JPH0650757A - Direction detection apparatus - Google Patents

Abstract

PURPOSE:To detect a direction precisely and with high accuracy. CONSTITUTION:The apparatus is provided with a fluxgate-type magnetic sensor 2 wherein an X-direction detection coil 2x having its axial center in the X- direction and a Y-direction detection coil having its axial center in the Y- direction with reference to a toroidal core 2c on which an excitation coil 2b has been wound and which is provided with its axial center in the Z-direction are arranged, with an excitation circuit 3 wherein the excitation coil 2b is excited by a pulse. excitation signal Sb and with signal processing systems 4x, 4y wherein detection signals Sx, Sy by the respective detection coils 2x, 2y are processed respectively. Especially, a gain setting circuit 5 which sets different gains so as to correspond to the range of a direction with reference to the detection signal Sx by the detection coil 2x is installed at the signal processing system 4x (in the same manner also on the side of the 4y).

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an azimuth detecting device suitable for use in a navigation system mounted on an automobile.

[0002]

2. Description of the Related Art Generally, in a car navigation system that uses direction information by radio waves from artificial satellites, mapping information of a CD-ROM, etc., a destination is input in advance so that the current traveling position and traveling guidance can be obtained. You can easily know the information of. However, in some driving areas, the reception state of radio waves becomes poor and stable azimuth information cannot be obtained. Therefore, such a navigation system is usually equipped with an azimuth detection device that complements unstable azimuth information. .

The conventional azimuth detecting device detects the terrestrial magnetism to obtain azimuth information. Usually, in this type of device, an X-direction is applied to a toroidal core having a Z-axis axis around which an exciting coil is wound. A flux-gate type (double frequency modulation type) magnetic sensor (X2 in FIG. 3) is provided by disposing an X-direction detection coil having an axis and a Y-direction detection coil having an axis in the Y direction.
And a signal processing system for processing the detection signal of each detection coil in this magnetic sensor to obtain output data (output value) corresponding to the azimuth.

[0004]

By the way, since the fluxgate type magnetic sensor detects weak geomagnetism, a high degree of detection accuracy is required. For this reason, conventionally, an eddy current loss has been reduced by using a toroidal core in which 10 to 20 micrometer thin ribbons made of a material such as amorphous or permalloy are laminated. In addition,
When a normal sintered core is used as the toroidal core, since a pulse excitation signal with a frequency of about 5 to 10 kHz is used, heat generation due to loss becomes large, so it cannot be used, and when a ferrite core is used. Has poor temperature characteristics and cannot be used for automobiles that require operating temperature conditions of -40 ° C to 150 ° C.

However, in the toroidal core in which the ribbons are laminated, the eddy current loss is greatly reduced, but the core cross-sectional area becomes non-uniform due to the thickness of the ribbon, the undulation, the positional deviation between the winding start and the winding end, and the like. Eventually, there is a problem in that the magnitude of the detection signal from each detection coil causes an error, and accurate and highly accurate azimuth detection cannot be performed. That is, as is clear from the BH curve W shown in FIG. 4, the output voltage (detection signal) V of the detection coil is V∝K (Δμ ₁ −Δμ ₂ ) H = K
B = K (φ / S) (K: constant, μ ₁ , μ ₂ : permeability, H: magnetic field strength, B: magnetic flux density, φ: magnetic flux, S: cross-sectional area) If the size of the cross-sectional area S lacks uniformity, there arises a problem that an error component is superimposed on the output voltage V depending on the orientation of the toroidal core. Note that FIG. 4 shows the pulse excitation signal Sb supplied to the excitation coil in correspondence with the BH curve W.

The present invention solves the problems existing in such conventional techniques, and an object of the present invention is to provide an azimuth detecting device capable of performing azimuth detection accurately and with high accuracy.

[0007]

The present invention provides an exciting coil 2b.
Fluxgate type in which an X-direction detection coil 2x having an X-axis axis and a Y-direction detection coil 2y having a Y-axis axis are arranged with respect to a toroidal core 2c having a Z-axis axis wound around Azimuth detection device comprising a magnetic sensor 2, an excitation circuit 3 for exciting the excitation coil 2b with a pulse excitation signal Sb, and a signal processing system 4x, 4y for processing the detection signals Sx, Sy of the detection coils 2x, 2y, respectively. 1 is configured, in particular, the signal processing system 4x (4y
The same applies to the side), a gain setting circuit 5 for setting different gains corresponding to the azimuth range with respect to the detection signal Sx of the detection coil 2x is provided.

In this case, the signal processing system 4x includes the detection coil 2
It can be configured by including a separation circuit 6 that separates the detection signal Sx of x into a positive component Sxp and a negative component Sxn. The gain setting circuit 5 can be configured to set the gain for each of the positive side component Sxp and the negative side component Sxn. For example, the integration resistors 8, 9, 1 in the integration circuit 7 of the signal processing system 4x can be set.
The gain can be set by switching the resistance values of 0 and 11.

[0009]

According to the azimuth detecting device 1 of the present invention, first,
The azimuth detected by the X-direction detection coil 2x (same for the 2y side) is set in two ranges (generally a plurality), that is, two ranges obtained by dividing 360 ° into the north side and the south side. And
When the X-direction detection coil 2x detects the north side range, the gain setting circuit 5 sets the first gain, and when the south side range is detected, the gain setting circuit 5 sets the second gain different from the first gain. Set the gain of. In this case, the gain is set by, for example, switching the analog switch in the gain setting circuit 5 so that the integration resistors 8, 9, 10, 1 having different resistance values in the integration circuit 7 are set.
1 can be selected and set.

Therefore, the X-direction detection coil 2x is previously prepared.
The gain setting circuit 5 is configured so that the magnitude (absolute value) of the detection signal Sx when the north or the south is detected becomes the same.
If the gain is set, the detection signal Sx on the north side and the detection signal Sx on the south side are balanced and a relative error is eliminated even if the toroidal core 2c of the magnetic sensor 2 has a variation in sectional area.

In the flux gate type magnetic sensor 2, the exciting coil 2b is excited by the pulse exciting signal Sb supplied from the exciting circuit 3, whereby the size of the X-direction detecting coil 2x changes according to the direction. Detection signal S
x is obtained. The detection signal Sx is processed by the signal processing system 4x, and an output value corresponding to the azimuth is obtained from the signal processing system 4x. Further, the detection signal S of the detection coil 2x
x is a positive side component Sxp and a negative side component Sxn by the separation circuit 6.
The gain can be set for each component Sxp and Sxn.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, preferred embodiments according to the present invention will be described in detail with reference to the drawings.

First, in order to clarify the present invention, an overall schematic configuration of the azimuth detecting apparatus 1 will be described with reference to FIG.

In FIG. 3, reference numeral 2 denotes a flux gate type (double frequency modulation type) magnetic sensor, which includes a toroidal core 2c around which an exciting coil 2b is wound, an X direction detecting coil 2x and a Y direction detecting coil 2y. X direction detection coil 2
The x-direction and Y-direction detection coils 2y are wound in a ring shape and are arranged in a right-angled relationship with their centers being coincident with each other.
The axis of the direction detection coil 2y is relatively arranged in the Y direction. Furthermore, the toroidal core 2c is arranged inside the X-direction detection coil 2x and the Y-direction detection coil 2y,
The centers are made to coincide with each other, and their axes are relatively arranged so as to be in the Z direction. Therefore, the magnetic sensor 2 in FIG.
Displace in the direction of arrow A to face north, south, east, and west. The direction of geomagnetism is indicated by arrow F.

On the other hand, 3 is an exciting circuit, which has a function of exciting the exciting coil 2b by supplying the pulse exciting signal Sb to the exciting coil 2b.

On the other hand, 4x and 4y are two systems of signal processing system, and the detection signals Sx and Sy from the detection coils 2x and 2y are supplied to the input side thereof, respectively. The output sides of the signal processing systems 4x and 4y are connected to the azimuth calculation unit 15. The azimuth calculation unit 15 obtains final azimuth information Do from the output values corresponding to the azimuths obtained by the signal processing systems 4x and 4y, and gives the final azimuth information Do to, for example, a display unit, a data processing unit, or the like (not shown).

Next, the configuration of the signal processing system that constitutes the main part of the azimuth detecting apparatus 1 according to the present invention will be specifically described with reference to FIG. Two signal processing systems 4x, 4
Since all y have the same basic configuration, only one signal processing system 4x will be described below.

In FIG. 1, 2x indicates an X-direction detection coil, and this detection coil 2x is connected to the input side of the amplifier circuit 21. The output side of the amplifier circuit 21 is connected to the input side of the integration circuit 7 including the gain setting circuit 5 and the separation circuit 6. The gain setting circuit 5 has four integrating resistors 8, 9, 10, 11 whose one end is connected to the output side of the amplifier circuit 21, and
It has analog switches 22, 23, 24, 25, one end of which is connected to the other end of each of the integrating resistors 8, 9, 10, 11. The integrating resistors 8, 9, 10 and 11 may be fixed resistors whose resistance values are selected in advance, but it is desirable to use variable resistors so that each resistance value can be arbitrarily changed.

Two analog switches 22 and 23 are also provided.
Is connected to one end of the analog switch 26, and the other ends of the other two analog switches 24 and 25 are connected to one end of the analog switch 27. In FIG. 1, Si,
Sj, Sp and Sn are analog switches 22, 23 and 2 respectively.
The open / close control signals of 4, 25, 26 and 27 are shown.

By the way, if the X-direction detection coil 2x detects the north-south direction, the direction detected by the coil 2x is divided into two ranges, that is, 360 ° is divided into two ranges which are divided into the north side and the south side. Set and turn on analog switches 22 and 24 to detect the north range, and analog switch 2 to detect the south range.
It is configured so that 3, 25 are turned on. In this case, the detection signal Sx of the X-direction detection coil 2x has a maximum negative output in the south azimuth and a maximum positive output in the north azimuth. Integral Sx
An azimuth in which the size of n is the same is defined as a switching point of each switch. The analog switch 25 is turned on when the detection signal Sx is the positive side component Sxp, and the analog switch 26 is turned on when the detection signal Sx is the negative side component Sxn.

Therefore, in the gain setting circuit 5, the gain is set in advance so that the magnitude (absolute value) of the detection signal Sx when the north or the south is detected by the X-direction detection coil 2x becomes the same, that is, Each integration resistance 8, 9,
The magnitude of the resistance value at 10 and 11 is variably set.

On the other hand, the other ends of the analog switches 26 and 27 are respectively connected to the inverting input section of the operational amplifier 28, and the inverting input section and the output section of the operational amplifier 28 are connected by the integrating capacitor 29, and the operational amplifier 28 is not connected. The inverting input is grounded. On the other hand, the output section of the operational amplifier 28, which is the output section of the integrating circuit 7, is connected to the input side of the hold circuit 30, and the output side of the hold circuit 30 is connected to the input side of the output circuit 31. The side is connected to the azimuth calculation unit 15 described above.

Next, the operation of the azimuth detecting apparatus 1 including the signal processing system 4x will be described with reference to FIGS.

First, the exciting coil 2b is excited by the pulse exciting signal Sb of 5 to 10 kHz shown in FIG.

On the other hand, if the X-direction detection coil 2x detects the north-south azimuth, the X-direction detection coil 2x will detect the azimuth according to the direction (direction) of the X-direction detection coil 2x.
The detection signal Sx including the positive side component Sxp and the negative side component Sxn shown in (B) is obtained. The detection signal Sx is given to the amplifier circuit 21, amplified, and then given to the gain setting circuit 5.

If the azimuth detected by the X-direction detection coil 2x is in the south side, the analog switches 23 and 2 will be used.
Since 5 is turned on, the integrating resistors 9 and 11 are selected. On the other hand, the analog switch 26 is provided with the switching control signal Sp shown in FIG. 2C, while the analog switch 27 is provided with the switching control signal Sn shown in FIG. The positive side component Sxp of the detection signal Sx is given to the inverting input section of the operational amplifier 28 via the integrating resistor 9, and the negative side component Sxn is given to the inverting input section of the operational amplifier 28 via the integrating resistor 11. This allows
The respective components Sxp and Sxn are integrated by the integrating circuit 7,
The integrating circuit 7 has reset signals Ss and S shown in FIG.
Since it is controlled by r, the output of the integrating circuit 7 is shown in FIG.
A sawtooth-shaped integrated output signal Sm that is repeated in a cycle of several msec as shown in (F) is obtained. In this case, the inclination angle of the signal waveform in the integrated output signal Sm changes according to the azimuth.

The integrated output signal Sm is held by the hold circuit 30 by the latch signal Sh shown in FIG. 2 (G) to hold an instantaneous value near the maximum value in the integrated output signal Sm.
Output to the outside via the output circuit 31. In this case, the output value from the output circuit 31 becomes a value corresponding to the azimuth.

On the other hand, if the azimuth detected by the X-direction detection coil 2x is in the north side, the analog switches 22, 2
4 is turned on and the integration resistors 8 and 10 are selected. Therefore,
Even if there are variations in the cross-sectional area of the toroidal core 2c of the magnetic sensor 2, the gain setting circuit 5 balances the absolute values of the detection signals Sx on the north side and the south side, so that the error of the detection signal Sx is eliminated. . Specifically, the azimuth error, which was about ± 7 ° in the past, is ± 1 according to the present invention.
I was able to improve to about °.

The Y-direction detection coil 2y detects the azimuth in the east-west direction, and the signal processing system 4y functions (operates) similarly to the above-mentioned signal processing system 4x.

Although the embodiments have been described in detail above, the present invention is not limited to such embodiments, and detailed circuit configurations and the like can be arbitrarily changed without departing from the gist of the present invention.

[0031]

As described above, according to the present invention, an X-direction detection coil having an X-axis axis and a Y-axis having a Y-axis axis with respect to a toroidal core having an Z-axis axis wound around an exciting coil. In a azimuth detecting device comprising a flux gate type magnetic sensor in which a direction detecting coil is arranged, an exciting circuit for exciting the exciting coil with a pulse exciting signal, and a signal processing system for processing the detection signal of each detecting coil, Since the signal processing system is provided with a gain setting circuit that sets different gains corresponding to the azimuth range with respect to the detection signal of the detection coil, even if the toroidal core of the magnetic sensor has variations in cross-sectional area, etc. The remarkable effect that the error accompanying this can be reduced and an accurate and highly accurate direction detection can be performed.

[Brief description of drawings]

FIG. 1 is a block circuit diagram of a signal processing system of an azimuth detecting device according to the present invention,

FIG. 2 is a time chart of signals in each part of the signal processing system,

FIG. 3 is an overall schematic configuration diagram of the same direction detection device,

FIG. 4 is an explanatory view of a conventional technique,

[Explanation of symbols]

 1 azimuth detecting device 2 flux gate type magnetic sensor 2b excitation coil 2c toroidal core 2x X direction detection coil 2y Y direction detection coil 3 excitation circuit 4x signal processing system 4y signal processing system 5 gain setting circuit 6 separation circuit 7 integration circuit 8 ... integration Resistance Sb Pulse excitation signal Sx Detection signal Sy Detection signal Sxp Positive component Sxn Negative component

Claims (4)

[Claims] 1. An X-direction detection coil having an X-direction axis and a Y-direction detection coil having a Y-direction axis are arranged with respect to a toroidal core having an Z-direction axis wound around an exciting coil. In the azimuth detection device, the signal processing system includes a flux gate type magnetic sensor, an exciting circuit for exciting the exciting coil with a pulse exciting signal, and a signal processing system for processing the detection signals of the respective detecting coils. An azimuth detecting apparatus comprising: a gain setting circuit that sets different gains corresponding to the azimuth range for the detection signal. 2. The azimuth detecting device according to claim 1, wherein the signal processing system includes a separation circuit for separating the detection signal of the detection coil into a positive side component and a negative side component. 3. The azimuth detecting device according to claim 1, wherein the gain setting circuit sets a gain for each of the positive side component and the negative side component. 4. The azimuth detecting device according to claim 1, wherein the gain setting circuit sets the gain by switching the resistance value of the integrating resistor in the integrating circuit of the signal processing system.