Subject:
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Re: 2D positioning ???
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Newsgroups:
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lugnet.robotics
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Date:
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Fri, 10 Dec 1999 08:30:13 GMT
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Viewed:
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458 times
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In lugnet.robotics, Michael Yates writes:
> Ideally that demo would involve some sort of cooperation. To achieve this we
> need to know where each robot is relative to the other robots. We can do one
> dimensional position control using a gradient fill pattern from one end of the
> "arena" to the other. It is the second dimension which has us stuck.
Hi!
I have tried a method for 2D positioning, and it works if you don't need a high
precision. It might be refined for higher precision, but I didn't try it. It is
a variant of the gradient fill pattern.
There are several ways to do it. The surface is covered with a square pattern
and the squares are in different shades of gray, allowing the robot to know in
which direction it is moving. In order to be able to be able to distinguish
between the 4 directions, 9 different shades must be used. This is difficult
because of the limited dynamic range of the light sensor.
A variant is to only use black and white, and use a kind of bar-code to code
the transitions from one square to another. The bar-code should be assymetric
in order to distinguish the direction. Eventually, a gray patch should be
placed on the corners, to avoid confusion.
I tested these methods on small surfaces, and they work fairly well; the first
is very sensitive to the lighting conditions; the other requires a rather slow
speed for the robot.
Of course, this method only give relative movement values, and they have to be
integrated over time in order to acquire absolute positions, but the advantage
is that it doesn't need any extra equipment (except the drawing on the floor).
Good luck. Please let us know how things go for you.
/Vlad
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Message is in Reply To:
 | | 2D positioning ???
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| I realise this is an open ended question but I will ask anyhow. We (as I have mentioned a number of times, probably maing in RCX newsgroup) have 6 RCX's that we wish to make into a demo for school kids. Ideally that demo would involve some sort of (...) (25 years ago, 8-Dec-99, to lugnet.robotics)
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