Method for high-precision measurement of gap variation of aircraft split doors

Abstract

The application provides a kind of high-precision measurement method for the gap change of aircraft split doors, belongs to the technical field of aircraft detection, specifically includes constructing binocular stereo vision measurement error transfer model;Establish a three-dimensional coordinate system;Based on the binocular stereo vision measurement error transfer model, the measurement uncertainty at any point in the measurement field is predicted, and the parameters of the binocular stereo vision measurement system are adjusted according to the predicted measurement uncertainty;The first target point is placed on the left cabin door of the aircraft split door, and the second target point is placed on the right cabin door of the aircraft split door;The position change of the first target point and the second target point after the cabin door is loaded is tracked by measuring the binocular stereo vision measurement system, and the gap width change and the step change of the aircraft split door are calculated according to the three-dimensional coordinate change of the first target point and the second target point. Through the processing scheme of the application, non-contact, high-precision, high-resolution gap morphology quantitative characterization is realized.

Description

Technical Field

[0001] This application relates to the field of aircraft inspection, and in particular to a high-precision method for measuring the change in the gap between aircraft hatches. Background Technology

[0002] The gap width and step difference of aircraft hatches are key indicators of assembly quality and maintenance status. Their accuracy is directly related to the airtightness, structural integrity, and aerodynamic performance during flight. Therefore, high-precision and efficient measurement methods are required to detect them.

[0003] In traditional measurement methods, contact tools such as feeler gauges rely on manual operation, and the measurement accuracy is easily affected by human factors and it is difficult to meet the high precision requirements of sub-millimeter level. Although precision equipment such as coordinate measuring machines has high accuracy, the measurement efficiency is low, the equipment cost is high, and the adaptability to online measurement of large-size doors or complex working conditions is poor.

[0004] In recent years, binocular stereo vision technology has been increasingly applied in industrial measurement due to its advantages such as non-contact operation, high efficiency, and strong 3D information acquisition capabilities. However, existing binocular stereo vision-based measurement methods still face challenges in scenarios with extremely high requirements for measurement accuracy and system stability, such as aircraft doors. These challenges include difficulty in accurately controlling 3D reconstruction errors and insufficient robustness under complex working conditions, resulting in measurement results for door gaps and step differences that fail to meet the needs of high-precision assembly or maintenance. Summary of the Invention

[0005] In view of this, this application provides a high-precision measurement method for the gap change of aircraft split doors, which solves the problems in the prior art and realizes non-contact, high-precision, and high-resolution quantitative characterization of gap morphology.

[0006] The high-precision measurement method for the gap change of aircraft double-opening hatches provided in this application adopts the following technical solution: A high-precision measurement method for the change in the gap of an aircraft's split-opening hatch includes the following steps: Construct a binocular stereo vision measurement error propagation model; Establish a three-dimensional coordinate system. The x-axis of the three-dimensional coordinate system is parallel to the line connecting the rotation axes of the left and right cabin doors of the aircraft. The y-axis of the three-dimensional coordinate system is parallel to the rotation axes of the left and right cabin doors of the aircraft. Based on the binocular stereo vision measurement error propagation model, the calibration parameters of the left and right cameras of the binocular stereo vision measurement system are input, and the measurement uncertainty at any point in the measurement field of view is predicted. According to the predicted measurement uncertainty, the parameters of the binocular stereo vision measurement system are adjusted until the predicted measurement error meets the accuracy requirements, thus obtaining the binocular stereo vision measurement system for measurement. A first target point was placed on the left side of the aircraft's double-leaf hatch, and a second target point was placed on the right side. The positional changes of the first and second target points after door loading were tracked using a binocular stereo vision measurement system. The changes in the three-dimensional coordinates of the first and second target points after door loading relative to their positions before loading were obtained. Based on these changes in three-dimensional coordinates, the change in the gap width of the aircraft's double-leaf hatches was calculated. and step change .

[0007] Optionally, the error propagation model for binocular stereo vision measurement is as follows:

[0008] Where P is a three-dimensional point in space. The measurement uncertainty of the three-dimensional coordinates of point P. Let be the error propagation function. Influence factors affecting the uncertainty of geometric reconstruction error of 3D objects Jacobian matrix, =( f L , x L , y L , f R , x R , y R , f , oh , k , t x , t y , t z ), Indicates the uncertainty of the influence factor ，f L The focal length of the left camera in the binocular stereo vision measurement system. x L Let x be the x-coordinate of the physical coordinates of point P mapped onto the left camera image plane. y L Let be the ordinate value of the physical coordinates of point P mapped to the left camera image plane. f R The focal length of the right camera in the binocular stereo vision measurement system. x R Let x be the x-coordinate of the physical coordinates of point P mapped onto the right camera image plane. y RLet be the ordinate value of the physical coordinates of point P mapped to the right camera image plane. f The Euler angles of rotation from the world coordinate system to the coordinate systems of the left and right cameras in the binocular stereo vision measurement system. oh The pitch angle is the angle from the world coordinate system to the coordinate systems of the left and right cameras in the binocular stereo vision measurement system. k The roll angle is the angle from the world coordinate system to the coordinate systems of the left and right cameras in the binocular stereo vision measurement system. t x , t y , t z Translation parameters from the world coordinate system to the camera coordinate system ，f L , f R , f , oh , k , t x , t y , t z The corresponding uncertainty is obtained after camera calibration; Then we have: ,in, This indicates one of the influencing factors. A is the camera intrinsic parameter matrix, and B is the constraint matrix; For a binocular stereo vision measurement system, the intrinsic parameter matrix of the calibrated left camera is: , The intrinsic parameter matrix of the right camera after calibration is: , ;in,( , ) represents the coordinates of the origin of the left camera image coordinate system in the pixel coordinate system. , () represents the coordinates of the origin of the right camera image coordinate system in the pixel coordinate system; The external parameters of the left camera after calibration are: ,in, Let be the rotation transformation matrix from the world coordinate system to the left camera coordinate system. Let be the rotation transformation matrix from the world coordinate system to the right camera coordinate system. Let be the translation matrix from the world coordinate system to the left camera coordinate system. Let be the translation matrix from the world coordinate system to the right camera coordinate system. r 1- r 9 represents the left camera rotation matrix element; joint , , , , and ,get: ; ; In the formula, , ( , ) represents the coordinates of point P mapped to the left camera pixel coordinate system. , () represents the coordinates of point P mapped to the right camera pixel coordinate system; , , and The expressions for the distortion coefficients are as follows:

[0009] in, This represents the distance from point P to the origin in the left camera image coordinate system. This represents the distance from point P to the origin in the right camera image coordinate system. , r 0 is a constant. K L1 , K L2 , K L1 The radial distortion coefficient of the left camera. K R1 , K R2 , K R3 The radial distortion coefficient of the right camera. P L1 ,and P L2 The eccentricity distortion coefficient of the left camera. P R1 and P R2 The eccentricity distortion coefficient of the right camera. b L1 and b L2 Let be the planar distortion coefficient of the right camera. b R1 and b R2 The plane distortion coefficient of the right camera; Using variance representation , , and Uncertainty: ; ; In the formula, ; u L0 , v L0 , K L1 , K L2 , K L3 , P L1 , P L2 , b L1 , b L2 , u R0 , v R0 , K R1 , K R2 , K R3 , P R1 , P R2 , b R1 , b R2 The uncertainty is obtained after camera calibration is completed. u L , v L , u R ,、 v R The uncertainty is obtained during image detection.

[0010] Optionally, the distance between the first target point and the edge of the left hatch near the gap, and the distance between the second target point and the edge of the right hatch near the gap, are both... The change in the three-dimensional coordinates of the first target point is ( , , The change in the three-dimensional coordinates of the first target point is ( ). , , ); ; ( + )-( + ), plus or minus sign and The signs must be the same. plus or minus sign and The signs must be the same; in, The rotation angle of the left hatch after loading is given. The rotation angle of the right hatch after loading.

[0011] Optionally, the target point is a circular pattern, which is formed by a combination of a central black solid circle and an outer white ring, with the inner circles of the central black solid circle and the outer white ring adjoining each other.

[0012] Optional, The value is 5mm.

[0013] Optionally, the radius of the target point is 5 mm.

[0014] In summary, this application includes the following beneficial technical effects: This application optimizes the binocular stereo vision measurement system based on the binocular stereo vision measurement error propagation model, thereby improving the accuracy of the binocular stereo vision measurement system. On this basis, by placing targets on the hatch closure interface and tracking the temporal evolution of the target's three-dimensional coordinates in real time, the width direction of the hatch gap, i.e., the longitudinal geometric change of the hatch gap outside the surface, and the full-field dynamic change of the step difference, i.e., the longitudinal geometric change of the hatch gap outside the surface, are inverted through stereo matching and spatial analysis algorithms. This achieves non-contact, high-precision, and high-resolution quantitative characterization of the gap morphology, and realizes highly robust measurement with sub-millimeter accuracy.

[0015] In this application, the gap width and step difference changes of the actual edges of the left and right hatches are calculated by combining the positional changes of the target point and the distance from the gap. Instead of directly equating the changes of the target point to the changes of the edges of the left and right hatches, this method improves the accuracy of the gap width and step difference measurement between the left and right hatches. Attached Figure Description

[0016] To more clearly illustrate the technical solutions of the embodiments of this application, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0017] Figure 1 This is a flowchart illustrating the high-precision measurement method for the aircraft's adjoint door clearance variation, as described in this application. Figure 2 This is a schematic diagram showing the position of the hatch before and after loading, according to an embodiment of this application. Detailed Implementation

[0018] The embodiments of this application will now be described in detail with reference to the accompanying drawings.

[0019] The following specific examples illustrate the implementation of this application. Those skilled in the art can easily understand other advantages and effects of this application from the content disclosed in this specification. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them. This application can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of this application. It should be noted that, in the absence of conflict, the following embodiments and features in the embodiments can be combined with each other. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0020] It should be noted that various aspects of embodiments within the scope of the appended claims are described below. It will be apparent that the aspects described herein can be embodied in a wide variety of forms, and any particular structure and / or function described herein is merely illustrative. Based on this application, those skilled in the art will understand that one aspect described herein can be implemented independently of any other aspect, and two or more of these aspects can be combined in various ways. For example, any number of aspects set forth herein can be used to implement the device and / or practice the method. Additionally, this device and / or method can be implemented using structures and / or functionalities other than one or more of the aspects set forth herein.

[0021] It should also be noted that the illustrations provided in the following embodiments are only schematic representations of the basic concept of this application. The illustrations only show the components related to this application and are not drawn according to the number, shape and size of the components in actual implementation. In actual implementation, the form, quantity and proportion of each component can be arbitrarily changed, and the layout of the components may also be more complex.

[0022] Furthermore, specific details are provided in the following description to facilitate a thorough understanding of the examples. However, those skilled in the art will understand that the described aspects can be practiced without these specific details.

[0023] This application provides a high-precision measurement method for the change in the gap between aircraft split doors.

[0024] like Figure 1 and Figure 2As shown, a high-precision measurement method for the change in the gap of an aircraft's split-opening hatch includes the following steps: Construct a model for the propagation of measurement errors in binocular stereo vision.

[0025] Establish a three-dimensional coordinate system. The x-axis of the three-dimensional coordinate system is parallel to the line connecting the left door rotation axis O1 and the right door rotation axis O2 of the aircraft's double-opening cabin doors. The y-axis of the three-dimensional coordinate system is parallel to the left door rotation axis O1 and the right door rotation axis O2 of the aircraft's double-opening cabin doors.

[0026] Based on the error propagation model of binocular stereo vision measurement, the calibration parameters of the left and right cameras of the binocular stereo vision measurement system are input, and the measurement uncertainty at any point in the measurement field of view is predicted. According to the predicted measurement uncertainty, the parameters of the binocular stereo vision measurement system are adjusted until the predicted measurement error meets the accuracy requirements, thus obtaining the binocular stereo vision measurement system for measurement.

[0027] A first target point was affixed to the left side of the aircraft's double-leaf hatch, and a second target point was affixed to the right side. The positional changes of the first and second target points after door loading were tracked using a binocular stereo vision measurement system. The three-dimensional coordinate changes of the first target point C1 and the second target point D1 after door loading relative to the first target point C0 and the second target point D0 before door loading were obtained. Based on these three-dimensional coordinate changes, the change in the gap width of the aircraft's double-leaf hatches was calculated. and step change In this embodiment, the target point is a circular pattern, which is formed by a central black solid circle and an outer white annular ring, with the inner circles of the central black solid circle and the outer white annular ring adjoining each other. The radius of the target point is 5mm.

[0028] This application optimizes the binocular stereo vision measurement system based on the binocular stereo vision measurement error propagation model, thereby improving the accuracy of the binocular stereo vision measurement system. On this basis, by placing targets on the hatch closure interface and tracking the temporal evolution of the target's three-dimensional coordinates in real time, the width direction of the hatch gap, i.e., the longitudinal geometric change of the hatch gap outside the surface, and the full-field dynamic change of the step difference, i.e., the longitudinal geometric change of the hatch gap outside the surface, are inverted through stereo matching and spatial analysis algorithms. This achieves non-contact, high-precision, and high-resolution quantitative characterization of the gap morphology, and realizes highly robust measurement with sub-millimeter accuracy.

[0029] The error propagation model for binocular stereo vision measurement is as follows:

[0030] Where P is a three-dimensional point in space. The measurement uncertainty of the three-dimensional coordinates of point P. Let be the error propagation function. Influence factors affecting the uncertainty of geometric reconstruction error of 3D objects Jacobian matrix, =( f L , x L , y L , f R , x R , y R , f , oh , k , t x , t y , t z ), Indicates the uncertainty of the influence factor ，f L The focal length of the left camera in the binocular stereo vision measurement system. x L Let x be the x-coordinate of the physical coordinates of point P mapped onto the left camera image plane. y L Let be the ordinate value of the physical coordinates of point P mapped to the left camera image plane. f R The focal length of the right camera in the binocular stereo vision measurement system. x R Let x be the x-coordinate of the physical coordinates of point P mapped onto the right camera image plane. y R Let be the ordinate value of the physical coordinates of point P mapped to the right camera image plane. f The Euler angles of rotation from the world coordinate system to the coordinate systems of the left and right cameras in the binocular stereo vision measurement system. oh The pitch angle is the angle from the world coordinate system to the coordinate systems of the left and right cameras in the binocular stereo vision measurement system. k The roll angle is the angle from the world coordinate system to the coordinate systems of the left and right cameras in the binocular stereo vision measurement system. t x , t y , t z Translation parameters from the world coordinate system to the camera coordinate system ，f L , f R , f , oh , k ,t x , t y , t z The corresponding uncertainty is obtained after camera calibration; Then we have: ,in, This indicates one of the influencing factors. A is the camera intrinsic parameter matrix, and B is the constraint matrix; For a binocular stereo vision measurement system, the intrinsic parameter matrix of the calibrated left camera is: , The intrinsic parameter matrix of the right camera after calibration is: , ;in,( , ) represents the coordinates of the origin of the left camera image coordinate system in the pixel coordinate system. , () represents the coordinates of the origin of the right camera image coordinate system in the pixel coordinate system; The external parameters of the left camera after calibration are: ,in, Let be the rotation transformation matrix from the world coordinate system to the left camera coordinate system. Let be the rotation transformation matrix from the world coordinate system to the right camera coordinate system. Let be the translation matrix from the world coordinate system to the left camera coordinate system. Let be the translation matrix from the world coordinate system to the right camera coordinate system. r 1- r 9 represents the left camera rotation matrix element; joint , , , , and ,get: ; ; In the formula, , ( , ) represents the coordinates of point P mapped to the left camera pixel coordinate system. , () represents the coordinates of point P mapped to the right camera pixel coordinate system; , , and The expressions for the distortion coefficients are as follows:

[0031] in, This represents the distance from point P to the origin in the left camera image coordinate system. This represents the distance from point P to the origin in the right camera image coordinate system. , r 0 is a constant. K L1 , K L2 , K L1 The radial distortion coefficient of the left camera. K R1 , K R2 , K R3 The radial distortion coefficient of the right camera. P L1 ,and P L2 The eccentricity distortion coefficient of the left camera. P R1 and P R2 The eccentricity distortion coefficient of the right camera. b L1 and b L2 Let be the planar distortion coefficient of the right camera. b R1 and b R2 The plane distortion coefficient of the right camera; Using variance representation , , and Uncertainty: ; ; In the formula, ; u L0 , v L0 , K L1 , K L2 , K L3 , P L1 , P L2 , b L1 , bL2 , u R0 , v R0 , K R1 , K R2 , K R3 , P R1 , P R2 , b R1 , b R2 The uncertainty is obtained after camera calibration is completed. u L , v L , u R ,、 v R The uncertainty is obtained during image detection.

[0032] The binocular stereo vision measurement error propagation model of this application can predict the measurement error at any point within the field of view.

[0033] The distances between the first target point and the edge of the left hatch near the gap, and the distances between the second target point and the edge of the right hatch near the gap, are both... The change in the three-dimensional coordinates of the first target point is ( , , The change in the three-dimensional coordinates of the first target point is ( ). , , In this embodiment of the application, The value is 5mm.

[0034] ; ( + )-( + ), plus or minus sign and The signs must be the same. plus or minus sign and The signs must be the same; in, The rotation angle of the left hatch after loading is given. The rotation angle of the right hatch after loading.

[0035] In this application, the gap width and step difference changes of the actual edges of the left and right hatches are calculated by combining the positional changes of the target point and the distance from the gap. Instead of directly equating the changes of the target point to the changes of the edges of the left and right hatches, this method improves the accuracy of the gap width and step difference measurement between the left and right hatches.

[0036] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A high-precision method for measuring the change in the gap of an aircraft's split-opening hatch, characterized in that, Includes the following steps: Construct a binocular stereo vision measurement error propagation model; Establish a three-dimensional coordinate system. The x-axis of the three-dimensional coordinate system is parallel to the line connecting the rotation axes of the left and right cabin doors of the aircraft. The y-axis of the three-dimensional coordinate system is parallel to the rotation axes of the left and right cabin doors of the aircraft. Based on the binocular stereo vision measurement error propagation model, the calibration parameters of the left and right cameras of the binocular stereo vision measurement system are input, and the measurement uncertainty at any point in the measurement field of view is predicted. According to the predicted measurement uncertainty, the parameters of the binocular stereo vision measurement system are adjusted until the predicted measurement error meets the accuracy requirements, thus obtaining the binocular stereo vision measurement system for measurement. A first target point was placed on the left side of the aircraft's double-leaf hatch, and a second target point was placed on the right side. The positional changes of the first and second target points after door loading were tracked using a binocular stereo vision measurement system. The changes in the three-dimensional coordinates of the first and second target points after door loading relative to their positions before loading were obtained. Based on these changes in three-dimensional coordinates, the change in the gap width of the aircraft's double-leaf hatches was calculated. and step change .

2. The high-precision measurement method for the change in the gap of aircraft hatches according to claim 1, characterized in that, The error propagation model for binocular stereo vision measurement is as follows: Where P is a three-dimensional point in space. The measurement uncertainty of the three-dimensional coordinates of point P. Let be the error propagation function. Influence factors affecting the uncertainty of geometric reconstruction error of 3D objects Jacobian matrix, =( f L , x L , y L , f R , x R , y R , φ , ω , κ , t x , t y , t z ), Indicates the uncertainty of the influence factor ，f L The focal length of the left camera in the binocular stereo vision measurement system. x L Let x be the x-coordinate of the physical coordinates of point P mapped onto the left camera image plane. y L Let be the ordinate value of the physical coordinates of point P mapped to the left camera image plane. f R The focal length of the right camera in the binocular stereo vision measurement system. x R Let x be the x-coordinate of the physical coordinates of point P mapped onto the right camera image plane. y R Let be the ordinate value of the physical coordinates of point P mapped to the right camera image plane. φ The Euler angles of rotation from the world coordinate system to the coordinate systems of the left and right cameras in the binocular stereo vision measurement system. ω The pitch angle is the angle from the world coordinate system to the coordinate systems of the left and right cameras in the binocular stereo vision measurement system. κ The roll angle is the angle from the world coordinate system to the coordinate systems of the left and right cameras in the binocular stereo vision measurement system. t x , t y , t z Translation parameters from the world coordinate system to the camera coordinate system ，f L , f R , φ , ω , κ , t x , t y , t z The corresponding uncertainty is obtained after camera calibration; Then we have: ,in, This indicates one of the influencing factors. A is the camera intrinsic parameter matrix, and B is the constraint matrix; For a binocular stereo vision measurement system, the intrinsic parameter matrix of the calibrated left camera is: , The intrinsic parameter matrix of the right camera after calibration is: , ;in,( , ) represents the coordinates of the origin of the left camera image coordinate system in the pixel coordinate system. , () represents the coordinates of the origin of the right camera image coordinate system in the pixel coordinate system; The external parameters of the left camera after calibration are: ,in, Let be the rotation transformation matrix from the world coordinate system to the left camera coordinate system. Let be the rotation transformation matrix from the world coordinate system to the right camera coordinate system. Let be the translation matrix from the world coordinate system to the left camera coordinate system. Let be the translation matrix from the world coordinate system to the right camera coordinate system. r 1- r 9 represents the left camera rotation matrix element; joint , , , , and ,get: ； ； In the formula, , ( , ) represents the coordinates of point P mapped to the left camera pixel coordinate system. , () represents the coordinates of point P mapped to the right camera pixel coordinate system; , , and The expressions for the distortion coefficients are as follows: in, This represents the distance from point P to the origin in the left camera image coordinate system. This represents the distance from point P to the origin in the right camera image coordinate system. , r 0 is a constant. K L1 , K L2 , K L1 The radial distortion coefficient of the left camera. K R1 , K R2 , K R3 The radial distortion coefficient of the right camera. P L1 ,and P L2 The eccentricity distortion coefficient of the left camera. P R1 and P R2 The eccentricity distortion coefficient of the right camera. b L1 and b L2 Let be the planar distortion coefficient of the right camera. b R1 and b R2 The plane distortion coefficient of the right camera; Using variance representation , , and Uncertainty: ； ； In the formula, ; u L0 , v L0 , K L1 , K L2 , K L3 , P L1 , P L2 , b L1 , b L2 , u R0 , v R0 , K R1 , K R2 , K R3 , P R1 , P R2 , b R1 , b R2 The uncertainty is obtained after camera calibration is completed. u L , v L , u R ,、 v R The uncertainty is obtained during image detection.

3. The high-precision measurement method for the change in the gap of aircraft hatches according to claim 1, characterized in that, The distances between the first target point and the edge of the left hatch near the gap, and the distances between the second target point and the edge of the right hatch near the gap, are both... The change in the three-dimensional coordinates of the first target point is ( , , The change in the three-dimensional coordinates of the first target point is ( ). , , ); ； ( + )-( + ), plus or minus sign and The signs must be the same. plus or minus sign and The signs must be the same; in, The rotation angle of the left hatch after loading is given. The rotation angle of the right hatch after loading.

4. The high-precision measurement method for the change in the gap of aircraft hatches according to claim 1, characterized in that, The target point is a circular pattern, which is formed by a combination of a central black solid circle and an outer white ring. The inner circles of the central black solid circle and the outer white ring are adjacent.

5. The high-precision measurement method for the change in the gap of aircraft hatches according to claim 3, characterized in that, The value is 5mm.

6. The high-precision measurement method for the change in the gap of aircraft hatches according to claim 4, characterized in that, The radius of the target point is 5mm.

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