JPH10154295A - Road position detection system and in-vehicle device - Google Patents

Abstract

(57) [Problem] To provide an absolute position of a vehicle on a road when laying a magnetic nail in a traveling direction of a road and detecting a position of the vehicle by detecting the magnetic nail. A plurality of rows of magnetic nails are arranged in one lane.
The absolute position information on the road is included by encoding the code of the magnetic nail.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a road position detecting system in which a road marker is laid on a road and a vehicle position on the road is detected by detecting the road marker.

[0002]

2. Description of the Related Art The lane position, mileage, speed, acceleration, inter-vehicle distance, etc. of a vehicle are taken as information by communication between the vehicle and the road or between the vehicle and the vehicle. Automatic driving that warns the driver and issues commands such as brake operation, accelerator operation, steering operation, etc. to the driving device and ultimately eliminates congestion by running in platoon while maintaining a fixed inter-vehicle distance Systems are known.

In such an automatic driving system,
It is important to accurately recognize the mileage of the vehicle (the mileage from a predetermined reference point), which lane of the road the vehicle is traveling on, whether it is out of the lane, or the distance between the vehicle and the vehicle in front. is there. 2. Description of the Related Art Conventionally, there has been proposed a technology for determining a traveling position and an inter-vehicle distance by photographing a state of a road through an in-vehicle camera and recognizing the image (for example, see Japanese Patent Application Laid-Open No. 7-77431). Is required, and the determination algorithm becomes complicated. Therefore, a device that can easily recognize the traveling position has been desired.

Also, a technology has been realized in which a laser radar is mounted on a vehicle, a pulse-like laser beam is emitted forward, and the propagation time of reflected light from a reflector of a preceding vehicle is measured to detect an inter-vehicle distance. (Aono, Maho, Starboard "Trends in Driving Environment Recognition Technology" Automotive Technology Vol.48, No.9, 5th
4-59, 1994), in addition to reflections from vehicles traveling ahead, reflections also occur from vehicles traveling in the opposite lane, guardrails, road side walls, etc., and these obstacles are also recognized as vehicles ahead. The disadvantage is that it gives a false warning.

Therefore, as shown in FIG. 6, a magnetic nail is embedded in the road surface along the direction of the road, and this magnetic nail is detected by a magnetic sensor provided on the vehicle body.
A system for detecting the mileage of a vehicle and the lateral displacement of a vehicle body has been proposed (US Pat. No. 5,34, September 13, 1994).
7,456, May 14, 1992 PCT International Publication WO 92/08176
No.).

There has also been proposed a system in which a pair of conductors is embedded in a road and a signal is transmitted to and received from a vehicle using electromagnetic induction coupling. Further, there has been proposed a system in which a magnetic tape having alternating polarities is attached to a road, and a signal is exchanged with a vehicle using a magnetic field generated by the magnetic tape. Equipment provided on the road for detecting the running position of the vehicle, such as magnetic nails, guide lines, magnetic tapes, etc., will be collectively referred to as "road markers".

[0007]

As described above, when a road marker is used, a vehicle equipped with an automatic driving system needs to know the traveling position of the vehicle by accurately detecting the road marker. However, in order to detect the road marker and to know the traveling position of the vehicle, it is conceivable to specify a reference road marker and to know the traveling position of the vehicle based on information on the number of the road marker.

Here, it is conceivable that the road marker is specified, for example, as follows. Before entering the highway, the vehicle receives information from communication means, for example a beacon, that it is about to enter the highway. If a navigation device is installed, the information may be received from the navigation device. A magnetic nail is embedded between the entrance and the exit of the highway. When a vehicle enters the highway from the entrance, a specific code (for example, S pole) appears first, and then both codes have a predetermined code content. Appears according to. The point at which the first specific code is detected for the first time is defined as a starting point. Thereafter, the relative coordinates can be known by counting the magnetic nails.

In the above-described method, when a plurality of vehicles traveling back and forth travel in platoon by exchanging traveling position information, if any of the vehicles has a wrong road marker count as a reference, the traveling An error occurs in the position information, which makes it impossible to realize safe platooning. In some cases,
It can lead to a major accident. Therefore, when exchanging the information of the traveling position between a plurality of vehicles traveling back and forth, a technology for significantly improving the reliability of the information is required.

Accordingly, an object of the present invention is to realize a reliable road position detection system that can accurately determine the position of a vehicle by detecting a road marker. Conventionally, the sign of the road marker is N
Although only two kinds of codes, such as poles and S poles, are used, the present invention aims to realize a road position detection system capable of transmitting a large amount of information by using a large number of codes. .

[0011]

A road position detecting system according to the present invention is capable of detecting an absolute position on a road by arranging a plurality of columns of road markers in one lane and encoding the codes of the road markers. It was done. According to the configuration described above, the vehicle can detect the plurality of road markers and read the codes thereof to know the absolute position on the road.

It is preferable that the arrangement interval of the road markers is set to a length corresponding to the speed limit of the road (claim 2). The “arrangement interval” specifically refers to a pitch at which magnetic nails are arranged along the direction of a road. In this case, the pitch should be longer on the highway,
On ordinary roads, the pitch will be shorter. In light of the fact that it is necessary to increase the distance between vehicles on a highway, and the distance between vehicles on an ordinary road can be shortened, the difference between the code read by the vehicle and the code read by the vehicle ahead ( The inter-vehicle distance can be adjusted based only on the distance between the cords).

[0013] The arrangement interval of the road markers may be set to a different length for each lane of the road. In this case, the vehicle knows the pitch,
It is possible to know which lane the vehicle is traveling in (traveling lane, passing lane, etc.). The vehicle-mounted device according to the present invention is applied to the road position detection system according to claim 1, and a road marker detection unit that detects a plurality of arranged road markers;
An absolute position detecting means for decoding a code based on the detected sign of the road marker and detecting an absolute position of the own vehicle on the road is provided (claim 4).

With this vehicle-mounted device, the absolute position of the vehicle on the road can be detected by the road position detection system. It is preferable that the on-vehicle device of the present invention further includes an inter-vehicle distance adjusting unit that transmits the absolute position information and receives the absolute position information from another vehicle to adjust the inter-vehicle distance. .

This is because the inter-vehicle distance can be accurately adjusted based on the absolute position of the vehicle on the road. In the road position detection system of the present invention, a road marker code is configured by installing road markers having three or more different signal radiation intensities. The expression "the signal radiation intensities differ by three or more types" means that in the case of a magnetic nail or a magnetic tape, three or more types of codes are realized by changing the direction and intensity of the magnetization. In the case of a colored tape, it means that three or more codes are realized by changing colors.

For example, if the magnetization strength of the N pole is set in two different strengths and the magnetization strength of the S pole is set in two different strengths, a total of four signs can be obtained. If N consecutive road markers embedded in the traveling direction are regarded as one unit, 4 ^N codes can be obtained based on this. Further, when M rows of road markers are arranged in one lane as described in claim 1, 4 ^MN kinds of codes can be obtained.

Since a plurality of codes can be obtained as described above, the content of the code of the road marker may be multiplexed by dividing it in terms of distance. In this way, a plurality of types of information, for example, absolute position information on the road, road shape information (there is a curve ahead, etc.), and traffic regulation information can be set at the same location on the road.

[0018]

Embodiments of the present invention will be described below in detail with reference to the accompanying drawings. -Embodiment 1- FIG. 1 shows three magnetic nails in the middle of a lane as road markers.
It is the figure which looked at the road embedded in the row from the low sky.

FIG. 2 is a plan view showing an arrangement of magnetic nails on a road. In the bottom row, the N pole and the S pole alternately have a predetermined pitch a as a cycle (−1, 1, −1, 1,..., Where 1 is the N pole and −1 is the S pole). Are arranged. In the middle row, the magnetic nails are arranged at every predetermined pitch a, but the sign change cycle of the N pole and the S pole is doubled. In the top row, the magnetic nail has a predetermined pitch a
However, the period of the sign change between the north pole and the south pole is quadrupled.

The code forming the lowermost column is regarded as the lower digit, the code constituting the middle column is regarded as the middle digit, and the code constituting the uppermost column is regarded as the upper digit. , A code combination (hereinafter, referred to as a “magnetic nail code” or a “code”) is formed by the upper, middle, and lower digits. For example, in FIG. 2, along the traveling direction, (1,1,1), (1,1, -1),
The code (1, -1,1), ‥‥ has been created.

The value of the pitch a and the meaning of the code are determined in advance on the road side and the vehicle-mounted device side.
You know. The repetition unit of this code depends on the number of digits. In the example of FIG. 2, since the code is a three-digit code, the repeating unit is eight times the pitch a (represented by A in FIG. 2).

In the present invention, the meaning of "detecting an absolute position on a road" means that it is possible to detect the position of the vehicle in this section of length A. Therefore, the inter-vehicle distance cannot be detected between vehicles separated by a distance A or more (an uncertainty of an integral multiple of A remains even if an attempt is made to detect the inter-vehicle distance), but this disadvantage can be tolerated by properly setting the distance A. . This is because it is not necessary to detect an inter-vehicle distance between vehicles that are too far apart.

From the above considerations, the distance A is determined. Distance A
In order to reduce the position detection error under the condition that is constant, the pitch a may be shortened. To do that, we need to increase the number of digits. Increasing the number of digits means increasing the number of rows of magnetic nails. Since the width of the vehicle is constant depending on the type of vehicle, if the number of magnetic nail rows is to be increased, the interval between the magnetic nail rows must be reduced. However, if the distance between the magnetic nail rows is excessively reduced, the magnetic field distributions overlap, and the sign of each digit cannot be determined. Therefore, shortening the pitch a is limited by the number of magnetic nail rows.

Therefore, in order to improve the accuracy of position detection, it is considered that a process of interpolating with an estimated position calculated by autonomous navigation is effective, as will be described later. FIG. 3 is a block diagram illustrating the in-vehicle device. The in-vehicle device is configured to calculate an estimated position by autonomous navigation based on a traveling distance detection unit 11, a traveling direction detection unit 12, a traveling distance detection signal output from each of the detection units 11, 12, and a traveling direction detection signal. And a magnetic field detector 13 for detecting a magnetic field of a magnetic nail embedded in a road.
A detecting element specifying unit 13d for specifying which magnetic resistance element of the magnetic field detecting unit 13 detects the magnetic field of the magnetic nail embedded along the road, and a waveform shaping unit 13a;
13b, 13c, a code decoding unit 19 for decoding codes of magnetic nails and outputting an absolute position signal indicating an absolute position on the road, and an estimated position detected by the position estimating unit 14 is used as the absolute position signal. Position determination unit 16 to be reset
And a transmission / reception unit 20 that transmits an absolute position signal of the vehicle detected by microwaves or millimeter waves to another vehicle and receives an absolute position signal from the other vehicle.

More specifically, a wheel speed sensor, for example, can be used as the traveling distance detector 11. This wheel speed sensor has a magnetic sensor that detects the rotation of the wheel, obtains the number of rotations of the wheel by counting the number of waves of a sine wave signal output from the magnetic sensor with a counter, and counts the data output from the counter. for,
The traveling distance per detection cycle Δt (cycle number is represented by n) is detected by multiplying a predetermined constant indicating the outer circumference of the wheel by a multiplier. In addition, a conventionally known configuration such as a vehicle speed sensor configured to detect a traveling distance by detecting a traveling speed of a vehicle based on a Doppler shift and integrating the detected traveling speed may be used.

A gyro that outputs rotation angle data per unit time can be used as the traveling direction detector 12, for example. Examples of this gyro include a vibrating gyro,
An optical fiber gyro and a differential wheel speed sensor can be used. Further, a geomagnetic sensor for detecting a horizontal component of the geomagnetism can be used, and a combination of the geomagnetic sensor and the gyro can be employed.

The magnetic field detector 13 is provided, for example, at the bottom of a bumper. As shown in FIG. 4, a plurality of magnetoresistive elements 1 are arranged on an elongated rubber-like permanent magnet 3, and an output voltage is taken out from each. It has a circuit configuration. The magnetoresistive element 1 is an element whose electric resistance changes when a magnetic field is applied, and semiconductor materials such as InSb, GaAs, and InAs are often used. In the present embodiment, an element in which an InSb thin film is formed on a substrate by a vacuum deposition method is used (for example, a “magnetic resistance element TMS-D series” manufactured by Toyocom Toyo Communication Equipment Co., Ltd.). Alternatively, a bulk (single crystal) type magnetoresistive element may be used.

The detecting element specifying unit 13d specifies which magnetic resistance element of the magnetic field detecting unit 13 detects the magnetic field of the magnetic nail embedded along the road. This identification is performed by sequentially scanning the magnetoresistive elements and identifying the magnetoresistive element when an output voltage equal to or higher than the threshold is detected. If the same number of magnetoresistive elements as the number of magnetic nail columns are specified, the sign (±) of the output voltage is determined.

The code decoding section 19 can read the code of the magnetic nail based on the sign of the output voltage.
Then, based on the absolute position information included in the read code and the pitch a, the absolute positions 0, 1a, and 2 on the road are determined.
a, 3a, ‥‥ are calculated. Since the number of magnetoresistive elements that output an output voltage equal to or higher than the threshold value should be equal to the number of magnetic nail columns (3), if the number of magnetic nail columns is insufficient or excessive, an abnormality is detected in detection. The output voltage at that time is invalidated assuming that there is something.

The position estimating unit 14 takes in the distance data ΔD _n output from the traveling distance detecting unit 11 and adds the component ΔD _n to the previous estimated position data D _n−1 to obtain the current estimated value. detecting the position D _n. Note that the initial position D ₀ of the estimated position needs to be determined, and the initial position D ₀ is calculated every time the absolute position signal is received from the code decoding unit 19 by the coordinates ma (m) indicated by the absolute position signal.
Is any of 0, 1, 2, 3,...) As the initial position D ₀ .

If the vehicle deviates from the lane beyond the installation length of the magnetoresistive element, it becomes impossible to detect the number of magnetic fields corresponding to the number of rows of the magnetic nails.
It will continue position detection based only on the estimated position D _n of the vehicle output from. Transceiver unit 20 transmits a signal corresponding to the estimated position D _n of the detected vehicle to another vehicle, receives a signal indicating the estimated position of the other vehicles. At this time, information such as a vehicle code number, speed, and acceleration is also exchanged. Then, the distance between the vehicles is calculated, and an automatic brake operation, an automatic accelerator operation, and the like of the own vehicle are performed so that the vehicle can always travel at a constant interval.

One of the important things at this time is to communicate only with the vehicles existing in the section of the length A. This is because communication with a vehicle outside the section having the length A is not preferable because the inter-vehicle distance has an uncertainty of an integral multiple of A as described above. Actually, the transmission power of the transmission / reception unit 20 is reduced so that reception cannot be performed at a sufficient level farther than the section of the length A.

While the first embodiment of the present invention has been described with reference to the drawings, the embodiment of the present invention is not limited to the above. In the above embodiment, the number of rows of the magnetic nail is three, but the number is not limited to three as long as it is a plurality of rows. Further, when there are a plurality of lanes in one direction, the pitch a may be changed for each lane when the magnetic nail is laid, and the running lane may be recognized by detecting the pitch a with the vehicle-mounted device. Thereby, platooning control in the same lane can be performed.

Although a magnetic nail embedded in a road is used as a road marker, it is not a magnetic nail, but a magnetic nail shown in FIG.
A magnetic tape as shown in FIG. The magnetic tape is a rubber tape filled with a ferromagnetic powder.
The pole (1) and the south pole (-1) are alternately arranged. Further, a light emitting element may be embedded in the road and the emission color thereof may be identified by the vehicle, or a reflector may be embedded in the road and the reflection color may be identified by the vehicle. Second Embodiment Next, a second embodiment of the present invention will be described.

FIG. 7 is a plan view of a road on which a magnetic tape is provided as a road marker. 3.5m road width with magnetic tape
Three roads, the distance between magnetic tapes is about 50c
m. In this magnetic tape, the N pole and the S pole do not always appear alternately, but have two types of N pole magnetization strength, two S pole magnetization strengths, and have 0 magnetization. It has a total of five codes including the case. The N maximum is 2, the N minimum is 1, the S maximum is -2, and the S minimum is -1, and three consecutive codes are defined as one unit (frame). Based on this, to form a 5 ^three types of code. The length of one frame is about 1 m.

Since this magnetic tape is embedded in three rows, it is possible to obtain (5 ³ ) ³ = approximately 1.95 million codes. A device for error detection (for example, a parity check code) may be added to this code. One frame of the code is divided into distances and multiplexed to include a plurality of types of invariant information, for example, absolute position information on a road, road shape information, and traffic regulation information. Examples of road shape information include the direction of curvature and radius of curvature if there is a curve ahead, the distinction of up-down and slope if there is a slope, and the like. Examples of traffic regulation information include information such as lane identification, intersection identification, lane count reduction, regulation speed change, and the like. As a multiplexing method, it is conceivable that the first code of one frame is used as a code for initialization, the next code is assigned to a certain type of information, and the next code is assigned to another type of information. .

The configuration of the magnetic field detecting section of the vehicle-mounted device is almost the same as that used in the first embodiment, except that a threshold value is provided for the detected magnetic field, and the N pole strong, N pole weak, S pole strong, S pole weak. Can be detected separately from each other. Therefore, if the in-vehicle device detects, decodes, and separates the code, various embedded information can be obtained at the same time.

The present invention is not limited to the second embodiment. For example, instead of the magnetic tape of the second embodiment, magnetic nails having different degrees of magnetization may be used, and three types of light-emitting elements having different colors may be embedded in a road, and the emission color may be identified in a vehicle. .

[0039]

As described above, according to the road position detecting system according to the first aspect or the vehicle-mounted device according to the fourth aspect, by detecting a plurality of road markers and reading their codes, the absolute position on the road is detected. Therefore, by exchanging the traveling position information between a plurality of vehicles traveling back and forth, an accurate inter-vehicle distance can be obtained, and traveling safety can be ensured.

According to the road position detecting system of the present invention, a large amount of information can be transmitted by using a large number of codes of the road marker.

[Brief description of the drawings]

FIG. 1 is a view of a road in which magnetic nails are driven in three rows in the middle of a lane as viewed from a low altitude as a road marker according to the present invention.

FIG. 2 is a plan view showing an arrangement of magnetic nails on a road.

FIG. 3 is a block diagram showing an in-vehicle device.

FIG. 4 is a diagram showing a circuit configuration in which a plurality of magnetoresistive elements are arranged on an elongated rubber-like permanent magnet, and an output voltage is taken out from each of them.

FIG. 5 is a plan view showing an arrangement of magnetic tapes on a road.

FIG. 6 is a view of a road in which magnetic nails are driven in a row in the middle of a lane, as viewed from a low altitude.

FIG. 7 is a plan view of a road on which magnetic tapes are stretched in three rows as road markers.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 magnetoresistive element 2 resistive element 3 permanent magnet 5 terrestrial data transmission device 11 running distance detecting unit 12 running direction detecting unit 13 magnetic field detecting units 13a, 13b, 13c waveform shaping unit 13d detecting element specifying unit 14 position estimating unit 16 position determining unit 19 Code decoding unit

Claims (7)

[Claims] 1. A road position detection system for laying road markers in a traveling direction of a road and detecting a position of the vehicle by detecting the road markers, wherein a plurality of columns of road markers are arranged in one lane. A road position detection system characterized in that an absolute position on a road can be detected by coding a sign of a road marker. 2. The road position detecting system according to claim 1, wherein the arrangement interval of the road markers is set to a length corresponding to a speed limit of the road. 3. The road position detection system according to claim 1, wherein the arrangement intervals of the road markers are set to different lengths for each lane of the road. 4. A road marker detecting means which is applied to the road position detecting system according to claim 1 and detects a plurality of arranged road markers, and decodes a code on the basis of a sign of the detected road marker. An on-vehicle apparatus, comprising: an absolute position detecting means for detecting an absolute position of a vehicle on a road. 5. The in-vehicle device according to claim 4, further comprising an inter-vehicle distance adjusting means for transmitting the absolute position information and receiving the absolute position information from another vehicle to adjust the inter-vehicle distance. . 6. A road position detecting system for detecting a position of a vehicle by laying a road marker in a traveling direction of a road and detecting the road marker, wherein a road marker having three or more different signal radiation intensities is detected. A road position detection system, wherein a road marker code is configured by being installed. 7. The road position detecting system according to claim 6, wherein the contents of the code of the road marker are divided in distance and multiplexed.