best way to detect impact on a paper target...

Thread Starter

Jesse Klein

Joined Dec 5, 2014
26
Looking for options on the best way to detect an impact on a paper target. Keeping in mind wind as a factor.

Currently plan on hanging the target from a metal frame, but not opposed to altering how it is mounted. Target is 19.5" x 40".

The plan is for the target to move upon impact. Stay put if missed. Once the target is moved, the circuit resets. And the process starts over again.

I'm thinking about something along the lines of vibration detection as opposed to something visual.

Any opinions would be most helpful. Thanks.
 

GopherT

Joined Nov 23, 2012
8,012
I would go with a microphone placed against the paper or metal frame.

There are also piezo "contact microphones", essentially a piezo buzzer but wired to detect an impact or noise (like using a speaker as a microphone).
 

Lestraveled

Joined May 19, 2014
1,946
Bullet speed, diameter, shape, and paper density, will have a big impact on the wave energy imposed on the paper. A .223 diameter bullet traveling at 3000 ft/sec will create a much different wave, (or sound), than a .450 diameter bullet traveling at 850 ft/sec. Suggest you get an inducer and a data recorder and take a lot of data.

There are optical bullet sensors used in "Chronographs". These are used to measure bullet speed. I suggest you put your energy into that area.
 

matthew798

Joined Jan 16, 2013
38
There are color sensors that will output RGB channels in digital format. You could use this to detect a significant color change. So for example: you would set up a target and hit the "reset" button, the device would sample the color it sees and keep that in memory. Every time a bullet hits, it would detect a color change (say 10% difference). Any less than that (shadows, clouds, whatever) and the system would ignore it.

https://www.sparkfun.com/products/10904

This is the best way I can think of.

A vibration sensor might be hard to fine tune, considering you want it to move... Motors cause vibrations.
 

GopherT

Joined Nov 23, 2012
8,012
I am assuming it is a pellet/air soft gun. Otherwise any device near or in contact with the paper or frame will be at risk of destruction. Please describe the situation a bit better.
 

blocco a spirale

Joined Jun 18, 2008
1,546
I would expect that a hit would cause a distinct pressure wave behind the paper target that would be very different from any other external sources of noise or vibration. One or more microphones mounted around or within the back of the frame would probably suffice.
 
Last edited:

atferrari

Joined Jan 6, 2004
3,573
There are impact sensors used to detect rough handling of delicate cargo (kind of seismic sensor) or tilt sensors (which once activated cannot be reset) also for the same purpose, probably not suitable but worth to look at.

BTW, have you considere that whatever you choose must be 100% sure that could be not damaged by a "creative" shooter? Those exist but maybe you know that.
 

Lestraveled

Joined May 19, 2014
1,946
Here is a picture of a shooting chronograph. A chronograph measures the speed of a bullet by measuring the time it takes to travel from the first sensor to the second sensor. The openings in top of the main housing are for photo sensors that look up at the defuser panels. The photo sensors detect the small change in light intensity when the bullet passes between the defuser panel and the photo sensor. This is a very proven technology.

 

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blocco a spirale

Joined Jun 18, 2008
1,546
Has anyone read the first post? The OP is not concerned with the speed of the bullet nor with just knowing by visual means that the target has been hit.
 

maj113

Joined May 26, 2012
10
out side the box, i'll toss in 2 cents. a vertical rotating wheel with a wireless trigger on a "stepper motor". an aperture the selected target aligns behind, you push the button, the next target rotates n2 position...balloons with a bit of flour in them are fun . . .
 

BReeves

Joined Nov 24, 2012
410
Personal I think the speaker suggestion to detect the air pressure increase when the target is hit would be the best. Even that would be difficult to implement. I'm thinking you may need some kind of baffle behind the paper to contain and maybe even direct the sound wave. The back would have to be open or replaceable, open may not work very well.

OK, A thin box with a replaceable back, mount the speaker or mic on the bottom with a hole so the air pressure can get to it, protected by a steel plate. Steel plate could also double for your pivot to rotate the target. Outline the front of the box with small but thick angle iron with the point facing forward. This would deflect stray bullets and sorta protect the sides of the box. Make everything replicable, it will get shot up.
 

alfacliff

Joined Dec 13, 2013
2,458
microphone methods would not be practical, dont you know about the pressure wave that comes out of the muzzle just behind the bullet? a lot of noise. why not use a video camera with a vision system to detect the hole in the paper?
 

KJ6EAD

Joined Apr 30, 2011
1,570
This may have become an academic exercise since the OP's not checked in since posting. I know the answer to his question but I don't think I'm allowed to say. Very enigmatic of me, I know.
 

KJ6EAD

Joined Apr 30, 2011
1,570
Since when has the OP needs ever impeded a good hypothetical discussion?
Never, and I only meant it as an observation, not a criticism. We have drive-by, one post wonders begin lots of productive and entertaining discussions that they don't benefit from.
 

atferrari

Joined Jan 6, 2004
3,573
It should be very close to the paper piece (but no bonded to it), maybe in/on the supporting frame.

Should be not in the way of the bullets to avoid bad (and good) shooters.

Should be able to distinguish the effect of (strong) wind.

So, KJ, you are not going to disclose anything, right?

Intrigued, interested, curious myself.
 
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