Boom guidance system for automated air-to-air refueling

1 . A boom guidance system for use during an automated air-to-air refueling (A3R) mission, the boom guidance system comprising:

a plurality of sensors configured to output sensor data indicative of a three-dimensional (3D) position of a fuel-receiving aircraft (receiver) and a boom of a fuel-supplying aircraft (tanker) in a receiver reference frame and a boom reference frame, respectively; and

an electronic control unit (ECU) in communication with the plurality of sensors, wherein the ECU is programmed to:

read a 3D model of the receiver from memory of the ECU;

receive the sensor data, including a position of the receiver in the receiver reference frame and a pitch, roll, and telescope length of the boom 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 of the receiver and a linear model of the boom;

create a bounding box that encompasses at least a boom tip and a boom pivot;

compute a set of Euclidian radial distances between each of the mapped points and each respective point on the boom located within the bounding box;

determine a minimum Euclidian radial distance in the set of Euclidian distances; and

execute a flight control operation of the boom during the A3R mission in response to the minimum Euclidian radial distance being less than a threshold minimum distance.

2 . The boom guidance system of claim 1 , wherein the memory of the ECU includes a library of different receiver models, and wherein the ECU is programmed to identify the receiver prior to or during the A3R mission, and thereafter select the 3D model of the receiver from the library based on an identity of the receiver.

3 . The boom guidance system of claim 2 , wherein the plurality of sensors includes a rearward-facing camera configured to output real-time image data as part of the sensor data, and wherein the ECU is configured to identify the receiver during the A3R mission by recognizing the receiver in the real-time image data.

4 . The boom guidance system of claim 1 , wherein the ECU is programmed to determine a closure rate of the boom to the receiver, and to selectively adjust the threshold minimum distance in real-time based on the closure rate.

5 . The boom guidance system of claim 4 , wherein the ECU is programmed with a lookup table indexed by the threshold minimum distance and the closure rate, and to select the threshold minimum distance from the lookup table using the closure rate.

6 . The boom guidance system of claim 1 , wherein the ECU is programmed to execute the flight control operation of the boom by transmitting flight control signals to one or more flight control surfaces on the boom to thereby cause the boom to increase the minimum Euclidian radial distance until the minimum Euclidian distance exceeds the threshold minimum distance.

7 . The boom guidance system of claim 1 , wherein the ECU is programmed to initiate an overriding flight control action in response to detection of a breakaway maneuver of the receiver.

8 . The boom guidance system of claim 1 , wherein a current position of the boom is determined in real-time via the sensor data.

9 . A method for controlling an automated air-to-air refueling (A3R) mission, comprising:

reading a 3D model of a fuel-receiving aircraft (receiver) from memory of an electronic control unit (ECU);

receiving sensor data from a plurality of sensors via the ECU, the sensor data being indicative of a three-dimensional (3D) position of the receiver and a position of a boom of a fuel-supplying aircraft (tanker) in a receiver reference frame and a boom reference frame, respectively, the sensor data including pitch, roll, and telescope length of the boom 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 and a linear model of the boom;

creating a bounding box that encompasses at least a boom tip and a boom pivot;

computing a set of Euclidian radial distances between each of the mapped points and each respective point on the boom located within the bounding box;

determining a minimum Euclidian radial distance in the set of Euclidian distances; and

executing a flight control operation of the boom via the ECU in response to the minimum Euclidian radial distance being less than a threshold minimum distance.

10 . The method of claim 9 , further comprising:

determining an identity of the receiver via the ECU; and

selecting the 3D model of the receiver, from a library stored in memory of the ECU, based on the identity of the receiver.

11 . The method of claim 10 , further comprising:

determining the identity of the receiver in real-time during the A3R mission by recognizing the receiver in real-time image data from one or more of the plurality of sensors, via the ECU, wherein the sensor data includes the real-time image data.

12 . The method of claim 9 , further comprising:

determining a closure rate of the boom to the receiver via the ECU; and

selectively adjusting the threshold minimum distance in real-time based on the closure rate.

13 . The method of claim 12 , further comprising:

selecting the threshold minimum distance from a lookup table via the ECU using the closure rate of the boom.

14 . The method of claim 9 , further comprising:

executing the flight control operation of the boom by transmitting flight control signals to one or more flight control surfaces on the boom, the flight control signals causing the boom to increase the minimum Euclidian radial distance until the minimum Euclidian distance exceeds the threshold minimum distance.

15 . The method of claim 9 , further comprising:

detecting a breakaway maneuver of the receiver via the ECU; and

initiating an overriding flight control action in response to detection of a breakaway maneuver of the receiver.

16 . The method of claim 9 , wherein a current position of the boom is determined in real-time via the sensor data.

17 . A tanker comprising:

a fuselage configured to transport aviation fuel;

a boom connected to the fuselage; and

a boom guidance system for use during an automated air-to-air refueling (A3R) mission, the boom guidance system comprising:

a plurality of sensors configured to output sensor data indicative of a three-dimensional (3D) position of a fuel-receiving aircraft (receiver) and the boom in a receiver reference frame and a boom reference frame, respectively; and

an electronic control unit (ECU) in communication with the plurality of sensors, wherein the ECU is programmed to:

read a 3D model of the receiver from memory of the ECU;

receive the sensor data, including a position of the receiver in the receiver reference frame and a pitch, roll, and telescope length of the boom 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 of the receiver and a linear model of the boom;

create a bounding box that encompasses at least a boom tip and a boom pivot;

compute a set of Euclidian radial distances between each of the mapped points and each respective point on the boom located within the bounding box;

determine a minimum Euclidian radial distance in the set of Euclidian distances; and

execute a flight control operation of the boom during the A3R mission in response to the minimum Euclidian radial distance being less than a threshold minimum distance.

18 . The tanker of claim 17 , wherein the ECU is programmed to determine a closure rate of the boom to the receiver, and to selectively adjust the threshold minimum distance in real-time based on the closure rate.

19 . The tanker of claim 17 , wherein the ECU is programmed to execute the flight control operation of the boom by transmitting flight control signals to one or more flight control surfaces on the boom, and to thereby increase the minimum Euclidian radial distance until the minimum Euclidian distance exceeds the threshold minimum distance.

20 . The tanker of claim 17 , wherein a current position of the boom is determined in real-time via the sensor data.