System and method for fusing sensor and satellite measurements for positioning determination

Patent metadata

Field	Value
Publication number	US-11906640-B2
Application number	US-202318115963-A
Country	US
Kind code	B2
Filing date	Mar 1, 2023
Priority date	Mar 1, 2022
Publication date	Feb 20, 2024
Grant date	Feb 20, 2024

Abstract

A method can include receiving a set of satellite signals, refining the set of satellite signals to generate a refined set of satellite signals, determining a satellite solution for each satellite associated with a satellite signal in the refined set of satellite signals, applying an a-priori correction to the satellite signals, determining a set of time differenced satellite signals between the satellite signals from a current epoch and a previous epoch; and determining the positioning solution of the rover using a fusion engine that processes the differenced satellite signals and inertial measurement unit (IMU) data.

First claim

We claim:

1. A method for determining a positioning solution of a rover comprising:
receiving a set of satellite signals associated with one or more satellite constellations;
selecting a first subset of satellite signals from the set of satellite signals;
determining a satellite position, velocity, and acceleration (PVA) for each satellite associated with a satellite signal in the first subset of satellite signals;
determining a variance model based on the satellite PVA;
selecting a reference satellite from the satellites associated with a satellite signal in the first subset of satellite signals;
applying an a-priori correction to each of the satellite signals in the filtered first subset of satellite signals;
determining a set of differenced satellite signals between a satellite signal associated with the reference satellite and each of the satellite signals associated with the remaining satellites;
determining a set of time differenced satellite signals between the differenced satellite signals from a current epoch and a previous epoch; and
determining the positioning solution of the rover using a fusion engine comprising an estimator that processes the set of time differenced satellite signals, inertial measurement unit (IMU) data, and the variance model, wherein the estimator uses stochastic cloning to model displacements using the set of time differenced satellite signals.

2. The method of claim 1 , further comprising detecting outliers in the set of time differenced satellite signals based on a normalized innovation squared statistic.

3. The method of claim 1 , wherein applying the a-priori correction to the satellites comprises determining the a-priori corrections using an atmospheric correction model selected from global zenith tropospheric delay model (GZTD), Satellite-based Augmentation System (SBAS), UNB3, or UNB3m models.

4. The method of claim 3 , wherein determining the a-priori corrections further comprises determining a satellite clock error using IGS model, IGU-P model, or RES-P5 model.

5. The method of claim 1 , wherein the reference satellite is shared across different satellite constellations.

6. The method of claim 1 , wherein selecting the first subset of satellite signals comprises determining satellite signals from the set of satellite signals to include in the first subset of satellite signals based on a carrier to noise density, a carrier lock time, a half cycle flag, or an elevation of a satellite associated with each satellite signal of the set of satellite signals.

7. The method of claim 1 , wherein selecting the reference satellite comprises selecting a satellite with a highest elevation angle.

8. The method of claim 1 , wherein the variance model does not consider cycle slips.

9. The method of claim 8 , wherein the variance model overbounds a thermal measurement noise, a change in orbit error projected onto a line-of-sight vector, satellite clock error change between the current epoch and the previous epoch, change in troposphere delay, change in ionospheric delay, and multipath effects.

10. The method of claim 1 , wherein the first subset of satellite signals comprises satellite signals associated with at most four satellites.

11. A system for determining a positioning solution of a body comprising:
a body comprising:
a magnetometer or an inertial measurement unit (IMU) comprising at least one of an accelerometer or a gyroscope;
an antenna configured to receive satellite signals corresponding to one or more satellite frequencies associated one or more satellite constellations; and

a processor comprising a fusion engine comprising an estimator configured to determine the positioning solution of the body based on IMU or magnetometer data measured by the IMU or the magnetometer and double differenced carrier phase information from a time difference of carrier phase (TDCP) module, wherein the estimator uses stochastic cloning to model displacements using the double differenced carrier phase information, wherein the TDCP module is configured to:
select a subset of the satellite signals to generate a subset of satellite signals based on a quality of satellites associated with the satellite signals;
select a reference satellite from satellites associated with the subset of satellite signals;
apply an a-priori correction to the satellite signals associated with the subset of satellite signals to generated corrected satellite signals;
determine the double-differenced carrier phase information from the corrected satellite signals by:
determining differenced satellite signals between satellite signals associated with the reference satellite and each of the satellite signals associated with the remaining satellites; and
determininge a set of time differenced satellite signals between the differenced satellite signals from a current epoch and a previous epoch.

12. The system of claim 11 , wherein the TDCP module is further configured to
determine a satellite position, velocity, and acceleration (PVA) for each satellite associated with a satellite signal in the subset of satellite signals;
select a second subset of satellite signals from the subset of satellite signals based on the satellite PVA; and
determine a variance model based on the satellite PVA;

wherein the fusion engine is further configured to determine the positioning solution of the body based on the variance model.

13. The system of claim 12 , wherein the variance model does not account for cycle slips.

14. The system of claim 12 , wherein the variance model overbounds a thermal measurement noise, a change in orbit error projected onto a line-of-sight vector, satellite clock error change between the current epoch and the previous epoch, change in troposphere delay, change in ionospheric delay, and multipath effects.

15. The system of claim 11 , wherein selecting the reference satellite comprises selecting a satellite with a highest elevation angle.

16. The system of claim 15 , where satellites from different satellite constellations are differenced to the reference satellite.

17. The system of Claim 11 , wherein applying the a-priori correction to the satellites comprises determining the a-priori correction using:
an atmospheric correction determined using one of global zenith tropospheric delay model (GZTD), Satellite-based Augmentation System (SBAS), UNB3 model, or UNB3m model; and
a satellite clock correction determined using one of IGS model, IGU-P model, or RES-P5 model.

18. The system of claim 11 , wherein selecting the subset of satellite signals comprises determining satellite signals from the satellite signals to include in the filtered set of satellite signals based on a carrier to noise density, a carrier lock time, a half cycle flag, or an elevation of a respective satellite.

19. The system of claim 11 , wherein the TDCP module is further configured to detect outliers in the double differenced carrier phase information based on a normalized innovation squared statistic, wherein the outliers are removed from the double differenced carrier phase information.

20. The system of claim 19 , wherein the outlier-removed double differenced carrier phase information comprises data from at most four distinct satellites.

21. The system of claim 11 , wherein the fusion engine comprises the TDCP module.

Assignees

• Swift Navigation Inc

Inventors

• Reimer Christian
• Angelo Joseph
• Carcanague Sebastien

Classifications

• G01S19/47 Primary

  the supplementary measurement being an inertial measurement, e.g. tightly coupled inertial · CPC title

• G01S19/28

  Satellite selection · CPC title

• G01S19/33

  Multimode operation in different systems which transmit time stamped messages, e.g. GPS/GLONASS · CPC title

• G01S19/396

  Determining accuracy or reliability of position or pseudorange measurements · CPC title

• G01S19/41

  Differential correction, e.g. DGPS [differential GPS] · CPC title