Some other hit sensor alternatives you might consider

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Arkane
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Some other hit sensor alternatives you might consider

Postby Arkane » Fri Dec 02, 2011 7:08 pm

There are some other alternatives that may not take as much clever coding (was looking at it, you have some good code there although I'm definitely not a codemaster) to determine a target hit.

The first may be through the use of a microswitch to sense a hit on the target. The army IMT (infantry target lifter) uses a motion activated microswitch to sense a hit on the target and then it cuts power to the solenoid (the IMTs lifting source) which allows the target to fall. IIRC it's a honeywell BRSA3 or something like that. The control board on the lifter itself has embedded code which tells the system to ignore the signal from the sensor for the first .75 or so seconds after the lift command - that avoids false indicators. A household alarm window sensor could probably be made to work.

Another option is through the use of a Hall type effect. If you create a magnetic field in the area of the target with the proper sensors they will be able to detect when a bullet breaks that field. The military typically uses this method for area target scoring. It is very similar to what a civilian choronograph uses sans the second set (no need to determine TOF of the projo).

A third possible option is a common household motion sensor type. You would have to finetune the discrimination and play with ignore code but it should be able to determine if the target has received a hit.

There are other methods (doppler, IR gate, etc...) but they typically require a lot more cash and effort to use.

Anyway guys, hope some of this helps.

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Awesomeness
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Re: Some other hit sensor alternatives you might consider

Postby Awesomeness » Sat Dec 03, 2011 12:24 am

That's very interesting info. This could be key to making it able to score hits/misses with some accuracy.

Can you explain how the microswitch was attached to the system?

It's also interesting that it ignores hits in the first 0.75 seconds. My thinking was that human reaction time isn't fast enough to hit it faster than that anyways, but one of the chief complaints I've gotten was about how the target wobbles some during lift, and it might make a shooter miss. My experience is that it's long done lifting before you can react, let alone aim and fire. That's just an aside.

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Arkane
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Re: Some other hit sensor alternatives you might consider

Postby Arkane » Sat Dec 03, 2011 1:52 am

The hit sensor (microswitch assembly) is mounted in the center of the bottom of the target frame. Over the years they have changed it up from the originals which were simply clamped to the bottom of the target (they tended to either fall off or register false hits). The system itself is rather elegant but I see your point with wobble. The solenoid system lifts rather smoothly (also it's not using a flat but a 3d "Ivan" target which is a bit more structurally stiff itself).

I think you could appreciably reduce the wobble by changing the actual structure of the target and it's holder. Imagine using an 18"x 36" styrofoam block or even a formed piece of plastic inserted or affixed to a central post made of cheap conduit with two smaller posts either side to provide stability. These three posts would be tacked onto a piece of square tubing bent on the ends (into almost a U shape) with a pillow block bearing either end. At the bottom center of the conduit you could drill a hole and affix the sensor. You are no longer lifting from the very center of the target but behind it which should dampen some of the vibration on lift. I can gin up some simple drawings if you'd like but I believe that setup would almost eliminate your wobble.

I concur with your thoughts about timing - the delay was something some Army Engineer came up with years ago that they use for a standard - in reality it has little to no impact on civ shooters and a delay up to a full second could probably be feasible. Anythign else and you might be pushing it. However a way to counter even having a delay could be by placing another switch that completes a circuit for the sensor when the target is at full lift.

Hope this is helping - like I said I've dorked with the .mil lifters for years and from what I've seen the audio systems always seemed to be plauged by problems in adverse weather or winds.


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