Unsigned electromagnetic positioning optimization method and system based on group symmetry

Abstract

The invention discloses an unsigned electromagnetic positioning optimization method and system based on group symmetry, and belongs to the technical field of wireless electromagnetic positioning. The method comprises the following steps: acquiring an absolute value of an induced magnetic field and a theoretical magnetic field to obtain 512 magnetic field symbol combinations; reducing the magnetic field symbols by using a magnetic field vector constraint condition to obtain 64 magnetic field symbol combinations; reducing the magnetic field symbols again by utilizing a magnetic field determinant constraint condition to obtain four magnetic field symbol combinations; and comparing the quadrant calculated by combining the four magnetic field symbols with the quadrant of the acceleration prediction magnetic field symbol to confirm the final magnetic field symbol, thereby solving the coordinate and attitude of the receiving module. According to the method, three schemes of magnetic field determinant constraint, magnetic field vector constraint and quadrant constraint are utilized, the magnetic field symbols are rapidly solved by combining the sequence of the three schemes, the coordinate solving period can be shortened to be within 2 ms, and compared with a traversal method, the efficiency is improved by nearly 12 times.

Description

Technical Field

[0001] The present invention relates to the technical field of wireless electromagnetic positioning, and in particular, to an unsigned electromagnetic positioning optimization method and system based on group symmetry. Background Art

[0002] Wireless alternating electromagnetic positioning generates an alternating magnetic field by passing an alternating current through a transmitting coil. The alternating magnetic field has stronger anti-interference ability compared with the traditional stable magnetic field. The receiving coil induces the alternating magnetic field to generate an induced electromotive force. Since the wireless electromagnetic field is continuously emitted, the actual phase difference between the transmitted magnetic field and the received induced magnetic field cannot be calculated, resulting in the inability to calculate the sign of the induced magnetic field amplitude. Without knowing the sign of the magnetic field amplitude, the coordinate sign of the tracked coil cannot be solved, and only the absolute value of the coordinate and the corresponding theoretical magnetic field can be obtained.

[0003] The three-axis transmitting coils respectively emit magnetic fields of different frequencies. After Fourier transform, the three-axis induction coils can obtain the absolute values of a total of nine magnetic field amplitudes. There are a total of 512 symbol combinations for the nine magnetic field amplitudes. Calculating by the traversal method has a large amount of calculation, which will affect the real-time performance of coordinate solving. Summary of the Invention

[0004] Other features and advantages of the present invention will be described in the following specification, and will be partially obvious from the specification, or understood by implementing the present invention. The objectives and other advantages of the present invention can be realized and obtained through the structures specifically pointed out in the specification and other specification drawings.

[0005] The objective of the present invention is to overcome the above deficiencies and provide an unsigned electromagnetic positioning optimization method and system based on group symmetry.

[0006] To achieve the above objective, the technical solution of the present invention is: an unsigned electromagnetic positioning optimization method based on group symmetry, including: Obtaining the absolute value of the induced magnetic field and the theoretical magnetic field to obtain 512 magnetic field symbol combinations; Reducing the magnetic field symbols using the magnetic field vector constraint condition to obtain 64 magnetic field symbol combinations; Reducing the magnetic field symbols again using the magnetic field determinant constraint condition to obtain 4 magnetic field symbol combinations; Comparing the quadrants calculated from the 4 magnetic field symbol combinations with the quadrant of the acceleration predicted magnetic field symbol to confirm the final magnetic field symbol, so as to solve the coordinates and attitude of the receiving module.

[0007] The present invention provides an unsigned electromagnetic positioning optimization method based on group symmetry, including: Obtaining the absolute value of the induced magnetic field and the theoretical magnetic field to obtain 512 magnetic field symbol combinations; Reduce the magnetic field symbols using the magnetic field determinant constraint conditions to obtain 32 combinations of magnetic field symbols; Reduce the magnetic field symbols again using the magnetic field vector constraint conditions to obtain 4 combinations of magnetic field symbols; Compare the quadrants calculated from the 4 combinations of magnetic field symbols with the quadrant of the predicted magnetic field of the acceleration to confirm the final magnetic field symbol.

[0008] In some embodiments, the induced magnetic field is obtained by applying drive currents of different frequencies to the transmitting coil and using Fourier transform to make the receiving coil sense 9 induced voltages with different amplitudes.

[0009] In some embodiments, the theoretical magnetic field is obtained based on calculations using the magnetic dipole model.

[0010] In some embodiments, the relationship between the induced magnetic field and the theoretical magnetic field is: , where, is the rotation matrix, is the theoretical magnetic field, is the induced magnetic field, and xyz represents the magnetic fields sensed by different axes of the receiving coil.

[0011] In some embodiments, the magnetic field vector constraint conditions are: , where, is the theoretical magnetic field vector is the angle between them, is the measured magnetic field is the angle between them.

[0012] In some embodiments, the magnetic field determinant constraint conditions are: .

[0013] In some embodiments, there are 16 combinations of magnetic field symbols for the magnetic field vector.

[0014] In some embodiments, there are 8 combinations of magnetic field symbols for the magnetic field determinant.

[0015] In some embodiments, the steps for reducing the magnetic field symbols using the magnetic field vector constraint conditions are as follows: Step 1, use to calculate the dot product of the theoretical magnetic field; Step 2, use , magnetic field to traverse 16 combinations of magnetic field vectors, where Dis a combination of multiple magnetic field symbols; Step 3, using Calculate the error between the dot product of the induced magnetic field and the dot product of the theoretical magnetic field; Step 4, using Return the magnetic field corresponding to the minimum error.

[0016] In some embodiments, the magnetic field symbols are reduced using the magnetic field determinant constraint condition. The specific steps are as follows: Step 1, using Calculate the determinant of the theoretical magnetic field; Step 2, using , , assign 8 combinations of magnetic field determinant symbols to the symbol combination with the minimum dot product, where C is a combination of 8 magnetic field symbols; Step 3, using Calculate the absolute value of the determinant error between the induced magnetic field determinant and the theoretical magnetic field determinant; Step 4, using , return the magnetic field corresponding to the minimum error.

[0017] The present invention also provides a group symmetry-based unsigned electromagnetic positioning optimization system, including: An acquisition module, which is used to acquire the absolute value of the induced magnetic field and the theoretical magnetic field to obtain 512 combinations of magnetic field symbols; A reduction module, which is used to reduce the magnetic field symbols using the magnetic field vector constraint condition to obtain 64 combinations of magnetic field symbols, and then reduce the magnetic field symbols using the magnetic field determinant constraint condition to obtain 4 combinations of magnetic field symbols; A comparison module, which is used to compare the quadrants calculated from the 4 combinations of magnetic field symbols with the quadrants of the acceleration prediction magnetic field symbols to confirm the final magnetic field symbols.

[0018] The present invention also provides a group symmetry-based unsigned electromagnetic positioning optimization system, including: An acquisition module, which is used to acquire the absolute value of the induced magnetic field and the theoretical magnetic field to obtain 512 combinations of magnetic field symbols; A reduction module, which is used to reduce the magnetic field symbols using the magnetic field determinant constraint condition to obtain 32 combinations of magnetic field symbols, and then reduce the magnetic field symbols using the magnetic field vector constraint condition to obtain 4 combinations of magnetic field symbols; A comparison module, which is used to compare the quadrants calculated from the 4 combinations of magnetic field symbols with the quadrants of the acceleration prediction magnetic field symbols to confirm the final magnetic field symbols.

[0019] In summary, the beneficial effects of the present invention are: The transmitting module sends magnetic fields of different frequencies through three coils, and the receiving coil is also a three-axis coil. The absolute values of nine magnetic field intensities and nine theoretical magnetic fields induced by the receiving coil are extracted through fast Fourier transform. Since the signs of the induced magnetic fields cannot be obtained, there are 512 sign combinations for the induced magnetic fields. The magnetic field signs are reduced using the magnetic field vector constraint condition to obtain 64 magnetic field sign combinations; the magnetic field signs are further reduced using the magnetic field determinant constraint condition to obtain 4 magnetic field sign combinations; the quadrants calculated from the 4 magnetic field sign combinations are compared with the quadrants of the acceleration predicted magnetic field signs to confirm the final magnetic field signs. The present invention utilizes three schemes of magnetic field determinant constraint, magnetic field vector constraint, and quadrant constraint, and realizes the rapid solution of magnetic field signs by combining the order of the three schemes, which can reduce the coordinate solution period to within 2 ms, and the efficiency is increased by nearly 12 times compared with the traversal method. After obtaining the signed magnetic field signs, the coordinates and attitude angles of the receiving coil can be calculated through the magnetic dipole model.

[0020] The present invention can rapidly screen 512 magnetic field signs through the principle of symmetry. The present invention can reduce the 512 possible magnetic field signs to 64 through the vector angle, and then reduce the 64 magnetic field signs to 4 through the determinant, and finally determine the final magnetic field signs according to the quadrant. In addition, the present invention can also first reduce the 512 magnetic field signs to 32 through the determinant method, then reduce the 32 to 4 through the vector angle, and finally confirm the final magnetic field signs according to the quadrant.

[0021] It should be understood that the above general description and the following detailed description are only exemplary and explanatory, and cannot limit the present disclosure.

[0022] Undoubtedly, such objects of the present invention and other objects will become more apparent after the details of the preferred embodiments described in multiple drawings and illustrations below.

[0023] To make the above and other objects, features, and advantages of the present invention more obvious and understandable, one or several preferred embodiments are specifically exemplified below, and in conjunction with the accompanying drawings, the detailed description is as follows. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The drawings are used to provide a further understanding of the present invention, and constitute a part of the specification. They are used together with the embodiments of the present invention to explain the present invention, and do not constitute a limitation to the present invention.

[0025] In the drawings, the same components are denoted by the same reference numerals, and the drawings are schematic and not necessarily drawn to actual scale.

[0026] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following briefly introduces the drawings required for the description of the embodiments or the prior art. Obviously, the drawings in the following description are only one or several embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on such drawings.

[0027] Figure 1 It is a schematic diagram of electromagnetic positioning; Figure 2 It is a schematic diagram of the ideal magnetic field and the measured magnetic field; Figure 3 It is a schematic diagram of the included angle of the magnetic field vectors; Figure 4 It is a schematic diagram of the symbol combination of the magnetic field vectors; Figure 5 It is a schematic diagram of the symbol combination of the magnetic field determinant; Figure 6 It is a schematic diagram of the symbol combination of the four quadrants of the magnetic field; Figure 7 It is a schematic flowchart of the present invention Figure 1 ; Figure 8 It is a schematic flowchart of the present invention Figure 2 . Specific embodiments

[0028] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the following further details the present invention in conjunction with specific embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention, but not to limit the present invention.

[0029] In addition, in the description of the present invention, it should be understood that the orientation or positional relationship indicated by the terms "center", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "axial", "radial", "circumferential", etc. is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the present invention.

[0030] In the present invention, unless otherwise clearly specified or limited, the terms "installed", "connected", "connected", "fixed", etc. shall be understood in a broad sense. For example, it may be a fixed connection, a detachable connection, or integrated; it may be directly connected or indirectly connected through an intermediate medium, and it may be the communication inside two components or the interaction relationship between two components. However, indicating a direct connection means that there is no connection relationship constructed through a transition structure between the two connected main bodies, and they are only connected through the connection structure to form a whole. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0031] In the present invention, unless otherwise clearly specified or limited, the first feature being "above" or "below" the second feature may be that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. In the description of this specification, the description referring to terms such as "one embodiment", "some embodiments", "examples", "specific examples", or "some examples" means that the specific features, structures, materials, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic expressions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described can be combined in a suitable manner in any one or more embodiments or examples.

[0032] Referring to Figures 1 - 8 , according to some embodiments of the present invention, the present invention provides an unsigned electromagnetic positioning optimization method based on group symmetry. The method includes the following steps: Obtain the absolute value of the induced magnetic field and the theoretical magnetic field to obtain 512 magnetic field symbol combinations; Use the magnetic field vector constraint condition to reduce the magnetic field symbols to obtain 64 magnetic field symbol combinations; Use the magnetic field determinant constraint condition to further reduce the magnetic field symbols to obtain 4 magnetic field symbol combinations; Compare the quadrants calculated from the 4 magnetic field symbol combinations with the quadrant of the acceleration predicted magnetic field symbol to confirm the final magnetic field symbol.

[0033] According to some embodiments of the present invention, the present invention provides an unsigned electromagnetic positioning optimization method based on group symmetry. The method includes: Obtain the absolute value of the induced magnetic field and the theoretical magnetic field to obtain 512 magnetic field symbol combinations; Use the magnetic field determinant constraint condition to reduce the magnetic field symbols to obtain 32 magnetic field symbol combinations; Use the magnetic field vector constraint condition to further reduce the magnetic field symbols to obtain 4 magnetic field symbol combinations; Compare the quadrants calculated from the combination of the four magnetic field symbols with the quadrants of the acceleration prediction magnetic field symbols to confirm the final magnetic field symbol.

[0034] According to some embodiments of the present invention, optionally, the acquisition of the induced magnetic field is obtained by applying drive currents of different frequencies to the transmitting coil and using Fourier transform to make the receiving coil sense nine different amplitude induced voltages.

[0035] According to some embodiments of the present invention, optionally, the acquisition of the theoretical magnetic field is calculated based on the magnetic dipole model.

[0036] According to some embodiments of the present invention, optionally, the relationship between the induced magnetic field and the theoretical magnetic field is: , wherein, is the rotation matrix, is the theoretical magnetic field, is the induced magnetic field, and xyz are the magnetic fields induced by the receiving coil on different axes.

[0037] According to some embodiments of the present invention, optionally, the magnetic field vector constraint condition is: , wherein, is the theoretical magnetic field vector is the angle between each other, is the measured magnetic field is the angle between each other.

[0038] According to some embodiments of the present invention, optionally, the magnetic field determinant constraint condition is: .

[0039] According to some embodiments of the present invention, optionally, there are 16 combinations of magnetic field symbols of the magnetic field vector.

[0040] According to some embodiments of the present invention, optionally, there are 8 combinations of magnetic field symbols of the magnetic field determinant.

[0041] According to some embodiments of the present invention, optionally, the reduction of the magnetic field symbol using the magnetic field vector constraint condition is as follows: Step 1, use to calculate the dot product of the theoretical magnetic fields; wherein, is the theoretical magnetic field induced by the receiving coil at the frequency, is the theoretical magnetic field induced by the receiving coil at the frequency, is the theoretical magnetic field induced by the receiving coil at the frequency, are the three operating frequencies of the system.

[0042] Step 2: Use to traverse the combinations of 16 magnetic field vectors with the magnetic field , where D is a combination of multiple magnetic field symbols, is the Figure 4 th of the 16 magnetic symbol combinations shown, is the induced magnetic field of the receiving module, is in the form of pseudocode, indicating that starting from the 0th, it traverses to the 15th, is an intermediate variable used to represent the measured magnetic fields of different symbols.

[0043] Step 3: Use to calculate the error between the dot product of the induced magnetic field and the dot product of the theoretical magnetic field; where is the magnetic field corresponding to the frequency of the magnetic field, is the magnetic field corresponding to the frequency of the magnetic field, is the magnetic field corresponding to the frequency of the magnetic field.

[0044] Step 4: Use to return the magnetic field corresponding to the minimum error.

[0045] According to some embodiments of the present invention, optionally, use the magnetic field determinant constraint condition to reduce the magnetic field symbols, and the specific steps are as follows: Step 1: Use to calculate the determinant of the theoretical magnetic field; where is the calculation result of the determinant of the theoretical magnetic field, is to perform a column calculation on the theoretical magnetic field.

[0046] Step 2: Use , , and assign 8 combinations of magnetic field determinant symbols to the symbol combination with the minimum dot product, where C is a combination of 8 magnetic field symbols; where is the calculation result of the determinant of the magnetic field under different symbol combinations, is the magnetic field with the minimum angular error among the 16 symbol combinations calculated in Step 1.

[0047] Step 3: Use to calculate the absolute value of the error between the determinant of the induced magnetic field and the determinant of the theoretical magnetic field; Step 4: Use to return the magnetic field corresponding to the minimum error.

[0048] According to some embodiments of the present invention, the present invention provides a group-symmetry-based unsigned electromagnetic positioning optimization system. The system includes an acquisition module, a reduction module, and a comparison module. The acquisition module is used to acquire the absolute value of the induced magnetic field and the theoretical magnetic field to obtain 512 magnetic field symbol combinations; the reduction module is used to reduce the magnetic field symbols using the magnetic field vector constraint condition to obtain 64 magnetic field symbol combinations, and then reduce the magnetic field symbols using the magnetic field determinant constraint condition to obtain 4 magnetic field symbol combinations; the comparison module is used to compare the quadrants calculated from the 4 magnetic field symbol combinations with the quadrant of the acceleration prediction magnetic field symbol to confirm the final magnetic field symbol.

[0049] According to some embodiments of the present invention, the present invention provides a group-symmetry-based unsigned electromagnetic positioning optimization system. The system includes an acquisition module, a reduction module, and a comparison module. The acquisition module is used to acquire the absolute value of the induced magnetic field and the theoretical magnetic field to obtain 512 magnetic field symbol combinations; the reduction module is used to reduce the magnetic field symbols using the magnetic field determinant constraint condition to obtain 32 magnetic field symbol combinations, and then reduce the magnetic field symbols using the magnetic field vector constraint condition to obtain 4 magnetic field symbol combinations; the comparison module is used to compare the quadrants calculated from the 4 magnetic field symbol combinations with the quadrant of the acceleration prediction magnetic field symbol to confirm the final magnetic field symbol.

[0050] Example 1 This example provides a group-symmetry-based unsigned electromagnetic positioning optimization method. The method includes the following steps: Acquire the absolute value of the induced magnetic field and the theoretical magnetic field to obtain 512 magnetic field symbol combinations; Reduce the magnetic field symbols using the magnetic field vector constraint condition to obtain 64 magnetic field symbol combinations; Reduce the magnetic field symbols again using the magnetic field determinant constraint condition to obtain 4 magnetic field symbol combinations; Compare the quadrants calculated from the 4 magnetic field symbol combinations with the quadrant of the acceleration prediction magnetic field symbol to confirm the final magnetic field symbol.

[0051] The specific steps of the method are as follows: By applying drive currents of different frequencies (F1, F2, F3) to the transmitting coils (T1, T2, T3) and using Fourier transform to make the receiving coils (R1, R2, R3) sense 9 different amplitude induced voltages to obtain the absolute value of the induced magnetic field and calculating the theoretical magnetic field based on the magnetic dipole model to obtain 512 magnetic field symbol combinations; Using calculate the dot product of the theoretical magnetic fields; Using , magnetic field Traverse the combinations of 16 magnetic field vectors, where D are multiple combinations of magnetic field symbols; Use to calculate the error between the dot product of the induced magnetic field and the dot product of the theoretical magnetic field; Use to return the magnetic field corresponding to the minimum error; Then use to calculate the determinant of the theoretical magnetic field; Use , , assign 8 combinations of determinant symbols to the symbol combination with the minimum dot product; Use to calculate the absolute value of the determinant error between the induced magnetic field determinant and the theoretical magnetic field determinant; Use to return the magnetic field corresponding to the minimum error, and finally 4 symbol possibilities remain.

[0052] The quadrant of the next frame coordinate can be obtained by , comparing the quadrants calculated from the four magnetic field symbols with the quadrant symbols predicted by the acceleration to find the consistent electromagnetic symbols.

[0053] Embodiment 2 This embodiment provides a signless electromagnetic positioning optimization method based on group symmetry. The method includes: Obtain the absolute value of the induced magnetic field and the theoretical magnetic field to obtain 512 combinations of magnetic field symbols; Use the magnetic field determinant constraint condition to reduce the magnetic field symbols to obtain 32 combinations of magnetic field symbols; Use the magnetic field vector constraint condition to further reduce the magnetic field symbols to obtain 4 combinations of magnetic field symbols; Compare the quadrants calculated from the 4 combinations of magnetic field symbols with the quadrants of the acceleration predicted magnetic field symbols to confirm the final magnetic field symbols.

[0054] The specific steps of the method are as follows: By turning on the drive currents of different frequencies (F1, F2, F3) on the transmitting coils (T1, T2, T3) and using Fourier transform to make the receiving coils (R1, R2, R3) sense 9 different amplitude induced voltages to obtain the absolute value of the induced magnetic field , calculate the theoretical magnetic field based on the magnetic dipole model to obtain 512 combinations of magnetic field symbols; Use to calculate the determinant of the theoretical magnetic field; Use , , assign 8 determinant symbol combinations to the symbol combination with the smallest dot product; Use , calculate the absolute value of the determinant error between the induced magnetic field determinant and the theoretical magnetic field determinant, Use , return the magnetic field corresponding to the minimum error; Then use , calculate the dot product of the theoretical magnetic field; Use , magnetic field Traverse the combinations of 16 magnetic field vectors; Use , calculate the error between the dot product of the induced magnetic field and the dot product of the theoretical magnetic field, Use , return the magnetic field corresponding to the minimum error, and the remaining 4 magnetic field symbol combinations; The quadrant of the next frame coordinate can be obtained by , compare the quadrant symbols calculated by the four magnetic field symbols with the quadrant symbols predicted by the acceleration, and find the consistent magnetic field symbols. Among them, is the coordinate at time t; is the coordinate at time t - 1; is the velocity; is the time interval for magnetic field acquisition......; is the acceleration.

[0055] It should be noted that many specific details are described above to fully understand the present invention. However, the present invention can also be implemented in other ways different from those described herein. Therefore, the protection scope of the present invention is not limited by the specific embodiments disclosed below.

Claims

1. An unsigned electromagnetic positioning optimization method based on group symmetry, characterized in that Including: Obtain the absolute value of the induced magnetic field and the theoretical magnetic field to obtain 512 combinations of magnetic field symbols; Reduce the magnetic field symbols using the magnetic field vector constraint conditions to obtain 64 combinations of magnetic field symbols; Reduce the magnetic field symbols again using the magnetic field determinant constraint conditions to obtain 4 combinations of magnetic field symbols; Compare the quadrants calculated from the 4 combinations of magnetic field symbols with the quadrant of the acceleration-predicted magnetic field symbol to confirm the final magnetic field symbol.

2. An unsigned electromagnetic positioning optimization method based on group symmetry, characterized in that, Including: Obtain the absolute value of the induced magnetic field and the theoretical magnetic field to obtain 512 combinations of magnetic field symbols; Reduce the magnetic field symbols using the magnetic field determinant constraint conditions to obtain 32 combinations of magnetic field symbols; Reduce the magnetic field symbols again using the magnetic field vector constraint conditions to obtain 4 combinations of magnetic field symbols; Compare the quadrants calculated from the 4 combinations of magnetic field symbols with the quadrant of the acceleration-predicted magnetic field symbol to confirm the final magnetic field symbol.

3. The unsigned electromagnetic positioning optimization method based on group symmetry according to claim 1 or 2, characterized in that The acquisition of the induced magnetic field is obtained by applying drive currents of different frequencies to the transmitting coil and using Fourier transform to make the receiving coil sense 9 different amplitude induced voltages.

4. The unsigned electromagnetic positioning optimization method based on group symmetry according to claim 1 or 2, characterized in that, The acquisition of the theoretical magnetic field is calculated based on the magnetic dipole model.

5. The unsigned electromagnetic positioning optimization method based on group symmetry according to claim 1 or 2, characterized in that The relationship between the induced magnetic field and the theoretical magnetic field is: ， In the formula, is the rotation matrix, is the theoretical magnetic field, is the induced magnetic field, and xyz represents the magnetic fields induced by the receiving coil on different axes.

6. The unsigned electromagnetic positioning optimization method based on group symmetry according to claim 5, characterized in that The magnetic field vector constraint condition is: ， In the formula, is the mutual angle between the theoretical magnetic field vectors , is the measured magnetic field is the mutual angle between them.

7. The unsigned electromagnetic positioning optimization method based on group symmetry according to claim 5, characterized in that The magnetic field determinant constraint condition is: 。 8. The unsigned electromagnetic positioning optimization method based on group symmetry according to claim 1 or 2, characterized in that There are 16 combinations of magnetic field symbols for the magnetic field vector.

9. The unsigned electromagnetic positioning optimization method based on group symmetry according to claim 1 or 2, characterized in that There are 8 combinations of magnetic field symbols for the magnetic field determinant.

10. The unsigned electromagnetic positioning optimization method based on group symmetry according to claim 1 or 2, characterized in that The specific steps for reducing the magnetic field symbols using the magnetic field vector constraint conditions are: Step 1, using calculate the dot product of the theoretical magnetic fields; where is the theoretical magnetic field of the receiving coil for the induced frequency, is the theoretical magnetic field of the receiving coil for the induced frequency, is the theoretical magnetic field of the receiving coil for the induced frequency, are the three operating frequencies of the system; Step 2, using , the magnetic field traverses the combinations of 16 magnetic field vectors, where D is a combination of multiple magnetic field symbols, is the i-th of 16 magnetic symbol combinations, is the induced magnetic field of the receiving module, is the expression form of the pseudocode, indicating that it starts from the 0th and traverses to the 15th, is an intermediate variable used to represent the measured magnetic fields of different symbols; Step 3, using to calculate the error between the dot product of the induced magnetic field and the dot product of the theoretical magnetic field; where is the magnetic field corresponding to the magnetic field frequency, is the magnetic field corresponding to the magnetic field frequency, is the magnetic field corresponding to the magnetic field frequency; Step 4, using return the magnetic field corresponding to the minimum error.

11. The unsigned electromagnetic positioning optimization method based on group symmetry according to claim 1 or 2, characterized in that The specific steps for reducing the magnetic field symbols using the magnetic field determinant constraint conditions are: Step 1, using calculate the determinant of the theoretical magnetic field; where is the calculation result of the determinant of the theoretical magnetic field, is to perform a column calculation on the theoretical magnetic field; Step 2, using , , assign 8 combinations of magnetic field determinant symbols to the symbol combination with the smallest dot product, where C is the combination of 8 magnetic field symbols; among them, is the determinant calculation result of the magnetic field under different symbol combinations, is the magnetic field with the smallest angle error among the 16 symbol combinations calculated in Step 1; Step 3, using , calculate the error between the dot product of the induced magnetic field and the dot product of the theoretical magnetic field; Step 4, using , return the magnetic field corresponding to the minimum error.

12. An unsigned electromagnetic positioning optimization system based on group symmetry, characterized in that, Including: An acquisition module for obtaining the absolute value of the induced magnetic field and the theoretical magnetic field to obtain 512 combinations of magnetic field symbols; A reduction module for reducing the magnetic field symbols using the magnetic field vector constraint conditions to obtain 64 combinations of magnetic field symbols, and then reducing the magnetic field symbols using the magnetic field determinant constraint conditions to obtain 4 combinations of magnetic field symbols; A comparison module for comparing the quadrants calculated from the 4 combinations of magnetic field symbols with the quadrant of the acceleration-predicted magnetic field symbol to confirm the final magnetic field symbol.

13. An unsigned electromagnetic positioning optimization system based on group symmetry, characterized in that, Including: An acquisition module for obtaining the absolute value of the induced magnetic field and the theoretical magnetic field to obtain 512 combinations of magnetic field symbols; A reduction module for reducing the magnetic field symbols using the magnetic field determinant constraint conditions to obtain 32 combinations of magnetic field symbols, and then reducing the magnetic field symbols using the magnetic field vector constraint conditions to obtain 4 combinations of magnetic field symbols; A comparison module for comparing the quadrants calculated from the 4 combinations of magnetic field symbols with the quadrant of the acceleration-predicted magnetic field symbol to confirm the final magnetic field symbol.

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