# PCB Heaven

## General Category => Your projects => Topic started by: cheerio on April 08, 2012, 19:52:42 PM

Title: Digital Target score
Post by: cheerio on April 08, 2012, 19:52:42 PM
Hi,
i shoot Airguns and stuff. I was wondering how i could count the target score with a circuit. While searching the web i found this:

Does anyone have an idea how they do this?

The projectile travels 0.15mm/us on impact.
Title: Re: Digital Target score
Post by: kam on April 09, 2012, 08:13:49 AM
this target detects and measures the position where you shoot with the rifle and then tells you the score? Or detects the shooting projectile when moving? :o
Title: Re: Digital Target score
Post by: cheerio on April 09, 2012, 11:26:55 AM
It must detect the projectile while moving. Because otherwise it won't detect an impact on the same location twice.

edit:
they use 3 sensors. so it must be a triangular positioning algorithm. But if they use laser distance measurement it would be pretty complex. isn't there a better/cheaper/simpler way?
Title: Re: Digital Target score
Post by: kam on April 10, 2012, 21:53:08 PM
i cannot even think of other way, nor could i believe that there could be a way to do it with lasers. I mean, they must be bloody fast to scan the whole area for the projectile!
Title: Re: Digital Target score
Post by: cheerio on April 11, 2012, 02:40:43 AM
Title: Re: Digital Target score
Post by: George on April 12, 2012, 13:20:01 PM
Each laser unit will have a detector so that each particular laser will be able to detect a penetration of it's beam and the distance to the point of penetration.
http://en.wikipedia.org/wiki/Laser_rangefinder

Each laser will scan an arc that covers the target area.

The by trigonometry, the location of where the projectile penetrated the three beams can be calculated. Basically, knowing the location of the three lasers equals three circles, where they intersect, is the spot where the projectile passed.
http://en.wikipedia.org/wiki/Trilateration
http://en.wikipedia.org/wiki/Multilateration

got this from a photonics dude, hope it helps

Cheers

Title: Re: Digital Target score
Post by: kam on April 12, 2012, 15:24:05 PM
the trick is that each laser has to scan an area rather than a line, so i suppose there is some sort of moving mirror like those in bar code readers, to deflect the laser and scan the area...