I think your beacon idea is great but I would use LEDs and modulate them to
ensure that reflections, etc.. don't confuse the robot.

Here is a way to scan for the beacons.
http://www.cyberg8t.com/pendragn/actlite.htm

Also, on the subject of safety, I really (REALLY) think that mowbots should
use the old multi-scissors clipper bar design operated very slowly (but all
the time) to avoid liability. The commercial mowbots do this.

P.S. Dave, let me know if you want another B+D battery lawn mower... with a
locked up motor... real cheap. Two weeks after the warranty ran out...

"Real men use push mowers."

---
James Newton, Admin #3 mailto:jamesnewton@piclist.com
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-----Original Message-----
From: pic microcontroller discussion list
[mailto:PICLIST@MITVMA.MIT.EDU]On Behalf Of David VanHorn
Sent: Friday, August 31, 2001 10:25
To: PICLIST@MITVMA.MIT.EDU
Subject: Re: [EE]: - Botboard


At 11:57 AM 8/31/01 -0500, Jim wrote:
>      "For mowing a lawn it may well be possible
>       to have some IR Led marker posts at strategic
>       points which the bot could sense."
>
>What if these IR LED markers were 'swept' at known
>intervals over the work area?
>
>What I mean is, what if they were 'rotated' in place and
>acted much like a VOR beacon.
>
>By taking the angular bearing from 2 (or more of these
>beacons) a very accurate position could be determined.
>Perhaps this in combination with a perimiter wire to mark
>the outer boundary?

Why rotate?
The beacons could be solar powered, (no mowing at night of course) with
movable blinders to restrict their output to cover only the yard.
You look around, and if you don't see the beacons, you're out of the yard.
If you see one, you're still out of the yard.
If you see two, then you can triangulate.

There are some nice solar powered lights made that I could see modifying
into mowbot beacons.

Alternatively, the beacons could be set up the other way, so that as the
bot begins to get outside, it comes into view of the beacons, but I am more
comfortable with positive control.

How would you deal with missing beacons due to kids or damage?

One of these days, I want to launch on a mowbot.
I already have a B+D battery powered mower.
I have an irregular yard. The front is two rectangular sections, divided by
a concrete sidewalk, which is crossable, but only at certain points for a
mower. The back is one rectangular section, with two apple trees, and some
minor hazards.  They are joined by a side which is about 4' wide.


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I would have a link to http://www.findu.com/cgi-bin/find.cgi?KC6ETE-9 here
in my signature line, but due to the inability of sysadmins at TELOCITY to
differentiate a signature line from the text of an email, I am forbidden to
have it.

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