CN113960069B - Method for establishing cable surface morphology through laser line scanning - Google Patents
Method for establishing cable surface morphology through laser line scanning Download PDFInfo
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- CN113960069B CN113960069B CN202111231309.8A CN202111231309A CN113960069B CN 113960069 B CN113960069 B CN 113960069B CN 202111231309 A CN202111231309 A CN 202111231309A CN 113960069 B CN113960069 B CN 113960069B
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- 238000012876 topography Methods 0.000 claims description 2
- 238000013528 artificial neural network Methods 0.000 description 6
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
- G01N21/84—Systems specially adapted for particular applications
- G01N21/88—Investigating the presence of flaws or contamination
- G01N21/95—Investigating the presence of flaws or contamination characterised by the material or shape of the object to be examined
- G01N21/952—Inspecting the exterior surface of cylindrical bodies or wires
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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
- G01B11/24—Measuring arrangements characterised by the use of optical techniques for measuring contours or curvatures
- G01B11/2433—Measuring arrangements characterised by the use of optical techniques for measuring contours or curvatures for measuring outlines by shadow casting
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
- G01N21/01—Arrangements or apparatus for facilitating the optical investigation
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Abstract
The invention discloses a method for establishing cable surface morphology through laser line scanning, which comprises the following steps: s1, constructing a scanning robot; s2, emitting a laser line to a target cable through a laser line emitter, and obtaining projection of the laser line on the surface of the target cable through a camera; s3, obtaining entity coordinates of a target cable where the projection map is located through the positions of the cameras; s4, splicing projection graphs based on four groups of section coordinates to obtain an outer surface projection model of the target cable; s5, acquiring coordinates and sizes of poles and abrupt points in the projection model of the outer surface of the target cable, and finishing cable surface detection. The method can rapidly and accurately detect the surface damage of the cable, and has low cost and high efficiency.
Description
Technical Field
The invention relates to the field of cable detection, in particular to a method for establishing cable surface morphology through laser line scanning.
Background
The existing detection methods for apparent damage of the cable are roughly divided into an artificial detection method, a laser scanning method, a machine learning neural network detection method and a machine vision defect detection method, wherein the artificial detection method is used for detecting the surface of the cable through human eyes, so that the time and the labor are consumed, potential safety hazards are caused, the cable damage is subjectivity, the cable damage is easy to miss or misdetect, and the efficiency is low.
The laser scanning method is an automatic detection method for cable surface defects, the acquisition principle is that reflected laser is received by emitting laser beams, the time and the distance in the laser are measured, the detection defects are not intuitive, the processing and analysis time for a three-dimensional space is long, the system has large constitution volume, and the equipment is expensive and is difficult to popularize and apply.
The machine learning neural network detection method mainly comprises a BP neural network, an SCG neural network and an RBF neural network, wherein a finite element analysis model is established mainly through numerical simulation, and the position where damage occurs is estimated by inputting specific parameters and load working conditions of a cable and applying a neural network algorithm; under the condition of damage of different degrees, the identification precision is different, and the stability is weaker; when processing data, the number of iterations of calculation is large, the workload is large, and the existing algorithm is not very mature.
The method has the limitations of low efficiency, high cost, insufficient intelligent degree and the like.
Disclosure of Invention
Aiming at the defects in the prior art, the method for establishing the cable surface morphology through laser line scanning solves the problem of low efficiency of the existing detection method.
In order to achieve the aim of the invention, the invention adopts the following technical scheme:
there is provided a method of establishing a cable topography by laser line scanning, comprising the steps of:
s1, constructing a scanning robot: four sides of the inner side of the cable climbing vehicle are respectively provided with a laser line emitter, so that all the laser line emitters are on the same plane and are vertical to a target cable; the four sides of the inner side of the cable climbing vehicle are respectively provided with a camera, so that all the cameras are on the same plane and are parallel to the plane of the laser transmitter; the included angles between the sight lines of all cameras and the target cable are equal;
s2, emitting laser lines to the target cable through a laser line emitter, and obtaining projection of the laser lines on the surface of the target cable through a camera to obtain four groups of projection graphs;
s3, obtaining entity coordinates of a target cable where the projection map is located through the positions of the cameras, and obtaining four groups of section coordinates;
s4, splicing projection graphs based on four groups of section coordinates to obtain an outer surface projection model of the target cable;
s5, acquiring coordinates and sizes of poles and abrupt points in the projection model of the outer surface of the target cable, and finishing cable surface detection.
Further, in step S1, the distance between two adjacent laser line emitters is equal, and the area of the laser line projected on the target cable by each laser line emitter is one quarter of the length of the cross-section ring of the target cable.
Further, the specific method of step S3 is as follows:
constructing a space coordinate system by taking the central axis direction of the scanning robot as a z axis and the laser line emitter direction as an x axis, and acquiring the z axis coordinate z of a target cable where a projection map is positioned according to the position of a camera * The method comprises the steps of carrying out a first treatment on the surface of the According to the formula:
obtaining the physical coordinates (x) of the target cable where any target point of the projection map is located * ,y * ) Thereby obtaining the physical coordinates (x) of the target cable where any target point of the projection map is located * ,y * ,z * ) The method comprises the steps of carrying out a first treatment on the surface of the Where cot represents the cotangent function; alpha is the included angle between the connecting line of the target point and the optical center of the camera and the central axis of the visual field of the camera; csc represents a post-cut function; θ represents the angle between the central axis of the video camera and the laser plane; (u, v) is the coordinates of the target point in the image coordinate system; l is the distance from the optical center of the camera to the laser plane; cos is a cosine function; f is the focal length of the camera when aimed at the target point.
The beneficial effects of the invention are as follows: the method comprises the steps of launching a laser line to a cable, collecting projection of the laser line on the appearance of the cable, converting the coordinates of a negative film of a computing camera system, obtaining the coordinates of the apparent entity of the cable, further establishing a three-dimensional model or a point cloud model, if the appearance of the cable is not damaged, the projection of the laser line on the cable should be a smooth continuous curve, if the cable is defective, a unfilled corner exists at a certain point of the cable, the projection of the laser line has a pole or a mutant point, the damaged position of the surface of the cable can be known through the coordinates of the pole and the mutant point in the three-dimensional model or the point cloud model, and the size of the damaged area can be calculated through the coordinates of the damaged position, so that the cable can be rapidly detected.
Drawings
FIG. 1 is a schematic flow chart of the method;
FIG. 2 is a schematic diagram of the relative positions of a scanning robot and a cable;
FIG. 3 is a schematic diagram of coordinate system conversion;
FIG. 4 is a schematic illustration of a projection of a unbroken cable;
FIG. 5 is a schematic illustration of a projection of a cable with breakage;
Detailed Description
The following description of the embodiments of the present invention is provided to facilitate understanding of the present invention by those skilled in the art, but it should be understood that the present invention is not limited to the scope of the embodiments, and all the inventions which make use of the inventive concept are protected by the spirit and scope of the present invention as defined and defined in the appended claims to those skilled in the art.
As shown in fig. 1 and 2, the method for establishing the cable surface morphology by laser line scanning comprises the following steps:
s1, constructing a scanning robot: the four sides of the inner side of the cable climbing vehicle are respectively provided with a laser line emitter, so that all the laser line emitters are on the same plane and are vertical to a target cable (cable, namely a guy cable); the four sides of the inner side of the cable climbing vehicle are respectively provided with a camera, so that all the cameras are on the same plane and are parallel to the plane of the laser transmitter; the included angles between the sight lines of all cameras and the target cable are equal;
s2, emitting laser lines to the target cable through a laser line emitter, and obtaining projection of the laser lines on the surface of the target cable through a camera to obtain four groups of projection graphs;
s3, obtaining entity coordinates of a target cable where the projection map is located through the positions of the cameras, and obtaining four groups of section coordinates;
s4, splicing projection graphs based on four groups of section coordinates to obtain an outer surface projection model of the target cable;
s5, acquiring coordinates and sizes of poles and abrupt points in the projection model of the outer surface of the target cable, and finishing cable surface detection.
In the step S1, the intervals between two adjacent laser line transmitters are equal, and the area of the laser line projected on the target cable by each laser line transmitter is one quarter of the length of the cross section ring of the target cable.
The specific method of the step S3 is as follows: as shown in FIG. 3, a space coordinate system is constructed by taking the central axis direction of the scanning robot as the z axis and the laser line emitter direction as the x axis, and the z-axis coordinate z of a target cable where a projection map is located is obtained according to the position of a camera * The method comprises the steps of carrying out a first treatment on the surface of the According to the formula:
obtaining the physical coordinates (x) of the target cable where any target point of the projection map is located * ,y * ) Thereby obtaining the physical coordinates (x) of the target cable where any target point of the projection map is located * ,y * ,z * ) The method comprises the steps of carrying out a first treatment on the surface of the Where cot represents the cotangent function; alpha is the included angle between the connecting line of the target point and the optical center of the camera and the central axis of the visual field of the camera; csc represents a post-cut function; θ represents the angle between the central axis of the video camera and the laser plane; (u, v) is the coordinates of the target point in the image coordinate system; l is the distance from the optical center of the camera to the laser plane; cos is a cosine function; f is the focal length of the camera when aimed at the target point.
In one embodiment of the invention, the laser line emitter and the camera form a camera system, the camera system replaces the actual defect condition of the periphery of the section of the cable by using the projection of the laser line on the appearance of the cable, so that each layer of section of the cable is one layer of laser line on the camera system, and the scanning result is a cable outside graph formed by a plurality of laser curve sections continuously; and (3) carrying out coordinate processing on imaging after finishing scanning by using a mathematical method, and constructing each section acquired by the camera system into an actual appearance model of the cable through coordinate conversion. The path of the moving scanning of the camera system is the axis of the cable, namely a smooth curve. The section scanned by the camera system is required to be connected in series according to the line shape (axis, which can be directly extracted by photographing) of the cable, so that the central line of the cable or the centroid position of each section can be found.
In summary, the present invention emits the laser line to the cable, collects the projection of the laser line on the appearance of the cable, and then converts the coordinate of the film of the camera system to obtain the coordinate of the apparent entity of the cable, and then establishes a three-dimensional model or a point cloud model, as shown in fig. 4, if the appearance of the cable is not damaged, the projection of the laser line on the cable should be a smooth continuous curve, as shown in fig. 5, if the cable is defective, there will be a unfilled corner at a certain point of the cable, the projection of the laser line will have a pole or a mutation point, the damaged position of the cable surface can be known by the coordinates of the pole and the mutation point in the three-dimensional model or the point cloud model, and the size of the damaged area can also be calculated by the coordinates of the damaged position, so as to realize the rapid detection of the cable.
Claims (2)
1. A method of establishing a cable topography by laser line scanning, comprising the steps of:
s1, constructing a scanning robot: four sides of the inner side of the cable climbing vehicle are respectively provided with a laser line emitter, so that all the laser line emitters are on the same plane and are vertical to a target cable; the four sides of the inner side of the cable climbing vehicle are respectively provided with a camera, so that all the cameras are on the same plane and are parallel to the plane of the laser transmitter; the included angles between the sight lines of all cameras and the target cable are equal;
s2, emitting laser lines to the target cable through a laser line emitter, and obtaining projection of the laser lines on the surface of the target cable through a camera to obtain four groups of projection graphs;
s3, obtaining entity coordinates of a target cable where the projection map is located through the positions of the cameras, and obtaining four groups of section coordinates;
s4, splicing projection graphs based on four groups of section coordinates to obtain an outer surface projection model of the target cable;
s5, acquiring coordinates and sizes of poles and abrupt points in an outer surface projection model of the target cable, and finishing cable surface detection;
the specific method of the step S3 is as follows:
constructing a space coordinate system by taking the central axis direction of the scanning robot as a z axis and the laser line emitter direction as an x axis, and acquiring the z axis coordinate of a target cable where a projection map is positioned according to the position of a cameraThe method comprises the steps of carrying out a first treatment on the surface of the According to the formula:
obtaining entity coordinates of a target cable where any target point of a projection chart is locatedThereby obtaining the physical coordinates of the target cable where any target point of the projection map is located>The method comprises the steps of carrying out a first treatment on the surface of the Where cot represents the cotangent function; />The included angle between the connecting line of the target point and the optical center of the camera and the central axis of the visual field of the camera; />Representation ofA residual function; />Representing the included angle between the central axis of the video camera field and the laser plane; (/>，/>) Coordinates of the target point in an image coordinate system;Ldistance from the optical center of the camera to the laser plane; cos is a cosine function;ffor the focal length of the camera when aimed at the target point.
2. The method of claim 1, wherein the distance between two adjacent laser line emitters in step S1 is equal, and the area of the laser line projected on the target cable by each laser line emitter is one-fourth the length of the cross-section ring of the target cable.
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| CN114778560B (en) * | 2022-06-20 | 2022-09-27 | 国网江苏省电力有限公司常州供电分公司 | Overhead line detection method and system based on cable inspection robot |
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