We are excited to now offer a reflectance sensor array designed specifically for use with the Zumo robot. It features six separate reflectance sensors, each consisting of an IR emitter coupled with a phototransistor that responds based on how much emitter light is reflected back to it. The two outside sensors are positioned at the very edges of the module to maximize their usefulness as edge detectors (e.g. for seeing the white boundary of a sumo ring or identifying the edge of a table) while the four inner sensors are closer together so that the Zumo can excel at line following.
The sensor array plugs into the front expansion header of the Zumo shield, which provides it with power and the necessary I/O connections. The default I/O connections are to pins that are otherwise unused by the Zumo shield, but the sensor module makes it possible to remap these pins or disconnect specific sensors altogether to free up I/O lines.
For more information, please see the Zumo reflectance sensor array product page.