METHOD AND APPARATUS FOR DETECTING ANOMALIES IN LANDING SYSTEMS UTILIZING A GLOBAL NAVIGATION SATELLITE SYSTEM

• US 20090069960A1
• Filed: 09/12/2007
• Published: 03/12/2009
• Est. Priority Date: 09/12/2007
• Status: Active Grant

• Current Assignee: The Boeing Co.
• Original Assignee: The Boeing Co.
• Inventors: Murphy, Timothy Allen, Lapp, Tiffany R.
• Granted Patent: US 7,970,503 B2
• Time in Patent Office: Days
• US Class Current: 701/16
• CPC Class Codes: G05D 1/0077 using redundant signals or controls

Abstract

A method, apparatus, and computer program product for detecting anomalies in a landing system. In one embodiment, a magnitude difference between a blended inertial deviation magnitude and a raw deviation magnitude is identified to form a magnitude difference. The magnitude difference is compared to a magnitude threshold. If the magnitude difference exceeds the magnitude threshold, an anomaly in the data is detected.

Claims

1. A computer implemented method for detecting data anomalies in a landing system, the computer implemented method comprising:

identifying a magnitude difference between a blended inertial deviation magnitude and a raw deviation magnitude in a landing system associated with a global navigation satellite system to form a magnitude difference;

comparing the magnitude difference to a magnitude threshold; and

responsive to the magnitude difference exceeding the magnitude threshold, detecting an anomaly in the data.

2. The computer implemented method of claim 1 further comprising:

measuring a difference between a blended inertial deviation rate and a raw deviation rate in the landing system associated with the global navigation satellite system to form a rate difference;

responsive to the rate difference exceeding the magnitude threshold, determining whether the rate difference indicates a ramp or a step; and

responsive to the rate difference indicating a ramp error, detecting an anomaly in the data.

3. The computer implemented method of claim 1 further comprising:

generating a dynamic inertial error estimate threshold; and

comparing an un-lagged bias estimate to the dynamic inertial error estimate threshold to determine whether a ramp error is detected.

4. The computer implemented method of claim 3 wherein the dynamic inertial error estimate threshold comprises an upper threshold and a lower threshold, and further comprising:

responsive to the un-lagged bias estimate exceeding the upper dynamic threshold, detecting the ramp error; and

responsive to the un-lagged bias estimate being lower than the lower threshold, detecting the ramp error.

5. The computer implemented method of claim 3 wherein generating the dynamic threshold further comprises:

inputting a bias estimate into a lag filter and generating an upper bound and a lower bound around the bias estimate;

generating an upper dynamic threshold using the upper bound; and

generating a lower dynamic threshold using the lower bound, wherein the upper dynamic threshold and the lower dynamic threshold forms the dynamic threshold.

6. The computer implemented method of claim 2 further comprising:

responsive to detecting an anomaly, triggering inertial coasting.

7. The computer implemented method of claim 4 further comprising:

responsive to detecting the ramp error, indicating a loss of extended coasting capability associated with the global navigation satellite system.

8. The computer implemented method of claim 5 wherein the bias estimate is a velocity bias estimate.

9. The computer implemented method of claim 5 wherein the bias estimate is an acceleration bias estimate.

10. A computer program product comprising:

a computer usable medium including computer usable program code for detecting data anomalies in a landing system, the computer program product comprising;

identifying a magnitude difference between a blended inertial deviation magnitude and a raw deviation magnitude in a landing system associated with a global navigation satellite system to form a magnitude difference;

comparing the magnitude difference to a magnitude threshold; and

responsive to the magnitude difference exceeding the magnitude threshold, triggering inertial coasting.

11. The computer program product of claim 10 further comprising:

computer usable program code for measuring a difference between a blended inertial deviation rate and a raw deviation rate in the landing system associated with the global navigation satellite system to form a rate difference;

computer usable program code for determining whether the rate difference indicates a ramp or a step in response to the rate difference exceeding the magnitude threshold in response to the rate difference exceeding the magnitude threshold; and

computer usable program code for detecting an anomaly in the data in response to the rate difference indicating a ramp.

12. The computer program product of claim 10 further comprising:

computer usable program code for generating a dynamic inertial error estimate threshold; and

computer usable program code for comparing an un-lagged bias estimate to the dynamic inertial error estimate threshold to determine whether a ramp error is detected.

13. The computer program product of claim 12 wherein the dynamic inertial error estimate threshold comprises an upper threshold and a lower threshold, and further comprising:

computer usable program code for detecting the ramp error in response to the un-lagged bias estimate exceeding the upper dynamic threshold; and

computer usable program code for detecting the ramp error in response to the un-lagged bias estimate being lower than the lower threshold.

14. The computer program product of claim 12 further comprising:

computer usable program code for inputting a bias estimate into a lag filter;

computer usable program code for biasing the bias estimate in a positive direction and in a negative direction to generate an upper bound and a lower bound around the bias estimate;

computer usable program code for generating an upper dynamic threshold using the upper bound; and

computer usable program code for generating a lower dynamic threshold using the lower bound, wherein the upper dynamic threshold and the lower dynamic threshold forms the dynamic threshold.

15. The computer program product of claim 10 further comprising:

computer usable program code for triggering inertial coasting in response to detecting an anomaly.

16. The computer program product of claim 13 further comprising:

computer usable program code for indicating a loss of extended coasting capability associated with the global navigation satellite system in response to detecting the ramp error.

17. An anomaly detector in a landing system associated with a global navigation satellite system, the anomaly detector comprising:

a coasting filter, wherein the coasting filter generates a blended inertial deviation magnitude and a blended inertial deviation rate;

a coast skip reset trigger anomaly detector, wherein the coast skip reset trigger anomaly detector identifies a magnitude difference between the blended inertial deviation magnitude and a raw deviation magnitude to form a magnitude difference;

measures a difference between a blended inertial deviation rate and a raw deviation rate to form a rate difference;

compares the magnitude difference to a magnitude threshold;

detects an anomaly in the data in response to the magnitude difference exceeding the magnitude threshold, detecting an anomaly in the data; and

detects the anomaly in the data if the rate difference exceeds the magnitude threshold and the rate difference indicates a ramp.

18. The anomaly detector of claim 17 further comprising:

a slow ramp detector, wherein the slow ramp detector generates a dynamic inertial error estimate threshold;

and compares an un-lagged bias estimate to the dynamic inertial error estimate threshold to determine whether a ramp error is detected.

19. The anomaly detector of claim 18 further comprising:

a lag filter, wherein the lag filter receives a bias estimate;

biases the bias estimate in a positive direction and in a negative direction to generate an upper bound and a lower bound around the bias estimate; and

wherein the slow ramp detector generates an upper dynamic threshold using the upper bound; and

generates a lower dynamic threshold using the lower bound, wherein the upper dynamic threshold and the lower dynamic threshold forms the dynamic threshold.

20. The anomaly detector of claim 17 further comprising:

an indicator, wherein the indicator indicates a loss of extended coasting capability associated with the global navigation satellite system in response to detecting a ramp error.