JP2006226810A - Azimuth measuring instrument - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an azimuth measuring instrument for performing calibration while suppressing the effect of an internal magnetic field by a simple operation and detecting an azimuth angle with high accuracy. <P>SOLUTION: When slightly turning this azimuth measuring instrument, a magnetic detection means detects at least three points P, Q and R as points on a circular detection path C2. A perpendicular bisector M of a line PQ passing through coordinates P and Q is found while finding a perpendicular bisector N of a line QR passing through coordinates Q and R. An intersection point of them is found as the center point G of the detection path C2. Assuming that the distance between the center point G and an original point O is L, the x and y components of the distance L can be used as x-axial and y-axial offset compensation values. By removing the respective compensation values component-by-component from magnetism data detected by the detection means, calibrated magnetism data can be obtained, making it possible to find a highly accurate direction angle θ from the magnetism data. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an azimuth measuring apparatus mounted on a portable terminal or the like, and more particularly to an azimuth measuring apparatus that can detect an azimuth angle with high accuracy by simple calibration.

  An azimuth measuring device (electronic compass) mounted on a cellular phone or the like detects a geomagnetism using a three-axis magnetic sensor and calculates an azimuth angle at a measurement point.

  However, electronic components for generating a magnetic field such as a speaker are mounted together in the mobile phone. Since the magnetic field as described above acts as noise or offset with respect to the geomagnetism, there is a problem that a large error is likely to be included in the azimuth angle calculated from the geomagnetism detected in such an environment.

As a prior art for reducing the influence of noise and offset caused by an external magnetic field other than the geomagnetism as described above, for example, the following Patent Document 1 exists.
JP 2004-12416 A

  In Patent Document 1, the azimuth measuring device is rotated 180 degrees in the same plane, and the offset is obtained by subtracting the output value of the magnetic sensor at the rotation start position and the output value of the magnetic sensor at the position rotated 180 degrees. It is what you want.

  However, even in the invention described in Patent Document 1, it is necessary to rotate the azimuth measuring device itself by 180 degrees or more in order to perform calibration reliably, which is complicated in use.

  In particular, if there is a shaft runout during rotation, an error indicating that calibration is not possible is displayed, and it is necessary to repeat the calibration operation many times, causing an excessive burden on the user. .

  The present invention is intended to solve the above-described conventional problems, and is capable of performing calibration for suppressing the influence of an internal magnetic field with a simple operation and capable of detecting an azimuth angle with high accuracy. The purpose is to provide.

  The present invention relates to a magnetic detection means capable of detecting geomagnetism generated in a direction along at least two axes orthogonal to the origin, and an arc shape or an elliptical shape formed by three or more magnetic data detected by the magnetic detection means. A correction calculation means for calculating an offset correction value for converting the detected locus into a reference locus centered on the origin, and removing the offset correction value from the magnetic data. An azimuth calculating means for calculating the corrected azimuth angle and a control means for controlling the operation of each means are provided.

In the present invention, the offset compensation values xg _{av. And} yg _{av. For} calibration can be obtained by a simple method of obtaining the intersection of at least two vertical bisectors. Moreover, theoretically, the offset compensation values xg _{av. And} yg _av. Can be obtained by slightly rotating (within 90 °) an electronic device equipped with the bearing measuring device. That is, since the calibration can be performed only by slightly rotating the electronic device, it is possible to reduce the burden on the operator when measuring the azimuth angle.

  For example, the magnetic detection unit continuously acquires the magnetic data at a predetermined sampling period, the correction calculation unit continuously calculates the offset correction value, and the azimuth calculation unit continuously The corrected azimuth angle is calculated.

  Alternatively, the magnetic detection means acquires the magnetic data continuously at a predetermined sampling period, and when the magnetic data changes, the correction calculation means calculates an offset correction value, and the azimuth calculation means The corrected azimuth angle is calculated.

  In the above, the correction calculation means includes a first perpendicular bisector for a straight line connecting any two points among the three or more points of magnetic data, and two other points different from the two arbitrary points. Obtaining a second vertical bisector with respect to a straight line connecting them, and setting an intersection of the first vertical bisector and a second vertical bisector as a center point of the reference trajectory Those characterized by the above are preferred.

  Further, a plurality of arbitrary two points are extracted from a plurality of magnetic data, a plurality of vertical bisectors are set for each straight line connecting the two points, and a plurality of the plurality of vertical bisectors intersect. It is preferable that the average coordinate of the center point is obtained by averaging the coordinates of the intersection points.

The correction calculation means substitutes the function F (x, y) = 0 when the coordinates corresponding to the magnetic data forming the detection locus are substituted into the function F (x, y) shown in the following equation 3. coefficients satisfy a, b, along with determining the x _g and y _g, the x _g determined this time as an offset compensation value in the x axis direction, and which the y _g offset compensation value in the y-axis direction is preferable.

In this case, among the distances between the center point and the origin, the average of the x-axis component offset compensation values is xg _av. , The average of the y-axis component offset compensation values is y g _av. When the magnetic data output from the means is (X, Y), the azimuth angle θ in the azimuth calculating means can be calculated by the following equation (4).

However, Hx and Hy are Hx = k1 · (X−xg _av. ) And Hy = k2 · (Y−yg _av. ), And k1 and k2 are arbitrary constants.

  In the present invention, calibration that is not affected by an internal magnetic field can be performed by a simple operation of slightly rotating an electronic device equipped with an azimuth measuring device within 90 °. Therefore, it is possible to calculate a highly accurate azimuth without imposing an excessive burden on the operator.

  FIG. 1 is a plan view showing a two-dimensional relationship between an azimuth angle and an electronic device equipped with an azimuth measuring device (three-axis electronic compass), FIG. 2 is a block diagram showing the configuration of the azimuth measuring device, and FIG. Fig. 4 is a side view of an electronic device that two-dimensionally shows a state inclined by a pitch angle α around the x axis, and Fig. 5 is a roll around the y axis. It is a bottom view of the electronic device which shows the state rotated only the angle β two-dimensionally.

  FIG. 1 shows a mobile phone as a representative example of the electronic apparatus 1. This electronic device 1 is equipped with an orientation measuring device 2.

  As shown in FIG. 2, the azimuth measuring device 2 includes a magnetic detection unit 3, a correction calculation unit 9, an azimuth calculation unit 10, and a control unit 11.

  The magnetic detection means 3 has three magnetic sensors 4a, 4b, 4c, a switching means 6, an amplification means 7, and an A / D conversion means 8. The magnetic sensors 4a, 4b, 4c are arranged in directions orthogonal to each other, the width direction of the electronic device 1 is the x ′ axis, the longitudinal direction of the electronic device 1 is the y ′ axis, and the thickness direction of the electronic device 1 is Is the z′-axis, the magnetic sensor 4a is in the x′-axis direction, the magnetic sensor 4b is in the y′-axis direction, and the magnetic sensor 4c is the amount of magnetic field (geomagnetism) generated in the z′-axis direction. Detect as. Therefore, in the azimuth measuring device 2, the x'y'z 'orthogonal coordinate system is formed by the three magnetic sensors 4a, 4b, 4c, and the three-axis direction component of the geomagnetic vector H generated around the earth is always obtained. Measuring.

  The outputs of the magnetic sensors 4a, 4b, 4c are connected to the switching means 6. The control means 11 drives the switching means 6 in order to switch the outputs (analog quantities) of the magnetic sensors 4 a, 4 b, 4 c in order and guide them to the amplification means 7. The amplifying means 7 amplifies each output of the magnetic sensors 4a, 4b, 4c with a predetermined gain, and outputs the amplified output to an A / D converting means 8 provided at the subsequent stage. The A / D conversion means 8 generates magnetic data X, Y, and Z by converting the amplified outputs of the magnetic sensors 4a, 4b, and 4c into digital signals at a predetermined sampling frequency.

  As the magnetic sensors 4a, 4b, 4c constituting the magnetic detection means, for example, an MR (Magneto Resistive) sensor, a GIG (Granular in Gap) sensor, a Hall element, a fluxgate type magnetic sensor (Japanese Patent Laid-Open No. 9-43322). And Japanese Patent Laid-Open No. 11-118892).

  In the following description, a horizontal plane (x′y ′ plane) in which the x ′ axis and the y ′ axis of the x′y′z ′ orthogonal coordinate system that changes according to the attitude of the electronic device 1 are parallel to the ground. (Horizontal plane)), and the z-axis perpendicular to both the x 'axis and the y axis' is perpendicular to the vertical direction (gravity direction). The coordinate system is used as a standard.

  Symbols Hx, Hy, and Hz indicate the magnitudes (magnetic field strengths) of the x-axis component, the y-axis component, and the z-axis component of the geomagnetic vector H detected by the three-axis magnetic sensor mounted on the electronic device 1. I mean. Reference numeral H ′ indicates a horizontal component when the geomagnetic vector H is projected onto the ground plane (xy plane) and indicates the direction of magnetic north.

  The azimuth angle θ shown in FIGS. 1 and 3 is an angle formed by the reference y ′ axis and magnetic north (the horizontal component H ′ of the geomagnetic vector). The azimuth angle θ ′ is an angle formed by the reference y ′ axis and true north, and is the angle that the azimuth measuring apparatus of the present invention finally seeks.

  Further, the symbol α shown in FIG. 4 indicates the y axis (or the ground plane (xy plane)) and the rotated y ′ axis (or x ′) when the electronic apparatus 1 is rotated around the x ′ axis (x axis). It means a posture angle (hereinafter referred to as a pitch angle) formed by y ′ plane. 5 indicates the x axis (or the ground plane (xy plane)) and the rotated x ′ axis (or x′y) when the electronic apparatus 1 is rotated about the y ′ axis (y axis). It means the posture angle (hereinafter referred to as roll angle) formed by the 'plane'.

  Here, the symbol η shown in FIG. 3 is an angle formed by the ground plane (xy plane) and the geomagnetic vector H that cuts through the ground plane, and means a dip angle (downward is a plus). However, the dip angle η is a value that varies depending on the location, and tends to increase as the latitude increases.

  The value of the dip angle η is stored, for example, in a memory means (not shown) corresponding to an arbitrary measurement position, via an artificial satellite that constructs a GPS (Global Positioning System) provided in the electronic device 1. While obtaining the current measurement position, it is possible to obtain it by reading the dip angle η corresponding to the current measurement position from the internal memory means. Alternatively, in the case where the electronic device 1 is a mobile phone, an area (current measurement position) where the mobile phone is used is determined from the position of the relay station connected during a call or mail, and through the relay station Data concerning the dip angle η can be obtained from the outside, and the azimuth measuring device 2 shown in FIG. 2 has a dip angle and declination obtaining means 20 for obtaining data concerning the dip angle η. In the present invention, as shown below, since the data of the dip angle η is not directly used, it is not always necessary to obtain the dip angle η.

  First, in the simplest case, that is, when the electronic apparatus 1 is placed at the center of the xyz orthogonal coordinate system and the pitch angle α and the roll angle β are both α = β = 0 °, detection of the azimuth angle θ with respect to magnetic north is detected. A method will be described. Since the pitch angle α and the roll angle β are both 0 °, the xyz orthogonal coordinate system and the x′y′z ′ orthogonal coordinate system are in agreement.

  At this time, each component of the x'y'z 'orthogonal coordinate system of the geomagnetic vector H detected by the azimuth measuring device is the same as each component of the xyz orthogonal coordinate system. Assuming that Hx, Hy, and Hz are respectively used, the components Hx, Hy, and Hz can be expressed as the following Expression 5 by using the azimuth angle θ and the dip angle η.

  As shown in FIGS. 1 and 3, the azimuth angle θ is an angle formed by the y ′ axis (in this case, coincident with the y axis) and the horizontal component H ′ of the geomagnetic vector. be able to.

  In this equation, the dip angle η is deleted, so it is possible to obtain the azimuth angle θ without knowing the dip angle η.

  As described above, when the pitch angle α and the roll angle β are both α = β = 0 °, that is, when the electronic apparatus 1 is placed parallel to the ground plane (xy plane), the detection is performed from the magnetic sensor 4a. The value Hx obtained by converting the magnetic data X (the magnetic field strength in the x′-axis direction) into a geomagnetic vector and the magnetic data Y (the magnetic field strength in the y′-axis direction) detected from the magnetic sensor 4b The azimuth angle θ can be obtained from the value Hy converted to a vector. Similarly, when the electronic device 1 is placed parallel to the yz plane, the azimuth angle θ can be obtained from the converted value Hy of the magnetic data Y and the converted value Hz of the magnetic data Z. In a state of being placed parallel to the zx plane, the azimuth angle θ can be obtained from the converted value Hx of the magnetic data Z and the converted value Hx of the magnetic data X. To generalize this point, when the electronic device 1 is on any plane, if at least two magnetic data can be acquired from the three magnetic sensors 4a, 4b, 4c, those The azimuth angle θ can be obtained from the converted value.

  By the way, components that generate a magnetic field such as magnets and coils are mounted inside the electronic device 1, and when the three magnetic sensors 4a, 4b, and 4c detect the internal magnetic fields generated by these components, It becomes difficult to obtain the correct azimuth angle θ.

  Therefore, calibration is required to minimize the influence of the internal magnetic field, and the method will be described below.

  FIG. 6 is a diagram for explaining a calibration method as an embodiment of the present invention.

  As described above, the magnetic detection means 3 always detects the magnetic data X, Y, Z at a predetermined sampling period.

First, a description will be given of an ideal case where the magnetic sensors 4a, 4b, 4c constituting the magnetic detection means 3 are not affected by an internal magnetic field such as a magnet or a coil. When the electronic device 1 is rotated around the z axis on the xy plane under such ideal conditions, the horizontal axis represents the converted value of the magnetic data X output through the magnetic sensor 4a, and A Lissajous waveform is obtained by using the magnetic data Y output through the magnetic sensor 4b and the converted value as the vertical axis. Then, an arc-shaped reference trajectory C1 having a predetermined radius r (r = (Hx ² + Hy ² ) ^1/2 ) centered on the origin O (0, 0) as shown by a one-dot chain line in FIG. 6 can be obtained. . Note that θ indicating the azimuth angle at this time is the above formula 6.

  Next, when the Lissajous waveform is obtained when the electronic device 1 is rotated around the z-axis on the xy plane in the same manner as described above under the influence of the internal magnetic field, a circle as indicated by a dotted line in FIG. 6 is obtained. Or arc-shaped detection locus C2.

  Comparing the reference trajectory C1 and the detection trajectory C2, it can be seen that the centers of the detection trajectories C2 are offset from the origin O by a distance L, although the radii of both the trajectories C1 and C2 are substantially the same. That is, the distance L indicates the magnitude of the error superimposed on the magnetic sensors 4a and 4b based on the internal magnetic field. Therefore, the electronic device 1 can be calibrated by obtaining the distance L and removing the distance L from the detection locus C2.

Therefore, although it is necessary to obtain the center coordinates of the detection locus C2, in the following, the coordinates of any three points on the arc-shaped detection locus C2 are P (x ₁ , y ₁ ), Q (x ₂ , A method for obtaining the center coordinates (xg, yg) of the center point G of the detection locus C2 from these three points will be described assuming that y ₂ ) and R (x ₃ , y ₃ ). FIG. 8 is a flowchart for calculating the offset compensation value.

  As shown in FIG. 8, in ST1, the electronic device 1 is installed on a horizontal plane with respect to the xy plane. At this time, the switching means 6, the amplifying means 7 and the A / D conversion means 8 are driven in the magnetism detecting means 3 by the command of the control means 11, and the magnetism corresponding to the magnetic sensors 4a, 4b and 4c is driven. Data (X, Y, Z) is output at a predetermined sampling period (ST2). Since the electronic device 1 is horizontal with respect to the xy plane, Z = 0 is omitted in the following description.

  In this state, when rotation about the Z-axis is given to the electronic device 1 on which the azimuth measuring device 2 is mounted (ST3), the magnetic data Z does not change or the amount of change is small, but the magnetic data X A large change occurs in Y and Y.

  In the azimuth measuring device 2, magnetic data (X, Y) output at a predetermined sampling period is continuously taken into the memory means 12 every predetermined amount of data (for example, every 10). Alternatively, when it is detected that a large change has occurred in two or more elements constituting the magnetic data (X, Y, Z), the magnetic data (X, Y) is received in response to an instruction from the control means 11. ) May be taken into the memory means 12.

  When the control means 11 determines that the quantity of magnetic data (X, Y) stored in the memory means 12 exceeds 2 (3 or more) (ST4), a method as shown in ST5 below. To calculate the offset compensation value. Therefore, in the case where magnetic data is continuously acquired, the offset compensation value is always calculated (however, in this case, since the electronic device 1 is not rotated, the output offset compensation value is always In the case where the magnetic data (X, Y) is acquired due to a large change, the offset compensation value is calculated only when there is a large change.

Here, the coordinates corresponding to the three magnetic data (X, Y, Z) stored in the memory means 12 are P (x ₁ , y ₁ ), Q (x ₂ , y ₂ ), R (x ₃ , Y ₃ ).

  In ST5, the correction calculation means 9 intersects perpendicularly with a straight line (PQ line) passing through arbitrary two coordinates P and Q as shown in FIG. 6 and bisects the two coordinates P and Q. Find the first vertical bisector M through p. It should be noted that the equation of a straight line representing the first vertical bisector M on the xy plane coordinates is given by Equation 7 below.

  Similarly, a second perpendicular bisector N passing through a point q that perpendicularly intersects a straight line (QR line) passing through arbitrary two coordinates Q and R and also bisects the two coordinates Q and R is defined as follows. It is obtained as a linear equation shown in the following equation (8).

  Therefore, by obtaining a solution of the first vertical bisector M (Equation 7) and the second vertical bisector N (Equation 8), the coordinates (xg) of the center point G of the detection locus C2 are obtained. , Yg). This point can be derived from the definition that two perpendicular bisectors of two or more straight lines passing through two points on the circumference intersect at one point, and the intersecting point (intersection point) indicates the center point of the circle. In addition, in order to derive the center point (center coordinates), the center angle of the detection locus C2 may be 90 ° or less, and thus it is necessary to rotate the electronic device 1 on which the orientation measuring device 2 is mounted 180 ° or more as in the past. Therefore, calibration can be performed easily.

Next, the control unit 11 causes the correction calculation unit 9 to repeat the contents of ST5 so as to obtain the coordinates (center coordinates) of the plurality of center points G, and average the average coordinates (xg _av ) of the center points. _., seek yg _av.). At this time, among the average coordinates Gav. Of the center point, xg _av. Is an offset compensation value in the x-axis direction, and yg _av. Is an offset compensation value in the y-axis direction. The offset compensation values xg _{av. And} yg _av. Are stored in the memory means 12.

Then, the offsets in the x-axis direction are respectively determined from the coordinates P (x ₁ , y ₁ ), Q (x ₂ , y ₂ ), and R (x ₃ , y ₃ ) of any three points on the arc-shaped detection locus C2. When the compensation value xg _{av. And} the offset compensation value yg _{av. In the} y-axis direction are removed, the detection trajectory C2 is converted into an arc-shaped reference trajectory C1 centered on the origin by eliminating the influence of the internal magnetic field, that is, calibration. can do.

Next, in the azimuth measuring apparatus 2, the azimuth angle is measured according to the operation of the operator. At this time, the correction calculation means 9 removes the offset compensation values (xg _av. , Yg _av. ) Stored in the memory means 12 from the magnetic data (X, Y) output from the magnetic detection means 3 _. The compensated magnetic data (X-xg _av. , Y-yg _av. ) Is obtained. Further, the correction calculation means 9 converts the compensated magnetic data (X-xg _av. , Y-yg _av. ) Into the components Hx and Hy of the geomagnetic vector H as shown in the following formula 9.

ただし、ｋ１，ｋ２は任意の定数（換算係数）である。

However, k1 and k2 are arbitrary constants (conversion coefficients).

  Then, the azimuth calculating means 10 calculates the compensated azimuth angle θ as the azimuth output of the azimuth measuring device 2 by substituting the converted values Hx and Hy into the above formula 6. As described above, it is possible to obtain a highly accurate azimuth angle θ which is not influenced by the internal magnetic field or has little effect.

  As another calibration method, a method using a nonlinear least square method and an elliptic equation can also be used.

  FIG. 7 is a diagram for explaining a calibration method according to another embodiment of the present invention.

  In this method, the detection locus (Lissajous waveform) E1 formed when the electronic device 1 is rotated about the z-axis on the xy plane is assumed to be an elliptical locus which is a kind of arcuate locus.

In other words, a function F (x, y) based on the elliptic equation shown in Equation 10 below is a coordinate corresponding to the magnetic data (X, Y) and a plurality of coordinates (ellipse locus) E1 forming the detection locus (elliptic locus) E1. The coefficients a, _xg and b satisfying the function F (x, y) = 0 when x ₁ , y ₁ ), (x ₂ , y ₂ ), (x ₃ , y ₃ ). , Y _g .

However, as shown in FIG. 7, one of the coefficients a and b indicates the major axis of the ellipse and the other indicates the minor axis, and the coefficients x _g and y _g indicate the center coordinates (center point) of the ellipse. Incidentally, the coefficients a, and a known value of the coefficient b, y _g when seeking x _g, also the coefficient b, and when determining the y _g do the coefficients a, a x _g as a known value.

As a solution of the nonlinear least square method, it is possible to use a method of forming an orthonormal matrix from a Jacobian matrix and converging the coefficients a, x _g or the coefficients b, y _g by the Gauss-Newton method.

Of the center coordinates (x _g , y _g ) obtained from such a method, the x _g represents the offset compensation value in the x-axis direction, and the y _g represents the offset compensation value in the y-axis direction. The offset compensation values x _g and y _g are stored in the memory means 12.

Further, the control unit 11 causes the correction calculation unit 9 to repeat these steps, thereby averaging the average coordinates Gav. (Xg _av. , Yg) of the center points obtained by averaging these from a plurality of center coordinates (x _g , y _g ) _{. av.} ) is preferred. At this time, among the average coordinates Gav. Of the center point, xg _av. Is an offset compensation value in the x-axis direction, and yg _av. Is an offset compensation value in the y-axis direction. The offset compensation values xg _{av. And} yg _av. Are stored in the memory means 12 as described above.

Therefore, the correction calculation means 9 uses the offset compensation values (xg _av. , Yg _av. ) Stored in the memory means 12 from the magnetic data (X, Y) output from the magnetic detection means 3 as described above _. Is obtained by obtaining the compensated magnetic data (X-xg _av. , Y-yg _av. ), And the detected locus E1 is converted into an elliptical reference locus E0 centered at the origin (0, 0). That is, it is possible to calibrate.

  Then, by using the equations 9 and 6 as described above, the compensated azimuth angle θ can be calculated as the azimuth output of the azimuth measuring apparatus 2.

  In the above embodiment, the case where the electronic device 1 is rotated about the z axis has been described. However, the present invention is not limited to this, and the electronic device 1 is rotated about the x axis or the y axis. In this case, calibration can be performed by using the same method as described above, and it is possible to obtain a highly accurate azimuth angle θ that is not affected by the internal magnetic field or has little effect.

A plan view two-dimensionally showing the relationship between an azimuth angle and an electronic device equipped with an azimuth measuring device; Block diagram showing the configuration of the bearing measuring device, Orientation analysis diagram to explain the principle of tilt correction three-dimensionally, A side view of an electronic device that two-dimensionally shows a state in which the pitch angle α is inclined about the x-axis; a bottom view of an electronic device that two-dimensionally shows a state rotated by a roll angle β around the y-axis; The figure for demonstrating the method of the calibration as embodiment in this invention, The figure for demonstrating the method of the calibration as other embodiment in this invention, A flowchart for calculating an offset compensation value;

Explanation of symbols

1 Electronic equipment 2 Direction measuring device (3-axis electronic compass)
3 Magnetic detecting means 4a, 4b, 4c Magnetic sensor 6 Switching means 7 Amplifying means 8 A / D converting means 9 Correction calculating means 10 Direction calculating means 11 Control means 12 Memory means 20 Depression and declination obtaining means C1 Arc-shaped reference locus C2 Arc-shaped detection trajectory E1 Elliptical reference trajectory E2 Elliptical detection trajectory H Geomagnetic vector H 'Horizontal component Hx of geomagnetic vector Hx conversion value of x-axis component of geomagnetic vector H Hy-converted value of y-axis component of geomagnetic vector H Hz Conversion value M of z-axis component of geomagnetic vector H First vertical bisector N Second vertical bisector x ′, y ′, z ′ Cartesian coordinate system (x′y fixed to electronic device) 'z' Cartesian coordinate system)
x, y, z Cartesian coordinate system (coordinate system fixed to the electronic device when the x′y ′ plane is the ground plane and the z ′ axis is the vertical direction)
xg _av. , yg _av. Average X, Y, Z of offset compensation values Magnetic data (magnetic sensor output)
α Actual pitch angle (posture angle) of electronic equipment
β Roll angle (Attitude angle)
η Depression angle θ Azimuth to magnetic north

Claims (7)

  From a magnetic detection means capable of detecting geomagnetism generated in a direction along at least two axes orthogonal to each other at the origin, and an arc-shaped or elliptical detection locus formed by three or more magnetic data detected by the magnetic detection means A correction calculation means for calculating an offset correction value for calculating the center point and converting the detected locus into a reference locus centered on the origin, and an orientation after correction after removing the offset correction value from the magnetic data An azimuth measuring apparatus comprising: an azimuth calculating means for calculating an angle; and a control means for controlling operations of the respective means.   The magnetic detection unit continuously acquires the magnetic data at a predetermined sampling period, the correction calculation unit continuously calculates the offset correction value, and the azimuth calculation unit continuously corrects the correction value. The azimuth measuring apparatus according to claim 1, wherein the azimuth angle is calculated.   The magnetic detection means continuously acquires the magnetic data at a predetermined sampling period, and when the magnetic data changes, the correction calculation means calculates an offset correction value, and the azimuth calculation means corrects it. The azimuth measuring apparatus according to claim 1, wherein a subsequent azimuth angle is calculated.   The correction calculation means connects a first perpendicular bisector of a straight line connecting any two points among the three or more points of magnetic data and another two points different from the two arbitrary points. A second vertical bisector with respect to the straight line is obtained, and an intersection of the first vertical bisector and the second vertical bisector is set as a center point of the reference trajectory. The direction measuring device according to any one of claims 1 to 3.   A number of arbitrary two points are extracted from a plurality of magnetic data, and a number of vertical bisectors are set for each straight line connecting the two points, and a plurality of intersections at which the plurality of vertical bisectors intersect are set. 5. The direction measuring apparatus according to claim 4, wherein an average coordinate is used as an average coordinate of the center point. The correction calculation means satisfies the function F (x, y) = 0 when the coordinates corresponding to the magnetic data forming the detection locus are substituted into the function F (x, y) expressed by the following formula 1. coefficients a, b, along with determining the x _g and y _g, the x _g determined this time as an offset compensation value in the x axis direction, and characterized in that said y _g and the offset compensation value in the y-axis direction The direction measuring device according to any one of claims 1 to 3.

Of the distance between the center point and the origin, the average of the offset compensation value of the x-axis component is xg _av. , The average of the offset compensation value of the y-axis component is yg _av. And is output from the magnetic detection means _. 7. The azimuth according to claim 1, wherein when the magnetic data is (X, Y), the azimuth angle θ in the azimuth calculation means is calculated by the following formula 2. Measuring device.

However, Hx and Hy are Hx = k1 · (X−xg _av. ) And Hy = k2 · (Y−yg _av. ), And k1 and k2 are arbitrary constants.

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