IMPROVED GNSS RECEIVER USING A COMBINATION OF VELOCITY INTEGRATION AND PRECISE POINT POSITIONING

• US 20190094385A1
• Filed: 03/31/2017
• Published: 03/28/2019
• Est. Priority Date: 04/01/2016
• Status: Active Grant

• Current Assignee: Centre National D'Etudes Spatiales
• Original Assignee: Centre National D'Etudes Spatiales
• Inventors: LAURICHESSE, Denis, MARMET, Francois-Xavier, RIES, Lionel
• Granted Patent: US 10,942,281 B2
• Time in Patent Office: Days
• CPC Class Codes: G01S 19/22 Multipath-related issues
• CPC Class Codes: G01S 19/32 Multimode operation in a single same satellite system, e.g. GPS L1/L2
• CPC Class Codes: G01S 19/396 Determining accuracy or reliability of position or pseudorange measurements
• CPC Class Codes: G01S 19/426 by combining or switching between position solutions or signals derived from different modes of operation in a single system
• CPC Class Codes: G01S 19/46 the supplementary measurement being of a radio-wave signal type
• CPC Class Codes: G01S 19/47 the supplementary measurement being an inertial measurement, e.g. tightly coupled inertial
• CPC Class Codes: G01S 19/52 Determining velocity

Abstract

The invention discloses an improved GNSS receiver which determines a location of the receiver by combining a first location determined either from the standard PVT of a multi-frequency receiver and/or from a positioning aid like a map matching algorithm, inertial navigation system, WiFi localization system or other, and a second location determined by integrating the velocity from the standard PVT. The combination is based on a duty cycle or a combination of the duty cycle with a weighting of the error budgets of the first position and the second location. The improved receiver is preferably based on a standard receiver with an add-on software module which receives and processes data transmitted from the standard receiver by, for example, NMEA messages. The improved receiver allows a determination of a more precise and smoother trajectory in a simple way.

Claims

1. A GNSS receiver comprising:

first computing logic configured to calculate a first location and a second location of the GNSS receiver, the first location based on position data in a PVT vector and calculated on one or more channels from a plurality of GNSS signals operating at two or more frequencies, the second location based on a result of an integration of velocity data in the PVT vector and calculated on the one or more channels from GNSS signals each operating at a single frequency;

second computing logic configured to determine one or more weighting factors of the first location and the second location and to cause the first computing logic to output a calculated location of the GNSS receiver as a weighted average of the first location and the second location.

2. The GNSS receiver of claim 1, wherein the one or more weighting factors comprise a time cycle.

3. The GNSS receiver of claim 2, wherein the time cycle is predetermined based on an average duration of validity of an atmospheric correction.

4. The GNSS receiver of claim 3, wherein the predetermined time cycle is in-between 60 s and 300 s.

5. The GNSS receiver of claim 2, wherein the first weight is set to zero and the second weight is set to one in-between two successive instants of the predetermined time cycle, while the first weight is set to one and the second weight is set to zero at said two successive instants.

6. The GNSS receiver of claim 2, wherein the second computing logic is further configured to estimate a first error budget of the first location and a second weight of the second location and the one or more weighting factors are calculated by one or more of the first computing logic or the second computing logic, based on one or more of a predetermined time cycle, the first error budget or the second error budget.

7. The GNSS receiver of claim 1, wherein a first weight of the first location in the calculated location equals a proportion of the first error budget in the total of the first error budget and the second error budget and a second weight of the second location in the calculated location equals a proportion of the second error budget in the total of the first error budget and the second error budget.

8. The GNSS receiver of claim 1, wherein the first weight equals a hundred percent if the first error budget is lower than or equal to a combination of the second error budget and a first threshold value,

9. The GNSS receiver of claim 1, wherein the second weight equals a hundred percent if the second error budget is lower than a combination of the first error budget and a second threshold value.

10. The GNSS receiver of claim 1, wherein the second location uses, based on a decision criterion, one or more of:

i) a calculated location of the GNSS receiver at an epoch before a current epoch as an initial value of the integration of the velocity data in the PVT vector or ii) a location of the GNSS receiver at a previous epoch input from positioning aids as an initial value of the integration of the velocity data in the PVT vector.

11. The GNSS receiver of claim 10, wherein the positioning aids comprise one or more of a map matching algorithm, an output of an inertial navigation system or a Wi-Fi localization system.

12. The GNSS receiver of claim 11, wherein the estimated error budgets depend upon one or more of a configuration of said GNSS receiver, a geometry of GNSS satellites in view of said GNSS receiver or a topology in an environment of said GNSS receiver.

13. The GNSS receiver of claim 11, wherein the estimated error budgets are estimated based on one or more of a Dilution Of Precision (DOP), a User Equivalent Range Error (UERE), a User Equivalent Range Rate Error (UERRE) or a probability estimate of a random walk of the integrated velocity along its path between a previous epoch and a current epoch.

14. The GNSS receiver of claim 13, wherein the first error budget equals the DOP multiplied by the UERE.

15. The GNSS receiver of claim 13, wherein the second error budget equals a product of the DOP multiplied by the UERRE, times the duration during which velocity has been integrated.

16. The GNSS receiver of claim 15, wherein the probability estimate of the random walk of the integrated velocity is modeled by an ellipsoid.

17. The GNSS receiver of claim 16, wherein one or more of the UERE and the UERRE are a combination of one or more of a parameter value, a carrier to noise ratio dependent value, an elevation dependent value or a signal dependent value.

18. The GNSS receiver of claim 17, wherein one or more of the first error budget or the second error budget are forecast estimated error budgets, said forecast being based on a combination of an estimated future trajectory of the GNSS receiver and a probability on said estimated future trajectory of one or more of a configuration of said GNSS receiver, a geometry of GNSS satellites in view of said GNSS receiver or a topology in an environment of said GNSS receiver.

19. The GNSS receiver of claim 18, wherein one or more of the UERE and the UERRE are predefined and stored in a database accessible by the first computing logic.

20. The GNSS receiver of claim 19, further comprising a third computing logic configured to calculate a heading information from the PVT vector.

21. A localization method using a GNSS receiver, the method comprising:

calculating a first location and a second location of the GNSS receiver, the first location based on position data in a PVT vector calculated by the GNSS receiver on one or more channels from a plurality of GNSS signals operating at two or more frequencies, the second location based on a result of an integration of velocity data in the PVT vector and calculated on the one or more channels from GNSS signals each operating at a single frequency;

determining one or more weighting factors of the first location and the second location and

causing the first computing logic to output a calculated location of the GNSS receiver as a weighted average of the first location and the second location.