This is another great ball machine drill, its called the Oscillate Drill, named after a button on the ball machine which delivers the balls to different parts of the court.  Most players find it easier to hit balls when they are stationary.  This is a drill to practise hitting balls whilst on the move, as you would in a match.  You can use this drill to practise any part of your game, technique, mobility or fitness.  Play around with the settings on the ball machine to suit what part of your game you are working on and watch the top players at the end of the video to see how important it is to practise hitting balls whilst moving.