CN109724531B - 360-degree profile measuring method - Google Patents
360-degree profile measuring method Download PDFInfo
- Publication number
- CN109724531B CN109724531B CN201811213174.0A CN201811213174A CN109724531B CN 109724531 B CN109724531 B CN 109724531B CN 201811213174 A CN201811213174 A CN 201811213174A CN 109724531 B CN109724531 B CN 109724531B
- Authority
- CN
- China
- Prior art keywords
- laser
- lasers
- cameras
- profile
- workpiece
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Active
Links
Images
Landscapes
- Length Measuring Devices By Optical Means (AREA)
Abstract
The invention relates to a 360-degree profile measuring method, which comprises the following steps: s1, providing at least four groups of lasers and laser cameras, wherein laser lines emitted by the lasers completely cover a circle of a to-be-detected surface of a to-be-detected workpiece, and an angle between the laser cameras and a laser line plane of the lasers is 30-60 degrees; s2, calibrating the laser camera to obtain a conversion formula, and drawing the workpiece to be detected through the laser camera to obtain an original image; s3, identifying a laser line in the original image and extracting the center of the laser line through a laser center extraction algorithm; and S4, calculating the actual coordinate of the laser line through a conversion formula to obtain the original profile data. The 360-degree profile measuring method uses at least four groups of lasers and laser cameras to simultaneously measure the workpiece to be measured from at least four different directions, combines data together, realizes extraction of the complete outer profile of a certain section of the workpiece to be measured, and obtains key dimension information such as profile original data of the workpiece to be measured.
Description
Technical Field
The invention relates to a 360-degree profile measuring method, and belongs to the field of laser measurement.
Background
Laser triangulation is a method of obtaining 3D information of an object by the cooperation of line laser and an area-array camera. Most industrial 3D cameras on the market today use the basic principle of laser triangulation. The limitations of these products are: only dimensional information of a single surface of the object can be measured, so that the object cannot be perfectly measured in size. Also, the conventional 3D camera can measure only height information of a single surface, so there is no way to precisely measure thickness information of the product. However, the plate product manufacturers pay most attention to the thickness information of the product in the quality inspection link, so that the traditional 3D camera cannot meet the requirements of the manufacturers.
At present, most of domestic manufacturers for producing section bars or adhesive tapes by using an extrusion forming process manually check the size of products on a production line: a small part of products are produced by a machine before production every day, a projector, a quadratic element measuring instrument and the like are used for measuring, and the machine starts production after the size is qualified. The process has the following obvious disadvantages
1. The inspection before the machine is started each time is time-consuming and labor-consuming, not only experienced technicians are needed, but also the measurement time is more than 1 hour in many times, and a large amount of raw materials are wasted in the process;
2. there is no way to implement online monitoring: if the size of the product changes in the production process and exceeds the tolerance range, the product on the line is scrapped, and the specific time when the size of the product changes beyond the tolerance cannot be known because the worker cannot stop the production adjusting machine in time.
Disclosure of Invention
The invention aims to provide a 360-degree profile measuring method, which measures a workpiece to be measured from at least four different directions simultaneously, combines data together, extracts the complete outer profile of a certain section of the workpiece to be measured, and obtains key dimension information such as original profile data of the workpiece to be measured.
In order to achieve the purpose, the invention provides the following technical scheme: a 360 ° profile measurement method comprising the steps of:
s1, providing at least four groups of lasers and at least four groups of laser cameras, wherein laser lines emitted by the lasers completely cover one circle of a to-be-detected surface of a to-be-detected workpiece, and the angle between the laser cameras and the laser line plane of the lasers is 30-60 degrees;
s2, calibrating the laser camera to obtain a conversion formula, and drawing the workpiece to be detected through the laser camera to obtain an original image;
s3, identifying the laser line in the original image and extracting the center of the laser line through a laser center extraction algorithm;
and S4, calculating the actual coordinate of the laser line through the conversion formula to obtain the original profile data.
Further, in step S1, at least four groups of lasers are provided, where the lasers are disposed around a same center, the workpiece to be measured is placed at the center, and each laser measures a partial profile of the surface to be measured.
Further, in step S2, the calibration processing procedure includes the following steps:
calculating internal parameters: providing a calibration plate and N laser cameras, wherein N is more than or equal to 4; placing the calibration plate near the laser line plane in different postures, and taking a plurality of groups of pictures of the calibration plate through the laser camera, wherein the requirements are met:
a. at least one set of the calibration plates is coplanar with the laser line plane and the dot matrix of the calibration plates is within all of the laser camera fields of view;
b. each set of camera lasers has at least two sets of the following images: 1) a calibration plate image, the lattice being clearly visible; 2) a corresponding laser line image printed on the calibration plate is obtained by adjusting the parameters of the printing and the camera;
in addition, the requirement that the laser lines printed on the calibration plate have obvious spatial position difference between two groups of images is also met; calculating the space relative position between each laser camera and the laser line plane according to the image required by the b, calculating the space relative positions between N laser cameras according to the image required by the a, and calculating N projective transformations between the imaging plane and the laser line plane according to the information;
obtaining a conversion formula: and when the equipment is installed on a production line, extracting the outline of the equipment by adopting a cylindrical calibration plate, fitting an ellipse according to the extracted outline points, taking the directions of the long axis and the short axis of the fitted ellipse as characteristic vectors, taking the size as a characteristic value, and taking the center of the image as a fixed point to calculate an affine matrix.
Further, in step S2, the calibration processing procedure includes the following steps: providing a cylinder calibration block and N laser cameras, wherein N is more than or equal to 4; 9 pillars are arranged on the pillar calibration block, the pillar calibration block is placed near the laser line plane, so that an intersection exists between the 9 pillars and the laser line plane, and the direction of the pillars is the normal direction of a surface to be measured in the equipment measurement process; and taking N groups of images through N laser cameras, extracting the intersection point of the laser line plane and the visible edge of the pillar, and then calculating N projective transformations through the corresponding relation between the point and the point.
Further, in step S3, the laser center extraction algorithm specifically includes:
s31, taking each column of pixels of the original image as an individual signal to obtain the maximum gray value C of the column of pixelsmaxAnd position, setting a threshold value if the maximum gray value CmaxIf the pixel number is larger than the threshold value, defining that the laser signal exists in the row of pixels;
s32, setting a search window near the pixel position of the maximum gray value, and calculating the gray in the search windowGravity center of gravity Cp；
S33, setting a communication coefficient if the gray scale gravity center CpThe centre of gray scale C of the pixel in the previous column(p-1)If the distance between the two pixels is smaller than the communication coefficient, the gray scale gravity centers of the pixels in the row and the pixels in the previous row are in the same contour;
s34, sequentially processing each row of pixels of the original image, setting a noise coefficient, and discarding outlines with the size smaller than the noise coefficient;
and S35, setting a link coefficient, and merging two contours with adjacent distances smaller than the link coefficient.
Further, the gray scale center of gravity CpThe calculation formula of (2) is as follows:
wherein x is a point in the search window, R (x) is the number of lines, I (x) is the gray value, and F is the photosensitive coefficient.
Further, the 360 ° profile measurement method further includes:
and S5, performing data processing on the contour raw data, wherein the data processing is selected from one or more of linear unit fitting, quadratic curve fitting or Akima curve.
Further, in step S5, the method further includes tracking the orientation and position of the workpiece to be measured during the measurement process through a point cloud matching algorithm, so as to automatically correct the position and orientation of the measurement tool configured by the user.
Further, the linear unit fitting comprises the steps of:
s51, fitting the contour original data to a contour point set, sequencing the contour point set, and identifying the feature points { x ] in the contouri}；
S52, according to xpAnd x(p+1)Calculating a straight line and finding that the straight line is at xpAnd x(p+1)The farthest point x ' from the straight line and the distance between the points x ' and x ' are obtained;
S53、setting a fitting error, and if the distance obtained in the step S52 is smaller than the fitting error, ending the linear unit fitting process; if the distance obtained in step S52 is not less than the fitting error, x is determinedpAnd x', x(p+1)The linear unit fitting process is repeated separately with x'.
Further, in step S1, four sets of the laser cameras and four sets of the lasers are provided, the four sets of the laser cameras and the lasers are circumferentially and symmetrically distributed, and an angle between the laser cameras and a laser line plane is 45 °.
Compared with the prior art, the invention has the beneficial effects that: the 360-degree profile measuring method uses at least four groups of lasers and laser cameras to simultaneously measure the workpiece to be measured from at least four different directions, combines data together, realizes extraction of the complete outer profile of a certain section of the workpiece to be measured, and obtains key dimension information such as profile original data of the workpiece to be measured. The 360-degree profile measurement method has the following advantages:
1. through the calibration process, the mutual cooperation and synchronous measurement of at least four groups of laser cameras and lasers are realized, and a complete and continuous profile is extracted, so that the measurement of key information of a workpiece to be measured becomes possible;
2. the algorithm developed from the bottom layer of the principle level ensures that no redundant steps are needed in the whole operation process, thereby ensuring the operation efficiency;
3. the improvement point in the laser center extraction process improves the reliability and stability of the process and is important for putting the product into practical industrial application;
4. the fitting algorithm in data processing can make the 360 degree profile measurement method of the invention be used in software, such as: CAD, and the fitting algorithm reduces the complexity, improves the function and improves the efficiency; and the point cloud matching algorithm is used for ensuring that the measured data is not influenced by the random jitter of the measured object, improving the reliability of the equipment and reducing the threshold of the user for configuring the equipment.
The foregoing description is only an overview of the technical solutions of the present invention, and in order to make the technical solutions of the present invention more clearly understood and to implement them in accordance with the contents of the description, the following detailed description is given with reference to the preferred embodiments of the present invention and the accompanying drawings.
Drawings
FIG. 1 is a flow chart of a 360 profile measurement method of the present invention;
FIG. 2 is a schematic structural diagram of a cylinder calibration block during calibration in the 360 profile measurement method of the present invention;
FIGS. 3 and 4 are schematic views illustrating the processing of a laser line during the laser center extraction process by the 360-degree profile measurement method of the present invention;
fig. 5 and 6 are schematic structural diagrams of an overall 360 ° laser measuring apparatus according to an embodiment of the present invention;
fig. 7 to 9 are schematic views of internal structures of the 360 ° laser measuring apparatus shown in fig. 5;
fig. 10 is a schematic diagram of the principle of laser triangulation employed in the 360 ° profile measurement method of the present invention.
Detailed Description
The following detailed description of embodiments of the present invention is provided in connection with the accompanying drawings and examples. The following examples are intended to illustrate the invention but are not intended to limit the scope of the invention.
It should be noted that: the terms "upper", "lower", "left", "right", "inner" and "outer" of the present invention are used for describing the present invention with reference to the drawings, and are not intended to be limiting terms.
The principle of laser triangulation adopted by the 360-degree profile measuring method of the invention is shown in fig. 10, wherein a is a laser plane, namely a plane where a surface to be measured of a workpiece to be measured is located, b is an imaging plane, namely an image seen from the visual angle of the laser camera 4, and the corresponding relation between a and b is given by laser emitted by the laser camera 4. The corresponding relation is found out through the calibration process, and the corresponding image in the laser plane a (the plane where the surface to be measured is located) can be calculated through the image (namely the plane image on the imaging plane b) obtained by the laser camera 4.
Referring to fig. 1, the 360 ° profile measuring method of the present invention includes the following steps:
s1, providing at least four groups of lasers and at least four groups of laser cameras, wherein laser lines emitted by the lasers completely cover one circle of a to-be-detected surface of a to-be-detected workpiece, and the angle between the laser cameras and the laser line plane of the lasers is 30-60 degrees; the laser devices are arranged around the same circle center, the workpiece to be measured is placed at the circle center, and each laser device measures partial profile of the surface to be measured;
s2, calibrating the laser camera to obtain a conversion formula, and drawing the workpiece to be measured through the laser camera (drawing measurement is carried out through hardware triggering at the same time) to obtain an original image;
s3, identifying the laser line in the original image and extracting the center of the laser line through a laser center extraction algorithm;
and S4, calculating the actual coordinate of the laser line through the conversion formula to obtain the original profile data.
Specifically, in step S2, in the calibration processing, the method includes the following steps:
calculating internal parameters: providing a calibration plate and N laser cameras, wherein N is more than or equal to 4; placing the calibration plate near the laser line plane in different postures, and taking a plurality of groups of pictures of the calibration plate through the laser camera, wherein the requirements are met:
a. at least one set of the calibration plates is coplanar with the laser line plane and the dot matrix of the calibration plates is within all of the laser camera fields of view;
b. each set of camera lasers has at least two sets of the following images: 1) a calibration plate image, the lattice being clearly visible; 2) a corresponding laser line image printed on the calibration plate is obtained by adjusting the parameters of the printing and the camera;
in addition, the requirement that the laser lines printed on the calibration plate have obvious spatial position difference between two groups of images is also met; calculating the space relative position between each laser camera and the laser line plane according to the image required by the b, calculating the space relative positions between N laser cameras according to the image required by the a, and calculating N projective transformations between the imaging plane and the laser line plane according to the information;
obtaining a conversion formula: and when the equipment is installed on a production line, extracting the outline of the equipment by adopting a cylindrical calibration plate, fitting an ellipse according to the extracted outline points, taking the directions of the long axis and the short axis of the fitted ellipse as characteristic vectors, taking the size as a characteristic value, and taking the center of the image as a fixed point to calculate an affine matrix.
The calibration board used in calculating the internal parameters of the calibration method is in a checkerboard shape or a dot matrix shape, and the corners of the squares or the centers of the dots are extracted by using cv:: findchessboardcorrers and cv:: findCirclesGrid, respectively, provided by OpenCV. Although the above calibration method has high theoretical precision, the process is complex, therefore, the inventor also provides a calibration method with lower operation, time and material cost and simple operation, and the column calibration block used in the calibration process is shown in fig. 3. The specific process is as follows: providing a cylinder calibration block and N laser cameras, wherein N is more than or equal to 4; 9 pillars are arranged on the pillar calibration block, the pillar calibration block is placed near the laser line plane, so that an intersection exists between the 9 pillars and the laser line plane, and the direction of the pillars is the normal direction of a surface to be measured in the equipment measurement process; and taking N groups of images through N laser cameras, extracting the intersection point of the laser line plane and the visible edge of the pillar, and then calculating N projective transformations through the corresponding relation between the point and the point. The precision of the calibration process depends on the manufacturing precision of the calibration block, which is not the same as that of the calibration plate, so the precision is slightly lower theoretically, but the operation process is simpler.
Specifically, in step S3, the laser center extraction algorithm specifically includes:
s31, taking each column of pixels of the original image as an individual signal to obtain the maximum gray value C of the column of pixelsmaxAnd position, setting a threshold value if the maximum gray value CmaxIf the pixel number is larger than the threshold value, defining that the laser signal exists in the row of pixels;
s32, setting a search window near the pixel position of the maximum gray scale value, and calculating the gray scale gravity center C in the search windowp；
S33, setting a communication coefficient if the gray scale gravity center CpThe centre of gray scale C of the pixel in the previous column(p-1)If the distance between the two pixels is smaller than the communication coefficient, the gray scale gravity centers of the pixels in the row and the pixels in the previous row are in the same contour;
s34, sequentially processing each row of pixels of the original image, setting a noise coefficient, and discarding outlines with the size smaller than the noise coefficient;
and S35, setting a link coefficient, and merging two contours with adjacent distances smaller than the link coefficient.
Further, the gray scale center of gravity CpThe calculation formula of (2) is as follows:
wherein x is a point in the search window, R (x) is the number of lines, I (x) is the gray value, and F is the photosensitive coefficient.
In the laser center extraction algorithm, the threshold, the search window, the communication coefficient, the noise point coefficient and the link coefficient are set parameters by a user, the threshold and the search window in the algorithm flow play a role in filtering background noise points, the actual calculation range is limited to the position of the laser, the influence of a light source with complex change in industrial production on measurement is relieved, and meanwhile, the calculation efficiency is improved.
The communication coefficient, the noise coefficient and the link coefficient have the following functions: referring to fig. 3, the laser is shown as a line, however, due to the varying ambient light or the sudden and sudden laser, there is one less laser line in the middle and two more noise points, which is often the case in the actual extraction process. Due to the control of the communication coefficient, the laser is divided into four different profiles (10, 20, 30, 40): please refer to fig. 4. By adjusting the noise figure, two noise points of the profiles 20 and 30 can be removed. By adjusting the link coefficients, we can connect the two laser segments of the profiles 10 and 40 to form a complete laser line. In practical applications, since the light sensing curves of different light sensing elements are different and the light reflection rates of different materials are different, the gray scale value cannot quantitatively represent the actual brightness of the laser, which results in that the center of the laser calculated from the original gray scale value is not the point where the intensity of the laser line is the maximum. The gray value I (x) can be zoomed through the photosensitive function F, and correction is carried out according to different materials and cameras, so that the accuracy of laser center extraction is further ensured.
The original contour data extracted in the above process can already meet many measurement requirements, such as measurement of size, angle, and radius of fillet, but in order to facilitate efficient calculation of the area enclosed by the contour and import CAD drawings to automatically match and compare the contour, the inventor will fit an abstract contour with the original contour data points for further calculation processing. Therefore, the 360 ° profile measurement method further includes:
and S5, performing data processing on the contour raw data, wherein the data processing is selected from one or more of linear unit fitting, quadratic curve fitting or Akima curve.
Taking the example of fitting using a linear unit, the linear unit fitting comprises the steps of:
s51, fitting the contour original data to a contour point set, sequencing the contour point set, and identifying the feature points { x ] in the contouri}；
S52, according to xpAnd x(p+1)Calculating a straight line and finding that the straight line is at xpAnd x(p+1)The farthest point x ' from the straight line and the distance between the points x ' and x ' are obtained;
s53, setting a fitting error, and if the distance obtained in the step S52 is smaller than the fitting error, ending the linear unit fitting process; if the distance obtained in step S52 is not less than the fitting error, x is determinedpAnd x', x(p+1)The linear unit fitting process is repeated separately with x'.
Through the fitting algorithm, the basic functions of the following matched software can be realized:
a. importing a CAD design drawing, automatically performing contour matching, and calculating an error value;
b. measuring size information by using an outer caliper, an inner caliper and a half caliper tool;
c. selecting a straight line on the outline, and automatically aligning the graph according to the direction of the straight line according to the requirement of a user;
d. an angle measuring tool;
e. a fillet radius measuring tool;
f. an area measurement tool.
In step S5, the method further includes tracking the orientation and position of the workpiece to be measured in the measurement process by a point cloud matching algorithm, so as to automatically correct the position and orientation of a measurement tool (such as a caliper tool) configured by a user, thereby ensuring that measurement data is not affected by random jitter of the measured object, improving reliability of the device, and reducing a threshold of the device configured by the user.
Preferably, in step S1, four sets of the laser cameras and lasers are provided, the four sets of the laser cameras and lasers are circumferentially and symmetrically distributed, and the angle between the laser cameras and the laser line plane is 45 °.
Referring to fig. 5 to 9, the 360 ° profile measuring method of the present invention employs a 360 ° laser measuring apparatus as shown in the figure, which includes a bracket 1, a mounting board 2, at least four sets of lasers 3, at least four sets of laser cameras 4, and a power supply 5, wherein the mounting board 2 is disposed on the bracket 1, the lasers 3, the laser cameras 4, and the power supply 5 are disposed on the mounting board 2, and the lasers 3 and the laser cameras 4 are movably mounted on the mounting board 2; the laser line emitted by the laser 3 completely covers a circle of the surface to be measured of the workpiece to be measured (not shown), and the angle between the imaging plane of the laser camera 4 and the laser line plane of the laser 3 is 30-60 degrees, preferably 45 degrees; the laser 3 and the laser camera 4 are electrically connected to the power supply 5, and wires for connection may be arranged on a terminal 21 mounted on the mounting board 2.
In this embodiment, the laser devices 3 and the laser cameras 4 have four sets, and the four sets of the laser devices 3 and the laser cameras 4 are circumferentially and symmetrically distributed. And the lasers 3 are arranged around the same circle center, the workpiece to be measured is placed at the circle center, and each laser 3 measures the partial profile of the surface to be measured.
In this embodiment, a circular slide 22 is provided on the mounting board 2, and the laser 3 and the laser camera 4 are provided on the circular slide 22. Through the design, the laser camera 4 can be integrally adjusted with the laser 3, so that the positioning of the workpiece to be measured and the angle adjustment of the laser camera 4 are met.
In the present embodiment, each of the laser cameras 4 corresponds to one of the lasers 3, and each of the laser cameras 4 is disposed above the corresponding laser 3. A lens 41 is disposed on the top of each laser camera 4, and light emitted from the laser camera 4 is reflected by the lens 41. By utilizing the mirror reflection principle, the internal space required by the direct shooting of the laser camera 4 can be reduced, the size of the equipment is reduced, and convenience is provided for the process of assembling to a production line. Moreover, each laser camera 4 is further provided with a glass 42, and the glass 42 not only plays a role of dust prevention, but also can be used for laser projection: the light reflected from the mirror 41 is projected on the workpiece to be measured through the glass 42.
In this embodiment, the bracket 1 is further provided with a conveying support 11, and the workpiece to be measured is arranged on the conveying support 11, so that the workpiece to be measured can be conveyed and transported conveniently.
The 360-degree laser measuring device adopts at least four laser cameras and lasers to simultaneously measure the workpiece to be measured in different directions, so that key dimension information such as profile original data of the workpiece to be measured is obtained, the complete profile of the workpiece to be measured can be measured without dead angles, the structure is simple, the detection precision is high, the efficiency is high, the cost is low, the device can be widely applied to various fields, and the effect of detecting irregular-shaped objects is particularly obvious. And, through setting up the lens at the top of laser camera, utilize the specular reflection principle to save inner space, reduced the equipment size, also facilitate for the process of assembling to the production line.
In summary, the following steps: the 360-degree profile measuring method uses at least four groups of lasers and laser cameras to simultaneously measure the workpiece to be measured from at least four different directions, combines data together, realizes extraction of the complete outer profile of a certain section of the workpiece to be measured, and obtains key dimension information such as profile original data of the workpiece to be measured. The 360-degree profile measurement method has the following advantages:
1. through the calibration process, the mutual cooperation and synchronous measurement of at least four groups of laser cameras and lasers are realized, and a complete and continuous profile is extracted, so that the measurement of key information of a workpiece to be measured becomes possible;
2. the algorithm developed from the bottom layer of the principle level ensures that no redundant steps are needed in the whole operation process, thereby ensuring the operation efficiency;
3. the improvement point in the laser center extraction process improves the reliability and stability of the process and is important for putting the product into practical industrial application;
4. the fitting algorithm in data processing can make the 360 degree profile measurement method of the invention be used in software, such as: CAD, and the fitting algorithm reduces the complexity, improves the function and improves the efficiency; and the point cloud matching algorithm is used for ensuring that the measured data is not influenced by the random jitter of the measured object, improving the reliability of the equipment and reducing the threshold of the user for configuring the equipment.
The technical features of the embodiments described above may be arbitrarily combined, and for the sake of brevity, all possible combinations of the technical features in the embodiments described above are not described, but should be considered as being within the scope of the present specification as long as there is no contradiction between the combinations of the technical features.
The above-mentioned embodiments only express several embodiments of the present invention, and the description thereof is more specific and detailed, but not construed as limiting the scope of the invention. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the inventive concept, which falls within the scope of the present invention. Therefore, the protection scope of the present patent shall be subject to the appended claims.
Claims (9)
1. A 360 ° profile measurement method, comprising the steps of:
s1, providing at least four groups of lasers and at least four groups of laser cameras, wherein laser lines emitted by the lasers completely cover one circle of a to-be-detected surface of a to-be-detected workpiece, and the angle between the laser cameras and the laser line plane of the lasers is 30-60 degrees;
s2, calibrating the laser camera to obtain a conversion formula, and drawing the workpiece to be detected through the laser camera to obtain an original image;
s3, identifying the laser line in the original image and extracting the center of the laser line through a laser center extraction algorithm;
s4, calculating the actual coordinate of the laser line through the conversion formula to obtain the original data of the profile;
in step S2, the calibration processing includes the following steps: providing a cylinder calibration block and N laser cameras, wherein N is more than or equal to 4; 9 pillars are arranged on the pillar calibration block, the pillar calibration block is placed near the laser line plane, so that an intersection exists between the 9 pillars and the laser line plane, and the direction of the pillars is the normal direction of a surface to be measured in the equipment measurement process; and taking N groups of images through N laser cameras, extracting the intersection point of the laser line plane and the visible edge of the pillar, and then calculating N projective transformations through the corresponding relation between the point and the point.
2. The 360 ° profile measuring method according to claim 1, wherein in step S1, at least four sets of lasers are provided, the lasers being arranged around a same center of circle, the workpiece to be measured being placed at the center of circle, each of the lasers measuring a partial profile of the surface to be measured.
3. The 360 ° profile measuring method according to claim 1, wherein in step S2, during the calibration process, the following steps are included:
calculating internal parameters: providing a calibration plate and N laser cameras, wherein N is more than or equal to 4; placing the calibration plate near the laser line plane in different postures, and taking a plurality of groups of pictures of the calibration plate through the laser camera, wherein the requirements are met:
a. at least one set of the calibration plates is coplanar with the laser line plane and the dot matrix of the calibration plates is within all of the laser camera fields of view;
b. each set of camera lasers has at least two sets of the following images: 1) a calibration plate image, the lattice being clearly visible; 2) a corresponding laser line image printed on the calibration plate is obtained by adjusting the parameters of the printing and the camera;
in addition, the requirement that the laser lines printed on the calibration plate have obvious spatial position difference between two groups of images is also met; calculating the space relative position between each laser camera and the laser line plane according to the image required by the b, calculating the space relative positions between N laser cameras according to the image required by the a, and calculating N projective transformations between the imaging plane and the laser line plane according to the information;
obtaining a conversion formula: and when the equipment is installed on a production line, extracting the outline of the equipment by adopting a cylindrical calibration plate, fitting an ellipse according to the extracted outline points, taking the directions of the long axis and the short axis of the fitted ellipse as characteristic vectors, taking the size as a characteristic value, and taking the center of the image as a fixed point to calculate an affine matrix.
4. The 360 ° profile measuring method of claim 1, wherein in step S3, the laser center extraction algorithm specifically comprises:
s31, taking each column of pixels of the original image as an individual signal to obtain the maximum gray value C of the column of pixelsmaxAnd position, setting a threshold value if the maximum gray value CmaxIf the pixel number is larger than the threshold value, defining that the laser signal exists in the row of pixels;
s32, setting a search window near the pixel position of the maximum gray scale value, and calculating the gray scale gravity center C in the search windowp；
S33, setting a communication coefficient if the gray scale gravity center CpIn the grey scale with the pixels of the previous columnHeart C(p-1)If the distance between the two pixels is smaller than the communication coefficient, the gray scale gravity centers of the pixels in the row and the pixels in the previous row are in the same contour;
s34, sequentially processing each row of pixels of the original image, setting a noise coefficient, and discarding outlines with the size smaller than the noise coefficient;
and S35, setting a link coefficient, and merging two contours with adjacent distances smaller than the link coefficient.
5. The 360 ° profile measurement method of claim 4, wherein the gray scale center of gravity CpThe calculation formula of (2) is as follows:
wherein x is a point in the search window, R (x) is the number of lines, I (x) is the gray value, and F is the photosensitive coefficient.
6. A360 ° profile measuring method according to any one of claims 1 to 5, wherein the 360 ° profile measuring method further comprises:
and S5, performing data processing on the contour raw data, wherein the data processing is selected from one or more of linear unit fitting, quadratic curve fitting or Akima curve.
7. The 360 ° profile measuring method of claim 6, further comprising tracking the orientation and position of the workpiece to be measured during the measuring process by a point cloud matching algorithm, thereby automatically correcting the position and orientation of the measuring tool configured by the user in step S5.
8. The 360 ° profile measurement method of claim 6, wherein said linear unit fitting comprises the steps of:
s51, fitting the contour original data to a contour point set, sorting the contour point set,identifying feature points { x ] in the contouri}；
S52, according to xpAnd x(p+1)Calculating a straight line and finding that the straight line is at xpAnd x(p+1)The farthest point x ' from the straight line and the distance between the points x ' and x ' are obtained;
s53, setting a fitting error, and if the distance obtained in the step S52 is smaller than the fitting error, ending the linear unit fitting process; if the distance obtained in step S52 is not less than the fitting error, x is determinedpAnd x', x(p+1)The linear unit fitting process is repeated separately with x'.
9. The 360 ° profile measuring method of claim 1, wherein in step S1, four sets of said laser cameras and four sets of said lasers are provided, wherein said four sets of said laser cameras and lasers are circumferentially symmetrically distributed, and wherein the angle between said laser cameras and the plane of the laser line is 45 °.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201811213174.0A CN109724531B (en) | 2018-10-18 | 2018-10-18 | 360-degree profile measuring method |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201811213174.0A CN109724531B (en) | 2018-10-18 | 2018-10-18 | 360-degree profile measuring method |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN109724531A CN109724531A (en) | 2019-05-07 |
| CN109724531B true CN109724531B (en) | 2021-05-28 |
Family
ID=66294930
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201811213174.0A Active CN109724531B (en) | 2018-10-18 | 2018-10-18 | 360-degree profile measuring method |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN109724531B (en) |
Families Citing this family (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110793458B (en) * | 2019-10-30 | 2022-10-21 | 成都安科泰丰科技有限公司 | Coplane adjusting method for two-dimensional laser displacement sensor |
| CN111122598B (en) * | 2019-12-16 | 2022-12-09 | 北京冶自欧博科技发展有限公司 | Three-dimensional detection system and method for surface defects of steel rail |
| CN114964024B (en) * | 2022-07-27 | 2022-11-01 | 承德建龙特殊钢有限公司 | Steel pipe measuring device |
| CN115371564B (en) * | 2022-10-24 | 2023-03-07 | 南京航空航天大学 | Method and system for calibrating relative pose of linear laser sensor and robot flange plate |
Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5085502A (en) * | 1987-04-30 | 1992-02-04 | Eastman Kodak Company | Method and apparatus for digital morie profilometry calibrated for accurate conversion of phase information into distance measurements in a plurality of directions |
| JPH04181106A (en) * | 1990-11-15 | 1992-06-29 | Komatsu Ltd | Calibration device of position dimension measuring device |
| JP2008122307A (en) * | 2006-11-15 | 2008-05-29 | Seiko Epson Corp | Reference position calibration tool, contour measuring instrument, visual inspection device, measuring object holding device, reference position calibration method, contour measuring method, and visual inspection method |
Family Cites Families (17)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB8719951D0 (en) * | 1987-08-24 | 1987-09-30 | Lbp Partnership | Three-dimensional scanner |
| JP2003322512A (en) * | 2002-05-02 | 2003-11-14 | Shimizu Corp | Size measuring device for sample |
| ES2369002T3 (en) * | 2007-05-23 | 2011-11-24 | Snap-On Equipment Srl A Unico Socio | PROCEDURE AND APPLIANCE TO DETERMINE THE GEOMETRIC DIMENSION OF A VEHICLE WHEEL THAT INCLUDES OPTICAL SENSORS. |
| CN100575864C (en) * | 2007-07-17 | 2009-12-30 | 天津大学 | A kind of three-dimensional splicing matching point selecting method based on global calibration constraint |
| CN100582651C (en) * | 2008-08-27 | 2010-01-20 | 天津大学 | Dynamic target for calibration of 3-D colorful digitalized system |
| CN102288131A (en) * | 2011-05-12 | 2011-12-21 | 上海大学 | Adaptive stripe measurement device of 360-degree contour error of object and method thereof |
| CN102364299B (en) * | 2011-08-30 | 2015-01-14 | 西南科技大学 | Calibration technology for multiple structured light projected three-dimensional profile measuring heads |
| EP2589925A1 (en) * | 2011-11-02 | 2013-05-08 | Siemens Aktiengesellschaft | 3D surface internal inspection system by means of 2D exposures and method |
| CN202331571U (en) * | 2011-11-14 | 2012-07-11 | 云南大学 | Crossed body calibration block for solving internal parameters of video camera |
| CN103148806A (en) * | 2011-12-07 | 2013-06-12 | 史金龙 | Ship steel plate dynamic three-dimensional measuring system based on projection and multi-view vision |
| DE102012009859B4 (en) * | 2012-05-21 | 2019-05-16 | QuISS Qualitäts-Inspektionssysteme und Service AG | A method for detecting a structure to be applied to a substrate with a plurality of optical image pickup units and a device therefor |
| US9117267B2 (en) * | 2012-10-18 | 2015-08-25 | Google Inc. | Systems and methods for marking images for three-dimensional image generation |
| CN104848801B (en) * | 2015-06-05 | 2017-06-13 | 北京航空航天大学 | A kind of line structured light vision sensor calibration method based on parallel bicylindrical target |
| CN104913737A (en) * | 2015-06-30 | 2015-09-16 | 长安大学 | Component quality checking device based on line laser three-dimensional measurement and detection method of device |
| DE102016002398B4 (en) * | 2016-02-26 | 2019-04-25 | Gerd Häusler | Optical 3D sensor for fast and dense shape detection |
| CN105966419A (en) * | 2016-07-08 | 2016-09-28 | 沈阳铁路局科学技术研究所 | Railway tunnel clearance inspection car |
| CN107796335A (en) * | 2017-11-24 | 2018-03-13 | 深圳市恒茂科技有限公司 | A kind of 360 ° of object section contour detecting devices and online test method |
-
2018
- 2018-10-18 CN CN201811213174.0A patent/CN109724531B/en active Active
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5085502A (en) * | 1987-04-30 | 1992-02-04 | Eastman Kodak Company | Method and apparatus for digital morie profilometry calibrated for accurate conversion of phase information into distance measurements in a plurality of directions |
| JPH04181106A (en) * | 1990-11-15 | 1992-06-29 | Komatsu Ltd | Calibration device of position dimension measuring device |
| JP2008122307A (en) * | 2006-11-15 | 2008-05-29 | Seiko Epson Corp | Reference position calibration tool, contour measuring instrument, visual inspection device, measuring object holding device, reference position calibration method, contour measuring method, and visual inspection method |
Also Published As
| Publication number | Publication date |
|---|---|
| CN109724531A (en) | 2019-05-07 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN109724531B (en) | 360-degree profile measuring method | |
| US12001191B2 (en) | Automated 360-degree dense point object inspection | |
| CN110276808B (en) | Method for measuring unevenness of glass plate by combining single camera with two-dimensional code | |
| CN105934648B (en) | Calibration method and survey tool | |
| CN103344182B (en) | A kind of confection physical dimension based on binocular vision measures system and method | |
| CN109859272B (en) | Automatic focusing binocular camera calibration method and device | |
| CN109767476A (en) | A kind of calibration of auto-focusing binocular camera and depth computing method | |
| EP1884740A2 (en) | Method and system for sensing the surface shape of a reflective object | |
| CN110490833B (en) | Method and device for measuring volume of target object | |
| CN107816943B (en) | Logistics box volume and weight measurement system and implementation method thereof | |
| CN108627119B (en) | Board-type furniture contour dimension detection method based on line scanning laser | |
| CN106815866B (en) | Calibration method of fisheye camera, calibration system and target thereof | |
| CN104729422A (en) | Method for calibrating a laser measuring device and system therefor | |
| CN113505626B (en) | Quick three-dimensional fingerprint acquisition method and system | |
| CN110966956A (en) | Binocular vision-based three-dimensional detection device and method | |
| CN113012234B (en) | High-precision camera calibration method based on plane transformation | |
| CN104075659A (en) | Three-dimensional imaging recognition method based on RGB structure light source | |
| US10628968B1 (en) | Systems and methods of calibrating a depth-IR image offset | |
| US11259000B2 (en) | Spatiotemporal calibration of RGB-D and displacement sensors | |
| CN115060162A (en) | Chamfer dimension measuring method and device, electronic equipment and storage medium | |
| Wang et al. | Measurement and analysis of depth resolution using active stereo cameras | |
| CN112097684B (en) | Visual measurement system and method based on multi-attitude band structured light | |
| CN103559710A (en) | Calibration method for three-dimensional reconstruction system | |
| TWI480507B (en) | Method and system for three-dimensional model reconstruction | |
| US20160349045A1 (en) | A method of measurement of linear dimensions of three-dimensional objects |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| GR01 | Patent grant | ||
| GR01 | Patent grant |