Re: [mh] [OT] Signaling a door opener

[Ralph M. <ral...@gm...>]

Heh, aren't forums like this great?  Jim's suggestion reminded me of
something else you might try.  Instead of the inductive loop, how about a
pressure mat, such as might be placed under a carpet as part of an intruder
alarm??  As I understand it, it's just a open/close switch, so any person
with sufficient weight moving onto the mat would trip the door opener.  Tha=
t
would take care of the proximity issue because there'd be a very specific
trigger area.

Ralph Mitchell


On 5/6/06, Jim Serack <js...@sy...> wrote:
>
> David,
>
> I understand much better what you want now and I have another idea.
>
> So far all the ideas have been trying to solve the hard problem of
> proximity
> detection of you in front of a door - but not to trigger when you are
> close
> by, and the range needs to be a at least couple of feet, etc, using some
> kind of wireless device.
>
> Whereas there is a much easier problem to solve that will get you the
> desired results - vehicle detection (your wheelchair) with an inductive
> loop
> placed under or in the floor in front of the door, and another outside th=
e
> door under or in whatever is there. Think traffic controls - demand left
> hand turns, parking garage barrier controls. When your wheelchair is
> within
> the loop it will trigger the door open. You could add logic to open the
> door
> when you come into either the indoor or the outdoor loop, and close the
> door
> when you transition from one loop to another (e.g. indoor loop trigger
> when
> no outdoor loop in last 10 seconds -> open door, outdoor loop trigger
> within
> 10 seconds of indoor loop trigger -> wait 5 seconds and close the door).
> The
> sensitivity can be adjusted so that if you are just near the loop it will
> not trigger. You might also look at controllers designed for parking
> barriers that integrate the loop detector.
>
> The inductive loop works just like a big metal detector. The wire loop ca=
n
> be a long way from the actual electronics - so you could put the
> electronics
> all together near a computer, door controller, etc. The wire could be a
> cable placed under the actual floor, a thin wire (28 gauge) under a carpe=
t
> or vinyl mat, outside in a welcome mat, buried in dirt, between
> interlocking
> bricks, cut into the grout between ceramic tiles, etc. The key thing woul=
d
> be to get one sensitive enough to pick up on your wheelchair - but if the=
y
> can make ones that work for bicycles - I'm sure your wheelchair with the
> motors, batteries, and metal will have a major impact on the inductive
> loop.
>
>