A 3D reconstruction method based on kinematic calibration of single - body of line - structured light point sets

Abstract

The present invention discloses a three-dimensional reconstruction method based on the kinematic calibration of a single-line structured light point set. The method includes: rigidly combining a planar array camera with a one-dimensional line structured light emitter and installing them on a motion platform; using the standard value of the standard ball radius and the line structured light scanning data to calibrate the structural parameters of the motion platform of the measuring device; taking the position of the center of the calibrated standard ball and the standard radius of the standard ball as constraints to calibrate the spatial position relationship of the line scan point set; controlling the five-axis motion platform to move and obtaining the scanning data of the measured part at different poses; using the scanning data and the instant point cloud calibration matrix to complete the high-quality three-dimensional model reconstruction of the multi-pose scanning of the measured part. The system includes: a device fixing module, a calibration module, a point cloud calibration module, a scanning module, and a point cloud reconstruction module. By using the present invention, the reconstruction accuracy of the three-dimensional point cloud model of the line structured light can be improved. The present invention can be widely applied to the field of three-dimensional reconstruction.

Description

Technical Field

[0001] The present invention relates to the field of three-dimensional reconstruction, and particularly to a three-dimensional reconstruction method based on kinematic calibration of line-structured light point set monomerization. Background Art

[0002] With the rapid development of China's manufacturing industry, the requirements for high-precision inspection of complex workpieces are increasing day by day. The combination of line-structured light and a five-axis motion platform can achieve multi-position scanning and point cloud model reconstruction, so as to complete the inspection task of complex workpieces. However, due to manufacturing and assembly errors, there are often certain deviations between the actual structure and the theoretical structure of the five-axis motion platform, which affects its positioning accuracy. And since the reconstruction accuracy of line-structured light is related to the platform structure, therefore, after improving the platform accuracy through kinematic calibration first, then obtaining the point cloud by line-structured light scanning and performing immediate calibration on the point cloud can improve the three-dimensional reconstruction accuracy of the line-structured light multi-position scanning system.

[0003] Kinematic calibration is a method for compensating the geometric errors of the platform and improving its absolute accuracy. Existing kinematic calibration methods usually need to rely on expensive equipment such as laser trackers to collect the multi-axis motion pose information, with high calibration costs and problems of insufficient observation data. In addition, the three-dimensional reconstruction accuracy of the line-structured light multi-position is not only related to the platform positioning accuracy but also affected by the point cloud position accuracy. Existing methods usually do not consider the immediate calibration of the point cloud measured by line-structured light, resulting in insufficient three-dimensional reconstruction accuracy of the line-structured light multi-position scanning system. Summary of the Invention

[0004] In view of this, in order to solve the three-dimensional reconstruction problem of the existing line-structured light multi-position scanning system, the present invention proposes a three-dimensional reconstruction method based on kinematic calibration of line-structured light point set monomerization, and the method includes the following steps:

[0005] Rigidly combine a area array camera and a one-dimensional line-structured light emitter, and install them on a five-axis motion platform to obtain a measuring device;

[0006] Use the standard value of the standard ball radius and the line-structured light scanning data to calibrate the structural parameters of the motion platform of the measuring device to obtain the calibrated measuring device;

[0007] Taking the position of the center of the calibrated standard ball and the standard radius of the standard ball as constraints, calibrate the spatial position relationship of the line scanning point set to obtain an immediate point cloud calibration matrix;

[0008] Control the five-axis motion platform to move and obtain the scanning data of the standard ball in different poses;

[0009] Based on the calibrated measuring device, according to the scanning data and the immediate point cloud calibration matrix, automatically complete the high-quality three-dimensional model reconstruction of the multi-position scanning of the workpiece to be measured.

[0010] The beneficial effects of this embodiment are: non-contact three-dimensional visual measurement is achieved by combining a straight-line structured light emitter and a camera, without the need for a laser tracker, thereby reducing calibration costs; and, since the line structured light three-dimensional scanning system can collect dense point clouds by controlling the movement of the platform, all point clouds can directly participate in the calibration of the structural parameters of the motion platform, the amount of observation data required for calibration is greatly increased, thereby improving the recognition accuracy of error parameters.

[0011] Furthermore, if the measuring device has already been calibrated, the calibration step is skipped.

[0012] In some embodiments, the step of calibrating the structural parameters of the motion platform of the measuring device using the standard value of the standard sphere radius and the line structured light scanning data to obtain the calibrated measuring device specifically includes:

[0013] Fix the standard ball at the center of the flange at the end of the five-axis motion platform;

[0014] Controlling the movement of the five-axis motion platform and acquiring scanning data of the standard ball in different positions and postures;

[0015] According to the influence of each axis of the five-axis motion platform on the end, the kinematic model and kinematic error model are constructed, and the error parameter items are determined;

[0016] Solve the spherical arc point cloud in the terminal coordinate system and take multiple frames of point cloud to fit the sphere center to obtain the initial sphere center position;

[0017] Constructing an objective function based on the three-dimensional information of the spherical arc point cloud, the initial sphere center position and the standard radius of the standard sphere;

[0018] Based on the objective function, all the spherical arc point sets are monomerized and directly involved in error identification, so as to complete the calibration of the motion platform structure parameters and obtain the calibrated measuring device.

[0019] The beneficial effect of this embodiment is that the influence of the structural parameters of each motion platform of the translation axis and the rotation axis on the measurement of the center and the measurement radius of the standard sphere is utilized, so as to minimize the interference caused by the error of the line structured light plane solution, and the calibration of the translation axis and the rotation axis can be taken into account. At the same time, all the spherical arc point sets obtained by scanning can be directly involved in the error identification after being monomerized, and finally the error parameter item identification result is ensured to be accurate, thereby improving the platform motion accuracy and the reconstruction accuracy of the three-dimensional point cloud model.

[0020] In some embodiments, the step of completing high-quality three-dimensional model reconstruction of the multi-pose scan of the measured object based on the calibrated measuring device using the scanning data and the real-time point cloud calibration matrix specifically includes:

[0021] Based on the calibrated measuring device, the three-dimensional information of the center points of the line structured light stripes in the camera coordinate system is calculated according to the camera internal parameter matrix and the light plane equation in the camera coordinate system;

[0022] Combined with the hand-eye transformation matrix, the calibrated inverse kinematic transformation matrix and the instant point cloud calibration matrix, the scanning data in each pose is converted to the end coordinate system.

[0023] The beneficial effect of this embodiment is that by using the position of the center of the standard ball after kinematic calibration, the calibration of the spatial position relationship of the line scanning point set can be realized, further improving the detection accuracy of the system. By combining the line structured light system with the multi-axis motion platform after kinematic calibration, complex workpieces can be scanned in multiple directions and the point clouds of each frame can be converted to the same coordinate system through the motion relationship, automatically realizing the high-quality and complete shape reconstruction of the multi-directional scanned point cloud model of the complex workpiece.

[0024] The present invention also proposes a three-dimensional reconstruction system, which includes:

[0025] A device fixing module for rigidly combining a area array camera and a one-dimensional line structured light emitter and installing them on a five-axis motion platform to obtain a measuring device;

[0026] A calibration module for calibrating the structural parameters of the motion platform of the measuring device by using the standard value of the radius of the standard ball and the line structured light scanning data to obtain a calibrated measuring device;

[0027] A point cloud calibration module for calibrating the spatial position relationship of the line scanning point set with the position of the center of the calibrated standard ball and the standard radius of the standard ball as constraints to obtain an instant point cloud calibration matrix;

[0028] A scanning module for controlling the motion of the five-axis motion platform and obtaining the scanning data of the workpiece under different poses;

[0029] A point cloud reconstruction module for automatically completing the high-quality three-dimensional model reconstruction of the multi-pose scanning of the workpiece based on the calibrated measuring device, according to the scanning data and the instant point cloud calibration matrix.

[0030] Based on the above solution, the present invention provides a three-dimensional reconstruction method based on kinematic calibration of line structured light point set monomerization, which combines line structured light with a five-axis platform and uses the calibrated five-axis platform and three-dimensional point cloud to perform three-dimensional reconstruction of the overall shape of the workpiece to be measured. While ensuring the motion accuracy of the platform and the absolute accuracy of the line scanning point set, the reconstruction accuracy of the multi-pose three-dimensional point cloud model of the line structured light is improved. Description of the Drawings

[0031] Figure 1 is the step flow chart of a three-dimensional reconstruction method based on kinematic calibration of line structured light point set monomerization of the present invention;

[0032] Figure 2 is a schematic diagram of the kinematic modeling of a five-axis motion platform according to a specific embodiment of the present invention;

[0033] Figure 3 is a schematic diagram of the light plane solution deviation according to a specific embodiment of the present invention;

[0034] Figure 4 is a structural block diagram of a three-dimensional reconstruction system according to the present invention. Detailed implementation manners

[0035] In addition to the problem that the existing calibration methods in the background technology usually need to rely on expensive equipment such as laser trackers, resulting in high costs, the traditional standard sphere calibration method calibrates the kinematic parameters by registering the center points of the spheres solved from each piece of point cloud. There are fewer parameters that can be identified, and multiple structural parameters of the motion platform cannot be calibrated simultaneously. At the same time, since the center point solution of a single piece of point cloud is easily affected and interfered by the solution accuracy of the stripe center point, it is difficult to ensure the accuracy of the identification result, which in turn affects the platform positioning accuracy and the point cloud model reconstruction accuracy.

[0036] Next, the technical solutions in the embodiments of the present application will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are only a part 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 of ordinary skill in the art without creative efforts shall fall within the protection scope of the present application.

[0037] It should be noted that for the convenience of description, only the parts related to the relevant invention are shown in the drawings. Without conflict, the embodiments in the present application and the features in the embodiments can be combined with each other.

[0038] It should be understood that the "system", "device" and / or "module" used in the present application is a method for distinguishing different components, elements, parts, portions or assemblies at different levels. However, if other words can achieve the same purpose, that word can be replaced by other expressions.

[0039] As shown in the present application and the claims, unless the context clearly indicates an exception, words such as "a", "an", "one" and / or "the" are not specifically singular and may also include plural. Generally speaking, the terms "include" and "comprise" only indicate the inclusion of the steps and elements that have been clearly identified, and these steps and elements do not constitute an exclusive list. A method or device may also include other steps or elements. An element defined by the statement "including one..." does not exclude the existence of another identical element in the process, method, commodity or device including the element.

[0040] In the description of the embodiments of the present application, "a plurality" means two or more than two. The following terms "first" and "second" are only used for descriptive purposes and cannot be construed as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include one or more of such features.

[0041] In addition, flowcharts are used in the present application to illustrate the operations performed by the system according to the embodiments of the present application. It should be understood that the operations before or after do not necessarily need to be executed precisely in sequence. On the contrary, they can be executed in reverse order or simultaneously. At the same time, other operations can also be added to these processes, or one or several steps of operations can be removed from these processes.

[0042] Refer to Figure 1 , which is a schematic flowchart of an optional example of the three-dimensional reconstruction method based on the kinematic calibration of the line-structured light point set monomerization proposed by the present invention. This method can be applied to computer devices. The three-dimensional point cloud reconstruction method proposed in this embodiment may include but is not limited to the following steps:

[0043] Step S1: Rigidly combine a planar array camera with a one-dimensional line-structured light emitter and install them on a five-axis motion platform to obtain a measuring device;

[0044] Among them, after the components are combined, the line-structured light stripes are within the camera's field of view.

[0045] Step S2: Use the standard value of the standard ball radius and the line-structured light scanning data to calibrate the structural parameters of the motion platform of the measuring device to obtain the calibrated measuring device;

[0046] S2.1: Fix the standard ball at the center of the end flange of the five-axis motion platform;

[0047] S2.2: Control the five-axis motion platform to move and obtain the scanning data of the standard ball in different poses;

[0048] Specifically, under the condition of ensuring that the line-structured light can irradiate the spherical surface of the standard ball, the platform makes arbitrary movements to obtain the scanning data of the standard ball in various poses.

[0049] S2.3: Construct a kinematic model and a kinematic error model according to the influence of each axis of the five-axis motion platform on the end, and determine the error parameter terms;

[0050] S2.4: Solve the spherical arc point cloud in the end coordinate system and take multiple frames to fit the center of the ball to obtain the initial position of the center of the ball;

[0051] S2.5: Construct an objective function according to the three-dimensional information of the spherical arc point cloud, the initial position of the center of the ball, and the standard radius of the standard ball;

[0052] S2.6. Based on the objective function, monomerize all the spherical arc point sets and directly participate in error identification to complete the calibration of the structural parameters of the moving platform, and obtain the calibrated measuring device.

[0053] Step S3: With the position of the center of the standard ball after calibration and the standard radius of the standard ball as constraints, calibrate the position relationship of the line scan space point set to obtain the instant point cloud calibration matrix;

[0054] Step S4: Control the five-axis moving platform to move and obtain the scan data of the measured part in different poses;

[0055] Step S5: Based on the calibrated measuring device, automatically complete the high-quality three-dimensional model reconstruction of the multi-pose scan of the measured part according to the scan data and the instant point cloud calibration matrix.

[0056] In some feasible embodiments, in S2.3, it specifically includes:

[0057] Construct a kinematic model, and this kinematic modeling refers to Figure 2 :

[0058] According to the influence on the end, the five-axis platform can be divided into translation axes and rotation axes. Since the translation motion of the machine tool does not affect the rotation motion, a model is established for the translation axes first as follows:

[0059]

[0060] Among them, a 11 、a 12 、a 13 、a 21 、a 22 、a 23 、a 31 、a 32 、a 33 are 9 parameters related to the yaw coefficient, and the yaw coefficient describes the yaw degree of each translation axis; k 1 、k 2 、k 3 are 3 parameters related to the pulse motion ratio, and the pulse motion ratio describes the proportional relationship between the amount of motion per unit pulse of the encoder feedback and the machine vision measurement value; X, Y, Z are the encoder feedback amounts, and the encoder feedback amounts describe the amount of motion of the end along each axis direction; x, y, z are 3 parameters related to the initial deviation, and the initial deviation describes the deviation in the X, Y, Z directions between the origin of the base coordinate system established by the hand-eye relationship and the actually selected machine tool origin. Taking the five-axis moving platform cited in this article as an example, the intersection of the A axis and the C axis is selected as the machine tool origin.

[0061] Simplify the above formula to obtain:

[0062]

[0063] The following model is established for the transmission relationship between the translation axis and the rotation axis:

[0064]

[0065] Where A is the encoder feedback of rotation about the X-axis direction, a is the initial deviation of rotation about the X-axis direction, and γ and θ are the two rotational degrees of freedom required for the transmission between the translation axis coordinate system and the rotation axis coordinate system.

[0066] The following model is established for the transmission relationship between the rotation axes:

[0067]

[0068] Where C is the encoder feedback of rotation about the Z-axis direction, c is the initial deviation of rotation about the Z-axis direction, and d 4 is the length of the connecting rod between the rotation axes.

[0069] Finally, by combining the above formulas, the kinematic model can be obtained:

[0070]

[0071] Construct a kinematic error model:

[0072] All the structural parameters of the moving platform in the aforementioned kinematic model are fixed values except for X, Y, Z, A, and C, and the theoretical values determined by relying on the three-dimensional model of the platform are used. Since it is inevitable to introduce errors during the manufacturing and assembly of the platform, these theoretical values may all have errors, resulting in the deviation of the results calculated from the structural parameters of the moving platform from the actual motion results. Therefore, it is necessary to construct a kinematic error model for the five-axis moving platform and calibrate the structural parameters of the moving platform containing error terms. Thus, the error model is as follows:

[0073]

[0074]

[0075]

[0076]

[0077] It can be seen from the above formula that the kinematic error model contains 17 error terms.

[0078] In some feasible embodiments, in S2.4 and S2.5:

[0079] First, the central point P of the line structured light stripe in the camera coordinate system is calculated through the camera internal parameter matrix and the light plane equation in the camera coordinate system. camera , and then relying on the hand-eye transformation matrix and the kinematic model the three-dimensional point cloud is transformed to the end-effector coordinate system of the platform, and the spherical surface arc point cloud P in the end-effector coordinate system is obtained. end , and the conversion formula is as follows:

[0080]

[0081] Among them, the camera internal parameter matrix and the light plane equation in the camera coordinate system are obtained through camera calibration and light plane calibration respectively, and there are mature calibration methods, which will not be elaborated here. It should be emphasized that the hand-eye transformation matrix is obtained by the hand-eye calibration method that is orthogonalized after fitting the motion directions of each axis, and no kinematic parameter errors are introduced. In addition, since the actual structural parameter information of the motion platform is not combined during the light plane calibration, it is inevitable that there is a deviation in the light plane calculation, which will affect the calculation accuracy of the single-frame line structured light point cloud. It is necessary to compensate for the error introduced by the insufficient light plane calculation accuracy after calibrating the structural parameters of the motion platform subsequently, so as to ensure the quality of the line structured light three-dimensional reconstruction model.

[0082] Take multi-frame non-collinear point cloud data to calculate the center of the sphere Q. center , and the position of this center of the sphere is used as the initial position, which is also described by the end-effector coordinate system. Using the spherical surface arc point cloud P in the end-effector coordinate system end and the initial center of the sphere Q center The difference between the distance between them and the standard radius r of the standard sphere is used to construct the objective function as follows:

[0083] Δr = ||P end - Q center || 2 - r 2

[0084] In some feasible embodiments, in S2.6:

[0085] The physical meaning of error parameter identification is to minimize the error between the model output and the actual observed data by adjusting the error term. For the objective function proposed in this paper, first, relying on the feedback of each axis encoder and the initial structural parameters of the motion platform, the multi-frame non-collinear three-dimensional point cloud data obtained by scanning the line structured light system is transformed to the end-effector coordinate system of the platform to obtain the theoretical values of the spherical surface arc point cloud in the end-effector coordinate system:

[0086]

[0087] Calculate the center of the sphere using the above theoretical values. The position of this center of the sphere as the initial position may contain error amounts Δx, Δy, and Δz in the XYZ directions.

[0088] Then, relying on the feedback of each axis encoder and the structural parameters of the moving platform with error, all the three-dimensional point clouds obtained by the line structured light system are transferred to the coordinate system of the platform end, and the measured values of the arc point clouds on the spherical surface in the end coordinate system are obtained:

[0089]

[0090] Since the arc point clouds on the spherical surface are distributed on the spherical surface and are all constrained by the standard sphere radius and the sphere center, all the observed data can be directly involved in the identification after the point set is monomerized. The expression of the point set monomerization is:

[0091]

[0092] where p represents a single point, P represents a point set, and q center represents the initial sphere center point determined by relying on multiple frames of line-scanned point clouds. Then p end represents the point obtained by solving the data acquired by the line scan in the end coordinate system, represents the point set of all the measured values obtained by the line structured light scan, and ε is a small quantity.

[0093] Meanwhile, due to the existence of the rotation axes A and C of the five-axis moving platform, under their influence, when using the scanned point clouds in multiple poses to jointly solve the standard sphere center, the interference caused by the calculation accuracy of the three-dimensional point clouds of the line structured light can be minimized as much as possible to ensure the effectiveness of the identification. This can avoid the problem that when the calculation accuracy of the single-frame line structured light point cloud in the three-dimensional point cloud is insufficient, the calculation of the sphere center of each piece of point cloud deviates from the actual situation, resulting in the difficulty of accurately identifying each error parameter. After monomerizing the measured value point set and the unique element of the initial sphere center point set is substituted into the objective function and converted into matrix form: Substitute it into the objective function and convert it into matrix form:

[0094]

[0095] where N is the size of the point set, J k is the error matrix, calculated based on all the observed data, Δq is the vector of error parameters to be solved, including 3 items carried by the initial sphere center and 17 items covered by the structural parameters of the moving platform with error, a total of 20 error parameters. By using the influence of the initial sphere center error and the structural parameter errors of each moving platform on the measured sphere center and measured radius of the standard sphere, these 20 error parameters can be identified through the identification algorithm, thus completing the kinematic calibration.

[0096] In some feasible embodiments, step S3 specifically includes:

[0097] Due to the presence of two rotating axes, namely the A-axis and the C-axis, in the five-axis motion platform, the position of the center of the standard sphere obtained by jointly fitting the arc point clouds on the sphere surface at each pose is not easily affected by the calculation accuracy of the line structured light three-dimensional point cloud. Therefore, the position of the center of the standard sphere after kinematic calibration can be used as the ideal center of the sphere. Meanwhile, since the calculation accuracy of the line structured light three-dimensional point cloud is mainly affected by the calculation accuracy of the light plane, when the light plane equation obtained through light plane calibration does not completely coincide with the actual light plane, it will bring about position deviations in the XYZ directions of the line structured light three-dimensional point cloud calculation. This position deviation can be compensated after calibration by a diagonal matrix with error terms. The schematic diagram of this deviation is referred to Figure 3 . Thus, the present invention uses the position of the ideal center of the sphere and the standard radius r of the standard sphere as constraints to achieve the calibration of the spatial position relationship of the line scanning point set, thereby improving the reconstruction accuracy of the three-dimensional point cloud model. The objective function used for calibration is as follows:

[0098]

[0099] where is the position of the center of the standard sphere after kinematic calibration, i.e., the position of the ideal center of the sphere, is the measured value of the three-dimensional point cloud of the arc on the sphere surface in the end coordinate system, which is composed of the initial values x, y, z of the point cloud coordinates and the position calibration diagonal matrix . The elements on the diagonal of the diagonal matrix are the position error coefficient terms s 1 , s 2 , s 3 , that is, . The error model of

[0100]

[0101] By using the identification algorithm to identify these three error parameters, the real-time point cloud position calibration matrix can further improve the absolute accuracy of the line scanning point set and the reconstruction accuracy of the three-dimensional point cloud model.

[0102] In some feasible embodiments, step S5 specifically includes:

[0103] After completing the above kinematic calibration and point cloud position calibration, both the motion accuracy of the platform and the absolute accuracy of the line scanning point set are guaranteed. Thus, by controlling the motion of each axis of the five-axis platform, the scanning data at different poses of the measured part is obtained, and using the camera internal parameter matrix and the light plane equation in the camera coordinate system, the three-dimensional information of the center point of the line structured light stripe in the camera coordinate system is calculated. Through the hand-eye transformation matrix the inverse kinematic transformation matrix after kinematic calibration and the position calibration matrix Transfer the scanned point cloud at each pose to the end - effector coordinate system to obtain a high - precision three - dimensional point cloud that conforms to the morphology of the workpiece to be measured. Automatically complete the high - quality three - dimensional model reconstruction of the multi - pose scanning of the workpiece to be measured.

[0104]

[0105] As Figure 4 shown, a three - dimensional reconstruction system includes:

[0106] A device fixing module, used to rigidly combine the area array camera and the one - dimensional line structured light emitter and install them on the five - axis motion platform to obtain a measuring device;

[0107] A calibration module, using the standard value of the standard ball radius and the line structured light scanning data to calibrate the structural parameters of the motion platform of the measuring device to obtain a calibrated measuring device;

[0108] A point cloud calibration module, with the center position of the calibrated standard ball and the standard radius of the standard ball as constraints, calibrating the spatial position relationship of the line - scanned point set to obtain an instant point cloud calibration matrix;

[0109] A scanning module, used to control the movement of the five - axis motion platform and obtain the scanning data of the workpiece to be measured at different poses;

[0110] A point cloud reconstruction module, based on the calibrated measuring device, using the scanning data and the instant point cloud calibration matrix to automatically complete the high - quality three - dimensional model reconstruction of the multi - pose scanning of the workpiece to be measured.

[0111] The content in the above - mentioned method embodiments is applicable to the system embodiments. The functions specifically implemented in the system embodiments are the same as those in the above - mentioned method embodiments, and the beneficial effects achieved are also the same as those in the above - mentioned method embodiments.

[0112] A three - dimensional reconstruction device based on the kinematic calibration of the single - body of the line - structured light point set:

[0113] At least one processor;

[0114] At least one memory, used to store at least one program;

[0115] When the at least one program is executed by the at least one processor, the at least one processor implements the three - dimensional reconstruction method based on the kinematic calibration of the single - body of the line - structured light point set as described above.

[0116] The content in the above - mentioned method embodiments is applicable to the device embodiments. The functions specifically implemented in the device embodiments are the same as those in the above - mentioned method embodiments, and the beneficial effects achieved are also the same as those in the above - mentioned method embodiments.

[0117] A storage medium stores instructions executable by a processor, and the instructions executable by the processor, when executed by the processor, are used to implement the three-dimensional reconstruction method based on the monomerization kinematic calibration of the line structure light point set as described above.

[0118] The content in the above method embodiments is applicable to the present storage medium embodiment. The functions specifically implemented by the present storage medium embodiment are the same as those of the above method embodiments, and the beneficial effects achieved are also the same as those of the above method embodiments.

[0119] The above is a specific description of the preferred embodiment of the present invention, but the present invention is not limited to the described embodiment. Those skilled in the art can make various equivalent deformations or substitutions without departing from the spirit of the present invention, and these equivalent deformations or substitutions are all included in the scope defined by the claims of this application.

Claims

1. A three-dimensional reconstruction method based on the kinematic calibration of a line structured light point set, characterized in that: The following steps are involved: The area array camera and the one-line structured light emitter are rigidly combined and mounted on a five-axis motion platform to obtain a measuring device; The five axes of the five-axis motion platform include an X-axis, a Y-axis, a Z-axis, a rotation axis rotating around the X-axis direction, and a rotation axis rotating around the Y-axis direction; Using the standard value of the standard sphere radius and the line structured light scanning data, calibrate the structural parameters of the motion platform of the measuring device to obtain a calibrated measuring device; Taking the calibrated center position of the standard sphere and the standard radius of the standard sphere as constraints, the spatial position relationship of the line scan point set is calibrated to obtain the instant point cloud calibration matrix; Controlling the movement of the five-axis motion platform and acquiring scanning data of the measured object in different positions and postures; Based on the calibrated measuring device, the scanning data and the real-time point cloud calibration matrix are used to complete the high-quality three-dimensional model reconstruction of the multi-pose scanning of the measured object.

2. According to claim 1, a three-dimensional reconstruction method based on the individual kinematic calibration of a line structured light point set is characterized in that: The step of calibrating the motion platform structural parameters of the measuring device by using the standard value of the standard sphere radius and the line structured light scanning data to obtain the calibrated measuring device specifically includes: Fix the standard ball at the center of the flange at the end of the five-axis motion platform; Controlling the movement of the five-axis motion platform and acquiring scanning data of the standard ball in different positions and postures; According to the influence of each axis of the five-axis motion platform on the end, the kinematic model and kinematic error model are constructed, and the error parameter items are determined; Solve the spherical arc point cloud in the terminal coordinate system and take multiple frames of point cloud to fit the sphere center to obtain the initial sphere center position; Constructing an objective function based on the three-dimensional information of the spherical arc point cloud, the initial sphere center position and the standard radius of the standard sphere; Based on the objective function, all point sets of the spherical arc point cloud are monomerized and directly involved in error identification, so as to complete the calibration of the motion platform structure parameters and obtain the calibrated measuring device.

3. The three-dimensional reconstruction method based on the kinematic calibration of a line structured light point set according to claim 2, characterized in that: The kinematic model is expressed as follows: in, represents the overall kinematic model, represents the translation axis model, Represents the transfer relationship model between the translation axis and the rotation axis, Represents the transmission relationship model between the rotating axes, A is the encoder feedback around the X-axis, a is the initial deviation around the X-axis, γ and θ are the two rotational degrees of freedom required for the transmission between the translation axis coordinate system and the rotation axis coordinate system, C is the encoder feedback around the Z-axis, c is the initial deviation around the Z-axis, d4 is the length of the connecting rod between the rotating axes; b 11 、b 12 、b 13 are three proportional coefficients related to the X-axis yaw coefficient and pulse motion ratio, b 21 、b 22 、b 23 are three proportional coefficients related to the Y-axis yaw coefficient and pulse motion ratio, b 31 、b 32 and b 33 are three proportional coefficients related to the Z-axis runout coefficient and pulse motion ratio; d1, d2, d3 are the origin deviations in the X-axis, Y-axis, and Z-axis directions respectively; X, Y, and Z represent the encoder feedback values ​​of the corresponding axes.

4. The three-dimensional reconstruction method based on the kinematic calibration of a line structured light point set according to claim 2, characterized in that: The objective function is expressed as follows: Δr=||P end -Q center || 2 -r 2 Among them, Q center represents the initial sphere center of the fitting, P end It represents the spherical arc point cloud in the terminal coordinate system, and r represents the standard radius of the standard sphere.

5. The three-dimensional reconstruction method based on the individual kinematic calibration of line structured light point set according to claim 4, characterized in that: The conversion formula of the spherical arc point cloud in the terminal coordinate system is as follows: in, represents the hand-eye transformation matrix, P camera Indicates the center point of the line structured light stripe in the camera coordinate system.

6. The three-dimensional reconstruction method based on the individual kinematic calibration of line structured light point set according to claim 2, characterized in that: Take multiple frames of non-collinear spherical arc point cloud data to fit the center of the sphere.

7. The three-dimensional reconstruction method based on the kinematic calibration of a line structured light point set according to claim 2, characterized in that: The step of completing high-quality three-dimensional model reconstruction of the multi-pose scan of the measured object based on the calibrated measuring device using the scanning data and the real-time point cloud calibration matrix specifically includes: Based on the calibrated measuring device, according to the camera intrinsic parameter matrix and the light plane equation in the camera coordinate system, the three-dimensional information of the center point of the line structured light stripe in the camera coordinate system is solved; By combining the hand-eye transformation matrix, the calibrated inverse kinematic transformation matrix and the real-time point cloud calibration matrix, the scanning data of the test piece in different postures are converted to the terminal coordinate system, and high-quality three-dimensional model reconstruction of the test piece in multi-posture scanning is automatically completed.

8. A three-dimensional reconstruction system, characterized in that: The method for performing the three-dimensional reconstruction based on the linear structured light point set monomerized kinematic calibration as claimed in claim 1 comprises: A device fixing module is used to rigidly combine the area array camera and the one-line structured light emitter, and install them on a five-axis motion platform to obtain a measuring device; A calibration module, using a standard value of a standard sphere radius and line structured light scanning data to calibrate the structural parameters of the motion platform of the measuring device to obtain a calibrated measuring device; The real-time point cloud calibration module uses the calibrated center position of the standard sphere and the standard radius of the standard sphere as constraints to calibrate the spatial position relationship of the line scan point set and obtain the real-time point cloud calibration matrix; A scanning module, used to control the movement of the five-axis motion platform and obtain scanning data of the measured object in different positions and postures; The point cloud reconstruction module completes high-quality three-dimensional model reconstruction of the multi-pose scanning of the measured object based on the calibrated measuring device and the scanning data and the real-time point cloud calibration matrix.

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