JP2016095310A - Bearing measurement method and bearing measurement device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a bearing measurement method using a three-axis electronic compass with which it is possible to accurately measure the specific bearing of a photographing device, e.g., the bearing of the photographic optical axis of the photographing device, irrespective of the postures of the three-axis electronic compass and the photographing device that incorporates it.SOLUTION: Provided is a bearing measurement method for measuring the bearing of a specific direction to a three-axis electronic compass using the three-axis electronic compass and an inclination sensor for detecting the inclination of the three-axis electronic compass, said method having: a step for acquiring the angle of elevation formed by the specific direction and the horizontal plane, and switching, in accordance with the acquired angle of elevation, two output values to select among the three output values obtained from the three-axis electronic compass; a step for acquiring the bearing of earth magnetism from the switched two output values; a step for acquiring the bearing of the angle of rotation in the specific direction from the inclination sensor; a step for calculating, on the basis the acquired angle of elevation, bearing of earth magnetism, and angle of rotation, a deviation angle in the bearing of the specific direction that occurs due to switching.SELECTED DRAWING: Figure 8

Description

  The present invention is a three-axis electronic device that can always accurately measure the orientation of a specific direction of the imaging device (for example, the orientation of the imaging optical axis of the imaging optical system of the imaging device) regardless of the orientation of the mounted imaging device (digital camera). The present invention relates to a direction measuring method and a direction measuring apparatus using a compass.

  Devices such as binoculars equipped with an electronic compass are known. For example, Patent Document 1 discloses binoculars that can display an electronic compass in the field of view, and Patent Document 2 discloses binoculars that display the orientation of the observed target in the field of view. However, in Patent Documents 1 and 2, the orientation cannot be detected correctly in a state where the optical axis or line of sight of the objective optical system is greatly inclined with respect to the horizontal, for example, when looking up at the sky or the zenith.

  In recent years, a three-axis electronic compass having three-axis geomagnetic sensors orthogonal to each other has been developed. A device such as a mobile phone equipped with this type of three-axis electronic compass detects a geomagnetism by a three-axis geomagnetic sensor orthogonal to each other, and further detects the direction of gravity (tilt in the front-rear direction of the device). The direction in which the user is facing is calculated (Patent Document 3).

  Furthermore, in order to photograph a celestial body that moves relative to the imaging device due to the rotation of the earth (diurnal motion), the imaging device of the imaging device is driven (moved) while the imaging device is fixed. Astronomical automatic tracking photography has been proposed (Patent Documents 4 and 5).

JP 2001-13420 A JP 7-43162 A JP 2007-40982 A JP 2008-289052 A JP 2010-122672 A

  In such celestial automatic tracking shooting, in order to perform celestial tracking with higher accuracy, it is necessary to accurately measure the shooting direction in which the shooting optical system of the shooting device is facing.

  However, a conventional three-axis electronic compass such as Patent Document 3 is applied to astronomical auto-tracking photographing such as Patent Documents 4 and 5, and the photographing device is directed in the zenith direction (or a direction close thereto). If an attempt is made to measure the shooting direction in which the photographing optical system of the apparatus is directed, a completely different direction may be measured as the direction in which the photographing optical system of the photographing apparatus is directed.

  The present invention is based on such a problem awareness, regardless of the orientation of the three-axis electronic compass and the photographing apparatus equipped with the three-axis electronic compass, the orientation of the photographing apparatus in a specific direction (for example, the orientation of the photographing optical axis of the photographing optical system of the photographing apparatus) It is an object of the present invention to obtain an azimuth measuring method and an azimuth measuring apparatus using a three-axis electronic compass capable of accurately measuring).

  An azimuth measuring method using a three-axis electronic compass according to the present invention includes a three-axis electronic compass having an orthogonal three-axis geomagnetic sensor and selecting and using two of three output values of each axis obtained from the sensor. An azimuth measuring method for measuring an azimuth in a specific direction with respect to the three-axis electronic compass using an inclination sensor for detecting the inclination of the three-axis electronic compass, wherein an elevation angle formed by the specific direction and a horizontal plane is determined from the tilt sensor. According to the acquired elevation angle, the step of switching two output values to be selected from among the three output values obtained from the three-axis electronic compass, and the geomagnetic azimuth by the two output values thus switched. Generated by the switching based on the step of acquiring, the step of acquiring the rotation angle around the specific direction from the tilt sensor, and the acquired elevation angle, geomagnetic azimuth, and rotation angle. Calculating a deviation angle of orientation of the specific direction that is characterized by having the steps of correcting the orientation of the specific direction by the shift angle calculated above.

  In the azimuth measuring method using the three-axis electronic compass of the present invention, the acquired elevation angle exceeds the predetermined boundary value in the range of 30 ° to 60 ° or in the range of −30 ° to −60 °. It is preferable to switch between two output values to be selected.

The step of calculating the deviation angle may include the step of calculating the deviation angle Δη by the following equation 3 where the elevation angle is h, the rotation angle is θ, and the deviation angle is Δη.
Δη = ArcTan (Tan (θ) / sin (h)) Equation 3

In the step of correcting the azimuth in the specific direction, when the azimuth obtained from the three-axis electronic compass after the switching is A and the actual azimuth in the specific direction after the switching is A ′, the actual azimuth A ′ is The step of calculating by Equation 4 may be included.
A '= A + Δη (4)

  An azimuth measuring apparatus using a three-axis electronic compass according to the present invention includes a three-axis electronic compass having an orthogonal three-axis geomagnetic sensor and selecting and using two of three output values of each axis obtained from the sensor. An azimuth measuring device for measuring an azimuth in a specific direction with respect to the three-axis electronic compass, wherein the elevation angle formed by the specific direction and a horizontal plane is determined from the tilt sensor. According to the acquired elevation angle, switching means for switching two output values to be selected from among the three output values obtained from the three-axis electronic compass, and the direction of geomagnetism by the two switched output values Based on the acquired elevation angle, geomagnetic azimuth, and rotation angle, the azimuth acquisition means for acquiring the rotation angle, the rotation angle acquisition means for acquiring the rotation angle around the specific direction from the tilt sensor, A deviation angle calculating means for calculating the deviation angle of the azimuth in the specific direction generated by switching by the conversion means; and a correcting means for correcting the azimuth in the specific direction based on the deviation angle calculated by the deviation angle calculating means. It is characterized by.

  The switching means switches the two output values to be selected when the acquired elevation angle exceeds a predetermined boundary value in a range of 30 ° to 60 ° or a range of −30 ° to −60 °. preferable.

The deviation angle calculation means can calculate the deviation angle Δη by the following equation 3 where the elevation angle is h, the rotation angle is θ, and the deviation angle is Δη.
Δη = ArcTan (Tan (θ) / sin (h)) Equation 3

The correction means calculates the actual azimuth A ′ by the following equation 4 when the azimuth obtained from the three-axis electronic compass after the switching is A and the actual azimuth in the specific direction after the switching is A ′. Can do.
A '= A + Δη (4)

  The azimuth measuring apparatus using the three-axis electronic compass of the present invention can be mounted on, for example, a digital camera, and the specific direction can be set in parallel with the shooting optical axis of the shooting lens of the mounted digital camera.

  The azimuth measuring apparatus using the three-axis electronic compass of the present invention preferably includes display means for displaying the measured azimuth of the photographing optical axis of the photographing lens.

  According to the present invention, it is possible to accurately measure the orientation of a specific direction of the imaging device (for example, the orientation of the imaging optical axis of the imaging optical system of the imaging device) regardless of the attitude of the 3-axis electronic compass and the imaging device equipped with the 3-axis electronic compass. An azimuth measuring method and an azimuth measuring apparatus using a three-axis electronic compass are obtained.

It is the perspective view which showed the relationship between the attitude | position of the camera carrying a 3-axis electronic compass, and the 3 axis | shafts of a 3-axis electronic compass. When the camera is held horizontally, (A) is a side view and (B) is a plan view. It is a side view at the time of facing the camera upward. When the camera is directed upward, (A) is a plan view, and (B) is a plan view in which the camera is rotated around the photographing optical axis. It is the graph which showed the mode of the geomagnetic vector measured by rotating a 3-axis electronic compass. It is the graph which decomposed | disassembled into the component and showed the mode of the geomagnetic vector measured by rotating a 3-axis electronic compass. It is the figure which showed the main component of embodiment of the digital camera to which the azimuth | direction measuring apparatus provided with the 3-axis electronic compass of this invention was applied with the block. It is the figure which showed the operation | movement which calculates the azimuth | direction which the imaging | photography optical axis is facing with the azimuth | direction measuring method and azimuth | direction measuring apparatus using a 3-axis electronic compass.

  FIG. 1 is a perspective view showing the relationship between the posture of a camera 10 equipped with a three-axis electronic compass 110 having three orthogonal axes and the three axes of the three-axis electronic compass 110 (the maximum sensitivity direction axis of each magnetic sensor). . The three-axis electronic compass 110 is configured to select and calculate two output values of three output values (voltage values, etc.) detected by the various magnetic sensors and detect the direction of the geomagnetism (geomagnetic line). is there. The three axes of the three-axis electronic compass 110 are defined by an X axis, a Y axis, and a Z axis that are orthogonal to each other. In FIG. 1, one of the three-axis geomagnetic sensors of the three-axis electronic compass 110 is coincident with the Y axis set in parallel with the photographing optical axis LO of the photographing lens 101 of the camera 10. The other two-axis geomagnetic sensors coincide with the X axis set in parallel with the bottom surface of the camera 10 and the Z axis set in the vertical direction of the camera 10.

  It is assumed that geomagnetism (lines of magnetic force) on the earth is oriented horizontally. Since the geomagnetism is a vector having a direction and a magnitude (hereinafter referred to as “geomagnetic vector”), the XY axis of the three-axis electronic compass 110 is set to be horizontal when the camera 10 is held horizontally on the earth. Yes. The relationship between the geomagnetic vector and the three axes of the camera 10 and the three-axis electronic compass 110 is as shown in FIGS. When the camera 10 is held horizontally, the photographing optical axis LO is horizontal (parallel to the horizontal plane), and the bottom surface of the camera 10 or the long side of the imaging surface of the camera is horizontal (parallel to the horizontal plane). Say. When the camera 10 is held horizontally as described above, the XY axis is horizontal and the Z axis is vertical. The posture of the camera 10 is the reference position. In FIG. 2 to FIG. 4, the symbol S denotes the geomagnetic south pole (magnetic north) direction, and the symbol N denotes the geomagnetic north pole direction.

  When the direction of the photographic lens 101 is changed (panned) on the horizontal plane, the angle formed by the X axis and Y axis of the three-axis electronic compass 110 and the geomagnetic vector changes, and the output of the geomagnetic sensor in the X axis and Y axis directions is changed. Therefore, the direction of the geomagnetic vector in the biaxial plane defined by the X axis and the Y axis (hereinafter referred to as “XY plane”) is synthesized by combining the outputs of the geomagnetic sensors in the X axis and Y axis directions. Magnetic north) can be calculated.

  Since the geomagnetism is a vector having a magnitude and direction, the greater the magnitude of the geomagnetic vector projected onto the XY plane, that is, the closer the angle (absolute value) between the XY plane and the horizontal plane is to 0 °, the geomagnetic vector. The direction (magnetic north (S pole) direction, orientation) can be calculated accurately and accurately. On the other hand, when the camera 10 is tilted upward or downward (tilted), the angle (absolute value) formed by the XY plane and the geomagnetism increases, and the geomagnetic vector projected on the XY plane decreases, resulting in accuracy. Since the magnitude of the projected geomagnetic vector is 0 at a maximum angle of 90 °, the accuracy and accuracy of the three-axis electronic compass 110 are extremely lowered. Therefore, when the camera 10 is tilted upward or downward from an angle of 45 ° formed by the XY plane and the geomagnetism, it is better to measure the geomagnetism in the XZ plane rather than the XY plane. Therefore, in the present embodiment, an acceleration sensor (3-axis acceleration sensor, tilt sensor) 120 (FIG. 7) is mounted on the camera 10, and the acceleration sensor 120 forms a horizontal plane with the camera posture, for example, the imaging optical axis LO of the imaging lens 101. The elevation angle (including elevation angle and depression angle) h is measured, and the selection of two output values among the three output values output by the triaxial geomagnetic sensor is switched with the absolute value 45 ° of the elevation angle h as a boundary. That is, when the geomagnetic vector is horizontal, the output value is switched to the output value of the geomagnetic sensor constituting the XY plane or the XZ plane where the absolute value of the elevation angle h is less than 45 °. Hereinafter, switching a specific 2-axis output value is referred to as “switching to a 2-axis geomagnetic sensor”, and calculating using a specific 2-axis output value is referred to as “measuring with a 2-axis geomagnetic sensor”.

  However, when the biaxial geomagnetic sensor is switched so that the geomagnetism is measured by the biaxial geomagnetic sensor constituting the XZ plane, the biaxial geomagnetic sensor measures the geomagnetic vector in the XZ plane. In the case of the camera 10 shown in FIG. 1, for example, when the two-axis geomagnetic sensor used in the three-axis electronic compass 110 is switched to the two-axis geomagnetic sensor corresponding to the XZ plane, the bottom and top of the camera 10 are facing Z. The azimuth in the X-axis direction in which the axial direction or the side surface of the camera 10 faces is measured.

  When the camera 10 calculates tracking data for performing automatic celestial tracking shooting as described in Patent Documents 4 and 5 described above, information on the direction in which the shooting lens 101 faces is required with high accuracy. However, in a state where the elevation angle h exceeds 45 °, that is, in a state where the three-axis electronic compass 110 is switched to the two-axis geomagnetic sensor constituting the XZ plane, the camera 10 is rotated about the photographing optical axis LO. When the posture is changed, for example, when the camera 10 is rotated about the photographing optical axis LO from the camera posture in FIGS. 3 and 4A with the camera 10 facing upward to the camera posture in FIG. 4B. Since the orientation of the geomagnetic vector with respect to the XZ plane changes even though the orientation of the photographing lens 101 is not changed, the three-axis electronic compass 110 is directed to the photographing lens 101. Will measure a different direction.

  Therefore, the acceleration for measuring the attitude of the camera 10 when the measurement data (the direction of the magnetic field, the data of the magnetic north direction) is obtained from the three-axis electronic compass 110 switched to the two-axis geomagnetic sensor constituting the XZ plane. An elevation angle h (an angle formed by the photographic optical axis LO and a horizontal plane) and a rotation angle θ around the photographic optical axis LO are obtained from the sensor (three-axis acceleration sensor) 120 (FIG. 7), and measurement data of the three-axis electronic compass 110 is obtained. Correction is made so that the photographic optical axis LO is oriented. The acceleration sensor 120 functions as an inclination sensor that detects an elevation angle h and a rotation angle θ around the photographing optical axis LO.

  More specifically, for example, a state in which the camera 10 is held horizontally (a state in which the photographing optical axis LO and the bottom surface of the camera 10 are parallel to the horizontal plane) is a state in which the rotation angle θ is 0 °, and an XY plane is configured. It is assumed that the orientation of the photographing optical axis LO is detected as “north” (N) by the biaxial geomagnetic sensor. If the elevation angle h is changed without rotating the camera 10 around the photographing optical axis LO as it is, the three-axis electronic compass 110 is switched to the geomagnetic sensor constituting the XZ plane, even if the geomagnetic sensor is switched to the three-axis. It is assumed that the orientation of the photographing optical axis LO measured by the electronic compass 110 is set (programmed) so as not to fluctuate as “north”. Now, when the camera 10 is rotated horizontally by the rotation angle θ = 90 ° around the photographing optical axis LO in a state where the camera 10 is held horizontally, the camera 10 is in the vertical shooting posture, and at this time, the two axes that already constitute the YZ plane. Since the camera 10 is switched to the geomagnetic sensor, when the elevation angle h is changed without rotating the camera 10 around the photographing optical axis LO from the vertical shooting posture, the camera 10 is switched to the geomagnetic sensor constituting the XZ plane. The direction of the photographing optical axis LO indicated by the three-axis electronic compass 10 is shifted by 90 ° (or −90 °) with respect to the previous direction (“north”), and “west” (or “east”). Therefore, when the vertical shooting posture (θ = 90 °) is detected, the detection value (azimuth) may be corrected by −90 ° (or + 90 °). However, when the rotation angle θ is an angle between 0 ° and 90 ° (0 ° <θ <90 °), the detected value (azimuth) of the three-axis electronic compass 110 indicates θ equal to the rotation angle. Just deducting can not get an accurate bearing.

  In order to generalize the method of measuring the accurate azimuth angle of the imaging optical axis LO in a state where the camera 10 is inclined at the elevation angle h and the two-axis geomagnetic sensor of the three-axis electronic compass 110 is switched, the elevation angle h (45 ° <h Consider that the XZ plane tilted according to <90 °) detects geomagnetism. That is, even when the elevation angle h is 45 ° and 90 °, the three-axis electronic compass 110 indicates the same azimuth 0 °, but the elevation angle h is 45 ° and 90 ° on the XZ plane. The magnitude of the projected geomagnetic vector is different. This change in the magnitude of the geomagnetic vector can be explained by the fact that when viewed from the top, when the horizontally held circle is tilted in the elevation direction, it becomes an ellipse. When the points obtained by the geomagnetic vector when the biaxial geomagnetic sensor is rotated on the horizontal plane are plotted on the biaxial plane, a circle (hereinafter referred to as “magnetic circle”) is drawn (see FIGS. 5 and 6).

  More specifically, referring to FIG. 5, the camera 10 is tilted upward until the elevation angle h reaches 90 ° without rotating the camera 10 around the photographic optical axis LO from the initial state where the camera 10 is directed to the horizontal line (θ = 0 °). When the camera 10 is rotated around the optical axis LO with the LO facing the zenith, the magnetic circle drawn on the XZ plane (the locus of the geomagnetic vector) is a circle (since the XZ plane is parallel to the horizontal plane). The XZ plane rotates with respect to the geomagnetic vector by an angle (rotation angle θ) rotated around the photographing optical axis LO. This magnetic circle is drawn as a unit circle in the arc of the locus (2) in FIG. 5, and the magnetic vector when the camera 10 is rotated 45 ° around the imaging optical axis LO (θ = 45 °) is the Z axis. The azimuth line (4) representing the azimuth of The vertical axis is the direction of the photographing optical axis LO (Y axis) in the initial state, and the direction of the Z axis when the photographing optical axis LO faces the zenith. It can be seen that the azimuth line (4) of the Z axis is deviated (rotated) by 45 ° from the initial direction of the photographing optical axis LO.

  On the other hand, when the camera 10 is tilted from the initial state until the elevation angle h is 45 ° without rotating around the imaging optical axis LO (when the elevation angle h of the imaging optical axis LO is 45 °), the XZ plane is Since the angle is 45 ° with respect to the horizontal plane, the magnetic circle projected onto the XZ plane becomes an ellipse as shown in the locus (1). In this state, when the camera 10 is rotated 45 ° around the photographic optical axis LO, the Z-axis orientation is shifted from the photographic optical axis LO and the Z-axis azimuth line (4) data as indicated by the azimuth line (3). It can be seen that it points to a different direction. This is a form in which only the diameter of the circle on the photographic optical axis LO side of the locus (2) in FIG. 6 is reduced as the locus (1), and the locus (2) is also (1) in the direction perpendicular to the photographic optical axis LO. ) Also has the same diameter. That is, as shown in FIG. 6, when the Z axis azimuth lines (3) and (4) are decomposed into orthogonal vectors α, β and vectors β, γ, in the case of elevation angles 90 ° and 45 °, Although the magnitude of the vector γ is the same, the vector β is reduced with respect to the vector α. Therefore, when combined, a shift such as Z-axis azimuth lines (3) and (4) occurs. Therefore, the present camera 10 corrects the deviation between the azimuth of the photographing optical axis LO and the azimuth measured by the three-axis electronic compass 110 caused by the change in the elevation angle h as follows.

If the angle formed by the photographic optical axis LO and the azimuth line (3) of the Z axis is Δη,
Δη = ArcTan (size of vector α / size of vector γ) Equation 1
It becomes.
The magnitude of the vector γ is cos (θ), where θ is the rotation angle around the photographing optical axis LO.
The magnitude of the vector α is the ellipse formula
(X ² ) / (a ² ) + (Y ² ) / (b ² ) = 1 ・ ・ ・ Equation 2
If the variable Y is considered to be the magnitude of the vector α, the elevation angle is h and if a = 1, then X = cos (θ) and b = sin (h), so the deviation angle Δη is
Δη = ArcTan (((1− (cos (θ) ² / a ² ) ^1/2 ) × sin (h)) / cos (θ))
= ArcTan (Tan (θ) / sin (h)) Equation 3
Can be calculated.
Therefore, the actual azimuth A ′ of the imaging optical axis LO when the biaxial geomagnetic sensor is switched from the azimuth A obtained from the triaxial electronic compass 110 and the deviation angle Δη is:
A '= A + Δη (4)
Can be calculated.

  An embodiment in which the azimuth measuring apparatus using the three-axis electronic compass of the present invention is mounted on a digital camera will be described with reference to FIG. The camera 10 of this embodiment includes a camera body 11 and a photographing lens 101 (photographing optical system L). In the camera body 11, an imaging sensor 13 is disposed behind the imaging optical system L as imaging means. The imaging optical axis LO of the imaging optical system L and the imaging surface 14 of the imaging sensor 13 are orthogonal to each other. This image sensor 13 is mounted on an image sensor drive unit (moving means) 15. The imaging sensor drive unit 15 includes a fixed stage, a movable stage movable with respect to the fixed stage, and an electromagnetic circuit that moves the movable stage with respect to the fixed stage. The imaging sensor 13 is mounted on the movable stage. Is retained. The imaging sensor 13 (movable stage) is controlled to move in a desired direction orthogonal to the photographing optical axis LO at a desired moving speed, and further, an axis parallel to the photographing optical axis LO (somewhere in a plane perpendicular to the optical axis). Rotation is controlled at a desired rotational speed with the instantaneous center) located at the center. Such an image sensor driving unit 15 is known as an image stabilization unit for a camera image blur correction device.

  The camera body 11 is equipped with a CPU (switching means, azimuth acquisition means, rotation angle acquisition means, deviation angle calculation means, correction means, calculation control means) 21 that controls the functions of the entire camera. The CPU 21 controls the drive of the image sensor 13, processes the image signal captured by the image sensor 13, displays it on the LCD monitor 23, and writes it in the memory card 25. (The CPU 21 detects signals detected by the X-direction gyro sensor GSX, the Y-direction gyro sensor GSY, and the rotation detection gyro sensor GSR in order to detect the shake applied to the camera when the image sensor driving unit 15 is used as the image stabilization unit. Is entered.

  The camera body 11 includes a power switch 27, a release switch 28, and a setting switch 29 as switches. The CPU 21 executes control according to the on / off states of these switches 27, 28 and 29. For example, in response to the operation of the power switch 27, the power supply from a battery (not shown) is turned on / off, and in response to the operation of the release switch 28, focus adjustment processing, photometry processing, and photographing processing are executed. The setting switch 29 is a switch for selecting and setting a shooting mode or the like.

  In the camera body 11, a GPS unit 130 as latitude information input means, a three-axis electronic compass 110 as direction information input means, and an acceleration sensor (three-axis acceleration sensor) 120 as elevation angle and inclination information input means are incorporated. ing. The CPU 21 includes latitude and longitude information from the GPS unit 130, azimuth A information from the three-axis electronic compass 110, and an acceleration sensor 120 that includes a rotation angle θ (left-right tilt angle of the camera body 11) and an elevation angle h about the photographing optical axis LO. Information is entered.

  The camera posture is information related to the rotation angle θ around the photographing optical axis LO from the reference position of the camera body 11 (imaging sensor 13) and information related to the elevation angle h of the photographing lens 101 (photographing optical axis LO). The reference position of the camera body 11 (imaging sensor 13) is, for example, a direction parallel to the photographing optical axis LO in the Y axis and a direction parallel to the long side direction of the rectangular imaging sensor 13 (usually parallel to the bottom surface of the camera body 11). The YX plane is the horizontal plane when the direction orthogonal to the photographing optical axis LO is the X axis. When the camera body 11 is directed upward or downward, the rotational angle θ around the imaging optical axis LO of the camera body 11 (rotation angle when the camera body 11 rotates around the imaging optical axis LO from the reference position). The angle formed by the photographic optical axis LO (Y axis) and the horizontal plane is the elevation angle h. At the reference position of the camera body 11, the rotation angle (left-right tilt angle) θ is 0 ° and the elevation angle h is 0 °.

  In the three-axis electronic compass 110, the Y axis is parallel to the photographing optical axis LO, the X axis is parallel to the longitudinal direction of the image sensor 13 of the camera body 11, and the Z axis is perpendicular to the X axis and Y axis (of the image sensor 13). Parallel to the short direction). The CPU 21 measures (calculates) the azimuth (photographing azimuth) of the photographic optical axis LO using the three-axis electronic compass 110 regardless of the posture of the camera body 11.

  The GPS unit 130, the three-axis electronic compass 110, and the acceleration sensor 120 may be externally attached to the camera body 11 in addition to being built in the camera body 11. Specifically, these sensors can be mounted on an accessory shoe or a bracket attached to the bottom plate, and input to the CPU 21 via a contact of the accessory shoe or a connector such as a USB.

  The CPU 21 receives the latitude / longitude information input from the GPS unit 130, the azimuth A input from the three-axis electronic compass 110, the elevation angle h and the rotation angle (camera posture) θ input from the acceleration sensor 120, and the focal length detection device 105 described above. The input focal length information f is displayed on the LCD monitor 23 and recorded in the memory card 25 as shooting information or log information.

  The azimuth measuring operation of the photographing optical axis LO by the camera 10 will be described with reference to the flowchart shown in FIG. In the flowchart, first, the CPU 21 acquires the elevation angle h from the acceleration sensor 120 (S11). Next, the CPU 21 checks whether the acquired elevation angle h is larger than 45 ° or smaller than −45 ° (S13). When the elevation angle h is not larger than 45 ° and not smaller than −45 ° (−45 ° ≦ h ≦ 45 °, S13: NO), the CPU 21 acquires the azimuth A from the triaxial electronic compass 110 (S15). )finish. In this case, since the triaxial electronic compass 110 uses a biaxial geomagnetic sensor constituting an XY axis plane, the azimuth A input from the triaxial electronic compass 110 coincides with the photographing azimuth of the photographing optical axis LO. ing.

  When the elevation angle h is larger than 45 ° or smaller than −45 ° (45 ° <h ≦ 90 ° or −90 ° ≦ h <−45 °, S13: YES), the CPU 21 changes the three-axis electronic compass 110 to A switching signal for switching to the biaxial geomagnetic sensor constituting the XZ axis plane is sent. Upon receiving this switching signal, the 3-axis electronic compass 110 switches to the 2-axis geomagnetic sensor constituting the XZ-axis plane (S17), measures the geomagnetism with the switched 2-axis geomagnetic sensor, and outputs the azimuth A. The CPU 21 acquires this orientation A from the three-axis electronic compass 110 (S19). Subsequently, the CPU 21 acquires the rotation angle θ from the acceleration sensor 120 (S21). The order of acquiring the azimuth A from the three-axis electronic compass 110 (S19) and the step of acquiring the rotation angle θ from the acceleration sensor 120 (S21) do not matter. That is, after obtaining the rotation angle θ from the acceleration sensor 120, the azimuth A may be obtained from the three-axis electronic compass 110.

  Next, the CPU 21 determines whether the elevation angle h is 90 ° or −90 ° (S22). When the elevation angle h is 90 ° or −90 ° (S22: YES), the photographing optical axis LO is vertically upward or vertically downward, and the orientation of the photographing optical axis LO cannot be defined. Also, the rotation angle θ cannot be acquired. Therefore, the azimuth A remains the azimuth acquired in S19, and θ = 0 ° is substituted (S24). At this time, “vertical” or the like may be displayed on the LCD monitor 23. When the elevation angle h is not 90 ° or −90 ° (45 ° <h <90 ° or −90 ° <h <−45 °, S22: NO), the CPU 21 sets the acquired elevation angle h and rotation angle θ to Equation 3. The displacement angle Δη is calculated by substituting (S23). Further, the CPU 21 substitutes the acquired azimuth A and the calculated shift angle Δη into the equation 4 to calculate the azimuth A ′ that is the photographic azimuth of the photographic optical axis LO (S25).

  With the above processing, the CPU 21 can calculate the azimuth A ′, which is an accurate photographing azimuth of the photographing optical axis LO, even when the camera body 11 faces the zenith or the like. The calculated azimuth A ′ is displayed on the LCD monitor 23 and written to the memory card 25 as photographing data.

  Since the camera 10 equipped with the azimuth measuring apparatus using the three-axis electronic compass of the present invention is also equipped with the GPS unit 130, the photographing azimuth and photographing elevation angle are recorded together with the photographing point position information (latitude and longitude information). can do. Further, by using the information obtained in the above for astronomical automatic tracking shooting as in Patent Documents 4 and 5, the shooting lens (shooting optical system) 101 of the camera (shooting apparatus) 10 can be used regardless of the elevation angle of the camera body 11. It is possible to accurately determine the shooting direction in which the camera is facing, and to accurately calculate tracking data for celestial automatic tracking shooting.

  In the above embodiment, when the acquired imaging elevation angle exceeds 45 ° or −45 °, the biaxial geomagnetic sensor is switched from the XY plane to the XZ plane. However, the boundary value of the elevation angle h for switching the biaxial geomagnetic sensor is not limited to 45 ° or −45 °, and is appropriately set within a range of 30 ° to 60 ° or within a range of −30 ° to −60 °, for example. be able to.

  As described above, the embodiment in which the azimuth measuring method and the azimuth measuring apparatus using the three-axis electronic compass of the present invention are applied to the camera 10 has been described. However, the present invention includes other devices such as an astronomical telescope, a telescope, binoculars, and a camera. Applicable to devices such as mobile phones.

DESCRIPTION OF SYMBOLS 10 Camera 11 Camera body 13 Image sensor 15 Image sensor drive unit 21 CPU (switching means, direction acquisition means, rotation angle acquisition means, deviation angle calculation means, correction means, calculation control means)
23 LCD monitor (display means)
25 Memory card 28 Release switch 29 Setting switch 101 Shooting lens (shooting optical system)
110 3-axis electronic compass 120 Acceleration sensor (tilt sensor)
130 GPS unit (latitude and longitude information input means)
GSX X direction gyro sensor GSY Y direction gyro sensor GSR Rotation detection gyro sensor LO Shooting optical axis (specific direction, Y direction)

  The present invention is an electronic azimuth meter that can always accurately measure the azimuth in a specific direction of the photographic device (eg, the azimuth of the photographic optical axis of the photographic optical system of the photographic device) regardless of the orientation of the mounted photographing device (digital camera). The present invention relates to an azimuth measuring method and an azimuth measuring apparatus using (for example, a three-axis electronic compass).

  In recent years, a three-axis electronic compass has been developed as an electronic azimuth meter equipped with three-axis geomagnetic sensors orthogonal to each other. A device such as a mobile phone equipped with this type of three-axis electronic compass detects a geomagnetism by a three-axis geomagnetic sensor orthogonal to each other, and further detects the direction of gravity (tilt in the front-rear direction of the device). The direction in which the user is facing is calculated (Patent Document 3).

  However, a conventional three-axis electronic compass such as Patent Document 3 is applied to astronomical auto-tracking photographing such as Patent Documents 4 and 5, and the photographing device is directed in the zenith direction (or a direction close thereto). If an attempt is made to measure the shooting direction in which the photographing optical system of the apparatus is directed, a completely different direction may be measured as the direction in which the photographing optical system of the photographing apparatus is directed. An object of the present invention is to provide an azimuth measuring method and an azimuth measuring device capable of accurately measuring the azimuth in a specific direction based on such problem awareness.

  An azimuth measuring method of the present invention is an azimuth measuring method for measuring an azimuth in a specific direction with respect to the electronic azimuth meter using an electronic azimuth meter including a plurality of magnetic detectors and an inclination detector. And selecting an output value of a plurality of magnetism output values obtained from the plurality of magnetic detectors according to the acquired elevation angle, and obtaining an elevation angle formed by the horizontal plane from the tilt detector. Obtaining a geomagnetic azimuth from the selected output value, obtaining a rotation angle around the specific direction from the tilt detector, and based on the acquired elevation angle, geomagnetic azimuth, and rotation angle. And a step of correcting an error in the azimuth in the specific direction caused by changing the selection of the output value.

  The azimuth measuring method of the present invention changes the selected output value when the acquired elevation angle exceeds a predetermined boundary value in the range of 30 ° to 60 ° or in the range of −30 ° to −60 °. There may be further stages.

  The plurality of magnetic detectors may obtain output values related to three magnetisms corresponding to three directions orthogonal to each other, and two output values may be selected from the three output values.

  An azimuth measuring apparatus of the present invention is an azimuth measuring apparatus that has an electronic azimuth meter including a plurality of magnetic detectors and an inclination detector, and measures the azimuth in a specific direction with respect to the electronic azimuth meter. And an elevation angle formed by the horizontal plane from the inclination detector, and a selection means for selecting a part of the output values related to the plurality of magnetisms obtained from the plurality of magnetic detectors according to the acquired elevation angle Azimuth obtaining means for obtaining a geomagnetic azimuth from the selected output value, rotation angle obtaining means for obtaining a rotation angle around the specific direction from the tilt detector, the obtained elevation angle, geomagnetic azimuth, And correction means for correcting an error in the azimuth in the specific direction caused by the change in the selection of the output value by the selection means based on the rotation angle.

  The azimuth measuring apparatus of the present invention changes the output value to be selected when the acquired elevation angle exceeds a predetermined boundary value in the range of 30 ° to 60 ° or in the range of −30 ° to −60 °. You may have a change means further.

  From the plurality of magnetic detectors, output values related to three magnetisms corresponding to three directions orthogonal to each other can be obtained, and the selection means may select two output values among the three output values. .

  The azimuth measuring device may be mounted on a digital camera, and the specific direction may be set in parallel with the shooting optical axis of the shooting lens of the mounted digital camera.

  The azimuth measuring apparatus may include display means for displaying the measured azimuth of the photographing optical axis of the photographing lens.

  ADVANTAGE OF THE INVENTION According to this invention, the azimuth | direction measuring method and azimuth | direction measuring apparatus which can measure the azimuth | direction of a specific direction correctly are obtained.

  FIG. 1 shows a posture of a camera (azimuth measuring device) 10 equipped with a three-axis electronic compass (multiple magnetic detectors, electronic azimuth meter) 110 having three orthogonal axes, and three axes (local magnetic sensors of the three-axis electronic compass 110). It is the perspective view which showed the relationship with the maximum sensitivity direction axis | shaft). The three-axis electronic compass 110 is configured to select and calculate two output values of three output values (voltage values, etc.) detected by the various magnetic sensors and detect the direction of the geomagnetism (geomagnetic line). is there. The three axes of the three-axis electronic compass 110 are defined by an X axis, a Y axis, and a Z axis that are orthogonal to each other. In FIG. 1, one of the three-axis geomagnetic sensors of the three-axis electronic compass 110 is coincident with the Y axis set in parallel with the photographing optical axis LO of the photographing lens 101 of the camera 10. The other two-axis geomagnetic sensors coincide with the X axis set in parallel with the bottom surface of the camera 10 and the Z axis set in the vertical direction of the camera 10.

  Since the geomagnetism is a vector having a magnitude and direction, the greater the magnitude of the geomagnetic vector projected onto the XY plane, that is, the closer the angle (absolute value) between the XY plane and the horizontal plane is to 0 °, the geomagnetic vector. The direction (magnetic north (S pole) direction, orientation) can be calculated accurately and accurately. On the other hand, when the camera 10 is tilted upward or downward (tilted), the angle (absolute value) formed by the XY plane and the geomagnetism increases, and the geomagnetic vector projected on the XY plane decreases, resulting in accuracy. Since the magnitude of the projected geomagnetic vector is 0 at a maximum angle of 90 °, the accuracy and accuracy of the three-axis electronic compass 110 are extremely lowered. Therefore, when the camera 10 is tilted upward or downward from an angle of 45 ° formed by the XY plane and the geomagnetism, it is better to measure the geomagnetism in the XZ plane rather than the XY plane. Therefore, in the present embodiment, an acceleration sensor (three-axis acceleration sensor, tilt sensor, tilt detector) 120 (FIG. 7) is mounted on the camera 10, and the camera attitude, for example, the shooting optical axis LO of the shooting lens 101 is measured by the acceleration sensor 120. The elevation angle (including elevation angle and depression angle) formed by the horizontal plane is measured, and two output values are selected from the three output values output by the triaxial geomagnetic sensor with the absolute value 45 ° of the elevation angle h as a boundary. Switch. That is, when the geomagnetic vector is horizontal, the output value is switched to the output value of the geomagnetic sensor constituting the XY plane or the XZ plane where the absolute value of the elevation angle h is less than 45 °. Hereinafter, switching a specific 2-axis output value is referred to as “switching to a 2-axis geomagnetic sensor”, and calculating using a specific 2-axis output value is referred to as “measuring with a 2-axis geomagnetic sensor”.

  The camera body 11 is equipped with a CPU (switching means, azimuth acquisition means, rotation angle acquisition means, deviation angle calculation means, correction means, calculation control means, selection means, change means) 21 that controls the functions of the entire camera. Yes. The CPU 21 controls the drive of the image sensor 13, processes the image signal captured by the image sensor 13, displays it on the LCD monitor 23, and writes it in the memory card 25. (The CPU 21 detects signals detected by the X-direction gyro sensor GSX, the Y-direction gyro sensor GSY, and the rotation detection gyro sensor GSR in order to detect the shake applied to the camera when the image sensor driving unit 15 is used as the image stabilization unit. Is entered.

10 Camera (azimuth measuring device)
11 Camera body 13 Image sensor 15 Image sensor drive unit 21 CPU (switching means, azimuth acquisition means, rotation angle acquisition means, deviation angle calculation means, correction means, calculation control means, selection means, change means)
23 LCD monitor (display means)
25 Memory card 28 Release switch 29 Setting switch 101 Shooting lens (shooting optical system)
110 3-axis electronic compass (multiple magnetic detectors, electronic compass)
120 Acceleration sensor (tilt sensor, tilt detector)
130 GPS unit (latitude and longitude information input means)
GSX X direction gyro sensor GSY Y direction gyro sensor GSR Rotation detection gyro sensor LO Shooting optical axis (specific direction, Y direction)

Claims (10)

A three-axis electronic compass having an orthogonal three-axis geomagnetic sensor and selecting and using two of three output values of each axis obtained from the sensor, and an inclination sensor for detecting the inclination of the three-axis electronic compass Using an orientation measurement method for measuring an orientation in a specific direction with respect to a three-axis electronic compass,
Acquiring an elevation angle formed by the specific direction and the horizontal plane from the tilt sensor, and switching two output values to be selected from among the three output values obtained from the three-axis electronic compass according to the acquired elevation angle;
Obtaining a geomagnetic orientation from the two switched output values;
Obtaining a rotation angle around the specific direction from the tilt sensor;
Calculating a deviation angle of the azimuth of the specific direction generated by the switching based on the acquired elevation angle, geomagnetic azimuth, and rotation angle;
Correcting the direction of the specific direction based on the calculated deviation angle;
A direction measuring method using a three-axis electronic compass characterized by comprising: In the azimuth measuring method using the three-axis electronic compass according to claim 1,
When the acquired elevation angle exceeded a predetermined boundary value in the range of 30 ° to 60 ° or in the range of −30 ° to −60 °, a three-axis electronic compass that switches between the two output values to be selected was used. Orientation measurement method. In the direction measuring method using the three-axis electronic compass according to claim 1 or 2,
The step of calculating the deviation angle includes an orientation using a three-axis electronic compass including a step of calculating the deviation angle Δη by the following equation 3 where the elevation angle is h, the rotation angle is θ, and the deviation angle is Δη. Measuring method.
Δη = ArcTan (Tan (θ) / sin (h)) Equation 3 In the azimuth measuring method using the three-axis electronic compass according to claim 3,
In the step of correcting the azimuth in the specific direction, when the azimuth obtained from the three-axis electronic compass after the switching is A and the actual azimuth in the specific direction after the switching is A ′, the actual azimuth A ′ is An azimuth measuring method using a three-axis electronic compass including the step of calculating by Equation 4.
A '= A + Δη (4) A three-axis electronic compass having an orthogonal three-axis geomagnetic sensor and selecting and using two of three output values of each axis obtained from the sensor, and an inclination sensor for detecting the inclination of the three-axis electronic compass Having an orientation measuring device for measuring the orientation of a specific direction with respect to the three-axis electronic compass,
Switching means for acquiring an elevation angle formed by the specific direction and a horizontal plane from the tilt sensor, and switching two output values to be selected among the three output values obtained from the three-axis electronic compass according to the acquired elevation angle; ,
Direction acquisition means for acquiring the direction of geomagnetism from the two output values switched;
Rotation angle acquisition means for acquiring a rotation angle around the specific direction from the tilt sensor;
A deviation angle calculating means for calculating a deviation angle of the azimuth in the specific direction generated by the switching by the switching means based on the acquired elevation angle, geomagnetic azimuth, and rotation angle;
Correction means for correcting the azimuth in the specific direction based on the deviation angle calculated by the deviation angle calculation means;
An azimuth measuring apparatus using a three-axis electronic compass. In the azimuth measuring apparatus using the three-axis electronic compass according to claim 5,
The switching means is configured to switch the two selected output values when the acquired elevation angle exceeds a predetermined boundary value in the range of 30 ° to 60 ° or in the range of −30 ° to −60 °. Orientation measurement device using an electronic compass. In the direction measuring device using the three-axis electronic compass according to claim 5 or 6,
The azimuth measuring apparatus using a three-axis electronic compass that calculates the deviation angle Δη by the following equation 3 when the elevation angle is h, the rotation angle is θ, and the deviation angle is Δη.
Δη = ArcTan (Tan (θ) / sin (h)) Equation 3 In the direction measuring device using the three-axis electronic compass according to claim 7,
The correction means calculates the actual azimuth A ′ by the following equation 4 when the azimuth obtained from the three-axis electronic compass after the switching is A and the actual azimuth in the specific direction after the switching is A ′. Orientation measurement device using an axial electronic compass.
A '= A + Δη (4) In the azimuth measuring apparatus using the three-axis electronic compass according to any one of claims 5 to 8,
The azimuth measuring apparatus is mounted on a digital camera, and the azimuth measuring apparatus uses a three-axis electronic compass in which the specific direction is set parallel to the photographing optical axis of the photographing lens of the mounted digital camera. In the azimuth measuring apparatus using the three-axis electronic compass according to claim 9,
The azimuth measuring apparatus is an azimuth measuring apparatus using a three-axis electronic compass provided with display means for displaying the measured azimuth of the photographing optical axis of the photographing lens.

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