JPH07198809A - Magnetism measuring instrument - Google Patents

Abstract

PURPOSE:To provide a magnetism measuring instrument in which a sensitivity axis is made to be adjusted easily and automatically and which is miniaturized further. CONSTITUTION:The magnetism measuring instrument is installed in an arbitrary attitude. Geomagnetism is first detected by a three-axis magnetic sensor 5 which is composed of a three-axis magnetic sensor element 1 and a sensor controller 2, it is converted into a digital signal by an A/D converter 3, the digital signal is taken into a computer 4, and a deviation angle from the sensitivity axis of the geomagnetism is computed. Then, a magnetic field to be measured is detected by the three-axis magnetic sensor 5. The magnetic field to be measured is turned around the axis and operated on the basis of the deviation angle which has already been computed by the computer 4, it is converted into a measured value corresponding to the sensitivity axis, and a converted value is output.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION This invention relates to a triaxial magnetic measuring device,
In particular, the present invention relates to a magnetic measuring device capable of automatically matching sensitivity axes.

[0002]

2. Description of the Related Art Generally, when a three-axis magnetic sensor is installed in the earth's magnetism to measure a magnetic field, the magnetic field sensitivity axes are installed in the vertical direction, the magnetic east-west direction, and the north-south direction. . Therefore, most of the accumulated data are obtained in these sensitivity axis directions. Conventionally, to match the vertical direction, magnetic east-west direction, north-south direction,
A method is adopted in which a person makes a match several times while making a measurement, or a method in which a gimbal mechanism is used to make a match in the vertical direction and the sensitivity axis is physically rotated by a human or a motor in the azimuth direction.

[0003]

In the above-mentioned conventional method of aligning the sensitivity axes, it takes time and labor if it is done manually, and if a gimbal mechanism or a motor is used, the size of the magnetic measuring device becomes correspondingly large. There was a problem. The present invention was made by focusing on the above problems,
It is an object of the present invention to provide a compact magnetic measuring device which can relatively easily and automatically match the sensitivity axes.

[0004]

The magnetic measuring instrument of the present invention comprises a triaxial magnetic sensor, a means for converting the magnetic field value detected by the triaxial magnetic sensor into a digital value, and a geomagnetic field. A means for calculating a deviation angle of the geomagnetic 3-axis magnetic sensor with respect to the sensitivity axis from the obtained three components of the magnetic field, and a rotation calculation about the axis for the magnetic field to be measured based on the deviation angle, and with respect to the sensitivity axis. And a means for converting the measured magnetic field value so as to obtain a desired relationship.

In this magnetometer, only the geomagnetism is measured in a state of being installed in an arbitrary posture, and the measured three-direction component values are made to coincide with each other in the vertical direction, the magnetic east-west direction, and the north-south direction. The deviation angle with respect to the sensitivity axis is calculated from the magnetic field value of. After that, in that posture, measure the magnetic field to be measured,
The magnetic fields are respectively rotated around the axes with reference to the displacement angles, and the magnetic field values obtained when the three-axis sensor is aligned with the sensitivity axis are converted and output.

[0006]

The present invention will be described in more detail with reference to the following examples. FIG. 1 is a block diagram showing the configuration of a magnetometer according to an embodiment of the present invention. The magnetometer of this embodiment includes a triaxial magnetic sensor element 1, a sensor controller 2, and an A /
It is composed of a D converter 3 and a computer 4.

The triaxial magnetic sensor element 1 has three components H of the magnetic field.
An analog signal is generated in response to x, Hy, and Hz. For example, a configuration in which three flux gate type magnetic sensor elements are arranged orthogonal to each other is used. Sensor controller 2
Drives the 3-axis magnetic sensor element 1, performs signal processing such as amplification of an analog signal generated in response to a magnetic field by the 3-axis magnetic sensor element, or removal of unnecessary frequency components, and outputs the result as an analog signal. To do. The triaxial magnetic sensor element 1 and the sensor controller 2 constitute a triaxial magnetic sensor 5.

The A / D converter 3 converts the analog detection signal output from the sensor controller 2 into a signal to be taken into the computer 4, that is, a digital signal. The computer 4 takes in the digitally converted detection signal, that is, the three components Hx, Hy, and Hz of the detection magnetic field, and performs an operation with an algorithm described later. The result thus obtained is used for another purposeful calculation, or is output to the display 6, the printer 7, or the like.

Next, the principle of adoption of the magnetic detector of the above embodiment will be described. The situation in which the sensitivity axis of the three-axis magnetic sensor faces various directions with respect to the earth's magnetism is the opposite. If the sensitivity axis is taken as a reference, the earth magnetism faces various directions with respect to the sensitivity axis. Means that. As shown in FIG. 2, the positional relationship between the geomagnetism H ′ and the triaxial sensitivity axis is unambiguously defined by the angle θ between the Z-axis direction and the geomagnetism, and the angle φ between the X-axis direction and the XY plane component of the geomagnetism in polar coordinate representation. Can be defined explicitly. The state in which the geomagnetism faces various directions with respect to the sensitivity axis means that the angles θ and φ take various values. What can be measured by the three-axis magnetic sensor is each axial component of the earth's magnetism, and these axial component values are Hx, Hy,
Hz,

[0010]

[Equation 1]

The following relationship holds. It can be said that the method of directing the sensitivity axis of the three-axis magnetic sensor in a predetermined direction is a method of keeping H constant and changing the angles θ and φ to arbitrary values. When the angles θ and φ are changed, equations (1) to (3) give
It can be seen that the magnetic fields Hx, Hy, Hz change. From the opposite viewpoint, if Hx, Hy, and Hz are changed while H is kept constant, the angles θ and φ will change. Therefore, if a method of transforming Hx, Hy, and Hz so that the target angles θ and φ are obtained is obtained,
The purpose of this time, which is to make the geomagnetism equivalently coincident with the sensitivity axis, will be achieved.

With respect to the angles θ and φ, current values are represented by the same notation θ and φ, desired values are θ ₀ and φ _0, and geomagnetisms θ and φ and θ ₀ and φ ₀ are H ′ = ( Hx, Hy, Hz) ... ( 5) H '0 = (Hx 0, Hy 0, Hz 0) ... (6) However, H' absolute value of = H _'0 of ... When (7), wherein From (1) to (3),

[0013]

[Equation 2]

And the angles θ and φ are Hx, Hy, Hz
You can ask more. The 'on the right shoulder of each character is used as a vector symbol for convenience (the same applies below).
In general, one of the movement transformations of a point (x, y, z) in an XYZ three-dimensional coordinate system is rotation about an axis. Since it is three-dimensional, rotation about this axis is as shown in FIG. 4, rotation about the X axis [(a) in FIG. 4], rotation about the Y axis [(b) in FIG. 4], And three rotation transformations of rotation around the Z axis [(c) in FIG. 4].

A point (x, y,
The coordinates after the movement of z) and _{(x a, y a, z} a), when the positive direction of rotation determines the rotation direction of when advancing the right screws in the positive direction of the coordinate axis representing the rotational angle α , rotation around · x axis _{x a = x ... (10)} y a = ycosα-zsinα ... (11) z a = ysinα + zcosα ... (12) around · Y axis rotation _{x a = zsinα + xcosα ... (} 13) y a = y ... a _{(14) z a = zcosα-} xsinα ... (15) · rotation around the Z-axis _{x a = xcosα-ysinα ... (} 16) y a = xsinα + ycosα ... (17) z a = z ... (18).

[0016] Now, to see the problem of conversion to ₀ 'H of' H shown in FIG. 3 in perspective of the movement of points around this axis, by the following two steps, that the conversion is possible Noticed. <First Procedure> Description will be given with reference to FIG.

First, H'is rotated by -φ about the Z axis. By this conversion, the obtained magnetic field vector is H ′ ₁ = (Hx ₁ , Hy ₁ , Hz ₁ ) ... (19), and then the vector H ′ ₁ is − (θ−θ ₀ ) around the Y axis.
Rotate. By this conversion, the obtained magnetic field vector is set to H ′ ₂ = (Hx ₂ , Hy ₂ , Hz ₂ ) ... (20), and finally H ′ ₂ is rotated by φ ₀ around the Z axis.

<Second Procedure> Description will be given with reference to FIG. Rotate H ′ about the Z axis (90 ° -φ). By this conversion, the obtained magnetic field vector is set to H ′ ₃ = (Hx ₃ , Hy ₃ , Hz ₃ ) ... (21), and then H ′ ₃ is rotated about the X axis (θ−θ ₀ ). This conversion 'and ₄ = a _{(Hx 4, Hy 4, Hz} 4) ... (22), the end H' obtained magnetic field vector H ₄ to about the Z-axis - (90 ° -φ ₀₎ is rotated . Since the coordinate point and the magnetic field vector have the same mathematical expression, applying equations (10) to (18) to the magnetic field vector gives, for example, H ′ ₁ , H ′ ₂ shown in step 1, and the conversion result. each axis component of H _{'0 is, Hx 1 = Hxcos (-φ)} -Hysin (-φ) ... (23) Hy 1 = Hxsin (-φ) + Hycos (-φ) ... (24) Hz 1 = Hz ... ( 25) Hx ₂ = Hz ₁ sin-(θ-θ ₀ ) + Hx ₁ cos-(θ-θ ₀ ) ... (26) Hy ₂ = Hy ₁ ... (27) Hz ₂ = Hz ₁ cos-(θ-θ ₀ ) −Hx ₁ sin − (θ−θ ₀ ) ... (28) Hx ₀ = Hx ₂ cos φ ₀ −Hy ₂ sin φ ₀ … (29) Hy ₀ = Hx ₂ sin φ ₀ + Hy ₂ cos φ ₀ … (30 ) Hz ₀ = Hz ₂ (31)

Therefore, the angles θ ₀ and φ ₀ are determined, and H
x, Hy, Hz are measured, θ and φ are obtained from the equations (8) and (9) from these values, and then H ′ ₁ is obtained from the equations (23) to (25).
This is substituted into equation (26) ~ (28), H ' seek _2, if finally substituted into equation (29) ~ (31), H' 0 is obtained. The same applies to the procedure 2, and H ₀ can be obtained from θ ₀ , φ ₀ , Hx, Hy, and Hz by any of the procedures.

[0020]

According to the present invention, the sensitivity axis physically determined by the software processing of the computer is
Even if it is installed in any posture, the measured value is converted into an equivalent value as if the magnetic sensor was aligned with the sensitivity axis and output, so there is no need for the effort to match the sensitivity axis in various settings. Moreover, since a gimbal configuration and a motor for adjusting the sensitivity axis are not required, it is possible to realize miniaturization.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of a magnetometer according to an embodiment of the present invention.

FIG. 2 is a diagram illustrating a positional relationship between geomagnetism and a triaxial sensitivity axis.

FIG. 3 is a diagram illustrating a conversion example of coordinate points.

FIG. 4 is a diagram illustrating rotational movement about three axes.

FIG. 5 is a diagram illustrating a procedure example of rotation conversion of a magnetic field vector in a polar coordinate system.

FIG. 6 is a diagram illustrating another procedure example of rotation conversion of a magnetic field vector in a polar coordinate system.

[Explanation of symbols]

 1 3-axis magnetic sensor element 2 Sensor controller 3 A / D converter 4 Computer 5 3-axis magnetic sensor

Claims (1)

[Claims] 1. A triaxial magnetic sensor for geomagnetism, comprising a triaxial magnetic sensor, means for converting a magnetic field value detected by the triaxial magnetic sensor into a digital value, and three magnetic field components obtained by measuring geomagnetism. Means for calculating the deviation angle with respect to the sensitivity axis of
The magnetic field to be measured is provided with means for performing rotation calculation about the axis based on the deviation angle and converting the measured magnetic field value so as to have a desired relationship with the sensitivity axis. Magnetic measuring instrument.