Absolute geomagnetic field vector observation method

Abstract

The invention discloses an absolute geomagnetic field vector observation method, and relates to the technical field of geomagnetic measurement. The absolute geomagnetic field vector observation method comprises the following steps: correcting drift values of three axes (A axis, B axis and C axis) of a three-axis fluxgate sensor for observation by using a three-axis magnetic sensor for correction and a magnetic shielding cylinder; determining the relative relationship between the three axes and the optical axis of the telescope of the non-magnetic theodolite, determining the absolute orientation of the three axes, and calculating the geomagnetic field component under the geographic coordinate system by combining the magnetic field readings of the three axes; the absolute total field intensity of the geomagnetic field observed by the total field sensor is used for correcting the observation error of the three-axis fluxgate sensor to obtain a corrected absolute geomagnetic field vector (including an absolute geomagnetic declination angle and a geomagnetic inclination angle); during the period, the three-axis magnetic sensor for correction and the magnetic shielding cylinder are used for automatically correcting the three-axis fluxgate sensor for observation. By implementing the absolute geomagnetic field vector observation method provided by the invention, high-precision absolute automatic continuous observation of three parameters including the geomagnetic field intensity, the geomagnetic declination and the geomagnetic dip angle can be realized.

Description

Technical Field

[0001] This invention relates to the field of geomagnetic measurement technology, and more specifically, to a method for observing absolute geomagnetic field vectors. Background Technology

[0002] The Earth's magnetic field is a vector field, described by three elements: magnetic field strength, magnetic declination, and magnetic inclination. High-precision geomagnetic field observations require accurate measurements of the absolute magnetic field strength and the precise directions of magnetic declination and inclination. According to the requirements of the INTERMAGNET international geomagnetic network, absolute geomagnetic observations require the use of a proton magnetometer or Overhauser magnetometer for absolute observation of the geomagnetic field strength, and a DI-Flux magnetometer for absolute observation of magnetic declination and inclination. Geomagnetic stations must conduct absolute geomagnetic field observations at a frequency of no less than once a week. Currently, some existing geomagnetic stations use other methods for absolute geomagnetic field observations; new stations are recommended to use a combination of absolute geomagnetic instruments and a DI magnetometer for absolute vector geomagnetic field observations. According to the requirements of the INTERMAGNET international geomagnetic network, the magnetic field strength of the geomagnetic field can be provided by scalar magnetometers (such as Overhauser magnetometers and proton magnetometers), while the direction of the geomagnetic field needs to be measured by DI magnetometers. These magnetometers consist of a non-magnetic theodolite and a single-axis fluxgate sensor. The theodolite is used to find north for orientation, and the single-axis fluxgate sensor is used to determine the deflection and tilt angle of the magnetic field.

[0003] When using a DI magnetometer for absolute observations of geomagnetic declination and inclination, the measurement axis of the fluxgate magnetometer deviates from the optical axis of the theodolite, and the fluxgate magnetometer itself has zero-drift error. Therefore, the DI magnetometer typically employs an eight-step measurement method: measuring magnetic inclination and declination using four orientations—left-face, right-face, forward, and reverse—to eliminate these errors. Since manually measuring geomagnetic declination and inclination using a DI magnetometer is cumbersome, taking approximately 30 minutes for a single complete measurement, continuous observation is difficult. Generally, stations only take two sets of data per week to correct for relative measurements. Therefore, it is necessary to adopt automated measurement methods to obtain higher-precision geomagnetic field vector observation results with a higher sampling rate.

[0004] Geomagnetic observatories typically include relative observation rooms, using vector fluxgate magnetometers to conduct continuous relative observations of the Earth's magnetic field. As a relatively well-developed magnetic field measurement device, the three-axis fluxgate magnetometer can continuously measure the strength and direction of the magnetic field. However, due to limitations in manufacturing precision, it is difficult to maintain absolute orthogonality between the three measurement axes of a three-axis fluxgate magnetometer. Furthermore, fluxgate sensors often suffer from long-term drift problems, which generally prevents fluxgate magnetometers from being used as absolute observation instruments for the Earth's magnetic field.

[0005] Currently, several automated geomagnetic observation methods and instruments exist both domestically and internationally. Representative examples include the automatic fluxgate theodolite from the China Earthquake Administration and the GAUSS automatic geomagnetic observation system from a German team. The former operates on the same principle as the traditional DI magnetometer, but relies on a magnetless motor to drive the instrument's rotation and laser north-finding for orientation. The latter, however, uses a three-axis fluxgate sensor rotating around a fixed, known direction for observation, calculates the magnetic field in that direction using Euler transformation, and combines this with the observation results from the total field sensor to obtain the geomagnetic field vector. While both of these approaches can theoretically achieve automated geomagnetic field vector observation, they still have some drawbacks. Both methods rely on mechanical rotation to observe the magnetic field, which inherently limits their observation speed (each observation cycle takes approximately 30 minutes). Furthermore, the continuous rotation of the shaft and motor over a long period inevitably causes mechanical wear, affecting the long-term stability and reliability of the instrument's observations. Summary of the Invention

[0006] The purpose of this invention is to provide an absolute geomagnetic field vector observation method that avoids the impact of mechanical wear on the instrument's observation accuracy and stability, and achieves high-precision automatic continuous observation of three parameters: magnetic field strength, magnetic declination, and magnetic inclination.

[0007] This invention provides a method for observing absolute geomagnetic field vectors, comprising the following steps: S1: Determine the A-axis, B-axis, and C-axis of the three-axis fluxgate sensor used for observation, and use the three-axis magnetic sensor and magnetic shielding cylinder for calibration to correct the drift of the three-axis fluxgate sensor used for observation. S2: Using a non-magnetic theodolite and a three-axis fluxgate sensor for observation, determine the relative relationships between the A-axis, B-axis, and C-axis of the three-axis fluxgate sensor for observation and the optical axis of the telescope of the non-magnetic theodolite; S3: Adjust the non-magnetic theodolite and the three-axis fluxgate sensor for observation to any observation position, and determine the absolute orientation of the three-axis fluxgate sensor for observation based on the relative relationship between the A-axis, B-axis, and C-axis of the three-axis fluxgate sensor for observation and the optical axis of the telescope of the non-magnetic theodolite. S4: Obtain the magnetic field readings of the A-axis, B-axis, and C-axis of the three-axis fluxgate sensor used for observation, and calculate the geomagnetic field components in the geographic coordinate system based on the absolute orientation of the A-axis, B-axis, and C-axis of the three-axis fluxgate sensor used for observation. S5: Based on the geomagnetic field components in the geographic coordinate system, the total geomagnetic field intensity observed by the total field sensor is corrected to obtain the corrected absolute geomagnetic field vector, which includes the absolute geomagnetic declination and the absolute geomagnetic inclination. S6: Using the triaxial magnetic sensor for calibration, the magnetic shielding cylinder, and the calibration method described in step S1, the triaxial fluxgate sensor for observation is periodically subjected to automatic drift calibration, and the process returns to step S4.

[0008] The present invention also provides a computer program product, including a computer program that, when executed by a processor, implements the steps of the above-described absolute geomagnetic field vector observation method.

[0009] The absolute geomagnetic field vector observation method provided by this invention has the following beneficial effects: The absolute geomagnetic field vector observation method provided by this invention utilizes a non-magnetic theodolite and a three-axis fluxgate sensor to monitor the dynamic changes of the magnetic field vector, and a total field sensor to provide absolute geomagnetic field strength data, together achieving continuous and accurate observation of the Earth's magnetic field vector. Specifically, the absolute geomagnetic field vector observation method mainly consists of a non-magnetic theodolite, a vector three-axis fluxgate sensor, and a scalar total field sensor. The non-magnetic theodolite can rotate freely 360° in both the horizontal and vertical directions, and has low remanence, thus not interfering with magnetic field measurements. The fluxgate sensor is fixed to the telescope tube of the non-magnetic theodolite and adjusted to a suitable observation position according to the environment to continuously observe the geomagnetic field components. The scalar total field sensor is used to measure the accurate geomagnetic field strength and provides calibration data for the observation results of the fluxgate sensor. The vector magnetic field data from the fluxgate sensor, combined with the absolute magnetic field strength of the scalar magnetometer, enables automatic and continuous observation of three parameters: geomagnetic field strength, geomagnetic declination, and geomagnetic inclination. At regular intervals, the triaxial fluxgate sensor used for observation is automatically calibrated using a calibration triaxial magnetic sensor and a magnetic shielding cylinder to ensure the long-term reliability of the triaxial fluxgate sensor's observation results.

[0010] This invention enables automated, continuous, and highly accurate absolute observation of geomagnetic field vectors. By utilizing a fluxgate sensor for absolute geomagnetic observation, the temporal resolution of absolute geomagnetic field vector observation is improved, allowing for accurate observation of geomagnetic field signals at frequencies of 10 Hz or even higher. Furthermore, the instrument does not undergo mechanical rotation during continuous observation, avoiding the impact of mechanical wear on the instrument's observation accuracy and stability, while significantly improving the efficiency of absolute geomagnetic field vector observation. Attached Figure Description

[0011] The present invention will be further described below with reference to the accompanying drawings and embodiments. In the accompanying drawings: Figure 1 This is a flowchart of the absolute geomagnetic field vector observation method provided by the present invention; Figure 2 This is a schematic diagram of the observation system structure provided by the present invention; Figure 3 This is a schematic diagram of the drift correction of the three-axis fluxgate sensor for observation provided by the present invention; Figure 4 This is a schematic diagram of the A-axis angle calibration operation of the three-axis fluxgate sensor for observation provided by the present invention; Figure 5 This is a schematic diagram of the C-axis angle calibration operation of the three-axis fluxgate sensor for observation provided by the present invention; Figure 6 This is a schematic diagram of the B-axis angle calibration operation of the three-axis fluxgate sensor for observation provided by the present invention; Figure 7 This is a schematic diagram of the B-axis angle calculation for the three-axis fluxgate sensor for observation provided by the present invention. Detailed Implementation

[0012] To provide a clearer understanding of the technical features, objectives, and effects of the present invention, specific embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

[0013] Figure 1 A flowchart of the absolute geomagnetic field vector measurement method of this embodiment is shown. In this embodiment, the absolute geomagnetic field vector observation method includes the following steps: S1: Determine the A-axis, B-axis, and C-axis of the three-axis fluxgate sensor used for observation, and use the three-axis SERF (Spin-Exchange Relaxation-Free) magnetic sensor as the calibration three-axis magnetic sensor and magnetic shielding cylinder to correct the drift of the three-axis fluxgate sensor used for observation; In one exemplary embodiment, step S1 specifically includes: S11: The observation axis that is approximately parallel to the optical axis of the telescope of the non-magnetic theodolite is denoted as axis A, the observation axis that is approximately parallel to the rotation axis of the telescope of the non-magnetic theodolite is denoted as axis B, and the other observation axis is denoted as axis C; rotate the non-magnetic theodolite and the observation three-axis fluxgate sensor to a fixed orientation. S12: Place the magnetic shielding cylinder in a fixed spatial orientation near the non-magnetic theodolite and the three-axis fluxgate sensor used for observation, and adjust the three-axis magnetic sensor used for calibration to be placed in the same orientation as the three-axis fluxgate sensor used for observation. S13: Keep the orientation of the triaxial magnetic sensor used for calibration unchanged, and move it to a fixed depth of the magnetic shielding cylinder to measure the magnetic field. This will obtain the magnitude of the residual field of the triaxial fluxgate sensor used for observation along different axes, i.e., the residual field of the magnetic shielding cylinder. S14: Keeping the spatial orientation of the magnetic shielding cylinder unchanged, move the magnetic shielding cylinder to the location of the non-magnetic theodolite used for observation, so that the three-axis fluxgate sensor used for observation enters the magnetic shielding cylinder and reaches the fixed depth described in step S13, and obtain a set of measurement results from the three-axis fluxgate sensor used for observation. After the measurement is completed, the magnetic shielding cylinder is removed; the drift value of the triaxial fluxgate sensor is calculated using the measurement results of the triaxial fluxgate sensor and the residual field of the magnetic shielding cylinder obtained in step S13, as shown in the formula:

[0014] in Measurement results of different observation axes of the triaxial fluxgate sensor used for observation. The residual fields along different axes of the triaxial fluxgate sensor used for observation of the magnetic shielding field. These are the drift values ​​corresponding to the three observation axes of the triaxial fluxgate sensor.

[0015] S15: Using the drift value of the three-axis fluxgate sensor used for observation calculated in step S14, correct the subsequent observation results of the three-axis fluxgate sensor used for observation.

[0016] S2: Using a non-magnetic theodolite and a three-axis fluxgate sensor for observation, determine the relative relationship between the A-axis, B-axis, and C-axis of the three-axis fluxgate sensor and the optical axis of the non-magnetic theodolite.

[0017] In one exemplary embodiment, step S2 specifically includes: S21: Using the A-axis of the three-axis fluxgate sensor used for observation and the observation method of the fluxgate theodolite, the relative relationship between the A-axis of the three-axis fluxgate sensor used for observation and the optical axis of the non-magnetic theodolite is obtained; The relative relationship between the A-axis of the three-axis fluxgate sensor used for observation and the optical axis of the non-magnetic theodolite includes the horizontal and vertical angles between the A-axis and the optical axis of the non-magnetic theodolite. S22: Using the C-axis of the three-axis fluxgate sensor used for observation and the observation method of the fluxgate theodolite, the relative relationship between the C-axis of the three-axis fluxgate sensor used for observation and the optical axis of the non-magnetic theodolite is obtained; The relative relationship between the C-axis of the three-axis fluxgate sensor used for observation and the optical axis of the non-magnetic theodolite includes the horizontal and vertical angles between the C-axis and the optical axis of the non-magnetic theodolite. S23: Determine the relative relationship between the B-axis of the three-axis fluxgate sensor used for observation and the optical axis of the non-magnetic theodolite using a non-magnetic theodolite; The relative relationship between the B-axis of the triaxial fluxgate sensor used for observation and the optical axis of the non-magnetic theodolite includes the angle between the B-axis and the optical axis of the non-magnetic theodolite, as well as the rotation phase.

[0018] In one exemplary embodiment, step S23 specifically includes: S231: Adjust the telescope of the non-magnetic theodolite to a horizontal optical axis, and rotate the vertical axis of the non-magnetic theodolite to make the B-axis reading of the three-axis fluxgate sensor used for observation reach 0. S232: Rotate the horizontal axis of the non-magnetic theodolite to obtain the reading of the horizontal axis's scale circle and the magnetic field reading of the B-axis of the three-axis fluxgate sensor used for observation; S233: Based on the reading of the horizontal rotating shaft and the magnetic field reading of the B-axis of the three-axis fluxgate sensor used for observation, the optimal fitting equation is obtained by using a trigonometric function fitting method. S234: Based on the optimal fitting equation, the relative relationship between the B-axis of the three-axis fluxgate sensor used for observation and the optical axis of the non-magnetic theodolite is obtained.

[0019] S3: Adjust the non-magnetic theodolite and the three-axis fluxgate sensor for observation to any observation position, and determine the absolute orientation of the three-axis fluxgate sensor for observation based on the relative relationship between the A-axis, B-axis, and C-axis of the three-axis fluxgate sensor for observation and the optical axis of the telescope of the non-magnetic theodolite. In one exemplary embodiment, step S3 specifically includes: S31: Based on the magnetic field environment and geographical location of the observation location, adjust the non-magnetic theodolite to any observation azimuth and record the readings of the vertical and horizontal axes of the non-magnetic theodolite at this time. S32: Based on the relative relationship between the A-axis, B-axis, and C-axis of the three-axis fluxgate sensor used for observation and the optical axis of the telescope of the non-magnetic theodolite, and the dial readings of the vertical and horizontal rotating axes, the absolute orientation of the A-axis, B-axis, and C-axis of the three-axis fluxgate sensor used for observation is obtained.

[0020] In one exemplary embodiment, step S32 specifically includes: S321: Based on the readings of the vertical and horizontal rotation axes of the non-magnetic theodolite, obtain the optical axis deflection angle, optical axis tilt angle, and optical axis direction vector in the geographic coordinate system; S322: Based on the optical axis deflection angle, optical axis tilt angle, optical axis direction vector, and the relative relationship between the A-axis, B-axis, and C-axis of the three-axis fluxgate sensor used for observation and the optical axis of the non-magnetic theodolite, determine the absolute orientation of the A-axis, B-axis, and C-axis of the three-axis fluxgate sensor used for observation; the absolute orientation of the A-axis, B-axis, and C-axis of the three-axis fluxgate sensor used for observation includes the A-axis direction vector, the B-axis direction vector, and the C-axis direction vector.

[0021] S4: Obtain the magnetic field readings of the A-axis, B-axis, and C-axis of the three-axis fluxgate sensor used for observation, and calculate the geomagnetic field components in the geographic coordinate system based on the absolute orientation of the A-axis, B-axis, and C-axis of the three-axis fluxgate sensor used for observation. In one exemplary embodiment, step S4 specifically includes: Obtain the magnetic field readings of the A-axis, B-axis, and C-axis of the triaxial fluxgate sensor used for observation, and calculate the geomagnetic field components in the geographic coordinate system based on the absolute orientation of the A-axis, B-axis, and C-axis of the triaxial fluxgate sensor. The geomagnetic field components include the northward, eastward, and downward magnetic components, as shown in the formula:

[0022] Where A, B, and C represent the magnetic field readings of the A-axis, B-axis, and C-axis of the triaxial fluxgate sensor used for observation. , , , , , , , , These represent the components of the A-axis, B-axis, and C-axis direction vectors of the three-axis fluxgate sensor used for observation; , , These are the northward, eastward, and downward components of the geomagnetic field without total field correction.

[0023] S5: Based on the geomagnetic field components in the geographic coordinate system, the absolute geomagnetic field strength observed by the total field sensor is used for correction to obtain the corrected absolute geomagnetic field vector, which includes the absolute geomagnetic declination, absolute geomagnetic inclination, and geomagnetic field strength.

[0024] In one exemplary embodiment, step S5 specifically includes: S51: Based on the geomagnetic field components in the aforementioned geographic coordinate system, the geomagnetic field intensity is corrected using the data observed by the total field sensor to obtain the corrected geomagnetic vector, as shown in the formula: , in, This is the corrected geomagnetic vector; The observed and calculated values ​​of the triaxial fluxgate sensor used for the observation of the correction point; and These represent the three-axis fluxgate sensors used for observation. and The observation value corresponding to the time; and This indicates the total field magnetometer at two different times. and Total field value observed; S52: Based on the corrected geomagnetic vector, the absolute geomagnetic declination, absolute geomagnetic inclination, and absolute geomagnetic field strength, i.e., the absolute geomagnetic field vector, are obtained, as shown in the formula: , in, The absolute geomagnetic field strength is ; , , These are the absolute observation results of the northward, eastward, and downward components of the geomagnetic field, respectively. and These are, respectively, absolute magnetic declination and absolute magnetic inclination.

[0025] S6: Using the triaxial magnetic sensor and magnetic shielding cylinder for calibration, the triaxial fluxgate sensor for observation is periodically automatically drift-corrected using the calibration method in step S1 to ensure the long-term observation stability and reliability of the instrument. Return to step S4.

[0026] In an exemplary embodiment, the automatic drift correction described in step S6 can be achieved through the following steps: S61: Fix the triaxial magnetic sensor used for calibration and the triaxial fluxgate sensor used for observation in the observation orientation of step S3; S62: The magnetic shielding cylinder is automatically moved by the track and motor to the triaxial magnetic sensor used for calibration to measure the residual field size of the triaxial fluxgate sensor used for observation in different axes corresponding to the magnetic shielding cylinder; S63: The magnetic shielding cylinder is automatically moved to the three-axis fluxgate sensor for observation via a track and motor to correct the drift of the three-axis fluxgate sensor for observation; S64: The magnetic shielding cylinder is automatically moved away from the three-axis fluxgate sensor used for observation via a track and motor. The three-axis fluxgate sensor used for observation continues to conduct geomagnetic field observations.

[0027] In some embodiments, the above-described absolute geomagnetic field vector observation method can also be implemented in the following ways.

[0028] Figure 2This is a schematic diagram of the observation system structure provided in this embodiment; in this embodiment, the absolute geomagnetic field vector observation method includes the following steps: Step 1: Place a total field magnetometer (using an Overhauser magnetometer as an example) on a magnetic measuring pier and begin continuous measurements.

[0029] Step 2: Place a non-magnetic theodolite on another magnetic measuring pier 3m away from the total field sensor, and fix the three-axis fluxgate sensor for observation on its telescope tube. One observation axis of the three-axis fluxgate sensor is approximately parallel to the telescope tube and is denoted as axis A. Another observation axis is approximately parallel to the rotation axis of the telescope tube and is denoted as axis B. The other observation axis is denoted as axis C.

[0030] Step 3: Using a triaxial fluxgate sensor as the calibration triaxial magnetic sensor and a magnetic shielding cylinder, the drift of the triaxial fluxgate sensor used for observation is corrected: Figure 3 The diagram shown is a schematic diagram of the drift correction of the three-axis fluxgate sensor for observation provided in this embodiment; Step 31: Rotate the non-magnetic theodolite and the three-axis fluxgate sensor used for observation to a fixed orientation, so that... Figure 3 The orientation of the three-axis fluxgate sensor used for observation is taken as an example; Step 32: Place the magnetic shielding cylinder in a fixed spatial orientation near the non-magnetic theodolite and the three-axis fluxgate sensor used for observation, and adjust the three-axis fluxgate sensor used for calibration to be placed in the same orientation as the three-axis fluxgate sensor used for observation. Step 33: Keeping the orientation of the triaxial fluxgate sensor used for calibration unchanged, move it to a fixed depth in the magnetic shielding cylinder to measure the magnetic field and obtain the first set of measurement results. ; Step 34: Rotate the triaxial fluxgate sensor used for calibration 180° around axis A' and observe the magnetic field, recording the measurement results. and The triaxial fluxgate sensor used for calibration was rotated 180° around the B' axis and the magnetic field was observed and the measurement results were recorded. The residual field matrix of the magnetic shielding cylinder was calculated. For example, in the formula: ; Step 35: Keeping the spatial orientation of the magnetic shielding cylinder unchanged, move the magnetic shielding cylinder to the location of the non-magnetic theodolite used for observation, so that the three-axis fluxgate sensor used for observation enters the magnetic shielding cylinder and reaches the fixed depth described in Step 34, and obtain a set of measurement results from the three-axis fluxgate sensor used for observation. After the measurement is completed, the magnetic shielding cylinder is removed; the drift value of the triaxial fluxgate sensor used for observation is calculated using the measurement results and the residual field of the magnetic shielding cylinder obtained in step S13, as shown in the formula: ; in , ,and These correspond to the drift values ​​of the A-axis, B-axis, and C-axis of the three-axis fluxgate sensor used for observation, respectively. Step 36: In the computer program, subtract the corresponding drift values ​​from the A-axis, B-axis, and C-axis of the triaxial fluxgate sensor used for observation, respectively. , ,and This corrects the drift error of the three measurement axes of the three-axis fluxgate sensor used for observation.

[0031] Step 4: Determine the relative relationships between the A-axis, B-axis, and C-axis of the triaxial fluxgate sensor used for observation and the optical axis of the theodolite: Step 41: First, determine the relative relationship between the A-axis of the three-axis fluxgate sensor used for observation and the optical axis of the theodolite. Using the A-axis as the magnetic field measurement axis, observe the magnetic declination and magnetic inclination according to the measurement method of the fluxgate theodolite. The specific observation process is as follows. like Figure 4 The diagram shown is a schematic of the A-axis angle calibration operation of the three-axis fluxgate sensor for observation provided in this embodiment; Step 411: Place the non-magnetic theodolite, adjust the center of the non-magnetic theodolite to be directly above the magnetic measuring pier reference point, and adjust the non-magnetic theodolite to have its optical axis horizontal; Step 412: Observe the geomagnetic declination, first turn the face left ( Right side () ) Observe the target object outside the window from the azimuth angle ( ) And read the corresponding horizontal circle reading. , Calculate the target data TD. , Adjust the horizontal and vertical axes so that the fluxgate A-axis reaches a reading of 0 in all four directions: forward left, forward right, reverse left, and reverse right. Simultaneously record the dial readings of the four vertical axes: , , , At this point, the average value of the magnetic midplane can be obtained. ,

[0032] Calculate the geomagnetic declination ,

[0033] Step 413: Observe the geomagnetic inclination and adjust the vertical axis until the dial reading is... Adjust the vertical dial to a position where the fluxgate reading is 0. and The observation was performed, and then the horizontal circle was rotated to... Adjust the vertical dial until the fluxgate reading is 0, then proceed. and The observation, Calculate the geomagnetic tilt angle ,

[0034] Step 414: Calculate the horizontal deviation of the fluxgate A-axis relative to the optical axis. Deviation from vertical direction ,

[0035]

[0036] Step 42: Determine the relative relationship between the C-axis of the three-axis fluxgate sensor used for observation and the optical axis of the theodolite. Using the fluxgate C-axis as the magnetic field measurement axis, observe the magnetic declination and magnetic inclination. The specific observation procedure is as follows. like Figure 5 The diagram shown is a schematic of the C-axis angle calibration operation of the three-axis fluxgate sensor for observation provided in this embodiment; Step 421: Adjust the non-magnetic theodolite until the optical axis is perpendicular; Step 422: Adjust the horizontal and vertical axes so that the fluxgate C-axis reaches a reading of 0 in all four positions: forward left, forward right, reverse left, and reverse right. Simultaneously record the readings of the four vertical axis dials: , , , At this point, the average value MM of the magnetic midplane can be obtained. C ,

[0037] Calculate the geomagnetic declination ,

[0038] Step 423: Observe the geomagnetic inclination and adjust the vertical axis until the dial reading is... Adjust the vertical dial to a position where the fluxgate reading is 0. and The observation was performed, and then the vertical axis was rotated to the dial to read the value. Adjust the direction of the horizontal axis until the fluxgate reading is 0, then proceed. and The observation, Calculate the geomagnetic tilt angle ,

[0039] Step 424: Calculate the horizontal deviation of the fluxgate C-axis relative to the optical axis. Deviation from vertical direction ,

[0040]

[0041] Step 43: Determine the relative relationship between the B-axis of the triaxial fluxgate sensor used for observation and the optical axis of the theodolite. The specific observation procedure is as follows. like Figure 6 The diagram shown is a schematic of the B-axis angle calibration operation of the three-axis fluxgate sensor for observation provided in this embodiment; as shown... Figure 7 The figure shown is a schematic diagram of the B-axis angle calculation of the three-axis fluxgate sensor for observation provided in this embodiment; Step 431: Adjust the telescope to a horizontal optical axis, and rotate the vertical axis until the fluxgate B-axis reading reaches 0. Step 432: Rotate the horizontal shaft and record the reading. and the reading of the fluxgate B-axis

[0042] Step 433: Use trigonometric functions to... and The data is fitted to obtain the optimal fitting equation.

[0043] In the fitting results, That is, it can show the angle by which the B-axis of the fluxgate deviates from the rotation axis. ), The calculation formula is as follows:

[0044] Where F represents the geomagnetic field strength measured by the total field magnetometer. Step 434: As Figure 5 As shown, The change in the magnetic field component caused by the deflection direction of the rotation axis (optical axis) The magnetic field tilt angle is in S333. The radius of the circle represents the angle by which the magnetic axis deviates from the optical axis, thus allowing us to calculate the angle by which the optical axis deviates from the magnetic east direction. The formula is as follows:

[0045] in The geomagnetic tilt at this moment can be obtained from the geomagnetic tilt value measured in the previous step. Instead, F represents the intensity of the Earth's magnetic field at this time, which is obtained by averaging the data measured by the total field magnetometer during the rotation correction process. Step 5: Adjust the triaxial fluxgate sensor used for observation to the observation orientation, calculate the absolute orientation of the A-axis, B-axis, and C-axis of the triaxial fluxgate sensor, and then calculate and obtain the components of the geomagnetic field in the geographic coordinate system: Step 51: Keep the telescope's optical axis horizontal, rotate the horizontal circle so that the B-axis of the three-axis fluxgate sensor used for observation is oriented towards magnetic east, and the reading reaches less than [value missing]. Then rotate the vertical circle so that the A-axis of the triaxial fluxgate sensor used for observation points upwards perpendicular to the magnetic field direction, and the reading reaches less than [value missing]. Then, the horizontal and vertical circles were repeatedly adjusted until the readings of the A and B axes of the triaxial fluxgate sensor used for observation were simultaneously less than [a certain value]. At this time, the C-axis of the three-axis fluxgate sensor used for observation points in the direction of the approximate Earth's magnetic field. Step 52: Calculate the absolute orientation of the A-axis, B-axis, and C-axis of the triaxial fluxgate sensor used for observation. Step 521: Read the dial readings of the horizontal and vertical axes. , Converted to the angle of the optical axis ,inclination They are respectively,

[0046]

[0047] Corresponding optical axis direction vector for,

[0048] Step 422: Based on the angular deviations between the fluxgate A and C axes and the optical axis obtained in steps 314 and 324, determine the direction vectors of the A and C axes. First, when the dial readings of both the horizontal and vertical axes are 0, that is, the optical axis points... When considering orientation, axes A and C can be regarded as optical axes around which the light rotates. , When the two axes are rotated by a certain angle, the directions of the two magnetic axes A and C can be calculated using the following formula.

[0049]

[0050]

[0051]

[0052] in, , The directions of the two magnetic axes are calculated. Next, the orientation of axes A and C during actual observation is calculated. At this time, the reading of the horizontal rotating circle is expressed as a rotation around the axis. When rotated, the vertical circle reading appears as a rotation around the axis. Rotate, For axis A,

[0053]

[0054] The direction vector of the A-axis; For the C-axis,

[0055]

[0056] The direction vector is the C-axis. The B-axis can be considered as having a fixed angle with the horizontal axis of rotation. And the phase is the horizontal axis reading, calculated using the following formula: When the horizontal shaft reading is 0

[0057]

[0058] The direction vector of the B-axis; Step 53: Calculate the components of the geomagnetic field in the geographic coordinate system based on the observation data from the three-axis fluxgate sensor and the absolute orientations of its A, B, and C axes. Since the data for each observation axis of the fluxgate sensor are projections of the geomagnetic field in that direction, the following system of equations can be solved to obtain the geomagnetic field vector. :

[0059] Where A, B, and C represent the observation data from the triaxial fluxgate sensor used for observation, and , , , , , , , , These represent the components of the three-axis direction vectors of the three-axis fluxgate sensor used for observation. , , The geomagnetic field vector The three components.

[0060] Step 6: Use the absolute geomagnetic field strength data obtained from the total field magnetometer to correct the data of the three-axis fluxgate sensor used for the observation.

[0061]

[0062] in, and This indicates that the total field sensor is at two different times. and The observed absolute geomagnetic field strength; and These represent the three-axis fluxgate sensors used for observation. and The observation value corresponding to the time; and The observation values ​​from the triaxial fluxgate sensor used to represent the calibration point. This is the corrected geomagnetic vector.

[0063] Step 7: Calculate the absolute geomagnetic field strength based on the corrected geomagnetic vector. Absolute magnetic declination and absolute geomagnetic tilt , which is the absolute geomagnetic field vector.

[0064]

[0065] Where N, E, and D are geomagnetic vectors. The three components of the geomagnetic field are the absolute observation results of the northward, eastward, and downward components.

[0066] Step 8: Using the correction method described in Step 3, periodically and automatically perform drift correction on the triaxial fluxgate sensor used for observation to ensure the long-term observation stability and reliability of the instrument.

[0067] Step 81: Fix the triaxial magnetic sensor used for calibration and the triaxial fluxgate sensor used for observation in the observation orientation described in S3; Step 82: Move the magnetic shielding cylinder automatically via the track and motor to the triaxial magnetic sensor used for calibration and measure the residual field magnitude of the triaxial fluxgate sensor used for observation at different axes corresponding to the magnetic shielding cylinder; Step 83: The magnetic shielding cylinder is automatically moved to the three-axis fluxgate sensor for observation via the track and motor to correct the drift of the three-axis fluxgate sensor for observation; Step 84: The magnetic shielding cylinder is automatically moved away from the three-axis fluxgate sensor used for observation via the track and motor. The three-axis fluxgate sensor used for observation continues to conduct geomagnetic field observations.

[0068] This embodiment provides a computer program product, including a computer program that, when executed by a processor, implements the steps of the above-described absolute geomagnetic field vector observation method.

[0069] The embodiments of the present invention have been described above with reference to the accompanying drawings. However, the present invention is not limited to the specific embodiments described above. The specific embodiments described above are merely illustrative and not restrictive. Those skilled in the art can make many other forms under the guidance of the present invention without departing from the spirit and scope of the claims. All of these forms are within the protection scope of the present invention.

Claims

1. A method for absolute geomagnetic field vector observation, characterized in that, Includes the following steps: S1: Determine the A-axis, B-axis, and C-axis of the three-axis fluxgate sensor used for observation, and use the three-axis magnetic sensor and magnetic shielding cylinder for calibration to correct the drift of the three-axis fluxgate sensor used for observation. S2: Using a non-magnetic theodolite and a three-axis fluxgate sensor for observation, determine the relative relationships between the A-axis, B-axis, and C-axis of the three-axis fluxgate sensor for observation and the optical axis of the telescope of the non-magnetic theodolite; S3: Adjust the non-magnetic theodolite and the three-axis fluxgate sensor for observation to any observation position, and determine the absolute orientation of the three-axis fluxgate sensor for observation based on the relative relationship between the A-axis, B-axis, and C-axis of the three-axis fluxgate sensor for observation and the optical axis of the telescope of the non-magnetic theodolite. S4: Obtain the magnetic field readings of the A-axis, B-axis, and C-axis of the three-axis fluxgate sensor used for observation, and calculate the geomagnetic field components in the geographic coordinate system based on the absolute orientation of the A-axis, B-axis, and C-axis of the three-axis fluxgate sensor used for observation. S5: Based on the geomagnetic field components in the geographic coordinate system, the total geomagnetic field intensity observed by the total field sensor is corrected to obtain the corrected absolute geomagnetic field vector, which includes the absolute geomagnetic declination and the absolute geomagnetic inclination. S6: Using the triaxial magnetic sensor for calibration, the magnetic shielding cylinder, and the calibration method of step S1, the triaxial fluxgate sensor for observation is periodically automatically drift-corrected, and the process returns to step S4.

2. The absolute geomagnetic field vector observation method as described in claim 1, characterized in that, Step S1 specifically includes: S11: The observation axis that is approximately parallel to the optical axis of the telescope of the non-magnetic theodolite is denoted as axis A, the observation axis that is approximately parallel to the rotation axis of the telescope of the non-magnetic theodolite is denoted as axis B, and the other observation axis is denoted as axis C; rotate the non-magnetic theodolite and the observation three-axis fluxgate sensor to a fixed orientation. S12: Place the magnetic shielding cylinder in a fixed spatial orientation near the non-magnetic theodolite and the three-axis fluxgate sensor used for observation, and adjust the three-axis magnetic sensor used for calibration to be placed in the same orientation as the three-axis fluxgate sensor used for observation. S13: Keeping the orientation of the triaxial magnetic sensor used for calibration unchanged, translate it to a fixed depth of the magnetic shielding cylinder to measure the magnetic field and obtain the residual field of the magnetic shielding cylinder; S14: Keeping the spatial orientation of the magnetic shielding cylinder unchanged, move the magnetic shielding cylinder to the location of the non-magnetic theodolite used for observation, so that the three-axis fluxgate sensor used for observation enters the magnetic shielding cylinder and reaches the fixed depth mentioned in step S13, and obtain a set of measurement results of the three-axis fluxgate sensor used for observation. After the measurement is completed, remove the magnetic shielding cylinder; calculate the drift value of the three-axis fluxgate sensor used for observation using the measurement results of the three-axis fluxgate sensor used for observation and the residual field of the magnetic shielding cylinder obtained in step S13. S15: Using the drift value of the three-axis fluxgate sensor used for observation obtained in step S14, correct the subsequent observation results of the three-axis fluxgate sensor used for observation.

3. The absolute geomagnetic field vector observation method as described in claim 1, characterized in that, Step S2 specifically includes: S21: Using the A-axis of the three-axis fluxgate sensor used for observation and the observation method of the fluxgate theodolite, the relative relationship between the A-axis of the three-axis fluxgate sensor used for observation and the optical axis of the non-magnetic theodolite is obtained; The relative relationship between the A-axis of the three-axis fluxgate sensor used for observation and the optical axis of the non-magnetic theodolite includes the horizontal and vertical angles between the A-axis and the optical axis of the non-magnetic theodolite. S22: Using the C-axis of the three-axis fluxgate sensor used for observation and the observation method of the fluxgate theodolite, the relative relationship between the C-axis of the three-axis fluxgate sensor used for observation and the optical axis of the non-magnetic theodolite is obtained; The relative relationship between the C-axis of the three-axis fluxgate sensor used for observation and the optical axis of the non-magnetic theodolite includes the horizontal and vertical angles between the C-axis and the optical axis of the non-magnetic theodolite. S23: Determine the relative relationship between the B-axis of the three-axis fluxgate sensor used for observation and the optical axis of the non-magnetic theodolite using a non-magnetic theodolite; The relative relationship between the B-axis of the triaxial fluxgate sensor used for observation and the optical axis of the non-magnetic theodolite includes the angle between the B-axis and the optical axis of the non-magnetic theodolite, as well as the rotation phase.

4. The absolute geomagnetic field vector observation method as described in claim 3, characterized in that, Step S23 specifically includes: S231: Adjust the telescope of the non-magnetic theodolite to a horizontal optical axis, and rotate the vertical axis of the non-magnetic theodolite to make the B-axis reading of the three-axis fluxgate sensor used for observation reach 0. S232: Rotate the horizontal axis of the non-magnetic theodolite to obtain the reading of the horizontal axis's scale circle and the magnetic field reading of the B-axis of the three-axis fluxgate sensor used for observation; S233: Based on the reading of the horizontal rotating shaft and the magnetic field reading of the B-axis of the three-axis fluxgate sensor used for observation, the optimal fitting equation is obtained by using a trigonometric function fitting method. S234: Based on the optimal fitting equation, the relative relationship between the B-axis of the three-axis fluxgate sensor used for observation and the optical axis of the non-magnetic theodolite is obtained.

5. The absolute geomagnetic field vector observation method as described in claim 1, characterized in that, Step S3 specifically includes: S31: Based on the magnetic field environment and geographical location of the observation location, adjust the non-magnetic theodolite to any observation azimuth and record the readings of the vertical and horizontal axes of the non-magnetic theodolite at this time. S32: Based on the relative relationship between the A-axis, B-axis, and C-axis of the three-axis fluxgate sensor used for observation and the optical axis of the telescope of the non-magnetic theodolite, and the dial readings of the vertical and horizontal rotating axes, the absolute orientation of the A-axis, B-axis, and C-axis of the three-axis fluxgate sensor used for observation is obtained.

6. The absolute geomagnetic field vector observation method as described in claim 5, characterized in that, Step S32 specifically includes: S321: Based on the readings of the vertical and horizontal rotation axes of the non-magnetic theodolite, obtain the optical axis deflection angle, optical axis tilt angle, and optical axis direction vector in the geographic coordinate system; S322: Based on the optical axis deflection angle, optical axis tilt angle, optical axis direction vector, and the relative relationship between the A-axis, B-axis, and C-axis of the three-axis fluxgate sensor used for observation and the optical axis of the non-magnetic theodolite, determine the absolute orientation of the A-axis, B-axis, and C-axis of the three-axis fluxgate sensor used for observation; the absolute orientation of the A-axis, B-axis, and C-axis of the three-axis fluxgate sensor used for observation includes the A-axis direction vector, the B-axis direction vector, and the C-axis direction vector.

7. The absolute geomagnetic field vector observation method according to claim 1, characterized in that, Step S4 specifically includes: Obtain the magnetic field readings of the A-axis, B-axis, and C-axis of the triaxial fluxgate sensor used for observation, and calculate the geomagnetic field components in the geographic coordinate system based on the absolute orientation of the A-axis, B-axis, and C-axis of the triaxial fluxgate sensor. The geomagnetic field components include the northward, eastward, and downward magnetic components, as shown in the formula: Where A, B, and C represent the magnetic field readings of the A-axis, B-axis, and C-axis of the triaxial fluxgate sensor used for observation. , , , , , , , , These represent the components of the A-axis, B-axis, and C-axis direction vectors of the three-axis fluxgate sensor used for observation; , , These are the northward, eastward, and downward components of the geomagnetic field without total field correction.

8. The absolute geomagnetic field vector observation method according to claim 1, characterized in that, Step S5 specifically includes: S51: Based on the geomagnetic field components in the aforementioned geographic coordinate system, the absolute geomagnetic field intensity observed by the total field sensor is used for correction to obtain the corrected geomagnetic vector, as shown in the formula: ， in, This is the corrected geomagnetic vector; The observed and calculated values ​​of the triaxial fluxgate sensor used for the observation of the correction point; and These represent the three-axis fluxgate sensors used for observation. and The observation value corresponding to the time; and This indicates the total field magnetometer at two different times. and Total field value observed; S52: Based on the corrected geomagnetic vector, the absolute geomagnetic declination, absolute geomagnetic inclination, and absolute geomagnetic field strength, i.e., the absolute geomagnetic field vector, are obtained, as shown in the formula: ， in, This refers to the absolute geomagnetic field strength. , , These are the absolute observation results of the northward, eastward, and downward components of the geomagnetic field, respectively. and These are, respectively, absolute magnetic declination and absolute magnetic inclination.

9. The absolute geomagnetic field vector observation method according to claim 1, characterized in that, Step S6 specifically includes: S61: Fix the triaxial magnetic sensor used for calibration and the triaxial fluxgate sensor used for observation in the observation orientation of step S3; S62: The magnetic shielding cylinder is automatically moved by the track and motor to the triaxial magnetic sensor used for calibration to measure the residual field size of the triaxial fluxgate sensor used for observation in different axes corresponding to the magnetic shielding cylinder; S63: The magnetic shielding cylinder is automatically moved to the three-axis fluxgate sensor for observation via a track and motor to correct the drift of the three-axis fluxgate sensor for observation; S64: The magnetic shielding cylinder is automatically moved away from the three-axis fluxgate sensor used for observation via a track and motor. The three-axis fluxgate sensor used for observation continues to conduct geomagnetic field observations.

10. A computer program product, comprising a computer program, characterized in that, When executed by a processor, the computer program implements the steps of the absolute geomagnetic field vector observation method according to any one of claims 1-9.

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