Patent ID: 7324906
Filing Date: 2008-01-29
Classification: G01C

Abstract:
1. An azimuth data computing method comprising the steps of: inputting a signal from a geomagnetic sensor to measure a magnetic field which may be a mixture of a geomagnetic field and other magnetic field causing an offset, thereby providing measurement data of the magnetic field, which is represented by a set of coordinate components corresponding to a set of different axes of a given coordinates space; calculating an offset value of the offset based on a plurality of the measurement data which are measured successively from the signal inputted from the geomagnetic sensor; comparing the plurality of the measurement data used for calculating the offset value with one another in terms of the coordinate components of each axis to obtain a difference between a maximum value and a minimum value of the coordinate components for each axis; judging the calculated offset value to be valid when the difference obtained for each axis is greater than a predetermined threshold difference; updating a previous offset value based on the offset value currently judged to be valid; and correcting the measurement data which is provided after the previous offset value has been updated, according to the updated offset value and computing azimuth data according to the corrected measurement data.