Re: moving away from the remote-control paradigm

["Mick Furlong" <dorsai@xxxxxxx>]

Well it depends on what you are trying to acheive...both of us have a habit
of
leaving lights on everywhere so a system which will turn off the lights
after
a period of no occupancy would work for us.

As long as you have instant lights on for PIR detection then it should work
pretty well (not perfectly I agree). I am slowly getting together
everything
to try this out on homebrew hardware/software (homevision is way to easy I
like being awkward ;)

Thinking about the two beams I can see potential problems with that as we
all
have arms and legs thereby allowing false triggering. Setting the beams at
an
appropriate height might limit the false triggers but would not eliminate
them.

So adding the mat sensors Mike mentioned to the beam breaks and PIRs I
suggested earlier would give you a pretty good concept of direction.

The beam sensor tells you a door is being used and if the mat sensor in the
room is triggered before the beam it is an exit from the room, if after it
is
an entry. The PIR provides ongoing information on occupancy (the BIK
sensors
Stuart is working on would be even better but if I recall means running
ariels
here there and everywhere which will have a low WAF).

I guess the best way to find out is to try it ;)


Cheers
Mick

Paul Gordon <paul_gordon@xxxxxxx> said:

> That's the fundamental flaw with PIR technology - it is so inherently
> unsuited to this kind of application that you _have_ to kludge it with
these
> timer rules, otherwise you end up with the lights going off when
you're in
> the middle of reading your evening paper!
>
> But, - suppose, as you say, you don't decrement the the "room
occupancy
> counter" until an inactivity delay has expired (say 5 minutes)...
now
> consider, - do you do the reverse when entering a room? - I would
imagine
> not, - so in the space of 5 minutes, lets say you go for a piss,
answer the
> door to the Pizza boy, and go to the kitchen to serve it up.. - Now
you have
> set about 4 seperate rooms to occupied, all of which will remain so
for 5
> minutes - according to your house, there are now 4 people in
residence! - no
> mean feat if only two people live there!
>
> If SWMBO is moving around upstairs as well, it's not hard to imagine
your
> house occupancy count spiraling ever upwards!
>
> So, you say, - you tell the house the max number of occupants that are
> permitted... - if there are 2 of you living there, then there can only
ever
> be a person in two places in the house, so the occupancy count should
never
> go above 2. - if a 3rd room detects occupancy, then one of the
previously
> occupied rooms must now be unoccupied, so you look at your detector
> histories and find out which of the allegedly occupied rooms has not
> triggered for the longest period of time, and mark that as now being
> unoccupied... But suppose that the wrong room is chosen? (perhaps
because
> you might be sitting still reading the paper...) Worse, what happens
when
> you have friends come over, or the man comes to read the meter? - you
then
> genuinely do have more people in the house that the house refuses to
> acknowledge!
>
>
> Think about it long enough, and you're brain will explode as well!...
>
> Paul G.
>
>
>
>
> -0000
> >
> >It should be possible to come up with a reasonably reliable system
using a
> >combination of beam breaks and PIRs. For example beam in living
room door
> >is
> >broken plus activity on PIR in Living room = living room occupied,
beam in
> >living room door broken and no activity on PIR = living room
empty. If you
> >couple this with counting beam breaks you will have a reasonably
reliable
> >system especially if you set the timing so that the system only
flags the
> >Living room as empty once there has been no movement for say 10
> >mins....personally I can't sit still for 5 mins unless I am asleep
;)
> >
> >Mick
> >
> >  Mark McCall <mark@xxxxxxx> said:
> >
> > > Remember reading way back at the start about this guy that
had two IR
> >beams
> >in his door frame.  Order they were broken in gave direction of
travel and
> >central controller kept a count of people as they went in and out
so it
> >didn't turn lights out until it knew there was no one left in the
room.
> > >
> > > He couldn't figure out why lights were still on one time and
no one was
> >in
> >the room.  Then he remembered he'd carried a chair into the room
which was
> >slightly in front of him and seen as another person :-)
> > >
> > > Nothing's perfect in this game.
> > >
> > > M.
> > >
> > >   ----- Original Message -----
> > >   From: Mark Harrison
> > >   To: ukha_d@xxxxxxx
> > >   Sent: Wednesday, August 08, 2001 4:39 PM
> > >   Subject: RE: [ukha_d] moving away from the remote-control
paradigm
> > >
> > >
> > >   Kieran,
> > >
> > >   Thanks.
> > >
> > >   Is there some way of sensing not just that I've been
through a doorway
> > >   (broken a beam), but to tell which DIRECTION I was going
in.
> > >
> > >   Given that there are only 2 of us in the house, it
wouldn't be beyond
> > >   the wit of man to be able to say that "person enters
room", ROOM IS
> >NOW
> > >   OCCUPIED, "person enters room", "person
leaves", "person leaves", ROOM
> > >   IS NOW EMPTY ... type of thing, but this is contingent on
being able
> >to
> > >   detect the diffence between "enters" and
"leaves".
> > >
> > >   Regards,
> > >
> > >   Mark Harrison
> > >   Head of Systems, eKingfisher
> > >
> > >         Yahoo! Groups Sponsor
> > >
> > >
> > >
> > >
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> >
> >--
> >
> >
> >
>
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