RE: Room occupancy detection and door opening/closing - 1-wire or wireless solution?

["Paul Gordon" <paul@xxxxxxxxxxxxxxxxxxxxx>]

Some good suggestions there...

I've thought about the pressure sensors under the seat cushion idea in
the past, - it works well enough in my car... never got round to trying
anything though, as my lounge sofas don't have removable cushion pads
that I could put anything under, so don't lend themselves to this kind
of modification.

I guess using *multiple* PIR's could also help quite a bit, - especially
if carefully positioned with a narrow field of view etc. - I like the
sound of the "curtain" ones you mentioned, - is this a specific
model/type or PIR designed for this use?

Paul G.

> -----Original Message-----
> From: ukha_d@xxxxxxx [mailto:ukha_d@xxxxxxx] On Behalf
Of
> Marcus Warrington
> Sent: 15 October 2008 11:50
> To: UKHA Group
> Subject: RE: [ukha_d] Room occupancy detection and door
opening/closing -
> 1-wire or wireless solution?
>
> >> but it can't tell you in what direction they're going, so
> >> how will you know whether to count someone out or count
someone in?
>
> You could get an idea of direction  if combined with the PIR data i.e
>
> If door state changed from closed to open AND the PIR was triggered
within
> the Room then you could assume someone was leaving the room. If on the
> other hand the Room PIR detected nothing but the hallway PIR had been
> triggered then assume they are entering the room.
> Of course the accuracy degrades when you have more than one person in
the
> house..
>
> >Beam-break sensors in the door jamb would signal someone actually
> >passing through the door rather than just opening it. Multiple
> >beam-breaks positioned horizontally could even give you the
direction
of
> >travel
>
> Rather than beam-break sensors (which might be hard to fit i.e. having
to
> fit into either side of the door frames etc) I've toyed with the idea
of
> using Curtain PIRs mounted above on either side of the doorway,
working in
> a similar way but being possibly easier to fit. The one disadvantage
might
> be that it would "see" pets walking through the door,
whereas a
beam-break
> could be set at a height higher than the pet.
>
> Another thing I'm currently about to fit are some stair pressure mats
> under the chair and settee cushions i.e. I can then detect if someone
is
> sat on a chair. I've done a quick and dirty trail run as proof of
concept
> and it seems to work OK, but I've no idea if they will stand up to the
> constant pressure of someone sat on them.
>
> Marcus
>
> ________________________________
> From: ukha_d@xxxxxxx [mailto:ukha_d@xxxxxxx] On Behalf
Of
> Paul Gordon
> Sent: 15 October 2008 10:17
> To: UKHA Group
> Subject: RE: [ukha_d] Room occupancy detection and door
opening/closing -
> 1-wire or wireless solution?
>
>
> Dermot, it strikes me that magnetic door sensors don't actually help
> much in determining room occupation do they?
>
> They just tell you if a door is open or closed. Unless you have
> automatic closers on the doors, either could be a valid state
regardless
> of the room occupancy - my lounge doors for example are routinely left
> open when the room is occupied. Even with automatic closers that just
> narrows down the logic a little bit, so that you can know that if a
door
> is open, someone must be holding it open, & thus presumably
passing
> through... - but it can't tell you in what direction they're going, so
> how will you know whether to count someone out or count someone in?
>
> If you have more than 1 person in the house you can't rely on PIR's
> alone, as they can't discriminate between the movement of a single
body
> or multiple bodies. Even with a combination of magnetic door sensors
and
> PIR's, I can't imagine how you could logically deduce room occupancy
> with any degree of reliability, and certainly not in real-time.
>
> I suppose if you don't care *how many* people are in a room, just
> whether anyone is in there or not, it can be simplified a little, but
II
> sill don't think it would be easy (possible?) to make near real-time
> judgements...
>
> I am assuming of course that the purpose of the exercise is to
determine
> room occupancy in order to do smart things with automation of lights
&
> appliances etc. rather than you having some other requirement for
which
> you just need to determine/count door openings....
>
> In order to do that a bit better, some other technologies, either
> instead of, or preferably in addition to those mentioned would
probably
> be beneficial...
>
> Beam-break sensors in the door jamb would signal someone actually
> passing through the door rather than just opening it. Multiple
> beam-breaks positioned horizontally could even give you the direction
of
> travel (and I guess vertical ones could tell you how tall they were,
> which might be useful if there are kids in the house perhaps?)
>
> Some CCTV systems have some image processing smarts in the software
that
> can count objects & people in this way.. - I know Geovision has
features
> like this for example, so the software can be used (and is designed)
for
> exactly this purpose... - to count people in & out of a room to
maintain
> a record of its occupants...
>
> Not wishing to pooh-pooh the idea, but I've been around on this long
> enough to learn that occupancy detection is pretty much the single
> hardest thing to get right...
>
> HTH
>
> Paul G.
>
> > -----Original Message-----
> > From: ukha_d@xxxxxxx<mailto:ukha_d%40yahoogroups.com>
> [mailto:ukha_d@xxxxxxx<mailto:ukha_d%40yahoogroups.com>]
On
Behalf
> Of
> > dermot_bradley
> > Sent: 15 October 2008 01:35
> > To: UKHA Group
> > Subject: [ukha_d] Room occupancy detection and door
opening/closing
-
> 1-
> > wire or wireless solution?
> >
> > Hi folks
> >
> > I'm trying to figure out the easiest way to detect room occupancy
and
> > doors being opened/closed from a PC.
> >
> > I already have 4-core telephone cable round around various rooms
and
> > I'm in the process of soldering 1-wire temperature sensors to
this
so
> > it would make sense to use this if possible.
> >
> > One easy way to wire up magnetic door sensors seems to be to use
a
EDS
> > D2PC "low cost 2 channel digital I/O 1-wire card" (as
sold by
> > Homechip) to connect the magnetic sensors to the 1-wire network.
> >
> > As for PIR sensors, I've not yet found a easy way to use them
with
> > 1-wire, mainly due to the requirement for power for the PIRs.
> >
> > I guess I could use a battery powered PIR and wire the contacts
to a
> > D2PC for 1-wire connection.
> >
> > Alternatively I could buy some Visonic wireless PIRs and their
> > Powercode receiver to convert the PIR wireless signals to
seperate
dry
> > contacts and then connect these to D2PC and on to the 1-wire
network.
> >
> > Has anyone on the list tried this sort of thing before? Anyone
have
> > comments or alternative suggestions?
> >
> > Basically I'm intended to use the PIRs and door contacts so that
a
> > program on my homeserver PC can control lights and appliances
(i.e.
> > turn on room lights after X minutes of no movement).
> >
> > I haven't decided what to use for light and appliance control yet
> > either (that's a whole other isseu) but will probably go with
Homeeasy
> > or Domia.
> >
> >
> >
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