Tunnel monitoring method based on radar high-precision phase ranging technology

Abstract

The invention belongs to the technical field of radar micro-motion characteristic monitoring, and relates to a tunnel monitoring method based on a radar high-precision phase ranging technology, which comprises the following steps: 1) configuring two linear frequency sweeping modes for a radar, and enabling the frequency difference between the two linear frequency sweeping modes when frequency sweeping starts to be performed by one frequency sweeping bandwidth; 2) processing the echo signal to obtain phase change information of the echo signal of the monitored point; 3) according to the phase change information of the monitored point, calculating the phase whole-cycle count of the echo signal of the monitored point; 4) calculating the high-precision displacement of the monitored point according to the phase change information of the echo signal of the monitored point and the phase whole-cycle count of the echo signal of the monitored point; and 5) fusing the high-precision displacement of the monitored point to obtain the final high-precision displacement of the monitored point. The method not only improves the precision of displacement monitoring, but also enhances the robustness of the system through the application of a multi-sweep-frequency mode, so that the system can adapt to different monitoring environments and conditions.

Description

Technical Field

[0001] The present invention belongs to the technical field of radar micro-motion feature monitoring, and relates to a tunnel monitoring method based on radar high-precision phase ranging technology, and in particular to a tunnel monitoring method based on radar high-precision phase ranging technology in a multi-sweep frequency mode. Background Art

[0002] With the advent of the 21st century, the pace of tunnel construction in my country has accelerated significantly, and the construction scale and mileage are in a leading position worldwide. However, due to long-term use, tunnels are inevitably affected by natural and human factors, leading to the occurrence of various diseases. These diseases not only pose a serious threat to traffic safety, but also shorten the service life of the tunnel and bring huge economic losses.

[0003] Common tunnel diseases include voids behind the lining, loose grouting, insufficient lining thickness, segment misalignment, uneven settlement, water seepage, and lining material deterioration. In order to effectively monitor and evaluate these diseases, the industry has developed a variety of tunnel monitoring and detection technologies, such as 3D laser scanning technology, impact echo technology, infrared detection technology, fiber grating technology, high-definition camera technology, and optical measurement technology.

[0004] In addition, radar high-precision phase ranging technology can be used for tunnel monitoring. This technology reflects the real-time status of the tunnel by monitoring the high-precision displacement information of the monitored points in the tunnel. Compared with traditional 3D laser scanning technology and high-definition camera technology, radar high-precision phase ranging technology has obvious advantages in accuracy.

[0005] However, in practical applications, the branch cutting displacement measurement method used in traditional radar high-precision phase ranging technology has certain limitations. When a vehicle passes through the tunnel or personnel perform maintenance, the measurement may be temporarily interrupted, which may result in the large displacement occurring during this period not being accurately captured, resulting in the whole-cycle ambiguity problem of displacement measurement.

[0006] Therefore, in view of the defects existing in the above-mentioned prior art, it is necessary to develop a new tunnel monitoring method based on radar high-precision phase ranging technology. Summary of the invention

[0007] In order to overcome the defects of the prior art, the present invention proposes a tunnel monitoring method based on radar high-precision phase ranging technology, which introduces a variety of scanning frequency modes, can solve the whole cycle ambiguity problem caused by vehicle passing and personnel maintenance, making the application of radar high-precision phase ranging technology in tunnel monitoring more stable and reliable.

[0008] In order to achieve the above object, the present invention provides the following technical solutions:

[0009] A tunnel monitoring method based on radar high-precision phase ranging technology, characterized in that it includes the following steps:

[0010] 1) Two linear sweep modes are configured for the radar, and the frequencies at which the sweep starts in the two linear sweep modes differ by a sweep bandwidth;

[0011] 2) Processing the echo signals of the two linear frequency sweep modes to obtain the phase change information of the echo signals of the monitored points in the two linear frequency sweep modes;

[0012] 3) calculating the phase integer counts of the echo signals of the monitored points in the two linear frequency sweep modes according to the phase change information of the echo signals of the monitored points in the two linear frequency sweep modes;

[0013] 4) Calculate the high-precision displacement of the monitored point in the two linear frequency sweep modes according to the phase change information of the echo signal of the monitored point in the two linear frequency sweep modes and the phase integer count of the echo signal of the monitored point in the two linear frequency sweep modes;

[0014] 5) The high-precision displacements of the monitored points in the two linear sweep frequency modes are fused to obtain the final high-precision displacement of the monitored points.

[0015] Preferably, the step 2) is specifically as follows: the echo signals of the two linear frequency sweeping modes are first de-skewed, and then analog-to-digital conversion sampling is performed to convert the continuous analog signal into a digital signal and the digital signal is filtered and signal enhancement processing is performed, and then the processed digital signal is windowed and the windowed digital signal is fast Fourier transformed to obtain the phase change information θ1 and θ2 of the echo signals of the monitored points in the two linear frequency sweeping modes.

[0016] Preferably, the integer count N1 of the echo signal of the monitored point in the two linear sweep modes is calculated in step 3) as follows:

[0017]

[0018] Where s1 is the displacement corresponding to a 360° phase change in linear sweep mode 1, and s2 is the displacement corresponding to a 360° phase change in linear sweep mode 2.

[0019] Preferably, the high-precision displacement of the monitored point in the two linear sweep frequency modes is calculated in step 4) as follows:

[0020] r1=(N1*360+θ1)*k1

[0021] r2=(N1*360+θ2)*k2

[0022] Where r1 is the high-precision displacement of the monitored point in linear sweep mode 1, and r2 is the high-precision displacement of the monitored point in linear sweep mode 2.

[0023] Preferably, in step 5), the high-precision displacements of the monitored points in the two linear frequency sweep modes are fused by averaging or weighted averaging.

[0024] Preferably, in step 5), the high-precision displacements of the monitored points in the two linear sweep frequency modes are fused by averaging, that is, r is the final high-precision displacement of the monitored point.

[0025] Preferably, in step 1), the frequency at which the frequency sweep starts in linear frequency sweep mode 1 is f1 and the frequency sweep bandwidth is B, and the frequency at which the frequency sweep starts in linear frequency sweep mode 2 is f2 and the frequency sweep bandwidth is B, then, f2=f1+B.

[0026] Preferably, the tunnel monitoring method based on radar high-precision phase ranging technology further comprises:

[0027] 6) Verify and analyze the final high-precision displacement of the monitored points to ensure its accuracy and reliability.

[0028] Preferably, the verification and analysis of the final high-precision displacement of the monitored point in step 6) includes comparison with historical data and statistical analysis.

[0029] Compared with the prior art, the tunnel monitoring method based on radar high-precision phase ranging technology of the present invention has one or more of the following beneficial technical effects:

[0030] 1. Compared with the prior art, the present invention can effectively solve the whole-circle ambiguity problem when vehicles or personnel undergo maintenance, thereby improving the accuracy and reliability of tunnel monitoring.

[0031] 2. The present invention can provide higher measurement accuracy by using multi-sweep frequency technology, and can more accurately identify and distinguish the tiny displacements of the target object.

[0032] 3. The present invention can achieve accurate displacement monitoring, which helps to timely discover and deal with potential structural problems, thereby reducing long-term maintenance costs and potential repair costs.

[0033] 4. The present invention helps to ensure public safety and prevent accidents caused by structural displacement by accurately monitoring the displacement of key structures such as tunnels.

[0034] 5. The present invention is easy to implement rapid deployment and application.

[0035] 6. The present invention is applicable to a variety of monitoring scenarios, including but not limited to displacement monitoring of tunnels, bridges and other key infrastructure. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 It is a flow chart of the tunnel monitoring method based on radar high-precision phase ranging technology of the present invention.

[0037] Figure 2 It is a schematic diagram of an exemplary installation of a radar in a tunnel to monitor a monitored point according to the present invention. DETAILED DESCRIPTION

[0038] Before describing in detail any embodiment of the present invention, it should be understood that the present invention is not limited in its application to the construction and arrangement details of the components described below or illustrated in the following figures. The present invention can have other embodiments and can be practiced or carried out in various ways. In addition, it should be understood that the words and terms used here are for descriptive purposes and should not be considered restrictive. The use of "including" or "having" and its variations herein is intended to cover the items and their equivalents and additional items displayed below. Unless otherwise specified or limited, the terms "install", "connect", "support" and "couple" and their variations are widely used and cover direct installation and indirect installation, connection, support and connection. In addition, "connect" and "couple" are not limited to physical or mechanical connections or connections.

[0039] Furthermore, on the first aspect, in the disclosure of the present invention, the orientation or positional relationship indicated by terms such as "longitudinal", "transverse", "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside" and "outside" are based on the orientation or positional relationship shown in the accompanying drawings, which are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operate in a specific orientation, and therefore the above terms cannot be understood as limitations on the present invention; on the second aspect, the term "one" should be understood as "at least one" or "one or more", that is, in one embodiment, the number of an element may be one, while in another embodiment, the number of the element may be multiple, and the term "one" cannot be understood as a limitation on the quantity.

[0040] In order to overcome the defects of the prior art, the present invention provides a tunnel monitoring method based on a radar high-precision phase ranging technology with a multi-sweep frequency mode, which adopts two linear sweep frequency modes, respectively calculates the phase difference of the echo signal of the monitored point under the two linear sweep frequency mode scenarios, and respectively calculates the phase integer number of the echo signal of the monitored point under the two linear sweep frequency modes according to the two phase differences, and then respectively adds the phase differences to calculate the high-precision displacement under the two linear sweep frequency modes, and finally sums and averages the high-precision displacement under the two linear sweep frequency modes to obtain the final high-precision displacement output. The method of the present invention not only improves the accuracy of displacement monitoring, but also enhances the robustness of the system through the application of the multi-sweep frequency mode, so that it can adapt to different monitoring environments and conditions, and provides an efficient and reliable solution for tunnel safety monitoring.

[0041] Figure 1 The flowchart of the tunnel monitoring method based on radar high-precision phase ranging technology of the present invention is shown. Figure 1 As shown, the tunnel monitoring method based on radar high-precision phase ranging technology of the present invention comprises the following steps:

[0042] 1. Configure two linear sweep modes for the radar, and the frequencies at which the sweep starts in the two linear sweep modes differ by a sweep bandwidth.

[0043] Specifically, two linear sweep modes can be configured for the radar, namely linear sweep mode 1 and linear sweep mode 2. In linear sweep mode 1, the frequency at which the sweep starts is f1 and the sweep bandwidth is B, and in linear sweep mode 2, the frequency at which the sweep starts is f2 and the sweep bandwidth is B, wherein f2=f1+B.

[0044] Second, the echo signals of the two linear frequency sweep modes are processed to obtain the phase change information of the echo signals of the monitored points in the two linear frequency sweep modes, that is, the phase difference.

[0045] In the present invention, two linear frequency sweep modes are used to sweep the monitored points respectively, to obtain echo signals in the two linear frequency sweep modes, and then the echo signals in the two linear frequency sweep modes are processed.

[0046] When processing, de-skewing is performed first. De-skewing is a signal processing technology that is mainly used to process linear frequency modulation signals. It obtains the range image of the target through mixing and DFT processing, effectively reducing the signal bandwidth. Through de-skewing, the linear phase change in the echo signal can be corrected, thereby improving the accuracy of the measurement.

[0047] Then analog-to-digital conversion sampling is performed to convert the continuous analog signal into a digital signal and the digital signal is filtered and signal enhanced.

[0048] The processed digital signal is then subjected to windowing processing, which can reduce the edge effect of the signal and improve the accuracy of spectrum analysis.

[0049] Finally, the windowed digital signal is subjected to a fast Fourier transform to obtain the phase change information θ1 and θ2 of the monitored points in two linear sweep modes, that is, the phase difference. Fast Fourier transform (FFT) is an efficient frequency domain analysis tool that converts time domain signals into frequency domain signals. Through FFT, the frequency components of the signal can be analyzed to identify the tiny displacements and deformations of the tunnel structure. By comparing the signals at different time points, the changes of the tunnel structure over time can be monitored.

[0050] 3. Calculate the phase integer count of the echo signal of the monitored point in the two linear frequency sweep modes according to the phase change information of the echo signal of the monitored point in the two linear frequency sweep modes.

[0051] After obtaining the phase change information θ1 and θ2 of the echo signal of the monitored point in the two linear scanning modes, the phase integer count N1 of the echo signal of the monitored point in the two linear scanning modes can be calculated according to θ1 and θ2. That is,

[0052]

[0053] Wherein, s1 is the displacement corresponding to a 360° phase change in linear sweep mode 1, which can be obtained in a laboratory scenario by measuring the slight change in the displacement of the angle inversion, and is a known quantity. s2 is the displacement corresponding to a 360° phase change in linear sweep mode 2, which can also be obtained in a laboratory scenario by measuring the slight change in the displacement of the angle inversion, and is also a known quantity.

[0054] Fourth, the high-precision displacement of the monitored point in the two linear frequency sweep modes is calculated based on the phase change information of the echo signal of the monitored point in the two linear frequency sweep modes and the phase integer count of the echo signal of the monitored point in the two linear frequency sweep modes.

[0055] According to the phase change information, the phase integer number of the echo signal in each linear sweep mode is calculated. The integer number represents the number of a complete cycle of displacement change. Combining the phase change information (i.e., phase difference) and the integer count, the high-precision displacement of the monitored point in each linear sweep mode can be calculated. That is,

[0056] r1=(N1*360+θ1)*k1

[0057] r2=(N1*360+θ2)*k2

[0058] Where r1 is the high-precision displacement of the monitored point in linear sweep mode 1, and r2 is the high-precision displacement of the monitored point in linear sweep mode 2.

[0059] 5. The high-precision displacements of the monitored points in the two linear sweep frequency modes are fused to obtain the final high-precision displacements of the monitored points.

[0060] In order to obtain more reliable displacement measurement results, the final high-precision displacement is obtained according to r1 and r2. The high-precision displacement data in the two linear sweep modes can be fused by averaging, weighted averaging and other data fusion techniques.

[0061] In the present invention, preferably, fusion is performed by averaging, that is, r is the final high-precision displacement of the monitored point.

[0062] 6. Verify and analyze the final high-precision displacement of the monitored points to ensure its accuracy and reliability.

[0063] The final high-precision displacement calculated is verified and analyzed (including comparison with historical data and statistical analysis methods) to ensure its accuracy and reliability. Finally, a detailed monitoring report can be generated, including displacement data, analysis results and possible recommendations, to provide decision support for tunnel maintenance and safety management.

[0064] When using the tunnel monitoring method based on radar high-precision phase ranging technology of the present invention, Figure 2 As shown, multiple radars can be installed in the tunnel to monitor the monitored points. The radar starts to sweep the frequency. In the radar system, configuring the sweep mode is an effective method to improve the detection accuracy and resolution. By setting a starting frequency and gradually increasing it to a predetermined sweep bandwidth, the radar system can transmit a signal whose frequency changes over time. The key to this mode is that it can use the change in frequency to measure the distance and speed of the target. The starting frequency is the starting point of the sweep process, and the sweep bandwidth determines the range of frequency change. The sweep rate and bandwidth jointly affect the resolution and detection capability of the radar. In the sweep mode, the radar receiver receives the reflected signal and compares it with the transmitted signal. Due to the Doppler effect, the frequency of the reflected signal changes according to the speed of the target object. By analyzing these frequency changes, the radar system can accurately measure the speed and displacement of the target. The present invention configures two linear sweep modes to start sweeping to enhance the reliability of the data. The linear sweep mode 1 starts the sweep from f1, and the sweep bandwidth is B. The linear sweep mode 2 starts the sweep from f2, and the sweep bandwidth is B. Wherein, f2=f1+B.

[0065] The monitored points of the tunnel are scanned by radar, which emits electromagnetic waves of a specific frequency and receives echo signals reflected from the tunnel surface. The characteristics of the tunnel surface determine the intensity and phase of the echo signals, which carry important information about the displacement and deformation of the tunnel structure. Since the radar signal may be affected by multipath effects or inhomogeneous media during propagation, the present invention uses de-skewing processing technology to correct the linear phase change in the echo signal, thereby improving the accuracy of the measurement. The continuous analog signal is converted into a digital signal through analog-to-digital conversion (AD) sampling, and the FPGA is used to receive the converted digital signal and perform further processing, such as filtering, signal enhancement, etc. In addition, the signal is windowed before performing fast Fourier transform (FFT). The windowing process can reduce the edge effect of the signal and improve the accuracy of spectrum analysis. Fast Fourier transform is an efficient frequency domain analysis tool that converts time domain signals into frequency domain signals. Through FFT, the frequency components of the signal can be analyzed to identify the small displacement and deformation of the tunnel structure. By comparing the signals at different time points, the changes of the tunnel structure over time can be monitored. After the device obtains the phase change information θ1 and θ2 of the monitored point in the two linear sweep modes, the integer count N1 of the echo signal in the two linear sweep modes can be calculated based on θ1 and θ2. Among them, s1 is the displacement corresponding to the phase change of 360° in linear sweep mode 1, and s2 is the displacement corresponding to the phase change of 360° in linear sweep mode 2.

[0066]

[0067] Based on the phase difference (that is, the phase change information θ1 and θ2), the phase integer number of the echo signal in each linear sweep mode is calculated. The integer number represents the number of a complete cycle of displacement change. Combining the phase difference and the integer number, the high-precision displacement in each linear sweep mode can be calculated.

[0068] r1=(N1*360+θ1)*k1

[0069] r2=(N1*360+θ2)*k2

[0070] In order to obtain more reliable displacement measurement results, the final high-precision displacement is obtained according to r1 and r2, and the high-precision displacement data in the two linear sweep modes are fused by averaging, weighted averaging and other data fusion techniques. The calculated high-precision displacement results are verified and analyzed (including comparison with historical data and statistical analysis) to ensure their accuracy and reliability. Finally, a detailed monitoring report is generated, including displacement data, analysis results and possible suggestions, to provide decision support for tunnel maintenance and safety management.

[0071]

[0072] The present invention uses multiple frequencies and the multi-sweep mode can more accurately measure the speed of the target object because radar waves of different frequencies are affected by scattering and absorption in different ways, which allows the radar to distinguish between targets of different speeds and improve the estimate of the speed of a specific target. Using multiple frequencies can improve the spatial resolution of the radar. Higher frequency radar waves have smaller wavelengths and can therefore provide more detailed images. The multi-sweep mode allows the radar to scan multiple frequencies at the same time, thereby providing higher resolution images.

[0073] At the same time, the multi-sweep mode can help the radar system better identify and classify different targets. Different types of objects have different reflection characteristics for radar waves of different frequencies, so by analyzing these characteristics, the radar can more accurately identify the type of object. In addition, the data generated by the multi-sweep mode can be processed in a variety of ways to suit different mission requirements. For example, data from certain frequencies can be used for speed detection, while data from other frequencies can be used for distance or angle measurement. This flexibility makes the radar system more versatile and efficient.

[0074] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention, rather than to limit the scope of protection of the present invention. Those skilled in the art can modify or replace the technical solution of the present invention according to the idea of ​​the present invention without departing from the essence and scope of the technical solution of the present invention.

Claims

1. A tunnel monitoring method based on radar high-precision phase ranging technology, characterized in that: The following steps are involved: 1) Two linear sweep modes are configured for the radar, and the frequencies at which the sweep starts in the two linear sweep modes differ by a sweep bandwidth; 2) Processing the echo signals of the two linear frequency sweep modes to obtain the phase change information of the echo signals of the monitored points in the two linear frequency sweep modes; 3) calculating the phase integer counts of the echo signals of the monitored points in the two linear frequency sweep modes according to the phase change information of the echo signals of the monitored points in the two linear frequency sweep modes; 4) Calculate the high-precision displacement of the monitored point in the two linear frequency sweep modes according to the phase change information of the echo signal of the monitored point in the two linear frequency sweep modes and the phase integer count of the echo signal of the monitored point in the two linear frequency sweep modes; 5) The high-precision displacements of the monitored points in the two linear sweep frequency modes are fused to obtain the final high-precision displacement of the monitored points.

2. The tunnel monitoring method based on radar high-precision phase ranging technology according to claim 1 is characterized in that: The step 2) is specifically as follows: the echo signals of the two linear frequency sweep modes are first de-skewed, and then analog-to-digital conversion sampling is performed to convert the continuous analog signal into a digital signal and the digital signal is filtered and signal enhanced, and then the processed digital signal is windowed and fast Fourier transformed to obtain the phase change information θ1 and θ2 of the echo signals of the monitored points under the two linear frequency sweep modes.

3. The tunnel monitoring method based on radar high-precision phase ranging technology according to claim 2 is characterized in that: In step 3), the integer count N1 of the echo signal of the monitored point under the two linear sweep modes is calculated as follows: Where s1 is the displacement corresponding to a 360° phase change in linear sweep mode 1, and s2 is the displacement corresponding to a 360° phase change in linear sweep mode 2.

4. The tunnel monitoring method based on radar high-precision phase ranging technology according to claim 3 is characterized in that: The high-precision displacement of the monitored point in the two linear sweep frequency modes calculated in step 4) is specifically: r1=(N1*360+θ1)*k1 r2=(N1*360+θ2)*k2 Where r1 is the high-precision displacement of the monitored point in linear sweep mode 1, and r2 is the high-precision displacement of the monitored point in linear sweep mode 2.

5. The tunnel monitoring method based on radar high-precision phase ranging technology according to claim 4 is characterized in that: In the step 5), the high-precision displacements of the monitored points in the two linear frequency sweep modes are fused by averaging or weighted averaging.

6. The tunnel monitoring method based on radar high-precision phase ranging technology according to claim 5 is characterized in that: In step 5), the high-precision displacements of the monitored points in the two linear sweep frequency modes are fused by averaging, that is, r is the final high-precision displacement of the monitored point.

7. The tunnel monitoring method based on radar high-precision phase ranging technology according to claim 6 is characterized in that: In the step 1), the frequency at which the frequency sweep starts in the linear frequency sweep mode 1 is f1 and the frequency sweep bandwidth is B, and the frequency at which the frequency sweep starts in the linear frequency sweep mode 2 is f2 and the frequency sweep bandwidth is B, then, f2=f1+B.

8. The tunnel monitoring method based on radar high-precision phase ranging technology according to any one of claims 1 to 7, characterized in that: Further including: 6) Verify and analyze the final high-precision displacement of the monitored points to ensure its accuracy and reliability.

9. The tunnel monitoring method based on radar high-precision phase ranging technology according to claim 8 is characterized in that: The verification and analysis of the final high-precision displacement of the monitored point in step 6) includes comparison with historical data and statistical analysis.

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