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

wayneh

Joined Sep 9, 2010
17,496
Perhaps the OP can explain if/why he wants to avoid visual methods like everyone else uses.

I can't recommend trying to develop a new method without knowing exactly what's "wrong" with the standard method. Read the title of his post, and explain to me why the "best way" is not the current state of the art already in use.
 

blocco a spirale

Joined Jun 18, 2008
1,546
Perhaps the OP can explain if/why he wants to avoid visual methods like everyone else uses.

I can't recommend trying to develop a new method without knowing exactly what's "wrong" with the standard method. Read the title of his post, and explain to me why the "best way" is not the current state of the art already in use.
Because he wants to automatically move the target following a hit.
 

wayneh

Joined Sep 9, 2010
17,496
Oh, you mean like in a pinball game, hit the target and it zips away? I totally missed that part of it. What provides the power to move it?
 

Lestraveled

Joined May 19, 2014
1,946
Regardless of what it is used to activate, the issue is still, what is the best method to detect a bullet passing through a paper target. So far there are two suggested methods, sonic and visual.

The visual method is tried and true, and is relatively simple.

The sonic method will require some kind of processing or filtering to discriminate between ambient gun shots (sound) and the wave created by a bullet passing through paper. The sonic wave from a gun shot will impact the entire target area, in this case 780 square inches. The bullet will only impact a very small area: .159 square inches for a 45 acp, and .04 square inches for a .223. That is a 1000 to 1 ratio at best. The paper will also want to resonate at one frequency. If the bullet passes through the paper close to the microphone, it might work. If the bullet passes through the paper far away from the microphone all the wave characteristics that make it different from a sound wave, will be lost.
 

wayneh

Joined Sep 9, 2010
17,496
Here's another method to consider - accelerometer. I think the sharp, unidirectional spike from a strike on the target ought to be "easily" distinguished from ambient wind and noise.
 

blocco a spirale

Joined Jun 18, 2008
1,546
Regardless of what it is used to activate, the issue is still, what is the best method to detect a bullet passing through a paper target. So far there are two suggested methods, sonic and visual.

The visual method is tried and true, and is relatively simple.
Can you elaborate on the simple visual method?
 

Brownout

Joined Jan 10, 2012
2,390
Not a shooter myself, but.... some time ago, I looked over a circuit meant to detect then a diesel injector fired. It was a diesel tachometer. It used a piezo device as a detector. I would try mounting the target to a frame with the device attached.
 
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BReeves

Joined Nov 24, 2012
410
Can you elaborate on the simple visual method?
Only way I can imagine is a computer analyzing an image captured with a camera.. Nothing simple about it..

I was once involved in an automated target project, wrote the software for the computer that controlled the micros out on the range which controlled the targets. The targets (10 targets each in 5 stations, 50 targets total) were steel and replaceable, the mechanism was air operated. Without air, the targets would fall just from being hit and a micro switch told the system when a target was hit. The software on the computer would raise and/or lower the targets depending on what scenario the shooter selected. All scenarios were timed and the computer reported to the shooter his time at the end. I still have all the technical stuff for this system and a demo board with 10 air cylinders. The original project crapped out when the range owner ran out of money, guess I now own it as he still owes me for some of the work I did. Anyone want to start marketing an automated target system, I could be bought.
 

Lestraveled

Joined May 19, 2014
1,946
Can you elaborate on the simple visual method?
OK
The sensor is a photo transistor. There is an AGC loop that keeps the transistor in the linear region no matter the ambient light level. The AGC loop is slow. The output if the photo transistor goes through a high pass filter and then to a high gain amplifier.



The bullet causes the light to decrease as it passes between the photo transistor and the light source. The very small voltage changes are amplified and threshold detected.
 

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wayneh

Joined Sep 9, 2010
17,496
It used a piezo device as a detector.
Knock detectors are common in cars these days. Piezoelectric accelerometers.

I think it would work (and suggested it in #26) but I'm leaning towards the optical method, since it has a history of successful use for this application.
 

djsfantasi

Joined Apr 11, 2010
9,156
The sensor is a photo transistor.

The bullet causes the light to decrease as it passes between the photo transistor and the light source. …
But the target is a plane. The photo transistor and light source form a line. There is an infinite number of lines on the plane, one of which is between the photo transistor and light source. What guarantee is there that the bullet will pass between the two, sufficiently close, to trigger a hit?

Confused
 

jpanhalt

Joined Jan 18, 2008
11,087
I have been intrigued by this question since the very first post. I hope the one-time poster is well. But as someone pointed out, lack of participation by the TS has never been a reason to stop a thread.

My initial though was static electricity. Google only returns garbage related to various myths. DuckDuckGo didn't return anything helpful either. First off, airplanes develop a static charge while in flight. Do bullets? (That's the answer I couldn't find.) There are now plastic coated bullets, which have higher velocity, and might have an even better charge.

So, why not use a static detector, such as this: http://amasci.com/emotor/chargdet.html to determine whether the target has been hit, not where it has been hit? If need be, a carbon or plastic coated target could be used.

John
 

BReeves

Joined Nov 24, 2012
410
If it wasn't winter I would preform a test, just happen to have a shooting range in my back yard. I still think sound is the answer, I would build the box I described above and hook a scope to the speaker. Chart a 22 hit from muzzle blast at 25 yards to target hit and see what signals I end up with. I'm guessing we would see a pretty large spike when the target is hit.
 

Lestraveled

Joined May 19, 2014
1,946
But the target is a plane. The photo transistor and light source form a line. There is an infinite number of lines on the plane, .........
The photo transistor has an aperture width of about 45 degrees. Look at the photo below. Sunlight illuminates the defuser panels at the top of the photo. Notice the slot openings on the top of the lower housing. This is where the photo transistors look up at the defuser panels. They detect the variation of the light when a bullet passes through the segment. One transistor watches a 45 degree segment. If you wanted to watch a larger area you probably would need more than one sensor.

 

shortbus

Joined Sep 30, 2009
10,045
I may be totally wrong on this, but hitting the "paper" has never been part of any target shooting I've ever seen or done. The object of target shooting is to hit the center of the target, not just the "paper" surrounding it. Which is how I read the original question, why would you want to know that the overall paper was hit? The center of the 'bullseye' is what is the object of target shooting is, and there has been/is another thread on how to make a target for that.
 

mcgyvr

Joined Oct 15, 2009
5,394
To me the objective is to simply sense a hit anywhere to trigger the movement of the target to another defined location.
I would simply achieve this with a simple hinged backing of sorts on the target (or frame around the target) with a microswitch. An impact would deflect the backing into the microswitch. Springs,etc.. could be used on this backing to ensure that a true bullet impact triggers the sensor and not wind movement,etc..
Of course there is the issue of this backing plate/frame being suitable to get the desired output without being a surface that would allow a ricochet or otherwise effect safety.
 

gerty

Joined Aug 30, 2007
1,305
Several years ago I was fortunate enough to get to tour the Barrett Arms facility,( the .50 caliber people) this was before the new addition. In the test range room they have a laptop computer on a shelf, on the screen is a target. On the bottom of the target is a place for the test shooters name, date, serial no.. The tester takes a new rifle from the hardcase, types serial number and name into computer. He then gets prone and fires 3 shots down the range tunnel at a target projected on the rear wall (bullet stop) 100 yds away.
Each shot shows up on the computer screen in real time, showing the point of impact on the target. When the 3 shots have been fired, and are within acceptable limits, the shooter clicks on "print" and the target prints out with 1/2" black circles where the bullet holes should be. The buyer then has a test target showing that his weapon has passed that part of QC.
I asked about the target, and neither the shooter or the man giving the tour knew anything about it. All they knew was you never have to go down range and you never run out of targets. I was able to speak to Chris Barrett afterwards and all he could tell me was " some sort of sensor eyes".
My guess is rows and columns like an old touch screen.
 

alfacliff

Joined Dec 13, 2013
2,458
If it wasn't winter I would preform a test, just happen to have a shooting range in my back yard. I still think sound is the answer, I would build the box I described above and hook a scope to the speaker. Chart a 22 hit from muzzle blast at 25 yards to target hit and see what signals I end up with. I'm guessing we would see a pretty large spike when the target is hit.
muzzle blast from a .22 at 25 yards? not very much. the op sisnt specify the calibre of bullet. I have an old 1884 springfield trapdoor rifle that I can hear the bullet hit the backstop at 100 yards away. a littloe more muzzle blast too. there are many, especially military weapons , that are louder.
 
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