Subject:
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Re: 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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Sat, 28 Apr 2007 03:02:29 GMT
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Viewed:
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18786 times
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In lugnet.robotics.nxt, Brian Davis wrote:
> In lugnet.robotics.nxt, Edwin Pilobello wrote:
>
> > 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.
>
> 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 idea of wires (where exact values can be wired in).
>
> > 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
>
> What do you mean by percentages here? By "readings recorded off the Move block"
> I would think you mean the degree readings in the feedback pane of the
> configuration panel... but those are pure numbers. Are you saying the inside
> wheel odometry reading is some percentage of the outer wheel odometry reading?
>
> > Vindication!
>
> Or, perhaps something else was going on with the students trials. For instance,
> are all of their data explainable by repeating readings? This is another test
> they could do, I'd think. For that matter, they could try to combine their
> datasets to get better results and identify outliers better.
I'm using terms of my own making. These are terms that seem to work with 10 - 12
year olds. By "dominant" I mean the wheel which measures the duration specified
in a turn. Sometimes I use the term "outside wheel".
For example, a duration of 1000 degrees with the slider closer to the C motor
will make the B motor "dominant". In other words, B would be the outside wheel.
C covers a distance equal to a percentage of 1000 degrees.
At the moment, the steering slider is still a novelty. When they're ready for
fine tuning, then I'll introduce data wires.
In the classroom, with a grid of 9x9 floor tiles, the physical activity seemed
appropriate for all four teams. The floor was marked with masking tape where
the dominant wheel stopped. On my dinner table, I ran the motors and recording
the degree readings off the feedback panel. I actually used 1000 degrees for
the duration. One tick off "0" averaged 977 degrees on the inside wheel and so
on and so on.
I moved the decimal point one place to the left to get a percentage.
I'm actually going to conduct this activity again with another class next week.
I'll report after that.
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Message has 1 Reply:
 | | RE: Classroom experiments gone awry
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| Your results are not at all what I intuitively expect. From your previous posts, I think the "turn ratio" settings you've used range from 0 to +100 in steps of 10. The following table is what I expected. Turn Inner Expected Observed Ratio Wheel (...) (18 years ago, 28-Apr-07, to lugnet.robotics.nxt)
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Message is in Reply To:
| | 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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