Positioning system and method

• US 8,547,276 B2
• Filed: 09/26/2008
• Issued: 10/01/2013
• Est. Priority Date: 09/28/2007
• Status: Active Grant

• Current Assignee: Leica Geosystems AG (Hexagon AB)
• Original Assignee: Leica Geosystems AG (Hexagon AB)
• Inventors: Kellar, William James, Cole, Anthony
• Primary Examiner(s): Issing, Gregory C
• Application Number:
  US12/680,358
• Publication Number:
  US 20110050488A1
• Time in Patent Office: 1,831 Days
• Field of Search: 342/357.28, 342/357.3
• US Class Current: 342/357.28
• CPC Class Codes: G01C 21/165 combined with non-inertial navigation instruments
• CPC Class Codes: G01S 19/45 by combining measurements of signals from the satellite radio beacon positioning system with a supplementary measurement
• CPC Class Codes: G01S 19/47 the supplementary measurement being an inertial measurement, e.g. tightly coupled inertial

Abstract

A positioning method whereby inertial positioning data is calculated based upon measurements of an Inertial Navigation System. Virtual satellite ranging data is then generated based upon the inertial positioning data. The virtual satellite ranging data is then combined with received satellite ranging data from one or more satellites forming part of a Global Navigation Satellite System (GNSS). A GNSS positioning solution is then calculated based upon the combined received satellite ranging data and the virtual satellite ranging data.

Claims

1. A positioning method including the steps of:

(i) calculating inertial positioning data based upon measurements of an Inertial Navigation System;

(ii) generating virtual satellite ranging data based upon the inertial positioning data, including the steps of;

(a) identifying one or more obstructed satellites forming part of the GNSS wherein satellite ranging data from the one or more obstructed satellites is not received;

(b) translating the inertial positioning data to form the virtual satellite ranging data such that the virtual satellite ranging data is identical in form to satellite ranging data from the one or more obstructed satellites;

(iii) combining received satellite ranging data from one or more satellites forming part of a Global Navigation Satellite System (GNSS) with the virtual satellite ranging data; and

(iv) calculating a GNSS positioning solution based upon the combined received satellite ranging data and the virtual satellite ranging data.

2. The positioning method of claim 1, wherein an almanac and an ephemeris of a GPS receiver is modified to accept virtual ranging data from one or more virtual satellites not forming part of any GNSS constelation, the step of generating virtual satellite ranging data based upon the inertial positioning data includes the step of:

translating the inertial positioning data to form the virtual satellite ranging data such that the virtual satellite ranging data corresponds with the modified almanac and ephemeris of the GPS receiver.

3. The positioning method of claim 2, wherein the almanac and the ephemeris of the GPS receiver is modified such that the one or more virtual satellites are placed in an orbit to allow the calculation of the GNSS positioning solution to occur half way between consecutive epochs of positioning calculations based upon satellite ranging data alone.

4. The positioning method of claim 1, further including the step of:

utilizing the calculated GNSS positioning solution to correct errors in the inertial positioning data.

5. The positioning method of claim 1, further including the step of adjusting the generated virtual satellite ranging data to include atmospheric errors prior to combing the virtual satellite ranging data with the received satellite ranging data.

6. A positioning system comprising:

an inertial navigation system adapted to calculate inertial positioning data;

a GPS system having a processing module, the GPS system adapted to receive satellite ranging data and calculate a GNSS positioning solution based upon the received satellite ranging data;

a translation module in communication with the inertial navigation system, the translation module adapted to receive the inertial positioning data and translate the inertial positioning data into virtual satellite ranging data including virtual ranging data from one or more virtual satellites, wherein the translation module;

(a) identifies one or more obstructed satellites forming part of the GNSS wherein satellite ranging data from the one or more obstructed satellites is not received; and

(b) translates the inertial positioning data to form the virtual satellite ranging data such that the virtual satellite ranging data is identical in form to satellite ranging data from the one or more obstructed satellites; and

an augmentation module in communication with the processing module of the GPS system and the translation module, the augmentation module adapted to receive the satellite ranging data from the GPS system and the virtual satellite ranging data from the translation module to form combined ranging data and communicate the combined ranging data to the processing module of the GPS system;

wherein the processing module of the GPS system calculates a positioning solution based upon the combined ranging data received from the augmentation module.

7. The positioning system of claim 6, wherein the processing module of the GPS system is adapted to communicate the calculated positioning solution to the inertial navigation system.

8. The positioning system of claim 7, wherein the inertial navigation system is adapted to correct errors in the calculated positioning data based upon the positioning received from the processing module of the GPS system.

9. The positioning system of claim 6, wherein the translation module adjusts the generated virtual satellite ranging data to include modeled atmospheric errors.

10. The positioning system of claim 6, wherein an almanac and an ephemeris of a GPS receiver is modified to accept virtual ranging data from one or more virtual satellites not forming part of any GNSS constellation.

11. The positioning system of claim 10, wherein the almanac and the ephemeris of the GPS receiver is modified such that the one or more virtual satellites are placed in an orbit to allow the calculation of the GNSS positioning solution to occur half way between consecutive epochs of positioning calculations based upon satellite ranging data alone.