JPH06167348A - Navigation system for vehicle - Google Patents

Abstract

PURPOSE:To detect the position of a driving vehicle accurately by correcting an azimuth axis basing on the integral value of a gyro output value and at the same time reading the map information of the current position which is estimated from the output values of an earth magnetism sensor, a vehicle speed sensor, and a gyro from a storage part and then displaying it. CONSTITUTION:A control means 40 obtains the center and the radius of a circular turning from the output value of an earth magnetism sensor 20 when a vehicle turns by one revolution, integrates the output value of a gyro 30 in reference to the time when the vehicle is directed toward the magnetic north, and then obtains the azimuth axes of east/west/north/south according to the output value of the sensor 20 and the center of the circular turning. When an arbitrary output value of the sensor 20 is input during driving, the control means 40 performs correction basing on each azimuth axis and the angle of the azimuth axes and then obtains an accurate azimuth. Further, a current position is estimated from the obtained azimuth and the output value of the vehicle sensor and the gyro 30 and then the map information of the position is read from a map information storage part 60 and then is displayed by a display means 50.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicle navigation system, and more particularly to a vehicle navigation system suitable for accurately detecting the position of a traveling vehicle.

[0002]

2. Description of the Related Art In recent years, a navigation system using a gyro as an estimated navigation sensor has been mounted on a vehicle.

A conventional vehicle navigation system is
Display information including a switch input mechanism, a map information storage unit that stores road map information, a geomagnetic sensor, a gyro, and map information of the current position estimated based on the data from the geomagnetic sensor and the gyro. It is composed of a control unit that reads out from the storage unit and displays it on the display unit.

Since the output of the gyro is generally dependent on the mounting angle of the vehicle with respect to the vertical axis, the output of the gyro varies even when the vehicle turns at the same angular velocity.

Further, when the gyro and the signal processing circuit are separate from each other, there are variations in the gyro and the signal processing circuit, so that an error occurs in the measurement result.

Therefore, various corrections are made to correct these errors.

Further, when using the geomagnetic sensor, the initialization work mainly for the purpose of correcting the mounting angle and correcting the magnetization of the vehicle body is carried out in the following manner, for example, at the time of mounting on the vehicle and subsequent adjustment.

[0008] As shown in FIG. 5, the geomagnetic sensor output x (t), y for about one rotation while turning the vehicle in a circle.
(T) is taken in, and the center (x ₀ , y ₀ ) of the azimuth circle and the radius r of the geomagnetic sensor output are obtained based on this.

[0009]. Next, the vehicle is directed to the magnetic north, and the output value (x _N , y _N ) of the geomagnetic sensor and the center (x ₀ , y ₀ ) of the bearing circle are used to determine the north bearing axis in the bearing circle as shown in FIG. .

[0010]. Regarding the east, west, and south azimuth axes, the azimuth axis is determined by actually directing the vehicle to that azimuth in the same manner as the north azimuth, or each azimuth axis is determined at 90 ° intervals from the north azimuth on the azimuth circle.

[0011]

As shown in FIG. 7, since the magnetic force lines are distorted by the iron structure or the like, the magnetic force lines are similarly affected inside the iron body. The degree of distortion of the lines of magnetic force differs depending on the orientation of the vehicle body with respect to the lines of magnetic force.

In the above-mentioned conventional example, the azimuth axis is displaced as shown in FIG. 8 due to the non-uniform distortion of the lines of magnetic force, and there is an inconvenience that an error occurs in the detection position because it does not coincide with the actual azimuth.

[0013]

SUMMARY OF THE INVENTION The object of the present invention is to improve the inconvenience of the conventional example, and in particular, to automatically correct the deviation of the azimuth axis due to the non-uniform distortion of the lines of magnetic force to accurately detect the position of the traveling vehicle. It is to provide a vehicle navigation system that can perform.

[0014]

Therefore, in the present invention, a display means including a switch input mechanism, a map information storage section for storing road map information, a geomagnetic sensor for detecting geomagnetism, and a vehicle speed are detected. The vehicle speed sensor, the gyro that detects the turning angular velocity, and the azimuth axis correction based on the integrated value of the gyro output value, and the map information of the current position estimated from the geomagnetic sensor, the vehicle speed sensor, and the output value of the gyro is stored as map information. And a control means for reading out from the unit and displaying it on the display means. This aims to achieve the above-mentioned object.

[0015]

The control means obtains the center and radius of the circular turning from the output value of the geomagnetic sensor when the vehicle makes one revolution.

Next, the gyro output value is integrated with reference to the time when the operator turns the vehicle to magnetic north. Then, the azimuth axis of north, south, east, and west is obtained from the output value of the geomagnetic sensor at the time when the integrated value becomes a multiple of 90 degrees and the center of the circular turning.

When an arbitrary geomagnetic sensor output value is input during traveling, the control means performs correction based on each azimuth axis and the angle between each azimuth axis to obtain an accurate azimuth.

Further, the control means estimates the current position from the obtained azimuth and the output values of the vehicle speed sensor and the gyro, reads the map information of the current position from the map information storage section and displays it on the display means.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS.

In the embodiment shown in FIG. 1, a display means 50 including a switch input mechanism, a map information storage section 60 for storing road map information, a geomagnetic sensor 20 for detecting geomagnetism,
A vehicle speed sensor 10 for detecting a vehicle speed and a gyro 30 for detecting a turning angular velocity are provided. Further, the azimuth axis is corrected based on the integrated value of the output value of the gyro 30, and the map information of the current position estimated from the output values of the geomagnetic sensor 20, the vehicle speed sensor 10 and the gyro 30 is read from the map information storage unit 60. Control means 4 displayed on the display means 50
0 is equipped.

Next, the operation of this embodiment will be described.

Here, as initial conditions, various flags, various parameters, and contents of various arrays are all cleared to 0.

The operator controls the start of turning of the vehicle by the control means 40.
The following processing is started when the notification is sent to.

(1). The control means 40 is the geomagnetic sensor 2
The output signals x (t) and y (t) of 0 and the output signal g (t) of the gyro 30 are input, and sampling processing is performed and stored in the internal memory.

(2). The control means 40 checks the turning start flag, and if the value is not "1", the gyro 3
Check the output change G _{d of} 0.

(3). As a result of checking the output change G _d of the gyro 30 in the processing of (2) above, if the control means 40 exceeds the preset value G _s , the vehicle has not yet turned. And judge
The process returns to the above (1) without doing anything.

On the other hand, when the change G _{d of the} gyro output is equal to or less than the preset value G _s , the turning start flag is set to "1" and the process returns to the above (1).

(4). On the other hand, in the process of (2) above, if the turning start flag is "1", the number of data NUM is checked.

(5). The control means 40 determines the number of data NUM
If the number of data NUM is 0 as a result of checking, the value of the output signal x (t) of the geomagnetic sensor 20 is set to the initial value S of x.
Maximum value of T_X and x MAX_X and minimum value of x MIN_X
Let the output signal y (t) be the initial value ST_Y of y, the maximum value MAX_Y of y, and the minimum value MIN_Y of y.

On the other hand, if the data number NUM is not 0, the control means 40 outputs the output signal x (t) of the geomagnetic sensor 20,
The value of y (t) is compared with their maximum and minimum values.

That is, the output signal x of the geomagnetic sensor 20
When the value of (t) is larger than the maximum value MAX_X of x, the value of the output signal x (t) is newly set to the maximum value MAX of x.
_X. When the value of the output signal x (t) of the geomagnetic sensor 20 is smaller than the minimum value MIN_X of x, the value of the output signal x (t) is set to the new minimum value MIN_X of x.

Similarly, the output signal y of the geomagnetic sensor 20
When the value of (t) is larger than the maximum value MAX_Y of y, the value of the output signal y (t) is newly set to the maximum value MAX of y.
_Y. When the value of the output signal y (t) of the geomagnetic sensor 20 is smaller than the minimum value MIN_Y of y, the value of the output signal y (t) is set to the new minimum value MIN_Y of y.

(6). Further, the control means 40 adds the value of the output signal g (t) of the gyro 30 to the gyro integral value SG, and the difference DX between the output signal x (t) of the geomagnetic sensor 20 and the initial value ST_X of X and its absolute value. ABS_D
Find X and.

(7). The control means 40 checks whether the turning monitoring flag is even.

If the turning monitoring flag is not an even number, it is checked whether the absolute value ABS_DX is less than or equal to a preset value D2.

On the other hand, if the turning monitoring flag is an even number, it is checked whether or not the absolute value ABS_DX is greater than or equal to a preset value D1.

(8). In the process (7), when the turning monitoring flag is even and the absolute value ABS_DX is D1 or more, or when the turning monitoring flag is odd and the absolute value ABS_D is
When X is D2 or less, "1" is set to the state array S [N] if the value of DX is positive, and "-1" is set to the state array S [N] if the value of DX is negative. Set. Then, the turning monitoring flag and the state array element number N are incremented by one.

On the other hand, when the turning monitoring flag is even, the absolute value AB
If S_DX is D1 or less, or if the turning monitoring flag is an odd number and absolute value ABS_DX is D2 or more, nothing is done and the process proceeds to the following.

(9). The control means 40 checks whether the turning monitoring flag is 3 or more.

(10). In the process (9), if the turning monitoring flag is 3 or more, it is further checked whether the turning monitoring flag is 5 or more.

(11). In the above process (10), if the turning monitoring flag is 5 or more, or if the turning monitoring flag is 5 or less and S [N], S [N-1], and S [N-2] are the same, the vehicle is It is determined that the vehicle has made one or more turns, and the turning end flag is set to "1", and the output value x (t) of the geomagnetic sensor 20 at that time is the final value EN_X and the output value y (t) of the geomagnetic sensor 20 is the final value. EN_Y.

Further, the end of turning is displayed on the display means 50.

On the other hand, in the processing (9), when the turning monitoring flag is 3 or less, and in the processing (10), when the turning monitoring flag is 5 or less, S [N] and S [N-1].
And S [N-2] are not the same, the process proceeds to the following process without doing anything.

(12). The control means 40 determines the number of data NU
Increment M by 1.

(13). The control means 40 checks whether the turning end flag is "1".

(14) In the process (13), if the turning end flag is not "1", the process returns to the process (1).

On the other hand, if the turning end flag is "1",
MAX_X, MAX_Y, MIN_ of the geomagnetic sensor 20
From X and MIN_Y, the center (x ₀ , y ₀ ) of the azimuth circle and the radius r are calculated.

(15). Next, the operator turns the vehicle to magnetic north. The control means 40 obtains the north azimuth PN as shown in FIG. 2 from the output values (x _N , y _N ) of the geomagnetic sensor 20 at this time and the azimuth center (x ₀ , y ₀ ), and at the same time, FIG. As shown in, the time t (= t _N ) when it coincides with the north direction P _N is calculated from the geomagnetic sensor output value g (t) stored in the internal memory.

(16). As shown in FIG. 3, when the measurement time range of the geomagnetic sensor output value g (t) stored in the internal memory of the control means 40 is t0 to t5,
The gyro output is integrated in the direction in which the amount of data is large when viewed from t _N. Here, integration is performed in the direction of t ₀ .

(17). The control unit 40 calculates t at each time when the vehicle turning angle that can be calculated from the gyro integral value Gn becomes 90 degrees.
Is obtained, and they are sequentially set as t _W , t _S , and t _E.

That is, assuming that the gyro integral value in the direction from tN to t0 is G1, the time when the following equation is satisfied is tW.
And

[0052]

[Equation 1]

KG ₁ = 90 (degrees)

Here, null is a reference voltage of the gyro output, and k is an angle conversion coefficient for converting the voltage value into an angle.

When t _W is determined, t _S is calculated next. That is, when the gyro integral value from t _W to t ₀ is G2, the time when the following expression is satisfied is t S.

[0056]

[Equation 2]

KG ₂ = 90 (degrees)

Once t _S has been determined, t _E is then determined. That is, when the gyro integral value in the direction from t _S to t ₀ is G ₃ , the time when the following equation is satisfied is t _E.

[0059]

[Equation 3]

KG3 = 90 (degrees)

(18). The control means 40 controls t _W , t _S and t
If there is no data in the direction where integration was first started, that is, in the direction t ₀ before the three _Es are determined, the process returns to tN, and the gyro output is integrated in the opposite direction, that is, direction t _5. To go.

(19). The control means 40 uses the above (17).
In the same manner as described above, t is calculated each time the vehicle turning angle that can be calculated from the gyro integral value Gn becomes 90 degrees.

(20). The control means 40 controls t _N , t _W , and t.
_The integration work is terminated when four of _S and t _E are obtained.
At this time, t _N , t _W , t _S , and t _E are when the vehicle turns to the north, west, south, and east, respectively, if the turn is a right turn, and as shown in FIG. Geomagnetic sensor data (x (t _N ), y (t _N )), (x (t _W ), y
(T _W )), (x (t _S ), y (t _S )), (x (t _E ),
y (t _E )) and the azimuth circle center (x ₀ , y ₀ ), the north, west, south, and east azimuth axes (P
_N , P _W , P _S , P _E ) and azimuth axis spacing (θ _NE , θ _ES , θ
_SW , θ _WN ) is calculated.

(21). The control means 40 calculates the azimuth P _i calculated from an arbitrary geomagnetic sensor output (x _i , y _i ) by the azimuth axis intervals θ _NE , θ _ES , θ _SW , and θ W-N obtained here.
To correct. If the angle is calculated counterclockwise with respect to the north azimuth, the corrected azimuth P _i ′ is obtained by one of the following expressions (1) to (4).

When P _N ≤P _i ≤P _W

P _i '= P _i · (90 / θ _WN )

When P _W <P _i ≤P _S

P _i '= P _W + (P _i −P _W ) · (90 / θ _SW ) ...

When P _S <P _i ≤P _E

P _i '= P _S + (P _i −P _S ) · (90 / θ _ES ) ...

When P _E <P _i <P _N

P _i '= P _E + (P _i −P _E ) · (90 / θ _NE ) ...

As described above, according to the present invention, when the geomagnetic sensor is initialized, the gyro output is simultaneously captured together with the geomagnetic sensor output, and the geomagnetic sensor output is obtained by using the turning angle of the vehicle obtained by the integrated value of the gyro output. The azimuth axis in the azimuth circle of is corrected.

[0074]

Since the present invention is constructed and functions as described above, according to this, it is possible to automatically correct the deviation of the azimuth axis due to the distortion of the lines of magnetic force, which enables accurate position detection. Therefore, it is possible to provide an unprecedented excellent vehicle navigation system that can improve the reliability of the vehicle navigation system.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing an embodiment of the present invention.

FIG. 2 is an explanatory diagram for explaining a method of calculating an azimuth axis in the embodiment of FIG.

FIG. 3 is a timing chart for explaining the operation of the embodiment of FIG.

FIG. 4 is an explanatory diagram for explaining a method of calculating an azimuth axis in the embodiment of FIG.

FIG. 5 is an explanatory diagram for explaining the output of the geomagnetic sensor during a circular turn.

FIG. 6 is an explanatory diagram for explaining a relationship between an azimuth circle and an azimuth axis.

FIG. 7 is an explanatory diagram for explaining distortion of magnetic force lines.

FIG. 8 is an explanatory diagram for explaining a change in an azimuth axis due to distortion of magnetic force lines.

[Explanation of symbols]

 10 vehicle speed sensor 20 geomagnetic sensor 30 gyro 40 control means 50 display means 60 map information storage unit

─────────────────────────────────────────────────── ───

[Procedure amendment]

[Submission date] November 19, 1993

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be amended] Detailed explanation of the invention

[Correction method] Change

[Correction content]

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicle navigation system, and more particularly to a vehicle navigation system suitable for accurately detecting the position of a traveling vehicle.

[0002]

2. Description of the Related Art In recent years, a navigation system using a gyro as an estimated navigation sensor has been mounted on a vehicle.

A conventional vehicle navigation system is
Display information including a switch input mechanism, a map information storage unit that stores road map information, a geomagnetic sensor, a gyro, and map information of the current position estimated based on the data from the geomagnetic sensor and the gyro. It is composed of a control unit that reads out from the storage unit and displays it on the display unit.

Since the output of the gyro is generally dependent on the mounting angle of the vehicle with respect to the vertical axis, the output of the gyro varies even when the vehicle turns at the same angular velocity.

Further, when the gyro and the signal processing circuit are separate from each other, there are variations in the gyro and the signal processing circuit, so that an error occurs in the measurement result.

Therefore, various corrections are made to correct these errors.

Further, when using the geomagnetic sensor, the initialization work mainly for the purpose of correcting the mounting angle and correcting the magnetization of the vehicle body is carried out in the following manner, for example, at the time of mounting on the vehicle and subsequent adjustment.

[0008] As shown in FIG. 5, the geomagnetic sensor output x (t), y for about one rotation while turning the vehicle in a circle.
(T) is taken in, and the center (x ₀ , y ₀ ) of the azimuth circle and the radius r of the geomagnetic sensor output are obtained based on this.

[0009]. Next, the vehicle is directed to the magnetic north, and the output value (x _N , y _N ) of the geomagnetic sensor and the center (x ₀ , y ₀ ) of the bearing circle are used to determine the north bearing axis in the bearing circle as shown in FIG. .

[0010]. Regarding the east, west, and south azimuth axes, the azimuth axis is determined by actually directing the vehicle to that azimuth in the same manner as the north azimuth, or each azimuth axis is determined at 90 ° intervals from the north azimuth on the azimuth circle.

[0011]

As shown in FIG. 7, since the magnetic force lines are distorted by the iron structure or the like, the magnetic force lines are similarly affected inside the iron body. The degree of distortion of the lines of magnetic force differs depending on the orientation of the vehicle body with respect to the lines of magnetic force.

In the above-mentioned conventional example, the azimuth axis is displaced as shown in FIG. 8 due to the non-uniform distortion of the lines of magnetic force, and there is an inconvenience that an error occurs in the detection position because it does not coincide with the actual azimuth.

[0013]

SUMMARY OF THE INVENTION The object of the present invention is to improve the inconvenience of the conventional example, and in particular, to automatically correct the deviation of the azimuth axis due to the non-uniform distortion of the lines of magnetic force to accurately detect the position of the traveling vehicle. It is to provide a vehicle navigation system that can perform.

[0014]

Therefore, in the present invention, a display means including a switch input mechanism, a map information storage section for storing road map information, a geomagnetic sensor for detecting geomagnetism, and a vehicle speed are detected. The vehicle speed sensor, the gyro that detects the turning angular velocity, and the azimuth axis correction based on the integrated value of the gyro output value, and the map information of the current position estimated from the geomagnetic sensor, the vehicle speed sensor, and the output value of the gyro is stored as map information. And a control means for reading out from the unit and displaying it on the display means. This aims to achieve the above-mentioned object.

[0015]

The control means obtains the center and radius of the circular turning from the output value of the geomagnetic sensor when the vehicle makes one revolution.

Next, the gyro output value is integrated with reference to the time when the operator turns the vehicle to magnetic north. Then, the azimuth axis of north, south, east, and west is obtained from the output value of the geomagnetic sensor at the time when the integrated value becomes a multiple of 90 degrees and the center of the circular turning.

When an arbitrary geomagnetic sensor output value is input during traveling, the control means performs correction based on each azimuth axis and the angle between each azimuth axis to obtain an accurate azimuth.

Further, the control means estimates the current position from the obtained azimuth and the output values of the vehicle speed sensor and the gyro, reads the map information of the current position from the map information storage section, and displays it on the display means.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS.

In the embodiment shown in FIG. 1, a display means 50 including a switch input mechanism, a map information storage section 60 for storing road map information, a geomagnetic sensor 20 for detecting geomagnetism,
A vehicle speed sensor 10 for detecting a vehicle speed and a gyro 30 for detecting a turning angular velocity are provided. Further, the azimuth axis is corrected based on the integrated value of the output value of the gyro 30, and the map information of the current position estimated from the output values of the geomagnetic sensor 20, the vehicle speed sensor 10 and the gyro 30 is read from the map information storage unit 60. Control means 4 displayed on the display means 50
0 is equipped.

Next, the operation of this embodiment will be described.

Here, as initial conditions, various flags, various parameters, and contents of various arrays are all cleared to 0.

The operator controls the start of turning of the vehicle by the control means 40.
The following processing is started when the notification is sent to.

(1). The control means 40 is the geomagnetic sensor 2
The output signals x (t) and y (t) of 0 and the output signal g (t) of the gyro 30 are input, and sampling processing is performed and stored in the internal memory.

(2). The control means 40 checks the turning start flag, and if the value is not "1", the gyro 3
Check the output change G _{d of} 0.

(3). As a result of checking the output change G _d of the gyro 30 in the processing of (2) above, the control means 40 determines that the vehicle has not yet been turned if it is equal to or less than the preset value G _s. Then, the process returns to the above (1) without doing anything.

On the other hand, returns to the case where it exceeds the value G _s change G _d of the gyro output is preset by the turning start flag to "1" in the process (1).

(4). On the other hand, in the process of (2) above, if the turning start flag is "1", the number of data NUM is checked.

(5). The control means 40 determines the number of data NUM
If the number of data NUM is 0 as a result of checking, the value of the output signal x (t) of the geomagnetic sensor 20 is set to the initial value S of x.
Maximum value of T_X and x MAX_X and minimum value of x MIN_X
Let the output signal y (t) be the initial value ST_Y of y, the maximum value MAX_Y of y, and the minimum value MIN_Y of y.

On the other hand, if the data number NUM is not 0, the control means 40 outputs the output signal x (t) of the geomagnetic sensor 20,
The value of y (t) is compared with their maximum and minimum values.

That is, the output signal x of the geomagnetic sensor 20
When the value of (t) is larger than the maximum value MAX_X of x, the value of the output signal x (t) is newly set to the maximum value MAX of x.
_X. When the value of the output signal x (t) of the geomagnetic sensor 20 is smaller than the minimum value MIN_X of x, the value of the output signal x (t) is set to the new minimum value MIN_X of x.

Similarly, the output signal y of the geomagnetic sensor 20
When the value of (t) is larger than the maximum value MAX_Y of y, the value of the output signal y (t) is newly set to the maximum value MAX of y.
_Y. When the value of the output signal y (t) of the geomagnetic sensor 20 is smaller than the minimum value MIN_Y of y, the value of the output signal y (t) is set to the new minimum value MIN_Y of y.

(6). Further, the control means 40 adds the value of the output signal g (t) of the gyro 30 to the gyro integral value SG, and the difference DX between the output signal x (t) of the geomagnetic sensor 20 and the initial value ST_X of X and its absolute value. ABS_D
Find X and.

(7). The control means 40 checks whether the turning monitoring flag is even.

If the turning monitoring flag is not an even number, it is checked whether the absolute value ABS_DX is less than or equal to a preset value D2.

On the other hand, if the turning monitoring flag is an even number, it is checked whether or not the absolute value ABS_DX is greater than or equal to a preset value D1.

(8). In the process (7), when the turning monitoring flag is even and the absolute value ABS_DX is D1 or more, or when the turning monitoring flag is odd and the absolute value ABS_D is
When X is D2 or less, "1" is set to the state array S [N] if the value of DX is positive, and "-1" is set to the state array S [N] if the value of DX is negative. Set. Then, the turning monitoring flag and the state array element number N are incremented by one.

On the other hand, when the turning monitoring flag is even, the absolute value AB
If S_DX is D1 or less, or if the turning monitoring flag is an odd number and absolute value ABS_DX is D2 or more, nothing is done and the process proceeds to the following.

(9). The control means 40 checks whether the turning monitoring flag is 3 or more.

(10). In the process (9), if the turning monitoring flag is 3 or more, it is further checked whether the turning monitoring flag is 5 or more.

(11). In the above process (10), the turning monitoring flag is 5 or more, or the turning monitoring flag is not 5
If S [N], S [N-1], and S [N-2] are the same, it is determined that the vehicle has made one or more turns, and the turning end flag is set to "1". The output value x (t) of the geomagnetic sensor 20 is the final value EN_X, and the output value y (t) of the geomagnetic sensor 20 is the final value EN_Y.

Further, the end of turning is displayed on the display means 50.

On the other hand, in the processing (9), when the turning monitoring flag is less than 3 , and in the processing (10), the turning monitoring flag is less than 5 , S [N] and S [N-1].
And S [N-2] are not the same, the process proceeds to the following process without doing anything.

(12). The control means 40 determines the number of data NU
Increment M by 1.

(13). The control means 40 checks whether the turning end flag is "1".

(14) In the process (13), if the turning end flag is not "1", the process returns to the process (1).

On the other hand, if the turning end flag is "1",
MAX_X, MAX_Y, MIN_ of the geomagnetic sensor 20
From X and MIN_Y, the center (x ₀ , y ₀ ) of the azimuth circle and the radius r are calculated.

(15). Next, the operator turns the vehicle to magnetic north. The control means 40 obtains the north azimuth PN as shown in FIG. 2 from the output values (x _N , y _N ) of the geomagnetic sensor 20 at this time and the azimuth center (x ₀ , y ₀ ), and at the same time, FIG. As shown in, the time t (= t _N ) when it coincides with the north direction P _N is calculated from the geomagnetic sensor output value g (t) stored in the internal memory.

(16). As shown in FIG. 3, when the measurement time range of the geomagnetic sensor output value g (t) stored in the internal memory of the control means 40 is t0 to t5,
The gyro output is integrated in the direction in which the amount of data is large when viewed from t _N. Here, integration is performed in the direction of t ₀ .

(17). The control unit 40 calculates t at each time when the vehicle turning angle that can be calculated from the gyro integral value Gn becomes 90 degrees.
Is obtained, and they are sequentially set as t _W , t _S , and t _E.

That is, assuming that the gyro integral value in the direction from tN to t0 is G1, the time when the following equation is satisfied is tW.
And

[0052]

[Equation 1]

KG ₁ = 90 (degrees)

Here, null is a reference voltage of the gyro output, and k is an angle conversion coefficient for converting the voltage value into an angle.

When t _W is determined, t _S is calculated next. That is, when the gyro integral value from t _W to t ₀ is G2, the time when the following expression is satisfied is t S.

[0056]

[Equation 2]

KG ₂ = 90 (degrees)

Once t _S has been determined, t _E is then determined. That is, when the gyro integral value in the direction from t _S to t ₀ is G ₃ , the time when the following equation is satisfied is t _E.

[0059]

[Equation 3]

KG3 = 90 (degrees)

(18). The control means 40 controls t _W , t _S and t
If there is no data in the direction where integration was first started, that is, in the direction t ₀ before the three _Es are determined, the process returns to tN, and the gyro output is integrated in the opposite direction, that is, direction t _5. To go.

(19). The control means 40 uses the above (17).
In the same manner as described above, t is calculated each time the vehicle turning angle that can be calculated from the gyro integral value Gn becomes 90 degrees.

(20). The control means 40 controls t _N , t _W , and t.
_The integration work is terminated when four of _S and t _E are obtained.
At this time, t _N , t _W , t _S , and t _E are when the vehicle turns to the north, west, south, and east, respectively, if the turn is a right turn, and as shown in FIG. Geomagnetic sensor data (x (t _N ), y (t _N )), (x (t _W ), y
(T _W )), (x (t _S ), y (t _S )), (x (t _E ),
y (t _E )) and the azimuth circle center (x ₀ , y ₀ ), the north, west, south, and east azimuth axes (P
_N , P _W , P _S , P _E ) and azimuth axis spacing (θ _NE , θ _ES , θ
_SW , θ _WN ) is calculated.

(21). The control means 40 calculates the azimuth P _i calculated from an arbitrary geomagnetic sensor output (x _i , y _i ) by the azimuth axis intervals θ _NE , θ _ES , θ _SW , and θ W-N obtained here.
To correct. If the angle is calculated counterclockwise with respect to the north azimuth, the corrected azimuth P _i ′ is obtained by one of the following expressions (1) to (4).

When P _N ≤P _i ≤P _W

P _i '= P _i · (90 / θ _WN )

When P _W <P _i ≤P _S

P _i '= P _W + (P _i −P _W ) · (90 / θ _SW ) ...

When P _S <P _i ≤P _E

P _i '= P _S + (P _i −P _S ) · (90 / θ _ES ) ...

When P _E <P _i <P _N

P _i '= P _E + (P _i −P _E ) · (90 / θ _NE ) ...

As described above, according to the present invention, when the geomagnetic sensor is initialized, the gyro output is simultaneously captured together with the geomagnetic sensor output, and the geomagnetic sensor output is obtained by using the turning angle of the vehicle obtained by the integrated value of the gyro output. The azimuth axis in the azimuth circle of is corrected.

[0074]

Since the present invention is constructed and functions as described above, according to this, it is possible to automatically correct the deviation of the azimuth axis due to the distortion of the lines of magnetic force, which enables accurate position detection. Therefore, it is possible to provide an unprecedented excellent vehicle navigation system that can improve the reliability of the vehicle navigation system.

[Procedure Amendment 2]

[Document name to be corrected] Drawing

[Name of item to be corrected] Figure 3

[Correction method] Change

[Correction content]

[Figure 3]

Claims (1)

[Claims] 1. A display unit including a switch input mechanism, a map information storage unit for storing road map information, a geomagnetic sensor for detecting geomagnetism, a vehicle speed sensor for detecting vehicle speed, and a gyro for detecting turning angular velocity. From the map information storage unit, the map information of the current position estimated from the output value of the geomagnetic sensor, the vehicle speed sensor, and the gyro while correcting the azimuth axis based on the integrated value of the output value of the gyro. A vehicle navigation system equipped with a control means for reading and displaying on the display means.