Magnetic declination measuring method combining gyroscopic total station and geomagnetic theodolite

Abstract

The invention discloses a gyroscopic total station and geomagnetic theodolite combined magnetic declination measurement method, which comprises the following steps of: 1, selecting a true north position edge to carry out gyroscopic orientation measurement, and calculating instrument constants of a gyroscopic total station; 2, erecting a gyroscopic total station and a geomagnetic theodolite at two ends of the measuring line; 3, starting the gyroscopic total station to carry out gyroscopic north-seeking measurement; 4, the gyroscopic total station is used for aiming at the geomagnetic theodolite installation point, and the true north azimuth angle in the direction from the gyroscopic total station measurement point to the geomagnetic theodolite measurement point is measured; 5, measuring a geomagnetic azimuth angle by adopting a geomagnetic theodolite; 6, returning to the true north position edge to carry out gyroscopic orientation measurement, and calculating instrument constants of the gyroscopic total station; if the two constant changes are smaller than 2 delta, the requirement is met, and otherwise, constant changing is performed again; and 7, inversely calculating the true north azimuth angle of the installation point of the geomagnetic theodolite, and calculating the magnetic declination of the installation point of the geomagnetic theodolite. The device is high in measurement efficiency, high in maneuverability, and low in labor intensity and measurement cost.

Description

Technical Field

[0001] The present invention relates to the technical field of engineering surveying, and in particular to a magnetic declination measurement method combining a gyro total station and a geomagnetic theodolite. Background Art

[0002] The Earth's magnetic field is a fundamental geophysical field. Because the magnetic north and south poles do not coincide with the geographic north and south poles, there is a deviation between the magnetic meridian and the true meridian, known as magnetic declination. This declination is a crucial fundamental data point for land, sea, and air transportation navigation. Its magnitude and direction change slowly over time, making it crucial for military, meteorological, airport construction, tunnel engineering, and basic surveying and mapping.

[0003] Currently, methods for obtaining magnetic declination can be divided into model calculation and instrument measurement. Model calculation methods often use the WMM model, EMM model, and IGRF model, but the accuracy of the magnetic declination obtained is often low. The actual measurement method mainly combines a geomagnetic theodolite with GNSS technology. First, a location with a good geomagnetic observation environment is selected to select a measurement line and bury the measurement points. GNSS technology is then used to obtain the coordinates of the measurement points and calculate the true north azimuth of the measurement line. Next, the geomagnetic azimuth of the corresponding measurement line is measured using a geomagnetic theodolite. Finally, the magnetic declination value at the measurement point is calculated by combining the true azimuth and the geomagnetic azimuth.

[0004] This type of method has the following problems when measuring:

[0005] First, the measurement efficiency is low. The process from GNSS measuring point coordinates to calculating azimuth is complex and the data processing time is long, which greatly reduces the efficiency of magnetic declination measurement.

[0006] Second, the point location is not very flexible. If the point location and azimuth information obtained through GNSS observation is interfered with by abnormal magnetic fields during geomagnetic measurement, the point location needs to be changed and GNSS coordinate measurement and azimuth calculation need to be repeated, which brings great inconvenience to the measurement work. Summary of the Invention

[0007] In view of the shortcomings of the existing technology, the present invention provides a method for measuring magnetic declination by combining a gyro total station with a geomagnetic theodolite, which has significant practical significance and practical value in improving the measurement efficiency of magnetic declination and reducing measurement costs.

[0008] In order to achieve the above object, the present invention adopts the following technical solutions:

[0009] A method for measuring magnetic declination by combining a gyro total station with a geomagnetic theodolite comprises the following steps:

[0010] The first step is to select the true north azimuth to perform gyroscopic orientation measurement and calculate the instrument constant of the gyroscopic total station;

[0011] The second step is to set up a gyro total station and a geomagnetic theodolite at the two ends of the survey line;

[0012] The third step is to start the north-seeking function of the gyro total station and start the gyro north-seeking measurement;

[0013] Step 4: After the gyroscopic north-seeking measurement is completed, the gyroscopic total station is used to sight the geomagnetic theodolite installation point, and the true north azimuth from the gyroscopic total station measurement point to the geomagnetic theodolite measurement point is measured;

[0014] The fifth step is to use a geomagnetic theodolite to measure the geomagnetic azimuth from the geomagnetic theodolite installation point to the gyro total station installation point;

[0015] Step 6: Return to the true north azimuth of the first step, perform gyroscopic orientation measurement, and calculate the instrument constant of the gyroscopic total station. Compare the two changes in the instrument constant of the gyroscopic total station. If the change is ≤ 2δ, the requirement is met. Otherwise, the instrument constant needs to be remeasured, where δ is the nominal accuracy of the gyroscopic total station.

[0016] The seventh step is to reversely calculate the true north azimuth of the geomagnetic theodolite installation point based on the 180° difference between the positive and negative angles and the true north azimuth measured by the gyro total station, and calculate the magnetic declination at the geomagnetic theodolite installation point based on the magnetic azimuth measured by the geomagnetic theodolite.

[0017] Furthermore, in the seventh step, the magnetic declination angle at the installation point of the geomagnetic theodolite is calculated as follows:

[0018] D=A±180°-M (2)

[0019] Where A represents the true north azimuth measured by the gyro total station. If A < 180°, use “+” in Equation 1; if A > 180°, use “-” in Equation 1. M represents the magnetic azimuth measured by the geomagnetic theodolite. D represents the magnetic declination at the installation point of the geomagnetic theodolite.

[0020] Compared with the prior art, the present invention has the following technical effects:

[0021] The gyroscopic total station used in this invention can independently determine the true north direction by sensing the Earth's rotation in all weather conditions, all day long, and without support. However, due to the instrument constant and measurement stability caused by the instrument structure, the instrument constant can be obtained by comparing it with the true north azimuth reference, thereby measuring the true north azimuth of any side. It has the following advantages:

[0022] First, the measurement time is short and the efficiency is high, and it can achieve real-time measurement of true north and magnetic north directions;

[0023] Second, it is highly mobile and can change the location of the measuring station at any time according to the on-site measurement conditions;

[0024] Third, the labor intensity and measurement cost are low. Since this method directly obtains the true north direction through gyro total station orientation, it simplifies the tedious process from point measurement to azimuth calculation, so the corresponding field labor intensity and measurement cost are significantly reduced. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 Schematic diagram for the definition of magnetic declination;

[0026] Figure 2 is a flow chart of the method of the present invention;

[0027] Figure 3 is a schematic diagram of an embodiment of the present invention.

[0028] The technical solution of the present invention is further explained below with reference to the accompanying drawings and examples. DETAILED DESCRIPTION

[0029] Example

[0030] An embodiment of the present invention is given below, which is applied to the measurement of magnetic declination of an airport runway. It should be noted that this embodiment is intended to make the implementation of the technical solution of the present invention easier to understand, and the scope of protection of the technical solution of the present invention is not limited to this embodiment.

[0031] The first step is to select the true north azimuth for gyroscopic orientation measurement and calculate the instrument constant of the gyroscopic total station Δ = -0°0′26″;

[0032] The second step is to select a measuring station O and an orientation point L on the centerline of the runway to be measured. The two points should be 400 meters apart and have a clear line of sight. The measuring station O should be surrounded by open space with no obvious external magnetic field interference. The orientation point L should be surrounded by open space with no obvious vibration interference. A geomagnetic theodolite should be set up at point O, and a gyro total station should be set up at point L.

[0033] The third step is to start the north-seeking function of the gyro total station and start the gyro north-seeking measurement;

[0034] Step 4: After the gyroscopic north-seeking measurement is completed, use the gyroscopic total station to aim at the geomagnetic theodolite installation point and measure the true azimuth A from the gyroscopic total station measurement point L to the geomagnetic theodolite measurement point O. LO =27°00′11″, the measurement results are shown in Table 1;

[0035] Table 1 Gyro total station observation results

[0036]

[0037] The fifth step is to use the geomagnetic theodolite to measure the geomagnetic azimuth M from the geomagnetic theodolite installation point O to the gyro total station installation point L. OL =211°53′57″, the measurement results are shown in Table 2;

[0038] Table 2 Geomagnetic theodolite observation results

[0039]

[0040] Step 6: Return to the true north azimuth of the first step, perform gyroscopic orientation measurement, and calculate the gyroscopic total station instrument constant Δ 返 =-0°0′30″; and compare the change values ​​of the gyro total station instrument constant for the two times. The change value is ≤2δ, where δ is the nominal accuracy of the gyro total station instrument. The instrument used this time has δ = ±5″, which meets the requirements;

[0041] Step 7: The true north azimuth A is measured by the gyro total station. LO , inversely calculate the true north azimuth angle A OL , and the magnetic azimuth M measured by the geomagnetic theodolite OL Calculate the magnetic declination D at the geomagnetic theodolite installation point according to formula 1 O .

[0042] D O =A LO +180°-M OL =27°00′11″+180°-211°53′57″=-4°53′46″;

[0043] In order to test the measurement accuracy of the technical solution of the present invention, the magnetic declination of the measuring station O is queried, and the results are shown in Table 3:

[0044] Table 3 Observation results

[0045] Roll Call Reference magnetic declination Measured magnetic declination O -4°56′ -4°53′46″

[0046] As can be seen from the table, the difference between the measured magnetic declination at measuring station O and the reference magnetic declination is less than 0.1°, which meets the magnetic declination measurement accuracy requirements of this example.

[0047] As can be seen from the above, compared with the prior art, the implementation process of the present invention is convenient and the measurement results are accurate, which has practical significance and practical value for improving the measurement efficiency of magnetic declination and reducing measurement costs.

Claims

1. A method for measuring magnetic declination by combining a gyro total station with a geomagnetic theodolite, characterized in that: The specific steps include: The first step is to select the true north azimuth to perform gyroscopic orientation measurement and calculate the instrument constant of the gyroscopic total station; The second step is to set up a gyro total station and a geomagnetic theodolite at the two ends of the survey line; The third step is to start the north-seeking function of the gyro total station and start the gyro north-seeking measurement; Step 4: After the gyroscopic north-seeking measurement is completed, the gyroscopic total station is used to sight the geomagnetic theodolite installation point, and the true north azimuth from the gyroscopic total station measurement point to the geomagnetic theodolite measurement point is measured; The fifth step is to use a geomagnetic theodolite to measure the geomagnetic azimuth from the geomagnetic theodolite installation point to the gyro total station installation point; Step 6: Return to the true north azimuth of the first step, perform gyroscopic orientation measurement, and calculate the instrument constant of the gyroscopic total station. Compare the two changes in the instrument constant of the gyroscopic total station. If the change is ≤ 2δ, the requirement is met. Otherwise, the instrument constant needs to be remeasured, where δ is the nominal accuracy of the gyroscopic total station. The seventh step is to reversely calculate the true north azimuth of the geomagnetic theodolite installation point based on the 180° difference between the positive and negative angles and the true north azimuth measured by the gyro total station, and calculate the magnetic declination at the geomagnetic theodolite installation point based on the magnetic azimuth measured by the geomagnetic theodolite.

2. The magnetic declination measurement method combining a gyro total station and a geomagnetic theodolite as claimed in claim 1, characterized in that: In the seventh step, the magnetic declination angle at the installation point of the geomagnetic theodolite is calculated as follows: D=A±180°-M (1) Where A represents the true north azimuth measured by the gyro total station. If A < 180°, use "+" in Equation 1; if A > 180°, use "-" in Equation 1. M represents the magnetic azimuth measured by the geomagnetic theodolite. D represents the magnetic declination at the geomagnetic theodolite installation point.

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