CN108613628B - Overhead transmission line sag measurement method based on binocular vision - Google Patents
Overhead transmission line sag measurement method based on binocular vision Download PDFInfo
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- CN108613628B CN108613628B CN201810466357.7A CN201810466357A CN108613628B CN 108613628 B CN108613628 B CN 108613628B CN 201810466357 A CN201810466357 A CN 201810466357A CN 108613628 B CN108613628 B CN 108613628B
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
- G01B11/00—Measuring arrangements characterised by the use of optical techniques
- G01B11/02—Measuring arrangements characterised by the use of optical techniques for measuring length, width or thickness
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
- G01B11/00—Measuring arrangements characterised by the use of optical techniques
- G01B11/002—Measuring arrangements characterised by the use of optical techniques for measuring two or more coordinates
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Abstract
The invention provides a binocular vision-based sag measurement method for an overhead transmission line, which comprises the steps of (1) building a binocular vision system and building a three-dimensional space coordinate system; (2) calibrating the binocular vision system to obtain internal and external parameters of the binocular vision system; (3) acquiring and correcting an on-site power transmission line image; (4) conducting wire selection and central line extraction; (5) matching characteristic points of the left and right view lead wires; (6) projecting the characteristic points of the wire on a sag measurement plane; (7) and (4) calculating sag. The method can quickly obtain the sag value by only taking one picture by each of two cameras of the field binocular vision system, has small field workload, has no requirement on a shooting place, and has strong applicability.
Description
Technical Field
The invention relates to the technical field of power transmission line measurement, in particular to a method for rapidly acquiring sag size of a power transmission line through a binocular vision system.
Background
The sag of the power transmission line is an important index for designing and operating and maintaining the line, and whether the sag is controlled within a specified design tolerance or not directly influences the safe and stable operation of the line. Design departments, construction units and operation and maintenance units all aim at the aspects of economy and safety to ensure that the sag of the overhead power line is controlled within a reasonable range. The change of the circuit operation load and the surrounding environment can cause the change of the circuit sag, for example, under the working conditions of high temperature and heavy load, ice coating of a power transmission line and the like, the sag can be increased, and the hidden trouble that the sag exceeds the limit, and the cross spanning safety distance is insufficient is caused. Therefore, the sag measurement of important power transmission lines is necessary. The traditional sag measurement methods mainly comprise a gear side angle method, a gear end angle method, a sag plate observation method and the like, and the methods need a large amount of physical quantity to be observed and have a complicated calculation process.
With the manufacturing cost of reliable large-area electronic photosensitive devices becoming lower and lower, images become a data source with low cost, rich information and high reliability. However, the traditional sag measurement method based on images causes image distortion of the power transmission line due to lack of depth information and shooting angles, has large measurement errors and is limited in application occasions.
Disclosure of Invention
The invention aims to provide a binocular vision-based overhead transmission line sag measurement method, which is characterized in that a binocular vision system is used for carrying out image acquisition on a transmission line, coordinate information of a space point of the transmission line is obtained through three-dimensional reconstruction, and then the coordinate information is projected to a sag calculation plane to calculate a sag value of the transmission line.
In order to achieve the above object, the present invention comprises the steps of:
(1) building a binocular vision system and establishing a three-dimensional space coordinate system;
(2) calibrating the binocular vision system to obtain internal and external parameters of the binocular vision system;
(3) acquiring and correcting an on-site power transmission line image;
(4) conducting wire selection and central line extraction;
(5) matching characteristic points of the left and right view lead wires;
(6) projecting the characteristic points of the wire on a sag measurement plane;
(7) and (4) calculating sag.
Further, the step (1) of building a binocular vision system and the step of building a three-dimensional space coordinate system are as follows: the double camera terminals are fixed on the horizontal base line seat, the relative positions of the two camera terminals are kept unchanged, the rotation angles are unchanged, and the two camera terminals have certain upward elevation angles, so that the overhead transmission line can be conveniently shot, and a space three-dimensional coordinate system is established by taking the left camera terminal as an original point.
Further, the binocular vision system calibration step in the step (2) is that internal parameters α, β, gamma, mu and upsilon of the binocular vision system are calibrated by using a Zhang method, wherein α is a scale factor on an x axis, β is a scale factor on a y axis, gamma is an oblique factor of an image coordinate and an optical axis coordinate, mu is a position of an optical axis optical center on the x axis of the image coordinate, and upsilon is a position of the optical axis optical center on the y axis of the image coordinate, and external parameters R, t of the binocular vision system are calibrated by using a self-calibration method, wherein R is a rotation factor, and t is a translation factor.
Further, the image acquisition and correction in the step (3) specifically comprises the following steps: firstly, ensuring that a left camera terminal and a right camera terminal can simultaneously acquire more than half of the full length of a first transmission line and comprise the lowest points; secondly, shooting images of the power transmission line respectively at the same time; and then, carrying out distortion correction and epipolar line correction on the images by using the calibration parameters so that the matching points of the two images are positioned on the same horizontal plane.
Further, the specific steps of wire selection and centerline extraction in the step (4) are as follows: firstly, edge detection is carried out on a left view and a right view by utilizing a Sobel operator; secondly, carrying out binarization and filtering processing; then, filtering a complex road surface background by selecting an interest area; and thinning and deburring to obtain the central line of the wire, and selecting the wire needing to measure the sag if a plurality of central lines exist in the graph.
Further, the matching of the characteristic points of the left and right view lead in the step (5) is specifically as follows: and scanning the wires in the left view and the right view in a certain step length in the vertical direction, determining corresponding characteristic points, and calculating the three-dimensional coordinate values of all the characteristic points according to the coordinate values of the characteristic points on different views and by combining calibration parameters.
Further, the projection of the characteristic point of the wire on the sag measurement plane in the step (6) specifically comprises the following steps: and determining a rotation factor according to the three-dimensional coordinate value of the characteristic point, and rotating the characteristic point to the sag measurement plane.
Further, the wire sag calculation in the step (7) specifically comprises the following steps: using catenary equations under new coordinate systems
And (4) bringing in different characteristic point coordinates, fitting to obtain values of parameters a, b and c in the equation, wherein the a, b and c are fitting coefficients, and calculating coordinates of a starting point and an end point of the wire in the gear by combining the wire span and the height difference value to calculate the sag value.
The invention has the advantages that:
1. the method combines the Zhang calibration method and the self-calibration method to calibrate the internal parameters and the external parameters of the binocular vision system in advance, and solves the problems of inconvenience, low precision and difficult field calibration by using the traditional calibration method after erection.
2. The sag calculation projection plane is determined by obtaining the spatial position information of the characteristic points of the wire, and the wire is projected onto a two-dimensional plane, so that sag calculation is realized in the two-dimensional plane. The existing commonly used angle method needs to measure a sag angle, a hanging point angle and a field temperature, and also needs to obtain information such as wire specific load and the like to calculate a sag value.
Drawings
FIG. 1 is a schematic structural view of a binocular measurement system of the present invention;
FIG. 2 is a schematic view of a sag calculation projection plane according to the present invention;
fig. 3 is a schematic flow chart of the overhead transmission line sag measurement method based on binocular vision.
In the figure: 1-left shooting terminal, 2-right shooting terminal, 3-horizontal base line seat, 4-support.
Detailed Description
The technical solution of the present invention will be clearly and completely described below with reference to the accompanying drawings.
As shown in fig. 3, a binocular vision-based overhead transmission line sag measurement method includes the following steps:
step P101: and (4) building a binocular vision system and building a three-dimensional space coordinate system. Specifically, as shown in fig. 1, the two camera terminals (the left camera terminal 1 and the left camera terminal 1) are fixed on the horizontal base 3, the horizontal base 3 is fixed on the bracket 4, the relative positions of the two camera terminals are kept unchanged, the rotation angles are unchanged, and both the camera terminals have certain upward elevation angles, so that the overhead transmission line can be conveniently shot. And establishing a spatial three-dimensional coordinate system by taking the left camera terminal as an origin.
The method comprises the following steps of P102, calibrating a binocular vision system to obtain internal and external parameters of the binocular vision system, specifically, calibrating internal parameters α, β, gamma, mu and upsilon of the binocular vision system by using a Zhang method, wherein α is a scale factor on an x axis, β is a scale factor on a y axis, gamma is an oblique factor of an image coordinate and an optical axis coordinate, mu is a position of an optical axis optical center on the x axis of the image coordinate, and upsilon is a position of the optical axis optical center on the y axis of the image coordinate, calibrating external parameters R, t of the binocular vision system by using a self-calibration method, wherein R is a rotation factor, and t is a translation factor.
Step P103: and collecting and correcting the on-site power transmission line image. Specifically, a binocular vision system is erected on site, and the level is adjusted. Ensuring that the left and right camera terminals can simultaneously acquire more than half of the full length of a first transmission line and comprise the lowest points; then, shooting images of the power transmission line respectively; and carrying out distortion correction and epipolar line correction on the images by using the calibration parameters so that the matching points of the two images are positioned on the same horizontal plane.
Step P104: wire selection and centerline extraction. Specifically, the left view and the right view are processed in the following ways: (1) performing edge detection by using a Sobel operator; (2) carrying out binarization and filtering processing; (3) filtering backgrounds such as complex road surfaces and the like by selecting interest areas; (4) in order to avoid the problem that the same wire is not consistent in thickness on a picture due to different distances, the center line of the wire is obtained after thinning and deburring.
If a plurality of wires exist in the figure, the wires (represented by central lines) needing to measure the sag are selected from the left and right view pictures for matching.
Step P105: and matching characteristic points of the left and right view lead lines. Through steps P103 and P104, the coordinates in the vertical direction of the sag wire to be measured in the left and right views are uniform, i.e., the matching points in the left and right views have the same y-coordinate value. The specific steps of matching characteristic points of the left and right view lead are as follows: and scanning the conducting wires in the left and right views in a certain step length in the vertical direction to determine corresponding characteristic points. According to the coordinate values of the characteristic points on different views, the three-dimensional coordinate values of all the characteristic points can be calculated by combining the calibration parameters.
Step P106: the characteristic points of the wire are projected on the sag measurement plane. Specifically, a rotation factor is determined according to the three-dimensional coordinate value of the feature point in step P105, and the feature point is rotated to the sag measurement plane, as shown in fig. 2. And establishing a new coordinate system, and converting all the characteristic point coordinates into two-dimensional coordinates under the new coordinate system.
Step P107: and (4) calculating sag. Specifically, under the coordinate system determined in step P106, the catenary equation is followed
And (4) bringing in different characteristic point coordinates, and fitting to obtain values of parameters a, b and c in the equation, wherein a, b and c are fitting coefficients.
Step P108: and D, according to the catenary equation determined in the step P107 and the span and height difference of the wire (the span and height difference are obtained by searching the line design operation and maintenance data), searching the line design operation and maintenance data to obtain the span and height difference, and calculating the sag value.
The above description is only an embodiment of the present invention, but the scope of the present invention is not limited thereto, and any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope of the present invention are included in the scope of the present invention.
Claims (2)
1. A binocular vision-based overhead transmission line sag measurement method is characterized by comprising the following steps:
(1) building a binocular vision system and establishing a three-dimensional space coordinate system;
(2) calibrating the binocular vision system to obtain internal and external parameters of the binocular vision system;
(3) acquiring and correcting an on-site power transmission line image;
(4) conducting wire selection and central line extraction;
(5) matching characteristic points of the left and right view lead wires;
(6) projecting the characteristic points of the wire on a sag measurement plane;
(7) calculating sag;
the binocular vision system is set up in the step (1), and the step of setting up the three-dimensional space coordinate system is as follows:
fixing the double camera terminals on a horizontal base line seat, keeping the relative positions of the two camera terminals unchanged, keeping the rotation angles unchanged, and keeping a certain upward elevation angle, so that the overhead transmission line can be conveniently shot, and establishing a space three-dimensional coordinate system by taking the left camera terminal as an original point;
calibrating internal parameters α, β, gamma, mu and upsilon of the binocular vision system by using a Zhang method, wherein α is a scale factor on an x axis, β is a scale factor on a y axis, gamma is an oblique factor of an image coordinate and an optical axis coordinate, mu is a position of an optical axis optical center on the x axis of the image coordinate, and upsilon is a position of the optical axis optical center on the y axis of the image coordinate;
the image acquisition and correction in the step (3) comprises the following specific steps: firstly, ensuring that a left camera terminal and a right camera terminal can simultaneously acquire more than half of the full length of a first transmission line and comprise the lowest points; secondly, shooting images of the power transmission line respectively at the same time; then, carrying out distortion correction and epipolar line correction on the images by using the calibration parameters to enable the matching points of the two images to be positioned on the same horizontal plane;
the specific steps of wire selection and center line extraction in the step (4) are as follows: firstly, edge detection is carried out on a left view and a right view by utilizing a Sobel operator; secondly, carrying out binarization and filtering processing; then, filtering a complex road surface background by selecting an interest area; then refining,
Deburring to obtain the center line of the wire, and if a plurality of center lines exist in the drawing, selecting the wire needing to be measured for sag;
the matching of the characteristic points of the left and right view lead in the step (5) is specifically as follows: scanning the wires in the left view and the right view in a certain step length in the vertical direction, determining corresponding characteristic points, and calculating three-dimensional coordinate values of all the characteristic points according to coordinate values of the characteristic points on different views and by combining calibration parameters;
the projection of the characteristic points of the wire in the sag measurement plane in the step (6) specifically comprises the following steps:
and determining a rotation factor according to the three-dimensional coordinate value of the characteristic point, and rotating the characteristic point to the sag measurement plane.
2. The binocular vision-based overhead transmission line sag measurement method according to claim 1, wherein: the calculation of the conductor sag in the step (7) comprises the following specific steps: using catenary equations under new coordinate systems
And (4) bringing in different characteristic point coordinates, fitting to obtain values of parameters a, b and c in the equation, wherein the a, b and c are fitting coefficients, and calculating coordinates of a starting point and an end point of the wire in the gear by combining the wire span and the height difference value to calculate the sag value.
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| CN108613628B (en) * | 2018-05-16 | 2020-05-15 | 国网湖北省电力有限公司电力科学研究院 | Overhead transmission line sag measurement method based on binocular vision |
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| CN112882644B (en) * | 2021-02-24 | 2022-07-29 | 中国电建集团河南工程有限公司 | Method for automatically extracting hectometer sag value of power transmission line |
| CN115731303B (en) * | 2022-11-23 | 2023-10-27 | 江苏濠汉信息技术有限公司 | Large-span transmission conductor sag three-dimensional reconstruction method based on bidirectional binocular vision |
| CN115600048B (en) * | 2022-12-12 | 2023-03-24 | 安徽送变电工程有限公司 | Sag observation method, device and system with adjacent wire spacing compensation function |
| CN116718122B (en) * | 2023-08-09 | 2023-10-20 | 南方电网数字电网研究院有限公司 | Sag measurement method and device based on image parallax depth and computer equipment |
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