Magnetic anomaly tracking for an inertial navigation system

Patent metadata

Field	Value
Publication number	US-9857179-B2
Application number	US-201414586207-A
Country	US
Kind code	B2
Filing date	Dec 30, 2014
Priority date	Dec 30, 2014
Publication date	Jan 2, 2018
Grant date	Jan 2, 2018

Abstract

One example includes an inertial navigation system (INS). The INS includes a navigation controller configured to generate inertial data associated with motion of a vehicle based on at least one navigation sensor configured on the vehicle and based on magnetic anomaly data. The INS also includes a magnetic anomaly INS-aiding system comprising a plurality of magnetometers distributed in a respective plurality of locations on the vehicle. The magnetic anomaly INS-aiding system can be configured to generate the magnetic anomaly data based on magnetic field measurements of a fixed magnetic anomaly at each of the plurality of magnetometers.

First claim

What is claimed is:

1. An inertial navigation system (INS) comprising:
a navigation controller configured to generate inertial data associated with motion of a vehicle based on at least one navigation sensor configured on the vehicle and based on magnetic anomaly data;
a magnetic anomaly INS-aiding system comprising a plurality of magnetometers distributed in a respective plurality of locations on the vehicle, the magnetic anomaly INS-aiding system being configured to generate the magnetic anomaly data based on magnetic field measurements of a fixed magnetic anomaly at each of the plurality of magnetometers; and
a magnetometer controller to implement a correlation algorithm based on the magnetic field measurements, the correlation algorithm being configured to provide feature matching on each of the magnetic field measurements to substantially suppress noise associated with the magnetic field measurements and provide error correction with respect to detection of the fixed magnetic anomaly, wherein the magnetometer controller is further configured to generate a confidence score associated with the detection of the fixed magnetic anomaly based on the correlation algorithm, and wherein the magnetometer controller implements the confidence score and the magnetic field measurements in real-time to calculate a velocity of the vehicle relative to an Earth coordinate frame.

2. The system of claim 1 , wherein the plurality of magnetometers are located at the plurality of locations at predetermined distances with respect to each other, such that the magnetic anomaly INS-aiding system is configured to generate the magnetic anomaly data based on magnetic field measurements at each of the plurality of magnetometers with respect to the predetermined distances.

3. The system of claim 1 , wherein the plurality of magnetometers comprises a first magnetometer located at a fore-section of the vehicle and a second magnetometer located at an aft-section of the vehicle, the first and second magnetometers being located a predetermined distance with respect to each other along a substantially central axis of the vehicle corresponding to a direction of forward vehicle motion.

4. The system of claim 3 , wherein the plurality of magnetometers further comprises a third magnetometer located on a port side of the vehicle and a fourth magnetometer located on a starboard side of the vehicle, the third and fourth magnetometers being located a predetermined distance with respect to each other along an axis of the vehicle that is approximately orthogonal with respect to the substantially central axis.

5. The system of claim 1 , wherein the magnetic anomaly data is implemented by the navigation controller to calculate a velocity of the vehicle relative to an Earth coordinate frame based on the magnetic field measurements at each of the plurality of magnetometers.

6. The system of claim 1 , wherein the magnetometer controller is further configured to receive the magnetic field measurements from each of the respective plurality of magnetometers and to generate the magnetic anomaly data as a composite magnetic field measurement associated with a location of the fixed magnetic anomaly based on a comparison of the magnetic field measurements.

7. The system of claim 1 , wherein the plurality of magnetometers are distributed in an at least two-dimensional array along the vehicle, wherein the magnetic anomaly INS-aiding system is configured to calculate at least one of velocity, acceleration, orientation, and position in at least two coordinate frame axes based on the at least two-dimensional array of magnetometers.

8. The system of claim 1 , wherein the at least one navigation sensor configured on the vehicle comprises at least one of a gyroscope and an accelerometer, wherein the navigation controller is configured to substantially mitigate errors associated with the at least one of the gyroscope and the accelerometer based on the magnetic anomaly data.

9. A method for providing magnetic anomaly detection assistance in an inertial navigation system (INS) of a vehicle, the method comprising:
obtaining magnetic field measurements associated with a fixed magnetic anomaly relative to an Earth coordinate frame via a plurality of magnetometers arranged in an array about the vehicle;
providing magnetic anomaly data associated with the magnetic field measurements relative to predetermined distances between a plurality of locations associated with the respective plurality of magnetometers about the vehicle;
implementing a correlation algorithm based on the magnetic field measurements;
comparing the magnetic field measurements based on the correlation algorithm to provide feature matching on each of the magnetic field measurements to substantially suppress noise associated with the magnetic field measurements and provide error correction with respect to detection of the fixed magnetic anomaly;
generating a confidence score associated with the detection of the fixed magnetic anomaly based on the correlation algorithm; and
calculating a velocity of the vehicle relative to an Earth coordinate frame via the INS based on the confidence score and the magnetic field measurements in real-time.

10. The method of claim 9 , further comprising generating inertial data associated with motion of a vehicle based on at least one navigation sensor configured on the vehicle and based on the magnetic anomaly data, the inertial data comprising the at least one of the velocity and the position of the vehicle.

11. The method of claim 9 , further comprising:
generating inertial data associated with the vehicle based on at least one of a gyroscope and an accelerometer; and
implementing error correction of the inertial data associated with the at least one of the gyroscope and the accelerometer based on the magnetic anomaly data.

12. An inertial navigation system (INS) comprising:
a navigation controller configured to generate inertial data associated with a velocity of a vehicle relative to an Earth coordinate frame based on at least one navigation sensor configured on the vehicle and based on magnetic anomaly data;
a magnetic anomaly INS-aiding system comprising a plurality of magnetometers distributed in an array at a respective plurality of locations on the vehicle having respective predetermined distances with respect to each other, the magnetic anomaly INS-aiding system being configured to generate the magnetic anomaly data based on magnetic field measurements of a fixed magnetic anomaly at each of the plurality of magnetometers with respect to the predetermined distances; and
a magnetometer controller configured to implement a correlation algorithm based on the magnetic field measurements, the correlation algorithm being configured to provide feature matching on each of the magnetic field measurements to substantially suppress noise associated with the magnetic field measurements and provide error correction with respect to detection of the fixed magnetic anomaly, wherein the magnetometer controller is further configured to generate a confidence score associated with the detection of the fixed magnetic anomaly based on the correlation algorithm, and wherein the magnetometer controller implements the confidence score and the magnetic field measurements in real-time to calculate the velocity of the vehicle relative to an Earth coordinate frame.

13. The system of claim 12 , wherein the plurality of magnetometers comprises a first magnetometer located at a fore-section of the vehicle and a second magnetometer located at an aft-section of the vehicle, the first and second magnetometers being located a predetermined distance with res

Assignees

• Larsen Michael S
• Bulatowicz Michael D
• Meyer A Douglas
• Bevan Dennis P
• Northrop Grumman Systems Corp

Inventors

• Larsen Michael S
• Bulatowicz Michael D
• Meyer A Douglas
• Bevan Dennis P

Classifications

• G01C21/1654

  with electromagnetic compass · CPC title

• G01C21/18 Primary

  Stabilised platforms, e.g. by gyroscope · CPC title

• G01C21/20

  Instruments for performing navigational calculations (G01C21/24, G01C21/26 take precedence) · CPC title

• G01C21/165

  combined with non-inertial navigation instruments · CPC title

• G01P15/14

  by making use of gyroscopes (gyroscopes per se G01C19/00) · CPC title