Road surface subsidence disease monitoring method, system and device

Abstract

The invention relates to the technical field of material analysis, in particular to a pavement subsidence disease monitoring method, system and device, and the method comprises the steps: dividing the frequency band of an ultrasonic echo signal of a pavement target region in a frequency domain into a plurality of sub-segments, and analyzing the frequency spectrum morphological characteristics of the echo signal based on the energy distribution condition in the sub-segments, thereby obtaining a pavement subsidence disease monitoring result. Determining the cavity subsidence scatterability of the road surface target area; based on the fluctuation change of the ultrasonic echo signal, analyzing the effective and continuous condition of the signal, and determining the time domain dispersivity of the road surface target area; and based on the cavity subsidence scatterability and the time domain dispersivity, determining a cavity subsidence discrimination factor of the road surface target area, and further determining whether subsidence diseases exist in the road surface target area. According to the method, the frequency spectrum form and the time domain continuity are integrated to identify whether the subsidence disease exists in the road surface target area, the specificity of subsidence disease identification is remarkably improved, and the false alarm rate caused by composite disease confusion is greatly reduced.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of material analysis, in particular to a method, system and device for monitoring road surface subsidence disease. BACKGROUND

[0002] Road surface subsidence is a common form of road structural disease, which not only affects driving comfort and safety, but also may indicate serious safety hazards such as cavities and voids in the roadbed or base. In order to achieve early warning and accurate evaluation of road surface subsidence, non-destructive testing technology has been widely used. Among them, the ultrasonic detection method has become a very potential technical means due to its sensitivity and penetration ability to internal defects. As an effective non-destructive testing method, ultrasonic detection technology can evaluate the internal structure of the road surface by emitting ultrasonic pulses into the road surface and receiving the echo signals. For example, by analyzing the characteristics of the echo signal such as the time of flight and amplitude attenuation, the existence and location of internal defects can be inferred.

[0003] Most of the existing methods for monitoring road surface disease using ultrasonic waves rely on analyzing a single echo feature, such as detecting abnormal echo peaks to determine the presence of defects. However, in actual road environments, precursors of subsidence such as roadbed cavities often coexist with other types of diseases such as cracks, interlayer peeling, and water damage areas. The responses of these complex diseases to ultrasonic signals are similar and superimposed, forming confusing signals. For example, a sharp crack and a small-sized cavity can both produce an identifiable echo, and traditional amplitude or time delay analysis methods cannot effectively distinguish their types, leading to misjudgment of cracks or interlayer peeling as precursors of subsidence, thereby seriously affecting the accuracy of monitoring. SUMMARY

[0004] To solve the above technical problems, the purpose of the present application is to provide a method, system and device for monitoring road surface subsidence disease, and the technical solution is as follows: In a first aspect, the present application provides a method for monitoring road surface subsidence disease, comprising the following steps: Collecting ultrasonic echo signals of a target area of the road surface; Dividing the frequency band of the ultrasonic echo signals in the frequency domain into several sub-segments, analyzing the spectral pattern features of the echo signals based on the energy distribution in the sub-segments, and determining the cavity subsidence scattering property of the target area of the road surface; Based on the wave variation of the ultrasonic echo signals, analyzing the signal effective duration, and determining the time domain dispersion of the target area of the road surface; Based on the cavity subsidence scattering property and the time domain dispersion, determining the cavity subsidence discriminant factor of the target area of the road surface; Determine whether the target region of the road surface has a settlement disease based on the cavity settlement discriminant factor.

[0005] In some possible implementation manners, based on the energy distribution in the sub-segment, the frequency spectrum feature of the echo signal is analyzed, and the cavity settlement scattering property of the target region of the road surface is determined, including: Obtain a plurality of decomposition coefficients corresponding to each sub-segment when a frequency band of the ultrasonic echo signal in the frequency domain is divided into a plurality of sub-segments; Determine an energy feature value of each sub-segment based on the plurality of decomposition coefficients; Determine a frequency spectrum energy offset factor of the target region of the road surface based on the energy feature values and the center frequencies of all sub-segments; Determine the cavity settlement scattering property of the target region of the road surface based on the difference between the center frequencies of all sub-segments and the frequency spectrum energy offset factor, and in combination with the energy feature values of all sub-segments.

[0006] In some possible implementation manners, the frequency spectrum energy offset factor of the target region of the road surface is determined, including: Determine an accumulated value of products of the energy feature values and the center frequencies of all sub-segments to obtain a first accumulated value; Determine an accumulated value of the energy feature values of all sub-segments to obtain a second accumulated value; Determine a ratio of the first accumulated value to the second accumulated value to obtain the frequency spectrum energy offset factor of the target region of the road surface.

[0007] In some possible implementation manners, the cavity settlement scattering property of the target region of the road surface is determined, including: Determine a difference between the center frequencies of each sub-segment and the frequency spectrum energy offset factor to determine a frequency difference value; Determine an accumulated value of products of the energy feature values of all sub-segments and the frequency difference value to obtain a third accumulated value; Determine the cavity settlement scattering property of the target region of the road surface based on a ratio of the third accumulated value to the second accumulated value.

[0008] In some possible implementation manners, the signal effective duration is analyzed, and the time-domain dispersion property of the target region of the road surface is determined, including: Determine an effective duration of the ultrasonic echo signal based on a change of the envelope line of the ultrasonic echo signal; Determine the time-domain dispersion property of the target region of the road surface based on a difference between the effective duration and a reference effective duration corresponding to a healthy road surface region.

[0009] With the first aspect above, in some possible implementation manners, the effective duration of the ultrasonic echo signal is determined in the following manner: a peak value of the envelope is determined based on the change of the envelope, and an energy threshold is determined based on the peak value; a starting time point is determined by searching backward from a time starting point, at which the signal value on the envelope rises from below the energy threshold to equal to or higher than the energy threshold for the first time; a terminal time point is determined by searching forward from a time terminal point, at which the signal value on the envelope rises from below the energy threshold to equal to or higher than the energy threshold for the first time; a duration between the starting time point and the terminal time point is taken as the effective duration of the ultrasonic echo signal.

[0010] With the first aspect above, in some possible implementation manners, before the frequency band of the ultrasonic echo signal in the frequency domain is divided into a plurality of subsegments, the ultrasonic echo signal is preprocessed, and the preprocessing process includes: the ultrasonic echo signal is subjected to band-pass filtering to obtain a filtered ultrasonic echo signal; the filtered ultrasonic echo signal is subjected to baseline correction to obtain a preprocessed ultrasonic echo signal.

[0011] With the first aspect above, in some possible implementation manners, the frequency band of the ultrasonic echo signal in the frequency domain is divided into a plurality of subsegments in the following manner: the frequency band of the ultrasonic echo signal in the frequency domain is divided into a plurality of equal-width subbands by using wavelet packet transform, and a plurality of decomposition coefficients corresponding to each subsegment in the frequency band division process are obtained.

[0012] In a second aspect, the present application further provides a device for monitoring road surface subsidence diseases, and the device includes: an ultrasonic signal acquisition module configured to collect ultrasonic echo signals of a target region of a road surface; a scattering analysis module configured to divide a frequency band of the ultrasonic echo signals in the frequency domain into a plurality of subsegments, analyze frequency spectrum morphological features of the echo signals based on energy distribution in the subsegments, and determine a cavity subsidence scattering property of the target region of the road surface; a dispersion analysis module configured to analyze signal effective duration based on fluctuation changes of the ultrasonic echo signals, and determine a time-domain dispersion of the target region of the road surface; a discriminant factor determination module configured to determine a cavity subsidence discriminant factor of the target region of the road surface based on the cavity subsidence scattering property and the time-domain dispersion; The subsidence defect identification module is used to determine whether subsidence defects exist in the target area of ​​the road surface based on the cavity subsidence discrimination factor.

[0013] Thirdly, the present invention also provides a monitoring system for road subsidence defects, including a memory and a processor. The memory is used to store executable computer program code, and the processor is used to call and run the executable computer program code from the memory, causing the system to perform a road subsidence defect monitoring method according to the first aspect or any possible implementation thereof.

[0014] Fourthly, the present invention also provides a computer program product comprising: computer program code, which, when run on a computer, causes the computer to execute a method for monitoring road subsidence defects as described in the first aspect or any possible implementation thereof.

[0015] Fifthly, the present invention also provides a computer-readable storage medium storing computer program code, which, when executed on a computer, causes the computer to perform a method for monitoring road subsidence defects as described in the first aspect or any possible implementation thereof.

[0016] This invention has the following beneficial effects: On the one hand, by dividing the frequency band of the ultrasonic echo signal of the target area of ​​the road surface into several sub-segments in the frequency domain, and analyzing the spectral morphology characteristics of the echo signal based on the energy distribution in the sub-segments, the scattering property of the cavity and subsidence in the target area of ​​the road surface is determined. On the other hand, based on the fluctuation changes of the ultrasonic echo signal, the effective duration of the signal is analyzed to determine the temporal dispersion of the target area of ​​the road surface. Thus, based on the scattering property of the cavity and subsidence in the target area of ​​the road surface and the temporal dispersion, a cavity and subsidence discrimination factor is determined, and based on this discrimination factor, the presence of subsidence defects in the target area of ​​the road surface is determined. This invention obtains a cavity and subsidence discrimination factor by comprehensively considering the spectral morphology and temporal persistence of the ultrasonic echo signal of the target area of ​​the road surface. This discrimination factor can effectively distinguish between complex scattering signals caused by cavity-like body defects and specular reflection signals caused by crack-like planar defects, significantly improving the specificity of subsidence defect identification and greatly reducing the false alarm rate caused by confusion due to complex defects. Attached Figure Description

[0017] To more clearly illustrate the technical solutions and advantages in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 A step flow chart of a road surface subsidence disease monitoring method according to an embodiment of the present application; Figure 2 A structural schematic diagram of a road surface subsidence disease monitoring device according to an embodiment of the present application; Figure 3 A structural schematic diagram of a road surface subsidence disease monitoring system according to an embodiment of the present application. DETAILED DESCRIPTION

[0019] To make the technical features of the present application clear, the present application will be described in detail below with reference to the specific embodiments and in conjunction with the drawings.

[0020] Embodiments of the present application will be described in more detail below with reference to the accompanying drawings. While certain embodiments of the present application are shown in the drawings, it is understood that the present application can be embodied in various forms and should not be construed as being limited to the embodiments set forth herein; rather, these embodiments are provided so that the present application can be more thoroughly and completely understood. It should be understood that the drawings and embodiments of the present application are only for illustrative purposes and should not be construed as limiting the scope of the present application.

[0021] It should be understood that each of the steps recited in the method embodiments of the present application can be performed in different orders and / or in parallel. In addition, the method embodiments can include additional steps and / or omit the performance of the steps shown. The scope of the present application is not limited in this respect.

[0022] The term "comprising" and variations thereof as used herein are used inclusively, i.e., "comprising but not limited to." The term "based on" is "based at least in part on." The term "one embodiment" means "at least one embodiment." The term "another embodiment" means "at least one additional embodiment." The term "some embodiments" means "at least some embodiments." Related definitions will be given in the description below.

[0023] It should be noted that the terms "first", "second", and so on used in the present application are only used to distinguish different devices, modules or units, and are not intended to limit the order or interdependence of the functions performed by these devices, modules or units.

[0024] In the embodiments of the present application, although the operations or steps are described in a specific order in the accompanying drawings, it should not be construed that the operations or steps must be performed in the specific order or in a serial order, or that all of the shown operations or steps must be performed to obtain a desired result. In the embodiments of the present application, the operations or steps can be performed in series; the operations or steps can be performed in parallel; or a part of the operations or steps can be performed.

[0025] Meanwhile, it can be understood that the data (including but not limited to the data itself, acquisition or use of the data) involved in the technical solutions of the present application should comply with the requirements of the corresponding laws, regulations and relevant provisions. Unless otherwise defined, all technical and scientific terms used in the present application have the same meanings as those commonly understood by the person skilled in the art to which the present application belongs, and all parameters or indexes in the formulas involved in the present application are the values after normalization, which eliminate the influence of dimension.

[0026] The road surface subsidence disease monitoring method, system and device provided by the embodiments of the present application will be described in detail below with reference to the accompanying drawings.

[0027] Figure 1 The basic flowchart of the road surface subsidence disease monitoring method provided by the embodiments of the present application is shown in FIG. 1, which specifically includes the following steps: Figure 1 Step S100: Collecting an ultrasonic echo signal of a target area of a road surface.

[0028] The target area of the road surface is scanned by using an ultrasonic probe to obtain a series of one-dimensional ultrasonic echo signals changing with time, which are denoted as original signals In the embodiments of the present application, in order to facilitate subsequent identification of the ultrasonic echo signals, thereby accurately identifying the subsidence disease of the target area of the road surface, the original signals are preprocessed, that is, the original signals are band-pass filtered to filter out noise in a frequency band irrelevant to detection, to obtain filtered ultrasonic echo signals; and the filtered ultrasonic echo signals are baseline corrected to eliminate direct current bias or low-frequency drift of the signals, thereby obtaining final ultrasonic echo signals after preprocessing . Since the process of preprocessing the original signals belongs to the prior art, it will not be described here.

[0029] Step S200: Dividing a frequency band of the ultrasonic echo signal in a frequency domain into a plurality of sub-sections, analyzing spectral morphological features of the echo signal based on energy distribution in the sub-sections, and determining cavity subsidence scattering of the target area of the road surface.

[0030] ​Due to the difference in geometry and physical properties, different types of pavement defects show different frequency characteristics in response to incident ultrasonic waves. For example, planar defects such as cracks or interlayer peeling tend to produce broadband, transient specular reflection, while volumetric, irregular defects such as cavity precursors cause more complex scattering phenomena, with energy mainly distributed in specific low-frequency bands, resulting in left shift of the echo signal spectrum morphology. Therefore, the signal is finely divided in the full frequency band, and based on the energy distribution in the divided sub-band, the subtle frequency response difference is captured, the spectral morphology characteristics of the echo signal are analyzed, and finally the cavity subsidence scattering property of the target area of the pavement is determined to distinguish different types of pavement defects.

[0031] Compared with the traditional wavelet transform, the wavelet packet transform (WPT) can more finely analyze the details of high-frequency signals and is suitable for complex signal processing such as ultrasonic echo. Therefore, in the embodiments of the present application, the wavelet packet transform algorithm is used to divide the preprocessed ultrasonic echo signal into several sub-bands in the frequency domain. The wavelet packet variation of the layer is obtained, and the frequency band of the ultrasonic echo signal is divided into equal-width sub-bands. For each sub-band, also called frequency band node, a plurality of decomposition coefficients corresponding thereto are obtained.

[0032] Further, the energy distribution in each sub-band obtained by dividing the ultrasonic echo signal is analyzed, such as analyzing the frequency components in which the energy of the signal is mainly concentrated, and the spectral morphology characteristics of the echo signal are analyzed, so as to determine the cavity subsidence scattering property of the target area of the pavement, thereby providing a strong basis for subsequent feature analysis and pattern recognition (such as identifying subsidence diseases).

[0033] In the embodiments of the present application, the step S200 of analyzing the spectral morphology characteristics of the echo signal based on the energy distribution in the sub-band, and determining the cavity subsidence scattering property of the target area of the pavement, comprises: Step S201: obtaining a plurality of decomposition coefficients corresponding to each sub-band when the frequency band of the ultrasonic echo signal in the frequency domain is divided into a plurality of sub-bands.

[0034] In the embodiments of the present application, the wavelet packet transform algorithm is used to divide the preprocessed ultrasonic echo signal into several sub-bands in the frequency domain, and a plurality of decomposition coefficients corresponding to each sub-band are obtained. The decomposition coefficient represents the intensity of the energy event of the frequency in the frequency band range corresponding to the corresponding sub-band.

[0035] Step S202: determining an energy characteristic value of each sub-segment based on the plurality of decomposition coefficients.

[0036] In the embodiment of the present application, for any i-th sub-segment, an energy characteristic value of the i-th sub-segment is calculated based on the decomposition coefficients. wherein, n i represents a number of all the decomposition coefficients corresponding to the i-th sub-segment;

[0037] Step S203: determining a spectral energy shift factor of the target region of the road surface based on the energy characteristic values and the center frequencies of all the sub-segments.

[0038] Considering the echo generated by a flat interface (such as a healthy interlayer interface or an ideal horizontal crack front), the spectral pattern thereof should be similar to that of the incident wave and exhibit good symmetry. However, the echo generated by a cavity sink scattering will cause significant spectral distortion due to multiple scattering and transmission inside the cavity, especially energy shift to the low frequency region, thereby causing the spectral pattern to exhibit obvious asymmetry.

[0039] Therefore, in the embodiment of the present application, the center frequency of each sub-segment is obtained according to the sampling rate of the ultrasonic wave and the decomposition layer number of the WPT algorithm. Since the specific process of obtaining the center frequency of each sub-segment belongs to the prior art, it will not be described here.

[0040] Considering that when the ultrasonic wave passes through the sink precursor region (such as a cavity or a loose area), these irregular and air-filled regions are "high attenuation" and "strong scattering" media for the ultrasonic wave, and therefore the attenuation speed of the high-frequency component is much faster than that of the low-frequency component when the ultrasonic wave propagates in these media. Therefore, the energy of the high-frequency part of the echo signal passing through these regions will be severely lost, while the energy of the low-frequency part will be relatively retained more. The "center of gravity" of the entire spectrum will inevitably move to the low frequency end. Therefore, the spectral energy shift factor of the target region of the road surface is determined based on the energy characteristic values and the center frequencies of all the sub-segments.

[0041] In the embodiment of the present application, the spectral energy shift factor of the target region of the road surface determined in step S203 comprises: First, the accumulated value of the product of the energy characteristic values and the center frequencies of all the sub-segments is determined to obtain a first accumulated value.

[0042] Secondly, the accumulated value of the energy characteristic values of all the sub-segments is determined to obtain a second accumulated value.

[0043] ​​​​​​​Finally, the ratio of the first accumulated value to the second accumulated value is determined to obtain the spectral energy shift factor of the target area of ​​the road surface.

[0044] The expression for calculating the spectral energy shift factor of the target area of ​​the road surface is as follows: In the formula: This represents the spectral energy shift factor of the target area on the road surface. Indicates the first The center frequency of each sub-segment; This indicates the number of all segments of the ultrasonic echo signal in the target area of ​​the road surface. Indicates the first Energy characteristic values ​​of each sub-segment.

[0045] Step S204: Based on the difference between the center frequency of all sub-segments and the spectral energy offset factor, and in combination with the energy characteristic values ​​of all sub-segments, determine the cavitation and subsidence scattering properties of the target area of ​​the road surface.

[0046] The greater the leftward skewness of the spectral energy distribution in the target area of ​​the road surface, the more likely the target area traversed by the ultrasonic waves is to be a pre-subsidence region. Therefore, based on the differences between the center frequencies and spectral energy shift factors of all sub-segments, and combined with the energy characteristic values ​​of all sub-segments, the degree of leftward skewness of the spectral energy distribution is analyzed to determine the scattering properties of the cavity subsidence in the target area of ​​the road surface.

[0047] In this embodiment of the invention, step S204, determining the scattering properties of the cavity subsidence in the target area of ​​the road surface, includes: First, determine the difference between the center frequency of each sub-segment and the spectral energy offset factor, and determine the frequency difference value.

[0048] Secondly, the cumulative value of the product of the energy characteristic values ​​of all sub-segments and the frequency difference values ​​is determined to obtain the third cumulative value.

[0049] Finally, based on the ratio of the third accumulated value to the second accumulated value, the scattering property of the cavity subsidence in the target area of ​​the road surface is determined.

[0050] The calculation expression for determining the scattering property of void subsidence in the target area of ​​the road surface is as follows: In the formula: This indicates the scattering properties of void subsidence in the target area of ​​the road surface; This represents the spectral energy shift factor of the target area on the road surface. Indicates the first The center frequency of each sub-segment; This indicates the number of all segments of the ultrasonic echo signal in the target area of ​​the road surface. Indicates the first Energy characteristic values ​​of each sub-segment; This represents an exponential function with the natural constant e as the base. Where, when the center frequency of each segment... The smaller the difference between the frequency difference and the frequency energy offset factor, the more severe the distortion and asymmetry of the frequency energy distribution of the ultrasonic echo signal in the target area of ​​the road surface. This corresponds to the scattering physical phenomenon of cavity subsidence, and the larger the value of the scattering property of cavity subsidence.

[0051] Step S300: Based on the fluctuation changes of the ultrasonic echo signal, analyze the effective duration of the signal and determine the temporal dispersion of the target area on the road surface.

[0052] Identifying subsidence defects solely based on the spectral energy distribution of ultrasonic echo signals from the target area of ​​the road surface can still lead to defect confusion. Furthermore, it's important to consider that, in addition to spectral characteristics, different defects also exhibit differences in their echo patterns in the temporal domain. For example, the echoes from planar cracks are short-duration and sharp; while the scattered echoes from cavities, due to their complex internal paths, have more dispersed energy over time, resulting in echo tailing and prolonged duration. Therefore, analyzing the effective duration of the ultrasonic echo signal based on its inherent fluctuations and determining the temporal dispersion of the target area of ​​the road surface, and combining the leftward skewness of the spectral energy distribution with its temporal dispersion, can significantly improve the specificity of identifying cavities in the target road surface area.

[0053] In this embodiment of the invention, step S300, which analyzes the effective duration of the signal and determines the temporal dispersion of the target area of ​​the road surface, includes: Step S301: Determine the effective duration of the ultrasonic echo signal based on the changes in the envelope of the ultrasonic echo signal.

[0054] Due to the ultrasonic echo signal in the target area of ​​the road surface The ultrasonic echo signal is a high-frequency oscillating waveform with both positive and negative amplitudes, making direct energy analysis difficult. Therefore, its amplitude profile is extracted to obtain the envelope of the ultrasonic echo signal. In this embodiment of the invention, the Hilbert transform algorithm is used to obtain the ultrasonic echo signal of the target area on the road surface. envelope The envelope Ultrasonic echo signals capable of accurately depicting target areas on the road surface Distribution profile on the time axis.

[0055] Further, based on the change of the envelope of the ultrasonic echo signal, a valid duration of the ultrasonic echo signal is determined. The valid duration reflects the duration of the main part of the ultrasonic echo signal.

[0056] In the embodiment of the present application, the valid duration of the ultrasonic echo signal is determined in step S301, comprising: First, based on the change of the envelope, the peak value of the envelope is determined, and based on the peak value, an energy threshold is determined. Specifically, the peak value (maximum peak value) of the envelope of the ultrasonic echo signal is obtained, and an empirical parameter is preset . The product of the empirical parameter and the peak value of the envelope is taken as the energy threshold . By determining the energy threshold in this way, for strong echoes, the energy threshold can be correspondingly increased; for weak echoes, the energy threshold will be correspondingly reduced, ensuring that the main part of the signal can always be intercepted.

[0057] Secondly, the time point at which the signal value on the envelope rises from below the energy threshold to equal to or higher than the energy threshold for the first time is determined as the starting time point. Specifically, starting from the time starting point, the time point at which the value of the envelope rises from below the energy threshold to equal to or higher than the energy threshold for the first time is found, the time point is taken as the starting time point, and is recorded as . .

[0058] Then, the time point at which the signal value on the envelope rises from below the energy threshold to equal to or higher than the energy threshold for the first time is determined as the ending time point. Specifically, the time point at which the value of the envelope rises from below the energy threshold to equal to or higher than the energy threshold for the first time is found by searching backward from the time ending point, the time point is taken as the ending time point, and is recorded as . .

[0059] Finally, the duration between the starting time point and the ending time point is taken as the valid duration of the ultrasonic echo signal. Specifically, based on the starting time point and the ending time point , the valid duration of the ultrasonic echo signal is determined.

[0060] ​​​​Step S302: Based on the difference between the effective duration and the reference effective duration corresponding to the healthy road surface area, determine the temporal dispersion of the target road surface area.

[0061] In this embodiment of the invention, following the same method as described above for obtaining the effective duration of the target road surface area, the effective duration of ultrasonic echo signals from multiple healthy road surface areas is pre-acquired. The average of the acquired multiple effective durations is calculated to obtain the mean effective duration. This mean effective duration is used as the reference effective duration corresponding to the healthy road surface area. This reference effective duration represents the reference duration of ideal specular reflection. .

[0062] Furthermore, based on the effective duration of the ultrasonic echo signal Reference effective duration The difference between them is obtained by using the following formula to determine the temporal dispersion of the target area of ​​the road surface: In the formula: This indicates the temporal dispersion of the target area on the road surface; This represents an exponential function with base e. Where, when Close to or less than When the exponent term is greater than or close to 1, A value less than or close to zero indicates that the echo signal may be an ultrasonic echo signal from a healthy road surface area; only when... Significantly greater than If the tailing of the echo signal is severe, it indicates that the echo signal may be a scattering echo from a hole.

[0063] Step S400: Based on the cavity subsidence scattering and the time-domain dispersion, determine the cavity subsidence discrimination factor for the target area of ​​the road surface.

[0064] Combining the leftward skewness of the spectral energy distribution of the target pavement area with its temporal dispersion can greatly improve the specificity of identifying cavities in the target pavement area. Therefore, by integrating the scattering and temporal dispersion of cavities and subsidence, a cavities and subsidence discrimination factor for the target pavement area can be obtained.

[0065] In this embodiment of the invention, based on the scattering properties of void subsidence... and temporal diffusion Determine the discriminant factor for void subsidence in the target area of ​​the road surface. In the formula, This represents a linear normalization function used to normalize values ​​to the range [0,1]. The void subsidence discriminant factor is also included. The greater the value is, the more serious the left skewness of the echo signal and the echo tailing are, and the greater the possibility of the echo signal being a hollow scattering echo is; therefore, the double discrimination mechanism ensures that only the signal satisfying the spectral and time-domain scattering characteristics simultaneously is identified as being derived from a hollow settlement.

[0066] So far, the hollow settlement discrimination factor of the target road surface region can be obtained.

[0067] Step S500: determining whether the target road surface region has a settlement disease based on the hollow settlement discrimination factor.

[0068] A threshold parameter is preset If the hollow settlement discrimination factor of the target road surface region is greater than or equal to the threshold parameter , it is determined that the current target road surface region has a settlement disease, i.e., has a hollow or a structural incompactness, etc., as a precursor disease related to the settlement, otherwise, it is determined that the current target road surface region does not have a settlement disease.

[0069] The present application finely captures subtle differences in frequency response of different diseases through multi-resolution decomposition of the ultrasonic echo signal by wavelet packet transform, and realizes decoupling of the characteristics of the settlement disease from the complex mixed echo signal fundamentally in combination with the spectral left skewness and time-domain feature analysis, so that the disease diagnosis conclusion is more accurate and reliable, and the precise identification of the settlement precursor disease is realized.

[0070] Based on the same inventive concept, the present application also provides a road surface settlement disease monitoring device, as shown in Figure 2 The device comprises: An ultrasonic signal acquisition module for collecting an ultrasonic echo signal of a target road surface region; A scattering analysis module for dividing a frequency band of the ultrasonic echo signal in a frequency domain into a plurality of subsegments, analyzing spectral pattern characteristics of the echo signal based on energy distribution in the subsegments, and determining a hollow settlement scattering property of the target road surface region; A dispersivity analysis module for analyzing signal effective duration based on fluctuation variation of the ultrasonic echo signal, and determining a time-domain dispersivity of the target road surface region; A discrimination factor determination module for determining a hollow settlement discrimination factor of the target road surface region based on the hollow settlement scattering property and the time-domain dispersivity; A settlement disease identification module for determining whether the target road surface region has a settlement disease based on the hollow settlement discrimination factor.

[0071] It should be noted that the device provided in the above embodiment is only used for example to divide the above function modules, and in actual application, the above functions can be completed by different function modules according to needs, that is, the internal structure of the computer device is divided into different function modules to complete all or part of the above described functions.

[0072] Based on the same inventive concept, the embodiment of the present application also provides a road surface subsidence disease monitoring system, as shown in the figure, the system comprises a memory, a processor and computer program code stored in the memory and running on the processor, wherein the processor executes the computer program code, so that the system can execute any one of the above-mentioned road surface subsidence disease monitoring methods. Figure 3

[0073] The embodiment of the present application can divide the function modules of the system according to the above method examples, for example, each function module can be corresponding, or two or more functions can be integrated in one processing module, and the above integrated module can be realized in the form of hardware.

[0074] Based on the same inventive concept, the embodiment of the present application also provides a computer program product, which comprises computer program code, when the computer program code runs on the computer, so that the computer executes any one of the above-mentioned road surface subsidence disease monitoring methods.

[0075] Based on the same inventive concept, the embodiment of the present application also provides a computer readable storage medium, which stores computer program code, when the computer program code runs on the computer, so that the computer executes any one of the above-mentioned road surface subsidence disease monitoring methods.

[0076] It should be noted that the above described embodiments are only used to illustrate the technical solutions of the present application, but not to limit them; although the present application has been described in detail with reference to the above embodiments, those skilled in the art should understand that they can modify the technical solutions recorded in the above embodiments, or make equivalent replacement for part of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application, and should be included in the protection scope of the present application.​

Claims

1. A method for monitoring road subsidence defects, characterized in that, The method includes the following steps: Collect ultrasonic echo signals from the target area on the road surface; The frequency band of the ultrasonic echo signal in the frequency domain is divided into several sub-segments. Based on the energy distribution in the sub-segments, the spectral morphology characteristics of the echo signal are analyzed to determine the scattering properties of the cavity subsidence in the target area of ​​the road surface. Based on the fluctuations of the ultrasonic echo signal, the effective duration of the signal is analyzed to determine the temporal dispersion of the target area on the road surface. Based on the scattering properties of the cavity subsidence and the time-domain dispersion, the cavity subsidence discrimination factor of the target area of ​​the road surface is determined. Based on the cavity and subsidence discrimination factor, it is determined whether there is subsidence damage in the target area of ​​the road surface.

2. The method for monitoring road subsidence according to claim 1, characterized in that, Based on the energy distribution in the sub-segments, the spectral morphology characteristics of the echo signal are analyzed to determine the scattering properties of cavities and subsidence in the target area of ​​the road surface, including: When the frequency band of the ultrasonic echo signal is divided into several sub-segments in the frequency domain, several decomposition coefficients corresponding to each sub-segment are obtained; Based on the aforementioned decomposition coefficients, the energy characteristic value of each sub-segment is determined; Based on the energy characteristic values ​​and center frequencies of all sub-segments, the spectral energy offset factor of the target area of ​​the road surface is determined; Based on the difference between the center frequency of all sub-segments and the spectral energy offset factor, and combined with the energy characteristic values ​​of all sub-segments, the scattering property of the cavity subsidence in the target area of ​​the road surface is determined.

3. The method for monitoring road subsidence according to claim 2, characterized in that, Determine the spectral energy shift factor for the target area of ​​the road surface, including: The first accumulated value is obtained by summing the products of the energy eigenvalues ​​and center frequencies of all segments. Determine the cumulative value of the energy characteristic values ​​of all sub-segments to obtain the second cumulative value; The ratio of the first accumulated value to the second accumulated value is determined to obtain the spectral energy shift factor of the target area of ​​the road surface.

4. The method for monitoring road subsidence according to claim 3, characterized in that, Determine the scattering properties of cavitation subsidence in the target area of ​​the road surface, including: Determine the difference between the center frequency of each sub-segment and the spectral energy offset factor, and determine the frequency difference value; The cumulative value of the product of the energy characteristic values ​​of all sub-segments and the frequency difference value is determined to obtain the third cumulative value; Based on the ratio of the third accumulated value to the second accumulated value, the scattering property of the cavity subsidence in the target area of ​​the road surface is determined.

5. The method for monitoring road subsidence according to claim 1, characterized in that, Analyze the effective duration of the signal to determine the temporal dispersion of the target area on the road surface, including: The effective duration of the ultrasonic echo signal is determined based on the changes in the envelope of the ultrasonic echo signal. The temporal dispersion of the target road surface area is determined based on the difference between the effective duration and the reference effective duration corresponding to the healthy road surface area.

6. The method for monitoring road subsidence according to claim 5, characterized in that, Determining the effective duration of the ultrasonic echo signal includes: Based on the changes in the envelope, the peak value of the envelope is determined, and based on the peak value, the energy threshold is determined. Searching backwards from the starting point of time, the time point at which the signal value on the envelope first rises from below the energy threshold to equal or above the energy threshold is determined as the starting time point; The search proceeds backward from the end of time to determine the point in time when the signal value on the envelope first rises from below the energy threshold to equal to or above the energy threshold, which is then taken as the termination point. The duration between the start time point and the end time point is taken as the effective duration of the ultrasonic echo signal.

7. The method for monitoring road subsidence according to claim 1, characterized in that, Before dividing the frequency band of the ultrasonic echo signal into several sub-segments in the frequency domain, the method further includes preprocessing the ultrasonic echo signal. The preprocessing process includes: The ultrasonic echo signal is bandpass filtered to obtain the filtered ultrasonic echo signal. Baseline correction is performed on the filtered ultrasonic echo signal to obtain the preprocessed ultrasonic echo signal.

8. The method for monitoring road subsidence according to claim 2, characterized in that, The frequency band of the ultrasonic echo signal in the frequency domain is divided into several sub-segments, including: The frequency band of the ultrasonic echo signal in the frequency domain is divided into several sub-bands of equal width using wavelet packet transform, and several decomposition coefficients corresponding to each sub-segment are obtained during the frequency band division process.

9. A monitoring device for road subsidence defects, characterized in that, The device includes: The ultrasonic signal acquisition module is used to collect ultrasonic echo signals from the target area of ​​the road surface. The scattering analysis module is used to divide the frequency band of the ultrasonic echo signal in the frequency domain into several sub-segments, analyze the spectral morphology characteristics of the echo signal based on the energy distribution in the sub-segments, and determine the scattering properties of the cavity subsidence in the target area of ​​the road surface. The dispersion analysis module is used to analyze the effective duration of the signal based on the fluctuation changes of the ultrasonic echo signal, and to determine the temporal dispersion of the target area of ​​the road surface. The discrimination factor determination module is used to determine the cavity subsidence discrimination factor of the target area of ​​the road surface based on the cavity subsidence scattering and the time-domain dispersion. The subsidence defect identification module is used to determine whether subsidence defects exist in the target area of ​​the road surface based on the cavity subsidence discrimination factor.

10. A monitoring system for road subsidence defects, characterized in that, The method includes a memory, a processor, and executable computer program code stored in the memory and executable on the processor, wherein the processor executes the computer program code to perform a method for monitoring road subsidence as described in any one of claims 1 to 8.

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