What's that Lassie? You say that Flash fell down the old
rec.crafts.metalworking mine and will die if we don't mount a rescue
by Sat, 6 Dec 2008 23:48:13 -0500:

I ran a flame-cutter several decades ago that used an optical trace - the
thing had to have a fairly high contrast between line and background, and it
had an "ey" about the size of a coffee cup. The whiz-kids who kept it in
operating order (as it was an *old* model) said that it had a set of pickups
surrounding the central sensor, and they read "more" or "less" and the
movement was controlled by that.

Thanks.

That is kind of what I figured for the steering of the pickup head.
But how does it convert the position of the pickup head to the X and Y
drive motors. I could make something follow a line easy enough. But
when it comes to going around a corner that would require one(or both)
of the drive motors to change direction, that's when I get lost.

If I had an X Y table (or gantry), that was controlled by a pointer
that you could rotate to change the direction of travel, I could make
a line following eye to move said pointer and trace out a shape on
paper.
--

Dan H.