Subject:
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Re: Newbie has an idea - Nascar style racing?
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Newsgroups:
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lugnet.robotics
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Date:
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Tue, 26 Nov 2002 00:23:06 GMT
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Original-From:
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Steve Baker <sjbaker1@^Spamless^airmail.net>
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Viewed:
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1149 times
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Tim Auton wrote:
> "Rob Limbaugh" <lego-robotics@crynwr.com> wrote:
>
> > Here is a drawing of what I was thinking of:
> > http://www.abs-robotics.com/ideas/track.jpg
>
>
> Like the idea, not sure about the colour choice though - you'd have to
> ensure the red, green and blue would look like different shades to the Lego
> light sensor. I think this would be easier to achieve (and therefore more
> reproducible) with shades of grey. Not that it matters much, calibration
> wouldn't be that hard when moving to a new track.
This makes robots have to depend much more on dead-reckoning. If you
are steering (say) 10% too much - then that error will build up
without limit. You'd come out of a 90 degree turn with a 9 degree
error - but unless you have two light sensors so you can detect
when the track changes colour in the two detectors and use that as a
one-time steering correction, you'd have no way to know. Even if
you did that - you'd need split-second accuracy to measure the time
delay between the two sensors seeing the colour change - and
correlate that with your speed.
When you hit the next turn, you'd build up another 9 degree error -
and it would be pretty unlikely that you'd make it around a single
lap because after 360 degrees of turns you are driving at an angle
of 36 degrees diagonally across the track. Even if your turn error
is only 1%, you won't manage more than a few laps before you run
into a wall or something.
Even the best programming and construction wouldn't allow the
system to support a ten lap race.
The grey-scale scheme where:
black==on the outside lane
white==on the inside lane
grey == in the middle somewhere
...has all the advantages and none of the disadvantages.
The *basic* racer only has to say: If the track is too dark, turn
more to the left - if the track is too light, turn to the right.
The more sophisticated racer can adjust it's track position for
tactical reasons - or head for a lighter part of the track when
it see's it's doing a lot of left turns or a darker part if it's
doing a lot of right turns - in that way it would take a faster
route through the turns and beat the simpler bots.
If you also implemented the tail-light requirement then you
could plan to overtake on the outside or on the inside
depending on which way the track is turning and how far
across the track you are right now.
Those all seem like the kind of skill-oriented behaviour we'd
want to concentrate on rather than making this merely a crash derby
or a boring precision-of-turning contest.
> Tiles are definitely better than paper, agreed. I'd like at least black
> bands (tape/paint) along the edges, or even a little wall around the edge of
> the track. This would encourage a wider variety of approaches - from simple
> wall/line followers to beasts with multiple light sensors which try to
> remember the track and pick the best line.
But if you want this to be do-able with a basic RIS set (only one
light sensor) then you'll have all the robots having to follow the
walls - and it won't be much of a race. Also - with wall followers,
you can't tell the difference between hitting a wall and hitting
another robot - probably resulting in pairs of contestants driving
around in little circles as they try to follow one another.
The grey scale across the width of the track is a GREAT solution.
With only a standard RIS set, I don't think you can improve on it.
The big problem is in the construction of it in a way that's cheap
and durable. Printing it on a computer printer seems reasonably
cheap - and if people are worried about their toner consumption
then head to your local copy-shop and have them do it.
You could also use multiple sheets of construction paper in
black, white and a couple of shades of grey and cut each 'lane'
from a separate.
---------------------------- Steve Baker -------------------------
HomeEmail: <sjbaker1@airmail.net> WorkEmail: <sjbaker@link.com>
HomePage : http://web2.airmail.net/sjbaker1
Projects : http://plib.sf.net http://tuxaqfh.sf.net
http://tuxkart.sf.net http://prettypoly.sf.net
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Message has 1 Reply:
 | | Re: Newbie has an idea - Nascar style racing?
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| (...) First Lego League uses a plastic mat made by 3M for their competitions. Every team gets one to practice with when they register. I don't know how expensive it is since 3M donates it to FLL, but it does have several redeeming qualities for this (...) (22 years ago, 27-Nov-02, to lugnet.robotics)
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Message is in Reply To:
| | Re: Newbie has an idea - Nascar style racing?
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| (...) ensure the red, green and blue would look like different shades to the Lego light sensor. I think this would be easier to achieve (and therefore more reproducible) with shades of grey. Not that it matters much, calibration wouldn't be that (...) (22 years ago, 25-Nov-02, to lugnet.robotics)
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