Keeping the Ball from CMUnited-99

This paper presents preliminary results achieved during our current development of a team for simulated robotic soccer in the RoboCup soccer server [2]. We have constructed a team that plays a simplified "keepaway" game. Playing keepaway against the 1999 RoboCup champion CMUnited-99 team, our new program holds the ball for an average of 25 second with an average distance of 24 meters from the opponents end of the field. CMUnited-99 playing against itself holds the ball for an average of only 6 seconds. Here we describe the design of the keepaway team. The principal technique used is the vector sum of force-fields for governing player motion when they are not in possession of the ball.