I'd like my kinetic art piece to shut off if there is no one near to see it, saving wear and tear on the mechanisms. Maybe an ultrasonic distance sensor, like Sparkfun SEN 24049? If this were a "picture on a wall", (a shallow case with motorized elements behind glass, maybe hanging in a hall or gallery.) I could put in a sensor that detects when someone comes to look. Ideally the piece would turn on whenever someone gets within 10 feet or so.
This would probably be controlled by something small like a Nano, and it simply turns on a relay to make the kinetics go whenever people are present. All passive, non-controlled stuff that just "runs free." With no outside movement detected, it would shut things off and await new people. As the place shuts down at night, the kinetics would "sleep".
I'm looking for suggestions of what might be a good option for sensing people?
Thanks for the ideas. I had thought a presence module might work, I'm finding things the size of a smoke detector - too big. Maybe one of the Parallax sensor modules would work - I can program my Nano to turn on at motion detected and turn off after a set time barring more motion. So far the piece looks something like this design:
Just use a very filtered power source. I used a power supply deemphasis filter out of frustration, the sensors worked for the first time now I do it out of superstition.
RCWL make other models of a RF Doppler motion detector.
You can use some code to stretch a detection to last for some arbitrary keep-alive time.
The RCWL-0516 is a Doppler sensor. this means that it only detects motion, not static objects. Also because of the simple construction it doesn't detect if the motion is toward or away from the sensor. It is still a useful part as long as these restrictions are not a problem for the application.
