JPH02218911A - Bearing meter for vehicle - Google Patents

Abstract

PURPOSE:To correct the bearing errors of wheels due to geomagnetism disturbance by estimating the maximum point and the initial point of the disturbance even if the disturbance is large and the indication is deviated out of the dynamic range of a geomagnetism bearing sensor, and computing the disturbance. CONSTITUTION:In a geomagnetism bearing sensor 1, the geomagnetism component is decomposed into the orthogonal two directions. The geomagnetism component in each direction is outputted as an electric signal. The output of the sensor 1 is converted into a digital signal in an output processing circuit 2. In a bearing detecting part 3, the bearing is detected based on the output signal from the sensor 1. In a disturbance-quantity operating part 4, the magnitude of the disturbance is estimated based on the time when the output of the sensor 1 stays in the measuring limit when the output of the sensor 1 exceeds the dynamic range. The maximum point and the initial point of the disturbance are obtained. Thus the disturbance quantity is computed. In a body magnetization detecting part 5, the presence or absence of magnetization is detected based on the disturbance quantity obtained in the operating part 4. In a magnetization operating part 6, the magnetized quantity is detected based on the disturbance quantity obtained in the operating part 4 and the coordinates of the center of the bearing circle from the detecting part 3 and fed back to the detecting part 3.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a vehicle direction meter that detects the running direction of a vehicle using a geomagnetic direction sensor, and particularly relates to a technique for accurately detecting magnetic disturbances.

(Prior Art) As a device for detecting the running direction of a vehicle using a geomagnetic direction sensor, for example, the device shown in Japanese Patent Laid-Open No. 100812/1983 is known.

The above-mentioned vehicle azimuth sensor uses a geomagnetic azimuth sensor in which a pair of windings are orthogonally crossed in a horizontal position, and these windings each obtain a geomagnetic component detection voltage (output value) according to the interlinking geomagnetism. It is being

When a vehicle travels around in a uniform geomagnetic field.

A circle (output circle of the geomagnetic direction sensor) is drawn on the coordinate plane by the coordinates indicated by the detected voltages of these windings. Therefore, during normal running of the vehicle, the direction from the center of the output circle to the coordinates indicated by the detected voltages of both windings is determined as the running direction of the vehicle.

In the vehicle direction meter as described above, when the vehicle body is magnetized, the center coordinates of the output circle shift, which causes an error in detecting the running direction. In order to correct this error, when the vehicle is magnetized, the vehicle turns, samples the output value of the geomagnetic direction sensor an appropriate number of times, and when the vehicle completes the turn, the sampled output value is It is configured to correct the error in detecting the traveling direction on average.

Another vehicular azimuth using a geomagnetic azimuth sensor is disclosed in, for example, Japanese Patent Application Laid-Open No. 63-48415. The method of magnetization correction in this compass is as follows:
Draw multiple virtual X-axes and virtual Y-axes parallel to the X-axis and Y-axis on the vx-vy plane of the compass output, and if the compass output is 2 points on the virtual X-axis and 2 points on the virtual Y-axis, respectively. This is for magnetization correction.

[Problem to be solved by the invention]

However, the conventional device as described above has the following problems.

First, in the former device, even if the magnetic field environment is bad when performing correction, averaging processing is performed using a small sampling output value, so it is not possible to obtain the center coordinate position with high accuracy. Moreover, there is a problem in that the driver is forced to make one round (360°) turn when making the correction.

In addition, in the latter device, two orthogonal axes (X axis, Y axis,
Since two points of intersection are required for each axis (axis) and the azimuth circle, azimuth data of at least 180° or more is required to measure the intersection.

However, in reality, it is rare for a vehicle to turn more than 180° immediately after being magnetized, so the compass output until azimuth data of 180° or more is collected.

There was a problem that the direction was far different from the actual direction.

In order to solve the above problems, the present applicant has developed a vehicle direction indicator (Japanese Patent Application No. 1983-203167) that can accurately detect when the vehicle body is magnetized, and a We have already filed an application for a vehicle compass (Japanese Patent Application No. 64-525) that can automatically perform magnetization correction without turning.

The method for calculating the amount of magnetic disturbance in the above vehicle compass is as follows:
The initial point of the disturbance was determined by averaging a specified number of geomagnetic direction sensor output points before the disturbance occurred, and the maximum point of the disturbance was the point farthest from the center point of the geomagnetic direction sensor output circle.

However, in the above method of calculating the amount of disturbance, the initial point is the average of the output points of the geomagnetic direction sensor, so in places where the geomagnetic field is highly disturbed, such as when waiting for a train to pass at a railroad crossing, it is difficult to obtain an accurate initial point. Points cannot be calculated. Regarding the maximum point, when a disturbance that exceeds the measurement range (dynamic range) of the geomagnetic direction sensor occurs, the limit point of the measurement range is indicated as the maximum point, making it impossible to calculate the accurate maximum point. There is a problem that there is no
Therefore, when the disturbance is large, accurate correction is difficult.

The present invention has been made in order to solve the above problems, and as already filed by the above applicant,
When a magnetic disturbance occurs, a vehicle compass can accurately calculate the center coordinate position of the azimuth circle after magnetization without making a turn for correction when the vehicle is magnetized. It is an object of the present invention to provide a vehicular azimuth meter that can accurately predict an initial point and a maximum point and accurately calculate a disturbance amount for azimuth circle correction.

[Means to solve the problem]

In order to achieve the above object, the present invention is constructed as described in the claims.

Hereinafter, the present invention will be explained in detail based on the functional block diagram shown in FIG.

In FIG. 1, a geomagnetic orientation sensor 100 is mounted on a vehicle and detects the geomagnetic orientation at the current location of the vehicle as geomagnetic data of two mutually orthogonal directional components. This corresponds to the geomagnetic direction sensor 1 (details are explained in FIG. 3).

Further, the magnetic disturbance detection means 110 includes the geomagnetic direction sensor 1
This is means for detecting that a geomagnetic disturbance has occurred based on the geomagnetic data detected at 00.

Further, the disturbance maximum point detection means 120 is a means for detecting the maximum point of disturbance when geomagnetic disturbance occurs. Note that this means is a means for detecting when the maximum point is within the dynamic range.

Further, the out-of-measurement-range detection means 130 is means for detecting that the magnitude of the disturbance exceeds the dynamic range of the geomagnetic azimuth sensor.

Further, the disturbance prediction calculating means 140 is a means for predicting the magnitude of the disturbance outside the detection range from the time when the magnitude of the disturbance exceeds the detection range (dynamic range) of the geomagnetic azimuth sensor. .

Further, the disturbance direction calculating means 150 is means for calculating the direction of the disturbance by finding the locus of the disturbance.

Further, the maximum point prediction calculation means 160 is a means for predicting the maximum point of a disturbance based on the predicted magnitude and direction of the disturbance when the magnitude of the disturbance exceeds the dynamic range of the geomagnetic azimuth sensor. .

Further, the initial point prediction calculation means 170 is means for calculating an initial point from the direction of the disturbance, the maximum point, and the output circle of the geomagnetic azimuth sensor before the occurrence of the disturbance determined by each of the above-mentioned means.

Further, the disturbance amount calculating means 180 is means for calculating the amount of disturbance, that is, the distance between the maximum point and the initial point, from the maximum point and initial point obtained by each of the above-mentioned means.

The above magnetic disturbance detection means 110. Disturbance maximum point detection means 1
20. Outside measurement range detection means 130, disturbance prediction calculation means 1
40, disturbance direction calculation means 150. Maximum point prediction calculation means 1
60, each of the initial point prediction calculation means 170 and the disturbance amount calculation means 180 is, for example, the disturbance amount calculation section 4 shown in FIG.
Specifically, it is composed of, for example, a computer.

[For production]

As described above, in the present invention, when the output of the geomagnetic direction sensor exceeds the dynamic range, the magnitude of the disturbance is predicted (time The larger the disturbance, the larger the disturbance), and the locus of the disturbance (direction of the disturbance)
is detected, and the point where the straight line of the above trajectory is extended to the outside of the output limit line by a distance corresponding to the magnitude of the disturbance predicted above is set as the maximum point, and the point between the above trajectory and the output circle before the disturbance occurs is One of the two intersection points is selected as the initial point in relation to the maximum point, and the distance between the maximum point and the initial point is used as the disturbance amount.

〔Example〕

Hereinafter, preferred embodiments of the vehicle compass according to the present invention will be described based on the drawings.

FIG. 2 is a block diagram showing the configuration of one embodiment of the vehicle compass according to the present invention.

In FIG. 2, the geomagnetic direction sensor 1 separates the geomagnetic component into two orthogonal directions on a horizontal plane and outputs the geomagnetic component in each direction as an electrical signal.

Further, 2 is an output processing circuit that converts the output of the geomagnetic azimuth sensor 1 into a digital signal, 3 is an azimuth detection unit that detects the azimuth from the output signal of the geomagnetic azimuth sensor 1, and 4 is a disturbance amount calculation unit that is the main focus of the present invention. , 5 is a vehicle body magnetization detection section for detecting magnetization of the vehicle body, and 6 is a magnetization amount calculation section. Note that the above-mentioned azimuth detection section 3, disturbance amount calculation section 4. The vehicle body magnetization detection section 5 and the magnetization amount calculation section 6 are configured by, for example, a computer.

Each of the above parts will be explained in detail below.

FIG. 3 is an example diagram of the geomagnetic direction sensor 1.

In FIG. 3, the annular permalloy core 6 is provided with windings 7X and 7Y that are orthogonal to each other. Furthermore, a winding 8 is wound around the permalloy core 6. This winding 8 is energized by an excitation power source 9, and is energized until just before the permalloy core 6 is saturated, as shown in the characteristics shown in FIG.

When the geomagnetic direction sensor 1 as described above is placed in a non-magnetic field, the magnetic fluxes Φ1 and Φ passing through the parts S1 and S2 of the permalloy core 6, respectively, have the same magnitude and direction, as shown in FIG. is the opposite.

Therefore, the magnetic flux interlinking with the winding 7X becomes zero, and the detected voltage Vy of the winding 7Y also becomes zero.

Furthermore, as shown in FIG. 3, when the earth's magnetic field He is applied perpendicularly to the winding 7X, the magnetic flux is biased within the permalloy core 6 by the magnetic flux density Be=μHa (μ is the magnetic permeability of the permalloy core 6). given, the magnetic flux Φ and Φ2 are the sixth
As shown in the figure, it becomes asymmetrical.

Therefore, a detection voltage v8 having a waveform as shown in FIG. 7 is obtained in the winding 7X.

In the case of FIG. 3, since the earth's magnetism Ha is parallel to the winding 7Y, the earth's magnetism He does not intersect with the first winding 7Y, and therefore no voltage Vy is generated in the winding 7Y.

This geomagnetic direction sensor 1 is mounted on a vehicle in a horizontal position as shown in FIG.
Detection voltages V- and Vy (output values) corresponding to the earth's magnetic field He are obtained respectively.

Those detection voltages Vx, Vy are determined by using the value K as the winding constant and the value B as the winding constant.
If is the horizontal component of geomagnetic He, then the following (1) and (2)
It will be shown by the formula.

Vx=KB cos θ-(1) Vy''KB sin θ (2) Therefore, if the width direction of the vehicle is used as a reference as shown in FIG. 8, the angle θ indicating the running direction is expressed by the following equation (3).

θ=jan-”(Vx/vy)...(3) And as understood from the above equations (1) and (2), when the vehicle runs around in the uniform geomagnetic He, the winding 7X, 7
At the coordinates indicated by the detected voltages Vx and Vyt' of Y, a circle is drawn on the X-Y plane coordinates as shown in FIG.

The output circle of the geomagnetic direction sensor 1 as described above is as follows (4
) is shown by the formula.

Vx" + Vy2 = (KB)" - (4) In this way, the detection voltages V, , v of the windings 7X and 7Y.

Since the coordinates determined by are on the output circle, the direction detection unit 3 in FIG. I can do it.

By the way, when the vehicle body is magnetized, for example, as shown in FIG.
7Y, the output circle moves from the broken line position to the solid line position as shown in FIG.

As a result, an error occurs in the detection of the running direction of the vehicle performed by the direction detecting section 3.

The above errors are caused by magnetization of the vehicle body, and the magnetization of the vehicle body that causes this error is caused by magnetic disturbance.

The disturbance amount calculation section 4, which is the main focus of the present invention, will be explained below.

FIGS. 12(A), 12(B), and 12(C) are flowcharts showing an embodiment of disturbance amount calculation according to the present invention.

First, in FIG. 12(A), steps 300 to 41
0 indicates calculation of geomagnetic disturbance detection.

In FIG. 12(A), in step 300, each flag and variable used in the calculation is initialized, and the center value of the azimuth circle (cx, cy, that is, the center value of the azimuth circle
(Y coordinate) and the azimuth circle radius R.

Next, in step 310, it is determined whether or not there is any unprocessed sensor output data, and if all data has been processed, the process goes to [2] in FIG. 12(C).

On the other hand, if there is unprocessed data, step 320
Go to and input the azimuth data (X, Y) of the geomagnetic azimuth sensor.

Next, in step 330, the distance between the center value of the azimuth circle and the input azimuth data is calculated based on the following formula.

L=((X-CX)"+(Y-CY)2)"Next, in steps 340 to 360, the output data is
It is determined whether the disturbance start determination point 2 shown in the figure has been reached.

First, in step 340, a flag F1 indicating whether or not the output data has reached the disturbance start judgment point 2 is determined. If not, step 3
Whether L<SL at 50.

That is, it is determined whether disturbance start determination point 2 has been reached. If YES, step 360 (F 1
= 1.5LX==X, 5LY=Y), and if it has not been reached, the process directly proceeds to step 370. In addition,
If NO in step 340, that is, if the disturbance start determination point 2 has already been reached by the previous time, the process directly proceeds to step 370.

Next, in steps 370-390, as above.

Determine whether disturbance start judgment point 1 in Figure 13 has been reached (F2
is a flag indicating whether or not the disturbance start judgment point 1 has been reached), and if it has been reached in this calculation, step 390
(F2=1, LLX=X, LLY=Y, MX=X, M
Y=Y), and if it has not been reached, proceed to step 400 without doing anything.

Next, in steps 400 and 410, flag F1. F2
It is determined whether the output data has reached the disturbance start judgment point or not. If the output data has not reached the disturbance start judgment point (if both Fl and F2 are O), the process directly proceeds to step 420. If at least one of disturbance start determination points 1 and 2 has been reached, the process proceeds to [1] in FIG. 12(B).

Next, in FIG. 12(B), steps 430 to 46
0 indicates the calculation for detecting the maximum disturbance point.

First, in step 430, a flag F3 indicating that the output data exceeds the dynamic range of the geomagnetic azimuth sensor is determined. If it has not been exceeded in the previous calculations (F3=O), it is determined in step 440 whether the distance 1iL between the center value and the output data is greater than the distance RMAX so far, and if it is, In step 460, the maximum value is updated, and the flag F4 indicating whether or not the disturbance is increasing is set to O (F44-0.R
MAX←R, MX4-X, MY4-Y). Step 44
0 and if L is less than RMAX, the above flag F
Set 4 to 1.

Next, in steps 470 to 490, if the flag F4 is 1, that is, if L is smaller than the previous value, it is determined whether the output data has decreased below the disturbance end reference value EL (L<EL). If the determination is YES, it is determined that the disturbance has ended and the end flag F5 is set to 1.

On the other hand, if the disturbance is large (step 470=
NO), the calculations in steps 500 to 540 are performed.

In steps 500 to 540, it is determined whether the sensor output exceeds the dynamic range.

That is, in steps 500.510.520.530, the maximum values (LEX, LEY) and minimum values (-LEX, -) of the dynamic range are determined for X and Y, respectively.
LEY) and L, and if any one of them is YES, the process goes to step 540, where the time T during which the output exceeds the dynamic range is measured and the flag F3 is set to 1.

On the other hand, if it is determined in steps 500 to 540 that the sensor output does not exceed the dynamic range.

Go to [3] in FIG. 12(A), that is, step 420.

In step 420, it is determined whether the end flag F5 is 1 or not.

That is, it is determined whether or not the disturbance has ended, and if it has not ended, the process returns to step 310 and processes the next data again.

On the other hand, if F5=1 in step 420, FIG.
Proceed to step 550 of C).

In step 550, an approximate equation of disturbance (a X+ b Y
=c) is created. In other words, this disturbance approximation formula is the 13th
It represents the locus of the disturbance shown by the broken line in the figure, and can indicate the direction of the disturbance.

Note that the trajectory of the disturbance is determined by the coordinates of the disturbance start judgment point 1 or 2 (
LLX, LLY or SLX, 5LY) and the coordinates of the measurement limit point (LMX, LMY), so
The respective coefficients a, b, and c of the above approximate expression aX+bY=c can be determined from the coordinates of the above-mentioned disturbance start judgment point and measurement limit point.

Next, in step 560, it is determined whether or not the disturbance exceeds the dynamic range of the geomagnetic direction sensor based on whether the flag F3 is 1. If the disturbance exceeds the dynamic range, the process proceeds to step 570 to predict the amount of disturbance. .

The prediction method in this step is to conduct an experiment in advance to determine the relationship between the magnitude of the disturbance FL and the time T (the duration of time outside the dynamic range) determined in step 540, and to form a corresponding relational expression. By asking for
The magnitude of the disturbance is calculated from the above time T using the relational expression. In other words, in this embodiment, the duration of time during which the output data is outside the dynamic range (the time from exceeding the measurement limit point to returning to point r in Figure 13), during which the output of the geomagnetic direction sensor is outside the measurement limit. The longer the value (fixed at the point value) is, the larger the disturbance magnitude FL is. The purpose is to find the relationship as follows.

Note that the above relational expression can be calculated using, for example, F
By using a formula such as 1T2+ for L= and 3 for T+, and calculating the above coefficients k2 and k3 by experiment,
FL can be calculated from time T.

Next, in step 580, the maximum disturbance point (px, PY) is predicted using the predicted disturbance magnitude FL and the disturbance approximation formula set in step 550. That is, the maximum point is predicted from the magnitude of the disturbance and the direction of the disturbance.

Furthermore, if the output data is within the dynamic range,
Maximum point detection is ended with the maximum point left as is.

Next, in step 590, the above disturbance approximation formula (aX+
bY=c) and geomagnetic azimuth circle approximation formula ((X-cX) 2+
(Y−cY)”=R) is found as a solution to the above two simultaneous equations, and the process proceeds to step 600.

In step 600, it is determined whether or not the two solutions of the simultaneous equations in step 590 have been found.

If no solution has been found, the process proceeds to step 620, where the center value of the azimuth circle is set as the initial point.

On the other hand, if a solution has been found, the process advances to step 610;
Steps 630 and 64 depending on whether the flag Fl is 1 or not.
0 selects one of the two solutions. That is, in the case of F1=1 (when the output data has reached disturbance start judgment point 2), the one farther from the maximum point (initial point A in Fig. 13) of the two solutions is set as the initial point, and F1 If =0, the one closest to the maximum point (initial point B in FIG. 13) is set as the initial point.

Next, in step 650, the amount of disturbance is calculated based on the following formula.

Disturbance t XMAX: l PX-8X IYMAX
= l PY-3Y l That is, the amount of disturbance is the distance from the initial point to the maximum point determined in the X direction and the Y direction. Note that this calculation is performed using the initial points (SX, S
Y) and the maximum point (px, py).

As described above, even if the magnitude of the disturbance is outside the dynamic range of the geomagnetic azimuth sensor, the maximum point, initial point, disturbance direction, and amount of disturbance can be accurately predicted.

In other words, as shown in Figure 13, when a disturbance occurs,
The output of the geomagnetic direction sensor reaches the maximum point from the initial point (either A or B) through the disturbance start determination point 1 or 2. If the maximum point is within the dynamic range of the geomagnetic direction sensor (within the output limit judgment line), that point can be directly determined, but as shown in the figure, if the maximum point exceeds the output limit judgment line, The output of the geomagnetic direction sensor remains at the measurement limit point or point r, and when the disturbance decreases and returns within the dynamic range, the output appears at point r and decreases toward the disturbance end judgment point. Therefore, in the present invention, the magnitude of the disturbance is predicted from the time during which the output of the geomagnetic azimuth sensor remains at the measurement limit point or point r (the longer the time, the greater the disturbance), and the disturbance start judgment point 1 or 2 is predicted. Detect the disturbance trajectory (the direction of the disturbance) from the straight line connecting the and the measurement limit point, and extend the straight line of the above trajectory to the outside of the output limit line by a distance corresponding to the predicted disturbance magnitude, and then set the maximum point. In addition, one of the two intersection points of the above trajectory and the output circle before the disturbance is selected as the initial point in relation to the maximum point, and the distance between the maximum point and the initial point is the disturbance amount. That is.

In addition, in FIG. 13, the output limit judgment line is X,
Although only the positive direction of Y is shown, it naturally exists in the negative direction as well.

The above is the calculation in the disturbance amount calculation section 4 shown in FIG. 2.

Next, the vehicle body magnetization detection unit 5 of FIG. 2 determines whether the amount of disturbance calculated by the disturbance amount calculation unit 4 is greater than 1, for example, 450 milliGauss at the level of geomagnetic intensity,
If it is large, it is determined that the vehicle body is magnetized. In addition,
If it is less than 450 milligauss, it is determined that the disturbance is not large enough to magnetize the vehicle body.

Next, the contents of calculation in the magnetization amount calculation section 6 will be explained based on FIG. 14.

In FIG. 14, step 700 corresponds to the calculation of the vehicle body magnetization detection section 5.

If it is determined in step 700 that magnetization has occurred, the process proceeds to step 710, where the disturbance amounts (X-ax, Y-ax) calculated by the disturbance amount calculation section 4 and the maximum point coordinate (px) are determined.

PY) and initial point coordinates (SX, SY).

Further, in step 720, the azimuth circle center coordinate [(output circle center coordinate O in FIG. 9) is input from the azimuth detecting section 3.

Next, in step 730, the direction coefficient of the disturbance is calculated based on the following formula.

Directional coefficient Dx=(Px −Sx)/(I Px −S
x I )D so=(Py-5y)/(l Py-5v
l) That is, the direction coefficient is the direction of the maximum point viewed from the initial point, that is, the direction of the X and Y coordinates of the maximum point when the initial point is the origin, expressed as positive or negative (+1 or -1). This calculation is performed using the initial point (SX, SY) and maximum point (px, py) input in step 710 above.

Next, in step 740, as shown in FIG. 16 below, a base point B1 and a base point B2 are set at points that the center value coordinates of the azimuth circle that moves due to vehicle body magnetization do not exceed. Calculate the XY two-component (7) distance 1iLXi, LX, LY, LY, from the azimuth circle center coordinate o.

In addition, LX□=Ox-Blx LX, =B2X-OX LY1=Oy-B 1y lY, =B2y-Oy However, ○X: X coordinate of o OY: Y coordinate of 0 Blx: Bl (7) X coordinate Bly : Y coordinate of B1 B2x: B2 (7) X coordinate B2y: Y coordinate of B2. The above base points Bl and B2 indicate the limits of the range in which the azimuth circle moves by one magnetization, and B1 is l.
The limit in the negative direction of the Y axis, B2 is the limit in the positive direction. Note that this value is set to a reasonable value in experiments, but since it does not vary depending on the vehicle type, it can be applied to all vehicle types by determining -degrees.

The origin of the coordinate system in this example is basically the center position Os of the output circle when there is no magnetization, but the center value of the output circle before magnetization is set as follows for convenience of handling: As mentioned above, the distances LX from the base points Bl and B2 are indicated by LX2, LYl, and LY2.

Next, in step 750, coefficient settings for calculating the amount of magnetization (a□.~a7nab1yo~b7.) are performed.

These coefficients are set in accordance with the above-mentioned disturbance amount, direction coefficient, and output circle center value before magnetization (the above-mentioned values of LX1, LY) as parameters (details will be described later).

Next, in step 760, the disturbance amount and the output circle center value, that is, the distances LX1, LX2, L obtained in step 740 are determined.
Using Y□, LY2 and the coefficient set in step 750, the magnetization amounts ΔX and ΔY are calculated by the following formulas.

Note that the above coefficients and the calculation formulas below are determined in advance using experimental data and the like, for example, by a method such as multiple regression analysis.

ΔX= aln+ a2nXmax+ a3nXjsa
x+ a4nxllax・L X1+ a sn(Xm
ax” L Xl)”+a@nXaax・L Xl +
a 7n(Xmax"L Xl)"ΔY=bl
, +b, -Y-ax+ b3-Y"-ax+ b 4-
Y-ax-L Yx +b 5-(Y-ax-L Yx
)” 10 b s-Y-ax-L Y z + b t-(
Y-ax-L Y 2)” Next, in step 770,
Calculate the azimuth circle center value 0' after the vehicle body is magnetized.

1. X coordinate of center value 0' after magnetization ○'X and Y coordinate 0'
y is O'xwOx+ΔX, O'v=Ov+
ΔY.

Next, in step 780, the center value after magnetization ○'
Send +0'Y to the direction detection unit 3 and obtain the new center value Ox, OY
shall be.

When the car body is magnetized by the above calculation process,
Since the coordinates of the center position of the output circle after magnetization can be calculated quickly and reliably, the accurate orientation of the vehicle can be detected at all times.

Next, the coefficient setting in step 750 will be explained based on FIG. 15.

In the calculation shown in FIG. 15, first, the coefficients for calculating the X component are set.

First, in step 800, the direction coefficient DX of the X component is determined, and if it is negative (DX<O), step 810
If the result is positive (DX>O), the process advances to step 880.

The case where the X-component direction coefficient is negative will be described below.

First, in step 810, the amount of disturbance Xmax is compared with a predetermined value Ki, and if Xmax≦, the process proceeds to step 820, and if X-ax>Kx, the process proceeds to step 850.

If the process proceeds to step 820 when the above X i+ a Proceeding to step 830, the coefficients for calculating the X component are set to a□1, a21, . . . a7□. Also L
If X□>Ka, the process advances to step 840, and the coefficients for calculating the X component are set to ai2, aaa, . . . atz.

Also, if X-ax>K□ in step 810 and the process proceeds to step 850, step 85
Compare the azimuth circle center value LX□ with 2 to a predetermined value at 0, and LX
If 1≦2, proceed to step 860;
60, the coefficient for calculating the X component is alf, aaa...a7
Set to 3. Also, LX〉If it is K2, step 87
Proceed to 0 and modify the coefficient for calculating the X component ai4...a
Set to i4.

The above explanation is based on an example in which the X-component direction coefficient DX is determined to be negative in step 800, but even if the X-component direction coefficient is positive, the coefficients are determined in steps 880 to 940, respectively. Set.

As described above, in steps 800 to 940, a set of X component calculation coefficients a1n, a, □, .

Also, in setting the Y component coefficient, similarly to the above, steps 1000 to 1140 are used to calculate the Y component calculation coefficient b.
ln, bNn... A set of b and n is set.

Note that the coefficients (ai.~a 7
The actual value of n a b 1 m"" b 7 m) changes depending on the shape of the car body (for example, sedan or 1-box type), so it is determined in advance according to the car type, and then the parameter is calculated using the above calculation. Select and set the corresponding value.

Moreover, the value of each predetermined value in the calculation of the above-mentioned X component and Y component is, for example, K□=500. K2=1500. K3
=500. K, is a value of about 1500.

As described above, in this embodiment, the component calculation coefficients are set corresponding to the amount of disturbance, the direction coefficient, and the center position of the circle before magnetization, and the reason is as follows.

First, in the calculation of this embodiment, since the central value calculation from the base point is changed depending on the direction of the disturbance, it is necessary to change the coefficients depending on the direction of the disturbance.

Furthermore, if the amount of disturbance is small, hardly any magnetization of the vehicle body will occur, so the coefficient is changed depending on the amount of disturbance, and when the amount of disturbance is small, the coefficient is set to almost 0.

In addition, the origin (center position of the azimuth circle when there is no magnetization at all)
Since the center shifts slightly depending on whether the center value of the azimuth circle is + or - with respect to Os ), accuracy can be improved by changing the coefficient in accordance with the center value of the azimuth circle.

It goes without saying that the technique for detecting the amount of geomagnetic disturbance according to the present invention can be applied not only to error correction of vehicle heading, but also to other control calculations performed in accordance with the amount of disturbance.

〔Effect of the invention〕

As explained above, according to the present invention, the disturbance is large and falls outside the dynamic range of the geomagnetic direction sensor,
Even if it cannot be actually measured, the system is configured to calculate the amount of disturbance by predicting the maximum point and initial point of the disturbance. Accurate disturbance amounts can be obtained even in locations where the amount of disturbance is large.

Therefore, if the present invention is applied to a vehicle compass, it is possible to accurately correct errors in vehicle heading caused by geomagnetic disturbances.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the configuration of the present invention, FIG. 2 is a block diagram showing the configuration of an embodiment of the present invention, FIG. 3 is a schematic configuration diagram of the geomagnetic direction sensor, and FIG. 4 is the block diagram of the geomagnetic direction sensor. Excitation characteristic diagram, Figure 5 is a magnetic flux change characteristic diagram in the permalloy core of the geomagnetic orientation sensor in no magnetic field, Figure 6 is a characteristic diagram showing the detection action of the geomagnetic orientation sensor, and Figure 7 is the detection voltage of the geomagnetic orientation sensor. Figure 8 is a plan view showing the state of installation of the geomagnetic orientation sensor on the vehicle body and the running direction of the vehicle, Figure 9 is a diagram showing the output circle, and Figure 10 is a diagram showing the installation state of the geomagnetic orientation sensor on the vehicle body, and Figure 10 is a diagram showing the installation status of the geomagnetic orientation sensor on the vehicle body. Explanatory diagram when added, 11th
The figure shows the movement of the output circle due to magnetization of the vehicle body, Figure 12 is an example of a flowchart showing calculations in the disturbance amount calculation section, and Figure 13 is a diagram showing the positional relationship of each point in the disturbance amount calculation. , FIG. 14 is an example of a flowchart showing the contents of the magnetization amount calculation in the magnetization amount calculation section, and FIG. 15 is an example of a flowchart showing the calculation contents of coefficient setting in the magnetization amount calculation section, FIG. 16 is a diagram showing the output azimuth circle and the azimuth circle movement due to magnetization. <Explanation of symbols> 100...Geomagnetic direction sensor 110...Magnetic disturbance detection means 120...Disturbance maximum point detection means 130...Measurement range outside detection means 140...Disturbance prediction means 150...Disturbance Direction calculation means 160... Maximum point prediction calculation means 170... Initial point prediction calculation means 180... Disturbance amount calculation means

Claims (1)

[Claims] A geomagnetic azimuth sensor detects geomagnetic components as components in two mutually orthogonal directions on a horizontal plane, and based on the direction from the center coordinate position of the output circle to the coordinate position indicated by the geomagnetic components in the two directions. A vehicle compass is equipped with a means for determining the running direction of the vehicle and, when a geomagnetic disturbance occurs, detecting the amount of disturbance and correcting the error in the vehicle direction caused by it. A geomagnetic azimuth sensor that detects geomagnetic data of orthogonal two-directional components; a means for detecting the occurrence of geomagnetic disturbance from the output of the geomagnetic azimuth sensor; a means for detecting the maximum point of the geomagnetic disturbance; and a means for detecting the direction of the disturbance. means for detecting when the magnitude of the disturbance exceeds the detection range of the output of the geomagnetic azimuth sensor; and means for detecting when the magnitude of the disturbance exceeds the detection range of the geomagnetic azimuth sensor; means for predicting the magnitude of a disturbance outside the detection range from the time when the disturbance is present; means for predicting the maximum point of the disturbance based on the predicted magnitude of the disturbance and the direction of the disturbance; A vehicle comprising: means for predicting the initial point of a disturbance based on a geomagnetic direction sensor output circle before occurrence; and means for calculating an amount of disturbance from the predicted initial point and maximum point. Direction meter.