Three-dimensional display of road internal defects and characteristic signal determination method based on radar

Abstract

The present invention discloses a method for three-dimensional display and characteristic signal determination of internal road diseases based on radar, including: S1, collecting ground-penetrating radar echo signals inside the road; S2, preprocessing the echo signals, and extracting signals corresponding to internal road diseases based on the preprocessed echo signals; S3, constructing a road internal disease data set based on the extracted signals corresponding to the internal road diseases; S4, based on the disease data set, three-dimensionally displaying the internal road diseases, and determining the characteristic signals corresponding to the target diseases based on the three-dimensional display. Based on the constructed road disease radar data set, the diseases are displayed in three dimensions, making the radar data and the internal road conditions more intuitive, solving the problem that radar spectra are difficult to identify and radar data are difficult to interpret.

Description

Technical Field

[0001] The present invention belongs to the technical field of road defect detection and radar detection imaging, and specifically relates to a radar-based three-dimensional display method for road internal defects and a characteristic signal determination method. Background Art

[0002] With the increase of road service life and the simultaneous effects of factors such as climate and load, the road surface will have different degrees of disease. If it is not maintained in time, it will affect the normal traffic and safe driving of vehicles. Therefore, accurate evaluation of road conditions and selection of appropriate maintenance plans are important prerequisites for extending the service life of roads and ensuring the normal operation of traffic. Three-dimensional ground penetrating radar has become an important means of obtaining information on the internal structure of roads due to its fast, accurate and non-destructive characteristics. Three-dimensional ground penetrating radar transmits high-frequency pulse electromagnetic waves to detect the spatial distribution of the medium through a leapfrogging multi-channel transmitting and multi-channel receiving antenna architecture, while taking into account shallow resolution and detection depth, to achieve high-density non-destructive testing and high-precision imaging of roads. Based on the obtained radar spectrum, the type of disease can be preliminarily determined based on the expert interpretation method. However, the establishment of the accurate relationship between the radar spectrum characteristics and the road structure still requires multiple core sampling verifications and the accumulation of rich experience; and the internal structure characteristics cannot be accurately understood based on the two-dimensional radar spectrum alone. Summary of the invention

[0003] In view of the problems in the prior art, the present invention proposes a method for three-dimensional display and characteristic signal determination of road internal defects based on ground penetrating radar detection, which is used to extract radar data, display the road internal defects in three dimensions and determine the characteristic signals corresponding to different types of defects, providing an accurate basis for identifying radar signals and interpreting radar maps in the future.

[0004] To achieve the above object, the present invention provides the following solutions:

[0005] The method for three-dimensional display of internal road defects and determination of characteristic signals based on radar includes the following steps:

[0006] S1, collecting ground penetrating radar echo signals inside the road;

[0007] S2, preprocessing the echo signal, and extracting a signal corresponding to the internal road disease based on the preprocessed echo signal;

[0008] S3. Constructing a road internal disease dataset based on the extracted signals corresponding to the road internal diseases;

[0009] S4. Based on the disease data set, a three-dimensional display of the internal diseases of the road is performed, and based on the three-dimensional display, a characteristic signal corresponding to the target disease is determined.

[0010] Preferably, the method for collecting the echo signal includes:

[0011] Divide the road to be measured into several measuring lines according to the driving direction;

[0012] The echo signal of the survey line is collected by using ground penetrating radar.

[0013] Preferably, the method for preprocessing the echo signal includes: zero bias processing, zero point adjustment, gain adjustment, data filtering and background elimination;

[0014] The zero bias processing is used to make the single-channel echo signal symmetrical;

[0015] The zero point adjustment is used to eliminate the distance between the ground penetrating radar transmitting antenna and the ground, and adjust the ground position to a position where the timing position is 0;

[0016] The gain adjustment is used to strengthen the echo signal of deep-seated diseases;

[0017] The data filtering is used to eliminate interference waves in the echo signal and extract useful signals from the echo signal;

[0018] The background elimination is used to eliminate the horizontal signal in the deep echo signal.

[0019] Preferably, the zero bias processing process includes:

[0020]

[0021] Where A(n) represents the original single-channel echo signal without processing; A'(n) represents the single-channel echo signal after zero bias processing; N represents the number of single-channel waveform sampling points, and n represents the nth sample scanned by each single-channel echo signal.

[0022] Preferably, the background elimination process includes:

[0023]

[0024] y(t)=x(t)-x(t)'

[0025] Where N1 and N2 represent the start and end trace numbers of the selected survey line respectively; x(t)' represents the average value of the signal in the selected area; x(t) represents the amplitude of the original trace reflection echo signal, and y(t) represents the amplitude of the original trace reflection echo signal.

[0026] Preferably, the method for constructing the road internal disease dataset includes:

[0027] Transposing the signals corresponding to the extracted internal road diseases into a one-dimensional matrix;

[0028] Constructing the three-dimensional coordinates of the signal corresponding to the internal disease of the road according to the sampling interval, the distance between the transmitting and receiving antennas, and the characteristic point sampling interval;

[0029] The one-dimensional matrix and the three-dimensional coordinates are matched one by one to obtain the road internal disease data set.

[0030] Preferably, the method for three-dimensionally displaying internal road damage includes:

[0031] The road internal disease data set is sorted according to depth, and the data point set formed according to antenna intervals is rearranged into a data point set formed by feature points;

[0032] Performing interpolation processing on the data point set consisting of the feature points to obtain dense discrete point data;

[0033] Parameters and attributes are set for the dense discrete point data to obtain a three-dimensional rendering of the road internal damage.

[0034] Preferably, the method for determining the characteristic signal corresponding to the target disease includes:

[0035] Select the isosurface module through the voxler software;

[0036] Adjusting the critical value of the isosurface graph module until a complete semi-closed isosurface is obtained;

[0037] Based on the complete semi-closed isosurface, a characteristic signal corresponding to the target disease is determined.

[0038] The beneficial effects of the present invention are:

[0039] The present invention makes full use of radar data detected by three-dimensional ground penetrating radar, and based on the constructed road disease radar data set, displays the diseases in three dimensions, making the radar data and the internal conditions of the road more intuitive, thus solving the problem that radar maps are difficult to identify and radar data are difficult to interpret.

[0040] The present invention makes full use of the ground penetrating radar echo signal to construct a three-dimensional body of internal road defects, realizes the three-dimensional visualization of radar data and determines the radar signal characteristics corresponding to different types of defects, has a higher accuracy in identifying radar signals, and provides a basis for establishing the corresponding relationship between radar signals and road defects in the future. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] In order to more clearly illustrate the technical solution of the present invention, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0042] Figure 1 A schematic flow chart of a method for three-dimensional display of internal road defects and determination of characteristic signals based on radar proposed in the present invention;

[0043] Figure 2 A radar data preprocessing flow chart of the radar-based road internal disease three-dimensional display and characteristic signal determination method proposed by the present invention;

[0044] Figure 3 A flow chart of the three-dimensional display of internal road diseases of the method for three-dimensional display of internal road diseases and determination of characteristic signals based on radar proposed by the present invention;

[0045] Figure 4 A flow chart of characteristic signals for determining target diseases in a method for three-dimensional display of internal road diseases and characteristic signal determination based on radar proposed by the present invention;

[0046] Figure 5 The pre-processed radar image extracted by the radar-based three-dimensional display of internal road diseases and the characteristic signal determination method proposed by the present invention;

[0047] Figure 6 A three-dimensional display diagram of internal road diseases according to the method for three-dimensional display of internal road diseases and determination of characteristic signals based on radar proposed by the present invention;

[0048] Figure 7 This is a complete semi-closed isosurface diagram of the radar-based three-dimensional display of internal road defects and the characteristic signal determination method proposed in the present invention. DETAILED DESCRIPTION

[0049] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0050] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0051] Embodiment 1

[0052] like Figure 1 FIG. 1 is a flow chart of a method for three-dimensional display of internal road defects and determination of characteristic signals based on radar according to the present invention, which includes the following steps:

[0053] S1, collecting ground penetrating radar echo signals inside the road;

[0054] In this embodiment, firstly, the road to be measured is divided into a plurality of measuring lines according to the driving direction; secondly, under the premise of ensuring the acquisition accuracy, the ground penetrating radar is used to collect echo signals from the plurality of measuring lines.

[0055] S2, preprocessing the echo signal, and extracting the signal corresponding to the internal disease of the road based on the preprocessed echo signal;

[0056] like Figure 2 As shown, in this embodiment, the preprocessing method includes: zero bias processing, zero point adjustment, gain adjustment, data filtering and background elimination;

[0057] Among them, the echo signal can be made symmetrical by performing zero bias processing on the echo signal. The method of zero bias processing includes: summing the single-channel echo signal, taking the mean value, and finally subtracting the mean value from the waveform data of the channel to obtain the zero bias result. The calculation formula is as follows:

[0058]

[0059] Wherein, A(n) represents the original single-channel echo signal without processing; A'(n) represents the single-channel echo signal after zero bias processing; N represents the number of single-channel waveform sampling points, and n represents the nth sample scanned by each single-channel echo signal. In this embodiment, N is 256.

[0060] Zero point adjustment can eliminate the distance between the ground penetrating radar transmitting antenna and the ground, and adjust the ground position to the position where the timing position is 0; the specific calculation process is as follows:

[0061]

[0062] In the formula, c represents the propagation speed of electromagnetic waves in vacuum; ε r represents the relative dielectric constant of air. In this embodiment, c=3×10 8 m / s; adjust the time window zero position to 30 cm downward from the profile.

[0063] The gain adjustment is used to strengthen the echo signal of deep-seated diseases. In this embodiment, the gain adjustment selects the compensation gain, and the gain coefficient is 50.

[0064] Data filtering is used to eliminate interference waves in the echo signal and extract useful signals from the echo signal; specifically, it includes: using a linear phase finite pulse response filter, according to the spectrum characteristics of the useful signal and the interference signal, and then building a selective frequency filter for road detection; eliminating interference waves through the above filter and extracting useful signals from the echo signal. In this embodiment, the low-frequency signal is 450MHz and the high-frequency signal is 1350MHz.

[0065] Background elimination is used to eliminate the horizontal signal in the deep echo signal; the method includes: averaging the collected echo signal to represent the horizontal signal, subtracting the mean interference data from each data, and then strengthening the target signal. The specific calculation process is as follows:

[0066]

[0067] y(t)=x(t)-x(t)'

[0068] In the formula, N1 and N2 represent the number of channels at the beginning and end of the selected survey line respectively; x(t)' represents the average value of the signal in the selected area; x(t) represents the amplitude of the original channel reflection echo signal, and y(t) represents the amplitude of the original channel reflection echo signal. This embodiment uses the overall method, and the processing range is 1-256. Figure 5 , which is a radar chart after preprocessing in this embodiment.

[0069] Methods for extracting signals corresponding to internal road diseases include:

[0070] The type of the disease is preliminarily determined based on the preprocessed echo signal, and the location of the disease is located; in this embodiment, the disease type is a crack disease, and the location of the disease is between the 17200th sampling point and the 17600th sampling point.

[0071] MATLAB is used to extract the echo signal of the located disease.

[0072] S3, constructing a road internal disease dataset based on the extracted signals corresponding to the road internal diseases;

[0073] The methods for constructing road internal disease datasets include:

[0074] The signals corresponding to the extracted internal road diseases are transposed and arranged into a one-dimensional matrix; in this embodiment, the 17200th sampling point to the 17600th sampling point are arranged in sequence and transposed into a one-dimensional matrix.

[0075] The three-dimensional coordinates of the signal corresponding to the internal road disease are constructed according to the sampling interval, the distance between the transmitting and receiving antennas, and the sampling interval of the feature points; the sampling interval is the distance corresponding to the round-trip travel time of each transmission and reception of the ground penetrating radar; the distance between the transmitting and receiving antennas is the distance between each transmitting antenna and the receiving antenna in the antenna array; in this embodiment, the interval is set to 2.58 cm, and the distance between a group of transmitting antennas and receiving antennas is 19.5 cm; there are 7 groups in total, each group is separated by 6.5 cm, and the sampling interval of the feature points is set to 0.4 cm, to construct the three-dimensional coordinates of the echo signal.

[0076] By making one-to-one correspondence between the one-dimensional matrix and the three-dimensional coordinates, we can obtain the road internal disease data set.

[0077] S4. Based on the disease data set, a three-dimensional display of the internal diseases of the road is performed, and based on the three-dimensional display, the characteristic signal corresponding to the target disease is determined.

[0078] like Figure 3 As shown in FIG. 1 , the methods for three-dimensionally displaying internal road diseases include:

[0079] The road internal disease data set is sorted according to depth, and the data point set formed according to the antenna interval is rearranged into a data point set composed of feature points; in this embodiment, the area where the crack disease is located with a depth of 114.18 cm is selected, and the data point set is rearranged from 0 to 114.18 cm according to the depth into a data point set composed of feature points.

[0080] Perform interpolation processing on the data point set composed of feature points to obtain dense discrete point data;

[0081] This embodiment uses voxler software to perform interpolation processing on a data point set consisting of feature points, gridding it, and then obtaining dense discrete point data; the specific steps are:

[0082] (1) Perform interpolation operation on the data point set consisting of feature points: Great → Computational → Gridder;

[0083] (2) Add the Gridder model to the Network workspace and connect it to the imported road internal disease dataset;

[0084] (3) Select the inverse distance method in the Gridder model's properties window, adjust the weighting index to 2, and run BeginGridding.

[0085] The parameters and attributes of the dense discrete point data are set to obtain the three-dimensional rendering of the road internal disease. Specifically include:

[0086] Add coordinate axes in voxler software, set color levels in ColorMap properties, add Axes and connect it to Gridder.

[0087] Add VolRender in the Network workspace and connect it to Gridder. Set the color level to Rainbow6 in the ColorMap property, select the trilinear method in the VolRender model property window, and adjust the opacity to 0.27 to obtain the 3D rendering of the road internal damage. Figure 6 As shown, it is a three-dimensional display diagram of the internal diseases of the road in this embodiment.

[0088] like Figure 4 As shown, the method for determining the characteristic signal of the target disease includes:

[0089] Select the isosurface module through voxler software; specifically:

[0090] Add an Isosurface in the Network workspace and connect it to Gridder.

[0091] Adjust the critical value of the isosurface module until a complete semi-closed isosurface is obtained; specifically:

[0092] Adjust the Critical Value in the Isosurface property until a complete semi-enclosed isosurface can be seen in the observer window. In this embodiment, when the critical value is 4202.64, a complete semi-enclosed isosurface can be obtained. Figure 7 As shown, it is a complete semi-closed isosurface diagram of this embodiment.

[0093] Based on the complete semi-closed isosurface, the characteristic signal corresponding to the target disease is determined. Specifically:

[0094] The Critical Value adjusted in the Isosurface attribute is the characteristic signal corresponding to the road disease. In this embodiment, the characteristic signal value of the crack disease is 4202.64.

[0095] The embodiments described above are only descriptions of the preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Without departing from the design spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by ordinary technicians in this field should all fall within the protection scope determined by the claims of the present invention.

Claims

1. A radar-based three-dimensional display method for internal road defects and a method for determining characteristic signals, characterized in that: The following steps are involved: S1, collecting ground penetrating radar echo signals inside the road; S2, preprocessing the echo signal, and extracting a signal corresponding to the internal road disease based on the preprocessed echo signal; S3. Constructing a road internal disease dataset based on the extracted signals corresponding to the road internal diseases; The method for constructing the road internal disease dataset includes: Transposing the signals corresponding to the extracted internal road diseases into a one-dimensional matrix; Constructing the three-dimensional coordinates of the signal corresponding to the internal disease of the road according to the sampling interval, the distance between the transmitting and receiving antennas, and the characteristic point sampling interval; The one-dimensional matrix and the three-dimensional coordinates are matched one by one to obtain the road internal disease data set; S4. Based on the disease data set, three-dimensionally display the internal diseases of the road, and based on the three-dimensional display, determine the characteristic signal corresponding to the target disease; The method for three-dimensionally displaying internal road defects comprises: The road internal disease data set is sorted according to depth, and the data point set formed according to antenna intervals is rearranged into a data point set formed by feature points; Performing interpolation processing on the data point set consisting of the feature points to obtain dense discrete point data; Setting parameters and attributes of the dense discrete point data to obtain a three-dimensional rendering of the road internal disease; The method for determining the characteristic signal corresponding to the target disease includes: Select the isosurface module through the voxler software; Adjusting the critical value of the isosurface graph module until a complete semi-closed isosurface is obtained; Based on the complete semi-closed isosurface, a characteristic signal corresponding to the target disease is determined.

2. The method for three-dimensional display of internal road defects and determination of characteristic signals based on radar according to claim 1 is characterized in that: The method for collecting the echo signal includes: Divide the road to be measured into several measuring lines according to the driving direction; The echo signal of the survey line is collected by using ground penetrating radar.

3. The method for three-dimensional display of internal road defects and determination of characteristic signals based on radar according to claim 1 is characterized in that: The method for preprocessing the echo signal includes: zero bias processing, zero point adjustment, gain adjustment, data filtering and background elimination; The zero bias processing is used to make the single-channel echo signal symmetrical; The zero point adjustment is used to eliminate the distance between the ground penetrating radar transmitting antenna and the ground, and adjust the ground position to a position where the timing position is 0; The gain adjustment is used to strengthen the echo signal of deep-seated diseases; The data filtering is used to eliminate interference waves in the echo signal and extract useful signals from the echo signal; The background elimination is used to eliminate the horizontal signal in the deep echo signal.

4. The method for three-dimensional display of internal road defects and determination of characteristic signals based on radar according to claim 3 is characterized in that: The zero bias processing process includes: Where A(n) represents the original single-channel echo signal without processing; A'(n) represents the single-channel echo signal after zero bias processing; N represents the number of single-channel waveform sampling points, and n represents the nth sample scanned by each single-channel echo signal.

5. The method for three-dimensional display of internal road defects and determination of characteristic signals based on radar according to claim 3 is characterized in that: The background elimination process includes: y(t)=x(t)-x(t)' Where N1 and N2 represent the start and end trace numbers of the selected survey line respectively; x(t)′ represents the average value of the signal in the selected area; x(t) represents the amplitude of the original trace reflection echo signal, and y(t) represents the amplitude of the original trace reflection echo signal.

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