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[DPRG] Contests at the Science Place

Subject: [DPRG] Contests at the Science Place
From: Ed Okerson eokerson at fw.telenic.net
Date: Tue Feb 5 09:48:55 CST 2002

Rick,

I don't know if the 1/4" hole itself would cause a gap for IR detectors
following the wall, but would the laser cause problems for IR detectors?  I
would think it would swamp them and prevent them from seeing the IR signal
they are looking for.  But your point about height also brings up a whole
other topic, how high should the laser be?  If we put it 2" from the floor,
and someone shows up with a 1" robot, we never detect it crossing the line.
On the other hand if we put it 1/2" from the floor, we will likely get
multiple triggers from tires going by and miss the robot body all together.
I would really like to see this problem solved however.  It would really be
nice to have 100% accurate timing for all the competitions.  It would also be
cool to have the running clock that could be seen by all the spectators as
the robot maneuvers around the course.  Maybe an array of beams 3 or 4 high
and at least 2 long.  As cheap as laser pointers are now days it should be
easy to do.

Ed Okerson
President DPRG

----- Original Message -----
>From: "R. Bickle" <rbickle at swbell.net>
To: "'Mike McCarty'" <jmccarty at SSD.usa.alcatel.com>; "'Ed Okerson'"
<eokerson at fw.telenic.net>
Cc: <DPRGlist at dprg.org>
Sent: Tuesday, February 05, 2002 9:26 AM
Subject: RE: [DPRG] Contests at the Science Place


> Ed,
>
> Sure, this was more or less my default solution, but you would only be
> sensing the passage of the robot at a given height. Some robots may have
> pieces protruding back above or below the height of the lasers which would
> change the time. Bill's little dragster robot comes to mind. It's rather
low
> to the ground. (And it has transparent wheels)
>
> What's the big deal about drilling holes in the walls? It would only take a
> 1/4 inch hole or so to insert the emitters and detectors. I don't think
that
> this would interfere with the robots sensors.
>
> Rick
>
>
> -----Original Message-----
> From: dprglist-admin at dprg.org [mailto:dprglist-admin at dprg.org]On Behalf
> Of Mike McCarty
> Sent: Monday, February 04, 2002 9:37 PM
> To: Ed Okerson
> Cc: DPRGlist at dprg.org
> Subject: Re: [DPRG] Contests at the Science Place
>
>
> On Mon, 4 Feb 2002, Ed Okerson wrote:
>
> > Why?  All you need is two lasers, parallel to each other at the same
> height
> > with detectors on the other side of the course.  The real problem is how
> to
> > get the lasers across without drilling holes in the course walls.  I also
> > suspect that lasers shining into the IR detectors will cause problems
with
> > many robots.  Most of our robots are probably not heavy enough to trigger
> any
> > pressure sensitive contacts.  I guess we could mount microphones at the
> > corners of the course and do surface wave acoustic analysis to
triangulate
> > the bots position.  I saw this approach used once for very large touch
> screen
> > monitors that did not have any overlay on the CRT.
> >
> > Ed Okerson
> > President DPRG
> >
> > ----- Original Message -----
> > From: "Ralph Tenny" <rten at metronet.com>
> > To: "R. Bickle" <rbickle at swbell.net>
> > Cc: "'Rodent'" <daweasel at swbell.net>; <dprglist at dprg.org>
> > Sent: Monday, February 04, 2002 7:04 PM
> > Subject: RE: [DPRG] Contests at the Science Place
> >
> >
> > > It is easy to detect when the front of the robot crosses the line; not
> > > easy to detect when the back end crosses!
> > > Ralph
>
> while (BeamSeen())
>     DoNothing();
>
> do {
>
>     while (!BeamSeen())
>         DoNothing();
>
>     ExitEpoch = GetEpoch();
>
> } while (BeamSeen() && GetEpoch()-ExitEpoch < MaxWaitTime);
>
>
> ExitEpoch is the moment that the robot completely exited the arena.
>
> IOW, we wait until we can't see the beam. Then we wait until we can see
> the beam. Then we "debounce" by forcing a wait until MaxWaitTime has
> lapsed with the beam constantly visible. If the beam goes away again,
> then we reset the timer. This way, if the beam sneaks through a hole in
> the robot for a moment, it doesn't fool us into thinking that the entire
> robot has gone by.
>
> Mike
> --
> char *p="char
> *p=%c%s%c;main(){printf(p,34,p,34);}";main(){printf(p,34,p,34);}
> This message made from 100% recycled bits.
> I can explain it for you, but I can't understand it for you.
> I don't speak for Alcatel      <- They make me say that.
>
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