METHOD AND SYSTEM FOR COMPENSATING FOR SOFT IRON MAGNETIC DISTURBANCES IN MULTIPLE HEADING REFERENCE SYSTEMS

摘要

A method and system for compensating for soft iron magnetic disturbances in multiple heading reference systems, such as aircraft heading reference systems, integrated standby units; or vehicle inertial systems, detects and provides a heading correction signal to the error prone heading reference system when a detected difference in value between a gyro heading relative to magnetic north and a magnetometer reading during a defined measurement period exceeds a predetermined acceptable threshold value of change, such as one based on the expected gyro drift over that period. Upon receipt of the heading correction signal, the gyro heading is adjusted to maintain an accurate heading relative to true magnetic north. If this threshold value is not exceeded, then the magnetometer reading is used for the heading value. This method is periodically repeated in order to continually maintain an accurate heading and may be employed for each heading measurement axis.

主权项

1. A method for compensating for soft iron magnetic disturbances in a vehicle that comprises a first heading reference system which includes a first magnetometer coupled to a first heading gyro and a second heading reference system which includes a second magnetometer coupled to a second heading gyro, wherein the first magnetometer and the second magnetometer are installed in different locations within the vehicle, the method comprising:
receiving magnetometer data from the first magnetometer and the second magnetometer; generating a first value and a second value indicating a change of a magnetic field based on the first magnetometer and the second magnetometer, respectively, during a detection period; determining a difference of change of the magnetic field between the first value based on the first magnetometer and the second value based on the second magnetometer; in response to determining that the difference of change of the magnetic field exceeds a threshold value:
generating a first pair of heading values utilizing the first magnetometer and the first heading gyro, and a second pair of heading values utilizing the second magnetometer and the second heading gyro;generating a first heading error value based on the first pair of heading values and a second heading error value based on the second pair of heading values;comparing the first heading error value associated with the first heading reference system and the second heading error value associated with the second heading reference system to an error threshold; andupon determining that either the first heading error value or the second heading error value exceeds the error threshold, utilizing a gyro heading value from the first heading gyro or the second heading gyro to calibrate the first magnetometer associated with the first heading reference system or the second magnetometer associated with the second heading reference system.