Systems and methods for assuring the accuracy of a synthetic runway presentation

• US 9,098,999 B2
• Filed: 09/10/2014
• Issued: 08/04/2015
• Est. Priority Date: 09/13/2013
• Status: Active Grant

• Current Assignee: The Boeing Co.
• Original Assignee: The Boeing Co.
• Inventors: Snow, Paul T., Hooks, Andrew R.
• Primary Examiner(s): Dager, Jonathan M
• Application Number:
  US14/482,237
• Publication Number:
  US 20150081143A1
• Time in Patent Office: 328 Days
• Field of Search: None
• US Class Current: 1/1
• CPC Class Codes: G08G 5/0021 located in the aircraft
• CPC Class Codes: G08G 5/025 Navigation or guidance aids radar or analogous systems specially adapted for landing purposes G01S13/913

Abstract

Automated systems and methods that utilize high-accuracy landing system data to correct the position of a synthetic runway presentation on a pilot display. This is achieved by first computing the “synthetic” lateral and vertical rectilinear deviations of the airplane from an ideal beam using the airplane'"'"'s GPS position and barometric altitude, the runway location and orientation contained in an airborne database, and approach angle information. This synthetic deviation data is then compared to rectilinear deviation data computed by the computer system as received from a ground installation. The computer system is programmed to determine the differences between the ground-based and GPS-based rectilinear deviation data and then compute a corrected position vector using those differences. The position of the synthetic runway symbology on the pilot display is adjusted as a function of the corrected position vector.

Claims

1. A method for positioning a synthetic runway presentation on a display screen of a display unit as an airplane approaches a runway, comprising the following steps performed by an onboard computer system:

(a) computing first rectilinear deviation data representing successive estimated rectilinear deviations of the airplane from the desired flight path during the approach, the first rectilinear deviation data being computed based at least in part on airplane sensed angular deviation data from ground-based reference beams and airplane-to-runway distance data;

(b) computing second rectilinear deviation data representing successive estimated rectilinear deviations of the airplane from the desired flight path during the approach, the second rectilinear deviation data being computed based at least in part on airplane latitude, longitude and altitude data and runway data;

(c) computing a corrected position vector based at least in part on a difference between said first and second rectilinear deviation data; and

(d) controlling a display unit to display a synthetic runway presentation having a position on the display screen that is a function of said corrected position vector.

2. The method as recited in claim 1, wherein step (c) comprises filtering differences between said first and second rectilinear deviation data to avoid perceptible motion of the synthetic runway presentation which is not associated with airplane motion.

3. The method as recited in claim 2, further comprising:

computing a display accuracy metric based on differences between unfiltered and filtered differences between said first and second rectilinear deviation data; and

inhibiting display of said synthetic runway presentation if the display accuracy metric indicates a difference greater than a threshold with sufficient persistence when the airplane is beyond a predetermined location on the approach.

4. The method as recited in claim 3, wherein step (d) further comprises controlling the display unit to display a primary guidance cue based on signals from an autopilot, said threshold having a value that assures that an aim point of said synthetic runway presentation will appear within said primary guidance cue when the airplane is stabilized on the approach path.

5. The method as recited in claim 2, further comprising:

computing a display accuracy metric based on differences between unfiltered and filtered differences between said first and second rectilinear deviation data; and

issuing an alert signal to the pilot if the display accuracy metric indicates a difference greater than a threshold with sufficient persistence when the airplane is beyond a predetermined location on the approach.

6. The method as recited in claim 1, wherein step (d) comprises moving said synthetic runway presentation from an uncorrected position on the display screen to said corrected position on the display screen.

7. A method for positioning a synthetic runway presentation on a display screen of a display unit as an airplane approaches a runway, comprising the following steps performed by an onboard computer system:

(a) obtaining runway and path definition data from an airborne database;

(b) acquiring sensed angular deviation data from ground-based reference beams and latitude, longitude and altitude data for the aircraft during its approach, said angular deviation data representing successive angular deviations of the airplane from a desired flight path;

(c) computing distance data representing successive distances of the airplane from the runway during the approach based on the latitude, longitude and altitude data and the runway data;

(d) computing first rectilinear deviation data representing successive estimated rectilinear deviations of the airplane from the desired flight path during the approach, the first rectilinear deviation data being computed based at least in part on the angular deviation data and the distance data;

(e) computing second rectilinear deviation data representing successive estimated rectilinear deviations of the airplane from the desired flight path during the approach, the second rectilinear deviation data being computed based at least in part on the latitude, longitude and altitude data representing a corrected position vector and the runway data;

(f) computing a corrected position vector based at least in part on a difference between said first and second rectilinear deviation data; and

(g) controlling a display unit to display a synthetic runway presentation having a position on a display screen that is a function of said corrected position vector.

8. The method as recited in claim 7, wherein step (f) comprises filtering differences between said first and second rectilinear deviation data to avoid perceptible motion of the synthetic runway presentation which is not associated with airplane motion.

9. The method as recited in claim 8, further comprising:

computing a display accuracy metric based on differences between unfiltered and filtered differences between said first and second rectilinear deviation data; and

inhibiting display of said synthetic runway presentation if the display accuracy metric indicates a difference greater than a threshold with sufficient persistence when the airplane is beyond a predetermined location on the approach.

10. The method as recited in claim 9, wherein step (g) further comprises controlling the display unit to display a primary guidance cue based on signals from an autopilot, said threshold having a value assuring that an aim point of said synthetic runway presentation will appear within said primary guidance cue when the airplane is stabilized on an approach path.

11. The method as recited in claim 8, further comprising:

computing a display accuracy metric based on differences between unfiltered and filtered differences between said first and second rectilinear deviation data; and

issuing an alert signal to the pilot if the display accuracy metric indicates a difference greater than a threshold with sufficient persistence when the airplane is beyond a predetermined location on the approach.

12. The method as recited in claim 7, wherein step (g) comprises moving said synthetic runway presentation from an uncorrected position on the display screen to said corrected position on the display screen.

13. A device for displaying a synthetic runway as an airplane approaches a runway, comprising a display screen and a computer system programmed to perform the following operations:

(a) computing first rectilinear deviation data representing successive estimated rectilinear deviations of the airplane from the desired flight path during the approach, the first rectilinear deviation data being computed based at least in part on airplane sensed angular deviation data from ground-based reference beams and airplane-to-runway distance data;

(b) computing second rectilinear deviation data representing successive estimated rectilinear deviations of the airplane from the desired flight path during the approach, the second rectilinear deviation data being computed based at least in part on airplane latitude, longitude and altitude data and runway data;

(c) computing a corrected position vector based at least in part on a difference between said first and second rectilinear deviation data; and

(d) controlling said display screen to display a synthetic runway presentation having a position that is a function of said corrected position vector.

14. The device as recited in claim 13, wherein step (c) comprises filtering differences between said first and second rectilinear deviation data to avoid perceptible motion of the synthetic runway presentation which is not associated with airplane motion.

15. The device as recited in claim 14, wherein said computer system is further programmed to perform the following operations:

computing a display accuracy metric based on differences between unfiltered and filtered differences between said first and second rectilinear deviation data; and

inhibiting display of said synthetic runway presentation if the display accuracy metric indicates a difference greater than a threshold with sufficient persistence when the airplane is beyond a predetermined location on the approach.

16. The device as recited in claim 15, wherein step (d) further comprises controlling the display unit to display a primary guidance cue based on signals from an autopilot, said threshold having a value that assures that an aim point of said synthetic runway presentation will appear within said primary guidance cue when the airplane is stabilized on the approach path.

17. The device as recited in claim 13, wherein step (d) comprises moving said synthetic runway presentation from an uncorrected position on the display screen to said corrected position on the display screen.

18. An onboard system for positioning a synthetic runway presentation on a display screen of a display unit as an airplane approaches a runway, said onboard system comprising:

a display unit comprising a display screen;

a localizer receiver that provides lateral difference in depth of modulation data;

a GPS receiver for receiving GPS signals;

a database containing runway data for a runway and path definition data; and

a computer system programmed to perform the following operations;

(a) determining a latitude and a longitude of the airplane from said GPS signals;

(b) determining an altitude of the airplane;

(c) computing a distance separating the airplane and a point on the runway based at least in part on at least said latitude, said longitude, said altitude, said runway data, and said path definition data;

(d) computing a lateral angular deviation of the airplane based at least in part on said lateral difference in depth of modulation data;

(e) computing a lateral rectilinear deviation of the airplane based at least in part on said distance and said lateral angular deviation;

(f) computing a synthetic lateral rectilinear deviation of the airplane based at least in part on said distance and said path definition data;

(g) computing a first difference between said lateral rectilinear deviation and said synthetic lateral rectilinear deviation;

(h) computing a corrected lateral position based at least in part on said first difference and a lateral position characterized by said latitude and said longitude of the airplane; and

(i) controlling said display unit to display on said display screen a synthetic runway presentation having a lateral position that is a function of said corrected lateral position.

19. The system as recited in claim 18, further comprising a lag filter that filters said difference between said lateral rectilinear deviation and said synthetic lateral rectilinear deviation.

20. The system as recited in claim 18, further comprising a glideslope receiver that provides vertical difference in depth of modulation data, wherein said computer system is further programmed to perform the following operations:

(j) computing a vertical angular deviation of the airplane based at least in part on said vertical difference in depth of modulation data;

(k) computing a vertical rectilinear deviation of the airplane based at least in part on said distance and said vertical angular deviation;

(l) computing a synthetic vertical rectilinear deviation of the airplane based at least in part on said distance and said path definition data;

(m) computing a second difference between said vertical rectilinear deviation and said synthetic vertical rectilinear deviation; and

(n) computing a corrected vertical position based at least in part on said second difference and a vertical position characterized by said latitude and said longitude of the airplane,

wherein operation (i) further comprises controlling said display unit to display on said display screen a synthetic runway presentation having a vertical position that is a function of said corrected vertical position.