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[DPRG] Contests at the Science Place

Subject: [DPRG] Contests at the Science Place
From: R. Bickle rbickle at swbell.net
Date: Tue Feb 5 09:26:13 CST 2002

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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