Obstacle Detection, Identification and Sharing on a Robotic Soccer Team

When building a representation of the environment for a robot in a multi-agent application, as is the case of robotic soccer, sensor and information fusion of several elements of the environment are an important task. To build an increasingly better world model, one of the aspects that one should consider is the treatment of obstacles. This paper gives an insight of the general steps necessary for a good obstacle representation in the robot world model. A first step is the visual detection of the obstacles in the image acquired by the robot. This is done using an algorithm based on radial search lines and colour-based blobs detection, where each obstacle is identified and delimited. After having the visually detected obstacles, a fusion with a-priori known information about the obstacles characteristics allows the obstacle separation and filtering, so that obstacles that don't fill the criteria are discarded. With the position information shared by team mates, the matching of the obstacles and the team mates positions is also possible, thus identifying each of them. Finally, and with the purpose of having a team world model as coherent as possible, the robots are able to share the obstacle information of each other. The work presented in this paper was developed for the CAMBADA robotic soccer team. After achieving the 1st place in the Portuguese robotics open Robotica2008 and in the Robocup2008 world championship, the correct treatment of obstacles was one of the new challenges proposed among the team to improve the performance for the next competitions.