VEHICLE NAVIGATION USING NON-GPS LEO SIGNALS AND ON-BOARD SENSORS

• US 20110238307A1
• Filed: 03/28/2011
• Published: 09/29/2011
• Est. Priority Date: 03/26/2010
• Status: Active Grant

• Current Assignee: Apple Inc.
• Original Assignee: Coherent Navigation, Inc. (Apple Inc.)
• Inventors: Psiaki, Mark Lockwood, Miller, Isaac Thomas, Ledvina, Brent Michael
• Granted Patent: US 8,682,581 B2
• Time in Patent Office: Days
• US Class Current: 701/213
• CPC Class Codes: G01C 21/28 with correlation of data from several navigational instruments
• CPC Class Codes: G01S 19/215 issues related to spoofing
• CPC Class Codes: G01S 19/31 Acquisition or tracking of other signals for positioning
• CPC Class Codes: G01S 19/42 Determining position
• CPC Class Codes: G01S 19/45 by combining measurements of signals from the satellite radio beacon positioning system with a supplementary measurement

Abstract

A navigation system includes a navigation radio and a sensor onboard a vehicle. The navigation radio receives and processes low earth orbit RF signals to derive range observables for a corresponding LEO satellite. A sensor is operable to generate at least one of vehicle speed data, acceleration data, angular rate data and rotational angle data under high vehicle dynamics. The navigation radio includes a navigation code operable to obtain a position, velocity and time solution (a “navigation solution”) based on the one or more range observables, ephemerides for the corresponding LEO satellite, a heading pseudomeasurement, a navigation radio altitude pseudomeasurement; one or more vehicle velocity pseudomeasurements orthogonal to the altitude pseudomeasurements; and the generated at least one of vehicle speed data, acceleration data, angular rate data and rotational angle data. The navigation radio uses the navigation solution to acquire a GPS signal during interference with a coarse acquisition GPS signal.

Claims

1. A vehicle navigation method comprising:

receiving, from one or more LEO satellites, RF signals at a navigation radio;

obtaining satellite ephemerides for a corresponding LEO satellite;

deriving one or more range observables, based on the received RF signals, for the corresponding LEO satellite;

establishing an altitude pseudomeasurement for the navigation radio;

establishing a heading pseudomeasurement for the navigation radio;

generating at least one of vehicle speed data, acceleration data, angular rate data and rotational angle data by one or more sensors onboard a vehicle moving at high dynamics;

computing a position, velocity and time solution (a “

navigation solution”

) based on the one or more range observables, the obtained ephemerides, the established altitude and heading pseudomeasurements, one or more vehicle velocity pseudomeasurements orthogonal to the altitude pseudomeasurement; and

the generated at least one of vehicle speed data, acceleration data, angular rate data and rotational angle data.

2. The navigation method of claim 1, further comprising acquiring a GPS signal based on the computed navigation solution.

3. The navigation method of claim 2, wherein the GPS signal is acquired under jamming of a coarse acquisition code and wherein the GPS signal includes one of a Y-code, M-code, encrypted GPS code, coarse acquisition code, military GPS code, and civil code.

4. The navigation method of claim 1, wherein the high dynamics of the vehicle includes speeds greater than about 12 mph.

5. The navigation method of claim 1, wherein the estimated navigation solution is accurate to about 10 m.

6. The navigation method of claim 1, wherein the one or more range observables includes at least one of a pseudorange measurement, carrier phase measurement, and a Carrier Doppler shift frequency measurement.

7. The navigation method of claim 1, wherein the altitude pseudomeasurement is based on at least one of local terrain data, an altimeter measurement, and a barometer measurement.

8. The navigation method of claim 1, wherein the vehicle is a wheeled vehicle and wherein the one or more orthogonal vehicle velocity pseudomeasurements includes a vehicle velocity constraint of substantially zero wheel side-slip.

9. The navigation system of claim 1, wherein the heading pseudomeasurement is established by at least one of a magnetometer, multi-antenna array, sun sensor, star tracker, digital compass, multiple hypothesis heading filter, and a LEO carrier phase measurement.

10. A navigation system comprising:

at least one sensor onboard a vehicle and operable to generate at least one of vehicle speed data, acceleration data, angular rate data and rotational angle data under high vehicle dynamics;

a navigation radio coupled to the sensor to receive generated sensor data, the navigation radio comprising;

an RF antenna operable to receive RF signals from one or more LEO satellites;

an RF front end operable to downconvert and digitize the RF signals;

a digital processor operable to derive one or more range observables from the downconverted RF signals for a corresponding LEO satellite;

a navigation code stored in media and including instructions executable on the digital processor to obtain a position, velocity and time solution (a “

navigation solution”

) based on the one or more range observables, ephemerides for the corresponding LEO satellite, navigation radio altitude and heading pseudomeasurements, one or more vehicle velocity pseudomeasurements orthogonal to the altitude pseudomeasurement, and the generated at least one of vehicle speed data, acceleration data, angular rate data and rotational angle data.

11. The navigation system of claim 10, wherein the navigation radio is positionally fixed with regard to a vehicle and the one or more vehicle velocity pseudomeasurements includes a vehicle velocity constraint of substantially zero wheel side-slip.

12. The navigation system of claim 11, wherein the heading pseudomeasurement is obtained via at least one of a magnetometer, multi-antenna array, sun sensor, star tracker, digital compass, multiple hypothesis heading filter, and a LEO carrier phase measurement.

13. The navigation system of claim 11, wherein the navigation radio is further capable of acquiring a GPS signal including at least one of a Y-code, M-code, encrypted GPS code, coarse acquisition code, military GPS code, and civil code based on the navigation solution.

14. The navigation system of claim 10, further comprising a second navigation radio capable of processing GPS signals and operable to acquire a GPS signal including one of a Y-code, M-code, encrypted GPS code, coarse acquisition code, military GPS code, and civil code based on the navigation solution.

16. A navigation system comprising:

a vehicle;

a navigation radio positionally fixed with regard to the vehicle;

an RF antenna electrically coupled to the navigation radio and operable to receive RF signals from one or more LEO satellites;

an RF front end operable to downconvert and digitize the RF signals to produce digital IF signals;

a digital processor operable to derive one or more range observables from the digital IF signals for a corresponding (LEO) satellite;

an sensor positionally fixed with regard to the vehicle and coupled to the navigation radio, the sensor operable to generate at least one of vehicle speed data, acceleration data, angular rate data and rotational angle data under high vehicle dynamics;

a navigation code stored in media and including instructions executable on the digital processor to calculate a position, velocity and time solution (“

navigation solution”

) based on the one or more range observables, ephemerides for the corresponding LEO satellite, a navigation radio altitude pseudomeasurement, one or more vehicle velocity pseudomeasurements orthogonal to the altitude pseudomeasurement;

a heading pseudomeasurement, and the generated at least one of vehicle speed data, acceleration data, angular rate data and rotational angle data.

15. The navigation system of claim 20, wherein the altitude pseudomeasurement is based on at least one of local terrain data, an altimeter measurement, and a barometer measurement.

17. The navigation system of claim 16, further comprising a GPS radio and wherein the navigation solution is sufficiently accurate to allow acquisition of a GPS signal including one of a Y-code, M-code, encrypted GPS code, coarse acquisition code, military GPS code, and civil code during a period of interference with a coarse acquisition signal.

18. The navigation system of claim 16, wherein the vehicle is one of a wheeled vehicle, an aircraft, and a boat.

19. The navigation system of claim 16, wherein the vehicle is a wheeled vehicle and the one or more vehicle velocity pseudomeasurements includes a velocity constraint of substantially zero wheel side-slip.

20. The navigation system of claim 16, wherein navigation code employs data from at least one of a wheel rate sensor, traction control unit, steering sensor, speedometer, odometer, tire pressure sensor, pitot tube, and anemometer.

21. The navigation system of claim 16, wherein the heading pseudomeasurement is generated by at least one of a magnetometer, multi-antenna array, sun sensor, digital compass, multiple hypothesis heading filter, and a LEO carrier phase measurement.

22. The navigation system of claim 16, wherein the altitude pseudomeasurement is based on at least one of terrain map data, an altimeter measurement, and a barometer measurement.

23. The navigation system of claim 16, wherein the navigation code includes an extended Kalman filter employing a measurement model, dynamics model and a state vector definition wherein the state vector definition includes a navigation radio position, a navigation radio velocity, a sensor rate-gyro bias, a sensor accelerometer bias;

and a navigation radio attitude estimate and wherein the measurement model defines a relationship between the state vector and each of the range observables and pseudomeasurements.