METHOD OF OPERATING A MAGNETIC COMPASS ON A MACHINE

A method of determining the heading of an excavator at a worksite uses a magnetic field sensor, mounted on the excavator, inclinometers that provide an indication of the pitch and roll of the excavator, a gyroscopic sensor that senses the rotational rate of the excavator about the Z axis of the magnetic field sensor, and a processor circuit, having an associated memory. A calibration table of data is created and stored using the gyroscopic sensor as the excavator is rotated at a uniform velocity. The sensed indications of the magnetic field from the coordinate reference frame of the sensor are transformed to the local level plane coordinate reference frame using the outputs from the inclinometers.