Re: [mowbot] Buried Boundary

William J. O'Reilly III (pookie nospam at
Wed, 30 Jul 1997 15:05:13 -0500

While I'm a passive person in this discussion, I have some ( a career )
experience in robotics.

> Have you looked at the "radio" fences for pets? They seem to
> have detection up to about 0.6 meters above the cable. One may
> be able to use one of these almost intact, or reverse engineer
> one.

Actually, you can pick them up much farther than that. Here is what you do.
Take an AM radio and tune into something like 1600AM. As you get near the
wire, the signal ( sounds like noise ) will get louder. It has a distinct
frequency, similar to the sound the dog hears before it is shocked.
Incidentially, this is how you find a break in the line. The radio wave
projection density at a wire end ( ie a break) will be much greater than the
rest of the wire. So you could use an off the shelf dog wire to corral your

Here's another idea. How about illuminating the lawn you want mowed with
some type of light source? Not in the visable range, but something else.
The "vision" on a mowbot would know where to mow because the grass is "lit
up," and a sense of "home" can be found by moving to the source of the
light. One could focus the light to follow straight lines for edges,
curves, even "don't mow" areas just by putting a different template infront
of the lens. Another advantage would be that it is a lot easier to change a
template that to pull up dog wire.
If the lawn has trees or bushes, put in two or more lights, just designate
the "home" as, say, a flashing light.



William O'Reilly
pookie nospam at