JPH10160485A - Road position detecting system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain absolute-position information on a road with least missing with regard to a road position detecting system for transferring multiplexed information, by using many codes as road markers. SOLUTION: While encoding the code of road marker, the code is divided in terms of distance to provide a multiplexed information containing an absolute- position information on a road, and road marker sensors for detecting road markers are mounted on a car with a specified distance D. The car is provided with code decoder parts 18A and 18B which, based on the road marker code detected with each road marker sensor, separately decode the code, and a position deciding part 17 which, assumes the absolute position on road detected with the code decoder parts 18A and 18B as car's position when one of code decoder parts 18A and 18B detects an absolute position of a car on a road.

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]

In the case where the road markers are used as described above, only one row of the road markers has been conventionally used. However, a plurality of rows of the road markers are arranged, and the codes of the respective rows are arranged. If a code is created by the combination, the amount of information to be included in the road marker can be significantly increased.

Further, N consecutive codes are defined as one unit (frame), and this one frame is divided and multiplexed by distance, and 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 allocated to a certain type of information, and the next code is allocated to another type of information. .

When information is multiplexed in this way, while it is receiving one type of information, it cannot normally receive another type of information. There are few problems with information that does not change frequently, such as road shape information and traffic regulation information, but information that changes every moment, such as absolute position information on the road, is acquired with as little omission as possible Is preferred.

Normally, it is conceivable that autonomous navigation is performed by an on-vehicle device, and the omission of absolute position information on a road is interpolated with the position information obtained by the autonomous navigation. Cannot be relied solely on autonomous navigation because of the errors involved (in autonomous driving, the order of allowable errors is much more severe than in map matching).

Therefore, according to the present invention, in a road position detecting system that transmits a large amount of information by using a large number of codes as road markers, it is possible to obtain absolute position information on a road with as little omission as possible. It is intended to realize a road position detection system.

[0012]

A road position detecting system according to the present invention encodes a sign of a road marker,
This code is divided into distances, multiplexed information including absolute position information on the road is added, and a road marker sensor for detecting a road marker is attached to the vehicle at a predetermined distance D, and the vehicle-mounted device is mounted on the vehicle. Based on the sign of the road marker detected by each road marker sensor, code decoding means for decoding codes independently of each other, and either one of the code decoding means detects the absolute position of the vehicle on the road. In this case, there is provided a position determining unit that sets the absolute position on the road detected by the code decoding unit as the position of the vehicle.

According to the above configuration, the road marker contains other information in addition to the absolute position information on the road.
A period occurs in which the in-vehicle device cannot detect the absolute position information on the road. Therefore, the road marker sensor is attached to the vehicle at a predetermined distance D, and the codes are decoded independently of each other. When one of the code decoding means detects the absolute position of the own vehicle on the road, The absolute position on the road detected by the code decoding means is defined as the position of the vehicle.

Thus, the number of times of detecting the absolute position information on the road can be doubled in principle, so that the accuracy of the absolute position information on the road increases. When detecting the absolute position on the road, any of the code decoding means needs to correct and detect the road marker sensor by a predetermined distance D (claim 2).

This is for unifying the position as a reference for the absolute position information on the road.

[0016]

Embodiments of the present invention will be described below in detail with reference to the accompanying drawings. FIG. 1 is a view of a road in which three rows of magnetic tapes are provided in the middle of a lane as viewed from a low altitude. FIG. 2 shows a perspective view of a magnetic tape attached to a road. Three magnetic tapes are stuck in a lane width of 3.5 m, and the distance between the magnetic tapes is about 50 cm. Magnetic tape is
This is a rubber tape filled with ferromagnetic powder and having a thickness of about 1 cm and a width of about 20 cm.
(For example, 30 cm) in a cycle (hereinafter, the N pole may be represented by 1 and the S pole may be represented by -1).

Since the magnetic tape is attached in three rows per lane, the code forming the rightmost column is regarded as the lower digit, and the code configuring the middle column is regarded as the middle digit. Considering the sign that constitutes the leftmost column as the upper digit,
A combination of codes (hereinafter referred to as a “code”) is formed by the codes of the upper, lower, middle, and lower digits. For example, codes (1,1,1), (1,1, -1), (1, -1,1),... Are created along the traveling direction.

A series of N codes is defined as one unit (frame). This one frame 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. A device for error detection (for example, a parity check code) may be added to this code. 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. .

Therefore, the code is detected by the on-vehicle device,
By decoding and separating, various embedded information can be obtained at the same time. 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. Unit 16, a magnetic field detecting unit 13A, 13B for detecting the magnetic field of the magnetic tape embedded in the road, and a magnetic field of the magnetic tape embedded along the road, and the magnetic resistance of any of the magnetic field detecting units 13A, 13B. Detecting element specifying unit 1 for specifying whether the element has been detected
4A, 14B and waveform shaping units 15A, 15B, and code decoding units 18A, 18 for decoding codes on the magnetic tape and outputting absolute position signals indicating absolute positions on the road.
B, a position determining unit 17 that resets the estimated position detected by the position estimating unit 16 with the absolute position signal, and transmits an absolute position signal of the vehicle detected by microwave or millimeter wave to another vehicle, and And a transmitting / receiving unit 20 for receiving an absolute position signal from the vehicle.

More specifically, for example, a wheel speed sensor can be used as the traveling distance detecting unit 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.

As shown in FIG. 4, the magnetic field detectors 13A and 13B have a circuit configuration in which a plurality of magnetoresistive elements 1 are arranged on a long and thin rubber-like permanent magnet 3, and an output voltage is taken out from each. The magnetoresistive element 1 is an element whose electric resistance changes when a magnetic field is applied.
Semiconductor materials such as b, GaAs, and InAs are often used. In the present embodiment, I.sub.
An element in which an nSb thin film is formed is used (for example, a “magnetic resistance element TMS-D series” manufactured by Toyocom Toyo Tsushinki Co., Ltd. can be used). In addition, a bulk (single crystal) type magnetic resistance element is used. May be used.

As shown in FIG. 5, the magnetic field detectors 13A and 13B are attached to the bottoms of the front and rear bumpers so as to be perpendicular to the direction of the vehicle and parallel to each other. The installation interval between the magnetic field detection units 13A and 13B is D.
The detection element specifying units 14A and 14B detect the magnetic field of the magnetic tape embedded along the road by using the magnetic field detection units 13A and 13B.
Which of the magnetoresistive elements has been detected is specified. 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. When a plurality of continuous elements are specified, the number is limited to one at the center.

If the same number of magnetoresistive elements as the number of rows of the magnetic tape are specified, the sign (±) of the output voltage is determined. The code decoding units 18A and 18B can read the code of the magnetic tape based on the sign of the output voltage. The code contents read by the code decoding units 18A and 18B are different from each other because the magnetic field detection units 13A and 13B are installed at an installation distance D. For example,
When the code decoding unit 18A is reading the absolute position information on the road, the code decoding unit 18B may be reading the road shape information. Code decoding unit 18A
When reading traffic regulation information,
8B may read the absolute position information on the road.

In the present invention, any one of the code decoding units 18
When A or 18B reads the absolute position information on the road, the absolute position signal is input to the position determining unit 17 through the OR circuit 21. In this case, the magnetic field detector 13
Since A and 13B are installed at the installation interval D, the adder 19 adds the distance D to the absolute position information on the road read by the code decoding unit 18B.

As a result, it is less likely that the absolute position information on the road is interrupted by dividing and multiplexing the codes of the magnetic tape in terms of distance. Then, based on the absolute position information on the road included in the read code and the pitch a, the absolute positions 0, 1 on the road are determined.
a, 2a, 3a, ‥‥ are calculated. The position estimating unit 16
The distance data ΔD _n output from the traveling distance detection unit 11 is taken in, and the component ΔD _n is added to the previous estimated position data D _n−1 in consideration of the traveling direction detected by the traveling direction detection unit 12. By doing so, the current estimated position D
_{Find n} .

[0027] Incidentally, it is necessary to determine the initial position D ₀ of the estimated position, the initial position D _0, the code decryption portion 18
A, Each time the absolute position signal is received from 18B,
The coordinates ma (m is 0, 1, 2, 2) indicated by the absolute position signal
3, ‥‥) may be used 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 tape.
It will continue position detection based only on the estimated position D _n of the vehicle output from.

According to the present invention, the disadvantage that "obtaining absolute position information on roads by dividing and multiplexing the codes of the magnetic tape in terms of distance is interrupted" is detected by two magnetic field detections. The units 13A and 13B are installed at an installation interval D, and the code decoding units 18A and 1 are independent from each other.
8B, but the position estimating unit 16
There is also an idea that it may be sufficient to supplement with the position estimation function.

However, since there is always an error in the estimated position of the position estimating section 16, it cannot always be said that it is always perfect if the position is estimated by the position estimating function. In the present invention, on the premise that there is an error in the estimated position, the error of the estimated position of the position estimating unit 16 is apparently reduced by increasing the number of times of obtaining the absolute position information on the road as much as possible. I have.

The transmitting and receiving 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 running lane, a vehicle code number, a speed, and acceleration is also exchanged. Then, the distance between the vehicles is calculated, and automatic driving such as automatic braking operation and automatic accelerator operation of the own vehicle is performed so that the vehicle can always travel at a constant interval.

Although the 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-described embodiment, a magnetic tape attached to a road is used as a road marker, but a magnetic nail (magnetized nail) may be embedded instead of the magnetic tape. 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.

[0032]

As described above, according to the road position detecting system of the first aspect, the road marker sensor is attached to the vehicle at a predetermined distance D, and the codes are decoded independently of each other. When the code decoding means detects the absolute position of the vehicle on the road, the absolute position on the road detected by the code decoding means is used as the position of the vehicle. The accuracy of absolute position information detection on the road can be improved.

[Brief description of the drawings]

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

FIG. 2 is a perspective view of a magnetic tape attached to a road.

FIG. 3 is a block diagram illustrating a configuration of 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 diagram showing a magnetic field detection unit attached to bottoms of front and rear bumpers so as to be perpendicular to the direction of the vehicle and parallel to each other.

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.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Magneto-resistance element 2 Resistance element 3 Permanent magnet 11 Travel distance detection part 12 Travel direction detection part 13A, 13B Magnetic field detection part 14A, 14B Detection element specification part 16 Position estimation part 17 Position determination part 18A, 18B Code decoding part

Claims (2)

[Claims] 1. A road position detecting system for laying a road marker in a traveling direction of a road, and detecting a position of the vehicle by detecting the road marker. Is divided into distances, multiplexed information including absolute position information on the road is added, and a road marker sensor for detecting a road marker is attached to the vehicle at a predetermined distance D, and the vehicle-mounted device includes: Two code decoding means for decoding codes independently of each other based on the sign of the road marker detected by the road marker sensor, and one of the code decoding means detects the absolute position of the own vehicle on the road. And a position determining means for determining an absolute position on the road detected by the code decoding means as a position of the vehicle. 2. An apparatus according to claim 1, wherein said code decoding means corrects and detects the road marker sensor by a predetermined distance D when detecting an absolute position on the road. Road position detection system as described.