Aerial refueling boom elevation estimation system

• US 10,132,628 B2
• Filed: 03/06/2015
• Issued: 11/20/2018
• Est. Priority Date: 03/06/2015
• Status: Active Grant

• Current Assignee: The Boeing Company
• Original Assignee: The Boeing Co.
• Inventors: Golob, Richard, Hatcher, Justin Cleve, Jang, Jung Soon, Hinson, Kimberly Ann, Musgrave, Jeffrey L.
• Primary Examiner(s): Ho, Anthony
• Application Number:
  US14/640,878
• Publication Number:
  US 20160258750A1
• Time in Patent Office: 1,355 Days
• Field of Search: 702154
• CPC Class Codes: B64D 39/00 Refuelling during flight filling or emptying fuel tanks B64D37/14
• CPC Class Codes: G01C 25/005 initial alignment, calibration or starting-up of inertial devices
• CPC Class Codes: G01C 9/005 specially adapted for use in aircraft
• CPC Class Codes: G01C 9/02 Details

Abstract

An aerial refueling boom elevation estimation (“ARBEE”) system for estimating an elevation angle of an aerial refueling boom on an aerial refueling aircraft is described. The ARBEE system may include a data collector, storage unit, optimizer, and comparator.

Claims

1. A method of estimating an elevation angle of an aerial refueling boom on an aerial refueling aircraft, the method comprising:

collecting measured data signals from a hoist-cable length sensor, a plurality of aerial refueling boom position sensors, and a dynamic pressure sensor;

generating a first database of measured data corresponding to the collected measured data signals;

optimizing the measured data of the first database to create a second database of optimized data corresponding to the measured data, wherein the measured data includes measured aerial refueling boom elevation data and wherein the optimized data includes optimized aerial refueling boom elevation estimation data;

comparing the optimized data to the measured data to determine a difference between the optimized aerial refueling boom elevation data and the measured aerial refueling boom elevation data to determine an elevation data error;

determining if the elevation data error is greater than a predetermined threshold value;

updating the optimized data if the elevation data error is greater than the predetermined threshold value; and

utilizing the optimized data to determine the elevation angle of the aerial refueling boom.

2. The method of claim 1, wherein the measured data further includes measured hoist-cable length data, measured dynamic pressure data, and measured aerial refueling boom azimuth data.

3. The method of claim 2, further including quantizing the measured data prior to saving the measured data to the first database.

4. The method of claim 3, wherein generating a first database includes generating a four-dimensional first database wherein the first-dimension is a range of the measured dynamic pressure data, the second-dimension is a range of the measured hoist-cable length data, the third-dimension is a range of the measured aerial refueling boom azimuth data, and the fourth-dimension is a range of the measured aerial refueling boom elevation data.

5. The method of claim 4, wherein creating a second database of optimized data includes removing the measured aerial refueling boom azimuth data to create a three-dimensional second database where the first-dimension is the range of the measured dynamic pressure data, the second-dimension is a range of the cable length data, and the third-dimension is a range of the optimized aerial refueling boom elevation estimation data.

6. The method of claim 5, wherein the second database is a lookup table which is configured to provide an estimate of the aerial refueling boom elevation angle.

7. The method of claim 6, further including determining a fault has occurred in the plurality of aerial refueling boom position sensors.

8. The method of claim 7, wherein the fault is determined by a fault detector in signal communication with the storage unit, the plurality of aerial refueling boom position sensors, the hoist-cable length sensor, and the dynamic pressure sensor.

9. The method of claim 8, wherein each aerial refueling boom position sensor of the plurality of aerial refueling boom position sensors is a linear variable differential transformer (“

LVDT”

) position sensor.

10. The method of claim 8, wherein determining a fault further includes generating a second estimate of the aerial refueling boom elevation angle with an extended Kalman filter (“

EKF”

) that is configured to receive the measured data and the optimized data, wherein the fault detector receives both the optimized data from the second database and the second estimate of the elevation angle of the aerial refueling boom from the EKF.

11. The method of claim 3,

wherein the measured data further includes a hoist-cable tension and

wherein determining the hoist-cable tension data includes

determining a drag coefficient for a hoist-cable connected between the aerial refueling boom and the aerial refueling aircraft,

determining a linear force density and aero-drag vector for the hoist-cable,

determining a linear force density perpendicular to the aero-drag vector,

determining an aerial refueling boom hoist cable location and hoist-cable stretchers,

determining an arc-length of the hoist-cable,

determining a hoist-cable spring constant, and

determining the hoist-cable tension from the drag coefficient for the hoist-cable, linear force density and aero-drag vector for the hoist-cable, linear force density perpendicular to the aero-drag vector, aerial refueling boom hoist-cable location, hoist-cable stretchers, arc-length of the hoist-cable, and hoist-cable spring constant.

12. An aerial refueling boom elevation estimation (“

ARBEE”

) system for estimating an elevation angle of an aerial refueling boom on an aerial refueling aircraft, the ARBEE system comprising;

a data collector in signal communication with a storage unit having a first database and a second database, a cable length sensor, a plurality of aerial refueling boom position sensors, and a dynamic pressure sensor;

an optimizer; and

a comparator;

wherein the storage unit is in signal communication with the optimizer and the comparator and the optimizer is also in signal communication with the comparator.

13. The ARBEE System of claim 12,

wherein the data collector is configured to receive measured data signals from the plurality aerial refueling boom position sensors, the cable length sensor, and the dynamic pressure sensor and send the measured data from the received measured data signals to the first database,

wherein the measured data includes measured aerial refueling boom elevation data, measured aerial refueling boom azimuth data, measured dynamic pressure data, and measured hoist cable length data corresponding to a measured aerial refueling boom elevation angle, measured aerial refueling boom azimuth angle, measured dynamic pressure exerted on the aerial refueling boom, and measured hoist cable length of a hoist cable coupled between a hoist on the aerial refueling aircraft and the aerial refueling boom, respectively,

wherein the optimizer is configured to receive the measured data from the first database, optimize it, and store it as optimized data in the second database, wherein the optimized data includes optimized aerial refueling boom elevation data that corresponds to a predicted aerial refueling boom elevation angle that was derived from the measured data,

wherein the comparator is configured to determine the difference between the optimized aerial refueling boom elevation estimation data and the measured aerial refueling boom elevation data to determine an elevation data error, compare the elevation data error to a predetermined threshold value, and send error information to the optimizer if the elevation data error is greater than the predetermined threshold value, wherein the optimizer is configured to utilize the error information to further optimize the measured data and store it as updated optimized data in the second database, and

wherein the elevation angle of the aerial refueling boom is determined from the optimized data.

14. The ARBEE System of claim 13, further including a quantizer in signal communication with the data collector and storage unit, wherein the quantizer is configured to quantize an output from the data collector to produce the measured data.

15. The ARBEE System of claim 14, further including a controller in signal communication with the data collector, storage unit, optimizer, and comparator.

16. The ARBEE System of claim 15, further including a fault detector in signal communication with the storage unit, the plurality of aerial refueling boom position sensors, the cable length sensor, and the dynamic pressure sensor, wherein the fault detector is configured to determine if a fault has occurred in the plurality of aerial refueling boom position sensors.

17. The ARBEE System of claim 16, wherein each aerial refueling boom position sensor of the plurality of aerial refueling boom position sensors is a linear variable differential transformer (“

LVDT”

) position sensor.

18. The ARBEE System of claim 17, further including an extended Kalman filter (“

EKF”

) in signal communication with the fault detector, storage unit, a plurality of inertial measurement units (“

IMUs”

), the cable length sensor, and the dynamic pressure sensor, wherein the EKF is configured to estimate the aerial refueling boom elevation angle from the measured data signals from the plurality of IMUs that includes angular rate signals and acceleration signals for control of the aerial refueling boom.

19. A method of estimating an elevation angle of an aerial refueling boom on an aerial refueling aircraft, the method comprising:

receiving measured hoist-cable length data corresponding to the hoist-cable length of a hoist-cable extending from the aerial refueling aircraft to the aerial refueling boom; and

determining an aerial refueling boom elevation angle from the measured hoist-cable length data, a first predetermined constant coefficient value, and a second predetermined constant coefficient value,

wherein the first and second predetermined constant coefficient values are determined by performing a polynomial fit on optimized data stored on an optimized data database,

wherein the optimized data, in the optimized data database, corresponds to measured data from a plurality of aerial refueling boom position sensors, a hoist-cable length sensor, and a dynamic pressure sensor, and

wherein the measured data was collected a priori.

20. The method of claim 19,

wherein the collecting the measured data a priori includes

collecting measured data signals from a plurality of aerial refueling boom position sensors, a hoist-cable length sensor, and a dynamic pressure sensor and

generating a measured database of measured data corresponding to the collected measured data signals and

wherein the optimized data is generated by

optimizing the measured data of the measured database to create the optimized database of optimized data corresponding to the measured data, wherein the measured data includes measured aerial refueling boom elevation data and wherein the optimized data includes optimized aerial refueling boom elevation estimation data,

comparing the optimized data to the measured data to determine a difference between the optimized aerial refueling boom elevation data and the measured aerial refueling boom elevation data to determine an elevation data error,

determining if the elevation data error is greater than a predetermined threshold value, and

updating the optimized data if the elevation data error is greater than the predetermined threshold value.