Drainage pipeline defect detection method, device, equipment, medium and program product

Abstract

The present application relates to the technical field of drainage pipeline, and discloses a drainage pipeline defect detection method, device, equipment, medium and program product.The drainage pipeline defect detection method comprises the following steps: controlling an infrasonic wave signal transmitter to emit an infrasonic wave signal to a target drainage pipeline, and collecting multiple initial echo signals of an infrasonic wave signal receiver array; performing pulse compression processing on each initial echo signal to obtain multiple pulse compression output signals; determining the echo arrival time corresponding to each pulse compression output signal according to the relevant peak position in each pulse compression output signal; and determining the position of the defect in the target drainage pipeline according to the echo arrival time corresponding to each pulse compression output signal, the position information of the infrasonic wave signal transmitter, the position information of each sensor element in the infrasonic wave signal receiver array and a preset sound speed.The present application detects the position of the drainage pipeline defect by processing the echo signal, thereby improving the accuracy of the drainage pipeline defect detection.

Description

Technical Field

[0001] This invention relates to the field of drainage pipeline technology, specifically to methods, devices, equipment, media, and procedures for detecting defects in drainage pipelines. Background Technology

[0002] As a vital urban infrastructure, drainage pipes are prone to structural and functional defects due to aging, corrosion, and external damage. These defects can manifest as collapse, sediment buildup, scaling, and foreign object intrusion, reducing the effective flow area and leading to poor drainage and high water levels. Therefore, timely inspection of drainage pipe defects is essential.

[0003] Among related technologies, closed-circuit television (CCTV) inspection and sonar inspection are used to detect defects in drainage pipes. CCTV inspection involves inserting a camera-equipped inspection device into the pipe to be inspected and transmitting real-time images of the pipe's interior to a ground control terminal via wired transmission. However, CCTV inspection requires complex operations such as sealing and dewatering before implementation, resulting in high costs and low efficiency. Sonar inspection utilizes the propagation and reflection characteristics of sound waves in a medium to reconstruct the geometric shape, location, and size of defects in drainage pipes. However, sonar can only be used underwater, making it impossible to detect defects in pipes above the water surface. Summary of the Invention

[0004] This invention provides a method, apparatus, equipment, medium, and program product for detecting defects in drainage pipes, in order to solve the problems of low efficiency and inability to detect defects in pipes above the water surface caused by related technologies.

[0005] In a first aspect, the present invention provides a method for detecting defects in a drainage pipe, comprising: controlling an infrasound signal transmitter to transmit an infrasound signal to a target drainage pipe, and acquiring multiple initial echo signals from an infrasound signal receiver array; the initial echo signals are echo signals generated by the transmission of the infrasound signal in the target drainage pipe; performing pulse compression processing on each initial echo signal to obtain multiple pulse compression output signals; determining the echo arrival time corresponding to each pulse compression output signal based on the position of the relevant peak in each pulse compression output signal; and determining the location of the defect in the target drainage pipe based on the echo arrival time corresponding to each pulse compression output signal, the position information of the infrasound signal transmitter, the position information of each sensor element in the infrasound signal receiver array, and a preset sound velocity.

[0006] This invention provides a defect detection method for drainage pipes. It controls an infrasound signal transmitter to emit infrasound signals towards the target drainage pipe and collects multiple initial echo signals from an infrasound signal receiver array. This method utilizes the stable propagation and strong penetrating power of infrasound in the target drainage pipe medium. Furthermore, infrasound can propagate in both air and water, ensuring defect detection across the entire target drainage pipe. The infrasound signal receiver array enables multi-dimensional signal acquisition, avoiding blind spots in single infrasound signal receivers and improving the comprehensiveness of echo signal coverage. This invention performs pulse compression processing on each initial echo signal, obtaining multiple pulse-compressed output signals. Pulse compression improves the signal-to-noise ratio of the echo signals, while also compressing the signal width and enhancing signal resolution, making subsequent echo feature identification more accurate and reducing false defect judgments caused by noise. Based on the position of the relevant peaks in each pulse-compressed output signal, this invention determines the echo arrival time corresponding to each pulse-compressed output signal. Locating the echo arrival time by the relevant peak position is more accurate and has stronger anti-interference capabilities than directly identifying the original signal, reducing time measurement errors and providing reliable time data for subsequent defect location. This invention determines the location of defects in a target drainage pipe based on the echo arrival time corresponding to each pulse compression output signal, the position information of the infrasound signal transmitter, the position information of each sensor element in the infrasound signal receiver array, and a preset sound velocity. By combining multiple parameters and utilizing multi-sensor data from the infrasound signal receiver array, it achieves precise defect location, improves the spatial accuracy of detection, and facilitates subsequent targeted maintenance. Compared with related technologies, this invention can detect defects in both the underwater and above-water sections of the target drainage pipe, reducing the cost of drainage pipe defect detection and improving its accuracy.

[0007] In one optional implementation, controlling an infrasound signal transmitter to emit infrasound signals toward a target drainage pipe, and collecting multiple initial echo signals from an infrasound signal receiver array, includes: controlling the infrasound signal transmitter to emit coded infrasound signals into the air or water of the target drainage pipe; the infrasound signal transmitter being installed in the air or water at the inlet of the target drainage pipe via a downstream inspection well; collecting the initial echo signal of each sensor element in the infrasound signal receiver array; and the infrasound signal receiver array being installed in the air or water at the inlet of the target drainage pipe via an upstream inspection well.

[0008] In one optional implementation, pulse compression processing is performed on each initial echo signal to obtain multiple pulse-compressed output signals, including: filtering each initial echo signal to obtain multiple first echo signals; performing amplitude consistency processing on each first echo signal to obtain multiple second echo signals; performing baseline correction processing on each second echo signal to obtain multiple third echo signals; determining the impulse response signal based on the time mirror of the infrasound signal; and convolving each third echo signal with the impulse response signal to obtain multiple pulse-compressed output signals.

[0009] This invention filters each initial echo signal to obtain multiple first echo signals, filtering out interference signals such as environmental noise and pipeline-irrelevant vibrations, while retaining effective signals related to infrasound propagation, thus improving the signal purity for subsequent processing. This invention performs amplitude consistency processing on each first echo signal to obtain multiple second echo signals, eliminating amplitude fluctuations caused by hardware differences and signal propagation path differences between different sensor array elements, making the echo signals of each channel more uniform in amplitude dimension, and avoiding interference from amplitude differences in subsequent feature recognition. This invention performs baseline correction processing on each second echo signal to obtain multiple third echo signals, correcting baseline drift and making the signal reference more stable. This invention determines the impulse response signal based on the time mirror of the infrasound signal, and convolves each third echo signal with the impulse response signal to obtain multiple pulse compression output signals. This further compresses the signal width, improves the signal's temporal resolution, enhances the correlation peak characteristics of the signal, makes the identification of subsequent echo arrival times more accurate, and improves the signal-to-noise ratio.

[0010] In one optional implementation, determining the echo arrival time corresponding to each pulse compression output signal based on the position of the relevant peak in each pulse compression output signal includes: performing peak detection on each pulse compression output signal to obtain the position of the relevant peak of each pulse compression output signal; and using the time corresponding to the position of the relevant peak as the echo arrival time corresponding to each pulse compression output signal.

[0011] In one optional implementation, the location of a defect in the target drainage pipe is determined based on the echo arrival time corresponding to each pulse compression output signal, the location information of the infrasound signal transmitter, the location information of each sensor element in the infrasound signal receiver array, and a preset sound velocity. This includes: using the location of the defect in the target drainage pipe as a variable, constructing multiple time-path relationships based on the echo arrival time corresponding to each pulse compression output signal, the location information of the infrasound signal transmitter, the location information of each sensor element in the infrasound signal receiver array, and a preset sound velocity; obtaining a preset time difference; using the preset time difference as a constraint, and taking the minimum error between the echo arrival time and the preset echo arrival time as the objective function, solving the multiple time-path relationships to obtain the location of the defect in the target drainage pipe.

[0012] This invention sets the defect location as a variable and constructs multiple time-path relationships by combining multiple sets of echo arrival times, the location information of the infrasound signal transmitter, the location information of each sensor element in the infrasound signal receiver array, and a preset sound velocity. This is equivalent to establishing a mathematical model for positioning using multi-dimensional data, avoiding the limitations of single data sources and providing a multi-constraint computational basis for accurate positioning. By using a preset time difference as a constraint, this invention narrows the solution range and avoids unreasonable solutions. With minimizing error as the objective function, the optimized algorithm makes the calculation results more closely match the actual signal conditions, reducing the influence of errors from single relationships, ultimately improving the calculation accuracy of the defect location, making the positioning results more reliable, and improving the accuracy of defect detection in target drainage pipes.

[0013] In one optional implementation, obtaining the preset time difference includes: selecting a reference sensor element in the infrasound signal receiver array, and obtaining the preset time difference based on the difference between the echo arrival time corresponding to each pulse compression output signal and the echo arrival time of the reference sensor element.

[0014] Secondly, the present invention provides a defect detection device for drainage pipes, comprising: a signal acquisition module for controlling an infrasound signal transmitter to transmit infrasound signals to a target drainage pipe and acquiring multiple initial echo signals from an infrasound signal receiver array; the initial echo signals are echo signals generated by the transmission of infrasound signals in the target drainage pipe; a compression processing module for performing pulse compression processing on each initial echo signal to obtain multiple pulse compression output signals; a time determination module for determining the echo arrival time corresponding to each pulse compression output signal based on the position of the relevant peak in each pulse compression output signal; and a defect location module for determining the location of a defect in the target drainage pipe based on the echo arrival time corresponding to each pulse compression output signal, the position information of the infrasound signal transmitter, the position information of each sensor element in the infrasound signal receiver array, and a preset sound velocity.

[0015] Thirdly, the present invention provides an electronic device, comprising: a memory and a processor, wherein the memory and the processor are communicatively connected to each other, the memory stores computer instructions, and the processor executes the computer instructions to perform the defect detection method for drainage pipes described in the first aspect or any corresponding embodiment thereof.

[0016] Fourthly, the present invention provides a computer-readable storage medium storing computer instructions for causing a computer to execute the defect detection method for drainage pipes described in the first aspect or any corresponding embodiment thereof.

[0017] Fifthly, the present invention provides a computer program product, including computer instructions for causing a computer to execute the method for detecting defects in drainage pipes described in the first aspect or any corresponding embodiment. Attached Figure Description

[0018] 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.

[0019] Figure 1 This is a schematic diagram of an application scenario according to an embodiment of the present invention;

[0020] Figure 2 This is a schematic flowchart of a first method for detecting defects in drainage pipes according to an embodiment of the present invention.

[0021] Figure 3 This is a schematic diagram of the layout of a drainage pipe defect detection device according to an embodiment of the present invention;

[0022] Figure 4 This is a schematic diagram of a second process for a defect detection method for drainage pipes according to an embodiment of the present invention;

[0023] Figure 5 This is a schematic diagram of linear frequency modulation signal generation according to an embodiment of the present invention;

[0024] Figure 6 This is a schematic diagram of the synchronous acquisition of the initial echo signal according to an embodiment of the present invention;

[0025] Figure 7 This is a schematic diagram of multiple third echo signals after preprocessing according to an embodiment of the present invention;

[0026] Figure 8This is a schematic diagram of pulse compression processing according to an embodiment of the present invention;

[0027] Figure 9 This is a schematic diagram of multi-channel signal superposition and enhancement according to an embodiment of the present invention;

[0028] Figure 10 This is a schematic diagram of the third process of a defect detection method for drainage pipes according to an embodiment of the present invention;

[0029] Figure 11 This is a schematic diagram showing the spatial location of a defect in a drainage pipe according to an embodiment of the present invention;

[0030] Figure 12 This is a structural block diagram of a defect detection device for drainage pipes according to an embodiment of the present invention;

[0031] Figure 13 This is a schematic diagram of the hardware structure of an electronic device according to an embodiment of the present invention. Detailed Implementation

[0032] 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.

[0033] It is understood that before using the technical solutions disclosed in the various embodiments of the present invention, users should be informed of the types, scope of use, and usage scenarios of the personal information involved in the present invention and their authorization should be obtained in accordance with relevant laws and regulations through appropriate means.

[0034] The terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0035] As an optional application scenario of this invention, such as Figure 1 As shown, the defect detection system for the drainage pipe may include at least one terminal device and at least one server. Figure 1 The system is illustrated in the example, which includes a computer 101, a mobile terminal 102, and a server 103, and the terminal devices such as the computer 101 and the mobile terminal 102 are connected to the server 103 through a network 110.

[0036] Specifically, the terminal device can be a smartphone, tablet, laptop, PDA, desktop computer, game console, smart TV, smart wearable device, in-vehicle terminal, VR (Virtual Reality) device, AR (Augmented Reality) device, etc. Server 103 can be a standalone physical server, a server cluster, a distributed system, or a cloud server providing cloud services. Network 110 can be a wired or wireless network, examples of which include, but are not limited to, the Internet, corporate intranet, local area network, wide area network, mobile communication network, and combinations thereof.

[0037] As an important urban infrastructure, drainage pipes are prone to causing urban flooding and sewage overflow when they suffer structural and functional defects due to aging, corrosion, or external damage.

[0038] Currently, non-destructive testing technologies, such as ground-penetrating radar (GPR) and seismic wave methods, are increasingly being applied to the detection of defects in drainage pipes. However, GPR suffers from severe signal attenuation and low resolution in saturated soil and water; seismic wave methods are easily affected by environmental vibrations and are difficult to accurately locate the fine internal structure of pipes.

[0039] Infrasound has the characteristics of long wavelength, strong penetration ability, and low attenuation in pipelines, making it theoretically suitable for underground pipeline inspection. However, related technologies mostly use passive infrasound (such as leakage noise) or a single sensor for measurement, which has problems such as poor positioning accuracy and weak anti-interference ability.

[0040] This invention provides a method for detecting defects in drainage pipes. By processing the echo signal, the method detects the location of defects in the drainage pipes, thereby improving the accuracy of defect detection.

[0041] According to an embodiment of the present invention, a method for detecting 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.

[0042] This embodiment provides a method for detecting defects in drainage pipes, which can be used with computer equipment. Figure 2 This is a first flowchart of a defect detection method for drainage pipes according to an embodiment of the present invention, as follows: Figure 2 As shown, the process includes the following steps:

[0043] Step S201: Control the infrasound signal transmitter to transmit infrasound signals to the target drainage pipe and collect multiple initial echo signals from the infrasound signal receiver array; the initial echo signals are the echo signals generated by the infrasound signals as they are transmitted in the target drainage pipe.

[0044] The infrasound signal transmitter is a device that emits infrasound signals, which are sound waves with a frequency below 20 Hz; the target drainage pipe is the drainage pipe to be inspected for defects; the infrasound signal is a low-frequency sound wave signal emitted by the infrasound signal transmitter for detecting defects in the drainage pipe; the infrasound signal receiver array is a collection of devices consisting of multiple sensor elements arranged in sequence for receiving echo signals; the initial echo signal is the original signal reflected back after the infrasound signal propagates within the target drainage pipe and encounters obstacles such as defects; one sensor element corresponds to one initial echo signal.

[0045] In some optional implementations, one infrasound signal transmitter corresponds to a set of infrasound signal receiver arrays. When the infrasound signal transmitter and the corresponding infrasound signal receiver array are deployed in the water medium of the target drainage pipe network, defect detection is performed on the drainage pipe section where the water medium is located. When the infrasound signal transmitter and the corresponding infrasound signal receiver array are deployed in the air medium of the target drainage pipe network, defect detection is performed on the drainage pipe section where the air medium is located.

[0046] For example, such as Figure 3 The diagram shows the layout of a device for detecting defects in a drainage pipe. The target drainage pipe is 50.0 meters long, 1.0 meter in diameter, and 0.2 meters deep. The top of the pipe has a collapse defect, and the distance between the collapse and the downstream inspection well is 30.0 meters. An infrasound transmitter is installed in the air or water at the inlet of the target drainage pipe through the downstream inspection well. An infrasound receiver array is installed in the air or water at the inlet of the target drainage pipe through the upstream inspection well. When deploying the infrasound transmitter, the contact surface should fit the cross-section of the medium to prevent energy leakage. The infrasound receiver array is arranged vertically, with N sensor elements (e.g., 8). The spacing between the sensor elements must satisfy the spatial sampling theorem.

[0047] ;

[0048] in, The spacing between sensor array elements, This is the smallest wavelength of the highest frequency component of a sound wave in the current medium. For example, when the frequency of a sound wave in air is 45 Hz (Hertz), =340 / 45≈7.56m, therefore The spacing should be ≤3.78m. In practice, a spacing much smaller than this value can be used to improve spatial resolution and avoid spatial aliasing. At the same time, the total height of the array must cover the vertical range of the same pipe medium (water flow, air) cross-section to ensure complete acquisition of the echo signal of the pipe cross-section.

[0049] exist Figure 3 In the process, a three-dimensional adjustable positioning mechanism is used to deploy the above-mentioned infrasound signal transmitter and infrasound signal receiver array. The three-dimensional adjustable positioning mechanism is set up at the upstream or downstream inspection well opening. The position of the infrasound signal transmitter and infrasound signal receiver array in the inspection well is adjusted by a control rod that can move up and down, left and right, and forward and backward. The space conditions of the inspection well and the installation status of the device are observed through the camera at the front end of the control rod.

[0050] Step S202: Perform pulse compression processing on each initial echo signal to obtain multiple pulse compressed output signals.

[0051] Among them, pulse compression processing is a process of improving resolution by compressing the signal width; multiple pulse compression output signals are echo signals after pulse compression processing, and one initial echo signal corresponds to one pulse compression output signal.

[0052] Step S203: Determine the echo arrival time corresponding to each pulse compressed output signal based on the position of the relevant peak in each pulse compressed output signal.

[0053] Among them, the correlation peak position is the time position corresponding to the peak value representing the valid echo in the signal; the echo arrival time is the time from the transmission of the echo signal to its reception by the receiver.

[0054] Step S204: Determine the location of the defect in the target drainage pipe based on the echo arrival time corresponding to each pulse compression output signal, the position information of the infrasound signal transmitter, the position information of each sensor element in the infrasound signal receiver array, and the preset sound velocity.

[0055] Among them, the position information of the infrasound signal transmitter can be the spatial coordinates of the infrasound signal transmitter, and the position information of each sensor element in the infrasound signal receiver array can be the spatial coordinates of each sensor element.

[0056] In some alternative implementations, based on the relationship between echo arrival time and sound path, a set of nonlinear equations is constructed according to the echo arrival time corresponding to each pulse compression output signal, the position information of the infrasound signal transmitter, the position information of each sensor element in the infrasound signal receiver array, and the preset sound velocity. The location of the defect in the target drainage pipe is obtained by solving the set of nonlinear equations using the least squares method.

[0057] The location of the defect in the target drainage pipe can be the spatial coordinates of the defect in the target drainage pipe.

[0058] The defect detection method for drainage pipes provided in this embodiment controls an infrasound signal transmitter to emit infrasound signals towards the target drainage pipe and collects multiple initial echo signals from an infrasound signal receiver array. This method utilizes the stable propagation and strong penetrating power of infrasound in the target drainage pipe medium. Furthermore, infrasound can propagate in both air and water, ensuring defect detection across the entire target drainage pipe. The infrasound signal receiver array also enables multi-dimensional signal acquisition, avoiding information blind spots from a single infrasound signal receiver and improving the comprehensiveness of echo signal coverage. This embodiment performs pulse compression processing on each initial echo signal to obtain multiple pulse-compressed output signals. Pulse compression improves the signal-to-noise ratio of the echo signals, while also compressing the signal width and enhancing signal resolution, making subsequent echo feature identification more accurate and reducing false defect judgments caused by noise. This invention determines the echo arrival time of each pulse-compressed output signal based on the position of the relevant peak in each pulse-compressed output signal. Locating the echo arrival time by the relevant peak position is more accurate and has stronger anti-interference capabilities than directly identifying the original signal, reducing time measurement errors and providing reliable time data for subsequent defect location. This invention also determines the location of defects in the target drainage pipe based on the echo arrival time of each pulse-compressed output signal, the position information of the infrasound signal transmitter, the position information of each sensor element in the infrasound signal receiver array, and a preset sound velocity. By combining multiple parameters and using multi-sensor data from the infrasound signal receiver array, precise defect location is achieved, improving the spatial accuracy of detection and facilitating subsequent targeted repairs. Compared with related technologies, this invention can detect defects in both the underwater and above-water sections of the target drainage pipe, reducing the cost of drainage pipe defect detection and improving its accuracy.

[0059] This embodiment provides a method for detecting defects in drainage pipes, which can be used with computer equipment. Figure 4 This is a second flowchart of a defect detection method for drainage pipes according to an embodiment of the present invention, as follows: Figure 4 As shown, the process includes the following steps:

[0060] Step S401: Control the infrasound signal transmitter to transmit infrasound signals to the target drainage pipe and collect multiple initial echo signals from the infrasound signal receiver array; the initial echo signals are the echo signals generated by the infrasound signals as they are transmitted in the target drainage pipe.

[0061] Specifically, step S401 includes:

[0062] Step S4011: Control the infrasound signal transmitter to transmit the encoded infrasound signal into the air or water of the target drainage pipe; the infrasound signal transmitter is installed in the air or water at the inlet of the target drainage pipe through a downstream inspection well.

[0063] For example, the encoded infrasound signal can be a linear frequency modulated (LFM) signal, and the expression for an LFM signal is:

[0064] ;

[0065] in, It is a linear frequency modulated signal. This is the Hanning window function (which suppresses sidelobes in the signal spectrum). The starting frequency, For frequency modulation slope, , For the termination frequency, The duration of the pulse. For pulse duration, This is the initial phase.

[0066] For example, such as Figure 5 The diagram illustrates the generation of a linear frequency modulated (LFM) signal. One infrasound transmitter is deployed in the air medium at the downstream inlet of the pipeline via a downstream inspection manhole. The effective area of ​​the transmitter is adapted to the cross-section of the medium. Eight infrasound receivers are vertically arranged at the downstream inlet of the pipeline via an upstream inspection manhole, with equal spacing (0.1m). Their effective receiving range is adapted to the entire cross-section of the medium. The coded sound wave type of the infrasound transmitter is linear frequency modulated (LFM) infrasound, with a frequency range of 15–45Hz and a pulse width of 1s. Figure 5 It includes the time-domain plot and spectrum plot of the Linear Frequency Modulation (LFM) signal. For the time-domain plot, the horizontal axis is time and the vertical axis is amplitude. For the spectrum plot, the horizontal axis is frequency and the vertical axis is amplitude.

[0067] Step S4012: Acquire the initial echo signal of each sensor element in the infrasound signal receiver array; the infrasound signal receiver array is installed in the air or water at the inlet of the target drainage pipe through an upstream inspection well.

[0068] In this process, the infrasound signal propagates through the target drainage pipe, generating the initial echo signal of each sensor element. Using a multi-channel data acquisition card, the initial echo signal of each sensor element in the infrasound signal receiver array is acquired synchronously, with the acquisition duration covering the entire cycle of signal transmission, propagation, and reflection. Each sensor element maintains high synchronous acquisition accuracy to ensure consistency of the time axis of each channel.

[0069] For example, such as Figure 6 The diagram shows the synchronous acquisition of the initial echo signal. An array of eight sensor elements synchronously acquires the initial echo signal generated after it is emitted by the infrasound transmitter and propagates through a pipe. Figure 6 As shown, each sub-figure corresponds to the output of a sensor element. The initial echo signal contains a large amount of environmental noise, electromagnetic interference, and system noise. At approximately 0.5 seconds on the time axis, a weak echo pulse (submerged in noise) is visible, which is the reflection signal from the defect. There are slight time delay differences in the signals of each channel, which stems from the difference in acoustic path from the defect reflection point to different array elements.

[0070] Step S402: Perform pulse compression processing on each initial echo signal to obtain multiple pulse compressed output signals.

[0071] Specifically, step S402 includes:

[0072] Step S4021: Filter each initial echo signal to obtain multiple first echo signals, perform amplitude consistency processing on each first echo signal to obtain multiple second echo signals, and perform baseline correction processing on each second echo signal to obtain multiple third echo signals.

[0073] The process involves using a digital filter to filter the initial echo signal, removing environmental noise and electromagnetic interference outside the passband to obtain multiple first echo signals. The amplifier gain is dynamically adjusted based on the amplitude of the first echo signal to ensure that the amplitude of each sensor element signal is within the linear operating range of the data acquisition card (avoiding signal saturation or undersampling), and that the amplitude difference between each channel is less than or equal to 5%, thus performing amplitude consistency processing on each first echo signal. The DC offset caused by hardware differences (such as sensor sensitivity deviation and cable attenuation) in each second echo signal is eliminated, making the zero signal level of each second echo signal consistent, thus performing baseline correction processing on each second echo signal to obtain multiple third echo signals.

[0074] For example, such as Figure 7 The diagram shows multiple third echo signals after preprocessing. Preprocessing of the initial signal includes: filtering out noise outside the passband (e.g., beyond 20-50Hz), dynamically adjusting the gain of each channel to normalize the signal amplitude for consistency in subsequent superposition, and eliminating sensor DC bias and low-frequency drift. The preprocessed signals for each channel are shown below. Figure 7 As shown.

[0075] Step S4022: Based on the time mirror of the infrasound signal, determine the impulse response signal, and convolve each third echo signal with the impulse response signal to obtain multiple pulse compression output signals.

[0076] Based on matched filtering theory, the impulse response signal of the matched filter is designed. The expression for the impulse response signal is a time mirror image of the infrasound signal, i.e.:

[0077] ;

[0078] in, For impulse response signal, It is a time mirror image of the infrasound signal.

[0079] For the discrete domain, the impulse response signal is:

[0080] ;

[0081] in, For impulse response signal, For discrete time series indexing, This represents the total number of sampling points.

[0082] In some alternative implementations, the formula for convolving each third echo signal with the impulse response signal to obtain multiple pulse-compressed output signals is as follows:

[0083] ;

[0084] in, For the first Each pulse is compressed to output a signal. For time delay variables, For the first The third echo signal, This is the impulse response signal.

[0085] In this embodiment of the invention, the convolution processing step can transform the originally blurry weak echoes into sharp correlation peaks, which facilitates the subsequent extraction of echo arrival times.

[0086] For example, such as Figure 8 The image shown is a schematic diagram of pulse compression processing. Figure 8 The image above shows the third echo signal received after preprocessing. The third echo signal has a wide pulse and is submerged in noise. Figure 8 The image below shows the pulse compression output signal after pulse compression processing. The wide pulse is compressed into a sharp correlation peak, which greatly improves its peak signal-to-noise ratio.

[0087] Step S403: Determine the echo arrival time corresponding to each pulse compressed output signal based on the position of the relevant peak in each pulse compressed output signal.

[0088] Specifically, step S403 includes:

[0089] Step S4031: Perform peak detection on each pulse compression output signal to obtain the relevant peak position of each pulse compression output signal.

[0090] The correlation peak position refers to the peak position of the correlation peak. A peak detection algorithm is used to identify the peak position of the correlation peak in each pulse compressed output signal. The correlation peak refers to the sharp, high-amplitude peak pulse formed at the output end of the received signal after the echo signal reflected by the target (in this case, the pipe defect) is processed by the matched filter.

[0091] For example, the derivative is calculated at each peak of the pulse compression output signal. When the derivative is 0, it indicates that the rate of change has changed from positive to negative, and the position of the relevant peak is obtained.

[0092] Step S4032: The time corresponding to the position of the relevant peak is used as the echo arrival time corresponding to each pulse compression output signal.

[0093] In some alternative implementations, the defect detection method for drainage pipes further includes: extracting the first... The arrival time of the echoes corresponding to each sensor element is calculated, and the time difference between each echo arrival time and the preset time difference of the reference sensor element (usually the middle element of the infrasound signal receiver array, such as the 4th sensor element in an infrasound signal receiver array containing 8 sensor elements) is calculated. This preset time difference reflects the spatial distance difference between the defect echoes and different sensor elements.

[0094] In some optional implementations, the pulse compression output signal is time-aligned according to a preset time difference. Specifically, the first... The pulse compression output signal of each sensor array element is shifted along the time axis by a preset time difference, so that the defect echo correlation peaks of all pulse compression output signals are precisely aligned (i.e., the echo of the same defect is at the same position on the time axis of each channel).

[0095] In some optional implementations, the time-aligned pulse compression output signals are weighted and summed, where the weighting coefficients are dynamically adjusted according to the array element signal-to-noise ratio. The resulting superimposed total signal can be expressed as:

[0096] ;

[0097] in, For the total signal, For the first The weighting coefficients corresponding to the pulse compressed output signal For the first A pulse compression output signal that has undergone time alignment processing.

[0098] For example, such as Figure 9The diagram shows a multi-channel signal superposition and enhancement process. The pulse-compressed output signal, after pulse compression processing, undergoes further beamforming enhancement based on the direction of arrival (DOA). Figure 9 As shown in the figure, the upper figure shows that the pulse compression output signal is not aligned on the time axis, and the lower figure shows that the pulse compression output signal is time aligned according to the estimated preset time difference, so that the echo signals from the same defect completely overlap in time. Then, the weighted superposition is performed, and finally it is determined that a sharp correlation peak with a very high signal-to-noise ratio appears at 0.5s on the time axis, which may be caused by a strong scattering source (i.e., defect). This indicates that the total propagation time of the sound wave from the transmitter, reflected by the scattering source, and reaching the center of the receiving array is about 0.5s.

[0099] In this embodiment of the invention, a total signal can be obtained by superimposing multiple signals. The total propagation time is determined based on the total signal. The subsequent echo arrival time is then verified based on the total propagation time to ensure the accuracy of the echo arrival time and prevent significant deviations.

[0100] Step S404: Based on the echo arrival time corresponding to each pulse compression output signal, the position information of the infrasound signal transmitter, the position information of each sensor element in the infrasound signal receiver array, and the preset sound velocity, determine the location of the defect in the target drainage pipe. For details, please refer to [link to relevant documentation]. Figure 2 Step S204 of the illustrated embodiment will not be described again here.

[0101] The defect detection method for drainage pipes provided in this embodiment filters each initial echo signal to obtain multiple first echo signals. This filters out interference signals such as environmental noise and pipe-irrelevant vibrations from the initial echo signals, retaining effective signals related to infrasound propagation and improving the signal purity for subsequent processing. This embodiment performs amplitude consistency processing on each first echo signal to obtain multiple second echo signals, eliminating amplitude fluctuations caused by hardware differences and signal propagation path differences between different sensor array elements. This makes the echo signals from each channel more uniform in amplitude dimension, avoiding interference from amplitude differences in subsequent feature recognition. This embodiment performs baseline correction processing on each second echo signal to obtain multiple third echo signals, correcting baseline drift and making the signal reference more stable. This embodiment determines the impulse response signal based on the time mirror of the infrasound signal. Each third echo signal is convolved with the impulse response signal to obtain multiple pulse compression output signals. This further compresses the signal width, improves the signal's temporal resolution, enhances the correlation peak characteristics of the signal, makes the identification of subsequent echo arrival times more accurate, and improves the signal-to-noise ratio.

[0102] This embodiment provides a method for detecting defects in drainage pipes, which can be used with computer equipment. Figure 10This is a third flowchart of a defect detection method for drainage pipes according to an embodiment of the present invention, as follows: Figure 10 As shown, the process includes the following steps:

[0103] Step S1001: Control the infrasound signal transmitter to transmit infrasound signals towards the target drainage pipe, and collect multiple initial echo signals from the infrasound signal receiver array; the initial echo signals are the echo signals generated by the infrasound signal propagating in the target drainage pipe. For details, please refer to... Figure 4 Step S401 of the illustrated embodiment will not be described again here.

[0104] Step S1002 involves pulse compression processing on each initial echo signal to obtain multiple pulse-compressed output signals. For details, please refer to [link to relevant documentation]. Figure 4 Step S402 of the illustrated embodiment will not be described again here.

[0105] Step S1003: Determine the echo arrival time corresponding to each pulse compressed output signal based on the position of the relevant peak in each pulse compressed output signal. For details, please refer to [link to relevant documentation]. Figure 4 Step S403 of the illustrated embodiment will not be described again here.

[0106] Step S1004: Determine the location of the defect in the target drainage pipe based on the echo arrival time corresponding to each pulse compression output signal, the position information of the infrasound signal transmitter, the position information of each sensor element in the infrasound signal receiver array, and the preset sound velocity.

[0107] Specifically, step S1004 includes:

[0108] Step S10041: Using the location of the defect in the target drainage pipe as a variable, construct multiple time-path relationships based on the echo arrival time corresponding to each pulse compression output signal, the location information of the infrasound signal transmitter, the location information of each sensor element in the infrasound signal receiver array, and the preset sound velocity.

[0109] The preset sound velocity can be set according to actual conditions. For air medium (when there is no water in the pipe or the water level is very low), the sound velocity in air is calculated based on the ideal gas law.

[0110] ;

[0111] in, The preset speed of sound in air. The temperature is in Celsius (°C).

[0112] Specifically, by measuring the air temperature inside the manhole or at the pipe inlet, the preset sound velocity can be obtained by substituting the temperature into the formula. For example, at 20℃, =331.4 + 0.6 * 20 = 343.4 m / s.

[0113] For a water medium (when the pipe is full or partially filled with water), the velocity of sound in water is calculated based on the formula:

[0114] ;

[0115] in, The preset sound velocity in the water medium, Water temperature For salinity, freshwater can be measured as 0. Due to the water depth, the impact is relatively small and can be ignored.

[0116] Specifically, water temperature is measured, and for urban drainage pipes (domestic sewage, rainwater), it is usually treated as freshwater. For example, in 15℃ freshwater, =1470m / s.

[0117] In some alternative implementations, the infrasound signal originates from an infrasound signal transmitter (coordinates (xt, yt, zt)) in the downstream inspection well, is scattered by a defect point (coordinate variables (xp, yp, zp)) within the pipeline, and then reaches the upstream receiving array. i There are three sensor array elements (coordinates (xi, yi, zi)). For each sensor array element, the echo arrival time and sound path satisfy the following relationship:

[0118] ;

[0119] in, For the first i The echo arrival time of the pulse compressed output signal The distance from the infrasound signal transmitter to the defect can be represented by the location of the defect in the target drainage pipe and the location of the infrasound signal transmitter. The distance from the defect to the sensor element can be represented by the location of the defect in the target drainage pipe and the position information of each sensor element in the infrasound signal receiver array. The preset sound velocity of the medium, The system launch initial time delay (can be calibrated and eliminated).

[0120] In some alternative implementations, based on the relationship between echo arrival time and sound path, multiple time-sound path relationships can be constructed according to the echo arrival time corresponding to each pulse compression output signal, the position information of the infrasound signal transmitter, the position information of each sensor element in the infrasound signal receiver array, and the preset sound velocity, thus obtaining a nonlinear equation set.

[0121] Step S10042: Obtain the preset time difference, take the preset time difference as a constraint, take the minimum error between the echo arrival time and the preset echo arrival time as the objective function, solve multiple time path relationships, and obtain the location of the defect in the target drainage pipe.

[0122] The expression for determining the location of the defect in the target drainage pipe is:

[0123] ;

[0124] in, The location of the defect in the target drainage pipe can be represented by its spatial coordinates. Let be the value of the variable that minimizes the objective function, i.e., the location of the defect in the target drainage pipe. For the first Measured echo arrival time of each sensor element For the first The preset echo arrival time of each sensor element That is, the first A time-range relationship. For the first The uncertainty or standard deviation of a time measurement. For sensor measurements with high signal-to-noise ratio and higher reliability ( The smaller the value, the larger the weight of the error term; for unreliable measurements ( The larger the value of a data point, the smaller its weight. This makes the algorithm more inclined to trust high-quality data.

[0125] In some optional implementations, step S10042 above includes:

[0126] Step a1: Select a reference sensor element in the infrasound signal receiver array, and obtain the preset time difference based on the difference between the echo arrival time corresponding to each pulse compression output signal and the echo arrival time of the reference sensor element.

[0127] In some alternative implementations, the echo arrival time of the pulse compression output signal is not entirely the time it takes for the sound wave to propagate within the pipe; it includes the actual propagation time of the sound wave within the pipe and the system's electronic delay. This includes the fixed time delays introduced by all hardware and software throughout the entire chain from signal generation, amplification, transmission, reception, acquisition to processing, which can modify the relationship between echo arrival time and sound path.

[0128] ;

[0129] in, For the first i The echo arrival time of the pulse compressed output signal The distance from the infrasound signal transmitter to the defect is [missing information]. The distance from the defect to the sensor array element. For electronic delay time, Given a preset sound velocity for the medium, for example, the pipe end is selected as a strong reflector at a known location, and the electron delay time is measured to be 0.343 s. Based on the type of medium in the pipe, the sound velocity is taken as 340 m / s, and we can obtain:

[0130] ;

[0131] The above result is greater than 50m of the straight length of the pipeline, indicating that the defect is not on the axis but has a certain offset, resulting in a longer sound path. Further, the calibrated, realistic constraints are substituted into the expression for determining the location of the defect in the target drainage pipeline, and a genetic algorithm is used for iterative solution to invert the three-dimensional spatial location of the defect. Here, the relative time delay difference of the sensor array elements is used as a constraint, and minimizing the error is the objective function. When the result converges, the unique and precise location of the defect is determined, which can be (30, 0.2, 0.8).

[0132] For example, such as Figure 11 The diagram shows the spatial location of the defect in the drainage pipe. The target drainage pipe has a diameter of 1.0m, a water depth of 0.2m, a burial depth of 6m, is made of concrete, and has a length of 50m. Taking the downstream inspection well as the origin, there is a top collapse with coordinates (30, 0.2, 0.8), which is 30m away from the downstream inspection well, 0.8m vertically upward, and 0.2m to the right of the center line.

[0133] The defect detection method for drainage pipes provided in this embodiment filters each initial echo signal to obtain multiple first echo signals. This filters out interference signals such as environmental noise and pipe-irrelevant vibrations from the initial echo signals, retaining effective signals related to infrasound propagation and improving the signal purity for subsequent processing. This embodiment performs amplitude consistency processing on each first echo signal to obtain multiple second echo signals, eliminating amplitude fluctuations caused by hardware differences and signal propagation path differences between different sensor array elements. This makes the echo signals from each channel more uniform in amplitude dimension, avoiding interference from amplitude differences in subsequent feature recognition. This embodiment performs baseline correction processing on each second echo signal to obtain multiple third echo signals, correcting baseline drift and making the signal reference more stable. This embodiment determines the impulse response signal based on the time mirror of the infrasound signal. Each third echo signal is convolved with the impulse response signal to obtain multiple pulse compression output signals. This further compresses the signal width, improves the signal's temporal resolution, enhances the correlation peak characteristics of the signal, makes the identification of subsequent echo arrival times more accurate, and improves the signal-to-noise ratio.

[0134] This embodiment also provides a defect detection device for drainage pipes, which is used to implement the above embodiments and preferred embodiments; details already described will not be repeated. As used below, the term "module" can refer to a combination of software and / or hardware that performs a predetermined function. Although the device described in the following embodiments is preferably implemented in software, hardware implementation, or a combination of software and hardware, is also possible and contemplated.

[0135] This embodiment provides a defect detection device for drainage pipes, such as... Figure 12 As shown, it includes:

[0136] The signal acquisition module 1201 is used to control the infrasound signal transmitter to transmit infrasound signals to the target drainage pipe and to acquire multiple initial echo signals from the infrasound signal receiver array; the initial echo signals are the echo signals generated by the infrasound signals as they are transmitted in the target drainage pipe.

[0137] The compression processing module 1202 is used to perform pulse compression processing on each initial echo signal to obtain multiple pulse compressed output signals.

[0138] The timing determination module 1203 is used to determine the echo arrival time corresponding to each pulse compressed output signal based on the position of the relevant peak in each pulse compressed output signal.

[0139] The defect location module 1204 is used to determine the location of the defect in the target drainage pipe based on the echo arrival time corresponding to each pulse compression output signal, the position information of the infrasound signal transmitter, the position information of each sensor element in the infrasound signal receiver array, and the preset sound velocity.

[0140] In some alternative implementations, the signal acquisition module 1201 includes:

[0141] The acoustic wave transmitting unit is used to control the infrasound signal transmitter to transmit coded infrasound signals into the air or water of the target drainage pipe; the infrasound signal transmitter is installed in the air or water at the inlet of the target drainage pipe through a downstream inspection well.

[0142] The echo acquisition unit is used to acquire the initial echo signal of each sensor element in the infrasound signal receiver array; the infrasound signal receiver array is installed in the air or water at the inlet of the target drainage pipe through an upstream inspection well.

[0143] In some alternative implementations, the compression processing module 1202 includes:

[0144] The preprocessing unit is used to filter each initial echo signal to obtain multiple first echo signals, perform amplitude consistency processing on each first echo signal to obtain multiple second echo signals, and perform baseline correction processing on each second echo signal to obtain multiple third echo signals.

[0145] The compression processing unit is used to determine the impulse response signal based on the time mirror of the infrasound signal, and to perform convolution processing on each third echo signal and the impulse response signal to obtain multiple pulse compressed output signals.

[0146] In some alternative implementations, the time determination module 1203 includes:

[0147] The peak detection unit is used to detect the peak value of each pulse compression output signal and obtain the relevant peak position of each pulse compression output signal.

[0148] The time determination unit is used to take the time corresponding to the position of the relevant peak as the echo arrival time corresponding to each pulse compression output signal.

[0149] In some alternative implementations, the defect location module 1204 includes:

[0150] The relation determination unit is used to construct multiple time-path relational expressions based on the location of the defect in the target drainage pipe, the echo arrival time corresponding to each pulse compression output signal, the location information of the infrasound signal transmitter, the location information of each sensor element in the infrasound signal receiver array, and the preset sound velocity, taking the location of the defect in the target drainage pipe as the variable.

[0151] The relational solving unit is used to obtain the preset time difference. With the preset time difference as a constraint and the objective function being to minimize the error between the echo arrival time and the preset echo arrival time, it solves multiple time-path relations to obtain the location of the defect in the target drainage pipe.

[0152] In some alternative implementations, the relational solving unit includes:

[0153] The time difference determination subunit is used to select a reference sensor element in the infrasound signal receiver array and obtain a preset time difference based on the difference between the echo arrival time corresponding to each pulse compression output signal and the echo arrival time of the reference sensor element.

[0154] The defect detection device for drainage pipes provided in this embodiment of the invention can execute the defect detection method for drainage pipes provided in any embodiment of the invention, and has the corresponding functional modules and beneficial effects for executing the method. Further functional descriptions of the above modules and units are the same as those in the corresponding embodiments described above, and will not be repeated here.

[0155] Figure 13This is a schematic diagram of the structure of an electronic device provided in an embodiment of the present invention.

[0156] The following is a detailed reference. Figure 13 This diagram illustrates a suitable structural schematic for implementing an electronic device according to embodiments of the present invention. The electronic device may include a processor (e.g., a central processing unit, graphics processor, etc.) 1301, which can perform various appropriate actions and processes according to a program stored in read-only memory (ROM) 1302 or a program loaded from memory 1308 into random access memory (RAM) 1303. The RAM 1303 also stores various programs and data required for the operation of the electronic device. The processor 1301, ROM 1302, and RAM 1303 are interconnected via a bus 1304. An input / output (I / O) interface 1305 is also connected to the bus 1304.

[0157] Typically, the following devices can be connected to I / O interface 1305: input devices 1306 including, for example, touchscreens, touchpads, keyboards, mice, cameras, microphones, accelerometers, gyroscopes, etc.; output devices 1307 including, for example, liquid crystal displays (LCDs), speakers, vibrators, etc.; memory devices 1308 including, for example, magnetic tapes, hard disks, etc.; and communication devices 1309. Communication device 1309 allows electronic devices to communicate wirelessly or wiredly with other devices to exchange data. Although Figure 13 Electronic devices with various devices are shown, but it should be understood that it is not required to implement or have all of the devices shown, and more or fewer devices may be implemented or have instead.

[0158] In particular, according to embodiments of the present invention, the processes described above with reference to the flowcharts can be implemented as computer software programs. For example, embodiments of the present invention include a computer program product comprising a computer program carried on a non-transitory computer-readable medium, the computer program containing program code for performing the methods shown in the flowcharts. In such embodiments, the computer program can be downloaded and installed from a network via a communication device 1309, or installed from a memory 1308, or installed from a ROM 1302. When the computer program is executed by the processor 1301, it performs the functions defined in the defect detection method for drainage pipes according to embodiments of the present invention.

[0159] Figure 13 The electronic device shown is merely an example and should not be construed as limiting the functionality and scope of the embodiments of the present invention.

[0160] 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. When the software or computer code is accessed and executed by the computer, processor, or hardware, the defect detection method for drainage pipes shown in the above embodiments is implemented.

[0161] 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.

[0162] 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 method for detecting defects in drainage pipes, characterized in that, The method includes: The system controls an infrasound signal transmitter to transmit infrasound signals toward a target drainage pipe and collects multiple initial echo signals from an infrasound signal receiver array; the initial echo signals are the echo signals generated by the infrasound signals as they travel through the target drainage pipe. Each initial echo signal is subjected to pulse compression processing to obtain multiple pulse compressed output signals; The echo arrival time corresponding to each pulse compression output signal is determined based on the position of the relevant peak in each pulse compression output signal. The location of the defect in the target drainage pipe is determined based on the echo arrival time corresponding to each pulse compression output signal, the position information of the infrasound signal transmitter, the position information of each sensor element in the infrasound signal receiver array, and the preset sound velocity. The step of determining the location of the defect in the target drainage pipe based on the echo arrival time corresponding to each pulse compression output signal, the position information of the infrasound signal transmitter, the position information of each sensor element in the infrasound signal receiver array, and a preset sound velocity includes: using the location of the defect in the target drainage pipe as a variable, constructing multiple time-path relationships based on the echo arrival time corresponding to each pulse compression output signal, the position information of the infrasound signal transmitter, the position information of each sensor element in the infrasound signal receiver array, and a preset sound velocity; obtaining a preset time difference, using the preset time difference as a constraint, and taking the minimization of the error between the echo arrival time and the preset echo arrival time as the objective function, solving the multiple time-path relationships to obtain the location of the defect in the target drainage pipe.

2. The method according to claim 1, characterized in that, The control unit transmits infrasound signals to the target drainage pipe, and the collected infrasound signal receiver array receives multiple initial echo signals, including: The infrasound signal transmitter is controlled to transmit the encoded infrasound signal into the air or water of the target drainage pipe; the infrasound signal transmitter is installed in the air or water at the inlet of the target drainage pipe through a downstream inspection well; The initial echo signal of each sensor element in the infrasound signal receiver array is acquired; the infrasound signal receiver array is installed in the air or water at the inlet of the target drainage pipe via an upstream inspection well.

3. The method according to claim 1 or 2, characterized in that, The step of performing pulse compression processing on each of the initial echo signals to obtain multiple pulse-compressed output signals includes: Each initial echo signal is filtered to obtain multiple first echo signals. Each first echo signal is then subjected to amplitude consistency processing to obtain multiple second echo signals. Each second echo signal is then subjected to baseline correction processing to obtain multiple third echo signals. Based on the time mirror of the infrasound signal, the impulse response signal is determined, and each of the third echo signals is convolved with the impulse response signal to obtain multiple pulse compression output signals.

4. The method according to claim 1 or 2, characterized in that, Determining the echo arrival time corresponding to each pulse compression output signal based on the position of the relevant peak in each pulse compression output signal includes: Peak detection is performed on each of the pulse compression output signals to obtain the relevant peak position of each pulse compression output signal; The time corresponding to the position of the relevant peak is taken as the echo arrival time corresponding to each pulse compression output signal.

5. The method according to claim 1, characterized in that, The process of obtaining the preset time difference includes: A reference sensor element is selected in the infrasound signal receiver array, and the preset time difference is obtained based on the difference between the echo arrival time corresponding to each pulse compression output signal and the echo arrival time of the reference sensor element.

6. A defect detection device for drainage pipes, characterized in that, The device includes: The signal acquisition module is used to control the infrasound signal transmitter to transmit infrasound signals to the target drainage pipe and to acquire multiple initial echo signals from the infrasound signal receiver array; the initial echo signals are the echo signals generated by the infrasound signals during transmission in the target drainage pipe. A compression processing module is used to perform pulse compression processing on each of the initial echo signals to obtain multiple pulse compressed output signals; The timing determination module is used to determine the echo arrival time corresponding to each pulse compression output signal based on the position of the relevant peak in each pulse compression output signal; The defect location module is used to determine the location of the defect in the target drainage pipe based on the echo arrival time corresponding to each pulse compression output signal, the position information of the infrasound signal transmitter, the position information of each sensor element in the infrasound signal receiver array, and a preset sound velocity. The defect location module includes: a relation determination unit, used to construct multiple time-path relational expressions based on the location of the defect in the target drainage pipe, the echo arrival time corresponding to each pulse compression output signal, the location information of the infrasound signal transmitter, the location information of each sensor element in the infrasound signal receiver array, and a preset sound velocity, using the location of the defect in the target drainage pipe as a variable; and a relation solving unit, used to obtain a preset time difference, and using the preset time difference as a constraint, and the objective function of minimizing the error between the echo arrival time and the preset echo arrival time, to solve the multiple time-path relational expressions to obtain the location of the defect in the target drainage pipe.

7. An electronic device, characterized in that, include: A memory and a processor are communicatively connected, the memory storing computer instructions, and the processor executing the computer instructions to perform the defect detection method for drainage pipes as described in any one of claims 1 to 5.

8. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores computer instructions for causing the computer to perform the defect detection method for the drainage pipe as described in any one of claims 1 to 5.

9. A computer program product, characterized in that, Includes computer instructions for causing a computer to perform the defect detection method for drainage pipes as described in any one of claims 1 to 5.

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