This is an airgun pellet trap:
I fire small metal pellets at it (4.5mm = .177" in diameter) at up to 120 m/s = 390 fps.
What are my options for detecting the X / Y position at which it enters the target?
Does it make it easier if I only need to know the distance from the center? (the score)
Right now my pellets are lead-free, but not ferromagnetic (they don't stick to a magnet.) If I were to get ferromagnetic pellets, would I have more options? Some inductive or otherwise electromagnetic effect maybe?
Right now I can think of:
A camera mounted on a tripod, that would compare successive pictures and detect any differences on the target paper. Downsides: it would need decent computing power (at least a Raspberry Pi) and it would probably miss a pellet passing right through a hole carved by the previous pellet. It would also not work as well against the black bands.
Two laser or CCD scanners, such as repurposed barcode scanners, mounted along the target edges at 90° to each other. Downsides: the optics would have to be tweaked in the case of CCD; they would probably need a white reference background on the other side; and they would have to be very fast, because the pellets are moving very fast.
Any other ideas?
Can I use antennas mounted along the edge, to detect some kind of electromagnetic effect? What if produce an electromagnetic field? Would the metal pellet interact with it in any noticeable way? Would a ferromagnetic pellet do so?
Can I use two supersonic distance detectors, mounted at 90° to each other? Can they detect such a small object, traveling fast?