Each of the robots is fitted with the same color tops and no attempts are made to differentiate them via color. Experience has shown that in order to differentiate 5 different robots by color, 5 different colors are needed. However, inevitable variations in lighting conditions over the area of the field are enough to make this detection mechanism unreliable.
Data association addresses the problem of retaining robot identification in subsequent frames. We devised an algorithm to retain association based on the spatial locations of the robots. During consecutive frames, association is maintained by searching for minimum distance criteria. Current robot positions are matched with the closest positions from the previous frame.