JP5341861B2 - Magnetic field detector - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a magnetic field detection device capable of accurately calculating rotation operations and angular velocity of magnetic vectors by using sensors of three axes for detecting magnetism such as earth magnetism. <P>SOLUTION: Coordinate points of the magnetic vectors are calculated based on detection outputs from three magnetic sensors for detecting the magnetic vectors. A movement plane on which coordinate point data moves is determined by using a first arithmetic data group N1-1 including a prescribed number of the calculated coordinate point data. An error between an average value of a latest data group Na-1 including a plurality of the latest coordinate point data and the movement plane is determined. When the error is small, a first arithmetic data group N1-2 composed of a larger number of data including the latest data group Na-1 is used to determine the movement plane. When the error is large, a second arithmetic data group N2-1 composed of a small number of data including the latest data group Na-1 is used to calculate the movement plane. <P>COPYRIGHT: (C)2012,JPO&amp;INPIT

Description

  The present invention relates to a magnetic field detection device that detects a magnetic vector such as a geomagnetic vector with a magnetic sensor directed in each of three orthogonal directions, and in particular, the magnetic vector rotates in a three-dimensional space with respect to a magnetic detection unit. In some cases, the present invention relates to a magnetic field detection apparatus that can determine the rotational locus of the magnetic vector and accurately know the rotational motion of a magnetic vector.

  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.

JP 2008-224642 A

  As described in Patent Document 1 and the like, in a magnetic field detection apparatus having a magnetic detection unit having a three-axis magnetic sensor, detection data obtained by detecting a magnetic vector is acquired at a certain sample time, and a plurality of detections are performed. Data is held in memory one after another. And the relative rotation state of a magnetic detection part and a magnetic vector is calculated using the hold | maintained some detection data.

  However, if the number of samples of detection data used in the calculation is too small, the relative rotation between the magnetic detection unit and the magnetic vector when the detection data of the magnetic vector changes temporarily due to external noise or the like, It will be recognized as something that has temporarily changed extremely. As a result, it becomes difficult to stably grasp the relative motion between the magnetic detection unit and the magnetic vector.

  Increasing the number of samples of detection data used for computation can stably determine the relative rotation between the magnetic detection unit and the magnetic vector without being affected by a large temporary change such as external noise. . However, in this case, when the relative rotation state between the magnetic detection unit and the magnetic vector actually changes greatly, it becomes impossible to accurately grasp the change.

  The present invention solves the above-described conventional problems, and uses a plurality of data detected by a magnetic sensor directed in three orthogonal directions to detect rotational motion stably without being affected by noise. In addition, an object of the present invention is to provide a magnetic field detection device that can improve follow-up to changes in rotational motion.

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.
The magnetic detection unit includes an X-axis magnetic sensor that detects an X-axis magnetic component, a Y-axis magnetic sensor that detects a Y-axis magnetic component, and a Z-axis magnetic sensor that detects a Z-axis magnetic component. ,
Based on the detection outputs of the X-axis magnetic sensor, the Y-axis magnetic sensor, and the Z-axis magnetic sensor, the arithmetic unit obtains the direction of the magnetic vector as coordinate point data on three-dimensional coordinates, and a plurality of coordinate points The plane with the smallest error from the data is calculated as the moving plane where the coordinate point data is moving,
When an error between the latest data group including at least one latest coordinate point data and the moving plane at that time is equal to or less than a predetermined value or less than the predetermined value, the latest data group and a plurality of data obtained before that The next movement plane is calculated from a predetermined number of first calculation data groups including the coordinate point data, and an error between the latest data group and the movement plane at that time is greater than or equal to a predetermined value or exceeds that value. In this case, the next movement plane is obtained from the second calculation data group including the latest data group and having a smaller number of data than the first calculation data group.

  The magnetic field detection apparatus of the present invention is obtained by estimating a moving plane in which coordinate point data is moving using a plurality of coordinate point data. When there is no significant change in the latest data group including the latest coordinate point data, the movement plane is calculated using the first calculation data group including a large number of coordinate point data, thereby temporarily converting the coordinate point data due to noise or the like. The moving plane can be obtained without being greatly affected by a large change. When the latest data group changes greatly, the moving plane is calculated using the second calculation data group with a small number of coordinate point data. As a result, when the relative position between the magnetic detection unit and the magnetic vector is actually changed, the moving plane can be obtained following this change.

  According to the present invention, the movement locus of the coordinate point data is obtained from the intersection line between the spherical surface where the coordinate point data appears on the three-dimensional coordinates and the movement plane, and the angle of the magnetic detection unit is obtained from the movement locus. Acceleration is required.

  In the present invention, the latest data group is composed of a plurality of coordinate point data including the latest coordinate point data, an average value of the plurality of coordinate point data included in the latest data group, and a moving plane at that time, Is preferably compared to a predetermined value.

  When configured as described above, even if some of the multiple coordinate point data included in the latest data group fluctuate greatly due to noise, the latest data group and the movement at that time can be obtained by taking the average value of the coordinate point data. When calculating the error from the plane, it is possible to reduce the influence of noise and the like.

  According to the present invention, the latest data group includes only one latest data, and the first calculation data group is determined depending on whether or not there is a large error between the one latest data and the moving plane at that time. Or the second calculation data group may be selected.

  In the present invention, the second calculation data group may be composed of only the latest data group. However, when the coordinate data included in the latest data group is small, the second calculation data group may be composed of the latest data group and at least one coordinate point data obtained before that.

  In the present invention, an error between a general formula of a plane on three-dimensional coordinates and a plurality of coordinate point data included in the first calculation data group is calculated by a least square method, and a plane having the smallest error is a moving plane. As required.

  Further, according to the present invention, the error between the general expression of the plane on the three-dimensional coordinates and the plurality of coordinate point data included in the second calculation data group is calculated by the least square method, and the plane with the smallest error is moved. Required as a plane.

  The present invention can determine the absolute motion of a magnetic vector by using the detection output of a magnetic sensor directed in three orthogonal directions. That is, it is difficult to be affected by temporary fluctuations in the detection output due to noise or the like, and the movement locus can be obtained following the movement change.

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, the Y-axis sensor and the Z-axis sensor provided in the geomagnetism detection unit, Explanatory drawing of three-dimensional coordinates showing the detection state of the geomagnetic vector with the Z-axis oriented in the direction of gravity, Explanatory drawing of three-dimensional coordinates showing the detection operation of the geomagnetic vector when the magnetic detection unit is rotating around an arbitrary axis, Explanatory drawing of the calculation process which calculates | requires the movement plane where coordinate point data move,

  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 intersection of the X axis, the Y axis, and the Z axis is the reference origin O. 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 includes a pinned magnetic layer and a free magnetic layer formed of a soft magnetic material formed of a Ni—Co alloy or a Ni—Fe alloy, and copper sandwiched between the pinned magnetic layer and the free magnetic layer. And a nonmagnetic 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 a fixed resistor are connected in series. A voltage is applied to the series circuit of the X-axis sensor 3 and the fixed resistor, and a midpoint voltage between the X-axis sensor 3 and the fixed resistor 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 is the origin.

  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. At this time, the detection output of the X axis becomes a maximum value on the plus side with respect to the origin. 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 detection output of the X axis is a maximum value on the minus side with respect to the origin.

  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 to the same direction as the geomagnetic vector V, the detection output of the Y-axis becomes a maximum value on the plus side with respect to the origin. 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 maximum value on the minus side with respect to the origin. Similarly, when the fixed direction PZ of the magnetization of the fixed magnetic layer of the Z-axis sensor 5 is set to 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 origin. 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 maximum value on the minus side with respect to the origin.

  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 coordinate point data D in the final stage 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 sampling times, and the calculated coordinate point data D is stored in the data buffer 11 in order. Go.

  Each of the XYZ axes of the three-dimensional coordinates shown in FIG. 5 is fixed and set to the magnetic field detection device 1, and as shown in FIG. 4, the X-axis sensor 3 is along the X-axis. The Y-axis sensor 4 is fixed along the Y-axis, and the Z-axis sensor 5 is fixed along the Z-axis.

  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, for example, 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 the center lines is calculated. In the calculation unit 10, the intersection obtained as a result of the calibration is corrected so as to become the reference origin O of the three-dimensional coordinates of XYZ.

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

  FIG. 5 shows a state in which the Z axis set in the magnetic field detection device 1 is oriented in the direction of gravity. In this case, 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. In this state, when the magnetic field detection device 1 is rotated about the Z axis (about the axis directed in the direction of gravity), the coordinate point data D (xb, yb, zb) sampled one after another becomes the Z axis. It moves along a horizontal latitude line Ha that is centered and parallel to the XY axis.

  Here, if the arithmetic unit 10 recognizes that the direction of the reference axis Z is directed in the direction of gravity, the horizontal latitude line Ha can be recognized as the movement locus of the coordinate point data, and the horizontal latitude line Ha. It is possible to obtain the angular velocity from the opening angle of a plurality of coordinate point data D centering on the intersection of the Z axis and the sampling time. However, when the magnetic field detection device 1 and the portable device in which the magnetic field detection device 1 is mounted are not equipped with a detection device that detects their posture, the reference coordinates in the magnetic detection device 1 are used. It cannot be recognized in which direction the three-dimensional coordinates of a certain XYZ are directed.

  Therefore, in the calculation unit 10 shown in FIG. 2, by executing the following software, when the magnetic detection device 1 is rotated about an arbitrary axis, what kind of rotation is performed in which direction. It is possible to calculate whether or not.

  FIG. 6 shows coordinate point data D1, D2,..., Dm obtained when the magnetic field detection device 1 is rotated around an arbitrary axis S0 other than XYZ. Yes. At the time when the coordinate point data is obtained, the orientation of the axis S0 is not specified, and the locus of the circle along which the coordinate point data D1, D2,.

  Therefore, the movement plane calculation unit 12 of the calculation unit 10 shown in FIG. 2 calculates the movement plane Px estimated that a plurality of coordinate point data are moving. The calculated intersection line of the movement plane Ps and the spherical surface G is specified as the movement locus of the coordinate point data.

  As an example of a method for calculating the movement plane Px, a general formula of a plane: ax + by + cz + d = 0 is used. In the general formula, a, b, and c are components of a normal vector of a plane {n → = (a, b, c)}. Substituting the components (xi, yi, zi) of the plurality of coordinate point data Di (xi, yi, zi) into (x, y, z) of the general formula of the plane, the equations of the plurality of planes are obtained. A plane having the smallest error from each equation is obtained by multiplication, and the plane is estimated as a moving plane Px.

  FIG. 7 shows a plurality of coordinate point data Di stored in the data buffer 11. The oldest coordinate point data is Dm, and is stored in the data buffer 11 as new coordinate point data in the order of D6, D5, D4,.

  A predetermined number of data among the coordinate point data Di stored in the data buffer 11 is used as the first calculation data group. In the example shown in FIG. 7, a plurality of coordinate point data from Dm to D7 is used as the first calculation data group N1-1. (Xm, ym, zm)... (X7, y7, z7) from the coordinate point data Dm to D7 is substituted into the general formula of the plane: ax + by + cz + d = 0 (x, y, z), and a plurality of equations Is obtained. The plane that minimizes the error from this equation is obtained by the least square method, and the obtained plane is obtained as the moving plane P1 at that time.

  By increasing the number of coordinate point data Di of the first calculation data group N1-1 to some extent, even if coordinate point data that has temporarily changed extremely due to external noise or the like is included, the influence thereof is reduced. A moving plane P1 that can be reduced and is close to the plane on which the coordinate point data Di is moving can be obtained.

  Thereafter, the plurality of latest coordinate point data D6, D5, and D4 obtained are set as the latest data group Na-1. In FIG. 7, the number of coordinate point data included in the latest data group Na-1 is “3” for the sake of simplicity, but in fact, the latest coordinate point data Di included in the latest data group Na-1. There are more. However, the number of coordinate point data Di included in the latest data group Na-1 is sufficiently smaller than the number of coordinate point data Di included in the first calculation data group N1-1. For example, the latest data group Na- The number of data included in 1 is 1/5 or less, preferably 1/10 or less, of the number of data included in the first calculation data group N1-1.

  After the movement plane P1 is calculated in the first calculation data group N1-1, the average value of the plurality of coordinate point data Di included in the latest data group Na-1, that is, the average value of x and the average value of y and z And an error between (x, y, z) of the equation of the moving plane P1. Alternatively, an error between each of the plurality of coordinate point data included in the latest data group Na-1 and the movement plane P1 is obtained by the least square method.

  The latest data group Na-1 is composed of a plurality of coordinate point data, and the average value calculation or the least square method calculation is performed as described above. Even when the latest data group Na-1 and the movement plane P1 are compared, the influence of extremely changing data can be reduced. Note that data that changes extremely in the latest data group Na-1 may be ignored and the comparison with the movement plane P1 may be performed.

  When the error between the latest data group Na-1 and the moving plane P1 at that time is less than or equal to a predetermined value or less than the predetermined value, the moving plane calculation unit 12 moves the coordinate point data Di. Is determined to have not changed significantly.

  At this time, the latest data group Na-1 and a plurality of coordinate point data Di obtained so far are defined as a first calculation data group N1-2, a general formula of the plane, and the first calculation data group N1-2. Is calculated by the least square method, and the plane with the smallest error is set as the next moving plane P2. The number of coordinate point data Di included in the first calculation data group N1-2 is the same as the number of coordinate point data Di included in the first calculation data group N1-1 used in the previous calculation.

  When the error between the coordinate point data Di included in the latest data group Na-1 and the moving plane P1 at that time is small, the first calculation data group N1- consisting of many data including the latest data group Na-1. Since the movement plane P2 is calculated based on 2, the change between the movement plane P1 and the movement plane P2 can be made extremely small. In some cases, the movement plane P1 and the next movement plane P2 may have the same equation. . That is, the movement plane Px can be calculated as a stable plane without being affected by temporary noise.

  When the error between the latest data group Na-1 and the moving plane P1 at that time is greater than or equal to a predetermined value or exceeds that value, the coordinate point data Di is moved in the moving plane calculation unit 12. Judge that the trajectory has changed significantly.

  At this time, errors of a plurality of equations obtained by substituting (Xi, yi, zi) of the respective coordinate point data Di of the second calculation data group N2-1 including the latest data group Na-1 into the general formula of the plane are The minimum plane is obtained by the method of least squares, and the plane is set as the next moving plane P3. The number of data of coordinate point data included in the second calculation data group N2-1 is sufficiently smaller than the number of data of coordinate point data included in the first calculation data group N1-2. For example, the number of data included in the second calculation data group N2-1 is 1/5 or less, preferably 1/10 or less, of the number of data included in the first calculation data number N1-2.

  Note that the second calculation data group N2-1 may be composed of only a plurality of coordinate point data constituting the latest data group Na-1.

  When the error between the coordinate point data Di included in the latest data group Na-1 and the moving plane P1 at that time becomes large, the moving plane P3 is based on the second calculation data group N2-1 having a small number of data. Therefore, when the relative motion trajectory between the actual magnetic field detector 1 and the geomagnetic vector V changes greatly, it is possible to update the moving plane following this.

  Thereafter, an error between the average value of the coordinate point data included in the predetermined number of latest data groups Na-2 including the coordinate point data D3, D2, and D1 and the moving plane P2 or P3 at that time is obtained. Alternatively, an error between a plurality of coordinate point data included in the latest data group Na-2 and the moving plane P2 or P3 at that time is obtained by the least square method. If the error is less than or equal to a predetermined value or less than that value, a moving plane is obtained from the first calculation data group N1-3 including the latest data group Na-2. When the error is greater than or equal to a predetermined value or exceeds the value, a moving plane is obtained from the second calculation data group N2-2.

  As described above, when the coordinate plane data Di does not change significantly in the movement plane calculation unit 12, the movement plane Px with little change or the movement plane Px with little change is stably obtained, and the coordinate point data Di is obtained. When there is a large change, a new movement plane Px is obtained so as to follow the change.

  In the rotation axis calculation unit 13 illustrated in FIG. 2, an intersection line between the movement plane Px and the spherical surface G calculated by the movement plane calculation unit 12 is obtained. This intersection line is the movement locus of the coordinate point data Di. A line connecting the center of the circle, which is an intersection line, and the origin O of the three-dimensional coordinates is obtained as the rotation axis S0. Furthermore, when the moving plane Px is obtained in the angular velocity calculation unit 14, the angular velocity is obtained by differentiating the opening angle around the rotation axis S0 of the plurality of coordinate point data Di with the sampling time between the data. Desired.

  The magnetic field detection apparatus of the present invention can calculate an angular velocity by specifying a three-dimensional rotational motion using only a three-axis magnetic sensor without providing posture detection means such as gravitational acceleration. 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 direction and movement 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 the direction in which the external magnetic vector is approaching.

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 Moving plane calculation part 13 Rotation axis calculation part 14 Angular velocity calculation part 15 Main calculation Part D1,... Dm Coordinate point data N1-1, N1-2 First calculation data group N2-1, N2-2 Second calculation data group Na-1, Na-2 Latest data group

Claims (8)

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;
The magnetic detection unit includes an X-axis magnetic sensor that detects an X-axis magnetic component, a Y-axis magnetic sensor that detects a Y-axis magnetic component, and a Z-axis magnetic sensor that detects a Z-axis magnetic component. ,
Based on the detection outputs of the X-axis magnetic sensor, the Y-axis magnetic sensor, and the Z-axis magnetic sensor, the arithmetic unit obtains the direction of the magnetic vector as coordinate point data on three-dimensional coordinates, and a plurality of coordinate points The plane with the smallest error from the data is calculated as the moving plane where the coordinate point data is moving,
When an error between the latest data group including at least one latest coordinate point data and the moving plane at that time is equal to or less than a predetermined value or less than the predetermined value, the latest data group and a plurality of data obtained before that The next movement plane is calculated from a predetermined number of first calculation data groups including the coordinate point data, and an error between the latest data group and the movement plane at that time is greater than or equal to a predetermined value or exceeds that value. The next moving plane is obtained from a second calculation data group including the latest data group and having a smaller number of data than the first calculation data group.   The magnetic field detection apparatus according to claim 1, wherein a movement locus of the coordinate point data is obtained from an intersection line between a spherical surface where the coordinate point data appears on the three-dimensional coordinates and the movement plane.   The magnetic field detection apparatus according to claim 2, wherein an angular acceleration of a magnetic detection unit is obtained from the movement locus.   The latest data group is composed of a plurality of coordinate point data including the latest coordinate point data, and an error between the average value of the plurality of coordinate point data included in the latest data group and the moving plane at that time, 4. The magnetic field detection device according to claim 1, wherein the magnetic field detection device is compared with a predetermined value.   The magnetic field detection apparatus according to any one of claims 1 to 4, wherein the second calculation data group includes only the latest data group.   5. The magnetic field detection device according to claim 1, wherein the second calculation data group includes a latest data group and at least one coordinate point data obtained before that.   An error between a general formula of a plane on three-dimensional coordinates and a plurality of coordinate point data included in the first calculation data group is calculated by a least square method, and a plane having the smallest error is obtained as a moving plane. Item 7. The magnetic field detection device according to any one of Items 1 to 6.   An error between a general expression of a plane on three-dimensional coordinates and a plurality of coordinate point data included in the second calculation data group is calculated by a least square method, and a plane having the smallest error is obtained as a moving plane. Item 8. The magnetic field detection device according to any one of Items 1 to 7.

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