Lasers for Strike Zone

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pfranks
 
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Joined: Mon Oct 31, 2022 6:20 pm

Lasers for Strike Zone

Post by pfranks »

Hello, please pardon me if I'm in the wrong area for this question.

Hello
My name is Pat Franks and I came across your company while looking for some lasers for a project. I am part of a training staff of baseball and softball umpires for Little League. We have been wanting to build something that would assist us in training a plate umpire on calling balls and strikes. We would use lasers to box in the strike zone and when a pitch was delivered, if it broke the laser grid (both vertical and horizontal, a light would come on to tell the trainer the pitch was a strike and compare it to what the umpire in training verbalized it was. See attached grid another person built. The lasers top and bottom would represent the width of the plate and the side lasers would represent the zone of the batter (armpits to knees). A pitch can break the laser (top and bottom) and be over the plate, but if it is too high and above the armpits of the batter, it wouldn't break the other lasers and thus be a ball. Our desire is to have two lights attached and if it broke the beams of both vertical and horizontal sets of lasers, it would flash one specific bulb (say green in color) but if it only broke one of the sets of lasers, it would flash another bulb (say red in color). I searched the forum and nothing came up on my search words. Can someone either direct me to something or let me know their thoughts on it? Thanks.
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adafruit_support_mike
 
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Re: Lasers for Strike Zone

Post by adafruit_support_mike »

That's basically a collection of break-beam sensors:

https://www.adafruit.com/?q=break-beam&sort=BestMatch

Short range break-beam sensors tend to use IR LEDs, but you can use lasers for greater distance. We have laser diodes in stock:

https://www.adafruit.com/category/118

and on the receiver side you can use a simple photosensor like these:

https://www.adafruit.com/product/2748

A microcontroller can read the light sensors like a switch, and a microcontroller can scan a dozen or so light sensors faster than a baseball can cross the plane of the lasers.. at 100mph, it takes about 1.65ms for a baseball to travel its 2.9" diameter.

A microcontroller can read several GPIO pins simultaneously, and the read takes a few microseconds at most. Even assuming 50us per read, the microcontroller could sense a 100mph fastball in slices less than 0.1" thick.

It looks like you have a 7x8 grid in the photo above, which would require 15 sensors and GPIO pins. For that number, it would probably be a good idea to use a Grand Central to get enough pins:

https://www.adafruit.com/product/4064

The Grand Central uses a 32-bit microcontroller, and microcontrollers map their GPIO pins to registers in memory. That means you could read up to 32 GPIO pins at once, if you wanted more density in your grid.

The Grand Central also has enough GPIO pins to light LEDs on the rows and columns that see the ball, so you know exactly where it came through.

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