Electronic – Occupancy Sensor for Arduino

home-automationsensor

I working on a home (rather room) automation system using a Raspberry Pi as 'brain' and an Arduino as sensor board.

I find it quite difficult to come up with a solution to reliably track if a person is currently inside the room or not (to trigger the lights).

Here are my current ideas and what I think about them:

  • PIR: only for movement detection, probably can't see when I'm sitting at my desk: would need to wave to the sensor every once in a while.
  • Door counter: not reliable if someone decides to turn on his heels.
  • camera: too difficult to program reliably.
  • IR thermo array: probably the most reliable, but expensive for high resolution, not sure if something about 4×16 would be enough. [Edit] I have found that the Panasonic Grid Eye 8×8 thermopile sensor (~30$) is advertised by Panasonic themselves as that it could span a whole room and indicate the position of a person in the room. Even though I think that this won't work for the entire room, it will surely be enough to get a nice movement vector in the area of the door if someone enters or leaves the room (if the sensor is faced more to the door instead into the whole room).
  • microwave sensor: haven't really found information about sensitivity in comparison to PIR.

Does anybody have some more ideas or thoughts on the ones listed above?

Best Answer

Combining the outputs from a few simple sensors such as a PIR, sound sensor, door switch, etc., might work well. You could set a different delay time for each and OR the results. So if you haven't moved, burped, or opened a door in a long while your either sleeping, not home, or just plain dead. (Its lights out in all cases.)