JP2011185865A - Magnetic field detector - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a magnetic field detector which enables computation of the rotation movement and angular velocity of a magnetic vector with relatively excellent accuracy, by using sensors of three axes for detecting magnetism such as terrestrial magnetism, and with fewer data samples. <P>SOLUTION: Based on detection outputs from three magnetic sensors for detecting the magnetic vector, the magnetic vector is determined as a coordinate point on spherical coordinates G. Data D1 among coordinate point data being computed are made reference coordinate point data, and a plurality of virtual circles passing through the reference coordinate point data D1 are set on the spherical coordinates G. A virtual line C25 of a circle out of the individual virtual circles, of which the error from coordinate point data D1, D2, D3, D4, ... is the least, is estimated to be a moving locus circle of the coordinate point data. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a magnetic field detection device that detects a magnetic vector with a magnetic sensor directed in each of three orthogonal directions, and relates to a magnetic field detection device that can know the rotational motion of a magnetic vector with a small number of data.

  A magnetic field detection device using a triaxial magnetic sensor that detects magnetic field strengths in three directions orthogonal to each other is used as a geomagnetic detection device that detects geomagnetism.

  The magnetic gyro described in Patent Document 1 has a three-axis magnetic sensor that detects geomagnetism arranged on three-axis orthogonal coordinates. When this magnetic gyroscope is rotated in a three-dimensional space, a difference vector between two different time points is obtained using output data of three axes, and the difference vector becomes smaller than a predetermined threshold value. It is determined whether or not one of the three axes is rotating as a center.

  The magnetic gyro described in Patent Document 1 can detect the rotation state when rotating around any of the three axes determined by the orientation of the magnetic sensor. When it is rotated about the rotation axis, the rotation axis cannot be recognized, and it cannot be specified in which rotation plane it is rotating. That is, the angular velocity when rotating around an arbitrary axis in the three-dimensional space cannot be detected with only one magnetic gyro described in Patent Document 1.

  Patent Document 2 discloses an attitude sensor mounted on an airplane or the like. This attitude sensor has a geomagnetic detection device, and is provided with a load weight and a force detection device that detects gravity acting on the load weight. When the attitude sensor is tilted with an airplane, etc., the inclination with respect to the direction of gravity is detected by the detection output of the force detection device, and the azimuth output obtained by the geomagnetism detection device is used as information on the inclination posture obtained by the force detection device. To correct.

  The posture sensor described in Patent Document 2 includes not only a geomagnetic detection device but also a load weight and a force detection device that detects gravity acting on the load weight. It is difficult to install in small equipment for the purpose.

  The three-axis attitude detection device described in Patent Document 3 detects the attitude of a target object, and is equipped with both a magnetic sensor capable of detecting in three directions and a gyro sensor capable of detecting in three directions. Has been. For this reason, it is not suitable for mounting on a portable small device or the like, and both the magnetic sensor and the gyro sensor are mounted.

JP 2008-224642 A JP-A-2-238336 JP 11-248456 A

  The present invention solves the above-described conventional problem, and can estimate a moving locus circle of a magnetic vector from a detection output from a sensor directed in three orthogonal directions, and can estimate a moving locus circle even with a small number of data. An object of the present invention is to provide a magnetic field detection device that can perform the above-described operation.

The present invention includes a magnetic detection unit in which the X direction, the Y direction, and the Z direction orthogonal to each other are determined as reference directions, and a calculation unit.
An X-axis sensor in which the absolute value of the detection output becomes a maximum value when the X direction is directed to the magnetic direction and the absolute value of the detection output when the Y direction is directed to the magnetic direction. Is equipped with a Y-axis sensor in which the maximum value is detected, and a Z-axis sensor in which the absolute value of the detection output is a maximum value when the Z direction is directed to the magnetic direction,
In the calculation unit, a magnetic vector obtained from a plurality of the detection outputs sampled intermittently is converted into coordinate point data on spherical coordinates, and includes one reference coordinate point data among the plurality of coordinate point data. A plurality of virtual circles positioned on the spherical coordinates are set, and a virtual circle having the smallest error from the plurality of coordinate point data is estimated as a movement locus circle of the coordinate point data.

  The magnetic field detection device of the present invention acquires a plurality of pieces of information of magnetic vectors specified by detection outputs of the X-axis sensor, the Y-axis sensor, and the Z-axis sensor as coordinate point data on spherical coordinates, and uses the coordinate point data. Thus, the movement locus circle of the magnetic vector can be obtained. Further, even when the relative rotation angle between the magnetic field detection device and the magnetic vector is narrow and the number of samples of the coordinate point data is small, the movement locus circle can be estimated with high accuracy.

In the present invention, a plurality of first virtual circles including the reference coordinate point data and having the same radius as the spherical coordinate are set on the spherical coordinate, and the error from the plurality of coordinate point data is the smallest. The first virtual circle is selected,
Next, a plurality of second virtual circles that include the reference coordinate point data, have an opening angle with the selected first virtual circle, and are located on the spherical coordinate and have different radii are set. The second virtual circle with the smallest error from a plurality of coordinate point data is estimated as the movement locus circle of the coordinate point data.

  For example, the plurality of first virtual circles are set with a certain angular interval around a reference center line passing through the center of the reference coordinate point data and the spherical coordinate. The plurality of second virtual circles are set with an opening angle of a certain angular interval from the selected first virtual circle.

  As described above, by setting a plurality of first virtual circles and a plurality of second virtual circles on the spherical coordinates, it is possible to estimate a locus circle close to the movement locus of the actual coordinate point data. .

  Alternatively, in the present invention, a plurality of virtual circles including the reference coordinate point data and having different radii may be set.

  The present invention can determine the angular velocity of the magnetic vector at that time from the opening angle of the two coordinate point data from the center of the moving locus circle and the time when the two coordinate point data are obtained. become.

  According to the present invention, the relative rotational motion of the magnetic vector can be estimated by using the detection output of the magnetic sensor directed in the orthogonal three-axis directions. In addition, it is possible to estimate the motion trajectory of the magnetic vector with high accuracy when the relative rotation angle of the magnetic vector is shallow and the number of data samples is at least.

The circuit block diagram of the magnetic field detection apparatus of embodiment of this invention, The block diagram explaining the function of the calculating part provided in the magnetic field detection apparatus shown in FIG. Explanatory drawing showing the processing operation of the data buffer, Explanatory drawing of the X-axis sensor, Y-axis sensor, and Z-axis sensor provided in the magnetic detection unit Explanatory diagram of 3D coordinates showing the detection principle of geomagnetic vector, Explanatory drawing which shows the calculation which estimates a movement locus circle, It is explanatory drawing which shows the calculation which estimates a movement locus | trajectory circle, VII arrow line view of FIG. It is explanatory drawing which shows the calculation which estimates a movement locus | trajectory circle, VIII arrow line view of FIG. Explanatory drawing which shows 2nd Embodiment of the calculation which estimates a movement locus | trajectory circle,

  A magnetic field detection device 1 according to an embodiment of the present invention shown in FIG. 1 is used as a geomagnetism detection device and has a magnetic detection unit 2. As shown in FIG. 4, in the magnetic detection unit 2, the X axis, the Y axis, and the Z axis, which are reference axes orthogonal to each other, are determined as fixed axes. The magnetic field detection device 1 is mounted on a portable device or the like, and the magnetic detection unit 2 can freely move in the space while maintaining the orthogonal relationship between the X axis, the Y axis, and the Z axis.

  As shown in FIG. 4, the X-axis sensor 3 is fixed along the X-axis, the Y-axis sensor 4 is fixed along the Y-axis, and the Z-axis sensor is fixed along the Z-axis. Has been. The X-axis sensor 3, the Y-axis sensor 4, and the Z-axis sensor 5 are all composed of GMR elements. The GMR element is composed of a pinned magnetic layer and a free magnetic layer made of a soft magnetic material such as a Ni—Co alloy or a Ni—Fe alloy, and a nonmagnetic material such as copper sandwiched between the pinned magnetic layer and the free magnetic layer. And a conductive layer. An antiferromagnetic layer is laminated under the pinned magnetic layer, and the magnetization of the pinned magnetic layer is pinned by antiferromagnetic coupling between the antiferromagnetic layer and the pinned magnetic layer.

  The X-axis sensor 3 detects a component of the geomagnetism facing in the X direction, and the magnetization direction of the pinned magnetic layer is fixed in the PX direction along the X axis. The direction of magnetization of the free magnetic layer responds to the direction of geomagnetism. When the magnetization direction of the free magnetic layer is parallel to the PX direction, the resistance value of the X-axis sensor 3 is minimized, and when the magnetization direction of the free magnetic layer is opposite to the PX direction, the resistance value of the X-axis sensor 3 is maximized. become. Further, when the magnetization direction of the free magnetic layer is orthogonal to the PX direction, the resistance value is an average value of the maximum value and the minimum value.

  In the magnetic field data detection unit 6 shown in FIG. 1, the X-axis sensor 3 and the fixed resistance are connected in series, and a voltage is applied to the series circuit of the X-axis sensor 3 and the fixed resistance. The voltage between the resistors is taken out as an X axis detection output. When a magnetic field directed in the X direction is not applied to the X-axis sensor 3, or when a magnetic field orthogonal to PX is applied, the X-axis detection output becomes a midpoint potential.

  When the entire magnetic detection unit 2 is tilted and the fixed direction PX of the magnetization of the fixed magnetic layer of the X-axis sensor 3 is set in the same direction as the geomagnetic vector V, the magnetic field component applied to the X-axis sensor 3 becomes a maximum value. The X-axis detection output at this time has a maximum value on the plus side with respect to the midpoint potential. Conversely, when the fixed direction PX of the magnetization of the fixed magnetic layer of the X-axis sensor 3 is directed opposite to the geomagnetic vector V, the reverse magnetic field component applied to the X-axis sensor 3 has a maximum value. At this time, the detected output of the X axis has a maximum value on the minus side with respect to the midpoint potential.

  Each of the Y-axis sensor 4 and the Z-axis sensor 5 is also connected to a fixed resistor in series, and a voltage is applied to the Y-axis sensor 4 or a series circuit of the Z-axis sensor 5 and the fixed resistor. Is taken out as a Y-axis or Z-axis detection output.

  When the fixed direction PY of the magnetization of the fixed magnetic layer of the Y-axis sensor 4 is set in the same direction as the geomagnetic vector V, the detected output of the Y-axis becomes a maximum value on the plus side with respect to the midpoint potential. When the fixed direction PY of the magnetization of the fixed magnetic layer of the Y-axis sensor 4 is directed opposite to the geomagnetic vector V, the detection output of the Y-axis becomes a negative maximum value with respect to the midpoint potential. Similarly, if the fixed direction PZ of the magnetization of the fixed magnetic layer of the Z-axis sensor 5 is set in the same direction as the geomagnetic vector V, the detection output of the Z-axis becomes a maximum value on the plus side with respect to the midpoint potential. When the fixed direction PZ of the magnetization of the fixed magnetic layer of the Z-axis sensor 5 is directed opposite to the geomagnetic vector V, the detection output of the Z-axis becomes a negative maximum value with respect to the midpoint potential.

  If the magnitude of the geomagnetic vector V is constant, the detection outputs from the X-axis sensor 3, the Y-axis sensor 4, and the Z-axis sensor 5 are all of the absolute value of the plus side maximum value and the minus side maximum value. The absolute value is the same.

  As the X-axis sensor 3, a positive detection output and a negative detection output are obtained depending on the direction of the geomagnetic vector, and the absolute value is the same between the maximum value of the positive detection output and the maximum value of the negative detection output. If it becomes, it can also be comprised with magnetic sensors other than a GMR element. For example, a Hall element or MR element that can detect only the positive magnetic field intensity along the X axis and a Hall element or MR element that can detect only the negative magnetic field intensity may be combined and used as the X axis sensor 3. Good. The same applies to the Y-axis sensor 4 and the Z-axis sensor 5.

  As shown in FIG. 1, the detection outputs of the X axis, the Y axis, and the Z axis detected by the magnetic field data detection unit 6 are given to the calculation unit 10. The arithmetic unit 10 includes an A / D converter, a CPU, a clock circuit, and the like. According to the measurement time of the clock circuit of the calculation unit 10, the detection outputs of the X axis, the Y axis, and the Z axis detected by the magnetic field data detection unit 6 are intermittently sampled in a short cycle and read out to the calculation unit 10. . Each detection output is converted into a digital value by the A / D conversion unit provided in the calculation unit.

  A memory 7 is connected to the CPU constituting the arithmetic unit 10. In the memory 7, software for arithmetic processing is programmed and stored. The arithmetic processing of the arithmetic unit 10 is executed by the software.

  As shown in FIG. 2, the arithmetic unit 10 performs a plurality of stages of arithmetic processing based on software. The X-axis detection output, the Y-axis detection output, and the Z-axis detection output converted into digital data are arithmetically processed by the main calculation unit 15, and the coordinates on the three-dimensional coordinates of XYZ shown in FIG. It is converted into point data D and stored in a data buffer (buffer memory) 11. The coordinate point data D sampled and calculated in a short cycle in synchronization with the clock circuit is supplied to the storage unit 11a of the data buffer 11 shown in FIG. Each time the coordinate point data D is given to the storage unit 11a, the coordinate point data D is sequentially sent from the storage unit 11a to 11m, and the oldest coordinate point data D stored in the final storage unit 11m is discarded. While the magnetic field detection device 1 is operating, the latest data is continuously read from the magnetic field data detection unit 6 at regular intervals, and the coordinate point data D after calculation is sequentially stored in the data buffer 11.

  As shown in FIG. 5, when the magnetic detection unit 2 is placed anywhere on the earth, the detection output xb is obtained from the X-axis sensor 3 of the magnetic detection unit 2, and the detection output yb is obtained from the Y-axis sensor 4. The detection output zb is obtained from the Z-axis sensor 5. In the main calculation unit 15 of the calculation unit 10 shown in FIG. 2, the coordinate point data D (xb, yb, zb) is calculated from the three-dimensional detection output. The coordinate point data D (xb, yb, zb) are obtained one after another for each sampling period, and are sequentially stored in the data buffer 11.

  The magnetic field detection device 1 needs to be calibrated immediately after the power is turned on. This calibration is performed by rotating a portable device or the like equipped with the magnetic field detection device 1 several times in an arbitrary direction. The main calculation unit 15 samples some of the coordinate point data D obtained one after another in the calibration. By obtaining at least three coordinate point data D, it is possible to specify a circle that matches the rotation locus of the coordinate point data D at that time. A plurality of circles are obtained, a center line passing through the center of each circle is obtained, and an intersection of these center lines is calculated. In the main calculation unit 15, the three-dimensional coordinates of XYZ shown in FIG. 5 are set on the software, and the intersection obtained as a result of the calibration becomes the reference origin O of the three-dimensional coordinates. It is corrected.

  When the reference origin O of the three-dimensional coordinates is corrected by the calibration, the coordinate point data D (xb, yb, zb) calculated from the subsequent detection output is a spherical surface centered on the reference origin O on the three-dimensional coordinates. Appears as a point on coordinates G. The radius R of the spherical coordinate G is proportional to the absolute value of the maximum value of the detection output obtained from the X-axis sensor 3, the Y-axis sensor 4, and the Z-axis sensor 5. The radius R of the spherical coordinate G differs depending on the measurement location at that time, and the radius R of the spherical coordinate G also changes depending on the magnitude of the detected absolute value of the geomagnetic vector V.

  FIG. 5 shows a state in which the Z axis set in the magnetic field detection device 1 is directed in the direction of gravity. A line connecting the coordinate point data D (xb, yb, zb) obtained from the detection output and the reference origin O of the three-dimensional coordinates is the geomagnetic vector V. When the magnetic field detector 1 is rotated about the Z axis (centered about the axis facing the direction of gravity), the coordinate point data D (xb, yb, zb) sampled one after another is centered on the Z axis and X -Move along a horizontal latitude line Ha parallel to the Y axis. If the calculation unit 10 recognizes that the direction of the reference axis Z is directed in the direction of gravity, the opening of a plurality of coordinate point data D centering on the intersection of the horizontal latitude line Ha and the Z axis is opened. The angular velocity can be obtained from the angle and the sampling time.

  However, when the mobile device or the like actually mounted with the magnetic field detection device 1 is rotated in an arbitrary direction in the three-dimensional space, the direction of the axis of the rotation trajectory is determined only from the coordinate point data D, It is impossible to recognize where the coordinates of the center of the rotation locus are. As a result, the angular velocity cannot be calculated.

  Therefore, in the calculation unit 10 shown in FIG. 2, by executing the following software, when the magnetic field detection device 1 is rotated around the axis in an arbitrary direction, what trajectory rotates in which direction. It is possible to calculate what is being done.

  As shown in FIG. 6, when the magnetic field detection device 1 rotates around an arbitrary axis other than the XYZ axes, coordinate point data D1, D2,. Dn appears. The coordinate point data D1 is the latest data, and becomes the old data dating back in the order of D2, D3, D4,... Dn−1, Dn. The latest coordinate point data D1 is stored in the storage unit 11a of the data buffer 11 shown in FIG. 3, and the coordinate point data D2, D3, D4,... Are stored in the storage units 11b, 11c,. The

  In the rotation plane calculation unit 12 of the calculation unit 10 shown in FIG. 2, any one of a plurality of coordinate point data D1, D2,..., Dn−1, Dn stored in the data buffer 11 is selected and the reference coordinates are selected. Point data. For example, the latest coordinate point data D1 is set as the reference coordinate point data. Then, as shown in FIG. 6, a reference center line L0 passing through the reference coordinate point data D1 and the reference origin O of the spherical coordinate G is obtained. Since the position of the reference coordinate point data D1 is specified on the three-dimensional coordinates (x, y, z), and the reference origin O is located at the zero point of the spherical coordinate G by calibration, the reference center line L0. Can be easily obtained as a linear equation on three-dimensional coordinates.

  In FIG. 7, the reference coordinate point data D1 on the spherical coordinate G is viewed from the extension of the reference center line L0. After the reference center line L0 is calculated, a plurality of first virtual circles C11, C12, C12,... C16 including the reference coordinate point data D1 and having the same radius as the radius R of the spherical coordinate G are calculated.

  In the calculation, an equation of a circle having a radius R centered on the reference origin O of the three-dimensional coordinates and including the reference coordinate point data D1 is obtained. Since there are an infinite number of equations for this circle, as shown in FIG. 7, a plurality of circles that are present with an arbitrary angle α around the reference center line L0 around the reference center line L0 are identified, A plurality of circles are defined as first virtual circles C11, C12, C12,. In the example of FIG. 7, six equations of the first virtual circle are obtained at α = 30.

  Next, an error between each of the first virtual circles C11, C12, C12,... C16 and the coordinate point data D1, D2,. The smallest first virtual circle is selected. This is based on the equations of the first virtual circles C11, C12, C12,... C16 and the coordinate points of a plurality of coordinate point data D1, D2,. It is obtained by calculating the circle with the smallest by the least square method. In FIG. 7, C11 is selected as the first virtual circle with the smallest error.

In the least square method, the distance between each coordinate point data and the arc of the virtual circle to be calculated is dn (n = 1, 2, 3,...), And each coordinate point data and the arc of the virtual circle to be calculated are The average value of the distances to is da, and error = Σ (dn−da) ² is obtained. The virtual circle with the smallest error is selected.

  Or, the distance between each coordinate point data and the plane including the virtual circle is dn (n = 1, 2, 3,...), And the average value of the distance is da, and the error is calculated by the least square method. May be. In the case of FIG. 6, the distance (distance in a direction parallel to the Z axis) between each coordinate point data and the plane including the virtual circle in the direction parallel to the Z axis is dn (n = 1, 2, 3, )), And the average of the distance may be da, and the error may be calculated by the least square method.

  Note that the coordinate point data for obtaining the distance from each first virtual circle may use all data that goes back to the predetermined number of samples from the reference coordinate point data D1, or the predetermined sample from the latest data D1. A plurality selected from the data that goes back to the number may be used.

  FIG. 8 is a view of the spherical coordinate G from the same surface extension as the selected first virtual circle C11, and is a view taken along arrow VIII in FIG.

  As shown in FIG. 8, when the first virtual circle C11 is selected, a plurality of second virtual circles C21, C22, including the reference coordinate point data D1 and having an opening angle with respect to the first virtual circle C11. C23, C24, C25, and C26 are set. Even if the second virtual circles C21, C22, C23, C24, C25, and C26 are set as a plurality of circles that open with a certain angle β difference from the selected first virtual circle C11. Alternatively, for example, a plurality of circles in which the radius is divided by an integer so that the radius becomes (3/4) R, (1/2) R, (1/4) R may be set. In FIG. 8, six second virtual circles C21, C22, C23, C24, C25, and C26 are set at a certain angle β from the plane including the selected first virtual circle C11.

  Then, an error between each of the second virtual circles C21, C22, C23, C24, C25, C26 and the coordinate point data D1, D2,..., Dn−1, Dn is obtained, and the error is the most. Find a small second virtual circle. This is the circle with the smallest error using the respective equations of the second virtual circles C21, C22, C23, C24, C25, C26 and the coordinate point data D1, D2,..., Dn-1, Dn. Is calculated by the method of least squares. In FIG. 8, C25 is selected as the second virtual circle with the smallest error.

  The calculation of the least squares method at this time can be performed by the same calculation method as that for obtaining the error between each coordinate point data and the first virtual circle.

  Also in this case, as the coordinate point data for obtaining the distance from the second virtual circle, all the data obtained while going back to the predetermined number of samples from the reference coordinate point data D1 may be used. A plurality of data selected from the data D1 to the predetermined number of samples may be used.

  It is estimated that the second virtual circle C25 selected by the above calculation is a movement locus circle along which the coordinate point data D1, D2,..., Dn−1, Dn move. The rotation plane calculation unit 13 provided in the calculation unit 10 obtains the current magnetic field by obtaining an axis that passes through the center Os of the selected second virtual circle C25 and is perpendicular to the plane including the second movable circle C25. A relative rotation axis between the detection device 1 and the geomagnetic vector V can be calculated. Further, the angular velocity calculation unit 14 of the calculation unit 10 selects any two of the coordinate point data D1, D2,..., Dn−1, Dn, and two coordinates from the center Os of the second virtual circle C25. The angular velocity can be obtained by obtaining the opening angle of the point data and differentiating the opening angle with the time when the two coordinate point data are obtained.

  In the calculation unit 10, new coordinate point data D <b> 1 is successively supplied to the storage unit of the data buffer 11 after a predetermined sampling time. Therefore, the estimated movement locus circle can be updated by extracting the latest coordinate point data as reference coordinate point data and performing the above calculation using this reference coordinate point data for each predetermined number of samplings. Therefore, it is possible to always calculate an angular velocity with high accuracy.

FIG. 9 shows a calculation method according to the second embodiment of the present invention.
FIG. 9 shows the reference coordinate point data D1 on the spherical coordinates G viewed from the extended line of the reference center line L0.

  In the second embodiment, a plurality of virtual circles including the reference coordinate point data D1 and having different radii are set on the spherical coordinate G in the respective directions. In the example of FIG. 9, two virtual circles Ca and Cb having the same radius R as the spherical coordinate G and including the reference coordinate point data D1 are set with an angle difference of 90 degrees. Further, virtual circles Cc, Cc, Cd, and Cd having an opening angle from one virtual circle Ca including the reference coordinate point data D1 are set, and having an opening angle from the other virtual circle Cb including the reference coordinate point data D1. Virtual circles Ce, Ce, Cf, Cf are set.

  The virtual circles Cc, Cc, Cd, and Cd and the virtual circles Ce, Ce, Cf, and Cf may be set to have an equal opening angle, or set so that the radius changes stepwise. May be.

  In FIG. 9, two virtual circles Ca and Cb are set with an angle of 90 degrees around the reference center line L0, and virtual circles Cc, Cc, Cd, and Cd having an opening angle from the respective virtual circles Ca and Cb. And virtual circles Ce, Ce, Cf, and Cf are set, but three or more virtual circles including the reference coordinate point data D1 with radius R are set, and a virtual having an opening angle with respect to each virtual circle. A circle may be set.

  Among the plurality of virtual circles set as shown in FIG. 9, the one having the shortest distance to the coordinate point data D1, D2, D3,... Dn-1, Dn, or the coordinate point data D1, D2, D3 ,..., Dn−1, Dn is selected as the virtual circle with the smallest error, and the virtual circle is estimated as the movement locus circle.

  The magnetic field detection apparatus of the present invention can calculate the angular velocity by specifying the rotational motion using the coordinate point data from the triaxial magnetic sensor. Therefore, it can be used for a portable game device or an input device of a game device. It can also be used as a detection unit that detects changes in posture of the robot's arms and joints.

  Furthermore, the magnetic field detection device of the present invention can be used as a device for detecting the motion of a magnetic vector of an external magnetic field other than geomagnetism. For example, it is possible to fix the magnetic detection device and detect what direction and how the external magnetic vector moves.

DESCRIPTION OF SYMBOLS 1 Magnetic field detection apparatus 2 Magnetic detection part 3 X-axis sensor 4 Y-axis sensor 5 Z-axis sensor 6 Magnetic field data detection part 7 Memory 10 Calculation part 11 Data buffer 12 Rotation plane calculation part 13 Rotation plane calculation part 14 Angular velocity calculation part 15 Main calculation Part D1, D2, D3, D4,..., Dn Coordinate point data D1 Reference coordinate point data C11, C12, C13, C14, C15, C16 First virtual circle C21, C22, C23, C24, C25, C26 2 virtual circles Ca, Cb, Cc, Cd, Ce, Cf Virtual circle V Geomagnetic vector

Claims (6)

A magnetic detection unit in which the X direction, the Y direction, and the Z direction orthogonal to each other are determined as reference directions, and a calculation unit;
An X-axis sensor in which the absolute value of the detection output becomes a maximum value when the X direction is directed to the magnetic direction and the absolute value of the detection output when the Y direction is directed to the magnetic direction. Is equipped with a Y-axis sensor in which the maximum value is detected, and a Z-axis sensor in which the absolute value of the detection output is a maximum value when the Z direction is directed to the magnetic direction,
In the calculation unit, a magnetic vector obtained from a plurality of the detection outputs sampled intermittently is converted into coordinate point data on spherical coordinates, and includes one reference coordinate point data among the plurality of coordinate point data. A magnetic field detection apparatus, wherein a plurality of virtual circles positioned on the spherical coordinates are set, and a virtual circle having the smallest error from the plurality of coordinate point data is estimated as a movement locus circle of the coordinate point data. A plurality of first virtual circles including the reference coordinate point data and having the same radius as the spherical coordinate radius are set on the spherical coordinates, and the first virtual circle with the smallest error from the plurality of coordinate point data is set. Circle is selected,
Next, a plurality of second virtual circles that include the reference coordinate point data, have an opening angle with the selected first virtual circle, and are located on the spherical coordinate and have different radii are set. The magnetic field detection device according to claim 1, wherein the second virtual circle having the smallest error from a plurality of coordinate point data is estimated as a movement locus circle of the coordinate point data.   3. The magnetic field detection measure according to claim 2, wherein the plurality of first virtual circles are set with a certain angular interval around a reference center line that passes through the center of the reference coordinate point data and the spherical coordinate.   4. The magnetic field detection device according to claim 2, wherein the plurality of second virtual circles are set apart from the selected first virtual circle by an opening angle of a predetermined angular interval. 5.   The magnetic field detection device according to claim 1, wherein a plurality of the virtual circles including the reference coordinate point data and having different radii are set.   6. The angular velocity of the magnetic vector at that time is obtained from the opening angle of two coordinate point data from the center of the moving locus circle and the time when the two coordinate point data are obtained. The magnetic field detection apparatus in any one.

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