Soccer Behaviors for Humanoid Robots

As the RoboCup Humanoid League moves from less demanding competitions to soccer games, the complexity of behavior control increases significantly. This calls for structured behavior engineering. In this paper, we describe the design of the behavior control software for the Humanoid League team NimbRo. The control software is based on a framework that supports a hierarchy of reactive behaviors. It is structured both as an agent hierarchy (joint – body part – player – team) and as a time hierarchy. The speed of sensors, behaviors, and actuators decreases when moving up in the hierarchy. The lowest levels of this framework contain position control of individual joints and kinematic interfaces for body parts. At the next level, basic skills like omnidirectional walking, kicking, and getting-up behaviors are implemented. These are used by soccer behaviors like searching for the ball, approaching the ball, avoiding obstacles, and defending the goal. Finally, on the team level, the robots communicate via a wireless network to share information about the world state and to negotiate roles like attacker and defender. Our robots performed well at the RoboCup 2006 competition, which took place in Bremen, Germany. The KidSize robots won the Penalty Kick competition and came in second in the overall Best Humanoid ranking, next only to the titleholder, Team Osaka.