Adding sensors to the Zumo allows it to sense and react to its surroundings. In a sumo competition where two robots try to push each other out of a circular ring, it is important for a robot to be able to detect the border of the ring so it can avoid driving over the edge. Since standard robot sumo rings are colored black with a white border around the edge, infrared reflectance sensors like our QTR sensors <small>[https://www.pololu.com/category/123/pololu-qtr-reflectance-sensors lien pololu]</small> are great for this purpose. The Zumo Reflectance Sensor Array {{polpl|1419}} conveniently mounts six of these sensors in a module designed to plug directly into the front expansion header of the Zumo Shield (note: the {{pl|448|pre-assembled version of the Zumo robot}} {{polpl|2510}} ships with this reflectance sensor array already installed). | Adding sensors to the Zumo allows it to sense and react to its surroundings. In a sumo competition where two robots try to push each other out of a circular ring, it is important for a robot to be able to detect the border of the ring so it can avoid driving over the edge. Since standard robot sumo rings are colored black with a white border around the edge, infrared reflectance sensors like our QTR sensors <small>[https://www.pololu.com/category/123/pololu-qtr-reflectance-sensors lien pololu]</small> are great for this purpose. The Zumo Reflectance Sensor Array {{polpl|1419}} conveniently mounts six of these sensors in a module designed to plug directly into the front expansion header of the Zumo Shield (note: the {{pl|448|pre-assembled version of the Zumo robot}} {{polpl|2510}} ships with this reflectance sensor array already installed). |