Three-dimensional deformation measurement method, device, equipment, medium and product

Abstract

The application provides a three-dimensional deformation measurement method, device, equipment, medium and product. Projected fringes generated by a projector projecting to a reference plane are parallel to each other, and an optical axis of a camera is perpendicular to the reference plane. The method comprises the following steps: acquiring geometric relationship parameters among the projector, the camera and the reference plane, projected fringe data on the reference plane and a fringe image corresponding to a measured object; the fringe image is generated by the camera shooting projected fringes on a surface of the measured object; inputting the projected fringe data, the geometric relationship parameters and the fringe image into a preset optical path measurement model, reconstructing three-dimensional topographic data of the measured object; and outputting three-dimensional topography of the measured object according to the three-dimensional topographic data. The three-dimensional deformation measurement method simplifies the spatial geometric constraint condition of a measurement optical path and reduces the adjustment difficulty of the measurement optical path. The method is not only suitable for long-distance measurement, but also suitable for large field of view and short-distance measurement, and has a wide application prospect.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of deformation measurement, and in particular to a three-dimensional deformation measurement method, device, equipment, medium and product. BACKGROUND

[0002] Deformation measurement can observe the shape, size and position changes of a deformed body under the action of load, and has important significance for the shape parameter measurement and structure quality monitoring of civil buildings, mechanical structures and the like. In the field of aviation, the wing as a key component of the aircraft directly affects the aerodynamic, control and safety performance of the aircraft, and is the focus of attention in aircraft design. Due to the characteristics of large deformation, small amplitude and strong three-dimensionality of the wing deformation, higher requirements are put forward for deformation measurement, and a large-range, high-resolution three-dimensional deformation measurement technology needs to be developed.

[0003] Fourier transform profilometry (FTP) in three-dimensional deformation measurement technology is a monocular vision topography measurement technology based on grating projection, which reconstructs three-dimensional topography from the fringe phase carrying deformation information through Fourier transform and frequency domain filtering. This technology has the advantages of recovering three-dimensional topography from a single image, non-contact and not changing the surface characteristics of the model, and has great development potential. The traditional FTP measurement light path needs to meet strict geometric relationships, including the coplanar of the camera optical axis and the projector optical axis, the parallel of the line connecting the optical centers and the reference plane, and the infinite distance of the camera position from the measured plane.

[0004] However, in the actual measurement process, the positions of the camera and the projector optical axis are difficult to adjust, and it is difficult to simultaneously satisfy the requirements of the coplanar of the two optical axes, the parallel of the line connecting the optical centers and the reference plane, and the infinite distance of the camera position, resulting in high difficulty and poor effect of three-dimensional deformation measurement. SUMMARY

[0005] The present application provides a three-dimensional deformation measurement method, device, equipment, medium and product to solve the problem of high difficulty and poor effect of three-dimensional deformation measurement caused by strong spatial geometric constraints and great adjustment difficulty of the three-dimensional deformation measurement light path.

[0006] The first aspect of the present application provides a three-dimensional deformation measurement method, and the projection fringes generated by the projector projecting to the reference plane are parallel to each other, and the camera optical axis is perpendicular to the reference plane. The method comprises:

[0007] Obtaining the geometric relationship parameters between the projector, the camera and the reference plane, the projection fringe data on the reference plane and the corresponding fringe image of the measured object; the fringe image is generated by the camera shooting the projection fringe on the surface of the measured object;

[0008] input the projection fringe data, the geometric relationship parameters and the fringe image into a preset optical path measurement model, and reconstruct three-dimensional topographic data of the measured object;

[0009] output three-dimensional topography of the measured object according to the three-dimensional topographic data.

[0010] Further, the method described above, the geometric relationship parameters among the projector, the camera and the reference plane are obtained, comprising:

[0011] a point of intersection between the optical axis of the projector and the reference plane is taken as a coordinate origin, and a reference coordinate system is established based on the reference plane; an x-axis of the reference coordinate system is perpendicular to a projection fringe direction of the reference plane, a y-axis is parallel to the projection fringe direction of the reference plane, and a z-axis is perpendicular to the reference plane;

[0012] position information of the projector and the camera in the reference coordinate system is obtained;

[0013] the geometric relationship parameters among the projector, the camera and the reference plane are determined according to the position information of the projector and the position information of the camera.

[0014] Further, the method described above, the geometric relationship parameters comprise the following parameters:

[0015] an angle between the optical axis of the projector and the z-axis of the reference coordinate system;

[0016] a distance from the optical center of the projector to the coordinate origin, a distance from the optical center of the camera to the reference plane, and a spatial distance between the optical center of the projector and the optical center of the camera;

[0017] an angle between a projection of a line connecting the optical center of the projector and the optical center of the camera in a vertical plane and a positive direction of the x-axis of the reference coordinate system; the vertical plane is a plane perpendicular to the reference plane and parallel to the x-axis;

[0018] an angle between the line connecting the optical center of the projector and the optical center of the camera and a plane in which the optical axis of the projector lies; the plane in which the optical axis of the projector lies comprises the x-axis and the z-axis of the reference coordinate system.

[0019] Further, the method described above, the preset optical path measurement model comprises a fringe gray scale distribution algorithm and an explicit mapping algorithm between fringe phase difference and deformation along the z direction;

[0020] the input of the projection fringe data, the geometric relationship parameters and the fringe image into the preset optical path measurement model, and the reconstruction of the three-dimensional topographic data of the measured object, comprising:

[0021] for each position on the surface of the measured object in the fringe image, the following processing is performed:

[0022] determining the fringe gray scale at the target position and the reference position according to the projected fringe data at the reference position in the reference plane and the fringe data at the target position in the fringe image; the pixel positions at the reference position and the target position are the same;

[0023] inputting the fringe gray scale and the geometric relationship parameter into a fringe gray scale distribution algorithm to determine the fringe phase difference between the target position and the reference position;

[0024] inputting the fringe phase difference and the geometric relationship parameter into the explicit mapping algorithm to determine the z coordinate value at the target position;

[0025] generating the three-dimensional topography data of the measured object according to the three-dimensional coordinates at each position on the surface of the measured object.

[0026] The second aspect of the present application provides a three-dimensional deformation measurement device, the projected fringes generated by the projector projecting to the reference plane are parallel to each other, and the optical axis of the camera is perpendicular to the reference plane, and the device comprises:

[0027] an acquisition module configured to acquire the geometric relationship parameter between the projector, the camera and the reference plane, the projected fringe data on the reference plane and the fringe image corresponding to the measured object; the fringe image is generated by the camera shooting the projected fringes on the surface of the measured object;

[0028] a reconstruction module configured to input the projected fringe data, the geometric relationship parameter and the fringe image into a preset optical path measurement model to reconstruct the three-dimensional topography data of the measured object;

[0029] an output module configured to output the three-dimensional topography of the measured object according to the three-dimensional topography data.

[0030] Further, the device as described above, the acquisition module, when acquiring the geometric relationship parameter between the projector, the camera and the reference plane, is specifically configured to:

[0031] taking the intersection point between the optical axis of the projector and the reference plane as the coordinate origin, establishing a reference coordinate system based on the reference plane; the x axis of the reference coordinate system is perpendicular to the projected fringe direction of the reference plane, the y axis is parallel to the projected fringe direction of the reference plane, and the z axis is perpendicular to the reference plane; acquiring the position information of the projector and the camera in the reference coordinate system; determining the geometric relationship parameter between the projector, the camera and the reference plane according to the position information of the projector and the position information of the camera.

[0032] Further, the device as described above, the geometric relationship parameter comprises the following parameters:

[0033] the included angle between the optical axis of the projector and the z axis of the reference coordinate system;

[0034] a distance from a projector optical center to a coordinate origin, a distance from a camera optical center to a reference plane, and a spatial distance between the projector optical center and the camera optical center;

[0035] an angle between a projection of a line connecting the projector optical center and the camera optical center in a vertical plane and a positive direction of an x-axis of a reference coordinate system, the vertical plane being perpendicular to the reference plane and parallel to the x-axis;

[0036] an angle between the line connecting the projector optical center and the camera optical center and a plane in which a projector optical axis lies, the plane including the x-axis and a z-axis of the reference coordinate system.

[0037] Further, the apparatus as described above, the preset optical path measurement model includes a fringe gray scale distribution algorithm and an explicit mapping algorithm between a fringe phase difference and a deformation amount along a z direction;

[0038] The reconstruction module is specifically configured to:

[0039] For each position of the surface of the measured object in the fringe image, the following processing is performed:

[0040] determine a fringe gray scale at the target position relative to the reference position according to projection fringe data at a reference position in the reference plane and fringe data at the target position in the fringe image, the pixel positions of the reference position and the target position being the same, input the fringe gray scale and geometric relationship parameters into the fringe gray scale distribution algorithm to determine a fringe phase difference between the target position and the reference position, and input the fringe phase difference and the geometric relationship parameters into the explicit mapping algorithm to determine a z coordinate value at the target position;

[0041] generate three-dimensional topographic data of the measured object according to the three-dimensional coordinates of each position of the surface of the measured object.

[0042] The third aspect of the present application provides an electronic device, comprising a memory and a processor;

[0043] The memory stores computer execution instructions;

[0044] The processor executes the computer execution instructions stored in the memory to implement the three-dimensional deformation measurement method according to any one of the first aspect.

[0045] The fourth aspect of the present application provides a computer readable storage medium, the computer readable storage medium stores computer execution instructions, and the computer execution instructions are executed by a processor to implement the three-dimensional deformation measurement method according to any one of the first aspect.

[0046] The fifth aspect of the present application provides a computer program product comprising a computer program which, when executed by a processor, implements the three-dimensional deformation measurement method of any one of the first aspect.

[0047] The three-dimensional deformation measurement method, device, equipment, medium and product provided by the present application, the projection stripes generated by the projector projecting to the reference plane are parallel to each other, and the camera optical axis is perpendicular to the reference plane. The method comprises the following steps: acquiring the geometric relationship parameters between the projector, the camera and the reference plane, the projection stripe data on the reference plane and the corresponding stripe image of the measured object; the stripe image is generated by the camera shooting the projection stripe on the surface of the measured object; inputting the projection stripe data, the geometric relationship parameters and the stripe image into a preset optical path measurement model, reconstructing the three-dimensional topographic data of the measured object; and outputting the three-dimensional topography of the measured object according to the three-dimensional topographic data. The three-dimensional deformation measurement method of the present application does not require the measurement optical path projection optical axis to be directly opposite to the reference plane, but only requires the projection stripes in the reference plane to be parallel to each other. In terms of camera arrangement, the camera optical center can be arranged arbitrarily, only requiring the camera optical axis to be perpendicular to the reference plane, not requiring the camera optical axis to be coplanar with the projection optical axis, and not requiring the line connecting the optical centers of the two to be parallel to the reference plane. Since the measurement optical path does not make the assumption of telecentric optical path in the derivation, the optical path is suitable not only for long-distance measurement, but also for large field of view and short-distance measurement. The measurement method simplifies the geometric constraint conditions of the measurement optical path space, reduces the adjustment difficulty of the measurement optical path, and enhances the applicability and effect of three-dimensional deformation measurement. BRIEF DESCRIPTION OF DRAWINGS

[0048] The accompanying drawings, which are incorporated into and form a part of the specification, illustrate embodiments consistent with the present application and, together with the description, serve to explain the principles of the application.

[0049] Figure 1 A scene diagram of the three-dimensional deformation measurement method according to the embodiments of the present application;

[0050] Figure 2 A flowchart of the three-dimensional deformation measurement method provided by the present application Figure 1 ;

[0051] Figure 3 A flowchart of the three-dimensional deformation measurement method provided by the present application Figure 2 ;

[0052] Figure 4 A measurement geometry diagram of the three-dimensional deformation measurement method provided by the present application Figure 1 ;

[0053] Figure 2 A measurement geometry diagram of the three-dimensional deformation measurement method provided by the present application Figure 6 ;

[0054] Figure 7 A structural schematic diagram of a three-dimensional deformation measurement device provided in the present application is shown in the following figure.

[0055] Figure 1 A structural schematic diagram of an electronic device provided in the present application is shown in the following figure.

[0056] The specific embodiments of the present application have been shown in the above figures, and will be described in more detail hereinafter. These figures and the written description are not intended to limit the scope of the present application in any way, but to illustrate the present application to those skilled in the art by referring to specific embodiments. DETAILED DESCRIPTION

[0057] The exemplary embodiments will be described in detail herein with reference to the attached drawings. The same or similar components are denoted by the same reference numerals throughout the drawings and the following description, unless otherwise specified. The embodiments described in the following exemplary embodiments do not represent all the embodiments consistent with the present application. Rather, they are merely examples of apparatus and methods consistent with some aspects of the present application as detailed in the appended claims.

[0058] The technical solutions of the present application will be described in detail below with specific embodiments. The following specific embodiments can be combined with each other, and the same or similar concepts or processes may not be described again in some embodiments. The embodiments of the present application will be described below with reference to the accompanying drawings.

[0059] In order to clearly understand the technical solutions of the present application, the prior art solutions will be described in detail first. As a key component of an aircraft, the deformation characteristics of the wing directly affect the aerodynamic, control and safety performance of the aircraft, and are the focus of attention in aircraft design. Due to the characteristics of large deformation, small amplitude and strong three-dimensionality of the wing deformation, higher requirements are put forward for deformation measurement, and a large range, high resolution three-dimensional deformation measurement technology needs to be developed.

[0060] Currently, the non-contact deformation measurement techniques for wings are divided into point deformation measurement, line deformation measurement and three-dimensional deformation measurement. The mainstream point deformation measurement device is a laser vibration meter, which is a deformation dynamic measurement method based on the laser Doppler effect, and has the characteristics of fast frequency response and high precision. The measurement frequency of this method can reach the order of megahertz, and the displacement resolution is usually in the order of nanometers, but since only a single point in a specified direction can be measured, this method is mainly used for measuring the deformation of key positions such as wing tips, leading and trailing edges. Currently, the mainstream line deformation measurement technique is shape shooting technology, which irradiates a certain two-dimensional section of the wing with a laser sheet and takes a picture with a camera to calculate and analyze the wing deformation and vibration on this section. This measurement technique only includes a laser sheet and a camera, and can be easily synchronized with flow field measurement techniques, and has been widely used in fluid-structure coupling measurement.

[0061] Three-dimensional deformation measurement technology can directly measure the three-dimensional deformation of a three-dimensional wing and the three-dimensional deformation characteristics of a two-dimensional model. The existing Fourier transform profilometry is a monocular vision topography measurement technology based on grating projection, which reconstructs the three-dimensional topography from the stripe phase carrying deformation information through Fourier transform and frequency domain filtering. This technology has the advantages of restoring three-dimensional topography from a single image, being non-contact and not changing the surface characteristics of the model, and has great development potential.

[0062] However, Fourier transform profilometry needs to meet strict optical geometry relationships, including that the camera optical axis and the projector optical axis are coplanar, the line connecting the optical centers of the two is parallel to the reference plane, and the distance between the camera and the measured plane is much greater than the characteristic length of the measured region. In actual measurement process, the camera and projector optical axes cannot be directly observed, and the spatial position adjustment is difficult, and it is difficult to simultaneously satisfy the requirements of coplanar two optical axes and parallel line connecting optical centers and reference plane. At the same time, due to the limitation of measurement experimental site, the camera position often cannot meet the requirement of infinite distance, and three-dimensional deformation measurement is difficult and the effect is poor.

[0063] Therefore, in order to solve the problems of difficult adjustment of the positions of the camera and the projector in the prior art, difficulty in simultaneously satisfying the requirements of coplanar two optical axes, parallel line connecting optical centers and reference plane, and infinite distance of the camera, the inventors found in research that the spatial geometric constraint conditions of the measurement optical path can be simplified, a new measurement optical path model is established, the spatial stripe distribution rule is derived, and an explicit mapping relationship between height and phase is given, thereby reducing the difficulty of three-dimensional deformation measurement and improving the applicability of the measurement method.

[0064] Specifically, the process involves acquiring the geometric relationship parameters between the projector, camera, and reference plane, the projected fringe data on the reference plane, and the fringe image corresponding to the object under test. The fringe image is generated by the camera capturing projected fringes on the surface of the object under test. The projected fringe data, geometric relationship parameters, and fringe image are input into a preset optical path measurement model to reconstruct the three-dimensional shape data of the object under test. Based on the three-dimensional shape data, the three-dimensional shape of the object under test is output.

[0065] Based on the above-mentioned inventive discovery, the inventor has proposed the technical solution of this application.

[0066] The following describes the application scenarios of the three-dimensional deformation measurement method provided in the embodiments of this application. For example... Figure 2 As shown, 1 represents an electronic device, 2 represents a projector, 3 represents a camera, 4 represents the surface of the object being measured, and 5 represents a reference plane. The projection fringes (not shown in the figure) generated by the projector 2 projecting onto the reference plane 5 are parallel to each other. The optical axis of the camera 3 is represented by a dashed line and is perpendicular to the reference plane 5. The reference plane 5 is represented by a straight line. If the intersection of the optical axis of the projector 2 (represented by the dashed line in the figure) and the reference plane 5 is taken as the origin, and the projection of the optical axis of the projector 2 onto the reference plane is taken as the x-axis, and the z-axis is perpendicular to the reference plane 5, then each point on the reference plane 5 has a corresponding x-value and y-value, and the z-value is 0.

[0067] During 3D deformation measurement, projector 2 projects light onto the surface 4 of the object under test, causing projected fringes to appear on the surface 4. Camera 3 captures an image of the fringe on the surface 4. Electronic device 1 acquires the geometric relationship parameters between the projector, camera, and reference plane, the projected fringe data on the reference plane, and the corresponding fringe image of the object under test. It then inputs the projected fringe data, geometric relationship parameters, and fringe image into a preset optical path measurement model to reconstruct the 3D topography data of the object under test. The preset optical path measurement model is generated after determining the spatial fringe distribution pattern and the explicit height-phase mapping relationship. Electronic device 1 outputs the 3D topography of the object under test based on the 3D topography data.

[0068] The embodiments of this application are described below with reference to the accompanying drawings.

[0069] Figure 1 Flowchart of the three-dimensional deformation measurement method provided in this application Figure 2 .like Figure 3 As shown, in this embodiment, the execution subject of this application embodiment is a three-dimensional deformation measurement device, which can be integrated into an electronic device. The three-dimensional deformation measurement method provided in this embodiment includes the following steps:

[0070] Step S101, obtain the geometric relationship parameters among the projector, the camera and the reference plane, the projection fringe data on the reference plane and the fringe image corresponding to the measured object. The fringe image is generated by the camera shooting the projection fringe on the surface of the measured object.

[0071] In this embodiment, the reference plane can be set in advance, and the set reference plane can be in the lower layer of the surface of the measured object. Since the positions of the projector and the camera and the reference plane are all set in advance, the geometric relationship parameters among the projector, the camera and the reference plane and the projection fringe data on the reference plane can be determined by algorithm calculation.

[0072] In this embodiment, the projection fringes generated by the projector projecting to the reference plane are required to be parallel to each other, but the optical axis of the projector can be inclined to the reference plane. Meanwhile, the optical axis of the camera is required to be perpendicular to the reference plane, but the optical center can be arranged arbitrarily. The projector can adopt a sinusoidal grating projection.

[0073] Generally, the projector projects the structured light fringe onto the surface of the measured object, the camera samples the fringe image, and the three-dimensional morphology of the measured object is reconstructed by comparing the difference between the three-dimensional surface of the measured object and the fringe distribution of the reference plane.

[0074] Step S102, input the projection fringe data, the geometric relationship parameters and the fringe image into a preset optical path measurement model to reconstruct the three-dimensional morphology data of the measured object.

[0075] In this embodiment, the preset optical path measurement model includes a fringe gray scale distribution algorithm and an explicit mapping algorithm obtained after derivation. The fringe gray scale distribution algorithm mainly reflects the spatial distribution law of the fringe, and the explicit mapping algorithm mainly reflects the relationship between the fringe phase difference and the height. The three-dimensional morphology data of the measured object, i.e., the three-dimensional data of each point of the measured object, can be reconstructed by the preset optical path measurement model.

[0076] Step S103, output the three-dimensional morphology of the measured object according to the three-dimensional morphology data.

[0077] After the three-dimensional morphology data of the measured object is determined, the three-dimensional morphology of the measured object can be directly outputted.

[0078] The three-dimensional deformation measurement method provided in the embodiment of the present application includes: obtaining the geometric relationship parameters among the projector, the camera and the reference plane, the projection fringe data on the reference plane and the fringe image corresponding to the measured object. The fringe image is generated by the camera shooting the projection fringe on the surface of the measured object. The projection fringe data, the geometric relationship parameters and the fringe image are inputted into a preset optical path measurement model to reconstruct the three-dimensional morphology data of the measured object. The three-dimensional morphology of the measured object is outputted according to the three-dimensional morphology data.

[0079] The three-dimensional deformation measurement method of the present application does not require the projection light axis of the measurement light path to be perpendicular to the reference plane, only requires the projection fringes in the reference plane to be parallel to each other. In terms of camera arrangement, the camera optical center can be arranged arbitrarily, only requires the camera optical axis to be perpendicular to the reference plane, does not require the camera optical axis to be coplanar with the projection optical axis, and the line connecting the optical centers of the two does not need to be parallel to the reference plane. Thus, the geometric constraint conditions of the measurement light path space are simplified, the difficulty of three-dimensional deformation measurement is reduced, and the applicability of the measurement method is improved.

[0080] Figure 2 Flowchart of the three-dimensional deformation measurement method provided by the present application Figure 3 As shown in Figure 4 , the three-dimensional deformation measurement method provided by the present embodiment is further refined on the basis of the three-dimensional deformation measurement method provided by the previous embodiment of the present application. Therefore, the three-dimensional deformation measurement method provided by the present embodiment includes the following steps.

[0081] Step S201: Establishing a reference coordinate system based on the reference plane with the point of intersection between the projection optical axis and the reference plane as the coordinate origin. The x-axis of the reference coordinate system is perpendicular to the projection fringe direction of the reference plane, the y-axis is parallel to the projection fringe direction of the reference plane, and the z-axis is perpendicular to the reference plane.

[0082] In the present embodiment, as shown in Figure 4 , the projection optical axis P1O1 intersects the reference plane at the O1 point, which is the coordinate origin, and the xyz direction of the established reference coordinate system is shown in the lower right corner of the figure.

[0083] Step S202: Obtaining the position information of the projector and the camera in the reference coordinate system.

[0084] In the present embodiment, the position information of the projector can include the position of the projector optical center, the information of the projector optical axis, etc., and the position information of the camera can include the position of the camera optical center, the information of the camera optical axis, etc.

[0085] Step S203: Determining the geometric relationship parameters between the projector, the camera and the reference plane according to the position information of the projector and the position information of the camera.

[0086] Optionally, in the present embodiment, the geometric relationship parameters include the following parameters:

[0087] The included angle between the projection optical axis and the z-axis of the reference coordinate system, which can reflect the inclination angle of the projection optical axis. If there is no inclination, the projection optical axis is perpendicular to the reference plane.

[0088] The distance from the projector optical center to the coordinate origin, the distance from the camera optical center to the reference plane, and the spatial distance between the projector optical center and the camera optical center.

[0089] An angle between a projection of a line connecting a projector optical center and a camera optical center in a vertical plane and a positive direction of an x-axis of a reference coordinate system. The vertical plane is a plane perpendicular to a reference plane and parallel to the x-axis. As shown in FIG. 1, the line connecting the projector optical center and the camera optical center is P1P2, the vertical plane is P1'GO1'O2', and the angle is a. Figure 4

[0090] An angle between a line connecting a projector optical center and a camera optical center and a plane in which a projector optical axis lies. The plane in which the projector optical axis lies includes an x-axis and a z-axis of a reference coordinate system. As shown in FIG. 2, the plane in which the projector optical axis lies is P1P2"O2"O1, and the angle is b. Figure 4

[0091] Step S204, acquiring the projection fringe data on the reference plane and the fringe image corresponding to the measured object.

[0092] The implementation of step 204 is similar to that of step 101 of the previous embodiment, and will not be repeated here.

[0093] It should be noted that the preset optical path measurement model includes a fringe gray scale distribution algorithm and an explicit mapping algorithm between fringe phase difference and deformation along the z direction.

[0094] Step S205, for each position on the surface of the measured object in the fringe image, the following processing is performed (steps S206-S208):

[0095] Step S206, determining the fringe gray scale at the target position and the reference position according to the projection fringe data at the reference position in the reference plane and the fringe data at the target position in the fringe image. The pixel positions at the reference position and the target position are the same.

[0096] Step S207, inputting the fringe gray scale and the geometric relationship parameter into the fringe gray scale distribution algorithm to determine the fringe phase difference between the target position and the reference position.

[0097] Step S208, inputting the fringe phase difference and the geometric relationship parameter into the explicit mapping algorithm to determine the z coordinate value at the target position.

[0098] Step S209, generating three-dimensional topographic data of the measured object according to the three-dimensional coordinates of each position on the surface of the measured object.

[0099] The implementation of step 209 is similar to that of step 102 of the previous embodiment, and will not be repeated here.

[0100] Step S210, outputting the three-dimensional topography of the measured object according to the three-dimensional topographic data.

[0101] ​​The implementation of step 210 is similar to that of step 103 in the previous embodiment, and will not be described in detail here.

[0102] In this embodiment, as Figure 4 As shown in the figure, the solid lines are in plane P1'O1'O2', the long dashed lines are in plane P1P2"O2, and the remaining spatial lines are represented by short dashed lines. P1O1 is the projector optical axis, which makes an angle θ with the vertical direction. P2O2 is the camera optical axis, which is perpendicular to the reference plane and intersects at point O2. Figure 4 The plane containing the projector's optical axis is defined as the xz plane, with the origin of the coordinate system located at point O1 within the reference plane. The x-direction is perpendicular to the direction of the projected fringes, the y-direction is parallel to the direction of the projected fringes, and the z-direction is perpendicular to the reference plane.

[0103] For a sinusoidal projection grating, when the projector's optical axis is perpendicular to the projected plane, the spacing of the projected fringes is equal. However, for... Figure 4 In the projection method described, the projector's optical axis has a tilt angle θ, and the spacing of the projected fringes in the reference plane varies with the x-coordinate position. To deduce the distribution pattern of the projected fringes in the reference plane... Figure 5 The diagram provides a partial schematic of the projection optical path, where O1A1 is the reference plane and O1N is perpendicular to the projector's optical axis P1O1. The projection fringes are evenly spaced within O1N, and their spatial frequency is assumed to be f. Without loss of generality, a point A1 is arbitrarily chosen within the reference plane, and the projection ray P1A1 intersects O1N at point A1'. Since points A1 and A1' lie on the same projection ray, the phase of the sinusoidal fringe at point A1 is the same as that at point A1', i.e., the phase of the sinusoidal fringe is... Considering that the two triangles △A1A1'N and △PA1'O1 are similar, the phase of the sinusoidal fringe at A1 can be obtained as follows:

[0104]

[0105] Among them, L p Let f be the distance from the optical center P1 of the projector to the reference plane O1, and f be the spatial frequency.

[0106] Furthermore, when the aforementioned sinusoidal fringes are projected onto the reference plane, the fringe grayscale distribution is as follows:

[0107]

[0108] Where I0 is twice the brightness amplitude of the sinusoidal fringe.

[0109] When the fringes are projected onto the three-dimensional surface of the object being measured, the grayscale distribution of the fringes can be obtained:

[0110]

[0111] Ψ is the fringe phase difference caused by three-dimensional topography modulation.

[0112] Now Figure 4 Take any point B on the surface of the measured object as an example, and derive the mapping relationship between the fringe phase difference Ψ(B) and the deformation amount of point B along the z direction. As Figure 4 shown, P1B is the projection light corresponding to point B, and the extension of P1B intersects the reference plane at point A, that is, the fringe phase at point A is the same as that at point B. P2B is the camera incident light corresponding to point B, and the extension of P2B intersects the reference plane at point C, that is, when the reference fringe is photographed, the fringe phase observed by the pixel point corresponding to point B is the fringe phase at point C. Therefore, for the pixel point corresponding to point B, the phase difference Ψ(B) is equivalent to the phase difference between points A and C in the reference plane.

[0113] For convenience of derivation, the camera optical axis P2O2 is translated along the negative direction of the y axis to y=0 and y=y B , that is, O2"P2" and O2'P2', and the projection optical axis is translated along the y direction to y=y B , that is, P1'O1'. Connect and extend P2'B to intersect O1'O2' at C', and connect and extend P1'B to intersect O1'O2' at A'. It can be proved that CC' and AA' are parallel to the positive direction of the y axis, that is, the phase at point C is the same as that at point C', and the phase at point A is the same as that at point A'. The phase difference Ψ is further equivalent to the phase difference between points A' and C' in the reference plane, that is,

[0114] Ψ(x)=Φ(x B )-Φ(x C )=Φ(x A' )-Φ(x C' )

[0115] Since

[0116]

[0117] Geometric sub-algorithm one can be obtained:

[0118]

[0119] In the following, the relationship between and will be further derived through spatial geometric relationship. Draw x-axis parallel line P1'G through point P1', and extend BP2' to intersect P1'G at M. It can be seen that △A'C'B≈Δ1P'MB, so there is geometric sub-algorithm two:

[0120]

[0121] wherein,

[0122]

[0123]

[0124] where L is the distance from camera optical center P2 to reference plane point O2, d is the spatial distance between projector optical center P1 and camera optical center P2, β is the angle between line P1P2 and x-z plane, α is the angle between the projection P1'P2' of P1P2 in the vertical plane and the positive direction of x-axis, and r is the distance between O1O2".

[0125] Substitute the above two equations of geometric sub-algorithm one into geometric sub-algorithm two to obtain an explicit mapping algorithm as follows:

[0126]

[0127] i.e. the explicit mapping relationship between the phase difference of the stripe Ψ and the deformation amount along the z direction.

[0128] Further, in the embodiment, the x and y coordinates are reconstructed based on the pinhole camera model, and the mapping relationship is shown as follows:

[0129]

[0130] where x c , y c are the pixel coordinates of the surface to be measured in the sampling image, z is the height coordinate, x c , y c and z are known quantities, m 11 to m 34 are pinhole camera model parameters, which can be obtained through camera calibration, and s ct is an intermediate variable. By solving the above equation, the x and y coordinates of the wing can be obtained.

[0131] The measurement light path corresponding to the above relationship does not require the projection optical axis to be directly opposite to the reference plane, but only requires the stripes in the reference plane to be parallel to each other. In terms of camera arrangement, the camera optical center can be arranged arbitrarily, as long as the camera optical axis is perpendicular to the reference plane. It is not required that the camera optical axis is coplanar with the projection optical axis, and the line connecting the optical centers of the two does not need to be parallel to the reference plane. Compared with the existing measurement light path, the light path does not make any telecentric light path approximation simplification in the derivation, and it does not require the distance from the camera to the measured plane to be much larger than the characteristic length of the measured area. It is not only suitable for long-distance measurement, but also suitable for large field of view and short-distance measurement.

[0132] To further illustrate the method of the embodiment, further illustration will be made in combination with specific application examples. The method is applied in the embodiment to measure three-dimensional deformation of a deformable elastic wing under the action of airflow in a wind tunnel experiment, and three-dimensional deformation data of the wing surface is quantitatively obtained. The elastic wing is installed on a simplified aircraft model, the model has a span length of 269.7 mm (millimeters), a wing root chord length of 39.5 mm, and a geometric angle of attack of 6°. In the measurement process, a projector projects a red sinusoidal grating onto the wing surface, the resolution is 1920*1080 pixels, the projection field of view is about 280 mm*160 mm, and the stripe period is about 15 pixels. A sampling camera uses a CCD (English full name: charge coupled device, Chinese: charge coupled device) camera, the resolution is 2456*2058 pixels, and the shooting field of view is greater than the wing span, about 300 mm*250 mm.

[0133] The coordinate origin of the embodiment is arranged at the wing tip of the undeformed wing, the positive direction of the x-axis is consistent with the flow direction, the positive direction of the y-axis is vertically upward, and the positive direction of the z-axis is along the span direction inward. The results show that the wing surface deformation is affected by the aerodynamic load, and the wing tip moves along the positive directions of the x-axis and the z-axis. Among them, the positive direction deformation of the elastic wing z-axis reduces the effective span length of the wing, and the reduction value is 4.32 mm. The wing tip of the elastic wing moves along the positive direction of the y-axis by 23.98 mm, and the wing tip position corresponds to the maximum upwash angle of 11.97°. In addition, under the action of the aerodynamic load, the elastic wing produces a torsional deformation, the effective angle of attack is reduced by about 1°, and the windward area is also significantly reduced.

[0134] Figure 6 A structural schematic diagram of a three-dimensional deformation measurement device provided for the application is shown in FIG. 1. Figure 6 As shown in the figure, in the embodiment, the three-dimensional deformation measurement device 300 can be arranged in an electronic device, the projection stripes generated by the projector projecting to the reference plane are parallel to each other, the optical axis of the camera is perpendicular to the reference plane, and the three-dimensional deformation measurement device 300 comprises:

[0135] The acquisition module 301 is configured to acquire geometric relationship parameters among the projector, the camera, and the reference plane, projection stripe data on the reference plane, and stripe images corresponding to the measured object. The stripe image is generated by the camera shooting the projection stripes on the surface of the measured object.

[0136] The reconstruction module 302 is configured to input the projection stripe data, the geometric relationship parameters, and the stripe image into a preset optical path measurement model, and reconstruct three-dimensional topographic data of the measured object.

[0137] The output module 303 is configured to output the three-dimensional topography of the measured object according to the three-dimensional topographic data.

[0138] The three-dimensional deformation measurement device provided in the embodiment can perform Figure 2The technical solutions, implementation principles and technical effects of the method embodiments shown Figure 2 The method embodiments shown are similar, and thus will not be described herein.

[0139] The three-dimensional deformation measurement device provided in the embodiment of the present application is further refined on the basis of the three-dimensional deformation measurement device provided in the previous embodiment. The three-dimensional deformation measurement device 300 comprises:

[0140] Optionally, in the embodiment, when acquiring the geometric relationship parameters among the projector, the camera and the reference plane, the acquisition module 301 is specifically configured to:

[0141] The point of intersection between the optical axis of the projector and the reference plane is taken as the coordinate origin, and a reference coordinate system is established based on the reference plane. The x-axis of the reference coordinate system is perpendicular to the projection stripe direction of the reference plane, the y-axis is parallel to the projection stripe direction of the reference plane, and the z-axis is perpendicular to the reference plane. The position information of the projector and the camera in the reference coordinate system is acquired. The geometric relationship parameters among the projector, the camera and the reference plane are determined according to the position information of the projector and the position information of the camera.

[0142] Optionally, in the embodiment, the geometric relationship parameters comprise the following parameters:

[0143] The included angle between the optical axis of the projector and the z-axis of the reference coordinate system.

[0144] The distance from the optical center of the projector to the coordinate origin, the distance from the optical center of the camera to the reference plane, and the spatial distance between the optical center of the projector and the optical center of the camera.

[0145] The included angle between the projection of the line connecting the optical center of the projector and the optical center of the camera in the vertical plane and the positive direction of the x-axis of the reference coordinate system. The vertical plane is a plane that is perpendicular to the reference plane and parallel to the x-axis.

[0146] The included angle between the line connecting the optical center of the projector and the optical center of the camera and the plane in which the optical axis of the projector is located. The plane in which the optical axis of the projector is located comprises the x-axis and the z-axis of the reference coordinate system.

[0147] Optionally, in the embodiment, the preset optical path measurement model comprises a stripe gray scale distribution algorithm and an explicit mapping algorithm between the stripe phase difference and the deformation amount along the z direction.

[0148] The reconstruction module 302 is specifically configured to:

[0149] For each position on the surface of the measured object in the stripe image, the following processing is performed:

[0150] The fringe gray scale at the target position and the fringe gray scale at the reference position are determined according to the projection fringe data at the reference position in the reference plane and the fringe data at the target position in the fringe image. The pixel positions at the reference position and the target position are the same. The fringe gray scales and the geometric relationship parameters are input into a fringe gray scale distribution algorithm to determine a fringe phase difference between the target position and the reference position. The fringe phase difference and the geometric relationship parameters are input into an explicit mapping algorithm to determine a z coordinate value at the target position.

[0151] The three-dimensional topography data of the measured object is generated according to the three-dimensional coordinates at each position on the surface of the measured object.

[0152] The three-dimensional deformation measurement device provided by the embodiment can perform Figures 2-5 The technical solutions of the method embodiment are similar to those of the device embodiment, and thus will not be repeated here. Figures 2-5

[0153] According to the embodiments of the present application, the present application further provides an electronic device, a computer readable storage medium and a computer program product.

[0154] As Figure 7 shown, Figure 7 is a structural schematic diagram of an electronic device provided by the present application. The electronic device is intended for various forms of digital computers, such as laptop computers, desktop computers, workstations, personal digital assistants, blade servers, mainframe computers, and other suitable computers. The components shown herein, their connections and relationships, and their functions, are merely examples and are not intended to limit the implementation of the present application described and / or claimed herein.

[0155] As Figure 7 shown, the electronic device includes a processor 401 and a memory 402. The various components are connected to each other by different buses, and can be installed on a common mainboard or in other ways as needed. The processor can process instructions executed within the electronic device.

[0156] The memory 402 is a non-transitory computer readable storage medium provided by the present application. The memory stores instructions executable by at least one processor, so that the at least one processor executes the three-dimensional deformation measurement method provided by the present application. The non-transitory computer readable storage medium of the present application stores computer instructions for causing a computer to execute the three-dimensional deformation measurement method provided by the present application.

[0157] The memory 402, as a kind of non-transitory computer readable storage medium, can be used to store non-transitory software programs, non-transitory computer executable programs and modules, such as program instructions / modules corresponding to the three-dimensional deformation measurement method in the embodiments of the present application (for example, the three-dimensional deformation measurement method shown in the foregoing method embodiment).​Figure 6 The processor 401 performs various function applications and data processing of the electronic device by running the non-transient software programs, instructions and modules stored in the memory 402, i.e. implements the three-dimensional deformation measurement method in the above method embodiments.

[0158] Meanwhile, the embodiment also provides a computer product. When instructions in the computer product are executed by a processor of an electronic device, the electronic device can execute the three-dimensional deformation measurement method of the above embodiment.

[0159] Other embodiments of the present application will be apparent to those skilled in the art from consideration of the specification and practice of the application disclosed herein. It is intended that the present application cover any and all variations of the application that come within the scope of the following claims and their equivalents. It is intended that the application not be limited to the examples described herein, but that it include all variations falling within the scope of the application.

[0160] It should be understood that the application is not limited to the precise construction that has been described above and illustrated in the accompanying drawings, and that various modifications and changes can be made by those skilled in the art without departing from the scope of the application. The scope of the application is limited only by the appended claims.

Claims

1. A three-dimensional deformation measurement method, characterized in that, The projected fringes generated by the projector onto the reference plane are parallel to each other, and the optical axis of the camera is perpendicular to the reference plane. The method includes: A reference coordinate system is established based on the reference plane, with the point where the projector's optical axis intersects the reference plane as the origin. The x-axis of the reference coordinate system is perpendicular to the direction of the projected fringes of the reference plane, the y-axis is parallel to the direction of the projected fringes of the reference plane, and the z-axis is perpendicular to the reference plane. The position information of the projector and camera within the reference coordinate system is obtained. The geometric relationship parameters between the projector, camera, and reference plane are determined based on the position information of the projector and camera. The plane containing the projector's optical axis includes the x-axis and z-axis of the reference coordinate system. Acquire the projected fringe data on the reference plane and the fringe image corresponding to the object under test; the fringe image is generated by the camera capturing the projected fringe on the surface of the object under test; The projected fringe data, geometric parameters, and fringe image are input into a preset optical path measurement model to reconstruct the three-dimensional shape data of the object under test. The preset optical path measurement model is applicable to optical path structures where the projector's optical axis is tilted at an arbitrary angle relative to the reference plane, and the camera's optical center is arbitrarily arranged in space. The preset optical path measurement model includes a fringe grayscale distribution algorithm and an explicit mapping algorithm. The fringe grayscale distribution algorithm establishes a spatial distribution model of the fringe based on the spatial geometric relationship between the projector and the camera. The explicit mapping algorithm establishes a direct mathematical mapping relationship between the fringe phase difference and height based on the principles of geometric optics. The three-dimensional shape of the object under test is output based on the three-dimensional shape data.

2. The method according to claim 1, characterized in that, The geometric relationship parameters include the following parameters: The angle between the projector's optical axis and the z-axis of the reference coordinate system; The distance from the projector's optical center to the origin of the coordinate system, the distance from the camera's optical center to the reference plane, and the spatial distance between the projector's optical center and the camera's optical center; The angle between the projection of the line connecting the optical center of the projector and the optical center of the camera onto the vertical plane and the positive direction of the x-axis of the reference coordinate system; the vertical plane is a plane that is perpendicular to the reference plane and parallel to the x-axis. The angle between the line connecting the optical center of the projector and the optical center of the camera and the plane containing the optical axis of the projector.

3. The method according to claim 2, characterized in that, The step of inputting the projected fringe data, geometric relationship parameters, and fringe image into a preset optical path measurement model to reconstruct the three-dimensional shape data of the object under test includes: The following processing is performed at each location on the surface of the object being measured in the stripe image: The grayscale values ​​of the stripes at the target position and the reference position are determined based on the projected stripe data at the reference position in the reference plane and the stripe data at the target position in the stripe image; the pixel positions at the reference position and the target position are the same. The stripe grayscale and geometric relationship parameters are input into the stripe grayscale distribution algorithm to determine the stripe phase difference between the target position and the reference position. The fringe phase difference and geometric relationship parameters are input into the explicit mapping algorithm to determine the z-coordinate value at the target location; The three-dimensional shape data of the object under test is generated based on the three-dimensional coordinates of various locations on the surface of the object under test.

4. A three-dimensional deformation measuring device, characterized in that, The projected fringes generated by the projector onto the reference plane are parallel to each other, and the optical axis of the camera is perpendicular to the reference plane. The device includes: The acquisition module is used to establish a reference coordinate system based on the reference plane, with the point where the projector's optical axis intersects the reference plane as the origin. The x-axis of the reference coordinate system is perpendicular to the direction of the projected fringes on the reference plane, the y-axis is parallel to the direction of the projected fringes on the reference plane, and the z-axis is perpendicular to the reference plane. It acquires the position information of the projector and camera within the reference coordinate system; determines the geometric relationship parameters between the projector, camera, and reference plane based on the position information of the projector and camera; the plane containing the projector's optical axis includes the x-axis and z-axis of the reference coordinate system; and acquires the projected fringes data on the reference plane and the fringes image corresponding to the object being measured; the fringes image is generated by the camera capturing the projected fringes on the surface of the object being measured. The reconstruction module is used to input the projected fringe data, geometric relationship parameters, and fringe image into a preset optical path measurement model to reconstruct the three-dimensional shape data of the object under test. The preset optical path measurement model is applicable to optical path structures where the projector's optical axis is at any tilt angle relative to the reference plane, and the camera's optical center is arbitrarily arranged in space. The preset optical path measurement model includes a fringe grayscale distribution algorithm and an explicit mapping algorithm. The fringe grayscale distribution algorithm establishes a spatial distribution model of the fringe based on the spatial geometric relationship between the projector and the camera. The explicit mapping algorithm establishes a direct mathematical mapping relationship between the fringe phase difference and height based on geometric optics principles. The output module is used to output the three-dimensional shape of the object under test based on the three-dimensional shape data.

5. An electronic device, characterized in that, include: Memory and processor; The memory stores computer-executed instructions; The processor executes computer execution instructions stored in the memory to implement the three-dimensional deformation measurement method as described in any one of claims 1 to 3.

6. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores computer-executable instructions, which, when executed by a processor, are used to implement the three-dimensional deformation measurement method as described in any one of claims 1 to 3.

7. A computer program product, comprising a computer program, characterized in that, When executed by a processor, the computer program implements the three-dimensional deformation measurement method as described in any one of claims 1 to 3.

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