JPH061195B2 - Magnetization using a digital map. Geomagnetic deviation area detection method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to a vehicle equipped with a navigation system and a location system, which is a constituent part of these systems due to the influence of geomagnetic deviation and magnetization received during traveling. The azimuth output data from the geomagnetic azimuth sensor of the vehicle position detection device becomes unstable, and the system may malfunction as a result.However, in order to perform the avoidance process, the vehicle running, the magnetized area, and the It relates to a method of detecting passage through a geomagnetic deviation area.

[Background Art] Generally speaking, a vehicle navigation system is
The purpose is to display the road map, the vehicle position, and the target position on the in-vehicle display to assist the driver in driving. It becomes a thing.

On the other hand, the location system aims at grasping the current positions and working states of a large number of vehicles such as emergency vehicles and delivery vehicles at the control center, and conducting and operating them efficiently in a short time. This system requires in-vehicle equipment and ground equipment.

Here, what is common to both of the above systems is that an on-vehicle vehicle position detection device is required. Various types of vehicle position detecting devices have been proposed. In the present invention described below, a wheel speed sensor is used as an example of an angle sensor and a distance sensor, and a geomagnetic direction sensor, a wheel speed sensor, and a digital road memory. , A processing device and the like.

FIG. 1 is a schematic diagram of the position detecting device, in which 1 is a right wheel of a vehicle, 2 is a left wheel, and 3 and 4 are right and left wheel speed sensors, respectively. The wheel speed sensor has, for example, a method of electromagnetically detecting the rotation of a soft iron pulsar attached to a wheel. Such a wheel speed sensor is usually attached to the left and right rear wheels of a vehicle and is calculated by a processing device. The vehicle has a function such that the vehicle traveling distance and the difference in the number of rotations of the left and right wheels in the curve can determine the bending angle of the vehicle, and another angle sensor and a distance sensor may be used instead. Reference numeral 5 denotes a geomagnetic direction sensor attached to the vehicle, which will be described later in detail, but has orthogonal fluxgates and has a function of detecting a horizontal component of geomagnetism and a magnetic field crossing the fluxgates such as vehicle body magnetization. Is something
Reference numeral 6 is a processing device, and 7 is a digital map memory.

The output of the geomagnetic direction sensor 6 and the outputs of the wheel speed sensors 3 and 4 are sent to the processing device 6, and the processing device 6 correlates the data from the geomagnetic direction sensor 5 and the wheel speed sensors 3 and 4 with the digital map memory 7. Then, the current position of the vehicle is estimated and displayed on the digital road map.

By the way, if there is an elevated road or a large structure, the geomagnetism is distorted in the surroundings, causing so-called magnetic deviation, and a running vehicle detects the magnetism affected by this.

Further, when a vehicle passes a railroad crossing or travels on a tramway, noise may be temporarily received, or a fixed error may occur after the vehicle body is magnetized.

Therefore, the geomagnetic direction sensor described above must always indicate the direction without error even if there is such a magnetic deviation or magnetization.

Therefore, Japanese Patent Application No. 60-111739 (Japanese Patent Application Laid-Open No. 61-269014) proposes a method of correcting the measurement error of the geomagnetic direction sensor, which can correct the magnetic deviation and the magnetization even if there is a magnetic deviation. . Here, the correction method in the above invention including the principle of the conventional magnetic direction sensor will be described with reference to FIGS. 2 and 3.

FIG. 2 shows a geomagnetic direction sensor. Reference numeral 10 is an annular ferromagnetic iron core, 11 is an exciting winding, and a magnetomotive force is applied by an AC power source until just before saturation. Reference numerals 12 and 13 denote secondary side output windings X and Y which are wound orthogonally between the outer sides of the iron core 10.

It is assumed that only the geomagnetism exists normally and there is no magnetization of the vehicle body.

When the vehicle rotates 360 ° under this condition, the locus drawn by the voltages V _x and V _y induced in the two output windings X and Y on the secondary side of the geomagnetic sensor is the radius KB (where K depends on the output winding). coefficient,
B should be a circle of the horizontal component of the earth's magnetic field. Third
The dotted circle in the figure shows this.

Next, when magnetic fields other than the earth's magnetism are superimposed at an angle α and a magnitude G, the locus drawn by X _x , V _y should be as shown by the solid line in the figure. After all, the magnetic field O due to the horizontal magnetic field
A moves to OB, and in the case of the figure, only the direction reduced is shown. This is the heading error.

Next, one method of correcting such an error will be described.

In FIG. 3, assuming that the coordinates of the point B are (V _x , V _y ), a solid line equation is obtained from V _x = KBcos θ + G cosα ... Formula V _y = KBsin θ + G sinα.

_{V x -Gcosα = KBcosθ V y -Gsinα} = KBsinθ than those ^{_{(V x -Gcosα) 2 + (}} V y -Gsinα) 2 = (KB) 2 (cos 2 θ + sin 2 θ) = (KB) 2 ............ The formula is the center of the circle (Gcosα, Gsinα), the circle of radius KB,
In other words, it represents the solid circle in the figure.

Next, _{V x-direction} at the point B of the circle, obtaining the derivative of _{V y} direction.

Differentiating equation, with respect to θ, Becomes

From formula, and formula, The expression, represents the V _x component and V _y component of the magnetization amount.

The size G and the angle α are obtained from the equations as follows.

In the formula, V _x , V _y , dV _x , and dV _y are obtained from the direction sensor, and dθ is obtained from the wheel speed sensors attached to the left and right wheels of the vehicle.

[Means for Solving Problems] As described above, when the above-described correction method is used using the geomagnetic direction sensor, it is possible to correct the traveling direction of the vehicle and give an instruction. In general, the fluctuation of the external magnetic field when passing through the magnetic deviation and the magnetizing area is large in general, and therefore the azimuth in the meantime is not necessarily reliable, and therefore, the passing through such area The detection of the azimuth at time is not based on the data from the magnetic azimuth sensor, but based on the distance data and the angle data from the wheel speed sensor and the road in the digital map memory,
The position of the vehicle is estimated, and after passing through the area, the data of the magnetic bearing sensor is used again to detect the position of the vehicle while traveling.

Therefore, according to the present invention, in the road network information in the digital map memory, the magnetization and the deviation are respectively expressed corresponding to the road links including the places where the magnetization such as the railroad crossing occurs, the tunnel, and the elevated road. In a processing device to which an identifier is added and data from the geomagnetic direction sensor and data from the wheel speed sensor are input, the position data is collated in the road network in the corresponding map memory, and the road link with the identifier is detected. After that, the output from the geomagnetic direction sensor is eliminated, and the use of only the data from the wheel speed sensor is switched to. After passing through the area, the geomagnetic direction sensor is corrected again and it is used as the direction information thereafter. It is a thing.

Examples of the present invention will be described below.

FIG. 4 (a) shows the passage of the crossing b of the vehicle a, and FIG. 5 (a).
Indicates the passage of the vehicle a along the elevated road c. Figure 4 (b),
FIG. 5B is a digital map corresponding to the railroad crossing b and the elevated road c, and is an area where the geomagnetic direction sensor is affected by the magnetization and the magnetic deviation as shown by d and e. Assuming that the traveling direction of the vehicle is in the direction indicated by the arrow, P indicates the estimated position of the vehicle a, but at the estimated position of the vehicle outside the range of these influences, the vehicle enters or crosses the railroad crossing b or the elevated road c. For completion detection, using the identifier, on the corresponding digital map memory, corresponding to the magnetized, magnetic deviation region, the identifier is added respectively, the data from the geomagnetic sensor is not used by the region entry detection signal, The traveling position is estimated from the data from the wheel speed sensor, and after the passage is completed, the data from the geomagnetic direction sensor and the data from the wheel speed sensor are used again based on the detection signal from the identifier, and the estimated vehicle position when the passage is completed The position is estimated in consideration of. After the passage is completed, particularly in the case of magnetization, it is necessary to correct the magnetized component by the above-mentioned geomagnetic sensor before starting the normal running. Further, the position where the identifier is added has been investigated in advance.

FIG. 6 shows a road network. On the other hand, Table 1 shows the start node and the end node of each road link in the digital map memory, which are written in the memory.

Although the figure shows a case where the road link g has a level crossing d and the road link h has an elevated road c, in this case, as shown in Table 1, a level crossing identifier 1 and a magnetic deviation identifier m are added. It

Table 1 and FIG. 6 show that the road links g and h do not depend on the geomagnetic direction sensor, but in reality,
For example, in the road link g, it may be limited to only a region that is magnetized before and after the railroad crossing d which is particularly problematic in magnetization. In this case, in Table 1, each road link in question can be further subdivided, and temporary start end nodes and end nodes can be defined and written in the memory.

[Operation] The data obtained by processing the output of the geomagnetic sensor has variations. On the other hand, as described above, the azimuth rotation angle can be obtained by processing the outputs of the left and right wheel speed sensors.

By using the absolute azimuth value obtained by the geomagnetic sensor and the relative azimuth value obtained by the wheel speed sensor, the optimum estimated value of the azimuth is calculated at every moment, while traveling the center points of the left and right rear wheels of the vehicle at the optimum azimuth rotation angle. The traveling locus of the vehicle can be obtained by calculating the distances and dividing the distances each time.

However, since a sensor error occurs in this locus as the vehicle travels, an error in the current position occurs. For this reason, the traveling locus of the vehicle is run on the road map memory, and the traveling locus and the road map pattern are corrected so that they match. Accumulation of position errors can be avoided by adding automatic correction.

Thus, the estimated position P shown in FIG. 4 (b) and FIG. 5 (b) is accurate. For example, if the identifier memory on the road map memory is involved at this position, the vehicle is The position of is calculated by calculating the output from the wheel speed sensor. When passing through the magnetized area, the geomagnetic direction sensor is corrected at this point, and then normal traveling is started.

[Effect] According to the present invention, the position detecting device is capable of correcting the influence of the deviation of the geomagnetism and the region of the magnetization even if the position is magnetized.
It is not perfect against the influence, but rather, when passing through the problem area, the output of the geomagnetic direction sensor is excluded, and in the range where the passing distance is short, depending on the rotation direction and the traveling distance by the output from the wheel speed sensor. Since the estimation of the traveling position can be made with a small error, the transition is made without using the output of the geomagnetic direction sensor, and after passing through the area, the output of the geomagnetic direction sensor is corrected, and then the normal traveling is performed. The detection accuracy of the estimated position of the vehicle can be improved.

In addition, even if the distance under the overpass is long, the road is specified, so even if only the wheel speed sensor and map memory are used,
The detection accuracy of the estimated position does not matter.

[Brief description of drawings]

FIG. 1 shows a position detecting device for a traveling vehicle. 2 and 3 are explanatory views of the geomagnetic direction sensor and its correction method. FIG. 4 (a) is an explanatory diagram of the magnetized area, and FIG. 4 (b) shows the digital map of (a). FIG. 5 is an explanatory diagram of the geomagnetic deviation region, and FIG. 5B shows the digital map of FIG. FIG. 6 is an explanatory diagram of a digital map of a road network. 1 ... right wheel, 2 ... left wheel, 3, 4 ... wheel speed sensor, 5 ...
Geomagnetic direction sensor, 6 ... Processing device, 7 ... Digital map memory, 10 ... Ring core, 11 ... Excitation winding, 12 ... X winding, 13 ...
Y winding.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kunihiko Mitto 1-3-3 Shimaya, Konohana-ku, Osaka City, Osaka Prefecture Sumitomo Electric Industries, Ltd. (56) Reference JP-A-58-33284 (JP, A) JP-A-60-89300 (JP, A)

Claims (1)

[Claims] 1. A position detecting device for a traveling vehicle comprising a geomagnetic orientation sensor, an angle sensor, a distance sensor, a digital map memory, and a processing device, wherein when the traveling vehicle passes through a magnetized region and a geomagnetic deviation region, the geomagnetic direction. In order to eliminate the output from the sensor, on the map memory corresponding to the traveling position, an identifier is added to each of the road links having the magnetized region and the geomagnetic deviation region, and the identifier is referred to when the vehicle is linked, Magnetization using a digital map, which is characterized by detecting the magnetized area and the geomagnetic deviation area. Geomagnetic deviation area detection method.