Subject:
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Re: Help with my robot
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Newsgroups:
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lugnet.robotics
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Date:
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Fri, 15 Dec 2000 04:05:39 GMT
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Original-From:
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Steve Baker <sjbaker1@airmail=antispam=.net>
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Reply-To:
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sjbaker1@airmail.=StopSpammers=net
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Viewed:
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975 times
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Rainer Balzerowski wrote:
> I thought in the same direction. For driving straight you don't need a light
> sensor (but for accurate turning) It must work with two touchsensors that were
> touched from an arm placed on the "detector-wheel". So you are able to detect
> to which side the robot "floats". The only thing you have to do is to drive it
> with an torque gear, so that you can turn anyways.
Yes - but that's using TWO inputs.
With a little thought, you can actually get the direction from a single light sensor.
Make your detector wheel white around one half and black around the other half.
Looking at the wheel, you'd want:
Light
Sensor
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v
W B
W B
W B W == White
W B B == Black.
W B
W B
W B
All the while you are getting a mid-range reading from the light sensor, you
are going pretty much straight. If it gets darker, turn in one direction,
if it gets lighter, turn in the other. (In fact, you probably shouldn't
*turn*...just 'float' the output of the appropriate motor).
When you want to make a 180 degree turn, you can shift to a different algorithm
and count revolutions of the detector wheel by the number of dark/light (or
light/dark) transitions that go past (because you KNOW which way the wheel
is rotating right now). If you gear the detector wheel so it does an exact
number of rotations for a 180 degree turn - then you can solve the entire
problem with one light sensor.
Of course this only ensures that the speed differences between your motors
are cancelled out. If your wheels don't grip equally well - or if the
floor is uneven - or the wheels are slightly different diameters - then
you'll still no go in an EXACT straight line...but it's hard to fix that.
--
Steve Baker HomeEmail: <sjbaker1@airmail.net>
WorkEmail: <sjbaker@link.com>
HomePage : http://web2.airmail.net/sjbaker1
Projects : http://plib.sourceforge.net
http://tuxaqfh.sourceforge.net
http://tuxkart.sourceforge.net
http://prettypoly.sourceforge.net
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Message is in Reply To:
 | | Re: Help with my robot
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| (...) I thought in the same direction. For driving straight you don't need a light sensor (but for accurate turning) It must work with two touchsensors that were touched from an arm placed on the "detector-wheel". So you are able to detect to which (...) (24 years ago, 14-Dec-00, to lugnet.robotics)
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