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DPRG: Line Follower Conditions

Subject: DPRG: Line Follower Conditions
From: Robert Singleton slugmusk at alias.flash.net
Date: Wed Feb 10 01:19:16 CST 1999

John Wadley wrote:

> If I recall
> correctly, the shop floor has that light grey protect coat on it and the
> lighting is dim overhead flourecents.  I'm having doubts about whether
> Low Rider (or most photodetecting robots) can detect a white tape on
> that light of a back ground even using active photo-detection.

I think the protect coat is glossy, which might further confound the

> Assuming I recall the conditions correctly, are you planning to
>   ...switch to black tape on the grey floor?
>   ...stay with white tape and provide a darker floor?
>   ...or is white on grey the final word on the
>      contest conditions for line-following?
> Is the lighting intensity adjustable?

I am not on the contest committee and the following is my personal
opinion: I agree that the change of venue will require adjustments and
resonable attempts to adapt the venue should be made by the club, such
as adjusting the lighting where possible.  In truth, however, the change
of conditions presented by the change of venue are a result of operating
a robot in the real world, the burden of which is to be borne by the
contestant, provided that resonable access to the contest area for
trials and adjustments can be provided.

On the other hand, The Trinity College Fire fighting Robot Contest
addresses this problem by providing a "standard" floor for the contest
area.  This is simply a 64 square foot floor consisting of two 4x8
sheets of plywood or similar, painted flat or semi-gloss blackwith with
seams concealed under walls.  The DPRG contest area is essentially 4 of
these area arranged in a T covering 256 square feet or 3 of these areas
arranged in a long strip covering 192 square feet, requiring 6 to 8
sheets of plywood to construct.

There are no interior walls to the contest area to hide the seams and
unless the concrete floor is particularly flat, the seams could present
physical barriers to many of the robots and would certainly serve as
some kind of obstacle to nearly all of them.  

This quantity of plywood would cost about $160 for pretty cheap 3/4"
plywood, which is about the thinest that I think would lay flat.  More
money could be spent to make 48x96x4 inch boxes that could be screwed
together like stage props, a technique I have experience with and that
works quite well and could be used even outdoors but presents an even
bigger problem with storage, transport, setup, teardown, tranport and

I must admit that I like this idea enough donate part of the materials
and much of the labor needed to build such platforms, but it does
contribute significantly to the "DPRG Empire" effect.

A possible compromise solution would be to lay a 3" wide or wider stripe
of something black and a 1" white tape down the center of that or maybe
one white tape bordered by two black tapes of the same or greater
width.  That way, existing line detection logic could probably still be
used and it would not cost the club so much to accomodate the line
follower class of robots.  This double-taping would eventually cost the
same as the plywood, but does not have nearly the storage difficulties
and can translate to any interior venue we might present in the future.

Robert Singleton


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