阅读说明：本技术 基于磁偶极子场的磁指纹提取方法、装置、系统与介质 (Magnetic fingerprint extraction method, device, system and medium based on magnetic dipole field ) 是由 王国强 程甚男 张铁龙 于 2020-11-24 设计创作，主要内容包括：本发明公开了一种基于磁偶极子场的磁指纹提取方法,磁偶极子场由采集空间中的磁场发生器产生,磁场发生器包括螺线管,方法包括：通过预设测量点处的磁传感器获取预设测量点处的叠加磁场分量；根据叠加磁场分量,确定预设测量点处的背景磁场,以及螺线管在预设测量点处产生的目标磁场；根据目标磁场,确定预设测量点的位置；根据背景磁场和位置,得到采集空间中的磁指纹。本发明还公开了一种基于磁偶极子场的磁指纹提取装置、系统和介质。本发明通过磁偶极子场环境中预设测量点处采集到的叠加磁场分量,确定预设测量点处的背景磁场以及预设测量点的位置,从而得到采集空间的磁指纹,不需要事先划分网格来采集磁指纹,有利于减小磁指纹采集的工作量。(The invention discloses a magnetic fingerprint extraction method based on a magnetic dipole field, wherein the magnetic dipole field is generated by a magnetic field generator in an acquisition space, the magnetic field generator comprises a solenoid, and the method comprises the following steps: acquiring a superposed magnetic field component at a preset measuring point through a magnetic sensor at the preset measuring point; determining a background magnetic field at a preset measuring point and a target magnetic field generated by the solenoid at the preset measuring point according to the superposed magnetic field components; determining the position of a preset measuring point according to the target magnetic field; and obtaining the magnetic fingerprint in the acquisition space according to the background magnetic field and the position. The invention also discloses a magnetic fingerprint extraction device, a system and a medium based on the magnetic dipole field. According to the invention, the background magnetic field at the preset measuring point and the position of the preset measuring point are determined through the superposed magnetic field component acquired at the preset measuring point in the magnetic dipole field environment, so that the magnetic fingerprint of the acquisition space is obtained, the magnetic fingerprint is acquired without dividing grids in advance, and the workload of magnetic fingerprint acquisition is favorably reduced.)

1. A magnetic fingerprint extraction method based on a magnetic dipole field generated by a magnetic field generator in an acquisition space, said magnetic field generator comprising a solenoid, said method comprising the steps of:

acquiring a superposed magnetic field component at a preset measuring point through a magnetic sensor at the preset measuring point;

determining a background magnetic field at the preset measuring point and a target magnetic field generated by the solenoid at the preset measuring point according to the superposed magnetic field components;

determining the position of the preset measuring point according to the target magnetic field;

and determining the magnetic fingerprint in the acquisition space according to the background magnetic field and the position.

2. The magnetic dipole field-based magnetic fingerprint extraction method as claimed in claim 1, wherein said step of acquiring the superimposed magnetic field component at a preset measurement point by a magnetic sensor at the preset measurement point comprises:

adjusting the posture of a magnetic sensor at a preset measuring point to enable the three-axis direction of the magnetic sensor to be consistent with the reference direction of a preset coordinate system;

and controlling the magnetic sensor to collect to obtain the superposed magnetic field component at the preset measuring point.

3. A magnetic dipole field based magnetic fingerprint extraction method as claimed in claim 1 wherein said magnetic field generator further comprises a power supply assembly supplying an alternating current to said solenoid, said determining a background magnetic field at said predetermined measurement point from said superimposed magnetic field components, and said step of said solenoid generating a target magnetic field at said predetermined measurement point comprises:

acquiring the period of the alternating current, and determining the statistical period of the superposed magnetic field component based on the period;

in the statistical period, acquiring a first superposed magnetic field component acquired at the preset measuring point when the solenoid is introduced with forward current and a second superposed magnetic field component acquired at the preset measuring point when the solenoid is introduced with reverse current;

determining a background magnetic field at the preset measurement point and a target magnetic field generated by the solenoid at the preset measurement point based on the first and second superimposed magnetic field components.

4. A magnetic dipole field based magnetic fingerprint extraction method as claimed in claim 3 wherein said step of determining a background magnetic field at said preset measurement point based on said first and second superimposed magnetic field components and a target magnetic field generated by said solenoid at said preset measurement point comprises:

calculating the average values of the first superposed magnetic field component and the second superposed magnetic field component respectively to obtain a first average superposed component and a second average superposed component;

determining a background magnetic field at the preset measuring point based on the first average superposition component, the second average superposition component and a first preset algorithm;

determining a target magnetic field produced by the solenoid at the preset measurement point based on the first average superimposed component, the second average superimposed component, and a second preset algorithm.

5. The magnetic dipole field-based magnetic fingerprint extraction method of claim 1, wherein the solenoid is wound with a coil, and the step of determining the location of the predetermined measurement point based on the target magnetic field comprises:

acquiring a central coordinate of the central position of each coil in a preset coordinate system, and respectively determining a coordinate vector between each central coordinate and each coordinate point in the preset coordinate system;

determining a spatial magnetic field generated by the solenoid in the preset coordinate system according to the coordinate vector;

and determining the position of the preset measuring point based on the target magnetic field and the space magnetic field.

6. A magnetic dipole field based magnetic fingerprint extraction method as claimed in claim 5 wherein said step of determining the spatial magnetic field generated by said solenoid in said predetermined coordinate system based on said coordinate vector comprises:

acquiring relative position information of the coordinate vector in the preset coordinate system, and determining a coil magnetic field generated by each coil at each coordinate point based on the relative position information;

determining a spatial magnetic field generated by the solenoid in the preset coordinate system based on the coil magnetic field.

7. The magnetic dipole field-based magnetic fingerprint extraction method of claim 5, wherein said step of determining the location of said predetermined measurement point based on said target magnetic field and said spatial magnetic field comprises:

acquiring a target magnetic field component corresponding to the target magnetic field and space magnetic field components of the space magnetic field at each coordinate point, and determining a target space magnetic field component which is the same as the target magnetic field component;

and determining a coordinate point corresponding to the target space magnetic field component as a target coordinate point, and determining the position of the target coordinate point as the position of the preset measuring point.

8. A magnetic dipole field-based magnetic fingerprint extraction device, wherein the magnetic dipole field is generated by a magnetic field generator in an acquisition space, the magnetic field generator comprising a solenoid, the magnetic dipole field-based magnetic fingerprint extraction device comprising:

the data acquisition module is used for acquiring the superposed magnetic field component at a preset measuring point through a magnetic sensor at the preset measuring point;

a magnetic field determination module for determining a background magnetic field at the preset measurement point and a target magnetic field generated by the solenoid at the preset measurement point according to the superimposed magnetic field component;

the position determining module is used for determining the position of the preset measuring point according to the target magnetic field;

and the final determination module is used for determining the magnetic fingerprint in the acquisition space according to the background magnetic field and the position.

9. A magnetic dipole field based magnetic fingerprint extraction system, comprising: a memory, a processor, and a magnetic dipole field-based magnetic fingerprint extraction program stored on the memory and executable on the processor, the magnetic dipole field-based magnetic fingerprint extraction program when executed by the processor implementing the steps of the magnetic dipole field-based magnetic fingerprint extraction method of any one of claims 1 to 7.

10. A medium having stored thereon a magnetic dipole field based magnetic fingerprint extraction program, which when executed by a processor implements the steps of the magnetic dipole field based magnetic fingerprint extraction method of any one of claims 1 to 7.

Technical Field

The invention relates to the technical field of space magnetic field distribution, in particular to a magnetic fingerprint extraction method, a device, a system and a medium based on a magnetic dipole field.

Background

Along with the continuous expansion of cities, the number of large buildings is increased, the indoor activity time of people is prolonged, and the requirements on indoor positioning and navigation are increased. In the research of the indoor positioning method, the indoor positioning method based on the magnetic field signal does not need to be provided with extra equipment in advance, is not influenced by the multipath effect and the like, and has higher commercial popularization value.

The indoor positioning method based on the magnetic field comprises the steps of constructing a magnetic fingerprint map, measuring the magnetic field and matching and positioning the contents of the three parts. The magnetic field inside the building is formed by superposing the earth inherent magnetic field, the structures of the building such as reinforcing steel bars and concrete, and the magnetic fields generated by metal door frames, furniture, electric appliances and the like, and the magnetic fingerprint refers to the spatial distribution of the inherent magnetic field inside the building. The magnetic fingerprint acquisition through magnetic field measurement is the basis for constructing a magnetic fingerprint map and is also the key for subsequent matching and positioning.

A common method for acquiring magnetic fingerprints is to perform area division on the internal space of a building according to a preset path type to form a plurality of split areas; establishing an acquisition path of each splitting area, and setting a corresponding acquisition rule for the acquisition path; and according to the acquisition path and the acquisition rule of each split area, carrying out data acquisition on the magnetic fingerprint of the corresponding split area, and processing the acquired magnetic fingerprint data to generate a magnetic fingerprint database. In this way, the magnetic field information of all grid points can be obtained to obtain the corresponding magnetic fingerprint information, but the method needs to divide the grid in advance, so that the workload of magnetic fingerprint acquisition is large.

Disclosure of Invention

The invention mainly aims to provide a magnetic fingerprint extraction method, a device, a system and a medium based on a magnetic dipole field, and aims to realize the purpose of extracting magnetic fingerprints without dividing grids in advance.

To achieve the above object, the present invention provides a magnetic fingerprint extraction method based on a magnetic dipole field generated by a magnetic field generator in an acquisition space, the magnetic field generator including a solenoid, the method comprising the steps of:

acquiring a superposed magnetic field component at a preset measuring point through a magnetic sensor at the preset measuring point;

determining a background magnetic field at the preset measuring point and a target magnetic field generated by the solenoid at the preset measuring point according to the superposed magnetic field components;

determining the position of the preset measuring point according to the target magnetic field;

and determining the magnetic fingerprint in the acquisition space according to the background magnetic field and the position.

Preferably, the step of acquiring the superimposed magnetic field component at the preset measurement point by the magnetic sensor at the preset measurement point includes:

adjusting the posture of a magnetic sensor at a preset measuring point to enable the three-axis direction of the magnetic sensor to be consistent with the reference direction of a preset coordinate system;

and controlling the magnetic sensor to collect to obtain the superposed magnetic field component at the preset measuring point.

Preferably, the magnetic field generator further comprises a power supply assembly supplying an alternating current to the solenoid, the step of determining a background magnetic field at the preset measurement point from the superimposed magnetic field component, and the target magnetic field generated by the solenoid at the preset measurement point comprises:

acquiring the period of the alternating current, and determining the statistical period of the superposed magnetic field component based on the period;

in the statistical period, acquiring a first superposed magnetic field component acquired at the preset measuring point when the solenoid is introduced with forward current and a second superposed magnetic field component acquired at the preset measuring point when the solenoid is introduced with reverse current;

determining a background magnetic field at the preset measurement point and a target magnetic field generated by the solenoid at the preset measurement point based on the first and second superimposed magnetic field components.

Preferably, the step of determining a background magnetic field at the preset measurement point based on the first and second superimposed magnetic field components, and a target magnetic field generated by the solenoid at the preset measurement point comprises:

calculating the average values of the first superposed magnetic field component and the second superposed magnetic field component respectively to obtain a first average superposed component and a second average superposed component;

determining a background magnetic field at the preset measuring point based on the first average superposition component, the second average superposition component and a first preset algorithm;

determining a target magnetic field produced by the solenoid at the preset measurement point based on the first average superimposed component, the second average superimposed component, and a second preset algorithm.

Preferably, the solenoid is formed by winding a coil, and the step of determining the position of the preset measuring point according to the target magnetic field includes:

acquiring a central coordinate of the central position of each coil in a preset coordinate system, and respectively determining a coordinate vector between each central coordinate and each coordinate point in the preset coordinate system;

determining a spatial magnetic field generated by the solenoid in the preset coordinate system according to the coordinate vector;

and determining the position of the preset measuring point based on the target magnetic field and the space magnetic field.

Preferably, the step of determining the space magnetic field generated by the solenoid in the preset coordinate system according to the coordinate vector comprises:

acquiring relative position information of the coordinate vector in the preset coordinate system, and determining a coil magnetic field generated by each coil at each coordinate point based on the relative position information;

determining a spatial magnetic field generated by the solenoid in the preset coordinate system based on the coil magnetic field.

Preferably, the step of determining the position of the preset measurement point based on the target magnetic field and the spatial magnetic field comprises:

acquiring a target magnetic field component corresponding to the target magnetic field and space magnetic field components of the space magnetic field at each coordinate point, and determining a target space magnetic field component which is the same as the target magnetic field component;

and determining a coordinate point corresponding to the target space magnetic field component as a target coordinate point, and determining the position of the target coordinate point as the position of the preset measuring point.

In addition, to achieve the above object, the present invention also provides a magnetic fingerprint extraction apparatus based on a magnetic dipole field, comprising:

the data acquisition module is used for acquiring the superposed magnetic field component at a preset measuring point through a magnetic sensor at the preset measuring point;

a magnetic field determination module for determining a background magnetic field at the preset measurement point and a target magnetic field generated by the solenoid at the preset measurement point according to the superimposed magnetic field component;

the position determining module is used for determining the position of the preset measuring point according to the target magnetic field;

and the final determination module is used for determining the magnetic fingerprint in the acquisition space according to the background magnetic field and the position.

Preferably, the data acquisition module is further configured to:

adjusting the posture of a magnetic sensor at a preset measuring point to enable the three-axis direction of the magnetic sensor to be consistent with the reference direction of a preset coordinate system;

and controlling the magnetic sensor to collect to obtain the superposed magnetic field component at the preset measuring point.

Preferably, the magnetic field determination module is further configured to:

acquiring the period of the alternating current, and determining the statistical period of the superposed magnetic field component based on the period;

in the statistical period, acquiring a first superposed magnetic field component acquired at the preset measuring point when the solenoid is introduced with forward current and a second superposed magnetic field component acquired at the preset measuring point when the solenoid is introduced with reverse current;

determining a background magnetic field at the preset measurement point and a target magnetic field generated by the solenoid at the preset measurement point based on the first and second superimposed magnetic field components.

Preferably, the magnetic field determination module is further configured to:

calculating the average values of the first superposed magnetic field component and the second superposed magnetic field component respectively to obtain a first average superposed component and a second average superposed component;

determining a background magnetic field at the preset measuring point based on the first average superposition component, the second average superposition component and a first preset algorithm;

determining a target magnetic field produced by the solenoid at the preset measurement point based on the first average superimposed component, the second average superimposed component, and a second preset algorithm.

Preferably, the position determination module is further configured to:

acquiring a central coordinate of the central position of each coil in a preset coordinate system, and respectively determining a coordinate vector between each central coordinate and each coordinate point in the preset coordinate system;

determining a spatial magnetic field generated by the solenoid in the preset coordinate system according to the coordinate vector;

and determining the position of the preset measuring point based on the target magnetic field and the space magnetic field.

Preferably, the position determination module is further configured to:

acquiring relative position information of the coordinate vector in the preset coordinate system, and determining a coil magnetic field generated by each coil at each coordinate point based on the relative position information;

determining a spatial magnetic field generated by the solenoid in the preset coordinate system based on the coil magnetic field.

Preferably, the position determination module is further configured to:

acquiring a target magnetic field component corresponding to the target magnetic field and space magnetic field components of the space magnetic field at each coordinate point, and determining a target space magnetic field component which is the same as the target magnetic field component;

and determining a coordinate point corresponding to the target space magnetic field component as a target coordinate point, and determining the position of the target coordinate point as the position of the preset measuring point.

In addition, to achieve the above object, the present invention further provides a magnetic fingerprint extraction system based on a magnetic dipole field, including: a memory, a processor, and a magnetic dipole field based magnetic fingerprint extraction program stored on the memory and executable on the processor, the magnetic dipole field based magnetic fingerprint extraction program when executed by the processor implementing the steps of the magnetic dipole field based magnetic fingerprint extraction method as described above.

In addition, to achieve the above object, the present invention further provides a medium having a magnetic fingerprint extraction program based on a magnetic dipole field stored thereon, wherein the magnetic fingerprint extraction program based on the magnetic dipole field, when executed by a processor, implements the steps of the magnetic fingerprint extraction method based on the magnetic dipole field as described above.

The invention provides a magnetic fingerprint extraction method based on a magnetic dipole field, which comprises the steps of obtaining a superposed magnetic field component at a preset measuring point through a magnetic sensor at the preset measuring point; determining a background magnetic field at a preset measuring point and a target magnetic field generated by the solenoid at the preset measuring point according to the superposed magnetic field components; determining the position of a preset measuring point according to the target magnetic field; and obtaining the magnetic fingerprint in the acquisition space according to the background magnetic field and the position. According to the invention, the background magnetic field at the preset measuring point and the position of the preset measuring point are determined through the magnetic field data acquired at the preset measuring point in the magnetic dipole field environment, so that the magnetic fingerprint of the acquisition space is obtained, the magnetic fingerprint is acquired without dividing grids in advance, and the workload of acquiring the magnetic fingerprint is favorably reduced.

Drawings

FIG. 1 is a system diagram of a hardware operating environment according to an embodiment of the present invention;

FIG. 2 is a schematic flow chart of a first embodiment of a magnetic fingerprint extraction method based on a magnetic dipole field according to the present invention;

FIG. 3 is a schematic diagram of a magnetic field generator and a square wave type AC power of the magnetic fingerprint extraction method based on a magnetic dipole field according to the present invention;

FIG. 4 is a schematic diagram of the magnetic field components measured by the magnetic sensor according to the magnetic fingerprint extraction method based on the magnetic dipole field of the present invention;

FIG. 5 is a functional block diagram of a magnetic fingerprint extraction device based on magnetic dipole field according to a preferred embodiment of the present invention.

The implementation, functional features and advantages of the objects of the present invention will be further explained with reference to the accompanying drawings.

Detailed Description

It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

As shown in fig. 1, fig. 1 is a system structural diagram of a hardware operating environment according to an embodiment of the present invention.

The system provided by the embodiment of the invention comprises a cloud server or an intelligent terminal and the like.

As shown in fig. 1, the system may include: a processor 1001, such as a CPU, a network interface 1004, a user interface 1003, a memory 1005, a communication bus 1002. Wherein a communication bus 1002 is used to enable connective communication between these components. The user interface 1003 may include a Display screen (Display), an input unit such as a Keyboard (Keyboard), and the optional user interface 1003 may also include a standard wired interface, a wireless interface. The network interface 1004 may optionally include a standard wired interface, a wireless interface (e.g., WI-FI interface). The memory 1005 may be a high-speed RAM memory or a non-volatile memory (e.g., a magnetic disk memory). The memory 1005 may alternatively be a storage device separate from the processor 1001.

Those skilled in the art will appreciate that the system architecture shown in FIG. 1 is not intended to be limiting of the system, and may include more or fewer components than those shown, or some components may be combined, or a different arrangement of components.

As shown in fig. 1, a memory 1005, which is a medium, may include therein an operating system, a network communication module, a user interface module, and a magnetic fingerprint extraction program based on a magnetic dipole field.

The operating system is a program for managing and controlling the magnetic fingerprint extraction system based on the magnetic dipole field and software resources, and supports the operation of a network communication module, a user interface module, the magnetic fingerprint extraction program based on the magnetic dipole field and other programs or software; the network communication module is used for managing and controlling the network interface 1002; the user interface module is used to manage and control the user interface 1003.

In the magnetic dipole field-based magnetic fingerprint extraction system shown in fig. 1, the magnetic dipole field-based magnetic fingerprint extraction system calls a magnetic dipole field-based magnetic fingerprint extraction program stored in a memory 1005 through a processor 1001 and performs the operations in the various embodiments of the magnetic dipole field-based magnetic fingerprint extraction method described below.

Based on the hardware structure, the embodiment of the magnetic fingerprint extraction method based on the magnetic dipole field is provided.

Referring to fig. 2, fig. 2 is a schematic flow chart of a first embodiment of a magnetic fingerprint extraction method based on a magnetic dipole field according to the present invention, where the method includes:

step S10, acquiring the superposed magnetic field component at the preset measuring point through the magnetic sensor at the preset measuring point;

the magnetic fingerprint extraction method based on the magnetic dipole field is applied to the magnetic fingerprint extraction system based on the magnetic dipole field of each large scene, particularly the magnetic fingerprint extraction system based on the magnetic dipole field of an indoor scene, and for convenience in description, the magnetic fingerprint extraction system based on the magnetic dipole field is referred to as a magnetic fingerprint system for short. Along with the continuous expansion of cities, the number of large buildings is increased, the indoor activity time of people is prolonged, and the requirements on indoor positioning and navigation are increased. In the research of the indoor positioning method, the indoor positioning method based on the magnetic field signal does not need to be provided with additional equipment in advance, is not influenced by the multipath effect and the like, and has higher research and development and commercial value.

The indoor positioning method based on the magnetic field comprises the steps of measuring the magnetic field, constructing a magnetic fingerprint map and matching and positioning the contents of the three parts. The magnetic field inside the building is formed by superposing the earth inherent magnetic field, the structures of the building such as reinforcing steel bars and concrete, and the magnetic fields generated by metal door frames, furniture, electric appliances and the like, and the magnetic fingerprint refers to the spatial distribution of the inherent magnetic field inside the building. The magnetic fingerprint acquisition through magnetic field measurement is the basis for constructing a magnetic fingerprint map and is also the key for subsequent matching and positioning.

A common method for acquiring magnetic fingerprints is to perform area division on the internal space of a building according to a preset path type to form a plurality of split areas; establishing an acquisition path of each splitting area, and setting a corresponding acquisition rule for the acquisition path; and according to the acquisition path and the acquisition rule of each split area, carrying out data acquisition on the magnetic fingerprint of the corresponding split area, and carrying out compatible preprocessing on the acquired magnetic fingerprint data to generate a magnetic fingerprint database. In this way, the magnetic field information of all grid points can be obtained to obtain the corresponding magnetic fingerprint information, but the method needs to divide the grid in advance, so that the workload of magnetic fingerprint acquisition is large.

In this embodiment, a magnetic field generator is first configured, and referring to fig. 3, the magnetic field generator includes a power supply assembly and a solenoid, wherein the solenoid is a circular coil wound with N turns, the power supply assembly can provide a periodic alternating current to the solenoid, and for example, the power supply assembly can be controlled to provide the solenoid with a square wave type current with alternating positive and negative current of 1A magnitude. The solenoid is connected with the power supply component by a lead to form a circuit loop, and if the circuit loop is conducted, the solenoid generates a target magnetic field at each coordinate point in the space. In addition, predetermine and preset the measuring point, preset the measuring point and can be any coordinate point or a plurality of coordinate points in gathering the space, and preset the measuring point and place the magnetic sensor, be used for measuring the superimposed magnetic field component of presetting the measuring point department, wherein, the magnetic sensor is three-axis magnetic sensor, measurable quantity magnetic sensor is located the position and is in the ascending magnetic field B of three axle directions_x、B_y、B_zWherein B is_xFor superimposing the magnetic field component of the magnetic field at a predetermined measuring point in the direction of the X-axis of a predetermined coordinate system, B_yFor superimposing the magnetic field component of the magnetic field in the direction of the Y-axis at a predetermined measuring point, B_zThe magnetic field component of the magnetic field in the Z-axis direction is superposed at the preset measuring point. In order to obtain higher positioning accuracy, a magnetic sensor with higher measurement accuracy is generally adopted, such as an industrial fluxgate magnetometer.

Further, step S10 includes:

a1, adjusting the posture of a magnetic sensor at a preset measuring point to make the three-axis direction of the magnetic sensor consistent with the reference direction of a preset coordinate system;

in the present embodiment, the preset coordinate system is established by placing the solenoid on a specific horizontal plane, such as a roof, a horizontal floor, etc., and setting the specific horizontal plane as an X-Y plane with the central position point of the solenoid as the origin of coordinates. The direction of the X axis and the direction of the Y axis are not limited, the axial direction of the solenoid is the Z axis, specifically, the axial direction of the solenoid can be the positive direction of the Z axis, then the positive direction of the X axis is set, and then the positive direction of the Y axis of the preset coordinate system is determined through the right-hand rule, so that the preset coordinate system is established, and the magnetic field generated by the solenoid at any coordinate point in the space needing to collect the magnetic fingerprint is determined. The three-axis direction of the magnetic sensor can be consistent with the reference direction of the preset coordinate system by adjusting the posture of the magnetic sensor at the preset measuring point, specifically, the magnetic sensor can be placed at a position point with known coordinate parameters in the preset coordinate system, the measured data of the magnetic sensor in the three-axis direction is compared with the coordinate parameters corresponding to the position point, and if the measured data is respectively consistent with the three coordinate parameters of the position point, the three-axis direction of the magnetic sensor is consistent with the reference direction of the preset coordinate system.

Step a2, controlling the magnetic sensor to collect to obtain the superposed magnetic field component at the preset measuring point.

In this embodiment, when the three-axis direction of the magnetic sensor at the preset measurement point is consistent with the reference direction of the preset coordinate system, the magnetic sensor is controlled to perform continuous acquisition, and the magnetic field data acquired by the magnetic sensor in the three-axis direction is the superimposed magnetic field component corresponding to the superimposed magnetic field at the preset measurement point.

Step S20, determining a background magnetic field at the preset measurement point and a target magnetic field generated by the solenoid at the preset measurement point according to the superimposed magnetic field component;

in the present embodiment, the superimposed magnetic field at the preset measurement point is formed by superimposing the target magnetic field generated by the solenoid at the preset measurement point and the background magnetic field at the preset measurement point, and therefore, the superimposed magnetic field component measured by the magnetic sensor includes the target magnetic field component corresponding to the target magnetic field generated by the solenoid at the preset measurement point and the background magnetic field component corresponding to the background magnetic field at the preset measurement point. The background magnetic field is formed by superposing the inherent magnetic field of the earth, the structures of the reinforcing steel bars, concrete and the like of the building, and the magnetic fields generated by the metal door frame, furniture, electric appliances and the like, and when the environment of the acquisition space changes, the background magnetic field at each position in the space can not change obviously, so that the background magnetic field at each position point can be considered to be basically unchanged. Because the alternating current provided by the power supply assembly is in periodic change, namely the current of the first half period and the current of the second half period are equal in magnitude and opposite in direction, after the solenoid is electrified with the alternating current, the target magnetic fields generated by the electrified solenoid in the first half period and the second half period are also equal in magnitude and opposite in direction, namely the target magnetic fields generated by the electrified solenoid at any point in the preset coordinate system can be mutually cancelled in integral multiple periods of the alternating current. Therefore, it is possible to determine the background magnetic field at the preset measurement point and the target magnetic field generated by the solenoid at the preset measurement point from the superimposed magnetic field at the preset measurement point using the periodic characteristics of the target magnetic field.

Further, step S20 includes:

step b1, acquiring the period of the alternating current, and determining the statistical period of the superposed magnetic field component based on the period;

in the present embodiment, since the target magnetic fields generated by the energized solenoids at any point in the preset coordinate system can cancel each other out during the period of the alternating current by an integral multiple, the integral multiple of the period can be determined as the statistical period by the period of the alternating current, and the background magnetic field at the preset measurement point and the target magnetic field generated by the energized solenoids at the preset measurement point can be determined by superimposing the magnetic field components during the statistical period.

Step b2, in the statistical period, acquiring a first superposed magnetic field component acquired at the preset measuring point when the solenoid is electrified with forward current and a second superposed magnetic field component acquired at the preset measuring point when the solenoid is electrified with reverse current;

in this embodiment, if the target magnetic field direction generated when the solenoid applies the forward current is positive, the target magnetic field direction generated when the solenoid applies the reverse current is negative, and therefore, the first superimposed magnetic field component acquired at the preset measurement point when the solenoid applies the forward current is different from the second superimposed magnetic field component acquired at the preset measurement point when the solenoid applies the reverse current.

Step b3, determining a background magnetic field at the preset measurement point and a target magnetic field generated by the solenoid at the preset measurement point based on the first and second superimposed magnetic field components.

In this embodiment, the superimposed magnetic field at the preset measurement point is formed by superimposing a target magnetic field generated by the solenoid at the preset measurement point and a background magnetic field at the preset measurement point, the first superimposed magnetic field at the preset measurement point when the forward current is applied to the solenoid can be determined according to the first superimposed magnetic field component, the second superimposed magnetic field at the preset measurement point when the reverse current is applied to the solenoid can be determined according to the second superimposed magnetic field component, and if the magnetic field components measured by the magnetic sensor in the three axial directions are respectively B_x、B_y、B_zThen, combining the unit vectors in the X-axis, Y-axis and Z-axis directions, the superimposed magnetic field at the preset measurement point can be determined asDue to the presettingThe background magnetic field in the coordinate system does not change significantly over a statistical period and therefore can be considered to be substantially constant. Eliminating the background magnetic field at the preset measuring point from the superposed magnetic field to obtain the target magnetic field generated by the solenoid at the preset measuring point; similarly, the target magnetic field of the energized solenoid at the preset measurement point is eliminated from the superimposed magnetic field, and the background magnetic field at the preset measurement point can be obtained. Therefore, the background magnetic field at the preset measuring point and the target magnetic field generated by the solenoid at the preset measuring point can be calculated according to the first superposed magnetic field component and the second superposed magnetic field component collected at the preset measuring point when the forward current and the reverse current are introduced into the solenoid.

Step S30, determining the position of the preset measuring point according to the target magnetic field;

in the present embodiment, since the target magnetic fields generated by the energized solenoids at different coordinate points in the preset coordinate system are also different, that is, by determining the target magnetic fields generated by the solenoids at the preset measurement points, the positions of the preset measurement points can be uniquely determined.

Further, step S30 includes:

step c1, obtaining the center coordinates of the center position of each coil in a preset coordinate system, and respectively determining the coordinate vectors between each center coordinate and each coordinate point in the preset coordinate system;

in the present embodiment, the solenoid is formed by winding N turns of coils, and therefore, the center position of each coil is different from the position of the center position of the solenoid in the Z-axis direction, that is, the center coordinates of each coil in the preset coordinate system are different. In specific implementation, the coordinates corresponding to the coordinate vector are obtained by subtracting the coordinates of each coordinate point in the preset coordinate system from the center coordinates, so as to determine the corresponding coordinate vector.

Step c2, determining the space magnetic field generated by the solenoid in the preset coordinate system according to the coordinate vector;

in this embodiment, since the target magnetic fields generated by the energized solenoid at coordinate points at different distances are different, the distance from each coordinate point to the center of the coil can be determined according to the coordinate vector of the center coordinate of each coil corresponding to each coordinate point in the preset coordinate system, and therefore, the magnetic field generated by each coil at each coordinate point can be determined according to the coordinate vector, so as to determine the space magnetic field generated by the solenoid in the preset coordinate system.

Further, step c2 further includes:

step c21, acquiring relative position information of the coordinate vector in the preset coordinate system, and determining a coil magnetic field generated by each coil at each coordinate point based on the relative position information;

in this embodiment, the relative position information of each coordinate vector in the preset coordinate system may be obtained through a preset algorithm model, and specifically, the relative position information includes an included angle between the coordinate vector and the Z axisThe rotation angle theta of the meridian plane of the coordinate vector relative to the meridian plane of the X axis₀The meridian plane is a plane parallel to the earth's rotation axis or including the short axis of the earth's ellipsoid. For example, the center coordinates of the i-th turn coil in the solenoid are (0,0, Z)₀) The coordinate of a certain coordinate point in the preset coordinate system is (X)₁，Y₁，Z₁) Then the coordinate vector pointing from the coordinate point to the center coordinate point is (X)₁，Y₁，Z₁-Z₀) Then the length of the coordinate vector is

Determining a coil magnetic field generated by the coil at each coordinate point, and acquiring the radius of each coil, wherein the magnetic field component formula of an ideal coil with the radius of R in a preset coordinate system is as follows:

wherein, B_x、B_y、B_zRespectively representing the magnetic field components of the ideal coil in the X-axis, Y-axis and Z-axis directions of a preset coordinate system;

mu is magnetic conductivity;

i is the magnitude of the current in the solenoid;

theta is the rotation angle of the meridian plane relative to the meridian plane of the X axis, and the range is [0,2 pi ];

r is the distance from the measuring point to the center of the coil, namely the length of the coordinate vector;

r is the radius of the coil;

the zenith angle at the measuring point, namely the included angle between the coordinate vector and the Z axis;

θ₀is the rotation angle of the meridian plane where the coordinate vector is located relative to the meridian plane of the X axis.

By acquiring the radius of the coil and the corresponding relative position information, the magnetic field component of each coil at each coordinate point in the preset coordinate system can be respectively obtained through the equations (1) and (2), so that the coil magnetic field generated by each coil at each coordinate point can be obtained.

A step c22 of determining a spatial magnetic field generated by the solenoid in the preset coordinate system based on the coil magnetic field;

in the present embodiment, the spatial magnetic field generated by the solenoid at each coordinate point, that is, the spatial magnetic field generated by the solenoid at all coordinate points in the preset coordinate system, can be obtained by performing a superposition operation on the coil magnetic fields generated by the respective coils at the respective coordinate points.

And c3, determining the position of the preset measuring point based on the target magnetic field and the space magnetic field.

In the present embodiment, since the target magnetic fields generated by the energized solenoid at different coordinate points in the preset coordinate system are different, that is, by determining the target magnetic fields generated by the solenoid at the preset measurement points, the position of the preset measurement points can be uniquely determined.

Further, step c3 further includes:

step c31, acquiring a target magnetic field component corresponding to the target magnetic field and a spatial magnetic field component of the spatial magnetic field at each coordinate point, and determining a target spatial magnetic field component identical to the target magnetic field component;

in this embodiment, the target magnetic field component corresponding to the target magnetic field generated at the preset measurement point is compared and matched with the coordinate magnetic field component corresponding to each spatial magnetic field, and the spatial magnetic field component that is the same as the target magnetic field component, that is, the target spatial magnetic field component, is determined.

And c32, determining the coordinate point corresponding to the target space magnetic field component as a target coordinate point, and determining the position of the target coordinate point as the position of the preset measuring point.

In this embodiment, since the target magnetic fields generated by the solenoids at the respective coordinate points in the space where the magnetic field is to be collected in the preset coordinate system are different, that is, by determining the target magnetic fields generated by the energized solenoids at the preset measurement points, the positions of the preset measurement points can be uniquely determined. Therefore, the position of any coordinate point in the space of the preset coordinate system where the magnetic field is to be collected can be determined by the method.

And step S40, determining the magnetic fingerprint in the acquisition space according to the background magnetic field and the position.

In this embodiment, the magnetic fingerprint in the collection space theoretically consists of the positions of all coordinate points in the preset coordinate system and the background magnetic field at each coordinate point, but in practical application, all coordinate points in the collection space do not need to be collected, and only the target coordinate point needs to be selected as the preset measurement point to be measured according to practical application requirements. And each coordinate point in the preset coordinate system can be used as a preset measuring point, the magnetic fingerprint information at the preset measuring point cannot be determined at one time through the magnetic sensor, and the measurement by adopting a large number of magnetic sensors also requires higher equipment cost, so that in order to reduce the equipment cost, one magnetic sensor can be adopted to measure the preset measuring point in the preset coordinate system, and a plurality of magnetic sensors can also be simultaneously utilized to collect, thereby completing the data collection at all the preset measuring points in the preset coordinate system, obtaining the magnetic fingerprint information at all the preset measuring points, and further determining the magnetic fingerprint in the collection space.

In the magnetic fingerprint extraction method based on the magnetic dipole field of the embodiment, a magnetic sensor at a preset measuring point is used for acquiring a superposed magnetic field component at the preset measuring point; determining a background magnetic field at a preset measuring point and a target magnetic field generated by the solenoid at the preset measuring point according to the superposed magnetic field components; determining the position of a preset measuring point according to the target magnetic field; and obtaining the magnetic fingerprint in the acquisition space according to the background magnetic field and the position. According to the invention, the background magnetic field at the preset measuring point and the position of the preset measuring point are determined through the magnetic field data acquired at the preset measuring point in the magnetic dipole field environment, so that the magnetic fingerprint of the acquisition space is obtained, the magnetic fingerprint is acquired without dividing grids in advance, and the workload of acquiring the magnetic fingerprint is favorably reduced.

Further, based on the first embodiment of the magnetic fingerprint extraction method based on the magnetic dipole field, the second embodiment of the magnetic fingerprint extraction method based on the magnetic dipole field is provided.

A second embodiment of a magnetic dipole field based magnetic fingerprint extraction method differs from the first embodiment in that the step of determining a background magnetic field at the preset measurement point based on the first and second superimposed magnetic field components and a target magnetic field generated by the solenoid at the preset measurement point comprises:

d, respectively calculating the average values of the first superposed magnetic field component and the second superposed magnetic field component to obtain a first average superposed component and a second average superposed component;

in this embodiment, when a square-wave type alternating current is applied to the solenoid, referring to fig. 4, fig. 4 is a diagram illustrating the magnetic field components measured by the magnetic sensor according to the magnetic fingerprint extraction method based on the magnetic dipole field of the present inventionIt is intended that the magnetic field data measured by the magnetic sensor is the magnetic field components of the preset measuring point in the directions of the X-axis, the Y-axis and the Z-axis. Due to the reason of environmental interference, the acquired magnetic field data can fluctuate, namely, the first superposed magnetic field component acquired when the solenoid is electrified with forward current in the statistical period can be different, and similarly, the second superposed magnetic field component acquired when the solenoid is electrified with reverse current can be different. Specifically, a first average superimposed component corresponding to the first superimposed magnetic field component is calculated, that is, when the solenoid is supplied with a forward current, a first superimposed magnetic field component B measured by a magnetic sensor at a preset measurement point in a statistical period is calculated respectively_xAverage value of (1), B_yAverage value of (1), B_zThe three average values are used as first average superposed components corresponding to the first superposed magnetic field component, and the second average superposed component can be obtained by the same method. The average value of the first superposed magnetic field component and the average value of the second superposed magnetic field component are obtained to obtain the first average superposed component and the second average superposed component, so that the obtained magnetic field data can be smoother, and the influence caused by measurement errors can be effectively reduced.

E, determining a background magnetic field at the preset measuring point based on the first average superposed component, the second average superposed component and a first preset algorithm;

in this embodiment, the superimposed magnetic field at the preset measurement point is formed by superimposing a target magnetic field generated by the solenoid at the preset measurement point and a background magnetic field at the preset measurement point, the first average superimposed magnetic field at the preset measurement point when the forward current is applied to the solenoid can be determined according to the first average superimposed component, and the second average superimposed magnetic field at the preset measurement point when the reverse current is applied to the solenoid can be determined according to the second average superimposed component. If the background magnetic field at the preset measuring point isThe average target magnetic field generated when the solenoid is electrified with forward current isThe average target magnetic field generated when the solenoid is energized with a reverse current isThen, when the solenoid is supplied with a forward current, the first average superposed magnetic field at the preset measuring point isWhen the solenoid is introduced with reverse current, the second average superposed magnetic field at the preset measuring point isThe first preset algorithm is preferably an addition operation, and the addition operation is performed on the first average superposed magnetic field and the second average superposed magnetic field, so that the target magnetic field generated by the solenoid at the preset measuring point can be offset, and the corresponding magnetic field sum is obtainedAnd dividing the sum of the magnetic fields by 2 to obtain the background magnetic field at the preset measuring point.

Step f, determining a target magnetic field generated by the solenoid at the preset measurement point based on the first average superimposed component, the second average superimposed component and a second preset algorithm.

In this embodiment, if the background magnetic field at the predetermined measurement point isThe average target magnetic field generated when the solenoid is electrified with forward current isThe average target magnetic field generated when the solenoid is electrified with reverse direction current isThen, when the solenoid is supplied with a forward current, the first average superposed magnetic field at the preset measuring point isWhen the solenoid is introduced with reverse current, the second average superposed magnetic field at the preset measuring point isThe second preset algorithm is preferably subtraction, and the subtraction is performed on the first average superposed magnetic field and the second average superposed magnetic field, so that the background magnetic field at the preset measuring point can be offset, and the corresponding magnetic field difference is obtainedAnd dividing the magnetic field difference by 2 to obtain a target magnetic field generated by the solenoid at a preset measuring point when the forward current is introduced into the solenoid.

In the magnetic fingerprint extraction method based on the magnetic dipole field of the embodiment, the average value of the magnetic field data collected at the preset measuring point when the solenoid is connected with the forward/reverse current is calculated in the statistical period, and then the background magnetic field and the corresponding target magnetic field at the preset measuring point are determined, so that the obtained magnetic field data are smoother, and the influence caused by the measuring error can be effectively reduced.

The invention also provides a magnetic fingerprint extraction device based on the magnetic dipole field. Referring to fig. 3, the magnetic fingerprint extracting apparatus based on a magnetic dipole field of the present invention includes:

the data acquisition module 10 is configured to acquire a superimposed magnetic field component at a preset measurement point through a magnetic sensor at the preset measurement point;

a magnetic field determining module 20, configured to determine, according to the superimposed magnetic field component, a background magnetic field at the preset measurement point and a target magnetic field generated by the solenoid at the preset measurement point;

a position determining module 30, configured to determine a position of the preset measurement point according to the target magnetic field;

a final determination module 40, configured to determine the magnetic fingerprint in the acquisition space according to the background magnetic field and the position.

Preferably, the data acquisition module is further configured to:

adjusting the posture of a magnetic sensor at a preset measuring point to enable the three-axis direction of the magnetic sensor to be consistent with the reference direction of a preset coordinate system;

and controlling the magnetic sensor to collect to obtain the superposed magnetic field component at the preset measuring point.

Preferably, the magnetic field determination module is further configured to:

acquiring the period of the alternating current, and determining the statistical period of the superposed magnetic field component based on the period;

in the statistical period, acquiring a first superposed magnetic field component acquired at the preset measuring point when the solenoid is introduced with forward current and a second superposed magnetic field component acquired at the preset measuring point when the solenoid is introduced with reverse current;

determining a background magnetic field at the preset measurement point and a target magnetic field generated by the solenoid at the preset measurement point based on the first and second superimposed magnetic field components.

Preferably, the magnetic field determination module is further configured to:

calculating the average values of the first superposed magnetic field component and the second superposed magnetic field component respectively to obtain a first average superposed component and a second average superposed component;

determining a background magnetic field at the preset measuring point based on the first average superposition component, the second average superposition component and a first preset algorithm;

determining a target magnetic field produced by the solenoid at the preset measurement point based on the first average superimposed component, the second average superimposed component, and a second preset algorithm.

Preferably, the position determination module is further configured to:

acquiring a central coordinate of the central position of each coil in a preset coordinate system, and respectively determining a coordinate vector between each central coordinate and each coordinate point in the preset coordinate system;

determining a spatial magnetic field generated by the solenoid in the preset coordinate system according to the coordinate vector;

and determining the position of the preset measuring point based on the target magnetic field and the space magnetic field.

Preferably, the position determination module is further configured to:

acquiring relative position information of the coordinate vector in the preset coordinate system, and determining a coil magnetic field generated by each coil at each coordinate point based on the relative position information;

determining a spatial magnetic field generated by the solenoid in the preset coordinate system based on the coil magnetic field.

Preferably, the position determination module is further configured to:

acquiring a target magnetic field component corresponding to the target magnetic field and space magnetic field components of the space magnetic field at each coordinate point, and determining a target space magnetic field component which is the same as the target magnetic field component;

and determining a coordinate point corresponding to the target space magnetic field component as a target coordinate point, and determining the position of the target coordinate point as the position of the preset measuring point.

The present invention also provides a medium, preferably a computer readable storage medium, having a magnetic dipole field based magnetic fingerprint extraction program stored thereon, which when executed by a processor, implements the steps of the magnetic dipole field based magnetic fingerprint extraction method as described above.

The method implemented when the magnetic fingerprint extraction program based on the magnetic dipole field run on the processor is executed may refer to each embodiment of the magnetic fingerprint extraction method based on the magnetic dipole field of the present invention, and is not described herein again.

It should be noted that, in this document, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or system that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or system. Without further limitation, an element defined by the phrase "comprising an … …" does not exclude the presence of other like elements in a process, method, article, or system that comprises the element.

The above-mentioned serial numbers of the embodiments of the present invention are merely for description and do not represent the merits of the embodiments.

Through the above description of the embodiments, those skilled in the art will clearly understand that the method of the above embodiments can be implemented by software plus a necessary general hardware platform, and certainly can also be implemented by hardware, but in many cases, the former is a better implementation manner. Based on such understanding, the technical solution of the present invention may be embodied in the form of a software product, which is stored in a medium (such as ROM/RAM, magnetic disk, optical disk) as described above and includes instructions for enabling a terminal system (such as a mobile phone, a computer, a server, an air conditioner, or a network system) to execute the method according to the embodiments of the present invention.

The above description is only a preferred embodiment of the present invention, and not intended to limit the scope of the present invention, and all modifications of equivalent structures and equivalent processes, which are made by using the contents of the present specification and the accompanying drawings, or directly or indirectly applied to other related technical fields, are included in the scope of the present invention.