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Subject: 
RE: Classroom experiments gone awry
Newsgroups: 
lugnet.robotics.nxt
Date: 
Sat, 28 Apr 2007 17:43:57 GMT
Reply-To: 
<dickswan@STOPSPAMMERSsbcglobal.net>
Viewed: 
19127 times
  
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   Inner Wheel   Inner Wheel
Setting         Ratio     Movement     Movement      Comments

   0.      0    +100        1000        1000      Straight Line
   1.    +10     +80         800         977
   2.    +20     +60         600         935
   3.    +30     +40         400         895
   4.    +40     +20         200         862
   5.    +50    stop           0         829      Inner wheel stopped
   6.    +60     -20        -200         788
   7.    +70     -40        -400         693
   8.    +80     -60        -600         581
   9.    +90     -80        -800         158
  10.   +100    -100       -1000       -1029      Turns in place

The third column is the speed or encoder percentage for the inner wheel
that I would expect to see vs the the outer wheel. Only the two extreme
values actually fit this!

Above is based on my understanding of how the "steering slider" works. I
could be wrong. I thought it worked as follows:
1. Setting   '0' corresponds to straight line.
2. Setting  '50' corresponds to inner wheel stopped.
3. Setting '100' corresponds to turning in place.
I've assumed that settings in between the above three points should be
linearly proportional to the three extremes.

Your observations are no where near what I would have expected. Can
anyone explain what's wrong with my assumptions? Also see my post at
http://forums.nxtasy.org/index.php?showtopic=1115 where I also did some
experiments.



Message has 1 Reply:
  Re: Classroom experiments gone awry
 
(...) Steering under NXT-G is... not exactly intuitive. I tried some experiments a whle back, but I never even tried to play with the steering slider because I had no patience for rough approximations (like trying to see if I had moved the slider (...) (18 years ago, 29-Apr-07, to lugnet.robotics.nxt)

Message is in Reply To:
  Re: Classroom experiments gone awry
 
(...) 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 (...) (18 years ago, 28-Apr-07, to lugnet.robotics.nxt)

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