BAJ wrote:
........
>I always liked the beacon idea. The problem I always had with it was trying
>to figure out how to sense on a moving plane. Between hills, valleys, and
>obstacles, along with a continuous slope in the yard it will be very very
>difficult to sync the transmitter and receiver. But the discussion on the
>rotating VOR mirrors I realized that creating a verticle sweep could help
>quite a bit because then the receiver could sense the transmission even
>with a height disparity.
>
>After thinking about it some more, I realized that putting a complex motorized
>mechanism on a number of stationary beacons probably isn't a good idea. The
>stationary part of the system needs to be as simple and reliable as possible.
>I also figured that the mowbot really only needs to know which beacon it's
>talking to and the angle of the front of the bot relative to that beacon.
>

This is basically the same as my idea. The beacons are fixed, and don't
rotate, but each probably has 3 LEDs wired in series to fire together
with the separate LEDs pointing 90 degrees apart - thus 180 deg xmit
coverage, so the bot can see it from anywhere within a room. Each
beacon has a separate output pulserate, and maybe a 555 or PIC508,
and costs $1-2.

In my case the beacons are always placed along a wall in a room,
and the bot swivels to determine the angle to the beacon, moves and
swivels again - else the bot uses a servo to pan the IR pickup. You
don't need 2 beacons for triangulation, either, because the bot
can only be on one side of it - ie, inside the room with the beacon
up against the wall. However, in my case, the bot uses the beacon as
an absolute reference point, and then uses other means to map out
the room - #wheel rotations, ultrasonics, etc.

- dan
========

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