I am working on what I hope is a simple project as I am dabbling in this field. I am trying to create a target (in the shape of a box) roughly 1m by 0.5 meters into which soccer balls will be shot (diameter of between 10 and 25 cm). I want to be able to detect any ball which passes through the opening of the goal. I have looked at PIR sensors but am not sure if they will be able to detect a fast moving object (potentially up to about 3 cm per sec). Another concern I have is that it may be possible for a ball to remain in the sensor(s) field if it hits the edge of the goal and does not pass cleanly through and exit the sensor field. If this happens I would want to make sure that the sensor(s) could pick up the motion of another ball which passes through the goal on either side or above the stationary ball.

The idea is to connect the sensors so that each "goal" is detected and that any miss (default if no goal is scored within a set time frame) is also detected.

I have read some similar questions regarding moving bullets and even soccer goals but these issues were not addressed. Also, I would like this to be outdoor usable, meaning weather resistant. I have looked at some weather proof ultrasonic range finders, although with any sensor I am concerned with dirt and other materials from obstructing the sensor(s).

Any help would be greatly appreciated.