Re: Sensors for doors & windows & ...

[Kevin Hawkins <yahoogroupskh@xxxxxxxxxxxxxx>]

I'm intending using some of the Maxbotix ultrasonic sensors pointing
slightly diagonally across the doorways.  These then provide a direction
indication for a person moving into or out of a room  (short to long or
long to short reading) and based on distance you can elimate outside
false trips.  I use Gerrys boards, only played so far but seems viable,
fortunately I have deep doorways in walls often 3 foot thick. .   A top
mount sensor might even identify people based on height- or the dog .

I also have some Pulsor -strain sensors arriving any day now - which I
hope to use on the stairs and a couple of doorways.

K

Chris Hunter wrote:
>
>
> 'thinking of sensors for doors & windows ... and the limitations
of
> the reed-switch (just open or closed & no certainty on what it's
> telling about the door, unless perhaps it's attached to the locking
> mechanism in some way - which can't see how to do as a retro-fit) ...
> was trying to think how else ... strain-gauge ... laser + mirror ...
> all have just-as-bad limitations ... hmmm ...
>
> 'wonder if PIRs are all the same ... obviously not, but in the sense
> of being designed to pick-up just movement .... are there some that
> are designed to pick-up position, say, or presence not associated
> with movement, or movement of hard but not soft objects, or ... ?
>
> with MHVR, having doors or windows open might be expected to affect
> the pressure in the house ... so, all closed => some
pressurisation,
> maybe, depending on the relative speeds of the inlet & outlet
> fans ... 'wonder if adding air-pressure-sensor(s) to each room could
> be useful ... picking-up both level & fluctuations ... and so
doors
> open, people moving-about, curtains wafting, pesky flies, whatever ...
>
> micro-phones are air-pressure sensors, of course ... wonder if a
> broad or limited bandwidth one would be best ...
>
> hmmm ... would fuzzy logic be the thing, to make it work ... looked-
> up Wiki, but 'am really none the wiser, 'though it did mention
> pattern recognition as being an application for it ...
>
> rambling, sorry, but I feel there's a glimmer here !
>
> or maybe I'm clutching at straws ...
>
> Chris
>
>