阅读说明：本技术 适用于刚柔接触网的实时定位点识别方法 (Real-time positioning point identification method suitable for rigid-flexible contact network ) 是由 高仕斌 于龙 占栋 *** 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,公开了一种适用于刚柔接触网的实时定位点识别方法,包括图像预处理步骤、接触线区域定位步骤、柔性定位点定位步骤和刚性定位点定位步骤,这种实时刚、柔性接触网的定位点识别方法,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以及梯度的图像处理方案,通过线条提取、线条聚类的方式形成接触线候选区域、采用定位杆定位的方式实现柔性定位点定位、采用绝缘子特征识别的方式实现刚性定位点定位,相比采用电子标签、雷达或GPS等定位点识别方案检测效率实施成本更低、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 line system, and discloses a real-time positioning point identification method suitable for a rigid-flexible contact line system, which comprises an image preprocessing step, a contact line region positioning step, a flexible positioning point positioning step and a rigid positioning point positioning step, the locating point identification method of the real-time rigid and flexible contact net realizes the non-contact detection of the locating point of the contact net and the image processing scheme of the gradient based on the image processing detection technology, the method has the advantages that the contact line candidate area is formed through line extraction and line clustering, the flexible positioning point is positioned through the positioning rod, the rigid positioning point is positioned through the insulator characteristic identification, and compared with positioning point identification schemes such as an electronic tag, a radar or a GPS, the method is lower in implementation cost, higher in detection efficiency and better in positioning reliability.)

1. The real-time positioning point identification method suitable for the rigid-flexible contact network is characterized by comprising the following steps of: the method comprises the steps of image preprocessing, contact line area positioning, flexible positioning point positioning or rigid positioning point positioning;

the image preprocessing step is to input the collected original image and perform gray level enhancement processing on the original image;

the contact line area positioning step is used for sequentially carrying out horizontal gradient calculation, line extraction and line clustering on the image subjected to the gray level enhancement processing in the image preprocessing step to form a candidate area, carrying out area screening processing on the candidate area, and respectively positioning a flexible contact line area or a rigid contact line area contained in the image;

the flexible positioning point positioning step is to take the candidate area positioned in the contact line area positioning step as an input image, traverse the gray image pixel points of the input image, respectively count the pixel segments with continuous gray values of greater than a set threshold in the directions of 0 degree, 45 degrees, 90 degrees and 135 degrees as strokes, and screen out characteristic strokes according to whether the stroke length meets the set threshold; then traversing all the characteristic strokes, expanding the characteristic strokes to the periphery by taking the middle points of the characteristic strokes as centers, intercepting a small image with a set size and carrying out binarization processing on the small image; then, conducting connected domain processing on the small images subjected to binarization processing, calculating geometric parameter characteristics including area, length-width ratio and perimeter value of the connected domain, and marking the connected domain with all the geometric parameter characteristics meeting set conditions as a flexible positioning point for output;

the step of positioning the rigid positioning point comprises the steps of extracting the image characteristics of the insulator sample and positioning and scanning; 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 small image screenshot of an insulator region, normalizing the intercepted small images to the same size to serve as an insulator sample image, traversing the insulator sample image by adopting a window with a preset size of Nx N, and sequentially calculating positive and negative marking values of difference between gray values of all non-central pixels and central pixels in the window to serve as a first feature, 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 real-time anchor point identification method applicable to the rigid-flexible contact line of claim 1, wherein: the image preprocessing step is to calculate the gradient value of each pixel point in the original image G (x, y) by using a numerical gradient function gradient (x, y), 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 adjacent pixels have gradients, the gradients are added with the corresponding original pixels, and the gray value is increased; otherwise, if the gradient is 0, the original pixel is unchanged.

3. The real-time anchor point identification method applicable to the rigid-flexible contact line of claim 1, wherein: in the step of locating the 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; then, calculating the midpoint of an interval of the interval marked as 1 continuously in each line, wherein the midpoint is used as a line candidate point of the interval; and then connecting the line candidate points of two adjacent lines within the distance of the specified pixel in the x direction and outputting the line candidate points as the same line, otherwise, outputting the line candidate points as different lines.

4. The real-time anchor point identification method applicable to the rigid-flexible contact line of claim 1, wherein: in the step of locating the 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 sequenced lines, wherein line clustering is to form a candidate area, classifying a first line into a first class, namely the first line after sequencing is completed, traversing each line from left to right from the beginning of a second line in sequence, calculating the distance between the line and the first line and the last line in all previous classes in the x direction by using the average value x _ mean, classifying the line into the same class if the distance meets a threshold condition, and classifying the line into one class if the distance does not meet the threshold condition of the distance with all previous classes; finally, each class is a candidate area containing a contact line.

5. The real-time anchor point identification method applicable to the rigid-flexible contact line as claimed in claim 5, characterized in that: in the step of locating 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 obtained by the line clustering in the x direction, namely the region width, and screen out the final candidate region containing the contact line according to the region width, for example, screen out the flexible contact line region according to whether the region width meets the threshold region of the flexible or rigid contact line region width.

6. The real-time anchor point identification method applicable to the rigid-flexible contact line of claim 1, wherein:

setting a threshold value in the flexible positioning point positioning step, wherein the threshold value is determined in an iterative optimal threshold value mode;

the aspect ratio of the connected domain is calculated by calculating the centroid of the region and then calculating the major axis and the minor axis of the region according to the centroid, specifically, assuming that the binary image f (x, y) and the area of the region is S, the centroid coordinate is

after the centroid of the region is obtained, traversing each coordinate point of the connected domain, and calculating the closest point p1 and the farthest point p2 from the centroid in the region; defining the distance between the closest point p1 and the centroid as a short axis D1, and the distance between the farthest point p2 and the centroid as a long axis D2, and then the aspect ratio pwr is D2/D1;

in the step of positioning the flexible positioning points, the perimeter of the connected domain is calculated, namely the area occupied by the boundary pixel points is defined as the perimeter, namely the number of the pixel points occupied by the boundary points; or the length of the curve coded by 8-chain codesWherein N is₁Number of pixel points, N, indicating a pointing direction of 0, 2, 4, 6₂The number of pixel points pointing to 1, 3, 5, 7.

7. The real-time anchor point identification method applicable to the rigid-flexible contact line of claim 1, wherein: 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 mirror image boundary expansion on the image in the sliding window, and 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.

8. The method for identifying the real-time positioning point suitable for the rigid-flexible contact line according to claim 1 or 8, wherein in the step of positioning the rigid positioning point, the step of calculating the insulator image features 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-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 it stores a computer program, which when executed in a computer processor, implements the steps of the method for real-time location point identification for a rigid-flexible contact line according to any one of the preceding claims 1 to 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 method for real-time location point identification for a rigid-flex contact system 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 contact networks, and particularly relates to a real-time positioning point identification method suitable for a rigid-flexible contact network.

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. The lead of the contact net can be divided into two types, namely a rigid lead and a flexible lead, wherein the flexible lead is mainly applied to the line design of the open environment, and the rigid lead is mainly applied to the tunnel environment of the lines such as the subway. 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.

In the measurement of geometrical parameters of the overhead line system, two different types of wires exist, and the design heights of the two wires are not consistent. Therefore, in the actual measurement process, there will be a rigid-flexible transition section of the line, which gradually transitions from a rigid wire to a flexible wire, or vice versa. At present, the main non-contact-based geometric parameter measurement method is to independently and separately measure geometric parameter data in different line intervals according to different types of wires, and finally integrate all complete data of a line after completing data measurement of the whole line, wherein the integrated reference standard is mainly the installation positions of the wires of different types. According to the method, the two different types of wires are arranged in the rigid-flexible transition section of the line at the same time, so that large errors can occur in measured data.

Currently, the positioning point detection technology is applied to a contact network, and is used as a basis for triggering an area-array camera to acquire and shoot images in a contact network defect detection system, and 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 the defects in the prior art, the invention aims to provide a real-time positioning point identification method suitable for a rigid-flexible contact network.

The invention provides a real-time positioning point identification method suitable for a rigid-flexible contact network, which comprises an image preprocessing step, a contact line area positioning step, a flexible positioning point positioning step and a rigid positioning point positioning step;

the image preprocessing step is to input the collected original image, and perform gray level enhancement processing on the original image to improve the quality, contrast and the like of the original image;

the contact line area positioning step is used for sequentially carrying out horizontal gradient calculation, line extraction and line clustering on the image subjected to the gray level enhancement processing in the image preprocessing step to form a candidate area and area screening processing, and respectively positioning the candidate area of the flexible contact line or the rigid contact line contained in the image;

the flexible positioning point positioning step comprises the steps of firstly taking the candidate area positioned in the contact line area positioning step as an input image, traversing the gray image pixel points of the input image, respectively counting the pixel segments of which the continuous gray values in the directions of 0 degree, 45 degrees, 90 degrees and 135 degrees are larger than a set threshold as strokes, namely strokes of all lengths, and extracting characteristic strokes according to whether the stroke lengths accord with the set threshold; then traversing all the characteristic strokes, expanding the characteristic strokes to the periphery by taking the middle points of the characteristic strokes as centers, intercepting a small image with a set size and carrying out binarization processing on the small image; then, conducting connected domain processing on the small images subjected to binarization processing, calculating geometric parameter characteristics including area, length-width ratio and perimeter value of the connected domain, and marking the connected domain with all the geometric parameter characteristics meeting set conditions as a flexible positioning point for output;

the step of positioning the rigid positioning point 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 candidate area obtained in the contact line area positioning step by adopting a sliding window, recording an image feature formed by connecting a first feature and/or a second feature contained in the sliding window in series 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.

Preferably, the image preprocessing step is to calculate a gradient value of each pixel point in the original image G (x, y) by using a value gradient function gradient (x, y), and superimpose 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, add the gradient to the corresponding original pixel, and increase the gray value; 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 locating the 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.

Preferably, in the step of locating the contact line region, the line extraction is to set a fixed gray threshold, sequentially traverse each pixel point in the image after the gradient calculation by row, and mark a certain pixel point as 1 when the gray value of the certain pixel point is greater than the threshold; then, calculating the midpoint of an interval of the interval marked as 1 continuously in each line, wherein the midpoint is used as a line candidate point of the interval; and then connecting the line candidate points of two adjacent lines within the distance of the specified pixel in the x direction and outputting the line candidate points as the same line, otherwise, outputting the line candidate points as different lines.

In the step of locating the 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 sequenced lines, wherein line clustering is to form a candidate area, classifying a first line into a first class, namely the first line after sequencing is completed, traversing each line from left to right from the beginning of a second line in sequence, calculating the distance between the line and the first line and the last line in all previous classes in the x direction by using the average value x _ mean, classifying the line into the same class if the distance meets a threshold condition, and classifying the line into one class if the distance does not meet the threshold condition of the distance with all previous classes; finally, each category is a candidate area containing a contact line, and it should be noted here that the candidate area of the contact line contains both flexible and rigid contact lines.

In the 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 difference and the rightmost difference is the width) is calculated, the area width is obtained, the final candidate area containing the contact line can be screened out according to the area widths, and a flexible contact line area or a rigid contact line area can be judged according to whether the area widths accord with a flexible or rigid contact line area width threshold interval or not.

Specifically, the threshold is set in the flexible positioning point positioning step and is determined in an iterative optimal threshold mode, the iterative optimal threshold is assumed to have no prior knowledge of the exact position of the related object, as a first step approximation, four corners of the image are considered to contain background pixels, and other parts of the image contain object pixels, specifically, in the t step, the gray level mean values of the background and the object are respectively calculated

Andwherein the threshold for segmenting the image into background and object at the T-th step is T^tIt is determined at step S3:

S1，

s2, placing

T^t+1Providing an updated background and object differentiation;

s3, if T^t+1＝T^tStopping; otherwise, the step S2 is returned to.

The area of the connected domain, the area of the region, that is, the number of pixels in the pixel point set of the region, that is, the number of pixels included in the boundary of the region, is calculated, and specifically, a connected domain of the binary image f (x, y) is setIs of a size M x N,

wherein:

then the area of the region is

Further, the aspect ratio of the connected domain may be obtained by calculating a centroid of the region and then calculating a major axis and a minor axis of the region according to the centroid, and specifically, assuming that the binary image f (x, y) and the area of the region is S, the centroid coordinate is S

After the centroid of the region is obtained, traversing each coordinate point of the connected domain, and calculating the closest point p1 and the farthest point p2 from the centroid in the region; defining the distance between the closest point p1 and the centroid as the short axis D1, and the distance between the farthest point p2 and the centroid as the long axis D2, the aspect ratio pwr is D2/D1.

The calculation of the perimeter of the connected domain mainly has two defining modes:

1. length of curve coded with 8-chain code:wherein N is₁The number of pixel points with pointing directions of 0, 2, 4 and 6 is represented; n is a radical of₂Number of pixel points pointing to 1, 3, 5, 7;

2. the area occupied by the boundary pixel points is defined as the perimeter, namely the number of the pixel points occupied by the boundary points.

Further, 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 mirror image boundary expansion on the image in the sliding window, and in order to avoid missing positioning, only performing expansion on left and right mirror image boundaries.

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.

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;

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.

Compared with the prior art, the technical scheme of the invention has the following beneficial effects:

1. the locating point identification method of the rigid and flexible contact net in real time realizes non-contact detection of the locating point of the contact net based on the image processing detection technology, and has lower implementation cost, higher detection efficiency and better locating reliability compared with the scheme of adopting electronic tags, radars or GPS and other locating point identification schemes.

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 flexible contact net positioning point identification algorithm is insensitive to the light source, and the method can be suitable for carrying out flexible 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 and flexible contact line areas are screened out from the contact line candidate area according to the width interval of the flexible contact line.

4. According to the technical scheme, the flexible positioning point is positioned by adopting a positioning rod positioning mode, the characteristic that the background interference of the flexible positioning point area is less than that of a rigid positioning point is fully considered, the stroke which does not meet the requirement is filtered according to the stroke characteristic threshold in the specific direction, and the stroke which meets the requirement is subjected to binaryzation and area characteristic calculation steps to finally obtain the flexible positioning point area, so that the positioning real-time performance is strong, and the accuracy is high; the method has the advantages that the positioning of the rigid positioning points 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 real-time performance and the accuracy are high.

5. The algorithm parameters adopted by the invention are convenient to modify, and after the codes are 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;

FIG. 2 is a schematic diagram of the binarization processing in the flexible positioning point positioning step 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.