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Subject: 
Inverting the robot position problem...
Newsgroups: 
lugnet.robotics
Date: 
Wed, 28 Apr 1999 19:40:11 GMT
Viewed: 
1040 times
  
John wrote:

I have been thinking about a different approach.  I have not actually built
anything to use it yet, but I believe it should work reasonably well.

The basic idea is similar to the old optical mouse pads -- draw
horizontal and vertical lines on the playing field.  Use different colors
for the horizontal and vertical lines (easily distinguishable by the
light sensor's greyscale values).  You can then compute relative position
changes and from that direction of travel.  Obviously, the resolution you can
achieve is limited to the spacing of the lines and the accuracy of
measuring your bot's motion in between them, but it should be sufficient.
The difficulties come from distinguishing the lighter-colored line from the
fringe of the darker line, and the varying line widths depending on the
angle of travel relative to the line.  For instance, travelling parallel
to one of the axes will result in no line crossings for that axis (or
continuously being on an axis).

This brings out a VERY interesting application. Most bots have trouble
navigating a real maze because of obvious slippage problems and generally poor
resolution of sensors. What about inverting the problem and printing (using
your favorite printer) a map using grids and lines on paper and using the
light sensor in a plotter bed.

Now you can program your "plotter" to traverse and learn the maze and
even print (using a pencil) an optimal path through the maze!

Comments? Snickers of derisive laughter? Anyone?

Cheers,

Ralph Hempel - P.Eng

--------------------------------------------------------
Check out pbFORTH for LEGO Mindstorms at:
<http://www.bmts.com/~rhempel/lego/pbFORTH/default.html>
--------------------------------------------------------
Reply to:      rhempel at bmts dot com
--------------------------------------------------------



Message has 1 Reply:
  Re: Inverting the robot position problem...
 
(...) You are right about the limitations of image based maze followers, but with you don't even need to get that complicated- any bot that can follow a wall using touch sensors can do a maze reasonably well. Picture a blind man walking along a (...) (25 years ago, 28-Apr-99, to lugnet.robotics)

Message is in Reply To:
  Re: A robot who knows his position (fwd)
 
(...) I have been thinking about a different approach. I have not actually built anything to use it yet, but I believe it should work reasonably well. The basic idea is similar to the old optical mouse pads -- draw horizontal and vertical lines on (...) (25 years ago, 28-Apr-99, to lugnet.robotics)

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