Line laser contourgraph data consistency evaluation method and device

Abstract

The invention relates to a line laser contourgraph data consistency evaluation method and device which are applied to the field of optical precision measurement, and the method comprises the steps: obtaining point cloud data generated when a line laser contourgraph scans a measured plane of a measured target object; determining a spatial relationship between the measured plane and an ideal horizontal plane based on the point cloud data; determining an ideal horizontal plane based on an optical axis formed by a line laser profiler; constructing a rotation matrix between the original coordinate system of the point cloud data and the coordinate system of the ideal horizontal plane according to the spatial relationship between the measured plane and the ideal horizontal plane; correcting the point coordinate of the original laser line in the point cloud data through the rotation matrix to obtain the corrected point coordinate of the laser line; and evaluating the data consistency of the line laser contourgraph based on the corrected point coordinates of the laser lines. According to the invention, the problem that the accuracy of the consistency evaluation of the overall line laser data measured by the line laser contourgraph needs to be improved is solved.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of optical precision measurement, in particular to a line laser profiler data consistency evaluation method and device. BACKGROUND

[0002] The line laser profiler is a high-precision measuring device, widely used in industrial detection, reverse engineering, quality control and other fields. It emits a narrow-band laser to the surface of the measured object, and uses a sensor to capture the profile image formed by the laser line on the surface of the object, and then calculates the three-dimensional shape information of the object.

[0003] In the current line laser data measurement method based on the line laser profiler, a repeatability evaluation method for a single point on the laser line is specified, which mainly calculates the standard deviation through the Bezier formula to represent the stability of a single point. However, in actual application, the measurement stability of the entire laser line needs to be ensured, and the evaluation of single point stability cannot completely represent the consistency (i.e. linearity) of the overall data. At the same time, in actual application, the installation of the line laser profiler cannot be completely perpendicular to the measured plane to achieve the ideal state, and the tilt between the measured plane and the installation plane of the line laser profiler will introduce the deviation of the coordinate system where the instrument is located, thereby polluting the original point cloud data, resulting in inaccurate consistency evaluation results of the line laser profiler.

[0004] In view of the problem that the accuracy of the consistency evaluation of the line laser data measured by the line laser profiler in the related art needs to be improved, no effective solution has been proposed so far. SUMMARY

[0005] A line laser profiler data consistency evaluation method and device are provided in the present embodiment to solve the problem that the accuracy of the consistency evaluation of the line laser data measured by the line laser profiler in the related art needs to be improved.

[0006] In a first aspect, a line laser profiler data consistency evaluation method is provided in the present embodiment, which comprises:

[0007] Obtaining point cloud data generated by a line laser profiler scanning a measured target object on a measured plane;

[0008] Based on the point cloud data, determining the spatial relationship between the measured plane and an ideal horizontal plane;

[0009] According to the spatial relationship between the measured plane and the ideal horizontal plane, a rotation matrix between the original coordinate system of the point cloud data and the coordinate system of the ideal horizontal plane is constructed; the ideal horizontal plane is determined based on the optical axis formed by the line laser profiler;

[0010] The point coordinates of the original laser line in the point cloud data are corrected by the rotation matrix to obtain point coordinates of a corrected laser line.

[0011] Data consistency of the line laser profiler is evaluated based on the point coordinates of the corrected laser line.

[0012] In some embodiments, the method further comprises:

[0013] The original coordinate system is corrected based on the rotation matrix to obtain a target coordinate system;

[0014] The measured target object is scanned by the line laser profiler in the target coordinate system to obtain the point coordinates of the corrected laser line.

[0015] In some embodiments, the determination of the spatial relationship between the measured plane and the ideal horizontal plane based on the point cloud data comprises:

[0016] The point cloud data is sampled at a preset interval to obtain point cloud sampling data;

[0017] A plane fitting parameter equation is obtained by fitting the point cloud sampling data based on a preset random sampling consistency algorithm.

[0018] In some embodiments, the construction of the rotation matrix between the original coordinate system of the point cloud data and the coordinate system in which the ideal horizontal plane is located based on the spatial relationship between the measured plane and the ideal horizontal plane comprises:

[0019] A plane normal vector of the plane fitting parameter equation is determined;

[0020] A rotation angle between the plane normal vector and a preset unit vector is calculated; the preset unit vector is perpendicular to the ideal horizontal plane;

[0021] A three-dimensional vector perpendicular to a spatial plane formed by the plane normal vector and the preset unit vector is determined;

[0022] A rotation matrix is constructed based on the three-dimensional vector and the rotation angle.

[0023] In some embodiments, the correction of the point coordinates of the original laser line in the point cloud data by the rotation matrix to obtain the point coordinates of the corrected laser line comprises:

[0024] Original laser line data in the point cloud data perpendicular to the moving direction of the measured target object is obtained;

[0025] The product of the point coordinates of the original laser line and the rotation matrix is calculated to obtain the point coordinates of the modified laser line.

[0026] In some embodiments, the data consistency of the line laser profiler is evaluated based on the point coordinates of the modified laser line, including:

[0027] A deviation value of the point coordinates of the modified laser line is calculated based on a preset consistency evaluation algorithm.

[0028] An evaluation result of the data consistency of the line laser profiler is determined based on the deviation value.

[0029] In some embodiments, the deviation value of the point coordinates of the modified laser line is calculated based on the preset consistency evaluation algorithm, including:

[0030] A modified coordinate arithmetic mean value of the point coordinates of the modified laser line is obtained.

[0031] The evaluation result is determined according to the coordinate value of each laser point in the modified coordinate arithmetic mean value.

[0032] In a second aspect, a line laser profiler data consistency evaluation device is provided in the embodiment, and the device includes a controller, a line laser profiler and a guide rail; the controller is electrically connected with the guide rail and the line laser profiler.

[0033] A measured target object is fixed on the guide rail; the line laser profiler is configured to scan the measured target object.

[0034] The controller is configured to execute the line laser profiler data consistency evaluation method in the first aspect.

[0035] In a third aspect, an electronic device is provided in the embodiment, which includes a memory, a processor and a computer program stored in the memory and executable on the processor, and the processor executes the computer program to implement the line laser profiler data consistency evaluation method in the first aspect.

[0036] In a fourth aspect, a storage medium is provided in the embodiment, which stores a computer program executable by a processor to implement the line laser profiler data consistency evaluation method in the first aspect.

[0037] Compared with the related art, the consistency evaluation method and device for the line laser profilometer data provided in the embodiment, by acquiring the point cloud data formed by the line laser profilometer scanning the measured target object, constructing the plane fitting equation of the measured plane through the point cloud data, determining the spatial relationship between the measured plane and the ideal horizontal plane based on the plane fitting equation, and then constructing the rotation matrix. Thereafter, based on the rotation matrix, the point cloud data obtained by the line laser profilometer scanning is corrected, so that the corrected laser point coordinates are in the coordinate system in which the ideal horizontal plane is located, and the ideal horizontal plane is perpendicular to the optical axis of the line laser profilometer, thereby realizing the self-calibration of the line laser point cloud data; and based on the corrected laser point coordinates, the consistency of the line laser data of the line laser profilometer is evaluated. Through the above self-correction method, the installation tilt error is eliminated, and the accuracy of the consistency evaluation of the line laser data is improved.

[0038] The details of one or more embodiments of the present application are presented in the following drawings and description to make other features, objects and advantages of the present application more apparent. BRIEF DESCRIPTION OF DRAWINGS

[0039] The drawings described herein are intended to provide further understanding of the present application, and form a part of the present application. The illustrative embodiments of the present application and their description serve to explain the present application, and do not constitute an improper limitation of the present application. In the drawings:

[0040] Figure 1 is a data evaluation device for a line laser profilometer provided by the embodiment of the present application;

[0041] Figure 2 is a flowchart of the consistency evaluation method for line laser profilometer data provided by the embodiment of the present application;

[0042] Figure 3 is a flowchart of the consistency evaluation method for line laser profilometer data based on plane fitting and coordinate transformation of the present embodiment;

[0043] Figure 4 is a flowchart of the rotation matrix construction method provided by the present embodiment;

[0044] Figure 5 is a hardware structure block diagram of the terminal of the consistency evaluation method for line laser profilometer data provided by the embodiment.

[0045] Reference signs: 1, line laser profilometer; 2, marble ruler; 3, guide rail; 102, processor; 104, memory; 106, transmission device; 108, input and output device. DETAILED DESCRIPTION

[0046] In order to clearly understand the purpose, technical solutions and advantages of the present application, the present application is described and explained below in conjunction with the accompanying drawings and examples.

[0047] Unless otherwise defined, technical terms or scientific terms used in the present application shall have the general meaning understood by a person with ordinary skill in the art to which the present application belongs. In the present application, "one", "a", "an", "the", "these" and similar words do not represent a quantitative limitation, and they can be singular or plural. In the present application, the terms "include", "contain", "have" and any variants thereof have the purpose of covering non-exclusive inclusion; for example, a process, method and system, product or device containing a series of steps or modules (units) are not limited to the listed steps or modules (units), but can include steps or modules (units) not listed, or can include other steps or modules (units) inherent to the process, method, product or device. In the present application, the terms "connected", "connected", "coupled" and similar words are not limited to physical or mechanical connections, but can include electrical connections, whether direct or indirect. In the present application, "multiple" means two or more. "And / or" describes the relationship between the associated objects, which means that there can be three relationships, for example, "A and / or B" can mean that A exists alone, A and B exist together, and B exists alone. In general, the character " / " represents an "or" relationship between the associated objects. In the present application, the terms "first", "second", "third" and the like are only used to distinguish similar objects, and do not represent a specific order for the objects.

[0048] The principle of the line laser profiler is based on laser triangulation. By emitting a line laser to the surface of the measured object, the reflected light signal is received and converted into three-dimensional coordinate data. Specifically, the line laser profiler projects a thin and narrow laser line on the surface of the object to be measured by a laser. When the laser line irradiates the surface of the object, due to the different shapes of the surface of the object, the laser line will be deformed. This deformed laser line image is captured by a camera (usually a CCD or CMOS sensor) in the profiler. Based on the principle of triangulation, the relative position relationship between the laser source and the camera is known, and the displacement of the laser line in the camera field of view can be calculated by geometric relationship to obtain the height information of each point on the surface of the object relative to the reference plane. Specifically, the height difference of the corresponding points on the surface of the object is calculated by using the properties of similar triangles.

[0049] In the process of line laser data collection, first, the object to be measured is placed in the measurement area of the line laser profiler, and then the measurement program of the line laser profiler is started, and the line laser profiler starts to emit a laser line for scanning. As the laser line moves on the surface of the object, the camera continuously captures a series of laser line image. The acquired raw image data is processed by software and converted into three-dimensional coordinate data. This step may include preprocessing steps such as denoising and feature extraction, as well as applying specific algorithms to convert into high-precision three-dimensional models. The final three-dimensional data can be used for further analysis, such as dimension inspection, reverse engineering design, etc.

[0050] In the prior art, by measuring the same position multiple times, only the repeatability of a single point is evaluated, and the consistency of the entire laser line measurement result cannot be guaranteed. At the same time, due to the difficulty in completely perpendicular installation of the line laser profiler to the measured plane during actual installation, an inclination will be generated, which will cause a deviation between the coordinate system of the line laser profiler and the measured plane, and further pollute the original data. The traditional method does not eliminate such system error, resulting in distorted evaluation results.

[0051] In order to solve the problem that the consistency evaluation accuracy of the line laser data measured by the line laser profiler needs to be improved, a line laser profiler data consistency evaluation device is provided in the embodiment, which comprises a controller, a line laser profiler and a guide rail. The controller is electrically connected with the guide rail and the line laser profiler; the guide rail is fixed with a measured target object; the line laser profiler is used for scanning the measured target object.

[0052] In order to solve the problem that the consistency evaluation accuracy of the line laser data measured by the line laser profiler needs to be improved, a line laser profiler data consistency evaluation device is provided in the embodiment, which comprises a controller, a line laser profiler and a guide rail. The controller is electrically connected with the guide rail and the line laser profiler; the guide rail is fixed with a measured target object; the line laser profiler is used for scanning the measured target object.

[0053] As an implementation manner, when the consistency evaluation device using the line laser profiler data is used, the measured target object is placed in the measurement area, and then the controller starts the measurement program to control the straightly-slidable guide rail to drive the measured target object to move uniformly in the measurement area. During the uniform movement of the measured target object, the line laser profiler starts to emit a laser line to scan the plane of the measured target object. Figure 1 is a data evaluation device of a line laser profiler provided by the embodiment of the present application. In the device, the measured target object is specifically a standard device used in the quality detection and evaluation process of the line laser profiler, for example Figure 1 In the device, the standard device is a marble ruler 2, and the measured surface of the measured target object is the working surface of the marble ruler 2. The working surface is a high-precision plane, and the flatness error generated in the quality detection and evaluation process can be directly ignored. The marble ruler 2 is slidably arranged on a guide rail 3, which is specifically a high-precision straight guide rail 3, and can drive the marble ruler 2 to move uniformly and straightly. The controller is not shown in Figure 1 .

[0054] As shown in Figure 1 , the device is arranged on a workbench, the line laser profiler 1 is arranged at the uppermost position in the device, is perpendicular to the surface of the measured object, is fixed on a support or gantry, and has a laser emission port downwardly emitting a laser line to the marble ruler 2 below to scan the surface profile of the object and generate 3D point cloud data in real time. The high-precision marble ruler 2 is driven to move uniformly by the moving guide rail 3, and the line laser profiler 1 is responsible for scanning the surface of the marble ruler 2 to generate point cloud data. Then, the controller receives the point cloud data, and performs high-precision consistency evaluation on the line laser profiler data based on a consistency evaluation method according to the point cloud data.

[0055] The line laser profiler data consistency evaluation method provided by the embodiment of the present application is specifically a line laser profiler data consistency evaluation method based on plane fitting and coordinate transformation. Figure 2 is a flowchart of the line laser profiler data consistency evaluation method provided by the embodiment of the present application, as shown in Figure 2 , the flowchart includes the following steps S210 to S250.

[0056] In step S210, point cloud data generated by the line laser profiler scanning the measured plane of the measured target object is obtained.

[0057] For example, in the data evaluation device of the line laser profiler, the controller controls the high-precision straight guide rail to drive the marble ruler to move uniformly, and the movement path of the marble ruler is located in the measurement range of the line laser profiler. The line laser profiler scans the surface of the marble ruler to generate point cloud data. The point cloud data includes three-dimensional information of the surface of the marble ruler.

[0058] Step S220, based on the point cloud data, determine the spatial relationship between the measured plane and the ideal horizontal plane. The ideal horizontal plane is determined based on the optical axis formed by the line laser profiler.

[0059] Specifically, a preset random sample consensus algorithm (RANSAC) can be used to iteratively select the minimum point set (such as three points) from the point cloud data to fit the candidate plane model, calculate the vertical distance of all data points to the plane, and based on the candidate plane model, determine the optimal plane equation parameters by maximizing the number of inliers; wherein, the ideal horizontal plane is mainly determined based on the optical axis formed by the line laser profiler, as can be known from the device in Figure 1 , the optical axis formed by the line laser profiler is set as the z-axis, so the ideal horizontal plane can be understood as a plane perpendicular to the optical axis formed by the line laser profiler, i.e. a plane perpendicular to the z-axis in the rectangular coordinate system in Figure 1 , i.e. a horizontal plane of the x-axis and y-axis travel. Then, according to the optimal plane equation parameters, the spatial relationship between the measured plane, i.e. the actual marble ruler plane, and the ideal horizontal plane can be determined. According to the spatial relationship, a basis is provided for subsequent consistency evaluation of the line laser profiler data.

[0060] Step S230, according to the spatial relationship between the measured plane and the ideal horizontal plane, construct a rotation matrix between the original coordinate system of the point cloud data and the coordinate system where the ideal horizontal plane is located.

[0061] Wherein, after determining the spatial relationship between the measured plane and the ideal horizontal plane based on the point cloud data, the rotation matrix between the original coordinate system of the device where the actual point cloud data is collected and the ideal coordinate system where the ideal horizontal plane is located can be constructed based on the spatial relationship, the normal vectors of different planes, the preset unit vector and the unit matrix, etc., and the original coordinate system is rotated to a new coordinate system perpendicular to the ideal horizontal plane.

[0062] The original coordinate system here can be understood as the coordinate system when the line laser profiler scans the point cloud data in Figure 1 , which is determined based on the installation position of the line laser profiler and the measured plane of the marble ruler. In actual application, since the measured surface of the marble ruler is not consistent with the ideal horizontal plane perpendicular to the z-axis of the light emitted by the line laser profiler, it is necessary to construct a rotation matrix based on the point cloud data and the ideal horizontal plane, and then correct the original coordinate system.

[0063] Step S240, correct the point coordinates of the original laser line in the point cloud data through the rotation matrix to obtain the point coordinates of the corrected laser line.

[0064] When the rotation matrix corresponding to the line laser profiler in the current device is determined, the point coordinates of the original laser line in the point cloud data are extracted, and the point coordinates of the original laser line are corrected based on the rotation matrix. Specifically, the product of the three-dimensional coordinates and the three-dimensional matrix is calculated to obtain the point coordinates of the corrected laser line.

[0065] Further, the original coordinate system can also be corrected based on the rotation matrix to obtain a target coordinate system. In the target coordinate system, the measured target object is scanned by the line laser profiler to obtain the point coordinates of the corrected laser line. It can be understood that the rotation matrix can directly correct the point coordinates of the original laser line to obtain the point coordinates of the corrected laser line, or correct the original coordinate system to obtain the point coordinates of the corrected laser line in the target coordinate system.

[0066] In step S250, the data consistency of the line laser profiler is evaluated based on the point coordinates of the corrected laser line.

[0067] Since the point coordinates of the corrected laser line can be understood as the laser line formed by the laser points scanned by the line laser profiler in the data consistency evaluation device of the line laser profiler without installation tilt error in the ideal state, the consistency of the current line laser profiler is calculated based on the point coordinates of the corrected laser line, and then whether the actual data of the line laser profiler has consistency is evaluated based on the result of the consistency calculation, specifically the consistency of the point coordinates of the corrected laser line in the height perpendicular to the measured surface of the marble ruler, i.e. the z-axis.

[0068] Exemplarily, the data consistency is evaluated by a consistency evaluation algorithm including the Bezier algorithm and the range method, which is not specifically limited here.

[0069] Through the above steps, the point cloud data formed by the line laser profiler scanning the measured target object is obtained, the plane fitting equation of the measured plane is constructed from the point cloud data, the spatial relationship between the measured plane and the ideal horizontal plane is determined based on the plane fitting equation, and then the rotation matrix is constructed according to the plane fitting equation, and the point cloud data scanned by the line laser profiler is corrected based on the rotation matrix, so that the corrected laser point coordinates are in the coordinate system of the ideal horizontal plane, which is perpendicular to the optical axis of the line laser profiler, realizing the self-calibration of the line laser point cloud data. The installation tilt error is eliminated by the above self-correction method, and the accuracy of the line laser data consistency evaluation is improved.

[0070] In some embodiments, in step S220, the spatial relationship between the measured plane and the ideal horizontal plane is determined based on the point cloud data, including: sampling the point cloud data at a preset interval to obtain point cloud sampling data; and performing plane fitting on the point cloud sampling data based on a preset random sample consensus algorithm to obtain a plane fitting parameter equation.

[0071] In some embodiments, the on-line laser profilometer scans the measured surface of the marble ruler, and after obtaining the three-dimensional point cloud data, the point cloud data is sampled at a preset interval to obtain a plurality of point cloud sampling data. For example, the preset interval can be 1mm, 2mm, etc. The plurality of point cloud sampling data obtained by sampling should not be too small, and generally should be more than 100 points.

[0072] Then, the plane fitting parameter equation is obtained by performing plane fitting on the point cloud sampling data based on a preset random sample consensus algorithm. Specifically, the RANSAC (RANdom SAmple Consensus) algorithm is used to fit the plane equation. RANSAC is a classic robust estimation method, mainly used for estimating the parameters of a mathematical model from data containing outliers. The plane fitting parameter equation obtained by using the RANSAC algorithm can be expressed as:

[0073] ;

[0074] Wherein, a, b, c, d are fitting parameters; x, y and z represent the coordinate values of the point cloud sampling data in the three-dimensional rectangular coordinate system, i.e. the original coordinate system.

[0075] The plane fitting parameter equation can be used to determine the spatial relationship between the actual measured plane and the ideal horizontal plane, which provides a basis for subsequent error analysis and correction.

[0076] In some embodiments, a rotation matrix between the original coordinate system of the point cloud data and the coordinate system in which the ideal horizontal plane is located is constructed according to the spatial relationship between the measured plane and the ideal horizontal plane, including: determining a plane normal vector of the plane fitting parameter equation; calculating a rotation included angle between the plane normal vector and a preset unit vector; the preset unit vector is perpendicular to the ideal horizontal plane; determining a three-dimensional vector perpendicular to the spatial plane formed by the plane normal vector and the preset unit vector; and constructing the rotation matrix based on the three-dimensional vector and the rotation included angle.

[0077] In this embodiment, after determining the plane fitting parametric equation that can characterize the spatial relationship between the measured plane and the ideal horizontal plane, the plane normal vector n = (a, b, c) is determined based on the fitting parameters a, b, and c in the plane fitting parametric equation. Then, the angle between the normal vector and the unit vector perpendicular to the ideal horizontal plane is calculated.

[0078] For example, refer to Figure 1 In the coordinate system, the unit vector here can be the unit vector (0,0,1) in the z-axis direction.

[0079] Then, the rotation angle between the normal vector and the unit vector is calculated; after obtaining the rotation angle, the rotation axis vector K, i.e. the three-dimensional vector, is determined based on the fitting parameters a and b, which are perpendicular to the spatial plane formed by the plane normal vector and the unit vector.

[0080] Finally, a skew-symmetric matrix is ​​constructed based on the rotation axis vector K. A rotation matrix is ​​then constructed based on this skew-symmetric matrix, the identity matrix, and the rotation angle. The original coordinate system is rotated to a new target coordinate system that includes an ideal horizontal plane perpendicular to the laser axis formed by the line laser profilometer.

[0081] Point cloud data of the measured plane is obtained by emitting a laser through a line laser profilometer. The rotation matrix between the original coordinate system of the point cloud data and the coordinate system of the ideal horizontal plane is calculated. Based on the rotation matrix, the original coordinate system of the point cloud data is self-calibrated and corrected to the ideal target coordinate system. These steps help eliminate tilt errors caused by the difficulty of perfectly perpendicular installation of the line laser profilometer to the measured plane; and by correcting the original coordinate system to the ideal target coordinate system, the accuracy of subsequent data consistency checks is improved.

[0082] In some embodiments, the point coordinates of the original laser line in the point cloud data are corrected by a rotation matrix to obtain the corrected point coordinates of the laser line. This includes: acquiring the original laser line data in the point cloud data in the direction perpendicular to the movement of the target object; and calculating the matrix product of the point coordinates of the original laser line and the rotation matrix to obtain the corrected point coordinates of the laser line.

[0083] For example, in such Figure 1 In the Cartesian coordinate system of the device shown, the point coordinate data of the original laser line includes point cloud data in the direction of movement perpendicular to the target object, with a fixed value on the y-axis. For example, point cloud coordinate data perpendicular to the direction of movement of the guide rail driving the marble ruler, with y=1. The y value here is not limited to a fixed value and can also be 0, 2, 3, etc., without specific limitation.

[0084] In some embodiments, the data consistency of the line laser profiler is evaluated based on the point coordinates of the corrected laser line, including: calculating a deviation value of the point coordinates of the corrected laser line based on a preset consistency evaluation algorithm; determining an evaluation result of the data consistency of the line laser profiler based on the deviation value.

[0085] Further, a corrected coordinate arithmetic mean of the point coordinates of the corrected laser line is obtained; and the evaluation result is determined according to the corrected coordinate arithmetic mean and a coordinate value of each laser point in the point coordinates of the corrected laser line.

[0086] In the method, when the point coordinates of the original laser line in the point cloud data are corrected by the rotation matrix, the point coordinates of the corrected laser line are calculated according to the preset consistency evaluation algorithm to obtain the deviation value.

[0087] Specifically, the experimental standard deviation of the z direction in all the point coordinates of the corrected laser line is calculated by using the Bezier algorithm. Further, the evaluation result of the data consistency of the line laser profiler is determined according to the deviation value.

[0088] If the current deviation value is within the preset deviation range, it indicates that the laser line data generated by the line laser profiler has consistency, and the product quality of the line laser profiler is high. If the current deviation value is outside the preset deviation range, it indicates that the consistency of the laser line data generated by the line laser profiler is poor, and the line laser profiler needs to be returned to the manufacturer for processing.

[0089] The present embodiment will be described and explained in detail through specific embodiments.

[0090] Figure 3 is a flowchart of a line laser profiler data consistency evaluation method based on plane fitting and coordinate transformation according to the present embodiment, as shown in Figure 3 The method includes the following steps:

[0091] Step S310, data acquisition and plane fitting.

[0092] Specifically, the step of acquiring the point cloud data includes: controlling the high-precision linear guide to move at a constant speed by the controller, and driving the marble ruler to move at a constant speed by the high-precision linear guide; acquiring three-dimensional point cloud data by the line laser profiler scanning the surface of the marble ruler moving at a constant speed; equally sampling the three-dimensional point cloud data; and then, fitting a plane equation by using the RANSAC algorithm for the three-dimensional point cloud data obtained by equally sampling.

[0093] Exemplarily, in the case that the marble flat ruler is measured to the flatness of the working surface of the standardizer reaches 0.8 μm, and the size is 100 mm x 100 mm, the demand of high-precision measurement can be met; the component is the core component of the entire measurement system, and the high flatness ensures the accuracy of the measurement. The high-precision linear guide rail has a repeat positioning accuracy of ±1 μm and a speed of 30 mm / s, ensuring the stable movement of the marble flat ruler; the guide rail ensures that the marble flat ruler can move at an accurate speed and direction, which is crucial for the accuracy of subsequent point cloud data acquisition; the line laser profiler has a Z-direction accuracy of up to 5 μm and a scanning frequency of up to 10 kHz, which can quickly and accurately obtain the point cloud data of the measured surface of the marble flat ruler; with reference to Figure 1 , the device is fixedly installed on the support and is responsible for scanning the measured surface of the flat ruler to generate point cloud data for subsequent analysis. The controller (including a plane fitting and coordinate transformation module) is responsible for processing the point cloud data obtained by scanning and performing key consistency calculation tasks such as plane fitting and coordinate transformation on the point cloud data.

[0094] The guide rail and the flat ruler are rigidly connected to ensure the stability of the movement of the flat ruler; the line laser profiler communicates with the controller through a data line or wirelessly, ensuring that the point cloud data obtained by the line laser profiler can be accurately transmitted to the controller in real time for analysis.

[0095] In the case that the running speed of the guide rail is 30 mm / s and the scanning range of the line laser profiler is 110 mm x 110 mm, the total number of point cloud data obtained is greater than 3 million, and the distance between every two adjacent point cloud data is 0.056 mm.

[0096] Subsequently, the point cloud data is equally sampled at a predetermined interval to obtain 1000 sampling point data, and the sampling point data is used for RANSAC algorithm plane fitting, and the formed fitting equation is: -0.130 x x + 0.000 x y + 0.992 x z - 260.241 = 0.

[0097] Step S320, coordinate system transformation parameter calculation.

[0098] Specifically, Figure 4 is a flowchart of the rotation matrix construction method provided by the embodiment, with reference to Figure 4 , the rotation matrix construction method comprises steps Q1 to Q4.

[0099] Q1, obtaining a plane normal vector.

[0100] wherein the plane normal vector is determined by the fitting parameters, n=(a, b, c). Specifically, based on the fitting equation obtained in step S310 above, the normal vector is calculated as: n=(-0.130, 0.000, 0.992).

[0101] Q2, calculate the rotation angle. The rotation angle is the angle θ between the normal vector and the z-axis (0, 0, 1).

[0102] wherein the angle is calculated according to the fitting parameters a, b, c, and the formula is:

[0103] ;

[0104] ;

[0105] Based on the normal vector obtained in step Q2 and the fitting equation obtained in step S310, the rotation angle is calculated as cosθ = 0.992 / 1.00048 = 0.9915; sinθ = sqrt(1-0.9915²) = 0.1304.

[0106] Q3, calculate the rotation axis vector k.

[0107] wherein the rotation axis vector k is a three-dimensional vector representing the direction of the rotation axis; the rotation axis vector k is perpendicular to the spatial plane formed by the normal vector n and the z-axis (0, 0, 1).

[0108] Let k = (kx, ky, kz), then kx = b / sqrt(a²+b²); ky = -a / sqrt(a²+b²); kz = 0 can be obtained.

[0109] Q4, construct the rotation matrix R.

[0110] wherein the K matrix is a 3x3 skew-symmetric matrix composed of rotation axis components: the matrix K is represented as:

[0111] ;

[0112] Based on the matrix K, the rotation matrix R is determined, and the formula of R can be represented as:

[0113] ;

[0114] wherein I represents a 3x3 unit matrix; K represents the above skew-symmetric matrix; K² represents the square (KxK) of the K matrix; θ represents the rotation angle.

[0115] Based on the rotation axis vector calculated in Q3 above, the matrix K = [0, 0, -1; 0, 0, 0; 1, 0, 0;] can be obtained; R = I + 0.1304xK + (1-0.9915)xK².

[0116] Step S330, calculate the consistency of the laser line data based on the corrected coordinates.

[0117] Specifically, the point coordinate data in the laser line is extracted, and all point cloud coordinate data P in the laser line perpendicular to the moving direction of the guide rail, y=0, is taken as an example, where y can be set to any value. Where P=[x,y,z] is the original point cloud coordinate on the laser line; the point cloud coordinate data P is corrected by a rotation matrix R, and the calculation formula of the corrected point cloud coordinate P' is:

[0118] ;

[0119] Where R represents the rotation matrix, and P represents the point coordinate of the original laser line in the point cloud coordinate.

[0120] After that, the experimental standard deviation of the z direction (the third parameter) in all corrected P' coordinates is calculated by using the Bezier algorithm:

[0121] ;

[0122] Where, represents the arithmetic mean of the z coordinates of each corrected point, n is the number of effective measurement points, and z i represents the axial coordinate value of the i-th measurement point.

[0123] Based on the actual point cloud data value in the above steps, the experimental standard deviation of the corrected laser line point set coordinate is calculated using the Bezier formula, and finally the standard deviation of the corrected z coordinate is 0.013mm.

[0124] The line laser profiler data consistency evaluation method based on plane fitting and coordinate transformation in the above embodiment can obtain a normal vector by fitting a plane equation from the original point cloud data, and further determine a rotation matrix, and implement a coordinate transformation strategy based on the rotation matrix, effectively eliminating the installation tilt error, and further improving the accuracy of the data consistency evaluation. And suitable for laser profiler systems with any installation angle. By scanning the marble ruler measured plane with high precision plane, and using the integrated plane fitting and matrix operation module, the accuracy of data consistency evaluation is improved.

[0125] The method embodiment provided in the embodiment can be executed in a terminal, a computer or a similar operation device. For example, it is run on a controller, Figure 5 is the hardware structure block diagram of the terminal of the line laser profiler data consistency evaluation method provided in the embodiment. As Figure 5 shown, the controller can include one or more ( Figure 5The terminal shown in the figure only includes one processor 102 and a memory 104 for storing data, wherein the processor 102 can include but is not limited to a processing device such as a microprocessor MCU or a programmable logic device FPGA. The above-mentioned controller can also include a transmission device 106 for communication function and an input and output device 108. Those skilled in the art can understand that Figure 5 The structure shown in the figure is only schematic and does not limit the structure of the terminal. For example, the controller can further include more or less components than those shown in the figure, or have a different configuration from that shown in the figure. Figure 5 The structure shown in the figure is only schematic and does not limit the structure of the terminal. For example, the controller can further include more or less components than those shown in the figure, or have a different configuration from that shown in the figure. Figure 5 The structure shown in the figure is only schematic and does not limit the structure of the terminal. For example, the controller can further include more or less components than those shown in the figure, or have a different configuration from that shown in the figure.

[0126] The memory 104 can be used to store computer programs, such as software programs of application software and modules, such as the computer program corresponding to the consistency evaluation method of the line laser profilometer data in the embodiment. The processor 102 executes various functional applications and data processing by running the computer program stored in the memory 104, that is, implements the above-mentioned method. The memory 104 can include a high-speed random access memory, and can also include a non-volatile memory, such as one or more magnetic storage devices, flash memories, or other non-volatile solid-state memories. In some examples, the memory 104 can further include a memory remotely arranged with respect to the processor 102, and these remote memories can be connected to the terminal through a network. Examples of the above-mentioned network include but are not limited to the Internet, an intranet, a local area network, a mobile communication network, and a combination thereof.

[0127] The transmission device 106 is used to receive or send data via a network. The above-mentioned network includes a wireless network provided by a communication provider of the terminal. In one example, the transmission device 106 includes a network adapter (Network Interface Controller, NIC) which can be connected to other network devices through a base station so as to communicate with the Internet. In one example, the transmission device 106 can be a radio frequency (Radio Frequency, RF) module which is used to communicate with the Internet in a wireless manner.

[0128] It should be noted that each of the above-mentioned modules can be a functional module or a program module, which can be implemented by software or hardware. For the module implemented by hardware, each of the above-mentioned modules can be located in the same processor; or each of the above-mentioned modules can also be located in different processors in any combination.

[0129] In the embodiment, an electronic device is also provided, which includes a memory and a processor, the memory stores a computer program, and the processor is configured to run the computer program to execute the steps in any one of the above-mentioned method embodiments.

[0130] Optionally, the electronic device described above can further include a transmission device connected with the processor, and an input and output device connected with the processor.

[0131] Optionally, in the embodiment, the processor can be configured to execute the following steps by means of a computer program:

[0132] S1, obtaining point cloud data generated by a line laser profiler scanning a measured plane of a measured target object.

[0133] S2, determining a spatial relationship between the measured plane and an ideal horizontal plane based on the point cloud data. The ideal horizontal plane is determined based on an optical axis formed by the line laser profiler.

[0134] S3, constructing a rotation matrix between a coordinate system of the point cloud data and a coordinate system in which the ideal horizontal plane is located according to the spatial relationship between the measured plane and the ideal horizontal plane.

[0135] S4, correcting point coordinates of original laser lines in the point cloud data by means of the rotation matrix to obtain point coordinates of corrected laser lines.

[0136] S5, evaluating data consistency of the line laser profiler based on the point coordinates of the corrected laser lines.

[0137] It should be noted that the specific examples in the embodiment can refer to the examples described in the above embodiments and optional implementation manners, which will not be described herein again.

[0138] In addition, in combination with the line laser profiler data consistency evaluation method provided in the above embodiments, a storage medium can also be provided to realize the line laser profiler data consistency evaluation method in the embodiment. The storage medium has a computer program stored thereon; the computer program is executed by a processor to realize any one of the line laser profiler data consistency evaluation methods in the above embodiments.

[0139] It should be understood that the specific embodiments described herein are only used to explain this application, but not to limit it. According to the embodiments provided in the present application, all other embodiments obtained by those of ordinary skill in the art without creative labor are within the scope of protection of the present application.

[0140] It is apparent that the drawings depicted are only a few exemplifying or embodiment of the present application and can be applied to other similar situations without paying creative labor by a person of ordinary skill in the art. In addition, it is understood that, although the work done in the development of the present application can be complex and long, certain modifications, made according to the technical content disclosed in the present application, such as design, manufacture or production, etc., should be regarded as routine technical means for a person of ordinary skill in the art and should not be regarded as insufficient disclosure of the present application.

[0141] The word "embodiment" in the present application means that the specific features, structures or characteristics described in connection with the embodiment can be included in at least one embodiment of the present application. The presence of this phrase in various places in the specification does not necessarily mean the same embodiment, nor does it mean independence or alternative to other embodiments. It is clear or implicitly understood by a person of ordinary skill in the art that the embodiments described in the present application can be combined with other embodiments without conflict.

[0142] The above-described embodiments only express several implementation manners of the present application, which are described in detail and specifically, but should not be understood as a limitation on the scope of patent protection. It should be pointed out that, for a person of ordinary skill in the art, several modifications and improvements can be made without departing from the concept of the present application, which are all within the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the appended claims.

Claims

1. A method for evaluating the consistency of line laser profilometer data, characterized in that, The method comprises: acquiring point cloud data generated by a line laser profiler scanning a measured plane of a measured target object; determining a spatial relationship between the measured plane and an ideal horizontal plane based on the point cloud data; the ideal horizontal plane is determined based on an optical axis formed by the line laser profiler; constructing a rotation matrix between an original coordinate system of the point cloud data and a coordinate system in which the ideal horizontal plane is located according to the spatial relationship between the measured plane and the ideal horizontal plane; correcting point coordinates of an original laser line in the point cloud data through the rotation matrix to obtain point coordinates of a corrected laser line; evaluating data consistency of the line laser profiler based on the point coordinates of the corrected laser line.

2. The method of claim 1, wherein, The method further comprises: correcting the original coordinate system based on the rotation matrix to obtain a target coordinate system; in the target coordinate system, scanning the measured target object through the line laser profiler to obtain the point coordinates of the corrected laser line.

3. The method of claim 1, wherein, The method further comprises: sampling the point cloud data at a preset interval to obtain point cloud sampling data; fitting a plane based on a preset random sampling consistency algorithm to obtain a plane fitting parameter equation.

4. The method of claim 3, wherein, The method further comprises: determining a plane normal vector of the plane fitting parameter equation; calculating a rotation included angle between the plane normal vector and a preset unit vector; the preset unit vector is perpendicular to the ideal horizontal plane; determining a three-dimensional vector perpendicular to a spatial plane formed by the plane normal vector and the preset unit vector; constructing a rotation matrix based on the three-dimensional vector and the rotation included angle.

5. The method of claim 3, wherein, The method further comprises: acquiring original laser line data in the point cloud data perpendicular to a moving direction of the measured target object; calculating a matrix product of the point coordinates of the original laser line and the rotation matrix to obtain the point coordinates of the corrected laser line.

6. The method of claim 1, wherein, The method further comprises: calculating a deviation value of the point coordinates of the corrected laser line based on a preset consistency evaluation algorithm; determining an evaluation result of the data consistency of the line laser profiler based on the deviation value.

7. The method of claim 6, wherein, The method further comprises: acquiring an arithmetic mean value of the corrected coordinates of the point coordinates of the corrected laser line; determining the evaluation result according to a coordinate value of each laser point in the arithmetic mean value of the corrected coordinates.

8. A device for evaluating the consistency of line laser profilometer data, characterized in that The device comprises a controller, a line laser profiler and a guide rail; the controller is electrically connected to the guide rail and the line laser profiler; a measured target object is fixed on the guide rail; The line laser profiler is used for scanning the measured target object. The controller is used for executing the line laser profiler data consistency evaluation method in any one of claims 1 to 7. 9.An electronic device comprising a memory and a processor, the electronic device characterized by, The memory stores a computer program, and the processor is configured to execute the computer program to execute the line laser profiler data consistency evaluation method in any one of claims 1 to 7.

10. A computer-readable storage medium having stored thereon a computer program, characterized in that, The computer program is executed by the processor to implement the steps of the line laser profiler data consistency evaluation method in any one of claims 1 to 7.

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