Target hit detection methods (electronic)
This is a discussion on Target hit detection methods (electronic) within the General Firearm Discussion forums, part of the Related Topics category; I want to make a pair of silhouette targets with and inner and out scoring area. I'd like to be able to "race" a buddy ...
April 24th, 2008 02:20 PM
Target hit detection methods (electronic)
I want to make a pair of silhouette targets with and inner and out scoring area. I'd like to be able to "race" a buddy from a random "go" signal and have the winner indicated. Each round would require a different, unknown number of hit "points" to consider the target neutralized. (I'm thinking inner target=2pts, outer=1pt).
The electronics are fairly easy for me, but I'm trying to figure out a good method of hit detection. Targets could be steel or something else. Light would be nice, but so would survivable.
Heres a couple of my brainstorming ideas. Pick 'em apart, expand on 'em, or give me something altogether different. Don't hold back if you don't think your idea might not be a good one. A variation of a lousy idea is often a great one.
a) Steel pendulum targets with a small bladder behind that triggers a pressure switch.
b) cardboard with tin foil on both sides (makes electrical contact)
-will there be a "bridge" of foil after the first shot, making it impossible to detect subsequent hits?
-will there be enough time for my electronics to detect the hit?
-Also, this'll have to be replaced regularly, but shouldn't cost too much.
c) your idea goes here
Last edited by Cupcake; April 25th, 2008 at 07:28 AM.
April 24th, 2008 02:20 PM
April 24th, 2008 02:30 PM
Not as fun as what you plan to build but much simpler.
Buy a Vickers Timer and shoot at IDPA targets. Shoot one at a time, time yourselves and compare that way.
Sometimes I wonder who the old man in the mirror is....
Lord, Grant me a good sword and no need to use it.
April 24th, 2008 04:05 PM
In this day of age and technology, your quest should be easily obtained. Cost and logistics will be random, but your idea is simple on the engineering level, and your knowledge of electronics/theory is very good. Field applications and fabrication could be fun and exciting, but you can probably get everything you need in a box. You do have an interesting concept here--we may revolutionize the way some competitions such as IDPA record times and scores. Have you thought about using a vehicle security system with a remote keyfob?
Anyway---here's some things of interest. You may find a device that automatically resets, or is user programmable. You could also likely find something to hook to a laptop with an alarm or something. Finding a device that will be able to withstand the magnitude of impact may be challenging.
Oceana Sensor - Impact Detection
Shock sensors - all the Manufacturers | Industry | Industrial | Suppliers | OEM | - DirectIndustry
ScienceDirect - Acta Astronautica : Impact sensor network for detection of hypervelocity impacts on spacecraft
You may be able to go with some photo-electric sensors also--one stationary, and one attached to the target stand. Upon impact, the light beam will be broken and you can wire up your visual or audible alert through a relay. You could go with low voltage AC this way also, or battery power to make it ultimately portable. Good luck with your project. I'm excited about it!
April 24th, 2008 04:10 PM
Have you thought about going low tech?
I can't find a picture of it, but I saw a three zone metal target once. You could probably make some yourself with a torch.
The silhouette was three parts that fit relatively tight together. The inner silhouette ring had two bars that would take the next out ring with them when it was hit, and the same for the second ring. If you scored a COM hit the whole thing went down. If you scored a second ring hit, the second ring and outer silhouette went down. If you missed the inner rings, only the outer went down.
Obviously this is not as flexible as what you are describing but they would work OK and probably for a lot less $$$.
April 24th, 2008 08:53 PM
You're right. Not nearly as fun. Thanks for the link though, I was hoping those targets were available so I didn't have to cut them myself.
Originally Posted by pgrass101
I try to only do low tech when I don't have the time or money to do it the fun way. It's not about easy.
Thanks for the links, I'll peruse those when I'm getting paid to. I'm not sure how a keyfob remote would fit in. I figured just a wired interface right next to the user. I could do wireless too, but it would add a few bucks and not be as reliable.
The two challenges are really finding/building the detection system, and writing the software. The software doesn't have to be that big a deal, but I want it to be able run a few different programs (games), and ultimately be expandable up to 4 targets.
April 24th, 2008 09:17 PM
Cupcake, if you're looking for fun, and a random, or pre-programmable list of points, I think there is only a few ways to go.
The best that comes to mind, is piezoelectric. Except, instead of 1-2 points, for areas of hit, you could probably program it to be levels of pressure=point value. Therefore, you could have an immovable, fixed object at a certain angle to prevent ricochets, but could do tests from a bench rest on what a sensor on the back would register at different locations and score from there. The programming would be fairly simple...All you would need is a simple adding program, with X=random, and when score = X, then trigger signal. You could easily set X or use a program to randomly decide X within a certain parameter. When score = x, you could provide a visual or auditory signal when the point level is reached. On the same note, you could take it a step further, and penalize for shots fired after the signal goes off. This could be accomplished via a decibel meter that only activates after score = X.
Anyway, that's my 2 cents...unless you patent it, and then I want more...
ETA: A soft support with a piezoelectric sensor at the top and bottom, say a tight hinge mount approx 3/5 of the way to the top of the target. When a shot is fired, depending on placement, it would compress your sensor and should give you a variable output...when the sensor reaches a certain level, it scores a hit. If it reaches a higher level it scores 2 or 3 or whatever. You could program X = between 3-30 or even 40. That would get a mag change in there as well.
April 24th, 2008 09:31 PM
A slightly cheaper, and less fun way of doing things, would be to use a limit (or momentary action push button) switch on the back of a weak spring mounted target. When the target was hit, the springs would compress actuating the limit switch. From there, it is very simple to count the signals that the limit switch sends, which would get you a score. Your program could set a random score to provide an auditory or visual signal. I still like the idea of the decibel meter to penalize for shots fired after the threat/target is neutralized.
Or you could use a bottom mount with it leaning against 2 weak springs, that would compress on impact. If a bottom, middle, and top switch are used, a hit at the top side would cause the most leverage, therefore all 3 switches would be activated, a hit COM would actuate only the top two switches, and a hit at the bottom, might or might not actuate the bottom switch. That would be another way of making it so some hits score better than other hits.
For an inner and outer scoring area, all you would have to do, is mount two targets, one a cutout of the larger one, and use 2 seperate limit switches. When either target is hit, it will compress, therefore actuating it's designated limit switch, therefore designated point value and sending your signal.
Anyway, thats my free engineering for tonight. Good luck with your project and if you need any help with the details let me know.
April 24th, 2008 10:50 PM
Hmm. How do those electronic dart boards work? They are able to distinguish between single, double and triple point areas with no problem. Of course darts don't penetrate the target. Might be worth dis-assembling one though, to get ideas.
April 25th, 2008 07:37 AM
Peizo was one of my first ideas, although rather than trying to measure an analog output, i was simply planning on having separate, concentric targets each giving their own digital signal. The big drawbacks with steel are the weight and ricochets. 3/8 steel weighs about 15lb per sqft. an 18"x24" target would come in at 45lb. If I wanted to set it at a 45degree angle to prevent ricochets, but still have an 18x24 target from the shooters' prospective, it would actually be about 63lb per target, not including any frame. Setting up 2-4 targets would be quite a chore. I'm not ruling it out as the way to go, but I'm gonna try and find something more user friendly...
April 25th, 2008 08:27 AM
I'm not sure I understand why you want a 45 degree angle? Everytime I have shot steel(which I will admit has only been a few times), they were upright targets, and bullet either fell to the ground after impact or splattered and fell to the ground.
I don't believe you will be able to make your system work with that extreme of an angle due to the fact that your bullets will be more of a ricochet than an impact. That will severely change the amount of force impacted onto the target and will make any measuring system inaccurate. Imperfections in the target would further amplify the difference in measured impact.
If you do not want to use a pressure switch, a push button, momentary action, limit switch would probably be your easiest and best bet.
It still seems like you are going to need to springmount or hingemount the target to allow some backward motion to activate any switch.
April 25th, 2008 09:53 AM
I was just reading on steel targets and even manufacturers' pages warn of the risk of ricochets at ranges of less than ten yards. I don't want to do all of my shooting that far out. Somewhere on the forum I just read a post of sixtos' where he caught a ricochet shrapnel that required minor surgery. Perhaps 45 deg isn't necessary though, maybe some lesser angle...
The peizo system should still be able to detect the hit in any case, though. But like I said, I'm not hung up on steel. I'm looking at novel solutions such as the foil-sandwiched cardboard. That would be light, fairly inexpensive, and no risk of ricochet. Other possible materials come to mind too, but gonna try the cheapest first.
April 25th, 2008 10:40 AM
I think you're on the right track to avoid steel for the transportation, weight, difficult setup, etc.
A few years back I looked at this myself. Without using steel, there are several tough problems. One of course is detection method itself, two is detection when a bullet goes through a previous hole.
However, one of the two methods I came up with but did not develop is a laser beam breaker. This concept is a laser above the target, protected by sufficient bullet stop (e.g. heavy steel angle) projects a beam downward to a reflector at the bottom of the target. This part of the target too, is protected by a bullet stop. The beam is reflected back to the top to another reflector which reflects it back down to the bottom, etc. forming a wall of light. At the end of the beam is a photo detector, say a photo transistor. If a bullet passes through the light 'wall' at any point, it interrupts the light to the sensor and hence a hit is detected. The same approach could be used by a left to right arrangement instead of the top and bottom and may be more conducive to construction.
The anticipated problem is initial beam alignment and maintaining alignment.
I think a better method would use a number of LEDs and photo sensors instead of a laser. The LEDs can have a 15° beam without external focusing. Detectors at the opposite end or side could be placed to detect interruption of the beam(s). Alignment should be much easier initially and to maintain.
Basically, this is an 'area intrusion' beam interruptor detector. The area would be defined by the wall of light. If scoring zones are needed, rather than hit-no hit, then a second set of LEDs and detectors could be used at 90° to the first. That could give a square center. If more than one scoring area is required, probably LED-detector pairs/groups could be used to define several areas.
I'm gonna be off for the summer in a week; wanna work on it?
I'm too young to be this old!
Getting old isn't good for you!
April 25th, 2008 11:26 AM
Just as an FYI, and you may already know this, but the Olympics use a system that uses microphones. They can locate the bullet very precisely and use it for scoring. No idea how hard it would be to make, but if you build one, let me know. Last I noticed they were built by SIUS AG
For an alternative to steel targets, check out Shooting Range Targets, Reactive Targets - Just Shoot Me Products
I have one of the spinners and it is very durable, though I've only shot .22 at it.
April 27th, 2008 10:46 AM
Questions to ask are:
What type of firearm?
I've shot lots of 800, 900, 1000 yard and buffalo Matches on Steel silhouettes and targets. With a good spotting scope, you'll be able to see the hits at distance due to the bullet splatter on the target, you'll also hear the hit except at the extreme distances.
At the Quigly match in MT, they have voice activated radios mounted on the back of the targets. At Alliance, NE they used two types of steel targets mounted within each other, so the different scoring shots "sound" different. They also use radios mounted to the back of the target for the longer distances. We still ended up using scopes for scoring/spotting though. Most of the other matches I've attended use simple steel silhouettes and relied on spotting scopes/sound to score hits.
At my place I shoot to 300 meters using AR500 2/3s IDPA targets. I use the same targets for pistol practice mounted on portable stands at a downward angle. The 2/3rds IDPA steel is about the same size as the -1 score on a full size IDPA Target.
You could do what you wanted to do, by either using 2/3s or 1/2 sized silhouettes mounted on a full size. I have one of my targets mounted on a long bolt with a spring shock system. It wouldn't be too hard to mount two targets together with a spring between them.
I'll tell you though, anything too complex is a pain to repaint.
A lot of the problems with steel are related to using soft "cheap" steel instead of the more expensive armor plate. Soft steel with crater/dent and then you will get splash back. Good plate mounted at an angle really works well.
Unfortunately good steel targets are around $100 a piece, but they will last a long, long time.
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