JPH09318357A - Three-dimensional bearing sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a three-dimensional sensor which achieves a higher accuracy, a smaller size and a lower cost. SOLUTION: A three-dimensional bearing sensor is provided with two magnetic sensors 1 and 2 orthogonal to each other and a rotation mechanism 3 to allow the rotating of the two magnetic sensors 1 and 2 being kept orthogonal to each other with three axes orthogonal to each other of this sensor individually as the center. Then, the earth magnetism is measured by the magnetic sensors 1 and 2 while rotating the magnetic sensors 1 and 2 by the rotation mechanism 3 to detect the bearing at which outputs from the magnetic sensors 1 and 2 reach the peaks thereof. Thus, the bearing of the earth magnetism is detected as reference of bearing information at a three-dimensional space.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a three-dimensional azimuth sensor for detecting azimuth in a three-dimensional space.

[0002]

2. Description of the Related Art As a sensor used as a three-dimensional azimuth sensor for detecting an azimuth in a three-dimensional space, for example, there is a level for detecting a level in a three-dimensional space.
The spirit level obtains tilt information by enclosing a bubble in a glass tube and detecting the moving state of the bubble.

By the way, it is preferable that the information detected by the sensor is output as an electric signal so that the information can be taken into another device or can be processed by a computer or the like. However, in order to take out the information from the level as an electric signal, it is necessary to detect the movement of the bubble by using an optical method or the like. Therefore, if the information from the electronic level is to be taken out as an electric signal, the configuration becomes complicated, and it becomes difficult to achieve miniaturization and cost reduction. Further, since the spirit level uses a glass tube, it is vulnerable to impact, and there is a problem in terms of durability and reliability.

Further, as a method for detecting the level in the three-dimensional space, there is also a method for detecting the level in the three-dimensional space by utilizing gravity applied to the object and obtaining the center of gravity of the object. However, if an attempt is made to secure sufficient detection accuracy by this method, the configuration becomes very large, and it is difficult to achieve miniaturization and cost reduction.

As a method of detecting the azimuth information of the moving body, the acceleration of the moving body is detected by an acceleration sensor,
There is a method of obtaining azimuth information from the detected acceleration information. However, with this method, since relative azimuth information is detected, once an error occurs, the error is accumulated. That is, this method has a drawback that a large cumulative error is likely to occur.

[0006]

As described above, conventionally,
The equipment used for detecting the orientation in the three-dimensional space has problems that the accuracy is insufficient and that it is difficult to reduce the size and cost.

Therefore, the present invention has been proposed in view of such a conventional situation, and it is an object of the present invention to provide a three-dimensional azimuth sensor which is more accurate and can be downsized and reduced in price. Has an aim.

[0008]

A three-dimensional azimuth sensor according to the present invention, which has been completed to achieve the above object, has two magnetic sensors which are orthogonal to each other and the two magnetic sensors which are orthogonal to each other. A rotation mechanism that can rotate about three axes that are orthogonal to each other is provided.

In the three-dimensional azimuth sensor according to the present invention,
The two magnetic sensors that are orthogonal to each other detect the geomagnetism applied to each magnetic sensor. Further, the rotating mechanism rotates the magnetic sensor detecting the geomagnetism while keeping the magnetic sensor orthogonal to each other.

[0010]

Embodiments of the present invention will be described below in detail with reference to the drawings. The present invention is not limited to the following examples, and it goes without saying that the configuration can be arbitrarily changed without departing from the gist of the present invention. In addition,
In the following description, three axes orthogonal to each other are defined as the X axis,
The vertical direction is referred to as the Y-axis and the Z-axis, and the vertical direction is the Z-axis, and two axes orthogonal to each other in the horizontal plane are the X-axis and the Y-axis.

The three-dimensional azimuth sensor according to this embodiment is
As shown in FIG. 1, a first magnetic sensor 1 and a second magnetic sensor 2 arranged so as to be orthogonal to the first magnetic sensor 1.
And a rotation mechanism 3 to which the first magnetic sensor 1 and the second magnetic sensor 2 are attached. Although not shown, the three-dimensional azimuth sensor includes a first display device that displays the magnitude of the magnetic field detected by the first magnetic sensor 1 and a magnetic field detected by the second magnetic sensor 2. And a second display device for displaying the size of the.

In the above three-dimensional azimuth sensor, the first magnetic sensor 1 is for detecting the horizontal component of geomagnetism. The first magnetic sensor 1 includes a pair of sensor portions that are parallel to the sensing surface 1a of the first magnetic sensor 1 and are orthogonal to each other, and the output from the first magnetic sensor 1 is one of It is output as a differential between the output from the sensor unit and the output from the other sensor unit. On the other hand, the second magnetic sensor 2 is for detecting the vertical component of the earth's magnetism, and like the first magnetic sensor 1, is parallel to the sensing surface 2a of the second magnetic sensor 2,
It has a pair of sensor units that are orthogonal to each other, and the output from the second magnetic sensor 2 is output as a differential between the output from one sensor unit and the output from the other sensor unit.

In the above three-dimensional azimuth sensor, the rotation mechanism 3 includes the sensing surface 1a of the first magnetic sensor 1 and the second sensing surface 1a.
It is possible to rotate the first magnetic sensor 1 and the second magnetic sensor 2 about the mutually orthogonal X-axis, Y-axis, and Z-axis while keeping the sensing surface 2a of the magnetic sensor 2 of FIG. Has become. That is, the rotating mechanism 3 is rotatable about three axes which are orthogonal to each other while the two magnetic sensors 1 and 2 are orthogonal to each other. The rotating mechanism 3 is, for example, the first
The magnetic sensor 1 of is rotated parallel to the horizontal plane,
The magnetic sensor 2 is rotated perpendicular to the horizontal plane.

In the three-dimensional azimuth sensor, the first magnetic sensor 1 and the second magnetic sensor 2 are magnetic sensors capable of detecting a weak magnetic field such as geomagnetism. Specifically, a magnetic sensor using a magnetoresistive effect element, a magnetic sensor using a fluxgate, or a magnetro inductance element (hereinafter referred to as M
It is called an I element. ) Is suitable. Further, these magnetic sensors are usually easy to be miniaturized and reduced in price, and can detect a magnetic field with high accuracy. Therefore, according to the third embodiment using such a magnetic sensor. The dimensional azimuth sensor can detect the azimuth with high accuracy, and can be easily reduced in size and cost.

An example of the structure of the magnetic sensor using the magnetoresistive effect element will be described with reference to FIG.

In this magnetic sensor, the gaps G10, G20, G30 and G40 are formed at 90 ° intervals.
Four arc-shaped ferromagnetic cores K10, K20, K30,
K40 is combined in an annular shape, and four magnetoresistive effect elements M10, M2 for geomagnetic detection are provided so as to correspond to the four gaps G10, G20, G30, G40.
0, M30, M40 are arranged. Here, the magnetoresistive effect elements M10, M20, M30, M40 are
This is a magnetoelectric conversion element that applies the magnetoresistive effect of a ferromagnetic thin film made of an i alloy or the like, and has the characteristic that the resistance value changes according to the magnitude of the applied magnetic field.

The ferromagnetic cores K10, K20, K3
0 and K40 have excitation coils C10 and C2, respectively.
0, C30, C40 are wound, and an AC bias current Ib is passed through the exciting coils C10, C20, C30, C40 so that the gaps G10, G20, G3.
An AC bias magnetic field is applied to each of the magnetoresistive effect elements M10, M20, M30, M40 arranged corresponding to 0, G40.

On the other hand, the magnetoresistive effect elements M10, M20,
M30 and M40 are connected to a constant potential power supply Vc,
From the constant potential power source Vc, the magnetoresistive effect elements M10,
A sense current is supplied to M20, M30 and M40. Then, by detecting the voltage change of the sense current, the magnetoresistive effect elements M10, M20, M30, M40 are detected.
Of the magnetic field applied to each of the magnetoresistive effect elements M10, M20, M30, M40 is detected.

In the magnetic sensor shown in FIG. 2, the sensing parts are the magnetoresistive effect elements M10, M20,
They are M30 and M40. Then, the pair of magnetoresistive effect elements M10 and M30 arranged so as to face the same direction are
The first sensor unit detects the magnetic field in the direction orthogonal to the longitudinal direction of the magnetoresistive effect elements M10 and M30.
Further, a pair of magnetoresistive effect elements M20, M40 arranged so as to be orthogonal to the magnetoresistive effect elements M10, M30.
Serves as a second sensor unit that detects a magnetic field in a direction orthogonal to the longitudinal direction of these magnetoresistive effect elements M20 and M40.

Next, an example of the structure of the magnetic sensor using the flux gate will be described with reference to FIG.

In this magnetic sensor, an exciting coil 111 is wound around an annular magnetic core 110 made of a high magnetic permeability material whose hysteresis curve is shifted by an external magnetic field, and a pair of detecting coils 11 are arranged so as to be orthogonal to each other.
It is formed by winding 2,113.

The one detection coil 112 is a coil 112a wound around the left side portion of the magnetic core 110.
And the coil 1 wound around the right side of the magnetic core 110.
12b, and the other detection coil 113 is a coil 113a wound around the upper part of the magnetic core 110.
And the coil 1 wound around the lower part of the magnetic core 110.
13b and.

When detecting an external magnetic field with this magnetic sensor, a high-frequency current that excites the magnetic core 110 to a supersaturated state is passed through the exciting coil 111. At this time, if the magnetic field from the outside does not act on the magnetic core 110, the coils 112a on the left and right of the detection coil 112,
The output from 112b has the same output waveform. Since the left and right coils 112a and 112b of the detection coil 112 are connected in reverse phase, the output from the left coil 112a of the detection coil 112 and the output from the right coil 112b of the detection coil 112 are Cancel each other out, and nothing is output from the entire detection coil 112. Similarly, since the left and right coils 113a and 113b of the detection coil 113 are also connected in anti-phase, the output from the left coil 113a of the detection coil 113 and the output from the right coil 113b of the detection coil 113. And cancel each other out, and nothing is output from the entire detection coil 113.

On the other hand, the magnetic flux B is generated by the exciting coil 111.
Is generated in the magnetic core 110, when a magnetic field in a direction orthogonal to the line connecting the left and right coils 112a and 112b of the detection coil 112 is applied to the magnetic core 110, this magnetic field acts as a bias magnetic field. Then, one side of the magnetic core 110 saturates quickly and the other side of the magnetic core 110 saturates with a delay. Therefore, the detection coil 11
2 the difference between the output from the coil 112a on the left side and the output from the coil 112b on the right side of the detection coil 112 is
The magnetic field is output according to the magnitude of the magnetic field applied to the magnetic sensor.

Similarly, when the magnetic flux B is generated in the magnetic core 110 by the exciting coil 111, the magnetic field in the direction orthogonal to the line connecting the upper and lower coils 113a and 113b of the detecting coil 113 is magnetic. When added to the core 110, this magnetic field acts as a bias magnetic field to saturate one side of the magnetic core 110 early and saturate the other side of the magnetic core 110 with a delay. Therefore, the detection coil 11
The difference between the output from the coil 113a on the upper side of 3 and the output from the coil 113b on the lower side of the detection coil 113 is
The magnetic field is output according to the magnitude of the magnetic field applied to the magnetic sensor.

In the magnetic sensor shown in FIG. 3, the sensing portions are the detection coils 112 and 113. The detection coil 112 serves as a first sensor unit that detects a magnetic field in a direction orthogonal to a line connecting the left and right coils 112a and 112b, and the detection coil 11
3 serves as a second sensor unit that detects a magnetic field in a direction orthogonal to a line connecting the upper and lower coils 113a and 113b.

Next, a configuration example of the magnetic sensor using the MI element will be described with reference to FIG.

This magnetic sensor includes a pair of MI elements 21.
0 and 220 are arranged so as to be orthogonal to each other. Here, the MI element 210 is an elongated magnetic body 211 made of a magnetic material having an excellent rectangular characteristic that exhibits a steep magnetic permeability change in a weak magnetic field of about several Gauss, and is wound in the longitudinal direction of the magnetic body 211. And a coil 212.
Similarly, the MI element 220 is composed of an elongated magnetic body 221 made of a magnetic material having an excellent rectangular characteristic that exhibits a steep magnetic permeability change in a weak magnetic field of about several Gauss, and is wound in the longitudinal direction of the magnetic body 221. And a coil 222.

The MI element 210 having such a configuration,
220 is a magnetic body 211,2 according to the change of the external magnetic field.
21 changes its permeability, resulting in coils 212, 22
The inductance of 2 changes greatly. Therefore, the magnetic field parallel to the longitudinal direction of the magnetic body 211 can be detected by detecting the change in the inductance of the coil 212, and similarly, the change in the inductance of the coil 222 can be detected to detect the magnetic field of the magnetic body 221. A magnetic field parallel to the longitudinal direction can be detected.

In this magnetic sensor, the MI elements 210 and 220 are the sensing portions. That is, one MI element 210 is the magnetic body 21 of the MI element 210.
1 serves as a first sensor unit that detects a magnetic field parallel to the longitudinal direction of the first MI element 220, and the other MI element 220 serves as a second sensor unit that detects a magnetic field parallel to the longitudinal direction of the magnetic body 221 of the MI element 220. .

Next, the detection of the direction by the above three-dimensional direction sensor will be described.

As shown in FIG. 5, the N magnetic pole exists near the north pole of the earth E, and the S magnetic pole exists near the south pole.
As a result, geomagnetism H is generated. The geomagnetism H includes azimuth information in the horizontal direction, has a dip angle, and also includes angle information in the vertical direction. That is, since the geomagnetism H has three-dimensional information, it can be used as a reference for three-dimensional information. Therefore, in the above three-dimensional orientation sensor,
By using as a reference, the orientation in the three-dimensional space is detected.

Specifically, first, as a first step, the first magnetic sensor 1 is rotated by the rotating mechanism 3 in a state where the sensing surface 1a of the first magnetic sensor 1 is substantially parallel to the horizontal plane. The geomagnetism H is detected while rotating around the axis. At this time, the output from the first magnetic sensor 1 depends on the direction of the geomagnetism H and the direction in which the first magnetic sensor 1 is facing. Therefore, by referring to the first display device that displays the magnitude of the geomagnetism H detected by the first magnetic sensor 1, by detecting the azimuth at which the output from the first magnetic sensor 1 reaches a peak, The orientation of the geomagnetism H in the horizontal plane will be known.

Here, the first magnetic sensor 1 is actually used, and the first magnetic sensor 1 is rotated about the Z axis by using the rotation angle of the first magnetic sensor 1 about the Y axis as a parameter. FIG. 6 shows the actual measurement value of the geomagnetism H measured while performing the measurement. In FIG. 6, the vertical axis represents the output obtained by taking the differential between the output from one sensor unit of the first magnetic sensor 1 and the output from the other sensor unit, and the horizontal axis. , And the rotation angle of the first magnetic sensor 1 about the Z axis.

As shown in FIG. 6, the output from the first magnetic sensor 1 depends on the direction in which the first magnetic sensor 1 is facing, and is output every 180 ° about the Z axis. It is at the peak. Therefore, by detecting the azimuth in which the output from the first magnetic sensor 1 has a peak, the azimuth of the geomagnetism in the horizontal plane can be known.

Next, as the second step, the direction of the second magnetic sensor 2 is set to be parallel to the geomagnetism H detected as described above, and then the second magnetic sensor 2 is set. The geomagnetism H is detected by rotating the rotating mechanism 3 perpendicularly to the horizontal plane. At this time, the output from the second magnetic sensor 2 depends on the direction of the geomagnetism H and the direction in which the second magnetic sensor 2 is facing. Therefore,
By referring to a second display device that displays the magnitude of the geomagnetism H detected by the second magnetic sensor 2, the azimuth at which the output from the second magnetic sensor 2 reaches a peak is detected to detect the geomagnetism H. You can see the dip angle.

Here, the second magnetic sensor 2 is actually used, the second magnetic sensor 2 is set to be parallel to the earth magnetism H, and then the second magnetic sensor is rotated by the rotating mechanism 3. While rotating perpendicular to the horizontal plane, the geomagnetism H
The actual measurement value obtained by measuring is shown in FIG. In addition, in FIG.
The vertical axis represents the output obtained by taking the differential between the output from one sensor section of the second magnetic sensor 2 and the output from the other sensor section, and the horizontal axis represents the second magnetic sensor. The rotation angle of 2 is shown.

As shown in FIG. 7, the output from the second magnetic sensor 2 depends on the direction in which the second magnetic sensor 2 faces, and has a peak every 180 ° rotation. . Therefore, by detecting the azimuth at which the output from the second magnetic sensor 2 has a peak, the dip angle of the geomagnetism can be known.

By the above two steps, both the horizontal direction and the vertical direction of the geomagnetism H, that is, the azimuth and the dip angle of the geomagnetism H can be measured, whereby the reference point in the three-dimensional space can be obtained.

The above-mentioned three-dimensional direction sensor can be widely applied to equipment utilizing three-dimensional information, and more specifically, it can be used for a device for measuring the moving amount of a moving body. When the above three-dimensional azimuth sensor is used in the device for measuring the moving amount of the moving body, the moving amount of the moving body is measured based on the reference point in the three-dimensional space obtained by the three-dimensional azimuth sensor. The amount of movement of the moving body can be measured with high accuracy. Further, when the moving amount of the moving body is detected, it is possible to detect the velocity and the acceleration of the moving body by performing a calculation process on the detected moving amount. That is, the velocity of the moving body can be obtained by differentiating the moving amount of the moving body with respect to time, and further, the acceleration of the moving body can be obtained by differentiating the speed with respect to time.

Since the outputs from the first magnetic sensor 1 and the second magnetic sensor 2 are output as electric signals in the three-dimensional orientation sensor, the three-dimensional orientation sensor uses the orientation information in the three-dimensional space. Can be taken out as an electric signal. Therefore, with this three-dimensional azimuth sensor, it is possible to easily import the information on the detected azimuth and dip of the geomagnetism into another device or to perform arithmetic processing by a computer or the like.

[0042]

As is apparent from the above description, the three-dimensional azimuth sensor according to the present invention can detect azimuth information with high accuracy, and can be easily reduced in size and cost. it can.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing a configuration example of a three-dimensional azimuth sensor to which the present invention is applied.

FIG. 2 is a schematic diagram showing a configuration example of a magnetic sensor using a magnetoresistive effect element.

FIG. 3 is a schematic diagram showing a configuration example of a magnetic sensor using a flux gate.

FIG. 4 is a schematic diagram showing a configuration example of a magnetic sensor using an MI element.

FIG. 5 is a schematic diagram showing geomagnetism.

FIG. 6 is a diagram showing a result of detecting geomagnetism while rotating a first magnetic sensor.

FIG. 7 is a diagram showing a result of detecting geomagnetism while rotating a second magnetic sensor.

[Explanation of symbols]

1 1st magnetic sensor, 2 2nd magnetic sensor, 3
Rotation mechanism

Claims (1)

[Claims] 1. A magnetic recording medium comprising: two magnetic sensors that are orthogonal to each other; and a rotating mechanism that is rotatable about three mutually orthogonal axes while keeping the two magnetic sensors orthogonal to each other. A three-dimensional direction sensor.