Method and apparatus for providing automatic lane calibration in a traffic sensor

A sensor for obtaining vehicular traffic data, the sensor comprising:

• at least one antenna for transmitting radiation to a vehicle and for receiving the radiation reflected back from the vehicle;
• a transceiver circuit for electrically driving the antenna;
• a processor unit for driving and processing electrical signals from the transceiver circuit plate to obtain vehicular traffic data, wherein the processor unit is operable to define ranges of centers of traffic lanes by performing the steps of
• a) providing a set of lane center variables representing the ranges of the centers of the traffic lanes from the traffic sensor;
• b) initializing each lane center variable in the set of lane center variables to have an associated starting range value;
• and then,
• c) updating the set of lane center variables by, for each vehicle in a plurality of vehicles,
• i) detecting the vehicle,
• ii) determining an associated lane center variable having an associated lane center range value closest to the vehicle,
• iii) estimating a vehicle displacement from the associated lane center range value, and
• iv) calculating a new lane center range value for the associated lane centre variable using the associated lane center range value and the vehicle displacement.