Method of calibrating a heading reference system

摘要

A method of calibrating a vehicle's heading system, such as the attitude heading and reference system of an aircraft or the heading system of a ship, positioned along the Earth's surface involves obtaining both actual and theoretical readings for the magnetometer of the heading system, and comparing these values to obtain calibration values for the heading system which are then averaged to obtain a universal average gain and offset for the magnetometer. The vehicle may be repositioned, such as to North, South, East, and west magnetic headings, with the procedure repeated at each of these headings, and the calibration values averaged, further increasing the accuracy.

主权项

1. A method for calibrating an aircraft attitude and reference heading system comprising at least one magnetometer, the method comprising the steps of:
selectively positioning an aircraft on the ground along the Earth's surface; obtaining an actual reading from the at least one magnetometer at a selected first magnetic heading for the positioned aircraft while the aircraft is stationary on the ground; obtaining a set of theoretical magnetic field properties of the Earth at a location of the positioned aircraft, the obtained theoretical magnetic field properties comprising theoretical values for a horizontal intensity and a vertical intensity of the magnetic field at the location of the positioned aircraft; computing a theoretical reading for the magnetometer at the first magnetic heading of the positioned aircraft based on at least the first magnetic heading, the associated attitude for the positioned aircraft, and the obtained theoretical values for the magnetic field at the location of the positioned aircraft; comparing the obtained actual reading from the at least one magnetometer for the positioned aircraft at the first magnetic heading with the obtained theoretical magnetometer reading at the first magnetic heading for providing a first calibration value for the heading system at the first magnetic heading for the positioned aircraft; selectively positioning the aircraft so as to select at least a second magnetic heading and repeating the obtaining, computing, and comparing steps for the at least second magnetic heading to provide at least a second calibration value for the heading system; utilizing the first and the at least one second provided calibration values at the first and the at least one second magnetic headings of the aircraft to calculate a universal average gain and offset for the at least one magnetometer based on averaging the first and the at least one second calibration values; and utilizing the universal average gain and offset to universally calibrate the heading system with respect to measurement errors.