Which is the best sensor to detect static human presence.

 

In what context?

 

In what context?

To sense if a person is wearing a helmet or not

 

Tricky. What sort of helmet?

Most likely viable solution is machine vision with AI trained to recognise a person wearing a helmet... unless there's something special about the helmet, ie it has a radio tag or a visible barcode.

 

Tricky. What sort of helmet?

Most likely viable solution is machine vision with AI trained to recognise a person wearing a helmet... unless there's something special about the helmet, ie it has a radio tag or a visible barcode.

A normal helmet...It just has to detect whether the person is wearing the helmet or not....so had to an find ideal sensor for this.

 

A normal helmet...It just has to detect whether the person is wearing the helmet or not....so had to an find ideal sensor for this.

What's a normal helmet? Motorbike, cycle, army, construction??? all are normal in context!

Assuming a motorbike helmet, there no obvious sensor for that. You can't, I'd bet, reliably detect its presence by light, heat, ultrasonics or radar (well maybe sub-millimetre radar but I doubt it), so machine vision would be my obvious choice...

 

What's a normal helmet? Motorbike, cycle, army, construction??? all are normal in context!

Assuming a motorbike helmet, there no obvious sensor for that. You can't, I'd bet, reliably detect its presence by light, heat, ultrasonics or radar (well maybe sub-millimetre radar but I doubt it), so machine vision would be my obvious choice...

Yes for a motorbike
Thank you!

 

Unless you can instrument the helmets, you are going to be stuck with using computer vision with AI, and in that case no separate sensor for presence is required.

 

We are trying to build a circuit that can sense if a human is wearing the helmet (for motorbike) or not.....we are placing it inside the helmet so it needs to be really small. Which sensor should we use?

 

Infrared sensors seem to work well for detecting human presence. They make a lot of different alarms with those kind of sensors, and even door alarms that detect when someone is just outside the door within some number of feet away and it can even be like 20 feet away.

 

We are trying to build a circuit that can sense if a human is wearing the helmet (for motorbike) or not.....we are placing it inside the helmet so it needs to be really small. Which sensor should we use?

Well thats a completely different problem to your original request. You must state your problem/requirement completely if you expect a useful answer.

I'm not sure how having the helmet detect if its being worn or not addresses your overall requirement because you've still not defined the problem fully, but I'd look at:
a) the differential shaded temperature inside v outside the helmet; or
b) optical beam across the helmet internally; or
c) microswitch pressure sensor in helmet lining...

 

Tell us what problem you are trying to solve! So far, the information you have given has been nothing but misleading.

Bob

 

How about putting two metal plated areas on the inside of the helmet and sense the capacitance between the two plates. The dielectric constant of a human head is quite a bit different than air. It would be very passive and not interfere with wearing of the helmet. The rider would not know it was there. The electronics could be quite small, battery powered and communicate with a system via BLE.

 

You will detect if there is a helmet around a head or a head inside a helmet?
IOW, you will have the helmet's ID or the human's ID as a reference?