Positioning sensor

hello, i am currently working on a project that enforces some rules of the drinking game 'beer pong". I want to use a microcontroller such as an arduino to detect if someone throws in the right way. When you throw a ball you can't move your elbow over the edge of the table. So i want to attach a sleeve with a piece of hardware like a sensor to a persons elbow, and when this piece moves over the plane that is the edge of the table, i want to be able to detect it. Does anyone have anyone know wich sensor i can use to detect when something moves true this plane?

After a few beers, does this matter any more ?

:rofl:

beerpong isn't just a game, it's a lifestile. I'm from belgium and it's a big deal

  • Project a LOW Power Line Laser from the table top to the ceiling.

  • Light sensor on elbow beeps when it crosses the laser line.

Check the safety of these lasers first !

EDIT

:thinking:

Lasers and beer probably don't go together well.

Does it matter which direction the elbow is moving?