US-20260126289-A1 - AZIMUTH MEASUREMENT DEVICE

Abstract

An azimuth measurement device is provided that includes a first angular velocity sensor, a rotation mechanism, and a second angular velocity sensor. The first angular velocity sensor has a first detection axis extending in a horizontal direction and is configured to detect a first angular velocity around the first detection axis serving as a rotation center. The rotation mechanism has a rotation axis extending in a vertical direction and is configured to rotate the first detection axis of the first angular velocity sensor around the rotation axis serving as a rotation center. The second angular velocity sensor corrects a rotation angle of the first detection axis in the rotation mechanism. The second angular velocity sensor has a second detection axis extending in the vertical direction and is configured to detect a second angular velocity around the second detection axis serving as a rotation center.

Inventors

• Shinya KANEDA

Assignees

• MURATA MANUFACTURING CO., LTD.

Dates

Publication Date

20260507

Application Date

20260106

Priority Date

20230829

Claims (20)

1. 1 . An azimuth measurement device comprising: a first angular velocity sensor that has a first detection axis extending in a first direction and is configured to detect a first angular velocity around the first detection axis serving as a rotation center; a rotation mechanism that has a rotation axis that extends in a second direction orthogonal to the first direction, the rotation mechanism configured to rotate the first detection axis of the first angular velocity sensor around the rotation axis; and a second angular velocity sensor configured to correct a rotation angle of the first detection axis in the rotation mechanism, the second angular velocity sensor having a second detection axis that extends in the second direction, wherein the second angular velocity sensor is configured to detect a second angular velocity around the second detection axis serving as a rotation center.
2. 2 . The azimuth measurement device according to claim 1 , wherein the first direction is a horizontal direction and the second direction is a vertical direction.
3. 3 . The azimuth measurement device according to claim 1 , further comprising a controller including a correction section that is configured to correct the rotation angle of the first detection axis in the rotation mechanism based on the second angular velocity.
4. 4 . The azimuth measurement device according to claim 3 , wherein the controller includes a calculation section that is configured to plot the first angular velocity against the rotation angle and to calculate an azimuth by fitting the plot to a sine function.
5. 5 . The azimuth measurement device according to claim 3 , wherein the correction section is configured to correct the rotation angle after the rotation angle is obtained from the rotation mechanism.
6. 6 . The azimuth measurement device according to claim 5 , wherein the correction section is configured to add 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 obtained from the rotation mechanism.
7. 7 . The azimuth measurement device according to claim 3 , wherein the correction section is configured to correct the rotation angle before the rotation angle is obtained from the rotation mechanism.
8. 8 . The azimuth measurement device according to claim 7 , wherein the correction section is configured to set the rotation angular velocity of the rotation mechanism at a value obtained by subtracting the second angular velocity measured by the second angular velocity sensor from a preset value for normal conditions.
9. 9 . The azimuth measurement device according to claim 1 , further comprising an attitude control unit configured to control attitudes of the first angular velocity sensor, the rotation mechanism, and the second angular velocity sensor.
10. 10 . The azimuth measurement device according to claim 9 , wherein the attitude control unit is a two-axis gimbal mechanism.
11. 11 . The azimuth measurement device according to claim 9 , further comprising an attitude measurement mechanism configured to measure the attitudes of the first angular velocity sensor, the rotation mechanism, and the second angular velocity sensor, wherein the attitude control unit is configured to control the attitudes based on measurement results of the attitude measurement mechanism.
12. 12 . The azimuth measurement device according to claim 3 , wherein the controller is a micro controller unit configured to execute a program stored in electronic memory to function as the correction section.
13. 13 . The azimuth measurement device according to claim 1 , wherein the rotation mechanism includes a rotary encoder configured to measure the rotation angle of the first detection axis in the rotation mechanism.
14. 14 . The azimuth measurement device according to claim 1 , wherein each of the first angular velocity sensor and the second angular velocity sensor is a MEMS gyro sensor.
15. 15 . An azimuth measurement device comprising: a first angular velocity sensor configured to detect a first angular velocity around a first detection axis extending in a first direction; a rotation mechanism that has a rotation axis that extends in a second direction orthogonal to the first direction, the rotation mechanism configured to rotate the first angular velocity sensor around the rotation axis; and a second angular velocity sensor configured to correct a rotation angle of the first detection axis in the rotation mechanism, the second angular velocity sensor having a second detection axis that extends in the second direction, wherein the second angular velocity sensor is configured to detect a second angular velocity around the second detection axis.
16. 16 . The azimuth measurement device according to claim 15 , wherein the first direction is a horizontal direction and the second direction is a vertical direction.
17. 17 . The azimuth measurement device according to claim 15 , further comprising a controller configured to correct the rotation angle of the first detection axis in the rotation mechanism based on the second angular velocity.
18. 18 . The azimuth measurement device according to claim 17 , wherein the controller is further configured to plot the first angular velocity against the rotation angle and to calculate an azimuth by fitting the plot to a sine function.
19. 19 . The azimuth measurement device according to claim 17 , wherein the controller is configured to: correct the rotation angle after the rotation angle is obtained from the rotation mechanism, and add 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 obtained from the rotation mechanism.
20. 20 . The azimuth measurement device according to claim 17 , wherein the controller is a micro controller unit configured to execute a program stored in electronic memory to function as the correction section.

Description

CROSS REFERENCE TO RELATED APPLICATIONS This application is a continuation of PCT Application No. PCT/JP2024/024079, filed Jul. 3, 2024, which claims priority to Japanese Patent Application No. 2023-138507, filed Aug. 29, 2023, the entire contents of each of which are hereby incorporated by reference in their entireties. TECHNICAL FIELD The present disclosure relates to an azimuth measurement device. BACKGROUND Currently, there are azimuth measurement methods that use azimuth measurement devices, such as an analog magnetic method using a magnetic compass needle, a digital magnetic method using a magnetic sensor, a GPS method, and a method using a gyroscope. For example, Non-Patent Document 1 (I. P. Prikhodko, S. A. Zotov, Alexander A. Trusov, and A. M. Shkel, “What is MEMS Gyrocompassing? Comparative Analysis of Maytagging and Carouseling” Journal of Microelectromechanical Systems, Vol. 22, No. 6, pp. 1257-1266, December 2013) discloses an azimuth measurement device and an azimuth measurement method. The azimuth measurement device includes a measurement unit for detecting the angular velocity associated with the Earth's rotation. The measurement unit includes an angular velocity sensor having a detection axis extending in a horizontal plane, and the angular velocity sensor is rotated around a vertical axis on a rotation mechanism. Measurement results are then plotted in a graph of which the horizontal axis represents the rotation angle of the detection axis of the angular velocity sensor and the vertical axis represents measured angular velocity. A resulted waveform of the plot is fitted to a sine function to calculate the azimuth. However, in the azimuth measurement device described in Non-Patent Document 1, if the azimuth measurement device happens to rotate around the vertical axis during the azimuth measurement, the rotation angle of the detection axis of the angular velocity sensor may deviate relative to the reference value, resulting in inaccurate calculation of the azimuth. SUMMARY OF THE INVENTION In view of the foregoing, it is an object of the present disclosure to provide an azimuth measurement device that improves the accuracy of azimuth measurement. According to an exemplary aspect of the present disclosure, an azimuth measurement device includes a first angular velocity sensor, a rotation mechanism, and a second angular velocity sensor. The first angular velocity sensor has a first detection axis extending in a horizontal direction and is configured to detect a first angular velocity around the first detection axis serving as a rotation center. The rotation mechanism has a rotation axis extending in a vertical direction and is configured to rotate the first detection axis of the first angular velocity sensor around the rotation axis serving as a rotation center. Moreover, the second angular velocity sensor is used to correct a rotation angle of the first detection axis in the rotation mechanism. The second angular velocity sensor has a second detection axis extending in the vertical direction and is configured to detect a second angular velocity around the second detection axis serving as a rotation center. Accordingly, the exemplary aspects of the present disclosure provide the azimuth measurement device with improved accuracy of azimuth measurement. BRIEF DESCRIPTION OF DRAWINGS FIG. 1 is a schematic diagram illustrating a configuration of an azimuth measurement device according to a first exemplary embodiment. FIG. 2 is a plan view illustrating a measurement unit. FIG. 3 is a diagram illustrating an example of a physical configuration of a control unit. FIG. 4 is a plan view illustrating the measurement unit that is rotated around a vertical axis. FIG. 5 is a graph of a first angular velocity with respect to a rotation angle before correction. FIG. 6 is a graph of the first angular velocity with respect to a rotation angle after correction. FIG. 7 is a schematic diagram illustrating a configuration of an azimuth measurement device according to a second exemplary embodiment. DETAILED DESCRIPTION OF EMBODIMENTS Exemplary embodiments of the present disclosure will be described. In the description of drawings, the same or similar elements are denoted by the same or similar reference signs. The drawings are illustrative, and the dimensions and shapes of elements are schematic. It is noted that the technical scope of the present disclosure should not be interpreted as being limited to the embodiment. An orthogonal coordinate system formed of an X-axis, a Y-axis, and a Z-axis may be indicated in the drawings for convenience in order to clarify the mutual relationship among the drawings and to help understand the positional relationship of each element. The X-axis, the Y-axis, and the Z-axis correspond to each other among the drawings. According to the present disclosure, the direction parallel to the X-axis is referred to as the “X-axis direction”, and the direction parallel to the Y-axis is refe