Simultaneous tracking and navigation using leo satellite signals

Patent metadata

Field	Value
Publication number	US-2022171077-A1
Application number	US-202017604157-A
Country	US
Kind code	A1
Filing date	Apr 15, 2020
Priority date	Apr 15, 2019
Publication date	Jun 2, 2022
Grant date	—

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; 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 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.

7 . 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.

8 . 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.

9 . 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.

10 . 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;
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.

11 . The device of claim 10 , 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.

12 . The device of claim 10 , 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.

13 . The device of claim 10 , wherein clock states of the vehicle and LEO satellites are propagated using a double integrator model driven by process noise.

14 . The device of claim 10 , 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.

15 . The device of claim 10 , 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.

16 . The device of claim 10 , 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.

17 . The device of claim 10 , 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.

18 . The device of claim 10 , 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

• G01C21/165

  combined with non-inertial navigation instruments · CPC title

• G01S19/52

  Determining velocity · CPC title

• G01S19/42

  Determining position · CPC title

• G01C21/188 Primary

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

• G01S19/49 Primary

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