FORMATION FLIGHT CONTROL

• US 20140214243A1
• Filed: 01/28/2013
• Published: 07/31/2014
• Est. Priority Date: 01/28/2013
• Status: Active Grant

• Current Assignee: The Boeing Co.
• Original Assignee: The Boeing Co.
• Inventors: Bieniawski, Stefan R., Halaas, David, Lavretsky, Eugene, Whitehead, Brian T.
• Granted Patent: US 8,949,090 B2
• Time in Patent Office: Days
• US Class Current: 701/3
• CPC Class Codes: B64C 19/00 Aircraft control not otherwise provided for
• CPC Class Codes: G05D 1/0202 specially adapted to aircraft
• CPC Class Codes: G05D 1/0825 using mathematical models
• CPC Class Codes: G05D 1/104 involving a plurality of aircrafts, e.g. formation flying traffic control systems for aircraft G08G5/00
• CPC Class Codes: Y02T 50/10 Drag reduction

Abstract

An apparatus for controlling the formation flight of a trailing aircraft relative to a vortex generated by a leading aircraft includes a position module, peak-seeking module, limiter module, and control module. The position module is configured to determine a position of the vortex relative to the trailing aircraft. The peak-seeking module is configured to determine a desired position of the trailing aircraft for providing desired vortex-induced aerodynamic benefits based on the position of the vortex relative to the trailing aircraft and a mapping function of an individual performance metric. The limiter module is configured to modify the desired position of the trailing aircraft to avoid unintended crossings of the trailing aircraft into the vortex. Finally, the control module is configured to control flight of the trailing aircraft based on one of the desired position of the trailing aircraft and modified desired position of the trailing aircraft.

Claims

1. An apparatus for controlling a formation flight of a trailing aircraft relative to a vortex generated by a leading aircraft, comprising

a position module configured to determine a position of the vortex relative to the trailing aircraft based on an estimate of wind conditions, the estimate of wind conditions being based on at least one air data measurement obtained by the leading aircraft;

a desired position module configured to determine a desired position of the trailing aircraft relative to the vortex for providing desired vortex-induced aerodynamic benefits based on the position of the vortex; and

a control module configured to control flight of the trailing aircraft based on the desired position of the trailing aircraft.

2. The apparatus of claim 1, wherein the at least one air data measurement obtained by the leading aircraft comprises measurements taken from a plurality of angle of attack and sideslip vane sensors on the leading aircraft.

3. The apparatus of claim 1, wherein the estimate of wind conditions is based on at least one of an estimated sideslip angle and an estimated angle of attack of the trailing aircraft.

4. The apparatus of claim 3, wherein the estimated sideslip angle is based on at least one of a position of an aileron of the trailing aircraft, a position of an upper rudder of the trailing aircraft, a position of a lower rudder of the trailing aircraft, a lateral acceleration of the trailing aircraft, a roll rate of the trailing aircraft, and a yaw rate of the trailing aircraft.

5. An apparatus for controlling a formation flight of a trailing aircraft relative to a vortex generated by a leading aircraft, comprising:

a position module configured to determine a position of the vortex relative to the trailing aircraft based on an estimator state vector comprising a relative position between the vortex and trailing aircraft;

a desired position module configured to determine a desired position of the trailing aircraft relative to the vortex for providing desired vortex-induced aerodynamic benefits based on the position of the vortex; and

a control module configured to control flight of the trailing aircraft based on the desired position of the trailing aircraft.

6. The apparatus of claim 5, wherein the relative position between the vortex and trailing aircraft comprises a relative lateral position of the vortex with respect to the trailing aircraft and a relative vertical position of the vortex with respect to the trailing aircraft.

7. The apparatus of claim 6, wherein the estimator state vector comprises a velocity of the leading aircraft in a lateral direction and a velocity of the leading aircraft in a vertical direction.

8. The apparatus of claim 7, wherein the estimator state vector comprises a wind gust component on the vortex in a lateral direction and a wind gust component on the vortex in a vertical direction.

9. The apparatus of claim 8, wherein the estimator state vector comprises a delay constant and a strength of the vortex.

10. The apparatus of claim 5, wherein the position module is configured to determine the position of the vortex relative to the trailing aircraft based on a measurement vector comprising a plurality of sensed measurements.

11. The apparatus of claim 10, wherein the plurality of sensed measurements comprises a longitudinal position of the leading aircraft relative to the trailing aircraft, a time-delayed lateral position of the leading aircraft relative to the trailing aircraft, a time-delayed vertical position of the leading aircraft relative to the trailing aircraft, a wind gust component acting on the trailing aircraft in a lateral direction, and a wind gust component acting on the trailing aircraft in a vertical direction.

12. The apparatus of claim 10, wherein the position module determines the position of the vortex relative to the trailing aircraft by recursively updating the estimator state vector individually for each of the plurality of sensed measurements using a Kalman filter recursion technique.

13. The apparatus of claim 5, wherein the position module determines the position of the vortex relative to the trailing aircraft based on an estimated vortex-induced component of total body-axes forces acting on the trailing aircraft and an estimated vortex-induced component of a total body-axes moment acting on the trailing aircraft.

14. The apparatus of claim 5, wherein the position module is configured to update the estimator state vector based on a comparison between the position of the vortex relative to the trailing aircraft determined by the position module and at least one actual measurement of the relative position of the trailing aircraft with respect to the vortex.

15. The apparatus of claim 14, wherein the at least one actual measurement is obtained from output signals of a plurality of angle of attack vanes secured to the trailing aircraft.

16. The apparatus of claim 5, wherein the control module is configured to control the flight of the trailing aircraft based on a proportional-integral-derivative architecture.

17. The apparatus of claim 5, wherein the control module is configured to control the flight of the trailing aircraft based on a crosstrack rate feedback value.

18. The apparatus of claim 5, wherein the control module is configured to control the flight of the trailing aircraft based on at least one of a roll feedback value, a rudder feedback value, and a sideslip feedback value.

19. The apparatus of claim 5, wherein the position of the vortex comprises a lateral position component and a vertical position component.

20. An apparatus for controlling a formation flight of a trailing aircraft relative to a vortex generated by a leading aircraft, comprising:

a position module configured to determine a position of the vortex relative to the trailing aircraft;

a desired position module configured to determine a desired position of the trailing aircraft relative to the vortex for providing desired vortex-induced aerodynamic benefits based on the position of the vortex;

a control module configured to control flight of the trailing aircraft based on the desired position of the trailing aircraft by generating at least one command; and

a limiter module configured to monitor the at least one command generated by the control module and modify the at least one command into at least one modified command to avoid unintended crossings of the trailing aircraft into the vortex.

21. The apparatus of claim 20, wherein the limiter module modifies the at least one command into the at least one modified command by limiting one of a crosstrack position of the trailing aircraft and a velocity of the trailing aircraft in a crosstrack direction.

22. The apparatus of claim 20, wherein the limiter module modifies the at least one command into the at least one modified command when a parameter being limited meets a threshold.

23. The apparatus of claim 20, wherein the limiter module limits a velocity of the trailing aircraft in a crosstrack direction as a function of a position of the trailing aircraft relative to a core of the vortex in the crosstrack direction.

24. The apparatus of claim 23, wherein as the position of the trailing aircraft relative to the core of the vortex in the crosstrack direction decreases, an allowed velocity of the trailing aircraft in the crosstrack direction is reduced.

25. The apparatus of claim 20, wherein the limiter module modifies the at least one command via a low-pass filter with one-side rate-saturation.

26. The apparatus of claim 20, wherein the limiter module modifies the at least one command when the trailing aircraft is moving toward the vortex, and does not modify the at least one command when the trailing aircraft is moving away from the vortex.

27. The apparatus of claim 20, wherein the limiter module modifies the at least one command when a threshold is met, and stops modifying the at least one command after the threshold ceases to be met, wherein the limiter module is configured to control a rate at which the at least one modified command returns to the at least one command after the threshold ceases to be met via a one-sided low-pass filter.

28. An apparatus for controlling a formation flight of a trailing aircraft relative to a vortex generated by a leading aircraft, comprising:

a position module configured to determine a position of the vortex relative to the trailing aircraft;

a peak-seeking module configured to determine a desired position of the trailing aircraft for providing desired vortex-induced aerodynamic benefits based on the position of the vortex relative to the trailing aircraft and a mapping function of an individual performance metric; and

a control module configured to control flight of the trailing aircraft based on the desired position of the trailing aircraft.

29. The apparatus of claim 28, wherein the individual performance metric is a function of the position of the trailing aircraft relative to the vortex.

30. The apparatus of claim 28, wherein the peak-seeking module estimates a shape of a quadratic model patterned within a region defined by a search pattern comprising a plurality of estimated values of an element of an estimator state vector, each estimated value being associated with a separate evaluation of the mapping function for each of a plurality of different variable values.

31. The apparatus of claim 30, wherein a bottom of the shape of the quadratic model defines one of a minimum and maximum value of the element of the estimator state vector, and wherein the desired position of the trailing aircraft is based on the one of the minimum and maximum value of the element.

32. The apparatus of claim 31, wherein the shape of the quadratic model is a first shape, the search pattern is a first search pattern, and the one of the minimum and maximum value of the element is a first minimum and first maximum value of the element, respectively, wherein the peak-seeking module estimates a second shape of the quadratic model patterned within a region defined by a second search pattern positioned locally about the one of the minimum and maximum value of the element, the second shape of the quadratic model being smaller than the first shape of the quadratic model and the second search pattern being smaller than the first search pattern, and wherein a bottom of the second shape of the quadratic model defines one of a second minimum and maximum value of the element, and wherein the desired position of the trailing aircraft is revised according to the one of the second minimum and maximum value of the element.

33. The apparatus of claim 28, wherein the peak-seeking module evaluates the mapping function according to a recursion scheme for each element of an estimator state vector, wherein for each element of the estimator state, the peak-seeking module determines an estimated value of the element, an estimated optimal position error, and an uncertainty factor representing a prediction of how close the estimated value of the element is to an actual value of the element, and wherein the peak-seeking module determines the desired position of the trailing aircraft based on the estimated state vector and the estimated optimal position error.

34. The apparatus of claim 33, wherein the peak-seeking module determines the estimated value of the element by generating a search pattern comprising a plurality of estimated values of the element, and wherein the peak-seeking module is configured to scale a size of search pattern based on the uncertainty factor.

35. An apparatus for controlling a formation flight of a trailing aircraft relative to a vortex generated by a leading aircraft, comprising:

a position module configured to determine a position of the vortex relative to the trailing aircraft based on an estimate of wind conditions at the leading aircraft and an estimator state vector comprising a relative position between the vortex and the trailing aircraft;

a peak-seeking module configured to determine a desired position of the trailing aircraft for providing desired vortex-induced aerodynamic benefits based on the position of the vortex relative to the trailing aircraft and a mapping function of an individual performance metric;

limiter module configured to monitor the desired position of the trailing aircraft and modify the desired position of the trailing aircraft into a modified desired position of the trailing aircraft to avoid unintended crossings of the trailing aircraft into the vortex; and

a control module configured to control flight of the trailing aircraft based on one of the desired position of the trailing aircraft and modified desired position of the trailing aircraft.