Subject:
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Rotaion Sensor Sampling Speed?
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Newsgroups:
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lugnet.robotics
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Date:
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Thu, 14 Oct 1999 16:40:18 GMT
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Viewed:
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606 times
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Hi all,
I'm putting together a mazebot for Mindfest, and ran into a
bit of a funny with the rotation sensor. I THINK it has to
do with the sample speed, but I'm not positive.
I'm using pbFORTH and sampling the rotation sensor in a tight
loop. The idea is to make it go to a certain count and back
again a number of times to see if I lose counts. If I can't
accurately figure out where I am, the maze problem is REALLY
hard...
I'm driving a suspended light sensor on a rack with a micromotor
and an 8 tooth gear. The axle of the micromotor drives the
gear and goes right through to the rotation sensor. The assembly
is solid, but does vibrate a bit, and I think this is where
my problem is.
Since pbFORTH can sample VERY quickly,I'm wondering if the
slow turning rotation sensor and the vibrations might cause
some "jumping" of the values to the rotation sensor processing
code as it transitions through the steps.
If I run the gantry manually (smoothly) the problem goes away...
If I add some DELAY between samples, say 40-50 msec, the problem
goes away....
Anyone else noticed this if you are using rotation sensors and
smapling at very high speeds? This is probably only an issue with
custom firmware, but I'm curious to see if the micromotor to
the rotation sensor is a problem with regular Mindstorms firmware...
Cheers,
Ralph Hempel - P.Eng
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Check out pbFORTH for LEGO Mindstorms at:
<http://www.hempeldesigngroup.com/lego/pbFORTH>
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Reply to: rhempel at bmts dot com
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Message has 1 Reply:
 | | Re: Rotaion Sensor Sampling Speed?
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| Ralph, I don't know about the specific issues with pbForth, but this summer I was working on a large gear train (for a problem that we have recently "proven" is computationally intractable for the RCX) and dropped about 20 counts out of every 1,000 (...) (25 years ago, 14-Oct-99, to lugnet.robotics)
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