WO2011158856A1 - Error cause determination method and device, error compensation method, three-axis magnetic sensor, sensor module, and program for determining error cause - Google Patents

Abstract

Provided is an error cause determination method for a three-axis magnetic sensor comprising three magnetic elements for respectively detecting magnetic fields in the X-axis, Y-axis, and Z-axis directions. On the basis of output values from the respective magnetic elements when magnetic fields are applied in the respective axis directions, space vectors (Xm, Ym, Zm) indicating the magnetic field detection directions of the three-axis magnetic sensor, and space vectors (Xe, Ye, Ze) indicating the magnetic field detection directions of the respective magnetic elements are calculated. Next, intersection angles between Xm, Ym, and Zm are calculated, and intersection angles between Xe, Ye, and Ze are calculated. It is determined whether an error is caused by the mounting states of the respective magnetic elements, a mismatch between the magnetic field application directions and the magnetic field detection directions of the three-axis magnetic sensor and the respective magnetic elements, nonuniformity of the sensitivities of the respective magnetic elements, or a combination thereof.

Description

Error factor determination method and apparatus, error compensation method, three-axis magnetic sensor, sensor module, and error factor determination program

The present invention relates to an error factor determination method and apparatus, an error compensation method, a three-axis magnetic sensor, a sensor module, and an error factor determination program. In particular, an error factor determination method and apparatus capable of determining an error factor included in a measured and calculated azimuth angle and canceling the error and accurately determining an azimuth angle, an error compensation method, and a three-axis magnetic sensor , A sensor module, and an error factor determination program.
This application claims priority based on Japanese Patent Application No. 2010-138531 filed in Japan on June 17, 2010, the contents of which are incorporated herein by reference.

In portable electronic devices such as mobile phones and portable terminals, an orientation detection system (hereinafter referred to as “sensor module”) including a sensor for detecting the orientation is widely used. In addition, if the sensor module is combined with GPS (Global Positioning System) functions, a navigation system can be constructed by detecting spatial position information in addition to the azimuth angle. ing.

In order to detect the direction by such a sensor module, it is necessary to detect the geomagnetic direction with respect to the sensor module. Since the above-described portable electronic devices and the like are used at various posture angles in a three-dimensional space, it is necessary to realize accurate azimuth measurement even if they are placed in various directions in three dimensions.

Conventionally, as a method of measuring the azimuth by the sensor module, a method of detecting each magnetic field in three orthogonal axes, a method of detecting two magnetic fields, and a method of selecting a two-axis direction by detecting a magnetic field in three axes. There are various methods such as a method of detecting magnetic fields (including a magnetic field), a method of obtaining them by combining a tilt angle and a declination angle with respect to geomagnetism by an acceleration sensor or a gyro sensor, and a tilt angle by a tilt sensor (for example, Patent Documents 1 to 5).

Here, the coordinate axis, dip angle and declination angle set for the mobile electronic device will be described. 17A and 17B are diagrams for explaining orthogonal coordinate axes that are logically but fixedly set in the portable electronic device 100. FIG. 17A and 17B are a plan view and a side view of the portable electronic device 100, respectively. The normal direction of the flat front surface of the portable electronic device 100 is the Z-axis direction, the longitudinal direction of the portable electronic device 100 is the Y-axis, and the rest is the X-axis direction. FIG. 18 is a diagram for explaining the dip angle and the declination angle. For example, the angle of intersection α between the azimuth obtained on the XY plane and the actual geomagnetic direction is called the dip angle, and the angle of intersection β between the direction and magnetic north is called the declination.

FIG. 19 is a diagram illustrating a logical configuration of a sensor module that can detect magnetic fields in three orthogonal axes and can calculate the azimuth by calculating the magnetic field with the detected dip, declination, and inclination.
A sensor module 50 shown in FIG. 19 is mounted with a three-axis magnetic sensor 1 that detects magnetic fields in three orthogonal directions set in a three-dimensional space, a geomagnetic dip and declination, and the sensor module 50. And a signal processing unit 3 that calculates an accurate azimuth angle based on information from the triaxial magnetic sensor 1 and the detection unit 2. .

Specifically, the three-axis magnetic sensor 1 includes an X-axis magnetic element 11X, a Y-axis magnetic element 11Y, and a Z-axis magnetic element 11Z that detect magnetic fields in the X-axis, Y-axis, and Z-axis directions. And a signal processing unit 12 that performs signal processing on detection results from the magnetic elements 11X, 11Y, and 11Z. That is, the direction and magnitude of the terrestrial magnetism are detected by separating them into components in three orthogonal directions.
The magnetic elements 11X, 11Y, and 11Z include, for example, an MR (Magneto Resistive) sensor using a magnetoresistive effect, a sensor using a Hall element, an MI (Magneto Impedance) sensor using electromagnetic induction, and a flux gate type magnetism. A sensor, an orthogonal fluxgate magnetic sensor, or the like can be used.

20A and 20B are diagrams showing the physical configuration of the three-axis magnetic sensor 1 shown in FIG. 20A is a side view, and FIG. 20B is a plan view. As shown in FIGS. 20A and 20B, the triaxial magnetic sensor 1 is detected by the mounting substrate 13, the magnetic elements 11X, 11Y, and 11Z mounted thereon by wire bonding, and the magnetic elements 11X, 11Y, and 11Z. And a signal processing unit 12 for performing arithmetic processing on the magnetic signal.
Here, the three-axis magnetic sensor 1 is mounted in the device so as to align with the above-described coordinate axis set in the device to be mounted, whereby the direction of magnetic detection in each of the magnetic elements 11X, 11Y, and 11Z. Is consistent with each axial direction set in the device.

By the way, in the conventional methods described above, it is assumed that the magnetic field detection directions of the magnetic elements included in the three-axis magnetic sensor are ideally orthogonal to each other.
Further, it is assumed that the magnetic field detection direction of each magnetic element and the magnetic field detection direction set for the three-axis magnetic sensor, that is, the three-axis direction set for the portable electronic device are the same. .
Further, it is assumed that the sensitivity of each magnetic element is set equal to each other.

However, in practice, it is inevitable that an error is included in the finally determined azimuth angle. Possible causes of the error are as follows.
The first error factor is mounting deviation of the magnetic element with respect to the mounting board in the assembly process of the three-axis magnetic sensor. FIG. 21A and FIG. 21B are diagrams for explaining the first error factor.
In the assembly process of installing the magnetic elements 11X, 11Y, and 11Z corresponding to the three-dimensional directions on the mounting substrate 13 of the three-axis magnetic sensor 1, each magnetic field for each axis of the three-axis magnetic sensor 1 is changed. The magnetic elements 11X, 11Y, and 11Z are installed so as to be orthogonal to each other so that they can be detected, and the directions of the axes of the three-axis magnetic sensor 1 and the magnetic field detection of the magnetic elements 11X, 11Y, and 11Z are detected. The direction must match.

However, in the assembling process, the installation position of each of the magnetic elements 11X, 11Y, 11Z with respect to the mounting substrate 13 is not displaced. There are two types of positional deviations shown in FIGS. 21A and 21B.
One is a state as shown in FIG. 21A in which at least two axes in the magnetic field detection direction of each of the magnetic elements 11X, 11Y, and 11Z are not orthogonal to each other (hereinafter referred to as “absolute error in assembly”). In the example of FIG. 21A, the axis of the magnetic element 11Y is not orthogonal to the axis of the magnetic element 11X.
The other is that, as shown in FIG. 21B, the magnetic sensing directions of the magnetic elements 11X, 11Y, and 11Z are orthogonal to each other, but each direction of the magnetic field detection direction of the three-axis magnetic sensor 1 and the magnetic elements thereof. In this state, at least one direction does not coincide with the magnetic field detection directions of 11X, 11Y, and 11Z (hereinafter referred to as “relative error in assembly”). In the example of FIG. 21B, since the elements mounted on the mounting board 13 are not aligned with the mounting board 13, in this case, the X-axis direction and the Y-direction of the magnetic field detection direction of the triaxial magnetic sensor 1 The magnetic field detection directions of the magnetic elements 11X and 11Y do not match.
In practice, it is difficult to distinguish between absolute errors and relative errors in assembly.

The second cause of error is that when measuring and adjusting the magnetic sensitivity of each axis of the triaxial magnetic sensor 1, the direction of the coil or the like for applying a magnetic field coincides with the magnetic field detection direction of the triaxial magnetic sensor 1. It is difficult to make it.
That is, in the three-axis magnetic sensor 1 used for the sensor module 50, since the geomagnetism is decomposed in the orthogonal coordinate system and the azimuth measurement is performed, the three-axis magnetic sensor 1 in the space in which a magnetic field can be arbitrarily applied in the three-axis directions orthogonal to each other. An azimuth error can be calculated by installing the axial magnetic sensor 1 and evaluating the crossing angle of the magnetic field detection direction of the triaxial magnetic sensor 1. However, at this time, when measuring and adjusting the magnetic sensitivity of each axis of the triaxial magnetic sensor 1, the direction of the coil for applying the magnetic field and the magnetic field detection direction of the triaxial magnetic sensor 1 should be matched. However, when the magnetic sensitivities of a plurality of three-axis magnetic sensors 1 are simultaneously measured using a socket or the like, the socket installation direction and the desired magnetic field detection direction of the three-axis magnetic sensor 1 are matched. Is difficult. Therefore, the accuracy of the azimuth error is reduced.
Due to the above error factors, it is difficult to measure an accurate error angle, and it is difficult to finally obtain an accurate azimuth angle.

JP 2005-172787 A JP 2006-337057 A JP 2008-241676 A JP 2007-309833 A JP 2009-204305 A

The present invention provides an error factor determination method capable of determining an error factor included in a measured and calculated azimuth angle, and an apparatus capable of implementing the error factor determination method.
The present invention also provides an error compensation method, a three-axis magnetic sensor, and a sensor module that can accurately determine the azimuth angle by canceling the above errors.

An error factor determination method according to an aspect of the present invention includes a three-axis magnetic field applied to a three-axis magnetic sensor having three magnetic elements that detect magnetic fields in the X-axis, Y-axis, and Z-axis directions orthogonal to each other. Output value from each magnetic element when the magnetic field applying means applies a magnetic field in the X-axis direction, and output from each magnetic element when the three-axis magnetic field applying means applies a magnetic field in the Y-axis direction Three space vectors representing the magnetic field detection direction of the three-axis magnetic sensor based on the value and the output value from each magnetic element when the three-axis magnetic field applying means applies a magnetic field in the Z-axis direction; The step of calculating each space vector representing the magnetic field detection direction of the three magnetic elements, and the mutual angle between the space vectors for the three space vectors representing the magnetic field detection direction of the three-axis magnetic sensor, respectively. And calculating each other's crossing angle between the space vectors, the magnetic field application direction by the three-axis magnetic field applying means, and the magnetic fields. Whether the magnetic field detection direction of the element and the magnetic field detection direction of the three-axis magnetic sensor coincide with each other, three intersection angles of the magnetic field detection direction of each magnetic element and three intersection angles of the magnetic field detection direction of the three-axis magnetic sensor Whether or not the cause of the error included in the azimuth to be obtained is due to the mounting state of each magnetic element, the magnetic field application direction by the three-axis magnetic field applying means, and the three-axis magnetic field It is due to the mismatch of the magnetic field detection direction of the sensor and each of the magnetic elements, due to inconsistency of the sensitivity of the magnetic elements, or a combination thereof Comprising a step of determining whether the at Align, a.

An error factor determination device according to an aspect of the present invention includes a three-axis magnetic sensor having three magnetic elements that detect magnetic fields in the X-axis, Y-axis, and Z-axis directions orthogonal to each other, and the three-axis magnetic sensor. And a three-axis magnetic field applying unit for applying a magnetic field, wherein the three-axis magnetic sensor is configured such that each of the three-axis magnetic sensors when the magnetic field is applied in the X-axis direction of the three-axis magnetic field applying unit. An output value from the magnetic element, an output value from each magnetic element when a magnetic field is applied in the Y-axis direction of the triaxial magnetic field applying means, and a magnetic field in the Z-axis direction of the triaxial magnetic field applying means. Based on the output values from the magnetic elements when applied, three space vectors representing the magnetic field detection directions of the three-axis magnetic sensor are calculated, and the magnetic field detection directions of the three magnetic elements are respectively calculated. Compute each space vector to represent , For the three space vectors representing the magnetic field detection direction of the three-axis magnetic sensor, the mutual angle between the space vectors is calculated, and for each space vector representing the magnetic field detection direction of the three magnetic elements, Calculating the crossing angle between the space vectors, whether the magnetic field application direction by the three-axis magnetic field applying means, the magnetic field detection direction of each magnetic element, and the magnetic field detection direction of the three-axis magnetic sensor coincide with each other; By verifying whether or not the three crossing angles in the magnetic field detection direction of each magnetic element coincide with the three crossing angles in the magnetic field detection direction of the three-axis magnetic sensor, the cause of the error included in the azimuth angle to be obtained is Whether the magnetic element depends on the mounting state of each magnetic element, the magnetic field application direction by the three-axis magnetic field applying means, and the magnetism of the three-axis magnetic sensor and each magnetic element. Whether is by detecting the direction of mismatch, comprising the magnetic element or the sensitivity of which the due unstructured, or signal processing unit for determining whether the combination thereof.

An error compensation method in a three-axis magnetic sensor according to an aspect of the present invention is to adjust the magnetic sensitivity of each magnetic element when it is determined that the magnetic field detection directions of the magnetic elements are not orthogonal to each other. Apparently, the magnetic field detection directions of the magnetic elements are orthogonal to each other.

The three-axis magnetic sensor according to one aspect of the present invention includes a magnetic element that detects magnetic fields in the directions of the X axis, the Y axis, and the Z axis that are orthogonal to each other, and a signal for the detection result from each magnetic element. A signal processing unit that performs processing, and the signal processing unit realizes the above-described error compensation method.

A sensor module according to an aspect of the present invention includes the above-described three-axis magnetic sensor, a detection unit that detects a dip and declination of geomagnetism, and an inclination angle, and information from the three-axis magnetic sensor and the detection unit. And a signal processing unit for calculating an azimuth angle.

An error factor determination program according to an aspect of the present invention is a three-axis magnetic sensor including three magnetic elements that detect magnetic fields in directions of the X axis, the Y axis, and the Z axis orthogonal to each other. Output value from each magnetic element when the magnetic field applying means applies a magnetic field in the X-axis direction, and output from each magnetic element when the three-axis magnetic field applying means applies a magnetic field in the Y-axis direction Three space vectors representing the magnetic field detection direction of the three-axis magnetic sensor based on the value and the output value from each magnetic element when the three-axis magnetic field applying means applies a magnetic field in the Z-axis direction; The procedure for calculating each space vector representing the magnetic field detection direction of each of the three magnetic elements, and the mutual angle between the space vectors for the three space vectors representing the magnetic field detection direction of the three-axis magnetic sensor, respectively. And for each space vector representing the magnetic field detection direction of each of the three magnetic elements, a procedure for calculating an intersection angle between the space vectors, a magnetic field application direction by the three-axis magnetic field applying means, Whether the magnetic field detection direction of the magnetic element and the magnetic field detection direction of the three-axis magnetic sensor coincide with each other, three intersection angles of the magnetic field detection directions of the magnetic elements and three magnetic field detection directions of the three-axis magnetic sensor Based on whether or not the crossing angles coincide with each other, whether the cause of the error included in the azimuth angle to be obtained is due to the mounting state of each magnetic element, the magnetic field application direction by the three-axis magnetic field application means, and the three-axis Whether the magnetic sensor is due to a mismatch in the magnetic field detection direction of each magnetic element, due to inconsistency in the sensitivity of each magnetic element, or a combination thereof A procedure for determining whether it is fit, is executed.

According to the error factor determination method and apparatus according to an embodiment of the present invention, it is possible to determine the error factor included in the measured and calculated azimuth angle.
According to the error compensation method, the three-axis magnetic sensor, and the sensor module according to an aspect of the present invention, the azimuth can be accurately determined by canceling the error.

The flowchart which shows the procedure of the error factor determination method in the triaxial magnetic sensor which concerns on the 1st Embodiment of this invention. The flowchart which shows the detail of the process of step S1. The flowchart which shows the detail of the process of step S2. The flowchart which shows the detail of a process of step S3. The flowchart which shows the detail of the process of step S4. The flowchart which shows the detail of a process of step S5. The flowchart which shows the detail of a process of step S6. The figure which shows the table | surface of a magnetic element (sensor) output value. The figure which shows the table | surface of a magnetic element (sensor) output value. The table | surface which shows the measurement calculation result corresponding to the combination of a state (a) thru | or a state (c). The figure for demonstrating the state (A) and (B) of the triaxial magnetic sensor 1 shown in FIG. The figure which shows the relationship between a magnetic field application direction (solid line), the magnetic field detection method (dotted line) of an element, and the magnetic field detection direction (one-dot chain line) of a triaxial magnetic sensor. The figure which shows the relationship between a magnetic field application direction (solid line), the magnetic field detection method (dotted line) of an element, and the magnetic field detection direction (one-dot chain line) of a triaxial magnetic sensor. The figure which shows the relationship between a magnetic field application direction (solid line), the magnetic field detection method (dotted line) of an element, and the magnetic field detection direction (one-dot chain line) of a triaxial magnetic sensor. The figure which shows the relationship between a magnetic field application direction (solid line), the magnetic field detection method (dotted line) of an element, and the magnetic field detection direction (one-dot chain line) of a triaxial magnetic sensor. The figure which shows the relationship between a magnetic field application direction (solid line), the magnetic field detection method (dotted line) of an element, and the magnetic field detection direction (one-dot chain line) of a triaxial magnetic sensor. The figure for demonstrating the orthogonal coordinate axis set to a portable electronic device. The figure for demonstrating the orthogonal coordinate axis set to a portable electronic device. The figure for demonstrating a dip and a declination. The figure which shows the logical structure of the sensor module which can detect each magnetic field of a triaxial direction, and can calculate it with the dip angle, deflection angle, and inclination angle which detected them, and can obtain | require an azimuth | direction. The figure which shows the physical structure of the triaxial magnetic sensor 1 shown in FIG. The figure which shows the physical structure of the triaxial magnetic sensor 1 shown in FIG. The figure for demonstrating a 1st error factor. The figure for demonstrating a 1st error factor.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
In the error factor determination method in the three-axis magnetic sensor according to the first embodiment of the present invention, first, a coil that can apply a uniform magnetic field in three orthogonal axes (hereinafter referred to as “three-axis Helmholtz coil”), etc. Thus, an environment capable of generating an arbitrary uniform magnetic field in a specific spatial region with respect to the orthogonal three-axis directions is prepared, and the three-axis magnetic sensor 1 is installed in the environment. In a 3-axis Helmholtz coil, it is possible to generate an arbitrary magnetic field in each coil to adjust the magnetic field of the surrounding environment to form an environment under a desired magnetic field strength (hereinafter referred to as “no magnetic field environment”). However, in this embodiment, since magnetic sensitivity is measured, it is not always necessary to form a magnetic field-free environment.

FIG. 1 is a flowchart showing a procedure of an error factor determination method in the three-axis magnetic sensor according to the first embodiment of the present invention.
In FIG. 1, first, output values from magnetic elements 11X, 11Y, and 11Z for magnetic field detection in the X-axis, Y-axis, and Z-axis directions when a magnetic field is applied in the X-axis direction of the 3-axis Helmholtz coil are read ( Step S1).

FIG. 2 is a flowchart showing details of the processing in step S1. In FIG. 2, first, a variable n that defines the number of data acquisition is initialized (n = 0) (step S11).
Next, data is acquired for (nmax + 1) magnetic fields Hx while increasing the strength of the magnetic field Hx (steps S11 to S15). At this time, the initial value of the magnetic field is set to Hx (start), and the increment is set to Hx (step).

Specifically, for the first time from the magnetic field Hx (start) (step S12), output values from the magnetic elements 11X, 11Y, and 11Z are read (step S13). Next, 1 is added to n for the next strength (step S14), and it is determined whether n is smaller than a predetermined number nmax (step S15). If n is smaller than the predetermined number nmax, the process returns to step S12, increments Hx (step) are added, and steps S13 and S14 are repeated. If n is equal to the predetermined number nmax in step S15, data acquisition has been completed for the predetermined number (nmax + 1) of magnetic fields, and the process proceeds to step S16.
In steps S16 to S19, contrary to steps S12 to S15, the magnetic field intensity is decreased by Hx (step), and the output values from the magnetic elements 11X, 11Y, and 11Z are read. The details, such as determination of the number of data, are the same as in the case of increasing.

By the processing in step S1, X1 (i), X2 (i), X3 (i) (i = 0 to nmax) in the table of FIG. 8, and X1 (i), Y1 (i), Z1 (i) (i = 0 to nmax) is obtained. More specifically, the output values from the magnetic elements 11X, 11Y, and 11Z for magnetic field detection in the X, Y, and Z directions when an arbitrary magnetic field is applied to the X-axis of the 3-axis Helmholtz coil, and the 3-axis Helmholtz The respective output values from the magnetic element 11X for detecting the magnetic field in the X direction when an arbitrary magnetic field is applied to the X axis, Y axis, and Z axis of the coil are obtained.

Returning to FIG. 1, next, output values from the magnetic elements 11X, 11Y, and 11Z for magnetic field detection in the X, Y, and Z directions when a magnetic field is applied in the Y-axis direction of the three-axis Helmholtz coil are read (steps). S2).
FIG. 3 is a flowchart showing details of the process in step S2. In FIG. 3, first, a variable n that defines the number of data acquisition is initialized (n = 0) (step S21).
Next, data is acquired for (nmax + 1) magnetic fields Hy while increasing the strength of the magnetic field Hy (steps S21 to S25). At this time, the initial value of the magnetic field is Hy (start), and the increment is Hy (step).

Specifically, the output values from the magnetic elements 11X, 11Y, and 11Z are read for the first time from the magnetic field Hy (start) (step S22) (step S23). Next, 1 is added to n for the next intensity (step S24), and it is determined whether n is smaller than a predetermined number nmax (step S25). If n is smaller than the predetermined number nmax, the process returns to step S22, the increment Hy (step) is added, and steps S23 and S24 are repeated. If n is equal to the predetermined number nmax in step S25, data acquisition is completed for the predetermined number (nmax + 1) of magnetic fields, and the process proceeds to step S26.

In steps S26 to S29, contrary to steps S22 to S25, the magnetic field intensity is decreased by Hy (step), and the output values from the magnetic elements 11X, 11Y, and 11Z are read. The details, such as determination of the number of data, are the same as in the case of increasing.
By the processing of step S2, Y1 (i), Y2 (i), Y3 (i) (i = 0 to nmax) in the table of FIG. 8, and X2 (i), Y2 (i), Z2 (i) (i = 0 to nmax) is obtained. More specifically, the output values from the magnetic elements 11X, 11Y, and 11Z for magnetic field detection in the X, Y, and Z directions when an arbitrary magnetic field is applied to the Y-axis of the 3-axis Helmholtz coil, and the 3-axis Helmholtz The respective output values from the magnetic elements 11Y for magnetic field detection in the Y direction when an arbitrary magnetic field is applied to the X axis, Y axis, and Z axis of the coil are obtained.

Returning to FIG. 1, next, output values from the magnetic elements 11X, 11Y, and 11Z for magnetic field detection in the X, Y, and Z directions when a magnetic field is applied in the Z-axis direction of the three-axis Helmholtz coil are read (steps). S3).
FIG. 4 is a flowchart showing details of the process in step S3. In FIG. 4, first, a variable n that defines the number of data acquisition is initialized (n = 0) (step S31).
Next, data is acquired for (nmax + 1) magnetic fields Hz while increasing the strength of the magnetic field Hz (steps S31 to S35). At this time, the initial value of the magnetic field is set to Hz (start), and the increment is set to Hz (step).

Specifically, for the first time from the magnetic field Hz (start) (step S32), the output values from the magnetic elements 11X, 11Y, and 11Z are read (step S33). Next, 1 is added to n for the next intensity (step S34), and it is determined whether n is smaller than a predetermined number nmax (step S35). If n is smaller than the predetermined number nmax, the process returns to step S32, increments Hy (step) is added, and steps S33 and S34 are repeated. If n is equal to the predetermined number nmax in step S35, data acquisition has been completed for the predetermined number (nmax + 1) of magnetic fields, and the process proceeds to step S36.

In steps S36 to S39, contrary to steps S32 to S35, the intensity of the magnetic field is decreased by Hz (step) and the output values from the magnetic elements 11X, 11Y, and 11Z are read. The details, such as determination of the number of data, are the same as in the case of increasing.
By the processing of step S3, Z1 (i), Z2 (i), Z3 (i) (i = 0 to nmax) in the table of FIG. 8, and X3 (i), Y3 (i), Z3 (i) (i = 0 to nmax) is obtained. More specifically, the output values from the magnetic elements 11X, 11Y, and 11Z for magnetic field detection in the X, Y, and Z directions when an arbitrary magnetic field is applied to the Z-axis of the 3-axis Helmholtz coil, and the 3-axis Helmholtz The respective output values from the magnetic elements 11Z for magnetic field detection in the Z direction when an arbitrary magnetic field is applied to the X axis, Y axis, and Z axis of the coil are obtained.

Returning to FIG. 1, next, space vectors Xm, Ym, Zm are calculated from the magnetic element (sensor) output values in the table of FIG. 8 (step S4).
FIG. 5 is a flowchart showing details of the process in step S4.
First, the space vector Xm is calculated from the output values X1 (i), Y1 (i), Z1 (i) (i = 0 to nmax) in the table of FIG. 8 (step S41). Specifically, a least square approximation line is determined from the output values X1 (i), Y1 (i), Z1 (i) (i = 0 to nmax), and the direction vector of the least square approximation line is defined as a space vector Xm. decide.
Next, the space vector Ym is calculated from the output values X2 (i), Y2 (i), Z2 (i) (i = 0 to nmax) in the table of FIG. 8 (step S42). Specifically, a least square approximation line is determined from the output values X2 (i), Y2 (i), Z2 (i) (i = 0 to nmax), and the direction vector of the least square approximation line is defined as a space vector Ym. decide.
Next, the space vector Zm is calculated from the output values X3 (i), Y3 (i), Z3 (i) (i = 0 to nmax) in the table of FIG. 8 (step S43). Specifically, a least square approximation line is determined from the output values X3 (i), Y3 (i), Z3 (i) (i = 0 to nmax), and the direction vector of the least square approximation line is defined as a space vector Zm. decide.
The space vectors Xm, Ym, and Zm thus obtained are the magnetic field detection directions (hereinafter referred to as the three magnetic elements 11X, 11Y, and 11Z in the three-axis magnetic sensor 1 when a magnetic field is applied in the specific magnetic field generation direction. , Which are referred to as “magnetic field detection direction of the three-axis magnetic sensor”).

Returning to FIG. 1, next, space vectors Xe, Ye, and Ze are calculated from the magnetic element (sensor) output values in the table of FIG. 9 (step S5).
FIG. 6 is a flowchart showing details of the process in step S5.
First, the space vector Xe is calculated from the output values X1 (i), Y1 (i), Z1 (i) (i = 0 to nmax) in the table of FIG. 9 (step S51). Specifically, a least square approximation line is determined from the output values X1 (i), Y1 (i), Z1 (i) (i = 0 to nmax), and the direction vector of the least square approximation line is defined as a space vector Xe. decide.
Next, the space vector Ye is calculated from the output values X2 (i), Y2 (i), Z2 (i) (i = 0 to nmax) in the table of FIG. 9 (step S52). Specifically, a least square approximation line is determined from the output values X2 (i), Y2 (i), Z2 (i) (i = 0 to nmax), and the direction vector of the least square approximation line is defined as a space vector Ye. decide.
Next, the space vector Ze is calculated from the output values X3 (i), Y3 (i), Z3 (i) (i = 0 to nmax) in the table of FIG. 9 (step S43). Specifically, a least square approximation line is determined from the output values X3 (i), Y3 (i), Z3 (i) (i = 0 to nmax), and the direction vector of the least square approximation line is defined as a space vector Ze. decide.
The space vectors Xe, Ye, Ze obtained in this way are the magnetic field detection directions (hereinafter referred to as the individual magnetic elements 11X, 11Y, 11Z) of the three-axis magnetic sensor 1 when a magnetic field is applied in a specific magnetic field generation direction. , “Referred to as“ magnetic field detection direction of the element ”).

The relationship between the obtained space vectors Xm, Ym, Zm, Xe, Ye, Ze and the magnetic field application direction (Hx, Hy, Hz) is shown, for example, in FIGS. .
Returning to FIG. 1, next, the mutual angles between the vectors are calculated for the space vectors Xm, Ym, and Zm, and the mutual angles between the vectors are calculated for the space vectors Xe, Ye, and Ze, respectively (step) S6).

FIG. 7 is a flowchart showing details of the process in step S6.
First, for each of the space vectors Xm, Ym, Zm, the mutual angle between the vectors is calculated (step S61). That is, if the intersection angle θmxy between the space vector Xm and the space vector Ym, the intersection angle θmyz between the space vector Ym and the space vector Zm, and the intersection angle θmzzx between the space vector Zm and the space vector Xm are defined, ) To (3) are satisfied.

Next, with respect to the space vectors Xe, Ye, Ze, the mutual angle between the vectors is calculated (step S62). That is, when the intersection angle θexy between the space vector Xe and the space vector Ye, the intersection angle θeyz between the space vector Ye and the space vector Ze, and the intersection angle θezx between the space vector Ze and the space vector Xe are defined, ) To (6) are satisfied.

In the present invention, whether the magnetic field application direction by the triaxial Helmholtz coil, the magnetic field detection direction of the element, and the magnetic field detection direction of the triaxial magnetic sensor coincide with each other, and the magnetic field detection direction of the element obtained as described above. By verifying whether the three crossing angles and the three crossing angles in the magnetic field detection direction of the three-axis magnetic sensor coincide with each other, whether the cause of the error is due to the mounting state of each magnetic element, the magnetic field application direction It is possible to determine whether it is due to a mismatch between the magnetic field detection directions and the magnetic field detection direction, due to inconsistency in sensitivity of the magnetic elements, or a combination thereof.

This will be described in more detail below.
Here, for convenience of explanation, a state where the magnetic field application direction and the magnetic field detection direction coincide with each other is “state (a)”, and a case where the magnetic field detection directions of the magnetic elements 11X, 11Y, and 11Z are orthogonal to each other. (B) ”, a case where the magnetic sensitivities of the magnetic elements 11X, 11Y, and 11Z are the same is referred to as“ state (c) ”. If these events are independent from each other, there are eight combinations, but since they are not independent from each other, there are combinations that are not possible in reality.

FIG. 10 shows measurement calculation results corresponding to the combinations of the states (a) to (c), that is, the coincidence between the magnetic field detection direction of the element and the magnetic field detection direction of the three-axis magnetic sensor, and the magnetic field detection direction of the element. It is a figure which shows as a table | surface the three intersection angles and the coincidence of the three intersection angles of the magnetic field detection direction of a 3-axis magnetic sensor. FIG. 11 is a diagram for explaining the states (A) and (B) of the triaxial magnetic sensor 1 shown in FIG. In FIG. 10, in the data column ○, when they match, the ○ in the status (a) to (c) columns indicates that the status is in that state.

Hereinafter, the states (A) to (G) of the three-axis magnetic sensor 1 shown in FIG. 10 will be described in order. For convenience of explanation, the magnetic field application direction is “direction (1)”, the magnetic field detection direction of the element is “direction (2)”, and the magnetic field detection direction of the triaxial magnetic sensor is “direction (3)”.
12 to 16 are diagrams showing the relationship between the magnetic field application direction (solid line), the magnetic field detection method of the element (dotted line), and the magnetic field detection direction of the three-axis magnetic sensor (dashed line).

First, the state (A) of the three-axis magnetic sensor 1 shown in FIG. 10 is obtained when the direction (2) and the direction (3) are the same, that is, the vector Xm and the vector Xe, and the vector Ym and the vector. Ye, when the vector Zm and the vector Ze match in direction and magnitude, and the crossing angle of each vector matches between the direction (2) and the direction (3), that is, The crossing angle of Xm and Ym and the crossing angle of Xe and Ye, the crossing angle of Ym and Zm and the crossing angle of Ye and Ze, the crossing angle of Zm and Xm and the crossing angle of Ze and Xe are the same, and the values shown in FIG. This is the case where a = b = c = 0 for a, b and c.

In this case, as shown in the table of FIG. 10, the states (a) to (c) are all satisfied. That is, as shown in FIG. 12, the magnetic field application direction, the magnetic field detection direction of the element, and the magnetic field detection direction of the triaxial magnetic sensor coincide with each other, and the magnetic field detection directions of the elements are orthogonal to each other. It is the same. In other words, it can be seen that an output without an azimuth error is obtained from the three-axis magnetic sensor 1 as a measurement result, and the magnetic sensitivities of the elements 11X, 11Y, and 11Z are accurately measured. That is, since the triaxial magnetic sensor 1 is appropriately installed in the magnetic field generated by the triaxial Helmholtz coil and there is no absolute error and relative error in assembly, the magnetic sensitivity is accurately measured, and each element 11X, 11Y, It can be seen that this is an ideal state where the magnetic sensitivity of 11Z is the same.

Next, in the state (B) shown in FIG. 10, the direction (2) and the direction (3) are the same according to the measurement calculation result, that is, the vector Xm and the vector Xe, the vector Ym and the vector Ye, and the vector Zm and the vector. Each of Ze matches in direction and size, and the crossing angle of each vector matches between direction (2) and direction (3), that is, the crossing angle of Xm and Ym The crossing angle of Xe and Ye, the crossing angle of Ym and Zm and the crossing angle of Ye and Ze, the crossing angle of Zm and Xm, and the crossing angle of Ze and Xe are the same, but the values a, b, and c shown in FIG. a = b = c = 0 is not satisfied.

In this case, as shown in the table of FIG. 10, the states (b) and (c) are satisfied, but the state (a) is not satisfied. That is, the magnetic field detection direction of each element is orthogonal to each other, and the magnetic sensitivity of each element is the same. As shown in FIG. 13, the magnetic field detection direction of the element and the magnetic field detection direction of the three-axis magnetic sensor are one. This is the case when they do not match the magnetic field application direction. In other words, there is no absolute or relative error in assembly, but due to a deviation in the installation position of the triaxial magnetic sensor 1 with respect to the magnetic field application direction or a deviation in the mounting of the element with respect to the mounting substrate 13 of the triaxial magnetic sensor 1 This is a case where an error occurs in the measurement of the magnetic sensitivity of the magnetic elements 11X, 11Y, and 11Z.

By the way, in practice, a measurement error (hereinafter referred to as an “installation position error”) due to an installation position deviation of the triaxial magnetic sensor 1 in a predetermined magnetic field detection direction with respect to the magnetic field application direction, and the triaxial magnetic sensor 1 In many cases, both of measurement errors due to mounting deviations of the respective elements 11X, 11Y, and 11Z with respect to the mounting substrate 13 are included. In this case, it has been difficult for the conventional technique to distinguish and evaluate an error in installation position, an absolute error in assembly, a relative error in assembly, and an error due to a difference in magnetic sensitivity of each magnetic element.

Here, in the case of the state (B) in the table of FIG. 10, it can be seen that at least the sensitivities of the magnetic elements 11X, 11Y, and 11Z in the three-axis magnetic sensor 1 to be measured are the same. In addition, when the intersection angle of Xe and Ye, the intersection angle of Ye and Ze, and the intersection angle of Ze and Xe are right angles, that is, when there is no relative error in assembly, Xm and Xe, Ym and Ye, Zm and Each of Ze matches in direction and size. In this case, based on the intersection angle of Hz and Xe, the intersection angle of Hy and Ye, and the intersection angle of Hz and Ze, an error including both an installation position error and an assembly absolute error can be defined. The error in the installation position depends on the installation method of the 3-axis magnetic sensor 1 to be measured with respect to the 3-axis Helmholtz coil, and the error can be reduced as much as possible by using a method with high alignment accuracy. On the other hand, the absolute error in assembly forms electrical connections between the magnetic elements 11 and the signal processing unit 12 in addition to the alignment accuracy of the mounting substrate 13 and the magnetic elements 11X, 11Y, and 11Z. In addition, when performing surface mounting using a solder ball or the like, the parallelism between the mounting substrate 13 surface and the magnetic sensitive surface of each element 11 depends on the height of each solder ball. Therefore, since the absolute error in assembly is larger than the error in installation position, in practice, the error evaluated by the present invention can be considered as an absolute error in assembly in many cases.

In the case of the state (B) in the table of FIG. 10, when any of the intersection angle of Xe and Ye, the intersection angle of Ye and Ze, and the intersection angle of Ze and Xe is not orthogonal, each element 11X, 11Y, At least one of the crossing angles in the magnetic field detection direction of 11Z is not orthogonal, but the magnetic sensitivities of the magnetic elements 11X, 11Y, and 11Z in the magnetic field detection direction are the same. Therefore, it can be seen that there is no deviation in the magnetic sensitivities of the magnetic elements 11X, 11Y, and 11Z, but there is an absolute error in assembly.

Next, in the state (C) shown in FIG. 10, the direction (2) and the direction (3) are not the same according to the measurement calculation result, and each vector between the direction (2) and the direction (3) This is a case where at least one of the intersection angles does not match, but the three intersection angles in the direction (2) are 90 degrees.
In this case, as shown in the table of FIG. 10, the states (a) and (b) are satisfied, but the state (c) is not satisfied. That is, as shown in FIG. 14, although the magnetic field application direction and the magnetic field detection direction of the element coincide with each other, they do not coincide with the magnetic field detection direction of the three-axis magnetic sensor. The directions are perpendicular to each other, but the magnetic sensitivities of the elements are not the same.

Next, in the state (D) illustrated in FIG. 10, the direction (2) and the direction (3) are not the same (at least one of the vectors does not match) according to the measurement calculation result, but the direction (2) and the direction (3 ), The crossing angles of the respective vectors coincide, that is, the crossing angle of Xm and Ym and the crossing angle of Xe and Ye, the crossing angle of Ym and Zm and the crossing angle of Ye and Ze, and the crossing angle of Zm and Xm This is a case where the intersection angles of Ze and Xe are the same.
In this case, as shown in the table of FIG. 10, only the state (c) is satisfied. That is, as shown in FIG. 15, the magnetic field application direction, the magnetic field detection direction of the element, and the magnetic field detection direction of the triaxial magnetic sensor do not coincide with each other, and the magnetic field detection directions of the elements are orthogonal to each other. However, this is a case where each element has the same magnetic sensitivity.

Next, in the state (E) shown in FIG. 10, the direction (2) and the direction (3) are not the same (at least one of the vectors does not match), and the direction (2) and the direction ( 3), at least one of the intersection angles of each vector does not match, and at least one of the three intersection angles in the direction (2) is not 90 degrees.
In this case, as shown in the table of FIG. 10, none of the state (a), the state (b), and the state (c) is satisfied. That is, as shown in FIG. 16, the magnetic field application direction, the magnetic field detection direction of the element, and the magnetic field detection direction of the triaxial magnetic sensor do not coincide with each other, and the magnetic field detection directions of the elements are orthogonal to each other. This is a case where the magnetic sensitivities of the elements are not the same. In other words, in addition to the installation position shift of the triaxial magnetic sensor 1 with respect to the magnetic field application direction, it means that accurate magnetic sensitivity measurement of each element cannot be performed due to the mounting displacement of the element with respect to the mounting board of the triaxial magnetic sensor. is doing. The state of FIG. 15 differs from the state of FIG. 16 only in whether the magnetic sensitivities of the respective elements are the same or not the same.
Since it is assumed that the magnetic field application directions are orthogonal to each other, the state (F) and the state (G) in the table of FIG. 10 are combinations that cannot be taken.

As described above, as a means for obtaining information on an installation position error, a relative error in assembly, an absolute error in assembly, and a deviation in magnetic sensitivity of each magnetic element with respect to the magnetic field detection direction of the three-axis magnetic sensor 1, A technique using the magnetic field detection direction of the element and the magnetic field detection direction of the three-axis magnetic sensor is useful.

Next, a method for compensating for an actual error caused by the above-described determined error factor will be described.
That is, if the error factor includes that the state (b) is not satisfied, that is, if the magnetic field detection directions of the elements are not orthogonal to each other, this is compensated by adjusting the sensitivity.

More specifically, in the assembly process of the triaxial magnetic sensor 1, it is ideal that the magnetic field detection directions of the magnetic elements are orthogonally orthogonal. However, in the actual assembly process, for each individual triaxial magnetic sensor 1 There will be some deviation in orthogonality. Therefore, when it is determined by the above-described method that the magnetic field detection directions of the respective elements are not orthogonal to each other, the signal processing unit 12 in FIG. 19 intentionally adjusts the magnetic sensitivity of each magnetic element, Apparently, the magnetic field detection directions of the respective elements are orthogonal to each other, and the three-axis magnetic sensor can be optimally adjusted. The confirmation of orthogonality can be determined from the inner product of vectors in the magnetic field detection direction of the three-axis magnetic sensor.

As described above, the signal processing unit 3 uses the calculation result from the signal processing unit 12 and the crossing angle of the magnetic field detection direction of the triaxial magnetic sensor and the geomagnetic direction to each component of the magnetic field detection direction of the triaxial magnetic sensor with respect to the geomagnetism. The magnetic field strength is calculated in consideration of the dip and declination of geomagnetism and the inclination angle of the portable electronic device, and the azimuth is derived.
For example, when the sensor module is mounted on a portable electronic device, the detection unit 2 detects the dip and declination of geomagnetism and the inclination angle of the portable electronic device, and the signal processing unit 3 detects the triaxial magnetic sensor 1. In addition, it is possible to obtain accurate azimuth information that does not depend on the inclination of the portable electronic device by performing calculation on the information from the detection unit 2.

At this time, it is desirable to install the triaxial magnetic sensor 1 on the portable electronic device so that the magnetic field detection direction of the triaxial magnetic sensor and the magnetic field instruction direction of the portable electronic device are parallel to each other.
According to this method, when there is an absolute error in assembly, the magnetic field detection directions of the magnetic elements are not orthogonal to each other, but the magnetic field detection directions of the three-axis magnetic sensor can be orthogonal to each other by arithmetic processing. By using the magnetic field detection direction of the triaxial magnetic sensor instead of the magnetic field detection direction of each element, it is possible to detect the direction without any direction error.

Normally, the azimuth is calculated with the magnetic field strengths in the X-axis direction and the Y-axis direction of the portable electronic device, but depending on the inclination angle of the portable electronic device, among the X-axis direction, the Y-axis direction, and the Z-axis direction, The direction in which the azimuth is calculated using any two-axis magnetic field strength may be used.

The present invention can be applied to a sensor module and a portable electronic device equipped with the sensor module.

DESCRIPTION OF SYMBOLS 1 3-axis magnetic sensor 2 Detection part 3 Signal processing part 11X Magnetic element 11Y Magnetic element 11Z Magnetic element 12 Signal processing part 13 Mounting board 50 Sensor module 100 Portable electronic device.

Claims (6)

1. When a three-axis magnetic field applying unit that applies a magnetic field to a three-axis magnetic sensor having three magnetic elements that detect magnetic fields in the X-axis, Y-axis, and Z-axis directions orthogonal to each other applies a magnetic field in the X-axis direction. Output values from the magnetic elements, output values from the magnetic elements when the triaxial magnetic field applying means applies a magnetic field in the Y-axis direction, and triaxial magnetic field applying means in the Z-axis direction. Each of the three space vectors representing the magnetic field detection direction of the three-axis magnetic sensor and the magnetic field detection directions of the three magnetic elements based on the output values from the magnetic elements when a magnetic field is applied to the magnetic field. Calculating a space vector;
   For each of the three space vectors representing the magnetic field detection direction of the three-axis magnetic sensor, the intersection angle between the three space vectors is calculated, and for each space vector representing the magnetic field detection direction of the three magnetic elements, respectively. Calculating each other's intersection angle between the space vectors;
   Three crossing angles of the magnetic field application direction by the three-axis magnetic field applying means, the magnetic field detection direction of each magnetic element, and whether or not the magnetic field detection direction of the three-axis magnetic sensor coincide with each other, and the magnetic field detection direction of each magnetic element And whether or not the three intersection angles in the magnetic field detection direction of the three-axis magnetic sensor coincide with each other, whether the cause of the error included in the azimuth angle to be obtained is due to the mounting state of each magnetic element, Whether the magnetic field application direction by the three-axis magnetic field applying means and the magnetic field detection direction of the three-axis magnetic sensor and each magnetic element are inconsistent, the sensitivity of each magnetic element is inconsistent, or Determining whether it is a combination; and
   An error factor determination method for a three-axis magnetic sensor.
2. A three-axis magnetic sensor having three magnetic elements for detecting magnetic fields in the X-axis, Y-axis, and Z-axis directions orthogonal to each other, and a three-axis magnetic field applying unit that applies a magnetic field to the three-axis magnetic sensor. An error factor determination device,
   The three-axis magnetic sensor
   When the three-axis magnetic field applying means applies a magnetic field in the X-axis direction, the output value from each magnetic element for magnetic field detection in the X-axis, Y-axis, and Z-axis directions, and the three-axis magnetic field applying means is the Y-axis. Based on the output value from each magnetic element when a magnetic field is applied in the direction and the output value from each magnetic element when the three-axis magnetic field applying means applies a magnetic field in the Z-axis direction, Three space vectors representing the magnetic field detection directions of the three-axis magnetic sensor are calculated, and three space vectors representing the magnetic field detection directions of the three-axis magnetic sensor are calculated. And calculating each other's crossing angle between the three space vectors, and calculating each other's crossing angle between the space vectors for each space vector representing the magnetic field detection direction of the three magnetic elements. The magnetic field application direction by the three-axis magnetic field applying means, the magnetic field detection direction of each magnetic element, and whether or not the magnetic field detection direction of the three-axis magnetic sensor coincide with each other, and the magnetic field detection direction of each magnetic element. Based on whether or not the intersection angle and the three intersection angles of the magnetic field detection direction of the three-axis magnetic sensor coincide with each other, whether the cause of the error included in the azimuth angle to be obtained is due to the mounting state of each magnetic element, Whether the magnetic field application direction by the three-axis magnetic field applying means is inconsistent with the magnetic field detection direction of the three-axis magnetic sensor and each magnetic element, the sensitivity of each magnetic element is inconsistent, or a combination thereof An error factor determination device comprising a signal processing unit for determining whether or not
3. When it is determined by the error factor determination method according to claim 1 that the magnetic field detection directions of the magnetic elements are not orthogonal to each other, by adjusting the magnetic sensitivity of the magnetic elements, apparently, An error compensation method for a three-axis magnetic sensor, wherein magnetic field detection directions of the magnetic elements are orthogonal to each other.
4. 3 provided with three magnetic elements that detect magnetic fields in the directions of the X axis, the Y axis, and the Z axis that are orthogonal to each other, and a signal processing unit that performs signal processing on detection results from the respective magnetic elements. An axial magnetic sensor,
   The three-axis magnetic sensor, wherein the signal processing unit realizes the error compensation method according to claim 3.
5. A triaxial magnetic sensor according to claim 4;
   A detection unit for detecting a dip and declination of geomagnetism and an inclination angle;
   A signal processing unit for calculating an azimuth angle based on information from the three-axis magnetic sensor and the detection unit;
   A sensor module comprising:
6. A three-axis magnetic sensor including three magnetic elements that detect magnetic fields in the directions of the X axis, the Y axis, and the Z axis orthogonal to each other.
   Output values from the magnetic elements when the triaxial magnetic field applying means applies a magnetic field in the X-axis direction, and from the magnetic elements when the triaxial magnetic field applying means applies a magnetic field in the Y-axis direction. And three spaces representing the magnetic field detection direction of the three-axis magnetic sensor based on the output value from the magnetic elements when the three-axis magnetic field applying means applies a magnetic field in the Z-axis direction. Calculating a vector and each space vector representing the magnetic field detection direction of each of the three magnetic elements;
   For the three space vectors representing the magnetic field detection directions of the three-axis magnetic sensor, the mutual angle between the three space vectors in the previous period is calculated, and for each space vector representing the magnetic field detection directions of the three magnetic elements, A procedure for calculating an intersection angle between the space vectors,
   Three crossing angles of the magnetic field application direction by the three-axis magnetic field applying means, the magnetic field detection direction of each magnetic element, and whether or not the magnetic field detection direction of the three-axis magnetic sensor coincide with each other, and the magnetic field detection direction of each magnetic element And whether or not the three intersection angles in the magnetic field detection direction of the three-axis magnetic sensor coincide with each other, whether the cause of the error included in the azimuth angle to be obtained is due to the mounting state of each magnetic element, Whether the magnetic field application direction by the three-axis magnetic field applying means and the magnetic field detection direction of the three-axis magnetic sensor and each magnetic element are inconsistent, the sensitivity of each magnetic element is inconsistent, or A procedure for determining whether it is a combination;
   An error factor determination program characterized by causing
   

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