Detector Pir

will PIR detect a human who is not moving?

I am building a robot that would stop when it detects a human lying down. I know about PIR motion detectors. I want to know if the same would work when the human is static

They are not called "motion detectors" just for fun! They trigger when the very low resolution infra-red image falling on the sensor chip changes. This is usually caused by someone walking in front of one. With the usual cheap security version, if you keep still, they don't go off.

Because of the way they work and the low resolution, they are much better at detecting side-to-side movement rather than towards / away from movement.

In your case presumably you would want to mount the PIR on the robot itself. In that case, the movement of the robot would cause the detected infra-red pattern to change anyway.

The real problem would probably be that people give off less infra-red than other things such as radiators, fires, light bulbs, the sun and so on. These other things would certainly cause a false signal every time something like that swept across the PIR's field of view as the robot moved.

Good luck anyway.

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