CN116907359A - Segment steel mould three-dimensional model acquisition and measurement method - Google Patents
Segment steel mould three-dimensional model acquisition and measurement method Download PDFInfo
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- 229910000831 Steel Inorganic materials 0.000 title claims abstract description 130
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- 229910001294 Reinforcing steel Inorganic materials 0.000 description 1
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- G—PHYSICS
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- G06T—IMAGE DATA PROCESSING OR GENERATION, IN GENERAL
- G06T7/00—Image analysis
- G06T7/80—Analysis of captured images to determine intrinsic or extrinsic camera parameters, i.e. camera calibration
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
- G01B11/00—Measuring arrangements characterised by the use of optical techniques
- G01B11/02—Measuring arrangements characterised by the use of optical techniques for measuring length, width or thickness
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
- G01B11/00—Measuring arrangements characterised by the use of optical techniques
- G01B11/02—Measuring arrangements characterised by the use of optical techniques for measuring length, width or thickness
- G01B11/028—Measuring arrangements characterised by the use of optical techniques for measuring length, width or thickness by measuring lateral position of a boundary of the object
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- G—PHYSICS
- G06—COMPUTING; CALCULATING OR COUNTING
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- G06T17/00—Three dimensional [3D] modelling, e.g. data description of 3D objects
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Abstract
The application discloses a segment steel mould three-dimensional model acquisition and measurement method, wherein a binocular camera is arranged at the moving end of a robot, the binocular camera comprises two monocular cameras, and the method specifically comprises the following steps: s1, calibrating internal parameters of a camera; s2, calibrating external parameters of the camera; s3, calibrating the eyes and hands; s4, controlling the binocular camera to move by the robot; s5, obtaining a local three-dimensional description of the segment steel mould; s6, obtaining a complete three-dimensional description of the segment steel mould; s7, detecting the mounting precision of the segment steel mould; s8, detecting the flatness of the segment steel mould; s9, measuring the size of the segment steel mould. According to the technical scheme, the binocular vision system and the robot coordinate system are matched to finish high-precision measurement of the segment steel die, a rapid and accurate segment steel die detection technology is provided, the segment is detected completely, and powerful technical support is provided for efficient, automatic and intelligent segment production.
Description
Technical Field
The application belongs to the technical field of computers, relates to a binocular vision three-dimensional measurement technology, and in particular relates to a segment steel mould three-dimensional model acquisition and measurement method.
Background
At present, most of subway tunnels in China are constructed by a shield method, and the use amount of prefabricated reinforced concrete segments (hereinafter referred to as segments) serving as a main component of the shield construction tends to increase year by year. The segment is used as a reinforced concrete structural member for shield construction tunnel lining, the impervious grade generally needs to reach more than P10, and the engineering structural design life is 100 years. These basic requirements determine that the segment meet the requirements of higher dimensional accuracy and appearance quality. Whether the quality of the duct piece is qualified or not directly influences the tunneling control of the shield machine, the assembly quality of the duct piece and the structural performance, the waterproof performance and the durability of the formed tunnel.
On the other hand, the steel mould assembly line method operation can reduce the environmental pollution of field production, reduce the logistics jam and exert the industrial operation management advantage; the quality of the product can be conveniently controlled, and the risk of unqualified finished products is greatly reduced; effectively improves the production efficiency, plays the productivity advantage and creates more economic benefits for enterprises.
Meanwhile, the pipe piece steel mould used in the steel mould assembly line method operation averagely needs to produce pipe pieces with more than 800 rings, namely, repeatedly assembling the mould, putting reinforcing steel bars into the mould, vibrating concrete and demoulding for 800 times, and extremely high precision is ensured each time, so that the material performance of the mould steel is a challenge, and the manufacturing and combination precision of the steel mould is extremely high. The greater the number of reuse times, the greater the likelihood that the mold will have reduced positioning accuracy.
Therefore, quick and accurate steel die outline dimension measurement and installation accuracy detection play a vital role in quality control of the duct piece and improvement of duct piece production efficiency.
However, the method has the characteristics of large size (span is 4-6 m), high precision requirement (error is less than 0.2 mm), irregular shape (circular arc with radius of 3-4 m) and the like, so that the realization difficulty of the high-precision and rapid measuring method of the segment steel die is improved.
The traditional measuring tool for large-scale workpieces is provided with a vernier caliper, a micrometer, a caliper gauge and the like. The micrometer is a relatively common method for measuring the size of a large workpiece by using a traditional machine, and is mainly used for workpieces with tolerance levels larger than IT 10. In order to reduce the measurement error, the measuring arm of the caliper cannot be too long, so that the measuring range is usually less than 1 meter, and the measurement of the duct piece cannot be satisfied. Meanwhile, the duct piece measurement comprises indexes such as arc length and the like such as nonlinear length measurement, so that accurate duct piece size measurement is difficult to achieve based on a traditional mechanical measurement method.
Because of the lack of advanced measurement means, the domestic segment steel die measurement still stays in the two-dimensional dimension detection stages of width, arc length, height and the like, and the integral deformation generated in the segment steel die production process cannot be detected. After deformation is detected by the segment steel mould, no guiding repair basis exists. For example, when the width dimension exceeds the limit value, it cannot be judged which one of the two side dies is deformed, and only two sides can be repaired simultaneously or two side dies can be repaired in turn; the same is true for the detection of arc length. Meanwhile, the problem that two side dies deform or misplacement in the same direction may exist under the condition that the width dimension is completely qualified. The above problems are not found by the conventional detection means. In addition, the traditional mechanical measurement needs manual operation, and has the problems of high labor intensity, easiness in being influenced by human factors, long measurement time, incapability of being in parallel line production with automatic equipment and the like, and can not meet the requirements of modernization and automatic duct piece generation.
On the other hand, the three-dimensional industrial measurement system which is a measurement method based on the optical theory is a system which combines various measurement instruments including an electronic theodolite, a total station, a laser tracker, an industrial camera and the like, completes real-time three-dimensional measurement of a large-sized component under the control of a computer, and performs data processing on site to obtain a measurement result. Currently, the conventional universal coordinate precision measurement representative equipment, namely a three-coordinate measuring machine, is widely applied in the manufacturing industry. However, the measuring range is limited (generally not more than 2 m) due to the limitation of the movement of the linear guide rail, and the measuring range has high requirements on application environment and is generally not suitable for complex production sites.
The three-dimensional measuring means such as a theodolite industrial measuring system, a total station polar coordinate measuring system, a three-dimensional laser scanner and the like have the problems that manual aiming is needed, a target is needed to be pasted and the like, and the requirements of high-precision, rapid and full-automatic segment steel die measurement cannot be well met.
The binocular vision-based three-dimensional measurement system has the problem that the precision is affected by the visual field range, and the high-precision measurement of large-sized workpieces such as segment steel dies cannot be realized. Therefore, this patent proposes combining binocular vision system and robot, through the cooperation of binocular vision system and robot coordinate system, accomplishes the high accuracy measurement of section of jurisdiction steel mould.
The theoretical basis of binocular stereoscopic vision is the imaging theory of human eye vision. The binocular stereo vision obtains three-dimensional information of an actual scene by processing two stereo images, further obtains a depth image, obtains three-dimensional point cloud information of the actual scene by certain processing and calculation, and takes the three-dimensional point cloud as three-dimensional description of an object to be detected for subsequent processing.
The three-dimensional measurement system based on binocular vision has the advantages that the precision is affected by the visual field range, and the requirement of high-precision measurement of large-scale workpieces such as segment steel dies cannot be met. Therefore, this patent proposes combining binocular vision system and robot, through the cooperation of binocular vision system and robot coordinate system, accomplishes the high accuracy measurement of section of jurisdiction steel mould.
Disclosure of Invention
In order to solve the defects and shortcomings in the prior art, the patent provides a segment steel die three-dimensional model acquisition and measurement method.
In particular, the application provides a segment steel mould three-dimensional model acquisition and measurement method,
the segment steel mould three-dimensional model acquisition and measurement method is characterized in that a binocular camera is arranged at the moving end of a robot, the binocular camera comprises two cameras, and the method specifically comprises the following steps:
s1, performing internal reference calibration on two cameras respectively;
s2, calibrating external parameters of the cameras, and calibrating the relative position relationship between the two cameras to obtain a binocular camera coordinate system;
s3, calibrating the eyes of the hand, and solving the conversion relation from the binocular camera coordinate system to the robot terminal coordinate system;
s4, controlling the binocular camera to move by the robot, sequentially acquiring the outer surface data of the duct piece according to the moving path of the robot by the binocular camera, and sequentially acquiring the outer surface data of all duct piece steel dies;
s5, obtaining a local three-dimensional description of the segment steel mould;
s6, obtaining a complete three-dimensional description of the segment steel mould;
s7, detecting the mounting precision of the segment steel mould;
s8, detecting the flatness of the segment steel mould;
s9, measuring the size of the segment steel mould.
In step S1, calibration plate images are acquired from different positions for a plurality of times, and the internal parameters of the two cameras are calculated respectively by the accurate positions of the calibration points in the calibration plate images.
In step S2, the rotation and translation relationships R of the calibration plates captured by each camera are solved 0 、t 0 And R is 1 、t 1 The method comprises the steps of carrying out a first treatment on the surface of the For points [ x, y, z ] in the world coordinate system on the calibration plate] T Presence in left cameraConversion relation, existence in right cameraConversion relation, and can be obtained after arrangementThe external parameters of the right camera relative to the left camera are expressed as:
secondly, three-dimensional correction is performed on the principle that the left view and the right view shot in the same scene are subjected to mathematical projection transformation to achieve coplanar line alignment;
and thirdly, three-dimensional matching, namely, for each pixel point in the left image, finding a corresponding point in the right image, and calculating parallax:
d＝(x i -x j ) A, where x i ，x j Respectively representing the column seating of two corresponding points in the imageThe standard, alpha is the camera pixel size; then, calculating depth information Z of the point cloud by using the following formula;
Z＝f*b/d (2)
wherein f is the focal length and b is the baseline length;
in addition, the X and Y coordinates of the point cloud are respectively calculated by the following formulas;
wherein (x) 0 ，y 0 ) Is the image optical center coordinates of the left camera.
In step S3, the camera is mounted on the robot tip and moves along with the robot tip, and the function of the hand-eye calibration is to calculate the transformation matrix from the camera coordinate system to the robot tip coordinate systemRobot base coordinate system lower coordinate P base Expressed as:
P board the lower coordinate of the calibration plate coordinate system is used for calibration;representing the conversion relation between the coordinate system of the calibration plate and the coordinate system of the camera; />Representing the conversion relation between the robot terminal coordinate system and the camera coordinate system; />The method is a conversion relation between a robot tail end coordinate system and a robot base coordinate;
the relation between the robot base and the calibration plate is fixed, and the robot is carried by moving the tail end of the robotThe camera shoots the fixed calibration board of position from different angles, obtain after the image processing of calibration boardAnd read out by robotThen, calculate ∈>
In step S4, the binocular camera acquires all the coordinates of the points on the left and right end surfaces and the points on the front and rear side surfaces of each segment steel mold, and acquires the outer surface data of the segment steel mold.
In step S5, the robot collects a local image of the segment steel mold with the binocular camera, and uses the internal and external parameters of the camera and the parallax of the calculated feature points to calculate a point cloud using the optical center of the left camera as the origin of the coordinate system, and uses the point cloud as a local three-dimensional feature description of the segment steel mold.
In step S6, the conversion relation between the camera coordinate system obtained by hand-eye calibration and the robot terminal coordinate system and the robot terminal coordinate when each local three-dimensional description is generated are utilized to convert the local three-dimensional description in different coordinate systems into the three-dimensional coordinates of the robot base coordinate system, so as to obtain the complete three-dimensional description of the segment steel mould;
wherein P is cam(i) The coordinate system origin of the three-dimensional point cloud set generated for utilizing the steel mould local image acquired by the ith acquisition is positioned at the optical center of the left camera;the conversion relation between the coordinate system of the flange at the tail end of the robot and the coordinate system of the camera with the left camera optical center as the origin of the coordinate system is represented, and the conversion relation is determined through hand-eye calibration; />Representing robot base at ith acquisitionThe conversion relation between the standard system and the robot tail end coordinate system;
meanwhile, the method is calculated through hand-eye calibrationBut->The three-dimensional coordinates P of the steel mould point cloud under the robot base coordinate system are calculated by utilizing the following steps of reading from a robot demonstrator when collecting the partial images of the segment steel mould base ；
Due to the above P base The three-dimensional point clouds are three-dimensional coordinates under a robot base coordinate system, so that the local three-dimensional point clouds of the steel mould under different coordinate systems are synthesized into the whole three-dimensional description of the steel mould under a unified coordinate system, and support is provided for subsequent measurement of the size of the steel mould.
Further, in step S7,
firstly, performing cylinder fitting in the generated steel mould three-dimensional model to obtain an equation of a cylinder where the intrados of the steel mould is located, which is shown in the following formula.
Wherein, (x) 0 ，y 0 ，z 0 ) R is the radius of the cylinder, and (l, m, n) is the vector of the direction of the cylinder axis;
then, a known point (x 0 ，y 0 ，z 0 ) After translating to the origin of the three-dimensional coordinate system, calculating a direction vector (l, m, n) and a Z-axis clamping angle alpha, and enabling the cylindrical axis to be overlapped with the Z axis after integrally rotating the steel mould three-dimensional model alpha;
according to the segment design rule, the two side dies are perpendicular to the axis of the cylinder where the bottom die is located, and the included angles between the side dies and the XOY plane and the YOZ plane are calculated respectively and used as judgment bases for detecting the installation accuracy of the side dies;
comparing the included angles of the side mold and the XOY plane and the YOZ plane with the design value, and calculating the deviation of the angles in the two directions to be used as the basis for adjusting the installation angle of the side mold;
then, respectively calculating the included angles of the end die and the XOY plane and the XOZ plane, and taking the included angles as a judgment basis for detecting the mounting precision of the end die;
and comparing the included angles of the end die and the XOY plane as well as the XOZ plane with the design value, and calculating the deviation of the angles in the two directions to be used as the basis for adjusting the installation angle of the end die.
Further, in step S8,
firstly, after calculating the distance between the point cloud of the inner arc surface of the steel die and the axis of the fitting cylinder of the inner arc surface, dividing the difference between the distance and the radius of the fitting cylinder into a plurality of intervals from small to large as arc surface roundness error, respectively calculating the point cloud duty ratio of each difference interval, and finally taking the proportional distribution as the roundness measurement of the inner arc surface of the steel die;
after calculating the distance between the end mode point cloud in the normal vector direction of the end simulation resultant plane and the end simulation resultant plane, dividing the distance into a plurality of sections from small to large, respectively calculating the point cloud duty ratio of each distance section, and finally taking the proportion distribution as the flatness measurement of the end mode plane;
after calculating the distance between the side model point cloud and the side model fitting plane in the normal vector direction of the side model fitting plane, dividing the distance into a plurality of sections from small to large, respectively calculating the point cloud duty ratio of each distance section, and finally taking the proportional distribution as the flatness measurement of the side model plane.
Further, in step S9,
firstly, calculating an intersection point of an intersection line between a left end die plane and a front side die plane and an intrados of a segment steel die model by using the following formula;
then, taking an intersection point which is close to the center point of the intrados of the segment steel die from the two calculated intersection points as an intersection point of the left end die, the front side die and the intrados;
after the processing is carried out on the side die, the end die and the inner and outer cambered surfaces respectively, three-dimensional coordinates of a measuring key point of the segment steel die are obtained and used as the basis for evaluating the size specification of the segment steel die, and the segment quality is evaluated;
finally, calculating the linear distances between the vertexes of the four sides of the inner surface and the outer surface of the segment steel mould;
calculating the arc length of the side edges of the inner arc surface and the outer arc surface of the segment steel die;
and calculating the arc length between the inner arc surface and the outer arc surface of the segment steel die and the corner points.
The application has the advantages and positive effects that:
according to the technical scheme, the binocular vision system and the robot coordinate system are matched to finish high-precision measurement of the segment steel die, a rapid and accurate segment steel die detection technology is provided, and powerful technical support is provided for efficient, automatic and intelligent segment production.
Drawings
In order to more clearly illustrate the technical solutions of the present application, the drawings that are needed in the description of the embodiments will be briefly described below, it being obvious that the drawings in the following description are only some embodiments of the present application, and that other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.
Fig. 1 is a diagram of a robot binocular camera detection.
Fig. 2 is a schematic diagram of a cavity structure of a segment steel mold (schematic diagram of a detection key point).
Detailed Description
In order to make the structure and advantages of the present application more apparent, the structure of the present application will be further described with reference to the accompanying drawings.
A segment steel mould three-dimensional model acquisition and measurement method installs a binocular camera at the moving end of a robot, wherein the binocular camera comprises two cameras, and the method comprises the following specific steps:
and step 1, performing internal parameter calibration on the two cameras respectively, wherein the camera internal parameter calibration is mainly used for obtaining an internal parameter matrix and a distortion coefficient of the camera.
According to the method, the Zhang Youzheng calibration method is adopted to calibrate the internal parameters of the camera, the influence of visual distortion is fully considered, the method is a commonly adopted internal parameter calibration method of the camera, in the calibration process, the calibration plate image is acquired from different positions for multiple times, and the calculation of the internal parameters of the camera is carried out through the accurate positions of the calibration points in the calibration plate image.
Step 2, calibrating external parameters of the camera,
the main target of the external reference calibration of the binocular camera is to find the relative position relation between the two cameras, and the relative position relation is determined by a rotation matrix R and a translation vector T between the two camera coordinate systems;
first, the rotation and translation relation R of each calibration plate shot by each camera is solved separately 0 、t 0 And R is 1 、t 1 The method comprises the steps of carrying out a first treatment on the surface of the For points [ x, y, z ] in the world coordinate system on the calibration plate] T Presence in left cameraConversion relation, existence in right cameraConversion relation, and can be obtained after arrangementSo the external parameters of the right camera relative to the left camera can be expressed as
Secondly, three-dimensional correction is based on the principle that the left view and the right view shot in the same scene are subjected to mathematical projection transformation, so that two imaging planes are parallel to a base line, the same point is positioned in the same row in the left view and the right view, and the coplanar rows are aligned for short, and the distance can be calculated by using the triangle principle only after the coplanar row alignment is achieved.
And thirdly, three-dimensional matching, namely, for each pixel point in the left image, finding a corresponding point in the right image, and calculating parallax:
d＝(x i -x j ) A, where x i ，x j Respectively representing column coordinates of two corresponding points in an image, wherein a is the size of a camera pixel; then, the depth information Z of the point cloud can be calculated using the following equation.
Z＝f*b/d (2)
Where f is the focal length and b is the baseline length.
The X and Y coordinates of the point cloud are calculated by the following equations.
Wherein (x) 0 ，y 0 ) Is the image optical center coordinates.
Step 3, calibrating the hand and the eye,
the camera is mounted on the robot tip and moves with the robot tip. For this eye-on-hand approach, the camera coordinate system is fixed relative to the robot tip coordinate system, while it is variable for the robot base coordinate system. For this purpose, the main task of hand-eye calibration is to calculate the transformation matrix from the camera coordinate system to the robot end coordinate systemRobot base coordinate system lower coordinate P base Expressed as:
P board the lower coordinate of the calibration plate coordinate system is used for calibration;representing the conversion relation between the coordinate system of the calibration plate and the coordinate system of the camera；/>Representing the conversion relation between the robot terminal coordinate system and the camera coordinate system; />Is the conversion relation between the robot terminal coordinate system and the robot base coordinate.
The relationship between the robot base coordinates and the calibration plate is fixed because the calibration plate is always fixed relative to the robot base coordinates in the whole calibration process, so that the calibration plate with the fixed position can be shot from different angles by moving the robot tail end to carry the camera, and then the calibration plate is calculatedAnd read +.>Then, calculate the ++>
And 4, controlling the binocular camera to move by the robot, setting a moving path of the tail end of the robot, wherein the moving path comprises all to-be-detected points, and respectively acquiring the inner cambered surface, the left end surface and the right end surface of the segment steel die, and the image information of the front side surface and the rear side surface.
Step 5 obtaining local three-dimensional description of segment steel mould
The robot end carries a binocular camera to a proper position, acquires a local image of the segment steel mould, obtains a point cloud with the optical center of the left camera at the moment as a coordinate origin by utilizing the internal and external parameters of the camera and the calculated characteristic point parallax, and can describe the point cloud as a local three-dimensional characteristic of the segment.
Step 6, generating complete three-dimensional description of segment steel mould
The process can collect the local three-dimensional description of the segment steel mould, and the coordinate system origins of the local three-dimensional description of the segment steel mould are different due to the fact that the binocular camera needs to be moved when the segment steel mould is collected at different positions. The whole set of the local three-dimensional descriptions under the origins of different coordinate systems cannot accurately restore the three-dimensional form of the segment steel mold, so that the local three-dimensional descriptions need to be unified under a certain coordinate system, and the complete three-dimensional description of the segment steel mold can be obtained.
The conversion relation between the camera coordinate system obtained by hand-eye calibration and the robot terminal coordinate system and the robot terminal coordinate when generating each local three-dimensional description are utilized to convert the local three-dimensional description under different coordinate systems into the three-dimensional coordinate of the robot base coordinate system, so that the complete three-dimensional description of the segment steel mould is obtained, and the dimension measurement based on the three-dimensional description is possible.
Wherein P is cam(i) The coordinate system origin of the three-dimensional point cloud set generated for utilizing the steel mould local image acquired by the ith acquisition is positioned at the optical center of the left camera;representing a conversion relation between a robot terminal flange (tool) coordinate system and a left camera optical center serving as an origin camera coordinate system, wherein the conversion relation is determined through hand-eye calibration; />And the conversion relation between the robot base coordinate system and the robot tail end coordinate system during the ith acquisition is shown.
Meanwhile, the method is calculated through hand-eye calibrationBut->The segment steel mould partial image can be read from the robot demonstrator when being acquired. For this purpose, the three-dimensional coordinates P of the point cloud of the steel mould in the robot base coordinate system can be calculated by using the following base 。
Due to the above P base The three-dimensional point clouds are three-dimensional coordinates under the robot base coordinate system, so that the local three-dimensional point clouds of the steel mould under different coordinate systems are synthesized into the whole three-dimensional description of the steel mould under a unified coordinate system, and support is provided for subsequent measurement of the size of the steel mould.
Step 7 segment steel die installation accuracy detection
Firstly, performing cylinder fitting in the generated steel mould three-dimensional model to obtain an equation of a cylinder where the intrados of the steel mould is located, which is shown in the following formula.
Wherein, (x) 0 ，y 0 ，z 0 ) R is the cylinder radius and (l, m, n) is the cylinder axis direction vector, which is a known point on the cylinder axis.
Then, a known point (x 0 ，y 0 ，z 0 ) After translating to the origin of the three-dimensional coordinate system, calculating a direction vector (l, m, n) and a Z-axis clamping angle alpha, and enabling the cylindrical axis to be overlapped with the Z axis after integrally rotating the steel mould three-dimensional model alpha;
according to the segment design rule, the two side dies are perpendicular to the axis of the cylinder where the bottom die is located, and the included angles between the side dies and the XOY plane and the YOZ plane are calculated respectively and used as judgment bases for detecting the installation accuracy of the side dies;
comparing the included angles of the side mold and the XOY plane and the YOZ plane with the design value, and calculating the deviation of the angles in the two directions to be used as the basis for adjusting the installation angle of the side mold;
then, respectively calculating the included angles of the end die and the XOY plane and the XOZ plane, and taking the included angles as a judgment basis for detecting the mounting precision of the end die;
and comparing the included angles of the end die and the XOY plane as well as the XOZ plane with the design value, and calculating the deviation of the angles in the two directions to be used as the basis for adjusting the installation angle of the end die.
Step 8 segment steel mould flatness detection
Firstly, after calculating the distance between the point cloud of the inner arc surface of the steel die and the axis of the fitting cylinder of the inner arc surface, dividing the difference between the distance and the radius of the fitting cylinder into a plurality of intervals from small to large as arc surface roundness error, respectively calculating the point cloud duty ratio of each difference interval, and finally taking the proportional distribution as the roundness measurement of the inner arc surface of the steel die;
after calculating the distance between the end mode point cloud in the normal vector direction of the end simulation resultant plane and the end simulation resultant plane, dividing the distance into a plurality of sections from small to large, respectively calculating the point cloud duty ratio of each distance section, and finally taking the proportion distribution as the flatness measurement of the end mode plane;
after calculating the distance between the side model point cloud and the side model fitting plane in the normal vector direction of the side model fitting plane, dividing the distance into a plurality of sections from small to large, respectively calculating the point cloud duty ratio of each distance section, and finally taking the proportional distribution as the flatness measurement of the side model plane.
Step 9 segment Steel die size measurement
Firstly, calculating an intersection point of an intersection line between a left end die plane and a front side die plane and an intrados of the segment steel film model by using the following formula;
and then, taking the intersection point which is close to the center point of the intrados of the segment steel die from the two calculated intersection points as the intersection point of the left end die, the front side die and the intrados.
After the processing is respectively carried out on the side die, the end die and the inner and outer cambered surfaces, three-dimensional coordinates of the number 1-8 segment measurement key points shown in fig. 2 can be obtained and used as a basis for evaluating segment size specification and segment quality.
The radius is set to be a theoretical value on the basis of the common axis of the cylinder where the outer cambered surface is positioned and the inner cambered surface cylinder, and then the treatment is carried out; the specific basis includes:
calculating the linear lengths of four sides of the inner surface and the outer surface of the segment steel die, and specifically calculating the linear distances among points 1-5, points 3-7, points 2-6 and points 4-8 in the attached drawings;
calculating the arc length of the side edges of the inner arc surface and the outer arc surface of the end surface of the segment steel die, wherein the arc length comprises the arc length between the points 1-2, 3-4, 5-6 and 7-8;
the arc length between the inner arc surface and the outer arc surface of the segment steel die and the corner point is calculated, and the arc length between the points 2-5, 4-7, 1-6 and 3-8 is specifically included.
The foregoing is illustrative of the present application and is not to be construed as limiting thereof, but rather, the present application is to be construed as limited to the appended claims.
Claims (10)
1. The segment steel mould three-dimensional model acquisition and measurement method is characterized in that a binocular camera is arranged at the moving end of a robot, the binocular camera comprises two cameras, and the method specifically comprises the following steps:
s1, performing internal reference calibration on two cameras respectively;
s2, calibrating external parameters of the cameras, and calibrating the relative position relationship between the two cameras to obtain a binocular camera coordinate system;
s3, calibrating the eyes of the hand, and solving the conversion relation from the binocular camera coordinate system to the robot terminal coordinate system;
s4, controlling the binocular camera to move by the robot, sequentially acquiring the outer surface data of the duct piece according to the moving path of the robot by the binocular camera, and sequentially acquiring the outer surface data of all duct piece steel dies;
s5, obtaining a local three-dimensional description of the segment steel mould;
s6, obtaining a complete three-dimensional description of the segment steel mould;
s7, detecting the mounting precision of the segment steel mould;
s8, detecting the flatness of the segment steel mould;
s9, measuring the size of the segment steel mould.
2. The method for acquiring and measuring the three-dimensional model of the segment steel mould according to claim 1, wherein in the step S1, the calibration plate image is acquired from different positions for a plurality of times, and the internal parameters of the two cameras are respectively calculated by the accurate positions of the calibration points in the calibration plate image.
3. The method for collecting and measuring a three-dimensional model of a segment steel mold according to claim 1, wherein in step S2, first, the rotation and translation relation R of each calibration plate photographed by each camera is solved separately 0 、t 0 And R is 1 、t 1 The method comprises the steps of carrying out a first treatment on the surface of the For points [ x, y, z ] in the world coordinate system on the calibration plate] T Presence in left cameraConversion relation, existence in right cameraConversion relation, and can be obtained after arrangementThe external parameters of the right camera relative to the left camera are expressed as:
secondly, three-dimensional correction is performed on the principle that the left view and the right view shot in the same scene are subjected to mathematical projection transformation to achieve coplanar line alignment;
and thirdly, three-dimensional matching, namely, for each pixel point in the left image, finding a corresponding point in the right image, and calculating parallax:
d＝(x i -x j ) A, where x i ，x j Respectively representing column coordinates of two corresponding points in an image, wherein a is the size of a camera pixel; then, calculating depth information Z of the point cloud by using the following formula;
Z＝f*b/d (2)
wherein f is the focal length and b is the baseline length;
in addition, the X and Y coordinates of the point cloud are respectively calculated by the following formulas;
wherein (x) 0 ，y 0 ) Is the image optical center coordinates of the left camera.
4. The method for three-dimensional model acquisition and measurement of segment steel mold according to claim 1, wherein in step S3, the camera is mounted on the robot tip, and the function of the hand-eye calibration is to calculate the transformation matrix from the camera coordinate system to the robot tip coordinate system as the robot tip moves togetherRobot base coordinate system lower coordinate P base Expressed as:
P board the lower coordinate of the calibration plate coordinate system is used for calibration;representing the conversion relation between the coordinate system of the calibration plate and the coordinate system of the camera; />Representing the conversion relation between the robot terminal coordinate system and the camera coordinate system; />The method is a conversion relation between a robot tail end coordinate system and a robot base coordinate;
the relation between the robot base and the calibration plate is fixed, the calibration plate with the camera fixed at different angles is shot by moving the end of the robot, and the calibration plate is used for drawingImage processing to obtainAnd read out +.>Then, calculate ∈>
5. The method for collecting and measuring the three-dimensional model of the segment steel mold according to claim 1, wherein in the step S4, the binocular camera collects all the coordinates of the points of the left and right end surfaces and the points of the front and rear side surfaces of each segment steel mold to obtain the outer surface data of the segment steel mold.
6. The method for collecting and measuring the three-dimensional model of the segment steel mold according to claim 1, wherein in the step S5, the robot collects the partial image of the segment steel mold with a binocular camera, and the point cloud using the optical center of the left camera at the moment as the origin of the coordinate system can be calculated by using the internal and external parameters of the camera and the calculated characteristic point parallax, and the point cloud is used as the partial three-dimensional characteristic description of the segment steel mold.
7. The method for collecting and measuring the three-dimensional model of the segment steel mould according to claim 1, wherein in the step S6, the conversion relation between a camera coordinate system obtained by hand-eye calibration and a tool coordinate system of a robot and the tail end coordinates of the robot when each local three-dimensional description is generated are utilized to convert the local three-dimensional description in different coordinate systems into the three-dimensional coordinates of a robot base coordinate system, so as to obtain the complete three-dimensional description of the segment steel mould;
wherein P is cam(i) The coordinate system origin of the three-dimensional point cloud set generated for utilizing the steel mould local image acquired by the ith acquisition is positioned at the optical center of the left camera;the conversion relation between the coordinate system of the flange at the tail end of the robot and the coordinate system of the camera with the left camera optical center as the origin of the coordinate system is represented, and the conversion relation is determined through hand-eye calibration; />The conversion relation between the robot base coordinate system and the robot terminal flange coordinate system during the ith acquisition is represented;
meanwhile, the method is calculated through hand-eye calibrationBut->The three-dimensional coordinates P of the steel mould point cloud under the robot base coordinate system are calculated by utilizing the following steps of reading from a robot demonstrator when collecting the partial images of the segment steel mould base ；
Due to the above P base The three-dimensional point clouds are three-dimensional coordinates under a robot base coordinate system, so that the local three-dimensional point clouds of the steel mould under different coordinate systems are synthesized into the whole three-dimensional description of the steel mould under a unified coordinate system, and support is provided for subsequent measurement of the size of the steel mould.
8. The method for collecting and measuring a three-dimensional model of a segment steel mold according to claim 1, wherein in step S7,
firstly, performing cylinder fitting in the generated steel mould three-dimensional model to obtain an equation of a cylinder where the intrados of the steel mould is located, which is shown in the following formula.
Wherein, (x) 0 ，y 0 ，z 0 ) R is the radius of the cylinder, and (l, m, n) is the vector of the direction of the cylinder axis;
then, a known point (x 0 ，y 0 ，z 0 ) After translating to the origin of the three-dimensional coordinate system, calculating a direction vector (l, m, n) and a Z-axis clamping angle alpha, and enabling the cylindrical axis to be overlapped with the Z axis after integrally rotating the steel mould three-dimensional model alpha;
according to the segment design rule, the two side dies are perpendicular to the axis of the cylinder where the bottom die is located, and the included angles between the side dies and the XOY plane and the YOZ plane are calculated respectively and used as judgment bases for detecting the installation accuracy of the side dies;
comparing the included angles of the side mold and the XOY plane and the YOZ plane with the design value, and calculating the deviation of the angles in the two directions to be used as the basis for adjusting the installation angle of the side mold;
then, respectively calculating the included angles of the end die and the XOY plane and the XOZ plane, and taking the included angles as a judgment basis for detecting the mounting precision of the end die;
and comparing the included angles of the end die and the XOY plane as well as the XOZ plane with the design value, and calculating the deviation of the angles in the two directions to be used as the basis for adjusting the installation angle of the end die.
9. The method for collecting and measuring a three-dimensional model of a segment steel mold according to claim 1, wherein in step S8,
firstly, after calculating the distance between the point cloud of the inner arc surface of the steel die and the axis of the fitting cylinder of the inner arc surface, dividing the difference between the distance and the radius of the fitting cylinder into a plurality of intervals from small to large as arc surface roundness error, respectively calculating the point cloud duty ratio of each difference interval, and finally taking the proportional distribution as the roundness measurement of the inner arc surface of the steel die;
after calculating the distance between the end mode point cloud in the normal vector direction of the end simulation resultant plane and the end simulation resultant plane, dividing the distance into a plurality of sections from small to large, respectively calculating the point cloud duty ratio of each distance section, and finally taking the proportion distribution as the flatness measurement of the end mode plane;
after calculating the distance between the side model point cloud and the side model fitting plane in the normal vector direction of the side model fitting plane, dividing the distance into a plurality of sections from small to large, respectively calculating the point cloud duty ratio of each distance section, and finally taking the proportional distribution as the flatness measurement of the side model plane.
10. The method for collecting and measuring a three-dimensional model of a segment steel mold according to claim 1, wherein in step S9,
firstly, calculating an intersection point of an intersection line between a left end die plane and a front side die plane and an intrados of the segment steel film model by using the following formula;
then, taking an intersection point which is close to the center point of the intrados of the segment steel die from the two calculated intersection points as an intersection point of the left end die, the front side die and the intrados;
after the processing is carried out on the side die, the end die and the inner and outer cambered surfaces respectively, three-dimensional coordinates of a measuring key point of the segment steel die are obtained and used as the basis for evaluating the size specification of the segment steel die, and the segment quality is evaluated;
finally, calculating the linear distances between the vertexes of the four sides of the inner surface and the outer surface of the segment steel mould;
calculating the arc length of the inner arc side and the outer arc side of the end face of the segment steel die;
and calculating the arc length between the inner arc surface and the outer arc surface of the segment steel die and the corner points.
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