Magnetic direction observation error correction method based on coil type absolute magnetometer

Abstract

The invention discloses a magnetic direction observation error correction method based on a coil type absolute magnetometer, and relates to the technical field of magnetometer error correction. The magnetic direction observation error correction method based on the coil type absolute magnetometer mainly comprises the following steps: applying a bias field in a specific direction by using an existing deflection coil in the coil type absolute magnetometer to realize electrical detection of a magnetic azimuth angle; the inconsistency of the optical axis of a collimator in the fluxgate theodolite and the magnetic axial direction of the fluxgate sensor is obtained by utilizing the sensitivity of the fluxgate sensor to the geomagnetic direction, and the included angle between the coil type absolute magnetometer and the optical axis of the fluxgate theodolite is further obtained through collimation of the collimator; and further obtaining observation errors of the magnetic axis and the optical axis of the coil type absolute magnetometer. According to the magnetic direction observation error correction method based on the coil type absolute magnetometer, the magnetic direction observation error caused by inconsistency of the optical axis and the magnetic axis can be corrected, and the magnetic direction observation precision is improved.

Description

Technical Field

[0001] The invention relates to the technical field of magnetometer error correction, and more specifically to a magnetic direction observation error correction method based on a coil-type absolute magnetometer. Background Art

[0002] The coil-type absolute magnetometer, which consists of a total field sensor, an orthogonal coil (i.e., a declination and inclination coil) and a north-facing unit, can realize absolute observation of the total geomagnetic field and magnetic direction. After applying the bias field generated by the horizontal inclination coil and the vertical declination coil, the corresponding synthetic field is measured by the total field sensor, and then the absolute measurement of the total geomagnetic field, magnetic declination and inclination can be realized by combining the geographic north azimuth introduced by the north-facing unit. At present, the existing methods can only use the total field magnetometer and fluxgate theodolite to perform absolute measurement of the total field and magnetic direction respectively. In addition, the fluxgate theodolite usually requires manual operation, resulting in long observation time and reliance on manual experience. In contrast, the coil-type absolute magnetometer can carry out integrated, fully automatic absolute measurement. Therefore, it has great application prospects in many fields such as earth science research, space weather forecasting and resource exploration.

[0003] Factors that affect the magnetic direction measurement accuracy of coil-type absolute magnetometers include attitude error, electrical error and observation error. The attitude error is caused by the non-orthogonality and non-horizontality of the coil system during the processing and assembly process. The high-precision detection and data correction of the attitude are achieved by applying the bias field and rotating the coil electrical detection method for multiple times. In addition, during long-term observation, the drift of the attitude will have a greater impact on the measurement results, and this error can be reduced by hanging. The electrical error mainly comes from the bias field noise and the measurement error of the total field sensor. For the bias field noise, the bias field noise is reduced by optimizing the stability and noise level of the constant current source. The negative impact of the sensor measurement error can be reduced by optimizing the excitation method and the frequency measurement algorithm. High-precision geographic north orientation is achieved through the high-precision astronomical time angle method or RTK (Real-Time Kinematic) technology, and the observed geographic north is introduced into the collimator on the top of the instrument. Therefore, the observation error mainly includes orientation error and angle transfer error. For the astronomical hour angle method, by observing the North Pole star and collecting accurate time (using GPS UTC or the built-in quartz clock of the total station), the orientation accuracy can usually be less than 1". In RTK-based orientation, an orientation accuracy of 3" can be achieved by compensating for atmospheric delay, orbit error, and phase center deviation. For angle transfer errors, the negative impact of observation errors can be weakened by suppressing the eccentricity error of the instrument and repeating the aiming method. Conventionally, for such coil-based magnetometers, mechanical processing can be used to ensure that the coil axis and the collimator optical axis (i.e., normal) are kept as parallel as possible, so the geographic north is considered to be introduced into the magnetic sensor. However, high-precision processing and assembly cannot ensure that the coil axis and the optical axis are completely coincident; in addition, it is difficult to ensure ideal coincidence between the coil axis and the magnetic axis that generates the bias field of the coil. Therefore, the magnetic direction error caused by this misalignment cannot be ignored. Although, in the calibration of inertial navigation equipment and high-precision multi-axis turntables, some literature has achieved the correction of the misalignment between the optical axis and the mechanical axis. However, there are few literatures on the direct correction of magnetic direction observation errors, which makes this error the main obstacle to further improving the accuracy of magnetic direction measurement. Therefore, it is necessary to propose a method that can measure and correct the magnetic direction observation error caused by the inconsistency between the optical axis and the magnetic axis. Summary of the invention

[0004] The purpose of the present invention is to provide a method for correcting magnetic direction observation errors based on a coil-type absolute magnetometer, which can correct the magnetic direction observation errors caused by the inconsistency between the optical axis and the magnetic axis and improve the accuracy of magnetic direction observation.

[0005] The invention provides a magnetic direction observation error correction method based on a coil-type absolute magnetometer, comprising the following steps: S1: obtaining the magnetic azimuth of the coil-type absolute magnetometer according to the geomagnetic background field, the positive bias synthetic total field and the reverse bias synthetic total field; S2: obtaining the axial inconsistency angle of the fluxgate theodolite according to the magnetic declination of the fluxgate theodolite in different states; S3: obtaining the optical axis transfer angles of the coil-type absolute magnetometer and the fluxgate theodolite, and obtaining the magnetic direction observation error according to the optical axis transfer angles of the coil-type absolute magnetometer and the fluxgate theodolite, the magnetic azimuth of the coil-type absolute magnetometer and the axial inconsistency angle of the fluxgate theodolite.

[0006] Furthermore, step S1 specifically includes: S11: using the total field sensor in the coil-type absolute magnetometer to measure and obtain the geomagnetic background field; S12: using equal and opposite currents to be passed through the magnetic declination coils in the coil-type absolute magnetometer in sequence to measure and obtain the positive bias synthetic total field and the reverse bias synthetic total field; S13: obtaining the magnetic azimuth of the coil-type absolute magnetometer according to the geomagnetic background field, the positive bias synthetic total field and the reverse bias synthetic total field.

[0007] Further, step S13 specifically includes: obtaining the magnetic azimuth of the coil-type absolute magnetometer according to the geomagnetic background field, the forward bias synthetic total field and the reverse bias synthetic total field, as shown in the formula: , in, is the magnetic azimuth of the coil-type absolute magnetometer, is the arccosine function, is the total field under positive bias, is the total field in reverse bias, is the geomagnetic background field, is the synthetic total field deflection angle.

[0008] Further, step S2 specifically includes: S21: using a fluxgate theodolite to obtain magnetic declination angles of the fluxgate theodolite in different states, the magnetic declination angles of the fluxgate theodolite in different states including a first magnetic declination angle, a second magnetic declination angle, a third magnetic declination angle, and a fourth magnetic declination angle; S22: obtaining an axial inconsistency angle of the fluxgate theodolite according to the first magnetic declination angle, the second magnetic declination angle, the third magnetic declination angle, and the fourth magnetic declination angle.

[0009] Further, step S22 specifically includes: obtaining the axial inconsistency angle of the fluxgate theodolite according to the first magnetic declination, the second magnetic declination, the third magnetic declination, and the fourth magnetic declination, such as the formula: , , Among them, the axial inconsistency angle of the fluxgate theodolite includes the horizontal characteristic angle and the vertical characteristic angle. is the horizontal characteristic angle, is the vertical characteristic angle, , , , are respectively a first magnetic declination, a second magnetic declination, a third magnetic declination, and a fourth magnetic declination; , , , They are the horizontal angles of the fluxgate theodolite rotating around the vertical axis, both read from the horizontal dial at the full minute; , , , They are the readings of the fluxgate sensor during the magnetic declination measurement process, is the horizontal component of the geomagnetic field, is the circumference of a circle, is the tangent function, is the magnetic inclination.

[0010] Furthermore, step S3 specifically includes: S31: using the coil-type absolute magnetometer and the fluxgate theodolite, obtaining the optical axis transfer angles of the coil-type absolute magnetometer and the fluxgate theodolite; S32: obtaining the magnetic direction observation error according to the optical axis transfer angles of the coil-type absolute magnetometer and the fluxgate theodolite, the magnetic azimuth angle of the coil-type absolute magnetometer and the axial inconsistency angle of the fluxgate theodolite.

[0011] Further, step S31 specifically includes: using the coil-type absolute magnetometer and the fluxgate theodolite to obtain the optical axis transfer angle of the coil-type absolute magnetometer and the fluxgate theodolite, such as the formula: , in, is the optical axis transfer angle of the coil absolute magnetometer and fluxgate theodolite, and They are respectively the horizontal disk reading when the fluxgate sensor sensitive axis of the fluxgate theodolite is on the horizontal plane and the fluxgate sensor output is zero, and the horizontal disk reading when the fluxgate sensor output is zero after the fluxgate sensor rotates 180° on the horizontal plane; and They are the fluxgate sensor outputting a horizontal disc correction value approximately below zero on the horizontal plane; and These are the horizontal disk readings when the telescope using the fluxgate theodolite is aimed at the coil-type absolute magnetometer in a symmetrical position.

[0012] Further, step S32 specifically includes: obtaining the magnetic direction observation error according to the optical axis transfer angle of the coil-type absolute magnetometer and the fluxgate theodolite, the magnetic azimuth of the coil-type absolute magnetometer and the axial inconsistency angle of the fluxgate theodolite, as shown in the formula: , in, is the magnetic direction observation error.

[0013] The implementation of the magnetic direction observation error correction method based on the coil-type absolute magnetometer provided by the present invention has the following beneficial effects: The present invention obtains the magnetic azimuth of a coil-type absolute magnetometer according to a geomagnetic background field, a positive bias synthetic total field and a reverse bias synthetic total field; obtains the axial inconsistency angle of a fluxgate theodolite according to the magnetic declination angles of different states of a fluxgate theodolite; obtains the optical axis transfer angles of the coil-type absolute magnetometer and the fluxgate theodolite, and obtains the magnetic direction observation error according to the optical axis transfer angles of the coil-type absolute magnetometer and the fluxgate theodolite, the magnetic azimuth of the coil-type absolute magnetometer and the axial inconsistency angle of the fluxgate theodolite; the coil-type vector magnetometer targeted by the present invention has a collimator itself, and if applied to other instruments, a collimator can be additionally installed, and then the present invention is used for correction; the present invention only needs to obtain three specific angles in sequence to achieve a high-precision compensation effect; the present invention obtains the quantitative relationship between two optical axes and magnetic axes that are difficult to visualize without changing the hardware design and the subsequent data processing, thereby realizing the direct detection and compensation of the magnetic direction observation error, and can obtain the magnetic direction observation error compensation effect, and improve the magnetic direction detection accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] The present invention will be further described below with reference to the accompanying drawings and embodiments, in which: Figure 1 It is a flow chart of a magnetic direction observation error correction method based on a coil-type absolute magnetometer provided by the present invention; Figure 2 It is a schematic diagram of the principle of the magnetic direction observation error detection method provided by the present invention; Figure 3 It is a schematic diagram of the magnetic azimuth angle solution principle provided by the present invention; Figure 4 It is a schematic diagram of the axial inconsistency principle of the fluxgate theodolite provided by the present invention; Figure 5 It is a schematic diagram of the geographic coordinate system XYZ and the fluxgate theodolite coordinate system X'Y'Z' provided by the present invention; wherein X points to geographic north, Y is geographic east, and Z is vertically downward; Figure 6 Schematic diagram of the fluxgate sensor provided by the present invention located in a horizontal plane (θ=0°); wherein (a) is a schematic diagram of the magnetic axis pointing to the magnetic east direction; (b) is a schematic diagram of the magnetic axis pointing to the magnetic west direction; Figure 7Schematic diagram of the fluxgate sensor provided by the present invention located in a horizontal plane (θ=180°); wherein (a) is a schematic diagram of the magnetic axis pointing to the magnetic east direction; and (b) is a schematic diagram of the magnetic axis pointing to the magnetic west direction. DETAILED DESCRIPTION

[0015] In order to have a clearer understanding of the technical features, purposes and effects of the present invention, specific embodiments of the present invention are now described in detail with reference to the accompanying drawings.

[0016] Figure 1 A schematic diagram of a magnetic direction observation error correction method based on a coil-type absolute magnetometer in this embodiment is shown. In this embodiment, the magnetic direction observation error correction method based on a coil-type absolute magnetometer includes the following steps: S1: According to the geomagnetic background field, the total synthetic field of the positive bias and the total synthetic field of the reverse bias, the magnetic azimuth of the coil-type absolute magnetometer is obtained; In an exemplary embodiment, step S1 specifically includes: S11: Use the total field sensor in the coil-type absolute magnetometer to measure and obtain the geomagnetic background field; S12: measuring by sequentially passing currents of equal magnitude and opposite direction into the magnetic declination coils in the coil-type absolute magnetometer to obtain a forward biased synthetic total field and a reverse biased synthetic total field; S13: obtaining the magnetic azimuth of the coil-type absolute magnetometer according to the geomagnetic background field, the forward bias synthetic total field and the reverse bias synthetic total field; In an exemplary embodiment, step S13 specifically includes: obtaining the magnetic azimuth of the coil-type absolute magnetometer according to the geomagnetic background field, the forward bias synthetic total field and the reverse bias synthetic total field, as shown in the formula: , in, is the magnetic azimuth of the coil-type absolute magnetometer, is the arccosine function, is the total field under positive bias, is the total field in reverse bias, is the geomagnetic background field, is the synthetic total field deflection angle; S2: According to the magnetic declination of the fluxgate theodolite in different states, the axial inconsistency angle of the fluxgate theodolite is obtained; In an exemplary embodiment, step S2 specifically includes: S21: using a fluxgate theodolite to obtain magnetic declination angles of the fluxgate theodolite in different states, where the magnetic declination angles of the fluxgate theodolite in different states include a first magnetic declination angle, a second magnetic declination angle, a third magnetic declination angle, and a fourth magnetic declination angle; As an exemplary embodiment, in step S21, the fluxgate theodolite is adjusted to four different states: the vertical dial is adjusted in the horizontal plane so that the fluxgate sensor output S is 0, when the sensor magnetic axis is perpendicular to magnetic north and the sensor is above the telescope (e.g. Figure 6 As shown in (a)); rotate the fluxgate sensor 180° in the horizontal plane around the vertical disk (as shown in Figure 6 Further, the sensor is rotated 180° around the horizontal disk (as shown in (b)). Figure 7 As shown in (a) in the figure), the sensor is below the telescope; rotate the sensor 180° around the vertical axis (as shown in Figure 7 (b)); S22: Obtaining an axial inconsistency angle of a fluxgate theodolite according to the first magnetic declination, the second magnetic declination, the third magnetic declination, and the fourth magnetic declination; In an exemplary embodiment, step S22 specifically includes: obtaining the axial inconsistency angle of the fluxgate theodolite according to the first magnetic declination, the second magnetic declination, the third magnetic declination, and the fourth magnetic declination, such as the formula: , , Among them, the axial inconsistency angle of the fluxgate theodolite includes the horizontal characteristic angle and the vertical characteristic angle. is the horizontal characteristic angle, is the vertical characteristic angle, , , , are respectively a first magnetic declination, a second magnetic declination, a third magnetic declination, and a fourth magnetic declination; , , , They are the horizontal angles of the fluxgate theodolite rotating around the vertical axis, both read from the horizontal dial at the full minute; , , , They are the readings of the fluxgate sensor during the magnetic declination measurement process, is the horizontal component of the geomagnetic field, is the circumference of a circle, is the tangent function, is the magnetic inclination; S3: Obtain the optical axis transfer angles of the coil-type absolute magnetometer and the fluxgate theodolite, and obtain the magnetic direction observation error according to the optical axis transfer angles of the coil-type absolute magnetometer and the fluxgate theodolite, the magnetic azimuth of the coil-type absolute magnetometer and the axial inconsistency angle of the fluxgate theodolite; In an exemplary embodiment, step S3 specifically includes: S31: using the coil-type absolute magnetometer and the fluxgate theodolite, obtaining the optical axis transfer angles of the coil-type absolute magnetometer and the fluxgate theodolite; In an exemplary embodiment, step S31 specifically includes: using a coil-type absolute magnetometer and a fluxgate theodolite to obtain the optical axis transfer angle of the coil-type absolute magnetometer and the fluxgate theodolite, such as the formula: , in, is the optical axis transfer angle of the coil absolute magnetometer and fluxgate theodolite, and They are respectively the horizontal disk reading when the fluxgate sensor sensitive axis of the fluxgate theodolite is on the horizontal plane and the fluxgate sensor output is zero, and the horizontal disk reading when the fluxgate sensor output is zero after the fluxgate sensor rotates 180° on the horizontal plane; and They are the fluxgate sensor outputting a horizontal disc correction value approximately below zero on the horizontal plane; and They are respectively the horizontal disk readings when the telescope using fluxgate theodolite is sighted by the coil-type absolute magnetometer in a symmetrical position; S32: Obtain the magnetic direction observation error according to the optical axis transfer angle of the coil-type absolute magnetometer and the fluxgate theodolite, the magnetic azimuth of the coil-type absolute magnetometer and the axial inconsistency angle of the fluxgate theodolite; In an exemplary embodiment, step S32 specifically includes: obtaining the magnetic direction observation error according to the optical axis transfer angle of the coil-type absolute magnetometer and the fluxgate theodolite, the magnetic azimuth of the coil-type absolute magnetometer and the axial inconsistency angle of the fluxgate theodolite, as shown in the formula: , in, is the magnetic direction observation error.

[0017] In some embodiments, the above-mentioned magnetic direction observation error correction method based on the coil-type absolute magnetometer can also be implemented in the following manner.

[0018] It should be noted that, in order to reduce the negative impact of observation errors on the measurement accuracy of magnetic declination, this embodiment uses bias field loading and fluxgate theodolite to respectively determine the magnetic azimuth of the magnetic axis (i.e., bias field direction) and the optical axis (i.e., mirror normal), thereby achieving high-precision detection of magnetic declination observation errors. Figure 2 As shown; First, the deflection coil in the coil-type absolute magnetometer is used to apply a bias field in a specific direction to realize the magnetic azimuth Then, the sensitivity of the fluxgate sensor to the geomagnetic direction is used to obtain the inconsistency between the collimator optical axis and the magnetic axis of the fluxgate sensor in the fluxgate theodolite. The angle between the optical axis of the coil absolute magnetometer and the fluxgate theodolite is further obtained by collimating the collimator. ; Using the above measured parameters, the observation errors of the magnetic axis and optical axis of the coil absolute magnetometer can be directly obtained δ ;in, is the angle between the optical axis of the coil absolute magnetometer and the magnetic north; Figure 6 The geometric relationship between , we can know: (1) Therefore, the magnetic direction observation error can be obtained : (2) Therefore, the magnetic direction observation error of the coil absolute magnetometer is The key to detection is to obtain high-precision magnetic azimuth of the magnetometer , Axial inconsistency of fluxgate theodolite , the angle between the optical axes of the two magnetometers ; In this embodiment, the magnetic direction observation error correction method based on the coil-type absolute magnetometer includes the following steps: Step 1: Obtain the magnetic azimuth of the coil-type absolute magnetometer: This step is mainly used to give the magnetic azimuth of the coil-type absolute magnetometer First, the total field sensor in the coil-type absolute magnetometer is used to measure the geomagnetic background field. ; Then, the magnetic declination coil Currents of equal magnitude and opposite direction are passed sequentially to apply positive and reverse bias magnetic fields. and ( ); measure the total synthetic field after superposition of positive and reverse bias fields and , the angle between the applied bias field and magnetic north can be solved (i.e. magnetic azimuth); Figure 3 Middle, deflection coil The generated positive and negative bias fields can be expressed as and , the geomagnetic field can also be expressed as ; According to the cosine rule, the synthetic field and The strength of can be written as (3) (4) According to equations (3) and (4), the bias field strength can be obtained: for (5) Therefore, the magnetic azimuth of the magnetic axis of the coil-type absolute magnetometer can be obtained , (6) The electrical detection method does not rely on auxiliary tools, and can realize high-precision electrical detection of magnetic azimuth angle by using existing magnetic field generating coils and total field sensors, which has strong practicality. Step 2: Axial inconsistency of fluxgate theodolite: This step is mainly used to give the axial inconsistency of the fluxgate theodolite The present embodiment proposes a method for measuring the axial inconsistency of a fluxgate theodolite. The fluxgate theodolite is mainly composed of a fluxgate magnetic sensor and a non-magnetic theodolite. The non-magnetic theodolite is used for instrument leveling, aiming and reading. The fluxgate sensor is used to detect the angle between the magnetic sensitive axis and the geomagnetic field. In order to more clearly describe the inconsistency between the optical axis of the telescope of the fluxgate theodolite and the magnetic axis of the fluxgate sensor, a method is established based on Point as origin Coordinate system (such as Figure 4 (b) is the fluxgate theodolite coordinate system); the inconsistency can be expressed by the horizontal characteristic angle and vertical characteristic angle To express; according to Figure 4 (b) Geometric relationship, magnetic axis of fluxgate sensor exist In the coordinate system, it can be written as (7) In order to Mapping to the fluxgate theodolite coordinate system and introducing the geographic coordinate system (like Figure 5 In order to realize the vector synthesis operation under different coordinate systems, it is necessary to convert the fluxgate theodolite coordinate system Around the vertical axis and horizontal axis Rotation angle and vertical angle , so as to realize the coincidence of the two coordinate systems; according to Figure 5 , we can get the relationship between the geographic coordinate system and the fluxgate theodolite coordinate system, (8) Among them, the coordinate system rotation matrix is ​​as follows: ; According to the relationship between geomagnetic parameters, Total field in coordinates Written ; Using the rotation matrix of formula (8) ,exist Total field in coordinate system It can be written as (9) Since the output value of the fluxgate sensor is a vector On the magnetic axis The projection on (10) In the formula, T 0 is the zero field offset; Substituting equations (7) and (9) into equation (10) we can further obtain (11) exist Figure 5 In the figure, let the characteristic angle ,but The actual Angle with magnetic north (i.e. The characteristic angle Substituting into equation (11), due to the horizontal characteristic angle and vertical characteristic angle Small, formula (11) can be simplified as: (12) Total geomagnetic field The direction of the projection on the horizontal plane is called magnetic north. , geographically northeast and The vertical horizontal axis is the magnetic east direction , Axis and Axis and perpendicular to the horizontal plane The axes together form the fluxgate sensor coordinate system ; In order to further simplify formula (12), the fluxgate theodolite is operated as follows (such as Figure 6 and Figure 7 As shown); adjust the vertical dial in the horizontal plane to make the fluxgate sensor output is 0, when the sensor magnetic axis is perpendicular to magnetic north and the sensor is above the telescope (e.g. Figure 6 as shown in (a) above), and , ; Rotate the fluxgate sensor 180° in the horizontal plane around the vertical disk (such as Figure 6 As shown in (b) above, then , ; Further, rotate the sensor 180° around the horizontal disk (such as Figure 7 As shown in (a) in the figure), the sensor is below the telescope and , ; Rotate the sensor 180° around the vertical axis (e.g. Figure 7 As shown in (b) above, then , ; When the fluxgate sensor is above the telescope (such as Figure 6 ), , are 90° and 270° respectively; using Taylor approximation expansion, equation (12) can be written as (13) (14) Similarly, when the sensor is below the telescope, , are 90° and 270° respectively; similarly, formula (12) can be written as (15) (16) To further simplify the above formula, subtract the difference between (13) and (14) from the difference between (15) and (16), and combine ,have (17) In the formula, and The results were obtained at four locations. and The average value of the magnetic field is , , and Approximately equal to ; By summing the difference between (13) and (14) and the difference between (15) and (16), we can obtain the horizontal characteristic angle of the axial inconsistency of the fluxgate theodolite: (Equation (18)); Similarly, subtracting the sum of equations (13) and (14) from the sum of (15) and (16) can give the vertical characteristic angle of inconsistency: (Formula (19)), (18) (19) In the formula ， , , , is the magnetic declination Four solution results of ; , , , is the horizontal angle of the fluxgate theodolite rotating around the vertical axis, which is read from the horizontal dial at the whole minute; , , , is the magnetic declination The reading of the fluxgate sensor during the measurement process; According to formulas (18)−(19), the horizontal characteristic angle of axial inconsistency can be calculated by operating the fluxgate theodolite and taking the average. and vertical features ; Step 3: Obtain the transfer angle between the optical axes of the two instruments and calculate the magnetic direction observation error This step is mainly used to give the optical axis angle between the two magnetometers First, adjust the fluxgate sensor sensitive axis to be on the horizontal plane, even if the vertical dial reads 90° or 270°, and lock the vertical dial; then, adjust the fluxgate sensor orientation only on the horizontal plane until the fluxgate sensor outputs Lock the level dial when it reaches zero and record the level dial reading Finally, loosen the level dial, rotate the fluxgate sensor 180° on the horizontal plane, and continuously fine-tune it to zero output, and record the level dial reading. ; In actual operation, it is impossible to adjust the fluxgate sensor output It is completely zero, so the near-zero method can be used to solve this problem (the sensor's magnetic field output and deviation angle are linear in the near-zero interval). In addition, the output value of the fluxgate sensor is read at the full minute, which can significantly reduce the operator's error and observation time. Therefore, the near-zero method requires further correction of the horizontal disk, and its correction value is ∆A for (20) Similarly, the fluxgate theodolite telescope is then used to obtain the normal direction of the instrument by aiming at the fluxgate theodolite marker in the collimator on the top of the coil absolute magnetometer at a symmetrical position, and the horizontal circle reading at this time is recorded. , ; Using formula (23), the transfer angle between the two magnetometer optical axes can be obtained , (twenty one) In the formula, , They are the fluxgate sensor outputting a horizontal disc correction value approximately below zero on the horizontal plane; Substituting equations (6), (18) and (21) into equation (2), the magnetic direction observation error of the coil magnetometer can be determined: , (twenty two) Therefore, the soft compensation method can be used to correct the magnetic direction observation error, thereby improving the magnetic declination The purpose of solving accuracy.

[0019] It should be noted that the coil-type vector magnetometer mentioned in the present invention has its own collimator. If it is applied to other instruments, an additional collimator can be installed, and then the present invention can be used for correction. The magnetic direction observation error correction method proposed in the present invention needs to obtain three specific angles in sequence according to the above requirements to achieve high-precision compensation effect.

[0020] The embodiments of the present invention are described above in conjunction with the accompanying drawings, but the present invention is not limited to the above-mentioned specific implementation modes, which are merely illustrative rather than restrictive. Under the guidance of the present invention, ordinary technicians in this field can also make many forms without departing from the scope of protection of the present invention and the claims, all of which are within the protection of the present invention.

Claims

1. A method for correcting magnetic direction observation errors based on a coil-type absolute magnetometer, characterized in that: The following steps are involved: S1: According to the geomagnetic background field, the total synthetic field of the positive bias and the total synthetic field of the reverse bias, the magnetic azimuth of the coil-type absolute magnetometer is obtained; S2: According to the magnetic declination of the fluxgate theodolite in different states, the axial inconsistency angle of the fluxgate theodolite is obtained; S3: Obtain the optical axis transfer angles of the coil-type absolute magnetometer and the fluxgate theodolite, and obtain the magnetic direction observation error according to the optical axis transfer angles of the coil-type absolute magnetometer and the fluxgate theodolite, the magnetic azimuth of the coil-type absolute magnetometer and the axial inconsistency angle of the fluxgate theodolite.

2. The magnetic direction observation error correction method based on the coil-type absolute magnetometer according to claim 1 is characterized in that: Step S1 specifically includes: S11: Use the total field sensor in the coil-type absolute magnetometer to measure and obtain the geomagnetic background field; S12: measuring by sequentially passing currents of equal magnitude and opposite direction into the magnetic declination coils in the coil-type absolute magnetometer to obtain a forward biased synthetic total field and a reverse biased synthetic total field; S13: Obtaining the magnetic azimuth of a coil-type absolute magnetometer according to the geomagnetic background field, the forward bias synthetic total field and the reverse bias synthetic total field.

3. The magnetic direction observation error correction method based on the coil-type absolute magnetometer according to claim 2 is characterized in that: Step S13 specifically includes: obtaining the magnetic azimuth of the coil-type absolute magnetometer according to the geomagnetic background field, the forward bias synthetic total field and the reverse bias synthetic total field, as shown in the formula: ， in, is the magnetic azimuth of the coil-type absolute magnetometer, is the arccosine function, is the total field under positive bias, is the total field in reverse bias, is the geomagnetic background field, is the synthetic total field deflection angle.

4. The magnetic direction observation error correction method based on the coil-type absolute magnetometer according to claim 1 is characterized in that: Step S2 specifically includes: S21: using a fluxgate theodolite to obtain magnetic declination angles of the fluxgate theodolite in different states, wherein the magnetic declination angles of the fluxgate theodolite in different states include a first magnetic declination angle, a second magnetic declination angle, a third magnetic declination angle, and a fourth magnetic declination angle; S22: Obtaining an axial inconsistency angle of a fluxgate theodolite according to the first magnetic declination, the second magnetic declination, the third magnetic declination, and the fourth magnetic declination.

5. The magnetic direction observation error correction method based on the coil-type absolute magnetometer according to claim 4 is characterized in that: Step S22 specifically includes: obtaining the axial inconsistency angle of the fluxgate theodolite according to the first magnetic declination, the second magnetic declination, the third magnetic declination, and the fourth magnetic declination, as shown in the formula: ， ， Among them, the axial inconsistency angle of the fluxgate theodolite includes the horizontal characteristic angle and the vertical characteristic angle. is the horizontal characteristic angle, is the vertical characteristic angle, , , , are respectively a first magnetic declination, a second magnetic declination, a third magnetic declination, and a fourth magnetic declination; , , , They are the horizontal angles of the fluxgate theodolite rotating around the vertical axis, both read from the horizontal dial at the full minute; , , , They are the readings of the fluxgate sensor during the magnetic declination measurement process, is the horizontal component of the geomagnetic field, is the circumference of a circle, is the tangent function, is the magnetic inclination.

6. The magnetic direction observation error correction method based on the coil-type absolute magnetometer according to claim 1 is characterized in that: Step S3 specifically includes: S31: using the coil-type absolute magnetometer and the fluxgate theodolite, obtaining the optical axis transfer angles of the coil-type absolute magnetometer and the fluxgate theodolite; S32: Obtaining a magnetic direction observation error according to the optical axis transfer angles of the coil-type absolute magnetometer and the fluxgate theodolite, the magnetic azimuth of the coil-type absolute magnetometer and the axial inconsistency angle of the fluxgate theodolite.

7. The magnetic direction observation error correction method based on the coil-type absolute magnetometer according to claim 6 is characterized in that: Step S31 specifically includes: using the coil-type absolute magnetometer and the fluxgate theodolite to obtain the optical axis transfer angle of the coil-type absolute magnetometer and the fluxgate theodolite, such as the formula: ， in, is the optical axis transfer angle of the coil absolute magnetometer and fluxgate theodolite, and They are respectively the horizontal disk reading when the fluxgate sensor sensitive axis of the fluxgate theodolite is on the horizontal plane and the fluxgate sensor output is zero, and the horizontal disk reading when the fluxgate sensor output is zero after the fluxgate sensor rotates 180° on the horizontal plane; and They are the fluxgate sensor outputting a horizontal disc correction value approximately below zero on the horizontal plane; and They are the horizontal disk readings when the telescope using the fluxgate theodolite is aimed at the coil-type absolute magnetometer in a symmetrical position.

8. The magnetic direction observation error correction method based on the coil-type absolute magnetometer according to claim 6 is characterized in that: Step S32 specifically includes: obtaining the magnetic direction observation error according to the optical axis transfer angles of the coil-type absolute magnetometer and the fluxgate theodolite, the magnetic azimuth of the coil-type absolute magnetometer and the axial inconsistency angle of the fluxgate theodolite, as shown in the formula: ， in, is the magnetic direction observation error.

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