Azimuth detection method, azimuth detection device, and surveying device

Abstract

To provide a compact and easy-to-use azimuth detection method, azimuth detection device, and surveying device. [Solution] The system includes a sensor unit 7 that detects tilt and rotation relative to the horizontal, and a flywheel 18 provided on the sensor unit that has a rotation axis extending in the vertical direction. The flywheel is rotated at a constant speed, and the flywheel is tilted to generate a gyroscopic moment in order to counteract the change in tilt that occurs in accordance with the rotation of the Earth, and the direction of the Earth's axis (north or south) can be determined from the direction of the gyroscopic moment.

Description

Technical Field

[0001] The present disclosure relates to an azimuth detection method using gyro moment, an azimuth detection device, and a surveying device.

Background Art

[0002] In surveying work, it is necessary to measure the vertical angle and horizontal angle of the surveying device body based on a predetermined measurement point. For the measurement of the vertical angle, an inclination sensor for detecting the horizontal state of the surveying device body and a vertical angle detector are used. On the other hand, the measured horizontal angle is a horizontal angle with a predetermined measurement point of the surveying device body as the reference direction and is temporary. Therefore, to indicate the position on the ground, the horizontal angle must be converted into an azimuth.

[0003] As a measuring instrument for detecting azimuth, a magnetic compass or a geocentric azimuth detector is used.

[0004] The accuracy of a magnetic compass is several degrees, the accuracy is poor, and it is easily affected by the surrounding (metal) situation, so it is not suitable for high-precision measurement.

[0005] Also, for high-precision measurement, a geocentric azimuth detector is used. The geocentric azimuth detector is an azimuth detector using gyro moment, which greatly captures the gravity change due to the rotation of the earth as gyro moment, and the device is large and heavy.

[0006] Furthermore, as a geocentric azimuth detector, there are some that use a gyrocompass, a ring laser gyro, etc., but these are expensive and large.

Prior Art Documents

Patent Documents

[0007]

Patent Document 1

Patent Document 2

Patent Document 3

[0008] This disclosure provides a compact and easy-to-use azimuth detection method, azimuth detection device, and surveying device. [Means for solving the problem]

[0009] This disclosure relates to an azimuth detection method comprising a sensor unit for detecting tilt and rotation relative to the horizontal, and a flywheel provided on the sensor unit having a rotation axis extending in the vertical direction, wherein the flywheel is rotated at a constant speed and tilted to generate a gyroscopic moment in order to counteract the change in tilt that occurs in accordance with the rotation of the Earth, and the north or south of the Earth's axis is determined from the direction of the gyroscopic moment.

[0010] The present disclosure also relates to an azimuth detection device comprising: an inner frame provided inside an outer frame; a sensor unit for detecting tilt and rotation relative to the horizontal, the inner frame being rotatably supported by the outer frame via a first axis; the sensor unit being rotatably supported by the inner frame via a second axis orthogonal to the first axis; first and second rotational powers provided on each axis to rotate each axis, respectively; a calculation processing unit that drives and controls each rotational power based on the detection results from the sensor unit; a flywheel provided on the sensor unit; and a rotational power for rotating the flywheel at a constant speed, wherein the calculation processing unit generates a gyroscopic moment by controlling the tilt of the sensor unit with the first and second rotational powers to counteract changes in the tilt of the sensor unit, and determines the north or south of the Earth's axis from the direction of the gyroscopic moment.

[0011] Furthermore, this disclosure relates to a surveying device comprising the above-mentioned azimuth angle detection device, a distance measuring unit, an optical axis deflection unit, a measurement direction detection unit, and a calculation control unit, wherein the calculation control unit is configured to acquire the three-dimensional coordinates of a measurement target with respect to true north based on the distance measuring result of the distance measuring unit, the detection result of the measurement direction detection unit, and the detection result of the azimuth angle detection device. [Effects of the Invention]

[0012] According to this disclosure, a compact and easy-to-use device can detect the azimuth angle. [Brief explanation of the drawing]

[0013] [Figure 1] This is a plan view of the azimuth angle detection device according to this embodiment. [Figure 2] This is a side cross-sectional view taken along arrow AA in Figure 1. [Figure 3] This is a schematic diagram of this embodiment. [Figure 4] This is a schematic diagram of the sensor used in this embodiment. [Figure 5] This is an explanatory diagram showing the relationship between the sensor, the Earth's rotation, and the gyroscopic moment. [Figure 6] This is a schematic diagram of the surveying device according to this embodiment. [Modes for carrying out the invention]

[0014] The embodiments of this disclosure will be described below with reference to the drawings.

[0015] Figures 1, 2, and 3 show the azimuth detection device 1 according to this embodiment. Figure 1 is a schematic plan view, Figure 2 is a side cross-sectional view taken along the arrow AA in Figure 1, and Figure 3 is a schematic configuration diagram of the azimuth detection device 1. In the following description, the upper side of Figure 1 will be referred to as the rear, the lower side as the front, the right side as the right, and the left side as the left. In Figure 2, the upper side will be referred to as the top, the lower side as the bottom, the right side as the right, and the left side as the left. Furthermore, when the azimuth detection device 1 is installed on a surveying device, it is installed so that the reference axis (Y-axis in the figures) set on the azimuth detection device 1 is in the direction of the reference axis (for example, the sighting axis) of the surveying device.

[0016] Of course, the azimuth detection device 1 is not limited to a surveying device and can be applied to any device that detects azimuth. In the following description, the device on which the azimuth detection device 1 is provided is referred to as the main body.

[0017] The azimuth detection device 1 according to this embodiment includes a gyro mechanism 3 and a sensor 2 supported by the gyro mechanism 3.

[0018] In this embodiment, an example is shown in which an integrated MEMS sensor incorporating a three-axis acceleration sensor and a gyro sensor is used as the sensor 2.

[0019] First, the gyro mechanism 3 will be described.

[0020] An inner frame 6 having a rectangular frame shape is provided inside an outer frame 5 having a rectangular frame shape, and a sensor unit 7 is provided inside the inner frame 6. The sensor unit 7 includes a rotating part 10 of the gyro mechanism and the sensor 2, and the sensor 2 and the rotating part 10 are integrated.

[0021] The sensor 2 is an integrated MEMS sensor incorporating a three-axis acceleration sensor and a gyro sensor, and the signal output from the sensor 2 includes a detection signal from the three-axis acceleration sensor and a detection signal from the gyro sensor. [[ID=2�]]

[0022] When the azimuth detection device 1 is provided in a device that requires an azimuth, such as a surveying device (not shown), the outer frame 5 is attached to a structural member of the surveying device main body.

[0023] A first shaft 8 protrudes from the rear side of the inner frame 6, and a first encoder 11 is provided on the first shaft 8. The first shaft 8 is rotatably supported by the outer frame 5 via a bearing 9 provided on the outer frame 5, and the inner frame 6 is rotatable with respect to the outer frame 5.

[0024] A first rotational drive force (hereinafter referred to as the first motor 12) is provided on the front side of the outer frame 5.

[0025] The first motor 12 is an outer rotor type motor, and its inner portion 12a is fixed to the outer frame 5, so that the outer portion 12b of the first motor 12 and the first shaft 8 rotate together, and the outer frame 5 and the inner frame 6 rotate relative to each other when driven by the first motor 12.

[0026] The first encoder 11 has detection units 11a and 11b at two locations on the left and right sides in the figure, and is configured to detect the rotation angle of the inner frame 6 with respect to the outer frame 5 (the relative rotation angle between the inner frame 6 and the outer frame 5).

[0027] A second shaft 13 protrudes from the right side of the sensor unit 7, and a second encoder 14 is provided on the second shaft 13. The second shaft 13 is rotatably supported by the inner frame 6 via a bearing 15 provided on the inner frame 6, and the sensor unit 7 is rotatable around the second shaft 13.

[0028] Here, the axis of the first axis 8 and the axis of the second axis 13 are configured to be orthogonal, with the axis of the first axis 8 being the X-axis and the axis of the second axis 13 being the Y-axis. Furthermore, the axis orthogonal to the plane containing the X-axis and Y-axis is defined as the Z-axis. In the figure, the Z-axis is set to pass through the intersection of the X-axis and Y-axis. The rotating part 10 of the gyro mechanism is positioned along the Z-axis. In the figure, the Y-axis or the direction of the Y-axis is set as the reference direction of the azimuth detection device 1.

[0029] A second rotational drive force (hereinafter referred to as the second motor 16) is provided on the left side of the inner frame 6, and the rotation axis of the second motor 16 is fixed to the left side of the sensor unit 7.

[0030] The second motor 16 is an outer rotor type motor, and its inner portion 16a is fixed to the inner frame 6, so that the outer portion 16b of the second motor 16 and the second shaft 13 rotate together, and the inner frame 6 and the sensor unit 7 rotate relative to each other when driven by the second motor 16.

[0031] The second encoder 14 has detection units 14a and 14b at two locations, front and rear, in the figure, and is configured to detect the rotation angle of the sensor unit 7 with respect to the inner frame 6 (the relative rotation angle between the sensor unit 7 and the inner frame 6).

[0032] Furthermore, the first encoder 11 and the second encoder 14 may be encoders (angle measurement accuracy: 10″ or less) that are commonly used for angle measurement in surveying equipment.

[0033] Furthermore, the motors used as the first and second rotational driving forces may be of a type in which the rotating shaft rotates relative to the motor body, and should generate relative rotation between the outer frame 5 and the inner frame 6, and between the inner frame 6 and the sensor unit 7.

[0034] The first encoder 11 and the second encoder 14 are electrically connected to the arithmetic processing unit 19, and the first encoder 11 and the second encoder 14 output detection results to the arithmetic processing unit 19.

[0035] The sensor 2 is electrically connected to the arithmetic processing unit 19. As described above, the sensor 2 incorporates the acceleration sensor and the gyro sensor, and the signals output by the sensor 2 include an acceleration detection signal from the acceleration sensor and an angular velocity detection signal from the gyro sensor, which are input to the arithmetic processing unit 19 as detection signals from the sensor 2. The arithmetic processing unit 19 associates the outputs of the first encoder 11 and the second encoder 14 with the signals emitted by the sensor 2.

[0036] The acceleration sensor of sensor 2 detects acceleration in three axes: acceleration in two orthogonal horizontal axes (X axis and Y axis) and acceleration in a vertical axis (Z axis) orthogonal to the two horizontal axes, and outputs acceleration signals for each of the three axes.

[0037] The gyro sensor of sensor 2 is configured to detect angular velocity with respect to the two horizontal axes (X axis and Y axis) and angular velocity with respect to the vertical axis (Z axis) perpendicular to the two horizontal axes.

[0038] Here, the two horizontal axes refer to the first axis 8 and the second axis 13 in Figure 1, where rotation (tilting) around the first axis 8 (X axis) is defined as pitching, rotation (tilting) around the second axis 13 (Y axis) is defined as rolling, and rotation around the vertical axis (Z axis) is defined as yawing.

[0039] The sensor unit 7 will now be described.

[0040] When the sensor unit 7 is in a horizontal position (for example, when the inner frame 6 and the sensor unit 7 are in the same plane, and the detection angles of the first encoder 11 and the second encoder 14 are 0°), the Z-axis passes vertically through the center of the sensor unit 7, and the rotating part 10 of the gyro mechanism is provided along the Z-axis (vertical axis).

[0041] The rotating part 10 has a flywheel rotation drive force (hereinafter referred to as the third motor 17) and a flywheel 18, and the third motor 17 is mounted on the sensor unit 7 such that its rotation axis coincides with the Z axis. The flywheel 18 is mounted concentrically with the rotation axis of the third motor 17 and is rotated at a constant speed by the third motor 17 when the azimuth angle detection device 1 is in operation.

[0042] The flywheel 18 is provided to acquire inertial force, and preferably has the largest possible shape within the limits of being housed in the inner frame 6 so as to obtain a large inertial force. Furthermore, the third motor 17 is preferably a motor capable of rotating the flywheel 18 at high speed in order to obtain a large gyroscopic moment. Here, the rotational speed of the third motor 17 (i.e., the rotational speed of the flywheel 18) can be set to 30 revolutions per second. However, the rotational speed is not limited to 30 revolutions per second, and it is conceivable to set the value of the mass of the flywheel 18 multiplied by the rotational speed to match the required gyroscopic moment.

[0043] Furthermore, the sensor unit 7 is directly connected to the third motor 17 of the rotating part 10, and the sensor 2 provided on the sensor unit 7 is housed in a space 21 formed below the third motor 17 so as to be located approximately on the Z-axis. Therefore, the output of the sensor 2 is linked to the rotation axis of the rotating part 10, and the gyroscopic effect can be detected. Note that the method of providing the sensor 2 on the sensor unit 7 is not limited to the method described above; for example, it may be attached to the lower surface of the sensor unit 7.

[0044] The schematic configuration of the azimuth angle detection device 1 will be explained with reference to Figure 3.

[0045] The azimuth angle detection device 1 comprises the sensor 2, the first encoder 11, the second encoder 14, the first motor 12, the second motor 16, the third motor 17, and the calculation processing unit 19, and further comprises a storage unit 23 and an input / output control unit 24.

[0046] The arithmetic processing unit 19 may be a CPU specifically designed for this embodiment, a general-purpose CPU, an embedded CPU, etc., and the arithmetic processing unit 19 may have a built-in time measurement means such as a clock generator. Furthermore, the storage unit 23 may be a semiconductor memory such as RAM or ROM.

[0047] The memory unit 23 stores programs such as a calculation program for detecting the tilt and rotation of the sensor unit 7 relative to the outer frame 5, a program for removing the offset and drift of the sensor 2, and a program for driving and controlling the first motor 12, the second motor 16, and the third motor 17. It also stores calculation data (i.e., detected acceleration data, tilt angle data, angular velocity data, rotation angle data) and other data.

[0048] The input / output control unit 24 drives the first motor 12 and the second motor 16 based on control commands output from the calculation processing unit 19, and outputs the tilt angle data and rotation data calculated by the calculation processing unit 19 as detection signals.

[0049] The arithmetic processing unit 19 calculates the tilt angle and tilt direction based on the detection result from the acceleration sensor of the sensor 2, corresponding to the rotation angle detected by the first encoder 11 and the rotation angle detected by the second encoder 14, and also calculates the rotation angle based on the detection result from the gyro sensor of the sensor 2.

[0050] Furthermore, the outer frame 5 and the sensor 2 are mechanically associated by the output of the first encoder 11 and the output of the second encoder 14, and are set to indicate the angle of rotation from a predetermined reference angle (for example, a rotation angle of 0°, for example, a state in which the outer frame 5, the inner frame 6, and the sensor unit 7 are located in the same plane).

[0051] The control and calculation processing of the azimuth angle detection device 1 will be explained with reference to Figures 3 and 4. Figure 3 shows the schematic configuration of the azimuth angle detection device 1, and Figure 4 is a schematic diagram of the sensor 2 (an integrated MEMS sensor incorporating a 3-axis acceleration sensor and a gyro sensor), and also shows the relationship between the mechanical axes (X axis, Y axis), the Earth's orientation (N, E, S, W), and the gyro moment due to the Earth's rotation.

[0052] In Figure 4, the X-axis corresponds to the first axis 8, the Y-axis corresponds to the second axis 13, and the axis perpendicular to the plane containing the X and Y axes is defined as the Z-axis. Furthermore, rotation around the X-axis is defined as pitching, rotation around the Y-axis as rolling, and rotation around the Z-axis as yawing.

[0053] Furthermore, the x, y, and z arrows shown in sensor 2 indicate the acceleration direction detected by the accelerometer of sensor 2, where x, y, and z correspond to the X, Y, and Z axes, respectively, and the accelerometer outputs acceleration signals corresponding to the three axes. Additionally, the φ, κ, and γ arrows indicate the rotation vector detected by the gyro sensor of sensor 2, and the gyro sensor outputs angular velocity signals of φ, κ, and γ.

[0054] In this embodiment, since motors and encoders are connected to the X and Y axes, respectively, the sensor unit 7 can be forcibly and accurately rotated 180° or continuously inverted with respect to the X and Y axes, respectively.

[0055] By the way, the sensors 2 (the acceleration sensor and the gyro sensor) are subject to manufacturing offsets and drift due to environmental changes (temperature, pressure, humidity, etc.) and changes over time.

[0056] These drifts can be eliminated by using the first motor 12, the second motor 16, the first encoder 11, and the second encoder 14 to invert the sensor 2 by 180° in the X and Y axes, and then taking the difference or average of the outputs.

[0057] Next, it is known that when a rotating object is rotated in such a way that its axis of rotation is twisted (rotated around an axis that intersects the axis of rotation (a twist axis)), a gyroscopic moment (torque) is generated that rotates on an axis different from both the axis of rotation and the twist axis.

[0058] In the following description, the sensor unit 7 of the azimuth detection device 1 is assumed to be horizontally leveled, that is, the detection angle of the first encoder 11 and the detection angle of the second encoder 14 are reference angles (for example, 0°), and the sensor 2 has detected horizontal. To further simplify the explanation, the azimuth detection device 1 is assumed to be installed on the equator. Also, the flywheel 18 is assumed to be rotating at a constant speed by the third motor 17.

[0059] In Figure 4, the rotation vector Jr of the flywheel of the gyro mechanism is added as a twist by the Earth's rotation (Er) from west W to east E (angular velocity at the equator: 360° / 24h ⇒ 15° / 1h), resulting in the generation of a gyro moment Jm.

[0060] The magnitude of the gyroscopic moment Jm is determined by the mass, radius, angular velocity, and torsional angular velocity of the flywheel. Note that the gyroscopic moment Jm is zero when the flywheel rotation stops, and can be used for offset calibration of gyroscopic moment Jm detection. Alternatively, it can be used for sensitivity calibration of gyroscopic moment Jm detection by changing the rotation speed.

[0061] In this embodiment, the specific generation of twist is achieved by horizontally controlling the pitching and rolling motors 12 and 16 so that the acceleration sensors on the two horizontal axes (X axis and Y axis) become zero, thereby adding a twist to the rotation vector Jr caused by the Earth's rotation Er.

[0062] Let's explain using Figure 5. In Figure 5, E represents the Earth, G represents gravity, and OE represents the Earth's axis, with the foreground pointing south and the background pointing north. Also, let's assume the Earth has rotated from position A to position B.

[0063] At position A, the azimuth detection device 1 is leveled, the sensor 2 detects horizontality, and the flywheel 18 rotates. The axis of rotation of the flywheel 18 coincides with the direction of gravity.

[0064] As the Earth rotates, when the azimuth detection device 1 moves to position B, assuming no external force acts on the azimuth detection device 1, the inertia from the rotation of the flywheel 18 maintains the attitude of the flywheel 18, resulting in state a, and the attitude of the azimuth detection device 1 tilts relative to gravity. The sensor 2 detects this tilt.

[0065] Based on the detection result of the sensor 2, the first motor 12 and the second motor 16 are driven to tilt the sensor 2 (sensor unit 7) so that the sensor 2 detects horizontal. That is, the azimuth angle detection device 1 is tilted in the opposite direction so that the acceleration sensor detects 0, in order to counteract the tilt that occurs in the azimuth angle detection device 1. At this time, a gyroscopic moment Jm is generated, and the direction of the gyroscopic moment Jm is toward the back of the paper (from the front to the back of the paper), that is, true north.

[0066] Furthermore, the magnitude of Earth's rotation Er in regions other than the equator is the cosine component of latitude.

[0067] The aforementioned gyroscopic moment Jm is oriented towards the North Pole (N pole), and the time integral of the gyroscopic moment Jm over a short period of time represents the angular velocity corresponding to its magnitude. The angular velocity corresponding to the magnitude of the gyroscopic moment Jm is captured as two-axis components by the gyro sensors κ and φ, and the azimuth angle relative to the main body is determined.

[0068] On the other hand, when measuring the vertical angle of the sighting axis that indicates an important measurement target point in surveying work, if the direction of the sighting axis of the surveying device and the direction of the Y-axis of the azimuth angle detection device 1 are set to coincide, the sensor unit 7 can be horizontally controlled by the first motor 12 so that the sensor 2 detects horizontality while the measurement target point is sighted, and the vertical angle of the sighting line can be determined by reading the value of the first encoder 11.

[0069] The horizontal control of the sensor unit 7 is a function necessary for measuring both the azimuth angle and the vertical angle. Furthermore, the azimuth angle and the vertical angle can be detected based on the detection results of the first encoder 11 and the second encoder 14 associated with the horizontal control of the sensor unit 7. In the azimuth angle detection device 1 according to this embodiment, the azimuth angle and the vertical angle can be detected with the same configuration mechanism, thus simplifying the device. That is, the azimuth angle detection device and the vertical angle detection device are integrated.

[0070] Furthermore, the sensitivity of the gyro sensor can be calibrated by reading the pitching and rolling motor rotations and the first and second encoders with time management, and comparing the angular velocity of the motor rotation obtained from the encoders and time with the angular velocity of the gyro sensor.

[0071] Incidentally, the gyro sensors κ and φ have a detected angular velocity which is the sum of the angular velocity during horizontal control and the angular velocity corresponding to the gyro moment. Therefore, the angular velocity corresponding to the gyro moment is obtained by subtracting the angular velocity during horizontal control from the detected angular velocity. The angular velocity during horizontal control is obtained from time-controlled readings of the first and second encoders (for example, at short periodic reading intervals).

[0072] Alternatively, by alternating between controlling the orthogonal X and Y axes for horizontal control, the angular velocity of the control and the angular velocity corresponding to the gyroscopic moment can be detected separately. This is because the rotation axis of the rotating object (flywheel) is the Z axis, and in the aforementioned relationship between the torsion axis and the gyroscopic moment generation axis, the X and Y axes become the torsion axis and the gyroscopic moment generation axis. Therefore, when the X axis is the torsion axis, the Y axis becomes the gyroscopic moment generation axis, and the angular velocity of the control (torsion) is detected in κ, and the angular velocity corresponding to the gyroscopic moment is detected in φ. Conversely, when the Y axis is the torsion axis, the X axis becomes the gyroscopic moment generation axis, and the angular velocity of the control (torsion) is detected in φ, and the angular velocity corresponding to the gyroscopic moment is detected in κ. Therefore, the angular velocity of the control (torsion) and the angular velocity corresponding to the gyroscopic moment can be detected separately.

[0073] As described above, in this embodiment, direction can be detected with an extremely simple configuration. Furthermore, by forcibly driving the first motor 12 and the second motor 16 so that the sensor 2 detects horizontal, the vertical can be detected from the angle detected by the first encoder 11 and the second encoder 14 at that time. In other words, with the azimuth angle detection device 1 according to this embodiment, azimuth angle detection and vertical detection can be performed with the same configuration.

[0074] Next, a surveying device 31 equipped with the azimuth detection device 1 will be described with reference to Figure 6.

[0075] The surveying device 31 mainly comprises a distance measuring unit 32, a measurement direction imaging unit 33, the calculation control unit 34, a main storage unit 35, the azimuth angle detection device 1, a measurement direction detection unit 36, a display unit 40, and an optical axis deflection unit 41. These are housed and integrated within a housing 42.

[0076] Furthermore, the outer frame 5 of the azimuth detection device 1 is fixed to the housing 42, or to a structural member fixed to the housing 42, and is integrated with the housing 42, i.e., the surveying device 31.

[0077] The arithmetic control unit 34 may be a CPU specifically designed for this embodiment, a general-purpose CPU, an embedded CPU, etc. The main storage unit 35 may be a semiconductor memory such as RAM or ROM, a magnetic recording memory such as an HDD, or an optical recording memory. Furthermore, some functions of the arithmetic control unit 34 may be assigned to the arithmetic processing unit 19.

[0078] The main unit storage unit 35 stores various programs for executing this embodiment, such as a distance measurement program, a tracking program, an image processing program, an optical axis deflection control program, a program for calculating the azimuth angle, a program for converting the detection result of the measurement direction detection unit into an azimuth angle, a program for calculating the measurement result into a 3D coordinate system based on the azimuth angle, and a program for performing calibration of the azimuth angle detection device 1. The calculation control unit 34 unpacks and executes the stored programs. The main unit storage unit 35 also stores various data such as measurement data and image data.

[0079] The calculation control unit 34 performs individual control of the distance measuring unit 32, the optical axis deflection unit 41, and the measurement direction imaging unit 33, as well as their synchronization control.

[0080] The distance measuring unit 32 irradiates the object to be measured with distance measuring light through the optical axis deflection unit 41, receives the reflected light from the object to be measured, and measures the distance to the object.

[0081] The optical axis deflection unit 41 deflects the distance measuring light so as to sight the object to be measured, and the measurement direction detection unit 36 ​​detects the angle of deviation of the distance measuring light with respect to the reference optical axis O. The reference optical axis O coincides with the reference axis set in the azimuth angle detection device 1 described above.

[0082] Furthermore, the optical axis deflection unit 41 disclosed in Patent Documents 2, 3, and 4 can be used.

[0083] The distance measuring unit 32 inputs the distance measurement result to the calculation control unit 34, and the measurement direction detection unit 36 ​​inputs the declination angle of the distance measuring light to the calculation control unit 34. The azimuth angle detection device 1 detects the azimuth angle and vertical angle with respect to the reference optical axis O, and inputs the detection result to the calculation control unit 34.

[0084] The calculation control unit 34 stores the distance measurement result from the distance measuring unit 32, the detection result from the measurement direction detection unit 36, and the detection result from the azimuth angle detection device 1 in the main unit storage unit 35, relating them together. Furthermore, it calculates three-dimensional coordinates based on the installation position of the surveying device 31, using the distance measurement result and the measurement direction detection as the basis. In addition, the calculation control unit 34 can calculate three-dimensional coordinates by converting the horizontal angle obtained from the detection result of the measurement direction detection unit 36 ​​into an azimuth angle, based on the detection result of the azimuth angle detection device 1.

[0085] The measurement direction imaging unit 33 has a known relationship with the reference optical axis O, that is, the imaging optical axis of the measurement direction imaging unit 33 is parallel to the reference optical axis O and the distance between the optical axes is known. The measurement direction imaging unit 33 acquires image data centered on the reference optical axis O with a field of view larger than the maximum deflection angle of the optical axis deflection unit 41.

[0086] The surveying device 31 is equipped with the azimuth detection device 1, which has azimuth detection and vertical angle detection functions, and can acquire three-dimensional coordinates of the object to be measured based on true north (true south) without the need for a separate azimuth detection device. [Explanation of Symbols]

[0087] 1. Azimuth detection device 2 sensors 3. Gyroscope mechanism 5 Outer frame 6. Inner frame 7 Sensor Unit 11. First Encoder 12 First Motor 14. Second Encoder 16. Second motor 17. Third motor 18 Flywheel 19. Arithmetic Processing Unit 31 Surveying equipment 34. Arithmetic Control Unit 36 Measurement direction detection unit 41 Optical axis deflection section

Claims

1. A method for detecting an azimuth angle, comprising a sensor unit for detecting tilt and rotation relative to the horizontal, and a flywheel provided on the sensor unit having a rotation axis extending in the vertical direction, wherein the flywheel is rotated at a constant speed and tilted to generate a gyroscopic moment in order to counteract the change in tilt that occurs in accordance with the rotation of the Earth, and the direction of the Earth's axis (north or south) is determined from the direction of the gyroscopic moment.

2. An azimuth detection device comprising: an inner frame provided inside an outer frame; a sensor unit for detecting tilt and rotation relative to the horizontal, the inner frame being rotatably supported by the outer frame via a first axis, the sensor unit being rotatably supported by the inner frame via a second axis orthogonal to the first axis, first and second rotational powers provided on each axis to rotate each axis, a calculation processing unit that drives and controls each rotational power based on the detection results from the sensor unit, a flywheel provided on the sensor unit, and a rotational power for rotating the flywheel at a constant speed, wherein the calculation processing unit generates a gyroscopic moment by controlling the tilt of the sensor unit with the first and second rotational powers to counteract changes in the tilt of the sensor unit, and determines the north or south of the Earth's axis from the direction of the gyroscopic moment.

3. The azimuth angle detection device according to claim 2, wherein a first encoder for detecting the relative rotation angle between the outer frame and the inner frame is provided on the first axis, a second encoder for detecting the relative rotation angle between the inner frame and the sensor unit is provided on the second axis, and the calculation processing unit is configured to drive and control each of the rotational powers based on the detection results from the sensor unit.

4. The azimuth angle detection device according to claim 3, wherein the calculation processing unit is configured to invert the sensor unit by 180° using the first and second rotational power based on the detection results of the first and second encoders, and to take the difference or average of the output of the sensor unit before and after inversion to remove the effect of drift of the sensor unit.

5. A surveying device comprising an azimuth angle detection device according to claim 2 or claim 3, a distance measuring unit, an optical axis deflection unit, a measurement direction detection unit, and a calculation control unit, wherein the calculation control unit is configured to acquire the three-dimensional coordinates of a measurement target with respect to true north based on the distance measuring result of the distance measuring unit, the detection result of the measurement direction detection unit, and the detection result of the azimuth angle detection device.

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