Deformation measurement method and system of composite vision measurement unit

Abstract

The invention belongs to the technical field of three-dimensional vision measurement, and relates to a deformation measurement method and system of a composite vision measurement unit. The internal and external parameters of the binocular measurement unit are obtained according to the image of the thrust vectoring nozzle target area calibration plate; obtaining coordinates of all binocular measurement units in the same reference coordinate system according to the internal and external parameters and the images of the thrust vectoring nozzles with the first coded mark points, and obtaining coordinates of all binocular measurement units in a unified coordinate system; and acquiring full-field deformation of all target areas of the thrust vectoring nozzle according to the speckle images of the target areas of the thrust vectoring nozzle in the working state and the coordinates of the unified coordinate system of all binocular measurement units. According to the invention, a digital image correlation method and a close-range photogrammetry technology are utilized to realize coordinate system unification and full-field deformation measurement. Compared with a traditional method, the measurement times and data processing steps are reduced, and the measurement efficiency is improved.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of three-dimensional vision measurement, and relates to a deformation measurement method and system of a composite vision measurement unit. BACKGROUND

[0002] In three-dimensional measurement, the DIC technology has the advantages of non-contact, high precision, wide application range, etc., and its main measurement scheme adopts a monocular camera or a binocular camera system for deformation measurement. The conventional monocular and binocular camera systems have problems such as visual field blind area and insufficient width, etc., and cannot realize simultaneous measurement of all key regions, such as deformation measurement of key regions of a vector nozzle with large curvature surface.

[0003] Specifically, the vector nozzle is relatively large in size, and it is impossible to shoot the complete region of interest (there will be occlusion in a single visual angle) by using only two cameras, so it is necessary to arrange camera groups at other visual angles to obtain local deformation fields of different key regions. At present, a binocular camera measurement system or a multi-camera measurement system is usually used for measurement. When the binocular camera measurement system is used for repeated measurement, the nozzle will be deformed due to work, a group of cameras cannot measure different regions at the same time, and the cumulative error will be caused by repeated measurement of deformation; the multi-camera measurement system cannot completely calculate the local deformation fields of all key regions. SUMMARY

[0004] The present application aims to provide a deformation measurement method and system of a composite vision measurement unit to solve the technical problems of cumulative error caused by repeated measurement of a binocular camera and the inability of a multi-camera measurement system to completely calculate the local deformation fields of all key regions.

[0005] In order to achieve the above-mentioned purpose, the present application adopts the following technical scheme: In a first aspect, the present application provides a deformation measurement method of a composite vision measurement unit, the composite vision measurement unit comprising a plurality of binocular measurement units arranged around a vector nozzle, the vector nozzle being provided with a calibration plate, a first coded marker and a speckle, and comprising the following steps: acquiring images of the calibration plate of the target region of the vector nozzle, images of the vector nozzle with the first coded marker and speckle images of the target region of the vector nozzle in a working state collected by the plurality of binocular measurement units; acquiring internal and external parameters of the binocular measurement units according to the images of the calibration plate of the target region of the vector nozzle; acquiring coordinates of all binocular measurement units in the same reference coordinate system according to the internal and external parameters and the images of the vector nozzle with the first coded marker, and obtaining coordinates of a unified coordinate system of all binocular measurement units; acquiring full-field deformation of all target regions of the vector nozzle according to the speckle images of the target region of the vector nozzle in the working state and the coordinates of the unified coordinate system of all binocular measurement units.

[0006] Further, the image acquisition method of the vector nozzle target area calibration board is specifically as follows: The calibration board is fixed on the target area of the vector nozzle, and the image of the vector nozzle target area calibration board is collected by the binocular measurement unit; The image acquisition method of the vector nozzle with first coded marker points is specifically as follows: The first coded marker points are arranged around the vector nozzle, and the binocular measurement unit is arranged around the periphery of the vector nozzle, and the image of the vector nozzle with first coded marker points is collected by the binocular measurement unit; The image acquisition method of the vector nozzle target area under working condition is specifically as follows: The high-temperature-resistant speckle is sprayed on the target area of the vector nozzle, and the speckle images of the vector nozzle target area under different working conditions are collected by the binocular measurement unit.

[0007] Further, the binocular measurement unit comprises two cameras, the two cameras are connected by a cross beam, and all the cross beams of the binocular measurement units are connected by a tripod.

[0008] Further, the internal and external parameters of the binocular measurement unit are acquired according to the image of the vector nozzle target area calibration board, and specifically as follows: The second coded marker points are arranged on the calibration board; The center coordinates of the second coded marker points are acquired based on edge detection algorithm and iterative least square fitting according to the image of the vector nozzle target area calibration board; The second coded marker points in the image of the vector nozzle target area calibration board are decoded by affine transformation and gray scale scanning to obtain the coded ID, the center coordinates of the second coded marker points are numbered according to the coded ID, and the number of the second coded marker points is obtained; The three-dimensional coordinates of the second coded marker points are acquired according to the image of the vector nozzle target area calibration board, the scale of the calibration board and the number of the second coded marker points; The internal and external parameters of the binocular measurement unit are acquired according to the center coordinates and three-dimensional coordinates of the second coded marker points combined with the camera imaging model.

[0009] Further, the center coordinates of the second coded marker points are acquired according to the following formula:

[0010]

[0011] In the formula, is the edge point with the center of the ellipse as the origin X axis coordinates, is the edge point with the ellipse center as the origin Y axis coordinates, is the edge point obtained by sub-pixel edge detection X axis coordinates, is the edge point obtained by sub-pixel edge detection Y axis coordinates, is the ellipse center point in the iteration process X axis coordinates, is the ellipse center point in the iteration process Y axis coordinates, is the major axis of the ellipse, is the minor axis of the ellipse, is the angle between the major axis of the ellipse and X axis, is the error term of the ellipse fitting, is the number of edge coordinates.

[0012] Further, the internal and external parameters of the binocular measurement unit are obtained according to the center coordinates and three-dimensional coordinates of the second coded marker point in combination with a camera imaging model, and the internal and external parameters of the binocular measurement unit are obtained according to the mapping relationship between the world coordinates and the pixel coordinates, and the formula is as follows: The mapping relationship between the world coordinates and the pixel coordinates is established by using the collinear condition equation of the camera imaging model, and the internal and external parameters of the binocular measurement unit are obtained according to the mapping relationship, and the formula is as follows:

[0013] In the formula, is the camera image point X axis coordinates, is the camera image point Y axis coordinates, is the object point in the camera coordinate system axis coordinates, is the camera internal parameter matrix, is the camera projection matrix, which is composed of a camera rotation matrix and a translation matrix.

[0014] Further, the coordinates of all binocular measurement units in the same reference coordinate system are obtained according to the internal and external parameters and the image of the vector nozzle with the first coded marker point, and the coordinates of the unified coordinate system of all binocular measurement units are obtained, and the specific process is as follows: The world coordinate system of each binocular measurement unit is established based on the left camera coordinate system of each binocular measurement unit; The center coordinates of the first coded marker point are obtained based on the edge detection algorithm and the iterative least square fitting according to the image of the vector nozzle with the first coded marker point. The first coding mark point in the image of the vector jet with the first coding mark point is decoded through affine transformation and gray scale scanning, to obtain a coding ID, and the center coordinates of the first coding mark point are numbered according to the coding ID, to obtain the number of the first coding mark point; According to the internal and external parameters and the image of the vector jet with the first coding mark point, the three-dimensional coordinates of the first coding mark point are obtained through the collinear condition equation; According to the number of the first coding mark point and the three-dimensional coordinates of the first coding mark point, the coordinates of all binocular measurement units in the same reference coordinate system are obtained, to obtain the coordinates of the unified coordinate system of all binocular measurement units.

[0015] Further, the formula for obtaining the three-dimensional coordinates of the first coding mark point is as follows:

[0016]

[0017] In the formula, is the left camera image point X axis coordinates, is the left camera image point Y axis coordinates, is the right camera image point X axis coordinates, is the right camera image point Y axis coordinates, is the left camera coordinate system under the object point axis coordinates, is the right camera coordinate system under the object point z-axis coordinates, is the left camera internal parameter matrix, is the right camera internal parameter matrix, is the left camera projection matrix, is the right camera projection matrix; According to the number of the first coding mark point and the three-dimensional coordinates of the first coding mark point, the coordinates of all binocular measurement units in the same reference coordinate system are obtained, to obtain the coordinates of the unified coordinate system of all binocular measurement units, including: Taking the world coordinate system of one group of binocular measurement units as the reference coordinate system, the world coordinate systems of the remaining groups of binocular measurement units are subjected to translation and rotation operations, to transform the world coordinate systems of the binocular measurement units to the reference coordinate system, and the conversion formula is:

[0018] In the formula, is the reference world coordinate system under X axis coordinates, is the reference world coordinate system under Y axis coordinates, is the axis coordinate of the reference world coordinate system under Z is the axis coordinate of the reference world coordinate system under is the axis coordinate of a set of world coordinate systems under X is the axis coordinate of a set of world coordinate systems under is the axis coordinate of a set of world coordinate systems under Y is the axis coordinate of a set of world coordinate systems under is the axis coordinate of a set of world coordinate systems under Z is the axis coordinate of a set of world coordinate systems under is the rotation matrix corresponding to the conversion of the binocular measurement unit to the reference world coordinate system is the translation matrix corresponding to the conversion of the binocular measurement unit to the reference world coordinate system.

[0019] Further, the full-field deformation of the vector jet is obtained according to the speckle image of the target area of the vector jet under the working state and the coordinates of the unified coordinate system of all binocular measurement units, including: the speckle image of the target area of the vector jet under the working state is divided into blocks and the gray level is calculated by digital image correlation method to obtain the center coordinates of the speckle image block sub-area; the center coordinates of the speckle image are processed by relative orientation, absolute orientation, epipolar matching, three-dimensional reconstruction and bundle adjustment algorithm to obtain the three-dimensional coordinates of the target area of the vector jet; the local deformation data of the target area of the vector jet is calculated using the three-dimensional coordinates of the target area of the vector jet to obtain the displacement and strain of the target area of the vector jet; the displacement and strain measured by each binocular measurement unit are unified to the reference coordinate system to obtain the full-field deformation of all target areas of the jet.

[0020] In a second aspect, the present application provides a deformation measurement system of a composite visual measurement unit, comprising: a data acquisition module for acquiring images of a vector jet target area calibration board collected by a plurality of binocular measurement units, images of a vector jet with first coded marker points and speckle images of a vector jet target area under a working state; an internal and external parameter acquisition module for acquiring internal and external parameters of the binocular measurement units according to the images of the vector jet target area calibration board; a binocular measurement unit coordinate system module for acquiring coordinates of all binocular measurement units under the same reference coordinate system according to the internal and external parameters and the images of the vector jet with first coded marker points to obtain the coordinates of the unified coordinate system of all binocular measurement units; a full-field deformation acquisition module for acquiring the full-field deformation of all target areas of the vector jet according to the speckle images of the vector jet target area under the working state and the coordinates of the unified coordinate system of all binocular measurement units.

[0021] Compared with the prior art, the present application has the following beneficial effects: The present application obtains the internal and external parameters of the binocular measurement unit according to the image of the target area calibration board of the vector nozzle. By obtaining the internal and external parameters of the binocular measurement unit, a foundation is laid for subsequent accurate measurement of different key areas. According to the internal and external parameters and the image of the vector nozzle with the first coded marker point, the coordinates of all binocular measurement units in the same reference coordinate system are obtained, and the coordinates of the unified coordinate system of all binocular measurement units are obtained. By using the internal and external parameters and the image with the coded marker point, the coordinates of all binocular measurement units are unified in the same reference coordinate system, which provides a unified reference system for comprehensive analysis of the deformation of the vector nozzle. It is beneficial to avoid data errors and misunderstandings caused by differences in coordinate systems, and to improve the accuracy and reliability of deformation analysis. In addition, the unified coordinate system makes subsequent data processing and analysis more convenient, improves the data processing efficiency, and reduces the difficulty and cost of data processing. According to the speckle image of the target area of the vector nozzle in the working state and the coordinates of the unified coordinate system of all binocular measurement units, the full-field deformation of all target areas of the vector nozzle is obtained. By combining the speckle image in the working state, the full-field deformation information of all target areas of the vector nozzle can be obtained, and the deformation of the nozzle in the working process can be comprehensively understood. In addition, the present application obtains the full-field deformation by one measurement, avoiding the cumulative error caused by multiple measurements, and improving the accuracy and reliability of deformation measurement.

[0022] The system of the present application comprises a data acquisition module, an internal and external parameter acquisition module, a binocular measurement unit coordinate system unification module and a full-field deformation acquisition module. The data acquisition module is used to acquire the images of the target area calibration board of the vector nozzle collected by multiple binocular measurement units, the image of the vector nozzle with the first coded marker point and the speckle image of the target area of the vector nozzle in the working state. The internal and external parameter acquisition module is used to obtain the internal and external parameters of the binocular measurement unit according to the image of the target area calibration board of the vector nozzle; the binocular measurement unit coordinate system unification module is used to obtain the coordinates of all binocular measurement units in the same reference coordinate system according to the internal and external parameters and the image of the vector nozzle with the first coded marker point, and obtain the coordinates of the unified coordinate system of all binocular measurement units; the full-field deformation acquisition module is used to obtain the full-field deformation of all target areas of the vector nozzle according to the speckle image of the target area of the vector nozzle in the working state and the coordinates of the unified coordinate system of all binocular measurement units. Each module cooperates with each other, and can comprehensively understand the deformation of the nozzle in the working process, improving the accuracy and reliability of deformation measurement. BRIEF DESCRIPTION OF DRAWINGS

[0023] Figure 1 The method flowchart of the embodiment of the present application.

[0024] Figure 2 The structural configuration schematic diagram of the multi-camera group system of the embodiment of the present application.

[0025] Figure 3 is the close-range photogrammetry principle diagram of the embodiment of the present application.

[0026] Figure 4 is the overall algorithm flow chart of the coordinate system I of the composite vision measurement unit and the deformation measurement method of the embodiment of the present application.

[0027] Figure 5 is the coordinate system I principle diagram of the measurement unit of the embodiment of the present application; Figure 6 is the coordinate system I principle diagram of the measurement unit of the embodiment of the present application; Figure 7 is the system module diagram of the embodiment of the present application.

[0028] Wherein: 1, binocular measurement unit; L1, left field of view boundary of the left camera of the binocular measurement unit; L2, right field of view boundary of the right camera of the binocular measurement unit. DETAILED DESCRIPTION

[0029] In order to make the personnel in the art better understand the present application scheme, the technical scheme in the embodiment of the present application will be described clearly and completely below in combination with the drawings in the embodiment of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by the person skilled in the art without creative labor should belong to the scope of protection of the present application.

[0030] It should be noted that the terms "first", "second" and the like in the specification of the present application and the above-mentioned drawings are used to distinguish similar objects, and do not necessarily indicate a specific order or sequence. It should be understood that the data thus used can be interchanged under appropriate circumstances, so that the embodiments of the present application described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "include" and "have" and any variations thereof are intended to cover non-exclusive inclusion, for example, a process, method, system, product or device including a series of steps or units does not necessarily limit to those steps or units clearly listed, but can include other steps or units not clearly listed or inherent to these processes, methods, products or devices.

[0031] The present application will be described in further detail below in combination with the drawings: Embodiment one: Reference Figure 1The embodiment discloses a deformation measurement method of a composite visual measurement unit, the composite visual measurement unit comprises a plurality of binocular measurement units arranged around a vector nozzle, and a calibration plate, a first coded mark point and a speckle are arranged on the vector nozzle, and the method comprises the following steps: S1, acquiring images of a target region calibration plate of the vector nozzle, images of the vector nozzle with the first coded mark point and speckle images of the target region of the vector nozzle in a working state collected by the plurality of binocular measurement units; In the embodiment of the application, the method for acquiring the images of the target region calibration plate of the vector nozzle is specifically as follows: The calibration plate is fixed on the target region of the vector nozzle, and the images of the target region calibration plate of the vector nozzle are collected by the binocular measurement unit; In the embodiment of the application, the method for acquiring the images of the vector nozzle with the first coded mark point is specifically as follows: The first coded mark point is arranged around the vector nozzle, and the binocular measurement unit is arranged around the periphery of the vector nozzle, and the images of the vector nozzle with the first coded mark point are collected by the binocular measurement unit; In the embodiment of the application, the method for acquiring the speckle images of the target region of the vector nozzle in the working state is specifically as follows: The high-temperature-resistant speckle is sprayed on the target region of the vector nozzle, and the speckle images of the target region of the vector nozzle in different working states are collected by the binocular measurement unit.

[0032] S2, acquiring the internal and external parameters of the binocular measurement unit 1 according to the images of the target region calibration plate of the vector nozzle. The internal and external parameters of the binocular measurement unit 1 are acquired, which lays a foundation for subsequent accurate measurement of different key regions. The internal and external parameters can accurately describe the geometric model of camera imaging, and accurately correspond three-dimensional space points and two-dimensional image points. When measuring the deformation of the vector nozzle, the measurement error caused by inaccurate camera parameters can be reduced, the measurement accuracy of the deformation is improved, and reliable data for subsequent accurate analysis of the working state of the nozzle is provided.

[0033] In the embodiment of the application, the internal and external parameters of the binocular measurement unit 1 are acquired according to the images of the target region calibration plate of the vector nozzle, and are specifically as follows: S21, the calibration plate is arranged with a second coded mark point; The center coordinates of the second coded mark point are acquired based on an edge detection algorithm and an iterative least square fitting according to the images of the target region calibration plate of the vector nozzle, and the acquisition formula of the center coordinates of the second coded mark point is as follows:

[0034]

[0035] In the formula, is the edge point with the ellipse center as the origin X axis coordinates, is the edge point with the ellipse center as the origin Y axis coordinates, is the edge point obtained by sub-pixel edge detection X axis coordinates, is the edge point obtained by sub-pixel edge detection Y axis coordinates, is the ellipse center point in the iteration process X axis coordinates, is the ellipse center point in the iteration process Y axis coordinates, is the major axis of the ellipse, is the minor axis of the ellipse, is the angle between the major axis of the ellipse and X axis, is the error term of the ellipse fitting, is the number of edge coordinates.

[0036] S22, decode the second coded mark point in the image of the vector jet target area calibration plate by affine transformation and gray scanning, obtain the coded ID, number the center coordinates of the second coded mark point according to the coded ID, and obtain the number of the second coded mark point; S23, obtain the three-dimensional coordinates of the second coded mark point according to the image of the vector jet target area calibration plate, the scale of the calibration plate and the number of the second coded mark point; S24, obtain the internal and external parameters of the binocular measurement unit 1 according to the center coordinates and three-dimensional coordinates of the second coded mark point combined with the camera imaging model, including: establish the mapping relationship between the world coordinates and the pixel coordinates by using the collinear condition equation of the camera imaging model, obtain the internal and external parameters of the binocular measurement unit 1 according to the mapping relationship, and the formula is as follows:

[0037] In the formula, is the camera image point X axis coordinates, is the camera image point Y axis coordinates, is the object side point in the camera coordinate system axis coordinates, is the camera internal parameter matrix, is the camera projection matrix, which is composed of a camera rotation matrix and a translation matrix.

[0038] S3, obtain the coordinates of all binocular measurement units 1 in the same reference coordinate system according to the internal and external parameters and the image of the vector nozzle with the first coded marker point, and obtain the coordinates of the unified coordinate system of all binocular measurement units 1. When a composite visual measurement unit is used, each binocular measurement unit 1 has its own local coordinate system, and the data is difficult to directly fuse and analyze. By using the internal and external parameters and the image with the coded marker point, the coordinates of all binocular measurement units 1 are unified to the same reference coordinate system, solving the problem of non-uniform coordinates in the multi-camera measurement system, and providing a unified reference framework for comprehensive analysis of the deformation of the vector nozzle. After unifying the coordinate system, the data measured by different binocular measurement units 1 has consistency and comparability. When analyzing the deformation of the vector nozzle, the deformation relationship between different key areas can be accurately judged, data errors and misunderstandings caused by coordinate system differences are avoided, and the accuracy and reliability of the deformation analysis are improved. In addition, the unified coordinate system makes subsequent data processing and analysis more convenient, improves the data processing efficiency, and reduces the difficulty and cost of data processing. Specifically as follows: S31, establish the world coordinate system of the corresponding binocular measurement unit 1 in the left camera coordinate system of each binocular measurement unit 1; S32, according to the image of the vector nozzle with the first coded marker point, obtain the center coordinates of the first coded marker point based on the edge detection algorithm and the iterative least squares fitting; S33, decode the first coded marker point in the image of the vector nozzle with the first coded marker point through affine transformation and gray scanning, obtain the coded ID, and number the center coordinates of the first coded marker point according to the coded ID, to obtain the number of the first coded marker point; S34, according to the internal and external parameters and the image of the vector nozzle with the first coded marker point, obtain the three-dimensional coordinates of the first coded marker point through the collinear condition equation, and the formula for obtaining the three-dimensional coordinates of the first coded marker point is as follows:

[0039]

[0040] In the formula, is the left camera image point X is the axis coordinate, is the left camera image point Y is the axis coordinate, is the right camera image point X is the axis coordinate, is the right camera image point Y is the axis coordinate, is the object point in the left camera coordinate system is the axis coordinate, is the object point z-axis coordinate in the right camera coordinate system, is the left camera internal parameter matrix, is a right camera internal parameter matrix, is a left camera projection matrix, is a right camera projection matrix; S35, according to the first coding mark point number and the three-dimensional coordinates of the first coding mark point, coordinates of all binocular measurement units 1 in the same reference coordinate system are obtained, and coordinates of the unified coordinate system of all binocular measurement units 1 are obtained, including: Taking the world coordinate system of one group of binocular measurement units 1 as the reference coordinate system, the world coordinate system of the remaining groups of binocular measurement units 1 is subjected to translation and rotation operation, and the world coordinate system of each binocular measurement unit 1 is transformed to the reference coordinate system, and the conversion formula is:

[0041] In the formula: is the x-axis coordinate of the reference world coordinate system, X is the y-axis coordinate of the reference world coordinate system, is the z-axis coordinate of the reference world coordinate system, Y is the x-axis coordinate of the world coordinate system of one group of the remaining binocular measurement units, is the y-axis coordinate of the world coordinate system of one group of the remaining binocular measurement units, Z is the z-axis coordinate of the world coordinate system of one group of the remaining binocular measurement units, is the x-axis coordinate of the world coordinate system of one group of the remaining binocular measurement units, X is the y-axis coordinate of the world coordinate system of one group of the remaining binocular measurement units, is the z-axis coordinate of the world coordinate system of one group of the remaining binocular measurement units, Y is the x-axis coordinate of the world coordinate system of one group of the remaining binocular measurement units, is the y-axis coordinate of the world coordinate system of one group of the remaining binocular measurement units, Z is the z-axis coordinate of the world coordinate system of one group of the remaining binocular measurement units, is the rotation matrix corresponding to the binocular measurement unit converted to the reference world coordinate system, is the translation matrix corresponding to the binocular measurement unit converted to the reference world coordinate system.

[0042] S4, according to the speckle image of the target area of the vector nozzle in the working state and the coordinates of the unified coordinate system of all binocular measurement units 1, the full-field deformation of all target areas of the vector nozzle is obtained. The present application can obtain the full-field deformation information of all target areas of the vector nozzle in combination with the speckle image in the working state, and comprehensively understand the deformation of the nozzle in the working process. In addition, when the binocular camera measurement system is repeatedly measured multiple times, the deformation of the nozzle will occur during the working process, and the cumulative error will be accumulated due to multiple measurement deformations. The present application obtains the full-field deformation through one measurement, avoids the cumulative error caused by multiple measurements, and improves the accuracy and reliability of the deformation measurement.

[0043] In the embodiment of the present application, the full-field deformation of all target areas of the vector nozzle is obtained according to the speckle image of the target area of the vector nozzle in the working state and the coordinates of the unified coordinate system of all binocular measurement units 1, including: S41, the speckle image of the target area of the vector nozzle in the working state is blocked and gray scale calculated by the digital image correlation method, and the center coordinates of the speckle image blocking sub-area are obtained; S42, referring to Figure 3 , the center coordinates of the speckle image are processed by relative orientation, absolute orientation, epipolar matching, three-dimensional reconstruction and beam adjustment algorithm, and the three-dimensional coordinates of the target area of the vector nozzle are obtained; S43, the three-dimensional coordinates of the target area of the vector nozzle are used to calculate the local deformation data of the target area of the vector nozzle, and the displacement and strain of the target area of the vector nozzle are obtained; S44, the displacement and strain measured by each binocular measurement unit 1 are unified to the reference coordinate system, and the full-field deformation of all target areas of the nozzle is obtained.

[0044] In the embodiment of the application, the image of the vector nozzle target area calibration board, the image of the vector nozzle with the first coded marker point and the speckle image of the target area of the vector nozzle in the working state are obtained by the same set of composite visual measurement unit, the composite visual measurement unit includes at least three groups of binocular measurement units 1, and the relative position of the binocular measurement unit 1 and the vector nozzle is unchanged during image acquisition; The method for acquiring the image of the vector nozzle target area calibration board is as follows: The calibration board is fixed on the target area of the vector nozzle, and the image of the vector nozzle target area calibration board is acquired by the binocular measurement unit 1; The method for acquiring the image of the vector nozzle with the first coded marker point is as follows: The first coded marker point is arranged around the vector nozzle, and the binocular measurement unit is arranged around the vector nozzle, and the image of the vector nozzle with the first coded marker point is acquired by the binocular measurement unit 1; The method for acquiring the speckle image of the target area of the vector nozzle in the working state is as follows: High-temperature-resistant speckle is sprayed on the target area of the vector nozzle, and the speckle image of the target area of the vector nozzle in different working states is acquired by the binocular measurement unit 1.

[0045] Referring to Figure 2 , in the embodiment of the application, the binocular measurement unit 1 is arranged around the periphery of the vector nozzle, the binocular measurement unit includes two cameras, the two cameras are connected by a cross beam, and all the cross beams of the binocular measurement units are connected by a tripod.

[0046] Based on the above method, the application further discloses a deformation measurement system of a composite visual measurement unit, referring to Figure 7 , comprising: The data acquisition module is configured to acquire images of a target area calibration plate of a vector nozzle collected by the plurality of binocular measurement units, images of the vector nozzle with first coded marker points, and speckle images of the target area of the vector nozzle in a working state; The internal and external parameter acquisition module is configured to acquire internal and external parameters of the binocular measurement unit 1 according to the images of the target area calibration plate of the vector nozzle. The binocular measurement unit coordinate system unification module is configured to acquire coordinates of all binocular measurement units 1 in the same reference coordinate system according to the internal and external parameters and the images of the vector nozzle with the first coded marker points, to obtain coordinates of a unified coordinate system of all binocular measurement units. The full-field deformation acquisition module is configured to acquire full-field deformations of all target areas of the vector nozzle according to the speckle images of the target area of the vector nozzle in the working state and the coordinates of the unified coordinate system of all binocular measurement units.

[0047] The various modules of the system of the present application cooperate with each other to comprehensively understand the deformation of the nozzle in the working process, and improve the accuracy and reliability of the deformation measurement.

[0048] The present application utilizes the digital image correlation method and the close-range photogrammetry technology to realize the coordinate system unification and the full-field deformation measurement. Compared with the traditional method, the number of measurements and the data processing steps are reduced, and the measurement efficiency is improved. At the same time, by accurately acquiring the internal and external parameters and the unified coordinate system, the measurement error is reduced, and accurate and comprehensive measurement of the deformation of each key area of the vector nozzle is realized.

[0049] Embodiment two: Referring to Figure 4 and Figure 6 , the present embodiment discloses a deformation measurement method of a composite visual binocular measurement unit, which can meet the requirements of coordinate system unification and deformation measurement of the composite binocular measurement unit, and comprises the following steps: S1: In the target area of the vector nozzle, high-temperature-resistant speckles are sprayed, the first coded marker points are placed around the vector nozzle, the binocular measurement unit 1 adopts a ring-encircling arrangement, multiple groups of binocular cameras are arranged, each group of binocular cameras is set as a binocular measurement unit 1, and the deformation measurement of the vector nozzle is performed, while ensuring that the subsequent steps can be normally performed. Specifically as follows: S11: In the target area of the vector nozzle, high-temperature-resistant speckles are sprayed, and the first coded marker points are placed around the vector nozzle; S12: Referring to Figure 2 , the two cameras of each binocular measurement unit 1 are connected by a rigid component, an existing cross beam frame is selected as the rigid connection component, and the two cameras are fixed on the cross beam frame to ensure that the relative spatial relationship does not change; wherein L1 is the left field boundary of the left camera of the binocular measurement unit; L2 is the right field boundary of the right camera of the binocular measurement unit.

[0050] S13: Fix each set of binocular measurement units 1 and crossbeam frame to the tripod. The binocular measurement units 1 are arranged in a ring around the two-dimensional vector nozzle, with one binocular measurement unit 1 corresponding to each target area.

[0051] S2: Using a marker point recognition and positioning algorithm and close-range photogrammetry technology, the intrinsic and extrinsic parameters of the binocular camera in each binocular measurement unit are calibrated using a calibration board; Preferably, step S2 specifically includes: S21: The image of the calibration plate placed in the target area of ​​the vector nozzle is acquired by the binocular measurement unit, and the scale of the calibration plate is known; S22: Acquire images of the calibration board through different binocular measurement units, obtain the center coordinates of the second coded marker point on the calibration board based on edge detection algorithm and iterative least squares fitting, decode the second coded marker point on the calibration board through affine transformation and grayscale scanning to obtain the coded ID, and number and record the center coordinates according to the coded ID; Preferably, step S22 specifically includes: The center coordinates of the second coded marker point are obtained by fitting the circle center using an iterative least squares fitting method, as shown in the following formula:

[0052]

[0053] In the formula, Edge points with the center of the ellipse as the origin X Axis coordinates Edge points with the center of the ellipse as the origin Y Axis coordinates These are edge points obtained from sub-pixel edge detection. X Axis coordinates These are edge points obtained from sub-pixel edge detection. Y Axis coordinates It is the center point of the ellipse during the iteration process. X Axis coordinates It is the center point of the ellipse during the iteration process. Y Axis coordinates It is the major axis of the ellipse. It is the minor axis of the ellipse. It is the major axis of the ellipse and X Angle between axes, This is the error term for ellipse fitting. It represents the number of edge coordinates.

[0054] S23: obtaining the three-dimensional coordinates of the second coded mark point through the scale of the calibration plate and the number of the second coded mark point, and substituting the center coordinates and the three-dimensional coordinates of the second coded mark point into the camera imaging model to solve the internal and external parameters of the binocular measurement unit.

[0055] Preferably, step S23 specifically comprises: mapping relationship between the three-dimensional coordinates and the center coordinates is established by using the collinear condition equation of the camera imaging model, and the internal and external parameters of the binocular measurement unit are solved by the least square method:

[0056] In the formula, is a camera image point X is an axis coordinate, is a camera image point Y is an axis coordinate, is an object point in the camera coordinate system is an axis coordinate, is a camera internal parameter matrix, is a camera projection matrix, which is composed of a camera rotation matrix and a translation matrix.

[0057] S3: establishing a world coordinate system of each binocular measurement unit and selecting a reference coordinate system, and realizing the coordinate system unification of all binocular measurement units by unifying the world coordinate system of each binocular measurement unit with the reference coordinate system; Preferably, step S3 specifically comprises: S31: acquiring the image of the vector jet with the first coded mark point by the binocular measurement unit, and establishing the world coordinate system of each binocular measurement unit by the left camera coordinate system of each binocular measurement unit; S32: based on the image of the vector jet with the first coded mark point, the center coordinates of the first coded mark point are obtained based on the edge detection algorithm and the iterative least square fitting, the first coded mark point is decoded through affine transformation and gray scanning to obtain the coded ID, the center coordinates are numbered and recorded according to the coded ID, and the three-dimensional coordinates of the first coded mark point are calculated through the collinear condition equation according to the internal and external parameters.

[0058] S33: unifying the world coordinate system of each binocular measurement unit with the reference world coordinate system by the number of the first coded mark point and the three-dimensional coordinates of the first coded mark point, and realizing the coordinate system unification of all binocular measurement units.

[0059] Preferably, step S32 specifically comprises: the three-dimensional coordinates of the point in the world coordinate system of the binocular measurement unit are solved by simultaneously solving the collinear condition equations of the left and right cameras;

[0060]

[0061] wherein, is the left camera image point X is the axis coordinate, is the left camera image point Y is the axis coordinate, is the right camera image point X is the axis coordinate, is the right camera image point Y is the axis coordinate, is the object point in the left camera coordinate system is the axis coordinate, is the object point z axis coordinate in the right camera coordinate system is the left camera intrinsic parameter matrix, is the right camera intrinsic parameter matrix, is the left camera projection matrix, is the right camera projection matrix.

[0062] Preferably, the step S33 specifically comprises: Referring to Figure 5 , a set of binocular measurement unit world coordinate systems is taken as a reference coordinate system, and translation and rotation operations are performed on the world coordinate systems of the remaining binocular measurement units to transform the world coordinate systems of the binocular measurement units to the reference coordinate system, and the conversion formula is:

[0063] wherein, is the in the reference world coordinate system X is the axis coordinate, is the in the reference world coordinate system Y is the axis coordinate, is the in the reference world coordinate system Z is the axis coordinate, is the in the world coordinate system of a set of the remaining binocular measurement units X is the axis coordinate, is the in the world coordinate system of a set of the remaining binocular measurement units Y is the axis coordinate, is the in the world coordinate system of a set of the remaining binocular measurement units Z is the axis coordinate, is the rotation matrix corresponding to the conversion of the binocular measurement unit to the reference world coordinate system, is the translation matrix corresponding to the conversion of the binocular measurement unit to the reference world coordinate system.

[0064] S4: collecting images of the target region of the vector nozzle in a working state, completing three-dimensional reconstruction of the target region of the vector nozzle by a digital image correlation method according to the images of the target region of the vector nozzle, obtaining displacement and strain of the target region of the vector nozzle, and unifying the displacement and strain measured by each binocular measurement unit to a reference coordinate system to obtain full-field deformation of all target regions of the vector nozzle.

[0065] Preferably, step S4 specifically comprises: S41: collecting speckle images of the target region of the vector nozzle in different working states; S42: completing three-dimensional reconstruction by matching through a digital image correlation method to obtain three-dimensional coordinates of the target region of the vector nozzle, calculating local deformation data of the target region of the vector nozzle by using the three-dimensional coordinates of the target region of the vector nozzle, and obtaining a local deformation field of the target region of the vector nozzle; S43: unifying the displacement and strain measured by each binocular measurement unit to the reference coordinate system to obtain full-field deformation of all target regions of the vector nozzle.

[0066] Preferably, step S42 specifically comprises: Referring to Figure 3 , the speckle images are blocked and gray scale calculation is performed through a digital image correlation method to obtain center coordinates, and accurate reconstruction of three-dimensional coordinates is realized through relative orientation (coplanar equation), absolute orientation (direct linear transformation solution), epipolar matching (epipolar geometry), three-dimensional reconstruction and bundle adjustment algorithm.

[0067] Compared with the prior art, the present application utilizes visual deformation measurement technology based on a digital image correlation method and close-range photogrammetry technology, obtains three-dimensional coordinates of the mark points through close-range photogrammetry technology, and then unifies local coordinate systems of each measurement unit to a reference global coordinate system by using the three-dimensional coordinates of the mark points, so that local deformation field measurement of the key regions is realized while unifying local measurement data of each key region to the global coordinate system, and the measurement demand in industry can be met.

[0068] The multi-camera group measurement unit system of the present application can realize synchronous measurement of local deformation fields of each key region while solving the problem of insufficient field of view. The method for unifying local measurement data proposed in the present application obtains a translation rotation matrix between each measurement unit through close-range photogrammetry technology, and can directly unify to the reference world coordinate system through matrix change when each measurement unit measures deformation of the key region.

[0069] The above content only illustrates the technical idea of the present application, and cannot limit the protection scope of the present application, and any modification made according to the technical idea of the present application on the basis of the technical solution falls within the protection scope of the present application.

Claims

1. A deformation measurement method for a composite vision measurement unit, the composite vision measurement unit comprising multiple binocular measurement units disposed around a vector nozzle, the vector nozzle being provided with a calibration plate, a first coded marker point, and speckle, characterized in that, Includes the following steps: Acquire images of the vector nozzle target area calibration plate, the vector nozzle with the first coded marker point, and the speckle image of the vector nozzle target area under working conditions, collected by multiple binocular measurement units; The intrinsic and extrinsic parameters of the binocular measurement unit are obtained from the image of the calibration plate of the target area of ​​the vector nozzle; Based on the internal and external parameters and the image of the vector nozzle with the first coded marker point, obtain the coordinates of all binocular measurement units in the same reference coordinate system, and obtain the coordinates of all binocular measurement units in a unified coordinate system; The full-field deformation of all target areas of the vector nozzle is obtained based on the speckle image of the target area under working conditions and the coordinates of all binocular measurement units in a unified coordinate system.

2. The deformation measurement method of a composite vision measurement unit according to claim 1, characterized in that, The method for acquiring the image of the vector nozzle target area calibration plate is as follows: The calibration plate is fixed in the target area of ​​the vector nozzle, and the image of the calibration plate in the target area of ​​the vector nozzle is acquired by the binocular measurement unit. The method for obtaining the vector nozzle image with the first coded marker point is as follows: The first coded marker points are arranged around the vector nozzle, and the binocular measurement unit is arranged around the periphery of the vector nozzle. The image of the vector nozzle with the first coded marker points is acquired by the binocular measurement unit. The specific method for obtaining the speckle image of the target area of ​​the vector nozzle under the working state is as follows: High-temperature resistant speckle coating is applied to the target area of ​​the vector nozzle, and speckle images of the target area under different operating conditions are acquired using a binocular measurement unit.

3. The deformation measurement method of a composite vision measurement unit according to claim 2, characterized in that, The binocular measurement unit includes two cameras, which are connected by a crossbeam frame. All crossbeam frames of the binocular measurement units are connected by a tripod.

4. The deformation measurement method of a composite vision measurement unit according to claim 1, characterized in that, The acquisition of intrinsic and extrinsic parameters of the binocular measurement unit based on the image of the calibration plate of the target area of ​​the vector nozzle is as follows: The calibration plate is provided with second coded marker points; Based on the image of the calibration plate in the target area of ​​the vector nozzle, the center coordinates of the second encoded marker point are obtained using an edge detection algorithm and iterative least squares fitting. The second coded marker point in the image of the calibration plate of the target area of ​​the vector nozzle is decoded by affine transformation and grayscale scanning to obtain the coded ID. The center coordinates of the second coded marker point are numbered according to the coded ID to obtain the number of the second coded marker point. The three-dimensional coordinates of the second coded marker point are obtained based on the image of the calibration plate of the vector nozzle target area, the scale of the calibration plate, and the number of the second coded marker point. The intrinsic and extrinsic parameters of the binocular measurement unit are obtained by combining the center coordinates and three-dimensional coordinates of the second coded marker with the camera imaging model.

5. The deformation measurement method of a composite vision measurement unit according to claim 4, characterized in that, The formula for obtaining the center coordinates of the second encoded marker point is as follows: In the formula, Edge points with the center of the ellipse as the origin X Axis coordinates Edge points with the center of the ellipse as the origin Y Axis coordinates These are edge points obtained from sub-pixel edge detection. X Axis coordinates These are edge points obtained from sub-pixel edge detection. Y Axis coordinates It is the center point of the ellipse during the iteration process. X Axis coordinates It is the center point of the ellipse during the iteration process. Y Axis coordinates It is the major axis of the ellipse. It is the minor axis of the ellipse. It is the major axis of the ellipse and X Angle between axes, This is the error term for ellipse fitting. It represents the number of edge coordinates.

6. The deformation measurement method of a composite vision measurement unit according to claim 4, characterized in that, The process of obtaining the intrinsic and extrinsic parameters of the binocular measurement unit based on the center coordinates and three-dimensional coordinates of the second coded marker point combined with the camera imaging model includes: The collinearity condition equation of the camera imaging model is used to establish the mapping relationship between world coordinates and pixel coordinates. Based on the mapping relationship, the intrinsic and extrinsic parameters of the binocular measurement unit are obtained, and the formulas are as follows: In the formula, For camera image points X Axis coordinates For camera image points Y Axis coordinates Object point in camera coordinate system Axis coordinates The camera intrinsic parameter matrix, The camera projection matrix consists of the camera rotation matrix and translation matrix.

7. The deformation measurement method of a composite vision measurement unit according to claim 1, characterized in that, The coordinates of all binocular measurement units in the same reference coordinate system are obtained from the image of the vector nozzle with the first coded marker point based on the internal and external parameters, and the coordinates of all binocular measurement units in a unified coordinate system are obtained as follows: Establish the world coordinate system of each binocular measurement unit using the left camera coordinate system of each binocular measurement unit; Based on the image of the vector nozzle with the first coded marker point, the center coordinates of the first coded marker point are obtained using an edge detection algorithm and iterative least squares fitting. The first coded marker in the image of the vector nozzle with the first coded marker is decoded by affine transformation and grayscale scanning to obtain the coded ID. The center coordinates of the first coded marker are numbered according to the coded ID to obtain the number of the first coded marker. Based on the internal and external parameters and the image of the vector nozzle with the first coded marker, the three-dimensional coordinates of the first coded marker are obtained through the collinearity condition equation. Based on the number and three-dimensional coordinates of the first coded marker, the coordinates of all binocular measurement units in the same reference coordinate system are obtained, thus obtaining the coordinates of all binocular measurement units in a unified coordinate system.

8. The deformation measurement method of a composite vision measurement unit according to claim 7, characterized in that, The formula for obtaining the three-dimensional coordinates of the first coded marker point is as follows: In the formula, Left camera image point X Axis coordinates Left camera image point Y Axis coordinates For the right camera image point X Axis coordinates For the right camera image point Y Axis coordinates Object point in the left camera coordinate system Axis coordinates The z-axis coordinates of the object point in the right camera coordinate system are: The intrinsic parameter matrix of the left camera. The intrinsic parameter matrix of the right camera. For the left camera projection matrix, The projection matrix of the right camera; The step of obtaining the coordinates of all binocular measurement units in the same reference coordinate system based on the number and three-dimensional coordinates of the first coded marker point, and thus obtaining the coordinates of all binocular measurement units in a unified coordinate system, includes: Using the world coordinate system of one set of binocular measurement units as the reference coordinate system, translation and rotation operations are performed on the world coordinate systems of the remaining sets of binocular measurement units to transform the world coordinate systems of each binocular measurement unit to the reference coordinate system. The transformation formula is as follows: In the formula: For the reference world coordinate system X Axis coordinates For the reference world coordinate system Y Axis coordinates For the reference world coordinate system Z Axis coordinates For the remaining binocular measurement units, a set of world coordinates X Axis coordinates For the remaining binocular measurement units, a set of world coordinates Y Axis coordinates For the remaining binocular measurement units, a set of world coordinates Z Axis coordinates The rotation matrix is ​​used to transform the binocular measurement unit to the corresponding reference world coordinate system. This is the translation matrix for transforming the binocular measurement unit to the reference world coordinate system.

9. The deformation measurement method of a composite vision measurement unit according to claim 1, characterized in that, The process of obtaining the full-field deformation of all target areas of the vector nozzle based on the speckle image of the target area under working conditions and the coordinates of all binocular measurement units in a unified coordinate system includes: The speckle image of the target area of ​​the vector nozzle under working conditions is divided into blocks and grayscale is calculated by digital image correlation method to obtain the center coordinates of the sub-blocks of the speckle image. The center coordinates of the speckle image are processed by relative orientation, absolute orientation, epipolar matching, 3D reconstruction and beam adjustment algorithms to obtain the 3D coordinates of the target area of ​​the vector nozzle. The local deformation data of the vector nozzle target area is calculated using the three-dimensional coordinates of the target area, and the displacement and strain of the vector nozzle target area are obtained. The displacements and strains measured by each binocular measurement unit are unified to the reference coordinate system to obtain the full-field deformation of all target areas of the nozzle.

10. A deformation measurement system for a composite vision measurement unit, characterized in that, include: The data acquisition module is used to acquire images of the vector nozzle target area calibration plate, the vector nozzle with the first coded marker point, and the speckle image of the vector nozzle target area under working conditions, collected by multiple binocular measurement units. The intrinsic and extrinsic parameter acquisition module is used to acquire the intrinsic and extrinsic parameters of the binocular measurement unit based on the image of the calibration plate of the target area of ​​the vector nozzle; The binocular measurement unit coordinate system module is used to obtain the coordinates of all binocular measurement units in the same reference coordinate system based on the internal and external parameters and the image of the vector nozzle with the first coded marker point, so as to obtain the coordinates of all binocular measurement units in a unified coordinate system. The full-field deformation acquisition module is used to acquire the full-field deformation of all target areas of the vector nozzle based on the speckle image of the target area of ​​the vector nozzle under working conditions and the coordinates of the unified coordinate system of all binocular measurement units.

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