Normally, our keeper will stop the ball on the goal line. However, sometimes, the keeper has too little time to move there and stand still. This is when we try to intercept the ball with an overshoot computation. In essence, instead of telling the robot to stand still at a certain point to stop the ball, we tell it to be at a certain point at a certain time with whatever speed it will have then.
We do this by looking at the ball trajectory and calculating whether we can intercept the ball when yeeting our keeper towards the ball trajectory.