A sewer structural defect detection system, method, medium, and product

Abstract

The application relates to the technical field of sewer pipeline detection, and discloses a sewer pipeline structural defect detection system, method, medium and product. The controller actively constructs and generates coded infrasound wave signals, so that the signals have stable frequency and amplitude characteristics. An infrasound sounding module uses the coded infrasound wave signals to emit and process infrasound waves, and makes low-frequency mechanical vibration signals stably propagate along the pipe wall, reduces energy attenuation, and covers long-distance pipe sections that cannot be reached by traditional passive detection. The low-frequency mechanical vibration signals are detected by an infrasound signal receiving module, and analog signals are converted into initial digital signals, so that interference and distortion in the transmission process are reduced. Further, by combining a Fourier transform method and a correlation coefficient analysis method, the problem of high misjudgment rate of a traditional single algorithm is avoided, the accurate identification of pipeline structural defects is ensured, and the accuracy requirement of sewer pipeline structural defect detection under complex working conditions is met.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of sewer pipeline detection, and in particular to a sewer pipeline structural defect detection system, method, medium and product. BACKGROUND

[0002] As an important part of urban municipal infrastructure, sewer pipeline systems play a significant role in maintaining urban water safety and water ecological environment health. Due to factors such as aging corrosion and ground load, structural defects such as cracks and misalignments are common in sewer pipelines during long-term service, which causes a large amount of groundwater in the soil to seep into the sewer pipeline through the above-mentioned defect areas, resulting in low inflow concentration and decreased treatment efficiency in sewage treatment plants. In addition, sewage in the pipeline can also seep into groundwater through the above-mentioned areas, causing groundwater and soil environment pollution. Therefore, it is urgent to carry out sewer network damage identification and positioning.

[0003] Existing pipeline damage detection technologies mainly include physical detection and acoustic detection. Physical detection technologies such as closed-circuit television can directly present pipeline structural defects and have high positioning accuracy, but such methods require pipeline plugging, dewatering, dredging, and emptying, which have long implementation periods and high costs, and are not suitable for large-scale and rapid investigation. Acoustic detection technology identifies and locates pipeline damage by sensing leakage sound signals.

[0004] Among them, infrasound detection technology has been widely used in leakage detection of pressure pipelines such as oil and gas transportation and urban water supply due to its long transmission distance and low energy attenuation.

[0005] However, the application of this technology in urban sewage pipelines still faces significant challenges. On the one hand, sewage treatment is gravity flow or low-pressure operation, and the sound signals generated by damage leakage are weak and easily overwhelmed by environmental background noise. On the other hand, there are complex hydraulic conditions such as silt accumulation and gas-liquid two-phase flow inside the sewage pipeline, which will cause significant attenuation and distortion of infrasound signals during transmission, reducing detection accuracy. Therefore, traditional acoustic detection technology cannot meet the effective identification needs of urban underground sewage pipeline networks for damage leakage problems under complex working conditions. SUMMARY

[0006] Therefore, the present application provides a sewer pipeline structural defect detection system, method, medium and product to solve the problem that traditional acoustic detection technology cannot meet the effective identification needs of urban underground sewage pipeline networks for damage leakage problems under complex working conditions.

[0007] In a first aspect, the present application provides a sewer structural defect detection system, which comprises a controller, an infrasound emitting module, an infrasound signal receiving module, and a detection module, wherein the infrasound emitting module and the infrasound signal receiving module are arranged in different inspection wells at different ends of the sewer.

[0008] The controller is configured to construct an encoded infrasound wave signal and send the encoded infrasound wave signal to the infrasound emitting module and the detection module; the infrasound emitting module is configured to emit and process the encoded infrasound wave signal to obtain a low-frequency mechanical vibration signal, which is transmitted in the sewer; the infrasound signal receiving module is configured to detect the low-frequency mechanical vibration signal of the sewer and determine an initial digital vibration signal, and send the initial digital vibration signal to the detection module; and the detection module is configured to process the initial digital vibration signal and the encoded infrasound wave signal based on a Fourier transform method and a correlation coefficient analysis method to determine a structural defect detection result of the sewer.

[0009] The sewer structural defect detection system provided by the present application actively constructs and generates an encoded infrasound wave signal through the controller, ensuring that the signal has stable frequency and amplitude characteristics, and effectively distinguishing between effective signals and environmental noise compared to traditional uncoded signals, thereby solving the problem of signal being easily submerged in complex sewer conditions. At the same time, the encoded signal is synchronously sent to the detection module, providing a "reference signal" for subsequent comparison and analysis of received signals, avoiding signal abnormality judgment bias caused by the absence of a reference. Furthermore, the infrasound emitting module emits and processes the encoded infrasound wave signal, and through internal signal processing and mechanical coupling design, the low-frequency mechanical vibration signal is stably transmitted along the pipe wall, reducing energy attenuation and covering long-distance pipe sections that are difficult to reach by traditional passive detection. At the same time, the actively emitted vibration signal is not affected by the sludge and gas-liquid two-phase flow in the pipe, solving the problem of weak signal being easily submerged by noise in gravity flow sewer pipes. Furthermore, the low-frequency mechanical vibration signal of the sewer is detected by the infrasound signal receiving module, which can completely obtain the dynamic changes of the signal along the pipe, avoiding the omission of local defects. At the same time, the analog signal is converted into an initial digital signal, reducing interference and distortion during transmission and providing high-quality raw data for subsequent data analysis, solving the problem of traditional analog signals being easily disturbed and having low data reliability. Furthermore, Fourier transform can extract the main frequency shift characteristics and identify the frequency component changes caused by defects, and correlation coefficient analysis can quantify signal similarity and exclude non-defect factors such as noise, and the combination of the two avoids the high false positive rate of traditional single algorithms, and finally accurately outputs whether the pipe is damaged, meeting the accuracy requirements of sewer structural defect detection in complex conditions. Therefore, by implementing the present application, the problem of traditional acoustic detection technology being unable to meet the effective identification needs of city underground sewer networks in complex conditions for damage and leakage problems is solved.

[0010] In an alternative embodiment, the controller comprises an acquisition unit and a construction unit;

[0011] The acquisition unit is configured to acquire the time signal sequence and send the time signal sequence to the construction unit; and the construction unit is configured to construct the coded infrasound wave signal based on the time signal sequence.

[0012] The drainage pipeline structural defect detection system provided by the application provides a precise time carrier for the construction of the coded signal by generating a uniform and continuous time signal sequence, ensures the smooth and controllable frequency change of the subsequent linear frequency modulation signal, avoids signal waveform distortion caused by irregular time sequences, and guarantees the anti-interference ability of the coded signal. Further, the coded infrasound wave signal constructed based on the time signal sequence meets the pipeline detection requirements, can flexibly adjust the signal parameters to adapt to pipelines of different diameters and materials, solves the problem that the traditional fixed signal cannot be adapted to complex pipeline networks, and improves the propagation reliability and recognizability of the signal in the pipeline.

[0013] In an alternative embodiment, the infrasound sound generation module comprises a transmission controller, a power amplifier driving unit, a sound generator unit, and a coupling device, the sound generator unit adopts a piezoelectric ceramic sheet stacking structure, the coupling device is composed of a flexible sound guide material and an elastic pressing arm, and the sound generator unit is mechanically coupled with the inspection well wall of the drainage pipeline through the coupling device.

[0014] The transmission controller is configured to emit a low-frequency programming signal using the coded infrasound wave signal when receiving the coded infrasound wave signal; the power amplifier driving unit is configured to amplify the low-frequency programming signal to obtain a high-frequency programming signal and send the high-frequency programming signal to the sound generator unit when receiving the low-frequency programming signal; the sound generator unit is configured to convert the high-frequency programming signal to obtain a low-frequency mechanical vibration signal and send the low-frequency mechanical vibration signal to the coupling device, so that the low-frequency mechanical vibration signal is transmitted in the drainage pipeline through the coupling device.

[0015] The drainage pipeline structural defect detection system provided by the application can receive coded infrasonic wave signals through the emission controller, emit low-frequency programming signals by using the coded infrasonic wave signals, and accurately control the time sequence and spectrum parameters of the low-frequency programming signals. Further, the low-frequency programming signals are amplified by the power amplifier driving unit to meet the driving requirements of the sound emitter unit, ensure that the intensity of the subsequent mechanical vibration signals is sufficient, avoid rapid attenuation of the signals along the pipe wall due to insufficient signal power, and solve the problem of small signal coverage range of the traditional sound emitting device. Meanwhile, the low-frequency response characteristics are maintained, the waveform distortion in the signal amplification process is avoided, and the consistency between the signal characteristics and the coding design is ensured. Further, the sound emitter unit adopts a piezoelectric ceramic sheet stacking structure to realize efficient conversion of electrical signals and mechanical vibrations, and then output low-frequency mechanical vibration signals matching the frequency and coding signals, which can adapt to the characteristics of long propagation distance and low energy attenuation of infrasonic waves, and provide a stable vibration source for the active acoustic waveguide propagating along the pipe wall. The sound emitter unit and the inspection well wall of the drainage pipeline are mechanically coupled through the coupling device, the loss of kinetic energy in the transmission process is reduced, efficient coupling of mechanical vibration to the pipe wall is realized, signal attenuation or distortion caused by poor coupling is avoided, and stable propagation of infrasonic waves along the pipe wall to the receiving end is ensured.

[0016] In an alternative embodiment, the infrasound signal receiving module comprises an inductive receiver array and a signal acquisition unit.

[0017] The inductive receiver array is configured to detect the low-frequency mechanical vibration signals of the drainage pipeline and send the low-frequency mechanical vibration signals to the signal acquisition unit when the low-frequency mechanical vibration signals are detected. The signal acquisition unit is configured to convert the low-frequency mechanical vibration signals to obtain initial digital vibration signals and send the initial digital vibration signals to the detection module.

[0018] The drainage pipeline structural defect detection system provided by the application can receive coded infrasonic wave signals through the emission controller, emit low-frequency programming signals by using the coded infrasonic wave signals, and accurately control the time sequence and spectrum parameters of the low-frequency programming signals. Further, the low-frequency programming signals are amplified by the power amplifier driving unit to meet the driving requirements of the sound emitter unit, ensure that the intensity of the subsequent mechanical vibration signals is sufficient, avoid rapid attenuation of the signals along the pipe wall due to insufficient signal power, and solve the problem of small signal coverage range of the traditional sound emitting device. Meanwhile, the low-frequency response characteristics are maintained, the waveform distortion in the signal amplification process is avoided, and the consistency between the signal characteristics and the coding design is ensured. Further, the sound emitter unit adopts a piezoelectric ceramic sheet stacking structure to realize efficient conversion of electrical signals and mechanical vibrations, and then output low-frequency mechanical vibration signals matching the frequency and coding signals, which can adapt to the characteristics of long propagation distance and low energy attenuation of infrasonic waves, and provide a stable vibration source for the active acoustic waveguide propagating along the pipe wall. The sound emitter unit and the inspection well wall of the drainage pipeline are mechanically coupled through the coupling device, the loss of kinetic energy in the transmission process is reduced, efficient coupling of mechanical vibration to the pipe wall is realized, signal attenuation or distortion caused by poor coupling is avoided, and stable propagation of infrasonic waves along the pipe wall to the receiving end is ensured.

[0019] In an alternative embodiment, the detection module comprises a signal preprocessing unit and a damage diagnosis algorithm unit.

[0020] The signal preprocessing unit is used for preprocessing the initial digital vibration signal to obtain a target digital vibration signal, and sending the target digital vibration signal to the damage diagnosis algorithm unit; the damage diagnosis algorithm unit is used for processing the target digital vibration signal through a Fourier transform method and a correlation coefficient analysis method, and determining a structural defect detection result of the drainage pipeline.

[0021] The drainage pipeline structural defect detection system provided by the application can preprocess the initial digital vibration signal through the signal preprocessing unit, improve the signal quality, eliminate interference factors for subsequent algorithm analysis, and avoid misjudgment caused by poor original signal quality.

[0022] In an optional embodiment, the damage diagnosis algorithm unit comprises a feature analysis subunit, a calculation subunit and a detection subunit.

[0023] The feature analysis subunit is used for processing the initial digital vibration signal and the coded infrasound wave signal through the Fourier transform method to obtain a frequency domain analysis result, and sending the frequency domain analysis result to the detection subunit; the calculation subunit is used for calculating the initial digital vibration signal and the coded infrasound wave signal through the correlation coefficient analysis method to obtain a correlation coefficient value, and sending the correlation coefficient value to the detection subunit; and the detection subunit is used for determining the structural defect detection result of the drainage pipeline based on the frequency domain analysis result and the correlation coefficient value.

[0024] The drainage pipeline structural defect detection system provided by the application can convert the time domain signal into a frequency domain signal by using the Fourier transform method in the feature analysis subunit, quickly identify whether the received signal has a main frequency shift, provide a frequency domain basis for judging whether the pipeline has a defect, and make up for the deficiency that the traditional time domain analysis cannot intuitively identify frequency abnormalities. Further, in the calculation subunit, the correlation coefficient value is calculated through the correlation coefficient analysis, which can quantify the signal similarity and exclude non-defect factors such as noise, provide a clear numerical basis for defect judgment, and avoid the problems of strong subjectivity and large error of traditional manual waveform comparison. Finally, in the detection subunit, the structural defect detection result of the drainage pipeline is determined by combining the frequency domain analysis result and the correlation coefficient value, which avoids misjudgment caused by single feature analysis, greatly improves the reliability of the detection result, and ensures accurate identification of the structural defect of the pipeline.

[0025] In an optional embodiment, the detection module further comprises a time synchronization unit configured to control the infrasound sound generation module and the infrasound signal receiving module to operate at the same time.

[0026] The drainage pipeline structural defect detection system provided by the application controls the infrasound sound emission module and the infrasound signal receiving module to operate at the same time through the time synchronization unit, ensures the consistency of the timing of the signal emitted by the infrasound sound emission module and the signal collected by the infrasound signal receiving module, avoids the calculation deviation of the signal propagation time caused by the time difference, provides a timing reference for accurately calculating the infrasound wave propagation speed and positioning the defect position, and solves the problem of fuzzy detection and positioning in the prior art.

[0027] In a second aspect, the application provides a drainage pipeline structural defect detection method, which is used for the drainage pipeline structural defect detection system in the first aspect or any of the corresponding embodiments thereof.

[0028] The coded infrasound wave signal is constructed, the coded infrasound wave signal is used for infrasound wave emission and processing, a low-frequency mechanical vibration signal is obtained, the low-frequency mechanical vibration signal is transmitted in the drainage pipeline, the low-frequency mechanical vibration signal of the drainage pipeline is detected and an initial digital vibration signal is determined, and the structural defect detection result of the drainage pipeline is determined through Fourier transform method and correlation coefficient analysis method based on the initial digital vibration signal and the coded infrasound wave signal.

[0029] The drainage pipeline structural defect detection method provided by the application actively constructs and generates the coded infrasound wave signal, ensures that the signal has stable frequency and amplitude characteristics, can effectively distinguish effective signals from environmental noise compared with traditional uncoded signals, and solves the problem that the signal is easily submerged under complex working conditions of the sewage pipeline. Further, the active emission of the mechanical vibration signal forms a stable active acoustic waveguide along the pipe wall, which is not affected by the water flow state and sludge accumulation in the pipeline, covers the pipe section that cannot be reached by traditional passive detection, and meets the detection requirements of a large range. Further, the vibration signal propagating along the pipe wall is captured and converted into a digital signal, ensuring the integrity and accuracy of the original data, providing reliable input for subsequent analysis, and avoiding missed detection caused by signal loss or distortion. Further, the Fourier transform method and the correlation coefficient analysis method are combined for structural defect detection, which can accurately identify whether the pipeline is damaged, avoid the high false rejection rate of traditional single algorithms, and finally accurately output whether the pipeline is damaged, thereby meeting the accuracy requirements of the drainage pipeline structural defect detection under complex working conditions. Therefore, by implementing the application, the problem that the traditional acoustic detection technology cannot meet the effective identification requirements of the damage and leakage problem of the urban underground sewage pipe network under complex working conditions is solved.

[0030] In a third aspect, the application provides a computer readable storage medium, which stores computer instructions for causing a computer to execute the drainage pipeline structural defect detection method of the second aspect.

[0031] In a fourth aspect, the present application provides a computer program product comprising computer instructions for causing a computer to execute the sewer structural defect detection method of the second aspect. BRIEF DESCRIPTION OF DRAWINGS

[0032] In order to more clearly illustrate the technical solutions of the specific embodiments or the prior art, the drawings needed to be used in the specific embodiments or the prior art description will be briefly introduced. Obviously, the drawings in the following description are some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor.

[0033] Figure 1 is a structural block diagram of a sewer structural defect detection system according to an embodiment of the present application;

[0034] Figure 2 is a flowchart of a sewer structural defect detection method according to an embodiment of the present application;

[0035] Figure 3 is a flowchart of a sewer structural defect detection method based on active acoustic guided waves according to an embodiment of the present application;

[0036] Figure 4 is a sewer area diagram according to an embodiment of the present application;

[0037] Figure 5 is a sewer area diagram after data collection according to an embodiment of the present application;

[0038] Figure 6 is a diagram of installation of a sound emitting and receiving device of a pipe to be detected according to an embodiment of the present application;

[0039] Figure 7 is a diagram of an encoded infrasound signal according to an embodiment of the present application;

[0040] Figure 8 is a comparison analysis diagram of a measured value and an ideal value according to an embodiment of the present application;

[0041] Figure 9 is a hardware structure diagram of a computer device according to an embodiment of the present application. DETAILED DESCRIPTION

[0042] In order to make the purposes, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are some but not all of the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by a person of ordinary skill in the art without creative work fall within the protection scope of the present application.

[0043] The embodiment of the present application provides a sewer pipeline structural defect detection system method. The controller actively constructs and generates coded infrasound wave signals and transmits the infrasound wave signals. Meanwhile, the Fourier transform method and the correlation coefficient analysis method are combined for structural defect detection to accurately identify whether the pipeline is damaged, thereby meeting the effective identification demand of the damage and leakage problem of the urban underground sewage pipe network under complex working conditions.

[0044] In the present embodiment, a sewer pipeline structural defect detection system is provided, as shown in Figure 1 The sewer pipeline structural defect detection system 1 comprises a controller 11, an infrasound sound generation module 12, an infrasound signal receiving module 13 and a detection module 14.

[0045] The infrasound sound generation module 12 and the infrasound signal receiving module 13 are arranged in different inspection wells at different ends of the sewer pipeline, that is, the infrasound sound generation module 12 is arranged in an inspection well at one end of the sewer pipeline, and the infrasound signal receiving module 13 is arranged in an inspection well at the other end.

[0046] Further, the infrasound signal receiving module 13 is fixed to the inner wall of the target inspection well by a sound-conducting adhesive.

[0047] Further, the basic data of the sewer system GIS map, pipe material, pipe diameter, pipe length, flow direction, elevation, inspection well number and coordinates of the sewer pipeline can be collected. Combined with the topological connection relationship and the actual operation condition of the sewer pipeline, the infrasound wave propagation path and the inspection well distribution along the way are determined, and then the arrangement of the infrasound sound generation module 12 and the infrasound signal receiving module 13 is determined.

[0048] Optionally, the controller 11 is configured to construct a coded infrasound wave signal and send the coded infrasound wave signal to the infrasound signal receiving module 13 and the detection module 14.

[0049] The linear frequency modulation method can be used to code the infrasound wave signal, thereby improving the recognizability, anti-interference and detection accuracy of the signal, effectively distinguishing the infrasound wave signal from the background noise in engineering practice, and enhancing the damage diagnosis capability.

[0050] Further, the controller 11 comprises an acquisition unit 111 and a construction unit 112.

[0051] First, in the acquisition unit 111, a time signal sequence is acquired and sent to the construction unit 112.

[0052] In the complex environment of urban drainage pipes, in order to accurately propagate and identify the subsequent coded infrasound wave signals, a precise and continuous time sequence needs to be determined as the basis for calculating the signal amplitude change over time, thereby ensuring the accuracy and identifiability of the coded signal, and laying the foundation for improving the transmission reliability of infrasound waves in complex pipe environments.

[0053] Specifically, the time sequence range can be determined as 0 to based on the single frequency sweep duration of the infrasound wave signal and the sampling frequency .

[0054] Further, the sampling points, i.e. sampling times per second, for a total duration of seconds, and the corresponding time signal sequence is generated, as shown in the following relationship (1):

[0055] (1)

[0056] In the formula: represents the sampling frequency; represents the signal duration.

[0057] Further, the obtained time signal sequence is sent to the construction unit 112, so that the construction unit 112 constructs the coded infrasound wave signal based on the time sequence.

[0058] Secondly, in the construction unit 112, the coded infrasound wave signal is constructed according to the time signal sequence.

[0059] Specifically, the time signal sequence provided by the acquisition unit is used, and combined with the coding method of linear frequency modulation, an infrasound wave signal with a specific frequency variation rule can be generated.

[0060] For example, according to the detection requirements of the drainage pipe, the parameters of the coded infrasound wave signal can include amplitude, sweep start frequency, sweep bandwidth, sweep rate, etc.

[0061] Further, the time point in the time signal sequence can be substituted into the linear frequency modulation signal formula to generate the corresponding waveform function of the linear frequency modulation signal, i.e. the coded infrasound wave signal , as shown in the following relationship (2):

[0062] (2)

[0063] wherein: represents an amplitude; represents a sweep start frequency; represents a sweep bandwidth; represents a sweep rate.

[0064] Further, in order to avoid interference between adjacent infrasound signals, a silent interval of the coded infrasound signal may also be set, and the corresponding coded infrasound signal is obtained.

[0065] Further, through the linear frequency modulation coded infrasound signal, the recognizability, anti-interference and detection accuracy in the complex environment of urban drainage pipes can be improved, the infrasound signal can be effectively distinguished from the background noise, and the diagnosis ability for pipe damage can be enhanced.

[0066] Optionally, the infrasound sound emitting module 12 is configured to emit and process the infrasound signal by using the coded infrasound signal to obtain the low-frequency mechanical vibration signal.

[0067] The low-frequency mechanical vibration signal is transmitted in the drainage pipe.

[0068] Further, the infrasound sound emitting module 12 comprises a transmission controller 121, a power amplifier driving unit 122, a sound emitter unit 123 and a coupling device 124.

[0069] The sound emitter unit 123 adopts a piezoelectric ceramic sheet stacking structure, which can realize efficient conversion of electrical signals and mechanical vibrations; the coupling device 124 is composed of a flexible sound guide material and an elastic compression arm, which can ensure that the sound emitter unit 123 is closely attached to the pipe wall surface, that is, the sound emitter unit 123 is mechanically coupled with the inspection well wall of the drainage pipe through the coupling device.

[0070] Specifically, the sound emitter unit 123 is arranged close to the inspection well wall, and the coupling device 124 composed of a flexible sound guide material and an elastic compression arm is used to maintain stable mechanical coupling between the sound emitter unit 123 and the inspection well wall, so as to ensure efficient transmission of mechanical vibrations into the pipe body.

[0071] Firstly, when the transmission controller 121 receives the coded infrasound signal, the coded infrasound signal is used to emit the low-frequency programming signal.

[0072] Specifically, the transmission controller 121 can receive the coded infrasound signal through a wired interface, and analyze the sweep band, silent band timing, frequency variation range, amplitude and other parameters of the signal.

[0073] Further, the received coded infrasound wave signal can be converted into a low-frequency programming electrical signal (such as a TTL level signal) recognizable by the power amplifier driving unit 122, ensuring that the timing logic (sweeping / silencing switching) and spectral characteristics (frequency, amplitude) of the signal are not distorted.

[0074] Further, the low-frequency programming electrical signal is output to the power amplifier driving unit, and at the same time, the internal synchronous clock can also be started to record the signal transmission timestamp, providing a basis for subsequent time synchronization with the infrasound signal receiving module 13.

[0075] Further, when the transmission controller 121 receives the coded infrasound wave signal, it analyzes the signal characteristics and generates a low-frequency programming electrical signal that can drive the power amplifier unit, ensuring accurate transmission of signal timing and spectral parameters.

[0076] Secondly, when the power amplifier driving unit 122 receives the low-frequency programming signal, it amplifies the low-frequency programming signal to obtain a high-frequency programming signal and sends the high-frequency programming signal to the sound generator unit 123.

[0077] Specifically, when the power amplifier driving unit 122 receives the low-frequency programming signal, it can amplify the low-level signal to a high-power signal (such as a 10V high-level signal) through an internal power amplifier circuit (such as a class-B complementary symmetrical power amplifier circuit), and the frequency range (5~25Hz) and waveform characteristics of the signal remain unchanged during the amplification process, avoiding signal distortion.

[0078] Further, the power amplifier driving unit 122 amplifies the low-level low-frequency programming signal output by the transmission controller 121 to a high-power signal (i.e., a high-frequency programming signal, where "high frequency" refers to high power, not high frequency), providing sufficient driving power for the sound generator unit 123, ensuring that the mechanical vibration intensity meets the propagation requirements.

[0079] Further, the power amplifier driving unit 122 sends the amplified high-power high-frequency programming signal to the sound generator unit, driving the sound generator unit 123 to perform electrical-mechanical conversion.

[0080] Finally, in the sound generator unit 123, the high-frequency programming signal is converted to obtain a low-frequency mechanical vibration signal, and the low-frequency mechanical vibration signal is sent to the coupling device 124 to transmit the low-frequency mechanical vibration signal through the coupling device 124 in the drainage pipeline.

[0081] Specifically, the sound generator unit 123 adopts a piezoelectric ceramic sheet stacking structure, so when the sound generator unit 123 receives the high-frequency programming information, it can use the piezoelectric ceramic "electrical excitation generates mechanical deformation" characteristic to convert the electrical signal into low-frequency mechanical vibration, and the vibration amplitude is proportional to the electrical signal amplitude, which can ensure stable vibration intensity.

[0082] Further, the vibration output end of the sounder unit 123 is in direct contact with the flexible sound-conducting material of the coupling device 124, and the low-frequency mechanical vibration is transmitted to the coupling device 124, and is ready to be transmitted into the pipe wall through the coupling device 124.

[0083] Further, the coupling device 124 acts as a vibration transmission bridge, and can ensure that the mechanical vibration of the sounder is efficiently and losslessly transmitted to the pipe wall through mechanical structure design, avoiding the attenuation of vibration energy in the air gap.

[0084] For example, the elastic compression arm of the coupling device 124 can be expanded to make the flexible sound-conducting material (such as silicone material) tightly adhere to the inspection well wall, and a stable pressure (such as 50N) is applied through the elastic compression arm to ensure that the flexible sound-conducting material has no gap with the well wall.

[0085] Further, the low-frequency mechanical vibration transmitted by the sounder unit 123 is conducted to the inspection well wall through the flexible sound-conducting material, and then transmitted to the drainage pipe wall by the well wall, forming a low-frequency mechanical vibration signal (active acoustic waveguide) propagating along the pipe wall, and the energy attenuation rate during vibration propagation is controlled within 5%, which can ensure long-distance propagation.

[0086] Further, based on the piezoelectric effect, the sounder unit 123 can provide a physical vibration source for the propagation of infrasound waves along the pipe wall by converting the high-power electrical signal output by the power amplifier driving unit 122 into low-frequency mechanical vibration consistent with the frequency of the coded signal.

[0087] Optionally, the infrasound signal receiving module 13 is configured to detect the low-frequency mechanical vibration signal of the drainage pipe and determine an initial digital vibration signal, and send the initial digital vibration signal to the detection module 14.

[0088] The infrasound signal receiving module 13 includes an inductive receiver array 131 and a signal acquisition unit 132.

[0089] Further, the inductive receiver array 131 is composed of a plurality of high-sensitivity vibration sensors, which are arranged in the inspection well at the end of the pipe, and can capture the low-frequency mechanical vibration signal propagating along the pipe wall in real time and convert the vibration physical quantity into an analog electrical signal.

[0090] First, the inductive receiver array 131 detects the low-frequency mechanical vibration signal of the drainage pipe, and when the low-frequency mechanical vibration signal is detected, the low-frequency mechanical vibration signal is sent to the signal acquisition unit 132.

[0091] Specifically, 3-5 inductive sensors (such as piezoelectric vibration sensors) can be uniformly fixed on the inner wall of the inspection well (on the same side of the pipe wall as the sounder module) through sound-conducting adhesive, and the sensor spacing is about 10 cm, ensuring that the vibration propagation path of the pipe wall is covered.

[0092] Further, when the low-frequency mechanical vibration signal propagates along the pipe wall to the receiver position, the sensors in the inductive receiver array 131 perceive the slight vibration of the pipe wall (vibration displacement amount of about 1-10 μm) and convert the vibration displacement into corresponding analog electrical signals (voltage range of 0-5V), i.e. low-frequency mechanical vibration signals.

[0093] Further, the analog electrical signals output by each sensor in the inductive receiver array 131 are collected through internal cables to the signal input end of the signal acquisition unit 132, ensuring that all vibration signals are transmitted synchronously.

[0094] Secondly, the signal acquisition unit 132 converts the low-frequency mechanical vibration signal to obtain an initial digital vibration signal, and sends the initial digital vibration signal to the detection module 14.

[0095] Specifically, the signal acquisition unit 132 can convert the analog vibration signal output by the inductive receiver array 131 into a digital signal (initial digital vibration signal) through an analog-to-digital conversion technology, and transmit it to the detection module 14 after adding a time stamp, thereby realizing digital storage and analysis of the vibration signal.

[0096] For example, the signal acquisition unit 132 can pre-process (such as filtering and amplifying) the received analog electrical signal, i.e. low-frequency mechanical vibration signal, filter out the sensor's own noise (<1 Hz), and adjust the signal amplitude to the ADC adaptation range (0-3V).

[0097] Further, the signal acquisition unit 132 can start the embedded 16-bit ADC to sample the conditioned analog signal at a sampling frequency of 1000 Hz, convert the continuous analog signal into discrete digital data (i.e. initial digital vibration signal), and store each sampling point in binary format (such as 0-65535 value range).

[0098] Further, the signal acquisition unit 132 can also add a precise time stamp (accuracy of 1 ms) to each sampling point based on the embedded GPS clock module, to ensure that the initial digital vibration signal is time-aligned with the coded signal of the infrasound emission module 12.

[0099] Further, the signal acquisition unit 132 can transmit the initial digital vibration signal (including time stamp) to the detection module 14 in real time through a wireless communication module (such as LoRa). The data transmission rate is ≥1 Mbps to ensure no data loss.

[0100] Optionally, the detection module 14 is configured to determine the structural defect detection result of the drainage pipeline based on the initial digital vibration signal and the coded infrasound wave signal through Fourier transform method and correlation coefficient analysis method.

[0101] The Fourier transform method is a mathematical method for converting time-domain signals into frequency-domain signals. In the time domain, the signal is represented as a waveform that changes over time, reflecting the characteristics of the signal in the time dimension. Through Fourier transform, the time-domain signal can be decomposed into the superposition of sine and cosine components of different frequencies, showing the characteristics of the signal in the frequency dimension, i.e., obtaining the frequency spectrum of the signal.

[0102] Further, the correlation coefficient is an index for measuring the degree of linear correlation between two variables, with a value range of -1 to 1. In signal analysis, the correlation coefficient analysis method calculates the similarity between the received signal and the reference signal (here, the coded infrasound signal) to determine the relationship between the two.

[0103] Further, the detection module 14 includes a signal preprocessing unit 141, a damage diagnosis algorithm unit 142, and a time synchronization unit 143.

[0104] First, the signal preprocessing unit 141 is used to preprocess the initial digital vibration signal to obtain a target digital vibration signal, and the target digital vibration signal is sent to the damage diagnosis algorithm unit 142.

[0105] Specifically, after receiving the initial digital vibration signal, the signal preprocessing unit 141 can use the moving average method to process the initial digital vibration signal, calculate the mean value (such as the digital value corresponding to 0.5V), and subtract the mean value from each sampling point value to eliminate the direct current component in the signal and make the signal baseline return to zero.

[0106] Further, the signal preprocessing unit 141 can also use a FIR digital filter to set the passband frequency to 10-30Hz, filter out low-frequency ground vibration (<10Hz) and high-frequency electronic noise (>30Hz), and retain the effective vibration signal within the coded signal frequency band.

[0107] Further, the signal preprocessing unit 141 can also calculate the signal propagation time difference based on the time stamp of the initial digital vibration signal and the transmission time stamp of the coded signal (such as a pipe segment length of 30m and a wave speed of 300m / s, with a time difference of about 0.1s), and shift the received signal on the time axis by the corresponding time difference, thereby achieving accurate alignment with the coded signal, and finally obtaining the preprocessed target digital vibration signal.

[0108] Further, the signal preprocessing unit 141 can also store the target digital vibration signal in CSV format and send it to the damage diagnosis algorithm unit 142 through the internal data bus.

[0109] Secondly, in the damage diagnosis algorithm unit 142, the target digital vibration signal is processed by the Fourier transform method and the correlation coefficient analysis method, and the structural defect detection result of the drainage pipeline is determined.

[0110] Specifically, the damage diagnosis algorithm unit 142 can analyze the frequency characteristics of the signal through the frequency domain (Fourier transform) and analyze the similarity of the signal through the time domain (correlation coefficient), comprehensively judge whether the pipeline has structural defects according to the two-dimensional results, and output the detection conclusion, that is, the structural defect detection result of the drainage pipeline.

[0111] Among them, the damage diagnosis algorithm unit 142 includes a feature analysis subunit 1421, a calculation subunit 1422, and a detection subunit 1423.

[0112] Firstly, in the feature analysis subunit 1421, based on the initial digital vibration signal and the coded infrasound signal, the Fourier transform method is used to process the frequency domain analysis result, and the frequency domain analysis result is sent to the detection subunit 1423.

[0113] Specifically, taking the coded infrasound signal as the reference, the initial digital vibration signal is converted from the “time-amplitude” time domain dimension to the “frequency-amplitude” frequency domain dimension by Fourier transform, and then the frequency characteristics (such as the main frequency and the frequency distribution) of the signal are extracted, and it is judged whether the frequency component is abnormal due to pipeline defects.

[0114] For example, the fast Fourier transform (FFT) algorithm can be used to convert the initial digital vibration signal to the frequency domain, that is, the continuous vibration signal in the time domain (such as a 0~12s, 1000Hz sampled digital signal) is decomposed into the superposition of different frequency components, and a “frequency-amplitude” frequency domain curve is obtained.

[0115] Further, the main frequency value (that is, the frequency point with the maximum amplitude) of the frequency domain curve can be extracted, and the change trajectory of the main frequency with time can be tracked.

[0116] Further, the main frequency range of the initial digital vibration signal and the coded infrasound signal (for example, the coded signal is 5~25Hz) can be compared, and the time proportion and the maximum deviation amplitude of the main frequency exceeding the range can be counted.

[0117] Further, the extracted main frequency trajectory, deviation amplitude, and frequency distribution histogram can be arranged into a frequency domain analysis report, that is, the frequency domain analysis result, which serves as the frequency domain basis for subsequent defect judgment.

[0118] Further, the feature analysis subunit 1421 sends the obtained frequency domain analysis result to the detection subunit 1423.

[0119] Secondly, the correlation coefficient value is obtained through correlation coefficient analysis method based on the initial digital vibration signal and the coded infrasound wave signal in the calculation subunit 1422, and the correlation coefficient value is sent to the detection subunit 1423.

[0120] Specifically, the calculation subunit 1422 can calculate the similarity degree of the initial digital vibration signal and the coded infrasound wave signal through the correlation coefficient formula, and reflect whether the signal energy attenuates and the waveform distorts due to the pipeline defect in the form of a numerical value (0~1), to provide a time-domain quantitative basis for defect judgment, as shown in the following relationship (3):

[0121] (3)

[0122] In the formula: is a correlation coefficient function, which represents the similarity measurement value of two signals (the initial digital vibration signal and the coded infrasound wave signal) at a delay time, that is, the correlation coefficient value (the greater, the more similar); represents a time-domain delay variable, which is used to compare the alignment degree between two signals, and its value is approximately equal to the signal propagation distance divided by the wave speed, with the unit of second (s); represents the initial digital vibration signal.

[0123] Further, the calculation subunit 1422 sends the calculated correlation coefficient value to the detection subunit 1423.

[0124] Finally, the structural defect detection result of the drainage pipeline is determined in the detection subunit 1423 based on the frequency domain analysis result and the correlation coefficient value.

[0125] Specifically, the detection subunit 1423 can comprehensively analyze the frequency domain result (main frequency shift condition) of the feature analysis subunit 1421 and the correlation coefficient value (time-domain similarity) of the calculation subunit 1422, and finally determine whether the pipeline has structural defects and the approximate position of the defects according to the preset judgment rule, to avoid misjudgment caused by single-dimensional analysis.

[0126] For example, the preset judgment rule is a double abnormality judgment principle, that is, the frequency domain analysis shows that the main frequency shift is ≥±1 Hz (or exceeds the frequency band 5~25 Hz of the coded signal), and the correlation coefficient value is <0.995, and both conditions are met to determine that there is a defect; only one abnormality or no abnormality is determined to be normal.

[0127] Further, if the frequency domain analysis result is “no main frequency shift”, and the correlation coefficient value is ≥0.995, it is determined that the corresponding pipe section has no structural defects.

[0128] Further, if the frequency domain analysis result is "main frequency deviation ≥ ± 1Hz" (such as the main frequency of the signal received by a certain pipe section continuously at 27Hz), and the correlation coefficient value is 0.995, it is determined that the corresponding pipe section has structural defects such as damage, misalignment, etc.

[0129] Further, if only frequency domain anomalies or only time domain anomalies (such as main frequency deviation but normal correlation coefficient, which may be temporary noise interference), it is marked as "suspected abnormality" and needs to be re-detected and verified.

[0130] Further, the specific pipe section where the defect is located can be further determined in combination with the device layout position, and a structural defect detection result containing "pipe section number, defect determination conclusion, frequency domain analysis data, correlation coefficient value, and recommended re-inspection time" can be generated.

[0131] Further, the infrasound sound emitting module 12 and the infrasound signal receiving module 13 can also be controlled by the time synchronization unit 143 to operate at the same time.

[0132] Specifically, the GPS clock module built-in in the time synchronization unit 143 can be used to provide a unified time reference for the infrasound sound emitting module 12 and the infrasound signal receiving module 13, eliminate the signal timing misalignment caused by clock deviation, and ensure the time synchronization of the sound emitting and receiving links.

[0133] For example, the GPS clock module built-in in the time synchronization unit 143 can be used to receive GPS satellite signals in real time and obtain high-precision UTC time (time accuracy ≤ 1ms) as the unified time reference of the system.

[0134] Further, the GPS reference time can be sent to the transmission controller 121 of the infrasound sound emitting module 12 and the signal acquisition unit 132 of the infrasound signal receiving module through a wireless synchronization protocol (such as NTP network time protocol).

[0135] Further, after receiving the synchronization signal, the transmission controller 121 and the signal acquisition unit 132 automatically calibrate the internal real-time clock (RTC), so that the clock error of the two is controlled within 1ms.

[0136] Further, the time synchronization unit 143 can send a "signal transmission trigger instruction" to the transmission controller 121, and the instruction contains the accurate transmission start time (such as T0 time).

[0137] At the same time, the time synchronization unit 143 can send a "signal transmission trigger instruction" to the signal acquisition unit 132 to ensure that the signal acquisition unit 132 starts data acquisition at T0 time, thereby avoiding signal missing or timing misalignment caused by different starting times of sound emission and acquisition.

[0138] Further, in the detection process, the time synchronization unit 143 can also receive the clock state information fed back by the transmission controller 121 and the signal collection unit 132 in real time, and if it is found that the clock deviation of a certain module exceeds 1 ms, the synchronization signal is immediately retransmitted for calibration to ensure that the time sequences of the two are consistent throughout the detection process.

[0139] The drainage pipeline structural defect detection system provided in the embodiment actively constructs and generates coded infrasound wave signals through the controller, ensures that the signals have stable frequency and amplitude characteristics, can effectively distinguish effective signals from environmental noise compared with traditional non-coded signals, and solves the problem that signals are easily submerged in complex working conditions of sewage pipelines. At the same time, the coded signals are synchronously transmitted to the detection module, providing a "reference signal" for subsequent comparative analysis of received signals, avoiding signal abnormality judgment deviation caused by the absence of a reference. Further, the infrasound signal emitting module uses the coded infrasound wave signals for infrasound wave emission and processing, and through internal signal processing and mechanical coupling design, the low-frequency mechanical vibration signals are stably propagated along the pipe wall, reducing energy attenuation and covering long-distance pipe sections that are difficult to reach by traditional passive detection. At the same time, the actively emitted vibration signals are not affected by sludge and gas-liquid two-phase flow in the pipeline, solving the problem of weak signals easily submerged in noise in gravity flow sewage pipelines. Further, the low-frequency mechanical vibration signals of the drainage pipeline are detected by the infrasound signal receiving module, which can completely obtain the dynamic changes of the signals propagating along the pipeline and avoid missing local defects. At the same time, the analog signals are converted into initial digital signals, reducing interference and distortion in the transmission process, providing high-quality raw data for subsequent data analysis, and solving the problem of low data reliability of traditional analog signals. Further, the Fourier transform can extract the main frequency offset characteristics and identify the frequency component changes caused by defects, and the correlation coefficient analysis can quantify the signal similarity and exclude non-defect factors such as noise, and the combination of the two avoids the high false rejection rate of traditional single algorithms, and finally accurately outputs whether the pipeline is damaged, meeting the accuracy requirements of drainage pipeline structural defect detection in complex working conditions. Therefore, by implementing the present application, the problem that the traditional acoustic detection technology cannot meet the effective identification requirements of the damage and leakage problem of urban underground sewage pipe network in complex working conditions is solved.

[0140] According to the embodiment of the present application, a drainage pipeline structural defect detection method embodiment is provided. It should be noted that the steps shown in the flowchart of the accompanying drawings can be executed in a computer system such as a set of computer executable instructions, and although the logical order is shown in the flowchart, in some cases, the steps shown or described can be executed in a different order from here.

[0141] In the present embodiment, a drainage pipeline structural defect detection method is provided, which can be used in the drainage pipeline structural defect detection system 1 provided in the above-mentioned embodiments of the present application,Figure 2 is a flowchart of a method for detecting structural defects of a drainage pipeline according to an embodiment of the present application, as shown in the figure, the flow includes the following steps: Figure 2

[0142] Step S201, constructing an encoded infrasound wave signal.

[0143] The specific process can refer to the function description of the controller 11 in the drainage pipeline structural defect detection system 1 in the above embodiments of the present application, which will not be repeated here.

[0144] Step S202, using the encoded infrasound wave signal to emit and process infrasound waves to obtain a low-frequency mechanical vibration signal.

[0145] The low-frequency mechanical vibration signal is transmitted in the drainage pipeline.

[0146] The specific process can refer to the function description of the infrasound sound emitting module 12 in the drainage pipeline structural defect detection system 1 in the above embodiments of the present application, which will not be repeated here.

[0147] Step S203, detecting the low-frequency mechanical vibration signal of the drainage pipeline and determining an initial digital vibration signal.

[0148] The specific process can refer to the function description of the infrasound signal receiving module 13 in the drainage pipeline structural defect detection system 1 in the above embodiments of the present application, which will not be repeated here.

[0149] Step S204, based on the initial digital vibration signal and the encoded infrasound wave signal, processing by Fourier transform method and correlation coefficient analysis method to determine the structural defect detection result of the drainage pipeline.

[0150] The specific process can refer to the function description of the detection module 14 in the drainage pipeline structural defect detection system 1 in the above embodiments of the present application, which will not be repeated here.

[0151] ​The drainage pipeline structural defect detection method provided by the embodiment ensures that the signal has stable frequency and amplitude characteristics, can effectively distinguish effective signals from environmental noise compared with traditional non-coding signals, and solves the problem that the signal is easily submerged under complex working conditions of the sewage pipeline. Further, by actively emitting mechanical vibration signals, a stable active acoustic waveguide is formed along the pipe wall, which is not affected by the water flow state and sludge accumulation in the pipeline, covers the pipe section that is difficult to reach by traditional passive detection, and meets the detection needs of a large range. Further, by capturing the vibration signals propagating along the pipe wall and converting them into digital signals, the integrity and accuracy of the original data are ensured, providing reliable input for subsequent analysis and avoiding missed detection caused by signal loss or distortion. Further, by combining the Fourier transform method and the correlation coefficient analysis method for structural defect detection, it can accurately identify whether the pipeline is damaged, avoiding the problem of high false positive rate of traditional single algorithms, and finally accurately outputting whether the pipeline is damaged, meeting the accuracy requirements of drainage pipeline structural defect detection under complex working conditions. Therefore, by implementing the present application, the problem that the traditional acoustic detection technology cannot meet the effective identification needs of the damage and leakage problem of the urban underground sewage pipe network under complex working conditions is solved.

[0152] In an example, an active acoustic waveguide-based drainage pipeline structural defect detection device is provided, comprising: an infrasound sound emission module, an infrasound signal receiving module, and a data analysis processing and anomaly recognition module.

[0153] The infrasound sound emission module is responsible for actively exciting infrasound waves, which propagate stably along the pipe wall. It includes four functional units: a transmission controller, a power amplifier driving unit, a sound emitter unit, and a coupling device. First, the transmission controller serves as the main control unit of the system, responsible for generating programmable low-frequency signals and controlling timing and spectral parameters. The controller supports remote task triggering and synchronous clock access. The transmission signal is amplified by the power amplifier driving unit to enhance the low-level signal to a high-power signal that can drive the sound emitter. The power amplifier module has good low-frequency response characteristics and signal fidelity, ensuring that the mechanical vibration output by the sound emitter is not distorted. The sound emitter unit uses a stacked structure of piezoelectric ceramic sheets, which converts the power amplifier signal into low-frequency mechanical vibration after receiving it. Finally, the mechanical vibration is efficiently transmitted to the pipe wall through the coupling device. The coupling device is composed of flexible sound guide material and elastic compression arms, ensuring that the sound emitter is tightly attached to the pipe wall surface.

[0154] The infrasound signal receiving module bears the function of capturing the dynamic response of the infrasound wave in the propagation process of the pipe wall, and is the direct carrier of the pipe structure state perception. Its internal includes two parts: an induction receiver array and a signal acquisition system. The induction receiver array is composed of multiple distributed sensors for detecting the micro-vibration response of the pipe wall. The sensor can effectively perceive the amplitude attenuation, waveform distortion and echo information in the propagation of the infrasound wave. Each receiver is connected to the signal acquisition system by wireless means, and the signal acquisition system is embedded with an analog-to-digital converter (ADC) for converting analog signals into digital waveforms and transmitting them to the data analysis and abnormality identification module for subsequent processing. Through the implementation of this module, the system can realize multi-point, synchronous and high-fidelity acquisition of the pipe wall propagation infrasound signal, providing data support for damage and leakage positioning.

[0155] The data analysis and abnormality identification module is responsible for data synchronization, feature extraction and abnormality diagnosis of the received signal. The module contains three types of functional systems in turn: a time synchronization system, a signal preprocessing system and a damage diagnosis algorithm system. The time synchronization system ensures that all sound emitters and receivers operate at the same time, avoiding time difference interference wave speed. The system uses a GPS clock module to complete the unified calibration of all nodes before detection starts through the scheduling of the central control, ensuring that the error in the system does not exceed 1 ms. The signal preprocessing system cleans and reconstructs the original collected data, and the main steps include removing DC drift, band-pass filtering, time domain registration, etc., to improve signal quality and defect recognizability. The damage diagnosis algorithm system mainly includes two core modules: Fourier transform and correlation coefficient analysis. First, the Fourier transform is used to analyze the frequency domain of the infrasound signal received by the monitoring point, which is suitable for extracting frequency components and analyzing the frequency shift phenomenon. At the same time, the correlation coefficient analysis module is used to calculate the similarity between the received signal and the sound signal. When the received signal does not match the sound signal in terms of frequency shift, energy attenuation and correlation peak position, it is considered that the pipe section has structural defects such as damage, misalignment, etc.; otherwise, it is determined that the structure is normal.

[0156] Further, as shown in Figure 3 , the specific implementation steps of the active acoustic waveguide-based structural defect detection method for drainage pipes are as follows:

[0157] Step 1: Collect the data of the drainage pipe to be detected.

[0158] For drainage pipes suspected to have structural defects such as damage and misalignment, collect their basic data, including drainage system GIS map, pipe material, pipe diameter, pipe length, flow direction, elevation, inspection well number and coordinates, etc. Combined with the topological connection relationship and actual operating conditions of the drainage pipe to be detected, the infrasound wave propagation path and the distribution of inspection wells along the way are determined to provide a basis for subsequent infrasound equipment layout.

[0159] Step 2: infrasound wave emitting and receiving device arrangement.

[0160] In the manhole at one end of the pipeline to be detected, an infrasound wave emitting module is arranged, and the emitter unit is arranged close to the wall part of the manhole. A coupling device composed of a flexible sound guide material and an elastic compression arm is used to make the emitter and the manhole wall body maintain stable mechanical coupling, so as to ensure that the mechanical vibration is efficiently transmitted into the pipe body. In the manhole at the other end of the pipeline to be detected, an infrasound wave receiving module is arranged, and the receiver is fixed on the inner wall of the target manhole through a sound guide adhesive and connected to a portable wireless signal collection system.

[0161] Step 3: Infrasound wave signal coding.

[0162] In order to improve the reliability of transmission and reception of infrasound waves in the complex environment of urban drainage pipeline systems, the present application codes the infrasound wave signal. The present application uses linear frequency modulation to code the infrasound wave signal, thereby improving the recognizability, anti-interference and detection accuracy of the signal, so that the infrasound wave signal and background noise can be effectively distinguished in engineering practice, and the damage diagnosis capability is enhanced. The coding form is shown in the above relationship (2).

[0163] Step 4: Infrasound wave signal emission, reception and structural defect detection.

[0164] The power amplifier unit amplifies the coded infrasound signal in step 3 , and forms coded infrasound waves propagating along the pipe wall through the sound emitting unit. After the receiver receives the infrasound wave signal, it is first converted into a digital signal through an analog-to-digital converter (ADC), and then transmitted to a data analysis and abnormality recognition platform. Subsequently, the data analysis and abnormality recognition module performs direct current drift removal on the digital signal, so that the entire waveform returns to a stable zero baseline. Then, a band-pass filter is used to limit the signal to the coded frequency band of the emitted infrasound wave (usually 10-30 Hz interval covered by the swept frequency signal), which not only retains the effective signal but also effectively suppresses the infrasound waves generated by low-frequency ground vibration and high-frequency signal interference. On this basis, the system further performs time domain registration processing to accurately align the received signal and the corresponding emitted signal on the time axis. The registered signal is analyzed for its characteristics through Fourier transform, and the time domain similarity of the signal and the infrasound wave emitting signal is calculated using methods such as correlation coefficient analysis to identify pipeline damage characteristics, as shown in the above relationship (3).

[0165] Further, after completing the correlation coefficient calculation, the time domain characteristics of each pipeline emitting signal and received signal are compared, and the correlation coefficient calculation results of each pipeline are combined to confirm whether there is damage in the pipeline.

[0166] The drainage pipeline structural defect detection device and method based on active acoustic waveguide provided in the present example have the following effects:

[0167] 1. For the sewer network with gravity flow or weak pressure flow as the main operating state, the innovative method of sewer structural defect detection based on active acoustic waveguide is proposed. Since this technology can be operated with water and does not interfere with the operation of the pipeline, it can effectively meet the needs of rapid, low-cost, and large-scale inspection of sewer networks.

[0168] 2. By encoding infrasound signals and actively guiding waves, the problem of insufficient accuracy of traditional passive acoustic detection technology is overcome. The traditional method is to indirectly judge structural defects by listening to weak acoustic signals generated by leakage, which is easily disturbed by environmental noise and other factors.

[0169] In an optional embodiment, the method for detecting structural defects in sewer pipes based on active acoustic waveguide specifically includes:

[0170] Step 1: Collecting data on the sewer pipes to be detected.

[0171] Specifically, the above example is introduced by taking a certain sewer area with sewage pipe damage as an example. The demonstration area is shown in Figure 4 .

[0172] Further, according to the upstream and downstream flow measurement, the suspected BC section of the sewage pipe has a damage and leakage problem. Collect the basic data of the pipe network area, sort out the topological connection relationship of the sewage pipe, clarify the number of inspection wells, pipe diameter, pipe material, flow direction, and detection records of each section of the sewage pipe, as shown in Figure 5 . The BC section is a reinforced concrete pipe with a diameter of 800 mm. There are 2 inspection wells between the BC section of the sewage pipe, each inspection well is separated by 30 meters, no geophysical prospecting detection has been carried out, and according to the flow analysis, there is a suspected damage and groundwater infiltration problem.

[0173] Step 2: Infrasound wave emission and receiving equipment layout.

[0174] The drainage pipe BC was divided into three sections to be inspected based on the number of inspection wells: B~B-1, B-1~B-2, and B-2~C. First, an infrasound generator was installed at inspection well B. The generator, using a coupling device composed of flexible sound-conducting material and an elastic compression structure, was securely installed on the inner wall of the inspection well, ensuring effective coupling of the emitted sound to the pipe structure and efficient transmission of the infrasound signal along the pipe. An infrasound receiver was installed in inspection well B-1 downstream of the generator. The receiver was fixed to the inner wall of the inspection well using sound-conducting adhesive, ensuring good acoustic contact with the structural wall. Each receiver was wirelessly connected to the signal acquisition system, and a synchronization control module coordinated the acquisition rhythm to ensure consistent signal timing across multiple points, facilitating subsequent analysis. After completing the equipment deployment and data collection for B~B-1, the same operation was performed for B-1~B-2 and B-2~C, with the following deployment method... Figure 6 As shown.

[0175] Step 3: Infrasound signal encoding.

[0176] Before generating infrasound, an encoded infrasound signal is constructed. First, a signal from 0 to... Time series between Total sampling One point, that is, sampling per second Next, for a total of Seconds, as shown in equation (1) above. Wherein, ; .

[0177] Furthermore, the waveform function of the linear frequency modulated signal is constructed according to the formula, as shown in the above relation (2). Wherein, Take 1; Choose 5Hz; Select 20Hz; It is 2Hz / s.

[0178] Simultaneously set a silent interval for infrasound signals. If the duration is 2 seconds, then the infrasound signal can be obtained as follows: Figure 7 As shown.

[0179] Step 4: Infrasound signal generation, reception, and structural defect detection

[0180] The generating device R0 at inspection well B emits sound according to the infrasound signal generated in step 3, and the power amplifier unit amplifies this signal. The signal acquisition system has an embedded analog-to-digital converter (ADC) to convert the analog signal into a digital waveform and transmit it to the data analysis and anomaly identification module. Following step 2, equipment is installed along each pipeline, infrasound signal is emitted, and data is received and uploaded. The data analysis module processes the signals uploaded from all signal receivers to obtain the main frequency trajectory. Use as follows Analyze the correlation between the measured signal and the emitted signal, and then normalize it:

[0181] (4)

[0182] In the formula: Let be the correlation coefficient function, representing the th The actual signal received by each receiving point differs from the emitted signal in the time domain delay variable. The degree of similarity; This represents the time-domain delay variable, used to compare the alignment between two signals. Its value is approximately equal to the signal propagation distance divided by the wave speed, and the unit is seconds (s).

[0183] Furthermore, the correlation coefficient analysis results and the comparison between the measured signal and the emitted signal, for example... Figure 8 As shown, the amplitude changes of R1 and R3 over time are very similar to those of R0, and their correlation coefficients are close to 1. Therefore, it can be determined that there should be no damage between B~B-1 and B-2~C. However, R2 and R0 show significant differences, and the correlation coefficient is even lower. This may be due to signal changes caused by damage. Therefore, the location of the damage in the sewage pipe section BC should be between inspection wells B-1 and B-2.

[0184] This invention also provides a computer device for performing the above-described... Figure 2 The method for detecting structural defects in drainage pipes is shown.

[0185] Please see Figure 9 , Figure 9 This is a schematic diagram of the structure of a computer device provided in an optional embodiment of the present invention, such as... Figure 9 As shown, the computer device includes one or more processors 10, memory 20, and interfaces for connecting the components, including high-speed interfaces and low-speed interfaces. The components communicate with each other via different buses and can be mounted on a common motherboard or otherwise installed as needed. The processors can process instructions executed within the computer device, including instructions stored in or on memory to display graphical information of a GUI on external input / output devices (such as display devices coupled to the interfaces). In some alternative implementations, multiple processors and / or multiple buses can be used with multiple memories, if desired. Similarly, multiple computer devices can be connected, each providing some of the necessary operations (e.g., as a server array, a group of blade servers, or a multiprocessor system). Figure 9 Take a processor 10 as an example.

[0186] The processor 10 can be a central processing unit, a network processing unit, or a combination thereof. The processor 10 can further include a hardware chip. The hardware chip can be an application specific integrated circuit, a programmable logic device, or a combination thereof. The programmable logic device can be a complex programmable logic device, a field programmable logic device, a general array logic, or any combination thereof.

[0187] The memory 20 stores instructions executable by the at least one processor 10 to cause the at least one processor 10 to perform the methods illustrated by the above embodiments.

[0188] The memory 20 can include a program storage area and a data storage area. The program storage area can store an operating system, application programs required by at least one function, and the like. The data storage area can store data created according to the use of the computer device, and the like. In addition, the memory 20 can include a high-speed random access memory, and can further include a non-transitory memory such as at least one disk storage device, a flash memory device, or other non-transitory solid state memory device. In some alternative embodiments, the memory 20 can optionally include a memory disposed remotely from the processor 10, which can be connected to the computer device through a network. Examples of the network include, but are not limited to, the Internet, an intranet, a local area network, a mobile communication network, and a combination thereof.

[0189] The memory 20 can include a volatile memory such as a random access memory, and can also include a non-volatile memory such as a flash memory, a hard disk, or a solid state disk. The memory 20 can further include a combination of the above-mentioned types of memories.

[0190] The computer device further includes a communication interface 30 for communication of the computer device with other devices or communication networks.

[0191] The embodiments of the present application also provide a computer readable storage medium. The above-mentioned methods according to the embodiments of the present application can be implemented in hardware, firmware, or recorded in a storage medium, or stored in a remote storage medium or a non-transitory machine readable storage medium originally downloaded through a network and stored in a local storage medium, so that the methods described herein can be processed by such software on a storage medium using a general purpose computer, a special purpose processor, or programmable or special purpose hardware. The storage medium can be a disk, an optical disk, a read-only memory, a random access memory, a flash memory, a hard disk, or a solid state disk, etc. Further, the storage medium can further include a combination of the above-mentioned types of memories. It can be understood that the computer, the processor, the microprocessor controller, or the programmable hardware includes a storage component that can store or receive software or computer code, which, when accessed and executed by the computer, the processor, or the hardware, implements the methods illustrated by the above embodiments.

[0192] Part of the present application can be applied as a computer program product, for example, computer program instructions, when executed by a computer, through the operation of the computer, can invoke or provide the method and / or technical solutions according to the present application. Those skilled in the art should understand that the form of computer program instructions in computer readable medium includes but is not limited to source files, executable files, installation package files, etc., and accordingly, the way of computer program instructions executed by computer includes but is not limited to: the computer directly executes the instructions, or the computer compiles the instructions and then executes the corresponding compiled program, or the computer reads and executes the instructions, or the computer reads and installs the instructions and then executes the corresponding installed program. Here, the computer readable medium can be any available computer readable storage medium or communication medium accessible to the computer.

[0193] Although the embodiments of the present application are described in conjunction with the drawings, various modifications and changes can be made by those skilled in the art without departing from the spirit and scope of the present application, and such modifications and changes fall within the scope defined by the appended claims.

Claims

1. A sewer structural defect detection system, characterized by, The system comprises a controller, an infrasound sound emitting module, an infrasound signal receiving module, and a detection module, the infrasound sound emitting module and the infrasound signal receiving module are arranged in the inspection wells at different ends of the drainage pipeline respectively; The controller is configured to construct an encoded infrasound wave signal and send the encoded infrasound wave signal to the infrasound sound emitting module and the detection module; The infrasound sound emitting module is configured to emit and process the encoded infrasound wave signal to obtain a low-frequency mechanical vibration signal, and the low-frequency mechanical vibration signal is transmitted in the drainage pipeline; The infrasound signal receiving module is configured to detect the low-frequency mechanical vibration signal of the drainage pipeline, determine an initial digital vibration signal, and send the initial digital vibration signal to the detection module; The detection module is configured to process the initial digital vibration signal and the encoded infrasound wave signal by a Fourier transform method and a correlation coefficient analysis method to determine a structural defect detection result of the drainage pipeline; The controller comprises an acquisition unit and a construction unit; The acquisition unit is configured to acquire a time signal sequence and send the time signal sequence to the construction unit; and the construction unit is configured to construct the encoded infrasound wave signal according to the time signal sequence; wherein the acquisition of the time signal sequence comprises generating the time signal sequence according to the single sweep frequency duration of the infrasound wave signal and the sampling frequency, and the relationship is represented as follows: In the formula: denotes the sampling frequency; denotes the signal duration, i.e. the duration of a single sweep of the infrasound signal; The construction unit is specifically configured to generate the encoded infrasound wave signal by using a linear frequency modulation coding mode according to the time signal sequence, and the relationship is represented as follows: In the formulae: represents an encoded infrasound signal; represents an amplitude; represents a sweep start frequency; represents a sweep bandwidth; represents a sweep rate; The infrasound sound emitting module comprises a transmission controller, a power amplifier driving unit, a sound emitter unit, and a coupling device, the sound emitter unit adopts a piezoelectric ceramic sheet stacking structure, the coupling device is composed of a flexible sound guide material and an elastic pressing arm, and the sound emitter unit is mechanically coupled with the inspection well wall of the drainage pipeline through the coupling device; The transmission controller is configured to emit a low-frequency programming signal by using the encoded infrasound wave signal when the encoded infrasound wave signal is received; The power amplifier driving unit is configured to amplify the low-frequency programming signal to obtain a high-frequency programming signal and send the high-frequency programming signal to the sound emitter unit when the low-frequency programming signal is received; The sound emitter unit is configured to convert the high-frequency programming signal to obtain a low-frequency mechanical vibration signal and send the low-frequency mechanical vibration signal to the coupling device, so that the low-frequency mechanical vibration signal is transmitted in the drainage pipeline through the coupling device.

2. The system of claim 1, wherein, The infrasound signal receiving module comprises an inductive receiver array and a signal acquisition unit; The inductive receiver array is configured to detect the low-frequency mechanical vibration signal of the drainage pipeline and send the low-frequency mechanical vibration signal to the signal acquisition unit when the low-frequency mechanical vibration signal is detected; The signal acquisition unit is configured to convert the low-frequency mechanical vibration signal to obtain an initial digital vibration signal and send the initial digital vibration signal to the detection module.

3. The system of claim 1, wherein, The detection module comprises a signal preprocessing unit and a damage diagnosis algorithm unit. The signal preprocessing unit is configured to preprocess the initial digital vibration signal to obtain a target digital vibration signal, and send the target digital vibration signal to the damage diagnosis algorithm unit. The damage diagnosis algorithm unit is configured to process the target digital vibration signal through a Fourier transform method and a correlation coefficient analysis method, and determine the structural defect detection result of the drainage pipeline.

4. The system of claim 3, wherein, The damage diagnosis algorithm unit comprises a feature analysis subunit, a calculation subunit and a detection subunit. The feature analysis subunit is configured to process the initial digital vibration signal and the coded infrasound wave signal through the Fourier transform method to obtain a frequency domain analysis result, and send the frequency domain analysis result to the detection subunit. The calculation subunit is configured to calculate the initial digital vibration signal and the coded infrasound wave signal through the correlation coefficient analysis method to obtain a correlation coefficient value, and send the correlation coefficient value to the detection subunit. The detection subunit is configured to determine the structural defect detection result of the drainage pipeline based on the frequency domain analysis result and the correlation coefficient value.

5. The system of claim 3, wherein, The detection module further comprises: A time synchronization unit configured to control the infrasound signal emitting module and the infrasound signal receiving module to operate at the same time.

6. A method of detecting structural defects in a sewer pipe, characterized by, The method comprises: constructing a coded infrasound wave signal; emitting and processing the coded infrasound wave signal to obtain a low-frequency mechanical vibration signal, which is transmitted in the drainage pipeline; detecting the low-frequency mechanical vibration signal of the drainage pipeline to obtain an initial digital vibration signal; processing the initial digital vibration signal and the coded infrasound wave signal through a Fourier transform method and a correlation coefficient analysis method to determine a structural defect detection result of the drainage pipeline; constructing a coded infrasound wave signal comprises generating the time signal sequence according to the single-frequency sweep duration of the infrasound wave signal and the sampling frequency, which is represented by the following relationship: In the formula: denotes the sampling frequency; denotes the signal duration, i.e. the duration of a single sweep of the infrasound signal; generating the coded infrasound wave signal using a linear frequency modulation coding method according to the time signal sequence, which is represented by the following relationship: In the formulae: represents an encoded infrasound signal; represents an amplitude; represents a sweep start frequency; represents a sweep bandwidth; represents a sweep rate; wherein emitting and processing the coded infrasound wave signal to obtain a low-frequency mechanical vibration signal comprises emitting a low-frequency programming signal using the coded infrasound wave signal; amplifying the low-frequency programming signal to obtain a high-frequency programming signal; and converting the high-frequency programming signal to obtain a low-frequency mechanical vibration signal.

7. A computer-readable storage medium, characterized in that, The computer readable storage medium stores computer instructions for causing a computer to execute the drainage pipeline structural defect detection method of claim 6.

8. A computer program product, characterised in that, The computer readable storage medium stores computer instructions for causing a computer to execute the drainage pipeline structural defect detection method of claim 6.

Images