Magnetic field measurement method based on aviation magnetometer

Abstract

The invention discloses a magnetic field measurement method based on an aviation magnetometer, and belongs to the technical field of magnetic field measurement, and the method comprises the steps: S10, measuring a magnetic field component in a preset direction, and obtaining the attitude information of an aircraft in real time in the measurement process; the attitude information comprises a pitch angle, a roll angle and a yaw angle of the aircraft; s20, position positioning information of the aircraft is obtained, data processing is carried out on the magnetic field data corresponding to the magnetic field component, and the data processing comprises environmental noise filtering, data fusion and interpolation and error correction; the position positioning information comprises longitude, latitude and height. According to the method, the error in the magnetic field distribution diagram is corrected through the error correction model, the method comprises the steps of reference data selection, error source determination, error model establishment, data preprocessing, error estimation, error correction, correction result verification and the like, and the accuracy of a measurement result is effectively improved.

Description

Technical Field

[0001] The present invention relates to the technical field of magnetic field measurement, in particular to a magnetic field measurement method based on an aviation magnetometer. Background Art

[0002] Accurate measurement of magnetic fields is of great significance in fields such as geophysical exploration and aerospace.

[0003] For research in this area, the application document with application number CN202110605297.4 provides a high-precision aeromagnetic measurement system based on a multi-rotor unmanned helicopter. The technical solution includes a multi-rotor unmanned helicopter, an electromagnetic interference shielding plate, an optically pumped magnetometer, a gimbal, a positioning system, and a data acquisition and storage system. The electromagnetic interference shielding plate is mounted on the bottom of the multi-rotor unmanned helicopter, and a gimbal is fixed underneath it. The magnetic sensor of the optically pumped magnetometer is installed inside the gimbal, and the positioning system is fixed on the outside of the bottom of the gimbal. This technical solution can solve the problems of low efficiency of ground magnetic surveys due to restrictions on terrain and other objective conditions, easy interference from electromagnetic signals generated by drones, and the inability of fixed-wing drone magnetic surveys to perform low-speed and low-altitude flights.

[0004] Another application, filed with application number CN202310112345.5, provides a proton magnetometer-based aerial magnetic measurement device and method for drones. This technical solution includes a housing and an inductive electromagnetic receiving coil. The housing is secured to a mounting plate, to which a data acquisition system, an ultrasonic rangefinder, a GNSS antenna, and a proton magnetometer probe are attached. The inductive electromagnetic receiving coil is connected to a data acquisition card, the GNSS antenna to its host computer, the proton magnetometer probe to its host computer, and the ultrasonic rangefinder, proton magnetometer host computer, GNSS host computer, and data acquisition card are connected to a main control module. This technical solution features a simple structure, high magnetic measurement resolution and detection accuracy, and a rich source of basic aeromagnetic data.

[0005] However, these technical solutions are subject to changes in the aircraft's attitude (such as pitch, roll, and yaw), which can affect the magnetometer's measurement direction and lead to measurement errors. While these can be corrected using attitude sensors, the accuracy and real-time performance of the attitude sensors themselves can also introduce errors, further affecting the measurement results. Summary of the Invention

[0006] In view of the above problems existing in the existing field of magnetic field measurement technology, the present invention is proposed.

[0007] Therefore, one of the objects of the present invention is to provide a magnetic field measurement method based on an airborne magnetometer, which corrects the errors in the magnetic field distribution map through an error correction model, including the steps of selecting reference data, determining the error source, establishing an error model, data preprocessing, error estimation, error correction and verification of the correction results, thereby effectively improving the accuracy of the measurement results.

[0008] In order to solve the above technical problems, the present invention provides the following technical solutions: The present invention provides a magnetic field measurement method based on an airborne magnetometer, comprising the following steps: S10: measuring the magnetic field component in a preset direction and obtaining attitude information of the aircraft in real time during the measurement process; the attitude information includes the pitch angle, roll angle and yaw angle of the aircraft; S20: Acquire the position information of the aircraft and perform data processing on the magnetic field data corresponding to the magnetic field components, wherein the data processing includes environmental noise filtering, data fusion and interpolation, and error correction; the position information includes longitude, latitude, and altitude; The environmental noise filtering is to filter the magnetic field data to remove environmental noise, which includes electromagnetic interference and atmospheric disturbance; The data fusion and interpolation is to fuse the magnetic field data with the position positioning information to generate a magnetic field distribution map; The error correction is to correct the error in the magnetic field distribution map; S30: Based on the error-corrected magnetic field distribution diagram, data information related to the magnetic field data is obtained, and the magnetic field data is divided into different time periods according to the different time periods of the magnetic field data. , ,..., ;in, Indicated in The magnetic field data obtained in each time period; the data information includes the position positioning information and the attitude information of the aircraft corresponding to each magnetic field data; S40: Constructing a database for the position positioning information and the attitude information of the aircraft corresponding to each of the magnetic field data, analyzing the changes in the attitude information corresponding to the magnetic field data in the database, and obtaining regular changes in the magnetic field data as the attitude information changes.

[0009] As a preferred embodiment of the present invention, in the error correction, the error in the magnetic field distribution map is corrected by an error correction model, and the correction steps include selecting reference data, determining the error source, establishing an error model, data preprocessing, error estimation, error correction and verification of the correction result; The selection of reference data is to select a known magnetic field standard point or reference data as a calibration benchmark; The error sources are determined to be error sources in the magnetic field data, including instrument error, attitude error, environmental error, and positioning error; and each error is quantitatively analyzed to determine the degree of influence of each error on the magnetic field distribution map; The error correction model is established by establishing a mathematical model based on the error source to describe the relationship between the error and the measurement result; the error correction model includes a linear error model, a polynomial error model and a spatial error model; and the parameters of the error correction model are estimated and optimized, including estimating and optimizing the parameters of the error correction model by using the least squares method; The data preprocessing includes aligning the magnetic field data with the reference data to ensure that the two are consistent in time and space; The error estimation is to calculate the error estimation value of each measurement point in the preset direction according to the established error correction model; The error correction is to correct the magnetic field data according to the error estimate; And smoothing the corrected magnetic field data; The correction result verification is to compare the corrected magnetic field data with the reference data to verify the correction effect.

[0010] As a preferred solution of the present invention, in the establishment of the error correction model, the least squares method includes a linear least squares method, as shown below: ; in, represents the observation vector, represents the design matrix, represents the parameter vector, represents the error vector; According to the above formula, the parameter estimation formula of the least squares method is: ; Where, Represents the design matrix The transpose of express The inverse matrix of , which is the pseudo inverse of the design matrix; represents the product of the transpose of the design matrix and the observation vector, represents the parameter estimate obtained by minimizing the sum of squared errors.

[0011] As a preferred solution of the present invention, in the error estimation, the error estimation value of each measurement point in the preset direction is calculated according to the established error correction model, and the following is obtained according to the Kriging interpolation calculation: ;in, Indicates the location The error estimate at ; Where, Indicates a known location The error observation value at represents the weight coefficient, which is obtained by solving the Kriging equations. represents the order of the polynomial in the error correction model.

[0012] As a preferred solution of the present invention, wherein: calculating the error estimation value of each measurement point in the preset direction according to the established error correction model also includes calculating it according to the inverse distance weighted calculation, as shown below: ;in, Indicates the location The error estimate at ; Where, Indicates a known location The error observation value at Indicates location and The distance between represents the power of the distance, and the power is 2; Indicates the number of known positions.

[0013] As a preferred solution of the present invention, in the error correction, the magnetic field data is corrected according to the error estimate, and the correction formula is as follows: ; Where, represents the corrected magnetic field data, represents the original measurement value, Represents the error estimate.

[0014] As a preferred solution of the present invention, in S40, the regular change of the magnetic field data is obtained as the posture information changes, and the acquisition method includes acquiring through a machine learning method, and the machine learning method includes supervised learning and unsupervised learning; Supervised learning uses labeled data to train a machine learning model. In the machine learning model, the posture information is used as input features, and the magnetic field data is used as the target variable to learn the mapping relationship between the two. The unsupervised learning shown is to obtain the distribution law of magnetic field data under different posture information through cluster analysis.

[0015] As a preferred solution of the present invention, wherein: according to the obtained regular changes, the changes in the position positioning information and posture information corresponding to the magnetic field data are divided into first posture information, second posture information and third posture information, and the position positioning information and magnetic field data corresponding to the first posture information, the second posture information and the third posture information are obtained respectively, and the magnetic field data are marked as reference magnetic field data; when the magnetic field data obtained in the future time period with the same position positioning information and posture information is different from the reference magnetic field data, it is determined that an error has occurred in the magnetic field measurement; otherwise, no determination is made.

[0016] A terminal includes a processor, an input interface, an output interface and a memory, wherein the processor, input interface, output interface and memory are interconnected, wherein the memory is used to store a computer program, the computer program includes program instructions, and the processor is configured to call the program instructions to execute the method described above.

[0017] A computer-readable storage medium stores a computer program, wherein the computer program includes program instructions. When the program instructions are executed by a processor, the processor is caused to execute the method described above.

[0018] Beneficial effects: 1. The accuracy and reliability of magnetic field measurement are improved by obtaining the attitude information and position positioning information of the aircraft, and performing environmental noise filtering, data fusion and interpolation, and error correction on the magnetic field data; 2. The errors in the magnetic field distribution map are corrected through the error correction model, including the steps of selecting reference data, determining the error source, establishing the error model, data preprocessing, error estimation, error correction and verification of the correction results, which effectively improves the accuracy of the measurement results; 3. By building a database, analyzing the changes in attitude information corresponding to the magnetic field data, and obtaining the regular changes in the magnetic field data as the attitude information changes, we can better understand the relationship between the magnetic field data and the aircraft attitude, and provide a data source for subsequent data analysis and processing. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for describing the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. Those skilled in the art can also derive other drawings based on these drawings without inventive effort. Among them: Figure 1 Schematic diagram of a method flow in an embodiment of the present invention; Figure 2 Schematic diagram of the process structure of an embodiment of the present invention. DETAILED DESCRIPTION

[0020] To make the objectives, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions of the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the described embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field are within the scope of protection of the present invention.

[0021] Existing technologies are limited by changes in the aircraft's attitude (such as pitch, roll, and yaw), which affect the magnetometer's measurement direction and lead to measurement errors. While these can be corrected using attitude sensors, the accuracy and real-time nature of the attitude sensors themselves can also introduce errors, further affecting the measurement results.

[0022] Based on this, the present invention proposes a magnetic field measurement method based on an airborne magnetometer, which corrects the errors in the magnetic field distribution map through an error correction model. The method includes the steps of selecting reference data, determining the error source, establishing an error model, data preprocessing, error estimation, error correction and correction result verification, thereby effectively improving the accuracy of the measurement results.

[0023] The present invention will be further described in detail below through embodiments and in conjunction with the accompanying drawings.

[0024] Reference Figures 1 to 2 , is an embodiment of the present invention, which provides a magnetic field measurement method based on an airborne magnetometer, comprising the following steps: S10: Measure the magnetic field component in a preset direction and obtain the attitude information of the aircraft in real time during the measurement process; the attitude information includes the pitch angle, roll angle and yaw angle of the aircraft; In this embodiment, a high-precision three-axis magnetometer is used to measure the magnetic field component in a preset direction. The high-precision three-axis magnetometer is installed on an aircraft (such as a drone, helicopter, or fixed-wing aircraft) and is fixed by a shock-absorbing device to reduce the impact of flight vibration on the measurement results. A gyroscope, an accelerometer, and a heading sensor are used to obtain the aircraft's attitude information in real time. S20: Acquire the position information of the aircraft and perform data processing on the magnetic field data corresponding to the magnetic field components. The data processing includes environmental noise filtering, data fusion and interpolation, and error correction. The position information includes longitude, latitude, and altitude. Environmental noise filtering is to filter the magnetic field data to remove environmental noise, which includes electromagnetic interference and atmospheric disturbances; Data fusion and interpolation, to fuse magnetic field data with position information to generate a magnetic field distribution map; Error correction, to correct errors in the magnetic field distribution map; S30: Based on the error-corrected magnetic field distribution diagram, data information related to the magnetic field data is obtained, and the magnetic field data is divided into different time periods according to the acquired magnetic field data. , ,..., ;in, Indicated in The magnetic field data obtained in each time period; the data information includes the position positioning information corresponding to each magnetic field data and the attitude information of the aircraft; S40: Building a database of the position information and the attitude information of the aircraft corresponding to each magnetic field data, analyzing changes in the attitude information corresponding to the magnetic field data in the database, and obtaining regular changes in the magnetic field data as the attitude information changes; It should be noted that by acquiring the aircraft's attitude and position information in real time, combined with the measurement of magnetic field components, comprehensive magnetic field data can be collected. At the same time, through data processing steps such as environmental noise filtering, data fusion and interpolation, and error correction, the accuracy and reliability of magnetic field measurements are improved. In error correction, the errors in the magnetic field distribution map are corrected using an error correction model. The correction steps include selecting reference data, determining the error source, establishing an error model, data preprocessing, error estimation, error correction, and verification of the correction results. Select reference data, which is to select a known magnetic field standard point or reference data as a calibration benchmark; In this embodiment, the reference data may be ground magnetic survey data, a known geological magnetic field model, or magnetic field distribution obtained by other high-precision measurement means (such as satellite magnetic field data); Identify the sources of error in the magnetic field data, including instrument error, attitude error, environmental error, and positioning error; and perform quantitative analysis on each error to determine the extent to which each error affects the magnetic field distribution map; In this embodiment, instrument errors, such as zero bias, sensitivity variation, and non-orthogonality errors of the measuring device; Attitude errors, such as the impact of changes in the aircraft's pitch, roll, and yaw angles on the direction of magnetic field measurements; Environmental errors, such as the impact of external factors such as electromagnetic interference, atmospheric disturbances, and diurnal magnetic variations on measurement results; Positioning errors, such as geographic location deviation caused by GPS or positioning system errors; Establish an error correction model, which is a mathematical model based on the error source to describe the relationship between the error and the measurement result; the error correction model includes a linear error model, a polynomial error model, and a spatial error model; and estimate and optimize the parameters of the error correction model, including estimating and optimizing the parameters of the error correction model through the least squares method; Data preprocessing, including aligning magnetic field data with reference data to ensure consistency in time and space; Error estimation, which is to calculate the error estimation value of each measurement point in the preset direction according to the established error correction model; Error correction, which is to correct the magnetic field data according to the error estimate; And smoothing the corrected magnetic field data; This can eliminate local fluctuations introduced by error correction; Verification of the calibration results: comparing the corrected magnetic field data with the reference data to verify the calibration effect; In this embodiment, if the correction result is not ideal, the parameters of the error correction model can be adjusted to re-estimate and correct the error; In establishing the error correction model, the least squares method includes the linear least squares method, as shown below: ; in, represents the observation vector, represents the design matrix, represents the parameter vector, represents the error vector; According to the above formula, the parameter estimation formula of the least squares method is: ; Where, Represents the design matrix The transpose of express The inverse matrix of , which is the pseudo inverse of the design matrix; represents the product of the transpose of the design matrix and the observation vector, represents the parameter estimate obtained by minimizing the sum of squared errors; In this embodiment, the optimal parameter estimation value is obtained by minimizing the sum of squared errors, thereby improving the accuracy of error correction; In error estimation, the error estimate value of each measurement point in the preset direction is calculated based on the established error correction model, and is calculated based on Kriging interpolation: ;in, Indicates the location The error estimate at ; Where, Indicates a known location The error observation value at Represents the weight coefficient, which is obtained by solving the Kriging equations. represents the order of the polynomial in the error correction model; In this embodiment, the accuracy of error estimation is improved, making the correction of magnetic field data more precise, thereby improving the quality of the magnetic field distribution map; The error estimate value of each measurement point in the preset direction is calculated based on the established error correction model, and is also calculated based on the inverse distance weighting, as shown below: ;in, Indicates the location The error estimate at ; Where, Indicates a known location The error observation value at Indicates location and The distance between Indicates the power of distance, the power value is 2; Indicates the number of known positions; In error correction, the magnetic field data is corrected according to the error estimate. The correction formula is as follows: ; Where, represents the corrected magnetic field data, represents the original measurement value, represents the error estimate; In this embodiment, the error correction process is simplified, making the corrected magnetic field data more reliable; In S40, the regular change of the magnetic field data is obtained as the posture information changes, and the acquisition method includes obtaining it through a machine learning method, and the machine learning method includes supervised learning and unsupervised learning; Supervised learning uses labeled data to train a machine learning model. In the machine learning model, the posture information is used as input features, and the magnetic field data is used as the target variable to learn the mapping relationship between the two. The unsupervised learning shown is to obtain the distribution pattern of magnetic field data under different posture information through cluster analysis; In this embodiment, the machine learning model includes support vector machine, random forest, and neural network; Cluster analysis, including K-means and hierarchical clustering; In this embodiment, machine learning methods (including supervised learning and unsupervised learning) are used to analyze the changes in magnetic field data with posture information. This method can automatically discover patterns and regularities in the data; Improved understanding of the regular changes in magnetic field data, which helps to better predict and interpret magnetic field measurement results; Based on the obtained regular changes, the changes in the position information and the attitude information corresponding to the magnetic field data are divided into first attitude information, second attitude information, and third attitude information, and the position information and magnetic field data corresponding to the first attitude information, the second attitude information, and the third attitude information are respectively obtained, and the magnetic field data are marked as reference magnetic field data; when the magnetic field data obtained in a future time period with the same position information and attitude information is different from the reference magnetic field data, it is determined that an error has occurred in the magnetic field measurement; otherwise, no determination is made; In this embodiment, by analyzing the changes in magnetic field data and posture information, different posture information can be distinguished, and reference magnetic field data can be marked to provide early warning for possible errors in the future.

[0025] A terminal includes a processor, an input interface, an output interface and a memory, wherein the processor, input interface, output interface and memory are interconnected, wherein the memory is used to store a computer program, the computer program includes program instructions, and the processor is configured to call the program instructions to execute the method described above.

[0026] A computer-readable storage medium stores a computer program, wherein the computer program includes program instructions. When the program instructions are executed by a processor, the processor is caused to execute the method described above.

[0027] In summary, the present application corrects the errors in the magnetic field distribution map through an error correction model, including the steps of selecting reference data, determining the source of error, establishing an error model, data preprocessing, error estimation, error correction and correction result verification, thereby effectively improving the accuracy of the measurement results.

[0028] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present invention, which should all be included in the scope of the claims of the present invention.

Claims

1. A magnetic field measurement method based on an airborne magnetometer, characterized in that: The following steps are involved: S10: measuring the magnetic field component in a preset direction and obtaining attitude information of the aircraft in real time during the measurement process; the attitude information includes the pitch angle, roll angle and yaw angle of the aircraft; S20: Acquire the position information of the aircraft and perform data processing on the magnetic field data corresponding to the magnetic field components, wherein the data processing includes environmental noise filtering, data fusion and interpolation, and error correction; the position information includes longitude, latitude, and altitude; The environmental noise filtering is to filter the magnetic field data to remove environmental noise, which includes electromagnetic interference and atmospheric disturbance; The data fusion and interpolation is to fuse the magnetic field data with the position positioning information to generate a magnetic field distribution map; The error correction is to correct the error in the magnetic field distribution map; S30: Based on the error-corrected magnetic field distribution diagram, data information related to the magnetic field data is obtained, and the magnetic field data is divided into different time periods according to the different time periods of the magnetic field data. , ,..., ;in, Indicated in The magnetic field data obtained in each time period; the data information includes the position positioning information and the attitude information of the aircraft corresponding to each magnetic field data; S40: Constructing a database for the position positioning information and the attitude information of the aircraft corresponding to each of the magnetic field data, analyzing the changes in the attitude information corresponding to the magnetic field data in the database, and obtaining regular changes in the magnetic field data as the attitude information changes.

2. The magnetic field measurement method based on an aeronautical magnetometer according to claim 1, characterized in that: In the error correction, the error in the magnetic field distribution map is corrected by an error correction model, and the correction steps include selecting reference data, determining the error source, establishing an error model, data preprocessing, error estimation, error correction and verification of the correction result; The selection of reference data is to select a known magnetic field standard point or reference data as a calibration benchmark; The error sources are determined to be error sources in the magnetic field data, including instrument error, attitude error, environmental error, and positioning error; and each error is quantitatively analyzed to determine the degree of influence of each error on the magnetic field distribution map; The error correction model is established by establishing a mathematical model based on the error source to describe the relationship between the error and the measurement result; the error correction model includes a linear error model, a polynomial error model and a spatial error model; and the parameters of the error correction model are estimated and optimized, including estimating and optimizing the parameters of the error correction model by using the least squares method; The data preprocessing includes aligning the magnetic field data with the reference data to ensure that the two are consistent in time and space; The error estimation is to calculate the error estimation value of each measurement point in the preset direction according to the established error correction model; The error correction is to correct the magnetic field data according to the error estimate; And smoothing the corrected magnetic field data; The correction result verification is to compare the corrected magnetic field data with the reference data to verify the correction effect.

3. The magnetic field measurement method based on an aeronautical magnetometer according to claim 2, characterized in that: In establishing the error correction model, the least square method includes a linear least square method, as shown below: ； in, represents the observation vector, represents the design matrix, represents the parameter vector, represents the error vector; According to the above formula, the parameter estimation formula of the least squares method is: ； Where, Represents the design matrix The transpose of express The inverse matrix of , which is the pseudo inverse of the design matrix; represents the product of the transpose of the design matrix and the observation vector, represents the parameter estimate obtained by minimizing the sum of squared errors.

4. The magnetic field measurement method based on an aeronautical magnetometer according to claim 2, characterized in that: In the error estimation, the error estimation value of each measurement point in the preset direction is calculated according to the established error correction model, and is obtained by Kriging interpolation: ;in, Indicates the location The error estimate at ; Where, Indicates a known location The error observation value at represents the weight coefficient, which is obtained by solving the Kriging equations. represents the order of the polynomial in the error correction model.

5. The magnetic field measurement method based on an airborne magnetometer according to claim 4, characterized in that: The error estimation value of each measurement point in the preset direction is calculated according to the established error correction model, and is also calculated according to the inverse distance weighted method, as shown below: ;in, Indicates the location The error estimate at ; Where, Indicates a known location The error observation value at Indicates location and The distance between represents the power of the distance, and the power is 2; Indicates the number of known positions.

6. The magnetic field measurement method based on an aeronautical magnetometer according to claim 2, characterized in that: In the error correction, the magnetic field data is corrected according to the error estimate. The correction formula is as follows: ； Where, represents the corrected magnetic field data, represents the original measurement value, Represents the error estimate.

7. The magnetic field measurement method based on an airborne magnetometer according to claim 1, characterized in that: In S40, a regular change of the magnetic field data is obtained as the posture information changes, and the obtaining method includes obtaining through a machine learning method, and the machine learning method includes supervised learning and unsupervised learning; Supervised learning uses labeled data to train a machine learning model. In the machine learning model, the posture information is used as input features, and the magnetic field data is used as the target variable to learn the mapping relationship between the two. The unsupervised learning shown is to obtain the distribution law of magnetic field data under different posture information through cluster analysis.

8. The magnetic field measurement method based on an aeronautical magnetometer according to claim 7, characterized in that: According to the obtained regular changes, the changes in the position positioning information and posture information corresponding to the magnetic field data are divided into first posture information, second posture information and third posture information, and the position positioning information and magnetic field data corresponding to the first posture information, the second posture information and the third posture information are respectively obtained, and the magnetic field data are marked as reference magnetic field data; when the magnetic field data obtained in the future time period with the same position positioning information and posture information is different from the reference magnetic field data, it is determined that an error has occurred in the magnetic field measurement; otherwise, no determination is made.

9. A terminal, characterized in that: The method comprises a processor, an input interface, an output interface and a memory, wherein the processor, the input interface, the output interface and the memory are interconnected, wherein the memory is used to store a computer program, the computer program includes program instructions, and the processor is configured to call the program instructions to execute the method according to any one of claims 1 to 8.

10. A computer-readable storage medium, characterized in that The computer-readable storage medium stores a computer program, wherein the computer program includes program instructions. When the program instructions are executed by a processor, the processor is caused to perform the method according to any one of claims 1 to 8.

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