At 01:19 PM 8/31/01 -0500, Jim wrote:
>      "Why rotate?"
>
>Consider a lighthouse - concentrate your radiated energy.

Likely not needed. Narrow pulses, relatively infrequently, they could even
be coded, as opposed to just at different frequencies. We don't have a
screaming need for speed.


>      "If you see one, you're still out of the yard."
>
>Now I'm getting confused. You should always be
>seeing *all* your beacons (otherwise you can't
>navigate). IOW - this is a disallowed state. Also,
>I *did* mention a perimeter wire in conjuction with
>this approach ...

Only if your yard is a single rectangular plot with no trees.
I have three rectangles, connected by a wide path. The back yard beacons
would not be visible from the front yard, except along the walkway.

XXXXXXXXXXXXXXXXXXX
XXXXTXXHHHHXXXTXXX
XXXXXXXHHHHXXXXXXX
XXXTXXXHHHHCCCCCC
XXXXXXXHHHHXXXXXXX

H is house, T is tree, C is Concrete, and X gets mowed.


>I see how this relates. Again, a seeing eye or sensor
>that can resolve angular bearing. But - how do you
>know which beacon is *which* beacon?

Either a different rep rate, or a different code.


>A VOR 'range' station works on the principle of
>providing user equipment the ability to determine their
>'angle' or bearing to the station - regardless of what
>that bearing may be. Fixes from two (or more) VOR
>stations fixes your positon. Additinally, each beacon \
>would either 'rotote' at different rates (to distinguish
>them) or modulated at differing rates (i.e. 25 and 30 KHz).

I understand. I'm just replacing rotation with modulation.
Less mechanical complexity.

I'm thinking along the same lines I think for raster scanning. All you
really need is to periodically check the beacons to make sure you are on
course. When you hit an end point, you make your turn, verify the beacons
are where they should be, wiggle till that's true, then mow for a while.
Check the beacons maybe every 10' or less, and if things aren't exactly
straight, well I'm not exactly straight either when I do it.

I have one other complexity, on the side where the long thin part is, the
front yard slopes about 30 degrees across the mow path. Steering will be
interesting.

Thinking on this a bit, what if Mr Bot has two crab-like eyes, which he can
lock onto a given pair of beacons.  A little hardware to keep them in lock,
and the angle between them then tells position immediately.  The eyes would
be smart enough to stay locked to a given beacon on their own, until told
to aquire a new beacon.


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