JP2002365009A - Vehicle position detector - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a vehicle position detector capable of exactly detecting position with a simple constitution regardless of the effects of magnetic flux variation due to vehicle height variation and the like. SOLUTION: With a position detector detecting vehicle position for a magnetism generation means by detecting the magnetism field generated by the magnetism generator placed on the road side, magnetic sensors 24a to 24c having different detection threshold are lined up in the front and back direction to form a pair of magnetic detection means 20. By lining up a plurality of them in the left and right direction and based on their detection results, the position relation between the magnetism generation means and the vehicle is judged with a judging means.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a vehicle mounted on a vehicle,
The present invention relates to a position detection device for a vehicle that detects a position of a host vehicle by detecting a magnetic field generated by a magnetic generation unit provided on a road surface.

[0002]

2. Description of the Related Art A magnetic field generating means such as a magnetic marker or a magnetic nail is embedded in a track on which a vehicle travels, and a magnetic field sensor installed in the vehicle detects a magnetic field generated by the magnetic field generating means. 2. Description of the Related Art A position detecting means for detecting a position of a host vehicle with respect to a running path by detecting a position with respect to a generating means is known, and a technique disclosed in Japanese Patent Application Laid-Open No. 11-94566 is an example of such a technique.

In this technology, a plurality of pairs of a horizontal sensor for detecting a horizontal magnetic field and a vertical sensor for detecting a vertical magnetic field are arranged in the width direction of a vehicle, and a magnetic marker or the like embedded in a road is provided. A magnetic field generated from the vehicle is detected, and output signals of a pair of sensors on both sides of the magnetic field marker or the like are mapped to detect a deviation of the vehicle from the magnetic marker or the like.

[0004]

However, in the case of a vehicle having a function of adjusting the loaded weight or a vehicle height, if the distance between a sensor for detecting a magnetic field on the vehicle side and a magnetic marker or the like changes due to the adjustment, the change is detected. Since the magnetic field strength and its direction vector change, in order to accurately detect the horizontal distance from a magnetic marker or the like by the above technique, map processing according to the vertical distance becomes expensive and complicated arithmetic processing is required. As a result, the processing device becomes complicated and expensive.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a vehicle position detecting device capable of performing accurate position detection with a simple configuration irrespective of the influence of magnetic flux fluctuation due to a change in vehicle height or the like.

[0006]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, a vehicle position detecting device according to the present invention detects a magnetic field generated by a magnetic field generating means provided on a road surface side to detect a magnetic field generated by the magnetic field generating means. In a position detecting device for detecting a vehicle position, a plurality of magnetic detecting means arranged in a lateral direction of the vehicle, each of which can detect a magnetic field level and output a signal according to a different detection threshold, A determination unit configured to determine a positional relationship between the magnetism generation unit and the vehicle based on detection results of the plurality of magnetism detection units.

In the position detecting device according to the present invention, when the vehicle height is low and the magnetic field level from a magnetic marker or the like to be detected is large, detection is performed based on the output signal when the detection threshold of the magnetic detecting means is large. When the vehicle height is high and the magnetic field level from the detected magnetic marker or the like is small, detection is performed based on the output signal when the detection threshold of the magnetic detection means is small. In this manner, by making the detection threshold of the magnetic detection means different according to the magnetic field level emitted from the magnetic marker or the like, position detection can be performed with a simple configuration without performing complicated map processing or the like.

Each of the magnetic detecting means is composed of (1) a plurality of magnetic sensors having different sensitivities, or (2) a magnetic sensor for generating an output signal corresponding to a magnetic field level, and a plurality of magnetic sensors having different comparison levels. It is preferable to be configured in combination with a comparator. With this configuration, it is possible to generate output signals corresponding to different detection thresholds from each of the magnetic detection units.

In the plurality of magnetic detection means, when a magnetic field is detected at a threshold level of an arbitrary sensitivity, it is preferable to permit the detection of the magnetic field at a threshold level of a sensitivity lower by one step. By doing so, it is not necessary to process the outputs of all the detecting means, so that the processing of the output signal is simplified and the configuration of the processing circuit can be simplified.

[0010]

Preferred embodiments of the present invention will be described below in detail with reference to the accompanying drawings. In order to facilitate understanding of the description, the same constituent elements are denoted by the same reference numerals as much as possible in each drawing, and redundant description will be omitted.

FIG. 1 is a schematic diagram showing a preferred embodiment of a vehicle position detecting device according to the present invention, and FIG. 2 is a diagram for explaining the structure of each magnetic detecting means.

As shown in FIG. 1, the vehicle position detecting device 2 of the present embodiment includes a plurality of position detecting means 20 disposed at equal intervals in the vehicle body lateral direction on the back side of the front bumper 11 of the vehicle 1. And a determination ECU 21. These position detecting means 20 detect a magnetic field generated by a magnetic nail 31 embedded at a predetermined interval along the center of the lane 30 on the road surface 3.

[0013] As shown in FIG.
Are three magnetic sensors 24a, 2
4b and 24c are arranged in the front-rear direction of the vehicle. Specifically, the most sensitive magnetic sensor 24a is located on the front side of the vehicle 1 and the least sensitive magnetic sensor 24a is located on the rear side.
c, a medium-sensitivity magnetic sensor 24b is arranged therebetween. These magnetic sensors 24a to 24c are on / off type sensors that output a predetermined signal when the vertical magnetic field exceeds a set threshold value.

As shown in FIG. 3, a temporal output change of each of the magnetic sensors 24 when the magnetic detecting means 20 arranged in the lateral direction passes over the magnetic nail 31 (time when the ON signal is output). Is imaged as a two-dimensional image, as shown in FIG. That is, a measurement image by the group of high-sensitivity magnetic sensors 24a (see FIG. 4A) and a measurement image by the group of medium-sensitivity magnetic sensors 24b (FIG.
(B)), the number of sensors capable of detecting a magnetic field in the order of a measurement image (see FIG. 4 (c)) by the low-sensitivity magnetic sensor group 24c and the detection time are both reduced, and the ON signal position on the image is reduced. , The image representing the time becomes smaller.

As is apparent from the figure, in the measurement using the high-sensitivity magnetic sensors 24a, it is difficult to accurately determine the center position of the ON image when the magnetic field strength is large. On the other hand, in the measurement by the group of low-sensitivity magnetic sensors 24c, an output may not be obtained when the magnetic field strength is small.

Normally, the height of the bumper portion of the vehicle from the road surface changes depending on the mounting weight of the vehicle, vertical movement, and the like. Further, there is a possibility that the magnetic field distribution itself formed around the magnetic nail varies due to the variation of the magnetic field itself emitted from the magnetic nail and the influence of the magnetic field due to the surrounding objects. As a result, in some cases, a single-sensitivity magnetic sensor cannot obtain an output or the output is too strong, so that accurate position measurement cannot be performed.

In the vehicle position detecting means according to the present invention, accurate measurement can be performed irrespective of a change in magnetic field intensity around the magnetic sensor by using a combination of magnetic sensors having different sensitivities. Hereinafter, the specific operation will be described with reference to FIG. FIG. 5 is a flowchart illustrating the detection process.

This processing is performed by the determination ECU 21 shown in FIG.
And is repeatedly executed once for each of the magnetic nails 31. The output values of the magnetic sensors 24a, 24b, 24c are assumed to be taken into the determination ECU 21 at predetermined intervals.

In step S1, the start and end positions of nail detection and the detection map are first initialized. In step S2, first, the high-sensitivity magnetic sensor 24a is selected and set as a sensor.

In step S3, the sensing result of the selected sensor (whether the value of each sensor is ON or OFF) is read. In step S4, if there is at least one sensor that outputs an ON signal among the sensing results, it is determined that there is detection, and if all sensors are OFF signals, it is determined that there is no detection.

If it is determined that there is a detection, the process proceeds to step S5 to determine whether the start position has been set. If the start position has not been set, the current position (may be a time step number or time) is set as the start position in step S15, and step S12 is performed.
Then, the sensing result is written into the detection map together with the current position information (for example, time step number or time).

On the other hand, if the start position has been set in step S5, the process proceeds to step S6 to determine whether or not there is a sensor next to the set sensor (a sensor group having a lower sensitivity). I do. When it is determined that there is a next sensitivity sensor (when the current sensor setting is the high sensitivity sensor 24a or the middle sensitivity sensor 24b), the process proceeds to step S7, and the next sensitivity sensor is set as the sensor. Then, the sensing result of the sensitivity sensor set in step S8 is read.

In step S9, as in step S4, if there is at least one sensor that outputs an ON signal among the sensing results, it is determined that there is detection, and if all sensors are OFF signals, it is determined that there is no detection. When it is determined that there is no detection, the process proceeds to step S16 to restore the previous sensor (a group of sensors with higher sensitivity) to the set sensor, and proceeds to step S12 to determine the sensing result of the previous sensor. It is additionally written to the detection map together with the position information.

If it is determined in step S9 that there is a detection, the process starts to lower the sensitivity. Specifically, after resetting the detection map in step S10 and resetting the start position in step S11, the process proceeds to step S12,
Write the sensing result of the currently selected sensor to the detection map.

After completion of step S12, in any case, the process returns to step S3 to continue the processing of the next sensing result.

If it is determined in step S4 that there is no detection, the process proceeds to step S20 to determine whether the start position has been set. If the start position has not been set yet, it is determined that the magnetic nail has not been detected, and the process returns to step S3 and continues. On the other hand, if the start position has been set, it is determined that the detection of the magnetic nail has been completed, and the process proceeds to step S21 to set the current position as the end position. Then, the process proceeds to step S22, and the vehicle position is calculated from the information written in the detection map.

Here, in the detection map, among the magnetic sensor groups, the output result of the least sensitive sensor group in which a magnetic field is detected, that is, at least one sensor outputs an ON signal at least once, is recorded. Will have been. From the values of the detection map thus recorded, the position of the magnetic nail can be detected by detecting the center position of the black portion in FIG. 4, and the position of the vehicle with respect to the magnetic nail can be detected based on the position. Then, in step S23, the vehicle position thus calculated is output, and the process ends.

Next, with reference to FIG. 6, how the above-described detection processing is actually performed will be described. 6A and 6B are diagrams showing a temporal change of the magnetic flux density at the predetermined position of the magnetic detecting means 20. FIG. 6A shows a case where the magnetic flux density is at a medium level, and FIG. In the case of FIG.
(C) shows a case where the magnetic flux density is at a low level.

Here, each of the magnetic sensors 24a, 24b, 2
The detection threshold levels of 4c are the magnetic flux densities B ₁ , B ₂ , B
It is assumed that it is set to ₃ .

First, when the magnetic flux density is at a medium level, as shown in FIG.
If it changes as shown, the time t₀₁High sensitivity at the time of
A start position using the sensor 24a is set. Soshi
And time t₀₂At the time of opening using the medium sensitivity sensor 24b.
The starting position is set and the time t ₀₃At this time
The ending position using the sub 24b is set. This result
As a result, in this case, the position detection using the medium sensitivity sensor 24b is performed.
Exit will take place.

Next, the magnetic flux density may change as shown in FIG. 6 at a high level (b), the starting position using a high-sensitivity sensor 24a at time t ₁₁ is set. Then, the start position using the mid sensor 24b at time t ₁₂ is set. Furthermore, time, start position using the low-sensitivity sensor 24c at the time of t ₁₃ is set.
Then, the end position using the low-sensitivity sensor 24c at time t ₁₄ is set. As a result, in this case, position detection using the low-sensitivity sensor 24c is performed.

Further, the magnetic flux density may change as shown in FIG. 6 at a low level (c), the starting position using a high-sensitivity sensor 24a at time t ₂₁ is set. The other magnetic sensor 24b, the end position using the high-sensitivity sensor 24a at the left time t ₂₂ does not lead to a set of start position using 24c is set. As a result, in this case, position detection using the high-sensitivity sensor 24a is performed.

As described above, even when the magnetic flux density in the magnetic sensor portion changes, by switching between sensors having different sensitivities in accordance with the magnetic flux density, detection is prevented and the time during which the signal is turned on is prevented. Can be shortened, so that accurate magnetic field detection can be performed without performing magnetic field detection in an excessively wide range.

FIG. 7 is a diagram showing another embodiment of the magnetic detecting means according to the present invention. Magnetic detection means 2 of this embodiment
0a is composed of a magnetic sensor 25 that outputs a power value according to the magnetic density and three comparators 26a to 26c. The output signal of the magnetic sensor 25 is input to the negative input terminals of the comparators 26a to 26c, Different constant voltage values V _{0 to} V ₂ are input to the input terminals. Thus, the comparator 26a~26c will be the voltage value is output when the output voltage value of the magnetic sensor 25 exceeds the constant voltage value V ₀ ~V ₂ respectively. Therefore, the same operation as the above-described embodiment can be realized.

In the above description, an embodiment in which three types of magnetic sensors having different sensitivities are combined has been described.
Four or more or two types of magnetic sensors having different sensitivities may be combined.

According to the present invention, since the sensitivity can be changed almost in real time, not only a change in the loaded weight of the vehicle, but also a change in the position of the magnetic sensor due to pitching and the like, and a change in the magnetic field itself due to deterioration of the magnetic nail, Accurate measurement can be performed in response to deterioration of the detected magnetic flux intensity due to sensor contamination, road surface foreign matter, magnetization of vehicle components, and the like.

[0037]

As described above, according to the present invention, the measurement is performed by changing the detection threshold value of the magnetic detection means according to the magnetic field intensity emitted from the magnetic nail, so that the magnetic detection means installed in the vehicle is provided. It is possible to reliably detect the position of the magnetic nail irrespective of the position change of the magnetic nail and the difference in the magnetic flux intensity generated by the magnetic nail. Further, since the configuration is simple, the maintenance is easy and the arithmetic circuit can be simplified.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram showing an embodiment of a vehicle position detection device according to the present invention.

FIG. 2 is a diagram illustrating a configuration in each magnetic detection unit.

FIG. 3 is a diagram illustrating an arrangement relationship between a magnetic detection unit of the apparatus of FIG. 1 and a magnetic nail installed on a road.

FIG. 4 is a two-dimensional image diagram of a detection result in the device of FIG. 1;

FIG. 5 is a flowchart of a detection process in the device of FIG. 1;

FIG. 6 is a diagram illustrating an example of a temporal change of a magnetic flux density at a sensor group position.

FIG. 7 is a block diagram showing another magnetic detection unit applicable to the vehicle position detection device according to the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... vehicle, 3 ... road surface, 11 ... front bumper, 20 ... position detection means, 21 ... determination ECU, 24, 25 ... magnetic sensor,
26: comparator, 30: lane, 31: magnetic nail.

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 2F063 AA02 BA11 CA08 DA01 DB04 DC08 DD04 GA52 KA06 LA09 NA06 5H180 AA01 CC19 FF05 LL01 LL02 5H301 AA01 BB20 CC03 CC06 DD07 DD11 EE06 EE12 FF04 FF11 FF15 FF23 GG11 H06

Claims (4)

[Claims] 1. A position detecting device for detecting a magnetic field generated by a magnetic generating means provided on a road surface to detect a vehicle position with respect to the magnetic generating means, wherein the position detecting apparatus is disposed in a lateral direction of the vehicle. A plurality of magnetic detectors each capable of detecting a magnetic field level and outputting a signal in accordance with a different detection threshold; and a communication between the magnetic generator and the vehicle based on a detection result of the plurality of magnetic detectors for each threshold. A position detecting device for a vehicle, comprising: determining means for determining a positional relationship; 2. The vehicle position detecting device according to claim 1, wherein each of said magnetic detecting means is configured by combining a plurality of magnetic sensors having different sensitivities. 3. The vehicle position detecting device according to claim 1, wherein each of said magnetic detecting means is configured by combining a magnetic sensor for outputting an output signal corresponding to a magnetic field level, and a plurality of comparators having different comparison levels. apparatus. 4. The apparatus according to claim 1, wherein when a magnetic field is detected at a threshold level of an arbitrary sensitivity in said plurality of magnetic detection means, magnetic field detection at a threshold level of a sensitivity lower by one step is permitted. 4. The vehicle position detection device according to any one of 3.