Aviation magnetic survey compensation method and system for fixed-wing aircraft

Abstract

The invention discloses an aviation magnetic survey compensation method and system for a fixed-wing aircraft, and the method comprises the steps: carrying out the calibration flight of the aircraft, and obtaining the related data of magnetic compensation in real time; secondly, based on magnetic compensation related data, an improved model based on a T-L model is established; and then magnetic compensation related data is applied to the improved model and then is processed, and a magnetic compensation coefficient is calculated by an improved truncated singular value method based on a crayfish optimization algorithm. And finally, separating the magnetic interference data by using the magnetic compensation coefficient to obtain normal magnetic induction data. According to the invention, the precision of the compensated magnetic field data is improved, and the environmental interference in the magnetic field data acquisition process is effectively removed.

Description

Technical Field

[0001] The invention relates to the technical field of aeromagnetic measurement, and in particular to an aeromagnetic measurement compensation method and system for fixed-wing aircraft. Background Art

[0002] Aeromagnetic survey technology is an important means of geophysical exploration, which is widely used in shipwreck detection, unexploded ordnance detection, and submarine pipeline or cable inspection. However, in the process of aeromagnetic survey, since the aircraft contains ferromagnetic materials, an interfering magnetic field will appear during the flight. The interfering magnetic field is much larger than the magnetic anomaly signal, which can easily cause the magnetic anomaly signal to be submerged in the interfering magnetic field. Therefore, extracting and eliminating the interfering magnetic field has become a key issue. The solution to this problem is called aeromagnetic compensation technology.

[0003] The earliest aeromagnetic compensation model was proposed by Tolles and Lawson in the 1940s. They analyzed the relationship between the interference magnetic field of the flight platform and the flight direction of the flight platform, and divided the interference magnetic field of the flight platform into a constant magnetic field, an induced magnetic field, and an eddy current magnetic field. The constant magnetic field is mainly caused by the inherent magnetism of the ferromagnetic components in the flight platform, the induced magnetic field is mainly generated by the magnetization of the soft iron material in the flight platform by the earth's magnetic field, and the eddy current magnetic field is mainly generated by the magnetic flux variable caused by the change in the attitude of the flight platform. In 1961, Leliak established a general aeromagnetic compensation model based on the research of Tolles and Lawson, namely the TL model. The method for aeromagnetic compensation is to solve the linear regression equation formed by the model to obtain the compensation coefficient.

[0004] However, fixed-wing aircraft have complex magnetic interference caused by current during flight, including the induced current generated by the sensor connecting rod and the metal layer on the aircraft surface during flight, as well as the working current of the aircraft's internal equipment. Existing research usually uses neural networks to solve this problem, but its generalization ability is insufficient. Some studies only analyze the working current of some equipment in the aircraft, while ignoring the influence of other currents, resulting in insufficient compensation accuracy. Moreover, in the actual calculation of the compensation coefficient, the aeromagnetic compensation model has complex collinearity problems, which will also affect the compensation effect. Therefore, it is necessary to improve the TL model to solve the problem of interfering magnetic fields caused by current, and propose a new calculation method to solve its complex collinearity problem. Summary of the invention

[0005] Based on the above situation, the purpose of the present invention is to provide a fixed-wing aircraft aeromagnetic compensation method and system, which analyzes and optimizes the aeromagnetic compensation process, proposes an improved aeromagnetic compensation modeling method, establishes a new aeromagnetic compensation model, and also proposes an improved truncated singular value method for determining parameters using a crayfish optimization algorithm, which has the advantages of high compensation accuracy and easy modeling.

[0006] To achieve the above object, the present invention adopts the following technical solution: a fixed-wing aircraft aeromagnetic measurement compensation method, comprising:

[0007] The aircraft performs a calibration flight and obtains magnetic compensation related data in real time; the magnetic compensation related data includes three-component fluxgate data obtained by a three-component fluxgate magnetometer, total magnetic field data obtained by a scalar magnetometer, current data of in-flight equipment, and aircraft attitude data obtained by an attitude instrument;

[0008] Based on the magnetic compensation related data, an improved model based on the TL model is established;

[0009] The magnetic compensation related data are applied to the improved model for processing, and then the magnetic compensation coefficient is calculated; wherein the magnetic compensation coefficient is calculated by an improved truncated singular value method based on the crayfish optimization algorithm, which is used to solve the complex collinearity problem caused by the extended term of the improved model;

[0010] The magnetic compensation coefficient is used to separate the magnetic interference data and obtain normal magnetic induction data.

[0011] Preferably, an improved model based on the TL model is established, including:

[0012] Based on the constant interference magnetic field, induced interference magnetic field and eddy current interference magnetic field generated by the aircraft itself under the influence of the geomagnetic field, a TL model is established. The model is expressed as follows:

[0013]

[0014] Among them B d is the total interference magnetic field generated by the aircraft itself under the influence of the geomagnetic field, B p is a constant interfering magnetic field, B i To induce interference magnetic field, B e is the eddy current interference magnetic field, h i is the direction cosine of the angle between the aircraft and the Earth's magnetic field measured by the three-component fluxgate magnetometer, h′ i is the first-order derivative of its direction cosine, a i , b ij and c ij is the compensation coefficient to be determined;

[0015] Based on the interference magnetic field excited by various currents generated by the aircraft in the flight environment, the compensation model extension item B is established c ;

[0016] Based on the induction interference magnetic field and eddy current interference magnetic field generated by the interference magnetic field excited by the current, the compensation model extension item B is established cd ;

[0017] The TL model and compensation model are extended by term B c and B cd After merging, the improved model is as follows:

[0018] B IMP =B d +B c +B cd

[0019] Among them, B IMP is the total interfering magnetic field.

[0020] Preferably, the magnetic compensation related data is applied to the improved model and then processed, including:

[0021] The three-component fluxgate data, the current data of the in-flight equipment and the aircraft attitude data obtained by the attitude instrument are applied to the improved model to obtain the improved model data, and the total magnetic field data and the improved model data are filtered. The filter is selected as a bandpass filter, and its lower limit cutoff frequency and upper limit cutoff frequency need to be obtained after the spectrum analysis of the total magnetic field data. The first peak at the low frequency is the geomagnetic field, the lower limit cutoff frequency needs to be higher than the geomagnetic field frequency, and the upper limit cutoff frequency is selected as 0.9Hz to obtain the total interference magnetic field B after filtering. IMP and are the total magnetic field data B measured by the scalar magnetometer t .

[0022] Preferably, calculating the magnetic compensation coefficient includes:

[0023] According to the total interference magnetic field B after filtering IMP and are the total magnetic field data B measured by the scalar magnetometer t The improved model based on the TL model is solved using the improved truncated singular value method to obtain the magnetic compensation coefficient. First, the improved model is subjected to singular value decomposition. u i is the left singular vector, σ i is a singular value, v i is a right singular vector, and the improved truncated singular value method is calculated as follows:

[0024]

[0025] Where χ is the magnetic compensation coefficient, s i The expression is as follows:

[0026]

[0027] Where k is the number of singular values ​​retained, λ is the constraint coefficient, and the values ​​of k and λ are determined by the crayfish optimization algorithm.

[0028] Preferably, calculating and separating magnetic interference data includes:

[0029] The calculated magnetic compensation coefficient is substituted into the improved model based on the TL model to obtain the magnetic interference data caused by various currents such as the aircraft itself, the metal induced current on the surface of the aircraft during flight, and the working current of the internal equipment. The normal magnetic induction data can be obtained by subtracting the magnetic interference data from the total magnetic field data.

[0030] Preferably, the compensation model extension items are established based on the interference magnetic fields excited by various currents generated by the aircraft in the flight environment, including:

[0031] The compensation model extension is expressed as follows:

[0032]

[0033] Among them C i is the induced current of the surface metal and sensor connecting rod during the flight of the aircraft, as well as the working current value of the equipment inside the aircraft. (sinθ)' represents the first-order derivative of sinθ. n is the number of equipment inside the aircraft. d i d ij is the compensation coefficient, θ and ψ are the attitude instrument pitch angle and attitude instrument roll angle in the aircraft attitude data respectively.

[0034] Preferably, the compensation model extension item is established based on the induced interference magnetic field and eddy current interference magnetic field further generated by the interference magnetic field excited by the current, including:

[0035] The compensation model extension is expressed as follows:

[0036]

[0037] Among them B ci is the current induced interference magnetic field, B ce is the eddy current interfering with the magnetic field, e i 、e ij and f ij is the compensation coefficient to be determined.

[0038] Preferably, the number of singular value retention and constraint coefficients of the improved truncated singular value method are determined by the crayfish optimization algorithm, including:

[0039] The error formula of the crayfish optimization algorithm is as follows:

[0040]

[0041] Where o is the error coefficient, B t is the total magnetic field data measured by the scalar magnetometer; ||·|| is the first-order norm; the crayfish optimization algorithm is used to determine the parameters k and λ of the improved truncated singular value method, that is, the values ​​of the parameters when the error coefficient o is minimized.

[0042] An aeromagnetic compensation system for fixed-wing aircraft, comprising:

[0043] The magnetic induction data collection module is used to obtain magnetic compensation related data in real time, including three-component fluxgate data, total magnetic field data, current data of on-board equipment, and aircraft attitude data obtained by the attitude instrument.

[0044] The model construction module is used to establish an improved model based on the TL model based on magnetic compensation related data.

[0045] The data processing module applies the three-component fluxgate data, the current data of the on-board equipment and the aircraft attitude data to the improved model, and performs filtering on the total magnetic field data and the data output by the improved model.

[0046] The calculation and processing module calculates the magnetic compensation coefficient based on the filtered data by the improved truncated singular value method of the crayfish optimization algorithm, separates the magnetic interference data, and obtains the normal magnetic induction data.

[0047] The output module is used to output the normal magnetic induction data obtained by the calculation and processing module.

[0048] On the basis of the above technical scheme, compared with the prior art, the advantages of the present invention are: taking into account the complex magnetic interference generated by current in the flight of fixed-wing aircraft, the TL model is improved, the accuracy of the compensated magnetic field data is improved, and the environmental interference in the magnetic field data acquisition process is effectively removed. At the same time, multiple current influences are modeled, the generalization ability of the model is enhanced, and the truncated singular value algorithm process is analyzed and optimized for the complex collinearity problem caused by model expansion, and the crayfish optimization algorithm is used to further improve the estimation accuracy of the magnetic compensation coefficient. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] Figure 1 is a flow chart according to the invention;

[0050] Figure 2 is a structural diagram according to the invention;

[0051] Figure 3 Schematic diagram of the total magnetic field comparison before and after compensation;

[0052] Figure 4 Schematic diagram of the total magnetic anomaly field comparison before and after compensation. DETAILED DESCRIPTION

[0053] In order to make the purpose, technical solution and advantages of the embodiments of the present application clearer, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of this application.

[0054] In a preferred embodiment of the present invention, a fixed-wing aircraft aeromagnetic measurement compensation method is provided. Figure 1 As shown, including:

[0055] A calibration flight is performed to obtain magnetic compensation related data in real time; the magnetic compensation related data includes three-component fluxgate data obtained by a three-component fluxgate magnetometer, total magnetic field data obtained by a scalar magnetometer, current data of in-flight equipment, and aircraft attitude data obtained by an attitude instrument.

[0056] An improved model based on the TL model is established; wherein the improved model needs to use magnetic compensation related data for modeling, and the specific model is as follows:

[0057]

[0058] Among them, B IMP is the total interfering magnetic field, h i is the direction cosine, h′ i is the first-order derivative of the direction cosine, θ is the pitch angle of the attitude instrument, ψ is the roll angle of the attitude instrument, C i is the working current value of the equipment inside the machine, C′ i is the first-order derivative of the working current value of the equipment inside the machine, a i 、b ij 、c ij d ij and e ji is the compensation coefficient to be determined.

[0059] The traditional TL model only includes the first three items of the improved aeromagnetic compensation model. Considering the complex magnetic interference generated by the current in the fixed-wing aircraft during flight, a specific analysis can be divided into the magnetic interference caused by the induced current on the surface metal outer layer and the sensor connecting rod during the flight of the fixed-wing aircraft and the working current of the aircraft's internal equipment. This magnetic interference will further generate induced magnetic fields and eddy current magnetic fields to cause magnetic interference. Existing research has only focused on the interference caused by some equipment inside the aircraft or ignored the further interference caused by the current magnetic interference. The improved aeromagnetic compensation model in the present invention can be obtained by fully modeling the complex magnetic interference generated by these currents, which improves the accuracy of the magnetic field data after compensation, effectively removes the environmental interference in the process of magnetic field data acquisition, and enhances the generalization ability of the model.

[0060] The direction cosines are calculated as follows:

[0061]

[0062]

[0063]

[0064] Where T x 、T y and T z These are the data measured by a three-component fluxgate magnetometer.

[0065] Perform spectrum analysis on the total magnetic field data, determine the lower cutoff frequency as the peak inflection point of the total magnetic field data spectrum, filter the total magnetic field data and the improved model data to remove the interference of the background geomagnetic field;

[0066] The improved truncated singular value method is used to solve the improved model based on the TL model to obtain the magnetic compensation coefficient. First, the improved model is subjected to singular value decomposition. The calculation method of the improved truncated singular value method is as follows:

[0067]

[0068] Where χ is the magnetic compensation coefficient. The improved truncated singular value algorithm combines Tikhonov regularization and truncated singular value algorithm, and uses the regularization parameter to correct the smaller singular values, which effectively improves the data accuracy.

[0069] Specifically, i The expression is as follows:

[0070]

[0071] Where λ is the constraint coefficient. Since the improved truncated singular value algorithm contains two parameters, they need to be estimated. The traditional L-curve method is difficult to use for dual-parameter estimation. Therefore, the values ​​of k and λ will be determined by referring to the crayfish optimization algorithm. The crayfish optimization algorithm simulates the foraging behavior of crayfish and has strong global search capabilities and fast convergence speed. Using the crayfish optimization algorithm for parameter estimation can effectively integrate the influence of the two parameters on the aeromagnetic compensation model and achieve better results.

[0072] Specifically, the crayfish optimization algorithm selects parameters including:

[0073] Step 1: Initialize the population and calculate the population fitness to obtain the optimal position X obtained by the number of iterations. G and the optimal position X obtained after updating the previous generation population L , as follows:

[0074] X ij =lb j +(ub j -lb j )rand

[0075] Where X ij is a candidate solution, lb is the lower bound, ub is the upper bound, and rand is a random number in [0,1]. The selection rules of lb and ub in the present invention are as follows:

[0076] lb=σ k-1

[0077] ub=σ k

[0078] The current population fitness is calculated according to the error formula, as follows:

[0079]

[0080] Where o is the error coefficient, B t is the total magnetic field data measured by the scalar magnetometer; ||·|| is the first-order norm; find the candidate solution with the smallest error coefficient and select it as the optimal position.

[0081] Step 2: Summer heat escape stage: when the temperature is above 30 degrees, crayfish will enter the cave to escape the heat. The cave location X is obtained according to the optimal location. sha de .

[0082] Step 3: When the temperature is greater than 30 degrees, calculate and obtain the candidate solution for the next iteration and proceed to step 6.

[0083] Step 4: When the temperature is ≤30 degrees, the crayfish enters the foraging stage, and the food intake p and food size Q are calculated.

[0084] Step five: the crayfish will tear up the food or eat it before entering step six.

[0085] Step 6: If the current number of iterations is less than the maximum number of iterations, return to step 2; if not, output the individual with the best position, which is the parameter selection of the improved truncated singular value algorithm.

[0086] Since some of the formulas are commonly used, they are not described in detail here; considering that the parameters selected by the optimization algorithm only represent the least squares method with a smaller error, it is impossible to select parameters that are better than the aeromagnetic compensation model, so the standard deviation of the compensated magnetic anomaly data is introduced as the judgment standard. When different k values ​​are selected, the error coefficient and the standard deviation of the compensated magnetic anomaly data are comprehensively compared, and the parameters with smaller error coefficient and standard deviation are selected to calculate the magnetic compensation coefficient.

[0087] The magnetic compensation coefficient is used to separate the magnetic interference data and obtain normal magnetic induction data.

[0088] Specifically, the solved compensation coefficient is substituted into the improved aeromagnetic compensation model to calculate the interfering magnetic field data. The interfering magnetic field data is subtracted from the total magnetic field data to obtain more accurate geomagnetic field data. The geomagnetic field data is further filtered to obtain more accurate magnetic anomaly data.

[0089] Evaluate the final calculated data, including:

[0090] Standard deviation of magnetic field data σ S The calculation formula is as follows:

[0091]

[0092] Where n B is the data sampling point, ΔB is the magnetic induction data, is the average value of magnetic induction data.

[0093] The improvement ratio is calculated as follows:

[0094]

[0095] where σ S1 is the magnetic induction data before compensation, σ S2 is the compensated magnetic induction data.

[0096] Specifically, a fixed-wing aircraft aeromagnetic measurement compensation system, such as Figure 2 As shown, including:

[0097] Magnetic induction data collection module, used to obtain magnetic compensation related data in real time;

[0098] A model construction module is used to establish an improved model based on the TL model; wherein the improved model needs to use the magnetic compensation related data obtained by the magnetic induction data collection module for modeling;

[0099] A data processing module, used for filtering the data;

[0100] A calculation and processing module is used to apply the filtered data to the improved model to calculate the magnetic compensation coefficient; the magnetic interference data is separated by the magnetic compensation coefficient to obtain normal magnetic induction data;

[0101] The output module is used to output normal magnetic induction data and magnetic anomaly data.

[0102] Example 1

[0103] The fixed-wing aircraft compensation flight data is obtained by using the four-route compensation flight method. The compensation results are as follows: Figure 3 and Figure 4 As shown, Figure 3 is the normal magnetic induction data after compensation, Figure 4 This is the compensated magnetic anomaly data. The horizontal axis represents the sampling time, and the vertical axis represents the magnetic field value.

[0104] Table 1 Comparison of compensation improvement rates between the present invention and previous methods, the improvement rates are based on magnetic anomaly data

[0105]

[0106] It can be seen from Table 1 that the improvement degree of the compensation data by the method of the present invention is better than that of the previous methods, which proves the effectiveness of the method.

[0107] It should be noted that, in this application, relational terms such as "first" and "second" are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, the elements defined by the sentence "comprise a ..." do not exclude the presence of other identical elements in the process, method, article or device including the elements.

[0108] The above description is only a specific implementation of the present application, so that those skilled in the art can understand or implement the present application. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application will not be limited to the embodiments shown herein, but will conform to the widest range consistent with the principles and novel features applied for herein.

Claims

1. A fixed-wing aircraft aeromagnetic survey compensation method, characterized in that: The process includes: The aircraft conducts calibration flight and obtains magnetic compensation related data in real time; Based on the magnetic compensation related data, an improved model based on the TL model is established; The magnetic compensation related data are applied to the improved model for processing, and then the magnetic compensation coefficients are calculated by the improved truncated singular value method based on the crayfish optimization algorithm; The magnetic compensation coefficient is used to separate the magnetic interference data and obtain normal magnetic induction data.

2. The fixed-wing aircraft aeromagnetic survey compensation method according to claim 1, characterized in that: The magnetic compensation related data includes three-component fluxgate data obtained by a three-component fluxgate magnetometer, total magnetic field data obtained by a scalar magnetometer, current data of in-flight equipment, and aircraft attitude data obtained by an attitude instrument.

3. A fixed-wing aircraft aeromagnetic survey compensation method according to claim 2, characterized in that: Establish an improved model based on the TL model, including: Based on the constant interference magnetic field, induced interference magnetic field and eddy current interference magnetic field generated by the aircraft itself under the influence of the geomagnetic field, a TL model is established. The model is expressed as follows: Among them B d is the total interference magnetic field generated by the aircraft itself under the influence of the geomagnetic field, B p is a constant interfering magnetic field, B i To induce interference magnetic field, B e is the eddy current interference magnetic field, h i h′ is the direction cosine of the angle between the aircraft and the Earth's magnetic field measured by the three-component fluxgate magnetometer. i is the first-order derivative of its direction cosine, a i , b ij and c ij is the compensation coefficient; Based on the interference magnetic field excited by various currents generated by the aircraft in the flight environment, the compensation model extension item B is established c ; Based on the inductive interference magnetic field and eddy current interference magnetic field generated by the interference magnetic field excited by the current, the compensation model extension item B is established cd ; The TL model and compensation model are extended by term B c and B cd After merging, the improved model is as follows: B IMP =B d +B c +B cd Among them, B IMP is the total interfering magnetic field.

4. The fixed-wing aircraft aeromagnetic survey compensation method according to claim 3, characterized in that: The preprocessing, the establishment of the compensation model extension item B c , which is expressed as follows: Among them C i is the induced current of the surface metal and sensor connecting rod during the flight of the aircraft, as well as the working current value of the equipment inside the aircraft. (sinθ)' represents the first-order derivative of sinθ. n is the number of equipment inside the aircraft. d i d ij is the compensation coefficient, θ and ψ are the attitude instrument pitch angle and attitude instrument roll angle in the aircraft attitude data respectively; The compensation model is established to extend item B cd , which is expressed as follows: Among them B ci is the current induced interference magnetic field, B ce is the eddy current interfering with the magnetic field, e i 、e ij and f ij is the compensation coefficient.

5. The fixed-wing aircraft aeromagnetic survey compensation method according to claim 4, characterized in that: The magnetic compensation related data is applied to the improved model for processing, specifically: the three-component fluxgate data, the current data of the in-flight equipment and the aircraft attitude data obtained by the attitude instrument are applied to the improved model to obtain the improved model data, and the total magnetic field data and the improved model data are filtered through a bandpass filter to obtain the filtered total interference magnetic field B IMP and are the total magnetic field data B measured by the scalar magnetometer t .

6. A fixed-wing aircraft aeromagnetic survey compensation method according to claim 5, characterized in that: The specific process of the preprocessing and the calculation of the magnetic compensation coefficient is as follows: According to the total interference magnetic field B after filtering IMP and are the total magnetic field data B measured by the scalar magnetometer t , perform singular value decomposition on the improved model u i is the left singular vector, σ i is a singular value, v i is a right singular vector, and the improved truncated singular value method is calculated as follows: Where χ is the magnetic compensation coefficient, s i The expression is as follows: k is the number of singular values ​​retained, λ is the constraint coefficient, and the values ​​of k and λ are determined by the crayfish optimization algorithm.

7. A fixed-wing aircraft aeromagnetic survey compensation method according to claim 6, characterized in that: The crayfish optimization algorithm is as follows: The error formula of the crayfish optimization algorithm is as follows: Where o is the error coefficient, B t is the total magnetic field data measured by the scalar magnetometer; ||·|| is the first-order norm; the crayfish optimization algorithm is used to determine the parameters k and λ of the improved truncated singular value method, that is, the values ​​of the parameters when the error coefficient o is minimized.

8. The fixed-wing aircraft aeromagnetic survey compensation method according to claim 7, characterized in that: The preprocessing, the use of magnetic compensation coefficient to separate magnetic interference data, and obtain normal magnetic induction data, the specific process is as follows: The calculated magnetic compensation coefficient is substituted into the improved model based on the TL model to obtain the magnetic interference data caused by the aircraft itself and the metal induced current on the surface of the aircraft and the working current of the equipment inside the aircraft during the flight. The magnetic interference data is subtracted from the total magnetic field data to obtain the normal magnetic induction data.

9. A fixed-wing aircraft aeromagnetic compensation system, used to implement the fixed-wing aircraft aeromagnetic compensation method according to any one of claims 1 to 8, characterized in that: include: The magnetic induction data collection module is used to obtain magnetic compensation related data in real time, including three-component fluxgate data, total magnetic field data, current data of in-flight equipment, and aircraft attitude data obtained by the attitude instrument; A model construction module is used to establish an improved model based on the TL model based on magnetic compensation related data; The data processing module applies the three-component fluxgate data, the current data of the in-flight equipment and the aircraft attitude data to the improved model, and performs filtering on the total magnetic field data and the data output by the improved model; The calculation and processing module calculates the magnetic compensation coefficient based on the filtered data by the improved truncated singular value method of the crayfish optimization algorithm, separates the magnetic interference data, and obtains the normal magnetic induction data; The output module is used to output the normal magnetic induction data obtained by the calculation and processing module.

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