Realization of a ball passing strategy for a robot soccer game: a case study of integrated planning and control

Ball passing is an elementary and frequently employed human soccer skill. This paper examines the realization and visualization of ball passing, a low level move-to-ball behavior of a soccer robot, in a robot soccer game. A case study of three mechanically identical mobile robots with a formation ready to pass a ball cyclically in a zigzag pattern is examined. We build a control command driven mobile robot motion simulator with a controller and dynamics of mobile robots, not only nonholonomic kinematic constraints to simulate the motion of a soccer robot driven by wheels torques to generate wheels accelerations, to update the robot position and orientation at successive time instants. Kick motion follows a physical law, and a simplified collision check and response model is utilized for the efficient detection of the hitting a robot with the ball or other robots. The realization of specific ball passing strategy to drive each soccer robot in a position to receive a pass includes three levels of organization, coordination, and execution: careful integrated design of a dynamic formation and role change scheme, ball position estimation, and coordinated trajectory (i.e. path and velocity) planning and tracking control. Simulations are performed to illustrate the feasibility of the realization of ball passing among three robots, implemented by a software program for coordinated trajectory planning and tracking control in the developed simulator.