Hi,

I apologize I'm new to this so might not be explaining this well but was wondering if it is possible to get motion detection sensors to trigger selectively at a certain mph or size of the object that is triggering it? Any info would be greatly appreciated. Thanks, Tom

 

hi tmh,
Welcome to AAC.
Which type of sensors are you considering, is it for animal or material type objects etc.?
What detection range.?
E

 

Do you have the skills to build or modify a basic sensor, or do you need an off-the-shelf solution?

 

Again, new to this all so not sure the sensor type. It would be trying to detect a large metallic projectile (1 meter in length), probably 100 feet range or more with speeds of the projectile at roughly 300 mph.

 

Either way is fine...more at the proof of concept stage so hypotheticals are fine at this point.

 

It would be trying to detect a large metallic projectile (1 meter in length), probably 100 feet range or more with speeds of the projectile at roughly 300 mph.

I would suggest a radar set-up, or camera with image-recognition, as possible options.
What's your budget for this?

 

Normal PIR motion sensors like HC-SR501 can only detect motion. Those cannot detect size etc.

 

Motion detectors are either passive infra red (PIR) or microwave.
PIR types detect a warm object moving in and out of the zones created by the lens. The bigger and warmer the object the larger the signal.
Microwave types return a signal which is the transmitted signal (usually 10.7GHz) doppler shifted due to the motion of the object. The return signal is mixed with the transmitted signal to give sum and difference frequencies, the difference frequency is proportional to the speed of movement of the object - which is how radar speed guns work.
The amplitude of the return signal is proportional to the fourth power of the distance and the size and reflectivity of the object.

 

Something moving 300mph would go 100 feet in less than 1/4 second.

 

One meter long projectiles moving 300 mph sounds a bit dangerous to me. What, other than military, could the application of this be?

Bob

 

Normal PIR motion sensors like HC-SR501 can only detect motion. Those cannot detect size etc.

Using two pieces of PIR motion sensors could detect the big size target, but it can not get a precise size.

 

How accurately in x, y an z coordinates do you need to know current velocity and current position?