piclist 2008\07\31\110904a >
Thread: Beacon system for position location
www.piclist.com/techref/index.htm?key=beacon+system+position
face picon face BY : M. Adam Davis email (remove spam text)



Your yard sounds like it has a number of interesting topological
features!  I wonder if you could put a triple axis accelerometer and
triple axis magnetometer in the mower to get the vector of the ground
surface and the magnetic field.  If you map out your entire yard you
may find that between those two vectors you can roughly identify the
location of the mower.  Place some large metal or magnetic objects
underground in areas where the sloping is not so great.  Or put
magnetic loops underground with time-varying fields.  Turn your yard
into a giant Wacom tablet!

I like the ultrasonic transducers idea, though.  There's a lot of
literature out there about using ultrasonic transducers for measuring
distance.  All you need (heh heh heh - there's that trivializing
phrase again!) is to place a dozen transducers around the yard, each
listening to each other and transmitting a code at a particular time.
Since they can be synchronized to each other, then you can gaurantee
that no transitter will be transmitting at the same time as another
(time slots).

The robot can hear at least 4 at any given time, and reflections can
be dealt with by only paying attention to the first sound heard.  If a
reflection is messing up one of the transmissions, there's lots of
redundancy, so you can safely ignore that one.

Since they can hear each other, wind speed, direction, and temperature
can all be calculated and accounted for on a per measurment basis.

Or reverse that and have the robot beep with transducers around the
yard picking the sound up - but then you'll need auxiliary beeps to
determine wind speed, direction, and temperature.

Fun stuff to think about...

-Adam

On 7/31/08, Kevin <RemoveMEkben@spam@spam.....dca.net> wrote:
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<bc7a59a0807310808i3e5598cfifd0d0e8da972faab@mail.gmail.com> 7bit

In reply to: <Pine.LNX.4.64.0807311004100.21971@shell.dca.net>
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Subject (change) Beacon system for position location

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