Terahertz detection method for vehicle-mounted cable terminal

Abstract

The invention relates to the technical field of vehicle-mounted cable terminals, and discloses a terahertz detection method for a vehicle-mounted cable terminal, which comprises the following steps: step 1), a detection area is selected, a terahertz transceiving antenna array unit is adjusted, and a host comprises a reflective terahertz time-domain spectroscopy system for generating terahertz waves and receiving fed-back terahertz waves; (2) the positions of the mechanical arm and the terahertz receiving and transmitting antenna array unit are adjusted, and scanning detection is started; (3) after scanning detection is completed, the terahertz signals are processed, and terahertz time-frequency domain information and an imaging result are obtained; step 4), judging whether defects exist in scanning detection at the present stage or not; if no defect exists, whether the vehicle-mounted cable terminal at the present stage exceeds an aging state threshold value or not is judged; if the defect exists, marking the coordinate of a defect area, and performing segmentation processing on the image of the defect area; and step 5), repeating the step 2) to the step 4) until terahertz detection of the vehicle-mounted cable terminal is completed.

Description

Technical Field

[0001] The patent of this invention relates to the technical field of vehicle-mounted cable terminals, and specifically, to a terahertz detection method for vehicle-mounted cable terminals. Background Art

[0002] Onboard cables are the key carriers for energy supply and transmission in EMU trains, playing a vital role in the safe and stable operation of the power supply system. Among them, onboard cable terminals, as a key component of onboard cables, are a weak link due to their complex structure.

[0003] my country is a vast country with significant regional climate differences and complex and diverse environmental conditions. Exposed onboard cable terminals are highly susceptible to harsh environmental conditions. Furthermore, the complex assembly process for onboard cable terminals, influenced by the on-site construction environment and the technical level of the construction personnel, can easily lead to problems such as scratches on the internal insulation surface, residual conductive metal particles, insufficient pressure at the interface connection, and improper electric field margin design.

[0004] These issues can easily lead to internal defects in onboard cable terminals, which, under high field strength, can cause partial discharges. Furthermore, as onboard cable terminals operate in extremely complex environments over extended periods, these internal defects can gradually expand and worsen, ultimately causing them to break down or explode, severely impacting the normal operation of EMU trains.

[0005] Existing methods for inspecting onboard cable terminals primarily include partial discharge, reflectometry, ultraviolet (UV), infrared, X-ray, and acoustic emission. While widely used, these methods still suffer from limitations such as insufficient accuracy, susceptibility to external interference, and the destructive nature of some methods, making it difficult to comprehensively and accurately assess the operating status of onboard cable terminals. Summary of the Invention

[0006] The present invention aims to provide a terahertz detection method for vehicle-mounted cable terminals, aiming to solve the problem of insufficient detection accuracy in the prior art detection method for vehicle-mounted cable terminals.

[0007] The present invention is implemented as follows: a terahertz detection method for a vehicle-mounted cable terminal comprises the following steps:

[0008] Step 1) Select the detection area of ​​the vehicle cable terminal to be detected, adjust the initial scanning position of the terahertz transceiver antenna array unit, and start the host, wherein the host includes a reflective terahertz time-domain spectroscopy system for generating terahertz waves and receiving feedback terahertz waves, and the transceiver antenna of the reflective terahertz time-domain spectroscopy system is a probe arranged on the terahertz transceiver antenna array unit, and the terahertz transceiver antenna array unit is arranged on the robotic arm;

[0009] Step 2) adjusting the position of the robotic arm and the terahertz transceiver antenna array unit through the feature points captured by the camera and the feedback of the angle sensor until the probe is adjusted to the set position and then starting the scanning detection;

[0010] Step 3), after the scanning detection is completed, the terahertz signal collected by the reflective terahertz time-domain spectroscopy system is processed to obtain the filtered terahertz time-frequency domain information of the detection area of ​​the vehicle-mounted mobile terminal, as well as the imaging result after super-resolution reconstruction and edge extraction optimization;

[0011] Step 4) Determine whether there are any defects in the current scanning test;

[0012] If there are no defects, determine whether the current vehicle cable terminal exceeds the aging state threshold. If so, mark the coordinates of the detection area and store the information of the detection area. If not, scan the next area of ​​the vehicle cable terminal after the detection area scan is completed.

[0013] If there is a defect, mark the coordinates of the defect area, segment the image of the defect area, store the terahertz time-frequency domain information and imaging results of the defect area, and determine the category and geometric information of the defect area;

[0014] Step 5) Repeat steps 2) to 4) until the terahertz detection of the vehicle-mounted cable terminal is completed.

[0015] Furthermore, in step 1), the robotic arm is a three-degree-of-freedom robotic arm.

[0016] Furthermore, in step 1), the terahertz transceiver antenna array unit is arranged in an arc-shaped sheet, and the curvature of the terahertz transceiver antenna array unit is the same as the curvature of the vehicle-mounted cable terminal.

[0017] Furthermore, in step 1), three groups of independently arranged probes are provided on the terahertz transceiver antenna array unit, and the probes are driven by a mechanical control unit to move in an arc along the terahertz transceiver antenna array unit.

[0018] Furthermore, the reflective terahertz time-domain spectroscopy system includes a femtosecond laser, a spectroscope, an optical delay line, a reflector, and a terahertz receiver. The laser pulse generated by the femtosecond laser passes through the spectroscope and is divided into pump light and detection light.

[0019] The pump light is incident on the photoconductive antenna through the optical delay line to generate a terahertz wave. After the detection light and the terahertz wave are combined, they pass through the terahertz detector in the same line.

[0020] Furthermore, the probe is provided with a pigtail, the host is provided with a pigtail interface, and the pigtail is inserted into the pigtail interface to electrically connect the probe to the reflective terahertz time-domain spectroscopy system.

[0021] Furthermore, the pigtail is passed through the interior of the robotic arm.

[0022] Furthermore, in step 3), the reflective terahertz time-domain spectroscopy system has an analysis system for processing the terahertz signal. The analysis system performs Fourier transform based on the terahertz time-frequency domain information to obtain a corresponding frequency domain spectrum, and obtains the transfer function of the detection area from the frequency domain spectrum. The corresponding refractive index, absorption coefficient, dielectric constant and dielectric loss are obtained from the amplitude and phase of the transfer function.

[0023] Furthermore, the robotic arm drives the terahertz transceiver antenna array unit to move so that the arc tangent of the terahertz transceiver antenna array unit and the arc tangent of the detection area are coplanar and arranged in parallel.

[0024] Furthermore, the robotic arm is arranged on a mobile vehicle body, the camera is arranged on a terahertz transceiver antenna array unit, the robotic arm has joints, and the angle sensor is arranged on the joints.

[0025] Compared with the prior art, the terahertz detection method for vehicle-mounted cable terminals provided by the present invention has the following beneficial effects:

[0026] 1) The non-destructive testing method is used to overcome the shortcomings of traditional vehicle-mounted cable terminal defect detection methods, and can qualitatively, quantitatively and visually characterize the internal defect conditions of vehicle-mounted cable terminals;

[0027] 2) The aging status of vehicle-mounted cable terminals was characterized and evaluated using terahertz spectrum parameters, providing a new method for evaluating the aging status of vehicle-mounted cable terminals;

[0028] 3) The probe on the terahertz transceiver antenna array unit is used to scan the detection area of ​​the vehicle cable terminal, and a set of scanning detection results is obtained at each stage, which improves the detection efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 It is a flow chart of the terahertz detection method for a vehicle-mounted cable terminal provided by the present invention;

[0030] Figure 2 This is a flow chart of terahertz signal processing, optimization, and evaluation of vehicle-mounted cable terminal status provided by the present invention;

[0031] Figure 3 It is a schematic diagram of the control flow of the robotic arm provided by the present invention. DETAILED DESCRIPTION

[0032] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention 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 invention and are not intended to limit the present invention.

[0033] The implementation of the present invention is described in detail below with reference to specific embodiments.

[0034] The same or similar numbers in the drawings of this embodiment correspond to the same or similar parts; in the description of the present invention, it should be understood that if the terms "upper", "lower", "left", "right", etc. indicate the orientation or position relationship, they are based on the orientation or position relationship shown in the drawings. This is only for the convenience of describing the present invention and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operate in a specific orientation. Therefore, the terms describing the position relationship in the drawings are only used for illustrative purposes and cannot be understood as limiting this patent. For ordinary technicians in this field, the specific meanings of the above terms can be understood according to specific circumstances.

[0035] Reference Figure 1-3 The figure shows a preferred embodiment of the present invention.

[0036] The terahertz detection method of the vehicle-mounted cable terminal comprises the following steps:

[0037] Step 1) Select the detection area of ​​the vehicle cable terminal to be inspected, adjust the initial scanning position of the terahertz transceiver antenna array unit, and start the host, which includes a reflective terahertz time-domain spectroscopy system for generating terahertz waves and receiving feedback terahertz waves. The transceiver antenna of the reflective terahertz time-domain spectroscopy system is a probe set on the terahertz transceiver antenna array unit, and the terahertz transceiver antenna array unit is set on the robotic arm;

[0038] Step 2) Adjust the position of the robotic arm and the terahertz transceiver antenna array unit through the feature points captured by the camera and the feedback of the angle sensor until the probe is adjusted to the set position and start scanning detection;

[0039] Step 3) After the scanning detection is completed, the terahertz signal collected by the reflective terahertz time-domain spectroscopy system is processed to obtain the filtered terahertz time-frequency domain information of the detection area of ​​the vehicle-mounted mobile terminal, as well as the imaging results after super-resolution reconstruction and edge extraction optimization;

[0040] Step 4) Determine whether there are any defects in the current scanning test;

[0041] If there are no defects, determine whether the current vehicle cable terminal exceeds the aging state threshold. If it exceeds the aging state threshold, mark the coordinates of the detection area and store the information of the detection area. If it does not exceed the aging state threshold, when the detection area scan is completed, scan the next area of ​​the vehicle cable terminal;

[0042] If there is a defect, mark the coordinates of the defect area, segment the image of the defect area, store the terahertz time-frequency domain information and imaging results of the defect area, and determine the category and geometric information of the defect area;

[0043] Step 5) Repeat steps 2) to 4) until the terahertz detection of the vehicle-mounted cable terminal is completed.

[0044] The terahertz detection method for vehicle-mounted cable terminals provided above has the following beneficial effects:

[0045] 1) The non-destructive testing method is used to overcome the shortcomings of traditional vehicle-mounted cable terminal defect detection methods, and can qualitatively, quantitatively and visually characterize the internal defect conditions of vehicle-mounted cable terminals;

[0046] 2) The aging status of vehicle-mounted cable terminals was characterized and evaluated using terahertz spectrum parameters, providing a new method for evaluating the aging status of vehicle-mounted cable terminals;

[0047] 3) The probe on the terahertz transceiver antenna array unit is used to scan the detection area of ​​the vehicle cable terminal, and a set of scanning detection results is obtained at each stage, which improves the detection efficiency.

[0048] In this embodiment, in step 1), the robotic arm is a three-degree-of-freedom robotic arm, which is provided with three motors and can make corresponding position calibration according to the detection area and posture, and is controlled by the data acquisition and processing terminal in the host.

[0049] In this embodiment, in step 1), the terahertz transceiver antenna array unit is arranged in an arc sheet shape, and the curvature of the terahertz transceiver antenna array unit is the same as the curvature of the vehicle-mounted cable terminal.

[0050] In step 1), three sets of independently arranged probes are provided on the terahertz transceiver antenna array unit. The probes are driven by a mechanical control unit and move along the arc of the terahertz transceiver antenna array unit.

[0051] Each set of probes is 5 cm apart horizontally and is controlled by a mechanical control unit. It moves step by step within the curved surface governed by the terahertz transceiver antenna array unit to achieve three-dimensional step-by-point scanning, which is controlled by the data acquisition and processing terminal.

[0052] In this embodiment, the reflective terahertz time-domain spectroscopy system includes a femtosecond laser, a spectrometer, an optical delay line, a reflector, and a terahertz receiver. The laser pulse generated by the femtosecond laser passes through the spectrometer and is divided into pump light and probe light. The pump light is incident on the photoconductive antenna through the optical delay line to generate a terahertz wave. After the probe light and the terahertz wave merge, they pass through the terahertz detector colinearly and are used to drive the terahertz detector for measurement. The time delay between the pump light and the probe light is adjusted by controlling the optical delay line, and the entire time domain waveform of the terahertz pulse is finally obtained.

[0053] In this embodiment, a pigtail is provided on the probe, and a pigtail interface is provided on the host. The pigtail is inserted into the pigtail interface to electrically connect the probe to the reflective terahertz time-domain spectroscopy system, which is equivalent to leading the terahertz transmitter and receiver to the outside through the terahertz wave transmission optical fiber. A pigtail interface is provided on the side of the host.

[0054] In this embodiment, the pigtail is threaded inside the robotic arm and is equipped with a probe control and data transmission line. The reflective terahertz time-domain spectroscopy system in the host computer features an external 24-inch display with eight main display modules: time-domain spectrum, frequency-domain spectrum, refractive index, absorption coefficient, dielectric constant, dielectric loss, image, and test results.

[0055] In step 3), the reflective terahertz time-domain spectroscopy system has an analysis system for processing the terahertz signal. The analysis system performs Fourier transform based on the terahertz time-frequency domain information to obtain the corresponding frequency domain spectrum, and obtains the transfer function of the detection area from the frequency domain spectrum. The corresponding refractive index, absorption coefficient, dielectric constant and dielectric loss are obtained from the amplitude and phase of the transfer function.

[0056] The imaging results are obtained from the time domain spectrum intensity information (time domain maximum value, minimum value, peak-to-peak value) and frequency domain / absorption spectrum intensity information of all detection points. At the same time, the analysis system can calculate the aging status assessment value based on the spectrum parameters and the proposed vehicle cable terminal aging assessment model.

[0057] In this embodiment, the robotic arm drives the terahertz transceiver antenna array unit to move so that the arc tangent of the terahertz transceiver antenna array unit and the arc tangent of the detection area are coplanar and parallel.

[0058] The terahertz transceiver antenna array unit performs phased inspections. Due to the length of the vehicle cable terminal, the maximum coordinates of the inspection area are set for each phase. The vehicle cable terminal is approximately 43 cm long, allowing for an effective inspection length of 5 cm per phase. The robot arm is then moved to perform the next phase of scanning inspection, ultimately completing the terahertz nondestructive inspection of the entire vehicle cable terminal.

[0059] The control probe moves within the scanning jurisdiction. Three groups of probes simultaneously complete scanning and detection of the existing detection area to improve detection efficiency. This is controlled by the control system in the host. The central spot diameter of each group of terahertz wave transmitting probes is 3mm.

[0060] The terahertz signal processing and analysis terminal in the host should integrate filtering algorithms for processing high-order terahertz reflection echoes, clustering algorithms for defect image area segmentation, terahertz image super-resolution reconstruction algorithms, and image edge processing algorithms to optimize terahertz detection results.

[0061] The robotic arm is arranged on a mobile vehicle body, the camera is set on the terahertz transceiver antenna array unit, the robotic arm has joints, and the angle sensor is set on the joints. The position of the robotic arm and the probe is adjusted in real time through feedback.

[0062] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A terahertz detection method for a vehicle-mounted cable terminal, characterized in that: The following steps are involved: Step 1) Select the detection area of ​​the vehicle cable terminal to be detected, adjust the initial scanning position of the terahertz transceiver antenna array unit, and start the host, wherein the host includes a reflective terahertz time-domain spectroscopy system for generating terahertz waves and receiving feedback terahertz waves, and the transceiver antenna of the reflective terahertz time-domain spectroscopy system is a probe arranged on the terahertz transceiver antenna array unit, and the terahertz transceiver antenna array unit is arranged on the robotic arm; Step 2) adjusting the position of the robotic arm and the terahertz transceiver antenna array unit through the feature points captured by the camera and the feedback of the angle sensor until the probe is adjusted to the set position and then starting the scanning detection; Step 3), after the scanning detection is completed, the terahertz signal collected by the reflective terahertz time-domain spectroscopy system is processed to obtain the filtered terahertz time-frequency domain information of the detection area of ​​the vehicle-mounted mobile terminal, as well as the imaging result after super-resolution reconstruction and edge extraction optimization; Step 4) Determine whether there are any defects in the current scanning test; If there are no defects, determine whether the current vehicle cable terminal exceeds the aging state threshold. If so, mark the coordinates of the detection area and store the information of the detection area. If not, scan the next area of ​​the vehicle cable terminal after the detection area scan is completed. If there is a defect, mark the coordinates of the defect area, segment the image of the defect area, store the terahertz time-frequency domain information and imaging results of the defect area, and determine the category and geometric information of the defect area; Step 5) Repeat steps 2) to 4) until the terahertz detection of the vehicle-mounted cable terminal is completed.

2. The terahertz detection method for a vehicle-mounted cable terminal according to claim 1, wherein: In the step 1), the robotic arm is a three-degree-of-freedom robotic arm.

3. The terahertz detection method for a vehicle-mounted cable terminal according to claim 1, wherein: In the step 1), the terahertz transceiver antenna array unit is arranged in an arc sheet shape, and the curvature of the terahertz transceiver antenna array unit is the same as the curvature of the vehicle-mounted cable terminal.

4. The terahertz detection method for a vehicle-mounted cable terminal according to any one of claims 1 to 3, characterized in that: In the step 1), three groups of independently arranged probes are provided on the terahertz transceiver antenna array unit, and the probes are driven by a mechanical control unit to move in an arc along the terahertz transceiver antenna array unit.

5. The terahertz detection method for a vehicle-mounted cable terminal according to any one of claims 1 to 3, characterized in that: The reflective terahertz time-domain spectroscopy system includes a femtosecond laser, a spectroscope, an optical delay line, a reflector, and a terahertz receiver. The laser pulse generated by the femtosecond laser passes through the spectroscope and is divided into pump light and detection light. The pump light is incident on the photoconductive antenna through the optical delay line to generate a terahertz wave. After the detection light and the terahertz wave are combined, they pass through the terahertz detector in the same line.

6. The terahertz detection method for a vehicle-mounted cable terminal according to any one of claims 1 to 3, characterized in that: The probe is provided with a pigtail, the host is provided with a pigtail interface, and the pigtail is inserted into the pigtail interface so that the probe is electrically connected to the reflective terahertz time-domain spectroscopy system.

7. The terahertz detection method for a vehicle-mounted cable terminal according to claim 6, wherein: The pigtail is passed through the interior of the mechanical arm.

8. The terahertz detection method for a vehicle-mounted cable terminal according to any one of claims 1 to 3, characterized in that: In step 3), the reflective terahertz time-domain spectroscopy system has an analysis system for processing the terahertz signal. The analysis system performs Fourier transform based on the terahertz time-frequency domain information to obtain a corresponding frequency domain spectrum, and obtains the transfer function of the detection area from the frequency domain spectrum. The corresponding refractive index, absorption coefficient, dielectric constant and dielectric loss are obtained from the amplitude and phase of the transfer function.

9. The terahertz detection method for a vehicle-mounted cable terminal according to any one of claims 1 to 3, characterized in that: The mechanical arm drives the terahertz transceiver antenna array unit to move so that the arc tangent of the terahertz transceiver antenna array unit and the arc tangent of the detection area are coplanar and parallel.

10. The terahertz detection method for a vehicle-mounted cable terminal according to any one of claims 1 to 3, characterized in that: The robotic arm is arranged on a mobile vehicle body, the camera is arranged on a terahertz transceiver antenna array unit, the robotic arm has a joint position, and the angle sensor is arranged at a door closing position.

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