Re: Room occupancy detection

[Wayne <Wayne@xxxxxxxxxxxxxxx>]

Hiya Brian,

I've wondered this myself as an idea for a while, albeit a slightly
different approach.
I was thinking something along the lines of giving people little
bluetooth 'badges' - which could be modified bluetooth headset to act as
the locator - although I don't suppose its too much different from a
phone for just the bluetooth side - (think 'star trek comms badge'
idea). (ok - wild thoughts but bare with ;-)

I'm sure I read somewhere that part of the bluetooth protocol has the
ability to tell you how far a bluetooth object was away from another
bluetooth object - more like a little 'pre amble' that gives you a
radius of separation. Now... if (there's a few ifs and buts here) you
can get a small bluetooth usb type stick positioned in the corner of
rooms, then you could hopefully tell from the bluetooth chatter if it
could 'see' a 'badge'. Scatter enough of these around and you can tell
what room a 'badge' is in.

ok, big problem 1, bluetooth knows no walls - the usb stick I have for
my pc here can pick up next doors mobile phone!. If (that word again) it
could be possible to shield the stick in such a way that it was
surrounded on 3 sides with metal - would that be enough to focus its
reception? Think along the lines of a metal square biscuit tin, then cut
off a corner to get yourself a 3 sided pyramid - put that up in the
corner - usb stick inside - would that be enough? (Now I'm not saying we
all need to be cutting up Foxes Chocolate Special collections tins here
- but you get the idea). If you didn't have any shielding then working
out distances from all the receivers would need calibration when they
are in place - as you may find that the receiver in your hall gets just
as good a signal from the one in your kitchen and throw the whole thing
out.
2, there are no bluetooth 'startrek' badges - so you would be butchering
a headset/ear piece. Interesting if you could make use of the audio as a
walkie talkie type thing - just remember to turn the audio off when you
visit the loo! Also, if you can intercept the audio from these things -
then maybe voice controlled HA is a possibility. Mostly the earpieces
are pretty focused on audio pick-up - so background noise now isnt a
problem?
3. the usb bluetooth sticks - erm - its usb! that wont stretch around
your house that's for sure! - you would have to look at getting some
sort of 'hub' that could then map these maybe into IP... I have seen
devices that let you extend usb over IP that may work - but they don't
seem to come in 'budget'
4. everyone/thing that you want to track needs to keep the 'badge' with
them. I guess including your pet dog! - If you were using phones, then
for teenagers this isn't so much of a problem - do you know any teenager
that /doesn't/ have their mobile with them!!


Other than that (could there be any more obstacles!!) - there's a few
'leaps of thought' with this - but at this point - bouncing around ideas
is the best way to start (after the sniggers die down that is :)

Cheers
Wayne.






Brian Milton wrote:
> Hi,
>
> I know this is a big area in home automation,  I have used PIR's,
> infrared triggers to try detect occupancy.  But have the usual problem
> of not being 100% sure if someone is in the room or not and have
> lights etc. turn off even when your in the room.
>
> I have been working on an idea and was wondering what people think of
> it and would it be of interest.  It will be just a hobby and will most
> likely make it open source if it works out.
>
> My idea is to create a indoor positioning system using bluetooth,
> mainly thinking of peoples phones.  Your phone could be used to track
> what room you are in rather than trying to find out if someone went
> into a room or not.  So if your sitting in a room the system will know
> you are there, getting rid of the guess work.
>
> Obviously this will require some bluetooth devices placed around the
> house to triangulate position.  The main advantages i am doing this
> for is to get rid of the guess work, but to also have the automation
> more personalised to the specific user/room/appliances/time etc.  Also
> will look at using your phone for control.
>
> I am going to be developing this in java as its the main language i
> know and most phones will support it.  I also will include the
> x10/xAP/xPL API's and maybe more.
>
> Any taughts? Know of a similar system? Or am i wasting my time?
>
> Cheers
> Brian
>
>
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