Simultaneous tracking and navigation using LEO satellite signals

Patent metadata

Field	Value
Publication number	US-11808867-B2
Application number	US-202017604157-A
Country	US
Kind code	B2
Filing date	Apr 15, 2020
Priority date	Apr 15, 2019
Publication date	Nov 7, 2023
Grant date	Nov 7, 2023

Abstract

Systems, device configurations, and processes are provided for tracking and navigation using low-earth orbit satellite (LEO) signals. Embodiments are provided to track LEO satellites in the absence or during interrupted service by global position sources (e.g., GNSS). Operations and a framework are provided to use low-earth orbit (LEO) downlink transmissions as a source of positioning data. Operations can include performing a Doppler frequency measurement on received satellite downlink transmissions to determine a pseudorange rate measurement for a vehicle relative to at least one LEO satellite. Pseudorange rate measurements may be used to correct vehicle position data of a vehicles inertial navigation system (INS) and for control/navigation of the vehicle. Embodiments allow for simultaneous tracking of LEO satellites and navigation of a vehicle, such as an unmanned aerial vehicle. Embodiments are also directed to employing a propagation model for LEO position and velocity within a simultaneous tracking and navigation (STAN) framework.

First claim

What is claimed is:

1. A method for navigation using low-earth orbit satellite (LEO) signals, the method comprising:
receiving, by a device, a low-earth orbit (LEO) satellite downlink transmission;
performing, by the device, a Doppler frequency measurement on received satellite downlink transmissions to determine a pseudorange rate measurement for a vehicle relative to at least one LEO satellite, wherein a simplified general perturbation model including analytical expressions to propagate a satellite position from an epoch time to a specified future time is employed to determine satellite position and velocity for determination of vehicle position;
correcting, by the device, position data of a vehicle intertial navigation system (INS) for control of the vehicle, wherein correcting includes determining a corrected position based on the pseudorange rate measurement; and
controlling, by the device, navigation of the vehicle based on the corrected position.

2. The method of claim 1 , wherein performing a Doppler frequency measurement includes performing an extended Kalman filter (EKF)-based operation for simultaneous tracking and navigation of a LEO satellite for LEO satellite position and velocity determination.

3. The method of claim 1 , wherein the pseudorange rate measurement represents rate of change of distance between the vehicle and an LEO satellite, and wherein a LEO satellite propagation model is employed to determine LEO satellite position and velocity.

4. The method of claim 1 , wherein clock states of the vehicle and LEO satellites are propagated using a double integrator model driven by process noise.

5. The method of claim 1 , wherein correcting position data of the vehicle includes fusing the corrected position with a vehicle orientation, position, and velocity determined by an inertial measurement unit of the inertial navigation system.

6. The method of claim 1 , wherein a two-body model including expressions of the satellite acceleration and a standard gravitational parameter are employed to determine satellite position and velocity for determination of vehicle position.

7. The method of claim 1 , wherein a two-body model with a zonal coefficient including expressions for non-uniform gravity are employed model to determine satellite position and velocity for determination of vehicle position.

8. The method of claim 1 , wherein controlling navigation based on the corrected position is performed during a period when GNSS signals are determined as unavailable for determining position of the vehicle.

9. A device configured for navigation using low-earth orbit satellite (LEO) signals, the device comprising:
a communications module configured to receive one or more low earth orbit (LEO) satellite signals; and
a controller, coupled to the communications module, wherein the controller is configured to receive a low-earth orbit (LEO) satellite downlink transmission;
perform a Doppler frequency measurement on received satellite downlink transmissions to determine a pseudorange rate measurement for a vehicle relative to at least one LEO satellite, wherein a simplified general perturbation model including analytical expressions to propagate a satellite position from an epoch time to a specified future time is employed to determine satellite position and velocity for determination of vehicle position;
correct position data of a vehicle intertial navigation system (INS) for control of the vehicle, wherein correcting includes determining a corrected position based on the pseudorange rate measurement; and
control navigation of the vehicle based on the corrected position.

10. The device of claim 9 , wherein performing a Doppler frequency measurement includes performing an extended Kalman filter (EKF)-based operation for simultaneous tracking and navigation of a LEO satellite for LEO satellite position and velocity determination.

11. The device of claim 9 , wherein the pseudorange rate measurement represents rate of change distance between the vehicle and an LEO satellite, and wherein a LEO satellite propagation model is employed to determine LEO satellite position and velocity.

12. The device of claim 9 , wherein clock states of the vehicle and LEO satellites are propagated using a double integrator model driven by process noise.

13. The device of claim 9 , wherein correcting position data of the vehicle includes fusing the corrected position with a vehicle orientation, position, and velocity determined by an inertial measurement unit of the inertial navigation system.

14. The device of claim 9 , wherein a two-body model including expressions of the satellite acceleration and a standard gravitational parameter are employed to determine satellite position and velocity for determination of vehicle position.

15. The device of claim 9 , wherein a two-body model with a zonal coefficient including expressions for non-uniform gravity are employed model to determine satellite position and velocity for determination of vehicle position.

16. The device of claim 9 , wherein controlling navigation based on the corrected position is performed during a period when GNSS signals are determined as unavailable for determining position of the vehicle.

Assignees

• Univ California

Inventors

• Kassas Zak
• Morales Josh
• Khalife Joe

Classifications

• G01S19/49 Primary

  whereby the further system is an inertial position system, e.g. loosely-coupled · CPC title

• G01C21/165

  combined with non-inertial navigation instruments · CPC title

• G01C21/188 Primary

  for accumulated errors, e.g. by coupling inertial systems with absolute positioning systems · CPC title

• G01S19/52

  Determining velocity · CPC title

• G01S19/42

  Determining position · CPC title