A method for monitoring the subsidence of a high-speed magnetic levitation track

Abstract

The present invention discloses a method for monitoring the settlement of a high-speed magnetic levitation track. First, during the travel of a magnetic levitation train, the communication signal power value of an existing high-speed magnetic levitation millimeter wave communication system is extracted, and a received power curve of the line is drawn. Then, by analyzing the changes in the received power curve, the settlement of the track is detected, and the settlement value is extracted using the offset of the peaks and troughs to achieve track monitoring. The method of the present invention is based on a dual-path propagation model in wireless communication and relies on an existing high-speed magnetic levitation millimeter wave communication system. It overcomes the problems of complex operation and poor real-time performance of existing track monitoring methods, and also solves the difficult problems of high cost and multiple environmental restrictions of modern track monitoring technology. It can serve as a powerful supplement to existing monitoring systems and is applicable to high-speed magnetic levitation tracks, as well as high-speed railways, ordinary railways, and even low-speed railways, where track settlement monitoring is required. It has the advantages of good real-time performance, a wide measurement range, and low cost.

Description

Technical Field

[0001] The invention belongs to the technical field of track settlement monitoring, and in particular relates to a settlement monitoring method for a high-speed magnetic levitation track. Background Art

[0002] Track settlement refers to the change in longitudinal height of railway tracks over long-term use due to compression, loss of foundation and roadbed, or other factors. Track settlement can affect the smoothness and safety of trains and can even lead to serious accidents such as derailments. In recent years, numerous accidents related to track settlement have highlighted the severity of this issue. In July 2009, track settlement on my country's Shijiazhuang-Taiyuan Passenger Dedicated Line led to speed restrictions on trains, severely disrupting transportation order and endangering safety. The Ministry of Railways classified the incident as a major engineering quality accident. In 2015, track settlement increased the track grade to 7% on a train in Mexico, exceeding braking capacity and causing it to collide with another train, injuring 12 people. In May 2021, a bridge collapsed and derailed Line 12 of the Mexico City Light Rail, killing 26 people. It was later discovered that several track posts had already posed safety hazards due to settlement. These examples highlight the potential threat of track settlement to railway system safety. Therefore, how to effectively monitor and prevent track settlement has become a key issue in railway transportation safety management. In recent years, with the rapid development of track construction, especially the rise of high-speed maglev trains, people have paid more and more attention to related safety issues and put forward higher requirements for the accurate measurement of track settlement.

[0003] Existing methods for monitoring track subsidence primarily include leveling and total station measurements. While these methods offer high accuracy, they are complex, time-consuming, labor-intensive, require extensive manual intervention, and are unable to achieve real-time monitoring. With advances in technology, modern track monitoring methods have gradually developed and been applied, including GNSS positioning, InSAR measurement, and laser scanning. Compared to traditional methods, these modern monitoring technologies offer significant advantages, including real-time monitoring, a high degree of automation, and comprehensive data integration and analysis. However, they also have limitations. For example, GNSS positioning technology performs poorly in tunnels or areas with limited signal availability, and the equipment is relatively expensive. InSAR technology has a long data acquisition cycle, high costs, and relatively low resolution. Laser scanning technology is susceptible to inclement weather, and data processing is complex and the equipment is expensive.

[0004] my country's existing high-speed maglev train-to-ground communication system uses millimeter-wave communication technology, which offers advantages such as large communication capacity, strong confidentiality, and all-weather communication. Compared to centimeter waves, millimeter waves are more sensitive to track settlement due to their higher frequency and shorter wavelength. Furthermore, millimeter-wave beams are narrower and more controllable, enabling better coverage of the track area and improving monitoring efficiency. However, existing track settlement monitoring methods suffer from cumbersome operation, poor real-time performance, high costs, and environmental and weather restrictions, making them difficult to apply to settlement measurements on high-speed maglev tracks. Therefore, a track settlement monitoring method with good real-time performance, a wide measurement range, and low cost is needed. Summary of the Invention

[0005] To solve the above technical problems, the present invention provides a settlement monitoring method for high-speed magnetic levitation tracks, which is based on the dual-path propagation model in wireless communications and relies on the existing high-speed magnetic levitation millimeter wave communication system. It has the advantages of good real-time performance, wide measurement range and low cost.

[0006] The technical solution adopted by the present invention is: a method for monitoring the settlement of a high-speed magnetic levitation track, the specific steps of which are as follows:

[0007] S1. During the travel of the maglev train, the onboard base station continuously transmits millimeter wave signals to the ground radio base station;

[0008] S2. Based on the dual-path propagation model, the ground radio base station receives the signal and extracts its power value. This is then correlated with the train's position on the track and a received power curve is plotted in real time. After the train has traveled the entire route, the received power curve for that route is obtained.

[0009] S3. When the train runs on the same line again, repeat steps S1 and S2 to obtain the current received power curve;

[0010] When the track settles, the relative height change between the vehicle-mounted base station and the ground radio base station causes l d and l r changes, so that P at the same point on the track sum The peaks and valleys of the received power curve change.

[0011] S4. Compare the current received power curve with the previously recorded curve to see if there is any shift in peaks or troughs. If so, proceed to step S5. Otherwise, no track settlement information is obtained.

[0012] S5. If a peak or trough is offset, the offset of the peak or trough on the curve is read, and the track settlement value is extracted based on the offset;

[0013] The offset of the peaks and troughs is in a linear relationship with the track settlement value, and the track settlement value can be extracted based on the offset.

[0014] S6. Compare the sedimentation value extracted in step S5 with a preset threshold value. When the sedimentation value exceeds the threshold value, trigger an alarm.

[0015] Furthermore, in step S1, the millimeter wave signal includes: a signal used for communication in an existing high-speed magnetic levitation millimeter wave communication system and an additional signal specifically used for monitoring track settlement.

[0016] Furthermore, in step S2, the ground radio base station receives the signal and extracts its power value as follows:

[0017] In the dual-path propagation model, the received signal consists of two parts: (1) a direct signal that reaches the receiving end through free space; and (2) a reflected signal that reaches the receiving end through ground reflection.

[0018] Among them, the received power of the direct signal P d and the received power P of the reflected signal r The expressions are as follows:

[0019]

[0020] Among them, P t represents the transmission power of the millimeter wave signal; λ represents the wavelength of the millimeter wave signal; l d and l r Represents the path length of the direct signal and the reflected signal respectively; G a G b G represents the product of the gains of the transmitting and receiving antennas in the direct path direction; c G d represents the product of the gains of the transmitting and receiving antennas in the direction of the reflection path; Γ represents the Fresnel reflection coefficient of the orbital plane.

[0021] The received signal is obtained by vector addition of the direct signal and the reflected signal at the receiving end, and its received power P sum The expression is as follows:

[0022]

[0023] in, Indicates the phase difference between the two signals; when the path difference between the direct signal and the reflected signal is an even multiple of the wavelength, the signals are superimposed in phase. The power of the received signal reaches a maximum value, forming a peak; when the path difference is an odd multiple of the wavelength, the signal is offset in reverse phase. The power of the received signal drops to a minimum, forming a trough.

[0024] Furthermore, in step S5, the track settlement value is extracted according to the offset of the peaks and troughs, as follows:

[0025] The calculation expression for extracting the settlement value Δy through the offset Δx1 of the trough is as follows:

[0026]

[0027] The calculation expression for extracting the sedimentation value Δy by the peak offset Δx2 is as follows:

[0028]

[0029] Among them, h t Represents the height of the base station transmitting the millimeter wave signal; k1 represents the k1th trough, and k2 represents the k2th peak.

[0030] The beneficial effects of the present invention are as follows: the method of the present invention first extracts the communication signal power value of the existing high-speed magnetic levitation millimeter wave communication system during the travel of the magnetic levitation train, and draws the receiving power curve of the line, and then detects the settlement of the track by analyzing the changes in the receiving power curve, and uses the offset of the peak and trough to extract the settlement value to realize track monitoring. The method of the present invention is based on the dual-path propagation model in wireless communication and relies on the existing high-speed magnetic levitation millimeter wave communication system. By utilizing the dual-path propagation model, the signal received by the receiving end is composed of the superposition of the direct signal and the reflected signal. The interference between the two signals will cause the power curve of the received signal to present alternating peaks and troughs. By analyzing the offset of these peaks and troughs, the settlement of the track can be effectively detected; utilizing the existing high-speed magnetic levitation millimeter wave communication system, track settlement monitoring can be achieved without adding additional hardware. The method of the present invention not only greatly reduces the monitoring cost, but also realizes real-time, continuous, and large-scale monitoring. It is a major breakthrough in the existing technology. The method of the present invention overcomes the problems of complex operation and poor real-time performance of existing track monitoring methods, and also solves the difficult problems of high cost and many environmental restrictions of modern track monitoring technology. It can be used as a powerful supplement to the existing monitoring system, suitable for high-speed magnetic levitation tracks, and also suitable for high-speed railways, ordinary railways, and even low-speed railways and other scenarios where track settlement monitoring is required. It has the advantages of good real-time performance, wide measurement range and low cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 The present invention is a flow chart of a method for monitoring the subsidence of a high-speed magnetic levitation track.

[0032] Figure 2 Schematic diagram of a dual-path propagation model in an embodiment of the present invention.

[0033] Figure 3 FIG. 1 is a top view of the geometric relationship between the vehicle-mounted base station and the ground radio base station in an embodiment of the present invention.

[0034] Figure 4Schematic diagram of a dual-path propagation model after track settlement in an embodiment of the present invention.

[0035] Figure 5 FIG. 4 is a graph showing a received power curve of a ground radio base station in an embodiment of the present invention.

[0036] Figure 6 Graph showing the relationship between the trough offset and the settlement value in an embodiment of the present invention. DETAILED DESCRIPTION

[0037] The method of the present invention is further described below with reference to the accompanying drawings and embodiments.

[0038] like Figure 1 As shown in the flowchart of a method for monitoring the settlement of a high-speed magnetic levitation track of the present invention, the specific steps are as follows:

[0039] S1. During the travel of the maglev train, the onboard base station continuously transmits millimeter wave signals to the ground radio base station;

[0040] In this embodiment, a 38 GHz millimeter wave signal is selected.

[0041] S2. Based on the dual-path propagation model, the ground radio base station receives the signal and extracts its power value. This is then correlated with the train's position on the track and a received power curve is plotted in real time. After the train has traveled the entire route, the received power curve for that route is obtained.

[0042] In the dual-path propagation model, the received signal consists of two parts: (1) a direct signal that reaches the receiver through free space; and (2) a reflected signal that reaches the receiver after reflecting off the ground. This model reflects the signal changes caused by interference between the ground-reflected signal and the direct signal and is suitable for areas with few reflectors, such as roads or tracks.

[0043] like Figure 2 As shown, in the dual-path propagation model, when the train-mounted base station communicates with the ground radio base station, a direct signal and a reflected signal are formed in the channel.

[0044] Among them, the received power of the direct signal P d and the received power P of the reflected signal r The expressions are as follows:

[0045]

[0046] Among them, P t represents the transmission power of the millimeter wave signal; λ represents the wavelength of the millimeter wave signal; l d and l r Represents the path length of the direct signal and the reflected signal respectively; G a G bG represents the product of the gains of the transmitting and receiving antennas in the direct path direction; c G d represents the product of the gains of the transmitting and receiving antennas in the direction of the reflection path; Γ represents the Fresnel reflection coefficient of the orbital plane.

[0047] The received signal is the vector addition of the two, so the power P of the received signal is calculated sum The expression is as follows:

[0048]

[0049] in, Represents the phase difference between two signals; Figure 3 The geometric relationship between the vehicle-mounted base station and the ground radio base station is shown in the top view. Figure 2 、 Figure 3 The geometric relationship shown in the figure is that the heights of the train-mounted base station and the ground radio base station are y t and y r , the horizontal distance between the vehicle-mounted base station and the ground radio base station is x, the vehicle-mounted base station is located at the center of the track, and the horizontal distance between the ground radio base station and the center of the track is z, then

[0050] When the path difference between the direct signal and the reflected signal is an even multiple of the wavelength, the signals are superimposed in phase. The power of the received signal reaches a maximum value, forming a peak; when the path difference is an odd multiple of the wavelength, the signal is offset in reverse phase. The power of the received signal drops to a minimum, forming a trough. The power curve of the received signal will show alternating peaks and troughs as the distance between the transmitter and the receiver changes.

[0051] In this embodiment, the train-mounted base station is used as the transmitting end and the ground radio base station is used as the receiving end. The total line length is 1000m. t =y r =3.2, z=2.5, and the millimeter wave signal frequency is 38GHz.

[0052] S3. When the train runs on the same line again, repeat steps S1 and S2 to obtain the current received power curve;

[0053] Among them, when the track sinks, such as Figure 4 As shown in Figure 1, the dual-path propagation model changes accordingly. At this time, the vehicle-mounted base station sinks with the track, while the ground base station is z meters away from the track center and does not sink. Since the height difference between the ground base station and the reflection point becomes y' r The relative height change between the vehicle-mounted base station and the ground radio base station causes l d and l r becomes ld ' and l r ', and then P d and P r becomes P d ' and P r '. This leads to P at the same point on the orbit sum The change is finally manifested as a change in the position of the peak and trough of the received power curve (shifting to the right), such as Figure 5 shown.

[0054] S4, such as Figure 5 As shown, compare the current received power curve with the previously recorded curve to observe whether there is a shift in the peaks and troughs. If so, proceed to step S5. Otherwise, no track settlement information is obtained.

[0055] By analyzing the changes in the curve, the settlement of the track can be detected.

[0056] S5. If a peak or trough is offset, the offset of the peak or trough on the curve is read, and the track settlement value is extracted based on the offset;

[0057] The offset of the peaks and valleys is linearly related to the track settlement value, and the track settlement value can be extracted based on this offset. The calculation expression for extracting the settlement value Δy from the valley offset Δx1 is as follows:

[0058]

[0059] The calculation expression for extracting the sedimentation value Δy by the peak offset Δx2 is as follows:

[0060]

[0061] Among them, h t Represents the height of the base station transmitting the millimeter wave signal; k1 represents the k1th trough, and k2 represents the k2th peak.

[0062] like Figure 6 As shown in the figure, the corresponding relationship diagram of the trough offset and the settlement value at the horizontal distance of 475m (the 5th trough) and 580m (the 4th trough) from the ground base station in this embodiment is shown. It can be seen from the figure that if the trough at 580m is offset by 5m, the track settlement value at this location is 5 / 181=0.0276m, that is, it has settled by 2.76cm; if the trough at 475m is offset by 2m, the track settlement value at this location is 2 / 148=0.0135m, which is a settlement of 1.35cm.

[0063] S6. Compare the sedimentation value extracted in step S5 with a preset threshold value. When the sedimentation value exceeds the threshold value, trigger an alarm.

[0064] The threshold is set based on actual conditions. This embodiment adopts the "High-Speed ​​Railway Design Specifications (Trial)" (TB10621-2009), which stipulates that post-construction settlement deformation of high-speed railway ballastless track subgrades must not exceed 15mm. Therefore, this embodiment uses 15mm as the threshold, and the corresponding trough offset at 580m is 0.015*181=2.715m. When the offset of this trough reaches or exceeds this value, an alarm is triggered. For the trough at 475m, the corresponding offset is 2.22m. When the offset reaches or exceeds this value, an alarm is also triggered. The same applies to peaks and troughs at other locations on the track.

[0065] In this embodiment, in step S1, the millimeter wave signal includes: a signal used for communication in an existing high-speed magnetic levitation millimeter wave communication system and an additional signal specifically used for monitoring track settlement.

[0066] In the track settlement monitoring method described in this embodiment, the train-mounted base station is the transmitting end and the ground radio base station is the receiving end. Similarly, when the ground base station is used as the transmitting end and the vehicle-mounted base station is used as the receiving end, the method of the present invention is also applicable. After the track line is built, the receiving power curve detected for the first time can be used as a reference curve. Subsequently, the receiving power curve during operation is compared with the reference curve to evaluate the settlement of the track. By using this method to compare the current receiving power curve with that of one year ago on an annual basis, annual settlement data can be obtained. Similarly, settlement conditions for other time periods such as monthly and daily can also be obtained.

[0067] In summary, the method of the present invention overcomes the problems of complex operation and poor real-time performance of existing track monitoring methods, realizes real-time and continuous monitoring, improves safety, and solves the difficult problems of high cost and many environmental restrictions of modern track monitoring technology. It does not require additional equipment, reduces costs, is not affected by environmental factors such as weather and tunnels, can be seamlessly integrated with existing communication systems without affecting normal communications, can serve as a powerful supplement to existing monitoring systems, and has a wide coverage range and is applicable to the entire line. Therefore, it is suitable for high-speed magnetic levitation tracks, and is also suitable for high-speed railways, ordinary railways, and even low-speed railways and other scenarios where track settlement monitoring is required.

[0068] Those skilled in the art will appreciate that the embodiments described herein are intended to help readers understand the principles of the present invention and should not be construed as limiting the scope of the present invention. The scope of the present invention is not limited to these specific descriptions and embodiments. Those skilled in the art may, based on the technical teachings disclosed herein, make various modifications and combinations that do not depart from the essence of the present invention, and such modifications and combinations still fall within the scope of the present invention.

Claims

1. A method for monitoring the settlement of a high-speed magnetic levitation track, comprising the following steps: S1. During the travel of the maglev train, the onboard base station continuously transmits millimeter wave signals to the ground radio base station; S2. Based on the dual-path propagation model, the ground radio base station receives the signal and extracts its power value. This is then correlated with the train's position on the track and a received power curve is plotted in real time. After the train has traveled the entire route, the received power curve for that route is obtained. The ground radio base station receives the signal and extracts its power value as follows: In the dual-path propagation model, the received signal consists of two parts: (1) the direct signal that reaches the receiving end through free space; (2) the reflected signal that reaches the receiving end after being reflected by the ground; in, The received power P of the direct signal d and the received power P of the reflected signal r The expressions are as follows: Among them, P t represents the transmission power of the millimeter wave signal; λ represents the wavelength of the millimeter wave signal; l d and l r Represents the path length of the direct signal and the reflected signal respectively; G a G b G represents the product of the gains of the transmitting and receiving antennas in the direct path direction; c G d represents the product of the gains of the transmitting and receiving antennas in the direction of the reflection path; Γ represents the Fresnel reflection coefficient of the orbital plane; The received signal is obtained by vector addition of the direct signal and the reflected signal at the receiving end, and its received power P sum The expression is as follows: in, Indicates the phase difference between the two signals; when the path difference between the direct signal and the reflected signal is an even multiple of the wavelength, the signals are superimposed in phase. The power of the received signal reaches a maximum value, forming a peak; when the path difference is an odd multiple of the wavelength, the signal is offset in reverse phase. The power of the received signal drops to a minimum, forming a trough; S3. When the train runs on the same line again, repeat steps S1 and S2 to obtain the current received power curve; When the track settles, the relative height change between the vehicle-mounted base station and the ground radio base station causes l d and l r changes, so that P at the same point on the track sum Changes occur, changing the positions of the peaks and troughs of the received power curve; S4. Compare the current received power curve with the previously recorded curve to see if there is any shift in peaks or troughs. If so, proceed to step S5. Otherwise, no track settlement information is obtained. S5. If a peak or trough is offset, the offset of the peak or trough on the curve is read, and the track settlement value is extracted based on the offset; The offset of the peaks and valleys is linearly related to the track settlement value, and the track settlement value can be extracted based on the offset; S6. Compare the sedimentation value extracted in step S5 with a preset threshold value. When the sedimentation value exceeds the threshold value, trigger an alarm.

2. The method for monitoring the subsidence of a high-speed magnetic levitation track according to claim 1, wherein: In step S1, the millimeter wave signal includes: a signal used for communication in an existing high-speed magnetic levitation millimeter wave communication system and an additional signal specifically used for monitoring track settlement.

3. The method for monitoring the subsidence of a high-speed magnetic levitation track according to claim 1, wherein: In step S5, the track settlement value is extracted based on the offset of the peaks and troughs, as follows: The calculation expression for extracting the settlement value Δy through the offset Δx1 of the trough is as follows: The calculation expression for extracting the sedimentation value Δy by the peak offset Δx2 is as follows: Among them, h t Represents the height of the base station transmitting the millimeter wave signal; k1 represents the k1th trough, and k2 represents the k2th peak.

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