One feature we would like to have on our light is occupancy detection, but a regular motion sensor will not suffice because of a few problems:
- We want the light to be completely self-contained, and a motion sensor on the light itself will constantly 'trip' if the occupant moves around
- Again with the 'trip wire' concept, it will not work with multiple people, pets, or if you trip it without entering
- If we are constantly using the motion sensor to check for moving occupants, someone taking a bath or shower may be too far or moving too little to be detected.
Obviously a Bluetooth device in the light to detect mobile devices are not optimal because you don't always bring your phone to the bathroom and we don't want to inconvenience the user.
After some research, we have come to the conclusion that using Wi-Fi as a radar is the best solution. By transmitting frequencies and analyzing them when they return to the device, we can see if there is continuous change and detect if something in the room is moving.