Creation of cooperative robot teams for complex tasks requires not only agents that can function well individually but also agents that can coordinate their actions. The paper presents several methods for collaboration and coordination in a team of soccer-playing robots. In our approach, fixed collaborative supporting behaviours allow for robots to aid each other and decrease interference. Coordinated dynamic role assignment then permits the robots to take advantage of their current location on the field. We present a robust protocol for dynamic role assignment based upon multithreaded computer programming that mitigates the risk often associated with initiating a role change in a distributed system. This protocol is independent from the manner in which the decision to switch roles is made and would therefore support any approach to role assignment. The individual and supporting behaviours were tested at RoboCup 2001 in Seattle, Washington.

We describe a behavior-based control system that enables a non-holonomic robot to push an object from an arbitrary starting position to a goal location through an obstacle field. The approach avoids the need for maintaining an internal model of the target and obstacles and the potentially high computational overhead associated with traditional path planning approaches for non-holonomic robots. The motor schema-based control system was prototyped in simulation, then evaluated empirically on mobile robots. The approach was demonstrated in two pushing tasks: box pushing and ball dribbling. Using the same generalized control system, a robot is able to successfully push a box through a static obstacle field and dribble a ball into a goal during RoboCup soccer matches. In both cases the robot is able to react quickly and recover from situations where it loses control of its target with due to its own motion or interference with others. Quantitative experimental results for reliability in box pushing are included.