Re: My latest cool DIY automation idea

[Marc F Hult <MFHult@xxxxxxxxxxxxxxxxxxxxx>]

On Thu, 6 Jul 2006 03:09:13 -0400, "Robert Green"
<ROBERT_GREEN1963@xxxxxxxxx> wrote in message
<FK6dndYe16G0KjHZnZ2dnUVZ_smdnZ2d@xxxxxxx>:

>"IVB" <ivb@xxxxxxxxxxxxxxxxxxx> wrote in message
>
><stuff snipped>
>
>> I'm going to setup CQC & the Elk to turn off speakers and lighting(future)
>> if there's been no motion in a room for 5 minutes. The design looks like
>it would be trivial
>
>It's about as trivial as a three body gravitional problem.  <g>
>
>The basic problem is most sensors will not see a person sitting quietly in a
>chair as motion and they'll turn things off.  It's called the automation
>"wave" because people then sit there flapping their arms to get whatever the
>MD shut off to come back on.
>
>Figuring out who's where and doing what in a house, short of making everyone
>wear transponders, is very tough business.

Yup.  But if everybody _were_ RFID'd, it seems to me that would suffice.

>The perfect solution would probably encompass microwave detectors, RFID
>sensors, IR beams, PIRs, pressure mats, 1000+ lines of code and a fast CPU
>to figure out where people *really* are in a house.  Anything less is going
>to get it wrong a lot of the time.  So much so that it becomes a serious
>annoyance as people get used to flapping their wings like insane geese.
>
>Ironically, I see some great parallels in game software design and occupancy
>sensing.  You'll need variables for each "player" or occupant indicating
>current positions and a set of rules governing how they can move from room
>to room.  Sounds like fun.  I'd like my HA system to have a "God" mode.

You mean locking the kitchen door after 10PM if you weighed more than
TargetWeight + n kg unless you logged in f(n) x m minutes on the Nordic Trac
? ;-)

More seriously, why is RFID by itself intrinsically inadequate for simple
(binary) localization (Is given person in room - yes/no)?

( A simple turnkey RFID solution exists now for at least one popular home
automation software, namely Homeseer. Homeseer addons can also do rudimentary
localization using a generic Bluetooth cell phone.)I have no experience with
either. )

Sophisticated systems with multiple sensors can locate an RFID tag to within
centimeters in 3-D space in real time. Do we need better than a 4-D
definition with centimeter and second resolution for occupancy _detection_?

This time-space resolution should also be adequate for calculation of
velocity vectors (how fast and what direction is an object/person travel
ling) that in turn can be used in a predictive mode, namely where is the body
headed next.

FWIW, RFID is advanced as superior to GPS in some situations for
first-responder emergency needs by these folks from the National Institutes
of Health:
http://www.antd.nist.gov/wctg/RFID/RFIDassist.htm

This url also has many useful references and links to RFID indoor use,
localization techniques,  pedestrian navigation, applications of Zigbee,
phone-based localization among other topics.

... Marc
Marc_F_Hult
www.ECOntrol.org