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EP-4631862-B1 - BOOM GUIDANCE SYSTEM FOR AUTOMATED AIR-TO-AIR REFUELING

EP4631862B1EP 4631862 B1EP4631862 B1EP 4631862B1EP-4631862-B1

Inventors

  • JANG, JUNG SOON

Dates

Publication Date
20260513
Application Date
20250313

Claims (15)

  1. A boom guidance system (11) for use during an automated air-to-air refueling, A3R, mission, the boom guidance system (11) comprising: a plurality of sensors (21) configured to output sensor data (201) indicative of a three-dimensional, 3D, position of a fuel-receiving aircraft, receiver, (12) and a refueling boom (18) of a fuel-supplying aircraft (10) in a receiver reference frame and a boom reference frame, respectively; and an electronic control unit, ECU, (50) in communication with the plurality of sensors (21), wherein the ECU (50) is programmed to: read a 3D model (55-R) of the receiver (12) from memory (52) of the ECU (50); receive the sensor data (201), including a position of the receiver (12) in the receiver reference frame and a pitch, roll, and telescope length of the boom (18) in the boom reference frame; map a set of points in the receiver reference frame to the boom reference frame as mapped points using the 3D model (55-R) of the receiver (12) and a linear model (55-B) of the boom (18); compute a set of Euclidian radial distances (Δr i ) between each of the mapped points and each respective point on the boom (18); determine a minimum Euclidian radial distance (Δr min ) in the set of Euclidian distances (Δr i ); and execute a flight control operation of the boom (18) during the A3R mission in response to the minimum Euclidian radial distance (Δr min ) being less than a threshold minimum distance.
  2. The boom guidance system (11) of claim 1, wherein the memory (52) of the ECU (50) includes a library (55) of different receiver models (55-R), and wherein the ECU (50) is programmed to identify the receiver (12) prior to or during the A3R mission, and thereafter select the 3D model (55-R) of the receiver (12) from the library (55) based on an identity of the receiver (12).
  3. The boom guidance system (11) of any preceding claim, wherein the plurality of sensors (21) includes a rearward-facing camera (20) configured to output real-time image data (200) as part of the sensor data (201), and wherein the ECU (50) is configured to identify the receiver (12) during the A3R mission by recognizing the receiver (12) in the real-time image data (200).
  4. The boom guidance system (11) of any preceding claim, wherein the ECU (50) is programmed to create a bounding box (62) around a current position of the boom (18), a volume of the bounding box (62) being based on a predetermined speed of movement of the boom (18), and to compute the set of Euclidian radial distances (Δr i ) only for points located within the volume of the bounding box (62).
  5. The boom guidance system (11) of any preceding claim, wherein the ECU (50) is programmed to determine a closure rate ( Δṙ min ) of the boom (18) to the receiver (12), and to selectively adjust the threshold minimum distance in real-time based on the closure rate ( Δ ṙ min ) .
  6. The boom guidance system (11) of claim 5, wherein the ECU (50) is programmed with a lookup table (80) indexed by the threshold minimum distance and the closure rate ( Δṙ min ) , and to select the threshold minimum distance from the lookup table (80) using the closure rate ( Δṙ min ).
  7. The boom guidance system (11) of any preceding claim, wherein the ECU (50) is programmed to execute the flight control operation of the boom (18) by transmitting flight control signals (CC 19 ) to one or more flight control surfaces (19) on the boom (18) to thereby cause the boom (18) to increase the minimum Euclidian radial distance (Δr min ) until the minimum Euclidian distance (Δr min ) exceeds the threshold minimum distance.
  8. The boom guidance system (11) of any preceding claim, wherein the ECU (50) is programmed to initiate an overriding flight control action in response to detection of a breakaway maneuver of the receiver (12).
  9. A method for controlling an automated air-to-air refueling, A3R, mission, comprising: reading a three-dimensional, 3D, model (55-R) of a fuel-receiving aircraft, receiver, (12) from memory (54) of an electronic control unit, ECU, (50); receiving sensor data (201) from a plurality of sensors (21) via the ECU (50), the sensor data (201) being indicative of a 3D position of the receiver (12) and a position of a refueling boom (18) of a fuel-supplying aircraft (10) in a receiver reference frame and a boom reference frame, respectively, the sensor data (201) including pitch, roll, and telescope length of the boom (18) in the boom reference frame; mapping a set of points in the receiver reference frame to the boom reference frame as mapped points using the 3D model of the receiver (12) and a linear model (55-B) of the boom (18); computing a set of Euclidian radial distances (Δr i ) between each of the mapped points and each respective point on the boom (18); determining a minimum Euclidian radial distance (Δr min ) in the set of Euclidian distances (Δr i ); and executing a flight control operation of the boom (18) via the ECU (50) in response to the minimum Euclidian radial distance (Δr min ) being less than a threshold minimum distance.
  10. The method of claim 9, further comprising: determining an identity of the receiver (12) via the ECU (50); and selecting the 3D model (55-R) of the receiver (12), from a library (55) stored in memory (52) of the ECU (50), based on the identity of the receiver (12).
  11. The method of claim 10, further comprising: determining the identity of the receiver (12) in real-time during the A3R mission by recognizing the receiver (12) in real-time image data from one or more of the sensors (21), via the ECU (50), wherein the sensor data (201) includes the real-time image data (200).
  12. The method of any of claims 9 to 11, further comprising: creating a bounding box (62) around a current position of the boom (18) via the ECU (50), wherein a volume of the bounding box (62) is based on a predetermined speed of movement of the boom (18); and computing the set of Euclidian radial distances (Δr i ) only for points located within the volume of the bounding box (62).
  13. The method of any of claims 9 to 12, further comprising: determining a closure rate ( Δṙ min ) of the boom (18) to the receiver (12) via the ECU (50); and selectively adjusting the threshold minimum distance in real-time based on the closure rate ( Δṙ min ) , wherein, optionally, the threshold minimum distance is selected from a lookup table (80) via the ECU (50) using the closure rate ( Δṙ min ) of the boom (18).
  14. The method of any of claims 9 to 13, further comprising: executing the flight control operation of the boom (18) by transmitting flight control signals (CC 19 ) to one or more flight control surfaces (19) on the boom (18), the flight control signals (CC 19 ) causing the boom (18) to increase the minimum Euclidian radial distance (Δr min ) until the minimum Euclidian distance (Δr min ) exceeds the threshold minimum distance.
  15. A tanker (10) comprising: a fuselage (24) configured to transport aviation fuel (23); a refueling boom (18) connected to the fuselage (24); and a boom guidance system (11) according to any of claims 1 to 8.

Description

BACKGROUND Air-to-air refueling is a process by which aviation fuel is offloaded from a fuel-supplying aircraft (tanker) to a fuel-receiving aircraft (receiver) while the tanker and receiver fly together in a close formation. Air-to-air refueling allows the receiver to remain airborne for extended periods of time or increase its flight range relative to traditional ground-based refueling options. During air-to-air refueling, aviation fuel is offloaded from the tanker to the receiver via an intervening conduit referred to as a refueling boom. A proximal end of the boom is pivotably mounted to the tanker at a point referred to as a boom pivot, while a distal end of the boom (boom tip) is operable for engaging a fuel receptacle on the receiver. The motion trajectory of the boom is typically controlled via a fly-by-wire process in response to manual or automated control inputs. Using a control station, for example, a team of boom operators may carefully align the boom tip with the receptacle via a control input while aircrew of the respective tanker and receiver minimize relative motion of the two aircraft. After achieving proper alignment, the boom tip securely engages the receptable. Aviation fuel is then transferred to the receiver through the boom. Aboard a modem tanker, the aforementioned control station is typically located just aft of the tanker's cockpit. The refueling boom and the receiver are therefore outside of direct view of the boom operators. The boom operators are therefore assisted by a live video feed from a set of tanker-mounted cameras. Real-time image data of the boom and receiver may be projected onto one or more high-resolution display screens of the control station. In this manner, the boom operators are able to closely monitor the aerial refueling process. The same vision system capabilities allow some or all of the refuel process to be automated. In this case, the boom operators may have a reduced supervisory role aboard the tanker. EP 3 566 949 A1, according to its abstract, states that a system is provided which includes a camera on a refueling aircraft to obtain an image of a receiver aircraft having a receptacle for refueling the receiver aircraft. The system also includes a processor on the refueling aircraft to determine an orientation and position of the receiver aircraft relative to the camera, a separation distance and respective positions of a refueling boom of the refueling aircraft and the receptacle. The processor also generates a display of a side perspective view of 3D models of the refueling boom and the receiver aircraft having the receptacle. The display of the side perspective view illustrates a current position of the refueling boom relative to a current position of the receptacle and enables an operator on the refueling aircraft to observe and guide the refueling boom to the receptacle. US 2018/0350104 A1, according to its abstract, states a system for detecting the tube tip of the flying boom of a tanker aircraft and the receptacle mouth of the receiver for semi-automatic or automatic contact for in-flight aerial refueling with a boom, which does not incorporate signaling devices installed on the receiver aircraft, wherein the system and associated method are robust and ensure that the tanker boom control system is provided with real-time, robust, reliable and simultaneous information, from the tip of the tube thereof and from the receiver aircraft's receptacle mouth, at all times. To this end, the system comprises: 1) light emitters mounted on the tip of the tube thereof, 2) a processing subsystem and 3) two 3D cameras, including a TOF camera or a DOE-type camera (or both), as well as at least one laser L to provide them with their specific functionality. US 2011/0001011 A1, according to its abstract, states an assisted in-flight refuelling system having a tanker aircraft equipped with a drogue; a fuel take-on aircraft equipped with a probe; and a drogue-probe coupling assist system designed to determine a first distance between the drogue and the take-on aircraft/probe, a second distance between the tanker aircraft and the drogue, and a third distance between the tanker aircraft and the take-on aircraft. The drogue-probe coupling assist system is also designed to determine information relative to the necessary movement of the drogue and/or the necessary movement of the take-on aircraft to couple the drogue to the probe, as a function of the first, second, and third distance. SUMMARY The present disclosure relates to systems and methods for performing an aerial refueling process, in particular a boom-type automated air-to-air refueling (A3R) mission during which a refueling boom is used to offload aviation fuel from a fuel-supplying aircraft (tanker) to a fuel-receiving aircraft (receiver). In particular, the technical solutions described herein allow a computerized control station, possibly monitored or controlled by boom operators located onboard the tanker as