A magnetic beacon and cross-domain magnetic positioning method based on a swinging permanent magnet type mechanical antenna array

Abstract

The present invention discloses a magnetic beacon and a cross-domain magnetic positioning method based on a swinging permanent magnet type mechanical antenna array, belonging to the technical field of magnetic positioning. The architecture of the magnetic beacon includes a signal generator module, a power amplifier module and a magnetic beacon antenna. The magnetic beacon antenna is composed of four swinging permanent magnet type mechanical antenna arrays with orthogonal cross structures. Each swinging permanent magnet type mechanical antenna with an orthogonal cross structure is composed of two groups of swinging permanent magnet type mechanical antenna units with different resonant frequencies. The positioning method of the present invention includes constructing a magnetic field distribution model of the magnetic beacon; obtaining the magnetic field information of the detection point based on a three-axis magnetic sensor; determining a fitness function, and using a particle swarm algorithm to solve the position of the magnetic source. The magnetic beacon proposed by the present invention has a compact structure and low power consumption. At the same time, the pose of the magnetic beacon can be solved by using a single three-axis magnetic sensor for one measurement at a single position, greatly simplifying the operation and contributing to the actual magnetic positioning application.

Description

Technical Field

[0001] The present invention belongs to the technical field of magnetic positioning, and particularly relates to a magnetic beacon and a cross-domain magnetic positioning method based on a swinging permanent magnet type mechanical antenna array. Background Art

[0002] In complex environments such as underground or underwater, traditional positioning methods based on radio frequency electromagnetic waves or the Earth's steady-state magnetic field are difficult to achieve high-precision positioning, while positioning methods based on artificial low-frequency alternating magnetic fields can provide high-precision positioning services in these scenarios. Low-frequency electromagnetic fields / electromagnetic waves have low attenuation in high-loss media such as land and seawater and can propagate well across domains. Since the wavelength of ultra-low-frequency electromagnetic fields (30 - 300 Hz) reaches 10 6 ~10 7 meters, it is difficult for traditional coils to generate strong low-frequency magnetic fields in a small volume, resulting in a relatively short effective positioning distance. A mechanical antenna is a brand-new low-frequency electromagnetic wave transmitting antenna that directly uses the mechanical motion of magnetic dipoles or electric dipoles to generate time-varying electromagnetic fields, usually operating below kHz, and can generate strong radiation magnetic fields in a small volume. Currently, permanent magnets are generally used as magnetic sources to generate magnetic field signals with the same frequency as the movement of the permanent magnets. In existing positioning systems based on rotating permanent magnets, due to the symmetry of the rotational movement of the permanent magnets, the magnetic field is evenly symmetrically distributed in the movement plane, which makes it impossible to fully obtain the attitude information of the magnetic beacon. At the same time, motors are used for driving, and the structure volume of the beacon magnetic source antenna is large. The magnetic beacon and cross-domain magnetic positioning method based on a swinging permanent magnet type mechanical antenna array proposed by the present invention have the advantages of simple structure, compact volume, low power consumption, long positioning distance, and high positioning accuracy. Summary of the Invention

[0003] In order to solve the problems of complex positioning operations and short positioning distance in existing magnetic field positioning technologies, the present invention proposes a magnetic beacon and a cross-domain magnetic positioning method based on a swinging permanent magnet type mechanical antenna array. The magnetic beacon generates a specific spatial magnetic field distribution, and a three-axis magnetic field sensor collects the magnetic field signals generated by the magnetic beacon. The collected signals are subjected to a fast Fourier transform to calculate the amplitudes corresponding to different frequency signals. A magnetic positioning objective function is constructed using the amplitude values and the positions of the three-axis magnetic field sensors, and the pose of the magnetic beacon can be obtained by solving the objective function.

[0004] To achieve the above object, the present invention is implemented by adopting the following technical solutions:

[0005] The magnetic beacon based on a swinging permanent magnet type mechanical antenna array includes a signal generator module, a power amplifier module, and a magnetic beacon antenna; the signal generator generates a sine wave signal, which is transmitted to the power amplifier module for power amplification and then transmitted to the magnetic beacon antenna for magnetic field radiation.

[0006] In one embodiment, the magnetic beacon antenna includes a swinging permanent magnet type mechanical antenna array arranged in a cross structure in a certain order, namely an array in the x-axis direction and an array in the z-axis direction; the operating frequency of the antenna in the x-axis direction is f1, and the operating frequency of the antenna in the z-axis direction is f2 (f1≠f2).

[0007] In one embodiment, each layer of the cross-structured antenna in the magnetic beacon antenna includes swinging permanent magnet type mechanical antenna units arranged according to four initial magnetic moments in a specific direction;

[0008] The mechanical antenna unit includes: a radiation permanent magnet, a coil, and a bias permanent magnet;

[0009] Among them, the positions of the coil and the bias permanent magnet are both fixed, and the radiation permanent magnet swings around the central y-axis of the cylinder;

[0010] The magnetic beacon antenna includes multiple layers of cross-structured antenna units along the y-axis to increase the number of antenna units.

[0011] In one embodiment, the magnetic beacon antenna is divided into multiple layers along the y-axis. In each layer of the cross-structured antenna, the initial magnetic moments of the four antenna units are arranged in the order of: counterclockwise → clockwise → counterclockwise → clockwise, or clockwise → counterclockwise → clockwise → counterclockwise, and the torque couples during the movement of the opposing swinging permanent magnet type mechanical antenna units in each layer will cancel each other out;

[0012] The torque couples during the movement of the swinging permanent magnet type mechanical antenna units between different layers along the y-axis will also cancel each other out.

[0013] On the other hand, a cross-domain magnetic positioning method, the positioning method is based on the magnetic beacon, and the method includes:

[0014] Construct a magnetic field distribution model of the magnetic beacon;

[0015] Perform magnetic beacon positioning through the constructed magnetic field distribution model of the magnetic beacon.

[0016] In one embodiment, the magnetic field distribution model of the magnetic beacon:

[0017] Take the geometric center point of the magnetic beacon as the center of the magnetic beacon. Assume that the center position coordinates of the magnetic beacon are (x0, y0, z0). The four orthogonal swinging permanent magnet type mechanical antenna arrays of the magnetic beacon can be divided into the x-axis direction and the z-axis direction. The x-axis direction is composed of swinging permanent magnet type mechanical antenna units arranged in a certain order, and the z-axis direction is composed of swinging permanent magnet type mechanical antenna units arranged in a certain order. The driving current of the driving coil of each swinging permanent magnet type mechanical antenna unit is , is the total magnitude of the current, I is the magnitude of the current driving the swinging of the permanent magnet for radiation, is the magnitude of the current corresponding to the magnetic moment of the driving coil radiating a magnetic field outward, is much smaller than I in magnitude. The swinging permanent magnet type mechanical antenna unit is driven by a parallel driving method;

[0018] The magnetic moments of the two orthogonal swinging permanent magnet type mechanical antenna arrays of the magnetic beacon radiating magnetic fields outward vary sinusoidally, and are respectively denoted as:

[0019] Among them, is the magnitude of the magnetic moment of the radiation permanent magnet of a single swinging permanent magnet type mechanical antenna unit, and are respectively the swinging angles of the radiation permanent magnets of a single swinging permanent magnet type mechanical antenna in the x-axis direction and the z-axis direction, and are respectively the radiation magnetic moments contributed by the driving coils of a single swinging permanent magnet type mechanical antenna in the x-axis direction and the z-axis direction. Among them, , are the number of turns of the coil, , are the areas of the coil, , are the magnitudes of the currents corresponding to the magnetic moments of the driving coils radiating magnetic fields outward; Denote the magnitude of the radiation magnetic moment in the x-axis direction as , and the resonance frequency as f1; Denote the magnitude of the radiation magnetic moment in the z-axis direction as , and the resonance frequency as f2;

[0020] represents the vector of the radiation magnetic moment of the swinging permanent magnet type mechanical antenna array in the x-axis direction,

[0021] At any point P(x, y, z) in space within the region, the distance between the magnetic beacon and this point When , is the maximum linear dimension of the magnetic beacon;

[0022] Regarding the magnetic beacon as a magnetic dipole, the magnetic fields generated in the x-axis, y-axis, and z-axis directions at this point are respectively:

[0023] (1)

[0024] The vector representing the radiation magnetic moment of the swinging permanent magnet type mechanical antenna array in the z-axis direction generates magnetic fields in the x-axis, y-axis, and z-axis directions at point P(x, y, z) in space, respectively, as follows:

[0025] (2)

[0026] Therefore, the total magnetic fields generated by the magnetic beacon in the x-axis, y-axis, and z-axis directions at any point P(x, y, z) in space are respectively:

[0027] (3)

[0028] where μ0 = 4π×10 -7 N·A -2 is the magnetic permeability in vacuum.

[0029] In one scheme, the determination process of the magnitude of is as follows:

[0030] S1. Only assemble the swinging permanent magnet type mechanical antenna array in the x-axis direction. Measure the attenuation curve of the magnetic field with distance at the center of the antenna on the x-axis. According to , where d is the distance between the measurement point and the swinging permanent magnet type mechanical antenna array. According to inversely deduce to obtain , and obtain the magnitude of the radiation magnetic dipole moment in the x-axis direction;

[0031] S2. Only assemble the swinging permanent magnet type mechanical antenna array in the z-axis direction. Measure the attenuation curve of the magnetic field with distance at the center of the antenna on the z-axis. According to , where d is the distance between the measurement point and the swinging permanent magnet type mechanical antenna array. According to inversely deduce to obtain , and obtain the magnitude of the radiation magnetic dipole moment in the z-axis direction.

[0032] In one scheme, the positioning of the magnetic beacon includes:

[0033] The position (x, y, z) of the three-axis magnetic field sensor at point P is a known quantity. The attitude change of the magnetic beacon relative to the coordinate axes of the three-axis magnetic field sensor is (α, β, γ), where α is the angle between the x-axis of the magnetic beacon and the x-axis of the coordinate system of the magnetic field sensor, β is the angle between the y-axis of the magnetic beacon and the y-axis of the coordinate system of the magnetic field sensor, and γ is the angle between the z-axis of the magnetic beacon and the z-axis of the coordinate system of the magnetic field sensor. Construct the relationship between the magnetic field generated by the magnetic beacon and the three-axis magnetic field received by the magnetic field sensor;

[0034] Use the fast Fourier transform to obtain the amplitude-frequency diagram of the signal;

[0035] A non-linear equation system is formed by combining a magnetic field distribution model, the relationship of three-axis magnetic fields, and the amplitudes of three-axis components corresponding to frequencies. An optimization algorithm is used to solve the non-linear equation system to obtain the pose of the magnetic beacon.

[0036] Advantages of the present invention:

[0037] (1) The magnetic beacon proposed by the present invention has a compact structure and low power consumption. The antenna used in the magnetic beacon of the present invention is a swinging permanent magnet type mechanical antenna, which is directly driven by a coil. Compared with the rotating permanent magnet scheme, meanwhile, its power consumption is lower;

[0038] (2) The positioning method proposed by the present invention can achieve fast and accurate positioning. Through two orthogonal swinging permanent magnet type mechanical antenna arrays with different resonant frequencies, using a single three-axis sensor, the position and attitude of the magnetic beacon, six unknowns, can be obtained in one positioning. While the traditional rotating permanent magnet scheme requires two three-axis sensors for one positioning or a single three-axis sensor for two positionings at different positions to achieve.

[0039] (3) The initial arrangement of the magnetic moments of the antenna units in the magnetic beacon antenna proposed by the present invention can solve the vibration problem during the operation of the magnetic beacon, ensure the stability of its pose, and thus improve the positioning accuracy.

[0040] The present invention has the advantages of simple structure, convenient and fast operation, and can solve the pose of the magnetic beacon by using a single three-axis magnetic sensor for one positioning at a single position, greatly improving the portability of the magnetic beacon positioning system in complex scenarios such as urban utility tunnels and underground mines. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] The drawings here are incorporated into the specification and form a part of this specification, showing embodiments consistent with the present invention, and are used together with the specification to explain the principles of the present invention, and do not constitute an improper limitation to the present invention.

[0042] Figure 1 It is a schematic structural diagram of the magnetic beacon of the present invention;

[0043] Figure 2 It is a front view schematic diagram of the magnetic beacon antenna of the present invention;

[0044] Figure 3 It is a side view schematic diagram of the magnetic beacon antenna of the present invention;

[0045] Figure 4 It is a front view schematic diagram of the initial magnetic moment arrangement of four antenna units in each layer of the magnetic beacon antenna of the present invention;

[0046] Figure 5Schematic side view of the initial magnetic moment arrangement of four antenna units per layer of the magnetic beacon antenna of the present invention;

[0047] Figure 6 Schematic diagram of the positions of the magnetic beacon and the three-axis sensor when positioning is performed according to the present invention;

[0048] Figure 7 Flowchart of the positioning method of the present invention.

[0049] Reference numerals in the figure: 1. Magnetic beacon; 2. Signal generator module; 3. Power amplifier module; 4. Magnetic beacon antenna; 5. Oscillating permanent magnet type mechanical antenna unit; 6. Radiation permanent magnet; 7. Coil; 8. Bias permanent magnet. Detailed implementation manners

[0050] To facilitate the understanding of the present invention, the present invention will be described more comprehensively below with reference to the relevant drawings. Typical embodiments of the present invention are shown in the drawings. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, these embodiments are provided to make the disclosure of the present invention more thorough and comprehensive.

[0051] Unless otherwise defined, all technical and scientific terms used in the present invention have the same meaning as understood by those skilled in the technical field to which the present invention belongs. The terms used in the specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention.

[0052] Embodiment 1

[0053] As Figure 1 shown, the structure of the magnetic beacon 1 of a swinging permanent magnet type mechanical antenna array according to the present invention includes: a signal generator module 2, a power amplifier module 3, and a magnetic beacon antenna 4. During operation, the signal generator 2 generates a sine wave signal of a certain frequency, which is transmitted to the power amplifier module 3 for power amplification, and then transmitted to the magnetic beacon antenna 4 for radiating a magnetic field outward. Preferably, both the signal generator module 2 and the power amplifier module 3 are powered by batteries.

[0054] In the above solution, as Figure 2 shown, the magnetic beacon antenna 4 includes a number of oscillating permanent magnet type mechanical antenna units 5 arranged in a cross structure in a certain order. Each of the oscillating permanent magnet type mechanical antenna units 5 includes: a radiation permanent magnet 6, a coil 7, and a bias permanent magnet 8. Among them, the positions of the coil 7 and the bias permanent magnet 8 are fixed, and the radiation permanent magnet 6 can rotate around the central y-axis of the cylinder. Figure 2 It shows that the magnetic beacon antenna 4 includes multiple layers of cross-structured antennas along the y-axis to increase the number of antenna units.

[0055] In the above solution, as Figure 3, for each antenna unit in the cross structure of each layer in the magnetic beacon antenna 4, the operating frequency of the antenna in the x-axis direction is f1, and the operating frequency of the antenna in the z-axis direction is f2 (f1≠f2). In order to reduce the vibration during the operation of the magnetic beacon antenna, which causes problems such as fluctuations in the amplitude of the magnetic beacon signal and instability of the attitude, the following arrangement method of the initial magnetic moment direction of the swinging permanent magnet type mechanical antenna unit 5 is proposed, as shown in Figure 4 , 5 . Divide the magnetic beacon antenna along the y-axis into multiple layers, then the initial magnetic moment arrangement of the swinging permanent magnet type mechanical antenna unit 5 in each layer is in the order of: counterclockwise → clockwise → counterclockwise → clockwise, or clockwise → counterclockwise → clockwise → counterclockwise, with the orientation alternating; in this arrangement, the torque couples during the movement of the swinging permanent magnet type mechanical antenna units 5 facing each other in each layer will cancel each other out. Similarly, the torque couples during the movement of the swinging permanent magnet type mechanical antenna units 5 between different layers along the y-axis will also cancel each other out. Based on this, the vibration of the magnetic beacon antenna 4 during operation is suppressed and the attitude is stabilized.

[0056] Embodiment 2:

[0057] As shown in Figure 7 , based on the swinging permanent magnet type mechanical antenna array of Embodiment 1, a positioning method based on the swinging permanent magnet type mechanical antenna array is constructed. It includes:

[0058] 1. Construct a magnetic field distribution model of the magnetic beacon

[0059] Take the geometric center point of the magnetic beacon as the center of the magnetic beacon. Assume the center position coordinates of the magnetic beacon are (x0, y0, z0). The four orthogonal swinging permanent magnet type mechanical antenna arrays of the magnetic beacon can be divided into the x-axis direction and the z-axis direction. The x-axis direction is composed of swinging permanent magnet type mechanical antenna units arranged in a certain order, and the z-axis direction is composed of swinging permanent magnet type mechanical antenna units arranged in a certain order. The driving current of the driving coil of each swinging permanent magnet type mechanical antenna unit is , is the total magnitude of the current, I is the magnitude of the current driving the swinging of the driving radiation permanent magnet, is the magnitude of the current corresponding to the magnetic moment of the driving coil radiating the magnetic field outward. The magnitude of is much smaller than the magnitude of I . The swinging permanent magnet type mechanical antenna units are driven in a parallel driving manner;

[0060] The magnetic moments of the two orthogonal swinging permanent magnet type mechanical antenna arrays of the magnetic beacon radiating the magnetic field outward change in a simple harmonic manner, which are respectively recorded as:

[0061] Among them, is the magnitude of the magnetic moment of the radiation permanent magnet of a single swinging permanent magnet type mechanical antenna unit, and are the swinging angles of the radiation permanent magnet of a single swinging permanent magnet type mechanical antenna in the x-axis direction and the z-axis direction respectively, and are the radiation magnetic moments contributed by the drive coils of a single swinging permanent magnet type mechanical antenna in the x-axis direction and the z-axis direction respectively, where, 、 are the number of turns of the coil, 、 are the coil areas, 、 are the magnitudes of the currents corresponding to the magnetic moments of the magnetic fields radiated outward by the drive coils; denote the magnitude of the radiation magnetic moment in the x-axis direction as , the resonance frequency as f1; denote the magnitude of the radiation magnetic moment in the z-axis direction as , the resonance frequency as f2;

[0062] represents the vector of the radiation magnetic moment of the swinging permanent magnet type mechanical antenna array in the x-axis direction. At any point P(x, y, z) in space , the distance between the magnetic beacon and this point When , is the maximum linear dimension of the magnetic beacon. The magnetic beacon can be regarded as a magnetic dipole. The magnetic fields generated in the x-axis, y-axis, and z-axis directions at this point are respectively:

[0063] (1)

[0064] represents the vector of the radiation magnetic moment of the swinging permanent magnet type mechanical antenna array in the z-axis direction. The magnetic fields generated in the x-axis, y-axis, and z-axis directions at the point P(x, y, z) in space are respectively:

[0065] (2)

[0066] Therefore, the total magnetic fields generated in the x-axis, y-axis, and z-axis directions at any point P(x, y, z) in space by the magnetic beacon are respectively:

[0067] (3)

[0068] where, μ0 = 4π × 10 -7 N·A -2 is the magnetic permeability in vacuum.

[0069] As Figure 7 shown, the said The determination process of the size is as follows:

[0070] S1. Only assemble the swinging permanent magnet type mechanical antenna array in the x-axis direction. Measure the attenuation curve of the magnetic field with distance at the x-axis directly opposite the center of the antenna. According to , where d is the distance between the measurement point and the swinging permanent magnet type mechanical antenna array. According to inversely deduce to obtain , and obtain the magnitude of the radiation magnetic dipole moment in the x-axis direction;

[0071] S2. Only assemble the swinging permanent magnet type mechanical antenna array in the z-axis direction. Measure the attenuation curve of the magnetic field with distance at the z-axis directly opposite the center of the antenna. According to , where d is the distance between the measurement point and the swinging permanent magnet type mechanical antenna array. According to inversely deduce to obtain , and obtain the magnitude of the radiation magnetic dipole moment in the z-axis direction;

[0072] To ensure the accuracy of the magnetic dipole moment of the magnetic beacon as much as possible, perform multi-point and multiple measurements, and take the result when the variance is the smallest.

[0073] 2. The positioning method of the magnetic beacon is to perform magnetic beacon positioning through the constructed magnetic field distribution model of the magnetic beacon.

[0074] Assume that the position of the three-axis magnetic field sensor is (x, y, z) as a known quantity, and the attitude change of the magnetic beacon relative to the coordinate axes of the three-axis magnetic field sensor is (α, β, γ), where α is the angle between the x-axis of the magnetic beacon and the x-axis of the coordinate system of the magnetic field sensor, β is the angle between the y-axis of the magnetic beacon and the y-axis of the coordinate system of the magnetic field sensor, and γ is the angle between the z-axis of the magnetic beacon and the z-axis of the coordinate system of the magnetic field sensor. The magnetic field generated by the magnetic beacon and the three-axis magnetic field received by the magnetic field sensor have the following relationship:

[0075] (4)

[0076] Denote as ;

[0077] Briefly denote as:

[0078] Among them, V x , V y , V z are the magnetic field components received by the three axes of the magnetic field sensor respectively. Use the fast Fourier transform to obtain the spectrogram of the signal. The amplitudes of the three-axis components corresponding to the frequency are respectively , , , and have the following relationship:

[0079] (5)

[0080] Frequency The corresponding triaxial component amplitudes , , , there is the following relationship:

[0081] (6)

[0082] Combining Equation (5) and Equation (6) can obtain 6 non - linear equations. Preferably, an optimization algorithm is used to solve this non - linear equation set.

[0083] The fitness function of the optimization algorithm is:

[0084] ,

[0085] ,

[0086] ,

[0087] ,

[0088] ,

[0089] ,

[0090] (7)

[0091] In the above - mentioned solution, the optimization problem is: , and find its minimum value in the domain.

[0092] In the above - mentioned solution, if Figure 6 , assuming that the position of the triaxial sensor is known and the position of the magnetic beacon is within the region , the pose of the magnetic beacon can be obtained according to the triaxial output of the triaxial sensor.

[0093] The positioning method of the magnetic beacon proposed by the present invention is simulated and verified. In the simulation verification of this example, the position of the triaxial magnetic sensor is (0 m, 0 m, 0 m), and the magnetic moment magnitudes of the x - axis and z - axis 6 A·m 2 , there is white noise with a magnitude of 3% of the signal amplitude in the environment. The magnetic beacon moves along the positive y - axis within the region . The magnetic field data is collected from the measurement point at a sampling frequency of 1000 Hz, and then the pose is estimated according to the magnetic field amplitude values at different frequencies. The true coordinates and attitudes and the inverted poses are shown in Table 1.

[0094] Comparison of Pose Simulation Results in Table 1

[0095]

[0096] As shown in Table 1, under the distance condition with an error of 3m, the position error is at the centimeter level, the attitude error is within 4°, and it can be achieved only by a single three-axis sensor with a single measurement at a single position.

[0097] Those of ordinary skill in the art can understand that all or part of the processes in the methods of the above embodiments can be completed by instructing relevant hardware through a computer program. The program can be stored in a computer-readable storage medium. When the program is executed, it can include the processes of the embodiments of the above methods. Among them, the storage medium can be a magnetic disk, an optical disk, a read-only memory (ROM), or a random access memory (RAM), etc.

[0098] It should be understood that the detailed description of the technical solutions of the present invention with the aid of the preferred embodiments above is illustrative rather than restrictive. Those of ordinary skill in the art can modify the technical solutions described in each embodiment on the basis of reading the specification of the present invention, or perform equivalent replacement on some of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of each embodiment of the present invention.

Claims

1. A magnetic beacon based on a swinging permanent magnet type mechanical antenna array, characterized in that: The magnetic beacon based on the swinging permanent magnet type mechanical antenna array includes: a signal generator module, a power amplifier module, and a magnetic beacon antenna; The magnetic beacon antenna is composed of four swinging permanent magnet type mechanical antenna arrays with an orthogonal cross structure; each swinging permanent magnet type mechanical antenna with an orthogonal cross structure is composed of two swinging permanent magnet type mechanical antenna units with different resonant frequencies; The magnetic beacon antenna includes: swinging permanent magnet type mechanical antenna units arranged in sequence to form a cross structure; The mechanical antenna unit includes: a radiation permanent magnet, a coil, and a bias permanent magnet; Among them, the positions of the coil and the bias permanent magnet are fixed, and the radiation permanent magnet swings around the central y-axis of the cylinder; The magnetic beacon antenna includes multiple layers of cross structure antenna units along the y-axis to increase the number of antenna units; In the magnetic beacon antenna, for the antenna units of each layer of cross structure, the working frequency of the antenna in the x-axis direction is f1, and the working frequency of the antenna in the z-axis direction is f2, where f1≠f2; The magnetic beacon antenna is divided into multiple layers along the y-axis. The initial magnetic moments of the four antenna units in each layer of cross structure antenna are arranged in the order of: counterclockwise → clockwise → counterclockwise → clockwise, or clockwise → counterclockwise → clockwise → counterclockwise, and the orientation alternates; the torque couples during the movement of the opposing swinging permanent magnet type mechanical antenna units in each layer cancel each other out; The torques during the movement of the swinging permanent magnet type mechanical antenna units between different layers along the y-axis cancel each other out.

2. A cross-domain magnetic positioning method, the positioning method is based on the magnetic beacon of the swinging permanent magnet type mechanical antenna array described in claim 1, and is characterized in that: The cross-domain magnetic positioning method includes: Constructing a magnetic beacon magnetic field distribution model; Obtaining the magnetic field information of the detection point based on a three-axis magnetic sensor; Determining the fitness function and using an optimization algorithm to solve the pose of the magnetic source; The magnetic beacon magnetic field distribution model is as follows: Take the geometric center point of the magnetic beacon as the center of the magnetic beacon. Assume that the center position coordinates of the magnetic beacon are (x0, y0, z0). The main radiation directions of the four orthogonal oscillating permanent magnet type mechanical antenna arrays of the magnetic beacon are divided into the x-axis direction and the z-axis direction. The x-axis direction is composed of oscillating permanent magnet type mechanical antenna units arranged in a certain order. The z-axis direction is composed of oscillating permanent magnet type mechanical antenna units arranged in a certain order. The drive current of the drive coil of each oscillating permanent magnet type mechanical antenna unit is , is the total magnitude of the current, I is the magnitude of the current driving the oscillation of the radiation permanent magnet, is the magnitude of the current corresponding to the magnetic moment of the drive coil radiating the magnetic field outwards. The magnitude of is much smaller than the magnitude of I . The oscillating permanent magnet type mechanical antenna units are driven in a parallel drive mode; The magnetic moments of the two orthogonal swinging permanent magnet type mechanical antenna arrays of the magnetic beacon radiating magnetic fields change in a simple harmonic manner, which are respectively denoted as: Among them, is the magnitude of the magnetic moment of the radiation permanent magnet of a single swinging permanent magnet type mechanical antenna unit, and are respectively the swinging angles of the radiation permanent magnet of a single swinging permanent magnet type mechanical antenna in the x-axis direction and the z-axis direction, and are respectively the radiation magnetic moments contributed by the drive coils of a single swinging permanent magnet type mechanical antenna in the x-axis direction and the z-axis direction. Among them, 、 is the number of turns of the coil, 、 is the area of the coil, 、 is the magnitude of the current corresponding to the magnetic moment of the magnetic field radiated outward by the drive coil; Denote the magnitude of the radiation magnetic moment in the x-axis direction as , and the resonance frequency as f1; Denote the magnitude of the radiation magnetic moment in the z-axis direction as , and the resonance frequency as f2; Denote the radiation magnetic moment vector of the swinging permanent magnet type mechanical antenna array in the x-axis direction at any point P(x, y, z) in space; , the distance between the magnetic beacon and this point When , is the maximum linear dimension of the magnetic beacon. Regarding the magnetic beacon as a magnetic dipole, the three components of the magnetic field generated at this point are respectively: (1) The magnetic field generated by the radiation magnetic moment vector of the swinging permanent magnet type mechanical antenna array in the z-axis direction at point P(x, y, z) is respectively: (2) Therefore, the total magnetic field of the magnetic beacon at any point P(x, y, z) in space is respectively: (3) where μ0 = 4π×10 -7 N·A -2 is the magnetic permeability in vacuum.

3. The cross-domain magnetic positioning method according to claim 2, characterized in that: The size is determined as follows: S1. Only assemble the swinging permanent magnet type mechanical antenna array in the x-axis direction, measure the attenuation curve of the magnetic field with distance at the x-axis directly opposite the center of the antenna, and according to , where d is the distance between the measurement point and the swinging permanent magnet type mechanical antenna array, and according to inversely deduce to obtain , and obtain the magnitude of the radiation magnetic dipole moment in the x-axis direction; S2. Only assemble the swinging permanent magnet type mechanical antenna array in the z-axis direction, measure the attenuation curve of the magnetic field with distance at the z-axis directly facing the center of the antenna, and according to , where d is the distance between the measurement point and the swinging permanent magnet type mechanical antenna array, and according to inversely deduce to obtain , and obtain the magnitude of the radiation magnetic dipole moment in the z-axis direction.

4. A cross-domain magnetic positioning method according to claim 2, characterized in that: The solving of the magnetic source pose includes: The position (x, y, z) of the three-axis magnetic field sensor at point P is a known quantity, and the attitude change of the magnetic beacon relative to the coordinate axes of the three-axis magnetic sensor is (α, β, γ), where α is the angle between the x-axis of the magnetic beacon and the x-axis of the coordinate system of the magnetic sensor, β is the angle between the y-axis of the magnetic beacon and the y-axis of the coordinate system of the magnetic sensor, and γ is the angle between the z-axis of the magnetic beacon and the z-axis of the coordinate system of the magnetic sensor. A relationship between the magnetic field generated by the magnetic beacon and the three-axis magnetic field received by the magnetic sensor is constructed; Using the fast Fourier transform to obtain the amplitude-frequency diagram of the signal; Combining the magnetic field distribution model, the three-axis magnetic field relationship, and the amplitudes of the three-axis components corresponding to the frequencies, a non-linear equation system is formed, and an optimization algorithm is used to solve the non-linear equation system to obtain the pose of the magnetic beacon.

Images