JPH07103766A - Azimuth measuring device - Google Patents

Abstract

PURPOSE:To provide an azimuth measuring device which can measure an accurate azimuth by automatically correcting magnetization when the magnetization occurs caused by the influence of a disturbance magnetic field. CONSTITUTION:Deviation of a detection value from a first window 26 enables influence of disturbance magnetic field to be detected. Stable data P1 before being affected by the disturbance magnetic field are detected by a second window 28. Further, stable data P2 after the influence of the disturbance magnetic field is eliminated is also detected by the second window 28. Assuming that the moving direction of a vehicle does not change before and after disturbance, the coordinates of a center O2 of an azimuth circle 24 after the disturbance are calculated from the above data P1 and P2 and the coordinates of a center O1 of the azimuth circle 20 before the turbulence, thus setting the azimuth circle 24 after magnetization.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a device for measuring the traveling direction of a moving body such as a vehicle based on the geomagnetism provided in the moving body. The present invention relates to an azimuth measuring device that can be corrected.

[0002]

2. Description of the Related Art In a navigation system mounted on a vehicle, it is necessary to obtain the traveling azimuth of the vehicle, and an azimuth measuring device using a magnetic sensor is used as a device for this purpose. This magnetic sensor is composed of a pair of magnetic detection elements arranged orthogonally to each other, and the azimuth measuring device calculates a geomagnetic vector based on the detected magnetic vector to determine the traveling azimuth of the vehicle.

The magnetic detection element constituting the magnetic sensor has a structure having directivity. When the external magnetic vector matches the direction of the magnetic detection element, its output becomes maximum, and when it is orthogonal, it is 0. Becomes Therefore, the direction and magnitude of the magnetism, that is, the magnetic vector can be determined by using two sensors at the same time to detect magnetisms orthogonal to each other. The magnetic sensor detects geomagnetism, and the traveling direction of the vehicle can be determined based on this direction.

On the coordinate plane having the output of each of the magnetic detection elements orthogonal to each other as coordinate axes, the direction of the vehicle changes, so that the tip position of the detected magnetic vector moves on the coordinate plane. The locus of this movement is a so-called azimuth circle. Ideally, the tip of the geomagnetic vector moves on one azimuth circle.

However, when a disturbance is generated by an external magnetic field, the output of the magnetic sensor deviates from the azimuth circle and it becomes impossible to determine the correct azimuth. Further, when the external magnetic field is very large, a magnetic field in the direction opposite to the external magnetic field is generated in the vehicle body, and so-called magnetization occurs in which the magnetic field remains even after the external magnetic field disappears. When this magnetization occurs, the residual magnetic field makes it impossible to accurately measure the earth's magnetism. This makes the azimuth measurement inaccurate and reduces the reliability of the navigation system.

Therefore, it is necessary to determine the magnetization and make a correction after the magnetization. Japanese Patent Application Laid-Open No. Hei 3 filed previously by the applicant
Japanese Patent No. 241481 discloses an apparatus for determining magnetization by using an annular window having a predetermined width along an azimuth circle and a window provided outside the annular window.

The apparatus determines that there is a magnetization due to continuous removal from the annular window for a predetermined time, and determines that there is disturbance due to removal from the outer window. Based on this determination, the passenger is notified that the magnetization correction is necessary.

[0008]

In the above-mentioned conventional apparatus, it is described that the warning for urging the magnetization correction is given, but it is not shown how the correction is executed thereafter. Even if the current azimuth is manually input, it is not always easy to know the current azimuth, and the manual input operation itself is troublesome during driving operation. That is, there is a problem that it is difficult for a passenger to make an appropriate correction even when receiving a warning.

In addition, in the case of automatically performing the correction, a method in which the azimuth after the disturbance is eliminated coincides with the azimuth measured immediately before the deviation from the annular window can be considered. However, in this case, the circular window is large,
There was a problem that the azimuth measured immediately before the departure may already be affected by the disturbance.

The present invention has been made to solve the above-mentioned problems, and in the case where magnetization occurs due to disturbance,
It is an object of the present invention to provide an azimuth measuring device capable of performing accurate magnetization correction without bothering passengers.

[0011]

In order to achieve the above-mentioned object, an azimuth measuring apparatus according to the present invention detects a magnetic vector by a magnetic sensor composed of a pair of magnetic detecting elements arranged orthogonal to each other, and A azimuth measuring device for measuring a geomagnetic azimuth based on a vector, comprising: a first window having an upper limit value and a lower limit value substantially equal to a detection upper limit output and a detection lower limit output of each of the magnetic detection elements; A second window that is set and determines the stability of the detected value of the magnetic vector; and storage means that stores the azimuth calculated based on the latest continuous predetermined number of detected magnetic vector values existing in the second window. A disturbance determining unit that determines that there is a disturbance when the detected value of the magnetic vector is outside the first window; Pre-disturb azimuth setting means for setting the azimuth stored in the storage means as the pre-disturb azimuth, and a predetermined number of continuous magnetic vectors for returning the magnetic vector to the first window and thereafter existing in the second window And a magnetization correction means for correcting the magnetization after the disturbance based on the detected value and the azimuth before the disturbance.

[0012]

The present invention has the above-mentioned configuration, and the disturbance is determined in the first window, and the measurement directions before and after the disturbance are calculated based on the detection data in the second window.
Assuming that the azimuth after the disturbance is equal to the azimuth before the disturbance, magnetization correction is performed by setting a new azimuth circle. The second window is a window for determining whether or not the detected magnetic vector is constant for a predetermined period of time. Therefore, accurate magnetization correction can be performed by excluding the detected value affected by the disturbance.

[0013]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows two magnetic detecting elements 10a and 10a.
A magnetic sensor 10 is shown with b arranged orthogonally.
The magnetic detection elements 10a and 10b detect the detection of the component in the direction of the magnetic sensor. Arrow 12 in FIG.
For the magnetic vector H indicated by
The element 10b detects the axial component Hx, and the element 10b detects the y-axis component Hy. That is, if the angle formed by the magnetic vector with respect to the x-axis is θ, the component of the magnetic vector detected by each of the elements 10a and 10b is Hx = H sin θ Hy = H cos θ, and conversely the components Hx and Hy in each direction. By detecting, the direction (θ) and magnitude (H) of the magnetic vector can be determined. This is the principle of the magnetic sensor.

FIG. 2 shows the magnetic sensing element 10 shown in FIG.
The Lissajous figure is drawn by the outputs Vx and Vy of a and 10b. In the case of a geomagnetic vector, its magnitude is almost constant, so the direction θ is 0 ° to 360 °.
When changed to, the outputs Vx and Vy of the magnetic detection element become sinusoidal waveforms 14 and 16, respectively. However, the phase is 90 °
Deviated. Therefore, as shown in FIG. 2, the Lissajous figure becomes a circle 18. This circle is the so-called azimuth circle 18
Therefore, the detection value of the magnetic sensor 10 exists on this azimuth circle 18. Then, if the position on the azimuth circle 18 is known, the azimuth θ can be known. That is, if the radius of the azimuth circle 18 is R, then θ that satisfies Vx = R sin θ Vy = R cos θ can be uniquely determined.

FIG. 3 illustrates the principle of the present invention. The outputs of the detection elements 10a and 10b of the magnetic sensor described above are represented on the Vx axis and the Vy axis, respectively. However, the output of the detection element is output both positively and negatively with 0 as the center, as described above. However, in order to perform A / D conversion, a constant value is added to the output and the azimuth circle is drawn in the positive area I am trying to do it. In the figure, the upper limit value of Vx is indicated by V _xm , the upper limit value of Vy is indicated by V _ym , and the lower limit values of both are 0.

As described above, when the geomagnetic field is detected by this magnetic sensor, the direction of the geomagnetic vector detected changes depending on the direction of the sensor, but its magnitude does not change. Further, the center of the azimuth circle is determined by changing the direction of the magnetic sensor and performing the measurement twice. Alternatively, if the azimuth to which the current geomagnetic sensor is facing is already known, the azimuth circle center can be determined by inputting this azimuth. In this way, the center O ₁ (V _xO1 ,
V _yO1 ) is determined and the orientation circle 20 is drawn. When the magnetic sensor is installed so that the detection direction of the magnetic detection element (the y-axis direction in FIG. 1) coincides with the traveling direction of the vehicle, the direction of the vehicle is represented by the angle between the geomagnetic vector and the Vy axis. In the case of FIG. 3, the geomagnetic vector P ₁ (V _xP1 ,
An angle θ ₁ formed between the V _yP1 ) and the Vy axis is the traveling direction of the vehicle. That is, (V _xP1 −V _xO1 ) = B sin θ ₁ (V _yP1 −V _yO1 ) = B cos θ ₁ where B = {(V _xP1 −V _xO1 ) ² + (V _yP1 −V _yO1 ) ² }
We will find θ ₁ that satisfies ^1/2 .

Normally, the detected geomagnetic vector does not deviate from the azimuth circle 20, but it may deviate by detecting a disturbance magnetic field other than the geomagnetic field. For example, when a vehicle passes a railroad crossing after passing a train, a magnetic field is formed by an electric current flowing through an overhead wire of a railway, and the magnetic sensor detects the magnetic field. In such a case, the values far exceed the upper limits of Vx and Vy described above. This is represented by curve 22 in the figure. A further problem is that the bearing circle does not return to its original position after such a large disturbance. This is because, when passing through the disturbance magnetic field described above, a reverse magnetic field is generated in the vehicle body of the vehicle so as to cancel the magnetic field, and the magnetic field remains even after passing through the disturbance magnetic field to cause magnetization.
That is, the magnetic sensor detects both the geomagnetism and the residual magnetic field, and the position of the azimuth circle is displaced by the residual magnetic field. In the figure, the azimuth circle 24 shows the azimuth circle after the disturbance has passed. Of course, since there is no element that changes in the geomagnetic vector, the size of the azimuth circle does not change. That is, the center of the azimuth circle simply moved from the point O ₁ to the point O ₂ .

However, if the magnetization is not corrected, the measured azimuth becomes inaccurate. In FIG. 4, when the azimuth circle 20 moves to the azimuth circle 24 due to the magnetization, even if the azimuth circle 20 shows the same azimuth θ ₁ even after originally magnetized, the magnetic vector P _N obtained by combining the geomagnetic vector and the magnetized vector. Since the azimuth is calculated based on, the azimuth obtained is θ ₂ .

Therefore, in the present apparatus, when the disturbance magnetic field is detected, the azimuth before the disturbance is determined based on the data not affected by the disturbance, and the azimuth at the time when the influence of the disturbance disappears is set to the azimuth before the disturbance. The position of the azimuth circle is corrected assuming that it is the azimuth. The disturbance magnetic field can be detected in the first window 2
6 is performed. The first window 26 displays the output Vx,
It has a square shape that is set slightly inside of the square created by the upper and lower limits of Vy. In the range of the first window 26, specifically, the lower limit values of Vx and Vy are V _x1 and V _y1 and the upper limit values are V _x2 and V _y2 . Then, when a magnetic field exceeding the measurable limit is detected, it is determined that the disturbance magnetic field is being received. When it is determined that the disturbance magnetic field is being received, the azimuth θ ₁ is calculated and stored based on the geomagnetic vector P ₁ (V _xP1 , V _yP1 ) before the disturbance. And it said the azimuth theta ₁ and the detection value after the disturbance _{(V xP2,} V yP2),
Determine the center O _{2 of the} azimuth circle. After this, the azimuth circle 24
The azimuth is measured based on. Here, it is necessary to determine whether or not the detected value is affected by the disturbance. For this reason, the second window 28 is provided in this device. That is, the detected value is within the predetermined time within the second window 2
If it exists within 8, it is considered that the measured azimuth is stable and is not affected by the disturbance. The above is the outline of the magnetization correction in this apparatus.

FIG. 5 shows the overall construction of the apparatus of this embodiment. The output V of the geomagnetic sensor 10 described above is applied to the main body 1.
x and Vy are input, the signal is A / D converted by the A / D converter 2, and then input to the microcomputer 3. Further, the signal T from the temperature sensor 4 is input to the main body 1, and this temperature signal is also A / D converted and input to the microcomputer 3. Microcomputer 3
A memory 5 is connected to and stores the center coordinates of the azimuth circle and the values of each window. Further, the microcomputer 3 calculates the traveling direction of the vehicle based on the output of the geomagnetic sensor 10, and the display 7 is displayed via the display driver 6.
To the azimuth signal. The power supply circuit 8 provided in the main body 1 is connected to the battery E to supply power to each circuit. In the figure, SW1 is an ignition switch of the vehicle.

The control of azimuth measurement of this apparatus will be described below in more detail with reference to the flowcharts shown in FIG. When the apparatus is activated, it is determined whether initial setting is necessary (S101). If the detected value when the device was used last time is stored, this is used and the initial setting is not performed. When the initial setting is necessary, the vehicle, that is, the magnetic sensor is turned to measure the maximum value and the minimum value of each of the detection values Vx and Vy (S102). Further, the azimuth circle is calculated from these detected values, the coordinates of the center O _{1 on} the Vx-Vy plane are calculated, and the initial setting is completed (S10).
3).

When the initial setting is not necessary or when the initial setting is completed, the temperature T is measured. This is to correct the output of the geomagnetic sensor, which has temperature dependence (S1).
04). Next, the outputs Vx and Vy of the geomagnetic sensor are measured (S105).

Based on these outputs, it is judged whether or not there is a disturbance magnetic field and whether or not magnetization has occurred. If magnetization has occurred, a magnetization warning is given and magnetization correction is started (S10).
6). This step S106 will be described in more detail later. If there is no magnetization, etc., the azimuth θ is calculated by the microcomputer 3 based on the output as it is (S107). When magnetization occurs and correction is necessary, the azimuth θ is calculated after the correction (S107). Then, this azimuth θ is displayed on the display 7 (S10
8). Thereafter, steps S104 to S108 are sequentially repeated at a predetermined cycle.

FIG. 7 shows a flow of disturbance and magnetization determination, and a flow of automatic magnetization correction. Step S
When the outputs Vx and Vy of the magnetic sensor are measured at 105, the distance B from the coordinates ( _VxO1 , _VyO1 ) of the center O ₁ of the azimuth circle 20 is calculated (S201). This distance B is compared with the radius R of the azimuth circle 20. Specifically, the azimuth circle 20
Along with the circular window 30 of width 2K ₁ R (3rd
Magnetic vector detected value (V
It is determined whether (x, Vy) exists (S202). Here, K ₁ is a predetermined coefficient of 0 or more and less than 1. Therefore, in the third window, the center is the point O ₁ and the outer radius is (1 + K ₁ ) R,
It has an annular shape with an inner radius (1-K ₁ ) R. The third window is suitable for detecting that the set azimuth circle does not match the current azimuth circle for some reason. When the detected value (Vx, Vy) does not exist in the third window 30, it is further determined whether the detected value exists in the first window 26 (S2).
03). If it is in the first window, the count C ₁ is 10
It is determined whether it is 0 or more (S204). This count C
₁ indicates the duration of the state in which the detected value is outside the third window 30 and inside the first window 26. if,
If the count C ₁ is 100 or more, a magnetization warning is given and prompts to redo the initial setting. After the count C ₁ is less than 100 or the magnetization warning is given in step S205, the count C ₁ is updated by adding 1 (S206). Further, 1 is input to the count C ₂ (S207). Count C ₂
Represents the elapsed time after the detected value returns to the third window 30.

The latest V when C ₁ = C ₂ = 0
x and Vy are regarded as output data (S208). this is,
This is based on the assumption that the data before leaving the third window is reliable data that is not affected by disturbance or the like. The latest Vx and Vy are stored in step S214 described later.

In step S202, the detected value is the third value.
If it is determined that it is within the window, it is further determined whether the coefficient C ₂ is 0 or exceeds 4 (S210).
When this condition is satisfied, C ₁ = C ₂ = 0 is input (S212, S213). Therefore, C ₁ = C ₂ = 0
In the case of, it can be seen that it indicates that there is no abnormal value in the output of the magnetic sensor. Detection values Vx, Vy in this case
Is stored (S214). This is step S20 described above.
It becomes the latest Vx, Vy data used in 8.

In step S210, C ₂ = 1 and
If it is determined to be 2 or 3, 1 is added to the existing C ₂ (S211), and the process proceeds to step S208. As described above, in step S210, C ₂ = 1, 2,
When it is determined to be 3, it means that the detected value once outside the third window has returned to the third window, and that the predetermined time has not elapsed since the return. In such a case, the current traveling direction is calculated using the latest reliable data, that is, the detection values Vx and Vy stored in step S214, until the detection value becomes stable.

From steps S208 and S214, the process proceeds to step S209. Here, stable data that is not affected by disturbance or the like is stored. This is because the N detected values which can be regarded as the same value are continuously detected, and these detected values are made stable data. The stable data collection will be described in detail with reference to FIG.

FIG. 8 is a flowchart showing step S209 in more detail. First, V _xP = 0 and V _yP
= 0 is determined (S301). V _xP and V _yP are reference values for stability determination, and the fact that they are 0 indicates that the data to be the target of stability determination has not been detected yet. On the contrary, if any of the reference values V _xP and V _yP is other than 0, it means that the reference value has already been set and data is stored. V _xP and V _yP are 0
If not, it is determined whether Vx and Vy detected in the current control cycle are within the width of 2K ₂ R centered on V _xP and V _yP , respectively (S302). The window used for this determination is the second window (reference numeral 2 in FIG. 3).
8). K ₂ is a coefficient of more than 0 and less than 1, so that the second window has coordinates of the reference value (V _xP ,
It can be seen that it has a rectangular shape with V _yP ) as the intersection of the diagonal lines. Then, if the detected value exists in the second window, the detected value is sequentially stored as Vx (n) and Vy (n) (S303). Here, n indicates the order of detection after the reference values V _xP and V _yP are determined. Then, when up to N pieces of data have been fetched, the oldest data is erased thereafter and the latest data is fetched.

When it is determined in step S302 that the detected value is outside the second window, V _xP = 0 and V _yP = 0.
Is input (S304).

Further, in step S301, V _xP = 0 and V x
_{When yP} = 0 is determined, if Vx (n) and Vy (n) are already stored, they are erased (S305). Further, the values detected this time are adopted as the reference values V _xP and V _yP (S306). Then, the process proceeds to step S303. As described above, the stable data determined by the second window is stored, and these data are used for the automatic one-sided magnetization correction described later.

Returning to FIG. 7, if it is determined in step S203 that the detected value is outside the first window, the routine proceeds to the automatic magnetization correction routine (S215, S216). The automatic magnetization correction function of this device determines the azimuth circle after magnetization by measuring one azimuth.

The automatic one-sided magnetization correction function will be described below with reference to FIGS. 9 and 10. FIG. 9 is a flowchart showing steps S215 and 216 in FIG. 7 in more detail. Further, FIG. 10 is a diagram in which the horizontal axis represents time and the vertical axis represents the detected value Vy. The reference numerals in FIG. 10 are the same as those in FIG.

FIG. 10 shows that the detected value, which was stable near V _yP1 , deviated from the first window due to the disturbance, and later again the first value was detected.
After returning to the window, the detected value V different from that before the disturbance
_{It shows} a stable course at _yP2 . According to the flow shown in FIG. 8 and the like, N detection values that can be regarded as continuous same values are stored. These data are present in the second window 28. When the detected value is disturbed due to the disturbance, B ₁₀ , B ₁₁ , and B ₁₂ and a value outside the second window 28 are detected. However, these detected values are not outside the first window. When this goes out of the first window, the automatic correction control is started. Here, the reason why the third window 30 is not used for the stability judgment of the data is that this window has an annular shape, and for example, A of FIG. 3 is used.
This is because, as can be seen from the part indicated by, the width may be extremely wide and may not be appropriate for stability determination. Referring to FIG. 10, the width of the third window 30 is wider than the width of the second window, and if this is used as it is, the detected values B ₁₀ and B ₁₁ are also taken in as stable data, and the influence of disturbance is affected. It may include the received data. For this reason, it is not suitable for the correction control of the present apparatus that uses the detected value before the disturbance, and therefore the stability determination is performed by the second window 28 in a smaller range in order to eliminate the influence of the disturbance as much as possible.

The control of the automatic magnetization correction will be described with reference to the flowchart of FIG. When a value outside the first window 26 is detected, it is determined whether the count C ₃ is 100 or more (S401). The count C ₃ counts the time required to execute the automatic magnetization correction. If the correction is not completed even if the predetermined time or more is required, the process proceeds to step S205 in FIG. 8 to notify the passenger of the abnormality. If the predetermined time has not elapsed yet, it is determined whether the detected value has returned to the first window (S40).
2). The first time is of course outside the first window, and Vx and Vy are measured again (S403). Next, 1 is added to the count C ₃ (S404). Then, the process returns to step S401. The steps S401 to S404 are repeated until the detected value returns to the first window 26. At this time, the count C ₃ increases each time it is repeated, and a predetermined time elapses unless it returns to the first window 26 for a long time.

When the detected value returns to the first window 26, the average values V _xP1 and V _{yP1 of} Vx (n) and Vy (n) stored in step S209 are calculated and stored (S405). These are the coordinates of the tip of the magnetic vector before the disturbance. The calculation of the average values V _xP1 and V _yP1 can be performed before this, but it is possible to reduce unnecessary calculation processing by actually calculating the average values. .

Next, again, it is determined whether the count C ₃ is 100 or more (S406). In this determination, it is determined that time has elapsed before detection after the disturbance and a predetermined time has passed since the disturbance determination was made.
Similar to 01, when a predetermined time has elapsed, the process proceeds to step S205. Vx, Vy when the predetermined time has not elapsed
Is measured. Then, the M detected values Vx (m) and Vy (m) which can be continuously regarded as the same value are sequentially stored (step S408). This step is processed in the flow shown in FIG. 8 similarly to step S209 in FIG. However, FIG.
The “n” in “1” is read as “m”, and after the number of data becomes M, the old data is not discarded and rewritten with new data. Then, it is determined whether the number of stored data has reached M (S409). If the number has not reached M, 1 is added to the count C ₃ (S410), and the process returns to step S406. Also, if the data has reached the M is stored Vx (m), each of the average value of _{Vy (m) V xP2, V} yP2 are calculated and stored (S41
1). These are the coordinates of the tip of the magnetic vector after the disturbance.

Before and after the disturbance obtained in steps S405 and S411, the azimuth circle after the disturbance is set based on the coordinates of the tip of the vector (S412). Specifically, it is as follows. It is assumed that the heading of the vehicle does not change while the disturbance magnetic field is generated, and therefore the measured heading does not change before and after the disturbance. That is, in FIG. 3, the angles formed by the Vy axis and the vectors P ₁ and P ₂ are equal to θ ₁ . Furthermore, since the geomagnetism is detected, the azimuth circles always have the same radius. From these two assumptions, if decision vector tip, it can be seen that it is possible to determine by the following formula center O ₂ of the coordinates of the orientation circle _{(V xO2, V yO 2)} .

[0040] _{V xO2 = V xP2 - (V} xP1 -V xO1) V yO2 = V yP2 - (V yP1 -V yO1) subsequent orientation determined by such new orientation ¥ 24 Motoma' in the are performed. Finally, the count C _{3 is set} to 0 (S413).

As described above, in the present apparatus, the apparatus determines that it is necessary to correct the output of the magnetic sensor due to the magnetization due to the disturbance magnetic field, and the correction operation is automatically performed.

[0042]

As described above, according to the present invention, it is determined by detecting the disturbance magnetic field that the magnetization is generated, and when the magnetization is generated, the correction is performed based on the detection values before and after the detection of the disturbance magnetic field. At this time, the passenger does not have to perform the initial settings again or perform any operation such as inputting the heading at present,
Magnetization correction is automatically performed.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of the principle of a magnetic sensor.

FIG. 2 is an explanatory diagram of a principle of a magnetic sensor, and particularly a diagram illustrating an azimuth circle.

FIG. 3 is an explanatory diagram of the principle of the azimuth measuring device, and is also an explanatory diagram of the principle of the present invention.

FIG. 4 is a diagram for explaining a magnetization phenomenon of the azimuth measuring device.

FIG. 5 is a diagram showing a configuration of a preferred embodiment of an azimuth measuring device according to the present invention.

FIG. 6 is a flowchart showing an outline of a control flow of this embodiment.

FIG. 7 is a control flow of the present embodiment, and is a flow chart of control particularly regarding magnetization determination.

FIG. 8 is a control flow of the present embodiment, and is a flow chart of control for storing stable data, particularly before disturbance magnetic field detection.

FIG. 9 is a control flow of the present embodiment, and is a flowchart of control relating to automatic magnetization correction in particular.

FIG. 10 is a diagram for explaining the automatic magnetization correction function of the present embodiment.

[Explanation of symbols]

 20 azimuth circle (before disturbance) 22 trajectory of magnetic vector tip at the time of detecting disturbance magnetism 24 azimuth circle (after disturbance) 26 first window 28 second window 30 third window

Claims (1)

[Claims] 1. An azimuth measuring device for detecting a magnetic vector by a magnetic sensor composed of a pair of magnetic detection elements arranged orthogonal to each other, and measuring a geomagnetic azimuth based on the magnetic vector, wherein a detection upper limit of each of the magnetic detection elements. A first window having an upper limit value and a lower limit value that are substantially equal to the output and the detection lower limit output; a second window that is set near the tip of the magnetic vector and that determines the stability of the detected value of the magnetic vector; Storage means for storing the azimuth calculated on the basis of the latest continuous predetermined magnetic vector detection values existing in, and a disturbance determined to have a disturbance when the detection value of the magnetic vector is outside the first window. When the disturbance is determined, the determination means and the pre-disturbance azimuth setting hand that sets the azimuth stored in the storage means as the pre-disturbance azimuth And a magnetization correction for correcting the magnetization after the disturbance based on a predetermined number of consecutive magnetic vector detection values existing in the second window and the disturbance front direction after the magnetic vector returns to the first window. And an azimuth measuring device having a means.