Getting better aquainted with the Stretch Sensors

As mentioned in a previous post, I now have a stretch sensor by Images in my possession. Though I was first a bit skeptical I am beginning to see more and more ways of using this. I sort of had a hunch that the relationship between stretch and resistance might not be linear (yeah admitted, nothing strange in that, I would be more surprised *where* there a linear relationship.)

I am a visual person and I need to see things to understand them, so I made these graphs:

Stretched to 125 % of original length.

Stretched to 150 %

Stretched to 175 %

Stretched to 112.5 %, 125 %, 137.5 %, 150 %, 162,5 %, and 175%

Stretched with incrementions of 6.25 %

 

Due to the fact that I am lazy the graphs might be a bit confusing to read. The x-axis represents time and the white vertical lines represent seconds (I just double checked my math and the white lines are more like half seconds - maybe I will redo these if I get around to it. However you still get the generally picture). The y-axis measure the change in resistance. The light gray area is the resistance of the sensor. I did not add units, as the interesting part is the relative change and that is all I measured. 

The fact that the signal is non-linear can, with some tinkering, be used as a bonus. The resolution in the first couple percent of stretch is quite high - so if I where to use two stretch sensors simultaneously but in opposite phase (if one is loose, the other one is stretched) I should be able to maximize the resolution available :-)

off topic --> Skiing & The Acceleration of Time

Another thing I was looking into was sports. I just have this vague memory of seeing some Austrian guy winning the slalom world championship in the 50's even though he had to track back for a second as he almost missed a gate.

As we all know, that does not really happen anymore today. (Missing gates: yes. Missing gates, backtracking and winning: nope.)

So I got myself the finishing times of the best 6 skiers in all World Championship and Olympic slalom events. Then I plotted some graphs. I found the results quite fascinating. I will show all graphs first with regular scales and then with logarithmic scales.

• Graph one shows the difference in time between first and second
• Graph two shows the difference in time between the first and the average of the first 6 (I included the first in this average, which is a bit silly, I just realized, but oh well...)
• Graph three shows the difference between the first and the sixth person to cross the finish

Whats really interesting here, IMHO is that these graphs don't look like some random development, governed by society and technological development. These graphs look more like something following a natural law.

I find the level of correlation quite spooky, to be honest. Take a look at these logarithmic charts...

The numbers in the graph is difference in time, measured in seconds.

Anyway. I would love to hear what other people have to say to the things I'm posting. I know people are reading this, and there is a comment function. Feel free to use it :-)