CN111507186A - Substation pointer instrument reading identification method - Google Patents
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Abstract
The invention relates to a substation pointer instrument reading identification method which comprises dial plate scale area detection, digital position detection, identification number, pointer detection and reading identification, wherein the instrument reading identification is carried out on the basis of digital identification and pointer detection results, the correctness of the scale area detection can be verified by carrying out inclination and alignment identification on the identified number, and a distance calculation method based on the scale number is adopted in the reading identification process, so that the identification precision is ensured, and the reading identification method has good reliability.
Description
Technical Field
The invention relates to the field of pattern recognition, in particular to scale and pointer reading recognition and application of a pointer instrument image.
Background
A transformer substation needs a large number of instruments to monitor the working state of transformer equipment, and due to factors such as a complex electromagnetic environment, the instruments in the transformer substation basically adopt analog instruments and a pointer reading mode; the pointer type instrument needs manual reading, so a large amount of labor is consumed, and the reading precision is interfered by subjective factors and weather factors; in order to improve the automation management degree of the transformer substation, the research on automatic identification and reading of the pointer instrument has important application value.
The pointer type instrument automatic reading system generally takes an inspection robot as a platform, the platform is provided with various sensors such as a visible light camera, an infrared sensor and the like, corresponding instrument images are collected according to a planned path and an inspection shooting point, and image data are transmitted through wireless transmission equipment; the automatic reading identification system of the instrument identifies and stores the reading of the transmitted image for equipment monitoring and data analysis; the inspection robot carries out reasonable path planning, can obtain an instrument front-view image with better size and definition, and the automatic reading identification process of the instrument can be divided into the steps of image preprocessing, dial plate detection, pointer reading calculation and the like; the image preprocessing generally comprises the conventional processing operations of distortion elimination, denoising, enhancement, graying and the like; after the image is preprocessed, the current mainstream method is to detect the dial and the meter pointer, then calculate the included angle between the pointer and the zero reticle of the meter, and then obtain the reading of the current meter through the conversion of equal proportion according to the angle range and the reading range of the meter.
The dial detection generally adopts a round contour detection algorithm based on Hough transform, and the round contour in an image is detected by Hough transform as a dial detection result by setting a proper radius threshold; in addition, researchers also provide a plurality of Hough transform improvement methods for detecting the outline of the instrument, and the detection efficiency and the detection precision are improved.
According to the shape structure characteristics of the instrument pointer, Hough transform can also be used for detecting a straight line as a detection result of the instrument pointer; and the instrument pointer detection method based on image segmentation extracts a pointer area larger than a certain length threshold value as a pointer extraction result. In addition, the instrument pointer detection method also comprises a least square method, a silhouette method, a visual saliency feature identification method and the like. Based on the visual saliency feature recognition method, the pointer region of the instrument image is extracted by using the prior knowledge of the visual saliency region detection such as region contrast, spatial relationship, central prior and the like.
The most common pointer reading calculation methods include an angle method and a distance method; the angle method is a method which is commonly applied at present, and the slope of the pointer is calculated according to the pointer straight line detected in the front, so that the inclination angle of the straight line where the pointer is located is obtained; the method directly utilizes the geometric relation of straight lines to calculate, is simple and widely applied, but the measurement error of the included angle in the angle method can cause larger reading error and can only be applied to the reading of instruments with uniform scales; the distance method firstly detects all the scale marks, then finds two nearest scale marks on the left side and the right side of the pointer straight line, and calculates the pointer reading by calculating the ratio of the distance between the pixel points on the two scale marks and the pointer straight line according to the meter reading value represented by the scale marks; the distance method requires a large amount of calculation, and if the scale lines are detected accurately, the obtained angle value is also accurate.
In the existing pointer reading identification, most methods are based on the included angle between a pointer and a zero scale line, the methods rely on the accurate positioning of the zero scale line, if the zero scale line is positioned wrongly, the subsequent accuracy cannot be guaranteed, and the methods usually need the prior knowledge of the zero scale line and the measuring range of the instrument to calculate the relative position through the included angle to obtain the reading of the instrument.
Disclosure of Invention
Aiming at the defects of the prior art, the invention provides a reading identification method for a pointer instrument of a transformer substation, which starts from the identification of numbers on a scale mark, adopts a mutual verification mode of the numbers and the scale mark to identify the reading of the pointer, and improves the stability and the accuracy of the automatic reading of the pointer instrument of the transformer substation.
In order to achieve the purpose, the invention adopts the technical scheme that: a reading identification method for a pointer instrument of a transformer substation comprises the following steps:
(1) detecting an initial circumference where a scale mark in an instrument image is located by adopting a circumference detection method based on Hough transform, and detecting a group of concentric circles in and outside the initial circumference to verify the correctness of the detection of the initial circumference and realize the detection of a scale area with a certain width;
(2) detecting the digital position at the scale mark in a scanning mode in an image space based on the circle center and the radius of the concentric circle, and carrying out image extraction on the detected digital region;
(3) calculating the inclination angle of each digital original position relative to the ordinate axis of the instrument image according to the position information of the digital area image on the scale mark, performing correction rotation at the same angle to realize the correction of the corresponding digital inclination, and then identifying the rotated digital by adopting a template matching method;
(4) analyzing and calculating the recognized number, and verifying the correctness of the detection of the scale area by the inclination and correction recognition process; after the number is identified, recording the coordinates of the intersection point of the number center and the concentric circle center from the connection line of the number center and the concentric circle center, and marking the scale value at the intersection point as the digital value;
(5) on the basis of scale area detection and digital identification, extracting a pointer area image of the dial according to the circle center and the radius of a concentric circle, detecting a straight line in a specific area by adopting Hough transform, and taking a detection result as an instrument pointer identification result;
(6) calculating the pointer reading of the meter from the identified number and pointer position: if the two sides of the pointer have recognized numbers, reading calculation is carried out by adopting a halving method; if no number is recognized on one side, corresponding numbers are supplemented on the initial circumference by adopting a distance method according to the existing scale numbers, and then the pointer reading calculation is carried out by adopting a halving method.
The step (1) specifically comprises the following steps: firstly, carrying out edge detection on an instrument image by adopting a Canny operator, then setting an angle parameter range to be [0, pi ], setting an angle step length to be 0.01, setting a radius parameter range to be 1/1-3/4 of the image height, setting a radius increasing step length to be 1, and carrying out Hough transform to obtain a circle center O and a radius R of an initial circumference; and meanwhile, taking O as a circle center, taking the radius R as an initial value, respectively carrying out cyclic search by the step length of +1 and-1, determining the change range of R according to the height of the scale mark of the instrument, finding out 1/6-1/2 which meets the requirement that the accumulated value is at the maximum value, wherein the difference value of the accumulated value is within 20%, the region formed by arcs on the concentric circles is the scale region of the instrument, the number of the concentric circles represents the width of the scale region, if the concentric circles are in the direction of the step length of +1 of the R, the scale region is outside the initial circumference, otherwise, the concentric circles are inside the initial circumference.
The step (2) is specifically as follows: on the basis of the detection of the scale area, the digital position scanning search is carried out on the digital area and the scale area in the same side direction of the initial circumference according to the transverse interval distribution characteristic of the numbers: firstly, calculating the height of a number by scanning, taking the circle center O of an initial circumference as the circle center in an image space, taking a radius larger than a scale area as an initial value and taking the step length as 1, assuming that the number is outside the initial circumference, scanning from a left edge point of the scale area to a right edge by an angle step length of 0.01, and simultaneously recording the number of edge points on an arc line passed by a radius terminal; when the number of edge points generated after one-time scanning is not more than 5, considering that the edge points reach the top end of the digital area, stopping scanning and recording a scanning radius value, wherein the height of the number is the scanning frequency; then, scanning to obtain a left boundary and a right boundary of a number, scanning from a left edge point of a scale area to a right edge by an angle step length of 0.01 by taking O as a center of a circle in an image space, and in each angle, taking a radius larger than the scale area as an initial value, taking a final value to the top end of the digital area and taking the step length as 1, assuming that the number is outside an initial circumference, performing radial scanning, and simultaneously recording the number of edge points which pass through the radius terminal in the image space; according to the number of the recorded edge points and the size proportion of the numbers in the image, continuous non-edge point descriptions are blank areas between the numbers, continuous edge point descriptions are digital areas, and therefore left and right boundaries of the numbers are obtained; the left and right boundaries of the number are combined with the height of the number obtained in the front, so that each number position on the scale mark can be obtained, and each number area is scratched in the original image.
The specific process of the step (3) is as follows: after detecting and picking up the digital position, according to the position information of the number on the scale mark, calculating the inclination angle of each number, namely the included angle between the connecting line from the position point to the center of the concentric circle and the vertical line in the image space, carrying out the correction of the corresponding digital inclination by rotating the picked-up digital area image at the same included angle, carrying out binarization and standardization on the rotated digital image, and adopting a template matching method to identify the number.
The step (5) specifically comprises the following steps: selecting a pointer detection area based on the initial circumference of the circle center O and the radius R, carrying out graying and binarization preprocessing again, carrying out edge detection by adopting a Laplacian operator, finally adopting Hough transform detection and finding a straight line which passes through the circle center O and is in the scale area range, and if two similar pointer straight lines are detected, combining by adopting a least square method to obtain a straight line as a final pointer detection result.
The half-folding method in the step (6) specifically comprises the following steps:
a) on the basis of pointer detection, a pointer straight line intersects with an initial circumference, the coordinates C (x, y) of an intersection point are recorded, if C is the same as the coordinates of a recognized digit or within a certain threshold range, the pointer reading N is the digital value, reading recognition is finished, and the process goes to f); otherwise, searching the marked scale reading in the left and right directions of the straight line of the pointer, and setting the coordinates of the left reading N1 as (x 1, y 1) and the coordinates of the right reading N2 as (x 2, y 2);
b) taking the coordinate mean value of N1 and N2, namely the midpoint as M ((x 1+ x 2)/2, (y 1+ y 2)/2);
c) if the mean value M is equal to the intersection point C, the pointer reading is N = (N1 + N2)/2, the reading identification is finished, and go to f);
d) if the calculated coordinate mean value M is on the left side of the intersection C, N1= (N1 + N2)/2, and the coordinate at N1 is reassigned to be the intersection coordinate of the straight line of M and the center of the dial and the circle, and b) is executed in a loop;
e) if the calculated coordinate mean value M is on the right side of the intersection C, N2= (N1 + N2)/2, and the coordinate at N2 is reassigned to be the intersection coordinate of the straight line of M and the center of the dial and the circle, and b) is executed in a loop;
f) and outputting a pointer reading N.
The distance method in the step (6) is specifically as follows: selecting numbers at the left end and the right end of the identified scale area, calculating the difference between the two numbers, and calculating the arc length of the initial circumference between the scales at the two numbers to obtain the corresponding relation between the scale value and the arc length; according to the corresponding relation between the arc length and the scale value, based on the position information of the recognized number, measuring a corresponding arc segment along the initial circumference in the direction of the non-scale number to obtain the missing number scale value and the coordinate position thereof, wherein the arc segment length is limited in the scale area, and then supplementing the missing scale value.
Has the advantages that: compared with other pointer instrument reading identification technologies, the invention can identify the inclined numbers distributed on the circumference of the scale mark, mutually verify the identified numbers and the scale mark, and calculate the pointer reading based on the distance, thereby ensuring the reliability and the precision of the instrument reading. The method mainly comprises two aspects:
firstly, after a scale area is detected, a digital area is detected near the circumference, the digital area image is correspondingly rotated, the inclined number on the circumference is corrected and then recognized, the normal number is recognized, meanwhile, the correctness of the detection of the scale area is verified, and the reliability of the recognition is ensured.
Secondly, in the pointer reading calculation process, the scale reading at the intersection point of the pointer straight line and the circumference is calculated in a distance mode based on the detected number position of the scale.
Drawings
FIG. 1 is a graph of the gauge scale area test results of the present invention;
FIG. 2 is a test result of the invention after verification of the gauge scale area;
FIG. 3 is a digital position detection result of the present invention;
FIG. 4 is a result of digit extraction and recognition according to the present invention;
FIG. 5 is a pointer region image edge detection and pointer extraction result of the present invention;
FIG. 6 is a broken half pointer reading identification of the present invention;
fig. 7 is a scale numerical complement of the present invention.
Detailed Description
The invention is described in further detail below with reference to the figures and specific examples.
The invention provides a method for identifying the reading of a pointer instrument of a transformer substation, which comprises the following implementation steps of:
(1) detecting an initial circumference where a scale mark in an instrument image is located based on Hough transform, and simultaneously detecting a group of concentric circles in and outside the initial circumference to verify the correctness of the detection of the initial circumference and realize scale area detection with a certain width;
(2) detecting the digital position at the scale mark in a scanning mode in an image space based on the circle center and the radius of the concentric circle, and carrying out image extraction on the detected digital region;
(3) calculating the inclination angle of each digital original position relative to the ordinate axis of the instrument image according to the position information of the digital area image on the scale mark, performing correction rotation at the same angle to realize the correction of the corresponding digital inclination, and then identifying the rotated digital by adopting a template matching method;
(4) analyzing and calculating the recognized numbers, wherein the requirements on the quantity, numerical value and other instrument scale value characteristics are met, and meanwhile, the accuracy of the detection of the scale area is verified through the inclination and alignment recognition processes; after the number is identified, the coordinates of the intersection point with the initial circumference are recorded from the line connecting the center of the number and the center of the concentric circle, and the scale value at the intersection point is marked as the digital value.
(5) On the basis of scale area detection and digital identification, extracting a pointer area image of the dial according to the circle center and the radius of a concentric circle, detecting a straight line in a specific area by adopting Hough transform, and taking a detection result as an instrument pointer identification result;
(6) calculating the pointer reading of the meter from the identified number and pointer position: if the two sides of the pointer have recognized numbers, reading calculation is carried out by adopting a halving method; if no number is recognized on one side, the corresponding number is supplemented on the initial circumference, and then the pointer reading calculation is carried out by adopting a halving method.
Examples
Based on the visible light image acquired by the transformer substation inspection robot platform, the background is relatively simple and the target position is relatively fixed, so that the pointer instrument image target to be processed is supposed to be extracted, and preprocessing operations such as distortion elimination, denoising, enhancement, graying, binarization and the like are performed, and the process of reading and identifying the pointer instrument image by using the method provided by the invention is as follows.
(1) Dial scale zone detection
The dial scale area of the pointer instrument has the characteristic of a circular shape, so a circle detection method based on Hough transform is adopted, based on the principle of Hough transform circle detection, the circle parameter equations x = a + rcos theta and y = b + r sin theta (theta ∈ [0, 2 pi ]) are utilized, the image pixel space is corresponding to the parameter space, wherein (a, b) is the center coordinate, r is the radius of the circle, theta is a parameter, and (x, y) is the coordinate of a point where the circle passes through, the change range and the step length of the angle theta and the radius r are set, the values of a and b are calculated, if the values of a and b are in a reasonable range, the positions are counted and accumulated, and finally the center coordinate and the radius are found according to the maximum value.
Firstly, carrying out edge detection on an instrument image by adopting a Canny operator, then setting an angle parameter range to be [0, pi ], setting an angle step length to be 0.01, setting a radius parameter range to be 1/1-3/4 of the image height, setting a radius increasing step length to be 1, and carrying out Hough transform to obtain a circle center O and a radius R of an initial circumference; meanwhile, with O as a circle center and the radius R as an initial value, carrying out cyclic search respectively by step length +1 and-1, determining the variation range of R according to the height of the scale mark of the instrument, finding out the concentric circles which meet the requirement that the accumulated value is 1/6-1/2 of the maximum value and have the difference value of the accumulated value within 20%, wherein the area formed by the arcs on the concentric circles is the instrument scale area, the number of the concentric circles represents the width of the scale area, as shown in a red area in FIG. 1, the detected instrument scale area displays a result on an original image, the circle with the largest accumulated value detected in FIG. 2 cannot meet the condition of the concentric circles and is excluded, and finally the red area meeting the condition of the concentric circles is obtained as a scale area detection result; if the concentric circles are in the step +1 direction of R, it means that the scale region is outside the initial circumference, otherwise inside.
(2) Digital position detection
In order to ensure the correctness of the scale area detected in the instrument image, the number is further detected and recognized near the scale area, and the scale area detection reliability can be improved by mutually verifying the scale area and the number. On the basis of the detection of the scale area, the digital position scanning search is carried out on the digital area and the scale area in the same side direction of the initial circumference according to the transverse interval distribution characteristic of the numbers. Firstly, the height of the number is calculated by scanning, the radius is larger than the scale area as an initial value and the step length is 1 (assuming that the number is outside the initial circumference) by taking O as the center of a circle in the image space, the left edge point of the scale area is scanned to the right edge by the angle step length of 0.01, and meanwhile, the number of the edge points on the arc line passing through the radius terminal is recorded. When the number of edge points generated after one-time scanning is not more than 5, considering that the edge points reach the top end of the digital area, stopping scanning and recording a scanning radius value, wherein the height of the number is the scanning frequency; then, the left and right boundaries of the number are obtained by scanning, and the left and right boundaries are scanned from the left edge point of the scale area to the right edge in angular steps of 0.01 around the center O in the image space, and radial scanning is performed at each angle with the radius larger than the scale area as the initial value and the final value to the top of the digital area and the step size of 1 (assuming that the number is outside the initial circumference), and the number of edge points passed by the radius end in the image space is recorded. According to the number of recorded edge points and the size proportion of the numbers in the image, continuous non-edge point descriptions are blank areas between the numbers, and continuous edge point descriptions are digital areas, so that left and right boundaries of the numbers are obtained. The left and right boundaries of the number are combined with the previously obtained height of the number, so that each number position on the scale mark can be obtained, and each number area is scratched in the original image (gray image). The red area is the numerical position marked on the original meter image as shown in fig. 3.
(3) Identification number
After detecting the position of the digit and picking the digit, calculating the inclination angle of each digit according to the position information of the digit on the scale mark, namely the included angle between the connecting line from the position point to the circle center O and the vertical line in the image space; the extracted digital area image is rotated back to the normal direction with the same included angle to realize the correction of the inclination of the corresponding number; and (4) carrying out binarization and standardization on the rotated digital image, and identifying the digital image by adopting a template matching method.
Fig. 4 shows the detected numbers in fig. 3, wherein the first action is the original instrument image number region cutout, and the second action corresponds to the binarized image after the number region is respectively rotated back to the positive direction by 37 °, 15 ° and-10 °. In the template matching method, a digital template is established based on typical numbers in an image of a transformer substation instrument, and in order to improve matching accuracy, the digital template which is inclined and then aligned is added into the template so as to adapt to tiny deformation generated in the rotation process.
The number of recognized digits should be at least 2, and the left-hand value is smaller than the right-hand value, according to the numeric characteristics on the scale of the meter. The template matching number identification method based on the rotating image can assist reading of the instrument scale numerical value on one hand, and on the other hand, the rotating readable number also shows the existence of the scale arc line accompanied with the instrument scale numerical value, so that the accuracy of detection on the scale area can be verified. Based on the position of each identified number, connecting a line between the center of the number and the center of the concentric circle, calculating the coordinates of the intersection point of the line and the initial circle, and recording the scale values at the intersection point as the identified digital values 0, 1 and 2 respectively.
(4) Pointer detection
The straight line is detected in the identified dial plate area, the detection range is reduced, and the pointer detection becomes simple and the detection efficiency and accuracy are improved due to the circle center limiting condition of the dial plate. And selecting a pointer detection area based on the initial circumference of the circle center O and the radius R, performing graying and binarization preprocessing again, and performing edge detection by using a Laplace operator, as shown in FIG. 5. And finally, detecting by adopting Hough transform and finding a straight line which passes through the circle center O and is in the scale area range, if two similar pointer straight lines are detected in the graph 5, combining by adopting a least square method to obtain a straight line as a final pointer detection result, as shown by a red straight line segment in the graph 5.
(5) Reading identification
The meter reading identification is carried out on the basis of the digital identification and the pointer detection results, and the two conditions are divided. Firstly, if the scale areas on both sides of the straight line of the pointer have recognized scale numbers, the reading is calculated by adopting a 'halving method'. Secondly, if no number is recognized in the scale area on one side of the pointer, the scale area is supplemented on the other side by adopting a distance method according to the existing scale number, the coordinate record of the corresponding position of the scale area on the circumference and the corresponding numerical value are recorded, and then the reading recognition is carried out by adopting a halving method.
Folding method
On the basis of the pointer detection, a pointer straight line intersects with the initial circle, and the coordinates C (x, y) of the intersection point are recorded, as shown in FIG. 6, if C is the same as the coordinate at which a certain number is recognized (or within a certain threshold value range), the pointer reading N is the digital value, the reading recognition is finished, and the step goes to f); otherwise, searching the marked scale reading in the left and right directions of the straight line of the pointer, and setting the coordinates of the left reading N1 as (x 1, y 1) and the coordinates of the right reading N2 as (x 2, y 2);
taking the coordinate mean (midpoint) of N1 and N2 as M ((x 1+ x 2)/2, (y 1+ y 2)/2);
if the mean M is equal to the intersection C, the pointer reading is N = (N1 + N2)/2, the reading identification is finished, go to f);
if the calculated coordinate mean (midpoint) M is to the left of the intersection C, N1= (N1 + N2)/2, and the coordinate at N1 is reassigned as the intersection coordinate of the line and the circle of M with the center of the dial, and b) is executed in a loop;
if the calculated coordinate mean (midpoint) M is to the right of the intersection C, N2= (N1 + N2)/2, and the coordinate at N2 is reassigned as the intersection coordinate of the line and the circle of M with the center of the dial, and b) is executed in a loop;
outputting a pointer reading N.
The pointer reading is calculated by adopting the halving method, and after 4 iterations of the halving method, the calculation result of the final pointer reading is 0.03 as shown in fig. 6.
Distance method
And selecting numbers at the left end and the right end of the identified scale area, calculating the difference between the two numbers, and calculating the arc length of the initial circumference between the scales at the two numbers to obtain the corresponding relation between the scale value and the arc length. According to the corresponding relation between the arc length and the scale numerical value, based on the position information of the recognized number, measuring a corresponding arc segment along the initial circumference in the direction of the non-scale number to obtain the missing number scale value and the coordinate position thereof, wherein the arc segment length is limited in the scale area. If the pointer is on the right side of the scale 2, as shown in fig. 3 where the figure number 3 is not detected, it is necessary to calculate the relationship between the arc length and the scale position from the existing figures 0 and 2, and then supplement the scale value missing on the right side, as shown in fig. 7.
The pointer reading identification in the invention adopts a distance calculation method based on scale numbers, which not only ensures the identification precision, but also has good reliability.
Claims (7)
1. A reading identification method for a pointer instrument of a transformer substation is characterized by comprising the following steps:
(1) detecting an initial circumference where a scale mark in an instrument image is located by adopting a circumference detection method based on Hough transform, and detecting a group of concentric circles in and outside the initial circumference to verify the correctness of the detection of the initial circumference and realize the detection of a scale area with a certain width;
(2) detecting the digital position at the scale mark in a scanning mode in an image space based on the circle center and the radius of the concentric circle, and carrying out image extraction on the detected digital region;
(3) calculating the inclination angle of each digital original position relative to the ordinate axis of the instrument image according to the position information of the digital area image on the scale mark, performing correction rotation at the same angle to realize the correction of the corresponding digital inclination, and then identifying the rotated digital by adopting a template matching method;
(4) analyzing and calculating the recognized number, and verifying the correctness of the detection of the scale area by the inclination and correction recognition process; after the number is identified, recording the coordinates of the intersection point of the number center and the concentric circle center from the connection line of the number center and the concentric circle center, and marking the scale value at the intersection point as the digital value;
(5) on the basis of scale area detection and digital identification, extracting a pointer area image of the dial according to the circle center and the radius of a concentric circle, detecting a straight line in a specific area by adopting Hough transform, and taking a detection result as an instrument pointer identification result;
(6) calculating the pointer reading of the meter from the identified number and pointer position: if the two sides of the pointer have recognized numbers, reading calculation is carried out by adopting a halving method; if no number is recognized on one side, corresponding numbers are supplemented on the initial circumference by adopting a distance method according to the existing scale numbers, and then the pointer reading calculation is carried out by adopting a halving method.
2. The substation pointer instrument reading identification method of claim 1, wherein the step (1) specifically comprises the following steps: firstly, carrying out edge detection on an instrument image by adopting a Canny operator, then setting an angle parameter range to be [0, pi ], setting an angle step length to be 0.01, setting a radius parameter range to be 1/1-3/4 of the image height, setting a radius increasing step length to be 1, and carrying out Hough transform to obtain a circle center O and a radius R of an initial circumference; and meanwhile, taking O as a circle center, taking the radius R as an initial value, respectively carrying out cyclic search by the step length of +1 and-1, determining the change range of R according to the height of the scale mark of the instrument, finding out 1/6-1/2 which meets the requirement that the accumulated value is at the maximum value, wherein the difference value of the accumulated value is within 20%, the region formed by arcs on the concentric circles is the scale region of the instrument, the number of the concentric circles represents the width of the scale region, if the concentric circles are in the direction of the step length of +1 of the R, the scale region is outside the initial circumference, otherwise, the concentric circles are inside the initial circumference.
3. The substation pointer instrument reading identification method according to claim 1, wherein the step (2) is specifically as follows: on the basis of the detection of the scale area, the digital position scanning search is carried out on the digital area and the scale area in the same side direction of the initial circumference according to the transverse interval distribution characteristic of the numbers: firstly, calculating the height of a number by scanning, taking the circle center O of an initial circumference as the circle center in an image space, taking a radius larger than a scale area as an initial value and taking the step length as 1, assuming that the number is outside the initial circumference, scanning from a left edge point of the scale area to a right edge by an angle step length of 0.01, and simultaneously recording the number of edge points on an arc line passed by a radius terminal; when the number of edge points generated after one-time scanning is not more than 5, considering that the edge points reach the top end of the digital area, stopping scanning and recording a scanning radius value, wherein the height of the number is the scanning frequency; then, scanning to obtain a left boundary and a right boundary of a number, scanning from a left edge point of a scale area to a right edge by an angle step length of 0.01 by taking O as a center of a circle in an image space, and in each angle, taking a radius larger than the scale area as an initial value, taking a final value to the top end of the digital area and taking the step length as 1, assuming that the number is outside an initial circumference, performing radial scanning, and simultaneously recording the number of edge points which pass through the radius terminal in the image space; according to the number of the recorded edge points and the size proportion of the numbers in the image, continuous non-edge point descriptions are blank areas between the numbers, continuous edge point descriptions are digital areas, and therefore left and right boundaries of the numbers are obtained; the left and right boundaries of the number are combined with the height of the number obtained in the front, so that each number position on the scale mark can be obtained, and each number area is scratched in the original image.
4. The substation pointer instrument reading identification method of claim 1, wherein the specific process of the step (3) is as follows: after detecting and picking up the digital position, according to the position information of the number on the scale mark, calculating the inclination angle of each number, namely the included angle between the connecting line from the position point to the center of the concentric circle and the vertical line in the image space, carrying out the correction of the corresponding digital inclination by rotating the picked-up digital area image at the same included angle, carrying out binarization and standardization on the rotated digital image, and adopting a template matching method to identify the number.
5. The substation pointer instrument reading identification method of claim 1, wherein the step (5) specifically comprises: selecting a pointer detection area based on the initial circumference of the circle center O and the radius R, carrying out graying and binarization preprocessing again, carrying out edge detection by adopting a Laplacian operator, finally adopting Hough transform detection and finding a straight line which passes through the circle center O and is in the scale area range, and if two similar pointer straight lines are detected, combining by adopting a least square method to obtain a straight line as a final pointer detection result.
6. The substation pointer instrument reading identification method of claim 1, characterized in that: the half-folding method in the step (6) specifically comprises the following steps:
a) on the basis of pointer detection, a pointer straight line intersects with an initial circumference, the coordinates C (x, y) of an intersection point are recorded, if C is the same as the coordinates of a recognized digit or within a certain threshold range, the pointer reading N is the digital value, reading recognition is finished, and the process goes to f); otherwise, searching the marked scale reading in the left and right directions of the straight line of the pointer, and setting the coordinates of the left reading N1 as (x 1, y 1) and the coordinates of the right reading N2 as (x 2, y 2);
b) taking the coordinate mean value of N1 and N2, namely the midpoint as M ((x 1+ x 2)/2, (y 1+ y 2)/2);
c) if the mean value M is equal to the intersection point C, the pointer reading is N = (N1 + N2)/2, the reading identification is finished, and go to f);
d) if the calculated coordinate mean value M is on the left side of the intersection C, N1= (N1 + N2)/2, and the coordinate at N1 is reassigned to be the intersection coordinate of the straight line of M and the center of the dial and the circle, and b) is executed in a loop;
e) if the calculated coordinate mean value M is on the right side of the intersection C, N2= (N1 + N2)/2, and the coordinate at N2 is reassigned to be the intersection coordinate of the straight line of M and the center of the dial and the circle, and b) is executed in a loop;
f) and outputting a pointer reading N.
7. The substation pointer instrument reading identification method according to claim 1, wherein the distance method in the step (6) is specifically as follows: selecting numbers at the left end and the right end of the identified scale area, calculating the difference between the two numbers, and calculating the arc length of the initial circumference between the scales at the two numbers to obtain the corresponding relation between the scale value and the arc length; according to the corresponding relation between the arc length and the scale value, based on the position information of the recognized number, measuring a corresponding arc segment along the initial circumference in the direction of the non-scale number to obtain the missing number scale value and the coordinate position thereof, wherein the arc segment length is limited in the scale area, and then supplementing the missing scale value.
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