Subject:
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Re: Creativity
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Newsgroups:
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lugnet.robotics.rcx
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Date:
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Wed, 1 Aug 2001 19:56:58 GMT
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Viewed:
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1687 times
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IHi Roger,
I have been meaning to make this available on the web, but I will try to
give a brief explanation in advance. The fuzzy logic line follower that I
have worked on also uses two light sensors and rack&pinion steering, but
follows a line that has a black/white gradient at the edges. I have found
that the light sensor will respond nearly linearly, with good resolution to
a coarse gradient (you can create this type of gradient using the spray can
in a paint program, Just move the cursor across the screen slow then faster
and faster, I got the idea while looking at a 2-dimensinal Aztec bar code).
Creating the gradient in this way takes a great deal of trial and error. A
friend of mine is a graphic designer and was able to produce tracks with
half inch lines and consistent gradients at the edges on 7’x7’ sheets of
paper quite easily.
Using a Fuzzy controller with this system has the benefit of smoothing out
the steering by filtering out the amplitude of the robot as it tracks the
line. The fuzzy rules are set up to take into account which side of the
line the bot is on, the difference between the two sensors and an estimate
of the curvature of the line at any given moment (this was particularly hard
to achieve, but is accomplished by using the known steepness of the gradient
and then checking the difference between the light sensors continuously as
the bot tracks. It does not give the true slope but works for the purpose).
I realize this may be a little much for a simple line follower, but the
result is a very smooth tracking robot. Plus I hope to use the gradient in
an optical encoder wheel.
Play Well!
JL
n lugnet.robotics.rcx, Roger Glassey writes:
> Hi Jeff,
> Tell me more about your fuzzy logic line follower.
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Message is in Reply To:
 | | Re: Creativity
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| Hi Jeff, Tell me more about your fuzzy logic line follower. My line follower was always losing track of which side of the line it is on and turning in the wrong direction. It would then stop and use an expanding sweep based on the ideas of Dave (...) (23 years ago, 31-Jul-01, to lugnet.robotics.rcx)
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