Aircraft shell vibration visual measurement device and method

Abstract

The present invention belongs to the field of non-contact measurement of aircraft status. Conventional vibration sensors cannot realize the overall measurement of the aircraft shell, and ordinary visual cameras cannot overcome the influence of jitter when measuring the vibration of the aircraft shell. The present invention provides an aircraft shell vibration visual measurement device and method, which collects three-axis vibration information of the aircraft body and the visual camera and the aircraft shell image information, calculates the three-axis vibration differential displacement of the aircraft body and the visual camera, calculates the two-dimensional offset of the aircraft shell image information collected by the visual camera based on the obtained three-axis vibration differential displacement, re-translates and calibrates the aircraft shell image information based on the offset, and calculates the aircraft shell vibration information based on the change of specific pixel position in the calibrated aircraft shell image information. The present invention uses a dual vibration sensor mode to construct a vibration differential model to solve the problem of aircraft shell vibration measurement based on a visual camera under non-same frequency resonance conditions.

Description

Technical Field

[0001] The present invention provides an aircraft shell vibration visual measurement device and method, belonging to the field of non-contact measurement of aircraft status. Background Art

[0002] During the ascent of an aircraft, the outer shell of the aircraft will vibrate (commonly known as "shell breathing") due to the influence of atmospheric turbulence, engine vibration, air pressure, etc. Accurate measurement of the vibration of the aircraft shell is of great significance to the shell thickness design, material selection, material distribution design, and aircraft operation safety.

[0003] Conventional vibration measurement methods primarily rely on contact measurement, using fixed vibration sensors to detect vibration at fixed points. However, due to the inherent characteristics of aircraft, such as large hull surface areas, uncertain vibration points, and complex internal wiring, it is difficult to achieve full hull vibration measurement using vibration sensors. Image-based aircraft vibration measurement is a current research hotspot, offering advantages such as a wide measurement range, high accuracy, non-contact operation, and the ability to perform simultaneous multi-point measurements. However, due to the significant vibration during ascent, the image capture camera typically uses a damped flexible connection between the camera and the aircraft body to protect the image capture. This places the aircraft body and camera in a non-co-resonant state. When using conventional image cameras for aircraft hull vibration measurement, they are unable to overcome the effects of aircraft and camera shake, resulting in low detection stability and accuracy. While action cameras utilize optical and electronic image stabilization (ESI) technologies, their use on aircraft can mitigate the image blur caused by camera shake to a certain extent, but they cannot effectively address the effects of aircraft shake (such as POGO shake) on hull vibration. Therefore, in terms of aircraft status measurement, there is an urgent need for a technical method that can use damping flexible connections to protect the visual camera and realize visual measurement of aircraft shell vibration under non-co-resonant frequency states. Summary of the Invention

[0004] In view of the shortcomings of the existing technology, the purpose of the present invention is to provide a method for visual measurement of aircraft shell vibration, which can effectively deal with the vibration measurement of aircraft shell under non-co-frequency resonance conditions.

[0005] To achieve the above purpose, this method adopts the following technical solutions:

[0006] A device for visually measuring the vibration of an aircraft shell is installed on an aircraft body and includes a vibration detection component and a connecting assembly for connecting the vibration detection component and the aircraft body, wherein:

[0007] The vibration detection component includes a visual camera, a first vibration sensor for measuring the three-axis vibration information of the visual camera, and a second vibration sensor for measuring the three-axis vibration information of the aircraft body. The visual camera is fixedly connected to the side of the aircraft body through a connecting component, the first vibration sensor is fixed to the outer wall of the visual camera, and the second vibration sensor is fixedly installed inside the aircraft body.

[0008] Furthermore, the connecting assembly includes a first connecting rod connected to the aircraft body and a second connecting rod connected to the visual camera. The first connecting rod and the second connecting rod are fixedly connected. The angle α between the first connecting rod and the aircraft body ranges from 10° to 60°, the angle β between the first connecting rod and the second connecting rod ranges from 120° to 170°, and α+β<180°.

[0009] A method for visually measuring aircraft shell vibration is provided. The method uses the aforementioned aircraft shell visual vibration measurement device to perform measurements. A vibration differential model is constructed using dual vibration sensors to obtain the three-axis vibration differential displacement of the aircraft body and a visual camera. The two-dimensional offset of the aircraft shell image information collected by the visual camera is calculated. The aircraft shell image information is recalibrated based on the offset, and finally a visual measurement result of the aircraft shell vibration is obtained by calculation. The method includes the following steps:

[0010] S1: using a first vibration sensor and a second vibration sensor to respectively collect three-axis vibration information of the aircraft body and three-axis vibration information of the visual camera, while the visual camera simultaneously collects image information of the shell of the aircraft body;

[0011] S2: Calculate the three-axis vibration differential displacement of the aircraft body and the three-axis vibration information of the visual camera;

[0012] S3: Calculate the two-dimensional offset of the aircraft shell image information collected by the visual camera based on the three-axis vibration differential displacement obtained in step S2, and recalibrate the aircraft shell image information based on the offset;

[0013] S4: Calculate the vibration information of the aircraft shell according to the position change of specific pixels in the calibrated aircraft shell image information obtained in step S3.

[0014] Furthermore, the Y-axis and Z-axis of the first vibration sensor that collects three-axis vibration information of the visual camera are consistent with the edge direction of the rectangular plane of the visual camera's photosensitive CCD; the Z-axis of the second vibration sensor that collects three-axis vibration information of the aircraft body is consistent with the ascent direction of the aircraft, and the Y-axis is consistent with the Y-axis direction of the first vibration sensor.

[0015] Furthermore, the first vibration sensor and the second vibration sensor have the same parameters; the three-axis vibration information is a three-axis vibration displacement measurement value.

[0016] Furthermore, in step S2, the specific steps for calculating the vibration differential displacement are as follows:

[0017] S2.1. Calculate the three-axis vibration measurement values ​​of the second vibration sensor based on the installation angle of the visual camera so that the three-axis vibration measurement values ​​of the first vibration sensor and the second vibration sensor are in the same coordinate system, namely, the three-dimensional coordinate system of the visual camera;

[0018] S2.2. Perform differential operations on the three-axis vibration displacement measurement values ​​of the first vibration sensor and the second vibration sensor respectively to obtain the three-axis vibration differential displacement of the aircraft body and the visual camera.

[0019] Furthermore, in step S3, the vibration differential displacement values ​​of the Y-axis and Z-axis of the three-dimensional coordinate system of the visual camera are used as the two-dimensional offset of the aircraft shell image information to perform translation calibration on the collected aircraft shell image.

[0020] Furthermore, the pixel size of the visual camera is the physical size of a single pixel on the visual camera's photosensitive CCD chip array. According to the two-dimensional offset of the aircraft shell image information, the number of pixels to be translated is calculated to calibrate the image.

[0021] Furthermore, in step S4, a reference target point is set on the aircraft shell, and the pixel position changes of the reference calibration point in two adjacent frames of the aircraft shell image are counted. Combined with the size calibration information of the camera, the displacement vibration value of the reference target point is calculated to obtain the final aircraft shell vibration information.

[0022] Furthermore, the visual camera size calibration information is collected by collecting standard chessboard calibration plate information to calculate the actual size represented by a single pixel at a specific distance.

[0023] In summary, the present invention has the following beneficial effects compared with the prior art:

[0024] 1. The present invention uses a vision-based method for measuring aircraft shell vibration. Non-contact measurement can effectively reduce the number of internal wiring connections in the aircraft, with a wide detection range and high detection accuracy.

[0025] 2. The present invention uses a dual vibration sensor mode to construct a vibration differential model to solve the problem of visual vibration measurement under non-same frequency resonance conditions;

[0026] 3. This invention is a methodological exploration study and can be adaptively extended to other industrial applications of vibration state detection. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] The present invention will be further described below with reference to the accompanying drawings:

[0028] Figure 1 This is a schematic diagram of the structure of the aircraft of the present invention;

[0029] Figure 2 Schematic diagram of the aircraft structure coordinate system of the present invention;

[0030] Figure 3 Schematic diagram of the flow chart of the measurement method of the present invention.

[0031] In the figure, (1) - second vibration sensor, (2) - aircraft body, (3) - visual camera, (4) - first vibration sensor, (5) - first connecting rod, (6) visual camera photosensitive CCD rectangular plane, (7) - second connecting rod.

[0032] (X, Y, Z) is the coordinate system of the second vibration sensor and also the coordinate system of the aircraft body.

[0033] (X', Y', Z') is the coordinate system of the first vibration sensor.

[0034] (H, V) is the two-dimensional coordinate system of the visual camera. DETAILED DESCRIPTION

[0035] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present invention more clearly understood, the present invention is further described in detail with reference to the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention. The technical solutions of the present invention will be described in detail below with reference to the embodiments, but the scope of protection is not limited thereto.

[0036] like Figure 1 As shown, the present invention discloses an aircraft shell vibration visual measurement device, which is installed on the aircraft body 2 and includes a vibration detection component and a connecting assembly for connecting the vibration detection component and the aircraft body 2, wherein:

[0037] The vibration detection component includes a visual camera 3, a first vibration sensor 4 for measuring the three-axis vibration information of the visual camera 3, and a second vibration sensor 1 for measuring the three-axis vibration information of the aircraft body 2. The visual camera 3 is fixedly connected to the side of the aircraft body 2 through a connecting component. The visual camera 3 has no contact with the aircraft body structure. The first vibration sensor 4 is installed on the outer wall of the visual camera 3, and the second vibration sensor 1 is fixedly installed inside the aircraft body 2. The installation position of the second vibration sensor 1 can be located at any fixed position inside the aircraft body 2 that is not the inner wall of the shell; the parameters of the first vibration sensor 4 and the second vibration sensor 1 are the same; the three-axis vibration information is the three-axis vibration displacement measurement value.

[0038] The connecting assembly includes a first connecting rod 5 connected to the aircraft body 2 and a second connecting rod 7 connected to the visual camera 3. The first connecting rod 5 and the second connecting rod 7 are fixedly connected. The angle α between the first connecting rod 5 and the aircraft body 2 ranges from 10° to 60°, and the angle β between the first connecting rod 5 and the second connecting rod 7 ranges from 120° to 170°, and α+β<180°.

[0039] The present invention also discloses a method for visually measuring vibration of an aircraft shell. The method performs measurement based on the above-mentioned visual measurement device for aircraft shell vibration. By using a dual vibration sensor to construct a vibration differential model, a three-axis vibration differential displacement of the aircraft body 2 and the visual camera 3 is obtained. The two-dimensional offset of the aircraft shell image information collected by the visual camera is calculated. The aircraft shell image information is recalibrated according to the offset. Finally, a visual measurement result of the aircraft shell vibration is calculated. The method includes the following steps:

[0040] S1: Use the first vibration sensor 4 and the second vibration sensor 1 to respectively collect the three-axis vibration information of the aircraft body 2 and the three-axis vibration information of the visual camera 3, and the visual camera 3 simultaneously collects the shell image information of the aircraft body 2.

[0041] In step S1, the Y-axis and Z-axis of the first vibration sensor 4 that collects the three-axis vibration information of the visual camera are consistent with the edge direction of the rectangular plane of the photosensitive CCD of the visual camera 3; the Z-axis of the second vibration sensor 1 that collects the three-axis vibration information of the aircraft body is consistent with the rising direction of the aircraft, and the Y-axis is consistent with the Y-axis direction of the first vibration sensor.

[0042] S2: Calculate the three-axis vibration differential displacement of the three-axis vibration information of the aircraft body 2 and the three-axis vibration information of the visual camera 3.

[0043] In step S2, the specific steps for calculating the vibration differential displacement are as follows:

[0044] S2.1. Calculate the three-axis vibration measurement values ​​of the second vibration sensor 1 according to the installation angle of the visual camera 3 so that the three-axis vibration measurement values ​​of the first vibration sensor 4 and the second vibration sensor 1 are in the same coordinate system, namely, the three-dimensional coordinate system of the visual camera.

[0045] S2.2. Perform differential operations on the three-axis vibration displacement measurement values ​​of the first vibration sensor 4 and the second vibration sensor 1 respectively to obtain the three-axis vibration differential displacement of the aircraft body 2 and the visual camera 3.

[0046] S3: Calculate the two-dimensional offset of the aircraft shell image information collected by the visual camera 3 based on the three-axis vibration differential displacement obtained in step S2, and recalibrate the aircraft shell image information based on the offset.

[0047] In step S3, the captured aircraft shell image is calibrated using the differential vibration displacement values ​​along the Y and Z axes of the visual camera's three-dimensional coordinate system as the two-dimensional offset of the aircraft shell image information. The pixel size of the visual camera 3 is the physical size of a single pixel on the camera's photosensitive CCD chip array. Based on the two-dimensional offset of the aircraft shell image information, the number of pixels required for translation is calculated to calibrate the image.

[0048] S4: Calculate the vibration information of the aircraft shell according to the position change of specific pixels in the calibrated aircraft shell image information obtained in step S3.

[0049] In step S4, a reference target point is set on the aircraft shell. The pixel position change of the reference target point between two adjacent frames of the aircraft shell image is counted. Combined with the camera's size calibration information, the displacement vibration value of the reference target point is calculated to obtain the final aircraft shell vibration information. The size calibration information of the visual camera is obtained by collecting information from a standard chessboard calibration plate and calculating the actual size represented by a single pixel at a specific distance.

[0050] like Figure 2 As shown, a two-dimensional coordinate system (H, V) of the visual camera is established in the edge direction of the rectangular plane 6 of the visual camera's photosensitive CCD. The Y'-axis and Z'-axis of the coordinate system of the first vibration sensor 4 are consistent with the V-axis and H-axis directions of the two-dimensional coordinate system of the visual camera. The Y-axis of the coordinate system of the second vibration sensor 1 is consistent with the Y'-axis direction of the coordinate system of the first vibration sensor. The Z-axis of the coordinate system of the second vibration sensor 1 is consistent with the ascending direction of the aircraft.

[0051] like Figure 3 In the embodiment shown, the specific steps are as follows:

[0052] The second vibration sensor 1 is used to collect the three-axis vibration displacement information (a, b, c) of the aircraft body 2, the first vibration sensor 4 is used to collect the three-axis vibration displacement information (a', b', c') of the visual camera 3, and the visual camera 3 is used to simultaneously collect the shell image information of the aircraft body 2.

[0053] Calculate the three-axis vibration differential displacement of the three-axis vibration information (a, b, c) of the aircraft body 2 and the three-axis vibration information (a', b', c') of the visual camera 3, specifically:

[0054] According to the installation angle of the visual camera 3, the three-axis vibration measurement value of the second vibration sensor 1 is adjusted and calculated so that the three-axis vibration measurement values ​​of the first vibration sensor 4 and the second vibration sensor 1 are in the same coordinate system (called the visual camera three-dimensional coordinate system). The adjusted three-axis vibration measurement value of the second vibration sensor 1 is

[0055] The three-axis vibration measurement values ​​(a', b', c') of the first vibration sensor 4 and the adjusted three-axis vibration measurement values ​​of the second vibration sensor 1 are calculated. Differential operations are performed separately to obtain the three-axis vibration differential displacement (m, n, l) of the aircraft body and the visual camera.

[0056]

[0057] Based on the obtained three-axis vibration differential displacement (m, n, l), the two-dimensional offset of the aircraft shell image information collected by the visual camera is calculated, and the aircraft shell image information is recalibrated based on the offset. Specifically:

[0058] The size of the photosensitive CCD pixel of the visual camera (3) is p×q. The vibration differential displacement values ​​(n, l) of the Y-axis and Z-axis of the three-dimensional coordinate system of the visual camera are used as the total two-dimensional offset value of the aircraft shell image information, and the image offset (i.e., the number of offset pixels) is calculated as follows:

[0059]

[0060] Among them, int() is the rounding function.

[0061] The collected image of the aircraft shell is subjected to a translation calibration operation according to the above-mentioned number of offset pixels.

[0062] The aircraft shell vibration information is calculated based on the position change of specific pixels in the calibrated aircraft shell image information. Specifically:

[0063] Use a visual camera to capture a standard chessboard calibration plate and measure and calculate the actual size represented by a single pixel at a specific distance. The resolution of the visual camera is s×t, the number of chessboards captured is u×v, and the side length of a single square on the chessboard calibration plate is r. Then the actual size represented by a single pixel of the visual camera is

[0064] An arbitrary reference target point is set on the aircraft shell, and the pixel position change j of the reference calibration point in two adjacent frames of the aircraft shell image is counted.

[0065] Combined with the camera's size calibration information, the displacement vibration value of the reference target point is calculated to obtain the final aircraft shell vibration displacement information:

[0066] Finally, it should be noted that the above-described embodiment represents only one embodiment of the present invention. While the description is relatively specific and detailed, it should not be construed as limiting the scope of the present invention. It should be noted that a person skilled in the art would be able to make various modifications and improvements without departing from the spirit of the present invention, and these modifications and improvements fall within the scope of protection of the present invention. Therefore, the scope of protection of the present invention shall be determined by the appended claims.

Claims

1. A device for visually measuring the vibration of an aircraft shell, characterized in that: The aircraft shell vibration visual measurement device is installed on the aircraft body (2), and comprises a vibration detection component and a connection assembly for connecting the vibration detection component and the aircraft body (2), wherein: The vibration detection component comprises a visual camera (3), a first vibration sensor (4) for measuring three-axis vibration information of the visual camera (3), and a second vibration sensor (1) for measuring three-axis vibration information of the aircraft body (2); the visual camera (3) is fixedly connected to the side of the aircraft body (2) through a connecting component, the first vibration sensor (4) is fixed to the outer wall of the visual camera (3), and the second vibration sensor (1) is fixedly installed inside the aircraft body (2).

2. The aircraft shell vibration visual measurement device according to claim 1, characterized in that: The connecting assembly comprises a first connecting rod (5) connected to the aircraft body (2) and a second connecting rod (7) connected to the visual camera (3); the first connecting rod (5) and the second connecting rod (7) are fixedly connected; an included angle α between the first connecting rod (5) and the aircraft body (2) ranges from 10° to 60°; an included angle β between the first connecting rod (5) and the second connecting rod (7) ranges from 120° to 170°, and α+β<180°.

3. A method for visually measuring the vibration of an aircraft shell, based on the aircraft shell visually measuring device according to claim 1 or 2, characterized in that: By using dual vibration sensors to construct a vibration differential model, the three-axis vibration differential displacement of the aircraft body (2) and the visual camera (3) is obtained, the two-dimensional offset of the aircraft shell image information collected by the visual camera is calculated, the aircraft shell image information is recalibrated according to the offset, and finally the visual measurement result of the aircraft shell vibration is calculated, including the following steps: S1: using a first vibration sensor (4) and a second vibration sensor (1) to respectively collect three-axis vibration information of a visual camera (3) and three-axis vibration information of an aircraft body (2), and the visual camera (3) simultaneously collects shell image information of the aircraft body (2); S2: Calculate the three-axis vibration differential displacement of the aircraft body (2) and the three-axis vibration information of the visual camera (3); S3: Calculate the two-dimensional offset of the aircraft shell image information collected by the visual camera (3) based on the three-axis vibration differential displacement obtained in step S2, and recalibrate the aircraft shell image information based on the offset; S4: Calculate the vibration information of the aircraft shell according to the position change of specific pixels in the calibrated aircraft shell image information obtained in step S3.

4. The method for visually measuring the vibration of an aircraft shell according to claim 3, wherein: The Y-axis and Z-axis of the first vibration sensor (4) for collecting three-axis vibration information of the visual camera (3) are consistent with the edge direction of the rectangular plane of the light-sensitive CCD of the visual camera (3); the Z-axis of the second vibration sensor (1) for collecting three-axis vibration information of the aircraft body (2) is consistent with the ascending direction of the aircraft, and the Y-axis is consistent with the Y-axis direction of the first vibration sensor (4).

5. The method for visually measuring the vibration of an aircraft shell according to claim 3, wherein: The first vibration sensor (4) and the second vibration sensor (1) have the same parameters; the three-axis vibration information is a three-axis vibration displacement measurement value.

6. The method for visually measuring the vibration of an aircraft shell according to claim 3, characterized in that: In step S2, the specific steps for calculating the vibration differential displacement are as follows: S2.

1. Calculate the three-axis vibration measurement value of the second vibration sensor (1) according to the installation angle of the visual camera (3), so that the three-axis vibration measurement values ​​of the first vibration sensor (4) and the second vibration sensor (1) are in the same coordinate system, that is, the three-dimensional coordinate system of the visual camera; S2.

2. Perform differential operations on the three-axis vibration displacement measurement values ​​of the first vibration sensor (4) and the second vibration sensor (1) to obtain the three-axis vibration differential displacement of the aircraft body (2) and the visual camera (3).

7. The method for visually measuring the vibration of an aircraft shell according to claim 3, wherein: In step S3, the vibration differential displacement values ​​of the Y-axis and Z-axis of the three-dimensional coordinate system of the visual camera are used as the two-dimensional offset of the aircraft shell image information to perform translation calibration on the collected aircraft shell image.

8. The method for visually measuring the vibration of an aircraft shell according to claim 7, characterized in that: The pixel size of the visual camera (3) is the physical size of a single pixel on the visual camera's photosensitive CCD chip array. The number of pixels to be translated is calculated based on the two-dimensional offset of the aircraft shell image information to calibrate the image.

9. The method for visually measuring the vibration of an aircraft shell according to claim 3, wherein: In step S4, a reference target point is set on the aircraft shell, and the pixel position changes of the reference calibration point in two adjacent frames of the aircraft shell image are counted. Combined with the size calibration information of the camera, the displacement vibration value of the reference target point is calculated to obtain the final aircraft shell vibration information.

10. The method for visually measuring the vibration of an aircraft shell according to claim 9, characterized in that: The visual camera size calibration information is obtained by collecting standard chessboard calibration plate information to calculate the actual size represented by a single pixel at a specific distance.

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