Subject:
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Re: Following the Line Follower
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Newsgroups:
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lugnet.robotics
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Date:
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Fri, 27 Sep 2002 16:43:32 GMT
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Original-From:
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Steve Baker <sjbaker1@airmail&saynotospam&.net>
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Reply-To:
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(sjbaker1@)StopSpammers(airmail.net)
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Viewed:
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1371 times
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It might be worth trying to increase the area that the light sensor is seeing
by putting some kind of a lens in front of it.
If the sensor could see (say) a roughly circular region 3 centimeters across
then numbers you'd read between the 'white' and 'black' readings would be
a rough estimate of the relative areas of black and white within that 3cm
patch. That in turn is a reasonable estimate of your distance from the
edge of the line. When the brightness is exactly halfway between 'black'
and 'white' readings, you are exactly over the edge - when it's lighter,
than you are 'outside' and when it's darker, you are 'inside'.
In a sense, fuzzing the image that the sensor sees damps out the oscillations
in the robot's motion that were evident in the jaggy lines that were produced
by the pen-plotting experiment - removing those high accelerations means you
can drive faster.
If you know the distance from the edge of the line, you can do things like
continuing to drive straight so long as the distance to the edge is
*decreasing* and to turn either left or right if the distance is *increasing*.
However, you could get even smarter and change your turn rate depending on
the rate that the distance is changing. In this way, the robot could (in
principle) figure out the instantaneous radius of the line and steer with
precisely that turn rate.
Of course you'll have to be careful not to increase the width of the visible
region beyond the width of the line you are following.
> I'm sure you can do even better with two sensors.
Sure - more information can only help.
----------------------------- Steve Baker -------------------------------
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URLs : http://www.sjbaker.org
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Message is in Reply To:
 | | Re: Following the Line Follower
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| (...) You can improve the single sensor program considerably by having it go straight when it sees an intermediate value, which is what it would see when it's right on the edge. So, you have two cutoffs, LOW and HIGH. If light value is less than (...) (22 years ago, 27-Sep-02, to lugnet.robotics)
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