Adjustment of altitude measurements

• US 9,099,012 B2
• Filed: 07/13/2006
• Issued: 08/04/2015
• Est. Priority Date: 03/14/2005
• Status: Active Grant

• Current Assignee: Cubic Corporation
• Original Assignee: Cubic Corporation
• Inventors: Testrake, Steven G., Ritchie, Gordon
• Primary Examiner(s): Yao, Sam
• Assistant Examiner(s): CARLOS, ALVIN LEABRES
• Application Number:
  US11/486,763
• Publication Number:
  US 20060271249A1
• Time in Patent Office: 3,309 Days
• Field of Search: 434/30, 434/37, 434/38, 701 1- 4
• US Class Current: 1/1
• CPC Class Codes: G01C 23/00 Combined instruments indicating more than one navigational value, e.g. for aircraft; Combined measuring devices for measuring two or more variables of movement, e.g. distance, speed or acceleration
• CPC Class Codes: G09B 9/08 for teaching control of aircraft, e.g. Link trainer

Abstract

This disclosure describes novel systems, methods and software for determining a position of a tracked object, which might be a fixed-wing or rotary-wing aircraft, some other flying object, a vehicle (e.g., an automobile, a tactical military vehicle, etc.), a person, and/or the like. More particularly, in an aspect of this disclosure, a measured altitude for an aircraft is adjusted based on a correction factor, which is determined by comparing a measured altitude at reference point with a known reference elevation for the same reference point. This can provide enhanced accuracy and/or precision in recorded altitude measurements, which allows for more faithful presentation of altitude data, for example in post-mission debriefings, simulations and the like.

Claims

1. A computer-implemented method of determining an elevation of a tracked object for creating a simulation, the method comprising:

(a) identifying, using a first computer system, a set of latitude and longitude coordinates of the tracked object at a fixed reference point at a certain point in time, wherein the first computer system includes a computer-readable storage device and a processor;

(b) identifying, using the first computer system, a reference elevation value corresponding to the set of latitude and longitude coordinates at the certain point in time wherein the tracked object is known to be at the reference elevation at the certain point in time;

(c) measuring a first apparent altitude of the tracked object at the fixed reference point at the certain point in time;

(d) comparing, using the first computer system, the first apparent altitude with the reference elevation value;

(e) based at least in part upon a comparison of the first apparent altitude with the reference elevation value, determining, using the first computer system, a correction factor that can be applied to the first. measured apparent altitude to adjust the first measured apparent altitude to be consistent with the reference elevation value;

(f) measuring one or more additional apparent altitudes of the tracked object over a duration of time to obtain a set of measured altitude values;

(g) storing, on the computer-readable storage medium, the set of measured altitude values;

(h) adjusting, using the first computer system, one or more of the measured altitude values, based at least in part on the correction factor, to obtain a set of adjusted altitude values; and

(i) storing, on the computer-readable storage medium, the set of adjusted altitude values; and

(j) generating, at a second computer system, the simulation of a flight of the tracked object, based at least in part on the stored set of adjusted altitude values.

2. A method as recited by claim 1, wherein the correction factor is weighted when adjusting the one or more of the measured altitude values, and wherein a weighting value accorded to the correction factor in adjusting the one or more of the measured altitude values changes over time.

3. A method as recited by claim 2, such that the correction factor is weighted relatively more heavily in adjusting a first measured altitude value that is measured relatively closer in time to the certain point in time and is weighted relatively less heavily in adjusting a second measured altitude value that is measured relatively further in time from the certain point in time.

4. A method as recited by claim 1, wherein the apparent altitude is measured using a set of global positioning system (“

GPS”

) information.

5. A method as recited by claim 4, wherein the set of GPS information comprises one or more sets of information selected from the group consisting of:

a set of information derived from precision code GPS (“

P-Code GPS”

),

a set of information derived from coarse access code GPS (“

CA-Code”

),

a set of information derived from differential GPS signals, and

a set of information derived from a GPS multilateration technique.

6. A method as recited by claim 1, wherein the apparent altitude is measured using a combination of global positioning system (“

GPS”

) information and barometric data.

7. A method as recited by claim 1, wherein the tracked object comprises one or more objects selected from the group consisting of:

a vehicle,

a person, and

a flying object.

8. A method as recited by claim 1, wherein the tracked object is an aircraft.

9. The method as recited by claim 8, wherein measuring the first apparent altitude of the tracked object comprises determining whether the tracked object is at ground level.

10. The method as recited by claim 9, wherein determining whether the tracked object is on the ground comprises receiving information from a weight on wheels (“

WOW”

) sensor.

11. The method as recited by claim 9, wherein determining whether the tracked object is on the ground comprises analyzing a set of flight data for the aircraft.

12. The method as recited by claim 11, wherein the flight data comprises one or more data elements selected from the group consisting of:

a groundspeed value,

an airspeed value,

a pitch value,

a roll value,

a wind speed value,

a wind direction value, and

a sound pressure level value.

13. The method as recited by claim 1, wherein the one or more additional apparent altitudes are measured subsequent to the certain point in time.

14. The method as recited by claim 1, wherein, for any given measured altitude value, (h) is performed substantially simultaneously with (g).

15. The method as recited by claim 1, wherein (h) is performed by a batch process.

16. A method as recited by claim 15, wherein (a)-(g) are performed during a mission, and wherein (h) is performed after the mission is complete.

17. The method as recited by claim 1, wherein (e) and (h) are performed when the aircraft is on the ground.

18. The method as recited by claim 1, wherein the tracked object is an aircraft, the method further comprising generating, at a computer, a simulation of a flight of the aircraft, based at least in part on the set of adjusted altitude values.

24. The method as recited by claim 1, wherein the one or more additional apparent altitudes are measured prior to the certain point in time.

25. The method of claim 1, wherein adjusting, using the first computer system, one or more of the measured altitude values, based at least in part on the correction factor, to obtain a set of adjusted altitude values utilizes a Kalman Filter.

19. A computer software program product comprising one or more non-transitory computer readable media, the computer software program product comprising:

instructions to collect a set of measured altitude values at a set of intervals of discreet units of time;

instructions to store the set of altitude measurements on a computer readable medium;

instructions to collect a set of latitude and longitude coordinates at the set of intervals of discreet units of time;

instructions to store the set of coordinates on the computer readable medium;

based upon the latitude and longitude coordinates, instructions to reference the set of elevation data;

instructions to store the elevation data on the computer readable medium; and

instructions to compare the measured altitude values to the referenced elevations, wherein a tracked object is known to have been at a reference elevation of the referenced elevations at a certain point in time;

based on the comparison, instructions to determine a correction factor;

instructions to adjust one or more of the measured altitude values, based at least in part on the correction factor, to obtain a set of adjusted altitude values, wherein the one or more measured altitude values are measured prior to the determination of the correction factor; and

instructions to store the set of adjusted altitude values.

20. A computer software program of claim 19 further comprising, instructions to transmit the measured and adjusted altitude values to a ground component.

21. A system comprising a processor and a set of instructions executable by the processor, the set of instructions comprising:

instructions to collect a set of measured altitude values at a set of intervals of discreet units of time;

instructions to store the set of altitude measurements on a computer readable medium;

instructions to collect a set of latitude and longitude coordinates at the set of intervals of discreet units of time;

instructions to store the set of coordinates on the computer readable medium;

based upon the latitude and longitude coordinates, instructions to reference the set of elevation data;

instructions to store the elevation data on the computer readable medium;

instruction to compare the measured altitude values to the reference elevations, wherein a tracked object is known to have been at a reference elevation of the reference elevations at a certain point in time;

based on the comparison, instructions to determine a correction factor;

instructions to adjust one or more of the measured altitude values, based at least in part on the correction factor, to obtain a set of adjusted altitude values, wherein adjustment of the one or more measured altitude values is performed on one or more measured altitude values measured prior to the determination of the correction factor;

instructions to store the set of adjusted altitude values; and

instructions to transmit the set of adjusted altitude values to a ground component.

22. A processor and a set of instructions of claim 21 further comprising, instructions to transmit the measured altitude values to the ground component.

23. A system, comprising:

means for collecting a set of measured altitude values;

storage means for storing the altitude values;

means for determining latitude and longitude coordinates;

means for referencing elevation data, based on the latitude and longitude coordinates;

means for comparing the measured altitude values and the referenced elevation values, wherein a tracked object is known to have been at a referenced elevation of the referenced elevation values at a certain point in time;

means for producing a correction factor, based on the comparison; and

means for regressively adjusting one or more of the measured altitude values, based at least in part on the correction factor, to obtain a set of adjusted altitude values, wherein the one or more of the measured altitude values are stored prior to the production of the correction factor.