JP2002230683A - On-vehicle magnetic sensor and vehicle position detector equipped therewith - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an on-vehicle magnetic sensor for detecting the intensity of a magnetic field generated from a magnetic marker set on a road surface to calculate the positional displacement of a vehicle, and a vehicle position detector equipped with this sensor. SOLUTION: This magnetic sensor comprises a magnetic detection part 2 for detecting the intensity of a prescribed one-directional magnetic field to the road surface of magnetic fields generated from the magnetic marker set on the road surface and a magnetic body 4 arranged adjacently to the magnetic detection part 2 in order to enhance the magnetic flux density in the one direction.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an on-vehicle magnetic sensor for detecting the strength of a magnetic field generated from a magnetic marker installed on a road surface and calculating a displacement of a vehicle, and a vehicle position detecting device having the same. .

[0002]

2. Description of the Related Art Vehicle position detecting devices used for automatic driving, lane departure prevention warning devices, and the like include, for example, a magnetic system, an optical system, and an image processing system. Above all, the magnetic system is relatively easy to configure and is excellent in economy.

FIG. 6 shows a schematic structure of a conventional magnetic vehicle position detecting device 101. A vehicle position detection device 101 provided on a vehicle (not shown) traveling toward the front of the drawing includes a vehicle-mounted magnetic sensor 103 having a magnetic detection unit 104 capable of measuring a magnetic field strength in two axial directions, and a vehicle position calculation. Unit 108. On the other hand, a magnetic marker 10 having magnetic poles arranged in a direction perpendicular to the road surface 106 is provided on the road surface 106.
2 are installed.

A magnetic detector 104 detects the strength of a horizontal component that is parallel to the road surface and that is perpendicular to the traveling direction of the vehicle and the strength of a vertical component that is perpendicular to the road surface, of the magnetic field generated by the magnetic marker 102. Signal line 110 as a magnetic detection signal
And outputs the result to the vehicle position calculation unit 108. In FIG.
Although only one is shown, usually, a plurality of (for example, five
) Are provided.

[0005] The vehicle position calculation unit 108 is provided for each magnetic detection unit 1.
On the basis of the vertical magnetic flux density data input from 04, the on-vehicle magnetic sensor 103 that has output the highest vertical magnetic flux density data is specified as the detection system closest to the magnetic marker 102, and from the specified on-vehicle magnetic sensor 103 The horizontal displacement of the vehicle with respect to the magnetic marker 102 is calculated based on the input horizontal magnetic flux density data.

[0006]

However, the magnetic field generated by the magnetic marker 102 has a weak horizontal component compared to the vertical component, and the magnetic field between the magnetic detection unit 104 and the magnetic marker 102 is small. When the distance in the direction becomes longer, the SN ratio (signal-to-noise ratio) of the magnetic detection signal decreases, and the problem arises that the detection accuracy of the vehicle displacement calculated by the vehicle position calculator 108 decreases. Therefore, it is necessary to use a large number of in-vehicle magnetic sensors 103 in order to secure a predetermined position detection range, and there is a problem that the cost increases.

An object of the present invention is to provide a vehicle-mounted magnetic sensor capable of accurately detecting the amount of positional displacement of a vehicle at low cost, and a vehicle position detecting device provided with the magnetic sensor.

[0008]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a magnetic detecting section for detecting the strength of a magnetic field in a predetermined direction among magnetic fields generated from a magnetic marker provided on a road surface, and a magnetic detecting section adjacent to the magnetic detecting section. This is achieved by a vehicle-mounted magnetic sensor comprising:

In the above-described magnetic sensor for vehicle use according to the present invention,
The magnetic member is arranged adjacent to the magnetic detection unit along the predetermined one direction.

In the above-described magnetic sensor for vehicle use according to the present invention,
The one direction is a horizontal direction parallel to the road surface and orthogonal to the traveling direction of the vehicle.

In the above-mentioned magnetic sensor for vehicle use according to the present invention,
The magnetic detection unit may further detect a strength of a magnetic field in a direction perpendicular to the road surface.

Further, the above object is to provide an on-vehicle magnetic sensor for outputting a magnetic detection signal based on a magnetic field generated from a magnetic marker installed on a road surface, and a position of a vehicle based on the magnetic marker based on the magnetic detection signal. This is achieved by a vehicle position detecting device having a vehicle position calculating unit for calculating displacement, wherein the vehicle-mounted magnetic sensor of the present invention is used as the vehicle-mounted magnetic sensor.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An on-vehicle magnetic sensor and a vehicle position detecting device provided with the same according to one embodiment of the present invention will be described with reference to FIGS. First, a schematic configuration of a vehicle-mounted magnetic sensor 1 according to the present embodiment will be described with reference to FIG. As shown in FIG. 1, the on-vehicle magnetic sensor 1 of the present embodiment has a magnetic detection unit 2 and a magnetic member 4.

The magnetic detector 2 is made of, for example, cobalt (Co).
It has an elongated strip-shaped (for example, 1 mm in width, 7 mm in length, and 15 μm in thickness) detection element magnetic bodies 10x and 10y using a system magnetic material having zero magnetostriction. Detection element magnetic body 10
x and 10y are arranged so that their longitudinal directions (directions in which the strip-shaped detection element magnetic bodies 10x and 10y extend) are orthogonal to each other in order to detect the strength of the horizontal component and the strength of the vertical component of the magnetic field, respectively. I have. Detection winding 12x, 12y
Are located around the outer circumference of the detection element magnetic bodies 10x and 10y, for example,
It is wound 0 times. One end of the detection element magnetic body 10x is connected to one end of the detection element magnetic body 10y, and the other end of the detection element magnetic bodies 10x and 10y is connected to a power supply 6 for supplying a pulse current or an AC current.

To increase the magnetic flux density penetrating in the longitudinal direction of the detection element magnetic body 10x, for example, a length of 30 cm and an outer diameter of 2 to 3c are provided at both ends in the longitudinal direction of the detection element magnetic body 10x.
A magnetic member 4 having a shape such as a columnar shape or a quadratic prism shape of m is arranged adjacently. The magnetic member 4 is formed of a soft magnetic material having a high magnetic permeability (eg, ferrite). In order to further increase the magnetic flux density in the longitudinal direction of the detection element magnetic body 10x, it is desirable that the distance d between the end of the magnetic member 4 and the detection element magnetic body 10x be small. Further, in order to detect the magnetic field distribution equally, it is desirable that the magnetic members 4 having the same size and shape are arranged symmetrically with respect to the detection element magnetic body 10x.

From the power source 6, the detecting element magnetic bodies 10x, 10y
By passing a pulse current or an alternating current to the magnetic field, the magnetic permeability of the detection element magnetic bodies 10x and 10y can be largely changed. As a result, the magnetic flux density of the external magnetic field penetrating the inside of the detection windings 12x and 12y is changed, and an induced electromotive force is generated in the detection windings 12x and 12y. Detection winding 12
output voltages Ex, Ey at output terminals 5x, 5y of x, 12y
Is detected, the strength of the external magnetic field in the horizontal and vertical directions can be detected.

Next, a schematic configuration of a vehicle position detecting device provided with the on-vehicle magnetic sensor 1 according to the present embodiment will be described with reference to FIG. FIG. 2 shows a schematic configuration of the vehicle position detecting device 3 according to the present embodiment. A vehicle position detecting device 3 provided in a vehicle (not shown) traveling toward the front of the drawing includes a magnetic detecting unit 2 and a magnetic member 4 which can measure the magnetic field strength in two axial directions shown in FIG. Vehicle-mounted magnetic sensor 1 and a vehicle position calculating unit 16. The on-vehicle magnetic sensor 1 includes the detection element magnetic body 10 shown in FIG.
x is installed in a horizontal direction that is parallel to the road surface 18 and is orthogonal to the traveling direction of the vehicle, and is installed such that the longitudinal direction of the detection element magnetic body 10y shown in FIG. I have.

On the other hand, a magnetic marker 14 is provided on a road surface 18. The magnetic detection unit 2 detects the strength of a horizontal component that is parallel to the road surface 18 and that is perpendicular to the traveling direction of the vehicle and the strength of a vertical component that is perpendicular to the road surface 18, of the magnetic field generated from the magnetic marker 14. Signal line 20 as a detection signal
Is output to the vehicle position calculation unit 16 via the. The vehicle position calculation unit 16 calculates a position displacement of the vehicle based on the magnetic marker 14 based on the input magnetic detection signal. Although FIG. 2 shows only one magnetic detection unit 2, FIG.
As shown in (1), in the on-vehicle magnetic sensor 1 of the present embodiment, a smaller number (for example, three) of magnetic detectors 2 than in the related art can be mounted at equal intervals in the horizontal direction of the vehicle.

The vehicle position calculating unit 16 determines the on-vehicle magnetic sensor 1 that has output the highest vertical magnetic flux density data based on the vertical magnetic flux density data input from the magnetic detection unit 2 of each of the on-vehicle magnetic sensors 1. Based on the magnetic flux density data in the horizontal direction input from the on-vehicle magnetic sensor 1 specified as the detection system closest to the magnetic marker 14, the horizontal displacement of the vehicle with respect to the magnetic marker 14 is calculated. I do.

Next, a specific example of the on-vehicle magnetic sensor 1 and the vehicle position detecting device provided with the same according to the present embodiment will be described with reference to FIG. FIG. 3 shows a schematic configuration of an on-vehicle magnetic sensor 1 according to the present embodiment and a vehicle position detecting device provided with the same. As shown in FIG. 3, the body 26 of the vehicle 22 that advances toward the front of the drawing is located at a height of about several tens cm to several tens cm vertically above the road surface 18 via the tires 24. .
The magnetic markers 14 are provided at predetermined intervals along the traveling direction of the vehicle 22. Although FIG. 3 illustrates a state where the magnetic markers 14 are installed in only one row along the traveling direction of the vehicle 22, a plurality of rows of the magnetic markers 14 may be arranged in the width direction of the road surface 18 (the left-right direction in the figure). Of course it is good.

The vehicle-mounted magnetic sensor 1 is installed below the body 26. The on-vehicle magnetic sensor 1 according to the present embodiment has three magnetic detecting units 2, which are arranged at equal intervals in a direction substantially parallel to the road surface 18 and perpendicular to the traveling direction in the vehicle 22. Specifically, one magnetism detection unit 2 is installed at substantially the center of the lower portion of the body 26, and one magnetism detection unit 2 is provided on each of the left and right sides. The four magnetic detection units 2 are adjacent to both ends in the horizontal direction so as to sandwich the magnetic detection units 2 from the left and right in the figure.
Two magnetic members 4 are arranged. Four magnetic members 4
Are preferably configured in the same dimensional shape. By doing so, the magnetic members 4
Can be arranged symmetrically.

In the on-vehicle magnetic sensor 1, the longitudinal direction of the detecting element magnetic body 10x shown in FIG. 1 is a horizontal direction orthogonal to the traveling direction of the vehicle, and the longitudinal direction of the detecting element magnetic body 10y is perpendicular to the road surface 18. It is installed to become. The magnetic detection unit 2 is configured to detect a road surface 1 of a magnetic field generated from the magnetic marker 14.
The strength of a horizontal component parallel to 8 and the strength of a vertical component perpendicular to the road surface 18 are detected, and a magnetic detection signal is output to a vehicle position calculation unit (not shown). As described above, the vehicle position calculation unit performs the magnetic marker 1 based on the input magnetic detection signal.
Then, the amount of positional displacement of the vehicle with reference to 4 is calculated.

Next, the operation of the on-vehicle magnetic sensor according to this embodiment will be described with reference to FIG. The upward arrow on the right side of FIG. 4 indicates the traveling direction of the vehicle. FIG.
Shows a state where the magnetic field generated from the magnetic marker 14 in which the magnetic poles are arranged in a direction perpendicular to the road surface 18 is viewed from a direction perpendicular to the road surface 18. From the magnetic marker 14 installed on the road surface 18, a plurality of magnetic force lines 30 schematically illustrated in FIG.
Extend radially. A circle (for example, a radius of about 30 cm) indicated by a broken line in the figure indicates the limit of the magnetic field strength detectable area 32 in which the conventional on-vehicle magnetic sensor 103 (see FIG. 6) can detect the magnetic field strength of the magnetic marker 14. I have.

As shown in FIG. 4, even if the magnetic detector 2 of the on-vehicle magnetic sensor 1 reaches a position beyond the limit of the magnetic field strength detectable area 32 as the vehicle advances,
One end of the magnetic member 4 adjacent to the left side of the magnetism detector 2 in the drawing is located near the limit of the magnetic field strength detectable region 32. As a result, a magnetic path through which the magnetic flux of the magnetic marker 14 passes is formed in the magnetic member 4 and the magnetic detection unit 2, so that the magnetic flux density of the magnetic flux penetrating in the longitudinal direction of the detection element magnetic body 10x in the magnetic detection unit 2 is increased. be able to.

According to the on-vehicle magnetic sensor 1 and the vehicle position detecting device having the same according to the present embodiment, a magnetic field having a high magnetic flux density can be obtained by the magnetic path formed by the magnetic member 4 adjacent to the magnetic detector 2. Therefore, even if the magnetic detection unit 2 is located outside the magnetic field strength detectable area 32, the strength of the magnetic field from the magnetic marker 14 can be sufficiently detected.
Further, when the magnetic detection unit 2 is within the magnetic field strength detectable region 32, a higher magnetic flux density can be obtained by the magnetic member 4, so that the strength of the magnetic field from the magnetic marker 14 can be detected with higher accuracy. Can be.

As described above, according to the present embodiment, even if the distance between the magnetic detection unit 2 and the magnetic marker 14 increases, it is possible to prevent the S / N ratio of the magnetic detection signal from lowering. Therefore, according to the on-vehicle magnetic sensor 1 and the vehicle position detecting device including the same according to the present embodiment, the positional displacement of the vehicle can be accurately detected, and the positional displacement of the vehicle can be detected in a wider range. . Also, with the improvement of the magnetic field detection accuracy, the number of magnetic detection units conventionally required five can be reduced to three,
A cost reduction effect can be obtained.

FIG. 5 is a graph for explaining the effects of the on-vehicle magnetic sensor according to the present embodiment and a vehicle position detecting device having the same. The horizontal axis represents the displacement (cm) of the vehicle 22 with respect to the magnetic marker 14, and the vertical axis represents the magnetic flux density (μT) of the horizontal magnetic field detected by the on-vehicle magnetic sensors 1 and 103. ing. The curve shown by the solid line represents the detection result of the on-vehicle magnetic sensor 1 according to the present embodiment, and the curve shown by the broken line represents the detection result of the conventional on-vehicle magnetic sensor 103. As shown in FIG.
Compared with the fact that the peak of the magnetic flux density detected by the conventional on-vehicle magnetic sensor 103 is about 60 μT, the on-vehicle magnetic sensor 1 of the present embodiment has a peak of the detected magnetic flux density of about 170 μT. It has three times the magnetic detection sensitivity.

Further, comparing the position detection range (the magnitude of the position displacement in a range in which the change in the magnetic flux density and the change in the position displacement maintain a substantially linear relationship), the position of the conventional on-vehicle magnetic sensor 103 is compared. The detection range R2 is 20 cm (± 10
cm), whereas the position detection range R1 of the on-vehicle magnetic sensor 1 of the present embodiment is 40 cm (± 20 cm).
Approximately twice as large as the conventional size can be obtained. Since it is within the position detection range that the amount of position displacement can be accurately calculated from the detected magnetic flux density, the on-vehicle magnetic sensor 1 of the present embodiment and the vehicle position detecting device 3 including the same can be compared with the related art. The position displacement amount of the vehicle can be detected in a range approximately twice as large.

The present invention is not limited to the above embodiment, but can be variously modified. For example, the magnetic member 4 according to the above-described embodiment is disposed adjacent to the magnetic detection unit 2 in the horizontal direction. However, the present invention is not limited to this.
The magnetic members 4 adjacent to each other in the vertical direction may be arranged. By doing so, the detection sensitivity of the strength of the vertical component of the magnetic field can be increased.

The magnetic member 4 between the adjacent magnetic detecting portions 2 of the on-vehicle magnetic sensor 1 according to the above-described embodiment is formed by a single columnar member having a length of, for example, 30 cm. The invention is not limited thereto, and a plurality of columnar magnetic bodies having a short length may be arranged.

Further, as described with reference to FIG. 1, the magnetic detection unit 2 of the above-described embodiment applies a pulse current (alternating current) in the longitudinal direction of the rod-shaped (band-shaped) magnetic body to change the external magnetic field. Although the corresponding electric signal is obtained from the detection winding, the present invention is not limited to this. For example, an excitation winding and a detection winding are wound around a magnetic core, an internal magnetic field is generated in the magnetic core by an alternating current flowing through the excitation winding, and an external magnetic field as a bias against the internal magnetic field is extracted as an electric signal from the detection winding. It is also possible to use a magnetic detection unit of the system.

[0032]

As described above, according to the present invention, the optimum magnetic field distribution can be obtained, and the vehicle position detection range of the on-vehicle magnetic sensor can be greatly expanded. Further, the positional displacement amount of the vehicle can be detected with high accuracy with a smaller number of sensors than in the conventional case.

[Brief description of the drawings]

FIG. 1 is a diagram showing a schematic configuration of a vehicle-mounted magnetic sensor according to an embodiment.

FIG. 2 is a diagram showing a schematic configuration of a vehicle position detecting device according to the present embodiment.

FIG. 3 is a diagram showing a schematic configuration of an example of an on-vehicle magnetic sensor and a vehicle position detecting device including the same according to the present embodiment.

FIG. 4 is a diagram illustrating a state where a magnetic field generated from a magnetic marker according to the present embodiment is viewed in a direction perpendicular to a road surface.

FIG. 5 is a graph illustrating the effects of the on-vehicle magnetic sensor and the vehicle position detecting device including the same according to the present embodiment.

FIG. 6 is a diagram showing a conventional on-vehicle magnetic sensor and a vehicle position detecting device including the same.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 On-vehicle magnetic sensor 2 Magnetic detection part 3 Vehicle position detection device 4 Magnetic member 6 Power supply 10x, 10y Detection element magnetic body 12x, 12y Detection winding 14 Magnetic marker 16 Vehicle position calculation part 18 Road surface 20 Signal line 22 Vehicle 24 Tire 26 Body 30 Magnetic field lines 32 Magnetic field strength detectable area

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 5H180 CC19 CC24 LL01 LL02 LL06 5H301 AA03 BB20 CC03 DD07 DD11 DD15 EE04 EE06 EE13 FF04 FF11 FF15 FF23 HH01 KK03 LL01 LL06 LL11

Claims (5)

[Claims] 1. A magnetic detector for detecting the strength of a magnetic field in a predetermined direction among magnetic fields generated from a magnetic marker installed on a road surface, and a magnetic member disposed adjacent to the magnetic detector. An in-vehicle magnetic sensor comprising: 2. The on-vehicle magnetic sensor according to claim 1, wherein the magnetic member is disposed adjacent to the magnetic detector along the one predetermined direction. Magnetic sensor. 3. The on-vehicle magnetic sensor according to claim 1, wherein the one direction is a horizontal direction parallel to the road surface and orthogonal to a traveling direction of the vehicle. Sensor. 4. The on-vehicle magnetic sensor according to claim 3, wherein the magnetic detector further detects a strength of a magnetic field in a direction perpendicular to the road surface. 5. A vehicle-mounted magnetic sensor for outputting a magnetic detection signal based on a magnetic field generated from a magnetic marker installed on a road surface, and calculating a position displacement of a vehicle based on the magnetic marker based on the magnetic detection signal. A vehicle position detecting device having a vehicle position calculating unit, wherein the vehicle-mounted magnetic sensor according to any one of claims 1 to 4 is used as the vehicle-mounted magnetic sensor. .