JPH0739959B2 - Magnetization correction method for geomagnetic direction sensor - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetization correction method for a geomagnetic direction sensor, and more specifically, a geomagnetic direction sensor for a moving body having a component that is magnetized by an external factor. The present invention relates to a magnetization correction method for a geomagnetic direction sensor, which is applied to a position detection device that detects a position of a moving body based on an output signal from the geomagnetic direction sensor and an estimated traveling direction of the moving body.

<Prior Art> Conventionally, as a method for detecting the position of a vehicle traveling at an arbitrary point in a road traffic network, a processing device that performs necessary processing on output signals from a distance sensor, a direction sensor, and both sensors. A dead reckoning method has been proposed which includes the following, and obtains the current position data of the vehicle by integrating the amount of change in distance and the amount of change in heading that occur as the vehicle travels. There is a problem that the error inevitably possessed by the sensor is accumulated as the running continues, and the error included in the obtained current position data is also accumulated.

In particular, when a geomagnetic orientation sensor is used as the orientation sensor, an accurate orientation detection signal should be output based on the relative relationship between the geomagnetism and the sensor if the vehicle is not magnetized at all. However, there is almost no state that the car body is not magnetized at all, and the car body is magnetized to some extent, so it is detected by the geomagnetic direction sensor under the influence of car body magnetization. This means that the azimuth of the vehicle is significantly deviated from the actual vehicle traveling azimuth.

More specifically, since the center of the geomagnetic orientation circle coincides with the origin of the coordinates when the vehicle body is not magnetized at all (see FIG. 6A), the geomagnetic orientation sensor An accurate direction vector D1 can be obtained based on the output data (x1, y1).

However, in the state where the vehicle body is magnetized, the center of the geomagnetic direction circle deviates from the origin of the coordinates depending on the degree of vehicle body magnetization (see FIG. 6B), and the output from the geomagnetic direction sensor The azimuth vector D2 obtained based on the data (x2, y2) is significantly different from the accurate azimuth vector D1, which makes it impossible to detect the vehicle position accurately. .

In order to solve such problems, 360
Or circled by a predetermined angle less than 360 degrees, the vehicle body magnetization amounts Δx1 and Δy1 are detected based on the output circle obtained as a result of the circular traveling, and the above detection is performed in actual driving thereafter. A method has been proposed for obtaining accurate azimuth data by performing correction based on the vehicle body magnetization amounts Δx1, Δy1 (issued in December 1984, Toyota Engineering Vol. 34, No. 2, "Development of Navicon"). ).

<Problems to be Solved by the Invention> In the above-described magnetization correction method, when new vehicle body magnetization occurs during actual traveling (when passing through a railroad crossing, etc.)
With respect to the above, there is a high possibility that the magnetization correction cannot be performed, and therefore, there is a high possibility that the vehicle position detection accuracy will be significantly reduced.

More specifically, the above-mentioned magnetization correction method is
It is indispensable to drive in a circle that rotates by a predetermined angle less than 360 degrees or 360 degrees, but it is guaranteed that there is a space where the above-mentioned circle travel can be performed in the middle of actual traveling, or the vehicle body There is no guarantee that the traveling direction will be changed within a short time after magnetization occurs, there is no space, or the traveling direction is not changed.
The vehicle position must be detected without performing the magnetization correction. In particular, during actual driving, the frequency of vehicles passing through a strong magnetic field area such as a railroad crossing is quite high, and the vehicle body magnetization amount after passing through such a strong magnetic field area changes from Δx1, Δy1 to Δx2, Δy2. Therefore, in order to accurately detect the position of the vehicle, the magnetization correction amount must be changed from Δx1, Δy1 to Δx2, Δy2.

Therefore, if correction is performed using the previous magnetization correction amounts Δx1 and Δy1 instead of the new magnetization correction amounts Δx2 and Δy2,
Since the correction amount irrelevant to the actual magnetization amount has been selected, the position of the vehicle cannot be detected accurately.

In addition, after the vehicle body is actually magnetized, the output data from the geomagnetic direction sensor is collected when there is a change in the traveling direction that is larger than a predetermined value (a value capable of correcting the vehicle body magnetization),
If the necessary analysis and processing are performed, it may take a long time until the magnetization correction amount is obtained depending on the road conditions, and the detected vehicle position may deviate from the actual position during that time. Moreover, there is a problem in that it is impossible to know the degree of deviation.

<Objects of the Invention> The present invention has been made in view of the above problems,
It is an object of the present invention to provide a method capable of easily performing the magnetization correction of the geomagnetic direction sensor without performing either circular traveling or changing the traveling direction.

<Means for Solving the Problems> In the magnetization correction method according to claim 1 for achieving the above object, the moving bodies having the constituent portions that are magnetized by an external factor have the same magnetization method. , And the geomagnetic direction sensors are installed at the positions where the magnetic flux densities due to the above-mentioned magnetization are different from each other, and the output signal Vx from each geomagnetic direction sensor is
Based on 1, Vy1, Vx2, Vy2, the magnetization direction α is calculated by α = tan ^-1 {(Vy1-Vy2) / (Vx1-Vx2)} and the output signal Vx1, Vy1 from one geomagnetic direction sensor is calculated. When Based on The magnetization amount G1 is calculated in accordance with, and the azimuth detection signal is corrected based on the calculated magnetization direction α and the magnetization amount G1.

The magnetization correction method according to claim 2 is the above-mentioned method. However, when the moving body is a vehicle, it is obtained by the method described in any one of (a), (b) and (c) below.

(A) Before traveling of the vehicle, the point where the geomagnetic direction sensor is initialized and the direction of the vehicle at the point where the geomagnetic direction sensor is initialized are fixed, and the fixed direction of the vehicle is measured using a map or a compass. To do.

(B) Before traveling of the vehicle, the direction of the road at the initial position is adopted when setting the initial position of the navigation system or the location system using the map matching method.

(C) When the vehicle is traveling, the difference in wheel speed is acquired based on the output of the wheel speed sensor, the relative direction change amount is calculated based on the acquired difference in wheel speed, and the calculated relative direction is calculated. The amount of change is added to the estimated traveling direction of the vehicle which is obtained immediately before.

<Operation> In the configuration according to claim 1, the moving bodies having the constituent portions that are magnetized by an external factor have the same magnetizing direction and have different magnetic flux densities due to the magnetizing at predetermined positions. A geomagnetic orientation sensor is attached. Therefore, the output signals Vx1, which have the same magnetization direction but different magnetization amounts,
Vy1, Vx2, Vy2 can be obtained. Therefore, the magnetization direction α can be obtained based on the output signals Vx1, Vy1, Vx2, and Vy2 of the geomagnetic direction sensors.

Further, the center coordinates of the azimuth circle of the geomagnetic azimuth sensor correspond to the intersection of the straight line determined based on the magnetization direction α and the straight line determined based on the moving direction of the moving body. Therefore, the output signals Vx1, Vy1 and Based on, the center coordinates of the azimuth circle can be obtained. Therefore, the magnetization amount G1 can be obtained.

The above For example, when the moving body is a vehicle, it is calculated as in the configuration of claim 2.

As described above, according to the above configuration, the magnetizing direction α and the magnetizing amount G1 can be obtained without circularly moving the moving body or changing the moving direction, so that the azimuth detection signal can be easily corrected. You can

<Example> Hereinafter, detailed description will be given with reference to the accompanying drawings illustrating an example.

FIG. 1 is a view schematically showing a state in which two geomagnetic direction sensors (2) and (3) are attached to a predetermined position of a vehicle (1), and the magnetization directions when the vehicle body is magnetized are the same. And so that the influences of the equivalent magnet (12) on the roof (11) and the equivalent magnet (14) on the lower part of the body (13) are different from each other.
Are installed in different places. Specifically, the geomagnetic direction sensor (2) is installed at a location at a distance 11 from the roof (11), and the geomagnetic direction sensor (3) is located at a location 12 (12> 11) from the roof (11). Installed.

The geomagnetic direction sensors (2) and (3) have the same characteristics.

FIG. 2 is a schematic view showing a fluxgate type geomagnetic direction sensor as an example of the geomagnetic direction sensors (2) and (3), which are mutually opposed to the toroidal core (21) excited by the exciting circuit (22). Output windings in quadrature (23)
(24) is provided.

The signals Vx and Vy output from the output windings (23) and (24) are in a state in which a magnetic field having a magnetic flux density of g intersects the geomagnetic direction sensor (2) and (3) at an angle ψ (first 2), Vx = gS cos ψ Vy = gS sin ψ. However, S is an output coefficient of the geomagnetic direction sensor.

In addition, information indicating the direction of the vehicle in the state where the vehicle (1) is directed in a predetermined direction, information indicating a preset road direction, or relative calculated based on a difference in wheel speed. Depending on the amount of change in direction, etc. Can be obtained.

Therefore, the signals Vx1, which are extracted from the output windings (23), (24), (33) and (34) of the dual geomagnetic direction sensors (2) and (3), respectively.
Vy1, Vx2, Vy2 and Based on the above, the magnetization correction is performed as follows, and the true traveling direction θ of the vehicle can be obtained.

FIG. 3 is a diagram schematically showing the configuration of a device for detecting the true traveling direction by performing the magnetization correction. The output signals from the geomagnetic direction sensors (2) and (3) and the wheel speed sensor ( The output signal from 4) is supplied to the arithmetic processing unit (5),
In the arithmetic processing unit (5), the true traveling direction θ of the vehicle is obtained by performing arithmetic processing described in detail below. In addition, as the wheel speed sensor (4),
For example, a magnetic resistance element and a magnetic belt may be used, but the wheel speed sensor is not limited to this structure, and a wheel speed sensor having another structure may be used. .

More specifically, the dual geomagnetic direction sensor (2)
Since the mounting position of (3) is very close to the roof (11), most of the magnetic field strength inversely proportional to the square of the distance is due to the equivalent magnet (12) and the equivalent magnet (14) The resulting component is almost nonexistent. Therefore, in the following description, the dual geomagnetic direction sensor (2)
(3) is the effect of the equivalent magnet (12) on the roof (11),
And it is assumed that it is only affected by geomagnetism.

First, for each magnetic direction sensor (2) (3), the magnetic field (the magnetic flux density received by each magnetic direction sensor (2) (3) is G1, G2) caused by the equivalent magnet (12), and the geomagnetism ( Since the magnetic flux density B) acts, the output signal from each output winding is as shown in FIG. Becomes Where a is the change rate of the radius of the azimuth circle (where a>
0, and a = 1 when the geomagnetism is normal) Is the angle at which the magnetic field caused by the equivalent magnet (12) intersects with the geomagnetic direction sensors (2) and (3), that is, the magnetization direction.

Therefore, the magnetization direction α of the roof (11) is calculated as α = tan ⁻¹ {(Vy1−Vy2) / (Vx1−Vx2)}.

In this way, the magnetization direction α of the roof (11) is calculated based on the output signals Vx1, Vy1, Vx2, Vy2 of the geomagnetic direction sensors (2), (3).

In the azimuth circle of the geomagnetic azimuth sensor (2),
The straight line L1 extending in the magnetizing direction α and the straight line L2 extending in the traveling direction of the vehicle (1) are the fifth points, if r1 and r2 are arbitrary lengths starting from the origin and the points (Vx1, Vy1). As shown in the figure, Respectively represented as.

Therefore, at the intersection of both straight lines L1 and L2, Therefore, the relation of As a result, we can get r1 and r2.

As a result, the magnetization amount G1 of the geomagnetic direction sensor (2) and the radius R of the azimuth circle are Obtained as.

As described above, the magnetization amount G1 is calculated based on the output signals Vx1, Vy1, Vx2, and Vy2 of the geomagnetic direction sensors (2) and (3), and thus the magnetic direction sensor (2 )
(3) output signals Vx1, Vy1, Vx2, Vy2 and Can be calculated based on

Further, the center coordinates (Ox1, Oy2) of the azimuth circle can be obtained by substituting the equation for r1 into the equation for the straight line L1. Obtained as.

Further used in the above operations If you want to initialize the geomagnetic direction sensor, fix the point that initializes the geomagnetic direction sensor and the vehicle direction at that point, and fix the fixed vehicle. The direction of is measured beforehand using a map or compass, or
Alternatively, in the case of a map matching type navigation system or location system, by obtaining the direction of the vehicle from the direction of the road at that point at the time of initial position setting, Can be obtained.

If the magnetization correction is performed during traveling, the wheel speed difference is acquired based on the output of the wheel speed sensor (4), and the relative direction change amount is calculated based on the acquired difference signal. The calculated relative bearing change amount By adding to Can be obtained.

As described above, the magnetization amount G1 of the one geomagnetic direction sensor (2), the changed radius R of the direction circle, and the magnetization direction α can be obtained. Then, the true traveling azimuth θ of the vehicle is θ = tan ⁻¹ {(based on the center coordinates (Ox1, Oy2) of the azimuth circle and the outputs Vx1, Vy1 of one of the geomagnetic azimuth sensors (2) and (3). Vy1-Oy1) / (Vx1-Ox1)}.

In the above embodiment, the geomagnetic direction sensor (2)
Based on the output of Finally, the true traveling direction θ of the vehicle
To obtain the geomagnetic direction sensor (2) (3)
Based on the output of Finally, the true traveling direction θ of the vehicle
May be obtained.

Further, in the above embodiment, Although only the case of is explained, In this case, the magnetization correction can be performed as follows.

When initializing the geomagnetic direction sensor In this case, it is sufficient to prepare a plurality of orientations of the vehicle (1) for initialization. Since the condition is satisfied, the geomagnetic direction sensor can be initialized as in the above embodiment.

When performing magnetization correction while the vehicle is traveling In this case, magnetization correction cannot be performed. Or Therefore, since the true traveling direction θ of the vehicle can be easily obtained by calculating α based on the output signal of the geomagnetic direction sensor, the magnetization correction operation of the above embodiment cannot be performed. But there is no inconvenience. The above Or The selection may be made based on, for example, an estimated value of the current traveling direction calculated based on the output signal from the wheel speed sensor.

The present invention is not limited to the above-described embodiment, and for example, a geomagnetic direction sensor other than the fluxgate type geomagnetic direction sensor can be used, and it can be applied to a moving body other than a vehicle. In addition, various design changes can be made without departing from the scope of the present invention.

<Effects of the Invention> As described above, according to the present invention, when magnetizing occurs and the direction detected by the geomagnetic direction sensor deviates from the true direction, a plurality of moving objects mounted on the moving body are not moved circularly. Based on the output signal from the geomagnetic direction sensor and the estimated traveling direction of the moving body, a correction value capable of compensating for the deviation of the detected direction can be calculated. Therefore, it is possible to continue the original movement of the moving body as it is, and it is possible to perform the accurate and quick position detection.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic view for explaining a state in which two geomagnetic direction sensors are attached to a vehicle, and FIG. 2 shows a configuration of a fluxgate type geomagnetic direction sensor as a kind of geomagnetic direction sensor. FIG. 3 is a schematic diagram, FIG. 3 is a block diagram showing a schematic configuration of an apparatus for performing magnetization correction, FIG. 4 is a diagram showing a relationship of azimuth circles corresponding to various magnetic azimuth sensors, and FIG. FIG. 6 is a diagram illustrating the calculation principle of FIG. 6, and FIG. 6 is a diagram illustrating a state in which the magnetization correction is not performed. (1) ... vehicle, (2) (3) ... geomagnetic direction sensor (4) ... wheel speed sensor, (5) ... arithmetic processing unit (12) ... equivalent magnet, (23) (24) ( 33) (34) …… Output winding

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Osamu Shimizu 1-3-1 Shimaya, Konohana-ku, Osaka City, Osaka Prefecture Sumitomo Electric Industries, Ltd. Osaka Works (72) Toshiyuki Shimizu 1 Shimaya, Konohana-ku, Osaka City, Osaka Prefecture 1 to 3 Sumitomo Electric Industries, Ltd. Osaka Works (56) Reference JP 60-135814 (P, A) JP 61-269014 (P, A) JP 61-269015 (P, A) ) JP-A-58-115376 (P, A)

Claims (2)

[Claims] 1. A geomagnetic direction sensor is attached to a moving body having a constituent portion magnetized by an external factor, the magnetizing methods being the same, and the magnetic flux densities resulting from the magnetizing are different from each other. Based on the output signals Vx1, Vy1, Vx2, Vy2 from each geomagnetic direction sensor, α = tan ^-1 {(Vy1-Vy2) / (Vx1-Vx2)} is used to calculate the magnetization direction α and Output signals Vx1, Vy1 from the direction sensor Based on A magnetization correction method for a geomagnetic bearing sensor, characterized in that the magnetization amount G1 is calculated by, and the direction detection signal is corrected based on the calculated magnetization direction α and the magnetization amount G1. 2. The above Is a vehicle, the following (a), (b)
Alternatively, it is obtained by any one of the methods described in (c), and the magnetization correction method for the geomagnetic direction sensor according to claim 1, characterized in that it is obtained. (A) Before traveling of the vehicle, the point where the geomagnetic direction sensor is initialized and the direction of the vehicle at the point where the geomagnetic direction sensor is initialized are fixed, and the fixed direction of the vehicle is measured using a map or a compass. To do. (B) Before traveling of the vehicle, the direction of the road at the initial position is adopted when setting the initial position of the navigation system or the location system using the map matching method. (C) When the vehicle is traveling, the difference in wheel speed is acquired based on the output of the wheel speed sensor, the relative direction change amount is calculated based on the acquired difference in wheel speed, and the calculated relative direction is calculated. The amount of change is added to the estimated traveling direction of the vehicle which is obtained immediately before.