阅读说明：本技术 一种实时刚性接触网定位点识别方法 (Real-time rigid contact net positioning point identification method ) 是由 占栋 高仕斌 于龙 张楠 于 2020-06-24 设计创作，主要内容包括：本发明属于本发明接触网智能检测技术领域,公开了一种实时刚性接触网定位点识别方法,包括图像预处理步骤、刚性接触线区域定位步骤和刚性定位点定位步骤,基于图像处理检测技术,实现对接触网定位点的非接触式检测,相比采用电子标签、雷达或GPS等定位点识别方案实施成本更低、检测效率更高、定位可靠性更好。(The invention belongs to the technical field of intelligent detection of a contact network, and discloses a real-time rigid contact network positioning point identification method which comprises an image preprocessing step, a rigid contact line area positioning step and a rigid positioning point positioning step.)

1. A real-time rigid contact net positioning point identification method is characterized by comprising the following steps:

an image preprocessing step, namely acquiring an original image and performing gray level enhancement processing on the original image;

a rigid contact line area positioning step, namely sequentially performing horizontal gradient calculation, line extraction and line clustering on the image subjected to gray level enhancement processing in the image preprocessing step to form a candidate area, and performing area screening processing on the candidate area to position a rigid contact line area in the image;

a rigid positioning point positioning step, which comprises the steps of extracting the image characteristics of the insulator sample and positioning and scanning; the method comprises the following steps that the characteristic extraction of the insulator sample image comprises the steps of carrying out small image screenshot on a plurality of existing images containing various insulators, and normalizing the small images after being intercepted to the same size to be used as the insulator sample image; traversing the insulator sample image by adopting a window with a preset size of N x N, and sequentially calculating positive and negative marking values of difference between each non-central pixel and a central pixel gray value in the window to be recorded as a first characteristic, wherein N is an odd number; traversing the insulator sample image by adopting the preset N-by-N window, sequentially calculating positive and negative marking values of differences between the gray value of each pixel in the window and a preset gray value, and counting statistics of the marking values in the horizontal and vertical directions to be recorded as a second characteristic; connecting the first characteristic and the second characteristic in series to obtain the image characteristic of the insulator sample; the positioning scanning comprises traversing the rigid contact line area by adopting a sliding window, recording an image feature formed by connecting a first feature and a second feature in series in the sliding window as a sliding window image feature, calculating the similarity between the sliding window image feature and the insulator sample image feature, judging the sliding window image meeting the similarity threshold as a rigid positioning point, and outputting the rigid positioning point area.

2. The method for identifying the positioning point of the rigid catenary in real time according to claim 1, wherein the method comprises the following steps: and positioning scanning in the rigid positioning point positioning step, before calculating the sliding window image characteristics of the image in the sliding window, carrying out mirror image boundary expansion on the image in the sliding window.

3. The method for identifying the positioning point of the rigid catenary in real time according to claim 1, wherein the method comprises the following steps: and positioning scanning in the rigid positioning point positioning step, before calculating the sliding window image characteristics of the image in the sliding window, performing interpolation processing on the image in the sliding window to make the size of the image in the sliding window consistent with that of the insulator sample image.

4. The method for identifying the positioning point of the rigid catenary in real time according to claim 1, wherein the method comprises the following steps: the image preprocessing step is to calculate each pixel point in an original image G (x, y) by taking a numerical gradient function gradient (x, y) as a gradient, and superpose the result with the original image G (x, y) to obtain an enhanced image G '(x, y), namely G' (x, y) is G (x, y) + gradient (x, y), if the values of adjacent pixels in the image change, namely the gradient exists, the gradient is added with the corresponding original pixel, and the gray value is increased; otherwise, if the gradient is 0, the original pixel is unchanged.

5. The method for identifying the positioning point of the rigid catenary in real time according to claim 1, wherein the method comprises the following steps: in the rigid contact line region positioning step, the horizontal gradient calculation is to set the image subjected to the enhancement processing in the image preprocessing step to be spread along the Y direction, and to perform gradient calculation in the x direction on the image subjected to the enhancement processing in the image preprocessing step, wherein the gradient of each pixel point (x, Y) in the x direction in the image is

G_x(x,y)＝H(x+1,y)-H(x-1,y)

H (x +1, y) and H (x-1, y) are gray values of pixel points on two sides of the pixel point.

6. The method for identifying the positioning points of the real-time rigid contact network as claimed in claim 1 or 3, wherein the method comprises the following steps: in the step of positioning the rigid contact line region, line extraction is to set a fixed gray threshold, sequentially traverse each pixel point in the image after the gradient calculation according to lines, and mark the gray value of a certain pixel point as 1 when the gray value of the certain pixel point is greater than the threshold; calculating the midpoint of a region for the region marked with 1 continuously in each line, wherein the midpoint is used as a line candidate point of the region; and then when outputting the line, connecting candidate points on two adjacent lines within a distance of 3 pixels in the x direction to be output as the same line, or else, outputting as different lines.

7. The method for identifying the positioning points of the real-time rigid contact network as claimed in claim 1 or 3, wherein the method comprises the following steps: in the step of positioning the rigid contact line region, line clustering firstly sequentially traverses each line obtained by extracting the lines, calculates the average value x _ mean of all pixel points in each line in the x direction, and sorts all the lines from small to large according to the x _ mean;

clustering the sorted lines, classifying the first line into a first class, traversing each line from the second line from left to right in sequence, calculating the distance between the line and the first line and the last line in all the previous classes in the x direction by using the average value x _ mean, classifying the line into the same class if the distance meets the threshold condition, and classifying the line into one class if the distance does not meet the threshold condition of the distance with all the previous classes; finally, each type is a contact line candidate area;

in the step of positioning the contact line region, region screening is to calculate the region widths of all candidate regions obtained after line clustering, calculate the difference between the x _ mean of the first line and the last line according to the average value x _ mean of all pixel points in the x direction obtained by the line clustering, namely the region width, and screen out the rigid contact line region according to whether the region width meets the rigid contact line width interval.

8. The method for identifying the positioning point of the rigid catenary in real time according to claim 1, wherein the method comprises the following steps: in the step of positioning the rigid positioning point, the calculation of the image characteristics of the insulator specifically comprises the following steps:

traversing all pixel points of the image in the window by taking the window as the center in the window of N x N (N is an odd number), subtracting the pixel point of the pixel point at the center of the window from the pixel point of the pixel point at the center of the window, marking the pixel as 1 if the result is positive, otherwise marking the pixel as 0, and thus obtaining a series of marking values of the window and marking the marking values as characteristics I;

in the window of N x N, setting the pixel points with the gray scale value larger than a set threshold value in the image as 1, otherwise, setting the pixel points as 0, then carrying out pixel statistics in the horizontal and vertical directions, and marking as a characteristic II;

and traversing the insulator sample image by adopting an N-by-N window, and connecting the characteristic I and the characteristic II in series to obtain the characteristic of the whole image.

9. A computer-readable storage medium, characterized in that the computer-readable storage medium stores a computer program, which when executed in a computer processor, implements the steps of the real-time rigid catenary location point identification method of any of the preceding claims 1-8.

10. A computer device comprising a memory, a processor and a computer program stored on the memory and executable on the processor, wherein the processor implements the steps of the real-time rigid catenary setpoint identification method according to any one of claims 1 to 8 when executing the computer program.

Technical Field

The invention belongs to the technical field of intelligent detection of overhead contact systems, and particularly relates to a real-time rigid overhead contact system positioning point identification method.

Background

In the design of an electrified railway, a contact network mainly comprises a contact suspension device, a positioning device, a supporting device, a support column, related infrastructure and the like, and is a special power transmission line erected in the air along a railway line. Its function is to provide electric energy to the electric locomotive through the contact between the wire and the pantograph. And two state parameters are mainly referred to for evaluating the current collection performance of the contact network: geometric parameters and kinetic parameters. The geometric parameters comprise the height of the wire, the pull-out value, the gradient of the positioning pipe, the line fork, the abrasion of the wire, the position of the strut and the like, and the geometric parameter evaluation of the contact network requires accurate positioning detection of the positioning point of the contact network.

The positioning point detection technology is applied to the contact network, is used as a basis for triggering an area-array camera to acquire and shoot images in a contact network defect detection system, and is also used as a basis for storing and managing one-rod one-file data. Whether the positioning point is detected accurately or not greatly influences the triggering accuracy of the area-array camera, and further influences the subsequent data analysis difficulty, increases the missing detection rate and the workload of data analysis and the accuracy of one-level-one-file data storage.

In the prior art, there are some overhead line system identification and maintenance technical solutions based on radar detection technology, for example, chinese utility model patent documents with publication number CN205097980U, publication time of 2016, 3, and 23 days, entitled "overhead line system detection and maintenance vehicle based on laser radar", the disclosed technical solution includes a detection vehicle body, a data acquisition unit, a lifting and rotating operation platform, and a server for data analysis and processing; the data acquisition unit is arranged on the detection vehicle body, and the lifting rotary operation platform is arranged behind the top of the detection vehicle body in a lifting and rotating manner; a display and control panel is arranged on the lifting rotary operation platform; the server is respectively connected with the data acquisition unit and the display and control panel, and the data acquired by the data acquisition unit is analyzed and processed by the server and then transmitted to the display and control panel. However, according to practical experience, the radar-based detection technology has the defects that the detection frequency is low, the detection technology is not suitable for a train with a high speed, and the defects are obvious under the requirement of the current rail transit speed increase.

Besides the detection technology based on radar, there are other technical solutions suitable for detecting the location point of the catenary, such as the detection technology based on an electronic tag and the detection technology based on GPS, but these new technologies also have some problems: although the detection technology based on the electronic tags has high detection precision, the investment cost is too large, and the detection technology can be realized only by adding corresponding electronic tags on all detected objects, which can be realized only by ultrahigh investment of material resources and manpower, particularly for the reconstruction of the existing line; the detection technology based on the GPS also has the problems of high construction and operation and maintenance cost, and the technology has poor signals under the conditions of tunnels and shielding and interference, is easy to miss positioning and has insufficient precision.

Disclosure of Invention

In order to overcome the problems and disadvantages of the prior art, the present invention is directed to a method for detecting a non-contact location point of a rigid contact line based on an image processing detection technique.

The invention discloses a real-time rigid contact net positioning point identification method, which comprises the following steps:

an image preprocessing step, namely inputting an acquired original image, and performing gray level enhancement processing on the original image to improve the quality, contrast and the like of the original image;

a rigid contact line area positioning step, namely sequentially performing horizontal gradient calculation, line extraction and line clustering on the image subjected to gray level enhancement processing in the image preprocessing step to form a candidate area, and performing area screening on the candidate area to position a rigid contact line area in the image;

a rigid positioning point positioning step, which comprises the steps of extracting the image characteristics of the insulator sample and positioning and scanning; firstly, the insulator sample image feature extraction comprises the steps of finding out images of various insulators from existing image data containing various insulators, carrying out screenshot on small images of insulator regions, normalizing the intercepted small images to the same size to be used as insulator sample images, wherein the small images are smaller than the size of the previous images; then, carrying out pixel identification and marking on the insulator sample image in a window with a set size to obtain the characteristics of each insulator sample image, specifically, traversing the insulator sample image by adopting a window with a preset size of N x N (N is an odd number), and sequentially calculating positive and negative marking values of difference between the gray values of each non-central pixel and the central pixel in the window to be marked as a first characteristic; traversing the insulator sample image by adopting the preset N-by-N window, sequentially calculating positive and negative marking values of differences between the gray value of each pixel in the window and a preset gray value, and counting statistics of the marking values in the horizontal and vertical directions to be recorded as a second characteristic; connecting the first characteristic and the second characteristic in series to obtain the image characteristic of the insulator sample; the positioning scanning comprises traversing the rigid contact line region obtained in the contact line region positioning step by adopting a sliding window, recording an image feature formed by connecting a first feature and a second feature in series in the sliding window as a sliding window image feature, calculating the similarity between the sliding window image feature and the insulator sample image feature, judging the sliding window image meeting the similarity threshold as a rigid positioning point, and outputting the rigid positioning point region.

Furthermore, before the positioning scanning in the rigid positioning point positioning step calculates the sliding window image characteristics of the image in the sliding window, mirror image boundary expansion is further performed on the image in the sliding window, so that the effect of avoiding missing positioning is achieved. In a specific embodiment, the positioning efficiency is considered, and only the left and right mirror image boundaries can be expanded.

Furthermore, before calculating the sliding window image characteristics of the image in the sliding window, the positioning scanning in the rigid positioning point positioning step further includes performing interpolation processing on the image in the sliding window to make the size of the image in the sliding window consistent with that of the insulator sample image.

Preferably, the image preprocessing step calculates a gradient value of each pixel point in the original image G (x, y) by using a numerical gradient function gradient (x, y) as a gradient, and superimposes the result on the original image G (x, y) to obtain an enhanced image G '(x, y), that is, G' (x, y) ═ G (x, y) + gradient (x, y), if adjacent pixel values in the image change, that is, there is a gradient, the gradient is added to the corresponding original pixel, and the gray value is increased; on the contrary, if the gradient is 0, the original pixels are unchanged, that is, the contrast of the new image after addition is obviously enhanced, especially the outlines and edges of objects in the image are obviously different from the background.

In the step of positioning the rigid contact line region, the gradient calculation is to obtain a gradient map of the image in one direction and remove interference with objects in other directions to reduce the processing time of a subsequent program, and the specific method of the gradient calculation is as follows: the image subjected to the enhancement processing in the image preprocessing step is arranged along the Y direction, the angle between the contact line area and the x axis is about 90 degrees when viewed from the image, the image subjected to the enhancement processing in the image preprocessing step is subjected to gradient calculation in the x direction, and gradient information in other directions in the image is filtered, wherein the gradient of each pixel point (x, Y) in the x direction is

G_x(x,y)＝H(x+1,y)-H(x-1,y)

H (x +1, y) and H (x-1, y) are gray values of pixel points on two sides of the pixel point.

In the step of positioning the rigid contact line region, line extraction is to set a fixed gray threshold, sequentially traverse each pixel point in the image after the gradient calculation according to lines, and mark the gray value of a certain pixel point as 1 when the gray value of the certain pixel point is greater than the threshold; calculating the midpoint of a region for the region marked with 1 continuously in each line, wherein the midpoint is used as a line candidate point of the region; and then when outputting the line, connecting candidate points on two adjacent lines within a distance of 3 pixels in the x direction to be output as the same line, or else, outputting as different lines.

In the step of positioning the rigid contact line region, line clustering firstly sequentially traverses each line obtained by extracting the lines, calculates an average value x _ mean of all pixel points in each line in the x direction, and sorts all the lines from small to large according to the x _ mean, namely sorts all the lines from left to right in the x direction;

clustering the lines after sequencing, classifying the first line into a first class, namely the first line after sequencing, traversing each line from left to right from the second line in turn, calculating the distance between the line and the first line and the last line in all the previous classes in the x direction by using the average value x _ mean, classifying the lines into the same class if the distance meets the threshold condition, and classifying the lines into one class if the distance does not meet the threshold condition of the distance with all the previous classes; finally, each class is a contact line candidate area.

In the rigid contact line area positioning step, area screening is to calculate the area widths of all candidate areas obtained after line clustering, the average value x _ mean of all pixel points of all lines in the candidate areas in the x direction is known, the difference between the x _ mean of the first line and the x _ mean of the last line (namely the difference of the abscissa of each line; the difference between the leftmost line and the rightmost line is the width) is calculated, the area width is determined, the final contact line area can be screened out according to the area width, and the rigid contact line area can be screened out according to whether the area width accords with a rigid contact line area width threshold interval or not.

In the step of positioning the rigid positioning point, the calculation of the image characteristics of the insulator specifically comprises the following steps:

traversing all pixel points of the image in the window by taking the window as the center in the n x n window, subtracting the pixel points of the window center from the pixel points of the window center, marking the pixel as 1 if the result is positive, otherwise marking the pixel as 0, and thus obtaining a series of marking values of the window and marking the marking values as characteristics I;

in the window of n x n, setting the pixel points with the gray scale value larger than a set threshold value in the image as 1, otherwise, setting the pixel points as 0, then carrying out pixel statistics in the horizontal and vertical directions, and recording the pixel statistics as a feature II;

and traversing the insulator sample image by adopting an n x n window, and connecting the characteristic I and the characteristic II in series to obtain the characteristics of the whole image.

Has the advantages that:

1. the real-time rigid contact net positioning point identification algorithm in the technical scheme of the invention is based on an image processing detection technology, realizes non-contact detection on the positioning point of the contact net, and has lower implementation cost, higher detection efficiency and better positioning reliability compared with the positioning point identification scheme adopting an electronic tag, a radar or a GPS and the like.

2. According to the technical scheme, the gray level enhancement pretreatment is carried out on the original image, so that the image quality is improved, and the image contrast is enhanced; meanwhile, a gradient map of the image in the horizontal direction is obtained in the positioning process of the contact line area, so that the interference of objects in other directions is removed, and the time for subsequent program processing is reduced. Due to the adoption of the image processing scheme based on the gradient, compared with the prior art, the real-time rigid contact net positioning point identification algorithm is insensitive to the light source, and the method can be suitable for carrying out rigid positioning point identification on images under different illumination conditions and can be used in the day and at night.

3. According to the technical scheme, the contact line candidate area is formed through the line extraction and line clustering modes, and the rigid contact line area is screened out from the contact line candidate area according to the width interval of the rigid contact line.

4. According to the technical scheme, the positioning of the rigid positioning point is realized by adopting an insulator characteristic identification mode, the image of the rigid contact line area is subjected to block analysis processing, the rigid positioning point area is obtained by identification through extracting the radial and longitudinal and transverse gray level distribution characteristics of the sliding window image, and the positioning is strong in real-time performance and high in accuracy.

5. The algorithm adopted by the technical scheme of the invention is convenient for parameter modification, and after the code is written, no professional is needed, and other non-professionals can modify the related parameters.

Drawings

The foregoing and following detailed description of the invention will be apparent when read in conjunction with the following drawings, in which:

FIG. 1 is a schematic diagram of the logical relationship of the present invention.

Detailed Description

The technical solutions for achieving the objects of the present invention are further illustrated by the following specific examples, and it should be noted that the technical solutions claimed in the present invention include, but are not limited to, the following examples.