A method for measuring relative positions of aircraft in an air formation

Abstract

The present application provides a method for measuring the relative position of aircraft in an aerial formation, which belongs to the field of photoelectric measurement technology for flight tests. The present invention first calculates the initial value of the relative spatial position of the tanker and the receiving aircraft; then corrects the initial value of the relative spatial position of the tanker and the receiving aircraft according to the camera installation attitude angle and the receiving aircraft platform attitude angle to obtain the relative spatial position of the two aircraft. Compared with related technologies, this method can meet the requirements of the safety distance parameters of the two aircraft in the aerial refueling test mission. The method has a simple calculation model derivation, flexible camera installation, and is easy to implement. At the same time, it can alleviate the current situation of tight flight test equipment resources to a certain extent and save costs.

Description

Technical Field

[0001] The present application belongs to the field of photoelectric measurement technology for flight tests, and in particular, relates to a method for measuring the relative positions of aircraft in an air formation. Background Art

[0002] Soft aerial refueling is an ultra-dense flight between two aircraft, during which mutual interference of aerodynamic forces is inevitable. During the flight of the tanker, the surrounding air is strongly disturbed, and the disturbed gas forms a complex flow field such as wing tail vortex, engine tail jet and boundary layer turbulence behind the wing of the tanker, namely the wake field of the tanker. When flying in formation during close-range aerial refueling, when the receiving aircraft is at different positions of the tanker's tail vortex, the tanker's wake field affects the aerodynamics, mass, center of gravity and maneuverability of the receiving aircraft dynamically, seriously affecting the flight safety of the receiving aircraft. Therefore, it is necessary to accurately calculate the relative spatial position of an air formation aircraft to ensure that the receiving aircraft is within a safe distance range and to ensure the safety of the air formation flight of the tanker and the receiving aircraft.

[0003] At present, the sensors that measure relative position information mainly include inertial navigation system and differential GPS. Among them, the error of inertial navigation system accumulates over time, and the accuracy cannot meet the requirements; the accuracy of differential GPS can meet the requirements of aerial refueling, but the GPS signal is easily blocked by the tanker during the aerial refueling docking stage. Once the signal is lost, the navigation accuracy will drop significantly. Summary of the invention

[0004] In order to solve the problem that the accuracy of the inertial navigation system cannot meet the requirements when measuring relative position information in the related art, the GPS signal is easily blocked by the tanker during the aerial refueling docking phase, and the navigation accuracy decreases, the present invention provides a relative position measurement method for aircraft in an aerial formation, and the technical solution is as follows:

[0005] In a first aspect, a method for measuring relative positions of aircraft in an air formation is provided, the method comprising:

[0006] Calculate the initial value of the relative spatial position between the tanker and the receiver;

[0007] According to the camera installation attitude angle and the attitude angle of the receiving aircraft platform, the initial value of the relative spatial position of the tanker and the receiving aircraft is corrected to obtain the relative spatial position of the two aircraft.

[0008] Among them, the calculation of the initial value of the relative spatial position between the tanker and the receiver includes:

[0009] The images transmitted remotely from the monitoring camera installed in the cockpit of the receiving aircraft to the ground monitoring hall are used as the data source. When the refueling drogue of the tanker and the refueling head of the receiving aircraft are docked, the horizontal projection of the wingspan of the tanker and the longitudinal distance from the measuring point to the camera installation point are used as additional reference information. The initial value of the relative spatial position of the tanker and the receiving aircraft is calculated based on the principle of central projection of photogrammetry.

[0010] Among them, the camera installation attitude angle and the receiving aircraft platform attitude angle are obtained based on the horizontal reference plane.

[0011] Among them, the camera installation attitude angle and the receiving aircraft platform attitude angle include: roll angle, pitch angle and yaw angle.

[0012] Furthermore, after calculating the initial value of the relative spatial position between the fuel dispenser and the receiving aircraft, the method further includes:

[0013] Obtain the attitude angle of the receiving aircraft platform from the collected data of the inertial navigation on the receiving aircraft;

[0014] The camera installation attitude angle is calculated using the principle of spatial resection in photogrammetry;

[0015] Calculate the composite angle of the receiving aircraft and camera attitude.

[0016] Among them, the initial value of the relative spatial position of the tanker and the receiver is corrected according to the camera installation attitude angle and the receiver platform attitude angle to obtain the relative spatial position of the two aircraft, including:

[0017] According to the calculated composite angle of the receiving aircraft and the camera attitude, the coordinates of the initial values ​​of the relative spatial positions of the two aircraft are rotated, and the relative spatial positions of the two aircraft based on the horizontal reference plane are calculated.

[0018] Specifically, when correcting the initial value of the relative spatial position between the tanker and the receiver, it includes:

[0019] Use the rolling angle to correct the initial value of the relative spatial position of the two aircraft to obtain the first initial value;

[0020] Correct the first initial value with the pitch angle to obtain the second initial value;

[0021] Correct the second initial value with the yaw angle to obtain the third initial value;

[0022] The third initial value is used as the relative spatial position of the two machines.

[0023] Furthermore, the method further includes: outputting a corrected result.

[0024] Among them, the resolution of the surveillance camera is 1600*1200 pixels.

[0025] In a second aspect, a device for measuring the relative positions of aircraft in an air formation is provided, comprising a processor and a memory, wherein the processor is configured to execute instructions stored in the memory, and the processor implements any method for measuring the relative spatial positions of aircraft in an air formation as described in the first aspect by executing the instructions.

[0026] The method for measuring the relative position of aircraft in an aerial formation provided by the present invention calculates the initial value of the relative spatial position of the tanker and the receiving aircraft; and corrects the initial value of the relative spatial position of the tanker and the receiving aircraft according to the camera installation attitude angle and the receiving aircraft platform attitude angle to obtain the relative spatial position of the two aircraft. Compared with related technologies, this method can meet the requirements of the safety distance parameters of the two aircraft in the aerial refueling test flight mission. The method has a simple calculation model derivation, flexible camera installation, and is easy to implement. At the same time, it can alleviate the current situation of tight resources of flight test equipment to a certain extent and save costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 A schematic diagram of a flow chart of a method for measuring the relative positions of aircraft in an air formation provided in an embodiment of the present application;

[0028] Figure 2 A schematic diagram of roll angle correction provided in an embodiment of the present application;

[0029] Figure 3 A schematic diagram of pitch angle correction provided in an embodiment of the present application;

[0030] Figure 4 A schematic diagram of yaw angle correction provided in an embodiment of the present application;

[0031] Figure 5 A schematic diagram of a measurement interface provided in an embodiment of the present application;

[0032] Figure 6 A top view of the relative spatial positions of two machines provided in an embodiment of the present application;

[0033] Figure 7 A side view of the relative spatial position of two machines provided in an embodiment of the present application;

[0034] Figure 8 A rear view of the relative spatial positions of two machines provided in an embodiment of the present application;

[0035] Fig. 9 A three-dimensional schematic diagram of the relative spatial positions of two machines provided in an embodiment of the present application. DETAILED DESCRIPTION

[0036] The present application is further described in detail below through specific implementation methods and drawings.

[0037] Visual images have the advantages of rich information and complete autonomy. The visual measurement system is divided into monocular vision measurement system and binocular vision measurement system according to the number of image sensors. Among them, the binocular vision measurement system is based on the principle of parallax. It finds the same-name points in the image set transmitted from multiple image sensors, obtains the position information of the same-name points, and then obtains the position information of the object to be measured. The monocular vision measurement system requires additional information about the object to be measured in order to obtain the position of the object from the image. However, the binocular vision measurement system has many disadvantages compared with the monocular vision measurement system. The field of view of the binocular vision measurement system is the common field of view of the image sensor, with a narrow range and limited measurement distance. Complex calibration is required between image sensors, which is inconvenient in practical application. The monocular vision measurement system has a larger field of view, simple calibration, and is easy to apply.

[0038] Therefore, the present invention provides a method for measuring the relative spatial position of aircraft in an aerial formation based on a single camera. The present invention focuses on how to use a single high-definition camera installed in the cockpit of the receiving aircraft to design a method for measuring the relative spatial position of aircraft in an aerial formation, thereby accurately measuring the distance between the two aircraft during close-range aerial refueling formation, and providing reliable data basis for the safety of aerial refueling test flights.

[0039] The embodiment of the present invention provides a method for measuring the relative positions of aircraft in an air formation, such as Figure 1 As shown, the method includes:

[0040] Step 1: Use the image transmitted from the monitoring camera installed in the cockpit of the receiving aircraft to the ground monitoring hall as the data source. When the refueling drogue of the tanker and the refueling head of the receiving aircraft are docked, use the horizontal projection of the wingspan of the tanker and the longitudinal distance from the measuring point to the camera installation point as additional reference information, and calculate the initial value of the relative spatial position of the tanker and the receiving aircraft based on the principle of photogrammetry center projection.

[0041] In order to improve the accuracy of the results, the resolution of the surveillance camera can be 1600*1200 pixels.

[0042] Step 2: Correct the initial value of the relative spatial position between the tanker and the receiver according to the camera installation attitude angle and the receiver platform attitude angle. The camera installation attitude angle and the receiver platform attitude angle are obtained based on the horizontal reference plane.

[0043] The camera installation attitude angle and the receiving aircraft platform attitude angle may include a roll angle, a pitch angle and a yaw angle.

[0044] Step 3: Use the corrected result of step 2 as the relative spatial position of the two machines.

[0045] Specifically, another embodiment of the present invention provides a method for measuring the relative positions of aircraft in an air formation, see Figure 1 , the method comprises the following steps:

[0046] Step 10: Define parameters and coordinate system.

[0047] Defining parameters and coordinate systems includes the following:

[0048] (1) Determine the measuring point: the midpoint of the line connecting the rear edges of the tanker wingtips.

[0049] (2) Define coordinates: The origin is the camera mounting point in the cockpit of the receiving aircraft, the longitudinal axis of the aircraft is the X-axis, the Y-axis is perpendicular to the X-axis and points to the left wing, and the Z-axis is perpendicular to the XY plane and points upward (right-hand coordinate system).

[0050] (3) Define the inertial navigation coordinate system: Looking from the back to the front along the heading direction, the right wing moves downward and the aircraft roll angle (hg fj ) is positive, the nose of the aircraft rises upwards, the pitch angle (fy fj ) is positive, the yaw angle is the angle between the aircraft heading and the true north direction, and clockwise is positive.

[0051] (4) Establish the camera coordinate system: With the photography center as the origin, the X-axis is horizontal and points to the right, the Y-axis is perpendicular to the X-axis and points upward, and the Z-axis is perpendicular to the XY plane and points to the tail of the aircraft, forming a right-handed coordinate system.

[0052] (5) Output result: the three-dimensional coordinates of the point to be measured relative to the coordinate origin.

[0053] Step 20: Calculate the initial value of the relative spatial position of the two machines.

[0054] The initial value of the relative spatial position of the tanker and the receiver is calculated based on the principle of central projection of photogrammetry. The object-image ratio is calculated using the actual distance between the wingtips of the tanker (the wingspan deviation caused by the deformation of the wing in the air is very small and can be ignored) and the pixels occupied by the wingtips of the two aircraft in the image when they approach, which is used as the object-image ratio benchmark for the relative spatial position of the two aircraft.

[0055] Assume that the wing tip line (wing span length) of the known reference data is w0, and the number of pixels in the image is w x0 , the length of the projection of the midpoint of the wing tip line on the horizontal plane to the camera installation position when the tanker drogue and the receiving aircraft refueling head are in docking state is d0. Then:

[0056] Where f is the focal length of the camera lens;

[0057] The relationship between the movement position of the measuring point at any time can be expressed as:

[0058]

[0059]

[0060]

[0061] The three-dimensional coordinates (X, Y, Z) of the measuring point relative to the origin of the coordinate system are obtained, that is, the initial values ​​of the relative spatial positions of the two machines are as follows:

[0062]

[0063]

[0064]

[0065] Among them, (w xi ,x i ,y i ) is the image interpretation coordinate of the measurement point at any time. w0 is obtained by measuring the wingspan length of the tanker aircraft with a total station; w x0 It is obtained through the benchmark reference image; d0 is the projection length of the distance from the measuring point to the camera installation position on the horizontal plane when the tanker drogue and the receiving head of the receiving aircraft are in the docking state, which is composed of the horizontal distances from the camera to the receiving head, from the refueling pod outlet to the refueling head, and from the measuring point to the refueling pod outlet.

[0066] Step 30: Calculate the camera installation attitude angle and the receiving aircraft platform attitude angle.

[0067] (1) Calculate the attitude angle of the receiving aircraft platform

[0068] The attitude angle of the receiving aircraft platform can be obtained from the data collected by the inertial navigation on the aircraft. At the same time, the attitude angle of the receiving aircraft platform is obtained based on the horizontal reference plane. The attitude angle of the receiving aircraft platform based on the horizontal reference plane can refer to the relevant technology, which will not be repeated here.

[0069] (2) Calculate the camera installation attitude angle

[0070] Since the camera has an initial installation angle, for example, the aircraft in the image before the receiving aircraft takes off can be used as a reference. After on-site coordinate measurement and image interpretation by the total station, the initial roll angle, pitch angle and yaw angle of the camera (hg o xj ,fy 0 xj ,ph 0 xj ). The initial pitch angle, roll angle and yaw angle of the camera are obtained based on the horizontal reference plane. The initial pitch angle, roll angle and yaw angle of the camera based on the horizontal reference plane can refer to the relevant technology and will not be repeated here.

[0071] In addition to using the aircraft in the picture before the receiving aircraft takes off as a reference, multiple feature points can also be manually arranged in the camera field of view as references.

[0072] Calculate the camera roll angle hg based on the calibration image 0 xj , camera pitch angle fy 0 xj , camera yaw angle ph 0 xj In the calibration image, the inertial navigation on the aircraft measures the aircraft attitude at this moment as hg 0 fj ,fy 0 fj Therefore, the camera calibration result is corrected to obtain the initial installation angle of the camera, hg xj =hg 0 xj +hg 0 fj ,fy xj =fy 0 xj -y 0 fj .

[0073] (3) Calculate the composite angle of the receiving aircraft and camera attitude

[0074] The camera is fixedly installed on the receiving aircraft and changes in attitude with the aircraft. The change angle of the camera attitude is obtained based on the inertial navigation data of the aircraft at the corresponding moment.

[0075] The synthetic roll angle hg, synthetic pitch angle fy, and synthetic yaw angle ph are:

[0076] hg=hg xj -hg fj (The camera and the aircraft are in opposite directions),

[0077] fy=fy xj +fy fj (the camera and the aircraft are in the same direction),

[0078] ph=ph 0 xj (the camera and the aircraft are in the same direction),

[0079] Step 40: Calculate the relative spatial positions of the two machines.

[0080] The initial value of the relative spatial position of the two aircrafts calculated in step 20 is subjected to attitude angle correction to obtain an accurate value of the relative spatial position of the two aircrafts.

[0081] The composite angle of the aircraft and camera attitudes calculated in step 30 is introduced, the initial value of the relative spatial position of the two aircraft calculated in step 20 is rotated, the camera attitude is corrected to the horizontal reference plane, and the relative spatial position of the two aircraft based on the horizontal reference plane is calculated.

[0082] The coordinate rotation order is: roll angle first, then pitch angle, and finally yaw angle.

[0083] Assuming the initial calculation result is (X, Y, Z), the coordinates after roll angle correction are (X′, Y′, Z′), the coordinates after pitch angle correction are (X″, Y″, Z″), and the coordinates after yaw angle correction are (X″′, Y″′, Z″′).

[0084] (1) Use the roll angle to correct the initial value of the relative spatial position of the two aircraft to obtain the first initial value

[0085] Since the coordinate system of the camera attitude calibration attitude is inconsistent with the direction of the calculation result coordinate system, in the calculation result coordinate system, it is equivalent to the YZ plane rotating clockwise around X by (-hg) angle. Therefore, it is necessary to rotate counterclockwise by (-hg) angle to correct the calculation result to the horizontal reference plane. Figure 2 As shown, the expression is:

[0086]

[0087] (2) Use the pitch angle to correct the first initial value and obtain the second initial value

[0088] In the calculation result coordinate system, it is equivalent to the X′Z′ plane rotating clockwise around Y′ by an angle of fy. Therefore, it is necessary to rotate counterclockwise by an angle of fy to correct the calculation result to the horizontal reference plane. Figure 3 As shown, the expression is:

[0089]

[0090] (3) Use the yaw angle to correct the second initial value and obtain the third initial value

[0091] Camera yaw angle ph xj Correction, in the XZ plane, clockwise is positive and counterclockwise is negative, such as Figure 4 As shown, the expression is:

[0092]

[0093] Therefore, the corrected result is:

[0094]

[0095] Step 50: Output the corrected result

[0096] According to the above steps, a calculation program is written to calculate and output the relative spatial positions of the aircraft in the air formation. For example, the calculation program interface can be as follows: Figure 5 shown. Figure 6 Schematic diagram of the relative spatial positions of the two machines.

[0097] The present invention also provides a device for measuring the relative positions of aircraft in an air formation, comprising a processor and a memory, wherein the processor is configured to execute instructions stored in the memory, and the processor implements the above-mentioned method for measuring the relative positions of aircraft in an air formation by executing the instructions.

[0098] The present invention uses a single high-definition camera to calculate the relative spatial position of aircraft in close-range aerial formation, achieving a measurement effect similar to that of dual-camera intersection, and can meet the requirements of the safety distance parameters between two aircraft in aerial refueling test missions. The method has a simple calculation model derivation, flexible camera installation, and is easy to implement. At the same time, it can alleviate the current situation of tight flight test equipment resources to a certain extent and save scientific research costs.

[0099] The above only expresses the implementation methods of the present application, and the description is relatively specific and detailed, but it cannot be understood as limiting the scope of the invention patent. It should be pointed out that for ordinary technicians in this field, several modifications and improvements can be made without departing from the concept of the present application, which all belong to the protection scope of the present application. In addition, the parts that are not detailed in the present invention are all conventional technologies.

Claims

1. A method for measuring the relative positions of aircraft in an air formation, characterized in that: The method comprises: Calculate the initial value of the relative spatial position between the tanker and the receiver; According to the camera installation attitude angle and the attitude angle of the receiving aircraft platform, the initial value of the relative spatial position between the tanker and the receiving aircraft is corrected to obtain the relative spatial position of the two aircraft; The camera installation attitude angle and the receiving aircraft platform attitude angle are obtained based on the horizontal reference plane; After calculating the initial value of the relative spatial position between the fuel dispenser and the fuel receiving machine, the method further includes: Obtain the attitude angle of the receiving aircraft platform from the collected data of the inertial navigation on the receiving aircraft; The camera installation attitude angle is calculated using the principle of spatial resection in photogrammetry; Calculate the composite angle of the receiving aircraft and camera attitude; According to the camera installation attitude angle and the attitude angle of the receiving aircraft platform, the initial value of the relative spatial position of the tanker and the receiving aircraft is corrected to obtain the relative spatial position of the two aircraft, including: According to the calculated composite angle of the receiving aircraft and the camera attitude, the coordinates of the initial values ​​of the relative spatial positions of the two aircraft are rotated, and the relative spatial positions of the two aircraft based on the horizontal reference plane are calculated.

2. The method according to claim 1, characterized in that Calculate the initial value of the relative spatial position between the tanker and the receiver, including: The images transmitted remotely from the monitoring camera installed in the cockpit of the receiving aircraft to the ground monitoring hall are used as the data source. When the refueling drogue of the tanker and the refueling head of the receiving aircraft are docked, the horizontal projection of the wingspan of the tanker and the longitudinal distance from the measuring point to the camera installation point are used as additional reference information. The initial value of the relative spatial position of the tanker and the receiving aircraft is calculated based on the principle of central projection of photogrammetry.

3. The method according to claim 1, characterized in that The camera installation attitude angle and the receiving aircraft platform attitude angle include: roll angle, pitch angle and yaw angle.

4. The method according to claim 1, characterized in that: When correcting the initial value of the relative spatial position between the tanker and the receiver, it includes: Use the rolling angle to correct the initial value of the relative spatial position of the two aircraft to obtain the first initial value; Correct the first initial value with the pitch angle to obtain the second initial value; Correct the second initial value with the yaw angle to obtain the third initial value; The third initial value is used as the relative spatial position of the two machines.

5. The method according to any one of claims 1 to 4, characterized in that: The method further includes: outputting the corrected result.

6. The method according to claim 1, characterized in that The resolution of the surveillance camera is 1600*1200 pixels.

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