Re: My latest cool DIY automation idea

["E. Lee Dickinson" <lee@xxxxxxxxxxxxxxxxxxxxx>]

"Robert Green" <ROBERT_GREEN1963@xxxxxxxxx> wrote:

> I'm working on ideas for multiple sensor "nets" so that there's always
> some
> way to verify the information one sensor sends with that of another.  I
> bought a big roll of pressure mat material that I'll be installing on each
> side of a door in the new house to hopefully give me information on an
> occupant's direction of travel as well as their presence in a room.  That
> information, along with PIR and IR beam data, should be able to
> conclusively
> determine whether a room is occupied or not.  There should also be enough
> redundancy so that the system can operate reliably if one or more sensors
> fails or has failed to "see" the occupant.

Bobby,

I stumbled across a solution to this at the airport, just the other day.
Pulling in to the parking garage, there was a sign that indicated the number
of available spaces on each floor. As you all know, I'm a geek with a
touchscreen in my kitchen cabinet, so naturally I had to figure out how this
worked.

I stomped around on the concrete for a while, trying to find the pressure
sensors in the slab, looked above for the laser range finders pointing down
above each space, and checked for underpaid workers with tally sheets.

Finally figured it out, and it was so elegant.  Every entry and exit to the
parking garage has two IR beams, spaced six inches from eachother. Whichever
beam is broken first indicated the directon of travel. Car goin in, add one.
Car going out, subtract one.

Same would work in a door jamb, put it about 3 feet up so it misses pets,
but detects (many) children, and doesn't count adult legs as two people.

Of course, this can't account for people jumping out of windows, beaming up,
or falling through transdimensional rifts. But after all, this is DIY... :)

Simple concept and I manage to make a narrative out of it. Sorry. :-P