Cable flexible joint defect detection method, device, system and equipment and storage medium

Abstract

The invention relates to a cable flexible joint defect detection method, device, system and equipment and a storage medium. The method comprises the following steps: scanning a to-be-detected cable flexible joint according to a preset scanning step length, and obtaining terahertz time-domain spectral signals of all scanning points in the to-be-detected cable flexible joint; the terahertz time-domain spectral signals of all the scanning points are preprocessed, target time-domain spectral signals corresponding to all the scanning points are obtained, and preprocessing comprises detrending processing, filtering processing and smoothing processing; and performing defect detection on the cable flexible joint according to each target time-domain spectral signal. By adopting the method, the defects of the cable flexible joint can be accurately detected.

Description

Technical Field

[0001] The present application relates to the technical field of cable defect detection, and particularly to a method, device, system, equipment and storage medium for detecting cable soft joint defects. Background Art

[0002] Due to limitations in cable manufacturing and transportation levels, the length of a single produced cable is insufficient to meet application requirements. Therefore, cable soft joints are needed to connect the cables to achieve the required length. During the production of soft joints, defects may form at the cable body - restored insulation interface, and these defects will ultimately cause the insulation of the soft joint to fail during operation. Therefore, to ensure the quality of soft joints, it is very necessary to detect the insulation defects of soft joints.

[0003] In the prior art, a scanning electron microscope is used to observe the cable soft joint. However, it is difficult to detect internal defects of the cable soft joint while locating the interface area, and there are inaccurate defect detection situations. Summary of the Invention

[0004] Based on this, in view of the above technical problems, it is necessary to provide a method, device, system, equipment and storage medium for detecting cable soft joint defects that can accurately detect cable soft joint defects.

[0005] In a first aspect, the present application provides a method for detecting cable soft joint defects, including:

[0006] Scanning the cable soft joint to be measured according to a preset scanning step length, and obtaining the terahertz time-domain spectroscopy signals of each scanning point in the cable soft joint to be measured;

[0007] Preprocessing the terahertz time-domain spectroscopy signals of each scanning point to obtain the target time-domain spectroscopy signals corresponding to each scanning point. The preprocessing includes detrending processing, filtering processing and smoothing processing;

[0008] Detecting defects of the cable soft joint according to each target time-domain spectroscopy signal.

[0009] In one of the embodiments, the method further includes:

[0010] If there are defects in the cable soft joint, determining the defect time-domain spectroscopy signal according to the defect position. The defect time-domain spectroscopy signal is the target time-domain spectroscopy signal of the scanning point corresponding to the defect position; determining the defect depth information according to the first time corresponding to the defect reflection peak and the second time corresponding to the upper surface reflection peak of the cable soft joint to be measured. The defect depth information is used to describe the distance between the defect and the upper surface of the cable soft joint.

[0011] In one embodiment, defect detection of a cable soft joint is performed based on each target time-domain spectral signal, including: determining imaging information of the cable soft joint to be measured according to each target time-domain spectral signal; and determining whether there is a defect in the cable soft joint according to the imaging information.

[0012] In one embodiment, determining imaging information of the cable soft joint to be measured according to each target time-domain spectral signal includes: for each scanning point, performing a Fourier transform on the target time-domain spectral signal of the scanning point to obtain signal information of the target time-domain spectral signal at different frequencies, where the signal information includes amplitude information and phase information; obtaining the target signal information corresponding to each scanning point at the target frequency; and determining the imaging information of the cable soft joint to be measured according to each target signal information.

[0013] In one embodiment, determining imaging information of the cable soft joint to be measured according to each target time-domain spectral signal includes: for each scanning point, determining the peak value and valley value of the target time-domain spectral signal of the scanning point, and calculating the peak-to-peak value by using the peak value and valley value to determine the peak-to-peak value corresponding to the scanning point; and determining the imaging information of the cable soft joint to be measured according to the peak-to-peak value corresponding to each scanning point and the position information of each scanning point.

[0014] In a second aspect, the present application further provides a cable soft joint defect detection device, including:

[0015] An acquisition module, which scans the cable soft joint to be measured according to a preset scanning step length and acquires the terahertz time-domain spectral signals of each scanning point in the cable soft joint to be measured;

[0016] A preprocessing module, which is used for preprocessing the terahertz time-domain spectral signals of each scanning point to obtain the target time-domain spectral signals corresponding to each scanning point, and the preprocessing includes detrending processing, filtering processing and smoothing processing;

[0017] A detection module, which is used for defect detection of the cable soft joint according to each target time-domain spectral signal.

[0018] In one embodiment, the device further includes a positioning module, which is used for if there is a defect in the cable soft joint, determining the defect time-domain spectral signal according to the defect position, where the defect time-domain spectral signal is the target time-domain spectral signal of the scanning point corresponding to the defect position; and determining the defect depth information according to the first time corresponding to the defect reflection peak in the defect time-domain spectral signal and the second time corresponding to the upper surface reflection peak of the cable soft joint to be measured, and the defect depth information is used to describe the distance between the defect and the upper surface of the cable soft joint.

[0019] In one embodiment, the detection module is specifically used for determining imaging information of the cable soft joint to be measured according to each target time-domain spectral signal; and determining whether there is a defect in the cable soft joint according to the imaging information.

[0020] In one embodiment, the detection module is specifically configured to, for each scanning point, perform Fourier transform on the target time-domain spectral signal of the scanning point to obtain signal information of the target time-domain spectral signal at different frequencies, where the signal information includes amplitude information and phase information; obtain the target signal information corresponding to each scanning point at the target frequency; and determine the imaging information of the cable soft joint to be measured according to each target signal information.

[0021] In one embodiment, the detection module is specifically configured to, for each scanning point, determine the peak value and the valley value of the target time-domain spectral signal of the scanning point, and calculate the peak-to-peak value by using the peak value and the valley value to determine the peak-to-peak value corresponding to the scanning point; and determine the imaging information of the cable soft joint to be measured according to the peak-to-peak value corresponding to each scanning point and the position information of each scanning point.

[0022] In a third aspect, the present application further provides a cable soft joint defect detection system, which includes a terahertz transmitter, a terahertz receiver, a stage, and a controller;

[0023] The terahertz transmitter is configured to generate a terahertz signal; the stage is configured to place the cable soft joint to be measured and move under the control of the controller so that the terahertz transmitter scans the cable soft joint to be measured; the terahertz receiver is configured to receive the terahertz time-domain spectral signal generated after the terahertz signal irradiates the cable soft joint to be measured, and send the terahertz time-domain spectral signal to the controller; the controller is configured to scan the cable soft joint to be measured according to a preset scanning step length, and obtain the terahertz time-domain spectral signal of each scanning point in the cable soft joint to be measured; perform preprocessing on the terahertz time-domain spectral signal of each scanning point to obtain the target time-domain spectral signal corresponding to each scanning point, where the preprocessing includes detrending processing, filtering processing, and smoothing processing; and perform defect detection on the cable soft joint according to each target time-domain spectral signal.

[0024] In a fourth aspect, the present application further provides a computer device, which includes a memory and a processor, the memory stores a computer program, and when the processor executes the computer program, the method described in any one of the first aspects above is implemented.

[0025] In a fifth aspect, the present application further provides a computer-readable storage medium, on which a computer program is stored, and when the computer program is executed by a processor, the method described in any one of the first aspects above is implemented.

[0026] In a sixth aspect, the present application further provides a computer program product, which includes a computer program, and when the computer program is executed by a processor, the method described in any one of the first aspects above is implemented.

[0027] The above-mentioned cable soft joint defect detection method, device, system, equipment, and storage medium scan the cable soft joint to be measured according to a preset scanning step length and obtain the terahertz time-domain spectral signals of each scanning point in the cable soft joint to be measured. Then, preprocess the terahertz time-domain spectral signals of each scanning point to obtain the target time-domain spectral signals corresponding to each scanning point. The preprocessing includes detrending, filtering, and smoothing. Finally, defect detection is performed on the cable soft joint according to each target time-domain spectral signal. Terahertz has a good penetration effect on dielectric materials. By scanning the cable soft joint to be measured, terahertz time-domain spectral signals can be obtained. After preprocessing the terahertz time-domain spectral signals, the stability and reliability of the signals can be improved, and the obtained signals can more accurately reflect the state of the cable soft joint to be measured. In this way, when defect detection is performed based on the preprocessed terahertz time-domain spectral signals, defects inside the cable soft joint near the interface area to be measured can be effectively detected, and the accuracy of detection can be improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] To more clearly illustrate the technical solutions in the embodiments of the present application or related technologies, the following will briefly introduce the drawings required for use in the description of the embodiments of the present application or related technologies. Obviously, the drawings in the following description are only some embodiments of the present application. For those of ordinary skill in the art, other related drawings can be obtained based on these drawings without creative efforts.

[0029] Figure 1 Schematic diagram of the structure of a cable soft joint in one embodiment;

[0030] Figure 2 Application environment diagram of the cable soft joint defect detection method in one embodiment;

[0031] Figure 3 Flow chart of the cable soft joint defect detection method in one embodiment;

[0032] Figure 4 Schematic diagram of the pencil tip structure of a cable soft joint in one embodiment;

[0033] Figure 5 Schematic diagram of terahertz signal passing through an air gap defect in one embodiment;

[0034] Figure 6 Comparison diagram of reflected signals of terahertz signals passing through areas with and without metal defects in one embodiment;

[0035] Figure 7 Comparison diagram of terahertz time-domain spectral signals of one scanning point in one embodiment;

[0036] Figure 8Terahertz time-domain spectroscopy signal comparison diagram of a scanning point in another embodiment;

[0037] Figure 9 Schematic flow diagram of the cable soft joint defect detection method in another embodiment;

[0038] Figure 10 Schematic flow diagram of the steps for detecting defects in a cable soft joint in one embodiment;

[0039] Figure 11 Cable soft joint imaging result in another embodiment;

[0040] Figure 12 Schematic flow diagram of the cable soft joint defect detection method in another embodiment;

[0041] Figure 13 Cable soft joint imaging result without defects in one embodiment;

[0042] Figure 14 Cable soft joint imaging result with surface copper powder defects in one embodiment;

[0043] Figure 15 Cable soft joint imaging result with internal copper powder defects in one embodiment;

[0044] Figure 16 Cable soft joint imaging result with internal inner screen material powder defects in one embodiment;

[0045] Figure 17 Cable soft joint imaging result with bubble defects in one embodiment;

[0046] Figure 18 Structural block diagram of the cable soft joint defect detection device in one embodiment;

[0047] Figure 19 Internal structure diagram of a computer device in one embodiment. Detailed implementation manners

[0048] In order to make the objectives, technical solutions and advantages of the present application clearer, the present application will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0049] For the construction of power grid interconnection projects between coastal islands and the mainland, offshore wind power stations, nuclear power plants, and drilling platforms, the demand for high-voltage submarine cables with long lengths is becoming increasingly urgent. Due to limitations in cable manufacturing and transportation, etc., the length of a single produced cable is insufficient to meet the application requirements. Therefore, cable soft joints are needed to connect the cables to achieve the required length. The reliability of the quality of cable soft joints is the key to the normal and reliable operation of the entire submarine cable power transmission system. To ensure the quality of soft joints, it is very necessary to detect the insulation defects of soft joints.

[0050] As Figure 1 shown, it is a schematic structural diagram of a cable soft joint, including: a first cable 10, a second cable 11, a cable soft joint 12, and pencil tips 13 located on both sides of the cable soft joint 12. In the production process of the soft joint, it is necessary to first remove the original armor and insulation structures of the cable, expose the conductor for welding, then wind a semi-conductive inner shielding tape on the exposed conductor, and then restore the cross-linked polyethylene insulation by extrusion. Finally, restore the outer shielding, armor, sheath and other structures. In the production process of the soft joint, the most important process is the restoration of the cable insulation layer. How to prepare and restore the insulation after the inner shielding is completed so that it matches well with the body insulation is the key to the success of the entire soft joint. Before restoring the insulation, to ensure that the outer diameters of the conductor and the semi-conductive shielding tape are the same and the surfaces are smooth without burrs, it is necessary to polish the conductor and the semi-conductive shielding tape respectively to avoid the occurrence of too high local field strength. During this process, residual metal particles, semi-conductive particles, and dust in the air may remain near the pencil tip during the casting process, forming defects at the interface between the body and the restored insulation; incomplete degassing or abnormal bonding between the body and the restored insulation may also lead to the existence of air gaps at the interface. These defects will ultimately cause the insulation of the soft joint to fail during operation. Therefore, the interface between the body and the restored insulation at the pencil tip of the soft joint often becomes a weak point where stress and electric field are concentrated in the soft joint structure. And it is of great significance to have means that can locate the interface area and detect defects around the interface.

[0051] In the prior art, the cable soft joint is observed through a scanning electron microscope. However, this method is difficult to detect internal defects of the cable soft joint while locating the interface area, and there are inaccurate defect detection situations.

[0052] In view of this, the present application provides a cable soft joint defect detection method that can accurately detect the defects of cable soft joints. The cable soft joint defect detection method provided by the embodiments of the present application can be used for such as Figure 2In the application environment shown. Among them, the cable soft joint defect detection system 20 includes a terahertz transmitter 201, a terahertz receiver 202, a stage 203, and a controller 204; the terahertz transmitter 201 is used to generate terahertz signals; the stage 202 is used to place the cable soft joint to be tested and move under the control of the controller 204 so that the terahertz transmitter 201 scans the cable soft joint to be tested; the terahertz receiver 203 is used to receive the terahertz time-domain spectral signals generated after the terahertz signals irradiate the cable soft joint to be tested, and send the terahertz time-domain spectral signals to the controller 204; the controller 204 is used to scan the cable soft joint to be tested according to a preset scanning step size and obtain the terahertz time-domain spectral signals of each scanning point in the cable soft joint to be tested; preprocess the terahertz time-domain spectral signals of each scanning point to obtain the target time-domain spectral signals corresponding to each scanning point, and the preprocessing includes detrending processing, filtering processing, and smoothing processing; perform defect detection on the cable soft joint according to each target time-domain spectral signal. The controller in the embodiment of the present application may be a computer device. Among them, the computer device may be a server or a computer, and the embodiment of the present application does not limit the specific type of the computer device.

[0053] In an exemplary embodiment, as Figure 3 shown, a method for detecting defects in a cable soft joint is provided, including the following steps 301 to 303. Among them:

[0054] Step 301, scan the cable soft joint to be tested according to a preset scanning step size, and obtain the terahertz time-domain spectral signals of each scanning point in the cable soft joint to be tested.

[0055] Optionally, the cable soft joint to be tested may be a sliced specimen at the pencil tip of the soft joint. Exemplarily, any one of the pencil tip structures 13 in Figure 1 can be taken and horizontally cut along the axial direction of the cable to obtain the cable soft joint to be tested. As Figure 4 shown, the thickness of the cable soft joint to be tested can be within 5 mm. The left side of the dotted line is the body insulation of the cable, the right side of the dotted line is the restored insulation, and the dotted line is the interface between the body and the restored insulation, and this interface area has a certain width.

[0056] Optionally, the cable soft joint to be tested can be horizontally placed in the stage, and the terahertz transmitter emits terahertz signals and irradiates the cable soft joint to be tested; when scanning the cable soft joint to be tested according to a preset scanning step size, the position of the stage can be controlled and adjusted so that the cable soft joint to be tested is located at the focus of the terahertz signal beam, and the terahertz receiver receives the reflected or transmitted signals of the cable soft joint to be tested, that is, the terahertz time-domain spectral signals, and sends the terahertz time-domain spectral signals to the controller.

[0057] Exemplarily, if there is an air gap inside the cable soft joint, there will be two additional interfaces, namely the medium-air interface and the air-medium interface. Terahertz waves will be reflected and transmitted at the two interfaces on the upper and lower surfaces of the air respectively, reducing the amplitude of the transmitted wave signal and increasing the number of reflected wave signals. At the same time, due to the different refractive indices of air and the medium, the transmitted and reflected signals at the air gap will have optical path differences compared to the signals without an air gap, resulting in a phase difference in the received signals. Semi-conductive and metallic materials will cause partial and total reflection of terahertz signals, reducing the amplitude of the received signals. Figure 5 Schematic diagram of terahertz signal passing through an air gap defect Figure 6 Comparison diagram of reflected signals of terahertz signals passing through areas with and without metal defects. 601 is the reflected signal of the defective area, and 602 is the reflected signal of the defect-free area.

[0058] Step 302: Preprocess the terahertz time-domain spectral signals of each scanning point to obtain the target time-domain spectral signals corresponding to each scanning point. The preprocessing includes detrending, filtering, and smoothing.

[0059] Optionally, since the defect sizes introduced into the cable soft joint during the injection molding process are often small (less than 500 μm), the responses generated during the detection are relatively small, and the defective reflection peaks are easily submerged by noise.

[0060] Optionally, the influence of noise can be removed by preprocessing the terahertz time-domain spectral signals of each scanning point, making it less likely for the defective reflection peaks to be submerged.

[0061] Optionally, detrending can remove the trend components in the terahertz time-domain spectral signals and can be achieved by methods such as linear detrending, moving average detrending, wavelet detrending, or high-pass filter detrending. Filtering can selectively retain or suppress specific frequency components to extract useful signals or remove noise. Smoothing also removes high-frequency noise or fluctuations and retains the overall trend of the terahertz time-domain spectral signals. Preprocessing can also be performed by subtracting the average value of the image range signal, which can remove the DC component of the terahertz time-domain spectral signals and highlight the fluctuating or changing parts of the terahertz time-domain spectral signals.

[0062] Exemplarily, as Figure 7 shown, it is a comparison diagram of terahertz time-domain spectral signals of a scanning point in the cable soft joint to be measured, including the signal 701 when there is a spherical copper powder defect with a diameter of 445 microns and the signal 702 at the defect-free location. The reflection peaks on the upper and lower surfaces of the cable soft joint to be measured are relatively obvious. However, when intercepting the signals between the reflection peaks on the upper and lower surfaces (the area where the black circle is located in the figure), the reflection peaks generated by the signals when there is a defect are not obvious. After preprocessing operations, as Figure 8As shown, the reflection peak of the signal 801 at the defective location can be clearly observed, and 802 is the signal at the defect-free location.

[0063] Step 203, perform defect detection on the cable soft joint according to each target time-domain spectral signal.

[0064] In a possible implementation manner, since the reflection peak at the defective location can be observed from the target time-domain spectral signal, therefore, by comparing the target time-domain spectral signal with the signal at the defect-free location, it is possible to determine whether there is a defect according to the comparison result.

[0065] In another possible implementation manner, imaging can be performed through the target time-domain spectral signal, and defect detection can be performed according to the imaging result.

[0066] In another possible implementation manner, the target time-domain spectral signal can be input into a pre-trained neural network model, and defect detection can be performed according to the output result of the pre-trained neural network model. The neural network model can be trained according to the historical time-domain spectral signal and the corresponding defect detection results.

[0067] The above cable soft joint defect detection method scans the cable soft joint to be measured according to a preset scanning step length and obtains the terahertz time-domain spectral signals of each scanning point in the cable soft joint to be measured; then, preprocesses the terahertz time-domain spectral signals of each scanning point to obtain the target time-domain spectral signals corresponding to each scanning point. The preprocessing includes detrending processing, filtering processing, and smoothing processing; finally, performs defect detection on the cable soft joint according to each target time-domain spectral signal. Terahertz has a good penetration effect on dielectric materials. By scanning the cable soft joint to be measured, terahertz time-domain spectral signals can be obtained. After preprocessing the terahertz time-domain spectral signals, the stability and reliability of the signals can be improved, and the obtained signals can more accurately reflect the state of the cable soft joint to be measured. In this way, when performing defect detection based on the preprocessed terahertz time-domain spectral signals, the accuracy of the detection can be improved. At the same time, when detecting the cable soft joint to be measured based on terahertz waves, non-destructive detection can be achieved.

[0068] In an exemplary embodiment, as Figure 9 shown, optionally, the method further includes the following steps 901 to 902. Wherein:

[0069] Step 901, if there is a defect in the cable soft joint, determine the defect time-domain spectral signal according to the defect location. The defect time-domain spectral signal is the target time-domain spectral signal of the scanning point corresponding to the defect location.

[0070] Optionally, when it is determined that the cable soft joint has a defect, the corresponding scanning point can be determined according to the defect position. It can be understood that the defect position can be the position where the defect is located in the direction parallel to the axial direction of the cable. Then, the target time-domain spectral signal of the corresponding scanning point is used as the defect time-domain spectral signal.

[0071] Step 902, determine the defect depth information according to the first time corresponding to the defect reflection peak in the defect time-domain spectral signal and the second time corresponding to the upper surface reflection peak of the cable soft joint to be measured.

[0072] Among them, the defect depth information is used to describe the distance between the defect and the upper surface of the cable soft joint.

[0073] Optionally, it can be understood that the second time corresponding to the upper surface reflection peak of the cable soft joint to be measured is earlier than the first time corresponding to the defect reflection peak.

[0074] Optionally, the defect depth can be determined according to the first time and the second time through the following formula:

[0075]

[0076] Among them, d is the defect depth, is the propagation speed of light in the cable insulation layer, is the difference between the first time and the second time.

[0077] Exemplarily, taking Figure 6 the terahertz time-domain spectral signal in as an example, the flight time of the defect reflection peak is about 19.9 ps. The flight time of the upper surface of the specimen is 8.6 ps (i.e., the second time), and the refractive index of cross-linked polyethylene is about 1.52. From this, the depth of the defect from the upper surface can be calculated to be 1.11 mm.

[0078] If the cable soft joint has a defect as described above, then the defect time-domain spectral signal is determined according to the defect position. The defect time-domain spectral signal is the target time-domain spectral signal of the scanning point corresponding to the defect position. The defect depth information is determined according to the first time corresponding to the defect reflection peak in the defect time-domain spectral signal and the second time corresponding to the upper surface reflection peak of the cable soft joint to be measured, which can accurately locate the defect when there is a defect.

[0079] In an exemplary embodiment, as Figure 10 shown, optionally, detecting the defects of the cable soft joint according to each target time-domain spectral signal includes the following steps 1001 to 1002. Among them:

[0080] Step 1001, determine the imaging information of the cable soft joint to be measured according to each target time-domain spectral signal.

[0081] In a possible implementation manner, determining the imaging information of the cable soft joint to be measured according to each target time-domain spectral signal may include: for each scanning point, performing a Fourier transform on the target time-domain spectral signal of the scanning point to obtain signal information of the target time-domain spectral signal at different frequencies, where the signal information includes amplitude information and phase information; obtaining the target signal information corresponding to each scanning point at the target frequency; and determining the imaging information of the cable soft joint to be measured according to each target signal information.

[0082] Optionally, the target frequency may be a preset fixed frequency. Selecting a specific fixed frequency from the terahertz time-domain spectral signal can utilize the unique response of the terahertz wave at this frequency when interacting with the cable soft joint to be measured. Different structures, states, etc. of the cable soft joint to be measured have differences in the absorption, scattering, transmission, etc. characteristics of the terahertz wave at different frequencies. Therefore, an image can be generated based on the changes in characteristics such as the intensity and phase of the terahertz time-domain spectral signal of each scanning point at this specific frequency.

[0083] In another possible implementation manner, determining the imaging information of the cable soft joint to be measured according to each target time-domain spectral signal may include: for each scanning point, determining the peak value and valley value of the target time-domain spectral signal of the scanning point, and calculating the peak-to-peak value by determining the peak value and valley value; and determining the imaging information of the cable soft joint to be measured according to the peak-to-peak value corresponding to each scanning point and the position information of each scanning point.

[0084] Optionally, the peak-to-peak value can be obtained by finding the maximum value and minimum value of the target time-domain spectral signal of the scanning point and calculating their difference, and mapping the calculated peak-to-peak value to the pixels of the image according to the position information of the scanning points. Usually, the area with a larger peak-to-peak value will be displayed as brighter or pixels with a specific color in the image, while the area with a smaller peak-to-peak value will be displayed as darker or pixels with a different color, thus forming a peak-to-peak value image.

[0085] It can be understood that the maximum value and minimum value can be the entire target time-domain spectral signal, or the signal intercepted between the reflection peaks on the upper and lower surfaces. The embodiments of the present application do not limit this.

[0086] In another possible implementation manner, the imaging information of the cable soft joint to be measured can also be determined based on the time-slice imaging method. Select a fixed time, and obtain the amplitude of the target time-domain spectral signal of each scanning point at the fixed time. Determine the imaging information of the cable soft joint to be measured according to the amplitude and the position information of each scanning point.

[0087] Step 1002, determining whether there are defects in the cable soft joint according to the imaging information.

[0088] Optionally, it is possible to determine whether there are defects in the cable soft joint from the imaging information through image processing, and mark the location of the defects. For example, the imaging information can be grayscale processed, and a suitable threshold determination method (such as the global threshold method or other methods) can be selected to determine the threshold. Then, the image is segmented according to the determined threshold, and the pixels with grayscale values greater than or less than the threshold are marked as possible defect regions.

[0089] Optionally, it is also possible to determine whether there are defects in the cable soft joint based on deep learning methods. A large number of terahertz imaging results can be collected as training data, including normal images and images containing various defects, and the images are labeled to mark the location and type of the defects. Then, a suitable neural network model is constructed, and the model is trained using the labeled data. The weight parameters of the network are updated through the backpropagation algorithm to enable the neural network model to accurately identify defect features. After training is completed, the imaging information can be input into the neural network model, and whether there are defects and the location of the defects can be determined according to the output results.

[0090] Optionally, during the actual use process, stress is introduced into the cable soft joint to be measured during the process of hot pressing and laminating the cable soft joint to be measured with the laboratory laminations, resulting in warping of the cable soft joint to be measured in its natural state. Even if external force is intentionally applied, it is impossible to avoid the problem of uneven air gap thickness between the cable soft joint to be measured and the stage during detection. The imaging information can be determined by means of fixed-frequency imaging. Figure 11 As the imaging result, it can be seen that the contrast between the defective and non-defective areas increases, and the influence of warping on imaging is small. Multiple defects can be observed from the figure, and the defects at the warped areas (the positions where the circles are located in the figure) can also be clearly observed.

[0091] By determining the imaging information of the cable soft joint to be measured according to the respective target time-domain spectral signals and determining whether there are defects in the cable soft joint based on the imaging information, the defect detection of the cable soft joint can be intuitively and accurately performed.

[0092] As an optional implementation manner, as Figure 12 shown, the cable soft joint defect detection method provided in the embodiments of the present application may include the following specific steps:

[0093] Step 1201, scan the cable soft joint to be measured according to a preset scanning step length, and obtain the terahertz time-domain spectral signals of each scanning point in the cable soft joint to be measured.

[0094] Step 1202, preprocess the terahertz time-domain spectral signals of each scanning point to obtain the corresponding target time-domain spectral signals of each scanning point. The preprocessing includes detrending processing, filtering processing, and smoothing processing.

[0095] Step 1203: For each scanning point, perform Fourier transform on the target time-domain spectral signal of the scanning point to obtain the signal information of the target time-domain spectral signal at different frequencies.

[0096] Among them, the signal information includes amplitude information and phase information.

[0097] Step 1204: Obtain the target signal information corresponding to each scanning point at the target frequency.

[0098] Step 1205: Determine the imaging information of the cable soft joint to be measured according to each target signal information.

[0099] Step 1206: Determine whether there is a defect in the cable soft joint according to the imaging information.

[0100] Step 1207: If there is a defect in the cable soft joint, determine the defect time-domain spectral signal according to the defect position.

[0101] Among them, the defect time-domain spectral signal is the target time-domain spectral signal of the scanning point corresponding to the defect position.

[0102] Step 1208: Determine the defect depth information according to the first time corresponding to the defect reflection peak in the defect time-domain spectral signal and the second time corresponding to the upper surface reflection peak of the cable soft joint to be measured.

[0103] Among them, the defect depth information is used to describe the distance between the defect and the upper surface of the cable soft joint.

[0104] As another alternative implementation manner, the steps of determining the imaging information in steps 1203 to 1205 can also be replaced by the following method: For each scanning point, determine the peak value and valley value of the target time-domain spectral signal of the scanning point, and calculate the peak-to-peak value by the peak value and valley value to determine the peak-to-peak value corresponding to the scanning point; according to the peak-to-peak value corresponding to each scanning point and the position information of each scanning point, determine the imaging information of the cable soft joint to be measured.

[0105] Exemplarily, the pencil tip parallel axial slice and the transmission imaging results of the body-recovery interface without defects are as Figure 13 shown; after sprinkling copper powder and inner screen powder obtained by sanding on the surface of the cable soft joint to be measured, the obtained imaging results are as Figure 14 shown. By comparing the imaging results with the actual situation, the accuracy of the cable soft joint defect detection method in the embodiments of the present application can be determined; a copper powder defect is added between the cross-linked polyethylene test piece and the low-density polyethylene test piece, and the two thin slices are pressed together using a flat vulcanizer for preheating, vulcanization, and cooling to obtain a cable soft joint to be measured containing a copper powder defect, and its imaging results are as Figure 15As shown in the figure; add the powder of the inner screen material obtained by sandpaper polishing between the cross-linked polyethylene test piece and the low-density polyethylene test piece, and use a flat vulcanizer to press the two thin pieces together for preheating, vulcanization, and cooling to obtain a cable soft joint to be tested containing inner screen powder defects, and its imaging result is as Figure 16 shown; the flat vulcanizer presses the cross-linked polyethylene test piece and the low-density polyethylene test piece together for preheating, vulcanization, and cooling. During the vulcanization process, the pressure is repeatedly removed and applied several times to allow a small amount of air to enter between the two thin pieces, obtaining a cable soft joint to be tested containing bubble defects, and its imaging result is as Figure 17 shown.

[0106] It should be understood that although the steps in the flowcharts involved in the above-described embodiments are sequentially shown according to the indications of the arrows, these steps are not necessarily executed in the order indicated by the arrows. Unless there is a clear description in this article, the execution of these steps has no strict order limit, and these steps can be executed in other orders. Moreover, at least a part of the steps in the flowcharts involved in the above-described embodiments may include multiple steps or multiple stages. These steps or stages are not necessarily executed at the same time, but can be executed at different times. The execution order of these steps or stages is not necessarily sequential, but can be executed alternately or alternately with at least a part of other steps or steps or stages in other steps.

[0107] Based on the same inventive concept, the embodiments of the present application also provide a cable soft joint defect detection device for implementing the cable soft joint defect detection method involved above. The implementation solutions provided by this device to solve problems are similar to the implementation solutions described in the above method. Therefore, the specific limitations in one or more embodiments of the cable soft joint defect detection device provided below can refer to the limitations on the cable soft joint defect detection method in the above text, and will not be repeated here.

[0108] In an exemplary embodiment, as Figure 18 shown, a cable soft joint defect detection device 1800 is provided, including: an acquisition module 1801, a preprocessing module 1802, and a detection module 1803, where:

[0109] The acquisition module 1801 scans the cable soft joint to be tested according to a preset scanning step size, and acquires the terahertz time-domain spectral signals of each scanning point in the cable soft joint to be tested.

[0110] The preprocessing module 1802 is used to preprocess the terahertz time-domain spectral signals of each scanning point to obtain the target time-domain spectral signals corresponding to each scanning point. The preprocessing includes detrending processing, filtering processing, and smoothing processing.

[0111] The detection module 1803 is configured to perform defect detection on the cable soft joint according to each target time-domain spectral signal.

[0112] In an exemplary embodiment, the device further includes a positioning module. If there is a defect in the cable soft joint, the positioning module is configured to determine a defect time-domain spectral signal according to the defect position, where the defect time-domain spectral signal is the target time-domain spectral signal of the scanning point corresponding to the defect position; and determine defect depth information according to the first time corresponding to the defect reflection peak and the second time corresponding to the upper surface reflection peak of the cable soft joint to be measured, where the defect depth information is used to describe the distance between the defect and the upper surface of the cable soft joint.

[0113] In an exemplary embodiment, the detection module 1803 is specifically configured to determine imaging information of the cable soft joint to be measured according to each target time-domain spectral signal; and determine whether there is a defect in the cable soft joint according to the imaging information.

[0114] In an exemplary embodiment, the detection module 1803 is specifically configured to, for each scanning point, perform a Fourier transform on the target time-domain spectral signal of the scanning point to obtain signal information of the target time-domain spectral signal at different frequencies, where the signal information includes amplitude information and phase information; obtain the target signal information corresponding to each scanning point at the target frequency; and determine imaging information of the cable soft joint to be measured according to each target signal information.

[0115] In an exemplary embodiment, the detection module 1803 is specifically configured to, for each scanning point, determine the peak value and valley value of the target time-domain spectral signal of the scanning point, and calculate the peak-to-peak value by using the peak value and valley value to determine the peak-to-peak value corresponding to the scanning point; and determine imaging information of the cable soft joint to be measured according to the peak-to-peak value corresponding to each scanning point and the position information of each scanning point.

[0116] Each module in the above cable soft joint defect detection device can be implemented in whole or in part by software, hardware, and their combination. The above modules can be embedded in the processor in the computer device in the form of hardware or be independent of the processor, or can be stored in the memory in the computer device in the form of software, so as to facilitate the processor to call and execute the operations corresponding to the above modules.

[0117] Based on the same inventive concept, an embodiment of the present application further provides a cable soft joint defect detection system for implementing the cable soft joint defect detection method involved above. The implementation solution provided by the system to solve the problem is similar to the implementation solution recorded in the above method. Therefore, the specific limitations in one or more embodiments of the cable soft joint defect detection system provided below can refer to the limitations on the cable soft joint defect detection method in the above text, and will not be repeated here. The cable soft joint defect detection system can refer to Figure 2, the cable soft joint defect detection system 20 includes a terahertz transmitter 201, a terahertz receiver 202, a stage 203, and a controller 204; the terahertz transmitter 201 is used to generate terahertz signals; the stage 202 is used to place the cable soft joint to be tested and move under the control of the controller 204 so that the terahertz transmitter 201 scans the cable soft joint to be tested; the terahertz receiver 203 is used to receive the terahertz time-domain spectral signals generated after the terahertz signals irradiate the cable soft joint to be tested and send the terahertz time-domain spectral signals to the controller 204; the controller 204 is used to scan the cable soft joint to be tested according to a preset scanning step size and obtain the terahertz time-domain spectral signals of each scanning point in the cable soft joint to be tested; preprocess the terahertz time-domain spectral signals of each scanning point to obtain the target time-domain spectral signals corresponding to each scanning point, and the preprocessing includes detrending processing, filtering processing, and smoothing processing; detect defects in the cable soft joint according to the target time-domain spectral signals of each scanning point.

[0118] In an exemplary embodiment, a computer device is provided. The computer device may be a computer, and its internal structure diagram may be as Figure 19 shown. The computer device includes a processor, a memory, an input / output interface, a communication interface, a display unit, and an input device. Among them, the processor, the memory, and the input / output interface are connected through a system bus, and the communication interface, the display unit, and the input device are connected to the system bus through the input / output interface. Among them, the processor of the computer device is used to provide computing and control capabilities. The memory of the computer device includes a non-volatile storage medium and an internal memory. The non-volatile storage medium stores an operating system and a computer program. The internal memory provides an environment for the operation of the operating system and the computer program in the non-volatile storage medium. The input / output interface of the computer device is used to exchange information between the processor and external devices. The communication interface of the computer device is used to communicate with external terminals in a wired or wireless manner, and the wireless manner can be implemented through WIFI, a mobile cellular network, near field communication (NFC), or other technologies. When the computer program is executed by the processor, it implements a method for detecting defects in a cable soft joint. The display unit of the computer device is used to form a visually visible picture, which may be a display screen, a projection device, or a virtual reality imaging device. The display screen may be a liquid crystal display screen or an electronic ink display screen. The input device of the computer device may be a touch layer covering the display screen, or a button, a trackball, or a touchpad provided on the housing of the computer device, or an external keyboard, touchpad, or mouse, etc.

[0119] Those skilled in the art can understand that Figure 19The structure shown is only a block diagram of some structures related to the solution of this application, and does not constitute a limitation on the computer device to which the solution of this application is applied. The specific computer device may include more or fewer components than those shown in the figure, or combine some components, or have different component arrangements.

[0120] In an exemplary embodiment, a computer device is provided, including a memory and a processor. A computer program is stored in the memory, and when the processor executes the computer program, the steps described in any one of the above method embodiments are implemented.

[0121] In an exemplary embodiment, a computer-readable storage medium is provided, on which a computer program is stored. When the computer program is executed by a processor, the steps described in any one of the above method embodiments are implemented.

[0122] In an exemplary embodiment, a computer program product is provided, including a computer program. When the computer program is executed by a processor, the steps described in any one of the above method embodiments are implemented.

[0123] Those of ordinary skill in the art can understand that all or part of the processes in the methods of the above embodiments can be completed by instructing relevant hardware through a computer program. The computer program can be stored in a non-volatile computer-readable storage medium. When the computer program is executed, it can include the processes of the embodiments of the above methods. Among them, any reference to a memory, database, or other medium used in the embodiments provided in the present application can include at least one of non-volatile memory and volatile memory. Non-volatile memory can include read-only memory (ROM), magnetic tape, floppy disk, flash memory, optical memory, high-density embedded non-volatile memory, resistive random access memory (ReRAM), magnetoresistive random access memory (MRAM), ferroelectric random access memory (FRAM), phase change memory (PCM), graphene memory, etc. Volatile memory can include random access memory (RAM) or external cache memory, etc. By way of illustration and not limitation, RAM can be in various forms, such as static random access memory (SRAM) or dynamic random access memory (DRAM), etc. The databases involved in the embodiments provided in the present application can include at least one of relational databases and non-relational databases. Non-relational databases can include distributed databases based on blockchain, etc., without limitation. The processors involved in the embodiments provided in the present application can be general-purpose processors, central processing units, graphics processing units, digital signal processors, programmable logic devices, data processing logics based on quantum computing, artificial intelligence (AI) processors, etc., without limitation.

[0124] The technical features of the above embodiments can be combined arbitrarily. For the sake of brevity of description, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, it should be considered to be within the scope recorded in the present application.

[0125] The above-described embodiments merely represent several implementation manners of the present application. The description thereof is relatively specific and detailed, but it should not be construed as a limitation to the patent scope of the present application. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present application, several modifications and improvements can still be made, and these all fall within the protection scope of the present application. Therefore, the protection scope of the present application shall be subject to the appended claims.

Claims

1. A method for detecting defects in cable flexible joints, characterized in that: The method comprises: Scanning the cable flexible joint to be tested according to a preset scanning step length, and acquiring a terahertz time-domain spectrum signal of each scanning point in the cable flexible joint to be tested; Preprocessing the terahertz time-domain spectrum signal of each scanning point to obtain a target time-domain spectrum signal corresponding to each scanning point, wherein the preprocessing includes detrending processing, filtering processing and smoothing processing; Defect detection is performed on the cable flexible joint according to each of the target time domain spectrum signals.

2. The method according to claim 1, characterized in that The method further comprises: If there is a defect in the cable flexible joint, a defect time domain spectrum signal is determined according to the defect position, and the defect time domain spectrum signal is a target time domain spectrum signal of a scanning point corresponding to the defect position; Defect depth information is determined based on a first time corresponding to a defect reflection peak in the defect time domain spectrum signal and a second time corresponding to an upper surface reflection peak of the tested cable flexible joint, wherein the defect depth information is used to describe the distance between the defect and the upper surface of the cable flexible joint.

3. The method according to claim 1, characterized in that: The detecting defects of the cable flexible joint according to each of the target time domain spectrum signals comprises: Determine the imaging information of the cable flexible joint to be tested according to each of the target time-domain spectral signals; Determine whether the cable flexible joint has defects based on the imaging information.

4. The method according to claim 3, characterized in that: Determining the imaging information of the cable flexible joint to be tested according to each of the target time-domain spectral signals includes: For each scanning point, performing Fourier transformation on the target time-domain spectrum signal of the scanning point to obtain signal information of the target time-domain spectrum signal at different frequencies, wherein the signal information includes amplitude information and phase information; Obtaining target signal information corresponding to each of the scanning points at the target frequency; The imaging information of the cable flexible joint to be tested is determined according to each of the target signal information.

5. The method according to claim 3, characterized in that: Determining the imaging information of the cable flexible joint to be tested according to each of the target time-domain spectral signals includes: For each scanning point, determining the peak value and valley value of the target time domain spectrum signal of the scanning point, and calculating the peak value and valley value to determine the peak-to-peak value corresponding to the scanning point; The imaging information of the cable flexible joint to be tested is determined according to the peak-to-peak value corresponding to each scanning point and the position information of each scanning point.

6. A cable flexible joint defect detection device, characterized in that: The device comprises: An acquisition module scans the cable flexible joint to be tested according to a preset scanning step length, and obtains a terahertz time-domain spectrum signal of each scanning point in the cable flexible joint to be tested; A preprocessing module, used for preprocessing the terahertz time-domain spectrum signal of each scanning point to obtain a target time-domain spectrum signal corresponding to each scanning point, wherein the preprocessing includes detrending processing, filtering processing and smoothing processing; A detection module is used to perform defect detection on the cable flexible joint according to each of the target time domain spectrum signals.

7. A cable flexible joint defect detection system, characterized in that: The cable flexible joint defect detection system comprises a terahertz transmitter, a terahertz receiver, a stage and a controller; The terahertz transmitter is used to generate a terahertz signal; The stage is used to place the cable flexible joint to be tested, and moves under the control of the controller so that the terahertz transmitter scans the cable flexible joint to be tested; The terahertz receiver is used to receive a terahertz time-domain spectrum signal generated after the terahertz signal is irradiated onto the flexible joint of the cable to be tested, and send the terahertz time-domain spectrum signal to a controller; The controller is used to scan the cable flexible joint to be tested according to a preset scanning step length, and obtain the terahertz time-domain spectrum signal of each scanning point in the cable flexible joint to be tested; pre-process the terahertz time-domain spectrum signal of each scanning point to obtain the target time-domain spectrum signal corresponding to each scanning point, and the pre-processing includes detrending processing, filtering processing and smoothing processing; Defect detection is performed on the cable flexible joint according to each of the target time domain spectrum signals.

8. A computer device comprising a memory and a processor, wherein the memory stores a computer program, wherein: When the processor executes the computer program, the steps of the method according to any one of claims 1 to 5 are implemented.

9. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the steps of the method according to any one of claims 1 to 5 are implemented.

10. A computer program product, comprising a computer program, characterized in that When the computer program is executed by a processor, the steps of the method according to any one of claims 1 to 5 are implemented.

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