Method for positioning a system for laying underground pipes based on a rotating permanent magnet magnetic beacon

Abstract

The positioning method of underground pipeline laying system based on rotary permanent magnet magnetic beacon belongs to the technical field of underground navigation positioning. The present application solves the problem of low positioning accuracy and high complexity of the existing positioning method of underground pipeline laying system. The present application analyzes the magnetic induction intensity distribution law of the rotary permanent magnet magnetic beacon, and then analyzes the propagation process of the magnetic field intensity in the metal pipeline by using the boundary theory of electromagnetic field. Based on the propagation process of the magnetic field intensity in the metal pipeline, the rotary permanent magnet magnetic beacon positioning technology is established to realize the positioning service for the underground straight pipeline equipment. Since the cumulative error is avoided, the present application improves the accuracy of the position estimation of the underground pipeline laying system, and does not need the process of stopping calibration, thereby reducing the complexity of the positioning of the underground pipeline laying system and improving the positioning efficiency, and indirectly improving the efficiency of the underground pipeline laying. The present application can be applied to underground navigation positioning.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of underground navigation positioning, and particularly relates to a positioning method for an underground pipeline laying system based on a rotating permanent magnet magnetic beacon. BACKGROUND

[0002] The rapid development of cities puts forward higher requirements for a new generation of urban infrastructure technology. Underground is one of the important environments for human life and development, and the pipeline system is an important part of the underground field. The laying of underground pipelines is an important step in the development plan of modern cities. In order to improve the speed of laying underground pipelines and avoid damage to the surface buildings during construction, the current method mostly uses a pipeline laying system composed of a shield to directly lay underground pipelines. High-precision navigation and positioning of the pipeline laying system is the key to ensuring that the pipeline is accurately excavated and laid according to the plan, and is also an important guarantee for efficient work without affecting surrounding buildings during the laying of underground pipelines. However, the existing radio positioning technology does not have the ability to continuously propagate in media such as pipelines and soil, so the radio positioning technology cannot provide high-precision positioning services for the underground pipeline laying system due to the limitation of penetration ability, and cannot meet the use requirements of the underground pipeline laying system. When a high-precision inertial measurement unit is used as the positioning system of the underground pipeline laying system, the high-precision inertial measurement unit cannot provide continuous long-time high-precision positioning services due to the cumulative error, and the cost is relatively high. The high-precision inertial measurement unit needs to be stopped for calibration after working for several hours, which increases the complexity of the pipeline laying project and reduces the efficiency of pipeline laying.

[0003] In summary, the existing positioning method for the underground pipeline laying system has the problems of low positioning accuracy and high complexity, and it is necessary to propose a new positioning method for the underground pipeline laying system. SUMMARY

[0004] The purpose of the present application is to solve the problems of low positioning accuracy and high complexity of the existing positioning method for the underground pipeline laying system, and a positioning method for the underground pipeline laying system based on a rotating permanent magnet magnetic beacon is proposed.

[0005] The technical scheme adopted by the present application to solve the above technical problems is:

[0006] A positioning method for an underground pipeline laying system based on a rotating permanent magnet magnetic beacon, the method specifically comprises the following steps:

[0007] Step 1: Start the rotating permanent magnet magnetic beacon fixed in the metal pipeline to generate a magnetic field signal, use a magnetic sensor to measure the magnetic field intensity vector at each data measurement point position, and calculate the magnetic induction intensity vector modulus value at each data measurement point position according to the magnetic field intensity vector;

[0008] Establish a sparse fingerprint database consisting of the relative positions of magnetic sensors and rotating permanent magnet magnetic beacons, as well as the vector magnitude of magnetic induction intensity.

[0009] Step 2: Calculate virtual measurement points based on the data in the sparse fingerprint database, and use the data corresponding to the virtual measurement points and the data in the sparse fingerprint database to form the final fingerprint database.

[0010] Step 3: Based on the relative distance between the magnetic sensor and the rotating permanent magnet beacon, group the data measurement points in the fingerprint database to obtain the data measurement points of each group;

[0011] Step 4: When the underground direct-lay pipeline starts working, the rotating permanent magnet beacon rotates at a preset angular rate and generates a magnetic field signal. The magnetic sensor collects the magnetic field signal at the data measurement point.

[0012] The range of relative distances between the data measurement point and the magnetic beacon is calculated based on the magnetic field signal collected by the magnetic sensor, and then the group located within the calculated range is selected from step three.

[0013] Step 5: Estimate the location of the underground pipeline laying system based on the data measurement points selected in Step 4 within the group.

[0014] Furthermore, at each data measurement point, the relative position of the magnetic sensor and the rotating permanent magnet beacon is measured using a total station. When the magnetic sensor is located at the nth data measurement point, the relative position of the magnetic sensor and the rotating permanent magnet beacon is recorded as follows:

[0015] in, θ is the relative pitch angle between the magnetic sensor and the rotating permanent magnet beacon at the nth data measurement point. n It is the relative yaw angle between the magnetic sensor and the rotating permanent magnet beacon at the nth data measurement point, r. n It is the relative distance between the magnetic sensor and the rotating permanent magnet beacon at the nth data measurement point.

[0016] Furthermore, at each data measurement point, the magnitude vector of the magnetic induction intensity vector is:

[0017]

[0018] Among them, B n It is the magnitude vector of the magnetic induction intensity measured at the location of the nth data measurement point;

[0019]

[0020] in, It is the magnitude of the magnetic flux density vector along the l-axis at the location of the nth data measurement point. It is the magnetic induction intensity vector of the l-axis measured by the magnetic sensor in the t-th period at the n-th data measurement point, where t = 1, 2, ..., T, T is the number of measurement periods, and |·| represents the modulus value.

[0021] Furthermore, the method for calculating the magnitude of the magnetic induction intensity vector is as follows:

[0022] Step 11: The angle at which the magnetic field is incident on the inner wall of the metal pipe and the magnetic field strength are respectively... H1, the angle and magnetic field strength emitted from the inner wall of the metal pipe are respectively And H2, then H1, The relationship between H2 and H2 is:

[0023]

[0024] Where μ1 is the relative permeability of air, and μ2 is the relative permeability of the pipe material. θ0 is the relative pitch angle between the magnetic sensor and the position of the magnetic field incident on the inner wall of the metal pipe, and θ1 is the relative yaw angle between the magnetic sensor and the position of the magnetic field incident on the inner wall of the metal pipe. θ1 is the relative pitch angle between the magnetic sensor and the position where the magnetic field exits from the inner wall of the metal pipe, and θ2 is the relative yaw angle between the magnetic sensor and the position where the magnetic field exits from the inner wall of the metal pipe.

[0025] Then the magnetic field strength H2 and the exit angle for:

[0026]

[0027] After the magnetic field propagates in the metal pipe, the angle at which the magnetic field is incident on the outer wall of the metal pipe and the magnetic field strength are respectively And H3, the exit angle and magnetic field strength of the magnetic field transmitted from the outer wall of the metal pipe to the soil are respectively and H4, H3, The relationship between H4 and H4 is:

[0028]

[0029] in, θ0 is the relative pitch angle between the magnetic sensor and the position of the magnetic field incident on the outer wall of the metal pipe, and θ3 is the relative yaw angle between the magnetic sensor and the position of the magnetic field incident on the outer wall of the metal pipe. θ4 is the relative pitch angle between the magnetic sensor and the position where the magnetic field exits from the outer wall of the metal pipe, and θ4 is the relative yaw angle between the magnetic sensor and the position where the magnetic field exits from the outer wall of the metal pipe.

[0030] but H4 is:

[0031]

[0032] Where μ3 is the relative magnetic permeability of the soil material;

[0033] Steps one and two, will Equivalent to If the relative distance r1 between the magnetic sensor and the position where the magnetic field penetrates the air and reaches the inner wall of the metal pipe is equivalent to the relative distance r2 between the magnetic sensor and the position where the magnetic field exits the inner wall of the metal pipe material, then...

[0034]

[0035] in,

[0036] Let the thickness of the metal pipe be h. When the magnetic field penetrates the metal pipe material and reaches the outer wall of the metal pipe, the magnetic field strength H3 is expressed as:

[0037]

[0038] Where M represents the equivalent magnetic moment of the rotating permanent magnet beacon. A function representing relative orientation;

[0039] The relative distance r2 is equivalent to the relative distance r3 between the magnetic sensor and the point where the magnetic field penetrates the metal pipe material to reach the soil incident position. The relationship between the two is:

[0040]

[0041] in,

[0042] Then the magnetic field strength vector H at the measurement point p for:

[0043]

[0044] Where d represents the height difference between the exit position of the outer wall and the data measurement point when the magnetic field is incident from the outer wall of the metal pipe into the soil;

[0045] The magnitude B of the magnetic field strength vector at the data measurement point p for:

[0046]

[0047] Furthermore, the specific process of step two is as follows:

[0048] Step 2: Select four nearest neighboring data measurement points as a group, and denote the four data measurement points within the group as RP. a+i,b+j Given i = 0, 1 and j = 0, 1, calculate the relative positions of the magnetic sensor and the rotating permanent magnet beacon at each data measurement point within the group, without considering the propagation of the magnetic field across the medium, based on the magnitude of the magnetic induction intensity vector.

[0049] The true value of the relative position between the magnetic sensor and the rotating permanent magnet beacon at each data measurement point within the group is recorded as follows: And calculate the true value of the relative position. Calculated values ​​with relative position deviation value

[0050]

[0051] Step 22: Perform polynomial fitting on the deviation value and the true value of the relative position to obtain the fitting result;

[0052] Step 23: For a virtual measurement point located within a square area composed of four data measurement points, obtain the deviation value corresponding to the virtual measurement point based on the actual relative position of the virtual measurement point with the rotating permanent magnet beacon and the fitting result of Step 22.

[0053] And the theoretical relative position is obtained based on the actual relative position and the deviation value:

[0054]

[0055] in, This is the theoretical relative position of the virtual measurement point and the rotating permanent magnet magnetic beacon. V(p,q) is the actual relative position between the virtual measurement point and the rotating permanent magnet beacon, and V(p,q) is the deviation value corresponding to the virtual measurement point.

[0056] Step 24: Based on the calculated theoretical relative position, obtain the magnitude of the magnetic induction intensity vector measured at the virtual measurement point;

[0057] Step 25: Repeat steps 23 and 24 to obtain the true relative positions of multiple virtual measurement points and the magnitude of the magnetic induction intensity vector, respectively.

[0058] The final fingerprint database is constructed by combining the data corresponding to all the obtained virtual measurement points with the data in the sparse fingerprint database.

[0059] Furthermore, without considering the propagation of the magnetic field across the medium, the method for calculating the relative position of the magnetic sensor and the rotating permanent magnet beacon at the data measurement point is as follows:

[0060]

[0061] Among them, |B x | is the magnitude of the magnetic flux density vector along the x-axis, |B y | is the magnitude of the magnetic flux density vector along the y-axis, B x B is the magnetic flux density vector along the x-axis. y It is the magnetic flux density vector along the y-axis. The values ​​represent the relative pitch angle between the rotating permanent magnet beacon and the measurement point, without considering the propagation of the magnetic field across the medium; θ represents the relative yaw angle between the rotating permanent magnet beacon and the measurement point, without considering the propagation of the magnetic field across the medium; r represents the relative distance between the rotating permanent magnet beacon and the measurement point, without considering the propagation of the magnetic field across the medium; and the superscript T represents transpose. It is a function of the relative orientation of the l-axis.

[0062] Furthermore, the specific process of step three is as follows:

[0063] Data points with a relative distance greater than 0 and less than 1m are grouped into a group, denoted as the [number]th group. Group;

[0064] Data measurement points with a relative distance greater than or equal to 1m and less than 2m are grouped into a group, denoted as the [number]th group. Group;

[0065] This process continues until all data measurement points have been grouped.

[0066] Further, the step involves calculating the interval of relative distance between the data measurement point and the magnetic beacon based on the magnetic field signal collected by the magnetic sensor, and then selecting groups located within the calculated interval from step three; specifically:

[0067]

[0068] Among them, B' x and B' y L represents the equivalent x-axis and y-axis magnetic flux density vector magnitudes of the rotating permanent magnet magnetic beacon at the location of the underground pipeline laying system to be positioned. U L is the upper bound of the relative distance between the data measurement point and the magnetic beacon. D It is the lower bound of the relative distance between the data measurement point and the magnetic beacon. Represents the relative distances corresponding to the selected groups. The conditions that need to be met.

[0069] Furthermore, the specific process of step five is as follows:

[0070] Step 51: Denote the set of data measurement points within the selected groups in Step 4 as [the set of data measurement points]. Let RP be the data measurement point in row a, column b, and layer c. a,b,c The magnetic flux density vector magnitudes are respectively and

[0071] Calculate data measurement points RP a,b,c Error value between the data and the data at the location to be located:

[0072]

[0073] Where, ε a,b,c It is the data measurement point RP a,b,c The corresponding error value;

[0074] Similarly, calculate the set The error value corresponding to each data measurement point in the dataset;

[0075] Step 52, then based on ε a,b,c Calculate data measurement points RP a,b,c weight w a,b,c Similarly, calculate the set After assigning weights to each data measurement point, the data measurement point with the highest weight is selected.

[0076] Step 53: Measure the data points Data measurement points and data measurement points The virtual measurement points enclosed within the formed area serve as data measurement points for precise matching;

[0077] Step 54: Calculate the error value between the data used for precise matching of each measurement point and the data at the location to be located, and then calculate the weight of the corresponding measurement point based on the error value:

[0078]

[0079] in, Data measurement points The corresponding error value, Data measurement points The weights;

[0080] Then calculate the mean of the weights of all data measurement points used for exact matching. Select weights greater than The relative position of the selected m-th data measurement point is denoted as . The weight of the selected m-th data measurement point is denoted as...

[0081] Step 55: Normalize the weights of the data measurement points selected in Step 54:

[0082]

[0083] in, M0 is the normalized weight of the m-th data measurement point, and M0 is the number of data measurement points selected in step five-four.

[0084] Then according to and Calculate the location of the underground pipeline system:

[0085]

[0086] in, It is the location of the underground pipeline laying system.

[0087] Furthermore, the specific process of step five two is as follows:

[0088]

[0089] intermediate variable σ a,b,c and Represented as:

[0090]

[0091] Then select the largest weight w ★ :

[0092]

[0093] The data measurement point corresponding to the largest weight is denoted as...

[0094] The beneficial effects of this invention are:

[0095] This invention analyzes the magnetic induction intensity distribution of a rotating permanent magnet beacon based on Ampere's circuital law and the magnetic dipole model. It then uses electromagnetic field boundary theory to analyze the propagation process of the magnetic field intensity in metal pipes and establishes a rotating permanent magnet beacon positioning technology based on this propagation process, providing positioning services for underground pipeline installations. By avoiding accumulated errors, this invention improves the accuracy of location estimation for underground pipeline laying systems. Furthermore, it eliminates the need for downtime calibration, reducing the complexity of positioning underground pipeline systems and increasing positioning efficiency, indirectly improving the efficiency of underground pipeline laying as well. Attached Figure Description

[0096] Figure 1This is a flowchart of a positioning method for an underground pipeline laying system based on a rotating permanent magnet magnetic beacon, according to the present invention.

[0097] Figure 2 This is a schematic diagram of a rotating permanent magnet structure;

[0098] The angular velocity of the magnetic beacon is set to ω1, and the frequency of the magnetic beacon generation is... Low-frequency magnetic field signals;

[0099] Figure 3 This is a schematic diagram showing the relative positional relationship between the rotating permanent magnet beacon and the measurement point;

[0100] Figure 4 A schematic diagram illustrating the propagation of the magnetic field generated by a rotating permanent magnet within a pipe.

[0101] Figure 5 This is a schematic diagram of the low-frequency magnetic field propagation process across a medium.

[0102] In the diagram, S ps S represents the point where the magnetic field exits from the outer wall of the pipe into the soil. ap This represents the point of entry of the magnetic field from the air to the inner wall of the pipe;

[0103] Figure 6 This is a schematic diagram illustrating the relationship between data collection points and virtual collection points for computation.

[0104] Figure 7 This is a comparison chart of the positioning accuracy of the method of the present invention with other methods;

[0105] Figure 8 This is a comparison chart of the computation time of the method of the present invention with other methods. Detailed Implementation

[0106] Specific Implementation Method 1: Combination Figure 1 This embodiment describes a positioning method for an underground pipeline laying system based on a rotating permanent magnet magnetic beacon. The method specifically includes the following steps:

[0107] Step 1: Assemble the rotating permanent magnet beacon in the underground metal pipe. A schematic diagram of the rotating permanent magnet structure is shown below. Figure 2 As shown, a rotating permanent magnet beacon fixed inside a metal pipe is activated to generate an extremely low frequency magnetic field signal (extremely low frequency refers to a frequency range of 3 to 30 Hz). The magnetic sensor is used to measure the magnetic field strength vector at each data measurement point, and the magnetic induction intensity vector magnitude at each data measurement point is calculated based on the magnetic field strength vector.

[0108] Establish a sparse fingerprint database consisting of the relative positions of magnetic sensors and rotating permanent magnet magnetic beacons, as well as the vector magnitude of magnetic induction intensity.

[0109] Step 2: Calculate virtual measurement points based on the data in the sparse fingerprint database, and use the data corresponding to the virtual measurement points and the data in the sparse fingerprint database to form the final fingerprint database.

[0110] Step 3: Based on the relative distance between the magnetic sensor and the rotating permanent magnet beacon, group the data measurement points in the fingerprint database to obtain the data measurement points of each group;

[0111] Step 4: When the underground direct-lay pipeline starts working, the rotating permanent magnet magnetic beacon rotates at a preset angular rate and generates an extremely low frequency magnetic field signal. The magnetic sensor collects the magnetic field signal at the data measurement point.

[0112] The range of relative distances between the data measurement point and the magnetic beacon is calculated based on the magnetic field signal collected by the magnetic sensor, and then the group located within the calculated range is selected from step three.

[0113] Step 5: Estimate the location of the underground pipeline laying system based on the data measurement points selected in Step 4 within the group.

[0114] A rotating permanent magnet magnetic beacon is installed inside a metal pipe at the location of the underground pipeline laying system. The position of the rotating permanent magnet magnetic beacon, calculated by this invention, is the location of the underground pipeline laying system.

[0115] Specific Implementation Method Two: This implementation method differs from Specific Implementation Method One in that the relative positions of the magnetic sensor and the rotating permanent magnet beacon at each data measurement point are measured using a total station. When the magnetic sensor is located at the nth data measurement point, the relative position of the magnetic sensor and the rotating permanent magnet beacon is recorded as...

[0116] in, θ is the relative pitch angle between the magnetic sensor and the rotating permanent magnet beacon at the nth data measurement point. n It is the relative yaw angle between the magnetic sensor and the rotating permanent magnet beacon at the nth data measurement point, r. n It is the relative distance between the magnetic sensor and the rotating permanent magnet beacon at the nth data measurement point.

[0117] The other steps and parameters are the same as in Specific Implementation Method 1.

[0118] In this invention, the measuring instruments that can be used to measure the relative position of the magnetic sensor and the rotating permanent magnet beacon include, but are not limited to, a total station.

[0119] Specific Implementation Method Three: This implementation method differs from Specific Implementation Method One or Two in that, at each data measurement point location, the magnitude vector of the magnetic induction intensity vector is:

[0120]

[0121] Among them, B n It is the magnitude vector of the magnetic induction intensity measured at the location of the nth data measurement point;

[0122]

[0123] in, It is the magnitude of the magnetic flux density vector along the l-axis at the location of the nth data measurement point. It is the magnetic induction intensity vector of the l-axis measured by the magnetic sensor in the t-th period at the n-th data measurement point, where t = 1, 2, ..., T, T is the number of measurement periods, and |·| represents the modulus value.

[0124] Other steps and parameters are the same as in specific implementation method one or two.

[0125] Specific Implementation Method Four: This implementation method differs from Specific Implementation Methods One to Three in that the method for calculating the magnitude of the magnetic induction intensity vector is as follows:

[0126] Based on the motion characteristics of the rotating permanent magnet beacon, the rotating permanent magnet beacon can be equivalent to two orthogonal current-carrying solenoids with the same magnetic moment and frequency. The magnetic field distribution of the rotating permanent magnet beacon is modeled using the Biotsafar and magnetic dipole equivalent models.

[0127] The equivalent magnetic moments of the rotating permanent magnet magnetic beacon along the x-axis and y-axis are as follows:

[0128]

[0129] Where ω is the angular velocity of the rotating permanent magnet beacon, φ is the initial rotation angle of the rotating permanent magnet beacon, and M represents the equivalent magnetic moment of the rotating permanent magnet beacon. x M is the equivalent magnetic moment along the x-axis. y M is the equivalent magnetic moment along the y-axis. z It is the equivalent magnetic moment along the z-axis;

[0130] According to such Figure 3 The relative positional relationship between the rotating permanent magnet beacon and the data measurement point (i.e., the magnetic sensor measurement point) shown, and the propagation law of the magnetic induction intensity vector in non-ferromagnetic media such as air, can be expressed as:

[0131]

[0132] Among them, B x B is the magnetic flux density vector along the x-axis. y y is the magnetic flux density vector along the y-axis, μ0 is the permeability of air, and r represents the relative distance between the rotating permanent magnet beacon and the data measurement point. θ is the relative pitch angle between the rotating permanent magnet beacon and the data measurement point, and θ is the relative yaw angle between the rotating permanent magnet beacon and the data measurement point.

[0133] The relationship between magnetic induction intensity and magnetic field strength can be expressed as:

[0134]

[0135] Underground pipelines are mainly made of materials such as steel. A schematic diagram illustrating the propagation of the magnetic field generated by the rotating permanent magnet within the pipeline is shown below. Figure 4 As shown, the medium that the magnetic field needs to pass through during propagation is mainly air-metal-air (soil). Since the magnetic permeability of soil and air is basically the same, the propagation process of the extremely low frequency magnetic field in soil can be regarded as propagation in air. The magnetic field signal changes when it penetrates ferromagnetic metal materials. At the same time, due to the large difference in parameters such as conductivity ε and magnetic permeability μ between metal and air, the signal attenuation rate and propagation path will change during continuous propagation through media such as pipes and air (soil).

[0136] The propagation process of low-frequency magnetic fields in pipes is analyzed by considering the boundary conditions of the static magnetic field. A schematic diagram of the cross-medium propagation process of extremely low-frequency magnetic fields is shown below. Figure 5 As shown, according to the quasi-static magnetic field boundary conditions:

[0137] Step 11: The angle at which the magnetic field is incident on the inner wall of the metal pipe and the magnetic field strength are respectively... H1, the angle and magnetic field strength emitted from the inner wall of the metal pipe are respectively And H2, then H1, The relationship between H2 and H2 is:

[0138]

[0139] Where μ1 is the relative permeability of air, and μ2 is the relative permeability of the pipe material. θ0 is the relative pitch angle between the magnetic sensor and the position of the magnetic field incident on the inner wall of the metal pipe, and θ1 is the relative yaw angle between the magnetic sensor and the position of the magnetic field incident on the inner wall of the metal pipe. θ1 is the relative pitch angle between the magnetic sensor and the position where the magnetic field exits from the inner wall of the metal pipe, and θ2 is the relative yaw angle between the magnetic sensor and the position where the magnetic field exits from the inner wall of the metal pipe.

[0140] Then the magnetic field strength H2 and the exit angle for:

[0141]

[0142] After the magnetic field propagates in the metal pipe, the angle at which the magnetic field is incident on the outer wall of the metal pipe and the magnetic field strength are respectively And H3, the exit angle and magnetic field strength of the magnetic field transmitted from the outer wall of the metal pipe to the soil (similar to air) are respectively and H4, H3, The relationship between H4 and H4 is:

[0143]

[0144] in, θ0 is the relative pitch angle between the magnetic sensor and the position of the magnetic field incident on the outer wall of the metal pipe, and θ3 is the relative yaw angle between the magnetic sensor and the position of the magnetic field incident on the outer wall of the metal pipe. θ4 is the relative pitch angle between the magnetic sensor and the position where the magnetic field exits from the outer wall of the metal pipe, and θ4 is the relative yaw angle between the magnetic sensor and the position where the magnetic field exits from the outer wall of the metal pipe.

[0145] but H4 is:

[0146]

[0147] Where μ3 is the relative magnetic permeability of the soil material;

[0148] The material of the cast metal pipe is a homogeneous medium. The metal pipe is hollow and has a certain thickness. The propagation process of a low-frequency magnetic field inside the metal pipe is similar to its propagation process in a homogeneous medium such as air. Since the thickness h of the metal pipe is much smaller than the relative distance r between the transmitter and the sensor, the propagation process of the magnetic field vector inside the pipe can be approximated as a straight line. Because the attenuation process of the magnetic field strength changes after it enters a metal pipe, a schematic diagram of the magnetic field propagation process through media such as air, pipe, and soil is shown below. Figure 5 As shown.

[0149] Steps one and two, will Equivalent to The relative distance r1 between the magnetic sensor and the position where the magnetic field penetrates the air to reach the inner wall of the metal pipe is equivalent to the relative distance r2 between the magnetic sensor and the position where the magnetic field penetrates the metal pipe material to reach the exit position on the inner wall. Here, we consider that the inner wall of the metal pipe has a certain thickness, so the inner wall of the pipe has two surfaces: one facing the air inside the pipe, and the other facing the pipe material.

[0150]

[0151] in,

[0152] Let the thickness of the metal pipe be h. When the magnetic field penetrates the metal pipe material and reaches the outer wall of the metal pipe, the magnetic field strength H3 is expressed as:

[0153]

[0154] Where M represents the equivalent magnetic moment of the rotating permanent magnet beacon. A function representing relative orientation;

[0155]

[0156] When a magnetic field penetrates the outer wall of a metal pipe, it is a process of transformation from a metallic medium to a soil medium. During this process, the relative distance r2 can be equivalently represented as the relative distance r3 between the magnetic sensor and the point where the magnetic field penetrates the metal pipe material and reaches the soil incident point. The relationship between the two is as follows:

[0157]

[0158] in,

[0159] Then the magnetic field strength vector H at the measurement point p for:

[0160]

[0161] Where d represents the height difference between the exit position of the outer wall and the data measurement point when the magnetic field is incident from the outer wall of the metal pipe into the soil;

[0162] The magnitude B of the magnetic field strength vector at the data measurement point p for:

[0163]

[0164] The other steps and parameters are the same as those in one of the specific implementation methods one to three.

[0165] Specific Implementation Method Five: This implementation method differs from Specific Implementation Methods One to Four in that the specific process of step two is as follows:

[0166] Step Two, 1. Figure 6 As shown, four nearest neighboring data measurement points are selected as a group (the data measurement points in the sparse fingerprint database are a series of points spatially distributed in rows, columns, and layers, with a spacing of 1 between adjacent points in each row, a spacing of 1 between adjacent points in each column, and a spacing of 1 between adjacent layers). The four data measurement points in the group are denoted as RP.a+i,b+j Given i = 0, 1 and j = 0, 1, calculate the relative positions of the magnetic sensor and the rotating permanent magnet beacon at each data measurement point within the group, without considering the propagation of the magnetic field across the medium, based on the magnitude of the magnetic induction intensity vector.

[0167] The true value of the relative position between the magnetic sensor and the rotating permanent magnet beacon at each data measurement point within the group is recorded as follows: And calculate the true value of the relative position. Calculated values ​​with relative position deviation value

[0168]

[0169] Step 22: Perform polynomial fitting on the deviation value and the true value of the relative position to obtain the fitting result;

[0170] Step 23: For a virtual measurement point located within a square area composed of four data measurement points, obtain the deviation value corresponding to the virtual measurement point based on the actual relative position of the virtual measurement point with the rotating permanent magnet beacon and the fitting result of Step 22.

[0171] And the theoretical relative position is obtained based on the actual relative position and the deviation value:

[0172]

[0173] in, This is the theoretical relative position of the virtual measurement point and the rotating permanent magnet magnetic beacon. V(p,q) is the actual relative position between the virtual measurement point and the rotating permanent magnet beacon, and V(p,q) is the deviation value corresponding to the virtual measurement point.

[0174] Step 24: Based on the calculated theoretical relative position, that is, substituting the theoretical relative position calculated in Step 23 into Formula (14), the magnitude of the magnetic induction intensity vector measured at the virtual measurement point is obtained.

[0175] Step 25: Repeat steps 23 and 24 to obtain the true relative positions of multiple virtual measurement points and the magnitude of the magnetic induction intensity vector, respectively.

[0176] The final fingerprint database is constructed by combining the data corresponding to all the obtained virtual measurement points with the data in the sparse fingerprint database.

[0177] The other steps and parameters are the same as those in one of the specific implementation methods one to four.

[0178] First, in step two of this invention, multiple sets of data points can be selected. Second, multiple virtual fingerprint points can be generated for each set of data points. This allows virtual fingerprint points to be calculated based on the data corresponding to the previously collected equally spaced measurement points, thereby expanding the fingerprint database. This avoids the process of collecting magnetic field data and relative positions for each measurement point individually, reducing the complexity of the algorithm.

[0179] Specific Implementation Method Six: This implementation method differs from Specific Implementation Methods One to Five in that, without considering the propagation of the magnetic field across the medium, the method for calculating the relative position of the magnetic sensor and the rotating permanent magnet beacon at the data measurement point is as follows:

[0180]

[0181] Among them, |B x | is the magnitude of the magnetic flux density vector along the x-axis, |B y | is the magnitude of the magnetic flux density vector along the y-axis, B x B is the magnetic flux density vector along the x-axis. y It is the magnetic flux density vector along the y-axis. The values ​​represent the relative pitch angle between the rotating permanent magnet beacon and the measurement point, without considering the propagation of the magnetic field across the medium; θ represents the relative yaw angle between the rotating permanent magnet beacon and the measurement point, without considering the propagation of the magnetic field across the medium; r represents the relative distance between the rotating permanent magnet beacon and the measurement point, without considering the propagation of the magnetic field across the medium; and the superscript T represents transpose. It is a function of the relative orientation of the l-axis.

[0182] The other steps and parameters are the same as those in one of the specific implementation methods one to five.

[0183] Specific Implementation Method Seven: This implementation method differs from Specific Implementation Methods One through Six in that the specific process of step three is as follows:

[0184] Data points with a relative distance greater than 0 and less than 1m are grouped into a group, denoted as the [number]th group. Group;

[0185] Data measurement points with a relative distance greater than or equal to 1m and less than 2m are grouped into a group, denoted as the [number]th group. Group;

[0186] This process continues until all data measurement points have been grouped.

[0187] The other steps and parameters are the same as those in one of the specific implementation methods one to six.

[0188] Specific Implementation Method Eight: This implementation method differs from Specific Implementation Methods One to Seven in that, in calculating the interval of the relative distance between the data measurement point and the magnetic beacon based on the magnetic field signal collected by the magnetic sensor, and then selecting the group located within the calculated interval from step Three; specifically:

[0189]

[0190] Among them, B' x and B' y L represents the equivalent x-axis and y-axis magnetic flux density vector magnitudes of the rotating permanent magnet magnetic beacon at the location of the underground pipeline laying system to be positioned. U L is the upper bound of the relative distance between the data measurement point and the magnetic beacon. D It is the lower bound of the relative distance between the data measurement point and the magnetic beacon. Represents the relative distances corresponding to the selected groups. The conditions to be met are as follows: (If the relative distances of all measurement points in a group are within the interval between the upper and lower bounds, then that group is selected. Similarly, all groups that meet the conditions are selected.)

[0191] The other steps and parameters are the same as those in any of the specific implementation methods one to seven.

[0192] Specific Implementation Method Nine: This implementation method differs from Specific Implementation Methods One to Eight in that the specific process of step five is as follows:

[0193] Step 51: Denote the set of data measurement points within the selected groups in Step 4 as [the set of data measurement points]. Let RP be the data measurement point in row a, column b, and layer c. a,b,c The magnetic flux density vector magnitudes are respectively and

[0194] Calculate data measurement points RP a,b,c Error value between the data and the data at the location to be located:

[0195]

[0196] Where, ε a,b,c It is the data measurement point RP a,b,c The corresponding error value;

[0197] Similarly, calculate the set The error value corresponding to each data measurement point in the dataset;

[0198] Step 52, then based on ε a,b,c Calculate data measurement points RP a,b,c weight wa,b,c Similarly, calculate the set After assigning weights to each data measurement point, the data measurement point with the highest weight is selected.

[0199] Step 53: Measure the data points Data measurement points and data measurement points The virtual measurement points enclosed within the formed area serve as data measurement points for precise matching;

[0200] Step 54: Calculate the error value between the data used for precise matching of each measurement point and the data at the location to be located, and then calculate the weight of the corresponding measurement point based on the error value:

[0201]

[0202] in, Data measurement points The corresponding error value, Data measurement points The weights;

[0203] Then calculate the mean of the weights of all data measurement points used for exact matching. Select weights greater than The relative position of the selected m-th data measurement point is denoted as . The weight of the selected m-th data measurement point is denoted as...

[0204] Step 55: Normalize the weights of the data measurement points selected in Step 54:

[0205]

[0206] in, M0 is the normalized weight of the m-th data measurement point, and M0 is the number of data measurement points selected in step five-four.

[0207] Then according to and Calculate the location of the underground pipeline system:

[0208]

[0209] in, It is the location of the underground pipeline laying system.

[0210] The other steps and parameters are the same as those in one of the specific implementation methods one to eight.

[0211] Specific Implementation Method Ten: This implementation method differs from Specific Implementation Methods One to Nine in that the specific process of step five-two is as follows:

[0212]

[0213] intermediate variable σ a,b,c and Represented as:

[0214]

[0215] Then select the largest weight w ★ :

[0216]

[0217] The data measurement point corresponding to the largest weight is denoted as...

[0218] The other steps and parameters are the same as those in any of the specific implementation methods one to nine.

[0219] Simulation section

[0220] Simulation verification was performed on a rotating permanent magnet magnetic beacon positioning algorithm for underground direct-lay pipeline applications. The proposed method was compared with a probability-based fingerprint matching algorithm, a fingerprint matching method without virtual measurement points, a method that does not consider cluster analysis, a method that does not consider cluster analysis and does not add virtual fingerprint measurement points, and a method based on magnetic induction intensity and feature vector magnitude that does not consider the influence of metal pipelines. The pipeline thickness was set to 7.5 cm, the magnetic sensor sampling frequency to 1000 Hz, and the environment contained a constant interference magnetic field with a mean of 40000 nT and white noise with an amplitude of 10 nT. The relative permeability of air and soil was set to 1, and the relative permeability of the metal pipeline was set to 900. Figure 7 As shown, simulation results demonstrate that, compared to probability-based fingerprint matching algorithms, fingerprint matching methods without virtual measurement points, methods that do not consider cluster analysis and do not add virtual fingerprint measurement points, and methods based on magnetic induction intensity and feature vector magnitude that do not consider the influence of metal pipes, this method improves the accuracy of pipe positioning. Figure 8 As shown, compared with the method that does not consider cluster analysis, the cluster analysis reduces the time for location calculation.

[0221] The above examples of the present invention are merely illustrative of the computational model and process of the present invention, and are not intended to limit the implementation of the present invention. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is impossible to exhaustively list all possible implementations here. Any obvious variations or modifications derived from the technical solutions of the present invention are still within the scope of protection of the present invention.

Claims

1. A positioning method for an underground pipeline laying system based on a rotating permanent magnet magnetic beacon, characterized in that, The method specifically includes the following steps: Step 1: Activate the rotating permanent magnet beacon fixed inside the metal pipe to generate a magnetic field signal. Use a magnetic sensor to measure the magnetic field strength vector at each data measurement point and calculate the magnitude of the magnetic induction intensity vector at each data measurement point based on the magnetic field strength vector. Establish a sparse fingerprint database consisting of the relative positions of magnetic sensors and rotating permanent magnet magnetic beacons, as well as the vector magnitude of magnetic induction intensity. Step 2: Calculate virtual measurement points based on the data in the sparse fingerprint database, and use the data corresponding to the virtual measurement points and the data in the sparse fingerprint database to form the final fingerprint database. Step 3: Based on the relative distance between the magnetic sensor and the rotating permanent magnet beacon, group the data measurement points in the fingerprint database to obtain the data measurement points of each group; Step 4: When the underground direct-lay pipeline starts working, the rotating permanent magnet beacon rotates at a preset angular rate and generates a magnetic field signal. The magnetic sensor collects the magnetic field signal at the data measurement point. The range of relative distances between the data measurement point and the magnetic beacon is calculated based on the magnetic field signal collected by the magnetic sensor, and then the group located within the calculated range is selected from step three. Step 5: Estimate the location of the underground pipeline laying system based on the data measurement points selected in Step 4 within the group.

2. The positioning method for an underground pipeline laying system based on a rotating permanent magnet magnetic beacon according to claim 1, characterized in that, At each data measurement point, the relative position of the magnetic sensor and the rotating permanent magnet beacon is measured using a total station. When the magnetic sensor is located at the nth data measurement point, the relative position of the magnetic sensor and the rotating permanent magnet beacon is recorded as follows: in, θ is the relative pitch angle between the magnetic sensor and the rotating permanent magnet beacon at the nth data measurement point. n It is the relative yaw angle between the magnetic sensor and the rotating permanent magnet beacon at the nth data measurement point, r. n It is the relative distance between the magnetic sensor and the rotating permanent magnet beacon at the nth data measurement point.

3. The positioning method for an underground pipeline laying system based on a rotating permanent magnet magnetic beacon according to claim 2, characterized in that, At each data measurement point, the magnitude vector of the magnetic induction intensity vector is: Among them, B n It is the magnitude vector of the magnetic induction intensity measured at the location of the nth data measurement point; in, It is the magnitude of the magnetic flux density vector along the l-axis at the location of the nth data measurement point. It is the magnetic induction intensity vector of the l-axis measured by the magnetic sensor in the t-th period at the n-th data measurement point, where t = 1, 2, ..., T, T is the number of measurement periods, and |·| represents the modulus value.

4. The positioning method for an underground pipeline laying system based on a rotating permanent magnet magnetic beacon according to claim 3, characterized in that, The method for calculating the magnitude of the magnetic induction intensity vector is as follows: Step 11: The angle at which the magnetic field is incident on the inner wall of the metal pipe and the magnetic field strength are respectively... H1, the angle and magnetic field strength emitted from the inner wall of the metal pipe are respectively And H2, then H1, The relationship between H2 and H2 is: Where μ1 is the relative permeability of air, and μ2 is the relative permeability of the pipe material. θ0 is the relative pitch angle between the magnetic sensor and the position of the magnetic field incident on the inner wall of the metal pipe, and θ1 is the relative yaw angle between the magnetic sensor and the position of the magnetic field incident on the inner wall of the metal pipe. θ1 is the relative pitch angle between the magnetic sensor and the position where the magnetic field exits from the inner wall of the metal pipe, and θ2 is the relative yaw angle between the magnetic sensor and the position where the magnetic field exits from the inner wall of the metal pipe. Then the magnetic field strength H2 and the exit angle for: After the magnetic field propagates in the metal pipe, the angle at which the magnetic field is incident on the outer wall of the metal pipe and the magnetic field strength are respectively And H3, the exit angle and magnetic field strength of the magnetic field transmitted from the outer wall of the metal pipe to the soil are respectively and H4, H3 The relationship between H4 and H4 is: in, θ0 is the relative pitch angle between the magnetic sensor and the position of the magnetic field incident on the outer wall of the metal pipe, and θ3 is the relative yaw angle between the magnetic sensor and the position of the magnetic field incident on the outer wall of the metal pipe. θ4 is the relative pitch angle between the magnetic sensor and the position where the magnetic field exits from the outer wall of the metal pipe, and θ4 is the relative yaw angle between the magnetic sensor and the position where the magnetic field exits from the outer wall of the metal pipe. but H4 is: Where μ3 is the relative magnetic permeability of the soil material; Steps one and two, will Equivalent to If the relative distance r1 between the magnetic sensor and the position where the magnetic field penetrates the air and reaches the inner wall of the metal pipe is equivalent to the relative distance r2 between the magnetic sensor and the position where the magnetic field exits the inner wall of the metal pipe material, then... in, Let the thickness of the metal pipe be h. When the magnetic field penetrates the metal pipe material and reaches the outer wall of the metal pipe, the magnetic field strength H3 is expressed as: Where M represents the equivalent magnetic moment of the rotating permanent magnet beacon. A function representing relative orientation; The relative distance r2 is equivalent to the relative distance r3 between the magnetic sensor and the point where the magnetic field penetrates the metal pipe material to reach the soil incident position. The relationship between the two is: in, Then the magnetic field strength vector H at the measurement point p for: Where d represents the height difference between the exit position of the outer wall and the data measurement point when the magnetic field is incident from the outer wall of the metal pipe into the soil; The magnitude B of the magnetic field strength vector at the data measurement point p for:

5. The positioning method for an underground pipeline laying system based on a rotating permanent magnet magnetic beacon according to claim 4, characterized in that, The specific process of step two is as follows: Step 2: Select four nearest neighboring data measurement points as a group, and denote the four data measurement points within the group as RP. a+i,b+j Given i = 0, 1 and j = 0, 1, calculate the relative positions of the magnetic sensor and the rotating permanent magnet beacon at each data measurement point within the group, without considering the propagation of the magnetic field across the medium, based on the magnitude of the magnetic induction intensity vector. The true value of the relative position between the magnetic sensor and the rotating permanent magnet beacon at each data measurement point within the group is recorded as follows: And calculate the true value of the relative position. Calculated values ​​with relative position deviation value Step 22: Perform polynomial fitting on the deviation value and the true value of the relative position to obtain the fitting result; Step 23: For a virtual measurement point located within a square area composed of four data measurement points, obtain the deviation value corresponding to the virtual measurement point based on the actual relative position of the virtual measurement point with the rotating permanent magnet beacon and the fitting result of Step 22. And the theoretical relative position is obtained based on the actual relative position and the deviation value: in, This is the theoretical relative position of the virtual measurement point and the rotating permanent magnet magnetic beacon. V(p,q) is the actual relative position between the virtual measurement point and the rotating permanent magnet beacon, and V(p,q) is the deviation value corresponding to the virtual measurement point. Step 24: Based on the calculated theoretical relative position, obtain the magnitude of the magnetic induction intensity vector measured at the virtual measurement point; Step 25: Repeat steps 23 and 24 to obtain the true relative positions of multiple virtual measurement points and the magnitude of the magnetic induction intensity vector, respectively. The final fingerprint database is constructed by combining the data corresponding to all the obtained virtual measurement points with the data in the sparse fingerprint database.

6. The positioning method for an underground pipeline laying system based on a rotating permanent magnet magnetic beacon according to claim 5, characterized in that, The method for calculating the relative position of the magnetic sensor and the rotating permanent magnet beacon at the data measurement point, without considering the propagation of the magnetic field across the medium, is as follows: Among them, |B x | is the magnitude of the magnetic flux density vector along the x-axis, |B y | is the magnitude of the magnetic flux density vector along the y-axis, B x B is the magnetic flux density vector along the x-axis. y It is the magnetic flux density vector along the y-axis. The values ​​represent the relative pitch angle between the rotating permanent magnet beacon and the measurement point, without considering the propagation of the magnetic field across the medium; θ represents the relative yaw angle between the rotating permanent magnet beacon and the measurement point, without considering the propagation of the magnetic field across the medium; r represents the relative distance between the rotating permanent magnet beacon and the measurement point, without considering the propagation of the magnetic field across the medium; and the superscript T represents transpose. It is a function of the relative orientation of the l-axis.

7. The positioning method for an underground pipeline laying system based on a rotating permanent magnet magnetic beacon according to claim 6, characterized in that, The specific process of step three is as follows: Data points with a relative distance greater than 0 and less than 1m are grouped into a group, denoted as the [number]th group. Group; Data measurement points with a relative distance greater than or equal to 1m and less than 2m are grouped into a group, denoted as the [number]th group. Group; This process continues until all data measurement points have been grouped.

8. The positioning method for an underground pipeline laying system based on a rotating permanent magnet magnetic beacon according to claim 7, characterized in that, The process involves calculating the relative distance interval between the data measurement point and the magnetic beacon based on the magnetic field signal collected by the magnetic sensor, and then selecting groups located within the calculated interval from step three; specifically: Among them, B' x and B' y L represents the equivalent x-axis and y-axis magnetic flux density vector magnitudes of the rotating permanent magnet magnetic beacon at the location of the underground pipeline laying system to be positioned. U L is the upper bound of the relative distance between the data measurement point and the magnetic beacon. D It is the lower bound of the relative distance between the data measurement point and the magnetic beacon. Represents the relative distances corresponding to the selected groups. The conditions that need to be met.

9. The positioning method for an underground pipeline laying system based on a rotating permanent magnet magnetic beacon according to claim 8, characterized in that, The specific process of step five is as follows: Step 51: Denote the set of data measurement points within the selected groups in Step 4 as [the set of data measurement points]. Let RP be the data measurement point in row a, column b, and layer c. a,b,c The magnetic flux density vector magnitudes are respectively and Calculate data measurement points RP a,b,c Error value between the data and the data at the location to be located: Where, ε a,b,c It is the data measurement point RP a,b,c The corresponding error value; Similarly, calculate the set The error value corresponding to each data measurement point in the dataset; Step 52, then based on ε a,b,c Calculate data measurement points RP a,b,c weight w a,b,c Similarly, calculate the set After assigning weights to each data measurement point, the data measurement point with the highest weight is selected. Step 53: Measure the data points Data measurement points and data measurement points The virtual measurement points enclosed within the formed area serve as data measurement points for precise matching; Step 54: Calculate the error value between the data used for precise matching of each measurement point and the data at the location to be located, and then calculate the weight of the corresponding measurement point based on the error value: in, Data measurement points The corresponding error value, Data measurement points The weights; Then calculate the mean of the weights of all data measurement points used for exact matching. Select weights greater than The relative position of the selected m-th data measurement point is denoted as . The weight of the selected m-th data measurement point is denoted as... Step 55: Normalize the weights of the data measurement points selected in Step 54: in, M0 is the normalized weight of the m-th data measurement point, and M0 is the number of data measurement points selected in step five-four. Then according to and Calculate the location of the underground pipeline system: in, It is the location of the underground pipeline laying system.

10. The positioning method for an underground pipeline laying system based on a rotating permanent magnet magnetic beacon according to claim 9, characterized in that, The specific process of step 52 is as follows: intermediate variable σ a,b,c and Represented as: Then select the largest weight w ＊ : The data measurement point corresponding to the largest weight is denoted as...

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