Drainage pipeline structural defect detection system and method, medium and product

Abstract

The invention relates to the technical field of drainage pipeline detection, and discloses a drainage pipeline structural defect detection system and method, a medium and a product, a controller actively constructs and generates a coded infrasonic wave signal, and it is ensured that the signal has stable frequency and amplitude characteristics; the infrasonic sound production module performs infrasonic wave emission and processing by using a coded infrasonic wave signal, and enables a low-frequency mechanical vibration signal to be stably propagated along a pipe wall, so that energy attenuation is reduced, and a long-distance pipe section which is difficult to touch in traditional passive detection is covered; the infrasound signal receiving module is used for detecting low-frequency mechanical vibration signals and converting analog signals into initial digital signals, and interference and distortion in the transmission process are reduced. Furthermore, 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, accurate recognition of the structural defects of the pipeline is ensured, and the requirement for accuracy of structural defect detection of the drainage pipeline under complex working conditions is met.

Description

Technical Field

[0001] This invention relates to the field of drainage pipeline inspection technology, specifically to a drainage pipeline structural defect detection system, method, medium, and product. Background Technology

[0002] As a crucial component of urban municipal infrastructure, drainage pipeline systems play a vital role in maintaining urban water security and the health of the aquatic ecosystem. Due to factors such as aging, corrosion, and ground load, drainage pipelines commonly suffer from structural defects such as cracks and misalignments during long-term service. This allows groundwater to seep into the pipelines through these defective areas, resulting in low influent concentrations and reduced treatment efficiency at wastewater treatment plants. Furthermore, wastewater from the pipelines can also leak into groundwater through these areas, causing pollution of both groundwater and soil. Therefore, it is urgently necessary to conduct identification and location analysis of drainage pipeline damage.

[0003] Existing pipeline damage detection technologies are mainly divided into two categories: physical detection and acoustic detection. Physical detection technologies, such as closed-circuit television (CCTV) of pipelines, can directly present structural defects in pipelines with high positioning accuracy. However, these methods require pipeline sealing, dewatering, dredging, and drainage, which are time-consuming and costly, making them unsuitable for large-scale rapid inspections. Acoustic detection technologies, on the other hand, identify and locate pipeline damage by sensing leakage sound signals.

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

[0005] However, the application of this technology in urban sewage pipelines still faces significant challenges. On the one hand, under gravity flow or low-pressure operation conditions in sewage treatment, the acoustic signals generated by damage and leakage are weak and easily drowned out by ambient background noise. On the other hand, the complex hydraulic conditions inside sewage pipelines, such as sludge accumulation and gas-liquid two-phase flow, cause significant attenuation and distortion of infrasound signals during propagation, reducing detection accuracy. Therefore, traditional acoustic detection technology is insufficient to meet the needs of effectively identifying damage and leakage problems in urban underground sewage pipe networks under complex operating conditions. Summary of the Invention

[0006] In view of this, the present invention provides a drainage pipeline structural defect detection system, method, medium and product to solve the problem that traditional acoustic detection technology is difficult to meet the needs of effectively identifying damage and leakage problems in urban underground sewage pipe networks under complex working conditions.

[0007] In a first aspect, the present invention provides a drainage pipeline structural defect detection system, the system comprising: a controller, an infrasound generating module, an infrasound signal receiving module, and a detection module, wherein the infrasound generating module and the infrasound signal receiving module are respectively installed in inspection wells at different ends of the drainage pipeline; The controller is used to construct an encoded infrasound signal and send it to the infrasound generation module and the detection module. The infrasound generation module is used to transmit and process the encoded infrasound signal to obtain a low-frequency mechanical vibration signal, which is transmitted within the drainage pipe. The infrasound signal receiving module is used to detect the low-frequency mechanical vibration signal of the drainage pipe and determine the initial digital vibration signal, and send the initial digital vibration signal to the detection module. The detection module is used to determine the structural defect detection results of the drainage pipe based on the initial digital vibration signal and the encoded infrasound signal, using Fourier transform and correlation coefficient analysis methods.

[0008] The drainage pipeline structural defect detection system provided by this invention actively constructs and generates coded infrasound signals through a controller, ensuring that the signals possess stable frequency and amplitude characteristics. Compared to traditional uncoded signals, it can effectively distinguish effective signals from environmental noise, solving the problem of signals being easily submerged in the complex operating conditions of sewage pipelines. Simultaneously, the coded signal is sent synchronously to the detection module, providing a "reference signal" for comparison and analysis of subsequent received signals, avoiding signal anomaly judgment errors caused by the lack of a reference. Furthermore, the infrasound emission module utilizes the coded infrasound signal for infrasound transmission and processing, and through internal signal processing and mechanical coupling design, enables the low-frequency mechanical vibration signal to propagate stably along the pipe wall, reducing energy attenuation and covering long-distance pipe sections that are difficult to reach with traditional passive detection. At the same time, the actively emitted vibration signal is not affected by sludge or gas-liquid two-phase flow within the pipeline, solving the problem of weak signals easily submerged by noise in gravity-flow sewage pipelines. Furthermore, by detecting the low-frequency mechanical vibration signal of the drainage pipeline through the infrasound signal receiving module, the dynamic changes of the signal propagating along the pipeline can be fully acquired, avoiding the omission of local defects. Simultaneously, converting analog signals into initial digital signals reduces interference and distortion during transmission, providing high-quality raw data for subsequent data analysis and solving the problems of traditional analog signals being susceptible to interference and having low data reliability. Furthermore, Fourier transform can extract the dominant frequency shift characteristics and identify frequency component changes caused by defects, while correlation coefficient analysis can quantify signal similarity and eliminate non-defect factors such as noise. The combination of these two methods avoids the high false positive rate of traditional single algorithms, ultimately providing accurate results on whether the pipeline is damaged, meeting the accuracy requirements for detecting structural defects in drainage pipelines under complex operating conditions. Therefore, by implementing this invention, the problem that traditional acoustic detection technology is insufficient to effectively identify damage and leakage issues in urban underground sewage pipe networks under complex operating conditions is solved.

[0009] In one alternative implementation, the controller includes: an acquisition unit and a construction unit; The acquisition unit is used to acquire the time signal sequence and send the time signal sequence to the construction unit; the construction unit is used to construct the coded infrasound signal based on the time signal sequence.

[0010] The drainage pipeline structural defect detection system provided by this invention generates a uniform and continuous time signal sequence, providing a precise time carrier for the construction of coded signals. This ensures that the frequency changes of subsequent linear frequency modulated signals are stable and controllable, avoiding signal waveform distortion caused by irregular time sequences and guaranteeing the anti-interference capability of the coded signals. Furthermore, by constructing coded infrasound signals based on the time signal sequence to meet the pipeline detection requirements, signal parameters can be flexibly adjusted to adapt to pipelines of different diameters and materials. This solves the problem that traditional fixed signals cannot adapt to complex pipe networks, improving the reliability and identifiability of signal propagation within the pipeline.

[0011] In one optional implementation, the infrasound module includes: a transmitter controller, a power amplifier driver unit, a transmitter unit, and a coupling device. The transmitter unit adopts a piezoelectric ceramic sheet stacked structure, and the coupling device is composed of a flexible sound-conducting material and an elastic clamping arm. The transmitter unit is mechanically coupled to the inspection well wall of the drainage pipe through the coupling device. The transmitter controller is used to transmit a low-frequency programming signal when it receives an coded infrasound signal; the power amplifier drive unit is used to amplify the low-frequency programming signal to obtain a high-frequency programming signal when it receives the low-frequency programming signal, and then send the high-frequency programming signal to the sound generator unit; the sound generator unit is used to convert the high-frequency programming signal to obtain a low-frequency mechanical vibration signal, and then send the low-frequency mechanical vibration signal to the coupling device so that the low-frequency mechanical vibration signal can be transmitted in the drainage pipe through the coupling device.

[0012] The drainage pipeline structural defect detection system provided by this invention receives coded infrasound signals through a transmitter controller and uses these signals to transmit low-frequency programming signals, enabling precise control of the timing and spectral parameters of the low-frequency programming signals. Furthermore, a power amplifier drive unit amplifies the low-frequency programming signals to meet the driving requirements of the transmitter unit, ensuring sufficient strength of the subsequent mechanical vibration signal and preventing rapid attenuation along the pipe wall due to insufficient signal power, thus solving the problem of small signal coverage in traditional sound-generating devices. Simultaneously, it maintains good low-frequency response characteristics, avoiding waveform distortion during signal amplification and ensuring consistency between signal characteristics and the coding design. Furthermore, the transmitter unit adopts a piezoelectric ceramic sheet stacked structure, achieving efficient conversion between electrical signals and mechanical vibrations, thereby outputting a low-frequency mechanical vibration signal with a frequency matching the coded signal. This is suitable for the long propagation distance and low energy attenuation characteristics of infrasound, providing a stable vibration source for active acoustic waveguides propagating along the pipe wall. The coupling device enables the sound generator unit to be mechanically coupled to the manhole wall of the drainage pipe, reducing the loss of kinetic energy during transmission and achieving efficient coupling of mechanical vibration to the pipe wall. This avoids signal attenuation or distortion caused by poor coupling and ensures that the infrasound waves propagate stably along the pipe wall to the receiving end.

[0013] In one optional implementation, the infrasound signal receiving module includes: an array of inductive receivers and a signal acquisition unit; The sensor array is used to detect low-frequency mechanical vibration signals of the drainage pipe, and when a low-frequency mechanical vibration signal is detected, it sends the low-frequency mechanical vibration signal to the signal acquisition unit; the signal acquisition unit is used to convert the low-frequency mechanical vibration signal to obtain an initial digital vibration signal, and then send the initial digital vibration signal to the detection module.

[0014] The drainage pipeline structural defect detection system provided by this invention detects low-frequency mechanical vibration signals of the drainage pipeline through an array of induction receivers. It can capture minute vibration responses of the pipe wall, and compared to traditional single-point detection, it can comprehensively acquire the signal variation characteristics along the pipeline, providing multi-dimensional data support for defect localization and avoiding the omission of localized damage. Furthermore, the low-frequency mechanical vibration signal is converted into an initial digital vibration signal by a signal acquisition unit, eliminating interference during analog signal transmission and ensuring that the initial digital signal accurately reflects the vibration characteristics of the pipe wall. Moreover, sending the initial digital vibration signal to the detection module avoids the deployment difficulties of wired connections within inspection wells, improving equipment deployment flexibility while ensuring real-time data transmission, laying the foundation for subsequent rapid analysis.

[0015] In one optional implementation, the detection module includes: a signal preprocessing unit and a damage diagnosis algorithm unit; The signal preprocessing unit is used to preprocess the initial digital vibration signal to obtain the target digital vibration signal, and then send the target digital vibration signal to the damage diagnosis algorithm unit. The damage diagnosis algorithm unit is used to process the target digital vibration signal through Fourier transform and correlation coefficient analysis methods, and determine the detection results of structural defects in the drainage pipeline.

[0016] The drainage pipeline structural defect detection system provided by this invention improves signal quality by preprocessing the initial digital vibration signal through a signal preprocessing unit, eliminating interference factors for subsequent algorithm analysis and avoiding misjudgments caused by poor original signal quality. Furthermore, Fourier transform can extract the dominant frequency shift characteristics and identify frequency component changes caused by defects, while correlation coefficient analysis can quantify signal similarity and eliminate non-defect factors such as noise. The combination of these two methods avoids the high misjudgment rate problem of traditional single algorithms, significantly improving the accuracy and reliability of damage detection.

[0017] In one optional implementation, the damage diagnosis algorithm unit includes: a feature analysis subunit, a calculation subunit, and a detection subunit; The feature analysis subunit is used to process the initial digital vibration signal and the coded infrasound signal using the Fourier transform method to obtain the frequency domain analysis result, and then send the frequency domain analysis result to the detection subunit; the calculation subunit is used to calculate the correlation coefficient value based on the initial digital vibration signal and the coded infrasound signal using the correlation coefficient analysis method, and then send the correlation coefficient value to the detection subunit; the detection subunit is used to determine the detection result of the structural defects of the drainage pipeline based on the frequency domain analysis result and the correlation coefficient value.

[0018] The drainage pipeline structural defect detection system provided by this invention utilizes Fourier transform in the feature analysis subunit to convert time-domain signals into frequency-domain signals. This enables rapid identification of frequency shifts in the received signal, providing a frequency-domain basis for determining pipeline defects and overcoming the limitation of traditional time-domain analysis in intuitively identifying frequency anomalies. Furthermore, in the calculation subunit, correlation coefficient analysis is used to calculate correlation coefficient values, quantifying signal similarity and eliminating non-defect factors such as noise. This provides a clear numerical basis for defect judgment, avoiding the subjective nature and large errors of traditional manual waveform comparison. Finally, the detection subunit combines the frequency-domain analysis results and correlation coefficient values ​​to determine the structural defect detection result of the drainage pipeline. This avoids misjudgments caused by single feature analysis, significantly improving the reliability of the detection results and ensuring accurate identification of pipeline structural defects.

[0019] In one optional implementation, the detection module further includes a time synchronization unit for controlling the infrasound generating module and the infrasound signal receiving module to operate at the same time.

[0020] The drainage pipeline structural defect detection system provided by this invention controls the infrasound emission module and the infrasound signal receiving module to operate at the same time through a time synchronization unit. This ensures that the timing of the signals emitted by the infrasound emission module and the signals collected by the infrasound signal receiving module is consistent, avoiding the deviation in signal propagation time calculation caused by time difference. It provides a timing reference for accurately calculating the infrasound wave propagation speed and locating the defect, and solves the problem of ambiguous location in traditional detection methods.

[0021] Secondly, the present invention provides a method for detecting structural defects in drainage pipes, used in the drainage pipe structural defect detection system of the first aspect or any corresponding embodiment thereof; the method includes: A coded infrasound signal is constructed; the coded infrasound signal is used for infrasound transmission and processing to obtain a low-frequency mechanical vibration signal, which is transmitted in the drainage pipe; the low-frequency mechanical vibration signal of the drainage pipe is detected and the initial digital vibration signal is determined; based on the initial digital vibration signal and the coded infrasound signal, the structural defect detection results of the drainage pipe are determined by processing with Fourier transform and correlation coefficient analysis methods.

[0022] The present invention provides a method for detecting structural defects in drainage pipelines. By actively constructing and generating coded infrasound signals, it ensures that the signals possess stable frequency and amplitude characteristics. Compared with traditional uncoded signals, this method can effectively distinguish effective signals from environmental noise, solving the problem of signal submersion under complex operating conditions in sewage pipelines. Furthermore, by actively emitting mechanical vibration signals, a stable active acoustic waveguide is formed along the pipe wall, unaffected by the water flow state or silt accumulation within the pipeline, covering pipe sections that are difficult to reach with traditional passive detection, thus meeting the needs of large-scale detection. Furthermore, 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 detections due to signal loss or distortion. Furthermore, by combining Fourier transform and correlation coefficient analysis methods for structural defect detection, the method can accurately identify whether the pipeline is damaged, avoiding the high false positive rate problem of traditional single algorithms, and ultimately accurately outputting the result of whether the pipeline is damaged, meeting the accuracy requirements for detecting structural defects in drainage pipelines under complex operating conditions. Therefore, by implementing this invention, the problem that traditional acoustic detection technology is difficult to meet the need for effective identification of damage and leakage in urban underground sewage pipe networks under complex operating conditions is solved.

[0023] Thirdly, the present invention provides a computer-readable storage medium storing computer instructions for causing a computer to execute the drainage pipe structural defect detection method described in the second aspect.

[0024] Fourthly, the present invention provides a computer program product, including computer instructions for causing a computer to execute the drainage pipe structural defect detection method described in the second aspect above. Attached Figure Description

[0025] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0026] Figure 1 This is a structural block diagram of a drainage pipeline structural defect detection system according to an embodiment of the present invention; Figure 2 This is a schematic flowchart of a method for detecting structural defects in drainage pipes according to an embodiment of the present invention; Figure 3 This is a schematic flowchart of a method for detecting structural defects in drainage pipelines based on active acoustic waveguides according to an embodiment of the present invention. Figure 4 This is a schematic diagram of the drainage area according to an embodiment of the present invention; Figure 5 This is a schematic diagram of the drainage area after data collection according to an embodiment of the present invention; Figure 6 This is a schematic diagram of the installation of the sound-emitting and receiving device for the pipeline under test according to an embodiment of the present invention; Figure 7 This is a schematic diagram of an encoded infrasound signal according to an embodiment of the present invention; Figure 8 This is a comparison and analysis chart of measured values ​​and ideal values ​​according to an embodiment of the present invention; Figure 9 This is a schematic diagram of the hardware structure of a computer device according to an embodiment of the present invention. Detailed Implementation

[0027] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0028] This invention provides a method for detecting structural defects in drainage pipelines. The method involves a controller that actively constructs, generates, and transmits coded infrasound signals. Simultaneously, it combines Fourier transform and correlation coefficient analysis methods to detect structural defects, thereby accurately identifying whether the pipeline is damaged. This achieves the desired effect of effectively identifying damage and leakage problems in urban underground sewage pipe networks under complex operating conditions.

[0029] This embodiment provides a drainage pipe structural defect detection system, such as... Figure 1 As shown, the drainage pipe structural defect detection system 1 includes: a controller 11, an infrasound generation module 12, an infrasound signal receiving module 13, and a detection module 14.

[0030] The infrasound generating module 12 and the infrasound signal receiving module 13 are respectively installed in the inspection wells at different ends of the drainage pipe, that is, the infrasound generating module 12 is installed in the inspection well at one end of the drainage pipe, and the infrasound signal receiving module 13 is installed in the inspection well at the other end.

[0031] Furthermore, the infrasound signal receiving module 13 is fixed to the inner wall of the target inspection well by a sound-conducting adhesive.

[0032] Furthermore, basic data such as drainage system GIS map, pipe material, pipe diameter, pipe length, flow direction, elevation, manhole number and coordinates of drainage pipelines can be collected. Combined with the topological connection relationship of drainage pipelines and actual operating conditions, the infrasound propagation path and the distribution of manholes along the way can be determined, thereby determining the deployment of infrasound generating module 12 and infrasound signal receiving module 13.

[0033] Optionally, the controller 11 is used to construct an encoded infrasound signal and send the encoded infrasound signal to the infrasound signal receiving module 13 and the detection module 14.

[0034] Among them, linear frequency modulation can be used to encode infrasound signals, thereby improving the signal's identifiability, anti-interference ability, and detection accuracy. This enables effective differentiation between infrasound signals and background noise in engineering practice, enhancing damage diagnosis capabilities.

[0035] Furthermore, the controller 11 includes an acquisition unit 111 and a construction unit 112.

[0036] First, in the acquisition unit 111, a time signal sequence is acquired and sent to the construction unit 112.

[0037] In the complex environment of urban drainage pipelines, in order to ensure that the subsequently encoded infrasound signals can be accurately propagated and identified, it is necessary to first determine an accurate and continuous time series as the basis for subsequent calculation of the signal amplitude changes over time. This ensures the accuracy and identifiability of the encoded signal and lays the foundation for improving the transmission reliability of infrasound in complex pipeline environments.

[0038] Specifically, it can be based on the duration of a single frequency sweep of the infrasound signal. and sampling frequency The time series is defined as ranging from 0 to... .

[0039] Further, sampling One point, that is, sampling per second Next, for a total of The time is measured in seconds, and the corresponding time signal sequence is generated, as shown in the following equation (1): (1) In the formula: Indicates the sampling frequency; Indicates the duration of the signal.

[0040] Furthermore, the obtained time signal sequence is sent to the construction unit 112 so that the construction unit 112 can construct the encoded infrasound signal based on this time sequence.

[0041] Secondly, in the construction unit 112, an encoded infrasound signal is constructed based on the time signal sequence.

[0042] Specifically, by using the time signal sequence provided by the acquisition unit and combining it with the linear frequency modulation encoding method, an infrasound signal with a specific frequency variation pattern can be generated.

[0043] For example, based on the requirements for drainage pipeline inspection, the parameters of the encoded infrasound signal can be set, which may include amplitude, sweep start frequency, sweep bandwidth, sweep rate, etc.

[0044] Furthermore, time points in the time signal sequence can be... Substituting the values ​​into the linear frequency modulated (LFM) signal formula and generating the corresponding LFM signal waveform function results in the encoded infrasound signal. The following relation (2) is shown: (2) In the formula: Indicates amplitude; Indicates the start frequency of the sweep; Indicates the sweep bandwidth; This indicates the sweep rate.

[0045] Furthermore, to avoid interference between adjacent infrasound signals, the infrasound signal can be encoded. The silence interval is used to obtain the corresponding encoded infrasound signal.

[0046] Furthermore, by using linear frequency modulation (LFM) coded infrasound signals, the identifiability, anti-interference capabilities, and detection accuracy in the complex environment of urban drainage pipelines can be improved, effectively distinguishing infrasound signals from background noise and enhancing the diagnostic capabilities for pipeline damage.

[0047] Optionally, the infrasound generation module 12 is used to transmit and process infrasound using coded infrasound signals to obtain low-frequency mechanical vibration signals.

[0048] Low-frequency mechanical vibration signals are transmitted within the drainage pipes.

[0049] Furthermore, the infrasound generation module 12 includes: a transmission controller 121, a power amplifier drive unit 122, a sound generator unit 123, and a coupling device 124.

[0050] The sound generator unit 123 adopts a piezoelectric ceramic sheet stacked structure, which can realize the efficient conversion of electrical signals and mechanical vibrations; the coupling device 124 is composed of flexible sound guiding material and elastic clamping arm, which can ensure that the sound generator unit 123 is closely attached to the pipe wall surface, that is, the sound generator unit 123 is mechanically coupled to the inspection well wall of the drainage pipe through the coupling device.

[0051] Specifically, the sound generator unit 123 is installed close to the manhole wall, and a coupling device 124 consisting of a flexible sound-conducting material and an elastic clamping arm is used to maintain a stable mechanical coupling between the sound generator unit 123 and the manhole wall, ensuring that mechanical vibration is efficiently transmitted into the pipe body.

[0052] First, when the transmitter controller 121 receives the coded infrasound signal, it uses the coded infrasound signal to transmit a low-frequency programming signal.

[0053] Specifically, the transmitter controller 121 can receive coded infrasound signals through a wired interface and analyze the signal's frequency sweep, silent phase timing, frequency variation range, amplitude, and other parameters.

[0054] Furthermore, the received coded infrasound signal can be converted into a low-frequency programmable electrical signal (such as a TTL level signal) that can be recognized by the power amplifier driver unit 122, ensuring that the timing logic (sweep / silent switching) and spectral characteristics (frequency, amplitude) of the signal are undistorted.

[0055] Furthermore, the low-frequency programming electrical signal is output to the power amplifier drive unit, and the internal synchronization clock can also be activated to record the signal transmission timestamp, providing a basis for subsequent time synchronization with the infrasound signal receiving module 13.

[0056] Furthermore, when the transmitter controller 121 receives the coded infrasound signal, it analyzes the signal characteristics and generates a low-frequency programming electrical signal that can drive the power amplifier unit, thus ensuring the accurate transmission of signal timing and spectral parameters.

[0057] Secondly, when the power amplifier driver 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.

[0058] Specifically, when the power amplifier driver unit 122 receives the low-frequency programming signal, it can amplify the low-level signal into a high-power signal (such as a 10V high-level signal) through an internal power amplifier circuit (such as a Class B complementary symmetry power amplifier circuit). During the amplification process, the frequency range (5~25Hz) and waveform characteristics of the signal remain unchanged to avoid signal distortion.

[0059] Furthermore, the power amplifier drive unit 122 amplifies the low-level, low-frequency programming signal output by the transmitter controller 121 into 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 and ensuring that the mechanical vibration intensity meets the propagation requirements.

[0060] Furthermore, the power amplifier driver unit 122 sends the amplified high-power high-frequency programming signal to the speaker unit, driving the speaker unit 123 to perform electromechanical conversion.

[0061] 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 so that the low-frequency mechanical vibration signal is transmitted in the drainage pipe through the coupling device 124.

[0062] Specifically, the sound generator unit 123 adopts a piezoelectric ceramic sheet stacked structure. Therefore, when the sound generator unit 123 receives high-frequency programming information, it can use the characteristic of piezoelectric ceramics to "generate mechanical deformation when energized" to convert the electrical signal into low-frequency mechanical vibration. The vibration amplitude is proportional to the electrical signal amplitude, which can ensure stable vibration intensity.

[0063] Furthermore, the vibration output end of the sound generator unit 123 is in direct contact with the flexible sound-conducting material of the coupling device 124, transmitting low-frequency mechanical vibration to the coupling device 124, preparing to transmit it to the pipe wall through the coupling device 124.

[0064] Furthermore, the coupling device 124, acting as a vibration transmission bridge, can ensure through mechanical structure design that the mechanical vibration of the sound generator is transmitted to the pipe wall efficiently and without loss, thus avoiding the attenuation of vibration energy in the air gap.

[0065] For example, the elastic clamping arm of the coupling device 124 can be unfolded to make the flexible sound-conducting material (such as silicone) adhere tightly to the inspection well wall. Stable pressure (such as 50N) is applied by the rebound force of the elastic clamping arm to ensure that there is no gap between the flexible sound-conducting material and the well wall.

[0066] Furthermore, the low-frequency mechanical vibration transmitted by the sound generator unit 123 is conducted to the manhole wall through the flexible sound guiding material, and then transmitted from the manhole wall to the drainage pipe wall, forming a low-frequency mechanical vibration signal (active acoustic wave guide) that propagates along the pipe wall axis. Moreover, the energy attenuation rate during vibration propagation is controlled within 5%, which can ensure long-distance propagation.

[0067] Furthermore, the sound generator unit 123, based on the piezoelectric effect, converts the high-power electrical signal output by the power amplifier drive unit 122 into low-frequency mechanical vibrations that are consistent with the frequency of the encoded signal, thereby providing a physical vibration source for the propagation of infrasound along the pipe wall.

[0068] Optionally, the infrasound signal receiving module 13 is used to detect the low-frequency mechanical vibration signal of the drainage pipe and determine the initial digital vibration signal, and to send the initial digital vibration signal to the detection module 14.

[0069] The infrasound signal receiving module 13 includes: an inductive receiver array 131 and a signal acquisition unit 132.

[0070] Furthermore, the sensor receiver array 131 consists of multiple high-sensitivity vibration sensors, which are installed in the inspection well at the end of the pipeline. It can capture low-frequency mechanical vibration signals propagating along the pipe wall in real time and convert the vibration physical quantity into an analog electrical signal.

[0071] First, the low-frequency mechanical vibration signal of the drainage pipe is detected by the sensor receiver array 131, and when the low-frequency mechanical vibration signal is detected, it is sent to the signal acquisition unit 132.

[0072] Specifically, 3 to 5 sensors (such as piezoelectric vibration sensors) can be evenly fixed to the inner wall of the inspection well (on the same side of the pipe wall as the sound-generating module) using sound-conducting adhesive, with a sensor spacing of about 10 cm, to ensure coverage of the vibration propagation path of the pipe wall.

[0073] Furthermore, when the low-frequency mechanical vibration signal propagates along the pipe wall to the receiver position, the sensor in the induction receiver array 131 senses the tiny vibration of the pipe wall (vibration displacement of about 1~10μm) and converts the vibration displacement into a corresponding analog electrical signal (voltage range 0~5V), i.e., the low-frequency mechanical vibration signal.

[0074] Furthermore, the analog electrical signals output by each sensor in the sensor receiver array 131 are aggregated to the signal input terminal of the signal acquisition unit 132 via internal cables to ensure that all vibration signals are transmitted synchronously.

[0075] Secondly, the low-frequency mechanical vibration signal is converted by the signal acquisition unit 132 to obtain the initial digital vibration signal, and the initial digital vibration signal is sent to the detection module 14.

[0076] Specifically, the signal acquisition unit 132 can use analog-to-digital conversion technology to convert the analog vibration signal output by the sensor array 131 into a digital signal (initial digital vibration signal), and after adding a timestamp, transmit it to the detection module 14, thereby realizing the digital storage and analysis of the vibration signal.

[0077] For example, the signal acquisition unit 132 can preprocess the received analog electrical signal, i.e., the low-frequency mechanical vibration signal (such as filtering and amplification), filter out the sensor's own noise (<1Hz), and adjust the signal amplitude to the ADC adaptation range (0~3V).

[0078] Furthermore, the signal acquisition unit 132 can activate the embedded 16-bit ADC to sample the conditioned analog signal at a sampling frequency of 1000Hz, converting the continuous analog signal into discrete digital data (i.e., the initial digital vibration signal), and storing each sampling point in binary format (e.g., a numerical range of 0 to 65535).

[0079] Furthermore, the signal acquisition unit 132 can also add a precise timestamp (accuracy 1ms) to each sampling point based on the embedded GPS clock module to ensure that the initial digital vibration signal is time-aligned with the encoded signal of the infrasound generation module 12.

[0080] Furthermore, the signal acquisition unit 132 can transmit the initial digital vibration signal (including a timestamp) to the detection module 14 in real time via a wireless communication module (such as LoRa). The data transmission rate is ≥1Mbps to ensure no data loss.

[0081] Optionally, the detection module 14 is used to determine the detection results of structural defects in the drainage pipeline based on the initial digital vibration signal and the coded infrasound signal, after processing by the Fourier transform method and the correlation coefficient analysis method.

[0082] The Fourier transform method is a mathematical method for converting a time-domain signal into a frequency-domain signal. In the time domain, a signal is represented as a waveform that changes over time, reflecting the signal's characteristics in the time dimension. Through the Fourier transform, this time-domain signal can be decomposed into a superposition of sine and cosine components of different frequencies, revealing the signal's characteristics in the frequency dimension, i.e., obtaining the signal's spectrum.

[0083] Furthermore, the correlation coefficient is an index used to measure the degree of linear correlation between two variables, with a value ranging from -1 to 1. In signal analysis, the correlation coefficient analysis method determines the relationship between the received signal and the reference signal (in this case, the coded infrasound signal) by calculating the similarity between the two.

[0084] Furthermore, the detection module 14 includes: a signal preprocessing unit 141, a damage diagnosis algorithm unit 142, and a time synchronization unit 143.

[0085] First, the initial digital vibration signal is preprocessed by the signal preprocessing unit 141 to obtain the target digital vibration signal, and then the target digital vibration signal is sent to the damage diagnosis algorithm unit 142.

[0086] 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 of the signal (such as the digital value corresponding to 0.5V), subtract the mean from the value of each sampling point, eliminate the DC component in the signal, and make the signal baseline return to zero.

[0087] Furthermore, the signal preprocessing unit 141 can also employ an FIR digital filter, setting the passband frequency to 10~30Hz, to filter out low-frequency ground vibrations (<10Hz) and high-frequency electronic noise (>30Hz), while retaining the effective vibration signal within the coded signal frequency band.

[0088] Furthermore, the signal preprocessing unit 141 can also calculate the signal propagation time difference (e.g., a pipe length of 30m, a wave speed of 300m / s, and a time difference of about 0.1s) based on the timestamp of the initial digital vibration signal and the transmission timestamp of the encoded signal, and shift the received signal on the time axis to the corresponding time difference, thereby achieving precise alignment with the encoded signal and finally obtaining the preprocessed target digital vibration signal.

[0089] Furthermore, 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 via the internal data bus.

[0090] 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 to determine the structural defect detection results of the drainage pipeline.

[0091] Specifically, the damage diagnosis algorithm unit 142 can analyze the signal frequency characteristics in the frequency domain (Fourier transform) and the signal similarity in the time domain (correlation coefficient), and judge whether there are structural defects in the pipeline by combining the two-dimensional results, and output the detection conclusion, namely the structural defect detection result of the drainage pipeline.

[0092] The damage diagnosis algorithm unit 142 includes: a feature analysis subunit 1421, a calculation subunit 1422, and a detection subunit 1423.

[0093] First, in the feature analysis subunit 1421, based on the initial digital vibration signal and the coded infrasound signal, the frequency domain analysis result is obtained by processing the signal using the Fourier transform method, and then the frequency domain analysis result is sent to the detection subunit 1423.

[0094] Specifically, based on the encoded infrasound signal, the initial digital vibration signal is transformed from the "time-amplitude" time domain dimension to the "frequency-amplitude" frequency domain dimension through Fourier transform, thereby extracting the frequency characteristics of the signal (such as the dominant frequency and frequency distribution) and determining whether the frequency components are abnormal due to pipeline defects.

[0095] For example, the Fast Fourier Transform (FFT) algorithm can be used to perform frequency domain transformation on the initial digital vibration signal, that is, to decompose the continuous vibration signal in the time domain (such as a digital signal sampled at 1000Hz and lasting 0~12s) into the superposition of different frequency components and obtain the "frequency-amplitude" frequency domain curve.

[0096] Furthermore, the dominant frequency value (i.e. the frequency point with the largest amplitude) of the frequency domain curve can be extracted, and the trajectory of the dominant frequency change over time can be tracked.

[0097] Furthermore, the main frequency range of the initial digital vibration signal and the encoded infrasound signal (e.g., the encoded signal is 5~25Hz) can be compared, and the percentage of time the main frequency exceeds this range and the maximum offset amplitude can be statistically analyzed.

[0098] Furthermore, the extracted main frequency trajectory, offset amplitude, and frequency distribution histogram can be compiled into a frequency domain analysis report, i.e., frequency domain analysis results, which can serve as the frequency domain basis for subsequent defect judgment.

[0099] Furthermore, the feature analysis subunit 1421 sends the obtained frequency domain analysis results to the detection subunit 1423.

[0100] Secondly, in the calculation subunit 1422, based on the initial digital vibration signal and the coded infrasound signal, the correlation coefficient value is calculated using the correlation coefficient analysis method, and then the correlation coefficient value is sent to the detection subunit 1423.

[0101] Specifically, the calculation subunit 1422 can calculate the similarity between the initial digital vibration signal and the coded infrasound signal using the correlation coefficient formula, and reflect in numerical form (0~1) whether the signal has energy attenuation and waveform distortion due to pipeline defects, providing a time-domain quantitative basis for defect judgment, as shown in the following relationship (3): (3) In the formula: The correlation coefficient function represents the correlation coefficient after a delay. At any given time, the similarity measure of two signals (initial digital vibration signal and coded infrasound signal), namely the correlation coefficient value (the larger the value, the more similar the signals). 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). This represents the initial digital vibration signal.

[0102] Furthermore, the calculation subunit 1422 sends the calculated correlation coefficient value to the detection subunit 1423.

[0103] Finally, in the detection subunit 1423, the detection results of structural defects in the drainage pipeline are determined based on the frequency domain analysis results and correlation coefficient values.

[0104] Specifically, the detection subunit 1423 can combine the frequency domain results (main frequency offset) of the feature analysis subunit 1421 with the correlation coefficient value (time domain similarity) of the calculation subunit 1422, and based on the preset judgment rules, finally determine whether there are structural defects in the pipeline and the approximate location of the defects, thus avoiding misjudgment caused by single-dimensional analysis.

[0105] For example, the preset judgment rule is the dual anomaly judgment principle, that is, if the frequency domain analysis shows that the main frequency offset is ≥ ±1Hz (or exceeds the frequency band of the encoded signal by 5~25Hz) and the correlation coefficient value is <0.995, then a defect is judged to exist if both conditions are met; if only one is abnormal or there are no abnormalities, then it is judged to be normal.

[0106] Furthermore, if the frequency domain analysis result is "no dominant frequency offset" and the correlation coefficient value is ≥0.995, it is determined that the corresponding pipe section has no structural defects.

[0107] Furthermore, if the frequency domain analysis result is "main frequency offset ≥ ±1Hz" (e.g., the main frequency of the received signal in a certain pipe section is consistently 27Hz), and the correlation coefficient value is 0.995, it is determined that the corresponding pipe section has structural defects such as damage or misalignment.

[0108] Furthermore, if only the frequency domain is abnormal or only the time domain is abnormal (such as a shift in the main frequency but a normal correlation coefficient, which may be due to temporary noise interference), it is marked as "suspected abnormality" and needs to be re-tested and verified.

[0109] Furthermore, the specific pipe section where the defect is located can be determined by combining the equipment layout location, and a structural defect detection result containing "pipe section number, defect judgment conclusion, frequency domain analysis data, correlation coefficient value, and suggested re-inspection time" can be generated.

[0110] Furthermore, the time synchronization unit 143 can be used to control the infrasound generation module 12 and the infrasound signal receiving module 13 to operate at the same time.

[0111] Specifically, the GPS clock module built into the time synchronization unit 143 can be used to provide a unified time reference for the infrasound emission module 12 and the infrasound signal receiving module 13, eliminating the signal timing misalignment caused by clock deviation and ensuring time synchronization between the emission and reception stages.

[0112] For example, the GPS clock module built into 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 a unified time reference for the system.

[0113] Furthermore, the GPS reference time can be sent to the transmitter controller 121 of the infrasound module 12 and the signal acquisition unit 132 of the infrasound signal receiving module via a wireless synchronization protocol (such as NTP network time protocol).

[0114] Furthermore, after receiving the synchronization signal, the transmitter controller 121 and the signal acquisition unit 132 automatically calibrate their internal real-time clock (RTC) to keep the error between their clocks and the GPS reference time within 1ms.

[0115] Furthermore, the time synchronization unit 143 can send a "signal transmission trigger command" to the transmission controller 121, and the command contains a precise transmission start time (such as time T0).

[0116] Meanwhile, the time synchronization unit 143 can send a "signal transmission trigger command" to the signal acquisition unit 132 to ensure that the signal acquisition unit 132 starts data acquisition synchronously at time T0, thereby avoiding signal omission or timing misalignment caused by the asynchronous start time of sound emission and acquisition.

[0117] Furthermore, during the testing process, the time synchronization unit 143 can also receive clock status information fed back by the transmitter controller 121 and the signal acquisition unit 132 in real time. If the clock deviation of a certain module is found to exceed 1ms, the synchronization signal is immediately resent for calibration to ensure that the timing of the two is consistent throughout the testing process.

[0118] The drainage pipeline structural defect detection system provided in this embodiment actively constructs and generates coded infrasound signals through a controller, ensuring that the signals have stable frequency and amplitude characteristics. Compared with traditional uncoded signals, it can effectively distinguish effective signals from environmental noise, solving the problem of signals being easily submerged in the complex operating conditions of sewage pipelines. Simultaneously, the coded signal is sent synchronously to the detection module, providing a "reference signal" for comparison and analysis of subsequent received signals, avoiding signal anomaly judgment errors caused by the lack of a reference. Furthermore, the infrasound emission module uses the coded infrasound signal for infrasound transmission and processing, and through internal signal processing and mechanical coupling design, enables the low-frequency mechanical vibration signal to propagate stably along the pipe wall, reducing energy attenuation and covering long-distance pipe sections that are difficult to reach with traditional passive detection. At the same time, the actively emitted vibration signal is not affected by sludge or gas-liquid two-phase flow within the pipeline, solving the problem of weak signals easily submerged by noise in gravity-flow sewage pipelines. Furthermore, by detecting the low-frequency mechanical vibration signal of the drainage pipeline through the infrasound signal receiving module, the dynamic changes of the signal propagating along the pipeline can be completely acquired, avoiding the omission of local defects. Simultaneously, converting analog signals into initial digital signals reduces interference and distortion during transmission, providing high-quality raw data for subsequent data analysis and solving the problems of traditional analog signals being susceptible to interference and having low data reliability. Furthermore, Fourier transform can extract the dominant frequency shift characteristics and identify frequency component changes caused by defects, while correlation coefficient analysis can quantify signal similarity and eliminate non-defect factors such as noise. The combination of these two methods avoids the high false positive rate of traditional single algorithms, ultimately providing accurate results on whether the pipeline is damaged, meeting the accuracy requirements for detecting structural defects in drainage pipelines under complex operating conditions. Therefore, by implementing this invention, the problem that traditional acoustic detection technology is insufficient to effectively identify damage and leakage issues in urban underground sewage pipe networks under complex operating conditions is solved.

[0119] According to an embodiment of the present invention, a method for detecting structural defects in drainage pipes is provided. It should be noted that the steps shown in the flowchart in the accompanying drawings can be executed in a computer system such as a set of computer-executable instructions. Furthermore, although a logical order is shown in the flowchart, in some cases, the steps shown or described may be executed in a different order than that shown here.

[0120] This embodiment provides a method for detecting structural defects in drainage pipes, which can be used in the drainage pipe structural defect detection system 1 provided in the above embodiments of the present invention. Figure 2 This is a flowchart of a method for detecting structural defects in drainage pipes according to an embodiment of the present invention, such as... Figure 2 As shown, the process includes the following steps: Step S201: Construct the encoded infrasound signal.

[0121] For a detailed description of the process, please refer to the functional description of the controller 11 in the drainage pipeline structural defect detection system 1 in the above embodiments of the present invention, which will not be repeated here.

[0122] Step S202: Infrasound is transmitted and processed using coded infrasound signals to obtain low-frequency mechanical vibration signals.

[0123] Low-frequency mechanical vibration signals are transmitted within the drainage pipes.

[0124] For the specific process, please refer to the functional description of the infrasound generation module 12 in the drainage pipeline structural defect detection system 1 in the above embodiments of the present invention, which will not be repeated here.

[0125] Step S203: Detect the low-frequency mechanical vibration signal of the drainage pipe and determine the initial digital vibration signal.

[0126] For the specific process, please refer to the functional description of the infrasound signal receiving module 13 in the drainage pipeline structural defect detection system 1 in the above embodiments of the present invention, which will not be repeated here.

[0127] Step S204: Based on the initial digital vibration signal and the coded infrasound signal, the structural defect detection results of the drainage pipeline are determined by processing them using the Fourier transform method and the correlation coefficient analysis method.

[0128] For a detailed description of the process, please refer to the functional description of the detection module 14 in the drainage pipeline structural defect detection system 1 in the above embodiments of the present invention, which will not be repeated here.

[0129] The drainage pipeline structural defect detection method provided in this embodiment actively constructs and generates coded infrasound signals, ensuring stable frequency and amplitude characteristics. Compared to traditional uncoded signals, it can effectively distinguish valid signals from environmental noise, solving the problem of signal submersion under complex sewage pipeline conditions. Furthermore, by actively emitting mechanical vibration signals, a stable active acoustic waveguide is formed along the pipe wall, unaffected by water flow conditions or silt accumulation within the pipe, covering pipe sections difficult to reach with traditional passive detection, meeting the needs of large-scale detection. Furthermore, 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 detections due to signal loss or distortion. Furthermore, by combining Fourier transform and correlation coefficient analysis methods for structural defect detection, the method can accurately identify whether the pipeline is damaged, avoiding the high false positive rate of traditional single algorithms, and ultimately accurately outputting the result of whether the pipeline is damaged, meeting the accuracy requirements for drainage pipeline structural defect detection under complex conditions. Therefore, by implementing this invention, the problem that traditional acoustic detection technology is difficult to meet the need for effective identification of damage and leakage in urban underground sewage pipe networks under complex operating conditions is solved.

[0130] In one example, a drainage pipeline structural defect detection device based on active acoustic waveguide is provided, including: an infrasound generation module, an infrasound signal receiving module, and a data analysis and processing and anomaly identification module.

[0131] The infrasound generation module is responsible for actively generating infrasound waves, enabling them to propagate stably along the pipe wall. Internally, it comprises four functional units: a transmitter controller, a power amplifier driver unit, a transmitter unit, and a coupling device. First, the transmitter controller, as the system's main control unit, is responsible for generating programmable low-frequency signals and controlling timing and spectral parameters. This controller supports remote task triggering and synchronous clock input. The transmitted signal is amplified by the power amplifier driver unit, transforming the low-level signal into a high-power signal capable of driving the transmitter. The power amplifier module possesses excellent low-frequency response characteristics and signal fidelity, ensuring that the mechanical vibration output by the transmitter is not distorted. The transmitter unit employs a piezoelectric ceramic sheet stack structure, receiving the power amplifier signal and converting it into low-frequency mechanical vibration. Finally, the mechanical vibration is efficiently transmitted to the pipe wall through the coupling device. The coupling device consists of flexible sound-conducting material and an elastic clamping arm, ensuring a tight fit between the transmitter and the pipe wall surface.

[0132] The infrasound signal receiving module is responsible for capturing the dynamic response of infrasound waves propagating through the pipe wall, serving as a direct carrier for sensing the pipe structure's condition. It comprises two parts: an inductive receiver array and a signal acquisition system. The inductive receiver array consists of multiple distributed sensors used to detect minute vibration responses within the pipe wall. These sensors effectively detect amplitude attenuation, waveform distortion, and echo information during infrasound propagation. Each receiver connects wirelessly to the signal acquisition system, which embeds an analog-to-digital converter (ADC) to convert analog signals into digital waveforms, transmitting them to the data analysis and anomaly identification module for further processing. Through this module, the system can acquire infrasound signals propagating through the pipe wall simultaneously and with high fidelity from multiple points, providing data support for locating leaks and damage.

[0133] The data analysis, processing, and anomaly identification module is responsible for data synchronization, feature extraction, and anomaly diagnosis of the received signals. This module comprises three functional systems: a time synchronization system, a signal preprocessing system, and a damage diagnosis algorithm system. The time synchronization system ensures that all transmitters and receivers operate at the same time, avoiding time difference interference with wave speed. The system uses a GPS clock module, and the central control system performs unified calibration of all nodes before detection begins, ensuring that the system error does not exceed 1 ms. The signal preprocessing system cleans and reconstructs the structure of the raw acquired data. Key steps include DC drift removal, bandpass filtering, and time-domain registration, improving signal quality and defect identifiability. The damage diagnosis algorithm system mainly includes two core modules: Fourier transform and correlation coefficient analysis. First, Fourier transform is used to perform frequency domain analysis on the infrasound signals received at the monitoring points, suitable for extracting frequency components and analyzing dominant frequency shift phenomena. Simultaneously, the correlation coefficient analysis module calculates the similarity between the received and transmitted signals. When the received signal does not match the emitted signal in terms of frequency offset, energy attenuation, and related peak positions, it is considered that the pipe section has structural defects such as damage or misalignment; otherwise, its structural condition is judged to be normal.

[0134] Furthermore, such as Figure 3 As shown, the specific implementation steps of the drainage pipeline structural defect detection method based on active acoustic guided waves are as follows: Step 1: Data collection of the drainage pipe to be inspected.

[0135] For drainage pipes suspected of having structural defects such as damage or misalignment, basic data is collected, including a GIS map of the drainage system, pipe materials, pipe diameter, pipe length, flow direction, elevation, manhole numbers, and coordinates. Based on the topological connections of the drainage pipes under inspection and actual operating conditions, the infrasound propagation path and the distribution of manholes along the route are determined, providing a basis for subsequent infrasound equipment deployment.

[0136] Step 2: Deployment of infrasound generating and receiving equipment.

[0137] An infrasound generating module is installed inside a manhole at one end of the pipeline to be inspected. The generator unit is positioned close to the manhole wall, and a coupling device consisting of flexible sound-conducting material and an elastic clamping arm is used to maintain stable mechanical coupling between the generator and the manhole wall, ensuring efficient transmission of mechanical vibrations into the pipeline. An infrasound receiving module is installed inside a manhole at the other end of the pipeline. The receiver is fixed to the inner wall of the target manhole using sound-conducting adhesive and connected to a portable wireless signal acquisition system.

[0138] Step 3: Infrasound signal encoding.

[0139] To improve the reliability of infrasound signal transmission and reception in the complex environment of urban drainage pipeline systems, this invention encodes the infrasound signal. This invention uses linear frequency modulation to encode the infrasound signal, thereby improving the signal's identifiability, anti-interference ability, and detection accuracy. This enables the effective differentiation of infrasound signals from background noise in engineering practice, enhancing the damage diagnosis capability. The encoding form is shown in the above-mentioned relation (2).

[0140] Step 4: Infrasound signal generation, reception, and structural defect detection.

[0141] The power amplifier unit amplifies the infrasound signal encoded in step 3. The system generates coded infrasound waves that propagate along the pipe wall via a sound-generating unit. Upon receiving the infrasound signal, the receiver first converts the analog signal to a digital signal using an analog-to-digital converter (ADC) and transmits it to a data analysis and anomaly detection platform. The data analysis and anomaly detection module then performs DC-drift removal on the digital signal, bringing the entire waveform back to a steady-state zero baseline. A bandpass filter is then used to confine the signal to the coded frequency band of the emitted infrasound (typically the 10-30 Hz range covered by the sweep signal), preserving the effective signal while effectively suppressing infrasound interference from low-frequency ground vibrations and high-frequency signals. Based on this, the system further performs time-domain registration processing, precisely aligning the received signal with the corresponding emitted signal on the time axis. The registered signal is then analyzed using Fourier transform, and methods such as correlation coefficient analysis are employed to calculate the relationship between the signal and the emitted infrasound signal. The temporal similarity is used to identify pipeline damage characteristics, as shown in the above relation (3).

[0142] Furthermore, after completing the correlation coefficient calculation, the time-domain characteristics of the sound signals emitted and received by each pipeline are compared, and the correlation coefficient calculation results of each pipeline are combined to confirm whether there is any damage to the pipeline section.

[0143] The drainage pipeline structural defect detection equipment and method based on active acoustic guided waves provided in this example have the following effects: 1. For drainage pipe networks that mainly operate under gravity flow or weak pressure flow, an innovative rapid detection method for pipe structural defects based on active acoustic guided wave is proposed. Since this technology can be used while the pipe is wet and does not interfere with the operation of the pipe, it can effectively meet the needs of rapid, low-cost and large-scale inspection of drainage pipe networks.

[0144] 2. By encoding infrasound signals and conducting active waveguide, the inaccuracy of traditional passive acoustic wave detection technology is overcome. This is mainly because traditional methods indirectly determine structural defects by listening to weak acoustic wave signals generated by leakage, which is easily affected by environmental noise and other factors.

[0145] In an optional embodiment, the method for detecting structural defects in drainage pipes based on active acoustic waveguides specifically includes: Step 1: Data collection of the drainage pipe to be inspected.

[0146] Specifically, the above example is illustrated using a drainage area with a damaged sewage pipe as an example. The demonstration area is as follows: Figure 4 As shown.

[0147] Furthermore, based on upstream and downstream flow measurements, a suspected leak was found in the sewage pipeline section BC. Basic data for this pipeline network area was collected, the topological connections of the sewage pipelines were clarified, and the number of inspection wells, pipe diameters, pipe materials, flow directions, and inspection records for each section of the sewage pipeline were identified. Figure 5 As shown, section BC is a reinforced concrete pipe with a diameter of 800 mm. There are two inspection wells between the sewage pipes in section BC, each 30 meters apart. No geophysical exploration has been carried out. Based on the flow analysis, it is suspected that there is a problem of groundwater infiltration due to damage.

[0148] Step 2: Deployment of infrasound generating and receiving equipment.

[0149] 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.

[0150] Step 3: Infrasound signal encoding.

[0151] 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, ; .

[0152] 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.

[0153] 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.

[0154] Step 4: Infrasound signal generation, reception, and structural defect detection 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: (4) 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).

[0155] Furthermore, the correlation coefficient analysis results and the comparison between the measured signal and the emitted signal, for example... Figure 8As 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.

[0156] 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.

[0157] 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.

[0158] Processor 10 may be a central processing unit, a network processor, or a combination thereof. Processor 10 may further include a hardware chip. The hardware chip may be an application-specific integrated circuit (ASIC), a programmable logic device (PLD), or a combination thereof. The programmable logic device may be a complex programmable logic device (CAMP), a field-programmable gate array (FPGA), a general-purpose array logic (GDA), or any combination thereof.

[0159] The memory 20 stores instructions executable by at least one processor 10 to cause at least one processor 10 to perform the method shown in the above embodiments.

[0160] The memory 20 may include a program storage area and a data storage area. The program storage area may store the operating system and applications required for at least one function; the data storage area may store data created based on the use of the computer device. Furthermore, the memory 20 may include high-speed random access memory and may also include non-transitory memory, such as at least one disk storage device, flash memory device, or other non-transitory solid-state storage device. In some alternative embodiments, the memory 20 may optionally include memory remotely located relative to the processor 10, and these remote memories may be connected to the computer device via a network. Examples of such networks include, but are not limited to, the Internet, intranets, local area networks, mobile communication networks, and combinations thereof.

[0161] The memory 20 may include volatile memory, such as random access memory; the memory may also include non-volatile memory, such as flash memory, hard disk or solid-state drive; the memory 20 may also include a combination of the above types of memory.

[0162] The computer device also includes a communication interface 30 for communicating with other devices or communication networks.

[0163] This invention also provides a computer-readable storage medium. The methods described above according to embodiments of the invention can be implemented in hardware or firmware, or implemented as computer code that can be recorded on a storage medium, or implemented as computer code downloaded via a network and originally stored on a remote storage medium or a non-transitory machine-readable storage medium and then stored on a local storage medium. Thus, the methods described herein can be processed by software stored on a storage medium using a general-purpose computer, a dedicated processor, or programmable or dedicated hardware. The storage medium can be a magnetic disk, optical disk, read-only memory, random access memory, flash memory, hard disk, or solid-state drive, etc.; further, the storage medium can also include combinations of the above types of memory. It is understood that computers, processors, microprocessor controllers, or programmable hardware include storage components capable of storing or receiving software or computer code, which, when accessed and executed by the computer, processor, or hardware, implements the methods shown in the above embodiments.

[0164] A portion of this invention can be applied as a computer program product, such as computer program instructions, which, when executed by a computer, can invoke or provide the methods and / or technical solutions according to the invention through the operation of the computer. Those skilled in the art will understand that the forms in which computer program instructions exist in a computer-readable medium include, but are not limited to, source files, executable files, installation package files, etc. Correspondingly, the ways in which computer program instructions are executed by a computer include, but are not limited to: the computer directly executing the instructions, or the computer compiling the instructions and then executing the corresponding compiled program, or the computer reading and executing the instructions, or the computer reading and installing the instructions and then executing the corresponding installed program. Here, the computer-readable medium can be any available computer-readable storage medium or communication medium accessible to a computer.

[0165] Although embodiments of the invention have been described in conjunction with the accompanying drawings, those skilled in the art can make various modifications and variations without departing from the spirit and scope of the invention, and such modifications and variations all 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 inspection wells at different ends of a 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 determine a structural defect detection result of the drainage pipeline based on the initial digital vibration signal and the encoded infrasound wave signal through a Fourier transform method and a correlation coefficient analysis method.

2. The system of claim 1, wherein, 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; The construction unit is configured to construct the encoded infrasound wave signal according to the time signal sequence.

3. The system of claim 1, wherein, 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 compression 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 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.

4. 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.

5. 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 by using a Fourier transform method and a correlation coefficient analysis method, and determine the structural defect detection result of the drainage pipeline.

6. The system of claim 5, 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 by using 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 by using 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.

7. The system of claim 5, wherein, 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.

8. A method of detecting structural defects in a sewer pipe, characterized by, The method comprises: Constructing a coded infrasound wave signal; Using the coded infrasound wave signal to perform infrasound wave emission and processing 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 and determining an initial digital vibration signal; Processing the initial digital vibration signal and the coded infrasound wave signal by using a Fourier transform method and a correlation coefficient analysis method to determine a structural defect detection result of the drainage pipeline.

9. 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 8.

10. 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 8. The computer readable storage medium stores computer instructions for causing a computer to execute the drainage pipeline structural defect detection method of claim 8.

Images