Subject:
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Re: line following
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Newsgroups:
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lugnet.robotics.handyboard
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Date:
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Wed, 16 Apr 1997 18:19:37 GMT
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Original-From:
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rabbit <G-WEBB@UX1.CSO.UIUC.EDUspamless>
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Viewed:
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1460 times
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> On Apr 14, 11:37pm, Rajesh Gottlieb wrote:
> This could be extended to use more sensors...for example, four sensors,
> with "normal" being the middle two black and the outer two white.
> Make up a truth table of the 16 possible conditions of the four sensors
> and decide what to do in each case - veer right, veer left, keep going
> straight, or stop.
I did something like this in an early computer engineering
course. The requirements are exactly the same ie. follow a black line.
What Chris said is a good start but you should also consider the case
when the turn is too sharp; In this case your robot will go from a
normal type condition of say the two middle sensors 'seeing' black to all
four sensors seeing white very quickly. True, you will go through some
valid contitions along the way but only a robot that can react *very*
quickly will work. The solution is to keep a memory of the last known
position of the black tape and have the robot turn in that direction
until it finds it again.
In my class all we used were logic gates to impliment this line
following robot (using flip flops as memory) so it should be very easy to
impliment using a microcontroller like the handyboard. I would recomend
using just two photosensors to detect the line since all you need to know
is whether you are on the line or not on the line. From my experience in
the class (where people were using as many as 16 sensors), less is better.
- Garth Webb -----------------------------------------------------------------
It's not so hard to lift yourself by your bootstraps once you're off
the ground.
-- Daniel B. Luten
- "http://www.cen.uiuc.edu/~g-webb" ------------------------------------------
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Message is in Reply To:
 | | Re: line following
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| (...) He have (had?) some robots here at work that were used in the production areas, and they followed a line on the floor. I've not studied them carefully, but I think they work something like this: Two reflective photosensors are aimed at the (...) (27 years ago, 16-Apr-97, to lugnet.robotics.handyboard)
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