Magnetic sensor calibration for aircraft

Patent metadata

Field	Value
Publication number	US-2016178371-A1
Application number	US-201414573657-A
Country	US
Kind code	A1
Filing date	Dec 17, 2014
Priority date	Dec 17, 2014
Publication date	Jun 23, 2016
Grant date	—

Abstract

A method of magnetic sensor calibration for aircraft comprises obtaining attitude data, heading angle data, position data, and date information; inputting the position data and date into an earth magnetic field (EMF) model and into an EMF model correction map; inputting the attitude and heading angle data into a NOLL to body frame transformation module; outputting an EMF model vector from the EMF model; outputting an EMF correction vector from the EMF model correction map; compensating the EMF model vector with the EMF correction vector to produce a corrected EMF model vector; inputting the corrected EMF model vector into the transformation module; inputting magnetic field measurements data into a calibration processing unit; inputting true earth magnetic field data from the transformation module into the processing unit; computing compensation coefficients in the processing unit based on the magnetic field measurements and the true earth magnetic field; and storing the compensation coefficients.

First claim

What is claimed is:

1 . A method of magnetic sensor calibration for an aircraft, the method comprising:
obtaining attitude data, heading angle data, position data, and date information for the aircraft; inputting the position data and the date information into an earth magnetic field model; inputting the position data and the date information into an earth magnetic field model correction map; inputting the attitude data and the heading angle data into a north oriented local level (NOLL) to body frame transformation module; outputting an earth magnetic field model vector from the earth magnetic field model; outputting an earth magnetic field model correction vector from the earth magnetic field model correction map; compensating the earth magnetic field model vector with the earth magnetic field model correction vector to produce a corrected earth magnetic field model vector; inputting the corrected earth magnetic field model vector into the NOLL to body frame transformation module; inputting magnetic field measurements data into a calibration processing unit; inputting true earth magnetic field data from the NOLL to body frame transformation module into the calibration processing unit; computing compensation coefficients in the calibration processing unit based on the magnetic field measurements data and the true earth magnetic field data; and storing the compensation coefficients in a memory unit.

2 . The method of claim 1 , further comprising:
sending calibration parameters from the calibration processing unit to a quality measures module; and outputting a calibration status from the quality measures module.

3 . The method of claim 1 , further comprising:
outputting the stored compensation coefficients to a magnetic sensor compensation module; inputting the magnetic field measurements data into the magnetic sensor compensation module; computing a compensated magnetic field measurement based on the magnetic field measurements data and the compensation coefficients; and outputting the compensated magnetic field measurement.

4 . The method of claim 1 , wherein the earth magnetic field correction map provides existing observed differences between the earth magnetic field model and actual earth magnetic field at a given location.

5 . The method of claim 1 , wherein the magnetic field measurements data are from at least one magnetometer in the aircraft.

6 . The method of claim 4 , wherein the attitude data and the heading angle data are obtained from an attitude and heading reference system in the aircraft.

7 . The method of claim 4 , wherein the attitude data, the heading angle data, and the position data are obtained from a global positioning system attitude and heading reference system in the aircraft.

8 . The method of claim 1 , wherein the attitude data and the heading data are obtained after one or more in-flight maneuvers by the aircraft.

9 . The method of claim 1 , wherein the calibration processing unit includes a Kalman filter that computes the compensation coefficients to correct the magnetic field measurements data.

10 . The method of claim 1 , further comprising:
obtaining inertial measurement data for the aircraft; and inputting the inertial measurement data into the calibration processing unit.

11 . A system for magnetic calibration of an aircraft, comprising:
a calibration processing unit in the aircraft; a memory unit in operative communication with the calibration processing unit; at least one magnetic sensor on the aircraft and in operative communication with the calibration processing unit; an earth magnetic field model configured to receive position and date information for the aircraft and output an earth magnetic field model vector; an earth magnetic field model correction map configured to receive position and date information for the aircraft and output an earth magnetic field model correction vector; an adder configured to combine the earth magnetic field model vector with the earth magnetic field model correction vector to produce a corrected earth magnetic field model vector; a north oriented local level (NOLL) to body frame transformation module configured to receive attitude data and heading angle data for the aircraft, and receive the corrected earth magnetic field model vector; and a magnetic sensor compensation module configured to receive magnetic field measurements data from the magnetic sensor; wherein the calibration processing unit is configured to:
receive the magnetic field measurements data from the magnetic sensor;
receive true earth magnetic field data from the NOLL to body frame transformation module;
compute compensation coefficients based on the magnetic field measurements data and the true earth magnetic field data;
store the compensation coefficients in the memory unit; and
output the stored compensation coefficients to the magnetic sensor compensation module.

12 . The system of claim 11 , further comprising a quality measures module configured to receive calibration parameters from the calibration processing unit and output a calibration status.

13 . The system of claim 11 , wherein the magnetic sensor compensation module is configured to:
compute a compensated magnetic field based on the magnetic field measurements data and the compensation coefficients; and output the compensated magnetic field.

14 . The system of claim 11 , wherein the at least one magnetic sensor comprises at least one magnetometer.

15 . The system of claim 11 , wherein the attitude data and the heading angle data are from an attitude and heading reference system in the aircraft.

16 . The system of claim 11 , wherein the attitude data, the heading angle data, and the position data are from a global positioning system attitude and heading reference system in the aircraft.

17 . The system of claim 11 , wherein the calibration processing unit includes a Kalman filter that computes the compensation coefficients.

18 . A method of magnetic sensor calibration for an aircraft, the method comprising:
obtaining attitude data, heading angle data, position data, and date information for the aircraft; inputting the position data and the date information into an earth magnetic field model; inputting the position data and the date information into an earth magnetic field model correction map; outputting an earth magnetic field model vector from the earth magnetic field model; outputting an earth magnetic field model correction vector from the earth magnetic field model correction map; compensating the earth magnetic field model vector with the earth magnetic field model correction vector to produce a corrected earth magnetic field model vector; inputting the attitude data and the heading angle into a calibration processing unit; inputting magnetic field measurements data into the calibration processing unit; inputting the corrected earth magnetic field model vector into the calibration processing unit; computing compensation coefficients in the calibration processing unit based on the magnetic field measurements data and the corrected earth magnetic field model vector; and storing the compensation coefficients in a memory unit.

19 . The method of claim 18 , further comprising:
outputting the stored compensation coefficients to a magnetic sensor compensation module; inputting the magnetic field measurements data into the magnetic sensor compensation module; computing a compensated magnetic field measurement based on the magn

Assignees

• Honeywell Int Inc

Inventors

• Morrison John R
• Bageshwar Vibhor L
• Kreichauf Ruth Dagmar
• Kana Zdenek

Classifications

• G01C17/38 Primary

  Testing, calibrating, or compensating of compasses · CPC title

• G01R33/0035

  Calibration of single magnetic sensors, e.g. integrated calibration · CPC title