CN117029691A - Segment three-dimensional model acquisition and measurement method - Google Patents
Segment three-dimensional model acquisition and measurement method Download PDFInfo
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- CN117029691A CN117029691A CN202310898694.4A CN202310898694A CN117029691A CN 117029691 A CN117029691 A CN 117029691A CN 202310898694 A CN202310898694 A CN 202310898694A CN 117029691 A CN117029691 A CN 117029691A
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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
- G06T—IMAGE DATA PROCESSING OR GENERATION, IN GENERAL
- G06T17/00—Three dimensional [3D] modelling, e.g. data description of 3D objects
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- G—PHYSICS
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- G06T7/00—Image analysis
- G06T7/80—Analysis of captured images to determine intrinsic or extrinsic camera parameters, i.e. camera calibration
Abstract
The application discloses a segment three-dimensional model acquisition and measurement method, which is characterized in that 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 segment local three-dimensional description; s6, obtaining a complete three-dimensional description of the segment; s7, segment size measurement. According to the technical scheme, the binocular vision system is matched with the robot coordinate system to finish high-precision measurement of the duct piece, a quick and accurate duct piece measurement technology is provided, the duct piece is completely inspected, and powerful technical support is provided for efficient, automatic and intelligent duct piece 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 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. 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. These basic requirements determine the requirements of the duct piece to ensure higher dimensional accuracy and appearance quality.
The pipe sheet production method is basically adopted in China because the pipe sheet production method has the advantages of reducing environmental pollution of field production, reducing logistics blockage, playing industrial operation management and the like.
Meanwhile, in general engineering, more than 800 rings of duct pieces are produced on average per sleeve piece, and the precision of a finished product-the duct piece is guaranteed to meet the design requirement every time, so that quick and accurate duct piece outline dimension measurement plays a vital role in quality control of the duct piece and improvement of duct piece production efficiency.
Because the duct piece has the characteristics of irregular shape (circular arc with radius of 3-4 meters), large size (span of 4-6 meters), high precision requirement (error is less than 0.2 millimeter) and the like, the realization difficulty of the high-precision and rapid duct piece measuring method 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 measuring means, the domestic duct piece measurement still stays in two-dimensional dimension detection stages such as width, arc length, height and the like, and the integral deformation generated in the duct piece production process cannot be detected. After deformation of the segment is detected, no guiding repair basis exists. For example, when the width dimension exceeds the limit value, it cannot be determined which of the two side dies is deformed; the same is true for the detection of arc length. Meanwhile, under the condition that the width dimension of the duct piece is completely qualified, the two end side dies deform or misplacement in the same direction. 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 measurement cannot be well met.
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 components such as duct pieces 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.
Disclosure of Invention
In order to solve the defects and shortcomings in the prior art, the patent provides a segment three-dimensional model acquisition and measurement method.
In particular, the application provides a segment three-dimensional model acquisition and measurement method,
a segment 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 pieces by the binocular camera according to the moving path of the robot, and sequentially acquiring the outer surface data of all the duct pieces;
s5, obtaining a segment local three-dimensional description;
s6, obtaining a complete three-dimensional description of the segment;
s7, segment size measurement.
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, x ] 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, depth information Z of the point cloud is calculated using the following equation:
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 together with the robot tip, and the hand-eye calibration function is to obtain a conversion 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, the calibration plate with the camera carried at the tail end of the mobile robot fixed at different angles is obtained after the image processing of the calibration plateAnd 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, and acquires the outer surface data of the segment.
In step S5, the robot collects a partial image of the segment with the binocular camera, and calculates a point cloud using the optical center of the left camera as the origin of the coordinate system by using the internal and external parameters of the camera and the calculated characteristic point parallax, and uses the point cloud as a partial three-dimensional characteristic description of the segment.
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 under different coordinate systems into the three-dimensional coordinate under the robot base coordinate system, so as to obtain the complete three-dimensional description of the segment;
wherein P is cam(i) The coordinate system origin of the three-dimensional point cloud set generated by utilizing the segment local image acquired by the ith acquisition is positioned at the optical center of the left camera;the method comprises the steps of representing a conversion relation between a robot tail end 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; />The conversion relation between the robot base coordinate system and the robot tail end coordinate system during the ith acquisition is represented;
meanwhile, the method is calculated through hand-eye calibrationBut->The segment point cloud three-dimensional coordinate P under the robot base coordinate system is calculated by reading from a robot demonstrator when the segment local image is acquired by utilizing the following formula 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 segment local three-dimensional point clouds under different coordinate systems are synthesized into segment integral three-dimensional description under a unified coordinate system, and support is provided for subsequent segment size measurement.
Further, in step S6,
firstly, performing cylinder fitting in the generated segment three-dimensional model to obtain an equation of a cylinder where the intrados of the segment 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;
subsequently, the axis is movedThe 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 enabling the segment three-dimensional model to integrally rotate 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 judging bases for judging whether the side die angles are correct or not;
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 judging basis for judging whether the end die angle is correct or not;
next, calculating an intersection point of an intersection line between the left end die plane and the front side die plane and the intrados by using the following formula;
then, taking the intersection point which is close to the center point of the intrados as the intersection point of the left end mould, the front side mould and the intrados from the two calculated intersection points;
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 number 1-8 are obtained and used as the basis for evaluating the segment size specification, and the segment quality is evaluated;
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 located and the inner cambered surface cylinder, and then the treatment is carried out.
Further, in step S7, the steps according to the present application include:
calculating the linear distances between the vertexes of the four sides of the inner surface and the outer surface of the segment;
calculating the arc length of the side edge of the inner arc surface and the outer arc surface of the end face of the segment;
and calculating the arc length between the inner arc surface and the outer arc surface of the segment and the corner points.
The application has the advantages and positive effects that:
according to the technical scheme, the binocular vision system is matched with the robot coordinate system to finish high-precision measurement of the duct piece, a rapid and accurate duct piece detection technology is provided, the duct piece is detected completely, and powerful technical support is provided for efficient, automatic and intelligent duct piece 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 schematic view of a segment structure.
Fig. 2 is a diagram of a robot binocular camera detection.
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 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, respectively performing internal parameter calibration on the two cameras, wherein the internal parameter calibration of the cameras is mainly used for obtaining an internal parameter matrix and a distortion coefficient of the cameras.
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 the calibration plate photographed by each camera is solved individually 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 systemP base The coordinates in the robot base coordinate system are 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 pass through machineRobot 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 detection points to be detected, and respectively acquiring the intrados, the left end face and the right end face of the duct piece and the image information of the front side face and the rear side face.
Step 5 segment local three-dimensional description acquisition
The robot carries a binocular camera to a proper position, acquires a local image of the duct piece, 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 takes the point cloud as a local three-dimensional characteristic description of the duct piece.
Step 6, segment complete three-dimensional description generation
The process can collect the local three-dimensional description of the duct piece, and the coordinate system origins of the local three-dimensional description of the duct piece are different due to the fact that the binocular camera needs to be moved when the different positions of the duct piece are collected. The whole set of the local three-dimensional descriptions at the origins of different coordinate systems cannot accurately restore the three-dimensional morphology of the segment, so that the local three-dimensional descriptions need to be unified to a certain coordinate system, and the complete three-dimensional description of the segment can be obtained.
The conversion relation between a camera coordinate system obtained by hand-eye calibration and a 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 under different coordinate systems into the three-dimensional coordinate of a robot base coordinate system, so that the complete three-dimensional description of the duct piece is obtained, and duct piece size 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 by utilizing the segment local image acquired by the ith acquisition is positioned at the optical center of the left camera;the conversion relation between the robot tail end coordinate system and the camera coordinate system 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; />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->Can be read from the robot demonstrator by collecting the segment local images. For this purpose, the three-dimensional coordinates P of the segment point cloud in the robot base coordinate system can be calculated by using 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 segment local three-dimensional point clouds under different coordinate systems are synthesized into segment integral three-dimensional description under a unified coordinate system, and support is provided for subsequent segment size measurement.
Step 7 segment size measurement
Firstly, performing cylinder fitting in the generated segment three-dimensional model to obtain an equation of a cylinder where the intrados of the segment is located 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 enabling the segment three-dimensional model to integrally rotate 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 judging bases for judging whether the side die angles are correct or not;
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 judging basis for judging whether the end die angle is correct or not;
next, calculating an intersection point of an intersection line between the left end die plane and the front side die plane and the intrados by using the following formula;
then, taking the intersection point which is close to the center point of the intrados as the intersection point of the left end mould, the front side mould and the intrados from the two calculated intersection points;
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 the segment measurement key points 1-8 as shown in the figure can be obtained and used as a basis for evaluating the segment size specification and the 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, 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 segment, 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 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 (9)
1. A segment 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 pieces by the binocular camera according to the moving path of the robot, and sequentially acquiring the outer surface data of all the duct pieces;
s5, obtaining a segment local three-dimensional description;
s6, obtaining a complete three-dimensional description of the segment;
s7, segment size measurement.
2. The method for collecting and measuring a three-dimensional model of a segment according to claim 1, wherein in step S1, calibration plate images are collected from different positions for a plurality of times, and two camera internal references are calculated respectively by the accurate positions of the calibration points in the calibration plate images.
3. The segment three-dimensional model acquisition and measurement method according to claim 1, wherein in step S2, first, rotation and translation relationships R of each calibration plate photographed by each camera are 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, right camera is provided with +.>Conversion relation, get ∈10 after arrangement>The 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, depth information Z of the point cloud is calculated using the following equation:
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 segment three-dimensional model acquisition and measurement method according to claim 1, wherein in step S3, a camera is installedOn the robot end, as the robot end moves together, the hand-eye calibration function 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; />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 carried at the tail end of the mobile robot fixed at different angles is obtained after the image processing of the calibration plateAnd read out +.>Then, calculate ∈>
5. The method for collecting and measuring a three-dimensional model of a segment according to claim 1, wherein in step S4, the binocular camera collects all the coordinates of points on the left and right end surfaces and the front and rear side surfaces of each segment to obtain the outer surface data of the segment.
6. The method for collecting and measuring a three-dimensional model of a segment according to claim 1, wherein in step S5, the robot collects a partial image of the segment with a binocular camera, and uses the internal and external parameters of the camera and the calculated parallax of the feature points to calculate a point cloud using the optical center of the left camera as the origin of the coordinate system, and describes the point cloud as a partial three-dimensional feature of the segment.
7. The segment three-dimensional model acquisition and measurement method according to claim 1, wherein in step S6, the conversion relation between a camera coordinate system obtained by hand-eye calibration and a 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 under different coordinate systems into the three-dimensional coordinate under a robot base coordinate system, so as to obtain the complete three-dimensional description of the segment;
wherein P is cam (i) The coordinate system origin of the three-dimensional point cloud set generated by utilizing the segment local image acquired by the ith acquisition is positioned at the optical center of the left camera;the method comprises the steps of representing a conversion relation between a robot tail end 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; />The conversion relation between the robot base coordinate system and the robot tail end coordinate system during the ith acquisition is represented;
meanwhile, the method is calculated through hand-eye calibrationBut->The segment point cloud three-dimensional coordinate P under the robot base coordinate system is calculated by reading from a robot demonstrator when the segment local image is acquired by utilizing the following formula 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 segment local three-dimensional point clouds under different coordinate systems are synthesized into segment integral three-dimensional description under a unified coordinate system, and support is provided for subsequent segment size measurement.
8. The method for collecting and measuring a three-dimensional model of a segment according to claim 1, wherein in step S6,
firstly, performing cylinder fitting in the generated segment three-dimensional model to obtain an equation of a cylinder where the intrados of the segment 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 enabling the segment three-dimensional model to integrally rotate 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 judging bases for judging whether the side die angles are correct or not;
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 judging basis for judging whether the end die angle is correct or not;
next, calculating an intersection point of an intersection line between the left end die plane and the front side die plane and the intrados by using the following formula;
then, taking the intersection point which is close to the center point of the intrados as the intersection point of the left end mould, the front side mould and the intrados from the two calculated intersection points;
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 number 1-8 are obtained and used as the basis for evaluating the segment size specification, and the segment quality is evaluated;
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 located and the inner cambered surface cylinder, and then the treatment is carried out.
9. The method for collecting and measuring a three-dimensional model of a segment according to claim 7, wherein in step S7, the method comprises the following steps:
calculating the linear distances between the vertexes of the four sides of the inner surface and the outer surface of the segment;
calculating the arc length of the side edge of the inner arc surface and the outer arc surface of the end face of the segment;
and calculating the arc length between the inner arc surface and the outer arc surface of the segment and the corner points.
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