Integrated inertial gravitational anomaly navigation system

Patent metadata

Field	Value
Publication number	US-11268813-B2
Application number	US-202016845987-A
Country	US
Kind code	B2
Filing date	Apr 10, 2020
Priority date	Jan 13, 2020
Publication date	Mar 8, 2022
Grant date	Mar 8, 2022

Abstract

A system implementing a method for generating a navigation output is provided. The method includes determining a gravitational anomaly estimate based at least in part on inertial sensor data and navigation output; generating navigation and sensor corrections that are due at least in part on inherent sensor errors that include vertical accelerometer/gravimeter corrections from at least a navigation output estimate, the gravitational anomaly estimate, and the gravity map data; and generating the navigation output based on the inertial sensor data, gravity map data and the navigation and sensor corrections.

First claim

The invention claimed is:

1. An integrated inertial and gravitational anomaly navigation system, the system comprising:
at least one inertial measurement unit (IMU) including an integrated gravimeter, the IMU configured to output inertial sensor data;
a gravity map including gravitational forces associated with locations;
at least one memory to store operational instructions for at least functions; and
at least one controller in communication with an output of the at least one IMU and the at least one memory, the at least one controller configured to execute the operating instructions stored in the at least one memory generating the functions, the functions including a strapdown navigation function, a measurement formation function and a fusion function, wherein the strapdown navigation function generates a navigation output by the system based at least in part on the inertial sensor data, map data from the gravity map and navigation and sensor corrections from the fusion function, further wherein the measurement formation function determines a gravitational anomaly estimate that is output to the fusion function based at least in part on the inertial sensor data and the navigation output, further yet wherein the fusion function generates the navigation and sensor corrections due at least in part on inherent sensor errors that include vertical accelerometer/gravimeter errors from at least the navigation output, the gravitational anomaly estimate and the map data.

2. The system of claim 1 , wherein the integrated gravimeter is a vertical accelerometer of a sufficient quality to act as a gravimeter.

3. The system of claim 1 , further comprising:
a depth/altitude sensor configured to provide at least one of altitude and altitude derivative sensor data to the fusion function to at least one of aid the altitude and altitude derivative estimates.

4. The system of claim 1 , further comprising:
at least one supplemental vertical accelerometer to at least one of extend dynamic range and eliminate correlated errors.

5. The system of claim 1 , wherein the gravity map further includes at least one of vector, scalar gravity information and gravity gradient information.

6. The system of claim 1 , wherein the gravitational anomaly estimate is also based in part on at least one of altitude and altitude rate sensor information that provides supplementary information about vertical acceleration to the measurement formulation function.

7. The system of claim 1 , wherein the at least one controller is a single controller.

8. The system of claim 1 , further comprising:
an input in communication with the at one controller to allow an operator to input operating instructions.

9. The system of claim 1 , further comprising:
an output in communication the at least one controller to output a navigation output determined by the at least one controller.

10. The system of claim 9 , wherein the output includes a vehicle control that is configured to control navigation of the vehicle at least in part on the navigation output determined by the at least one controller.

11. The system of claim 1 , wherein the fusion function is configured to implement at least one of a fusion filter, an optimal filter and a matching algorithm in generating the navigation and sensor corrections.

12. A method for generating a navigation output, the method comprising:
determining a gravitational anomaly estimate based at least in part on inertial sensor data and navigation output;
generating navigation and sensor corrections that are due at least in part on inherent sensor errors that include vertical accelerometer/gravimeter errors from at least a navigation output estimate, the gravitational anomaly estimate, and gravity map data; and
generating the navigation output based on the inertial sensor data, the gravity map data and the navigation and sensor corrections.

13. The method of claim 12 , wherein determining a gravitational anomaly estimate is further based on sensor data from a depth/altitude sensor.

14. The method of claim 12 , wherein generating the navigation and sensor corrections is further based on sensor data from a depth/altitude sensor.

15. The method of claim 12 , wherein the inertial sensor data is generated by at least one inertial measurement unit (IMU) that includes an integrated gravimeter.

16. The method of claim 15 , wherein the integrated gravimeter is a vertical accelerometer that is of a sufficient quality to act as a gravimeter.

17. The method of claim 12 , further comprising:
retrieving the gravity map data from a gravity map stored in memory.

18. The method of claim 12 , wherein generating navigation and sensor corrections further comprises:
implementing at least one of a fusion filter, an optimal filter and a matching algorithm on data from at least the navigation output estimate, the gravitational anomaly estimate, and the gravity map data.

19. A method for generating a navigation output, the method comprising:
determining a gravitational anomaly estimate based at least in part on inertial sensor data, altitude and altitude derivative estimate sensor data, and navigation output;
generating navigation and sensor corrections that are due at least in part on inherent sensor errors that include vertical accelerometer/gravimeter errors from at least a navigation output estimate, the gravitational anomaly estimate, altitude and altitude derivative sensor data and the gravity map data; and
generating the navigation output based on the inertial sensor data, the gravity map data and the navigation and sensor corrections.

20. The method of claim 19 , further comprising:
using a vertical accelerometer to at least one of extend dynamic range and eliminate correlated errors.

Assignees

• Honeywell Int Inc

Inventors

• Keyes Sally Ann

Classifications

• G01C21/165 Primary

  combined with non-inertial navigation instruments · CPC title

• G01C5/06

  by using barometric means · CPC title

• G01C21/04

  by terrestrial means (G01C21/24, G01C21/26 take precedence) · CPC title

• G01C25/005

  initial alignment, calibration or starting-up of inertial devices · CPC title

• G01C21/28

  with correlation of data from several navigational instruments · CPC title