CN114279325B - System and method for calibrating spatial position relation of measurement coordinate system of vision measurement module - Google Patents
System and method for calibrating spatial position relation of measurement coordinate system of vision measurement module Download PDFInfo
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Abstract
The invention relates to a system and a method for calibrating the spatial position relation of a measurement coordinate system of a vision measurement module, which can quickly realize the accurate calibration of the spatial position relation of the measurement coordinate system of two machine vision measurement modules in a pose measurement device, can realize the conversion from two-dimensional plane coordinates to three-dimensional space coordinates in a two-dimensional image measurement coordinate system, and realize the contact measurement of the three-dimensional coordinates of space image points in a three-coordinate measurement machine by materializing an abstract facula imaging center. The method is mainly used for calibrating the spatial position relation of the visual measurement module image measurement coordinate system in the spatial pose measurement device, and ensures the measurement precision of the spatial pose measurement device.
Description
Technical Field
The invention belongs to the technical field of vision measurement, and particularly relates to a system and a method for calibrating a spatial position relation of a measurement coordinate system of a vision measurement module.
Background
The vision measurement technique has been rapidly developed in recent years due to its advantages such as non-contact property, high dynamic property, high accuracy, and the like. The image sensor is used as a key device of a visual measurement technology product, plays a key role in acquiring the image of a part to be measured, and for the visual device for realizing measurement by utilizing the multi-image sensor, the calibration of the position relation between the image coordinate systems is a basis for realizing the whole measurement.
The existing common binocular vision camera external parameter, namely two measurement coordinate system relation calibration method is provided with a camera external parameter calibration method based on a Zhang Zhengyou chessboard grid method, and the method is used on the premise that two cameras can acquire the same chessboard grid image at the same time, however, in some space position measurement devices based on laser and machine vision, on one hand, the working coordinate system of an image sensor is built on a laser imaging receiving screen, and on the other hand, because the laser imaging receiving screen shields the image sensor, a plurality of image sensors cannot acquire calibration plate images directly at the same time, so that the traditional image coordinate system relation calibration method is not applicable any more.
The invention can effectively solve the calibration problem of the relation between the image coordinate systems established on the two image receiving screens in the space position measuring device based on laser and machine vision.
Disclosure of Invention
The invention aims to overcome the defects of the prior art, and provides a system and a method for calibrating the spatial position relation of a measurement coordinate system of a vision measurement module, which can rapidly realize the accurate calibration of the spatial position relation of the measurement coordinate system of images of two machine vision measurement modules in a spatial pose measurement device.
The invention solves the technical problems by the following technical proposal:
a visual measurement module measurement coordinate system space position relation calibration system is characterized in that: the calibration system comprises a space pose measuring device, a point structure light generator, a V-shaped positioning groove and a three-coordinate measuring machine,
the point structure light generator is used for generating point structure light and providing a point light spot image acquired by the image sensor in the calibration process;
the V-shaped positioning groove is used for calibrating the installation point structure light generator in the process;
the three-coordinate measuring machine comprises a contact measuring head, a marble measuring platform, a measuring head motion remote control handle, an industrial personal computer and a measuring system, and is used for realizing contact measurement of space coordinate points in the calibration process;
the space pose measuring device comprises two sets of image acquisition units, a laser beam splitting and refracting optical path unit, an industrial personal computer and measuring software, wherein the image acquisition units comprise an image sensing module A, an image sensing module B, a laser receiving screen A, a laser receiving screen B, an image sensor A and an image sensor B, the laser beam splitting and refracting optical path unit comprises a laser beam splitting module and a refracting optical path module, and the image sensor A and the image sensor B are respectively and fixedly connected to the rear sides of the laser receiving screen A and the laser receiving screen B and are used for acquiring laser spot images on the laser receiving screen; the industrial personal computer is connected with the image sensor A and the image sensor B through USB, so that image signals of the image sensor are collected, and the central coordinates of the light spots are extracted through the measuring software.
And the laser receiving screen A and the laser receiving screen B are made of transparent acrylic plates, and the outer sides of the laser receiving screen A and the laser receiving screen B are coated with nanometer diffuse reflection coatings.
A calibration method for measuring the spatial position relation of a coordinate system by a vision measurement module is characterized by comprising the following steps of: the calibration method comprises the following steps:
1) A thin plate chessboard grid is attached to the inner sides of a laser receiving screen A and a laser receiving screen B of the space pose measuring device, perspective distortion and radial distortion of an image sensor A and an image sensor B are respectively corrected by a known camera distortion correction method, and optical axes of the corrected image sensor A and the corrected image sensor B are vertical to a plane where the laser receiving screen is located;
2) Taking down the laser beam splitting module, and taking down a plane reflector of the laser beam splitting module;
3) Placing the space pose measuring device on a marble measuring platform of the three-coordinate measuring machine, starting the three-coordinate measuring machine, opening the industrial personal computer and the measuring system, and establishing a space pose measuring device coordinate system O-XYZ;
4) Placing the point structure light generator on a V-shaped positioning groove, opening the point structure light generator, enabling the V-shaped positioning groove to be close to a laser receiving screen A, and ensuring that a spot image of the point structure light generator (3-5) on the laser receiving screen A is located in the field of view of the image sensor A;
5) The axis of the V-shaped positioning groove is perpendicular to the laser receiving screen A, the end face of the point structure light generator is guaranteed to be tightly attached to the laser receiving screen A, and coordinate values of the center point of an image facula acquired by the image sensor at the moment are read out through the industrial personal computer and measurement software;
6) The point structure light generator is rotated in the V-shaped positioning groove, the central coordinate value of an image light spot in the industrial personal computer and the measuring software is observed, the lens end face of the point structure light generator is continuously adjusted to be tightly attached to the laser receiving screen A, the central coordinate value of the laser light spot in the industrial personal computer and the measuring software is not changed in the rotating process of the point structure light generator, the axis of the laser light spot is indicated to coincide with the axis of the shell of the point structure light generator, the axis of the point structure light generator is perpendicular to the laser receiving screen A, the central coordinate value (x 1, y 1) pixel of the light spot at the moment is recorded, the point structure light generator and the V-shaped positioning groove are fixed through the pressing device, and the position relation between the point structure light generator and the receiving screen is kept unchanged;
7) Moving a remote control handle through a measuring head, moving a contact measuring head of a three-coordinate measuring machine, carrying out cylindrical measurement on the surface of a shell of the point structure light generator under an O-XYZ coordinate system, measuring at least 5 points, fitting a cylindrical surface, and constructing a central axis 1 through the fitted cylindrical surface;
8) Moving a contact type measuring head of a three-coordinate measuring machine through a measuring head moving remote control handle, carrying out plane measurement on the inner surface of a laser receiving screen A under an O-XYZ coordinate system, measuring at least 5 points, and fitting a plane 1;
9) The intersection point coordinates (X1, Y1, Z1) of the equation of the central axis 1 and the corresponding equation of the plane 1 of the laser receiving screen A are the space position coordinates of the spot center of the spot laser, and are marked as a mark point 1;
10 Moving the spot-structured light generator along the horizontal direction for a certain distance to ensure that the moved laser light spot is still positioned in the view field range of the image sensor A;
11 Repeating the steps 5-9, recording the coordinate value (X2, Y2) pixel of the center of the light spot when the coordinate of the light spot of the rotating point structure light generator is unchanged, and recording the coordinate (X2, Y2, Z2) of the intersection point of the fitting axis equation of the outer shell of the point structure light generator and the plane equation of the laser receiving screen A, namely the space position coordinate of the center of the laser light spot at the moment, as a marking point 2;
12 Placing the point structure light generator on the V-shaped positioning groove, opening the point structure light generator, enabling the V-shaped positioning groove to be close to the laser receiving screen B, and ensuring that the spot imaging of the point structure light generator on the laser receiving screen B is located in the field of view of the image sensor B;
13 Repeating the steps 4-11, and respectively recording coordinate values (X3, Y3) pixel of the mark point 3 light spot center in the measuring coordinate system of the image sensor B and space position coordinates (X3, Y3, Z3) of the corresponding point laser light spot center, and coordinate values (X4, Y4) pixel of the mark point 4 light spot center in the measuring coordinate system of the image sensor B and space position coordinates (X4, Y4, Z4) of the corresponding point laser light spot center;
14 Mounting the laser beam splitting module and mounting the plane reflecting mirror;
15 In the industrial personal computer and the measuring system, the established coordinate system of the O-XYZ space pose measuring device is taken as a measuring coordinate system, the probe is contacted with a plane corresponding to measurement by controlling the remote control moving handle, at least five points are measured on each plane, and equations of the plane of the corresponding laser beam splitter and the plane of the three plane reflectors in the folding light path are measured and fitted;
16 Processing the light spot image coordinates and the space coordinate data under the coordinate system of the space pose measuring device to obtain the space position relation between the two coordinate systems.
The processing method of the spot image coordinates and the space coordinates in the step 16) is as follows:
the plane equation of the laser beam splitter obtained by fitting the three-coordinate measuring machine is as follows:
wherein: (A, B, C) is the normal vector of plane 1;
(X a ，Y a ，Z a ) Is a point on plane 1;
the plane equation of the plane mirror (1-4-1) is set as follows:
wherein: (D, E, F) is the normal vector of the plane;
(X b ，Y b ，Z b ) Is a point on the plane;
the equation for the plane in which the plane mirror (1-4-2) is arranged is:
wherein: (G, H, I) is the normal vector of the plane,
(X c ，Y c ，Z c ) Is a point on the plane;
the equation for the plane in which plane mirror (1_4-3) is set is:
wherein: (J, K, L) is the normal vector of the plane;
(X d ，Y d ，Z d ) Is a point on the plane;
the equation for the plane in which the plane mirrors (1-4-3) are arranged is:
wherein: (M, N, P) is the normal vector of the plane;
(X e ，Y e ，Z e ) Is a point on the plane;
in an industrial personal computer and measurement software, the coordinate system of a pose measurement device is used as a measurement coordinate system, the data are processed, the corresponding spatial position relation in the coordinate system O-XYZ of the pose measurement device after the two image measurement coordinate systems are subjected to beam splitting and folding light path actions is obtained, the plane of a laser receiving screen A, a mirror plane R and mirror symmetry points of a mark point 1 and a mark point 2 relative to the plane of a laser beam splitter (1-3-1) are made in the industrial personal computer and measurement software, and the spatial coordinate values of the mark point 1 'and the mark point 2' can be read by three-coordinate measurement software;
the method comprises the steps of making a plane of a laser receiving screen B, a space coordinate point of a mark point 3 and a space coordinate point of a mark point 4 in three-coordinate machine software, and respectively obtaining the mark point 3 'and the mark point 4' by a mirror plane S and a mirror symmetry point after the plane of a plane mirror (1-4-3), the plane of a plane mirror (1-4-2) and the plane of a plane mirror (1-4-1) are symmetrical, wherein the space coordinate values of the space coordinate points can be read by three-coordinate measuring software;
let the equation for plane R be:
wherein: (X) r ，Y r ，Z r ) Is a point on plane R;
(R X ，R Y ，R Z : ) Is the normal vector of the plane;
the equation for plane S is:
wherein: (X) s ，Y s ，Z s : ) Is a point on plane R;
(S x ，S Y ，S Z ) Is the normal vector of the plane;
1) Calculating the rotation angle:
2) Through the obtained rotation angle, the image coordinate system is rotated by a known method, so that the two image coordinate systems after the action of the measuring light path are rotated and then are parallel to the Y axis of the measuring coordinate system 0-XYZ of the pose measuring device; the coordinate values of the rotated mark points 1', 2', 3', 4' are (X1 ", Y1", Z1 "), (X2", Y2", Z2"), (X3 ", Y3", Z3 "), and (X4", Y4", Z4"), respectively;
3) Calculating two image sensor conversion coefficients:
4) Setting the pixel values of the image sensor as X0 and Y0 pixels, and calculating the spatial positions of the origins of the two image coordinate systems in the pose measurement coordinate system after the light path function: taking an image coordinate system of the image sensor a on the laser receiving screen a as an example:
setting the origin of the coordinate system as (X) 0 ，Y 0 ，Z 0 ) After the light path is acted, the origin is positioned on the plane R, so that the plane equation is satisfied:
origin (X) 0 ，Y 0 ，Z 0 ) The distance from the OXY plane is l=k1·y1+z1", i.e.
Z 0 ＝K1·y1+Z1″
Origin (X) 0 ，Y 0 ，Z 0 ) Distance from OYZ plane is L' =k1·x1+y1", i.e
Y 0 ＝K1·x1+Y1″
Coordinate values of the origin of the image coordinate system 1 in the measurement coordinate system O-XYZ can be obtained by combining the above 3 types; similarly, the coordinate value of the origin of the image coordinate system 2 in the measurement coordinate system O-XYZ can be obtained, and the relation between the two coordinate systems can be obtained by combining the equation of the laser receiving screen A, B.
The invention has the advantages and beneficial effects that:
1. the system and the method for calibrating the spatial position relation of the measurement coordinate system of the vision measurement module solve the problem that the spatial position relation of the measurement coordinate system of the multi-image sensing system cannot be calibrated by the traditional method due to shielding of the receiving screen, and can realize the contact type accurate calibration of the spatial position relation of the measurement coordinate system of the vision measurement module image in the spatial pose measurement device.
2. The system and the method for calibrating the spatial position relation of the measurement coordinate system of the vision measurement module can quickly realize the accurate calibration of the spatial position relation of the measurement coordinate system of the image measurement coordinate system of the two machine vision measurement modules in the pose measurement device, can realize the conversion from two-dimensional plane coordinates to three-dimensional spatial coordinates in the two-dimensional image measurement coordinate system, realize the materialization of an abstract facula imaging center and realize the contact measurement of the three-dimensional coordinates of space image points in a three-coordinate measuring machine. The method is mainly used for calibrating the spatial position relation of the visual measurement module image measurement coordinate system in the spatial pose measurement device, and ensures the measurement precision of the spatial pose measurement device.
Drawings
FIG. 1 is a schematic diagram of a space pose measurement device according to the present invention;
FIG. 2 is a schematic illustration of the calibration process of the present invention;
FIG. 3 is a schematic representation of the calibration details of the present invention.
Description of the reference numerals
1-1: an image sensing module A;1-2: an image sensing module B;1-3: a laser beam splitting module; 1-4: folding the light path module; 1-1-1: an image sensor A;1-1-2: a laser receiving screen A;1-2-1: an image sensor B;1-2-2: a laser receiving screen B;1-3-1: a laser beam splitter; 1-4-1: a plane mirror 1;1-4-2: a plane mirror 2;1-4-3: a plane mirror 3;2-1: a space pose measuring device; 2-2: a three-coordinate measuring machine; 2-3: the industrial personal computer and the measuring software; 2-4: the industrial personal computer and the measuring system; 2-2-1: a measuring head moves a remote control handle; 2-2-2: a contact probe; 3-1: measuring an X axis of a coordinate system by using a space pose; 3-2: a space pose measurement coordinate system Y axis; 3-3: measuring a Z axis of a coordinate system by using the space pose; 3-4: v positioning type groove; 3-5: a point structured light generator.
Detailed Description
The invention is further illustrated by the following examples, which are intended to be illustrative only and not limiting in any way.
A calibration system for measuring the spatial position relation of a coordinate system by a vision measurement module is characterized in that: the calibration system comprises a space pose measuring device 2-1, a point structure light generator 3-5, a V-shaped positioning groove 3-4 and a three-coordinate measuring machine 2-2,
the point structure light generator 3-5 is used for generating point structure light and providing a point light spot image acquired by the image sensor in the calibration process;
the V-shaped positioning groove 3-4 is used for calibrating a mounting point structure light generator in the process;
the three-coordinate measuring machine 2-2 comprises a contact measuring head 2-2-2, a marble measuring platform, a measuring head movement remote control handle 2-2-1, an industrial personal computer and a measuring system 2-4, and is used for realizing contact measurement of space coordinate points in the calibration process;
the space pose measuring device 2-1 comprises two sets of image acquisition units, a laser beam splitting and refracting light path unit, an industrial personal computer and measuring software 2-3, wherein the image acquisition units comprise an image sensing module A1-1, an image sensing module B1-2, a laser receiving screen A1-1-2, a laser receiving screen B1-2-2, an image sensor A1-1-1 and an image sensor B1-2-1, the laser beam splitting and refracting light path unit comprises a laser beam splitting module 1-3 and a refracting light path module 1-4, and the image sensor A1-1-1 and the image sensor B1-2-1 are respectively fixedly connected to the rear sides of the laser receiving screen A1-1-2 and the laser receiving screen B1-2-2 so as to acquire laser spot images on the laser receiving screen; the industrial personal computer is connected with the image sensor A1-1-1 and the image sensor B1-2-1 through USB and the measuring software 2-3 to collect image signals of the image sensor, and the measuring software is used for extracting central coordinates of light spots.
The laser receiving screens A1-1-2 and B1-2-2 are made of transparent acrylic plates, and the outer sides of the laser receiving screens A1-1-2 and B1-2-2 are coated with nanometer diffuse reflection coatings.
A calibration method for measuring the spatial position relation of a coordinate system by a vision measurement module is characterized by comprising the following steps of: the calibration method comprises the following steps:
1) A thin plate chessboard grid is attached to the inner sides of a laser receiving screen A and a laser receiving screen B of the space pose measuring device, perspective distortion and radial distortion of an image sensor A and an image sensor B are respectively corrected by a known camera distortion correction method, and optical axes of the corrected image sensor A and the corrected image sensor B are vertical to a plane where the laser receiving screen is located;
2) Taking down the laser beam splitting module, and taking down a plane reflector of the laser beam splitting module;
3) Placing the space pose measuring device on a marble measuring platform of the three-coordinate measuring machine, starting the three-coordinate measuring machine, opening the industrial personal computer and the measuring system, and establishing a space pose measuring device coordinate system O-XYZ;
4) Placing the point structure light generator on a V-shaped positioning groove, opening the point structure light generator, enabling the V-shaped positioning groove to be close to the laser receiving screen A, and ensuring that the spot imaging of the point structure light generator 3-5 on the laser receiving screen A is positioned in the field of view of the image sensor A;
5) The axis of the V-shaped positioning groove is perpendicular to the laser receiving screen A, the end face of the point structure light generator is guaranteed to be tightly attached to the laser receiving screen A, and coordinate values of the center point of an image facula acquired by the image sensor at the moment are read out through the industrial personal computer and measurement software;
6) The point structure light generator is rotated in the V-shaped positioning groove, the central coordinate value of an image light spot in the industrial personal computer and the measuring software is observed, the lens end face of the point structure light generator is continuously adjusted to be tightly attached to the laser receiving screen A, the central coordinate value of the laser light spot in the industrial personal computer and the measuring software is not changed in the rotating process of the point structure light generator, the axis of the laser light spot is indicated to coincide with the axis of the shell of the point structure light generator, the axis of the point structure light generator is perpendicular to the laser receiving screen A, the central coordinate value (x 1, y 1) pixel of the light spot at the moment is recorded, the point structure light generator and the V-shaped positioning groove are fixed through the pressing device, and the position relation between the point structure light generator and the receiving screen is kept unchanged;
7) Moving a remote control handle through a measuring head, moving a contact measuring head of a three-coordinate measuring machine, carrying out cylindrical measurement on the surface of a shell of the point structure light generator under an O-XYZ coordinate system, measuring at least 5 points, fitting a cylindrical surface, and constructing a central axis 1 through the fitted cylindrical surface;
8) Moving a contact type measuring head of a three-coordinate measuring machine through a measuring head moving remote control handle, carrying out plane measurement on the inner surface of a laser receiving screen A under an O-XYZ coordinate system, measuring at least 5 points, and fitting a plane 1;
9) The intersection point coordinates (X1, Y1, Z1) of the equation of the central axis 1 and the corresponding equation of the plane 1 of the laser receiving screen A are the space position coordinates of the spot center of the spot laser, and are marked as a mark point 1;
10 Moving the spot-structured light generator along the horizontal direction for a certain distance to ensure that the moved laser light spot is still positioned in the view field range of the image sensor A;
11 Repeating the steps 5-9, recording the coordinate value (X2, Y2) pixel of the center of the light spot when the coordinate of the light spot of the rotating point structure light generator is unchanged, and recording the coordinate (X2, Y2, Z2) of the intersection point of the fitting axis equation of the outer shell of the point structure light generator and the plane equation of the laser receiving screen A, namely the space position coordinate of the center of the laser light spot at the moment, as a marking point 2;
12 Placing the point structure light generator on the V-shaped positioning groove, opening the point structure light generator, enabling the V-shaped positioning groove to be close to the laser receiving screen B, and ensuring that the spot imaging of the point structure light generator on the laser receiving screen B is located in the field of view of the image sensor B;
13 Repeating the steps 4-11, and respectively recording coordinate values (X3, Y3) pixel of the mark point 3 light spot center in the measuring coordinate system of the image sensor B and space position coordinates (X3, Y3, Z3) of the corresponding point laser light spot center, and coordinate values (X4, Y4) pixel of the mark point 4 light spot center in the measuring coordinate system of the image sensor B and space position coordinates (X4, Y4, Z4) of the corresponding point laser light spot center;
14 Mounting the laser beam splitting module and mounting the plane reflecting mirror;
15 In the industrial personal computer and the measuring system, the established coordinate system of the O-XYZ space pose measuring device is taken as a measuring coordinate system, the probe is contacted with a plane corresponding to measurement by controlling the remote control moving handle, at least five points are measured on each plane, and equations of the plane of the corresponding laser beam splitter and the plane of the three plane reflectors in the folding light path are measured and fitted;
16 Processing the light spot image coordinates and the space coordinate data under the coordinate system of the space pose measuring device to obtain the space position relation between the two coordinate systems.
The processing method of the spot image coordinates and the space coordinates in the step 16) is as follows:
the plane equation of the laser beam splitter obtained by fitting the three-coordinate measuring machine is as follows:
wherein: (A, B, C) is the normal vector of plane 1;
(X a ，Y a ，Z a ) Is a point on plane 1;
the plane equation of the plane mirror (1-4-1) is set as follows:
wherein: (D, E, F) is the normal vector of the plane;
(X b ，Y b ，Z b ) Is a point on the plane;
the equation for the plane in which the plane mirror (1-4-2) is arranged is:
wherein: (G, H, I) is the normal vector of the plane,
(X c ，Y c ，Z c ) Is a point on the plane;
the equation for the plane in which the plane mirrors (1-4-3) are arranged is:
wherein: (J, K, L) is the normal vector of the plane;
(Xd, yd, zd) is a point on the plane;
the equation for the plane in which plane mirror (1_4-3) is set is:
wherein: (M, N, P) is the normal vector of the plane;
(X e ，Y e ，Z e ) Is a point on the plane;
in an industrial personal computer and measurement software, the coordinate system of a pose measurement device is used as a measurement coordinate system, the data are processed, the corresponding spatial position relation in the coordinate system O-XYZ of the pose measurement device after the two image measurement coordinate systems are subjected to beam splitting and folding light path actions is obtained, the plane of a laser receiving screen A, a mirror plane R and mirror symmetry points of a mark point 1 and a mark point 2 relative to the plane of a laser beam splitter (1-3-1) are made in the industrial personal computer and measurement software, and the spatial coordinate values of the mark point 1 'and the mark point 2' can be read by three-coordinate measurement software;
the method comprises the steps of making a plane of a laser receiving screen B, a space coordinate point of a mark point 3 and a space coordinate point of a mark point 4 in three-coordinate machine software, and respectively obtaining the mark point 3 'and the mark point 4' by a mirror plane S and a mirror symmetry point after the plane of a plane mirror (1-4-3), the plane of a plane mirror (1-4-2) and the plane of a plane mirror (1-4-1) are symmetrical, wherein the space coordinate values of the space coordinate points can be read by three-coordinate measuring software;
let the equation for plane R be:
wherein: (X) r ，Y r ，Z r ) Is a point on plane R;
(R X ，R Y ，R Z : ) Is the normal vector of the plane;
the equation for plane S is:
wherein: (X) s ，Y s ，Z s : ) Is a point on plane R;
(S X ，S Y ，S Z ) Is the normal vector of the plane;
1) Calculating the rotation angle:
4) Through the obtained rotation angle, the image coordinate system is rotated by a known method, so that the two image coordinate systems after the action of the measuring light path are rotated and then are parallel to the Y axis of the measuring coordinate system 0-XYZ of the pose measuring device; the coordinate values of the rotated mark points 1', 2', 3', 4' are (X1 ", Y1", Z1 "), (X2", Y2", Z2"), (X3 ", Y3", Z3 "), and (X4", Y4", Z4"), respectively;
5) Calculating two image sensor conversion coefficients:
4) Setting the pixel values of the image sensor as X0 and Y0 pixels, and calculating the spatial positions of the origins of the two image coordinate systems in the pose measurement coordinate system after the light path function: taking an image coordinate system of the image sensor a on the laser receiving screen a as an example:
measuring coordinates in pose with origin of coordinate systemThe three-dimensional coordinates in the system are (X 0 ，Y 0 ，Z 0 ) After the light path is acted, the origin is positioned on the plane R, so that the plane equation is satisfied:
origin (X) 0 ，Y 0 ，Z 0 ) The distance from the OXY plane is l=k1·y1+z1", i.e.
Z 0 ＝K1·y1+Z1″
Origin (X) 0 ，Y 0 ，Z 0 ) Distance from OYZ plane is L' =k1·x1+y1", i.e
Y 0 ＝K1·x1+Y1″
Coordinate values of the origin of the image coordinate system 1 in the measurement coordinate system O-XYZ can be obtained by combining the above 3 types; similarly, the coordinate value of the origin of the image coordinate system 2 in the measurement coordinate system O-XYZ can be obtained, and the relation between the two coordinate systems can be obtained by combining the equation of the laser receiving screen A, B.
Although the embodiments of the present invention and the accompanying drawings have been disclosed for illustrative purposes, those skilled in the art will appreciate that: various substitutions, changes and modifications are possible without departing from the spirit and scope of the invention and the appended claims, and therefore the scope of the invention is not limited to the embodiments and the disclosure of the drawings.
Claims (4)
1. A visual measurement module measurement coordinate system space position relation calibration system is characterized in that: the calibration system comprises a space pose measuring device (2-1), a point structure light generator (3-5), a V-shaped positioning groove (3-4) and a three-coordinate measuring machine (2-2),
the point structure light generator (3-5) is used for generating point structure light and providing a point light spot image acquired by the image sensor in the calibration process;
the V-shaped positioning groove (3-4) is used for installing the point structure light generator in the calibration process;
the three-coordinate measuring machine (2-2) comprises a contact measuring head (2-2-2), a marble measuring platform, a measuring head movement remote control handle (2-2-1) and an industrial personal computer and measuring system (2-4) which are used for realizing contact measurement of space coordinate points in the calibration process;
the space pose measuring device (2-1) comprises two sets of image acquisition units, a laser beam splitting and refracting optical path unit, an industrial personal computer and measuring software (2-3), wherein the image acquisition units comprise an image sensing module A (1-1), an image sensing module B (1-2), a laser receiving screen A (1-1-2), a laser receiving screen B (1-2-2), an image sensor A (1-1-1) and an image sensor B (1-2-1), the laser beam splitting and refracting optical path unit comprises a laser beam splitting module (1-3) and a refracting optical path module (1-4), and the image sensor A (1-1-1) and the image sensor B (1-2-1) are respectively fixedly connected to the rear sides of the laser receiving screen A (1-1-2) and the laser receiving screen B (1-2-2) so as to acquire laser spot images on the laser receiving screen; the industrial personal computer is connected with the measuring software (2-3) through USB and the image sensor A (1-1-1) and the image sensor B (1-2-1) to collect image signals of the image sensor, and the measuring software is used for extracting central coordinates of light spots.
2. The vision measurement module measurement coordinate system spatial position relationship calibration system according to claim 1, wherein: the laser receiving screen A (1-1-2) and the laser receiving screen B (1-2-2) are made of transparent acrylic plates, and the outer sides of the laser receiving screen A (1-1-2) and the laser receiving screen B (1-2-2) are coated with nanometer diffuse reflection coatings.
3. The method for calibrating spatial position relation of measurement coordinate system of vision measurement module according to claim 1 or 2, wherein the method comprises the following steps: the calibration method comprises the following steps:
1) A thin plate chessboard grid is attached to the inner sides of a laser receiving screen A and a laser receiving screen B of the space pose measuring device, perspective distortion and radial distortion of an image sensor A and an image sensor B are respectively corrected by a known camera distortion correction method, and optical axes of the corrected image sensor A and the corrected image sensor B are vertical to a plane where the laser receiving screen is located;
2) Taking down the laser beam splitting module, and taking down a plane reflector of the laser beam splitting module;
3) Placing the space pose measuring device on a marble measuring platform of the three-coordinate measuring machine, starting the three-coordinate measuring machine, opening the industrial personal computer and the measuring system, and establishing a space pose measuring device coordinate system O-XYZ;
4) Placing the point structure light generator on a V-shaped positioning groove, opening the point structure light generator, enabling the V-shaped positioning groove to be close to a laser receiving screen A, and ensuring that a spot image of the point structure light generator (3-5) on the laser receiving screen A is located in the field of view of the image sensor A;
5) The axis of the V-shaped positioning groove is perpendicular to the laser receiving screen A, the end face of the point structure light generator is guaranteed to be tightly attached to the laser receiving screen A, and coordinate values of the center point of an image facula acquired by the image sensor at the moment are read out through the industrial personal computer and measurement software;
6) The point structure light generator is rotated in the V-shaped positioning groove, the central coordinate value of an image light spot in the industrial personal computer and the measuring software is observed, the lens end face of the point structure light generator is continuously adjusted to be tightly attached to the laser receiving screen A, the central coordinate value of the laser light spot in the industrial personal computer and the measuring software is not changed in the rotating process of the point structure light generator, the axis of the laser light spot is indicated to coincide with the axis of the shell of the point structure light generator, the axis of the point structure light generator is perpendicular to the laser receiving screen A, the central coordinate value (x 1, y 1) pixel of the light spot at the moment is recorded, the point structure light generator and the V-shaped positioning groove are fixed through the pressing device, and the position relation between the point structure light generator and the receiving screen is kept unchanged;
7) Moving a remote control handle through a measuring head, moving a contact measuring head of a three-coordinate measuring machine, carrying out cylindrical measurement on the surface of a shell of the point structure light generator under an O-XYZ coordinate system, measuring at least 5 points, fitting a cylindrical surface, and constructing a central axis 1 through the fitted cylindrical surface;
8) Moving a contact type measuring head of a three-coordinate measuring machine through a measuring head moving remote control handle, carrying out plane measurement on the inner surface of a laser receiving screen A under an O-XYZ coordinate system, measuring at least 5 points, and fitting a plane 1;
9) The intersection point coordinates (X1, Y1, Z1) of the equation of the central axis 1 and the corresponding equation of the plane 1 of the laser receiving screen A are the space position coordinates of the spot center of the spot laser, and are marked as a mark point 1;
10 Moving the spot-structured light generator along the horizontal direction for a certain distance to ensure that the moved laser light spot is still positioned in the view field range of the image sensor A;
11 Repeating the steps 5-9, recording the coordinate value (X2, Y2) pixel of the center of the light spot when the coordinate of the light spot of the rotating point structure light generator is unchanged, and recording the coordinate (X2, Y2, Z2) of the intersection point of the fitting axis equation of the outer shell of the point structure light generator and the plane equation of the laser receiving screen A, namely the space position coordinate of the center of the laser light spot at the moment, as a marking point 2;
12 Placing the point structure light generator on the V-shaped positioning groove, opening the point structure light generator, enabling the V-shaped positioning groove to be close to the laser receiving screen B, and ensuring that the spot imaging of the point structure light generator on the laser receiving screen B is located in the field of view of the image sensor B;
13 Repeating the steps 4-11, and respectively recording coordinate values (X3, Y3) pixel of the mark point 3 light spot center in the measuring coordinate system of the image sensor B and space position coordinates (X3, Y3, Z3) of the corresponding point laser light spot center, and coordinate values (X4, Y4) pixel of the mark point 4 light spot center in the measuring coordinate system of the image sensor B and space position coordinates (X4, Y4, Z4) of the corresponding point laser light spot center;
14 Mounting the laser beam splitting module and mounting the plane reflecting mirror;
15 In the industrial personal computer and the measuring system, the established coordinate system of the O-XYZ space pose measuring device is taken as a measuring coordinate system, the probe is contacted with a plane corresponding to measurement by controlling the remote control moving handle, at least five points are measured on each plane, and equations of the plane of the corresponding laser beam splitter and the planes of the three plane reflectors in the refraction light path are measured and fitted;
16 Processing the light spot image coordinates and the space coordinate data under the coordinate system of the space pose measuring device to obtain the space position relation between the two coordinate systems.
4. A method for calibrating spatial position relation of a measurement coordinate system of a vision measurement module according to claim 3, wherein the method comprises the following steps: the processing method of the spot image coordinates and the space coordinates in the step 16) comprises the following steps:
the plane equation of the laser beam splitter obtained by fitting the three-coordinate measuring machine is as follows:
wherein: (A, B, C) is the normal vector of plane 1;
(X a ，Y a ，Z a ) Is a point on plane 1;
the plane equation of the plane mirror (1-4-1) is set as follows:
wherein: (D, E, F) is the normal vector of the plane;
(X b ，Y b ，Z b ) Is a point on the plane;
the equation for the plane in which the plane mirror (1-4-2) is arranged is:
wherein: (G, H, I) is the normal vector of the plane,
(X c ，Y c ，Z c ) Is a point on the plane;
the equation for the plane in which the plane mirrors (1-4-3) are arranged is:
wherein: (J, K, L) is the normal vector of the plane;
(X d ，Y d ，Z d ) Is a point on the plane;
the equation for the plane in which the plane mirrors (1-4-3) are arranged is:
wherein: (M, N, P) is the normal vector of the plane;
(X e ，Y e ，Z e ) Is a point on the plane;
in an industrial personal computer and measurement software, the coordinate system of a pose measurement device is used as a measurement coordinate system, the data are processed, the corresponding spatial position relation of the two image measurement coordinate systems in the coordinate system O-XYZ of the pose measurement device after the action of beam splitting and refraction light paths is obtained, the plane of a laser receiving screen A, a mirror plane R and mirror symmetry points of a mark point 1 and a mark point 2 relative to the plane of a laser beam splitter (1-3-1) are made in the industrial personal computer and measurement software, and the spatial coordinate values of the mark point 1 'and the mark point 2' can be read by three-coordinate measurement software;
the method comprises the steps of making a plane of a laser receiving screen B, a space coordinate point of a mark point 3 and a space coordinate point of a mark point 4 in three-coordinate machine software, and respectively obtaining the mark point 3 'and the mark point 4' by a mirror plane S and a mirror symmetry point after the plane of a plane mirror (1-4-3), the plane of a plane mirror (1-4-2) and the plane of a plane mirror (1-4-1) are symmetrical, wherein the space coordinate values of the space coordinate points can be read by three-coordinate measuring software;
let the equation for plane R be:
wherein: (X) r ，Y r ，Z r ) Is a point on plane R;
(R X ，R Y ，R Z ) Is the normal vector of the plane;
the equation for plane S is:
wherein: (X) s ，Y s ，Z s ) Is a point on the plane S;
(S X ，S Y ，S Z ) Is the normal vector of the plane;
1) Calculating the rotation angle:
2) Through the obtained rotation angle, the image coordinate system is rotated by a known method, so that the two image coordinate systems after the action of the measuring light path are rotated and then are parallel to the Y axis of the measuring coordinate system 0-XYZ of the pose measuring device; the coordinate values of the rotated mark points 1', 2', 3', 4' are (X1 ", Y1", Z1 "), (X2", Y2", Z2"), (X3 ", Y3", Z3 "), and (X4", Y4", Z4"), respectively;
3) Calculating two image sensor conversion coefficients:
4) Setting the pixel values of the image sensor as X0 and Y0 pixels, and calculating the spatial positions of the origins of the two image coordinate systems in the pose measurement coordinate system after the light path function: for an image coordinate system of the image sensor a on the laser receiving screen a:
setting the origin of the coordinate system as (X) O ，Y O ，Z O ) After the light path is acted, the origin is positioned on the plane R, so that the plane equation is satisfied:
origin (X) O ，Y O ，Z O ) The distance from the OXY plane is l=k1·y1+z1", i.e.
Z 0 ＝K1·y1+Z1”
Origin (X) O ，Y O ，Z O ) The distance from the OYZ plane is L' =k1·x1+y1", i.e
Y 0 ＝K1·x1+Y1″
Coordinate values of the origin of the image coordinate system 1 in the measurement coordinate system O-XYZ can be obtained by combining the above 3 types; similarly, the coordinate value of the origin of the image coordinate system 2 in the measurement coordinate system O-XYZ can be obtained, and the relation between the two coordinate systems can be obtained by combining the equation of the laser receiving screen A, B.
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