JP5086225B2 - Calibration apparatus, method and program for magnetic direction sensor - Google Patents

Description

  The present invention is for adjusting the sensitivity of magnetic sensors of each axis when a two-dimensional or three-dimensional azimuth sensor is configured by combining a plurality of one-dimensional magnetic sensors that measure the magnetic strength in one direction. The present invention relates to a magnetic azimuth sensor calibration apparatus, method, and program for calculating parameters.

  When a one-dimensional azimuth sensor is rotated in a plane including a magnetic field direction in a parallel and uniform magnetic field, its output (measured value) changes in a sine wave shape according to the rotation angle. Since the magnitude of the output amplitude at this time is the sensitivity of the sensor to a given magnetic field, the reciprocal of this amplitude is called the sensor gain. The center value of the measured amplitude is called a sensor offset. Gain and offset are parameters unique to each sensor and must be accurately measured and calibrated.

When a two-dimensional or three-dimensional azimuth sensor is configured using a plurality of sensors, the outputs of the sensors cannot be combined unless these parameters are calibrated.
In calibration at the time of shipment of the sensor chip, the sensor can be calibrated by installing the sensor chip alone at an appropriate position and rotating the magnetic field by using a magnetism generator.
In addition to this calibration at the time of shipment, it is desirable to recalibrate the sensor chip in accordance with the usage situation in consideration of the environment of the place of use and the influence of the circuit incorporated at the same time.

  In general, calibration using a geomagnetism is performed in calibration in a use environment. In calibration using geomagnetism, a sensor is installed on a turntable that can rotate around the vertical axis so that it is parallel to the ground surface, and the geomagnetism is measured while rotating the sensor in a horizontal plane to obtain the gain and offset. . Such a calibration method using geomagnetism is disclosed in Non-Patent Document 1, for example.

“6-Axis G2 Motion Sensor Evaluation Kit AMI601-CG Instruction Manual”, Aichi Micro Intelligent Co., Ltd., <http: // www. aichi-mi. com / 3_products / 601-cgmanual_j. pdf>

  The calibration method disclosed in Non-Patent Document 1 assumes that the sensor can be installed horizontally with the ground surface. However, in the state in which the sensor is incorporated in the equipment case, the sensor and the equipment case are not necessarily parallel, and an error may occur in the mounting angle depending on the individual installation situation. It was not easy to rotate with.

  According to the present invention, on the assumption that the rotation surface for calibration and the sensor are not necessarily parallel, the sensor mounting angle with respect to the rotation surface can be obtained simultaneously in addition to the gain and offset which are the original parameters of the magnetic sensor. An object of the present invention is to realize a simple calibration method and to enable highly accurate calibration of a magnetic direction sensor in a user environment.

  The magnetic azimuth sensor calibration apparatus according to the present invention includes two or more different magnetic intensity measuring directions constituting the magnetic azimuth sensor when the two-dimensional or three-dimensional magnetic azimuth sensor rotates in a horizontal plane. Sensor observation value collection means for collecting observation values from three magnetic sensors, maximum value detection means for detecting the maximum value of observation values of each magnetic sensor, and minimum value for detecting the minimum value of observation values of each magnetic sensor With the detection means and one magnetic sensor as an attention sensor, the first observation value that is an observation value of each magnetic sensor when the attention sensor observes the maximum value and each of the observation values when the attention sensor observes the minimum value The second observation value, which is the observation value of the magnetic sensor, is obtained as each sensor of interest, and the difference between the first observation value and the second observation value is determined for each magnetic sensor. To calculate In addition, an inclination calculating means for calculating the inclination of each magnetic sensor with respect to the horizontal plane from the difference between the observed values, and a difference between the pre-given horizontal component of the geomagnetism and the inclination of each magnetic sensor calculated by the inclination calculating means and the observed value. From the gain calculation means for calculating the gain of each magnetic sensor, and the horizontal component of the geomagnetism and the dip angle that is the angle of the geomagnetic vector at the observation point with respect to the horizontal plane, the inclination of each magnetic sensor, and the gain of each magnetic sensor, And an offset calculating means for calculating an offset of the magnetic sensor.

により計算することを特徴とするものである。
また、本発明の磁気方位センサのキャリブレーション装置の１構成例において、予め与えられた地磁気の水平成分をＮ_Hとしたとき、前記ゲイン計算手段は、各磁気センサＳ_x，Ｓ_y，Ｓ_zのゲインｇａｉｎ_x，ｇａｉｎ_y，ｇａｉｎ_zを、２Ｎ_H＝ｇａｉｎ_xｘ_xdiff／ｃｏｓφ_x＝ｇａｉｎ_yｙ_ydiff／ｃｏｓφ_y＝ｇａｉｎ_zｚ_zdiff／ｃｏｓφ_zにより計算することを特徴とするものである。
また、本発明の磁気方位センサのキャリブレーション装置の１構成例において、前記観測地点の伏角をαとしたとき、前記オフセット計算手段は、各磁気センサＳ_x，Ｓ_y，Ｓ_zのオフセットｏｆｆｓｅｔ_x，ｏｆｆｓｅｔ_y，ｏｆｆｓｅｔ_zを、ｏｆｆｓｅｔ_x＝（ｘ_xmax＋ｘ_xmin）／２−Ｎ_Hｔａｎαｓｉｎφ_x／ｇａｉｎ_x、ｏｆｆｓｅｔ_y＝（ｙ_ymax＋ｙ_ymin）／２−Ｎ_Hｔａｎαｓｉｎφ_y／ｇａｉｎ_y、ｏｆｆｓｅｔ_z＝（ｚ_zmax＋ｚ_zmin）／２−Ｎ_Hｔａｎαｓｉｎφ_z／ｇａｉｎ_zにより計算することを特徴とするものである。
また、本発明の磁気方位センサのキャリブレーション装置の１構成例において、前記オフセット計算手段は、前記磁気方位センサの姿勢が異なる複数の状態の各々について各磁気センサＳ_x，Ｓ_y，Ｓ_zの観測値の最大値ｘ_xmax，ｙ_ymax，ｚ_zmaxおよび観測値の最小値ｘ_xmin，ｙ_ymin，ｚ_zminが得られ、前記複数の状態の各々について各磁気センサＳ_x，Ｓ_y，Ｓ_zの水平面に対する傾きφ_x，φ_y，φ_zが計算されたとき、（ｘ_xmax＋ｘ_xmin）／２＝Ａ_xｓｉｎφ_x＋Ｂ_x、（ｙ_ymax＋ｙ_ymin）／２＝Ａ_yｓｉｎφ_y＋Ｂ_y、（ｚ_zmax＋ｚ_zmin）／２＝Ａ_zｓｉｎφ_z＋Ｂ_zの関係から最小二乗法により係数Ｂ_x，Ｂ_y，Ｂ_zを計算し、この係数Ｂ_x，Ｂ_y，Ｂ_zを各磁気センサＳ_x，Ｓ_y，Ｓ_zのオフセットｏｆｆｓｅｔ_x，ｏｆｆｓｅｔ_y，ｏｆｆｓｅｔ_zとすることを特徴とするものである。 In one configuration example of the magnetic orientation sensor calibration apparatus according to the present invention, the magnetic orientation sensor includes three magnetic sensors S _x , S _y , S _z , and a sensor of interest S _u (S _u ε { _{S x, S y, S z} }) magnetic sensor when the observed maximum value _{S v (S v ∈ {S} x, S y, observed value v _umax of interest sensor S _u is the minimum value of S _z}) when the difference between the observed value v _umin magnetic sensor S _v when observed was v _Udiff, said slope calculating means, the magnetic sensors S _x, S _y, inclination phi _x with respect to the horizontal plane of the S _z, phi _y , Φ _z

It is characterized by calculating by.
Further, in one configuration example of the magnetic azimuth sensor calibration apparatus of the present invention, when the pre-given horizontal component of the geomagnetism is N _H , the gain calculation means includes the magnetic sensors S _x , S _y , S _z. The gains gain _x , gain _y , and gain _z are calculated by 2N _H = gain _x x _xdiff / cos φ _x = gain _y y _diff / cos φ _y = gain _z z _zdiff / cos φ _z .
Further, in one configuration example of the magnetic azimuth sensor calibration apparatus of the present invention, when the dip angle of the observation point is α, the offset calculating means is configured to offset the offset offset _{x of} each magnetic sensor S _x , S _y , S _z. , Offset _y , offset _z , offset _x = (x _xmax + x _xmin ) / 2−N _H tan αsin φ _x / gain _x , offset _y = (y _ymax + y _ymin ) / 2−N _H tan αsin φ _y / gain _y , offset _z = (Z _zmax + z _zmin ) / 2−N _H tan α sin φ _z / gain _z
Also, in one configuration example of the magnetic azimuth sensor calibration apparatus according to the present invention, the offset calculation means includes the magnetic sensors S _x , S _y , and S _z for each of a plurality of states in which the orientation of the magnetic azimuth sensor is different. Maximum values x _xmax , y _ymax , z _zmax of observation values and minimum values x _xmin , y _ymin , z _{zmin of} observation values are obtained, and for each of the plurality of states, each of the magnetic sensors S _x , S _y , S _z When the inclinations φ _x , φ _y , φ _z with respect to the horizontal plane are calculated, (x _xmax + x _xmin ) / 2 = A _x sin φ _x + B _x , (y _ymax + y _ymin ) / 2 = A _y sin φ _y + B _y , ( _{z zmax + z zmin) / 2} = a z sinφ z + B z factor B _x by the least square method from the relationship, B _y, and B _z calculated, the coefficient B _x, B _y, and B _z the magnetic sensor S _x , S _y, S _z of offset offset _x, offset _y, of It is characterized in that a The set _z.

  In addition, according to the calibration method of the magnetic direction sensor of the present invention, when the two-dimensional or three-dimensional magnetic direction sensor is rotating in the horizontal plane, the magnetic intensity measuring direction constituting the magnetic direction sensor is different. Sensor observation value collection procedure for collecting observation values from three or three magnetic sensors, maximum value detection procedure for detecting the maximum value of the observation values of each magnetic sensor, and detection of the minimum value of the observation values of each magnetic sensor Minimum value detection procedure, when one magnetic sensor is used as a target sensor, and when the target sensor observes the maximum value, the first observation value that is the observation value of each magnetic sensor and the target sensor observes the minimum value The second observation value, which is the observation value of each magnetic sensor, is determined as each sensor of interest, and the difference between the first observation value and the second observation value is determined magnetically. For each sensor An inclination calculation procedure for calculating and calculating the inclination of each magnetic sensor with respect to the horizontal plane from the difference between the observed values, and a predetermined horizontal component of geomagnetism and the inclination and observation value of each magnetic sensor calculated by the inclination calculation procedure. The gain calculation procedure for calculating the gain of each magnetic sensor from the difference between the horizontal direction, the dip angle that is the angle of the horizontal component of the geomagnetism and the geomagnetic vector at the observation point with respect to the horizontal plane, the inclination of each magnetic sensor, and the gain of each magnetic sensor. And an offset calculation procedure for calculating an offset of the magnetic sensor.

  ADVANTAGE OF THE INVENTION According to this invention, even if it is a case where each magnetic sensor which comprises a magnetic direction sensor inclines with respect to a horizontal surface, a magnetic direction sensor can be calibrated.

[Calibration using conventional technology]
First, before explaining the present embodiment, a magnetic direction sensor calibration method according to the prior art will be explained. As the coordinate system of the measurement point, the XY plane is determined so that the Z axis is taken upward in the vertical direction and is orthogonal to the Z axis. At this time, the XY plane is a horizontal plane parallel to the ground surface. With reference to a vector (geomagnetic vector) pointing to the magnetic north direction of the geomagnetism, the X axis is taken to be orthogonal to the Z axis in the north direction, and the Y axis is taken to be orthogonal to the X axis and the Z axis in the west direction.
In this coordinate system, the geomagnetic vector is a vector on the XZ plane. The angle between the geomagnetic vector and the horizontal plane (the ground surface) is called the dip angle.

Qualitatively, when a magnetic sensor placed in the XY plane is rotated around the Z axis, the measured value becomes maximum when the magnetic sensor faces the X axis positive direction (north), and the magnetic sensor is negative on the X axis. The measured value is minimum when facing the direction (south).
When the magnetic sensor placed in the XY plane is rotated around the Z axis, the angle formed by the magnetic sensor with respect to the positive direction of the X axis is defined as θ. Let N be the geomagnetic vector. This vector is divided into a Z-axis direction component and an X-axis direction component, the Z-axis direction component is N _Z , and the X-axis direction component (horizontal plane component) is N _H. If the dip angle of geomagnetism is α, N _Z = Nsin α and N _H = N cos α.

The observation value by the magnetic sensor is represented by x. Since x is a function of θ, it is expressed as x (θ) when discussing θ. As a parameter unique to the sensor, an offset value _x is set as an output value when there is no magnetic field, and a gain gain _x is set so that an appropriate output is obtained when the reference magnetism (N _C ) is observed. That is, the relationship between the observed value x and the offset, gain, and reference magnetism is determined as follows.
N _C = gain _x (x−offset _x ) (1)

From the equation (1), the observed value when an arbitrary magnetic N is observed is as follows.
x = N / gain _x + offset _x (2)
The observed value x (θ) when the magnetic sensor is rotated in the horizontal plane is as follows.
x (θ) = N _H cos θ / gain _x + offset _x (3)

The observed value is maximized when the magnetic sensor is facing north (θ = 0), and the observed value is minimized when the magnetic sensor is facing south (θ = π). The maximum value x _max and the minimum value x _min of the observed value x are as follows.
x _max = x (0) = N _H / gain _x + offset _x (4)
x _min = x (π) = − N _H / gain _x + offset _x (5)
From the equations (4) and (5), the gain gain _x and the offset offset _x can be obtained as follows.
offset _x = (x _max + x _min ) / 2 (6)
gain _x ⁻¹ = (x _max −x _min ) / 2N _H (7)

To actually determine the maximum value x _max and the minimum value x _min from the observed value at the time of rotating the magnetic sensor in a horizontal plane may be selected maximum value x _max and the minimum value x _min.
When considering three-axis magnetic sensors Sx, Sy, and Sz orthogonal to each other, if rotation is performed in the horizontal plane for each axis, calibration can be performed with three rotations. If two magnetic sensors (for example, Sx and Sy) can be installed in the horizontal plane at the same time, it is possible to perform calibration for all three axes by two rotations.

[Errors that occur when the sensor is tilted]
Next, a case where the magnetic sensor cannot be installed in the horizontal plane in the conventional calibration method will be considered. The angle between the magnetic sensor and the horizontal plane is φ. The direction of the magnetic sensor is represented by two variables θ and φ.
Observation values x (θ, φ) by the magnetic sensor are as follows.
x (θ, φ) = N _H cos θ cos φ / gain _x + N _Z sin φ / gain _x
+ Offset _x (8)

The maximum value x _max and the minimum value x _min of the observed value x observed when the magnetic sensor is rotated in the horizontal plane are as follows.
x _max = x (0, φ) = N _H cos φ / gain _x + N _Z sin φ / gain _x
+ Offset _x (9)
x _min = x (π, φ) = − N _H cos φ / gain _x + N _Z sin φ / gain _x
+ Offset _x (10)

Here, ignoring the inclination φ of the magnetic sensor from the horizontal plane and obtaining the gain gain _x and the offset offset _x based on the equations (9) and (10), values including errors are obtained as follows. .
offset _x '= (x _max + x _min ) / 2 = offset _x + N _Z sin φ / gain _x
(11)
gain _x ′ ⁻¹ = (x _max −x _min ) / 2N _H = gain _x ⁻¹ cos φ (12)

In recent years, a triaxial magnetic sensor chip of about 5 mm square has been produced, but when such a chip is attached, if a difference of about 0.5 mm occurs at the height of both ends, an inclination of about 10 degrees occurs. It will be. This inclination corresponds to about sin φ = 0.2, and the offset error cannot be ignored.
Therefore, in a situation where the magnetic sensor cannot be installed in a horizontal plane, the conventional calibration method based on a model without an inclination cannot be applied.

[Inclined calibration model]
Next, a calibration method used in this embodiment will be described. Consider three-axis magnetic sensors S _x , S _y , and S _z that are orthogonal to each other. The magnetic sensors S _x , S _y , and S _z are one-dimensional magnetic sensors that measure the magnetic strength in the X, Y, and Z directions, respectively. The angles formed by the respective magnetic sensors S _x , S _y , S _{z and the} horizontal plane are φ _x , φ _y , φ _z (FIG. 1).

When a certain magnetic sensor S _u (S _u ε {S _x , S _y , S _z }) observes the maximum value, the observation values at the sensors S _x , S _y , S _z are respectively represented by x _umax , y _umax , It is expressed as z _umax . Similarly, when the magnetic sensor S _u (S _u ε {S _x , S _y , S _z }) observes the minimum value, the observed values at the sensors S _x , S _y , S _z are respectively x _umin , y. _umin and _zumin .

Difference in observed values at each sensor S _x , S _y , S _z when the magnetic sensor S _u (S _u ∈ {S _x , S _y , S _z }) observes the maximum value and the minimum value. each x _udiff, y _udiff, and z _Udiff. That is, when the magnetic sensor when the magnetic sensor S _u observes the maximum value _{S v (S v ∈ {S} x, S y, S z}) observations v _umax and the magnetic sensor S _u of the observed minimum The difference v _udiff from the observed value v _umin of the magnetic sensor S _v is as follows.
v _udiff = v _umax −v _umin (S _u , S _v ε {S _x , S _y , S _z }) (13)

Not only using the maximum and minimum values of each magnetic sensor as in the conventional method, but also using the observation values when the observation values of the other magnetic sensors become maximum and minimum, It is possible to calculate the angle between the two at the same time.
Specifically, the parameters are calculated by using the following relationship that is geometrically established between the observed values.

In the formula _{(14), x xdiff, x} ydiff, x zdiff a magnetic sensor S _x, respectively, S _y, observed value of the magnetic sensor S _x when the S _z observes the maximum value x _xmax, x _ymax, x _zmax And the observed values x _xmin , x _ymin , x _zmin of the magnetic sensor S _x when the magnetic sensors S _x , S _y , S _z observe the minimum value. y _xdiff , y _ydiff , and y _zdiff are the observed values y _xmax , y _ymax , and y _zmax of the magnetic sensor S _y when the maximum values of the magnetic sensors S _x , S _y , and S _z are observed, and the magnetic sensors S _x , This is the difference between the observed values y _xmin , y _ymin , and y _zmin of the magnetic sensor S _y when the minimum values of S _y and S _z are observed. z _xdiff , z _ydiff , z _zdiff are the observed values z _xmax , z _ymax , z _zmax of the magnetic sensor S _z when the magnetic sensors S _x , S _y , S _z observe the maximum values, and the magnetic sensors S _x , S _y and S _z are the differences from the observed values z _xmin , z _ymin and z _zmin of the magnetic sensor S _z when the minimum values are observed.

Since terms other than φ _x , φ _y , and φ _z are all observed values, the inclination of each magnetic sensor with respect to the horizontal plane can be obtained from the relationship of Equation (14).
The following relationship holds for gain.
2N _H = gain _x x _xdiff / cos φ _x = gain _y y _ydiff / cos φ _y
= Gain _z z _zdiff / cosφ _z (15)

Gain _x , gain _y , and gain _z are gains of the magnetic sensors S _x , S _y , and S _z , respectively. Although it is desirable that the intensity of the horizontal component of the geomagnetism at the observation point is given as N _H in Equation (15), if the purpose is to construct an azimuth sensor, even if the value of N _H is not accurate, It is not a problem because it is balanced. Therefore, a value of about N _H = 30000 [nT] used as a horizontal component of geomagnetism near Japan may be given.

If dip angle α of the observation point by using a dip meter is measured, it is possible to obtain the large bamboo N _z in the vertical direction component of terrestrial magnetism as _{N z = Nsinα = N H tanα} , the magnetic sensors S _x, The offsets offset _x , offset _y , and offset _z of S _y and S _z can be obtained as follows.
offset _x = (x _xmax + x _xmin ) / 2−N _H tan α sin φ _x / gain _x
... (16)
offset _y = (y _ymax + y _ymin ) / 2−N _H tan α sin φ _y / gain _y
... (17)
offset _z = (z _zmax + z _zmin ) / 2-N _H tanαsinφ _z / gain _z
... (18)

x _xmax, y _ymax, z _zmax magnetic sensor S _x, respectively, S _y, the maximum value of the observed value of _{S z, x xmin, y ymin} , z zmin magnetic sensor each S _x, S _y, observed value of S _z Is the minimum value.
The above calibration can be realized by one rotation in the horizontal plane.

When the dipmeter cannot be used, if A _x = N _H tan α / gain _x and B _x = offset _x in equation (16), (x _xmax + x _xmin ) / 2 = A _x sin φ _x + B _x Can be transformed. The same measurement is performed in a plurality of postures by changing the installation method of the sensor, the observed values x _xmax and x _xmin for a plurality of φ _x are obtained, and the coefficients A _x and B _x are obtained by the least square method. B _{x at} this time is an offset offset _x of the sensor S _x .
Also because the same format for formula (17) and (18), the offset offset _z offset offset _y and sensor S _z of the sensor S _y can be obtained in the same manner.

In the above calculation, in order to reduce the influence of measurement errors, it is desirable that the direction of each magnetic sensor is away from the vertical direction and the horizontal plane. This is because the absolute value of v _udiff (S _u , S _v ∈ {S _x , S _y , S _z }) decreases when the value of φ is around 0 and 90 degrees, and the influence of measurement error Can be large.

FIG. 2 shows a configuration of a calibration apparatus that realizes calibration of a three-axis magnetic sensor installed in a state where there is an inclination with respect to a horizontal plane based on the calibration model described above with reference to FIG.
The calibration apparatus includes a sensor observation value collection unit 1, maximum value detection units 2 _x , 2 _y , 2 _z , minimum value detection units 3 _x , 3 _y , 3 _z , a slope and gain calculation unit 4, and an offset And a calculator 5.

A rotating table (not shown) for rotating the magnetic sensors S _x , S _y , S _z in the horizontal plane, and a magnetic sensor S _x , S _y , S _z for fixing the magnetic sensors S _x , S _y , S _z in an arbitrary posture on the rotating table. A fixing tool (not shown) is provided. The material of the turntable and fixtures shall not affect the geomagnetism.

FIG. 3 is a flowchart showing the operation of the calibration apparatus of the present embodiment. Sensor observation value acquisition unit 1, the magnetic sensor S _x, S _y, while the S _z rotates in a horizontal plane with rotation of the turntable, the magnetic sensors S _x, S _y, the observed value S _z outputs Collect and store (step S1). The outputs of the magnetic sensors S _x , S _y , S _z are aligned in time order. The sensor observation value collection unit 1 assigns a unique index number to each collected observation value. A specific observation value can be read from the sensor observation value collection unit 1 by this index number.

The maximum value detectors 2 _x , 2 _y , 2 _z detect the maximum values of the observed values of the magnetic sensors S _x , S _y , S _z , respectively, and output the index numbers of the detected maximum values (step S2). .
The minimum value detectors 3 _x , 3 _y , 3 _z detect the minimum values of the observed values of the magnetic sensors S _x , S _y , S _z , respectively, and output the detected index numbers of the minimum values (step S3). .

The inclination and gain calculation unit 4 is based on the index numbers output from the maximum value detection units 2 _x , 2 _y , 2 _z and the minimum value detection units 3 _x , 3 _y , 3 _z , and the magnetic sensors S _x , S _y , S _z is the observed value x _xmax of the magnetic sensor S _x when the observed maximum value, x _ymax, x _zmax, observation of the magnetic sensor S _y when the magnetic sensor S _x, S _y, S _z observes the maximum value Sensor observation value collection unit for values y _xmax , y _ymax , y _zmax , and observation values z _xmax , z _ymax , z _zmax of magnetic sensor S _z when the maximum values of magnetic sensors S _x , S _y , S _z are observed reads from 1, the magnetic sensor S _x, S _y, observed value of the magnetic sensor S _x when the S _z observes the minimum _{x xmin, x ymin, x zmin} , the magnetic sensor S _x, S _y, is S _z Observation values y _xmin , y _ymin , y _zmin of the magnetic sensor S _y when the minimum value is observed, and the magnetic sensors S _x , S _y , S _z , the observed values z _xmin , z _ymin , z _zmin of the magnetic sensor S _z when the minimum value is observed are read out from the sensor observation value collecting unit 1 and each of the magnetic sensors S _x , S is read using equation (14). _The inclinations φ _x , φ _y and φ _z with respect to the horizontal plane of _y and S _z are calculated (step S4).

Subsequently, the inclination and gain calculation unit 4 calculates the inclinations φ _x , φ _y , φ of each of the magnetic sensors S _x , S _y , S _z obtained by the calculation of the geomagnetic horizontal component _NH and the calculation in step S4. _z and the observed value of the difference _{x xdiff,} y ydiff, and a z _zdiff, equation (15) the magnetic sensors S _x using, S _y, gain gain _x of S _z, gain _y, to calculate the gain _z (step S5).

The offset calculation unit 5 includes the horizontal component N _{H of} geomagnetism, the dip angle α of the observation point measured by the dip meter 6 and the inclination φ _{x of} each magnetic sensor S _x , S _y , S _z obtained by the calculation in step S4. , Φ _y , φ _z and gains gain _x , gain _y , gain _{z of the} magnetic sensors S _x , S _y , S _z obtained by the calculation in step S5, the expressions (16), (17), (18) is used to calculate the offsets offset _x , offset _y , offset _z of each magnetic sensor (step S6).

When the observation value x is obtained for the magnetic sensor S _x , the calibration unit (not shown) uses the parameters gain _x and offset _x obtained by the inclination and gain calculation unit 4 and the offset calculation unit 5 to determine the geomagnetism S at the observation point. _{The x-} direction component M _x can be obtained as M _x = gain _x (x−offset _x ) from Equation (1). It can be obtained similarly for the geomagnetic S _y direction component M _y and S _z direction component M _z. The magnetic sensors S _x, S _y, geomagnetism observed at S _z by using these values, the sensor S _x, S _y, 3-dimensional vector to base the axes of S _z (M _x, M _y , M _z ). In this way, the sensors S _x , S _y , S _z can be calibrated.

Sensor S _x to構戒each axis, S _y, when the S _z has been calibrated well balanced discharge the influence of inclination at the time of installation, the vector _{(M x, M y, M} z) is the sensor coordinate Since it indicates the direction of geomagnetism as seen from the system, it can be used to detect the stationary posture of the object, the posture during movement, and the movement trajectory.

As described above, in the present embodiment, the tilt of the triaxial magnetic sensor is modeled as a parameter, and the gain and offset of each magnetic sensor are obtained after obtaining the tilt of each magnetic sensor based on this model. I made it.
In the conventional calibration method, it was necessary to rotate each magnetic sensor horizontally with respect to the ground surface, but it was difficult to realize when the magnetic sensor was incorporated in an actual circuit. On the other hand, in this Embodiment, even if it is a case where each magnetic sensor inclines with respect to a horizontal surface, a magnetic orientation sensor can be calibrated.

  The calibration device according to the present embodiment can be realized by a computer having a CPU, a storage device, and an external interface, and a program for controlling these hardware resources. In such a computer, a program for realizing the calibration method of the present invention is provided in a state of being recorded on a recording medium such as a flexible disk, a CD-ROM, a DVD-ROM, or a memory card. The CPU stores the program read from the recording medium in the storage device, and executes the processing described in the present embodiment in accordance with the program stored in the storage device.

  The present invention can be applied to a magnetic direction sensor calibration technique.

It is a figure which shows the calibration model used by embodiment of this invention. It is a block diagram which shows the structure of the calibration apparatus which concerns on embodiment of this invention. It is a flowchart which shows operation | movement of the calibration apparatus which concerns on embodiment of this invention.

Explanation of symbols

S _x , S _y , S _z ... magnetic sensor, 1 ... sensor observation value collection unit, 2 _x , 2 _y , 2 _z ... maximum value detection unit, 3 _x , 3 _y , 3 _z ... minimum value detection unit, 4 ... Inclination and gain calculation unit, 5... Offset calculation unit, 6.

Claims (11)

When a two-dimensional or three-dimensional magnetic direction sensor rotates in a horizontal plane, a sensor that collects observation values from two or three magnetic sensors with different magnetic intensity measurement directions that constitute the magnetic direction sensor. Observation value collection means;
Maximum value detecting means for detecting the maximum value of the observed value of each magnetic sensor;
Minimum value detecting means for detecting the minimum value of the observed value of each magnetic sensor;
Using one magnetic sensor as an attention sensor, the first observation value that is an observation value of each magnetic sensor when the attention sensor observes the maximum value and the observation of each magnetic sensor when the attention sensor observes the minimum value. The second observation value that is a value is obtained by performing each of the magnetic sensors as the attention sensor, and calculating a difference between the first observation value and the second observation value for each magnetic sensor. Inclination calculating means for calculating the inclination of each magnetic sensor with respect to the horizontal plane from the difference between the observed values
Gain calculation means for calculating the gain of each magnetic sensor from the horizontal component of geomagnetism given in advance and the difference between the inclination and observation value of each magnetic sensor calculated by the inclination calculation means;
Offset calculation means for calculating an offset of each magnetic sensor from the horizontal component of the geomagnetism and the dip angle that is the angle of the geomagnetic vector of the observation point with respect to the horizontal plane, the inclination of each magnetic sensor, and the gain of each magnetic sensor. A magnetic azimuth sensor calibration device. The magnetic orientation sensor calibration apparatus according to claim 1,
The magnetic azimuth sensor is composed of three magnetic sensors S _x , S _y , S _z , and a certain sensor S _u (S _u ∈ {S _x , S _y , S _z }) observes the maximum value. magnetic sensor _{S v (S v ∈ {S} x, S y, S z}) the difference between the observed value v _umin magnetic sensor S _v when observed value v _umax of interest sensor S _u of the observed minimum When v _udiff is given, the inclination calculation means calculates the inclinations φ _x , φ _y , φ _z of the magnetic sensors S _x , S _y , S _z with respect to the horizontal plane,

The magnetic azimuth sensor calibration apparatus characterized by the above calculation. In the magnetic orientation sensor calibration apparatus according to claim 2,
When the horizontal component of the pre-given geomagnetism was N _H, the gain calculation means, the magnetic sensors S _x, S _y, gain gain _x of S _z, gain _y, the _{gain z, 2N H = gain x} x _{xdiff / cosφ x = gain y y} ydiff / cosφ y = gain z z zdiff / calibration apparatus of the magnetic direction sensor and calculates a cos [phi _z. The magnetic orientation sensor calibration apparatus according to claim 3,
When the dip angle of the observation point alpha, the offset calculation means, the magnetic sensors S _x, S _y, offset offset _x of S _z, offset _y, the _{offset z, offset x = (x} xmax + x xmin) / 2-N _H tan αsin φ _x / gain _x , offset _y = (y _ymax + y _ymin ) / 2−N _H tan αsin φ _y / gain _y , offset _z = (z _zmax + z _zmin ) / 2−N _H tan αsin φ _z / gain _z A magnetic azimuth sensor calibration apparatus characterized by calculating. In the magnetic orientation sensor calibration apparatus according to claim 2,
The offset calculation means includes a maximum value x _xmax , y _ymax , z _zmax of the observed values of the magnetic sensors S _x , S _y , S _z and a minimum of the observed values for each of a plurality of states having different attitudes of the magnetic direction sensor. When the values x _xmin , y _ymin , z _zmin are obtained and the inclinations φ _x , φ _y , φ _z of the respective magnetic sensors S _x , S _y , S _z with respect to the horizontal plane are calculated for each of the plurality of states, x _xmax + x _xmin ) / 2 = A _{x sinφ x} + B _x , (y _ymax + y _ymin ) / 2 = A _y sinφ _y + B _y , (z _zmax + z _zmin ) / 2 = minimum from the relationship of A _z sinφ _z + B _z Coefficients B _x , B _y , B _z are calculated by the square method, and these coefficients B _x , B _y , B _z are set as offsets offset _x , offset _y , offset _z of the magnetic sensors S _x , S _y , S _z. A magnetic orientation sensor calibration apparatus. When a two-dimensional or three-dimensional magnetic direction sensor rotates in a horizontal plane, a sensor that collects observation values from two or three magnetic sensors with different magnetic intensity measurement directions that constitute the magnetic direction sensor. Observation value collection procedure,
A maximum value detection procedure for detecting the maximum value of the observed value of each magnetic sensor;
Minimum value detection procedure for detecting the minimum value of the observed value of each magnetic sensor;
Using one magnetic sensor as an attention sensor, the first observation value that is an observation value of each magnetic sensor when the attention sensor observes the maximum value and the observation of each magnetic sensor when the attention sensor observes the minimum value. The second observation value that is a value is obtained by performing each of the magnetic sensors as the attention sensor, and calculating a difference between the first observation value and the second observation value for each magnetic sensor. , An inclination calculation procedure for calculating the inclination of each magnetic sensor with respect to the horizontal plane from the difference between the observed values,
A gain calculation procedure for calculating a gain of each magnetic sensor from a horizontal component of geomagnetism given in advance and a difference between an inclination and an observation value of each magnetic sensor calculated by the inclination calculation procedure;
An offset calculation procedure for calculating an offset of each magnetic sensor from the horizontal component of the geomagnetism and the dip angle that is an angle of the geomagnetic vector of the observation point with respect to the horizontal plane, the inclination of each magnetic sensor, and the gain of each magnetic sensor; Calibration method for magnetic orientation sensor. The magnetic direction sensor calibration method according to claim 6,
The magnetic azimuth sensor is composed of three magnetic sensors S _x , S _y , S _z , and a certain sensor S _u (S _u ∈ {S _x , S _y , S _z }) observes the maximum value. magnetic sensor _{S v (S v ∈ {S} x, S y, S z}) the difference between the observed value v _umin magnetic sensor S _v when observed value v _umax of interest sensor S _u of the observed minimum When v _udiff is given, the inclination calculation procedure is to calculate the inclinations φ _x , φ _y , φ _z of the magnetic sensors S _x , S _y , S _z with respect to the horizontal plane,

A method for calibrating a magnetic azimuth sensor, characterized by: The magnetic direction sensor calibration method according to claim 7,
When the pre-given horizontal component of geomagnetism is N _H , the gain calculation procedure is to calculate the gains gain _x , gain _y , and gain _z of each magnetic sensor S _x , S _y , S _z as 2N _H = gain _x x A method for calibrating a magnetic azimuth sensor, characterized in that _xdiff / cos φ _x = gain _y y _ydiff / cos φ _y = gain _z z _zdiff / cos φ _z The magnetic direction sensor calibration method according to claim 8,
When the dip angle of the observation point is α, the offset calculation procedure is as follows: offset _x , offset _y , offset _z of each magnetic sensor S _x , S _y , S _z is offset _x = (x _xmax + xx _min ) / 2-N _H tan αsin φ _x / gain _x , offset _y = (y _ymax + y _ymin ) / 2−N _H tan αsin φ _y / gain _y , offset _z = (z _zmax + z _zmin ) / 2−N _H tan αsin φ _z / gain _z A method for calibrating a magnetic azimuth sensor, characterized by: The magnetic direction sensor calibration method according to claim 7,
In the offset calculation procedure, the maximum value x _xmax , y _ymax , z _zmax of the observed value of each magnetic sensor S _x , S _y , S _z and the minimum of the observed value for each of a plurality of states having different attitudes of the magnetic direction sensor When the values x _xmin , y _ymin , z _zmin are obtained and the inclinations φ _x , φ _y , φ _z of the respective magnetic sensors S _x , S _y , S _z with respect to the horizontal plane are calculated for each of the plurality of states, x _xmax + x _xmin ) / 2 = A _{x sinφ x} + B _x , (y _ymax + y _ymin ) / 2 = A _y sinφ _y + B _y , (z _zmax + z _zmin ) / 2 = minimum from the relationship of A _z sinφ _z + B _z Coefficients B _x , B _y , B _z are calculated by the square method, and these coefficients B _x , B _y , B _z are set as offsets offset _x , offset _y , offset _z of the magnetic sensors S _x , S _y , S _z. A magnetic direction sensor calibration method characterized by the above.   A calibration program for causing a computer to execute the procedure according to any one of claims 6 to 10.

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