JPH0749960B2 - Geomagnetic azimuth measuring device - Google Patents

Description

Description: [Industrial field of application] The present invention relates to an azimuth measuring device by geomagnetism used in ships, automobiles and the like.

[Prior Art] A magnetic compass is well known as an orientation measuring device using geomagnetism. The magnetic compass is inexpensive and has a simple structure, but when installed and used on a moving body such as a ship,
It is necessary to always keep the compass horizontal with respect to the inclination of the moving body, and a gimbal mechanism is well known as a device for that purpose.

As a azimuth measuring device capable of detecting the measurement azimuth by an electric signal, a device using a flux gate magnetic sensor is known. FIG. 5 shows an example of the flux gate magnetic sensor. An excitation coil 21 is wound around the ring-shaped magnetic core 20 in an interlinking manner, and an excitation current is supplied from an excitation AC power supply 22. The two detection coils 23 and 24 are orthogonal to each other and are wound on the outer side of the whole magnetic core 20, and an electric signal indicating two azimuth direction components of the intensity of the earth's magnetism according to the direction of the flux gate magnetic sensor. You can get the output.

An example of an azimuth measuring device using such a flux gate magnetic sensor is disclosed in Japanese Patent Laid-Open Nos. 57-76410 and 57-12231.
It is disclosed in 0. The azimuth detecting device disclosed in Japanese Laid-Open Patent Publication No. 57-76410 aims to obtain the azimuth from magnetic north detected by the flux gate magnetic sensor as a digital signal. When this azimuth detecting device is installed on a moving body such as a ship, a gimbal device for keeping the above-mentioned flux gate magnetic sensor always horizontal is required in order to prevent an error caused by the inclination of the moving body.

Further, in the invention of JP-A-57-76410, when a moving body such as a car equipped with a magnetic azimuth meter using a flux gate magnetic sensor passes through an iron bridge or a tunnel, for example, it is caused by a local disturbance of the geomagnetism. A countermeasure against an error in the measurement direction is disclosed. To prevent this error,
When the geomagnetic turbulence occurs and exceeds a preset constant limit, the measurement direction in the steady state immediately before the geomagnetic turbulence occurs is held by a latch circuit, and thereby the passing environment for the moving body. This prevents a sudden change in the display value on the azimuth display section due to a sudden change in. Although this prior example does not have means equivalent to a gimbal device, when the moving body tilts and the measurement azimuth changes, the azimuth value immediately before tilting is held, thereby causing the tilt. It was necessary to avoid the effect of error.

[Problems to be Solved by the Invention] When a conventional azimuth measuring device using geomagnetism is installed and used on a moving body such as a ship, it must be held horizontally in order to prevent a measurement error caused by the inclination of the moving body. I won't. The gimbal device, which is known as a device for holding horizontally, is a structure in which the movable part is generally made of a metal material, so there is friction and inertia that cannot be ignored in the movable part.
Due to these influences, when the moving body shakes or vibrates due to acceleration, the gimbal device cannot immediately respond and a measurement error may occur. In addition, the mechanical section is expensive because it requires high-precision machining, and its maintenance requires a great deal of cost.

Furthermore, since it is difficult to downsize the gimbal device when downsizing the azimuth measuring device, it is impossible to downsize the entire device. In the magnetic azimuth meter according to JP-A-57-122320, although the gimbal device is not used, the azimuth is not measured when the moving body is tilted, and only the azimuth value immediately before tilting is held. When the tilt of the moving body continues for a long time, the displayed azimuth value actually causes an error.

[Means for Solving the Problems] The azimuth measuring device by geomagnetism according to the present invention includes the following.

The moving body (3) fixed to a moving body (30) moving on the earth and having a known geomagnetic vector (G) at a predetermined position (3)
The first coil (2) for detecting the value of the component in the direction of the heading horizontal axis (x) of 0), of the orthogonal horizontal axis (y) orthogonal to the heading horizontal axis (x) of the geomagnetic vector (G). The second coil (3) and the third coil (6) for detecting the value of the component in the direction, and the value of the component in the direction of the vertical axis (z) of the moving body (30) of the geomagnetic vector (G) are detected. A fourth coil (7), a first excitation means (4, 9) and a third coil (6) for applying an alternating magnetic field of a predetermined frequency to the first coil (2) and the second coil (3) ) And second excitation means (5, 10) for applying another AC magnetic field of the predetermined frequency to the fourth coil (7)
Which constitutes a coil portion of a flux gate type magnetometer together with the first, second, third and fourth coils, and an excitation oscillator for supplying an AC signal of the predetermined frequency to the first and second excitation means. (10A), provided for each of the first coil (2), the second coil (3), the third coil (6) and the fourth coil (7), and output signals of the respective coils Of the geomagnetic vector (G) from the second harmonic signal of the output signal of the first coil (2). A first synchronous rectification circuit (13X) that outputs a first detection signal value (EX) representing the value of the component in the direction of the heading horizontal axis (x), and a first output signal of the second coil (3) From the second harmonic signal, the orthogonal horizontal axis (y) of the geomagnetic vector (G) A second synchronous rectification circuit (13Yx) that outputs a second detection signal value (EY) that represents the value of the component of the direction, and a geomagnetic vector (G) from the second harmonic signal of the output signal of the third coil (6). ), A third synchronous rectification circuit (13Yz) for outputting a third detection signal value (EYz) representing the value of the component in the orthogonal horizontal axis (y) direction, a second detection signal value (EY) and a third detection signal value (EY). First excitation means (4, 9) and second excitation means (5, 10) for the same horizontal axis component of the geomagnetic vector based on the detection signal value (EYz) of
The level compensating circuit (12) that detects a variation value of the detection output due to the difference in the characteristics of (1) and outputs a level compensation signal based on it, from the second harmonic signal of the output signal of the fourth coil (7) to the geomagnetic vector ( G) a fourth detection signal value (EZ) representing the value of the component in the direction of the vertical axis (z), the signal value being controlled by the level compensation signal of the level compensation circuit (12); 4 synchronous rectification circuit (13Z), and the first detection signal value (EX) and the second detection signal value (E
Y), fourth detection signal value (EZ), geomagnetic vector (G)
Of the moving body (30), the azimuth (A) of the rotation axis (x ') of the tilt, and the tilt angle around the rotation axis (x') based on the value of (B) is a computing device that performs a computation to determine the magnetic north axis (X) of the geomagnetic vector (G) based on the value of the geomagnetic vector (G) and the known dip angle (I) at the predetermined position. the value of the horizontal component in the ( _o ) direction (G
X _o ), the value of the horizontal component (GY) of the geomagnetic vector (G) in the direction of the horizontal axis (Y _o ) orthogonal to the magnetic north axis (X _o ).
_o ) and a value (GZ _o ) of the vertical component of the geomagnetic vector (G) in the direction of the vertical axis (Z _o ), respectively, and the first detection signal value (EX), The second detection signal value (EY), the fourth detection signal value (EZ), the value of the horizontal component in the magnetic north direction of the geomagnetic vector (G) obtained by the first calculation (GX _o ), the magnetic north direction axis The value of the horizontal component (GY _o ) of the geomagnetic vector (G) in the direction of the horizontal axis (Y _o ) orthogonal to (X _o ), and the vertical direction of the geomagnetic vector (G) in the direction of the vertical axis (Z _o ). Based on each of the component values (GZ _o ), the heading direction (θ) of the moving body (30), the direction (A) of the rotation axis (x ′) of inclination, and the direction around the rotation axis (x ′) Three-dimensional Cartesian coordinates (x, y,
z), (i) magnetic north axis (X _o ), (ii) magnetic north axis (X _o )
_a second operation for obtaining a change from a three-dimensional Cartesian coordinate having a horizontal axis (Y _o ) orthogonal to ( _o ) and (iii) a vertical axis (Z _o ) by a coordinate transformation operation of the three-dimensional Cartesian coordinate; An arithmetic unit (14) for performing calculation to obtain the values of the course direction (θ), the direction (A) of the rotation axis (x ′) of inclination, and the inclination angle (B).

[Operation] As described above, the values of the respective components in the heading direction horizontal axis x, orthogonal horizontal axis y, and vertical axis z direction of the geomagnetic vector G detected by the three-dimensional magnetic sensor are set to the geomagnetic vector G.
Based on the dip angle I, the heading azimuth θ, the azimuth A of the rotation axis x ′ of inclination, and the inclination angle B around the rotation axis x ′ representing the position / orientation of the moving body, and magnetic north as a reference By calculating the difference from the three-dimensional Cartesian coordinates, the heading azimuth θ, the azimuth A of the rotation axis x ′ of inclination, and the inclination angle B around the rotation axis x ′ are calculated.

[Embodiment] FIG. 2 shows a three-dimensional flux gate magnetic sensor used in the present invention. Two flux gate magnetic sensors
1A and 1B are fixed to the moving body as follows. The flux gate magnetic sensor 1A has its ring-shaped magnetic core 9 fixed horizontally on the moving body 30 shown in FIG. 3A with its X axis aligned with the bow direction and its Y axis horizontally between both sides of the ship. The flux gate magnetic sensor 1B has its ring-shaped magnetic core 10
It is perpendicular to the moving body 30 shown in FIG. A and its Y axis is aligned with the Y axis of the flux gate 1A, and the Z axis is aligned with the vertical direction of the moving body 30 and fixed. Ring-shaped magnetic cores 9 and 1 of the flux gate magnetic sensors 1A and 1B, respectively.
The excitation coils 4 and 5 are wound around 0, respectively. Y
An X-axis coil 2 wound around the outside of the magnetic core 9 in a plane orthogonal to the axis and elongated in the X-axis direction, and Y
The Y-axis coil 3, which is wound outside the magnetic core 10 in a plane orthogonal to the axis and is elongated in the Y-axis direction, is wound around the outer periphery of the ring-shaped magnetic core 9 orthogonal to each other. .
Then, the Z-axis coil 7 elongated in the Z direction is wound on the outside of the magnetic core 10 in the plane orthogonal to the Y-axis, and is wound outside the magnetic core 10 in the plane orthogonal to the X-axis. The second Y-axis coil 6, which is elongated in the axial direction, has a magnetic core 9
Are wound around the outer periphery of the magnetic core 10 arranged at right angles to each other.

FIG. 1 shows the configuration of the circuit of the present invention. The two exciting coils 4 and 5 are connected to an exciting oscillator 10A for forming an alternating magnetic field in the magnetic cores 9 and 10, and an alternating current of, for example, 10 KHz is applied. The output of the coil 2 of the flux gate magnetic sensor 1A for detecting the horizontal component of the earth's magnetism becomes the input of the synchronous rectification signal 13X via the band filter 11.
The output of the coil 3 passes through the band filter 11 and the synchronous rectification circuit 13
It becomes the input of Y _x . The output of the coil 6 of the flux gate magnetic sensor 1B that detects the vertical component of the earth's magnetism is a band filter.
Similarly, it becomes an input of the synchronous rectification circuit 13Y _z via 11, and the output of the coil 7 becomes an input of the synchronous rectification circuit 13Z via the band filter 11. The outputs of the synchronous rectification circuits 13Y _x and 13Y _z are input to the level compensation circuit 12. The output of the level compensation circuit 12 is input to the synchronous rectification circuit 13Z. The synchronous rectification circuit 13X, 13Y _x , 13
The detection signal values EX, EY, EZ that are the outputs of Z are input to the arithmetic unit 14 as data. Display devices 15θ, 15A and 15B Display the calculation results of the calculation device 14.

Next, the operation of this embodiment will be described. Since the operating principle of the flux gate magnetic sensor is well known, it will be omitted. The coil 2 is a coil for detecting the horizontal component X component of the geomagnetism, and the coils 3 and 6 are coils for detecting the horizontal component Y component. Further, the coil 7 detects a component in the vertical direction.

The exciting current of the oscillation frequency fo of the oscillator 10A causes distortion due to geomagnetism in the flux gate magnetic sensor according to a known principle. In order to detect this amount of distortion, each band filter 11 separates the second harmonic 2f _o . The second harmonic is a synchronous rectifier circuit 13X, 13 for extracting only half wave of AC waveform.
Input to Y _x , 13Y _z , 13Z. The level compensating circuit 12 compares the outputs of the coils 3 and 6 for detecting the Y components of the two magnetic cores 9 and 10 to detect the fluctuation of the detection output caused by the difference in the size and the characteristics of the two magnetic cores, and detects the detected signal. The synchronous rectification circuit 13Z is controlled by so that the detection sensitivities in the three directions of X, Y and Z become uniform. Fig. 4 shows synchronous rectification circuit 13X, 13
Y _x, a diagram showing the relationship between the output signal is the detection signal value EX of 13Z, EY, the level and heading of EZ, "0 '" represents magnetic north.

The detection signal values EX, EY, EZ are input to the arithmetic unit 14 and the arithmetic operations described below are performed. The data used in the calculation are defined as follows.

Each of these data is a moving object existing at a predetermined position on the earth.
It is in 30.

X _o : Magnetic north horizontal axis of geomagnetic vector G at a certain position of the moving body 30 Y _o : Horizontal magnetic horizontal axis orthogonal to the magnetic north horizontal axis X _o at the above position, Z _o : Earth at the same position Vertical axis above, GX _o : horizontal component of the geomagnetic vector G at the same position in the magnetic north direction, GY _o : horizontal component of the geomagnetic vector G at the same position in the direction of the orthogonal horizontal axis Y _o , GZ _o : component of the geomagnetic vector G in the direction of the vertical axis Z _o at the same position, x: heading direction axis of the moving body 30 (the heading is substantially equal to the heading direction) y: moving body 30 Orthogonal horizontal axis that is orthogonal to the direction axis x of the vehicle z: Vertical axis of the moving body 30 (for example, the axis of the mast in the case where the mast stands upright) A: Normal position of the moving body 30 (vertical axis of the moving body) The orientation of the horizontal axis of rotation x'when rotating and tilting from a position where z is vertical) If the hull of the ongoing direction shakes is,
Pitching (vertical shaking) and rolling (horizontal shaking) occur. These may occur independently, but in general, both often occur simultaneously. If only rolling occurs, the hull rotates about the bow axis x,
If only pitching occurs, the hull rotates about the orthogonal horizontal axis y. When both occur, the hull is neither a synthetic motion of the rotational movement around the heading azimuth axis x and the horizontal axis y orthogonal to the two axes, for example, the horizontal axis x'in FIG. 3A.
It is thought to rotate around.

B: A rotation angle about the rotation axis x ′, which is measured with the vertical axis Z _o as a reference.

θ: Moving body from that direction with reference to the magnetic north axis X _o
Angle formed by 30 course directions C: The value of the difference between the course direction θ value and the direction A value is defined as C (C = θ−A). The detection signal values EX, EY, EZ are the geomagnetic vector G. vertical axis Z _o direction component GZ _o, in the direction of the horizontal axis Y _o perpendicular to the horizontal component of the direction of magnetic north axis X _o GX _o and magnetic north axis X _o of three directions of the horizontal components GY _o of Each value of the geomagnetic component is detected by the three-dimensional magnetic sensor as the value of the geomagnetic component in the direction of the bow azimuth axis x, the value of the component in the direction of the horizontal axis y, and the value of the component in the direction of the vertical value z. is there.

On the other hand, the dip angle, which is the angle between the horizontal plane and the geomagnetic vector G, is I
Then, each component value GX _o , GY _o , GZ _o of the geomagnetic vector G is expressed by the equation (1).

The component values GX _o , GY _o , and GZ _o in equation (1) correspond to the detection values of the three-dimensional magnetic sensor when the bow faces magnetic north and has no inclination at all. If the magnitude of the geomagnetic vector G is set to 1, equation (1) is expressed by the following equation (1A) (Since the magnitude of the geomagnetic vector G is always a constant value at the same point, the calculation is simplified. To "1").

In the azimuth measuring device of the present invention, the moving body 30 is provided with a three-dimensional coordinate system including the magnetic north axis X _o , the horizontal axis Y _o , and the vertical axis Z _o.
To obtain the heading azimuth θ, the azimuth A of the rotation axis x ′ of the hull inclination, and the inclination angle B by coordinate conversion into a three-dimensional coordinate consisting of the bow azimuth entry axis x, the horizontal axis y, and the vertical axis z representing the state of Is.

An example of calculation of coordinate conversion will be described below.

Generally, when the Cartesian coordinates represented by the three axes of P, Q, and R are rotated and converted into new Cartesian coordinates represented by the three axes of Xn, Yn, and Zn, first, the R axis is used as the rotation axis and the angle A is used. By rotating the new two axes to the P'axis and the Q'axis, and then rotating the new axis by the angle B using the P'axis as the rotation axis.
A method is known in which the axes are Q'-axis and Zn-axis, and further, the Zn-axis is rotated by an angle C and the two new axes are Xn-axis and Yn-axis to perform coordinate conversion. New three-dimensional Cartesian coordinates Xn, Yn, Zn coordinate values Xv, Yv, Zv
It is known that the following relations (2), (3), and (4) are established by Euler's formula between and the coordinate values q, q, r of the old three-dimensional Cartesian coordinates P, Q, R. ing.

_{Xv = p (c o sA ·} c o sC-sinA · c o sB · sinC) -q (cosA · sinC + sinA · cosB · cosC) + r (sinA · sinB)
…… (2) Yv = p (sinA ・ cosC ＋ cosA ・ cosB ・ sinC) −q (sinA ・ sinC−cosA ・ cosB ・ cosC) −r (cosA ・ sinB)
(3) Zv = psinB sinC + qsinB cosC + rcosB (4) In the above conversion formulas (2), (3), and (4), the coordinate values p of the coordinate axes P, Q, and R of the old three-dimensional Cartesian coordinate system Substituting the respective component values shown in equation (1A) for q, r, they are represented as shown in equation (1B).

As shown in FIG. 3A showing the plane of the moving body 30 and FIG. 3B as seen from the stern of the moving body 30 in the direction of the x ′ axis, Body 30
If the rotation axis x'when tilted is the direction of A degrees measured clockwise from the magnetic north direction axis X _o , and its inclination angle is B degrees, the moving body 30 rotates B degrees about the rotation axis x '. It can be expressed as having a posture. Further, assuming that the heading horizontal axis x is in the direction of θ degrees measured clockwise from the magnetic north direction axis X _o , the moving body 30 rotates θ degrees from the magnetic north direction axis X _o about the vertical axis z of the moving body 30. It can be said that it is in the position.

Substituting the above-mentioned A degree, B degree and the value of C defined above into the Euler's formula to transform the coordinate axes, the direction of the bow azimuth axis x and the direction of the horizontal axis y of the geomagnetism detected by the three-dimensional magnetic sensor. The detection signal values EX, EY, EZ of the components in each direction of the vertical axis z correspond to the coordinate values Xv, Yv, Zv of the new three-dimensional Cartesian coordinates, and are respectively the following equations (5), (6), (7). Is represented by

Ex = cos [cosA ・ cos (θ−A) −sinA ・ cosB ・ sin (θ−A)] ＋ sinI ・ sinA ・ sinB …… (5) EY ＝ cosI [sinA ・ cos (θ−A) ＋ cosA ・ cosB ・sin (θ-A)] −sinI ・ cosA ・ sinB …… (6) EZ ＝ cosI ・ sinB ・ sin (θ−A) ＋ sinI ・ cosB ……
(7) The dip angle I is a value determined by the position on the earth and can be obtained from the dip diagram. Equation (5) above,
The values of A, B and θ can be obtained by calculating the equations (6) and (7) as a three-dimensional simultaneous equation by the arithmetic unit 14 in FIG. In the arithmetic unit 14, first, the detection signal values EX, EY, EZ which are analog signals are converted into digital data by the built-in A / D converter, and then the digital data are calculated. The result of the calculation is displayed on the digital displays 15θ, 15A, 15B as the heading azimuth θ, the azimuth A of the rotation axis x ′ of the inclination, and the inclination angle B, respectively.

EFFECTS OF THE INVENTION The azimuth measuring apparatus of the present invention can know the azimuth, tilt direction, and tilt angle of the moving body from the horizontal and vertical components of the geomagnetism detected by the flux gate magnetic sensor fixed to the moving body. No gimbal device is required to keep the sensor horizontal. Furthermore, as described above, it is possible to measure the tilt direction and tilt angle as well as the azimuth, so the posture of the moving body is controlled using these measured values, and when the hull is tilted by a measuring device such as a sonar. However, it can be effectively used in various fields, such that a transmitting / receiving element such as a sonar can be controlled to always face in a predetermined direction. Further, the magnetic sensor is not limited to the flux gate magnetic sensor, but may be configured by combining with any magnetic sensor such as a semiconductor magnetic sensor. In such a case, an extremely small azimuth measuring device can be realized. .

[Brief description of drawings]

FIG. 1 is a block diagram of an azimuth measuring apparatus of the present invention, FIG. 2 is a configuration diagram of a three-dimensional flux gate magnetic sensor used in the azimuth measuring apparatus of the present invention, and FIG. 3A is an azimuth measuring apparatus of the present invention. Fig. 3B, a plan view of a moving body installed with
Is a rear view of the moving body on which the azimuth measuring apparatus of the present invention is installed, as viewed from substantially behind, FIG. 4 is a view showing the output of a three-dimensional flux gate magnetic sensor, and FIG. 5 is used for a conventional magnetic azimuth measuring apparatus. It is a figure which shows the flex gate magnetic sensor currently performed.

Claims (1)

[Claims] 1. A fixed component of a moving body (30) moving on the earth, of a component of a known geomagnetic vector (G) at a predetermined position in a direction of a heading direction horizontal axis (x) of the moving body (30). A first coil (2) for detecting a value, a second coil (3) for detecting a value of a component of a geomagnetic vector (G) in a direction of an orthogonal horizontal axis (y) orthogonal to a horizontal axis (x) of a heading.
And a third coil (6), and a fourth coil (7) for detecting the value of the component of the geomagnetic vector (G) in the direction of the vertical axis (z) of the moving body (30), the first coil (6) 2) and the second coil (3), the first excitation means (4, 9) for giving an alternating magnetic field of a predetermined frequency, the third coil (6) and the fourth coil (7) are Second excitation means (5,10) for applying the alternating magnetic field of
Which constitutes a coil portion of a flux gate type magnetometer together with the first, second, third and fourth coils, and an excitation oscillator for supplying an AC signal of the predetermined frequency to the first and second excitation means. (10A), provided for each of the first coil (2), the second coil (3), the third coil (6) and the fourth coil (7), and output signals of the respective coils Of the geomagnetic vector (G) from the second harmonic signal of the output signal of the first coil (2). A first synchronous rectification circuit (13X) that outputs a first detection signal value (EX) representing the value of the component in the direction of the heading horizontal axis (x), and a first output signal of the second coil (3) From the second harmonic signal, the orthogonal horizontal axis (y) of the geomagnetic vector (G) A second synchronous rectification circuit (13Yx) that outputs a second detection signal value (EY) that represents the value of the component of the direction, and a geomagnetic vector (G) from the second harmonic signal of the output signal of the third coil (6). ), A third synchronous rectification circuit (13Yz) for outputting a third detection signal value (EYz) representing the value of the component in the orthogonal horizontal axis (y) direction, a second detection signal value (EY) and a third detection signal value (EY). First excitation means (4, 9) and second excitation means (5, 10) for the same horizontal axis component of the geomagnetic vector based on the detection signal value (EYz) of
The level compensating circuit (12) that detects a variation value of the detection output due to the difference in the characteristics of (1) and outputs a level compensation signal based on it, from the second harmonic signal of the output signal of the fourth coil (7) to the geomagnetic vector ( G) a fourth detection signal value (EZ) representing the value of the component in the direction of the vertical axis (z), the signal value being controlled by the level compensation signal of the level compensation circuit (12); 4 synchronous rectification circuit (13Z), and the first detection signal value (EX) and the second detection signal value (E
Y), fourth detection signal value (EZ), geomagnetic vector (G)
Of the moving body (30), the azimuth (A) of the rotation axis (x ') of the tilt, and the tilt angle around the rotation axis (x') based on the value of (B) is a computing device that performs a computation to determine the magnetic north axis (X) of the geomagnetic vector (G) based on the value of the geomagnetic vector (G) and the known dip angle (I) at the predetermined position. the value of the horizontal component in the ( _o ) direction (G
X _o ), the value of the horizontal component (GY) of the geomagnetic vector (G) in the direction of the horizontal axis (Y _o ) orthogonal to the magnetic north axis (X _o ).
_o ) and a value (GZ _o ) of the vertical component of the geomagnetic vector (G) in the direction of the vertical axis (Z _o ), respectively, and the first detection signal value (EX), The second detection signal value (EY), the fourth detection signal value (EZ), the value of the horizontal component in the magnetic north direction of the geomagnetic vector (G) obtained by the first calculation (GX _o ), the magnetic north direction axis The value of the horizontal component (GY _o ) of the geomagnetic vector (G) in the direction of the horizontal axis (Y _o ) orthogonal to (X _o ), and the vertical direction of the geomagnetic vector (G) in the direction of the vertical axis (Z _o ). Based on each of the component values (GZ _o ), the heading direction (θ) of the moving body (30), the direction (A) of the rotation axis (x ′) of inclination, and the direction around the rotation axis (x ′) Three-dimensional Cartesian coordinates (x, y,
z), (i) magnetic north axis (X _o ), (ii) magnetic north axis (X _o )
_a second operation for obtaining a change from a three-dimensional Cartesian coordinate having a horizontal axis (Y _o ) orthogonal to ( _o ) and (iii) a vertical axis (Z _o ) by a coordinate transformation operation of the three-dimensional Cartesian coordinate; An azimuth measuring device by geomagnetism, comprising: a calculation device (14) for performing calculation to obtain the values of the heading azimuth (θ), the azimuth (A) of the rotation axis (x ') of inclination, and the inclination angle (B).