Here is a proximity sensor that upgrades your robot, enabling it to find objects and navigate around in a smart fashion. Your robot will be able to avoid obstacles, solve mazes, and do a whole lot more. The Protractor works with the Pololu Zumo robot shield. It measures the amount of light bouncing off nearby objects from different directions.
The Protractor relies on a special algorithm to calculate the angles to the objects it sees. It is accurate to 10 degrees.