An Omnidirectional Vision System for Soccer Robots

This thesis develops a local omnidirectional vision system for the FU-Fighters, the F180 robotic soccer team of the Freie Universität Berlin, playing in the Small Size League of RoboCup. RoboCup was founded in 1997 with the aim to foster the development of artificial intelligence and related field by organizing international games where robotic soccer teams compete. The system consists of a small PAL video camera mounted vertically on top the robots. A concave mirror placed above the camera reflects the 360 degrees of the field around the robot. The image is sent by a radio link to an external computer for processing. The omnidirectional vision system can find the ball and detect the presence of other robots on the field, classifying them as obstacles. The outline of the field is also detected and is used to determine the position of the robot. In order to be able to process 24 fps the movement of all objects is tracked, including the ball, the obstacles, and the outline of the field. For all objects, we divide the image processing task into the two following phases: Initial Search, to locate the objects on the field, and Tracking, to follow moving objects in the video stream. The key of our approach is to search for color transitions along lines. We present an algorithm for this subtask. The omnidirectional vision system is simple and inexpensive. Neither special hardware for image processing nor special optical devices have been used: The concave, parabolic mirror mounted above the camera to obtain the omnidirectional view was taken from a conventional lamp.