Electronic Targets - DIY?

[Home Guard]

Any progress?

[Synthasy2000]

Why not use the original palm/laptop set-up but with an airsoft pistol firing the plastic 6mm bbs??!

I want to use air gun pellets up to 12 ft/lbs not plastic BBs.

In my small experiemnts, my Palm requires some "hold" time to register a tap. I believe this hold time is too long to register the short sharp "tap" a pellet hit would produce.

I think Palms and resistive pads cannot be senses quickly enough

[Home Guard]

I want to use air gun pellets up to 12 ft/lbs not plastic BBs.

In my small experiemnts, my Palm requires some "hold" time to register a tap. I believe this hold time is too long to register the short sharp "tap" a pellet hit would produce.

I think Palms and resistive pads cannot be senses quickly enough

But them again, if you was to make you own programe for it, you could reduce the tap time? just a gess.

[Synthasy2000]

Any progress?

More investigations but more brick walls I'm afraid

As said before, the professional units use sound and microphones to extract the hit position. But they still use a roll of paper (air gun) or band of rubber (smallbore) to help produce the sound of the hit that is subsequently analysed. Ideally, I'd like to eradicate consumables.

I'm tentatively (theoretically) playing around with an optical method as this ticks most of the boxes for me, including no consumables, to register the hit position.

There are optical units coming out from the electronic target makers e.g
LS10 Laserscore from Sius-Ascor
http://www.sius.com/default.aspx
and
http://www.meyton.de/index.php

These are not to be confused with laser training aids like SCATT.

The quest is for a fast enough and cost effective enough set of optical sensors. Also there is the requirement of precision and accuracy of the pellet measurement. The professional units can be as precise as 0.1mm. I'd be happy with 1mm at the moment and I'm not looking for ISSF accreditation.

This is not going to happen overnight

[Synthasy2000]

But them again, if you was to make you own programe for it, you could reduce the tap time? just a gess.

The time is used as a means of reducing false\accidental readings. Reduce this and there'll be more erroneous readings.

Also, I believe the pad needs to be read really, really fast which is not possible with a standard resistive 4 wire pad that's read serially. Typically the reponse time is 10ms. I believe I need much faster than this.

Of course, this requires the fabled pellet energy absorbing material to put infront of the screen. This has not been solved either

[Denno]

could you not have a hard backstop with a thermal imaging camera pointed at it, providing it was zero'd with the target there must be a bit of heat generated by the pellet impact that the camera could pick up?

no idea how you would write the software to plot the shot but it should be possible.

anyway.... just a though..

[Synthasy2000]

...thermal imaging camera...

Nice left field thinking there! Especially as I have some experience with image processing thermal imagery

Also, I would have thought that the heat signature would last long enough for it to be detected even at a 10 frames per second rate which is a bonus.

However, the cheapest thermal imaging cameras are around £2000. This on its own is more than a "standard" electronic target

I've thought of using web cams too but the frame rate will be too slow. Ideally I don't want to use visible wavelengths either as you might have to illuminate the target hole. This is not good as we want a black hole to aim into.

So, we need an Infra red camera an IR illuminator. We are into night vision here and the frame rates are too low again.

[Denno]

Nice left field thinking there! Especially as I have some experience with image processing thermal imagery

Also, I would have thought that the heat signature would last long enough for it to be detected even at a 10 frames per second rate which is a bonus.

However, the cheapest thermal imaging cameras are around £2000. This on its own is more than a "standard" electronic target

I've thought of using web cams too but the frame rate will be too slow. Ideally I don't want to use visible wavelengths either as you might have to illuminate the target hole. This is not good as we want a black hole to aim into.

So, we need an Infra red camera an IR illuminator. We are into night vision here and the frame rates are too low again.

Would something like a DSLR (bottom end to keep costs down) with IR filter on it work? I have done a bit of IR photography before but not sure if it would work, or even has the potential to work. However any solution where you dont actually shoot the piece of kit measuring the shot position must be a bonus.

[Synthasy2000]

Would something like a DSLR (bottom end to keep costs down) with IR filter on it work?

In either IR or thermal case the back stop needs to be IR transparent so you can actually take a picture of it. Again we are looking for exotic materials which I want to avoid.

However any solution where you dont actually shoot the piece of kit measuring the shot position must be a bonus.

I was drinking my cup of tea when I read that and now you need to send me a screen wipe to clear up the mess from spitting it out laughing

[Rob M]

Would strain gauges be sensitive enough to record a hit? I was just thinking, a steel plate must bend slightly for a short period when a pellet hits it. Would a matrix of gauges across the back of the target plate be able to detect the pellet's position by the deformation of the plate? You might need a sort of sandwich of two layers of strain gauges, one layer going across the back plate horizontally, while the others cross it vertically, but provided they react fast enough you could maybe divine the location of the hit from them.

[Home Guard]

When they say "thinking out of the box" this is probably the definition. We all know that objects appear different when they are seen through cameras that pick up different parts of the light spectrum. Well how about if an absorbant, yet strong and spongy material is used with the camera facing the back of it (the target) and the camera may be able to pick up the contrast between where the pellet has just hit and the rest (before the spongyness turns flat again.)

Will it work????

[Synthasy2000]

Would strain gauges be sensitive enough to record a hit? I was just thinking, a steel plate must bend slightly for a short period when a pellet hits it. Would a matrix of gauges across the back of the target plate be able to detect the pellet's position by the deformation of the plate? You might need a sort of sandwich of two layers of strain gauges, one layer going across the back plate horizontally, while the others cross it vertically, but provided they react fast enough you could maybe divine the location of the hit from them.

I believe they would be sensitive enough but I think it's a case of resolution. To match the professional systems you'd need 10 gauges per mm!

I'm happy with 1mm resolution but looking at the gauges themselves, they seem to be at least 10mm x 5mm wide. This will only tell the strain in that area so we'd need lots of them say 200 to cover a 10cm by 10cm area.

A matrix using two layers of thin strips may give you the positional result required. I haven't seen long thin strain gauges though. Perhaps there's some resistive wire that would achieve the same thing.

Also I'm not sure of the response time but stain gauges are essentially resistive so with suitably fast analog to digital conversion they may be "quick" enough.

With a suitable back stop material, hopefully more than one strain gauge will respond so that the hit postion can be triangulated.

This still seems a lot of work and a lot of unknowns.

[Synthasy2000]

Well how about if an absorbant, yet strong and spongy material is used with the camera facing the back of it (the target) and the camera may be able to pick up the contrast between where the pellet has just hit and the rest (before the spongyness turns flat again.)

Will it work????

Conceptually I say yes.

However, we are back to magic, exotic materials.

We also need a back stop material that has a long life. Steel?

[Stot]

How about...


A box with an few IR LEDs in it, each side of the target area with a hole in the front of the box is covered by the target. Put 4 holes in the box for the software to use as reference points.

Buy the cheapest webcam you can get from Asda ~£5. Take it apart and remove the IR filter from the camera sensor. This is easy actually and makes the camera now sensitive to IR light. Possibly some IR material over the camera lens to cut out the daylight/visible light so the camera only sees the IR.

Hook up the web cam and point it at your target and take a shot.
Where the pellet pierced the target IR light will be seen through and be picked up by the camera and would be high contrast against the target.
Then you need some software that will do your scoring, fairly easy in something like VB if you do that kind of thing.

You can even hook it into a mic so that the software knows when to take a score reading just after it hears the gun. Only problem would be how to handle same hole shots, depending on how close the camera is you can probably pick up a change in ragged holes so it would depend on the software to handle it. If the software cant decide where the shot went, prompt the user to place the 'unknown' shots.

Total cost maybe £15-£20 + software development.

Cheers
Stot

[Synthasy2000]

How about...
A box with an few IR LEDs in it, each side of the target area

Thanks very much for your input Stot

The web cam will need to be out of pellet's harms way. Therefore it needs to be behind an IR translucent piece of back stop (exotic material?) - maybe Perspex (not exotic!) - or angled down to look at the target but then we have angular problems of hole marking.

I would have thought that repeated pellets smashing into a translucent back stop will eventually mark and degrade its optical properties. Might require constant cleaning. Something I want to avoid.

However, I'm not looking to electronic score a paper target (others might though). In my vision, I want to remove the paper target completely but also electronically score.

If you still want to use paper targets and video camera there are these systems:

http://williamson-labs.com/target.htm
http://www.roborealm.com/forum/index.php?thread_id=3451