Building Smart LEGO MINDSTORMS EV3 Robots

Rotation sensor

This second sensor is not an external sensor like the IR sensor. Rather, it is located inside the EV3 motor. The Falcon makes extensive use of the rotation sensor (also referred to as an encoder) built into the medium motor that is used for steering (port A). The encoder provides information about the motor's current position in degrees, which the Falcon's program uses to coordinate the steering and facilitate its return-to-center feature. In short, the built-in encoder provides the steering with enough intelligence and makes the Falcon easier to drive.