Precision Approach Guidance System And Associated Method

• US 20080119970A1
• Filed: 01/24/2006
• Published: 05/22/2008
• Est. Priority Date: 01/24/2005
• Status: Active Grant

• Current Assignee: Ohio University
• Original Assignee: Ohio University
• Inventors: Van Graas, Frank, De Haag, Maarten Uilt, Campbell, Jacob L.
• Granted Patent: US 7,920,943 B2
• Time in Patent Office: Days
• US Class Current: 701/8
• CPC Class Codes: G05D 1/0676 specially adapted for landing

Abstract

A precision approach guidance system that provides flying craft guidance information during a precision approach to a landing site and methods associated therewith are provided. In one embodiment, the system includes: an inertial navigation system, an onboard ranging sensor, a terrain database storing previously identified position-referenced terrain information associated with the landing site, and a position determining process. The position determining process repetitively determines a corrected position of the flying craft during the precision approach based at least in part on attitude and velocity information from an inertial navigation system, current position-referenced terrain information based on measurements from an onboard ranging sensor, and previously identified position-referenced terrain information from the terrain database.

Claims

1. A method of providing flying craft guidance information during a precision approach to a landing site, the method including:

a) providing a terrain database storing previously identified position-referenced terrain information associated with the landing site; and

b) repetitively determining a corrected position of the flying craft during the precision approach based at least in part on attitude and velocity information from an inertial navigation system, current position-referenced terrain information based on measurements from an on-board ranging sensor, and previously identified position-referenced terrain information from the terrain database.

2. The method set forth in claim 1 wherein the determining in b) is performed when a value for a parameter associated with a current position of the flying craft is in a first logical relation to a predetermined threshold value, the method further including:

c) repetitively determining the corrected position of the flying craft during the precision approach based at least in part on attitude and velocity information from the inertial navigation system when the value for the parameter associated with the current position of the flying craft is in a second logical relation to the predetermined threshold value;

wherein the predetermined threshold value is between parameter values in first logical relation and parameter values in second logical relation.

3. The method set forth in claim 2 wherein the determining in c) is also based at least in part on position information from an onboard radio receiver associated with a radio navigation system.

4. The method set forth in claim 3 wherein the radio navigation system includes a global positioning system (GPS) navigation system and the onboard radio receiver includes a GPS receiver.

5. The method set forth in claim 4 wherein the position information from the onboard radio receiver includes GPS carrier phase information and the determining in c) includes use of the GPS carrier phase information to compensate for drift error associated with the inertial navigation system.

6. The method set forth in claim 4 wherein the radio navigation system includes a wide area augmentation system (WAAS) and the onboard radio receiver includes a WAAS receiver.

7. The method set forth in claim 6 wherein the position information from the onboard radio receiver includes WAAS position information and the determining in c) includes use of the WAAS position information to compensate for position error associated with the GPS navigation system and to further compensate for drift error associated with the inertial navigation system.

8. The method set forth in claim 2 wherein the parameter associated with the current position of the flying craft is height above a ground level associated with the landing site and the determining in c) is performed when the parameter value is greater than the predetermined threshold value.

9. The method set forth in claim 1 wherein the terrain database includes a three-dimensional (3-D) terrain model associated with the landing site formed by a plurality of previously identified points and the onboard ranging sensor is configured to scan a terrain surface area associated with the current position of the flying craft to provide the measurements used to form the current position-referenced terrain information.

10. The method set forth in claim 9, each iteration of determining the corrected position in b) further including:

c) identifying an initial position of the flying craft based at least in part on attitude and velocity information from the inertial navigation system;

d) relating the initial position to an initial previously identified point from the previously identified position-referenced terrain information in the terrain database and to an initial currently identified point of the current position-referenced terrain information based on measurements from the onboard ranging sensor;

e) performing a gradient-based search technique for a minimum mean of the square error agreement metric to adjust one of the previously identified position-referenced terrain information and current position-referenced terrain information in relation to each other to identify an acceptable match between the current position-referenced terrain information and the terrain database and to estimate a corresponding position error; and

f) adjusting the corrected position to compensate for the estimated position error.

11. A precision approach guidance system that provides flying craft guidance information during a precision approach to a landing site, the system including:

an inertial navigation system;

an onboard ranging sensor;

a terrain database storing previously identified position-referenced terrain information associated with the landing site; and

a position determining process in communication with the inertial navigation system, onboard ranging sensor, and terrain database;

wherein the position determining process repetitively determines a corrected position of the flying craft during the precision approach based at least in part on attitude and velocity information from the inertial navigation system, current position-referenced terrain information based on measurements from the onboard ranging sensor, and previously identified position-referenced terrain information from the terrain database.

12. The system set forth in claim 11 wherein corrected positions of the flying craft that are based at least in part on attitude and velocity information from an inertial navigation system, current position-referenced terrain information based on measurements from the onboard ranging sensor, and previously identified position-referenced terrain information from the terrain database are determined when a value for a parameter associated with a current position of the flying craft is in a first logical relation to a predetermined threshold value;

and

wherein the position determining process repetitively determines the corrected position of the flying craft during the precision approach based at least in part on attitude and velocity information from the inertial navigation system when the value for the parameter associated with the current position of the flying craft is in a second logical relation to the predetermined threshold value;

wherein the predetermined threshold value is between parameter values in first logical relation and parameter values in second logical relation.

13. The system set forth in claim 12, further including:

an onboard radio receiver associated with a radio navigation system;

wherein corrected positions of the flying craft determined by the position determining process when the value for the parameter associated with the current position of the flying craft is in the second logical relation to the predetermined threshold value are also based at least in part on position information from the onboard radio receiver.

14. The system set forth in claim 13 wherein the radio navigation system includes a global positioning system (GPS) navigation system and the onboard radio receiver includes a GPS receiver.

15. The system set forth in claim 14 wherein the radio navigation system includes a wide area augmentation system (WAAS) and the onboard radio receiver includes a WAAS receiver.

16. The system set forth in claim 12 wherein the parameter associated with the current position of the flying craft is height above a ground level associated with the landing site and parameter values in second logical relation to the predetermined threshold value are greater than the predetermined threshold value.

17. The system set forth in claim 11 wherein the onboard ranging sensor includes an onboard laser scanner.

18. The system set forth in claim 11 wherein the terrain database includes a three-dimensional (3-D) terrain model associated with the landing site formed by a plurality of previously identified points and the onboard ranging sensor is configured to scan a terrain surface area associated with the current position of the flying craft to provide the measurements used to form the current position-referenced terrain information.

19. The system set forth in claim 11 wherein the flying craft is an aircraft.

20. The system set forth in claim 11 wherein the flying craft is a spacecraft.

21. A precision approach guidance system that provides flying craft guidance information during a precision approach to a landing site, the system including:

an inertial navigation system;

an onboard ranging sensor;

a terrain database storing previously identified position-referenced terrain information associated with the landing site; and

first means for repetitively determining a corrected position of the flying craft during the precision approach based at least in part on attitude and velocity information from the inertial navigation system, current position-referenced terrain information based on measurements from the onboard ranging sensor, and previously identified position-referenced terrain information from the terrain database.

22. The system set forth in claim 21 wherein the first means for repetitively determining corrected positions of the flying craft is active when a value for a parameter associated with a current position of the flying craft is in a first logical relation to a predetermined threshold value, the system further including:

second means for repetitively determining the corrected position of the flying craft during the precision approach based at least in part on attitude and velocity information from the inertial navigation system when the value for the parameter associated with the current position of the flying craft is in a second logical relation to the predetermined threshold value;

wherein the predetermined threshold value is between parameter values in first logical relation and parameter values in second logical relation.

23. The system set forth in claim 22, further including:

an onboard radio receiver associated with a radio navigation system;

wherein the second means for repetitively determining the corrected position of the flying craft is also based at least in part on position information from the onboard radio receiver.

24. The system set forth in claim 23 wherein the radio navigation system includes a global positioning system (GPS) navigation system and the onboard radio receiver includes a GPS receiver.

25. The system set forth in claim 24 wherein the radio navigation system includes a wide area augmentation system (WAAS) and the onboard radio receiver includes a WAAS receiver.

26. The system set forth in claim 22 wherein the parameter associated with the current position of the flying craft is height above a ground level associated with the landing site and parameter values in second logical relation to the predetermined threshold value are greater than the predetermined threshold value.

27. The system set forth in claim 21 wherein the onboard ranging sensor includes an onboard laser scanner.

28. The system set forth in claim 21 wherein the terrain database includes a three-dimensional (3-D) terrain model associated with the landing site formed by a plurality of previously identified points and the onboard ranging sensor is configured to scan a terrain surface area associated with the current position of the flying craft to provide the measurements used to form the current position-referenced terrain information.