A pipeline laying path intelligent microwave detection device and method based on circular waveguide mode

Abstract

The application provides a pipeline laying path intelligent microwave detection device and method based on a circular waveguide mode, which comprises a feed horn used for being connected with the end of a metal pipeline to be detected to realize non-leakage transmission of a microwave signal, a microwave signal source used for generating an excitation signal of a specific frequency band, and an FPGA control system used for controlling the signal emission and receiving timing of the microwave signal source, collecting and processing time-domain voltage wave signals at a waveguide port. 11 The FPGA control system excites pure TE 11 mode microwaves into the metal pipeline to be detected through the feed horn, collects time-domain voltage wave signals of reflected waves and transmitted waves, extracts wave peak characteristics and time information, and inverses the corner position of the pipeline, the length of the pipeline section and the total path. The device has simple structure, low cost and convenient installation, and has wide engineering application prospect.

Description

Technical Field

[0001] This invention relates to the field of nondestructive testing and intelligent testing technology, and in particular to an intelligent microwave testing device and method for pipeline laying paths based on circular waveguide modes. Background Technology

[0002] Metal pipelines, as a highly efficient fluid transport structure, are widely used in oil, natural gas, and urban pipe networks. During pipeline laying and long-term service, the actual laying path of the pipeline may deviate due to engineering quality, geological subsidence, landslides, earthquakes, or disturbances caused by third-party construction. This unexpected path deviation can lead to additional stress on the pipeline, which is a significant hidden danger causing pipeline buckling, weld cracking, support overload, and even overall structural failure. Therefore, accurate detection of the laying path of in-service pipelines, especially long-distance transport pipelines or pipelines in concealed spaces (such as pipe galleries or suspended ceilings), is of great significance for assessing the structural integrity of pipelines and ensuring safe operation and maintenance. However, current metal pipeline path detection methods have drawbacks such as high cost and limited applicability.

[0003] In summary, the problems with existing technologies are: 1. Internal inspection methods, based on inertial navigation technology, typically involve sending a robot or detector equipped with a high-precision inertial measurement unit (IMU) into the pipeline. This method can accurately measure the pipeline path. However, this technology also has obvious limitations: high inspection costs, and risks of equipment jamming or loss. It is also difficult to apply to small-diameter pipelines or pipelines without transceiver devices.

[0004] 2. External detection method achieves non-contact path detection by receiving physical field signals generated by the pipeline on the ground. It is mainly based on two core technologies: electromagnetic induction and magnetic stress. It achieves non-contact path detection by receiving electromagnetic field signals or radar reflection waves generated by the pipeline on the ground. This method is easily affected by surrounding metal objects and complex environments, and usually can only obtain the planar projection position of the pipeline. It has low detection accuracy or is not applicable to pipelines in pipe racks and deeply buried pipelines. Summary of the Invention

[0005] In view of this, the purpose of this invention is to provide an intelligent microwave detection device and method for pipeline laying path based on circular waveguide mode. The device has a simple structure, low cost, and convenient installation, and has broad engineering application prospects.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: an intelligent microwave detection device for pipeline laying paths based on circular waveguide modes, comprising: The feed horn is used to connect to the end of the metal pipe under test to achieve leakage-free transmission of microwave signals. A microwave signal source is used to generate excitation signals in a specific frequency band. An FPGA control system is used to control the signal transmission and reception timing of the microwave signal source, and to acquire and process the time-domain voltage wave signal at the waveguide port. The FPGA control system excites pure TE signals into the metal pipe under test through the feed horn. 11 The main mode microwave is used to collect the time-domain voltage wave signals of the reflected and transmitted waves. By extracting the peak characteristics and time information, the corner position, pipe segment length and total path of the pipeline are inverted.

[0007] In a preferred embodiment, the aperture of the feed horn is matched with the inner diameter of the metal pipe under test. One end of the feed horn is sealed to the end face of the metal pipe under test via a flange or clamp, and the other end integrates a coaxial-waveguide conversion structure and is connected to the microwave signal source and the FPGA control system via a coaxial cable.

[0008] In a preferred embodiment, the FPGA control system has a built-in high-speed AD / DA module for parallel acquisition and real-time digital processing of the time-domain voltage wave signal at the waveguide port, and supports waveform display, data storage, and intelligent inversion analysis of detection results.

[0009] This invention also provides an intelligent microwave detection method for pipeline laying paths based on circular waveguide modes, applied to the aforementioned intelligent microwave detection device for pipeline laying paths based on circular waveguide modes, characterized by comprising the following steps: Step 1: Treat the metal pipe under test as a circular waveguide structure and calculate TE based on its inner diameter. 11 The single-mode transmission bandwidth of the main mode; Step 2: Install feed horns at both ends of the metal pipe under test, and control the microwave signal source to emit Gaussian pulse signals within the frequency band through the FPGA control system to excite the pure TE. 11 The main microwave mode is transmitted along the pipe; Step 4: Acquire the time-domain reflected wave and transmitted wave voltage signals at the pipe port through the FPGA control system; Step 5: Extract the peak features and corresponding time information from the time-domain reflected wave and the transmitted wave, and invert the corner position of the pipeline, the length of each pipe segment, and the total length of the pipeline.

[0010] In a preferred embodiment, the TE 11 The single-mode transmission bandwidth of the master mode meets the following conditions

[0011] Its frequency range is:

[0012] Where r is the inner radius of the pipe, λ TE11 For TE 11 The operating wavelength of the mode.

[0013] In a preferred embodiment, the spectral range of the Gaussian pulse signal is limited to the TE. 11 Within the single-mode transmission band of the main mode, the modal purity of the excitation signal is ensured.

[0014] In a preferred embodiment, the steps of inverting the pipe bend position and pipe segment length include: determining the microwave propagation time in each pipe segment based on the occurrence time of each voltage peak in the reflected wave, and calculating the position of each bend and the pipe segment length between adjacent bends in combination with the microwave propagation speed.

[0015] In a preferred embodiment, the step of inverting the total length of the pipe includes: determining the propagation time of the microwave from the transmitting end to the receiving end based on the arrival time of the transmitted wave, and calculating the total length of the pipe in combination with the microwave propagation speed.

[0016] In a preferred embodiment, the number of voltage peaks in the reflected wave corresponds one-to-one with the number of pipe bends, and the time interval between peaks reflects the pipe segment length between adjacent bends.

[0017] Compared with the prior art, the present invention has the following beneficial effects: This invention utilizes metal pipes as a natural circular waveguide structure, eliminating the need to place mobile detection equipment inside the pipe and avoiding the risks of jamming and loss inherent in internal detection methods. It is particularly suitable for small-diameter pipes and pipes without transceiver devices.

[0018] This invention uses pure TE 11 The main model uses microwave for detection. The microwave signal is less affected by the external environment during propagation inside the pipeline, and has good detection capabilities for both pipelines in pipe racks and buried pipelines. It overcomes the problems of poor anti-interference ability and low detection accuracy of external detection methods.

[0019] This invention achieves precise signal transmission and high-speed acquisition through an FPGA control system. By combining the feature extraction of time-domain reflected waves and transmitted waves, it can realize intelligent inversion of pipeline corner positions, pipe segment lengths and total paths. The detection process is highly automated and easy to operate.

[0020] The device of this invention has a simple structure, low cost, and convenient installation, and has broad prospects for engineering applications. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the system structure provided in the embodiment of the present invention.

[0022] Figure 2This is a schematic diagram of the connection between the feed horn and the metal pipe provided in this embodiment of the invention.

[0023] Figure 3 This is a schematic diagram of a metal pipe model provided in the embodiment of the present invention.

[0024] Figure 4 This is an excitation signal diagram provided in the embodiment of the present invention.

[0025] Figure 5 This is a diagram showing the metal pipe structure and simulation results of Embodiment 1 of the present invention.

[0026] Figure 6 This is a diagram showing the metal pipe structure and simulation results of Embodiment 2 of the present invention. Detailed Implementation

[0027] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0028] It should be noted that the following detailed descriptions are illustrative and intended to provide further explanation of this application. Unless otherwise specified, 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 application pertains.

[0029] It should be noted that the terminology used herein is for the purpose of describing particular implementations only and is not intended to limit the exemplary implementations according to this application; as used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise; furthermore, it should be understood that when the terms “comprising” and / or “including” are used in this specification, they indicate the presence of features, steps, operations, devices, components and / or combinations thereof.

[0030] A smart microwave detection device for pipeline laying paths based on specific modes of circular waveguides, referenced Figure 1-6 This intelligent detection device mainly consists of three parts: a feed horn, a microwave signal source, and an FPGA control system. It features low cost, easy installation, small footprint, and excellent detection capabilities even in complex environments. By changing the opening size of the feed horn, it can detect metal pipes of different diameters, solving the problem that internal inspection methods are difficult to apply to small-diameter pipes. The device sends a specific mode TE11 signal into the metal pipe under test through the feed horn, unaffected by the surrounding environment during the detection process, and has excellent detection capabilities for pipes in pipe racks and buried pipes. The FPGA control system emits a specific frequency band Gaussian pulse signal to excite pure TE11 main mode microwaves to propagate within the pipe. Simultaneously, it collects time-domain reflected and transmitted wave signals at the ports, extracts peak characteristics and time information, and inverts the pipe's corner positions, segment lengths, and total path, thereby achieving intelligent and accurate detection of the pipe path.

[0031] The method of this invention is based on the circular waveguide mode theory and combined with an FPGA control system. The metal pipe under test is regarded as a circular waveguide structure. The frequency band range of pure TE11 mode excitation is calculated according to the diameter of the metal pipe. Taking advantage of the characteristics of TE11 mode excitation, which generates reflection at the bend of the metal pipe and propagates continuously at the straight section, the geometric path of the pipe is inverted by acquiring and analyzing the time-domain voltage wave signal at the port of the metal pipe through the FPGA control system.

[0032] The core of the detection method described in this invention lies in utilizing a metal pipe as a natural circular waveguide. By selecting a specific mode of microwave signal for excitation and analyzing its time-domain reflection and transmission characteristics within the metal pipe, the pipe's laying path can be inverted. Specifically, this method first requires satisfying the condition of single-mode transmission of the TE11 master mode within the pipe; secondly, by arranging feed horns at both ends of the pipe, the transmission and reception of microwave signals within the metal pipe are achieved; finally, by extracting the characteristics of the time-domain voltage wave signal, the path of the metal pipe is inverted.

[0033] At each of the two openings of the metal pipe under test, a waveguide feed horn is installed. The diameter of the horn opening is the same as that of the metal pipe. One end of the waveguide feed horn is sealed to the end face of the metal pipe via a flange or special clamp to ensure that the microwave signal enters the metal pipe for transmission without leakage. The other end of the waveguide feed horn integrates a coaxial-waveguide conversion structure (specific structure as shown in...). Figure 2 As shown, the waveguide feed horn is connected to the microwave signal source and FPGA control system via a coaxial cable; the internal cross section of the waveguide feed horn gradually transitions from the standard waveguide size to the same diameter as the pipe under test, so as to achieve impedance matching and pure excitation of the master mode TE11.

[0034] The FPGA control system, as the core control and data processing unit of the entire microwave detection device, realizes precise timing control of signal transmission and reception. The microwave signal source sends electrical pulses of a specific frequency to the feedhorn through a coaxial cable. The feedhorn converts the voltage wave into a pure TE11 mode electromagnetic wave in the waveguide. At the same time, the system uses a built-in high-speed AD / DA module to perform parallel acquisition and real-time digital processing of the time-domain voltage wave signal at the waveguide port, extracting the peak characteristics and time information in the reflected and transmitted waves. It also supports real-time display of waveform data and storage of detection results on the touch screen, thereby realizing intelligent identification and inversion analysis of pipeline laying paths.

[0035] Implementation Example 1 The following are experimental data obtained through simulation in CST simulation software, illustrating the influence of a horizontal section structure of a metal pipe on the transmission characteristics of excitation waves.

[0036] A metal pipe with an inner radius of 0.05m was designed and constructed. This pipe consists of three horizontal sections and two vertical sections. The pipe has a bending angle of 90 degrees and a bending radius of 0.1m. Specifications are as follows: Figure 3 As shown. Keeping the vertical section of the metal pipe with a length of c=0.5m constant, three sets of data are configured: the first set is a=2.0m, b=1.0m, c=0.5m; the second set is a=1.5m, b=2.0m, c=0.5m; and the third set is a=1.0m, b=2.0m, c=0.5m.

[0037] Circular waveguides are structurally axially symmetric, and their behavior changes with the direction of the electric field (TE). 11 The propagation characteristics and field distribution of electromagnetic waves are exactly the same for a circular waveguide with radius r. Its TE... 11 The wavelength range in which the mode operates is:

[0038] Its frequency range is:

[0039] In this example, the radius of the metal pipe used is 0.05m. The TE value was calculated. 11 The cutoff frequency of the mode is 1.76GHz, using a single-mode TE. 11 The operating frequency band of the mode is 1.76 GHz to 2.2 GHz. Excitation is configured at both ends of the metal pipe, using a Gaussian pulse signal as the excitation signal. By configuring the spectral range Fmin = 1.8 GHz and Fmax = 2.1 GHz, the spectrum of the excitation signal is limited to TE. 11 Within the operating frequency band of the module. Excitation signal such as... Figure 4 As shown, the metal pipe structure and simulation results are as follows: Figure 5 As shown.

[0040] By changing the structure of the horizontal section of the metal pipe, simulation results show that four voltage wave signals appear in the reflected wave at port one in all three cases, and the amplitudes of the voltage waves corresponding to the four corners are basically the same. As the length of section b of the metal pipe increases, the distance between the second and third voltage waves reflected at port one begins to increase, indicating that the transmission time of the excitation signal between the second and third corners of the curved metal pipe increases. As the length of section a of the metal pipe decreases, the appearance time of the first voltage wave at port one begins to advance, while the appearance time of the fourth voltage wave begins to delay. In all three cases, the total length of the metal pipe structure remains constant, so the appearance time and amplitude of the transmitted wave at port two are the same.

[0041] The results show that each corner corresponds to a different voltage wave. The location of each corner and the distance between corners can be deduced by the time of each voltage wave in the reflected wave. This method is of high value for determining the laying path of metal pipes. The simulation results in the embodiment fully demonstrate the correctness of the design method in this invention patent.

[0042] Implementation Example 2 The following are experimental data obtained through simulation in CST simulation software, illustrating the influence of the vertical section structure of a metal pipe on the transmission characteristics of excitation waves.

[0043] A metal pipe with an inner radius of 0.05m was designed and constructed. This pipe consists of three horizontal sections and two vertical sections. The pipe has a bending angle of 90 degrees and a bending radius of 0.1m. Specifications are as follows: Figure 3 As shown. Keeping the lengths of the horizontal sections of the metal pipe constant (a=1.0m, b=3.0m), three sets of data are configured: the first set uses a=1.0m, b=3.0m, c=0.5m; the second set uses a=1.0m, b=3.0m, c=0.75m; and the third set uses a=1.0m, b=3.0m, c=1.0m. Excitation is applied at both ends of the metal pipe, using Gaussian pulse signals as the excitation signals. By configuring Fmin=1.8GHz and Fmax=2.1GHz, the spectrum of the excitation signal is limited to TE. 11 Within the operating frequency band of the module. Excitation signal such as... Figure 4 As shown, the metal pipe structure and simulation results are as follows: Figure 6 As shown.

[0044] By changing the structure of the vertical section of the metal pipe, simulation results show that four voltage wave signals also appear in the reflected wave at port one. As the length of the metal pipe increases, the fourth reflected wave gradually dissipates. With the increase of the length of section c of the metal pipe, the distance between the first and second voltage waves at port one begins to increase. Since the length of section b of the metal pipe is constant, the distance between the second and third voltage waves at port one remains essentially unchanged. In all three cases, the change in the length of section c of the metal pipe causes a change in the overall length of the metal pipe. The length of the metal pipe increases sequentially from the first group to the third group, therefore the time of the transmitted wave at port two begins to be delayed, while the amplitude remains essentially unchanged.

[0045] The results show that each corner corresponds to a different voltage wave. The position of each corner can be deduced by the time of each voltage wave in the reflected wave. As the length of the metal pipe increases, the time of the transmitted wave begins to increase. The length of the metal pipe can be deduced by the time of the transmitted wave. This method has high value for judging the laying path and length analysis of metal pipes. The simulation results in the embodiment fully prove the correctness of the design method in this invention patent.

[0046] This invention utilizes a metal pipe as a natural circular waveguide structure. An FPGA control system precisely selects and transmits Gaussian pulse signals at specific frequencies to excite a pure TE11 master mode for transmission within the pipe. The system can simultaneously acquire the time-domain reflected wave and transmitted wave voltage signals at the waveguide ports and automatically extract peak features and time information from the waveforms. Experimental results show that the voltage peaks appearing in the reflected wave correspond one-to-one with the position of each bend in the pipe, and the time interval between peaks accurately reflects the length of each pipe segment and the bend spacing. The arrival time of the transmitted wave directly corresponds to the total length of the pipe, thus achieving accurate inversion of the pipe laying path.

[0047] This method, through intelligent signal control and feature extraction, can stably acquire waveform features reflecting the pipeline path structure. The amplitude and temporal variations are highly correlated with the path's geometric parameters. It boasts advantages such as simple structure, easy installation, low cost, and wide applicability, making it particularly suitable for path detection in small-diameter pipelines and concealed spaces. This fully demonstrates the feasibility and reliability of this invention in practical engineering applications, providing a novel intelligent detection method for assessing the structural integrity and ensuring safe operation and maintenance of in-service metal pipelines.

Claims

1. A smart microwave detection device for pipeline laying paths based on circular waveguide modes, characterized in that, include: The feed horn is used to connect to the end of the metal pipe under test to achieve leakage-free transmission of microwave signals. A microwave signal source is used to generate excitation signals in a specific frequency band. An FPGA control system is used to control the signal transmission and reception timing of the microwave signal source, and to acquire and process the time-domain voltage wave signal at the waveguide port. The FPGA control system excites pure TE signals into the metal pipe under test through the feed horn. 11 The main mode microwave is used to collect the time-domain voltage wave signals of the reflected and transmitted waves. By extracting the peak characteristics and time information, the corner position, pipe segment length and total path of the pipeline are inverted.

2. The intelligent microwave detection device for pipeline laying path based on circular waveguide mode according to claim 1, characterized in that, The aperture of the feed horn matches the inner diameter of the metal pipe under test. One end of the feed horn is sealed to the end face of the metal pipe under test via a flange or clamp, and the other end integrates a coaxial-waveguide conversion structure and is connected to the microwave signal source and the FPGA control system via a coaxial cable.

3. The intelligent microwave detection device for pipeline laying path based on circular waveguide mode according to claim 1, characterized in that, The FPGA control system has a built-in high-speed AD / DA module for parallel acquisition and real-time digital processing of time-domain voltage wave signals at the waveguide port, and supports waveform display, data storage, and intelligent inversion analysis of detection results.

4. A smart microwave detection method for pipeline laying paths based on circular waveguide modes, applied to the smart microwave detection device for pipeline laying paths based on circular waveguide modes as described in any one of claims 1 to 3, characterized in that, Includes the following steps: Step 1: Treat the metal pipe under test as a circular waveguide structure and calculate TE based on its inner diameter. 11 The single-mode transmission bandwidth of the main mode; Step 2: Install feed horns at both ends of the metal pipe under test, and control the microwave signal source to emit Gaussian pulse signals within the frequency band through the FPGA control system to excite the pure TE. 11 The main microwave mode is transmitted along the pipe; Step 4: Acquire the time-domain reflected wave and transmitted wave voltage signals at the pipe port through the FPGA control system; Step 5: Extract the peak features and corresponding time information from the time-domain reflected wave and the transmitted wave, and invert the corner position of the pipeline, the length of each pipe segment, and the total length of the pipeline.

5. The intelligent microwave detection method for pipeline laying path based on circular waveguide modes according to claim 4, characterized in that, The TE 11 The single-mode transmission bandwidth of the master mode meets the following conditions Its frequency range is: Where r is the inner radius of the pipe, λ TE11 For TE 11 The operating wavelength of the mode.

6. The intelligent microwave detection method for pipeline laying path based on circular waveguide modes according to claim 4, characterized in that, The spectral range of the Gaussian pulse signal is limited to the TE. 11 Within the single-mode transmission band of the main mode, the modal purity of the excitation signal is ensured.

7. The intelligent microwave detection method for pipeline laying path based on circular waveguide modes according to claim 4, characterized in that, The steps for inverting the location of pipe bends and the length of pipe segments include: determining the propagation time of microwaves in each pipe segment based on the occurrence time of each voltage peak in the reflected wave, and calculating the location of each bend and the length of the pipe segment between adjacent bends by combining the microwave propagation speed.

8. The intelligent microwave detection method for pipeline laying path based on circular waveguide modes according to claim 4, characterized in that, The steps for inverting the total length of the pipe include: determining the propagation time of the microwave from the transmitting end to the receiving end based on the arrival time of the transmitted wave, and calculating the total length of the pipe by combining the microwave propagation speed.

9. The intelligent microwave detection method for pipeline laying path based on circular waveguide modes according to claim 4, characterized in that, The number of voltage peaks in the reflected wave corresponds one-to-one with the number of pipe bends, and the time interval between peaks reflects the pipe segment length between adjacent bends.

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