VEHICLE SENSOR

Methods and apparatus forming part of a vehicle sensor system () comprising a plurality of sensor units (-) and a controller (). A sensor unit comprises: a motion sensor () configured to determine a first speed of the sensor unit; and a transmitter () configured to transmit first identification data to the controller if the first speed of the sensor unit exceeds a first threshold. The motion sensor is further configured to determine a second speed of the sensor unit a period of time after determination of the first speed of the sensor unit, and the transmitter is configured to transmit to the controller second identification data if the second speed of the sensor unit exceeds a second threshold. The controller comprises: a receiver () configured to receive the first identification data, and further configured to receive the second identification data a period of time later; and a sensor unit assigner () configured to assign the sensor unit to the controller if the first identification data and the second identification data are received.