Azimuth measurement device

Abstract

An azimuth measurement device (1) comprises a first angular velocity sensor (11) that has a first detection axis (11D) extending along the horizontal direction and detects a first angular velocity with the first detection axis (11D) as the center of rotation, a rotation mechanism (13) that has a rotation axis (13R) extending along the vertical direction and rotates the first detection axis (11D) of the first angular velocity sensor (11) with a rotation axis (13R) as the center of rotation, and a second angular velocity sensor (12) that is used to correct the rotation angle (alpha) of the first detection axis (11D) in the rotation mechanism (13), the second angular velocity sensor (12) having a second detection axis (12D) extending along the vertical direction and detecting a second angular velocity having the second detection axis (12D) as the center of rotation.

Description

Compass measurement device

[0001] The present invention relates to a direction measuring device.

[0002] As a direction measurement device, various direction measurement methods are known, such as an analog magnetic method using a compass needle, a digital magnetic method using a magnetic sensor, a GPS method, and a gyroscope method.

[0003] For example, Non-Patent Document 1 discloses an orientation measurement device and an orientation measurement method that include a measurement unit in which an angular velocity sensor having a detection axis in a horizontal plane rotates around a vertical axis on a rotation mechanism to detect angular velocity associated with the rotation of the Earth, and that calculates orientation by plotting the rotation angle of the detection axis of the angular velocity sensor on the horizontal axis of a graph and the measurement results of the angular velocity on the vertical axis and performing sine function fitting on the plotted waveform.

[0004] IP Prikhodko, SA Zotov, Alexander A. Trusov and AM Shkel, "What is MEMS Gyrocompassing? Comparative Analysis of Maytagging and Carouseling" Journal of Microelectromechanical Systems, Vol. 22, No. 6, pp. 1257-1266, December 2013.

[0005] However, in the direction measurement device described in Non-Patent Document 1, if the direction measurement device rotates around the vertical axis while measuring the direction, the rotation angle of the detection axis of the angular velocity sensor may deviate from the reference value, making it impossible to accurately calculate the direction.

[0006] The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a direction measurement device that can improve the direction measurement accuracy.

[0007] An orientation measuring device according to one aspect of the present invention includes a first angular velocity sensor having a first detection axis extending along a horizontal direction and detecting a first angular velocity around the first detection axis as a rotation center; a rotation mechanism having a rotation axis extending along a vertical direction and rotating the first detection axis of the first angular velocity sensor around the rotation axis as a rotation center; and a second angular velocity sensor used to correct the rotation angle of the first detection axis in the rotation mechanism, the second angular velocity sensor having a second detection axis extending along the vertical direction and detecting a second angular velocity around the second detection axis as a rotation center.

[0008] According to the present invention, it is possible to provide a direction measurement device that can improve the direction measurement accuracy.

[0009] FIG. 1 is a schematic diagram showing the configuration of an azimuth measuring device according to a first embodiment; FIG. 2 is a plan view showing a measurement unit; FIG. 3 is a diagram showing an example of the physical configuration of a control unit; FIG. 4 is a plan view showing a measurement unit rotated around a vertical axis; FIG. 5 is a graph showing a first angular velocity with respect to a rotation angle before correction; and FIG. 6 is a graph showing a first angular velocity with respect to a rotation angle after correction. FIG. 7 is a schematic diagram showing the configuration of an azimuth measuring device according to a second embodiment;

[0010]

[0023] The following describes embodiments of the present invention. In the following description of the drawings, the same or similar components are denoted by the same or similar reference numerals. The drawings are illustrative, and the dimensions and shapes of each part are schematic. The technical scope of the present invention should not be interpreted as being limited to the embodiments.

[0011] For the sake of clarity, each drawing may be accompanied by a Cartesian coordinate system consisting of an X-axis, a Y-axis, and a Z-axis to clarify the interrelationships between the drawings and to aid in understanding the positional relationships of each component. The X-axis, Y-axis, and Z-axis correspond to each other in each drawing. The direction parallel to the X-axis is referred to as the "X-axis direction," the direction parallel to the Y-axis is referred to as the "Y-axis direction," and the direction parallel to the Z-axis is referred to as the "Z-axis direction." The directions of the arrows on the X-axis, Y-axis, and Z-axis are referred to as "positive" or "+ (plus)," and the directions opposite the arrows are referred to as "negative" or "- (minus)." The plane defined by the X-axis and Y-axis is referred to as the "XY plane," as are the planes defined by the other axes. The Z-axis direction is an example of the "vertical direction," and the direction along the XY plane is an example of the "horizontal direction."

[0012] First Embodiment

[0013] First, the configuration of an azimuth measuring device 1 according to one embodiment of the present invention will be described with reference to Figures 1 and 2. Figure 1 is a schematic diagram showing the configuration of the azimuth measuring device according to the first embodiment. Figure 2 is a plan view showing a measurement unit.

[0014] The azimuth measurement device 1 measures the azimuth by measuring the angular velocity of the Earth's rotation. The azimuth measurement device 1 is, for example, a north-finding device that finds true north. The azimuth measurement device 1 includes a measurement unit 10 and a control unit 20.

[0015] The measurement unit 10 measures the rotational angular velocity of the Earth. As shown in FIG. 1 , the measurement unit 10 includes a first angular velocity sensor 11, a second angular velocity sensor 12, a rotation mechanism 13, and a sensor housing 19.

[0016] The first angular velocity sensor 11 has a first detection axis 11D extending along the horizontal direction (XY plane) and detects a first angular velocity around the first detection axis 11D as the center of rotation. The first angular velocity sensor 11 is, for example, a MEMS (Micro Electro Mechanical Systems) gyro sensor, but is not limited to this as long as it can detect angular velocity. The first angular velocity when the measurement unit 10 is stationary corresponds to the component of the horizontal component of the angular velocity of the Earth's rotation at the latitude of the measurement point, the component having the first detection axis 11D as the center of rotation. In other words, the magnitude of the first angular velocity changes based on the azimuth angle of the first detection axis 11D. Specifically, the Earth's rotation angular velocity is expressed as Ω Ｅ When the latitude of the measurement point is φ, the angle between the true north direction in the horizontal plane at the measurement point and the earth's axis is φ, so the horizontal component of the rotational angular velocity around the true north direction in the horizontal plane at the measurement point is ω ｈ is ω ｈ =Ω Ｅ When the angle between the true north direction in the horizontal plane and the first detection axis 11D is defined as the azimuth angle θ of the first detection axis 11D, the first angular velocity ω resulting from the rotation about the first detection axis 11D is expressed as ω=ω ｈ ×cosθ=Ω Ｅ × cosφ × cosθ. From the above equation, ΩＥ is constant (Ω Ｅ = 15.041 [dph]), the angular velocity ω is determined by the latitude φ and the azimuth angle θ of the first detection axis 11D. If the positive direction of the first angular velocity is defined as clockwise when viewing the first detection axis 11D from the first angular velocity sensor 11, under the condition that the azimuth angle θ of the first detection axis 11D is constant, the first angular velocity ω is maximum when the measurement position is on the equator (φ = 0). The closer the measurement position is to due north or due south, i.e., the larger φ becomes, the smaller the first angular velocity ω becomes. Furthermore, under the condition that the latitude φ is constant, the first angular velocity ω is maximum when the first detection axis 11D faces due north, i.e., when θ = 0. The first angular velocity ω is minimum when the first detection axis 11D faces due south, i.e., when θ = 180. When the first detection axis 11D faces due west or due east, that is, when θ=90° or 270°, the first angular velocity ω becomes zero. Ｅ × cosφ = k (constant), the first angular velocity ω is Ｅ ×cosφ×cos θ=k×sin(90−θ) That is, the first angular velocity ω can be expressed by a sine function with the azimuth angle θ of the first detection axis 11D as a variable.

[0017] The rotation mechanism 13 has a rotation axis 13R extending along the vertical direction (Z-axis), and rotates the first detection axis 11D of the first angular velocity sensor 11 around the rotation axis 13R. The angle that the first detection axis 11D rotated by the rotation mechanism 13 makes with the reference direction RD in the XY plane is defined as the rotation angle α of the first detection axis 11D. For example, the rotation mechanism 13 is a rotary table, and the first angular velocity sensor 11 is fixed on the table surface of the rotation mechanism 13.

[0018] The rotation angle α is measured by a rotary encoder 13 A. The rotary encoder 13 A is provided in the rotation mechanism 13, for example, but may also be provided outside the rotation mechanism 13.

[0019] The second angular velocity sensor 12 is used to correct the rotation angle α of the first detection axis 11D in the rotation mechanism 13. When the measurement unit 10 rotates around the vertical axis due to an external impact or the like, the first angular velocity sensor 11 rotates together with the rotation mechanism 13 and the rotary encoder 13A. As a result, the rotation angle of the first detection axis 11D deviates from the rotation angle α measured by the rotary encoder 13A. In this case, the second angular velocity sensor 12 is used to correct the rotation angle α, which is the measurement value of the rotary encoder 13A, to obtain the true rotation angle.

[0020] The second angular velocity sensor 12, like the first angular velocity sensor 11, is, for example, a MEMS gyro sensor, but is not limited thereto. The second angular velocity sensor 12 has a second detection axis 12D extending along the vertical direction (Z-axis) and detects a second angular velocity around the second detection axis 12D as the center of rotation. The second angular velocity is the angular velocity when the measurement unit 10 rotates around the vertical axis due to an external impact or the like. The angular deviation of the orientation of the measurement unit 10 from the reference direction RD can be calculated based on the rotation angle calculated by integrating the measurement value of the second angular velocity measured by the second angular velocity sensor 12. This makes it possible to correct the rotation angle α based on the second angular velocity.

[0021] The second angular velocity sensor 12 is provided at a distance from the rotation mechanism 13. In this case, the second angular velocity sensor 12 detects only the angular velocity of the measurement unit 10 around the vertical axis. However, the second angular velocity sensor may be provided in the rotation mechanism, like the first angular velocity sensor. In this case, the second angular velocity sensor detects a combined angular velocity of the angular velocity of the rotation mechanism and the angular velocity of the measurement unit around the vertical axis. Therefore, the angular velocity of the measurement unit is calculated, for example, by subtracting the angular velocity detected when the measurement unit is stationary from the detection result of the second angular velocity sensor. Alternatively, the angular velocity of the measurement unit may be calculated by subtracting the set angular velocity of the rotation mechanism from the detection result of the second angular velocity sensor.

[0022] The sensor housing 19 houses the first angular velocity sensor 11, the second angular velocity sensor 12, and the rotation mechanism 13. Although not shown, the sensor housing 19 may include a communication module that enables the first angular velocity sensor 11, the second angular velocity sensor 12, and the rotation mechanism 13 to communicate with the control unit 20.

[0023] The control unit 20 controls the measurement unit 10 and measures the direction based on the measurement results of the measurement unit 10. As shown in Fig. 1 , the control unit 20 is communicably connected to the measurement unit 10. The control unit 20 includes a drive unit 21, an acquisition unit 22, a calculation unit 23, and a correction unit 24.

[0024] The drive unit 21 drives the rotation mechanism 13. The acquisition unit 22 acquires the first angular velocity from the first angular velocity sensor 11, acquires the second angular velocity from the second angular velocity sensor 12, and acquires the rotation angle α from the rotary encoder 13A. The calculation unit 23 calculates the orientation by plotting the first angular velocity against the rotation angle α and fitting this plot with a sine function. Because the first angular velocity is maximum when the first detection axis 11D faces due north, the calculation unit 23 may calculate due north from the rotation angle α at which the first angular velocity is maximum, without fitting with a sine function.

[0025] The correction unit 24 corrects the rotation angle α of the first detection axis 11D of the rotation mechanism 13 based on the second angular velocity. For example, the correction unit 24 corrects the rotation angle α after it has been acquired from the rotation mechanism 13 and changes the plot position in the calculation unit 23. However, the correction method of the correction unit 24 is not limited to the above, and the correction unit 24 may correct the rotation angle α before it has been acquired from the rotation mechanism 13. For example, the correction unit 24 may use a value obtained by subtracting the second angular velocity from a normal setting value as the rotation angular velocity of the rotation mechanism 13. Furthermore, the correction unit 24 may drive the rotation mechanism 13 via the drive unit 21 and rotate the rotation mechanism 13 so that the orientation of the rotation mechanism 13 matches the true rotation angle. Furthermore, the correction unit 24 may calibrate the rotary encoder 13A so that the value measured by the rotary encoder 13A matches the true rotation angle.

[0026] Next, the physical configuration of the control unit 20 will be described with reference to Fig. 3. Fig. 3 is a diagram showing an example of the physical configuration of the control unit.

[0027] The control unit 20 includes a CPU (Central Processing Unit) 95, a RAM (Random Access Memory) 96, a ROM (Read Only Memory) 97, and a communication module 98. These components are connected to each other via a bus so as to be able to transmit and receive data. The CPU 95, RAM 96, ROM 97, and communication module 98 are also connected to an operation unit 92 and a display unit 94 via the bus so as to be able to transmit and receive data. The control unit 20 is, for example, a Micro Controller Unit (MCU), but may be configured by a single computer or may be realized by combining multiple distributed computers. The control unit 20 can function the drive unit 21, acquisition unit 22, calculation unit 23, and correction unit 24 by, for example, executing a predetermined program stored in the RAM 96 or ROM 97 by the CPU 95.

[0028] Next, the mechanism of correction will be described in more detail with reference to FIGS. 4 to 6. FIG. 4 is a plan view showing the measurement unit rotated around the vertical axis. FIG. 5 is a graph showing the first angular velocity versus the rotation angle before correction. FIG. 6 is a graph showing the first angular velocity versus the rotation angle after correction. In the graph shown in FIG. 5, the horizontal axis represents the rotation angle of the first detection axis 11D before correction, and the vertical axis represents the first angular velocity. In the graph shown in FIG. 6, the horizontal axis represents the rotation angle of the first detection axis 11D after correction, and the vertical axis represents the first angular velocity.

[0029] First, the rotation mechanism 13 is driven to rotate the first detection axis 11D of the first angular velocity sensor 11 from the reference direction RD. At the same time, the first angular velocity sensor 11 is operated to detect the first angular velocity at a rotation angle α at a predetermined interval.

[0030] As shown in FIG. 4 , assume that at a certain time Tm, the measurement unit 10 rotates by an angle β in the same direction as the rotation direction of the rotation mechanism 13. At this time, if the initial reference direction before the original rotation is RD0, the reference direction RD of the rotation mechanism 13 rotates by an angle β from the initial reference direction RD0. Therefore, the true rotation angle of the first detection axis 11D of the first angular velocity sensor 11 from the initial reference direction RD0 is α + β. Therefore, when the rotary encoder 13A measures the rotation angle as α, the first angular velocity sensor 11 detects the first angular velocity at the true rotation angle α + β. Therefore, as shown in FIG. 5 , the first angular velocity changes discontinuously at the time Tm when the measurement unit 10 rotates. Such discontinuous changes in the first angular velocity result in an error when fitting a plot of the first angular velocity with a sine function.

[0031] Therefore, when the second angular velocity sensor 12 detects the second angular velocity, the correction unit 24 calculates the angle β based on the second angular velocity. As shown in FIG. 6 , the correction unit 24 adds the rotation angle β to the rotation angle α measured by the rotary encoder 13A after timing Tm. Although the plot of the first angular velocity is interrupted at timing Tm, deviation of the plot from a sine function can be suppressed. In other words, errors that occur when fitting with a sine function can be suppressed. Therefore, compared to measuring the orientation based on the graph shown in FIG. 5 , measuring the orientation based on the graph shown in FIG. 6 improves the orientation measurement accuracy. The azimuth angle calculated by fitting the corrected graph shown in FIG. 6 is the azimuth angle assuming that the measurement unit 10 has not rotated, i.e., the angle relative to the initial reference direction RD0. Therefore, to calculate the azimuth angle of the measurement unit 10 after rotation by angle β, the rotation angle β of the measurement unit 10 needs to be added to the azimuth angle calculated by fitting the corrected graph shown in FIG. 6 . For example, if the azimuth angle of true north calculated by fitting the corrected graph is α = 30 degrees and the rotation angle of the measurement unit 10 calculated by integrating the measurement value of the second angular velocity is β = 10 degrees, the azimuth angle of true north in the measurement unit 10 is α + β = 40 degrees.

[0032] As described above, according to this embodiment, the azimuth measuring device 1 includes the first angular velocity sensor 11 having the first detection axis 11D extending in the horizontal direction, the rotation mechanism 13 that rotates the first detection axis 11D around the rotation axis 13R that extends in the vertical direction, and the second angular velocity sensor 12 that is used to correct the rotation angle α of the first detection axis 11D in the rotation mechanism 13, the second angular velocity sensor having the second detection axis 12D that extends along the vertical direction and that detects a second angular velocity around the second detection axis 12D as the rotation center.

[0033] According to this, even if the measurement unit 10 rotates around the vertical axis during azimuth measurement, the error in the rotation angle α caused by the rotation of the measurement unit 10 can be corrected based on the second angular velocity, thereby suppressing the occurrence of azimuth measurement errors.

[0034] Other embodiments will be described below. Note that components that are the same as or similar to those in the first embodiment are denoted by the same or similar reference numerals, and descriptions thereof will be omitted as appropriate. Furthermore, similar effects resulting from similar components will not be mentioned one after another.

[0035] Second Embodiment The configuration of a direction measuring device 2 according to a second embodiment will be described with reference to Fig. 7. Fig. 7 is a schematic diagram showing the configuration of the direction measuring device according to the second embodiment.

[0036] The direction measuring device 2 further includes an attitude control unit 230. The measurement unit 210 of the direction measuring device 2 further includes an attitude measurement mechanism 214. The control unit 220 of the direction measuring device 2 further includes an attitude information acquisition section 225 and an attitude control section 226.

[0037] The attitude control unit 230 corrects rotation around a rotation axis extending along the horizontal direction (XY plane) in the measurement unit 210, and controls the attitudes of the first angular velocity sensor 11, the second angular velocity sensor 12, and the rotation mechanism 13. The attitude control unit 230 includes a two-axis gimbal mechanism 231 and a servo motor 232 that operates the two-axis gimbal mechanism 231.

[0038] The attitude measurement mechanism 214 measures rotation around a rotation axis extending along the XY plane of the measurement unit 210. That is, the attitude measurement mechanism 214 measures the attitudes of the first angular velocity sensor 11, the second angular velocity sensor 12, and the rotation mechanism 13. The attitude measurement mechanism 214 is, for example, an inertial measurement unit (IMU). The attitude information acquisition unit 225 acquires information about the attitude of the measurement unit 210 from the attitude measurement mechanism 214. The attitude control unit 226 servo-controls the two-axis gimbal mechanism 231 via a servo motor 232 based on the information about the attitude of the measurement unit 210 acquired by the attitude information acquisition unit 225.

[0039] According to this embodiment, the orientation measurement device 2 is equipped with the attitude control unit 230, which makes it possible to suppress the occurrence of orientation measurement errors caused by rotation around a rotation axis extending along the horizontal direction in the measurement unit 210, thereby improving orientation measurement accuracy.

[0040] Furthermore, as one aspect of this embodiment, the attitude control unit 230 controls the attitude based on the measurement results of the attitude measurement mechanism 214, so that the horizontal attitude of the measurement unit 210 can be maintained with high precision.

[0041] In this embodiment, the attitude control unit 230 controls the attitude of the measurement unit 210 by servo control based on the measurement results of the attitude measurement mechanism 214, but this is not limiting. The azimuth measurement device may control the attitude of the measurement unit by constantly operating the two-axis gimbal mechanism at a constant output, without measuring the attitude of the attitude control unit.

[0042] Furthermore, the attitude control mechanism is not limited to a two-axis gimbal mechanism. For example, the attitude control mechanism may be two or more support columns with lifting functions connected to the bottom surface of the measurement unit. The attitude control mechanism may also be a passive attitude control mechanism having an air spring, a spring, an oil damper, an air damper, urethane rubber, or the like.

[0043] Some or all of the embodiments of the present invention will be described below, but the present invention is not limited to the following descriptions.

[0044] <1> A azimuth measurement device comprising: a first angular velocity sensor having a first detection axis extending along a horizontal direction and detecting a first angular velocity around the first detection axis as a rotation center; a rotation mechanism having a rotation axis extending along a vertical direction and rotating the first detection axis of the first angular velocity sensor around the rotation axis as a rotation center; and a second angular velocity sensor used to correct the rotation angle of the first detection axis in the rotation mechanism, the second angular velocity sensor having a second detection axis extending along the vertical direction and detecting a second angular velocity around the second detection axis as a rotation center.

[0045] <2> The azimuth measurement device according to <1>, further comprising a correction unit that corrects the rotation angle of the first detection axis in the rotation mechanism based on the second angular velocity.

[0046] <3> The orientation measuring device according to <2>, further comprising a calculation unit that calculates the orientation by plotting the first angular velocity against the rotation angle and fitting the plot with a sine function.

[0047] <4> The azimuth measurement device according to <2> or <3>, wherein the correction unit corrects the rotation angle after it is acquired from the rotation mechanism.

[0048] <5> The azimuth measuring device according to <4>, wherein the correction unit adds a rotation angle calculated based on the second angular velocity measured by the second angular velocity sensor to the rotation angle of the first detection axis acquired from the rotation mechanism.

[0049] <6> The azimuth measurement device according to <2> or <3>, wherein the correction unit corrects the rotation angle before it is acquired from the rotation mechanism.

[0050] <7> The azimuth measurement device according to <6>, wherein the correction unit sets a value obtained by subtracting the second angular velocity measured by the second angular velocity sensor from a setting value in normal times as the rotational angular velocity of the rotation mechanism.

[0051] <8> The direction measuring device according to any one of <1> to <7>, further comprising an attitude control unit that controls the attitudes of the first angular velocity sensor, the rotation mechanism, and the second angular velocity sensor.

[0052] <9> The orientation measuring device according to <8>, wherein the attitude control unit is a two-axis gimbal mechanism.

[0053] <10> The azimuth measuring device according to <8> or <9>, further comprising an attitude measurement mechanism that measures the attitudes of the first angular velocity sensor, the rotation mechanism, and the second angular velocity sensor, and the attitude control unit performs attitude control based on the measurement results of the attitude measurement mechanism.

[0054] As described above, according to one aspect of the present invention, it is possible to provide a direction measurement device that can improve the direction measurement accuracy.

[0055] The above-described embodiments are intended to facilitate understanding of the present invention and are not intended to limit the scope of the present invention. The present invention may be modified or improved without departing from its spirit, and equivalents are also included within the scope of the present invention. In other words, designs modified by those skilled in the art as appropriate to the embodiments and / or modifications are also encompassed within the scope of the present invention as long as they incorporate the characteristics of the present invention. For example, the elements and their arrangements, materials, conditions, shapes, sizes, etc. of the embodiments and / or modifications are not limited to those illustrated and can be modified as appropriate. Furthermore, the embodiments and modifications are merely examples, and it goes without saying that partial substitutions or combinations of the components shown in different embodiments and / or modifications are possible. These are also encompassed within the scope of the present invention as long as they incorporate the characteristics of the present invention.

[0056] REFERENCE SIGNS LIST 1... Orientation measurement device 10... Measurement unit 11... First angular velocity sensor 11D... First detection axis 12... Second angular velocity sensor 12D... Second detection axis 13... Rotation mechanism 13R... Rotation axis 13A... Rotary encoder RD... Reference direction α... Rotation angle 20... Control unit 21... Drive unit 22... Acquisition unit 23... Calculation unit 24... Correction unit 214... Attitude measurement mechanism 230... Attitude control unit 231... Two-axis gimbal mechanism 232... Servo motor 225... Attitude information acquisition unit 226... Attitude control unit

Claims

1. A first angular velocity sensor having a first detection axis extending along the horizontal direction, which detects a first angular velocity with the first detection axis as the center of rotation, A rotation mechanism having a rotation axis extending in the vertical direction, which rotates the first detection axis of the first angular velocity sensor with the rotation axis as the center of rotation, A second angular velocity sensor used to correct the rotation angle of the first detection axis in the aforementioned rotation mechanism, the second angular velocity sensor having a second detection axis extending along the vertical direction, and detecting a second angular velocity with the second detection axis as the center of rotation. Equipped with, Direction-measuring device.

2. The mechanism further includes a correction unit that corrects the rotation angle of the first detection shaft in the rotation mechanism based on the second angular velocity. The compass measuring device according to claim 1.

3. The system further includes a calculation unit that plots the first angular velocity against the rotation angle and calculates the direction by fitting the plot with a sine function. The compass measuring device according to claim 2.

4. The correction unit corrects the rotation angle obtained from the rotation mechanism. The compass measuring device according to claim 2.

5. The correction unit adds to the rotation angle of the first detection shaft obtained from the rotation mechanism the rotation angle calculated based on the second angular velocity measured by the second angular velocity sensor. The compass measuring device according to claim 4.

6. The correction unit corrects the rotation angle before it is obtained from the rotation mechanism. The compass measuring device according to claim 2.

7. The correction unit subtracts the second angular velocity measured by the second angular velocity sensor from the normal set value to obtain the rotational angular velocity of the rotation mechanism. The compass measuring device according to claim 6.

8. The system further comprises an attitude control unit for controlling the attitude of the first angular velocity sensor, the rotation mechanism, and the second angular velocity sensor. The compass measuring device according to any one of claims 1 to 7.

9. The attitude control unit is a two-axis gimbal mechanism. The compass measuring device according to claim 8.

10. The system further comprises an attitude measuring mechanism for measuring the attitude of the first angular velocity sensor, the rotation mechanism, and the second angular velocity sensor, The attitude control unit performs attitude control based on the measurement results of the attitude measurement mechanism. The compass measuring device according to claim 8.