Comment by t0mas88
1 year ago
Wifi sensing is interesting, but you can combine a $3 ESP chip with one of these for a much easier project at lower cost: https://www.dfrobot.com/product-2795.html
I use those for presence detection in my house. 3D print a small case and for < $20 you have highly accurate presence detection that also works when sitting still. Ideal for automatic light and climate control.
My problem with similar sensors is that they don't work very well if you're sitting still around 3m away. Maybe my sensor isn't great, but when I'm sitting still at the computer, it frequently thinks I'm not there any more, which ruins any benefit.
There are some that detect heartbeat, I guess those might work. But those are mmWave, not just cheap 2.4GHz radars or PIR.
I've got LD2410B, which are mmWave, so they should detect heartbeat (and do), but not from more than 2-3m away.
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A hack is to put a sensor on the chair
I solved the issue by linking my lights to a switch that I turn on when needed. It has worked very well so far, with no false detection at all!
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Hmmmmm that's not a bad idea, I'll have to see how to do that, though. I don't want cables restricting me.
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Pairing them with PIR detection should help to also detect stationary warm objects.
It's difficult to find good PIR sensors though. The commonly found cheap modules don't include a thermistor to compensate for room temperature. Finding one with analog output or continuous detection is even more difficult, most detect changes.
I did pair them, unfortunately PIR sensors are even worse at detecting stationary objects (less sensitive to body micromovements).