s. The barrel is 9ft in circumference, and the time it took to go 1 revolution was 0.9, so, it was going about (~) 10ft/s.

Here is a little 30 second video that shows how I made the data (I started the program around 0:12):

Thanks for reading!



  1. Could you include the part where you puke,cause that looked nousiating.

  2. Lol...First of all, you're sick. I'm sorry, but if you want to see me puke (which I did NOT puke), you are sick. Second...why?! lol :-)

  3. What a write!! Very informative also easy to understand. Looking for more such comments!! Do you have a twitter?
    I recommended it on digg. The only thing that it's missing is a bit of speed, the pictures are appearing slowly. Anyway thank you for this information.