A dual-frequency grating fringe projection system

Abstract

The application discloses a dual-frequency grating fringe projection system, and relates to the technical field of structured light measurement.The system comprises a light source modulation group, a grating modulation group, a beam splitter prism and a projection lens.The light source modulation group comprises a first LED light source, a second LED light source, a first collimating lens group and a second collimating lens group.The grating modulation group comprises a first grating sheet, a second grating sheet, a first piezoelectric ceramic and a second piezoelectric ceramic.The first piezoelectric ceramic in the grating modulation group is connected with the first grating sheet, and the second piezoelectric ceramic is connected with the second grating sheet, which is used to move the position of the grating sheet and make the fringe pattern at the bottom of the grating sheet translate.The system adopts two piezoelectric ceramics to drive grating sheets with different widths, and the beam splitter prism is used for beam combination, so that the system has a simple structure and can realize a low-cost dual-frequency four-step phase shift pattern.Fine grating fringes can improve the measurement accuracy of three-dimensional reconstruction, and wide grating fringes can improve the measurement depth of field of three-dimensional reconstruction, so that the application scope of the structured light 3D system is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of structured light measurement, in particular to a dual-frequency grating fringe projection system. BACKGROUND

[0002] The structured light three-dimensional measurement technology is also known as active triangulation, and its measurement principle is that a projector projects a coded grating pattern onto the surface of a measured object, a camera acquires a deformed fringe image modulated by the object, the modulated image contains the height information of the object, and thus the three-dimensional topography of the object can be obtained. However, the measurement accuracy and the measurement depth of the single-frequency grating fringe cannot meet the requirements of high-requirement measurement scenes. In order to improve the measurement accuracy and the measurement depth, researchers in the field need to develop a dual-frequency grating fringe projection system to meet the applicability of high-requirement measurement scenes. SUMMARY

[0003] The present application provides a dual-frequency grating fringe projection system, comprising:

[0004] a light source modulation group (1), a grating modulation group (2), a beam splitting prism (3), and a projection lens (4); the light source modulation group (1) comprises a first LED light source (11), a second LED light source (12), a first collimating lens group (13), and a second collimating lens group (14); the grating modulation group (2) comprises a first grating sheet (21), a second grating sheet (22), a first piezoelectric ceramic (23), and a second piezoelectric ceramic (24); the first piezoelectric ceramic (23) in the grating modulation group is connected with the first grating sheet (21), and the second piezoelectric ceramic (24) is connected with the second grating sheet (22), which is used to move the position of the grating sheet to make the fringe pattern at the bottom of the grating sheet translate; the light source emitted by the first LED light source (11) in the light source modulation group is modulated by the first collimating lens group (13) and then irradiates to the first grating sheet (21), the light source emitted by the second LED light source (12) is modulated by the second collimating lens group (14) and then irradiates to the second grating sheet (22), the structured light modulated by the first grating sheet (21) and the second grating sheet (22) is combined by the beam splitting prism (3), and finally projected onto the measured object by the projection lens (4) to obtain a dual-frequency grating fringe modulation pattern.

[0005] The dual-frequency grating fringe projection system as described above, wherein the first collimating lens group (13) and the second collimating lens group (14) respectively comprise a plurality of collimating lenses, the plurality of collimating lenses in the first collimating lens group (13) are connected along the vertical direction, and the central axes thereof are consistent in the vertical direction; the plurality of collimating lenses in the second collimating lens group (14) are connected along the horizontal direction, and the central axes thereof are consistent in the horizontal direction.

[0006] The double-frequency grating fringe projection system as claimed in claim 1, wherein the first collimating lens group (13) comprises an upper lens (131) and a lower lens (132), and the corresponding second collimating lens group (14) comprises a left lens (141) and a right lens (142), wherein the upper lens (131) and the right lens (142) are of the same size, the lower lens (132) and the left lens (141) are of the same size, and the size of the upper lens (131) and the right lens (142) is smaller than that of the lower lens (132) and the left lens (141).

[0007] The double-frequency grating fringe projection system as claimed in claim 1, wherein the first grating sheet (21) and the second grating sheet (22) are of different fringe pattern widths, the first grating sheet (21) is of a fine grating fringe, and the second grating sheet (22) is of a wide grating fringe.

[0008] The application further provides a height information measurement method based on the double-frequency grating fringe projection system.

[0009] In step S10, the first LED light source emits collimated light to the first grating sheet, the light is projected to the measured object by the projection lens after passing through the light splitting prism, the first grating sheet is driven by the first piezoelectric ceramic, and the grating fringe modulation pattern generated in the movement of the first grating sheet is collected.

[0010] In step S20, the second LED light source emits collimated light to the second grating sheet, the light is projected to the measured object by the projection lens after passing through the light splitting prism, the second grating sheet is driven by the second piezoelectric ceramic, and the grating fringe modulation pattern generated in the movement of the second grating sheet is collected.

[0011] In step S30, the double-frequency height map of the measured object is generated based on the two collected grating fringe modulation patterns.

[0012] In step S40, the three-dimensional reconstruction of the measured object is performed according to the generated double-frequency height map, and the final high-precision three-dimensional model is obtained.

[0013] The application has the following beneficial effects: two piezoelectric ceramics are used to drive grating sheets of different widths, and the light splitting prism is used for beam combination, so that a low-cost double-frequency four-step phase shift pattern can be realized. BRIEF DESCRIPTION OF DRAWINGS

[0014] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the drawings needed to be used in the embodiments or prior art description will be briefly introduced as follows. Obviously, the drawings in the following description only represent some embodiments of the present application, and other drawings can also be obtained by those skilled in the art based on these drawings.

[0015] Figure 1 and Figure 2 is a schematic diagram of a dual-frequency grating fringe projection system provided by Embodiment One of the present application;

[0016] Figure 3 is a schematic diagram of a bottom fine fringe pattern of a grating sheet provided by Embodiment One of the present application;

[0017] Figure 4 is a schematic diagram of a bottom wide fringe pattern of a grating sheet provided by Embodiment One of the present application;

[0018] Figure 5 is a flowchart of a height information measurement method based on a dual-frequency grating fringe projection system provided by Embodiment Two of the present application. DETAILED DESCRIPTION

[0019] The technical solutions in the embodiments of the present application will be described clearly and completely in combination with the drawings in the embodiments of the present application. Obviously, the described embodiments are only some of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work fall within the scope of protection of the present application.

[0020] Embodiment One

[0021] As Figure 1As shown, the embodiment one of the present application provides a dual-frequency grating fringe projection system, which comprises a light source modulation group 1, a grating modulation group 2, a beam splitter prism 3 and a projection lens 4; the light source modulation group 1 comprises a first LED light source 11, a second LED light source 12, a first collimating lens group 13 and a second collimating lens group 14; the grating modulation group 2 comprises a first grating sheet 21, a second grating sheet 22, a first piezoelectric ceramic 23 and a second piezoelectric ceramic 24; the first piezoelectric ceramic 23 in the grating modulation group is connected with the first grating sheet 21, and the second piezoelectric ceramic 24 is connected with the second grating sheet, which is used to move the position of the grating sheet to make the fringe pattern at the bottom of the grating sheet translate; the light source emitted by the first LED light source 11 in the light source modulation group is modulated by the first collimating lens group 13 and then irradiates to the first grating sheet 21, and the light source emitted by the second LED light source 12 is modulated by the second collimating lens group 14 and then irradiates to the second grating sheet 22, and then the structured light modulated by the first grating sheet 21 and the second grating sheet 22 is combined by the beam splitter prism 3, and finally projected onto the measured object through the projection lens 4 to obtain a dual-frequency grating fringe modulation pattern.

[0022] In the embodiment of the present application, the number of the light source modulation group (1) and the grating modulation group (2) is set as needed to obtain a multi-frequency grating fringe modulation pattern.

[0023] The first collimating lens group 13 and the second collimating lens group 14 respectively comprise a plurality of collimating lenses, wherein the plurality of collimating lenses in the first collimating lens group 13 are connected in the vertical direction, and the central axes thereof are consistent in the vertical direction; the plurality of collimating lenses in the second collimating lens group 14 are connected in the horizontal direction, and the central axes thereof are consistent in the horizontal direction. It should be noted that the number of lenses in the collimating lens group can be set as needed within the allowable cost to improve the coupling efficiency of LED collimation and image quality.

[0024] Figure 1 Taking two collimating lenses as an example, referring to Figure 2 , the first collimating lens group 13 comprises an upper lens 131 and a lower lens 132, and the corresponding second collimating lens group 14 comprises a left lens 141 and a right lens 142, wherein the upper lens 131 and the right lens 142 are consistent in size, the lower lens 132 and the left lens 141 are consistent in size, and the size of the upper lens 131 and the right lens 142 is smaller than that of the lower lens 132 and the left lens 141.

[0025] As shown in Figure 3 , Figure 4 , the fringe pattern width at the bottom of the first grating sheet 21 and the second grating sheet 22 is different, the fringe pattern at the bottom of the first grating sheet 21 is fine, which is used to improve the measurement accuracy of three-dimensional reconstruction, and the fringe pattern at the bottom of the second grating sheet 22 is wide, which is used to improve the measurement depth of view of three-dimensional reconstruction.

[0026] The working principle of the system is that two grating pieces with different widths are adopted, the light is combined through a beam splitter prism, and is projected to a projection object plane through a projection lens. The system can project two grating fringe patterns with different widths. The fine grating fringe can improve the measurement precision of three-dimensional reconstruction, and the wide grating fringe can improve the measurement depth of field of three-dimensional reconstruction, thereby improving the applicable scene of the structured light 3D system.

[0027] In the measurement, the first LED light source 11 is first turned on, the light emitted by the first LED light source 11 is collimated by the first collimating lens group 13 and then irradiates the first grating piece 21, the fringe pattern at the bottom of the first grating piece 21 is projected onto the measured object through the projection lens 4 after passing through the beam splitter prism 3, at this time, the captured camera captures the mapped fringe pattern once, then the first grating piece 21 is moved three times by the first piezoelectric ceramic 23, and the grating fringe width is 1 / 2 each time. The projection fringe pattern after each movement of the first grating piece 21 is synchronously captured by the capture camera, at this time, the fine grating fringe modulation pattern has been captured; the first LED light source 11 is turned off, the second LED light source 12 is turned on, the light emitted by the second LED light source 12 is collimated by the second collimating lens group 14 and then irradiates the second grating piece 22, the fringe pattern at the bottom of the second grating piece 22 is projected onto the measured object through the projection lens 4 after passing through the beam splitter prism 3, and the captured camera captures the mapped fringe pattern once, then the second grating piece 22 is moved three times by the second piezoelectric ceramic 24, and the grating fringe width is 1 / 2 each time. The projection fringe pattern after each movement of the second grating piece 22 is synchronously captured by the capture camera, at this time, the wide grating fringe modulation pattern has also been captured, and the three-dimensional reconstruction is performed using the eight captured images, so that more accurate height information of the measured object can be obtained.

[0028] Embodiment two

[0029] As shown in Figure 5 , the embodiment two of the application provides a height information measurement method based on a dual-frequency grating fringe projection system, which comprises:

[0030] Step S10: The first LED light source emits collimated light to the first grating piece, the light is projected to the measured object by the projection lens after passing through the beam splitter prism, the first grating piece is pushed by the first piezoelectric ceramic, and the grating fringe modulation pattern generated in the movement of the first grating piece is captured;

[0031] Firstly, the first LED light source is turned on, and the light emitted by the first LED light source is irradiated to the first grating sheet after collimation by the first collimation lens group 13. The stripe pattern at the bottom of the first grating sheet is projected onto the measured object by the projection lens after passing through the light splitting prism. At this time, the captured camera captures the mapped stripe pattern once. Then, the first grating sheet is moved three times by the first piezoelectric ceramic, and each time the grating stripe width is 1 / 2. The captured camera synchronously captures the projected stripe pattern after each movement of the first grating sheet. At this time, the fine grating stripe modulation pattern has been captured, and the first LED light source is turned off.

[0032] Step S20: The second LED light source emits collimated light to the second grating sheet, which is projected onto the measured object by the projection lens after passing through the light splitting prism. The second grating sheet is moved by the second piezoelectric ceramic, and the grating stripe modulation pattern generated during the movement of the second grating sheet is captured.

[0033] The second LED light source is turned on, and the light emitted by the second LED light source is irradiated to the second grating sheet after collimation by the second collimation lens group. The stripe pattern at the bottom of the second grating sheet is projected onto the measured object by the projection lens after passing through the light splitting prism. The captured camera captures the mapped stripe pattern once. Then, the second grating sheet is moved three times by the second piezoelectric ceramic, and each time the grating stripe width is 1 / 2. The captured camera synchronously captures the projected stripe pattern after each movement of the second grating sheet. At this time, the wide grating stripe modulation pattern has been captured.

[0034] Step S30: Based on the two groups of captured grating stripe modulation patterns, a dual-frequency height map of the measured object is generated.

[0035] The captured grating stripe modulation patterns have two groups, each with four pictures. The four-step phase shift method is used to represent the phase change on the four pictures, and the height information of the measured object is solved by using the relationship between the phase and the height. The dual-frequency height map of the measured object is constructed. Specifically:

[0036] Step S31: Create a phase value solving equation set according to the gray value of the pixel in the grating stripe adjustment pattern.

[0037] In the grating stripe adjustment pattern, the gray value corresponding to the object point (x, y) is represented as :

[0038] wherein, is the light intensity of the ambient light, is the light wave amplitude value related to the projection light intensity, is the phase value corresponding to the object point , is the phase shift amount of the phase shift stripe.

[0039] When acquiring the grating stripe adjustment pattern, the structured light stripes move each time. One cycle means that the phase shift amount for each cycle is... Therefore, the system of equations for solving the phase value can be expressed as:

[0040] Where I1, I2, I3, and I4 represent the gray values ​​corresponding to the object points (x, y) in a set of grating stripe modulation patterns.

[0041] Step S32: Solve the equations in the system of equations to obtain the phase values ​​of each point of the measured object in the two sets of grating stripe modulation patterns.

[0042] Formula used: Solve for the position of each point of the object The corresponding phase values, where I1, I2, I3, and I4 represent the gray values ​​corresponding to the object point (x, y) in a set of grating stripe modulation patterns.

[0043] Because the arctangent function is used in the formula for calculating the phase value, the range of the obtained phase values ​​is: This type of phase is called the wrap phase or truncated phase. To reconstruct a continuous phase distribution, we need to unwrap the wrap phase, usually by comparing the truncated phase values ​​of two adjacent pixels and adding or subtracting them. To restore continuous phase.

[0044] Step S33: Calculate the height of the object surface based on the two sets of phase values ​​at each point of the object being measured, and generate a dual-frequency height map;

[0045] Using formula To calculate the height h of each point on the object being measured, where AC represents the distance between point A and the adjacent point C, and β is the angle between point C and the light ray projected by the projection lens. For stripe spacing, Let be the phase difference between point A and point C.

[0046] After calculation, two sets of phase values ​​can be used to obtain two sets of height data, namely the height data presented at the two fringe frequencies of the fine grating fringes and the wide grating fringes. The height map made based on these height data is stored as a dual-frequency height map.

[0047] Step S40: Perform 3D reconstruction of the object under test based on the generated dual-frequency height map to obtain the final high-precision 3D model;

[0048] The fine grating stripe can improve the measurement accuracy of three-dimensional reconstruction, and the wide grating stripe can improve the measurement depth of field of three-dimensional reconstruction. In this step, the dual-frequency height map generated by combining the two grating stripes is used for three-dimensional reconstruction of the measured object to obtain the final high-precision three-dimensional model, so as to meet the measurement requirements of the application scene to the greatest extent. The specific steps are as follows:

[0049] Step S41: Calculate the fusion coefficient of measurement accuracy and measurement depth of field according to the measurement requirements of the current application scene;

[0050] Take the n expected measurement data of the measured object as the standard data, and bring the n current dual-frequency height data into the fusion coefficient calculation formula: The fusion coefficient of measurement accuracy and measurement depth of field is obtained, denoted as And , wherein is the estimated value of the jth measurement accuracy fusion coefficient, is the estimated value of the jth measurement depth of field fusion coefficient, j takes the value of 1~m, m is the total number of fusion coefficient estimates, and subscript j is iterated after each summation formula calculation is completed, is the height data of the ith point measured by the fine grating stripe in the dual-frequency height map, is the height data of the ith point measured by the wide grating stripe in the dual-frequency height map, Y is the expected measurement data of the ith point, i takes the value of 1~n, n is the total number of points participating in the calculation, The return expression in the bracket is the minimum And .

[0051] Step S42: Fuse the height data in the dual-frequency height map based on the calculated fusion coefficient;

[0052] Bring the height data of each point in the dual-frequency height map into the height fusion formula: The fused point height data is obtained, and these data are collected into a set to provide data support for subsequent three-dimensional reconstruction, wherein is the fused point height data, is the height data measured by the fine grating stripe in the dual-frequency height map, is the height data measured by the wide grating stripe in the dual-frequency height map, And are the fusion coefficients of measurement accuracy and measurement depth of field, respectively, is the error generated when the stripe pitch changes by one unit, is the preset standard stripe pitch, is the pitch of the fine grating stripe, is the pitch of the wide grating stripe.

[0053] Step S43: using the fused height data to reconstruct a three-dimensional model of the measured object;

[0054] According to the fused height data, the spatial coordinates (X, Y, Z) of each sampling point of the measured object are obtained. A set of points is called a point cloud. The point cloud is further simplified into a mesh form, which is composed of a set of vertices and polygons, usually composed of triangles, quadrilaterals or other simple convex polygons. Thus, the point cloud data is converted into a polyhedral shape. Then, an image is overlaid on the surface of the polyhedron to achieve texture mapping, increase the details and realism of the model, and finally form a three-dimensional model which is the result of the combination of the polyhedron and the mapping or rendering.

[0055] Those skilled in the art should be aware that, in one or more examples described above, the functions described by the present application can be implemented by a combination of hardware and software. When the software is applied, the corresponding functions can be stored in a computer readable medium or transmitted as one or more instructions or codes on a computer readable medium. The computer readable medium includes a computer storage medium and a communication medium, wherein the communication medium includes any medium that facilitates the transfer of a computer program from one place to another. The storage medium can be any available medium that can be accessed by a general or special purpose computer.

[0056] The above detailed description of the specific embodiments of the present application further illustrates the purposes, technical solutions and beneficial effects of the present application. It should be understood that the above detailed description is only a specific embodiment of the present application and is not used to limit the protection scope of the present application. Any modification, equivalent replacement, improvement, etc. made on the basis of the technical solutions of the present application should be included in the protection scope of the present application.

Claims

1. A dual-frequency grating fringe projection system, characterized in that, Comprise: Light source modulation group (1), grating modulation group (2), light splitting prism (3) and projection lens (4); Light source modulation group (1) comprises first LED light source (11), second LED light source (12), first collimating lens group (13) and second collimating lens group (14); Grating modulation group (2) comprises first grating sheet (21), second grating sheet (22), first piezoelectric ceramic (23) and second piezoelectric ceramic (24); The first piezoelectric ceramic (23) in the grating modulation group is connected with the first grating sheet (21), and the second piezoelectric ceramic (24) is connected with the second grating sheet (22), for moving the position of grating sheet, so that the stripe pattern at the bottom of grating sheet is translated; The light source emitted by the first LED light source (11) in the light source modulation group is modulated by the first collimating lens group (13) and then irradiated to the first grating sheet (21), the light source emitted by the second LED light source (12) is modulated by the second collimating lens group (14) and then irradiated to the second grating sheet (22), then the structured light modulated by the first grating sheet (21) and the second grating sheet (22) is combined by the light splitting prism (3), and finally projected onto the measured object through the projection lens (4), to obtain a double-frequency grating stripe modulation pattern; The number of light source modulation group (1) and grating modulation group (2) is set as required, for obtaining a multi-frequency grating stripe modulation pattern; The three-dimensional reconstruction of the measured object is carried out based on the double-frequency height map generated based on the double-frequency stripe modulation pattern, to obtain a final high-precision three-dimensional model, specifically comprising the following substeps: The fusion coefficient of the measurement accuracy and the measurement depth of field is calculated according to the measurement requirements of the current application scene; n measurement data of the measured object meeting the expectation is taken as standard data, and the n double-frequency height data are brought into the fusion coefficient calculation formula: The fusion coefficient of the measurement accuracy and the measurement depth of field is calculated according to the measurement requirements of the current application scene; n measurement data of the measured object meeting the expectation is taken as standard data, and the n double-frequency height data are brought into the fusion coefficient calculation formula: And , wherein is the estimated value of the jth measurement accuracy fusion coefficient, is the estimated value of the jth measurement depth of field fusion coefficient, j takes the value of 1~m, m is the total number of the estimated value of the fusion coefficient, and the subscript j is iterated after the calculation of the summation formula is completed each time, is the height data of the ith point measured by the fine grating fringe in the double-frequency height map, is the height data of the ith point measured by the wide grating fringe in the double-frequency height map, Y is the expected measurement data of the ith point, i takes the value of 1~n, n is the total number of points participating in the calculation, The calculation result of the expression in the return bracket is the minimum And ; Fuse the height data in the dual-frequency height map based on the calculated fusion coefficient; bring the height data of each point in the dual-frequency height map into the height fusion formula: In the formula, the fused point height data is obtained, and the data is collected into a set to provide data support for subsequent three-dimensional reconstruction, wherein For the fused point height data, For the height data measured by the fine grating fringe in the dual-frequency height map, For the height data measured by the wide grating fringe in the dual-frequency height map, And The fusion coefficients of the measurement accuracy and the measurement depth are respectively, The error generated when the fringe spacing changes by one unit, The preset standard fringe spacing, The spacing of the fine grating fringe, The spacing of the wide grating fringe; Reconstructing the three-dimensional model of the measured object using the fused height data.

2. The dual-frequency grating fringe projection system according to claim 1, wherein, The first collimating lens group (13) and the second collimating lens group (14) respectively comprise a plurality of collimating lenses, wherein the plurality of collimating lenses in the first collimating lens group (13) are connected along the vertical direction, and the central axes thereof are consistent in the vertical direction; The plurality of collimating lenses in the second collimating lens group (14) are connected along the horizontal direction, and the central axes thereof are consistent in the horizontal direction.

3. The dual-frequency grating fringe projection system of claim 2, wherein, The first collimating lens group (13) comprises an upper lens (131) and a lower lens (132), and the corresponding second collimating lens group (14) comprises a left lens (141) and a right lens (142), wherein the upper lens (131) and the right lens (142) are consistent in size, the lower lens (132) and the left lens (141) are consistent in size, and the size of the upper lens (131) and the right lens (142) is smaller than that of the lower lens (132) and the left lens (141).

4. The dual-frequency grating fringe projection system of claim 1, wherein, The stripe pattern at the bottom of the first grating sheet (21) and the second grating sheet (22) is different in width, the stripe pattern at the bottom of the first grating sheet (21) is fine, for improving the measurement accuracy of three-dimensional reconstruction, and the stripe pattern at the bottom of the second grating sheet (22) is wide, for improving the measurement depth of three-dimensional reconstruction.

5. The dual-frequency grating fringe projection system according to claim 1, wherein, In the measurement, first open the first LED light source (11), the light source emitted by the first LED light source (11) is collimated through the first collimating lens group (13) and irradiated to the first grating sheet (21), the stripe pattern at the bottom of the first grating sheet (21) is projected onto the measured object through the light splitting prism (3) and the projection lens (4), at this time, the mapping stripe pattern is collected by the collection camera for one time, then the first grating sheet (21) is moved three times by the first piezoelectric ceramic (23), the grating stripe width is moved by 1 / 2 each time, the projection stripe pattern of the first grating sheet (21) after each movement is collected by the collection camera synchronously, four fine grating stripe modulation patterns are obtained, then the first LED light source (11) is turned off, the second LED light source (12) is turned on, the light source emitted by the second LED light source (12) is collimated through the second collimating lens group (14) and irradiated to the second grating sheet (22), the stripe pattern at the bottom of the second grating sheet (22) is projected onto the measured object through the light splitting prism (3) and the projection lens (4), the mapping stripe pattern is collected by the collection camera for one time, then the second grating sheet (22) is moved three times by the second piezoelectric ceramic (24), the grating stripe width is moved by 1 / 2 each time, the projection stripe pattern of the second grating sheet (22) after each movement is collected by the collection camera synchronously, four wide grating stripe modulation patterns are obtained.

6. A height information measurement method based on a dual-frequency grating fringe projection system, for implementing the dual-frequency grating fringe projection system according to any one of claims 1-5, characterized in that, Comprise: Step S10: the first LED light source emits collimated light to the first grating sheet, which is projected onto the measured object by the projection lens after passing through the light splitting prism, the first grating sheet is pushed by the first piezoelectric ceramic, and the grating stripe modulation pattern generated during the movement of the first grating sheet is collected; Step S20: the second LED light source emits collimated light to the second grating sheet, which is projected onto the measured object by the projection lens after passing through the light splitting prism, the second grating sheet is pushed by the second piezoelectric ceramic, and the grating stripe modulation pattern generated during the movement of the second grating sheet is collected; Step S30: generating a dual-frequency height map of the measured object based on the two groups of collected grating stripe modulation patterns; Step S40: three-dimensional reconstruction of the measured object is performed according to the generated dual-frequency height map, and a final high-precision three-dimensional model is obtained.

7. The height information measurement method based on a dual-frequency grating fringe projection system according to claim 6, characterized in that, Generating a dual-frequency height map of the measured object based on the two groups of collected grating stripe modulation patterns, specifically comprising the following sub-steps: Creating a phase value solving equation group according to the gray value of the pixels in the grating stripe adjustment pattern; Solving the phase value of each point of the measured object in the two groups of grating stripe modulation patterns by simultaneously solving the equations in the phase value solving equation group; According to the two groups of phase values of each point of the measured object, the height of the object surface is calculated respectively, and a dual-frequency height map is generated.

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