Subject:
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Classroom experiments gone awry
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Newsgroups:
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lugnet.robotics.nxt
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Date:
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Thu, 26 Apr 2007 19:53:45 GMT
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Viewed:
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17959 times
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Imagine a classroom with eight 13-year old boys, paired up with a laptop and the
standard NXT Edu robot. The 9x9 inch floor tiles made perfect for a little
experiment in derivation. Starting at a fixed point and heading, each team
marked where the dominant wheel stopped after 10 rotations for each "tick" on
the steering slider of the Move Block.
Two of the robots had their wheels flush to the hubs, while the other two
extended two lego units to the tips of the axles. The resulting plots on the
tile floor showed a nicely curved fabionacci sequence.
Question: What was the turn radius was for each of the "ticks" on the steering
slider? How did the distance between the wheels affect the results?
This should have been a fairly easy object lesson. It was, except something was
wrong. One team had 8 marks for 10 tries. Their 4 & 5 and 8 & 9 where exactly
the same. The other teams all had some anomally of some sort. They swore by
their diligence in following the procedures. How was this to be explained?
Fortunately, this teacher was saved by the bell.
I've conducted my own experiments for most of the night. I recorded the
readings off the Move block for the inside motor and averaged 9 sets of results.
0. 100.0% Straight
1. 97.7%
2. 93.5%
3. 89.5%
4. 86.2%
5. 82.9%
6. 78.8%
7. 69.3%
8. 58.1%
9. 15.8% Had a small negative value to start with
10.-102.9% Spin in place
I dd not get any of the aberrant readings the kids got. So, I've concluded that
they inadvertently repeated some settings and missed others.
Vindication!
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Message has 2 Replies:
 | | RE: Classroom experiments gone awry
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| I'm having trouble understanding the meaning of your results. What do the percentages mean? I'd also just like to check that you used the "run for 10 rotations" as duration with "next action" indicated as stop. What speed did you use for the (...) (18 years ago, 26-Apr-07, to lugnet.robotics.nxt)
| | | Re: Classroom experiments gone awry
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| (...) What do you mean by "dominant" here? And what is a "tick" on the steering slider equal to? I've done something similar to figure out the behavior with respect to the position of the steering slider, but this is a *great* place to introduce the (...) (18 years ago, 26-Apr-07, to lugnet.robotics.nxt)
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