A cable joint detection test device

Abstract

The present invention relates to the technical field of cable joint thickness uniformity detection, and specifically to a cable joint detection test device, the device comprising a cable joint thickness uniformity detection device, the cable joint thickness uniformity detection device comprising a data collector, a controller and a clamping head, the clamping head having a clamping claw, the data collector connected to the controller, the data collector collects the cable joint image of the cable joint to be tested at each moment in the detection cycle and the pressure data of the clamping claws of the two clamping heads at each moment in the detection cycle; the controller obtains the overall edge fluctuation according to the difference in the position distribution of the edge line of the cable joint image at different moments, and obtains the overall concentricity by combining the direction of the edge line with the difference in the pressure data of the clamping claws of the two clamping heads at the same moment; the thickness uniformity detection result of the cable joint is obtained by combining the overall edge fluctuation and the overall concentricity. The present invention improves the accuracy of the test on the uniformity of the thickness of the insulation layer of the cable joint.

Description

Technical Field

[0001] The invention relates to the technical field of cable joint thickness uniformity detection, and in particular to a cable joint detection test device. Background Art

[0002] With the acceleration of urbanization and the widespread application of new energy, cables are the main medium for power transmission, and the quality of their joints directly affects the reliability of the power system. The insulation layer in the cable joint may be uneven due to various reasons during production, resulting in the concentration of electric field strength in certain areas of the cable joint, increasing the risk of partial discharge, accelerating the aging of the insulation layer, and ultimately leading to insulation breakdown. Therefore, it is very important to perform uniformity detection on the thickness of the insulation layer of the cable joint.

[0003] Methods for testing the uniformity of the thickness of the insulation layer of cable joints include laser detection methods and ultrasonic detection methods. The above traditional methods use probes to measure relevant data of cable joints. Probe inaccuracies or changes in probe pressure can easily cause errors in the collected data, resulting in low accuracy in testing the uniformity of the thickness of the insulation layer of cable joints. Summary of the invention

[0004] In order to solve the technical problem that the cable joint related test data collection is inaccurate, resulting in low accuracy of uniformity test of cable joint insulation layer thickness, the purpose of the present invention is to provide a cable joint detection test device, and the technical scheme adopted is as follows:

[0005] A cable joint detection test device, comprising a cable joint detection test device, the cable joint detection test device comprising a cable joint thickness uniformity detection device, the cable joint thickness uniformity detection device comprising a data collector, a controller and two clamping heads, the clamping heads having different clamping claws; the data collector is used to collect a cable joint image of a cable joint to be tested at each moment in a detection cycle, and pressure data of each clamping claw on the two clamping heads at each moment in the detection cycle;

[0006] The controller is used to obtain the analysis edge line of the received cable joint image at each moment, and obtain the overall edge fluctuation according to the difference between the position distributions of the analysis edge lines of the cable joint image at different moments in the detection cycle;

[0007] The overall concentricity is obtained according to the direction of the analyzed edge line of the cable joint image at all times during the detection cycle and the difference between the pressure data of the clamping claws on the two clamping heads at the same time;

[0008] According to the overall edge fluctuation and the overall concentricity, a thickness uniformity detection result of the cable joint is obtained.

[0009] Furthermore, the obtaining of the overall edge fluctuation specifically includes:

[0010] An image of a cable joint at any time is recorded as a reference image, and a matching point of each pixel on the analysis edge line in the reference image is obtained according to the relative position distribution of the analysis edge line in the reference image and the cable joint images at other times in the detection period except the reference image;

[0011] Obtain a standard edge line for the analysis edge line in the reference image; obtain the local edge fluctuation of the reference image based on the distance between the pixel point on the analysis edge line of the reference image and the standard edge line, and the distance between the pixel point and its matching point; and use the concentrated value of the local edge fluctuation of the cable connector image at all times within the detection period as the overall edge fluctuation.

[0012] Furthermore, obtaining the matching point of each pixel on the analysis edge line in the reference image specifically includes:

[0013] The analysis edge lines of the cable joint images at other times in the detection period except the reference image are respectively mapped to the corresponding curves of the reference image, which are recorded as the matching edge lines of the analysis edge lines of the reference image;

[0014] A pixel point is randomly selected from the analysis edge line of the reference image and recorded as the analysis pixel point; a straight line in a first preset direction is drawn through the analysis pixel point and recorded as the analysis straight line of the analysis pixel point; the analysis straight line intersects with all matching edge lines of the analysis edge line of the reference image;

[0015] The intersection points of the analysis straight line and all matching edge lines of the analysis edge line of the reference image are recorded as matching points of the analysis pixel points.

[0016] Furthermore, the method for obtaining the overall concentricity specifically includes:

[0017] According to the difference between the pressure data of the clamping claws on the two clamping heads at the same time, the clamping pressure difference at each moment in the detection cycle is obtained;

[0018] The angle between the standard edge line of the analysis edge line in the cable joint image at each moment and the second preset direction is used as the edge inclination of the analysis edge line in the cable joint image at each moment;

[0019] The local concentricity at each moment is obtained by analyzing the edge inclination and the clamping pressure difference of the edge line in the cable joint image at each moment; the concentrated value of the local concentricity at all moments in the detection cycle is taken as the overall concentricity.

[0020] Furthermore, the obtaining of the clamping pressure difference at each moment in the detection cycle specifically includes:

[0021] The accumulated sum of the pressure data of all the clamping claws on each clamping head at each moment is taken as the comprehensive pressure value of each clamping head at each moment;

[0022] The pressure data of the clamping claws on each clamping head at each moment are arranged in sequence to obtain the pressure sequence of each clamping head at each moment; the first-order difference sequence of the pressure sequence is obtained, and the difference between two elements in the first-order difference sequence is used as the pressure distribution difference of each clamping head at each moment;

[0023] The clamping pressure difference at each moment in the detection cycle is obtained according to the difference between the pressure comprehensive values ​​of the two clamping heads at each moment in the detection cycle and the difference between the pressure distribution differences.

[0024] Furthermore, the obtaining of the local edge fluctuation of the reference image according to the distance between the pixel point on the analysis edge line of the reference image and the standard edge line, and the distance between the pixel point and its matching point, specifically includes:

[0025] Obtain the average of the distances between each pixel point on the analysis edge line in the reference image and its matching point, as the edge change degree of each pixel point on the analysis edge line in the reference image;

[0026] The distance between each pixel point on the analysis edge line of the reference image and the standard edge line is recorded as the thickness abnormal value of the pixel point;

[0027] The average value of the product of the thickness abnormal value and the edge variation degree of all pixel points on the analysis edge line of the reference image is normalized to obtain the local edge fluctuation degree of the reference image.

[0028] Further, the obtaining of the uniform thickness detection result of the cable joint according to the overall edge fluctuation and the overall concentricity specifically includes:

[0029] According to the overall edge fluctuation and the overall concentricity, an insulation uniformity index is obtained;

[0030] A judgment is made based on the insulation uniformity index to obtain a thickness uniformity test result of the cable joint.

[0031] Furthermore, the method for obtaining the analysis edge line of the cable joint image at each moment specifically includes:

[0032] Obtaining a grayscale image of the cable joint image at each moment, performing curve fitting on pixel points at the same position in the cable joint image of edge pixel points obtained by edge detection of the grayscale image, and using the fitted curve as the initial edge line in the cable joint image at each moment;

[0033] The initial edge line representing any side of the cable joint to be tested in the cable joint images at all moments in the detection cycle is used as the analysis edge line of the cable joint image at each moment.

[0034] Furthermore, the method for obtaining a standard edge line for analyzing an edge line in a reference image specifically includes:

[0035] A fitting straight line obtained by linearly fitting the analysis edge line of the reference image and all its matching edge lines is recorded as the standard edge line of the reference image.

[0036] Furthermore, the clamping head is provided with three clamping claws.

[0037] The present invention has the following beneficial effects:

[0038] In the present invention, a cable joint thickness uniformity detection device is deployed on the cable joint detection test device, wherein the data acquisition device in the cable joint thickness uniformity detection device is used to collect the cable joint image of the cable joint to be tested at each moment in the detection cycle, and the pressure data of each clamping claw on the two clamping heads at each moment in the detection cycle, thereby providing a data basis for subsequently accurately judging the uniformity of the insulation layer thickness of the cable joint. Since the uneven thickness of the insulation layer of the cable joint will be reflected on the edge line of the cable joint image, the analysis edge line of the cable joint image is obtained through the controller; the difference between the position distribution of the analysis edge line of the cable joint image at different times in the detection cycle reflects the surface unevenness of the insulation layer of the cable joint to be tested during the rotation process, and the overall edge fluctuation that measures the difference in the thickness of the insulation layer of the cable joint to be tested is obtained; when there is a large difference in the thickness of the insulation layer of the cable joint, there is a large difference in the pressure on the two clamping heads, and the difference between the pressure data of the clamping claws on the two clamping heads at the same time can measure the concentricity of the cable joint during the rotation process, and then reflect the uniformity of the thickness of the insulation layer of the cable joint, and combine the direction of the analysis edge line of the cable joint image at all times in the detection cycle to obtain the overall concentricity, and measure the uniformity of the thickness of the insulation layer of the cable joint. The overall edge fluctuation and the overall concentricity are analyzed to accurately reflect the uniformity of the thickness of the insulation layer of the cable joint, and improve the accuracy of the uniformity test of the thickness of the insulation layer of the cable joint. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] In order to more clearly illustrate the technical solutions and advantages in the embodiments of the present invention or the prior art, the drawings required for use in the embodiments or the prior art descriptions are briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0040] Figure 1 A structural diagram of a cable joint detection test device provided by one embodiment of the present invention;

[0041] Figure 2 A schematic flow chart of a data processing process of a controller in a cable joint detection test device provided by an embodiment of the present invention;

[0042] Figure 1 The numbers in the figure are: 11, supporting platform; 12, platform supporting rod; 13, slide groove; 21, clamping base; 22, clamping claw; 23, knob; 31, motor; 32, transmission mechanism; 33, clamping device supporting rod; 41, pressure sensor; 51, camera supporting rod; 52, camera. DETAILED DESCRIPTION

[0043] In order to further explain the technical means and effects adopted by the present invention to achieve the predetermined invention purpose, the following is a detailed description of the specific implementation, structure, features and effects of a cable joint detection test device proposed according to the present invention in combination with the accompanying drawings and preferred embodiments. In the following description, different "one embodiment" or "another embodiment" does not necessarily refer to the same embodiment. In addition, specific features, structures or characteristics in one or more embodiments may be combined in any suitable form.

[0044] Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs.

[0045] An embodiment of the present invention provides a cable joint detection test device, including a cable joint detection test device, the cable joint detection test device includes a cable joint thickness uniformity detection device, and the cable joint thickness uniformity detection device includes a data collector, a controller and two clamping heads.

[0046] The specific scheme of the cable joint detection test device provided by the present invention is described in detail below with reference to the accompanying drawings.

[0047] See also Figure 1 , which shows a structural diagram of a cable joint detection test device provided by an embodiment of the present invention, the cable joint detection test device includes: a support platform 11; a platform support rod 12; a slide groove 13; a clamping base 21; a clamping claw 22; a knob 23; a motor 31; a transmission mechanism 32; a clamping device support rod 33; a pressure sensor 41; a camera support rod 51; and a camera 52.

[0048] The clamping device consists of two clamping heads, which are responsible for clamping the cable joint; one clamping head consists of a clamping seat 21, a knob 23 and three clamping claws 22; the clamping radius of the three clamping claws 22 is controlled by the knob 23. When testing the cable joint, the two clamping heads clamp the two ends of the insulation layer of the cable joint respectively. It should be noted that the two clamping heads are symmetrically and concentrically distributed in space, and a slide groove 13 is installed at the bottom of one of the clamping heads.

[0049] A pressure sensor 41 is distributed on the contact surface of each clamping claw 22 to detect the clamping force of each clamping claw. The camera 52 is located facing the cable connector to be tested.

[0050] The supporting device is composed of a supporting platform 11, four platform supporting rods 12 and a slide 13, which is used to provide a supporting platform for other devices; wherein the slide 13 is responsible for controlling the movement of a clamping head to facilitate the loading of the cable connector.

[0051] The rotating device is composed of two rotating structures; one rotating structure is composed of a motor 31, a transmission mechanism 32 and a support rod 33; one end of the support rod 33 is connected to the support platform 11, and the other end is connected to the motor 31 to support the motor; a clamping head is installed on the output side of the motor 31, and the rotation of the clamping head is controlled by the transmission mechanism 32. The transmission mechanism is a transmission shaft or a gear, etc.

[0052] The operation process of the cable joint detection test device is as follows:

[0053] (1) Move one of the clamping heads along the slide groove 13 to increase the distance between the two clamping heads to facilitate the placement of the cable connector to be tested.

[0054] (2) Rotate the knob 23 of each clamping head to release the clamping claw 22, place the two ends of the cable connector to be tested into the clamping device, and move the clamping device along the slide groove 13 so that the two clamping heads just clamp on both sides of the insulation layer of the cable connector to be tested; at the same time, fix the slide groove 13 and rotate the knob 23 to tighten the clamping claw 22 of the clamping device, thereby completing the fixation of the cable connector to be tested.

[0055] (3) The motor 31 is started and the power is transmitted through the transmission mechanism 32, so that the two clamping bases 21 rotate in the same direction and at the same speed, and the cable connector to be tested rotates one circle and then stops.

[0056] In the embodiment of the present invention, the time period corresponding to one rotation of the cable joint to be tested is taken as the detection period; the data acquisition device is composed of a camera 52 and pressure sensors 41 distributed on the contact surfaces of the three clamping claws 22 of the two clamping heads, that is, it is composed of a camera and six pressure sensors. Among them, the camera 52 is used to collect the image of the cable joint to be tested at each moment in the detection period, and the pressure sensor is used to collect the pressure data of each clamping claw on the two clamping heads at each moment in the detection period. It should be noted that the image acquisition frequency of the camera is the same as the data acquisition frequency of the pressure sensor. In the embodiment of the present invention, the image acquisition frequency of the camera is 60 frames per second, and the data acquisition frequency of the pressure sensor is 60 Hz. The implementer can set it according to the specific situation.

[0057] The controller can be a data processing chip such as a CPU, MCU, FPGA, or a data processing device such as a computer host. The data collector is connected to the controller, and the two can be connected by wire through a data transmission line, or wirelessly through wireless communication methods such as Bluetooth and WiFi. In addition, the data collector and the controller can also be integrated to form a device that integrates data collection and data processing functions.

[0058] The data collector is connected to the controller, and the data collector outputs the collected cable joint image and pressure data to the controller.

[0059] See also Figure 2 , which shows a flow chart of a data processing process of a controller in a cable joint detection test device provided by an embodiment of the present invention, comprising the following steps:

[0060] Step S100: obtaining the analysis edge line of the received cable joint image at each moment, and obtaining the overall edge fluctuation according to the difference between the position distributions of the analysis edge lines of the cable joint image at different moments in the detection cycle.

[0061] When the insulation thickness of the cable joint to be tested is uneven, during the detection process of the cable joint to be tested, since the cable joint is rotated around the center, the uneven insulation thickness of the cable joint will be reflected on the edge line of the cable joint image, so the analysis edge line of the cable joint image is obtained.

[0062] Preferably, in some possible implementation methods of the embodiments of the present invention, the method for obtaining the analysis edge line includes: obtaining a grayscale image of the cable joint image at each moment, performing curve fitting on the pixel points at the same position in the cable joint image obtained by edge detection of the grayscale image, and using the fitted curve as the initial edge line in the cable joint image at each moment; using the initial edge line representing any side of the cable joint to be tested in the cable joint images at all moments in the detection period as the analysis edge line of the cable joint image at each moment.

[0063] It should be noted that, in the embodiment of the present invention, a weighted average grayscale algorithm is used to grayscale the cable joint image, a Canny operator is used for edge detection, and a least square method is used for curve fitting. Among them, the weighted average grayscale algorithm, the Canny operator and the least square method are all well-known technologies for those skilled in the art, and will not be described in detail here. The cable joint image corresponds to the pixels in its grayscale image one by one.

[0064] When testing the cable joint to be tested, the cable joint to be tested is fixed in the horizontal direction and there is a certain distance between the two side edges of the cable joint to be tested. The edge pixel points obtained by edge detection of the grayscale image of the cable joint image are the pixel points at the edge positions on both sides of the cable joint to be tested, and then the initial edge lines obtained by curve fitting are the edges of the two side positions of the cable device to be tested. There are two initial edge lines in total and they do not intersect.

[0065] Since the two clamping heads in the device rotate in the same direction and at the same speed, and the change of the edge line on any side of the cable joint to be tested during the rotation process is global, that is, the position distribution of the edge line on one side can represent the thickness state of the insulation layer of the entire cable joint to be tested. In order to simplify the analysis process, this embodiment only selects the edge line on one side of the cable joint to be tested for analysis. The embodiment of the present invention uses the initial edge line that characterizes the upper edge of the cable joint to be tested as the analysis edge line. Specifically: the cable joint image at each moment has two initial edge lines, one initial edge line is located above the image, and the other initial edge line is located below the image. This embodiment uses the initial edge line located above the image in the cable joint image at all moments in the detection cycle as the analysis edge line.

[0066] The analysis edge line is the edge of the insulation layer surface of the cable joint to be tested. The difference between the position distribution of the analysis edge line of the cable joint image at different times during the detection cycle reflects the surface roughness, i.e., fluctuation, of the insulation layer of the cable joint to be tested during the rotation process. The overall edge fluctuation can be obtained to measure the difference in insulation layer thickness of the cable joint to be tested. The specific steps for obtaining the overall edge fluctuation are as follows:

[0067] Step S110: a cable joint image at any time is recorded as a reference image, and matching points of each pixel on the analysis edge line in the reference image are obtained according to the relative position distribution of the analysis edge lines in the reference image and the cable joint images at other times in the detection period except the reference image.

[0068] Preferably, in some possible implementation modes of the embodiments of the present invention, the method for obtaining the matching point of each pixel point on the analysis edge line includes: mapping the analysis edge lines of the cable connector image at the remaining moments in the detection period except the reference image to the corresponding curves of the reference image, respectively, and recording them as the matching edge lines of the analysis edge lines of the reference image; randomly selecting a pixel point from the analysis edge line of the reference image as the analysis pixel point, and drawing a straight line in a first preset direction through the analysis pixel point, which is recorded as the analysis straight line of the analysis pixel point; the analysis straight line intersects with all the matching edge lines of the analysis edge line of the reference image; and recording the intersection point of the analysis straight line with all the matching edge lines of the analysis edge line of the reference image as the matching point of the analysis pixel point.

[0069] It should be noted that, since the camera position in the cable joint detection test device is fixed, each moment in the detection cycle corresponds to the pixel points in the cable joint image at other moments. To facilitate subsequent analysis, the analysis edge lines in the cable joint images at all moments in the detection cycle are mapped to the same image, specifically: the edge line formed by the pixel points on the analysis edge line in the cable joint image at other moments in the detection cycle except the reference image and the pixel points at the corresponding position in the reference image is used as the matching edge line of the analysis edge line of the reference image.

[0070] When testing the cable joint to be tested, the cable joint to be tested is fixed in the horizontal direction. If the thickness uniformity of the insulation layer of the cable joint to be tested is good, the pixel points in the vertical direction of the analysis edge line of the reference image and any position on its matching edge line should be relatively concentrated; otherwise, the pixel points in the vertical direction of the analysis edge line of the reference image and any position on its matching edge line are discretely distributed. Therefore, in order to analyze the uniformity of the thickness of the insulation layer of the cable joint, the matching points of the analysis pixel points are obtained. In summary, in the embodiment of the present invention, the first preset direction is the vertical direction, and the implementer can set it according to the specific situation.

[0071] Step S120: Obtain the standard edge line of the analysis edge line in the reference image; obtain the local edge fluctuation of the reference image based on the distance between the pixel point on the analysis edge line of the reference image and the standard edge line, and the distance between the pixel point and its matching point; take the concentrated value of the local edge fluctuation of the cable connector image at all times within the detection period as the overall edge fluctuation.

[0072] The standard edge line of the analysis edge line reflects the overall trend of the edge line of the cable joint to be tested during the rotation process. In the embodiment of the present invention, a fitting straight line is obtained by linearly fitting the analysis edge line of the reference image with all its matching edge lines, and is recorded as the standard edge line of the analysis edge line in the reference image. It should be noted that the position of the standard edge line of the analysis edge line in the cable joint image at each moment in the detection cycle is the same as that at other moments.

[0073] If the distance between the pixel point on the analysis edge line of the reference image and the standard edge line is larger, the local fluctuation of the edge position edge line of the cable joint to be tested is larger, indicating that the difference in the insulation thickness of the corresponding area of ​​the reference image analysis edge line and other areas of the cable joint to be tested is larger, and the insulation thickness of the cable joint to be tested is uneven. The distance between the pixel point on the analysis edge line of the reference image and its matching point reflects the degree of fluctuation of the local edge position of the cable joint to be tested, and then the uniformity of the insulation thickness of the cable joint to be tested. Combining the above two factors for analysis, the overall edge fluctuation can accurately reflect the degree of edge fluctuation of the cable joint to be tested, and then reflect the uniformity of the insulation thickness of the cable joint to be tested.

[0074] Preferably, in some possible implementation modes of the embodiments of the present invention, the method for obtaining the local edge fluctuation includes: obtaining the mean of the distances between each pixel point on the analysis edge line in the reference image and its matching point, as the edge variation degree of each pixel point on the analysis edge line in the reference image; recording the distance between each pixel point on the analysis edge line of the reference image and the standard edge line as the thickness outlier value of the corresponding pixel point; normalizing the mean of the product of the thickness outlier values ​​of all pixel points on the analysis edge line of the reference image and the edge variation degree to obtain the local edge fluctuation degree of the reference image.

[0075] In a specific implementation of the embodiment of the present invention, the local edge fluctuation is expressed by the formula:

[0076]

[0077] Where FT is the local edge fluctuation of the reference image; M is the total number of pixels on the analysis edge line of the reference image; is the thickness outlier value of the mth pixel on the analysis edge line of the reference image; is the edge change degree of the mth pixel on the analysis edge line of the reference image; exp is an exponential function with the natural constant e as the base; Norm is the normalization function.

[0078] It should be noted that when The smaller the value is, the smaller the local fluctuation of the edge position of the cable joint to be tested is, which means that the analysis edge line of the reference image is closer to the insulation layer thickness of the corresponding area of ​​the cable joint to be tested and other areas, and the larger the local edge fluctuation degree FT is. When the value is larger, the discrete distribution of the pixels on the analysis edge line of the reference image and its matching points is more obvious, the fluctuation degree of the local edge position of the cable joint to be tested is greater, and the local edge fluctuation degree FT is greater. Therefore, the thickness anomaly value and edge variation are positively correlated with the local edge fluctuation degree.

[0079] The larger the local edge fluctuation, the worse the uniformity of the insulation layer thickness at the local position corresponding to the analyzed edge line in the reference image of the cable joint to be tested. In order to analyze the edge fluctuation of all positions of the cable joint to be tested, the local edge fluctuation of the cable joint image at all times in the detection period is comprehensively considered to obtain the overall edge fluctuation that measures the overall unevenness of the insulation layer thickness of the cable joint to be tested.

[0080] The central value of data is used to describe the central tendency of a group of data, which can be measured by statistical indicators such as mean, median and mode. In the embodiment of the present invention, the mean is used to measure the central value of data, and the mean of the local edge fluctuation of the cable joint image at all times in the detection period is used as the overall edge fluctuation; in other embodiments of the present invention, the mean can also be replaced by the median or mode. The larger the overall edge fluctuation, the more obvious the overall unevenness of the insulation layer thickness of the cable joint to be tested.

[0081] Step S200: Obtaining the overall concentricity according to the direction of the analyzed edge line of the cable joint image at all times within the detection cycle and the difference between the pressure data of the clamping claws on the two clamping heads at the same time.

[0082] Since the two clamping heads on the cable joint detection test device are symmetrically and concentrically distributed in space, and the two clamping heads rotate in the same direction and at the same speed during the detection, the forces felt by the two clamping heads during the rotation of the cable joint to be tested are similar. However, when there is a large difference in the thickness of the insulation layer of the cable joint, that is, the thickness at different positions of the cable joint is different, the cable joint will be non-concentric during the rotation process, and the force of the clamping heads on both sides to clamp the cable will change, resulting in a large difference in the pressure on the two clamping heads. Therefore, the difference between the pressure data of the clamping claws on the two clamping heads at the same time can measure the concentricity of the cable joint during the rotation process, and then reflect the uniformity of the insulation layer thickness of the cable joint.

[0083] Step S210: Obtain the clamping pressure difference at each moment in the detection cycle according to the difference between the pressure data of the clamping claws on the two clamping heads at the same moment.

[0084] Since the three clamping claws on the clamping head have different spatial positions at different times during the test, the pressure on each clamping claw is also different. The pressure distribution of the clamping claws on the clamping head can reflect the center of the cable joint to be tested in the clamping claws. If the concentricity of the cable joint is poor, the clamping claw will show a center deviation, that is, the position of the cable joint in the clamping claw is not centered. The concentricity of the cable joint can be determined by detecting the pressure distribution on the clamping claws.

[0085] This embodiment analyzes the pressure distribution of the clamping claws on the clamping head from two aspects: the total pressure distribution of the clamping claws on the clamping head and the pressure difference of different clamping claws on the clamping head. The clamping pressure difference is obtained according to the difference between the pressure distributions of the clamping claws on the two clamping heads, reflecting the concentricity of the cable connector to be tested.

[0086] Preferably, in some possible implementation modes of the embodiments of the present invention, the method for obtaining the clamping pressure difference includes: taking the cumulative sum of the pressure data of all the clamping claws on each clamping head at each moment as the comprehensive pressure value of each clamping head at each moment; arranging the pressure data of the clamping claws on each clamping head at each moment in sequence to obtain the pressure sequence of each clamping head at each moment; obtaining the first-order difference sequence of the pressure sequence, and taking the difference between two elements in the first-order difference sequence as the pressure distribution difference of each clamping head at each moment; and obtaining the clamping pressure difference at each moment in the detection cycle based on the difference between the comprehensive pressure values ​​of the two clamping heads at each moment in the detection cycle and the difference between the pressure distribution differences.

[0087] For each moment in the detection cycle, if the difference between the comprehensive pressure values ​​of the two clamping heads is greater, it indicates that the overall pressure difference on both sides of the cable joint to be tested is greater, and the clamping pressure difference is greater; if the difference between the pressure distribution differences of the two clamping heads is greater, it indicates that the pressure distribution deviation on both sides of the cable joint to be tested is greater, so that the pressure difference on both sides is greater, the clamping pressure difference is greater. Therefore, the difference in the comprehensive pressure values ​​of the two clamping heads at each moment and the difference in the pressure distribution difference are both positively correlated with the clamping pressure difference. In a specific implementation of an embodiment of the present invention, the pressure clamping difference is expressed by the formula:

[0088]

[0089] In the formula, is the clamping pressure difference at the tth moment in the detection cycle; It is the comprehensive pressure value of the first clamping head of the cable joint detection test device at the tth moment in the detection cycle; It is the comprehensive pressure value of the second clamping head of the cable joint detection test device at the tth moment in the detection cycle; is the pressure distribution difference of the first clamping head of the cable joint detection test device at the tth moment in the detection cycle; is the pressure distribution difference of the second clamping head of the cable joint detection test device at the tth moment in the detection cycle; is the absolute value function; is a normalized function. It should be noted that when the clamping pressure difference When it is larger, the difference between the pressure distribution on both sides of the cable joint to be tested is greater, and the concentricity of the cable joint to be tested is worse.

[0090] Step S220: taking the angle between the standard edge line of the analysis edge line in the cable joint image at each moment and the second preset direction as the edge inclination of the analysis edge line in the cable joint image at each moment.

[0091] The standard edge line of the analysis edge line reflects the overall trend of the edge line of the cable joint to be tested during the rotation process; when the cable joint to be tested is tested using the cable joint detection test device, the cable joint to be tested is fixed in the horizontal direction. If the cable joint to be tested is completely concentric in the clamping head, the deviation between the standard edge line of the analysis edge line and the horizontal direction is small; if the concentricity of the cable joint to be tested in the clamping head is worse, the distribution of the analysis edge line in the cable joint image during the detection cycle will deviate, resulting in a greater deviation between the standard edge line and the horizontal direction. Therefore, the angle between the standard edge line of the analysis edge line and the second preset direction, that is, the edge inclination, reflects the concentricity of the cable joint in the clamping head, and the greater the edge inclination, the worse the concentricity of the cable joint in the clamping head.

[0092] Since the cable connector to be tested in this embodiment is fixed in a horizontal direction during the test, the second preset direction is a horizontal direction, and the implementer can set it according to the specific situation.

[0093] Step S230: Analyze the edge inclination and clamping pressure difference of the edge line in the cable joint image at each moment to obtain the local concentricity at each moment; and take the concentrated value of the local concentricity at all moments in the detection cycle as the overall concentricity.

[0094] If the edge inclination of the analysis edge line in the cable joint image at each moment is larger, the concentricity of the clamping head of the cable joint to be tested at that moment is worse; if the clamping pressure difference at each moment is larger, the difference between the pressure distribution on both sides of the cable joint to be tested is larger, and the concentricity of the cable joint to be tested at that moment is worse. Therefore, the clamping pressure difference and the edge inclination are both negatively correlated with the overall concentricity. In an embodiment of the present invention, the product of the edge inclination of the analysis edge line in the cable joint image at each moment and the clamping pressure difference is negatively correlated and normalized to obtain the local concentricity at each moment. If the local concentricity at each moment is larger, the uniformity of the insulation layer distribution corresponding to the cable joint to be tested at each moment is better; conversely, the uniformity of the insulation layer distribution corresponding to the cable joint to be tested at each moment is worse.

[0095] In the embodiment of the present invention, the correlation between the edge inclination and the clamping pressure difference and the local concentricity difference can also be constructed through other basic mathematical operations, which will not be limited or elaborated here.

[0096] It should be noted that, in the embodiment of the present invention, the Sigmoid function is used for normalization processing. In the embodiment of the present invention, other normalization methods may also be selected, such as function conversion and other normalization methods, which are not limited here.

[0097] The local concentricity reflects the uniformity of the insulation layer distribution at the local position of the cable joint to be tested. To analyze the uniformity of the overall insulation layer distribution of the cable joint to be tested, it is necessary to consider the local concentricity at all times within the detection cycle. In the embodiment of the present invention, the average of the local concentricity at all times within the detection cycle is used as the overall concentricity; the greater the overall concentricity, the better the uniformity of the overall insulation layer distribution of the cable joint to be tested.

[0098] Step S300: Obtaining a thickness uniformity detection result of the cable joint according to the overall edge fluctuation and overall concentricity.

[0099] The overall edge fluctuation and overall concentricity both reflect the uniformity of the overall insulation layer distribution of the cable joint to be tested. In this embodiment, an insulation uniformity index is obtained based on the overall edge fluctuation and overall concentricity; and a thickness uniformity test result of the cable joint is obtained by making a judgment based on the insulation uniformity index.

[0100] If the overall edge fluctuation is larger, the overall insulation layer thickness of the cable joint to be tested is more uneven; if the overall concentricity is larger, the overall insulation layer distribution uniformity of the cable joint to be tested is better. Therefore, the overall edge fluctuation is negatively correlated with the insulation uniformity index, and the overall concentricity is positively correlated with the insulation uniformity index. In an embodiment of the present invention, the ratio of the overall concentricity to the overall edge fluctuation is normalized to obtain the insulation uniformity index. If the insulation uniformity index is larger, the insulation layer thickness of the cable joint to be tested is more uniform, and the possibility that the insulation layer thickness of the cable joint to be tested is qualified is greater.

[0101] In the embodiment of the present invention, the correlation between the overall concentricity and the overall edge fluctuation and the insulation uniformity index, such as the difference, can also be constructed through other basic mathematical operations, which are not limited or elaborated here.

[0102] If the insulation uniformity index is less than the insulation uniformity threshold, the insulation layer thickness uniformity of the cable joint to be tested is poor, and the insulation layer thickness of the cable joint to be tested is unqualified; if the insulation uniformity index is greater than or equal to the insulation uniformity threshold, the insulation layer uniformity of the cable joint to be tested is good, and the insulation layer thickness of the cable joint to be tested is qualified.

[0103] It should be noted that in the embodiment of the present invention, the insulation uniformity threshold is an empirical value of 0.6, and the implementer can set it according to the specific situation.

[0104] The embodiments described above are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, a person skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some of the technical features may be replaced by equivalents. Such modifications or replacements do not deviate the essence of the corresponding technical solutions from the scope of the technical solutions of the embodiments of the present application, and should all be included in the protection scope of the present application.

Claims

1. A cable joint detection test device, comprising a cable joint detection test device, characterized in that: The cable joint detection test device comprises a cable joint thickness uniformity detection device, which comprises a data collector, a controller and two clamping heads, wherein the clamping heads are provided with different clamping claws; the data collector is used to collect the cable joint image of the cable joint to be tested at each moment in the detection cycle, and the pressure data of each clamping claw on the two clamping heads at each moment in the detection cycle; The controller is used to obtain the analysis edge line of the received cable joint image at each moment, and obtain the overall edge fluctuation according to the difference between the position distributions of the analysis edge lines of the cable joint image at different moments in the detection cycle; The overall concentricity is obtained according to the direction of the analyzed edge line of the cable joint image at all times during the detection cycle and the difference between the pressure data of the clamping claws on the two clamping heads at the same time; Obtaining a thickness uniformity detection result of the cable joint according to the overall edge fluctuation and the overall concentricity; The obtaining of the overall edge fluctuation specifically includes: An image of a cable joint at any time is recorded as a reference image, and a matching point of each pixel on the analysis edge line in the reference image is obtained according to the relative position distribution of the analysis edge line in the reference image and the cable joint images at other times in the detection period except the reference image; Obtain a standard edge line for the analysis edge line in the reference image; obtain the local edge fluctuation of the reference image based on the distance between the pixel point on the analysis edge line of the reference image and the standard edge line, and the distance between the pixel point and its matching point; and use the concentrated value of the local edge fluctuation of the cable connector image at all times within the detection period as the overall edge fluctuation.

2. A cable joint detection test device according to claim 1, characterized in that: The obtaining of the matching point of each pixel on the edge line of the reference image specifically includes: The analysis edge lines of the cable joint images at other times in the detection period except the reference image are respectively mapped to the corresponding curves of the reference image, which are recorded as the matching edge lines of the analysis edge lines of the reference image; A pixel point is randomly selected from the analysis edge line of the reference image and recorded as the analysis pixel point; a straight line in a first preset direction is drawn through the analysis pixel point and recorded as the analysis straight line of the analysis pixel point; the analysis straight line intersects with all matching edge lines of the analysis edge line of the reference image; The intersection points of the analysis straight line and all matching edge lines of the analysis edge line of the reference image are recorded as matching points of the analysis pixel points.

3. A cable joint detection test device according to claim 1, characterized in that: The method for obtaining the overall concentricity specifically includes: According to the difference between the pressure data of the clamping claws on the two clamping heads at the same time, the clamping pressure difference at each moment in the detection cycle is obtained; The angle between the standard edge line of the analysis edge line in the cable joint image at each moment and the second preset direction is used as the edge inclination of the analysis edge line in the cable joint image at each moment; The local concentricity at each moment is obtained by analyzing the edge inclination and the clamping pressure difference of the edge line in the cable joint image at each moment; the concentrated value of the local concentricity at all moments in the detection cycle is taken as the overall concentricity.

4. A cable joint detection test device according to claim 3, characterized in that: The obtaining of the clamping pressure difference at each moment in the detection cycle specifically includes: The accumulated sum of the pressure data of all the clamping claws on each clamping head at each moment is taken as the comprehensive pressure value of each clamping head at each moment; The pressure data of the clamping claws on each clamping head at each moment are arranged in sequence to obtain the pressure sequence of each clamping head at each moment; the first-order difference sequence of the pressure sequence is obtained, and the difference between two elements in the first-order difference sequence is used as the pressure distribution difference of each clamping head at each moment; The clamping pressure difference at each moment in the detection cycle is obtained according to the difference between the pressure comprehensive values ​​of the two clamping heads at each moment in the detection cycle and the difference between the pressure distribution differences.

5. A cable joint detection test device according to claim 1, characterized in that: The obtaining of the local edge fluctuation degree of the reference image according to the distance between the pixel point on the analysis edge line of the reference image and the standard edge line, and the distance between the pixel point and the matching point thereof, specifically includes: Obtain the average of the distances between each pixel point on the analysis edge line in the reference image and its matching point, as the edge change degree of each pixel point on the analysis edge line in the reference image; The distance between each pixel point on the analysis edge line of the reference image and the standard edge line is recorded as the thickness abnormal value of the pixel point; The average value of the product of the thickness abnormal value and the edge variation degree of all pixel points on the analysis edge line of the reference image is normalized to obtain the local edge fluctuation degree of the reference image.

6. A cable joint detection test device according to claim 1, characterized in that: The obtaining of the uniform thickness detection result of the cable joint according to the overall edge fluctuation and the overall concentricity specifically includes: According to the overall edge fluctuation and the overall concentricity, an insulation uniformity index is obtained; A judgment is made based on the insulation uniformity index to obtain a thickness uniformity test result of the cable joint.

7. A cable joint detection test device according to claim 1, characterized in that: The method for obtaining the analysis edge line of the cable joint image at each moment specifically includes: Obtaining a grayscale image of the cable joint image at each moment, performing curve fitting on pixel points at the same position in the cable joint image of edge pixel points obtained by edge detection of the grayscale image, and using the fitted curve as the initial edge line in the cable joint image at each moment; The initial edge line representing any side of the cable joint to be tested in the cable joint images at all times within the detection cycle is used as the analysis edge line of the cable joint image at each time.

8. A cable joint detection test device according to claim 1, characterized in that: The method for obtaining a standard edge line for analyzing an edge line in a reference image specifically comprises: A fitting straight line obtained by linearly fitting the analysis edge line of the reference image and all its matching edge lines is recorded as the standard edge line of the reference image.

9. A cable joint detection test device according to claim 1, characterized in that: The clamping head is provided with three clamping claws.

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