Linear single-point positioning method based on permanent magnet type mechanical antenna

Abstract

The invention discloses a linear single-point positioning method based on a permanent magnet type mechanical antenna, and belongs to the technical field of electromagnetic detection and positioning. The method comprises the following steps: establishing a Cartesian coordinate system by taking a three-axis magnetic field sensor as an original point, wherein the coordinate axis direction is the same as the sensitive axis of the sensor; measuring radiation magnetic field data generated by the permanent magnet type mechanical antenna with known frequency and equivalent magnetic moment; obtaining a plurality of uncertain positions in the half space based on the amplitude information of the measurement data; error positions are eliminated according to phase information of a measured magnetic field, a unique correct position is selected, and positioning is completed. Compared with a traditional permanent magnet type mechanical antenna positioning method based on numerical optimization, the amplitude and phase information of the radiation magnetic field can be utilized, the calculation process can be completed more quickly, meanwhile, the positioning range is expanded, and the positioning range is expanded by installing the antenna on a robot or a human body. Accurate positioning can be realized in a global navigation satellite system denial environment, and the method has wide application potential.

Description

Technical Field

[0001] The present invention belongs to the technical field of electromagnetic detection and positioning, and specifically relates to a linear single-point positioning method based on a permanent magnetic mechanical antenna, which is mainly used for precise positioning of human bodies / robots in GNSS-denied environments. Background Art

[0002] With the widespread application of global navigation satellite systems (GNSS) in the fields of positioning, navigation and timing, many modern systems have become highly dependent on them. However, in some special scenarios, such as urban canyons, underground facilities, submarine environments and military scenarios, GNSS signals may be severely shielded, interfered or even completely ineffective, which makes it impossible to rely on GNSS for positioning. Therefore, how to achieve accurate and efficient positioning in an environment where GNSS is limited or without coverage has become an important research topic. In order to solve this problem, researchers began to explore the use of alternative positioning methods. Among them, the positioning technology using magnetic field characteristics has become an important research direction because it does not rely on external wireless signal sources and has strong anti-interference ability. Permanent magnetic mechanical antenna is a new positioning technology based on this concept. The dynamic magnetic field generated by the rotation of the antenna can form a spatial magnetic field distribution around the target object, and the change of magnetic field characteristics can be used to estimate the target position. This antenna positioning technology is particularly suitable for use in GNSS-denied environments. Current research and applications are mostly focused on how to improve positioning accuracy, adapt to more complex environments, and speed up calculations. Although existing positioning methods, such as those based on particle swarm optimization (PSO), can provide a certain degree of positioning accuracy, in practical applications, existing methods often have problems such as long calculation time and inability to handle positioning needs in a larger range. With the increasing requirements for real-time performance and computational efficiency, the limitations of existing technologies are gradually exposed, which makes further optimizing positioning algorithms and expanding their applicability the focus of current research. Summary of the invention

[0003] In order to solve the above technical problems, the present invention provides a linear single-point positioning method based on a permanent magnet mechanical antenna, which fully considers the amplitude information and phase information of the radiated magnetic field, can significantly improve the positioning speed and expand the positioning range, and can be used for fast and accurate positioning of human bodies / robots in GNSS-denied environments.

[0004] To achieve the above purpose, the technical solution adopted by the present invention is as follows:

[0005] A linear single-point positioning method based on a permanent magnetic mechanical antenna, the implementation steps are as follows:

[0006] A Cartesian coordinate system is established with the three-axis magnetic field sensor as the origin, and the direction of the coordinate axis is the same as the sensor sensitive axis;

[0007] Measure the radiation magnetic field data generated by a permanent magnet mechanical antenna with a known frequency and equivalent magnetic moment;

[0008] Based on the amplitude information of the measured radiation magnetic field data, obtain multiple symmetric uncertain positions in the half space. The multiple symmetric uncertain positions include 8 possible positions of the mechanical antenna under the condition that the extreme value of the z-axis component of the radiation magnetic field is zero, or 5 possible positions of the mechanical antenna under the condition that the extreme value of the z-axis component of the radiation magnetic field is not zero;

[0009] Exclude the wrong positions according to the phase information of the measured radiation magnetic field data, select the only correct position, and complete the positioning.

[0010] The beneficial effects of the present invention are as follows:

[0011] (1) The present invention fully considers the problem of slow calculation speed of traditional positioning methods based on numerical optimization, and derives a faster linear positioning method.

[0012] (2) The present invention expands the positioning range of the algorithm by simultaneously using the amplitude information and phase information of the radiation field of the mechanical antenna. Description of the Drawings

[0013] Figure 1 It is a flow chart of a linear single-point positioning method based on a permanent magnet mechanical antenna of the present invention;

[0014] Figure 2 It is a schematic diagram of the coordinate system established by the present invention, the magnetic field sensor and the position of the mechanical antenna. Detailed Embodiment

[0015] The present invention will be further described below with reference to the drawings and embodiments.

[0016] As Figure 1 shown, a linear single-point positioning method based on a permanent magnet mechanical antenna of the present invention includes the following steps: First, establish a Cartesian coordinate system with a three-axis magnetic field sensor as the origin, and the axis directions are the same as the sensor sensitive axes; Second, measure the radiation magnetic field generated by the cooperative mechanical antenna: measure the radiation magnetic field data generated by a permanent magnet mechanical antenna with a known frequency and equivalent magnetic moment; Then, calculate the feasible positions based on the amplitude information: obtain multiple uncertain positions in the half space based on the amplitude information of the measured data; Finally, select the true position according to the phase information: further exclude the wrong positions according to the phase information of the measured magnetic field, select the only correct position, and complete the positioning. The specific implementation steps are as follows:

[0017] In the first step, as Figure 2 shown, in the spherical coordinate system, the radiation magnetic field generated by the permanent magnet mechanical antenna at any measurement point in space is:

[0018] (1)

[0019] Among them, among them, and respectively represent the remanence and volume of the permanent magnet, represents the position vector from the mechanical antenna to the sensor, represents the transpose operation, represents the position vector modulus, that is, the distance between the mechanical antenna and the sensor, and are respectively the inclination angle and declination angle of the mechanical antenna position, represents the wave number, and are respectively the magnetic permeability and dielectric constant of the propagation medium, represents the angular velocity of rotation of the mechanical antenna, j represents the imaginary unit, e represents the exponential function, and t represents the time instant.

[0020] In addition, the magnetic field measured by the sensor is in the Cartesian coordinate system, so coordinate transformation is required, and the rotation matrix is:

[0021] (2)

[0022] Therefore, the radiated magnetic field in the Cartesian coordinate system is:

[0023] (3)

[0024] Among them, is the three-axis component of the radiated magnetic field, which varies with time according to a quasi-sine law.

[0025] The extreme values in one cycle are represented by and specifically are:

[0026] (4)

[0027] (5)

[0028] (6)

[0029] First, consider the case of From (6), we can obtain:

[0030] (7)

[0031] Substituting (7) into (4) and (5), we can deduce:

[0032] (8)

[0033] (9)

[0034] Let , then there is . Similarly, let , there is . Substitute into (8) and (9), and square both ends of the equal sign, we can get:

[0035] (10)

[0036] (11)

[0037] Sum the above formula, we get:

[0038] (12)

[0039] Because , so (12) can be rewritten as: , where is the coefficient. By solving the above quartic equation in one variable, usually two non - negative solutions can be calculated. Substitute into the above formula, the distance between the mechanical antenna and the sensor can be obtained.

[0040] Furthermore, the deflection angle of the mechanical antenna in the coordinate system can also be calculated accordingly, which is:

[0041] (13)

[0042] The above analysis is for non - singular points. However, for singular points, their positions need to be further analyzed, which can be mainly divided into and two cases.

[0043] For the first case, , then the deflection angle can be any value. Under this condition, there is , then (4) and (5) can be rewritten as:

[0044] (14)

[0045] (15)

[0046] Therefore, the distance between the mechanical antenna and the sensor is:

[0047] (16)

[0048] For the second case , the mechanical antenna is located at on a plane. At this time , then (4) and (5) can be rewritten as:

[0049] (17)

[0050] (18)

[0051] Squaring both ends of the above formula and summing them up, we can get:

[0052] (19)

[0053] Correspondingly, the distance between the mechanical antenna and the sensor is:

[0054] (20)

[0055] Based on (17) and (18), the position declination angle can be expressed as:

[0056] (21)

[0057] That is:

[0058] (22)

[0059] So far, 8 possible positions of the mechanical antenna in the half-space under the condition or 5 possible positions of the mechanical antenna under the condition are obtained.

[0060] Step 2: From (3), it can be known that the real part of the three-axis components of the radiation magnetic field of the mechanical antenna is:

[0061] (23)

[0062] (24)

[0063] (25)

[0064] The imaginary part of the three-axis components of the radiation magnetic field data of the mechanical antenna is:

[0065] (26)

[0066] (27)

[0067] (28)

[0068] Among them, Indicates the azimuth angle of the mechanical antenna at different times The mechanical antenna is a low-frequency emission source and has at this time .

[0069] When the position parameters of the measurement point remain unchanged, The phase remains unchanged and is only related to the variable . Let respectively represent the azimuth angles when is at the extreme point, is the corresponding time. According to formulas (23)-(25), when the z-axis component is at the extreme point, there is , that is , . For , the azimuth angle can be expressed as:

[0070] (29)

[0071] (30)

[0072] According to the auxiliary angle formula, we get:

[0073] (31)

[0074] (32)

[0075] where and are variables related to .

[0076] To make reach the extreme point, it must satisfy:

[0077] (33)

[0078] (34)

[0079] Based on formulas (33) and (34), the final position inclination angle of the mechanical antenna is calculated as:

[0080] (35)

[0081] At this point, the incorrect antenna positions can be excluded, and the only true mechanical antenna position can be selected according to (35).

[0082] The content not detailedly described in the specification of the present invention belongs to the prior art well-known to those skilled in the art. Although, for the purpose of illustration, exemplary embodiments of the present invention have been described, those skilled in the art will understand that various modifications, additions, substitutions and other changes can be made in form and detail without departing from the scope and spirit of the invention disclosed in the appended claims. All such changes shall fall within the protection scope of the appended claims of the present invention, and each part of the product and each step in the method claimed by the present invention can be combined together in any combination form. Therefore, the description of the embodiments disclosed in the present invention is not intended to limit the scope of the present invention, but to describe the present invention. Accordingly, the scope of the present invention is not limited by the above embodiments, but is defined by the claims or their equivalents.

Claims

1. A linear single-point positioning method based on a permanent magnet mechanical antenna, characterized in that Including the following steps: Establish a Cartesian coordinate system with the triaxial magnetic field sensor as the origin, and the coordinate axis directions are the same as the sensor sensitive axes; Measure the radiation magnetic field data generated by a permanent magnet mechanical antenna with a known frequency and equivalent magnetic moment; Obtain multiple mutually symmetric uncertain positions in the half space based on the amplitude information of the measured radiation magnetic field data. The multiple mutually symmetric uncertain positions include 8 possible positions of the mechanical antenna under the condition that the extreme value of the z-axis component of the radiation magnetic field is zero, or 5 possible positions of the mechanical antenna under the condition that the extreme value of the z-axis component of the radiation magnetic field is not zero; Exclude the wrong positions according to the phase information of the measured radiation magnetic field data, and select the only correct position to complete the positioning.

2. A linear single-point positioning method based on a permanent magnet mechanical antenna according to claim 1, characterized in that The obtaining of the uncertain positions in the half space based on the amplitude information of the measured radiation magnetic field data includes: Radiation Magnetic Field of a Permanent Magnet Mechanical Antenna in a Cartesian Coordinate System is as follows: （3） Among them, are the three-axis components of the radiated magnetic field, which vary with time according to a quasi-sine law, and is the radiated magnetic field generated at any measurement point in space by the permanent magnet mechanical antenna in the spherical coordinate system, represents the radiated magnetic field and is the rotation matrix for coordinate transformation, Suppose The extreme value in a period is represented by When the following results are obtained in sequence: （7） （8） （9） Let the intermediate parameter , , substitute into (8) and (9), and we get: （12） When the deflection angle of the mechanical antenna position is: （13） Consider When the inclination angle of the mechanical antenna position there is At this time: （14） （15） At this time, the distance between the mechanical antenna and the sensor is: （16） Consider when the inclination angle of the mechanical antenna position and the mechanical antenna is located at on a plane at this time: （19） The distance between the mechanical antenna and the sensor is: （20） Then the deflection angle of the mechanical antenna at this time is expressed as: （22） Thus far, the 8 possible positions of the mechanical antenna in the half-space under the condition or the 5 possible positions of the mechanical antenna under the condition are obtained.

3. A linear single-point positioning method based on a permanent magnet mechanical antenna according to claim 1, characterized in that, The excluding of the wrong positions and the selection of the only correct position according to the phase information of the measured radiation magnetic field data includes calculating the real part and the imaginary part of the three-axis components of the mechanical antenna radiation magnetic field data; Let respectively represent the three-axis components of the radiated magnetic field when at the extreme point, the azimuth angle, is the corresponding moment. When the z-axis component is at the extreme point, there is . If we want to reach the extreme point, it must satisfy: （33） （34） Based on formulas (33) and (34), calculate the final position inclination angle of the mechanical antenna as: （35） Thus, the wrong antenna positions can be excluded, and the only real mechanical antenna position can be selected according to formula (35).

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