Post-mission high accuracy position and orientation system

• US 20080284643A1
• Filed: 05/16/2007
• Published: 11/20/2008
• Est. Priority Date: 05/16/2007
• Status: Active Grant

• Current Assignee: Trimble Navigation Limited (Trimble Inc.)
• Original Assignee: Trimble Navigation Limited (Trimble Inc.)
• Inventors: Vollath, Ulrich, Scherzinger, Bruno M., Hutton, Joseph J.
• Granted Patent: US 7,855,678 B2
• Time in Patent Office: Days
• US Class Current: 342/357.02
• CPC Class Codes: G01C 21/005 with correlation of navigation data from several sources, e.g. map or contour matching G01C21/30 takes precedence
• CPC Class Codes: G01S 19/43 using carrier phase measurements, e.g. kinematic positioning; using long or short baseline interferometry

Abstract

A method of generating post-mission position and orientation data comprises generating position and orientation data representing positions and orientations of a mobile platform, based on global navigation satellite system (GNSS) data and inertial navigation system (INS) data acquired during a data acquisition period by the mobile platform, using a network real-time kinematic (RTK) subsystem to generate correction data associated with the data acquisition period, and correcting the position and orientation data based on the correction data. The RTK subsystem may implement a virtual reference station (VRS) technique to generate the correction data.

Claims

1. A method comprising,

after a data acquisition period during which GNSS data and INS data have been acquired on a mobile platform:

generating position data representing positions of the mobile platform, based on the GNSS data and INS data acquired during the data acquisition period;

using a network RTK subsystem which includes a VRS subsystem to generate correction data associated with the data acquisition period; and

correcting the position data based on the correction data.

2. A method as recited in claim 1, wherein using the network RTK subsystem comprises:

acquiring differential GNSS observables measurements; and

performing integer carrier phase ambiguity resolution and carrier phase measurements.

3. A method as recited in claim 2, wherein using the network RTK subsystem further comprises:

integrating observables from a plurality of GNSS reference receivers arranged in a network to correct for atmospheric delays in GNSS observables acquired by the mobile platform, when a distance from the mobile platform to the nearest reference receiver exceeds a specified distance.

4. A method of generating post-mission GNSS-AINS based positioning data for a mobile platform, the method comprising:

inputting a set of rover GNSS observables previously acquired and recorded during a data acquisition period by a GNSS subsystem on the mobile platform;

inputting a set of reference GNSS observables acquired during said data acquisition period by a plurality of fixed GNSS receiver stations;

computing a set of VRS observables applicable to a VRS position for the data acquisition period, based on the reference GNSS observables and the rover GNSS observables; and

computing positions of the mobile platform for the data acquisition period based on the VRS observables, the rover GNSS observables and IMU data acquired and recorded during the data acquisition period by an IMU on the mobile platform.

5. A method as recited in claim 4, wherein computing positions of the mobile platform for the data acquisition period comprises:

computing the positions of the mobile platform for the data acquisition period based on the IMU data and based on correction data indicating corrections for predetermined types of uncertainties.

6. A method as recited in claim 4, further comprising:

correcting the reference GNSS observables based on the reference GNSS observables, prior to computing the set of VRS observables.

7. A method as recited in claim 6, wherein correcting the reference GNSS observables comprises:

correcting the reference GNSS observables for atmospheric error.

8. A method as recited in claim 7, wherein correcting the reference GNSS observables further comprises further comprises:

correcting the reference GNSS observables for antenna position error.

9. A method as recited in claim 4, characterized in that:

the mobile platform was located within a project area while the GNSS observables were acquired and recorded during the data acquisition period; and

the plurality of fixed reference receivers are distributed across the project area.

10. A method as recited in claim 4, wherein said computing positions of the mobile platform comprises:

acquiring differential GNSS observables measurements; and

performing integer carrier phase ambiguity resolution and carrier phase measurements.

11. A method as recited in claim 4, further comprising:

integrating the set of reference GNSS observables acquired by the plurality of fixed GNSS receiver stations to correct for atmospheric delays in the rover GNSS observables, when a distance from the mobile platform to the nearest reference receiver exceeds a specified distance.

12. A post-mission position and orientation system comprising:

a GNSS-AINS subsystem to generate position data representing positions of a mobile platform, based on GNSS data and INS data acquired during a data acquisition period by the mobile platform; and

a network RTK subsystem including a VRS subsystem to generate correction data associated with the data acquisition period, wherein the GNSS-AINS subsystem further is to generate the position data based on the correction data;

wherein neither the GNSS-AINS subsystem nor the network RTK subsystem is located on the mobile platform.

13. A system as recited in claim 12, further comprising:

a network adjustment subsystem to evaluate and correct antenna positions for a plurality of GNSS reference receivers arranged in a network, wherein the network RTK subsystem generates the correction data based on the corrected antenna positions.

14. A system as recited in claim 12, wherein the mobile platform.

15. A system as recited in claim 12, wherein the network RTK subsystem comprises a VRS subsystem.

16. A system as recited in claim 12, wherein the network RTK subsystem is configured to:

acquire differential GNSS observables measurements; and

perform integer carrier phase ambiguity resolution and carrier phase measurements.

17. A system as recited in claim 12, wherein the network RTK subsystem is configured to:

integrate observables from a plurality of GNSS reference receivers arranged in a network to correct for atmospheric delays in GNSS observables acquired by the mobile platform, when a distance from the mobile platform to the nearest reference receiver exceeds a specified distance.

18. A GNSS-AINS post-processing system comprising:

a VRS module to input rover GNSS observables previously acquired and recorded by a GNSS subsystem on a mobile platform during a data acquisition period and to input a set of reference GNSS observables for the data acquisition period, and to compute a set of VRS observables applicable to a VRS position for the data acquisition period based on the reference GNSS observables and the rover GNSS observables; and

a GNSS-AINS module to compute positions of the mobile platform for the data acquisition period, based on IMU data acquired and recorded during the data acquisition period by the mobile platform and based on the VRS observables and the rover GNSS observables.

19. A system as recited in claim 18, further comprising:

a network adjustment subsystem to evaluate and correct antenna positions for a plurality of fixed GNSS receiver stations arranged in a network, wherein the network RTK subsystem generates the correction data based on the corrected antenna positions.

20. A system as recited in claim 18, wherein the reference GNSS observables are acquired by a plurality of fixed GNSS receiver stations during said data acquisition period.

21. A system as recited in claim 18, wherein the virtual reference station module comprises:

a network module to input the set of reference GNSS observables and to produce a set of corrected reference GNSS observables; and

a VRS generator to compute the set of VRS observables, based on the rover GNSS observables and the corrected reference GNSS observables.

22. A system as recited in claim 21, wherein the network module determines an estimate of atmospheric error in the reference GNSS observables and corrects the reference GNSS observables based on the estimate.

23. A system as recited in claim 18, wherein the GNSS-AINS module comprises:

an inertial navigation module to receive the IMU data acquired and recorded by the mobile platform during the data acquisition period and to compute the positions of the mobile platform for the data acquisition period based on the IMU data.

24. A system as recited in claim 23, wherein the GNSS-AINS module comprises a correction module to generate correction data indicating corrections for predetermined types of uncertainties, wherein the inertial navigation module computes the positions of the mobile platform for the data acquisition period further based on the correction data.

25. A system as recited in claim 24, wherein the correction module comprises:

a Kalman filter to generate estimates of inertial navigation error based on the rover GNSS observables and the VRS observables and to generate carrier phase measurements;

an ambiguity resolution module to determine integer ambiguities based on the estimates and to indicate the integer ambiguities to the Kalman filter; and

an error controller to provide corrections to the inertial navigation unit based on the carrier phase measurements.

26. A system as recited in claim 18, wherein the mobile platform is an aircraft.

27. A system as recited in claim 18, wherein the VRS module is configured to:

acquire differential GNSS observables measurements; and

perform integer carrier phase ambiguity resolution and carrier phase measurements.

28. A system as recited in claim 27, wherein the VRS module is further configured to:

integrate the set of reference observables to correct for atmospheric delays in GNSS observables acquired by the mobile platform, when a distance from the mobile platform to the nearest reference receiver exceeds a specified distance, wherein the reference observables are from a plurality of GNSS reference receivers arranged in a network.

29. A GNSS-AINS post-processing system comprising:

a VRS module to input rover GNSS observables previously acquired and recorded by a GNSS subsystem on an aircraft during a data acquisition period, the VRS module including

a network module to input a set of reference GNSS observables acquired during said data acquisition period by a plurality of fixed GNSS receiver stations and to produce a set of corrected reference GNSS observables; and

a VRS generator to compute a set of VRS observables applicable to a VRS position for the data acquisition period, based on the corrected reference GNSS observables and the rover GNSS observables; and

a GNSS-AINS module to compute positions and orientations of the aircraft for the data acquisition period based on the VRS observables, the rover GNSS observables and IMU data acquired and recorded during the data acquisition period by an IMU on the aircraft, including

an inertial navigation module to compute the positions and orientations of the aircraft for the data acquisition period based on the IMU data and based on correction data indicating corrections for predetermined types of uncertainties; and

a correction module to generate the correction data.

30. A system as recited in claim 29, wherein the network module determines an estimate of atmospheric error in the reference GNSS observables and corrects the reference GNSS observables based on the estimate.

31. A system as recited in claim 29, wherein the correction module comprises:

a Kalman filter to generate estimates of inertial navigation error based on the rover GNSS observables and the VRS observables and to generate carrier phase measurements;

an ambiguity resolution module to determine integer ambiguities based on the estimates and to indicate the integer ambiguities to the Kalman filter; and

an error controller to provide corrections to the inertial navigation unit based on the carrier phase measurements.