Re: Occupancy detection

[nobody@xxxxxxxxxxxx (Dave Houston)]

Just a couple of points...

1. There's no reason to think the various motion detectors are saturating
the RF environment. They only transmit for a very brief period (5 bursts
that last about 65mS each) when triggered by motion so unless someone in the
household is now constantly wandering about aimlessly (or purposefully, for
that matter), RF activity attributable to the motion sensors should remain
more or less the same over time. The decrease in range could be caused by
any number of things - weaker batteries, higher humidity, temperature, etc.

2. The IR used in the types of sensors you are considering is usually of a
different wavelength and does not modulate a 38-40kHz carrier and IR is also
line-of-sight so it's unlikely to affect the Powermids.

"Robert Green" <ROBERT_GREEN1963@xxxxxxxxx> wrote:

>I came across the following article recently and began to wonder about the
>current state of occupancy detection.  Even X-10 at its smartest is pretty
>dumb when it comes to turning out lights that you're not really using and
>conversely NOT turning out lights that your ARE using (i.e. longer than
>average bathroom stays.)   The article got me to thinking about how dogs do
>"occupancy detection" and where AI could play an important part of light
>control, conservation and "wellness detection" for want of a better term.
>
>***************************************************************
>http://wtop.com/?nid=106&sid=1169767
>
>Can Motion Sensors Predict Dementia?
>June 18, 2007 - 4:15pm
>
>By LAURAN NEERGAARD
>AP Medical Writer
>
>WASHINGTON (AP) - Tiny motion sensors are attached to the walls, doorways
>and even the refrigerator of Elaine Bloomquist's home, tracking the
>seemingly healthy 86-year-old's daily activity . . . to see if
>round-the-clock tracking of
>elderly people's movements can provide early clues of impending Alzheimer's
>disease. . . . The theory is that as Alzheimer's begins destroying brain
>cells,
>signals to nerves may become inconsistent _ like static on a radio _ well
>before memories become irretrievable. One day, signals to walk fire fine.
>The next, those signals are fuzzy and people hesitate, creating wildly
>varying activity patterns.
>
>
>***************************************************************
>
>I recently took a tumble down a stairway controlled by an X-10 Hawkeye
>(OUCH!).  As a result, I've come to the conclusion that X-10's motion
>detectors, while useful in some situations and for some people, are not
>making the cut when it comes to my house.  Ironically, the fall occurred
>because I was moving very quickly and did not trigger the Hawkeye, which,
>until I fell, had never failed to turn on that particular light reliably.
>It's a lot to ask of an HA system to be able to record and analyze speed of
>travel and travel patterns within a house, but that article made me think we
>might finally be there, equipment and software-wise.   The dog sure knew I
>was heading down the stairs at a fast clip, but the HA system did not.  It
>could have known, though.
>
>Part of the problem with X-10 RF is wire lathing in all the walls blocking
>radio reception.  But I suspect another part of the problem is the growing
>saturation of the RF band used by the HawkEye/EagleEyes.  I tested reception
>in my house five years ago and where I was reaching 15' between test points
>in the past, I now only reach 10'.  While I'm aware there could be a number
>of possible causes, the bottom line is that RF-based motion detector signal
>propagation is not reliable, particularly in dangerous areas like dark
>stairwells.
>
>I've decided instead to investigate the feasibility of using multiple
>sensors, and incorporating IR light beams across doorway openings to
>positively detect when someone has entered or exited a room.  I've had some
>success with pressure mats under carpeted areas, but the places that most
>need automatic light control have concrete, tile or wood floors.  If the
>sensors and light sources are small enough, I could embed them in the door
>trim pretty easily.
>
>I've come across an interesting candidate at:
>
>http://www.apogeekits.com/ir_light_barrier_mk120.htm
>
>and the price per doorway seems to be right but I have a few concerns.  The
>first is whether I can mount the diodes and detectors remotely on a 10'
>length of wire without affecting circuit values adversely.  The second, more
>important question is whether putting IR emitters in all the doorways is
>going to cause more problems for the Powermid and other IR communication
>devices.  The third is whether I can run all the kits from a master power
>supply without interaction issues.
>
>The second half of this equation is what sort of controller is best suited
>to handling the demands of multiple-sensor, very high reliability occupancy
>detection?  We've discussed this here before, but with WiFi-enabled cell
>phones and other new, miniaturized wireless devices becoming available, it
>may finally be possible to tell where every member of the household is, 24
>by 7.  While it sounds intrusive, think about how much greater the degree of
>control there would be over personalized automation if the HA system could
>know who was where, and what they were doing.
>
>If they are sitting quietly watching TV, no sudden light flashes.  If
>someone's taking a super-long shower or "other" activity, no sudden
>darkness.  The system would be able to respond to rules like "if no motion
>is detected *but* no one has left the bathroom, leave the light on."  This
>one ability would shoot SAF (and my own AF) up considerably and it should be
>doable unless someone climbs out the bathroom window.  Turning off lights as
>soon as rooms became empty (instead of after X minutes) and being able to
>provide "light pathways" as a person walks along through a darkened house
>should shave some serious $ off the electric bill.
>
>If FPS games can track hundreds of actors across multiple continents in huge
>simulated terrains the CPU horsepower is obviously available to track two
>slow moving people and two somewhat livelier little dogs in a rather small
>residence!
>
>Any thoughts or relevant information will be appreciated.