JP3278950B2 - Direction detection device - Google Patents

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, more specifically, an azimuth sensor attached to a moving body such as a vehicle.
The present invention relates to an azimuth detecting device that detects a traveling direction of a moving object based on an X component signal and a Y component signal output from the azimuth sensor as a pair.

[0002]

2. Description of the Related Art In this type of azimuth detecting device, when there is no distortion in the geomagnetism, the trajectory of the X and Y coordinate points determined by the X and Y component signals of the azimuth sensor is centered on the origin of the X and Y coordinates. Circle (azimuth circle) or ellipse (azimuth ellipse)
Draw. However, when the moving object passes through a strong magnetic field such as a railroad crossing, the moving object is magnetized, and the subsequent output signal of the direction sensor includes a disturbance component corresponding to the direction and magnitude of the magnetization. The center deviates from the origin, and the traveling direction, that is, the azimuth of the moving body cannot be accurately detected.

In view of the above points, conventionally, the center coordinates of the azimuth circle drawn by the X and Y coordinate points determined from the X component signal and the Y component signal of the azimuth circle are obtained, and then the deviation between the center coordinates and the origin is calculated. Are variously taken to correct the X and Y coordinate points.

[0004] As an example, the moving body is turned by one rotation, and X, Y is determined based on the output signal of the direction sensor at this time.
Measures for correcting coordinate points (hereinafter referred to as a first conventional example)
It has been known.

Another example is disclosed in Japanese Patent Application Laid-Open No. 58-34.
As described in Japanese Patent Publication No. 314, while the moving body is in progress,
Any three X, Y coordinate points are selected from the output signal of the azimuth sensor, and the center coordinates are directly obtained from the three X, Y coordinate points by using a predetermined calculation formula, so that the X, Y coordinate points are obtained. (Hereinafter, referred to as a second conventional example) is known.

Further, as another example, Japanese Patent Application Laid-Open No. 3-68
As described in Japanese Patent Publication No. 811, a calculation formula used when the moving body makes a right turn and a calculation formula used when making a left turn are stored separately in advance, and the steering is performed while the moving body is in progress. There has been known a measure (hereinafter, referred to as a third conventional example) for detecting a turning direction by a sensor or the like and correcting the X, Y coordinate points using a calculation formula corresponding to the turning direction.

[0007]

However, the first conventional example has a problem in that a complicated operation of rotating the moving body once and turning to correct the X and Y coordinate points is required. Was.

In the second conventional example, since the calculation formula used for correction is a polynomial, there is a problem that it takes a long calculation time to execute the calculation by a microcomputer normally mounted.

Further, in the third conventional example, since a sensor for detecting the turning direction of the moving body such as a steering sensor is an essential component, the moving body without such a sensor is required. Was not applicable.

The present invention has been made in view of the above problems, and can eliminate a complicated turning operation as in the first conventional example. It is an object of the present invention to provide an azimuth detecting device which does not require a long calculation time and does not require a steering sensor or the like as in the third conventional example.

[0011]

In order to solve the above-mentioned problems, an azimuth detecting device according to the present invention is configured as shown in FIG.
A direction sensor attached to a moving body and outputting a pair of an X-component signal and a Y-component signal according to the traveling direction of the moving body with respect to terrestrial magnetism; A coordinate point selecting means for selecting at least three X, Y coordinate points to be formed, and an arbitrary three of the X, Y coordinate points among the X, Y coordinate points selected by the coordinate point selecting means, A quadrant discriminating means for discriminating which of the four quadrants in the azimuth circle an intermediate coordinate point located in the middle belongs to; and a positional relationship between the three arbitrary X and Y coordinate points (for a moving object). And a plurality of correction formulas for correcting the center coordinates of the azimuth circle in advance.
In each correction formula, the radius of the azimuth circle is set as one of the parameters, for each quadrant to which the intermediate coordinate point belongs, and in accordance with the positional relationship between the three arbitrary X and Y coordinate points. The correction calculation formula storage means is stored in the correction calculation formula storage means based on the correction calculation formula storage means stored in each case and the quadrant determined by the quadrant determination means and the positional relationship determined by the positional relationship determination means. A corresponding correction formula is selected from the plurality of correction formulas, and a center coordinate setting means for obtaining the center coordinates of the azimuth circle based on the selected correction calculation formula; and the azimuth circle obtained by the center coordinate setting means. By the center coordinates, X of the direction sensor
Azimuth coordinate correcting means for correcting X, Y coordinate points determined from the component signal and the Y component signal.

[0012]

The present invention does not adopt a method of correcting the X and Y coordinate points by rotating the moving body one turn and rotating as in the first conventional example, but adopting a method in which the moving body is moved while the moving body is in progress. , Y coordinate points are corrected. Therefore, a complicated turning operation is not required.

Further, in the present invention, a plurality of correction formulas are stored in advance in the correction formula storage means in a case-by-case manner, and an intermediate coordinate point among arbitrary three X and Y coordinate points is stored. The center coordinates of the azimuth circle are obtained by using a corresponding correction formula in accordance with the quadrant to which belongs and the positional relationship among the arbitrary three X, Y coordinate points. For this reason,
The correction formula can be simplified, and the calculation time can be shorter than in the second conventional example.

In the present invention, the positional relationship determining means determines the positional relationship between any three X, Y coordinate points, and the positional relationship includes the turning direction of the moving body. I have. Therefore, it is not necessary to provide a steering sensor or the like for detecting the turning direction of the moving body as in the third conventional example.

[0015]

An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 shows the overall configuration of the azimuth detecting device according to the present embodiment.

In FIG. 1, reference numeral 1 denotes a known azimuth sensor which is attached to a moving body, for example, a vehicle, and outputs an X component signal X and a Y component signal Y corresponding to the traveling direction of the moving body with respect to the earth magnetism. . The output terminal of the direction sensor 1 is
It is connected to an arithmetic processing circuit 2 including a microcomputer. The arithmetic processing circuit 2 receives the X component signal X and the Y component signal Y of the azimuth sensor 1 and executes a predetermined arithmetic processing, and sends the azimuth display signal Z to a known display 3, as described later in detail. Is what you do. Note that the other reference numeral 4 in FIG. 1 represents an ignition switch.

FIG. 2 is a flowchart showing main arithmetic processing executed by the microcomputer of the arithmetic processing circuit 2. Hereinafter, the arithmetic processing shown in FIG. 2 will be roughly described in order. This calculation process is started when the ignition switch 4 is turned on.

(1) Three X, Y coordinate points T ₁ , T ₂ , T
Selection of ₃ (Steps 101 to 110) When the ignition switch is turned on (Step 10)
1) At this time, each instantaneous value of the X component signal X and the Y component signal Y of the direction sensor is stored in the register T as a point T (x, y) (step 102).

Next, the start point T₁ (X₁ , Y₁ )
Start point register T₁ Judge whether it is memorized in
(Step 103). Ignition switch off
Immediately after the start point register T₁ To
Start point T₁ (X₁ , Y₁) Was not remembered
Therefore, the point T (x, y) is changed to the start point T₁ (X₁ , Y
₁ ) As start point register T₁ (Step
104).

Thereafter, the instantaneous values of the X component signal X and the Y component signal Y of the azimuth sensor are successively stored in the register T as points T (x, y) while being rewritten, and each time the point T and the start point T distance T ₁ T and ₁ slide into determining whether a predetermined value △ T or more (step 102,103,1
05, 106). When the distance T ₁ T is equal to or greater than the predetermined value ΔT, the point T (x, y) at this time is changed to the intermediate point T ₂ (x
₂ , y ₂ ) is stored in the intermediate point register T ₂ (step 107). Note that the predetermined value ΔT is set to an appropriate value that satisfies the relational expression of ΔT ₁ O′T ₂ ≦ 90 ° in FIG. Here, O ′ represents the center of the azimuth circle C.

Thereafter, it is determined whether the distance T ₂ T between the point T and the intermediate point T ₂ is equal to or greater than a predetermined value ΔT equal to the predetermined value ΔT (steps 102, 103, 103).
105, 108), when the distance T ₂ T is equal to or greater than a predetermined value ΔT, the distance T ₁ T between the point T and the start point T ₁ at this time is equal to or greater than the predetermined value ΔT. Intermediate point T
_After confirming that the point is located on the opposite side to the start point T ₁ with reference to ₂ (step 109),
(X, y) is stored in the end point register T ₃ as the end point T ₃ (x ₃ , y ₃ ) (step 110). The predetermined value ΔT is represented by ΔT ₂ O′T ₃ in FIG.
It is set to an appropriate value that satisfies the relational expression of ≦ 90 °.

As described above, in steps 101 to 110, the start point T ₁ is selected and the start point T ₁ is selected.
₁ from selected intermediate points T ₂ a predetermined distance △ T,
Moreover, apart from this intermediate point T ₂ distance equal △ T and the predetermined distance △ T, the starting point T ₁ executes processing to designate the end point T ₃ on the opposite side.

(2) Setting of azimuth radius R (step 111) The start point T ₁ and the intermediate point T selected as described above
₂ and the end point T _3, determine the radius R of the azimuth circle C has three points located (step 111). Hereinafter, a method of obtaining the radius R will be described with reference to FIG.

First, as shown in FIG. 3, the start point T ₁
And the end point T ₃ by a straight line l ₁ , and this line segment T ₁ T ₃
The middle point T ₄ (x ₄ , y ₄ ) is set. Then, when a straight line l ₂ passing from the intermediate point T ₂ to the middle point T ₄ is drawn, the center O ′ (x ₀ , y ₀ ) of the azimuth circle C should be located on the straight line l ₂ . Next, on this straight line l ₂ , a point T ₅ (x ₅ , at which the distance from the midpoint T ₄ becomes equal to the distance of the straight line T ₂ T ₄
Setting the y _5).

When the middle point T ₄ and the point T ₅ are set as described above, the triangle T ₁ T ₂ T ₅ and the triangle O′T ₁ T ₂ have a similar relationship. Therefore, the following equation is established.

T ₂ T ₅ : T ₁ T ₂ = T ₁ T ₂ : O′T ₁ (where T ₂ T ₅ , T ₁ T ₂ , and O′T ₁ represent the distance between the points) Here, T ₂ T ₅ = √ ｛(x ₁ -2x ₂ + x ₃ ) ² + (y ₁ -2
y ₂ + y ₃ ) ² ｝ T ₁ T ₂ = √ ｛(x ₁ -x ₂ ) ² + (y ₁ -y ₂ ) ² ｝ O′T ₁ = R Therefore, R = {(x ₁ −x ₂ ) ² + (y ₁ −y ₂ ) ² } / √
_{{(X 1 -2x 2 + x} 3) 2 + (y 1 -2y 2 + y 3)
² ｝, and the radius R can be obtained.

The radius R obtained in this manner can be said to be a corrected azimuth radius including the amount of change in the intensity of geomagnetism depending on the latitude of the earth. In this embodiment, the above-described radius correction is performed for the following reason. That is, in the present embodiment, as described later, the center O ′ of the azimuth circle C is obtained using the radius R. Here, the radius R has a proportional relationship with the strength of the geomagnetism. Therefore, when the mobile body is used only in Japan, the radius R is substantially constant because the intensity of the geomagnetism is substantially constant. Therefore, the radius R may be always set to a constant value. This is because when the body is used outside of Japan, the radius R varies depending on the region where the body is used, since the strength of the geomagnetism greatly differs depending on the region where the body is used.

As described above, in step 111, the start point T ₁ , the intermediate point T ₂ , and the end point T
The radius R of the azimuth circle C is obtained from ₃ .

For this reason, according to the present embodiment, the third conventional example shown at the beginning of the specification discloses that the radius R is stored in advance in the map memory in correspondence with the latitude. Thus, a large-capacity memory for such a radius R is not required at all.

(3) Quadrant Determination (Step 112) Next, it is determined to which quadrant of the azimuth circle C the intermediate point T ₂ belongs as shown in FIG. 4 (Step 112).

This quadrant discriminating method, as shown in FIG.
The intermediate point T _2, the slope of the line connecting the middle point T ₄ obtained in the above step 111, it is possible to midpoint T ₂ is easily determined belongs to one of the quadrants. That is, the quadrant midpoint T ₂ belongs is determined by the conditions A and B as shown in Table 1 below.

[0033]

[Table 1]

(4) Determination of Positional Relationship (Step 113) Next, the positional relationship between the above three points T ₁ , T ₂ and T ₃ is determined (Step 113). This positional relationship is shown in the following C,
The determination is made by discriminating the sign of each of the conditions D, E, and F.

C = x ₂ −x ₁ D = y ₂ −y ₁ E = x ₂ −x ₃ F = y ₂ −y _{3 The} reason why the above conditions of C, D, E and F will be described.

For example, regarding the positional relationship between the start point T ₁ and the intermediate point T ₂ , as shown in FIGS. 6A and 6B, even if the intermediate point T ₂ belongs to the first quadrant. even, the midpoint T ₂ is located in the clockwise direction relative to the starting point T ₁ (FIG. 6 (a) shows a case of clockwise direction.) the one or positioned in counterclockwise direction (FIG. 6
(b) shows the case of the counterclockwise direction. ) And whether the slope of the straight line T ₁ T ₂ is positive (corresponding to the case indicated by the solid line in FIG. 6) or negative (corresponding to the case indicated by the dashed line in FIG. 6). Is different. This difference in the positional relationship leads to the necessity of a plurality of correction formulas as described later.

The same applies to the positional relationship between the intermediate point T ₂ and the end point T ₃ , as shown in FIGS. 7A and 7B, even if the intermediate point T ₂ belongs to the first quadrant. even if there are, end point T ₃ intermediate points T ₂ as a reference (corresponding to FIG. 7 (a).) located in a clockwise direction of either, or located counterclockwise direction (FIG. 7 (b ) And the inclination of the straight line T ₂ T ₃ is positive (a solid line corresponds in FIG. 7) or negative (a dash-dot line corresponds in FIG. 7). This is because they are different. Then, this difference in the positional relationship similarly leads to the necessity of a plurality of correction formulas as described later.

(5) Setting of Center Coordinates (Step 114) Next, a plurality of correction formulas for correcting the center O ′ (x ₀ , y ₀ ) of the azimuth circle C (formulas in Table 3 to be described later) 1), (2), from the memory which stores (3), (4)), discriminated midpoint T ₂ of the belonging quadrant in step 112, and the determined position relationship in step 113 Based on the positive / negative of the conditions C, D, E, and F shown, two necessary correction formulas are read. Here, one of the two correction formulas is a start point T ₁ (x ₁ , y ₁ ).
And the intermediate point T ₂ (x ₂ , y ₂ )
The center O ′ ₁ (x) of the azimuth circle C ₁ (FIG. 6) formed by the start point T ₁ and the intermediate point T ₂ based on the radius R obtained in
₀₁ , y ₀₁ ) (FIG. 6).
_The other one is the intermediate point T ₂ (x
₂ , y ₂ ), the end point T ₃ (x ₃ , y ₃ ), and the radius R obtained in step 111, the intermediate point T ₂
Calculation formula (correction calculation formula for O ' ₂ ) for calculating the center O ′ ₂ (x ₀₂ , y ₀₂ ) (FIG. 7) of the azimuth circle C ₂ (FIG. 7) formed by the end point T ₃ and the end point T ₃ . It is.

Then, the read O '₁ Correction formula
X_a , Y_a X₁ , Y₁ And x_b , Y_b To
x_Two , Y_Two And substitute (x_p , Y_p ), And this (x
_p , Y_p ) To the compass circle C₁ Center O '₁ (X₀₁, Y₀₁)When
To determine. Also, O '_Two X in the correction formula for_a ,
y_a X_Two , Y_Two And x_b , Y_b X_Three , Y_ThreeTo
Substitute (x_p , Y_p ), And this (x_p , Y_p )
Azimuth circle C_Two Center O ' _Two (X₀₂, Y₀₂).
And the center O '₁ , Center O '_Two The midpoint between ((x₀₁+ X
₀₂) / 2, (y₀₁+ Y₀₂) / 2) and find the midpoint
The target is the center O '(x₀ , Y₀ )
You.

Here, a plurality of correction formulas and an intermediate point T ₂
Table 2 below shows the relationship between the belonging quadrants and the conditions C, D, E, and F.

[0041]

[Table 2]

Here, the above correction formulas (1), (2),
(3) and (4) are as shown in the following equation 1.

[0043]

(Equation 1)

(However, Z = R ² / ｛(x _a −x _b ) ² +
(Y _a −y _b ) ² ｝ − ／) Here, a method of calculating the above-mentioned correction formula will be described below with reference to FIG.

In FIG. 8, a point A (x _a , y _a ) and a point B (x _b , y _b ) are located on the circumference of the circle C ₃ . Also,
The point _{O '(x p, y p} ) is the center of the circle C _3. A point _{A '((x a + x} b) / 2, (y a + y b) / 2) is the midpoint between points A and B. Point C is the intersection of an extension from point A in the X-axis direction and an extension from point B in the Y-axis direction. Further, the point C ′ is located at X from the center O ′.
This is the intersection of the extension line in the axial direction and the extension line in the Y-axis direction from point A ′. In addition, R is the radius of the circle C _3.

Under such conditions, the triangle ABC and the triangle A'O'C 'have a similar relationship, and the following equation is established.

A'O ': AB = A'C': AC A'O ': AB = C'O': BC (However, A'O ', AB, A'C', AC, C'O ' ,
BC represents the distance between each point. Therefore, A'C 'and C'O' are respectively obtained by the following equations.

A′C ′ = | x _a −x _b | × {[R ² / ｛(x _a −x
^{_{b) 2 + (y a -y}} b) 2} -1/4] C'O '= | y a -y b | × √ [R 2 / {(x a -x
^{_{b) 2 + (y a -y}} b) 2} -1/4] Further, the point _{O '(x p, y p} ) is the point _A' ((x _a + x
_{b) / 2, (y a} + y b) / 2) from each A '
C ', C'O' can be obtained by the the point A 'or decreasing depending on the quadrant belonging, x _p, y _p is represented by the following formula.

[0049] _{x p = (x a + x} b) / 2 ± | y a -y b | × √ [R 2
_{/ {(X a -x b)} 2 + (y a -y b) 2} -1/4] y p = (y a + y b) / 2 ± | x a -x b | × √ [R 2
_{/ {(X a -x b)} 2 + (y a -y b) 2} -1/4] ^{where, Z = R 2 / {(} x a -x b) 2 + (y a -y
_b ) By placing ² ｝ − ／), the above-described correction formulas (1), (2), (3) and (4) can be obtained.

As described above, the execution of step 114
The line determines the midpoint T_Two And the three points T₁ ,
T_Two , T_Three And stored in the correction formula memory
Four correction formulas (1), (2), (3),
A corresponding correction formula is selected from (4), and the selected correction formula is selected.
The center O '(x₀ , Y
₀ ) Is obtained.

(6) Correction of azimuth coordinate (step 115) Next, the center O 'of the azimuth circle C obtained in step 114
(X ₀ , y ₀ ) corrects (x, y) determined from the X component signal and the Y component signal of the direction sensor.

More specifically, an azimuth display signal is obtained by subtracting x ₀ from x and y ₀ from y.

(7) Direction Display Signal Output (Step 116) Next, the above-mentioned direction display signal is output to the display 3, and the current traveling direction of the moving object is displayed on the screen. And
The series of processes described above ends.

As described above, according to the present embodiment,
Since the correction of the center coordinates of the azimuth circle is automatically performed while the moving body is in progress, a complicated operation of rotating and rotating the moving body one time as in the first conventional example can be omitted. become.

Further, the correction calculation formula memory previously stores four correction calculation formulas for each of the quadrants to which the intermediate point belongs, and these correction calculation formulas are the same as those of the second conventional example. Since the equation is simpler than the equation, the calculation time for correction is shorter than in the second conventional example.

Further, since the sensor for detecting the turning direction of the moving body as in the third conventional example is not provided, it is simply attached to the moving body on which such a sensor is not mounted. Will be able to do it.

Further, since the radius R used for the correction calculation is corrected, it is not necessary to provide a large-capacity memory for the radius R as in the third conventional example.

In the above embodiment, T ₁ T ₂ = T ₂ T
_Three points T ₁ , T ₂ , T ₃ that satisfy ₃ were selected,
The three points satisfying ∠T ₁ O'T ₃ ≦ 180 ° are not limited to the above three points. In addition, four or more points are selected, and for all combinations of three points,
The same processing as in the above embodiment may be executed, and the center of the azimuth circle may be corrected from the average value. In the above embodiment, at the same time as the ignition switch is turned on 4 has been set the start point T _1, may be to set the starting point T ₁ by other suitable triggering means. Further, in the above embodiment, are set three points T _1, T _2, T ₃ only one each, a plurality set for each point, if to take the average value, the influence of the disturbance Is reduced. Also, in the above embodiment, the three points are set by taking in the signal of the direction sensor 1 indefinitely. However, considering that the signal may include a disturbance component, the reliability of the signal may be reduced. Three points may be set after a high time is determined by appropriate means.

[Brief description of the drawings]

FIG. 1 is a block diagram of an azimuth detecting device according to an embodiment.

FIG. 2 is a flowchart for explaining arithmetic processing of the apparatus.

FIG. 3 is an explanatory diagram of a method of calculating a radius R of an azimuth circle.

FIG. 4 is an explanatory diagram of a quadrant of an azimuth circle.

FIG. 5 is an explanatory diagram of a method of calculating a quadrant to which an intermediate point T ₂ belongs.

Figure 6 is an explanatory diagram of the need for different correction formulas the positional relationship between the starting point T ₁ and the intermediate point T ₂

Figure 7 is an explanatory view of the need for different correction formulas the positional relationship between the intermediate point T ₂ and the end point T ₃

FIG. 8 is an explanatory diagram of a method of calculating a correction calculation expression.

FIG. 9 is a diagram corresponding to claims of the present invention.

[Explanation of symbols]

 Reference Signs List 1 orientation sensor 2 arithmetic processing circuit 3 display 4 ignition switch

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁷ , DB name) G01C 17/38 G01C 17/30

Claims (2)

(57) [Claims] An azimuth sensor attached to a moving body and outputting a pair of an X component signal and a Y component signal according to a traveling direction of the moving body with respect to the earth magnetism, and an X component signal and a Y component signal of the azimuth sensor. type in,
Coordinate point selecting means for selecting at least three X, Y coordinate points to form an azimuth circle; and arbitrary three X, Y coordinate points among the X, Y coordinate points selected by the coordinate point selecting means. A quadrant discriminating means for discriminating which of the four quadrants in the azimuth circle an intermediate coordinate point located in the middle belongs to; a positional relationship (movement) between the three arbitrary X and Y coordinate points; And a plurality of correction formulas for correcting the center coordinates of the azimuth circle in advance, wherein the radius of the azimuth circle is a parameter in each correction calculation formula. Is stored in each of the quadrants to which the intermediate coordinate point belongs and according to the positional relationship between the three arbitrary X and Y coordinate points. Storage means, and the quadrant discriminating means Based on the determined quadrant and the positional relationship determined by the positional relationship determining means, a corresponding correction formula is selected from a plurality of correction formulas stored in the correction formula storage means, and the selected correction formula is selected. A center coordinate setting means for obtaining center coordinates of the azimuth circle by an equation; and X, Y determined from an X component signal and a Y component signal of the azimuth sensor by the center coordinates of the azimuth circle obtained by the center coordinate setting means. An azimuth detecting device comprising: azimuth coordinate correcting means for correcting a coordinate point. 2. The apparatus according to claim 1, further comprising: a radius setting unit that obtains a radius of the azimuth circle from any three of the X and Y coordinate points selected by the coordinate point selecting unit. The azimuth detecting device, wherein the center coordinate setting means is configured to obtain the center coordinates of the azimuth circle using the radius calculated by the radius setting means in the correction calculation formula.