Subject:
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Re: Advice on Rotation sensors and steering please.
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Newsgroups:
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lugnet.robotics
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Date:
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Thu, 21 Sep 2000 21:35:02 GMT
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Original-From:
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John Barnes <barnes@sensors.&antispam&com>
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Viewed:
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656 times
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I discovered, during the course of implementing a software interface
to the Lego rotation sensors on another hardware platform altogether
(not RCX) that there is a problem with the sensors themselves. They
suffer from the well known "between states" problem. I had written some
code which after some serious testing lost or gained counts. So I tried the
same test with the RCX and it loses counts too. I think it is the grey area
(excuse the pun) between one output level and the next, fooling the
analog input circuitry and the software state machine into interpreting the
values wrongly. I found that if you very very slowly move the sensor back and
forth right on the ragged edge between states you can accumulate phantom
counts.
In normal operation it is less likely, but I think it will happen. The critical
time seems to be when you stop and start rotation.
JB
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