CN113358098A - Portable detection method and system based on intelligent reverse positioning - Google Patents
Portable detection method and system based on intelligent reverse positioning Download PDFInfo
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- G—PHYSICS
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- 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
- G01B11/002—Measuring arrangements characterised by the use of optical techniques for measuring two or more coordinates
- G01B11/005—Measuring arrangements characterised by the use of optical techniques for measuring two or more coordinates coordinate measuring machines
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Abstract
The invention provides a portable detection method and a portable detection system based on intelligent reverse positioning.A stable reference body is preset as an auxiliary measurement scene matched with a measurement light pen, a plurality of mark points and coding pieces are fixed on the surface of the stable reference body as targets, the position relation between a probe of the measurement light pen and a monocular camera is calibrated to obtain the relative pose between the probe and the camera, the coding pieces and the mark points of the stable reference body are identified by the monocular camera to position and fix the pose of the monocular camera and the probe, and the intelligent reverse positioning is realized. And obtaining the three-dimensional coordinate of the measured point on the workpiece to be measured according to the pose of the probe, thereby realizing the portable and contact type detection of the three-dimensional coordinate by the monocular camera. The target is arranged on the stable reference body, is not limited on the measuring light pen, and is large in number, so that the measuring precision is improved, and the measuring range of the measuring light pen is expanded.
Description
Technical Field
The invention relates to the technical field of photogrammetry and positioning, in particular to a portable detection method and a system based on intelligent reverse positioning.
Background
With the development of high-end intelligent manufacturing industry, various high-end intelligent manufacturing technologies are continuously emerging. The traditional industrial measuring means is based on scanning analysis and hard contact type analysis comparison, the hard contact type is generally divided into a joint arm and a three-coordinate measuring machine, the mode is relatively fixed, and the scene is relatively fixed, namely, a method system for realizing portable detection by using an intelligent reverse positioning method is created;
the development of high-end manufacturing industry has higher requirements on product quality, so that the measurement and detection of industrial products also have higher requirements, and the measurement and detection of industrial products are light and handy, portable, real-time and intelligent in processing, good man-machine interaction and automation work are all considered.
The measurement light pens (CMM probes) currently available on the market and retrievable in the literature are classified into two major categories, one is that a three-coordinate measuring machine, a six-axis or eight-axis robot arm, etc. are integrated with probes, the positions of Probe probes are measured by these mechanical motion devices through mathematical transformation of the rotation angle of a motor, and the other is that a mark point, a light emitting LED, etc. (collectively called a target) are integrated with probes, and the mark point or the light emitting LED on a Probe is tracked by a single camera, a dual camera, or a plurality of cameras, so that the positions of the Probe probes are calculated.
The first Probe has a disadvantage that the measuring range is limited by the size of the mechanical movement device, and such devices are generally heavy and inconvenient to carry.
The second Probe has the disadvantage that the number of targets on the Probe is very limited and the size of the targets is limited, which greatly reduces the accuracy of the Probe. In addition, the tracking accuracy of a single camera is often not high (mainly because the target size is limited), and the tracking of a dual camera often requires a long enough distance between two cameras, so that the size of the device is often large, and the carrying convenience is limited. In addition, the field of view of the camera is limited, and the position of the camera needs to be kept still whether the camera is a single camera or a double camera, so that the measurement range is limited by the field of view of the camera.
Disclosure of Invention
The embodiment of the invention provides a portable detection method and a portable detection system based on intelligent reverse positioning, which realize positioning and attitude determination of a monocular camera and a probe by identifying a code sheet and a mark point of a stable reference body through the monocular camera, and further obtain a three-dimensional coordinate of a measured point on a workpiece to be measured according to the attitude of the probe.
In a first aspect, an embodiment of the present invention provides a portable detection method based on intelligent reverse positioning, including:
s1, presetting a stable reference body as an auxiliary measurement scene matched with the measurement light pen, and fixing a plurality of mark points and coding pieces on the surface of the stable reference body as targets; acquiring the coordinates of mark points and the coordinates of a coding piece on the surface of a pre-measured stable reference body through the photogrammetric function of a monocular camera;
s2, calibrating the position relation between the probe of the measuring light pen and the monocular camera to obtain the relative pose between the probe and the camera; wherein the probe is rigidly connected with the monocular camera;
s3, calculating the pose of the monocular camera according to at least 3 mark points/encoding sheet coordinates in the visual field range of the monocular camera;
s4, acquiring the pose of the probe according to the pose of the monocular camera and the relative pose between the probe and the camera;
and S5, obtaining the three-dimensional coordinates of the measured point on the workpiece to be measured according to the pose of the probe.
Optionally, in step S1, the acquiring, by the photogrammetry function of the monocular camera, coordinates of the mark point and coordinates of the code piece of the previously measured stable reference body surface includes:
shooting images of the stable reference body surface mark points and the coding sheet by using a monocular camera;
and extracting the coordinates of the mark points and the coordinates of the coding pieces according to the images of the mark points and the coding pieces.
Optionally, in step S2, the calibrating the position relationship between the probe of the measurement light pen and the monocular camera to obtain the relative pose between the probe and the camera includes:
the calibration cone is stably placed in the stable reference body, the probe head of the measuring light pen is stably placed in the calibration cone to swing to different postures, the rotation and translation matrixes of the probe head under different postures are obtained through the monocular camera, and then the relative pose between the probe and the monocular camera is calculated.
Optionally, before step S3, the method further includes:
and numbering the coded slice coordinates of the stable reference body according to a preset rule.
Optionally, in step S3, the calculating the pose of the monocular camera according to at least 3 landmark points/coded slice coordinates within the field of view of the monocular camera specifically includes:
the coordinates of the three marker points/code patches A, B, C are known, the focus center of the monocular camera is located at point P, and a ' ═ BC |, b ' ═ AC |, c ' ═ AB |; let X ═ PA |, Y ═ PB |, Z ═ PC |; let X ═ xZ, Y ═ yZ; it is known that α ═ PB, PC >, β ═ PA, PB >, γ ═ PA, PC >;
a'2＝ac'2、b'2＝bc'2、c'2＝vZ2Where p ═ 2cos α, q ═ 2cos β, and r ═ 2cos γ, then there are a'2＝ac'2＝avZ2， b'2＝bc'2＝bvZ2；
The constraint equation is derived from the P, A, B, C non-coplanarity: p is a radical of2+q2+r2-pqr-1≠0；
According to the cosine theorem of the triangle, the following formula can be obtained in three triangles formed by P, A, B, C four points:
Y2+Z2-2YZcosα＝a'2(1)
X2+Z2-2XZcosβ＝b'2(2)
Y2+X2-2YXcosγ＝c'2(3)
the above three equations (1) (2) (3) are converted into the following equations according to the defined parameter relationships:
(1-a)y2-ax2+axyr-yp+1＝0 (4)
(1-b)x2-by2+bxyr-xq+1＝0 (5)
solving x, y and v by a Wu zero decomposition method according to equations (4) and (5); bound parameter relationship bc'2＝bvZ2Determining X, Y and Z, wherein X is xZ, and Y is yZ;
after the distance X, Y, Z from the point A, B, C to the focusing center of the monocular camera is calculated, the coordinates of the points A, B and C in the camera coordinate system are respectively calculated according to the triangle similarity principle, and the pose of the monocular camera is obtained by combining the coordinates of the mark points/encoding sheets measured in advance.
Optionally, the stable reference body includes, but is not limited to, an indoor wall, a steel structure scaffold, or an indoor supporting column.
In a second aspect, an embodiment of the present invention further provides a portable detection system based on intelligent reverse positioning, including a measuring light pen, a stable reference body, and a computing device, where a plurality of mark points and a code sheet are fixed on the surface of the stable reference body as a target;
the measuring light pen at least comprises a monocular camera and a probe which are rigidly connected, the monocular camera faces towards the stable reference body, the probe faces towards the workpiece to be measured, and the monocular camera is in communication connection with the computing device;
the monocular camera is used for collecting images of the stable reference body surface mark points and the coding sheet and transmitting the images to the computing device;
a calibration cone is fixedly arranged in the stable reference body and used for calibrating the position relation between a probe of the measuring light pen and the monocular camera to obtain the relative pose between the probe and the camera;
the computing device includes:
the extraction unit is used for receiving the images of the mark points and the coding pieces on the surface of the stable reference body and extracting the coordinates of the mark points and the coordinates of the coding pieces from the images;
the camera pose calculation unit is used for calculating the pose of the monocular camera according to at least 3 mark points/code sheet coordinates in the visual field range of the monocular camera;
the probe pose obtaining unit is used for obtaining the pose of the probe according to the pose of the monocular camera and the relative pose between the probe and the camera;
and the measured point coordinate obtaining unit is used for obtaining the three-dimensional coordinate of the measured point on the workpiece to be measured according to the pose of the probe.
Optionally, the camera pose calculation unit is specifically configured to:
the coordinates of the three marker points/code patches A, B, C are known, the focus center of the monocular camera is located at point P, and a ' ═ BC |, b ' ═ AC |, c ' ═ AB |; let X ═ PA |, Y ═ PB |, Z ═ PC |; let X ═ xZ, Y ═ yZ; it is known that α ═ PB, PC >, β ═ PA, PB >, γ ═ PA, PC >;
a'2＝ac'2、b'2＝bc'2、c'2＝vZ2Where p ═ 2cos α, q ═ 2cos β, and r ═ 2cos γ, then there are a'2＝ac'2＝avZ2， b'2＝bc'2＝bvZ2；
The constraint equation is derived from the P, A, B, C non-coplanarity: p is a radical of2+q2+r2-pqr-1≠0；
According to the cosine theorem of the triangle, the following formula can be obtained in three triangles formed by P, A, B, C four points:
Y2+Z2-2YZcosα＝a'2(1)
X2+Z2-2XZcosβ＝b'2(2)
Y2+X2-2YXcosγ＝c'2(3)
the above three equations (1) (2) (3) are converted into the following equations according to the defined parameter relationships:
(1-a)y2-ax2+axyr-yp+1＝0 (4)
(1-b)x2-by2+bxyr-xq+1＝0 (5)
solving x, y andv; bound parameter relationship bc'2＝bvZ2Determining X, Y and Z, wherein X is xZ, and Y is yZ;
after the distance X, Y, Z from the point A, B, C to the focusing center of the monocular camera is calculated, the coordinates of the points A, B and C in the camera coordinate system are respectively calculated according to the triangle similarity principle, and the pose of the monocular camera is obtained by combining the coordinates of the mark points/encoding sheets measured in advance.
Optionally, the surface of the measuring light pen is provided with a plurality of probe joints, and the probe joints are used for fixedly mounting the probes.
Optionally, the probe comprises a probe metal rod and a probe head arranged at one end of the probe metal rod, and the probe head is made of ruby.
According to the portable detection method and system based on intelligent reverse positioning, provided by the embodiment of the invention, the monocular camera is used for identifying the coding sheet and the mark point of the stable reference body, so that the positioning and attitude determination of the monocular camera and the probe are carried out, and the intelligent reverse positioning is realized. And obtaining the three-dimensional coordinate of the measured point on the workpiece to be measured according to the pose of the probe, thereby realizing the portable and contact type detection of the three-dimensional coordinate by the monocular camera. The target is arranged on the stable reference body, is not limited on the measuring light pen, and is large in number, so that the measuring precision is improved. And the measuring range of the measuring light pen is enlarged, the range of the stable reference body surface target is large, and the measuring range is large, so that the measuring range of the measuring light pen is not limited any more.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below, and it is obvious that the drawings in the following description are some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to these drawings without creative efforts.
Fig. 1 is a flow chart of a portable detection method based on intelligent reverse positioning according to an embodiment of the present invention;
FIG. 2(a) is a schematic structural diagram of a stable reference body;
FIG. 2(b) is another schematic structural view of a stable reference body;
FIG. 3 is a schematic diagram of global photogrammetry provided by an embodiment of the present invention;
FIG. 4 is a schematic structural diagram of a measurement light pen according to an embodiment of the present invention;
FIG. 5 is a schematic view of a contact detection measurement provided by an embodiment of the present invention;
fig. 6 is a schematic diagram of the P3P algorithm according to an embodiment of the present invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are some, but not all, embodiments of the present invention. All other embodiments, which can be obtained by a person skilled in the art without any inventive step based on the embodiments of the present invention, are within the scope of the present invention.
Reference herein to "an embodiment" means that a particular feature, structure, or characteristic described in connection with the embodiment can be included in at least one embodiment of the application. The appearances of the phrase in various places in the specification are not necessarily all referring to the same embodiment, nor are separate or alternative embodiments mutually exclusive of other embodiments. It is explicitly and implicitly understood by one skilled in the art that the embodiments described herein can be combined with other embodiments.
Fig. 1 is a flow chart showing a portable detection method based on intelligent reverse positioning according to an embodiment of the present invention, and as shown in fig. 1, the portable detection method based on intelligent reverse positioning according to an embodiment of the present invention includes, but is not limited to, the following steps:
s1, presetting a stable reference body as an auxiliary measurement scene matched with the measurement light pen, and fixing a plurality of mark points and coding pieces on the surface of the stable reference body as targets; acquiring the coordinates of mark points and the coordinates of a coding piece on the surface of a pre-measured stable reference body through the photogrammetric function of a monocular camera;
s2, calibrating the position relation between the probe of the measuring light pen and the monocular camera to obtain the relative pose between the probe and the camera; wherein the probe is rigidly connected with the monocular camera;
s3, calculating the pose of the monocular camera according to at least 3 mark points/encoding sheet coordinates in the visual field range of the monocular camera;
s4, acquiring the pose of the probe according to the pose of the monocular camera and the relative pose between the probe and the camera;
and S5, obtaining the three-dimensional coordinates of the measured point on the workpiece to be measured according to the pose of the probe.
Specifically, the invention uses the measuring light pen to perform contact measurement on the workpiece to be measured, in step S1, the measuring light pen needs an auxiliary measuring scene matched with the measuring light pen, the invention presets a stable reference body as the auxiliary measuring scene matched with the measuring light pen, and the stable reference body is a large scene which is not easy to deform, such as an indoor wall, a steel structure scaffold, an indoor supporting column and the like, and is collectively called as a stable reference body. To ensure the stability of the stable reference body, the stable reference body provided in this embodiment has the following requirements: 1. keeping away from a vibration source, otherwise, adding a vibration-proof foundation; 2. controlling the temperature of the measuring chamber to be 20 +/-5 ℃; 3. if the point 2 can not be realized, the temperature difference between the temperature during measurement and the temperature during the collection of the coding sheet does not exceed +/-5 ℃; 4. the surface roughness is less than Ra3.2 (the code piece is easy to fall off when the roughness is larger). It will be appreciated that the above requirement is a reference condition for a stable reference body and is not intended as a limitation on a stable reference body.
Fig. 2 is a schematic diagram of two stable reference bodies provided by the embodiment of the present invention. Wherein, fig. 2(a) is a schematic structural diagram of a stable reference body; FIG. 2(b) is a schematic view of another structure of the stabilized reference body; fig. 2(a) and 2(b) show two stable references, namely an indoor wall and a steel structure scaffold, respectively. A large number of mark points and coding pieces are required to be arranged on the surface of a stable reference body to serve as a target, and the pasting range of the target is required to be larger than the visual field range of a monocular camera, such as the range of 3-20 meters. The target is arranged on the stable reference body, is not limited on the measuring light pen, and is large in number, so that the measuring accuracy is improved. The measuring range of the measuring light pen is expanded, the range of the stable reference body surface target is large, and the measuring range is large, so that the measuring range of the measuring light pen is not limited any more.
After a large number of mark points and coding pieces are arranged on the surface of the stable reference body as targets, as a possible embodiment mode, a monocular camera is adopted to acquire images of the mark points and the coding pieces on the surface of the stable reference body, and global photogrammetry is carried out. Fig. 3 is a schematic diagram of global photogrammetry provided in an embodiment of the present invention. Then, the monocular camera transmits the image to a computing device connected with the monocular camera, and the computing device extracts the coordinates of the mark points and the coordinates of the coded slice according to the image of the mark points and the coded slice. Fig. 4 is a schematic structural diagram of a measurement light pen according to an embodiment of the present invention, where the measurement light pen at least includes a monocular camera, a probe, and a connector, and the monocular camera and the probe are rigidly connected through the connector. A plurality of probe connectors are arranged on the surface of one side of the connector, and the specifications of the probe connectors can be different, so that probes with different lengths and diameters can be conveniently replaced. Compared with the existing measuring light pen, the measuring light pen provided by the embodiment of the invention has the advantages of simple structure, light weight, small volume and portability. In this embodiment, the lens of the monocular camera uses a lens with a viewing angle of not less than 40 degrees and not more than 100 degrees, a too small viewing angle easily causes a too small viewing range, which may reduce the positioning accuracy, while a too large viewing angle generally has a larger distortion, which may also reduce the positioning accuracy.
In step S2, before performing contact measurement on the workpiece to be measured, the position relationship between the probe of the measurement optical pen and the monocular camera needs to be calibrated to obtain the relative pose between the probe and the camera. Next, in step S3, the pose of the monocular camera is calculated from at least 3 landmark points/code patch coordinates within the field of view of the monocular camera. Referring to fig. 3, the monocular camera is oriented towards the stable reference volume such that there are no less than 3 marker points or code slices in the monocular camera field of view all the time. In step S4, the pose of the probe can be obtained from the pose of the monocular camera and the relative pose between the probe and the camera.
Fig. 5 is a schematic view of contact detection measurement according to an embodiment of the present invention, and as shown in fig. 5, in this embodiment, a workpiece to be measured is disposed at one end of a probe of a measurement light pen, the probe is directed toward the workpiece to be measured, contact detection measurement is performed, a probe head of the probe is used to measure a measured point of the workpiece to be measured, and a three-dimensional coordinate of the measured point on the workpiece to be measured can be obtained according to a pose of the probe.
According to the portable detection method based on intelligent reverse positioning, provided by the embodiment of the invention, the monocular camera is used for identifying the code sheet and the mark point of the stable reference body, so that the positioning and attitude determination are carried out on the monocular camera and the probe, and the intelligent reverse positioning is realized. And obtaining the three-dimensional coordinate of the measured point on the workpiece to be measured according to the pose of the probe, thereby realizing the portable and contact type detection of the three-dimensional coordinate by the monocular camera.
In a possible embodiment, in step S2, the calibrating the position relationship between the probe of the measurement light pen and the monocular camera to obtain the relative pose between the probe and the camera specifically includes:
the calibration cone is stably placed in the stable reference body, the probe head of the measuring light pen is stably placed in the calibration cone to swing to different postures, the rotation and translation matrixes of the probe head under different postures are obtained through the monocular camera, and then the relative pose between the probe and the monocular camera is calculated.
In the embodiment, the position relation between the probe of the measuring light pen and the monocular camera is calibrated to obtain the accurate position relation between the probe and the monocular camera, so that the pose of the probe can be obtained according to the pose of the monocular camera.
In a possible embodiment, before step S3, the portable detection method based on intelligent reverse positioning further includes: and numbering the coded slice coordinates of the stable reference body according to a preset rule.
Specifically, in this embodiment, the coordinates of the encoding pieces of the stable reference body are numbered according to a preset rule, and are organized into a data format of { point sequence numbers (a, B, C) }, which is convenient for calculating the pose of the monocular camera according to the coordinates of the numbered encoding pieces.
Fig. 6 is a schematic diagram of the P3P algorithm according to an embodiment of the present invention. In a possible embodiment, in step S3, the calculating the pose of the monocular camera according to at least 3 landmark points/code patch coordinates within the field of view of the monocular camera specifically includes:
the coordinates of the three index points/code patches A, B, C are known, the focus center of the monocular camera is located at point P, and referring to fig. 6, a ' ═ BC |, b ' ═ AC |, c ' ═ AB |; let X ═ PA |, Y ═ PB |, Z ═ PC |; let X ═ xZ, Y ═ yZ; it is known that α ═ PB, PC >, β ═ PA, PB >, γ ═ PA, PC >;
a'2＝ac'2、b'2＝bc'2、c'2＝vZ2Where p ═ 2cos α, q ═ 2cos β, and r ═ 2cos γ, then there are a'2＝ac'2＝avZ2， b'2＝bc'2＝bvZ2；
The constraint equation is derived from the P, A, B, C non-coplanarity: p is a radical of2+q2+r2-pqr-1≠0；
According to the cosine theorem of the triangle, the following formula can be obtained in three triangles formed by P, A, B, C four points:
Y2+Z2-2YZcosα＝a'2(1)
X2+Z2-2XZcosβ＝b'2(2)
Y2+X2-2YXcosγ＝c'2(3)
the above three equations (1) (2) (3) are converted into the following equations according to the defined parameter relationships:
(1-a)y2-ax2+axyr-yp+1＝0 (4)
(1-b)x2-by2+bxyr-xq+1＝0 (5)
solving x, y and v by a Wu zero decomposition method according to equations (4) and (5); bound parameter relationship bc'2＝bvZ2Determining X, Y and Z, wherein X is xZ, and Y is yZ;
after the distance X, Y, Z from the point A, B, C to the focusing center of the monocular camera is calculated, the coordinates of the points A, B and C in the camera coordinate system are respectively calculated according to the triangle similarity principle, and the pose of the monocular camera is obtained by combining the coordinates of the mark points/encoding sheets measured in advance.
In this embodiment, according to at least 3 coordinates of the mark Points/encoding pieces in the visual field range of the monocular camera, the pose of the monocular camera is calculated by using the improved P3P (Perspective 3Points) algorithm, so that the calculation accuracy of the pose of the monocular camera is improved, and the measurement accuracy of the workpiece to be measured can be improved.
In one embodiment, the embodiment of the present invention further provides a portable detection system based on intelligent reverse positioning, including a measuring light pen, a stable reference body and a computing device, wherein the stable reference body has several fixed mark points and a code sheet as targets;
the measuring light pen at least comprises a monocular camera and a probe which are rigidly connected, and referring to fig. 5, the monocular camera faces towards the stable reference body, the probe faces towards the workpiece to be measured, and the monocular camera is in communication connection with the computing device;
the monocular camera is used for collecting images of the stable reference body surface mark points and the coding sheet and transmitting the images to the computing device;
a calibration cone is fixedly arranged in the stable reference body and used for calibrating the position relation between a probe of the measuring light pen and the monocular camera to obtain the relative pose between the probe and the camera;
the computing device includes:
the extraction unit is used for receiving the images of the mark points and the coding pieces on the surface of the stable reference body and extracting the coordinates of the mark points and the coordinates of the coding pieces from the images;
the camera pose calculation unit is used for calculating the pose of the monocular camera according to at least 3 mark points/code sheet coordinates in the visual field range of the monocular camera;
the probe pose obtaining unit is used for obtaining the pose of the probe according to the pose of the monocular camera and the relative pose between the probe and the camera;
and the measured point coordinate obtaining unit is used for obtaining the three-dimensional coordinate of the measured point on the workpiece to be measured according to the pose of the probe.
It can be understood that the portable detection system based on intelligent reverse positioning provided by the present invention corresponds to the portable detection method based on intelligent reverse positioning provided by the foregoing embodiments, and the relevant technical features of the portable detection system based on intelligent reverse positioning may refer to the relevant technical features of the portable detection method based on intelligent reverse positioning, and are not described herein again.
In a possible embodiment, the camera pose calculation unit of the calculation apparatus is specifically configured to:
referring to fig. 6, the coordinates of the three index points/code patches A, B, C are known, the focus center of the monocular camera is located at point P, and a ' ═ BC |, b ' ═ AC |, c ' ═ AB |; let X ═ PA |, Y ═ PB |, Z ═ PC |; let X ═ xZ, Y ═ yZ; it is known that α ═ PB, PC >, β ═ PA, PB >, γ ═ PA, PC >;
a'2＝ac'2、b'2＝bc'2、c'2＝vZ2Where p ═ 2cos α, q ═ 2cos β, and r ═ 2cos γ, then there are a'2＝ac'2＝avZ2， b'2＝bc'2＝bvZ2；
The constraint equation is derived from the P, A, B, C non-coplanarity: p is a radical of2+q2+r2-pqr-1≠0；
According to the cosine theorem of the triangle, the following formula can be obtained in three triangles formed by P, A, B, C four points:
Y2+Z2-2YZcosα＝a'2(1)
X2+Z2-2XZcosβ＝b'2(2)
Y2+X2-2YXcosγ＝c'2(3)
the above three equations (1) (2) (3) are converted into the following equations according to the defined parameter relationships:
(1-a)y2-ax2+axyr-yp+1＝0 (4)
(1-b)x2-by2+bxyr-xq+1＝0 (5)
solving x, y and v by a Wu zero decomposition method according to equations (4) and (5); bound parameter relationship bc'2＝bvZ2Determining X, Y and Z, wherein X is xZ, and Y is yZ;
after the distance X, Y, Z from the point A, B, C to the focusing center of the monocular camera is calculated, the coordinates of the points A, B and C in the camera coordinate system are respectively calculated according to the triangle similarity principle, and the pose of the monocular camera is obtained by combining the coordinates of the mark points/encoding sheets measured in advance.
In a possible embodiment, the surface of the measuring light pen is provided with a plurality of probe connectors for fixedly mounting the probes. In this embodiment, the plurality of probe tips may have different specifications for the purpose of facilitating replacement of probes of different lengths, diameters, and orientations.
In one possible embodiment, the probe comprises a probe metal rod and a probe head arranged at one end of the probe metal rod, wherein the probe head is made of ruby.
The precision of scanning and measuring the workpiece to be measured by the probe made of the ruby is higher.
In summary, the embodiments of the present invention provide a portable detection method and system based on intelligent reverse positioning, which perform positioning and attitude determination on a monocular camera and a probe by using the monocular camera to identify a code sheet and a mark point of a stable reference body, thereby implementing intelligent reverse positioning. And obtaining the three-dimensional coordinate of the measured point on the workpiece to be measured according to the pose of the probe, thereby realizing the portable and contact detection of the three-dimensional coordinate by the single camera. The target is arranged on the stable reference body, is not limited on the measuring light pen, and is large in number, so that the measuring accuracy is improved. The measuring range of the measuring light pen is expanded, the range of the stable reference body surface target is large, and the measuring range is large, so that the measuring range of the measuring light pen is not limited any more.
The embodiments of the present invention can be arbitrarily combined to achieve different technical effects.
Through the above description of the embodiments, those skilled in the art will clearly understand that each embodiment can be implemented by software plus a necessary general hardware platform, and of course, can also be implemented by hardware. With this understanding in mind, the above technical solutions may be embodied in the form of a software product, which can be stored in a computer readable storage medium, such as ROM/RAM, magnetic disk, optical disk, etc., and includes instructions for causing a computer device (which may be a personal computer, a server, or a network device) to execute the method according to the embodiments or some parts of the embodiments.
Finally, it should be noted that: the above examples are only intended to illustrate the technical solution of the present invention, but not to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; and such modifications or substitutions do not depart from the spirit and scope of the corresponding technical solutions of the embodiments of the present invention.
Claims (10)
1. A portable detection method based on intelligent reverse positioning is characterized by comprising the following steps:
s1, presetting a stable reference body as an auxiliary measuring scene matched with the measuring light pen, and fixing a plurality of mark points and coding pieces on the surface of the stable reference body as targets; acquiring the coordinates of the mark points and the coordinates of the coding chips on the surface of the stable reference body through the photogrammetric function of the monocular camera;
s2, calibrating the position relation between the probe of the measuring light pen and the monocular camera to obtain the relative pose between the probe and the camera; wherein the probe is rigidly connected with the monocular camera;
s3, calculating the pose of the monocular camera according to at least 3 mark points/encoding sheet coordinates in the visual field range of the monocular camera;
s4, acquiring the pose of the probe according to the pose of the monocular camera and the relative pose between the probe and the camera;
and S5, obtaining the three-dimensional coordinates of the measured point on the workpiece to be measured according to the pose of the probe.
2. The portable detection method based on intelligent reverse orientation as claimed in claim 1, wherein the step S1, acquiring the coordinates of the surface landmark points of the stable reference body and the coordinates of the code slice by the photogrammetric function of the monocular camera, comprises:
shooting images of the stable reference body surface mark points and the coding sheet by using a monocular camera;
and extracting the coordinates of the mark points and the coordinates of the coding pieces according to the images of the mark points and the coding pieces.
3. The portable detection method based on intelligent reverse orientation as claimed in claim 1, wherein in step S2, the calibrating the position relationship between the probe of the measurement light pen and the monocular camera to obtain the relative pose between the probe and the camera includes:
the calibration cone is stably placed in the stable reference body, the probe head of the measuring light pen is stably placed in the calibration cone to swing to different postures, the rotation and translation matrixes of the probe head under different postures are obtained through the monocular camera, and then the relative pose between the probe and the monocular camera is calculated.
4. The portable detection method based on intelligent reverse positioning as claimed in claim 1, further comprising, before step S3:
and numbering the coded slice coordinates of the stable reference body according to a preset rule.
5. The portable detection method based on intelligent backward positioning as claimed in claim 1, wherein in step S3, the calculating the pose of the monocular camera according to the coordinates of at least 3 landmark points/code slices in the field of view of the monocular camera specifically comprises:
the coordinates of the three index points/code patches A, B, C are known, the focus center of the monocular camera is located at point P, and a ' ═ BC |, b ' ═ AC |, c ' ═ AB |; let X ═ PA |, Y ═ PB |, Z ═ PC |; let X ═ xZ, Y ═ yZ; it is known that α ═ PB, PC >, β ═ PA, PB >, γ ═ PA, PC >;
a'2＝ac'2、b'2＝bc'2、c'2＝vZ2Where p ═ 2cos α, q ═ 2cos β, and r ═ 2cos γ, then there are a'2＝ac'2＝avZ2，b'2＝bc'2＝bvZ2；
The constraint equation is derived from the P, A, B, C non-coplanarity: p is a radical of2+q2+r2-pqr-1≠0；
According to the cosine theorem of the triangle, the following formula can be obtained in three triangles formed by P, A, B, C four points:
Y2+Z2-2YZcosα＝a'2 (1)
X2+Z2-2XZcosβ＝b'2 (2)
Y2+X2-2YXcosγ＝c'2 (3)
the above three equations (1) (2) (3) are converted into the following equations according to the defined parameter relationships:
(1-a)y2-ax2+axyr-yp+1＝0 (4)
(1-b)x2-by2+bxyr-xq+1＝0 (5)
solving x, y and v by a Wu zero decomposition method according to equations (4) and (5); bound parameter relationship bc'2＝bvZ2Determining X, Y and Z, wherein X is xZ, and Y is yZ;
after the distance X, Y, Z from the point A, B, C to the focusing center of the monocular camera is calculated, the coordinates of the points A, B and C in the camera coordinate system are respectively calculated according to the triangle similarity principle, and the pose of the monocular camera is obtained by combining the coordinates of the mark point/coding piece which are measured in advance.
6. The portable intelligent reverse positioning-based detection method according to claim 1, wherein the stable reference body comprises but is not limited to an indoor wall, a steel structure scaffold or an indoor support column.
7. A portable detection system based on intelligent reverse positioning is characterized by comprising a measuring light pen, a stable reference body and a computing device, wherein a plurality of mark points and a coding sheet are fixed on the surface of the stable reference body to serve as targets;
the measuring light pen at least comprises a monocular camera and a probe which are rigidly connected, the monocular camera faces towards the stable reference body, the probe faces towards the workpiece to be measured, and the monocular camera is in communication connection with the computing device;
the monocular camera is used for collecting images of the stable reference body surface mark points and the coding sheet and transmitting the images to the computing device;
a calibration cone is fixedly arranged in the stable reference body and used for calibrating the position relation between a probe of the measuring light pen and the monocular camera to obtain the relative pose between the probe and the camera;
the computing device includes:
the extraction unit is used for receiving the images of the mark points and the coding pieces on the surface of the stable reference body and extracting the coordinates of the mark points and the coordinates of the coding pieces from the images;
the camera pose calculation unit is used for calculating the pose of the monocular camera according to at least 3 mark points/coding piece coordinates in the visual field range of the monocular camera;
the probe pose obtaining unit is used for obtaining the pose of the probe according to the pose of the monocular camera and the relative pose between the probe and the camera;
and the measured point coordinate obtaining unit is used for obtaining the three-dimensional coordinate of the measured point on the workpiece to be measured according to the pose of the probe.
8. The portable detection system based on intelligent backward positioning of claim 7, wherein the camera pose calculation unit is specifically configured to:
the coordinates of the three index points/code patches A, B, C are known, the focus center of the monocular camera is located at point P, and a ' ═ BC |, b ' ═ AC |, c ' ═ AB |; let X ═ PA |, Y ═ PB |, Z ═ PC |; let X ═ xZ, Y ═ yZ; it is known that α ═ PB, PC >, β ═ PA, PB >, γ ═ PA, PC >;
a'2＝ac'2、b'2＝bc'2、c'2＝vZ2Where p ═ 2cos α, q ═ 2cos β, and r ═ 2cos γ, then there are a'2＝ac'2＝avZ2，b'2＝bc'2＝bvZ2；
The constraint equation is derived from the P, A, B, C non-coplanarity: p is a radical of2+q2+r2-pqr-1≠0；
According to the cosine theorem of the triangle, the following formula can be obtained in three triangles formed by P, A, B, C four points:
Y2+Z2-2YZcosα＝a'2 (1)
X2+Z2-2XZcosβ＝b'2 (2)
Y2+X2-2YXcosγ＝c'2 (3)
the above three equations (1) (2) (3) are converted into the following equations according to the defined parameter relationships:
(1-a)y2-ax2+axyr-yp+1＝0 (4)
(1-b)x2-by2+bxyr-xq+1＝0 (5)
solving x, y and v by a Wu zero decomposition method according to equations (4) and (5); bound parameter relationship bc'2＝bvZ2Determining X, Y and Z, wherein X is xZ, and Y is yZ;
after the distance X, Y, Z from the point A, B, C to the focusing center of the monocular camera is calculated, the coordinates of the points A, B and C in the camera coordinate system are respectively calculated according to the triangle similarity principle, and the pose of the monocular camera is obtained by combining the coordinates of the mark point/coding piece which are measured in advance.
9. The portable detection system based on intelligent reverse orientation as claimed in claim 7, wherein the measuring light pen surface is provided with a plurality of probe connectors for fixedly mounting the probe.
10. The portable intelligent reverse-orientation-based detection system of claim 7, wherein the probe comprises a probe metal rod and a probe head disposed at one end of the probe metal rod, the probe head being made of ruby.
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