AIRCRAFT NAVIGATION USING THE GLOBAL POSITIONING SYSTEM AND AN ATTITUDE AND HEADING REFERENCE SYSTEM

• US 20100179758A1
• Filed: 01/09/2009
• Published: 07/15/2010
• Est. Priority Date: 01/09/2009
• Status: Active Grant

• Current Assignee: Universal Avionics Systems Corporation (Elbit Systems Limited)
• Original Assignee: Universal Avionics Systems Corporation (Elbit Systems Limited)
• Inventors: Latif, Shehzad
• Granted Patent: US 8,082,099 B2
• Time in Patent Office: Days
• US Class Current: 701/216
• CPC Class Codes: G01C 21/165 combined with non-inertial navigation instruments
• CPC Class Codes: G01S 5/018 Involving non-radio wave signals or measurements

Abstract

A vehicle navigation technique uses a receiver for signals of a global positioning system to produce a first position indication and a first velocity indication. An attitude and heading reference system employs accelerometers and gyroscopes oriented along three axes. The raw signals from the accelerometers and gyroscopes are used to derive a second position indication and a second velocity value. A Kalman filter function is applied to the first and second position indications and to the first and second velocity indications to thereby produce a present position indication and a present velocity indication. The Kalman filter function exploits GPS data to corrects periodic drift in the position and velocity indications derived form the accelerometers and gyroscopes by calculating accelerometer and gyroscope biases, thereby enabling relatively inexpensive devices to be utilized.

Claims

1. A navigation system for a vehicle comprising:

an attitude and heading reference system onboard the vehicle and comprising a plurality of accelerometers and a plurality of gyroscopes;

a receiver, onboard the vehicle, for first signals of a global positioning system and producing a first position indication; and

a processor that receives accelerometer data and gyroscope data from the attitude and heading reference system and therefrom produces a second position indication, and also receives the first position indication, wherein the processor employs the first and second position indications to produce a present position indication for the vehicle.

2. The navigation system as recited in claim 1 wherein the processor applies a recursive data processing algorithm to the first and second position indications.

3. The navigation system as recited in claim 1 wherein the processor applies a Kalman filter function to the first and second position indications.

4. The navigation system as recited in claim 1 wherein the receiver also receives second signals of a Wide Area Augmentation System and wherein the first position indication also is produced in response to the second signals.

5. The navigation system as recited in claim 1 wherein:

the first receiver also produces a first velocity indication; and

the processor also produces a second velocity indication using the accelerometer data and gyroscope data, and employs the first and second velocity indications to produce a present velocity indication for the vehicle.

6. The navigation system as recited in claim 5 wherein the processor applies a recursive data processing algorithm to the first and second position indications and to the first and second velocity indications to produce the present position indication and the present velocity indication.

7. The navigation system as recited in claim 5 wherein the processor applies a Kalman filter to the first and second position indications and to the first and second velocity indications to produce the present position indication and the present velocity indication.

8. A navigation method for a vehicle comprising:

receiving, via a receiver onboard the vehicle, signals of a global positioning system and in response thereto producing a first position indication;

providing an attitude and heading reference system onboard the vehicle, wherein the attitude and heading reference system utilizes a plurality of accelerometers attached to the vehicle and a plurality of gyroscopes attached to the vehicle;

deriving a second position indication from data provided by the plurality of accelerometers and the plurality of gyroscopes; and

employing the first and second position indications to produce a present position indication for the vehicle.

9. The navigation method as recited in claim 8 wherein deriving a second position indication employs an inertial strapdown navigation algorithm.

10. The navigation method as recited in claim 8 wherein the present position indication for the vehicle is produced by applying a recursive data processing algorithm to the first and second position indications.

11. The navigation method as recited in claim 8 wherein the present position indication for the vehicle is produced by applying a Kalman filter function to the first and second position indications.

12. The navigation method as recited in claim 11 wherein the Kalman filter function produces bias data indicating errors in the data provided by the plurality of accelerometers and the plurality of gyroscopes;

and further comprising employing the bias data to compensate the data provided by the plurality of accelerometers and the plurality of gyroscopes, and then using such compensated data in deriving the second position indication.

13. The navigation method as recited in claim 8 wherein the first position indication is produced repeatedly at a first frequency;

and the second position indication is produced repeatedly at a second frequency that is greater than the first frequency.

14. The navigation method as recited in claim 8 further comprising:

deriving a first velocity indication from the signals of a global positioning system;

deriving a second velocity indication from data provided by the plurality of accelerometers and the plurality of gyroscopes; and

employing the first and second velocity indications to produce a present velocity indication for the vehicle.

15. The navigation method as recited in claim 14 wherein the present position indication and the present velocity indication are produced by applying a recursive data processing algorithm to the first and second position indications and to the first and second velocity indications.

16. The navigation method as recited in claim 14 wherein the present position indication and the present velocity indication are produced by applying a Kalman filter function to the first and second position indications and to the first and second velocity indications.

17. The navigation method as recited in claim 14 wherein the first position indication is produced repeatedly at a first frequency;

and the second position indication is produced repeatedly at a second frequency that is greater than the first frequency.

18. A navigation method for a vehicle comprising:

receiving, onboard the vehicle, signals of a global positioning system and in response thereto producing a first position indication and a first velocity indication;

providing, onboard the vehicle, an attitude and heading reference system that includes a plurality of accelerometers attached to the vehicle and a plurality of gyroscopes attached to the vehicle;

deriving a second position indication from accelerometer data and gyroscope data provided from the attitude and heading reference system;

deriving a second velocity indication from accelerometer data and gyroscope data provided from the attitude and heading reference system; and

applying a Kalman filter function to the first and second position indications and to the first and second velocity indications to thereby produce a present position indication and a present velocity indication.

19. The navigation method as recited in claim 18 wherein deriving a second position indication and deriving a second velocity indication employs a inertial strapdown navigation algorithm.

20. The navigation method as recited in claim 18 wherein applying a Kalman filter function to produce the present position indication and the present velocity indication occurs repeatedly at a first frequency;

and the second position indication and the second velocity indication are produced repeatedly at a second frequency that is greater than the first frequency.