Magnetic field positioning system
By designing a sandwich structure between the magnetoelectric transmitting and receiving nodes, and combining it with a location determination module, the problem of small coverage radius in low-frequency magnetic field positioning systems is solved, achieving efficient magnetic field positioning coverage and improved accuracy.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- CHINA JILIANG UNIV
- Filing Date
- 2026-05-07
- Publication Date
- 2026-06-26
Smart Images
Figure CN122283587A_ABST
Abstract
Description
Technical Field
[0001] This disclosure relates to the field of positioning technology, and in particular to a magnetic field positioning system. Background Technology
[0002] Positioning systems based on technologies such as Wi-Fi, ultra-wideband, RFID, Bluetooth, and optics have been widely researched and implemented in fields such as industrial IoT, smart homes, emergency rescue, and intelligent robots. However, these systems also face serious challenges such as limited coverage radius of transmitting nodes, low radiation efficiency, susceptibility to environmental electromagnetic interference, and insufficient sensitivity and low positioning accuracy of receiving nodes.
[0003] Low-frequency magnetic field positioning technology has wide applications in specific scenarios such as indoors, underwater, and underground. Currently, coils are typically used as magnetic field transmitting nodes, and magnetic field sensors, including coils, are used to form receiving nodes. Although low-frequency magnetic field positioning systems have ideal robustness against multipath scattering and are simple in structure and have high positioning accuracy, the use of coils as magnetic field transmitting nodes results in large transmitting antenna sizes, low radiation efficiency, and small coverage radii. This necessitates the deployment of a large number of transmitting nodes in limited spaces, thus restricting the use of magnetic field positioning systems and severely limiting their application. Summary of the Invention
[0004] To address the aforementioned technical problems, this disclosure provides a magnetic field positioning method and system.
[0005] According to one aspect of this disclosure, a magnetic field positioning system is provided, the magnetic field positioning system comprising: At least two magnetoelectric transmitting nodes, each of the magnetoelectric transmitting nodes includes a signal generator, a voltage amplification circuit and a first magnetoelectric device connected in sequence. The signal generator is used to generate a first electrical signal, the voltage amplification circuit is used to amplify the first electrical signal and send it to the first magnetoelectric device, and the first magnetoelectric device is used to radiate a magnetic field under the drive of the first electrical signal amplified by the voltage amplification circuit. The magnetic field frequencies of the magnetic fields radiated by different magnetoelectric transmitting nodes are different. At least one magnetoelectric receiving node, each of the magnetoelectric receiving nodes including a second magnetoelectric device, a charge amplification circuit and an amplitude detection circuit connected in sequence, the second magnetoelectric device being used to generate a second electrical signal by sensing the magnetic field radiated by all the magnetoelectric transmitting nodes, the charge amplification circuit being used to detect and amplify the second electrical signal and send it to the amplitude detection circuit, the amplitude detection circuit being used to measure the voltage signal spectrum of the second electrical signal amplified by the charge amplification circuit and send it to the position determination module; The location determination module is used to determine the distance from each magnetoelectric transmitting node to the magnetoelectric receiving node using the voltage signal spectrum of each magnetoelectric transmitting node, and to determine the location of the magnetoelectric receiving node based on the location of each magnetoelectric transmitting node and the distance from each magnetoelectric transmitting node to the magnetoelectric receiving node.
[0006] In some embodiments of this disclosure, the first magnetoelectric device and the second magnetoelectric device adopt the same structure of magnetoelectric device, the same structure of magnetoelectric device including: a first piezoelectric layer, a magnetostrictive layer and a second piezoelectric layer, the first piezoelectric layer, the magnetostrictive layer and the second piezoelectric layer forming a sandwich structure, the middle layer of the sandwich structure being the magnetostrictive layer.
[0007] In some embodiments of this disclosure, the piezoelectric layer is made of lead zirconate titanate ceramic, lead magnesium niobate-lead titanate, or polyvinylidene fluoride.
[0008] In some embodiments of this disclosure, the magnetostrictive layer is made of amorphous alloy Metglas or terbium-dysprosium-iron supermagnetostrictive material Terfenol-D.
[0009] In some embodiments of this disclosure, the voltage amplification circuit includes: a power amplification module and a transformer. The non-inverting input terminal of the power amplification module is used to connect to a power supply, the inverting input terminal of the power amplification module is grounded, the output terminal of the power amplification module is connected to the primary winding terminal of the transformer, and the secondary winding terminal of the transformer is used to connect to the first magnetoelectric device.
[0010] In some embodiments of this disclosure, the charge amplification circuit includes: an operational amplifier, a feedback capacitor, and a feedback resistor; wherein, the inverting input terminal of the operational amplifier is used to connect to the second magnetoelectric device, the non-inverting input terminal of the operational amplifier is grounded, and the output terminal of the operational amplifier serves as the output terminal of the charge amplification circuit, used to connect to the amplitude detection circuit; the feedback capacitor is connected in series between the inverting input terminal and the output terminal of the operational amplifier, the feedback resistor is connected in series between the inverting input terminal and the output terminal of the operational amplifier, and the feedback capacitor and the feedback resistor are connected in parallel.
[0011] In some embodiments of this disclosure, the amplitude detection circuit includes a spectrum analyzer.
[0012] In some embodiments of this disclosure, the location determination module is specifically used to determine the distance from each of the magnetoelectric transmitting nodes to the magnetoelectric receiving nodes in the following manner: determining the magnetic field amplitude of the magnetic field radiated by each magnetoelectric transmitting node at the magnetoelectric receiving node based on the voltage signal spectrum, the magnetic field frequency of each of the magnetoelectric transmitting nodes, and the magnetoelectric conversion coefficient; and calculating the distance from the corresponding magnetoelectric transmitting node to the magnetoelectric receiving node based on the magnetic field amplitude of the magnetic field radiated by each of the magnetoelectric transmitting nodes at the magnetoelectric receiving node using a pre-calibrated distance attenuation model.
[0013] In some embodiments of this disclosure, the pre-calibrated distance attenuation model is expressed as follows: , in, This indicates the amplitude of the magnetic field on the receiving node side. This represents the distance between the magnetoelectric transmitting node and the magnetoelectric receiving node. , The parameters of the distance attenuation model are pre-calibrated by fitting the attenuation curve of the radiation intensity of the magnetoelectric emission node with distance.
[0014] In some embodiments of this disclosure, the location determination module is specifically used to: calculate the location of the magnetoelectric receiving node by means of the following formula when there are two magnetoelectric transmitting nodes and one magnetoelectric receiving node: , in, This represents the X-axis coordinate of the magnetoelectric receiving node. This represents the Y-axis coordinate of the magnetoelectric receiving node. , These represent the distances from the two magnetoelectric transmitting nodes to the magnetoelectric receiving node, respectively. This indicates the distance between the two magnetoelectric emission nodes. It is calculated based on the positions of the two magnetoelectric emission nodes.
[0015] The magnetoelectric transmitting node and magnetoelectric receiving node of the present disclosure adopt magnetoelectric devices. These magnetoelectric devices have the advantages of small size, high radiation efficiency, high precision, strong anti-interference ability, and no error accumulation. They can increase the coverage radius of the transmitting node, effectively improve the maximum measurable distance of magnetic field positioning, effectively solve the problem of deploying a large number of transmitting nodes in a limited space, reduce positioning error, improve magnetic field positioning accuracy, and can be used on a large scale in various complex electromagnetic environment industrial scenarios. Attached Figure Description
[0016] Figure 1 This is a schematic diagram of the structure of the magnetic field positioning system provided in the embodiments of this disclosure; Figure 2 This is a schematic diagram of the structure of the magnetoelectric device involved in the embodiments of this disclosure; Figure 3 This is a schematic diagram of the structure of the magnetoelectric transmitting node according to an embodiment of this disclosure; Figure 4 This is a schematic diagram of the voltage amplifier circuit according to an embodiment of the present disclosure; Figure 5 This is a schematic diagram of the structure of the magnetoelectric receiving node according to an embodiment of this disclosure; Figure 6 This is a schematic diagram of the charge amplification circuit according to an embodiment of the present disclosure; Figure 7 This is a schematic diagram illustrating the test results of the magnetic field positioning system deployed on a school playground according to an embodiment of this disclosure; Figure 8 This is a schematic diagram illustrating the test results of a magnetic field positioning system deployed on a school playground according to an embodiment of this disclosure. Detailed Implementation
[0017] Hereinafter, exemplary embodiments according to the present disclosure will be described in detail with reference to the accompanying drawings. Obviously, the described embodiments are merely some embodiments of the present disclosure, and not all embodiments of the present disclosure, and it should be understood that the present disclosure is not limited to the exemplary embodiments described herein.
[0018] As mentioned earlier, although low-frequency magnetic field positioning systems have ideal robustness against multipath scattering and are simple in structure and have high positioning accuracy, the use of coils as magnetic field transmitting nodes results in a large number of transmitting nodes needing to be deployed in a limited space due to the large size of the transmitting antenna, low radiation efficiency, and small coverage radius of the transmitting nodes. This limits the use of magnetic field positioning systems and severely restricts their application.
[0019] Valter Pasku et al. used a 7 cm radius toroidal coil as both the transmitting and receiving nodes. The transmitting node, with a power consumption of 150 mW, could generate a 2.2 μT AC magnetic field at a distance of approximately 20 cm. The receiving node had a minimum magnetic field detection limit of 12.6 pT in the environment, at a distance of 180 m. 2 Achieving positioning in an indoor environment requires 7 transmission nodes.
[0020] Xiaokang Qi et al. used a 2 m long, 5 cm diameter coil as the transmitting node, with a transmitting power of 6.42 W, and a magnetic sensor with a minimum magnetic field detection limit of 2.7 nT as the receiving node. Using two transmitting nodes, they could only achieve a distance of 16.1 m. 2 The scope is defined.
[0021] Xinnian Li's team used three coils with a radius of 0.15 m as transmitting nodes and a triaxial fluxgate with a minimum magnetic field detection limit of 0.1 nT as receiving nodes. This magnetic field positioning system covers a range of 396.8 m. 2 The area requires 8 launch nodes.
[0022] Roman Kusche et al. used a rotating permanent magnet consisting of a permanent magnet, a turntable, and a motor as the transmitting node, with a power consumption of about 750 mW. Using an AMR sensor with a minimum magnetic field detection limit of 2 nT as the receiving node, one transmitting node was required to achieve positioning within a 100 m² area.
[0023] Yong Cui et al. used a rotating permanent magnet with a total mass exceeding 1000 g as the launching node, placed on a UAV, and employed a magnetic field sensor with a pT-level magnetic field detection limit as the receiving node, fixed at a known location on the ground, to receive low-frequency magnetic signals from three directions at a height of 15 meters and an area of 100 m². 2 The drone can be located within its range.
[0024] It is evident that related technologies generally suffer from large transmitting antenna size and low radiation efficiency, as well as small coverage radius of transmitting nodes. This necessitates the deployment of a large number of transmitting nodes within a limited space, severely restricting the application of magnetic field positioning systems.
[0025] In view of this, the present disclosure provides the following magnetic field positioning system. The magnetic field positioning system of the present disclosure embodiments will be described in detail below.
[0026] Figure 1 A schematic diagram of the magnetic field positioning system provided in an embodiment of this disclosure is shown. See also... Figure 1 The magnetic field positioning system 100 provided in this embodiment may include at least two magnetoelectric transmitting nodes 110, at least one magnetoelectric receiving node 120 and a position determination module 130. At least one magnetoelectric receiving node 120 is located within the magnetic field range of each magnetoelectric transmitting node 110, and at least one magnetoelectric receiving node 120 is connected to the position determination module 130.
[0027] The magnetoelectric transmitting node 110 can be used to radiate a magnetic field under the drive of an electrical signal. The magnetic field frequencies of the magnetic fields radiated by different magnetoelectric transmitting nodes are different. The magnetoelectric receiving node 120 can be used to detect the voltage signal spectrum of the magnetic field radiated by these magnetoelectric transmitting nodes 110. The position determination module 130 can be used to determine the distance from each magnetoelectric transmitting node 110 to the magnetoelectric receiving node 120 using the voltage signal spectrum of each magnetoelectric transmitting node 110. The position of the magnetoelectric receiving node 120 is determined based on the position of each magnetoelectric transmitting node 110 and the distance from each magnetoelectric transmitting node 110 to the magnetoelectric receiving node 120.
[0028] The location determination module 130 can be deployed independently. See also... Figure 1 When the position determination module 130 is deployed independently, at least one magnetoelectric receiving node 120 can share the same position determination module 130. In other examples, the position determination module 130 can be integrated inside the magnetoelectric receiving node 120 as a component of the magnetoelectric receiving node 120, connecting to the amplitude detection circuit of the magnetoelectric receiving node 120 and outputting the position of the magnetoelectric receiving node 120. When the position determination module 130 is integrated inside the magnetoelectric receiving node 120, each magnetoelectric receiving node 120 can output its position independently. In specific applications, the position determination module 130 can be implemented as, but is not limited to, a microprocessor (MCU), a processor (CPU), or other devices that are easy to integrate inside the magnetoelectric receiving node 120, or as electronic devices such as computers, personal computers, and servers.
[0029] The magnetoelectric receiving node 120 is mobile and can be deployed. In specific applications, the magnetoelectric receiving node 120 can be used to locate the position of a target area or the position of a target object. This disclosed embodiment is applicable to, but not limited to, various fields such as industrial IoT, smart homes, emergency rescue, and intelligent robots, and can be applied to target positioning in various scenarios such as indoors, outdoors, underwater, and underground.
[0030] See Figure 1 Taking a magnetic field positioning system comprising N magnetoelectric transmitting nodes 110 and M magnetoelectric receiving nodes 120 as an example, where N is an integer greater than or equal to 2 and M is an integer greater than or equal to 1. The positions of the N magnetoelectric transmitting nodes 110 are known, and the magnetic field frequencies f1, f2, ..., f of the radiated magnetic fields from these N magnetoelectric transmitting nodes 110 are... N It is known that, based on the principle that the amplitude of the radiated magnetic field of the magnetoelectric transmitting node 110 decreases with the cube of the distance, and the voltage signal spectrum detected by the magnetoelectric receiving node 120 for each magnetoelectric transmitting node 110, the distance {d} from each magnetoelectric transmitting node 110 to the magnetoelectric receiving node 120 can be determined. 11 d 12 、…、d 1N}、……、{d M1 d M2 、…、d MN The position of the magnetoelectric receiving node 120 can be calculated from the positions of the N magnetoelectric transmitting nodes 110 and the distance from each magnetoelectric transmitting node 110 to the magnetoelectric receiving node 120.
[0031] In practical applications, a Cartesian coordinate system can be pre-constructed on the plane where the magnetoelectric transmitting node 110 and the magnetoelectric receiving node 120 are located. The positions of the N magnetoelectric transmitting nodes 110 can be represented as their coordinates in this Cartesian coordinate system, and the positions of the magnetoelectric receiving nodes 120 can be represented as their coordinates in the same Cartesian coordinate system. Each magnetoelectric receiving node 120 can represent a target to be measured, and this magnetic field positioning system can simultaneously locate the positions of M targets to be measured.
[0032] The predetermined magnetic field frequency of the magnetoelectric transmitting node is in the low-frequency band. For example, the predetermined magnetic field frequency of each magnetoelectric transmitting node can be 3Hz-30kHz. Magnetic fields in this frequency band can penetrate to relatively deep (e.g., 10 meters) depths in weakly conductive media. Choosing a low frequency allows for better adaptation to specific scenarios such as underwater and underground environments, while also providing stronger resistance to electromagnetic interference and a larger coverage radius.
[0033] The magnetoelectric devices involved in the embodiments of this disclosure can be made of magnetostrictive materials and piezoelectric materials to realize magnetic field radiation and induction. Figure 2 A schematic diagram of the structure of the magnetoelectric device involved in an embodiment of this disclosure is shown. This structure can be used for the magnetoelectric devices in both the magnetoelectric transmitting node and the magnetoelectric receiving node of the magnetic field positioning system according to embodiments of this disclosure.
[0034] See Figure 2 The magnetoelectric device 200 involved in the embodiments of this disclosure may include: a first piezoelectric layer 201, a magnetostrictive layer 202 and a second piezoelectric layer 203, wherein the first piezoelectric layer 201, the magnetostrictive layer 202 and the second piezoelectric layer 203 form a sandwich structure, and the middle layer of the sandwich structure is a magnetostrictive layer.
[0035] When the magnetoelectric device 200 is used in the magnetoelectric transmitting node 110, an AC driving voltage is applied to the first piezoelectric layer 201 and the second piezoelectric layer 203 of the magnetoelectric device 200. Through the inverse piezoelectric effect, the first piezoelectric layer 201 and the second piezoelectric layer 203 are deformed and the deformation is transmitted to the magnetostrictive layer, leading to a change in the magnetization of the magnetostrictive layer. This change in magnetization causes the magnetic moment of the magnetostrictive layer to oscillate with the change in AC voltage. Thus, the magnetoelectric device radiates a magnetic field due to the oscillation of the magnetic moment of the magnetostrictive layer.
[0036] When the magnetoelectric device 200 is used in the magnetoelectric receiving node 120, it can be regarded as a magnetoelectric sensor. The external magnetic field causes the magnetostrictive layer 202 to deform through the magnetoelectric effect and is transmitted to the first piezoelectric layer 201 and the second piezoelectric layer 203, which in turn leads to the change of surface charge of the first piezoelectric layer 201 and the second piezoelectric layer 203. The change of surface charge of the first piezoelectric layer 201 and the second piezoelectric layer 203 will be detected and amplified by the charge amplification circuit, thereby converting the magnetic field signal into a voltage signal.
[0037] In specific applications, the first piezoelectric layer 201 and the second piezoelectric layer 203 are made of the same material, which can be, but is not limited to, lead zirconate titanate ceramic (PZT), lead magnesium niobate-lead titanate (PMN-PT), polyvinylidene fluoride (PVDF), etc. The magnetostrictive layer can be made of, but is not limited to, amorphous alloy (Metglas), terbium-dysprosium-iron super magnetostrictive material (Terfenol-D), etc.
[0038] In practical applications, the size and thickness of the first piezoelectric layer, the magnetostrictive layer, and the second piezoelectric layer in a magnetoelectric device can be flexibly adjusted as needed.
[0039] For example, the magnetostrictive layer of the magnetoelectric device may include four identical Metglas sheets arranged in parallel and bonded together to form the magnetoelectric stretching layer. Each Metglas sheet may have dimensions of 15 mm × 26 μm, where 15 mm is the width and 26 μm is the thickness. Each piezoelectric layer of the magnetoelectric device may include five identical lead zirconate titanate (PZT) ceramic sheets arranged in parallel between interdigitated electrodes (IDEs) and bonded together with epoxy resin. Each PZT ceramic sheet may have dimensions of 40 mm (length) × 2 mm (width) × 0.2 mm (thickness). The magnetostrictive layer can be bonded to the upper and lower surfaces of the two piezoelectric layers respectively using epoxy resin to form a Metglas-PZT-Metglas sandwich structure. This Metglas-PZT-Metglas sandwich structure can then be placed in a vacuum bag and cured for a certain period (e.g., 24 hours) to complete the fabrication of the magnetoelectric device.
[0040] The lengths of the magnetoelectric components in the magnetoelectric receiving node and each magnetoelectric transmitting node can be different. For example, in a magnetic field positioning system with two magnetoelectric transmitting nodes and one magnetoelectric receiving node, the lengths of the magnetoelectric components in the two transmitting nodes and the one receiving node can be 145.1 mm, 145.6 mm, and 146.1 mm, respectively.
[0041] like Figure 2 As shown, the magnetoelectric device 200 is placed at the origin O (0, 0, 0) of the spherical coordinate system, with its length along the z-axis, width along the y-axis, and thickness along the x-axis. The magnetoelectric device 200 is positioned at point P ( , , The magnetic field generated by the oscillation of the magnetic moment is shown in the following equation: , in, This represents the distance from point P to the origin. Let be the angle between the line connecting point P to the origin and the positive z-axis. Let be the angle between the projection of the line connecting point P to the origin onto the xoy plane and the positive x-axis. It is angular frequency. Represents the permeability of free space. It is the free-space radiation impedance. Represents the propagation constant. λ is the wavelength. The total magnetic dipole moment of the magnetoelectric device is the product of the magnetostrictive layer volume and the saturation magnetization. express Magnetic field strength in the direction, express Magnetic field strength in the direction, express The magnetic field strength in the direction.
[0042] Figure 3 A structural example diagram of the magnetoelectric emission node 110 is shown. See also... Figure 3 The magnetoelectric transmitting node 110 may include a signal generator 111, a voltage amplifier circuit 112, and a first magnetoelectric device 113 connected in sequence. The signal generator 111 can be used to generate a first electrical signal. The voltage amplifier circuit 112 can be used to amplify the first electrical signal and send it to the first magnetoelectric device 113. The first magnetoelectric device 113 is used to radiate a magnetic field under the drive of the first electrical signal amplified by the voltage amplifier circuit 112.
[0043] The first electrical signal can be an alternating current (AC) signal. In each magnetoelectric transmitting node 110, the AC signal (i.e., the first electrical signal) provided by the signal generator 111 is amplified by the voltage amplifier circuit 112 and then sent to the first magnetoelectric device 113 to drive the first magnetoelectric device 113 to radiate an AC magnetic field.
[0044] Figure 4 A structural example diagram of a voltage amplifier circuit is shown. See also... Figure 4 In some examples, the voltage amplifier circuit 112 may include: a power amplifier module and a transformer, the non-inverting input terminal of the power amplifier module is used to connect to a power supply, the inverting input terminal of the power amplifier module is grounded, the output terminal of the power amplifier module is connected to the primary winding terminal of the transformer, and the secondary winding terminal of the transformer is used to connect to the first magnetoelectric device 113. Figure 4 The red dashed box contains the power amplifier module, and the blue dashed box contains the transformer.
[0045] In some examples, the power amplifier module can be a power operational amplifier, such as the OPA549 chip. It has been verified that the power amplifier module can amplify the initial electrical signal by approximately 33 times, and then amplify it again by approximately 100 times after passing through a transformer.
[0046] Furthermore, the voltage amplifier circuit 112 may also include a first power management module, which is used to supply power to the power amplifier module. In specific applications, the voltage amplifier circuit 112 may also adopt other structures, and the specific structure of the voltage amplifier circuit is not limited in the embodiments disclosed herein.
[0047] Figure 5 A schematic diagram of the magnetoelectric receiving node 120 is shown. See also... Figure 5 The magnetoelectric receiving node 120 may include a second magnetoelectric device 121, a charge amplification circuit 122, and an amplitude detection circuit 123 connected in sequence. The second electrical signal generated by the second magnetoelectric device 121 due to sensing the magnetic field radiated by each magnetoelectric transmitting node 110 is amplified by the charge amplification circuit 122, and the amplitude detection circuit 123 detects the voltage signal spectrum and sends it to the position determination module 130. Specifically, the second magnetoelectric device 121 can be used to generate a second electrical signal by sensing the magnetic field radiated by all magnetoelectric transmitting nodes 110. The charge amplification circuit 122 can be used to amplify the second electrical signal and send it to the amplitude detection circuit. The amplitude detection circuit 123 can be used to measure the voltage signal spectrum of the second electrical signal amplified by the charge amplification circuit 122 and send it to the position determination module 130.
[0048] Figure 6 A structural example diagram of charge amplifier circuit 122 is shown. See also... Figure 6 In some examples, the charge amplifier circuit 122 may include: an operational amplifier and a feedback capacitor C. f and feedback resistor R f The inverting input of the operational amplifier is connected to the second magnetoelectric device 121, the non-inverting input is grounded, and the output of the operational amplifier serves as the output V of the charge amplifier circuit. out Used to connect the amplitude detection circuit; feedback capacitor C f The feedback resistor R is connected in series between the inverting input and the output of the operational amplifier. f The feedback capacitor C is connected in series between the inverting input and the output of the operational amplifier. f With feedback resistor R f in parallel.
[0049] In some examples, the operational amplifier in charge amplifier circuit 122 can be a low-noise operational amplifier. For example, the operational amplifier in charge amplifier circuit 122 can be an AD795 chip with an input current noise of 0.6 fA / √Hz. The feedback resistor in the charge amplifier circuit can be set to, but is not limited to, 200 MΩ, and the feedback capacitor can be set to, but is not limited to, 100 pF.
[0050] Furthermore, the charge amplifier circuit 122 may also include a second power management module, which can be used to supply power to the charge amplifier circuit. In specific applications, the charge amplifier circuit 122 may also adopt other structures, and the specific structure of the charge amplifier circuit is not limited in the embodiments disclosed herein.
[0051] In some examples, the amplitude detection circuit 123 may include a spectrum analyzer. Specifically, the amplitude detection circuit 123 may be implemented as a circuit that includes a spectrum analyzer, or it may be implemented as a spectrum analyzer itself. The specific structure of the amplitude detection circuit is not limited in the embodiments disclosed herein.
[0052] The first magnetoelectric device 113 and the second magnetoelectric device 121 have the same structure, both adopting the aforementioned Figure 2 The structure is shown. As mentioned above, the lengths of the first magnetoelectric device 113 and the second magnetoelectric device 121 can be different.
[0053] Considering that the maximum measurable distance of the magnetic field positioning system mainly depends on the magnetic field strength radiated by the magnetoelectric transmitting node 110 and the minimum magnetic field detection limit of the magnetoelectric receiving node 120, in this embodiment of the disclosure, a magnetoelectric device 200 with a low minimum magnetic field detection limit and / or low equivalent magnetic field noise can be selected as the second magnetoelectric device 121. That is, the minimum magnetic field detection limit of the second magnetoelectric device 121 is less than or equal to the minimum magnetic field detection limit of the first magnetoelectric device 113; and / or, the equivalent magnetic field noise of the second magnetoelectric device 121 is less than or equal to the equivalent magnetic field noise of the first magnetoelectric device 113.
[0054] Taking three magnetoelectric devices 200 with lengths of 145.1 mm, 145.6 mm, and 146.1 mm as an example, the magnetoelectric receiving node can be found by detecting the minimum magnetic field detection limit and the magnetoelectric device with the lowest equivalent magnetic field noise at the pre-selected resonant frequency. This magnetoelectric device is used as the second magnetoelectric device 121 to form the magnetoelectric receiving node 120, while the other magnetoelectric devices can be used as the first magnetoelectric device 113 to form the magnetoelectric transmitting node 110.
[0055] The location determination module 130 can be used to determine the distance from each magnetoelectric transmitting node 110 to the magnetoelectric receiving node 120 by using the voltage signal spectrum of each magnetoelectric transmitting node 110 in the following manner: first, the magnetic field amplitude of the magnetic field radiated by each magnetoelectric transmitting node 110 at the magnetoelectric receiving node 120 is determined according to the voltage signal spectrum, the magnetic field frequency of each magnetoelectric transmitting node 110 and the magnetoelectric conversion coefficient; then, the distance from the corresponding magnetoelectric transmitting node 110 to the magnetoelectric receiving node 120 is calculated based on the magnetic field amplitude of the magnetic field radiated by each magnetoelectric transmitting node 110 at the magnetoelectric receiving node 120 using a pre-calibrated distance attenuation model.
[0056] Specifically, for each magnetoelectric transmitting node 110, its voltage signal spectrum can be divided by the magnetoelectric conversion coefficient corresponding to the magnetic field frequency of the magnetoelectric transmitting node 110 to obtain the magnetic field signal spectrum of the magnetoelectric transmitting node 110. The amplitude corresponding to the magnetic field frequency of the magnetoelectric transmitting node 110 in the magnetic field signal spectrum is then looked up. This amplitude is the magnetic field amplitude of the magnetic field radiated by the magnetoelectric transmitting node 110 at the magnetoelectric receiving node 120.
[0057] In practical applications, the magnetoelectric conversion coefficient of each magnetoelectric transmitting node 110 can be measured in advance. Typically, the magnetoelectric conversion coefficient of a magnetoelectric transmitting node 110 is related to its magnetic field frequency. The magnetoelectric conversion coefficient used to calculate the magnetic field amplitude can be the magnetoelectric conversion coefficient value corresponding to the magnetic field frequency of the magnetoelectric transmitting node 110.
[0058] The magnetoelectric conversion coefficient of each magnetoelectric transmitting node 110 can be pre-calibrated. Specifically, a sinusoidal signal generated by an alternating current source can be input into a Helmholtz coil to generate an alternating test magnetic field inside the Helmholtz coil. The magnetic field frequency gradually increases from 0 Hz to 50 kHz. The first magnetoelectric device 113 in the magnetoelectric transmitting node 110 is placed in the uniform magnetic field region at the center of the Helmholtz coil. Its output signal is amplified by charge and then the voltage signal is measured by a dynamic signal analyzer. The ratio of the voltage signal to the aforementioned alternating test magnetic field is the magnetoelectric conversion coefficient of the magnetoelectric transmitting node 110.
[0059] Specifically, the distance decay model is expressed as follows: , in, This indicates the amplitude of the magnetic field on the receiving node side. This represents the distance from the magnetoelectric transmitting node 110 to the magnetoelectric receiving node 120. , These are the parameters for the distance attenuation model. The parameters of the distance attenuation model can be pre-calibrated by fitting the attenuation curve of the radiation intensity of magnetoelectric emitting node 110 with distance. Taking magnetoelectric emitting nodes II and III as examples, after calibration, The value is 2.66. The value is 6.59.
[0060] The location determination module 130 can construct a set of equations based on geometric relationships using the locations of each magnetoelectric transmitting node and the distance from each magnetoelectric transmitting node to the magnetoelectric receiving node. By solving the set of equations, the location of the magnetoelectric receiving node can be calculated.
[0061] In some examples, the location determination module 130 can be specifically used to calculate the location of the magnetoelectric receiving node 120 by means of the following formula when the magnetic field positioning system includes two magnetoelectric transmitting nodes 110 and one magnetoelectric receiving node 120: , in, This indicates the X-axis coordinate of the magnetoelectric receiving node 120. This indicates the Y-axis coordinate of the magnetoelectric receiving node 120. , These represent the distances from the two magnetoelectric transmitting nodes 110 to the magnetoelectric receiving node 120, respectively. This indicates the distance between the two magnetoelectric emission nodes 110. It can be calculated based on the positions of the two magnetoelectric emission nodes 110.
[0062] The following section uses the structure of two magnetoelectric transmitting nodes 110 and one magnetoelectric receiving node 120 as an example to illustrate the actual test results of the embodiments of this disclosure.
[0063] Test 1, The magnetic field positioning system of this embodiment is deployed in a school cafeteria. The magnetic field positioning system includes a magnetoelectric transmitting node II, a magnetoelectric transmitting node III, and a magnetoelectric receiving node 120. Magnetoelectric transmitting nodes II and III are fixed at points (0, 0) and (60, 0) respectively in a pre-constructed Cartesian coordinate system perpendicular to the ground, and their magnetic field frequencies are set to 16.30 kHz and 16.36 kHz respectively. Magnetoelectric transmitting nodes II, III, and 120 are all vertically fixed on a tripod with a height of 1.6 m to ensure the stability of magnetic field radiation and reception.
[0064] The magnetoelectric receiving node 120 was subjected to a movement test within a 2400 m² rectangular area bounded by points (0, 0), (60, 0), (60, 40), and (0, 40). The magnetoelectric receiving node 120 was sequentially placed at 120 pre-marked test points within this 2400 m² rectangular area. The actual locations of the 120 test points in the 2400 m² indoor area are shown below. Figure 7 As shown by the black circle in (a) of this disclosure, the actual position measured by the magnetic field positioning system according to this embodiment is as follows: Figure 7 As shown in the red box (a) in the figure. Through comparison and statistics, it was found that the minimum positioning error is about 0.10 m, the maximum positioning error is about 0.35 m, and the average positioning error is about 0.20 m. The cumulative distribution function (CDF) of the positioning error of the magnetic field positioning system is as follows. Figure 7 As shown in (b) above, by Figure 7 As can be seen in (b), approximately 90% of the positioning point errors are less than 0.25 m.
[0065] Test 2, The magnetic field positioning system of this embodiment is deployed on a school playground. The system includes a magnetoelectric transmitting node II, a magnetoelectric transmitting node III, and a magnetoelectric receiving node 120. Magnetoelectric transmitting nodes II and III are fixed at points (0, 0) and (60, 0) respectively in a pre-constructed Cartesian coordinate system perpendicular to the ground, with their magnetic field frequencies set to 16.30 kHz and 16.36 kHz respectively. All three nodes—magnetoelectric transmitting nodes II, III, and 120—are vertically fixed on a tripod with a height of 1.6 m to ensure the stability of magnetic field radiation and reception.
[0066] The magnetoelectric receiving node 120 can be moved and tested within a 3600 m² square area bounded by points (0, 0), (60, 0), (60, 60), and (0, 60). The magnetoelectric receiving node 120 is placed sequentially at 130 pre-marked test points within this 3600 m² square area.
[0067] The actual locations of the 130 test points are as follows: Figure 8 As shown by the black circle in (a) of this disclosure, the actual position measured by the magnetic field positioning system according to this embodiment is as follows: Figure 8 As shown in the red box (a) in the figure. Statistically, the minimum positioning error is approximately 0.11 m, the maximum positioning error is approximately 0.35 m, and the average positioning error is approximately 0.20 m. The cumulative distribution function of the positioning error of the magnetic field positioning system provided in this embodiment of the present disclosure in this scenario is as follows: Figure 8 As shown in (b) in the figure, from Figure 8 As can be seen from (b) in the figure, about 90% of the positioning point errors are less than 0.25 m.
[0068] Based on the two actual test results above, it can be seen that the magnetic field positioning system provided in this embodiment only requires two magnetoelectric transmitting nodes and one magnetoelectric receiving node to achieve a range of 2400m. 2 Indoor area and 3600m 2 The positioning accuracy in outdoor areas is approximately 0.20 m, which effectively solves the problem of deploying a large number of transmitting nodes in a limited space, significantly improves the measurable range of magnetic field positioning technology, and provides high positioning accuracy with no error accumulation.
[0069] It should be noted that although the embodiments of this disclosure employ a system structure with two magnetoelectric transmitting nodes 110 and one magnetoelectric receiving node 120 in the test, those skilled in the art should understand that in specific applications, the number of magnetoelectric transmitting nodes 110 can be flexibly increased according to scenario requirements, positioning accuracy requirements, etc., and the number of magnetoelectric receiving nodes 120 can also be flexibly increased according to the number of targets to be located in order to locate multiple targets simultaneously. This disclosure does not limit the specific number or deployment location of the magnetoelectric transmitting nodes 110 and magnetoelectric receiving nodes 120 in the magnetic field positioning system, as long as the number of magnetoelectric transmitting nodes is greater than or equal to 2 and the number of magnetoelectric receiving nodes is greater than or equal to 1.
[0070] The above description has been given for purposes of illustration and description. Furthermore, this description is not intended to limit the embodiments of this disclosure to the forms disclosed herein. Although numerous exemplary aspects and embodiments have been discussed above, those skilled in the art will recognize certain variations, modifications, alterations, additions, and sub-combinations therein.
Claims
1. A magnetic field positioning system, characterized in that, The magnetic field positioning system includes: At least two magnetoelectric transmitting nodes, each of the magnetoelectric transmitting nodes includes a signal generator, a voltage amplification circuit and a first magnetoelectric device connected in sequence. The signal generator is used to generate a first electrical signal, the voltage amplification circuit is used to amplify the first electrical signal and send it to the first magnetoelectric device, and the first magnetoelectric device is used to radiate a magnetic field under the drive of the first electrical signal amplified by the voltage amplification circuit. The magnetic field frequencies of the magnetic fields radiated by different magnetoelectric transmitting nodes are different. At least one magnetoelectric receiving node, each of the magnetoelectric receiving nodes including a second magnetoelectric device, a charge amplification circuit and an amplitude detection circuit connected in sequence, the second magnetoelectric device being used to generate a second electrical signal by sensing the magnetic field radiated by all the magnetoelectric transmitting nodes, the charge amplification circuit being used to detect and amplify the second electrical signal and send it to the amplitude detection circuit, the amplitude detection circuit being used to measure the voltage signal spectrum of the second electrical signal amplified by the charge amplification circuit and send it to the position determination module; The location determination module is used to determine the distance from each magnetoelectric transmitting node to the magnetoelectric receiving node using the voltage signal spectrum of each magnetoelectric transmitting node, and to determine the location of the magnetoelectric receiving node based on the location of each magnetoelectric transmitting node and the distance from each magnetoelectric transmitting node to the magnetoelectric receiving node.
2. The system according to claim 1, characterized in that, The first and second magnetoelectric devices are magnetoelectric devices with the same structure, which includes a first piezoelectric layer, a magnetostrictive layer and a second piezoelectric layer. The first piezoelectric layer, the magnetostrictive layer and the second piezoelectric layer form a sandwich structure, and the middle layer of the sandwich structure is the magnetostrictive layer.
3. The system according to claim 2, characterized in that, The piezoelectric layer is made of lead zirconate titanate ceramic, lead magnesium niobate-lead titanate, or polyvinylidene fluoride.
4. The system according to claim 2, characterized in that, The magnetostrictive layer is made of amorphous alloy Metglas or terbium-dysprosium-iron super magnetostrictive material Terfenol-D.
5. The system according to claim 1, characterized in that, The voltage amplification circuit includes a power amplification module and a transformer. The non-inverting input terminal of the power amplification module is used to connect to a power supply, the inverting input terminal of the power amplification module is grounded, the output terminal of the power amplification module is connected to the primary winding terminal of the transformer, and the secondary winding terminal of the transformer is used to connect to the first magnetoelectric device.
6. The system according to claim 1, characterized in that, The charge amplification circuit includes: an operational amplifier, a feedback capacitor, and a feedback resistor; Wherein, the inverting input terminal of the operational amplifier is used to connect to the second magnetoelectric device, the non-inverting input terminal of the operational amplifier is grounded, and the output terminal of the operational amplifier serves as the output terminal of the charge amplification circuit, used to connect to the amplitude detection circuit; The feedback capacitor is connected in series between the inverting input terminal and the output terminal of the operational amplifier, the feedback resistor is connected in series between the inverting input terminal and the output terminal of the operational amplifier, and the feedback capacitor and the feedback resistor are connected in parallel.
7. The system according to claim 1, characterized in that, The amplitude detection circuit includes a spectrum analyzer.
8. The system according to claim 1, characterized in that, The location determination module is specifically used to determine the distance from each of the magnetoelectric transmitting nodes to the magnetoelectric receiving nodes in the following manner: The magnetic field amplitude of the magnetic field radiated by each magnetoelectric transmitting node at the magnetoelectric receiving node is determined based on the voltage signal spectrum, the magnetic field frequency of each magnetoelectric transmitting node, and the magnetoelectric conversion coefficient. The distance from the corresponding magnetoelectric transmitting node to the magnetoelectric receiving node is calculated using a pre-calibrated distance attenuation model based on the magnetic field amplitude at the magnetoelectric receiving node of the magnetic field radiated by each magnetoelectric transmitting node.
9. The system according to claim 8, characterized in that, The pre-calibrated distance attenuation model is expressed as follows: ， in, This indicates the amplitude of the magnetic field on the receiving node side. This represents the distance between the magnetoelectric transmitting node and the magnetoelectric receiving node. , The parameters of the distance attenuation model are pre-calibrated by fitting the attenuation curve of the radiation intensity of the magnetoelectric emission node with distance.
10. The system according to claim 1, characterized in that, The location determination module is specifically used to: calculate the location of the magnetoelectric receiving node by means of the following formula when there are two magnetoelectric transmitting nodes and one magnetoelectric receiving node: ， in, This represents the X-axis coordinate of the magnetoelectric receiving node. This represents the Y-axis coordinate of the magnetoelectric receiving node. , These represent the distances from the two magnetoelectric transmitting nodes to the magnetoelectric receiving node, respectively. This indicates the distance between the two magnetoelectric emission nodes. It is calculated based on the positions of the two magnetoelectric emission nodes.