Inertially augmented GPS landing system

• US 6,178,363 B1
• Filed: 12/22/1998
• Issued: 01/23/2001
• Est. Priority Date: 12/22/1998
• Status: Expired due to Term

• Current Assignee: The Boeing Co.
• Original Assignee: The Boeing Co.
• Inventors: McIntyre, Melville D., Anderson, Leonard R.
• Primary Examiner(s): Tarcza, Thomas H.
• Assistant Examiner(s): Mull, Fred H.
• Application Number:
  US09/219,552
• Time in Patent Office: 763 Days
• Field of Search: 342/357.06, 342/33, 342/34, 342/35, 342/357.03, 342/358, 342/357.17, 342/357.13, 342/357.14, 701/16, 701/17
• US Class Current: 701/16
• CPC Class Codes: G01S 19/08 providing integrity information, e.g. health of satellites or quality of ephemeris data
• CPC Class Codes: G01S 19/15 Aircraft landing systems
• CPC Class Codes: G01S 19/20 Integrity monitoring, fault detection or fault isolation of space segment
• CPC Class Codes: G01S 19/41 Differential correction, e.g. DGPS [differential GPS]
• CPC Class Codes: G01S 19/49 whereby the further system is an inertial position system, e.g. loosely-coupled
• CPC Class Codes: G01S 19/51 Relative positioning
• CPC Class Codes: G01S 19/52 Determining velocity
• CPC Class Codes: G05D 1/0676 specially adapted for landing

Abstract

An airplane precision approach guidance system and method. The airplane precision approach guidance system includes: (i) GPS landing system (GLS) components (12) for receiving and processing signals from GPS satellites (30) and a GPS ground station (32) and generating a first set of velocities; (ii) an inertial reference system (IRS)(20) for generating a second set of velocities; and (iii) guidance software (24) for generating a cross-runway velocity and a lateral distance from runway centerline based on received runway centerline information and the generated first and second set of velocities. The airplane precision approach guidance system also includes flight instruments (26) and an autopilot system (28) for receiving and processing the information produced by the guidance software. The guidance software may be executed by a conventional airplane processor, such as the GLS processor, the IRS processor or the airplane'"'"'s autopilot processor, or by a separate stand-alone processor. The runway centerline information may be stored at the ground station or in local memory. The ground station can also provide differential GPS information. In airplanes that include redundant systems, voting is used to determine which IRS supplies the second set of velocities.

Claims

1. An airplane guidance processor coupled to a global positioning system for generating runway centerline information and an inertial reference system, said airplane guidance processor comprising:

a first filter for generating a first velocity in a first predefined direction based on received velocities in the first predefined direction from the global positioning system and the inertial reference system;

a second filter for generating a second velocity in a second predefined direction based on received velocities in the second predefined direction from the global positioning system and the inertial reference system; and

a third filter for generating a cross-runway velocity and a lateral distance from runway centerline based on the generated runway centerline information and the generated first and second velocities.

2. The processor of claim 1, wherein said third filter further generates the lateral distance from runway centerline based on a lateral distance from runway centerline value received from the global positioning system.

3. The processor of claim 1, wherein the first, second, and third filters are Kalman filters.

4. The processor of claim 1, wherein the first, second, and third filters are complementary filters, respectively.

5. The processor of claim 4, wherein the first and second complementary filters estimate velocity and acceleration biases in the first and second predefined directions of the velocities received from the inertial reference system based on the velocities received from the global positioning system.

6. The processor of claim 5, wherein the first and second complementary filters provide a correcting component for generating the first and second velocities based on the estimated velocity and acceleration biases when the velocities received from the global positioning system become unacceptable.

7. A method for generating airplane navigational signals comprising:

generating a first velocity in a first predefined direction based on received global positioning and inertial reference velocities in the first predefined direction;

generating a second velocity in a second predefined direction based on received global positioning and inertial reference velocities in the second predefined direction; and

generating a cross-runway velocity and a lateral distance from runway centerline value based on received runway centerline information and the generated first and second velocities.

8. The method of claim 7, wherein generating a cross-runway velocity and a lateral distance from runway centerline further generates the lateral distance from runway centerline based on a received global positioning lateral distance from runway centerline value.

9. The method of claim 8, wherein generating a first and second velocity further comprise estimating velocity and acceleration biases in the first and second predefined directions of the received inertial reference velocities based on the received global positioning velocities.

10. The method of claim 9, wherein generating a first and second velocity further comprise generating the first and second velocities based on the estimated velocity and acceleration biases.

11. An airplane precision guidance system comprising:

a global positioning landing system with a differential GPS ground station for generating velocities;

an inertial reference system for generating velocities; and

a guidance processor for generating a cross-runway velocity and a lateral distance from runway centerline based on received runway centerline information and the velocities generated by the global positioning landing system and the inertial reference system.

12. The system of claim 11, further comprising a memory for prestoring said runway centerline information.

13. The system of claim 11, wherein said global positioning landing system comprises a ground station for generating differential global positioning system information.

14. The system of claim 13, wherein said runway centerline information is prestored at the ground station.

15. The system of claim 11, wherein the guidance processor is a component of the global positioning system.

16. The system of claim 11, wherein the guidance processor is a component of the inertial reference system.

17. The system of claim 11, further comprising an autopilot system for generating airplane control signals based on the generated cross-runway velocity and lateral distance from runway centerline.

18. The system of claim 17, wherein the guidance processor is a component of the autopilot system.

19. The system of claim 11, wherein the guidance processor comprises:

a first filter for generating a first velocity in a first predefined direction based on received velocities in the first predefined direction from the global positioning system and the inertial reference system;

a second filter for generating a second velocity in a second predefined direction based on received velocities in the second predefined direction from the global positioning system and the inertial reference system; and

a third filter for generating a cross-runway velocity and a lateral distance from runway centerline based on received runway centerline information and the generated first and second velocities.

20. The system of claim 19, wherein said third filter further generates the lateral distance from runway centerline based on a lateral distance from runway centerline value received from the global positioning system.

21. The system of claim 19, wherein the first, second, and third filters are Kalman filters.

22. The system of claim 19, wherein the first, second, and third filters are complementary filters, respectively.

23. The system of claim 22, wherein the first and second complementary filters further comprise a bias estimating component for estimating velocity and acceleration biases in the first and second predefined directions of the velocities received from the inertial reference system based on the velocities received from the global positioning system.

24. The system of claim 23, wherein the first and second complementary filters further comprise a correcting component for generating the first and second velocities based on the generated velocity and acceleration biases when the velocities received from the global positioning system become unacceptable.

25. The system of claim 19, including a plurality of inertial reference systems for generating velocities and wherein said guidance processor includes a first and second filters for each of said inertial reference systems and selects which of the first and second velocities produced by said first and second filters to use.

26. The system of claim 25 wherein said plurality of inertial reference systems is three and wherein said selection is based on which of the first and second velocities lies between the other two first and second velocities.

27. An airplane precision guidance method comprising:

generating global positioning velocities;

generating inertial reference velocities; and

generating a cross-runway velocity and a lateral distance from runway centerline based on received runway centerline information and the global positioning and inertial reference velocities.

28. The method of claim 27, wherein said global positioning information comprises differential global positioning information.

29. The method of claim 27, wherein generating a cross-runway velocity and a lateral distance from runway centerline comprises:

generating a first velocity in a first predefined direction based on the global positioning and inertial reference velocities defined in the first predefined direction;

generating a second velocity in a second predefined direction based on the global positioning and inertial reference velocities defined in the second predefined direction; and

generating a cross-runway velocity and a lateral distance from runway centerline value based on runway centerline information and the generated first and second velocities.

30. The method of claim 29, wherein generating a cross-runway velocity and a lateral distance from runway centerline value further generates the lateral distance from runway centerline value based on a global positioning lateral distance from runway centerline value.

31. The method of claim 29, wherein generating a first and second velocity further comprise estimating velocity and acceleration biases in the first and second predefined directions of the inertial reference velocities based on the received global positioning velocities.

32. The method of claim 31, wherein generating a first and second velocity further comprise generating the first and second velocities based on the estimated velocity and acceleration biases.

33. The method of claim 27, wherein a plurality of inertial reference velocities are generated, first and second velocities are generated for each of said plurality of inertial reference velocities, and wherein one of said first and second velocities is selected for use in generating said cross-runway velocity and distance from runway centerline.

34. The method of claim 33, wherein said plurality of inertial reference velocities is three and wherein said selection is based on which of the three first and second velocities lies between the other two first and second velocities.

35. An airplane precision approach landing method comprising:

augmenting received global positioning information with inertial reference information;

generating inertial reference bias information during the global positioning information augmentation;

determining acceptability of the global positioning information during a precision approach to landing;

if while on a precision approach to landing the global positioning information is determined to be unacceptable before the airplane reaches a predefined distance from a safe landing and runway roll-out using only corrected inertial reference information, discontinuing the precision approach; and

if while on a precision approach to landing the global positioning information is determined to be unacceptable after the airplane passes a predefined distance from a safe landing and runway roll-out using only inertial reference information, continuing the precision approach using the inertial reference information corrected according to the last generated bias information.

36. An airplane precision approach landing system comprising:

a first component for augmenting received global positioning information with inertial reference information and generating inertial reference bias information during the global positioning information augmentation;

a second component for determining acceptability of the global positioning information during a precision approach to landing; and

a third component for discontinuing a precision approach, if while on the precision approach to landing the global positioning information is determined to be unacceptable before the airplane reaches a predefined distance from a safe landing and runway roll-out using inertial reference information, and using the inertial reference information adjusted according to the generated bias information, if while on a precision approach to landing the global positioning information is determined to be unacceptable after the airplane passes a predefined distance from a safe landing and runway roll-out.