Positioning method based on magnetic induction communication, processing device, positioning system

Abstract

The application belongs to the technical field of target positioning, and discloses a positioning method based on magnetic induction communication, a processing device and a positioning system. The positioning method comprises the following steps: acquiring ideal magnetic induction receiving signal power and calculating shadow fading loss power based on a magnetic induction link model; calculating a shadow fading weight matrix, wherein if a position point is located in a near-field coupling interval range, the shadow fading weight is not 0, otherwise, the shadow fading weight is 0, a shadow blocking coefficient is constructed, a blocking probability distribution matrix is constructed, and a shadow fading metric matrix is constructed, so as to minimize the deviation between the shadow fading loss and the shadow fading metric as the target of the inversion inverse problem, the blocking probability distribution matrix is solved, and a position point with the maximum blocking probability is estimated as the position of a target object; wherein N is a preset positive integer, and L is the total number of magnetic induction links. The application does not need to divide finite elements and iteratively calculate, so that the calculation amount is greatly reduced, and the accuracy of object position estimation is ensured.

Description

Technical Field

[0001] This invention belongs to the field of target positioning technology, and more specifically, relates to a positioning method, processing device, and positioning system based on magnetic induction communication. Background Technology

[0002] With the rapid growth of positioning needs in various scenarios, traditional communication and positioning technologies based on sound waves or electromagnetic waves are facing severe challenges in complex environments. Taking the underground environment as an example, the high conductivity, large fluctuations in water content, and dense and complex metal structures of underground media lead to strong absorption, strong scattering, and severe multipath effects, resulting in unstable links, limited coverage, and a sharp decline in positioning accuracy.

[0003] Magnetic induction (MI) technology relies on low-frequency magnetic induction near-field coupling to achieve information transmission and environmental perception. With its four core advantages—low path loss, strong penetration, insensitivity to electromagnetic shielding and multipath propagation, and stable channel response—it has become an important research direction in underground communication and positioning. However, in real-world non-uniform environments (such as aquifer fluctuations, densely packed tunnel structures, and ore body metal anomalies), magnetic field propagation is easily disturbed. Specifically, the magnetic permeability of rock strata... Spatial differences, conductivity Dielectric constant Uneven distribution of water content and eddy current effects generated by metal structures can both lead to uneven distribution of magnetic field energy in space, ultimately manifesting as sharp fluctuations in received signal power and creating communication "blind spots." These signal amplitude fluctuations induced by both the environment and the target can be summarized as the "shadow fading" effect. The "shadow fading" effect directly reduces positioning accuracy and weakens the reliability of communication systems, significantly limiting its applicability to high-reliability scenarios such as mining operations, pipeline inspection, and underground emergency rescue.

[0004] Most existing link models for magnetic induction communication and positioning still assume an ideal homogeneous medium, modeling only through the equivalent of an ideal magnetic dipole and the coupling relationship in a homogeneous medium space. This simplification fails to accurately characterize the spatial non-uniformity of the actual underground environment and its statistical impact on received signal strength (RSSI), and also lacks explicit modeling and computable description of the link shadowing effect. The direct consequence is a significant discrepancy between the communication link budget and the positioning error assessment results, making it difficult to support reliable decisions for engineering application deployment.

[0005] Therefore, providing a positioning method that can achieve accurate positioning is a technical problem that urgently needs to be solved. Summary of the Invention

[0006] In view of the above-mentioned defects or improvement needs of the existing technology, the present invention provides a positioning method, processing device and positioning system based on magnetic induction communication, the purpose of which is to achieve accurate positioning.

[0007] To achieve the above objectives, this invention is proposed.

[0008] According to a first aspect of the present invention, a positioning method based on magnetic induction communication is provided, comprising: Based on the magnetic induction link model of the transmitting and receiving antennas, the ideal magnetic induction received signal power of the receiving coil when there is no target object on the magnetic induction link is obtained. ; Based on the actual magnetic induction received signal power of the receiving coil Calculate the power loss due to shadow fading introduced by the target object in each magnetic induction link. Integrating the shadowing losses of L magnetic induction links yields the shadowing loss matrix. L represents the total number of magnetic induction links; The positioning area is divided into N location points, where N is a preset positive integer, and an occlusion probability distribution matrix is ​​constructed for the N location points. , The decision variables are: For each magnetic induction link, calculate the shadow fading weights at N locations to obtain the shadow fading weight matrix for L magnetic induction links. ,matrix Each element in Indicates the first The first magnetic induction link The shadow fading weight at the i-th location point, if the i-th location point... The location point is located at the th The near-field coupling range of the magnetic induction link is then Otherwise, it is 0. This refers to the shadow occlusion coefficient caused by a target object within the near-field coupling range of the magnetic induction link, reflecting the degree to which the target object occludes the magnetic induction link. The transmission coefficient of the magnetic field penetrating the target object; construct the shadow fading metric matrix for L magnetic induction links. ; With the shadow fading loss matrix With the shadow fading metric matrix Minimizing the deviation between the two is the objective of the inverse problem; the occlusion probability distribution matrix is ​​then solved. Then, the position of the target object is determined by the location with the highest probability of occlusion.

[0009] According to a second aspect of the present invention, a positioning information processing device based on magnetic induction communication is provided, including a memory and a processor, wherein the memory stores a computer program, and the processor executes the computer program to implement the steps of the method described above.

[0010] According to a third aspect of the present invention, a positioning system based on magnetic induction communication is provided, comprising: A magnetic induction transmitting antenna is used to transmit magnetic induction signals; A magnetic induction receiving antenna is used to receive magnetic induction signals and store the magnetic induction signal data. The positioning information processing device described above is used to estimate the position of a target object based on magnetic induction signal data.

[0011] In summary, compared with the prior art, the technical solutions conceived in this invention have the following main advantages: In this invention, a magnetic induction link model is first constructed based on the transmit and receive antenna topology and environmental information. The received signal power when no target object is present in the link is obtained through the link model. Then, the shadowing fading loss introduced when a target object is present in the link is considered. Subsequently, a position estimation inversion problem is constructed, with the objective of minimizing the deviation between the shadowing fading loss of all links and the shadowing fading metric of all links to solve for the target object's position. This invention, through in-depth analysis of the magnetic induction transmission link under shadowing fading conditions, can characterize the shadowing fading characteristics affecting the channel. Only the received signal power information is needed to estimate the spatial position of the target object. Simultaneously, this invention eliminates the need for finite element analysis and iterative calculations, significantly reducing computational load while ensuring the accuracy of object position estimation. Attached Figure Description

[0012] Figure 1 A schematic diagram of a positioning method and system based on magnetic induction communication provided as an example of the present invention; Figure 2 A flowchart illustrating the steps of a positioning method based on magnetic induction communication provided in an embodiment of the present invention; Figure 3 A schematic diagram of the equivalent circuit of the transmitting coil and receiving coil in an environment facing shadow fading, provided for an example of the present invention; Figure 4 A Cartesian coordinate system schematic diagram of the magnetic induction link established by the transmitting coil and the receiving coil, provided as an example of the present invention; Figure 5 A schematic diagram of a three-layer dielectric model of a transmitting coil, a shadow-occluding object, and a receiving coil in an environment facing shadow fading, provided for an example of the present invention; Figure 6This is a schematic diagram of the change of the received power of the theoretical magnetic induction communication signal with distance in the simulation of the example of the present invention; wherein (a) is a schematic diagram of the received signal power when there is no shadow occlusion object in the magnetic induction link in the simulation and theory; (b) is a schematic diagram of the received signal power when there is shadow occlusion object in the magnetic induction link in the simulation and theory. Figure 7 This is a schematic diagram illustrating the theoretical magnetic induction communication positioning performance simulated in an example of the present invention. Detailed Implementation

[0013] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention. Furthermore, the technical features involved in the various embodiments of this invention described below can be combined with each other as long as they do not conflict with each other.

[0014] like Figure 1 The diagram shows a positioning system based on magnetic induction communication. The magnetic induction communication link (for shadow fading) consists of a transmitting coil, a receiving coil, and a target object. The target object is located in the near field of the magnetic induction link formed by the transmitting and receiving coils. When the transmitting coil transmits information to the receiving coil, the target object will block the signal propagation, thereby introducing shadow fading and ultimately leading to a decrease in communication quality.

[0015] like Figure 2 The diagram shows a flowchart of the positioning method based on magnetic induction communication in an embodiment of the present invention, which includes the following steps.

[0016] S1. Based on the magnetic induction link model of the transmitting and receiving antennas, obtain the ideal magnetic induction received signal power of the receiving coil when there is no target object on the magnetic induction link. .

[0017] The purpose of this step is to determine the magnetic induction signal power of the receiving coil under ideal conditions when there are no target objects (i.e., obstructions).

[0018] Specifically, the transceiver antenna includes a transmitting antenna and a receiving antenna. The transmitting antenna has a transmitting coil, and the receiving antenna has a receiving coil. Link modeling is performed based on the actual deployment of the transmitting and receiving coils, such as... Figure 3 The diagram shows a schematic of a magnetic induction link model, which includes a series equivalent circuit for both the transmitting and receiving coils. Each side's series equivalent circuit specifically includes series-connected coil loss resistors. Coil inductance and coil resonant capacitor .

[0019] Define the input voltage of the transmitting coil as The input current is The operating frequency is The corresponding angular frequency is .

[0020] Transmitting coil: The radius of the transmitting coil is wire diameter is Number of turns In its equivalent circuit, the coil loss resistance of the transmitting coil is... The coil inductance is The resonant capacitance of the coil is The impedance of this coil consists of resistance, inductive reactance, and capacitive reactance, and is expressed as resistance. Plus the immune component Subtract capacitive part ,in Angular frequency, It is the imaginary unit.

[0021] Receiving coil: The radius of the receiving coil is wire diameter is Number of turns The equivalent circuit of the receiving coil includes a resistor. ,inductance Resonant capacitor and load resistance Its impedance is determined by the resistance. , immune part Capacitive part and load resistance composition.

[0022] Coil loss resistance.

[0023] In the series equivalent circuit of each coil, its coil loss resistance consists of two parts: AC loss resistance and AC loss resistance. and radiation loss resistance .

[0024] AC loss resistor The resistance is related to the geometry of the coil, the properties of the wire material, and the operating frequency; it depends on the length of the coil. Conductivity of coil wire Skin depth of coil conductor at operating frequency Wire diameter of the coil conductor Factors such as skin depth It represents the depth to which current flows on the surface of the conductor. It decreases as the operating frequency increases. The AC loss resistance is determined by the combined effect of these factors and varies with frequency.

[0025] Radiation loss resistance The impedance of this resistor relative to the dielectric material surrounding the coil conductor. The propagation constant of the coil wire and the cross-sectional area of ​​the conductor Related. Radiation loss resistance is the energy loss caused by the electromagnetic waves radiated into the surrounding medium when the coil is working, and it is usually more significant under high-frequency operating conditions.

[0026] In the equivalent series resistance of the transmitting coil, the total resistance of the transmitting coil is... Equal to its AC loss resistance and radiation loss resistance The sum, that is: .

[0027] Similarly, the total resistance of the receiving coil Due to its AC loss resistance and radiation loss resistance The sum of the components is composed of: .

[0028] Coil inductance.

[0029] In the series equivalent circuit of each coil, the coil inductance includes the self-inductance of a single-turn coil. Mutual inductance between different turns , Indicates the first The self-inductance of the coil express Turns of coil and the first Mutual inductance between coils.

[0030] Self-inductance of a single-turn coil The self-inductance of a single-turn coil consists of two parts. The first part is related to the radius of the coil. and wire diameter The relevant parameters are mainly derived by calculating the geometric dimensions of the coil. The second part relates to the operating frequency. and the conductivity of the coil wire Related. This section reflects the effect of frequency and conductivity on coil self-inductance. Specifically, the self-inductance of a single-turn coil can be influenced by the coil's conductivity. magnetic permeability It is expressed in terms of the geometric properties of the conductor (such as radius and diameter) and takes into account the effect of frequency on the current distribution in the conductor.

[0031] Mutual inductance between multi-turn coils Mutual inductance describes the degree of magnetic coupling between different turns, and depends on the geometry of the coil and the distance between the turns. And the propagation constant of the surrounding medium. The magnitude of mutual inductance is determined by the radii of the two different turns. and The combination of these factors determines the mutual inductance and is closely related to the spacing between the two turns and the propagation characteristics of the electromagnetic field. Mutual inductance also involves an integral operator based on elliptic integrals, which reflects the degree of coupling between the coils.

[0032] Equivalent series inductance of the transmitting coil The total inductance of the transmitting coil is the sum of the self-inductance of each individual turn, plus the sum of the mutual inductance between different turns. The self-inductance of each individual turn is related to its radius, wire diameter, and operating frequency, while the mutual inductance takes into account the relative positions and electromagnetic coupling between the turns. The total inductance includes the contribution of each turn as well as the coupling effects between turns, forming the overall inductance of the transmitting coil.

[0033] Equivalent series inductance of the receiving coil Similar to the transmitting coil, the total inductance of the receiving coil consists of the sum of the self-inductance of all individual turns and the sum of the mutual inductance between different turns. The inductance of the receiving coil is also affected by the coil geometry, operating frequency, and inter-turn coupling. The inductance of each individual turn and the mutual inductance between turns together determine the overall inductance of the receiving coil.

[0034] Coil resonant capacitor.

[0035] In the series equivalent circuit of each coil, its resonant capacitance is used to make the reactance of the coil zero, achieving a resonant state. The resonant capacitance of the transmitting and receiving coils is related to their inductance values; specifically, the capacitance is the reciprocal of the product of the resonant inductance and the square of the resonant operating angular frequency. Therefore, the resonant capacitance of the transmitting and receiving coils is determined by their target resonant frequencies and their corresponding inductances, respectively.

[0036] Based on Kirchhoff's voltage law, the system of equations for the magnetic induction link is as follows: (1); (2); In the formula, The output voltage of the receiving coil, To receive the output current of the coil, The intrinsic impedance of the transmitting coil is... This is the intrinsic impedance of the receiving coil.

[0037] The magnetic induction link established by the transmitting coil and the receiving coil is as follows: Figure 4 As shown, the origin is the center of the transmitting coil. oThe plane where the transmitting coil is located is xoy A plane that is perpendicular to the plane containing the transmitting coil and passes through o The straight line from point is z Establish a rectangular coordinate system along the axes. The magnetic induction link parameters are: (The spatial position of the receiving coil center in this rectangular coordinate system is given by...) Link length Link pitch angle and link azimuth .

[0038] The transmitting and receiving coils are equivalent to magnetic dipoles. The transmitting coil is calculated under input voltage... The induced electromotive force on the receiving coil .

[0039] Specifically, the magnitude of the equivalent magnetic dipole moment of the transmitting coil is: (3); In the formula, It is the number of turns of the transmitting coil. It is the cross-sectional area of ​​the transmitting coil. It is the input current of the transmitting coil. This is the unit normal vector of the transmitting coil cross section.

[0040] The equivalent magnetic dipole moment of the transmitting coil along the magnetic induction link The transmitted magnetic field components are as follows: (4); (5); (6); (7); In the formula, Let be the amplitude of the equivalent magnetic dipole moment of the transmitting coil. unit normal vector The components on the x-axis, y-axis, and z-axis respectively. These are the magnetic field strength components of the receiving coil center on the x-axis, y-axis, and z-axis, respectively. The vector of the resultant magnetic field strength at the center of the receiving coil. is the propagation constant of the medium in which the link is located.

[0041] Based on Faraday's law of electromagnetic induction, the induced electromotive force on the receiving coil is: (8); In the formula, Permeability, This represents the cross-sectional area of ​​the receiving coil.

[0042] Combining the above formulas (1) to (8), the magnetic induction received signal power of the receiving coil can be calculated. ,as follows: (9); In the formula, for conjugate, for . conjugate.

[0043] S2, Based on the actual magnetic induction received signal power of the receiving coil Calculate the power loss due to shadow fading introduced by the target object in each magnetic induction link. Integrating the shadowing losses of L magnetic induction links yields the shadowing loss matrix. L represents the total number of magnetic induction links.

[0044] If the location area is deployed One magnetic induction antenna node, this Each magnetic induction node operates in half-duplex mode, with one node emitting a magnetic induction signal and the remaining nodes... Each node receives a signal, and the entire positioning area can be formed. A magnetic induction link collects all The actual magnetic induction signal power corresponding to each of the L links can be used to construct the shadow fading loss matrix for the L magnetic induction links. Shadow fading loss matrix The L elements in the equation correspond one-to-one with the shadow fading loss power of the L magnetic induction links.

[0045] S3. Divide the positioning area into N location points, where N is a preset positive integer, and construct an occlusion probability distribution matrix for the N location points. , The decision variables are: For each magnetic induction link, calculate the shadow fading weights at N locations to obtain the shadow fading weight matrix for L magnetic induction links. ,matrix Each element in Indicates the first The first magnetic induction link The shadow fading weight at the i-th location point, if the i-th location point... The location point is located at the th The near-field coupling range of the magnetic induction link is then Otherwise, it is 0. This refers to the shadow occlusion coefficient caused by a target object within the near-field coupling range of the magnetic induction link, reflecting the degree to which the target object occludes the magnetic induction link. The transmission coefficient of the magnetic field penetrating the target object; construct the shadow fading metric matrix for L magnetic induction links. .

[0046] The following describes how to construct a shadow fading metric matrix. The process.

[0047] This is the occlusion probability distribution matrix. The positioning area is divided into N location points, and an occlusion probability distribution matrix is ​​constructed for these N location points. ,matrix The N elements in the array correspond one-to-one with the occlusion probabilities of the N location points. Let be the variable to be decided, and the location with the highest occlusion probability be the location of the occluder. Therefore, when the solution is obtained... Then, the location of the obstruction can be determined, thus achieving localization.

[0048] Given a shadow fading weight matrix with L distinct links, each with a different topology, it is necessary to calculate the shadow fading weights for N locations on each link, forming a matrix. A shadow fading weight matrix of dimension 1. The rule for calculating the shadow fading weight is: if the 1st dimension is 1... The location point is located at the th The near-field coupling range of the magnetic induction link is then Otherwise, it is 0, which can be represented in the following form: .

[0049] Because of the coordinates of each location point Since the shadow fading weights are known, the shadow fading weight matrix can be directly calculated for each location. It can be calculated directly.

[0050] Choose any link and take a location point with an obstruction as an example to illustrate how to determine its shadow fading weight.

[0051] Specifically, we can first determine the first Fresnel region of the magnetic induction link, and then obtain the first Fresnel region in... Length on the surface And in Length on the surface The near-field coupling range of the magnetic induction link can be considered as the length of the magnetic induction link. With the major axis of the ellipsoid as the length For the ellipsoid in The minor axis on the surface, with length For the ellipsoid in Within the ellipsoidal region bounded by the minor axes on the surface, it can be represented as: ; ; ; In the formula, The coordinates of the obstruction are: Link length exist Projected length on the surface Link length exist Projected length on the surface The wavelength of the magnetic field reflects the propagation scale of electromagnetic waves in space. Its magnitude determines the geometric range of the first Fresnel zone, which in turn affects the effective near-field region of the magnetic induction link.

[0052] Within the defined near-field range, the presence of an occluder blocks the magnetic induction signal, thus causing shadow fading. Furthermore, the shadow effect varies depending on the object's scale. To accurately characterize the shadow fading caused by the target object's scale, the position of the occluder in the coordinate system is defined as... Given a cross-sectional dimension of s, to address the shadowing effect of occluders of different locations and scales, we first solve for their maximum occlusion coefficient. Then normalize this coefficient to the occlusion coefficient generated at the midpoint of the link. The final shadow occlusion coefficient caused by the target object can be expressed as: ; Among them, the maximum occlusion coefficient It can be set to 1, representing the occlusion coefficient generated by the midpoint of the link. for: ; In the formula, This is the length of the first Fresnel zone.

[0053] In addition, it is necessary to calculate the transmission coefficient of the magnetic field through the obstruction. Specifically, the magnetic induction link can be divided into three media regions according to the obstruction, such as... Figure 5 As shown, the region from the transmitter to the obstruction is the first medium region, the obstruction itself is the second medium region, and the region from the obstruction to the receiver is the third medium region. Based on this, a three-layer heterogeneous medium model is constructed, and the generalized magnetic induction transmission coefficient can be expressed as: This model considers the reflection and transmission coefficients between different media, and the reflection and transmission characteristics between each pair of media can be described by the physical parameters of the media.

[0054] According to Fresnel's law, the transmission coefficient of a magnetic field through an obstruction can be calculated using the following formula: ; In the formula, is the transmission coefficient of the magnetic field from the first medium region to the second medium region. is the transmission coefficient of the magnetic field from the second medium region into the third medium region. The magnetic field reflection coefficient from the second medium region to the first medium region. The magnetic field reflection coefficient from the second medium region to the third medium region. Let be the propagation constant of the magnetic field in the obstruction.

[0055] Among them, corresponding to any two adjacent media, they are defined as medium a and medium b; The magnetic field reflection coefficient from medium a to medium b is Based on Fresnel's law, its calculation formula is: ; The magnetic field projection coefficient from medium a into medium b is: Based on Fresnel's law, its calculation formula is: ; In the formula, Let be the permeabilities of dielectrics a and b, respectively. are the magnetic field propagation constants in medium a and medium b, respectively.

[0056] Based on the above process, the transmission coefficient of the magnetic field penetrating the target object is determined. and the shadow occlusion coefficient at the corresponding location point of the corresponding link. This allows us to calculate the shadow fading weight at the corresponding location point under that link. Integrating the shadow fading weights of L links and N location points yields the shadow fading weight matrix. .

[0057] The shadow fading weight matrix obtained from the above calculations and the constructed occlusion probability distribution matrix to be decided A shadow fading metric matrix can be constructed. . The L elements represent the total shadow fading value of the L different links.

[0058] In fact, based on the above analysis, combined with the ideal magnetic induction received signal power when the magnetic induction link is unobstructed, And the shadow fading coefficient introduced when there are obstructions on the link; shadow occlusion coefficient. Transmission coefficient of magnetic field penetrating the barrier We can obtain the expression for the received signal power when there is an obstruction in the magnetic induction link: .

[0059] The essence of the subsequent inversion algorithm is to make the actual loss as close as possible to the calculated loss based on the above expression.

[0060] S4, using the shadow fading loss matrix With the shadow fading metric matrix Minimizing the deviation between the two is the objective of the inverse problem; the occlusion probability distribution matrix is ​​then solved. Then, the position of the target object is determined by the location with the highest probability of occlusion.

[0061] Specifically, this step involves solving the estimated location of the occluding obstacle by constructing an inverse problem.

[0062] With the shadow fading loss matrix With the shadow fading metric matrix The objective of the inverse problem is to minimize the deviation between the two values, solve for the occlusion probability distribution matrix, and determine the location of the occluder. This objective can be expressed as: ; ; In the formula, Represents the index occlusion probability distribution matrix The position point corresponding to the maximum value in the value. The location of the determined obstruction.

[0063] Example 2 The present invention also relates to a positioning information processing device based on magnetic induction communication, including a memory and a processor. The memory stores a computer program, and the processor executes the computer program to implement the steps of the method described above.

[0064] The device can be a desktop computer, laptop, handheld computer, or cloud server, etc. The processor can be a Central Processing Unit (CPU), or other general-purpose processors, digital signal processors (DSPs), application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. The memory can be used to store computer programs and / or modules. The processor implements various functions of the electronic device by running or executing the computer programs and / or modules stored in the memory, and by accessing data stored in the memory.

[0065] Example 3 The present invention also relates to a positioning system based on magnetic induction communication, comprising: A magnetic induction transmitting antenna is used to transmit magnetic induction signals; A magnetic induction receiving antenna is used to receive magnetic induction signals and store the magnetic induction signal data. The positioning information processing device described above is used to estimate the location of obstructions based on magnetic induction signal data.

[0066] The feasibility of this invention will be verified through experiments below.

[0067] Figure 6 This is a schematic diagram illustrating the variation of the received power of the theoretical magnetic induction communication signal with distance in the simulation of an example of this invention; where (a) is a schematic diagram of the received signal power when there are no shadowed objects in the magnetic induction link in the simulation and theory; (b) is a schematic diagram of the received signal power when there are shadowed objects in the magnetic induction link in the simulation and theory. It can be seen that when there are no shadowed objects in the link, the error between the simulation results and the theoretical results does not exceed 3 dB; after introducing shadowed objects, the maximum error is less than 1.2 dB. The theoretical results and simulation results have good consistency, providing reliable theoretical model support and high-precision data verification for achieving object inversion positioning. Figure 7 The diagram shows the theoretical magnetic induction communication positioning performance simulation of an example of the present invention. It can be seen that the positioning error of the magnetic induction positioning method proposed in this invention does not exceed 0.3m when the CDF reaches 0.9, achieving a positioning accuracy at the decimeter level.

[0068] In summary, the analytical channel model for magnetic induction links with target objects proposed in this invention does not require a large amount of CPU resources or excessive computation time, providing a simple channel modeling method while maintaining accuracy. Furthermore, the near-field region partitioning method for magnetic induction links with target objects, and the characterization of shadow fading coefficients introduced by target objects of different scales and characteristics, proposed in this invention, can comprehensively describe the characteristics of magnetic induction links under shadow fading, thereby achieving accurate target object localization. Its localization advantage is particularly significant in complex environments such as underground environments.

[0069] The technical features of the above embodiments can be combined arbitrarily. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as the combination of these technical features does not contradict each other, it should be considered within the scope of this specification. It should be noted that the terms "in one embodiment," "for example," and "again" are intended to illustrate the present invention and are not intended to limit the present invention.

[0070] The above embodiments merely illustrate several implementation methods of the present invention, and their descriptions are relatively specific and detailed, but they should not be construed as limiting the scope of the patent application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention.

Claims

1. A positioning method based on magnetic induction communication, characterized in that, include: Based on the magnetic induction link model of the transmitting and receiving antennas, the ideal magnetic induction received signal power of the receiving coil when there is no target object on the magnetic induction link is obtained. ; Based on the actual magnetic induction received signal power of the receiving coil Calculate the power loss due to shadow fading introduced by the target object in each magnetic induction link. Integrating the shadowing losses of L magnetic induction links yields the shadowing loss matrix. L represents the total number of magnetic induction links; The positioning area is divided into N location points, where N is a preset positive integer, and an occlusion probability distribution matrix is ​​constructed for the N location points. , The decision variables are: For each magnetic induction link, calculate the shadow fading weights at N locations to obtain the shadow fading weight matrix for L magnetic induction links. ,matrix Each element in Indicates the first The first magnetic induction link The shadow fading weight at the i-th location point, if the i-th location point... The location point is located at the th The near-field coupling range of the magnetic induction link is then Otherwise, it is 0. This refers to the shadow occlusion coefficient caused by a target object within the near-field coupling range of the magnetic induction link, reflecting the degree to which the target object occludes the magnetic induction link. The transmission coefficient of the magnetic field penetrating the target object; construct the shadow fading metric matrix for L magnetic induction links. ; With the shadow fading loss matrix With the shadow fading metric matrix Minimizing the deviation between the two is the objective of the inverse problem; the occlusion probability distribution matrix is ​​then solved. Then, the position of the target object is determined by the location with the highest probability of occlusion.

2. The positioning method based on magnetic induction communication as described in claim 1, characterized in that, For any magnetic induction link: the near-field coupling range of the magnetic induction link is determined based on the first Fresnel zone of the magnetic induction link, wherein the near-field coupling range of the magnetic induction link is based on the length of the magnetic induction link. With the major axis of the ellipsoid as the length For the ellipsoid in The minor axis on the surface, with length For the ellipsoid in Within the ellipsoidal region bounded by the minor axes on the surface; where, length For the first Fresnel zone of the magnetic induction link in Length on the surface; length For the first Fresnel zone of the magnetic induction link in Length on the surface; The surface is perpendicular to it in the positioning space coordinate system. The plane of the axis; The surface is perpendicular to it in the positioning space coordinate system. The plane of the axis.

3. The positioning method based on magnetic induction communication as described in claim 2, characterized in that, Coordinates The occlusion coefficient of the target object at that location The calculation formula is: ； In the formula, The maximum occlusion factor, This is the occlusion coefficient generated at the midpoint of the link.

4. The positioning method based on magnetic induction communication as described in claim 2, characterized in that, No. The first magnetic induction link Shadow fading weight at each location point The calculation formula is: ； In the formula, For the first The coordinates of each location point.

5. The positioning method based on magnetic induction communication as described in claim 1, characterized in that, The inverse problem is: ； ； In the formula, The set adjustment coefficient, Represents the index occlusion probability distribution matrix The position point corresponding to the maximum value in the value. This refers to the location of the target object.

6. The positioning method based on magnetic induction communication as described in claim 1, characterized in that, The magnetic induction link model of the transmitting and receiving antennas includes the series equivalent circuit of the transmitting coil and the series equivalent circuit of the receiving coil. In the series equivalent circuit at each end: it includes coil loss resistance, coil inductance and coil resonant capacitance, and its coil loss resistance includes the sum of its AC loss resistance and radiation loss resistance. Its coil inductance includes the sum of the self-inductance of all single-turn coils and the sum of the mutual inductance between different turns.

7. The positioning method based on magnetic induction communication as described in claim 1, characterized in that, Divide the positioning area into N location points, including dividing the positioning area into N uniformly distributed location points using a grid division method.

8. The positioning method based on magnetic induction communication as described in claim 1, characterized in that, The transmission coefficient of a magnetic field penetrating a target object The calculation method is as follows: The magnetic induction link is divided into three media regions according to the target object to obtain a three-layer heterogeneous media model. The first media region is from the transmitter to the target object, the second media region is the target object itself, and the third media region is from the target object to the receiver. Based on the aforementioned three-layer heterogeneous medium model, the transmission coefficient of a magnetic field penetrating a target object can be calculated according to Fresnel's law. .

9. A positioning information processing device based on magnetic induction communication, characterized in that, The method includes a memory and a processor, the memory storing a computer program, characterized in that the processor executes the computer program to implement the steps of the method as described in any one of claims 1 to 8.

10. A positioning system based on magnetic induction communication, characterized in that, include: A magnetic induction transmitting antenna is used to transmit magnetic induction signals; A magnetic induction receiving antenna is used to receive magnetic induction signals and store the magnetic induction signal data. The positioning information processing device as described in claim 9 is used to estimate the position of a target object based on magnetic induction signal data.

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