JP2008269295A - Road-vehicle communication system, road-to-vehicle communication method, and optical beacon - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a road-vehicle communication system which finds a traveling position in a travelling direction of an on-vehicle device, in an optical beacon. <P>SOLUTION: An optical beacon 4 is provided with; a light projection and reception device 8 having first and second light-receiving elements 10 and 11 which are different in installation position in a vehicle travelling direction; and a computation part 7 which computes a traveling position in a travelling direction of the on-vehicle device, on the basis of a time difference between the time when the first light-receiving element 10 receives an optical signal from the on-vehicle device 2 and the time when the second light-receiving element 11 receives the optical signal. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a road-to-vehicle communication system, a road-to-vehicle communication method, and an optical beacon used for road-to-vehicle communication that perform bidirectional communication using optical signals between an optical beacon and an in-vehicle device mounted on a vehicle.

As a traffic information service using a road-to-vehicle communication system, so-called VICS (Vehicle Information and Communication System) using optical beacons, radio wave beacons or FM multiplex broadcasting has already been developed. Among these, the optical beacon employs optical communication using near infrared rays as a communication medium, and bidirectional communication with the in-vehicle device is possible.
Specifically, uplink information held by the vehicle is transmitted from the in-vehicle device to the infrastructure-side optical beacon, and conversely, downlink information including traffic jam information, distance information, event regulation information, lane notification information, and the like is an optical beacon. Is transmitted to the in-vehicle device (for example, see Patent Document 1).

In such a road-to-vehicle communication system, the optical beacon continues to transmit the first downlink information to the road, and when the in-vehicle device mounted on the vehicle receives it, the in-vehicle device moves to the optical beacon side. Transmission of uplink information including ID information is started. When the optical beacon receives this uplink information, the optical beacon starts transmitting the second downlink information to the in-vehicle device having the vehicle ID information. The second downlink information includes the traffic jam information and distance information described later. Thereby, the required communication is performed between the optical beacon and a specific in-vehicle device.
JP 2005-268925 A

In the road-to-vehicle communication system, the length in the vehicle traveling direction of the downlink region where the in-vehicle device receives the downlink information from the optical beacon and the uplink region where the optical beacon receives the uplink information from the in-vehicle device. The optical beacon needs to transmit the downlink information to the in-vehicle device by receiving the uplink information from the in-vehicle device in the uplink area.
However, in fact, the in-vehicle device may receive downlink information even in an area other than the specified downlink area, or an optical beacon may receive uplink information in an area other than the specified uplink area. In this case, the optical beacon starts to transmit the second downlink information to the in-vehicle device in the area other than the prescribed communication area. That is, the optical beacon cannot determine the traveling position of the in-vehicle device, and determines whether the received uplink information is information transmitted from the in-vehicle device existing in the specified uplink region. Could not do.

  Further, the distance information included in the second downlink information is a stop provided in front of a traffic signal, for example, a predetermined position on the downstream side from a travel position of the vehicle (on-vehicle device) during information communication. Information about the distance to the line. Therefore, the in-vehicle device that has received the distance information uses the distance information to brake the vehicle so as to forcibly stop before the stop line, or to notify the driver to stop or decelerate. In some cases, safe driving assistance is provided to the driver (for example, Japanese Patent Application Nos. 2006-121692 and 2006-121700 proposed by the applicant of the present application).

  When performing such safe driving support, the distance information provided to the in-vehicle device needs to be highly accurate. This means that if the distance information received by the in-vehicle device is significantly different from the actual distance to the stop line, even if the vehicle is braked to stop before the stop line by the safe driving function, it will stop. This is because a situation may occur in which the vehicle is stopped after the line is exceeded. In order to obtain highly accurate distance information, it is necessary to accurately obtain the current traveling position of the in-vehicle device (since the position of the stop line is a specified position).

  Then, this invention aims at providing the road-to-vehicle communication system, the road-to-vehicle communication method, and the optical beacon which can obtain | require the driving | running | working position of vehicle equipment.

  In order to achieve the above object, a first road-to-vehicle communication system according to the present invention includes an in-vehicle device for a vehicle traveling on a road, and an optical beacon in which a communication area is set in a predetermined range of the road. A road-to-vehicle communication system that performs two-way communication using an optical signal between an aircraft and the optical beacon, wherein the optical beacon includes first and second light receiving elements having different installation positions in the vehicle traveling direction. And, based on at least one of the time difference and the difference in received light intensity when the first and second light receiving elements respectively receive the optical signals from the in-vehicle device, the travel position of the in-vehicle device in the vehicle traveling direction is determined. And a calculation unit to be obtained.

  And the road-to-vehicle communication method performed by this road-to-vehicle communication system is a two-way communication using an optical signal between an in-vehicle device of a vehicle traveling on a road and an optical beacon in which a communication area is set in a predetermined range of the road. In the optical beacon, the first and second light receiving elements are provided in the optical beacon so that the installation positions in the vehicle traveling direction are different, and the optical signal from the in-vehicle device is transmitted to the first and second optical signals. Based on at least one of the time difference and the light intensity difference when each light receiving element receives light, the travel position of the in-vehicle device in the vehicle traveling direction is obtained.

  According to the road-to-vehicle communication system and the road-to-vehicle communication method, in the light beacon projector / receiver, the first and second light receiving elements are provided so that the installation positions in the vehicle traveling direction are different. There is a time difference between the time when the first light receiving element receives the light signal transmitted from the first light receiving element and the time when the second light receiving element receives light. There is a difference between the received light intensity when the element receives light and the received light intensity when the second light receiving element receives light. And the calculating part can obtain | require the driving | running | working position of the vehicle advancing direction of a vehicle-mounted apparatus based on at least one of this time difference and light reception intensity difference.

The calculation unit includes a difference detection unit that detects a time difference between light reception times of the first and second light receiving elements, and a storage unit that stores a functional relationship that is established between the time difference and the travel position; And a position specifying unit that obtains the travel position corresponding to the time difference detected by the difference detection unit from the functional relationship.
According to this, when the difference detection unit detects the time difference, the position specifying unit can easily obtain the traveling position from the functional relationship stored in the storage unit.

In addition, the arithmetic unit stores a difference detection unit that detects a difference in received light intensity between the first and second light receiving elements, and a storage unit that stores a functional relationship established between the difference in received light intensity and the travel position. And a position specifying unit that obtains the traveling position corresponding to the difference in received light intensity detected by the difference detecting unit from the functional relationship.
According to this, when the difference detection unit detects the difference in received light intensity, the position specifying unit can easily obtain the traveling position from the functional relationship stored in the storage unit.

Further, the storage unit stores a plurality of different functional relationships for each installation height of the in-vehicle device, and the position specifying unit obtains information related to the installation height of the in-vehicle device and determines the installation height. It is preferable to select the functional relationship corresponding to the size.
The relationship between the time difference and the traveling position, or the relationship between the difference in received light intensity and the traveling position varies depending on the installation height of the vehicle-mounted device in the vehicle. Therefore, according to this configuration, the position specifying unit can acquire information related to the installation height of the in-vehicle device and select a functional relationship corresponding to the installation height, thereby increasing the accuracy of obtaining the traveling position. Can do.

  Furthermore, it is preferable that the optical beacon transmits the obtained travel position information to the in-vehicle device. As a result, the in-vehicle device can determine its own travel position.

  A second road-to-vehicle communication system of the present invention includes an in-vehicle device for a vehicle traveling on a road, and an optical beacon in which a downlink region and an uplink region are set in a predetermined range of the road, and the in-vehicle device Two-way communication using an optical signal between the vehicle and the optical beacon, and the optical beacon is a road-to-vehicle communication system that transmits predetermined downlink information according to uplink information from the in-vehicle device. The beacon includes a light projecting / receiving device having first and second light receiving elements having different installation positions in the vehicle traveling direction, and a time difference and light reception when the first and second light receiving elements receive light signals from the vehicle-mounted device, respectively. Based on at least one of the intensity differences, a calculation unit that calculates a traveling position of the vehicle-mounted device in the vehicle traveling direction, and the uplink region in which the traveling position determined by the calculation unit is set Wherein in which and a determination unit to start sending predetermined downlink information if it is determined to be.

  According to this road-to-vehicle communication system, in the light beacon projector / receiver, the first and second light receiving elements are provided so that the installation positions in the vehicle traveling direction are different, so that the optical signal transmitted from the in-vehicle device. The time when the first light receiving element receives light and the time when the second light receiving element receives light is different, and when the first light receiving element receives the optical signal transmitted from the vehicle-mounted device There is a difference between the received light intensity and the received light intensity when the second light receiving element receives light. And the calculating part can obtain | require the driving | running | working position of the vehicle advancing direction of a vehicle-mounted apparatus based on at least one of this time difference and light reception intensity difference. Then, the determination unit can transmit the predetermined downlink information to the in-vehicle device by determining that the traveling position is within the set uplink region, so that the optical beacon is When an optical signal transmitted from an in-vehicle device in the link area is received, predetermined downlink information can be transmitted to the in-vehicle device.

  Further, the third road-to-vehicle communication system of the present invention is an in-vehicle device capable of selecting and installing an installation height in a vehicle traveling on a road, an optical beacon in which a communication area is set in a predetermined range of the road, A vehicle-to-vehicle communication system that performs two-way communication using an optical signal between the in-vehicle device and the optical beacon, wherein the optical beacon has first and second light receiving elements having different installation positions in the vehicle traveling direction. And the vehicle traveling of the vehicle-mounted device based on at least one of the time difference and the light-receiving intensity difference when the first and second light receiving elements respectively receive the optical signals from the vehicle-mounted device. A calculation unit that obtains a plurality of travel positions in each direction for each installation height; and a transmission unit that transmits correspondence information of the travel position corresponding to each installation height to the in-vehicle device. Based on the installation height of In which a control unit for obtaining the self-travel position from said corresponding information.

  According to this road-to-vehicle communication system, the installation height can be selected and the vehicle-mounted device can be mounted on the vehicle. That is, it can be mounted on a plurality of types of vehicles such as large vehicles and ordinary vehicles. In the light beacon light emitter / receiver, the first and second light receiving elements are provided so that the installation positions in the vehicle traveling direction are different, so that the first light receiving element transmits the optical signal transmitted from the vehicle-mounted device. There is a time difference between the time when the light is received and the time when the second light receiving element receives light, and the light receiving intensity and the second light receiving element when the first light receiving element receives the optical signal transmitted from the in-vehicle device. There is a difference between the received light intensity when the light is received. And the calculating part can obtain | require multiple about the driving | running | working position of the said vehicle equipment in the vehicle advancing direction for every installation height of an vehicle equipment based on at least one of this time difference and light reception intensity difference. Then, from the transmission unit of the optical beacon, the correspondence information of the traveling position corresponding to each installation height is transmitted to the in-vehicle device, and when the in-vehicle device receives this information, the control unit of the in-vehicle device receives the information From the correspondence information, the traveling position corresponding to the installation height of the user can be obtained. That is, the in-vehicle device can determine the travel position without acquiring information on the installation height of the in-vehicle device on the optical beacon side.

  The optical beacon according to the present invention is an optical beacon that is used for road-to-vehicle communication that performs bidirectional communication using an optical signal with an in-vehicle device of a vehicle, and has different installation positions in the vehicle traveling direction. A projector / receiver having two light-receiving elements, and the vehicle-mounted device based on at least one of a time difference and a light-receiving intensity difference when the first and second light-receiving devices respectively receive optical signals from the vehicle-mounted device. And a calculation unit for obtaining a travel position in the vehicle traveling direction.

  According to this optical beacon, in the light projector / receiver, the first and second light receiving elements are provided so that the installation positions in the vehicle traveling direction are different, so that the optical signal transmitted from the in-vehicle device is received by the first light receiving device. There is a time difference between the time when the element receives light and the time when the second light receiving element receives light, and the received light intensity and the second time when the first light receiving element receives the optical signal transmitted from the in-vehicle device. There is a difference between the received light intensity when the light receiving element receives light. And the calculating part can obtain | require the driving | running | working position of the vehicle advancing direction of a vehicle-mounted apparatus based on at least one of this time difference and light reception intensity difference.

  According to this invention, it becomes possible to grasp the traveling position of the in-vehicle device when the in-vehicle device transmits an optical signal as uplink information.

Embodiments of the present invention will be described below with reference to the drawings.
[Overall system configuration]
FIG. 1 is a block diagram showing the overall configuration of the road-vehicle communication system of the present invention.
As shown in FIG. 1, the road-to-vehicle communication system includes an infrastructure-side traffic control system 1 and an in-vehicle device 2 mounted on each vehicle traveling on a road. The traffic control system 1 includes a central device 3 provided in a control room and a large number of optical beacons (optical vehicle detectors) 4 installed at various locations on the road. Bidirectional communication is performed with the vehicle-mounted device 2 by optical communication using an optical signal) as a communication medium. The central device 3 is provided in the traffic control room.

[Configuration of in-vehicle device 2 and vehicle]
FIG. 2 is a schematic configuration diagram of the optical beacon 4, the in-vehicle device 2 that communicates with the optical beacon 4, and the vehicle C in which the in-vehicle device 2 is mounted. In FIG. 2, a vehicle C includes a vehicle body 15 having a driver's boarding seat (not shown), the vehicle-mounted device 2 mounted on the vehicle body 15, and an electronic control unit (ECU) that integrally controls each part of the vehicle C. 16, an engine 17 that drives the vehicle body 15, a brake device 18 that brakes the vehicle body 15, and a speed detector 26 that constantly detects the current speed of the vehicle C.

The in-vehicle device 2 includes an in-vehicle computer 19 and a projector / receiver (hereinafter referred to as an in-vehicle head 20) connected to the sensor interface of the computer 19.
The in-vehicle head 20 includes a light emitting diode (LED) and a light receiving element (photo sensor) (not shown). Among these, the LED emits uplink information composed of near infrared rays, and the light receiving element receives downlink information composed of near infrared rays emitted in a communication area described later. At least the in-vehicle head 20 of the in-vehicle device 2 is provided in the cab of the vehicle C.

  The in-vehicle computer 19 is composed of a programmable microcomputer having a CPU, a memory (RAM), and a storage device (ROM), and performs control processing for road-to-vehicle communication with the optical beacon 4 by the in-vehicle head 20. The ECU 16 performs various controls on the vehicle C such as drive control of the engine 17 based on the driver's accelerator operation and braking control of the brake device 18 based on the brake operation.

[Configuration of optical beacon 4]
In FIG. 1, an optical beacon 4 includes a communication unit 6 that is a communication interface connected to a central apparatus 3 via a communication line 5 such as a telephone line, a beacon controller 7 to which the communication unit 6 is connected, A plurality of (four in the illustrated example) projector / receiver (hereinafter referred to as a beacon head 8) connected to the sensor interface of the controller 7 is provided.
Each beacon head 8 is configured by housing a light emitting diode (LED: not shown) and a plurality (two) of light receiving elements (photosensors) 10 and 11 in a housing (see FIG. 3). . Among these, the LED emits downlink information composed of near infrared rays to a communication area described later, and each of the photosensors 10 and 11 receives uplink information composed of near infrared rays from the in-vehicle device 2.

  FIG. 4 is a plan view of the optical beacon 4. As shown in FIG. 4, the optical beacon 4 of this embodiment is installed on a road R having a plurality of lanes R1 to R4 (four in the illustrated example) in the same direction, and corresponds to each lane R1 to R4. And four beacon heads 8 provided, and one beacon controller 7 serving as a control unit that collectively controls these beacon heads 8.

The beacon controller 7 is installed on a support column 12 erected on the side of the road, and each beacon head 8 is attached to an installation bar 13 installed horizontally on the road R side from the support column 12, and each lane R <b> 1 of the road R. It is arrange | positioned just above -R4.
The LED of each beacon head 8 emits near-infrared light toward the upstream side of the position immediately below it in each lane R1 to R4, and the light receiving elements 10 and 11 of each beacon head 8 are upstream of the position immediately below. It is possible to receive near-infrared light from the vehicle-mounted device 2 located at the position. Thus, in the optical beacon 4, the communication area A for performing road-to-vehicle communication with the in-vehicle device 2 is set to a predetermined range of the road R, that is, upstream of the beacon head 8 (right side in FIG. 4). ing.

  FIG. 3 is a side view showing a schematic configuration of the beacon head 8 and a communication area A of the optical beacon 4. As shown in FIG. 3, in this communication area A, the in-vehicle head 20 can receive downlink information in a downlink area (area provided with a solid line hatching in FIG. 3) DA, and the beacon head 8 is uplink. It consists of an uplink area (area provided with broken-line hatching in FIG. 3) UA from which information can be received.

  In the “near-infrared interface standard” of the optical beacon (optical vehicle sensor) 4, in the case of the optical beacon 4 for general roads, the uplink area UA at a position 1 m from the road R (road surface) is used. The downstream end b is located 3.4 m upstream from directly below the beacon head 8, and the distance from the downstream end b of the uplink area UA to the upstream end c of the area UA is defined as 1.6 m. Further, the downstream end a of the downlink area DA is located 1.3 m upstream from directly below the beacon head 8, and the distance from the downstream end a of the downlink area DA to the upstream end c of the area DA is 3.7 m. It is prescribed. Note that the lengths of the areas DA and UA in the vehicle traveling direction are not limited to the above numerical values.

  1 and 2, the beacon controller 7 includes a programmable microcomputer having a CPU, a memory (RAM), and a storage device (ROM). The communication unit 6 performs bidirectional communication with the central device 3, and a beacon head. 8 functions as a communication control unit that controls road-to-vehicle communication with the vehicle-mounted device 2. In addition, the beacon controller 7 stores a program that executes each predetermined function in the storage unit 23 (storage device), and the difference detection unit 21, the position specifying unit 22, and the determination unit as the function units that the program executes. 24. In addition, the processing content by the difference detection part 21, the position specific | specification part 22, and the determination part 24 of this beacon controller 7 is mentioned later.

[First Embodiment of Beacon Head 8]
As described above in FIG. 3, the beacon head 8 has the first light receiving element 10 and the second light receiving element 11. The two light receiving elements 10 and 11 are provided in the housing of the beacon head 8 so that the installation positions in the vehicle traveling direction are different. Specifically, the two light receiving elements 10 and 11 are provided at the same height in front and rear positions in the vehicle traveling direction, and the first light receiving element 10 is upstream of the second light receiving element 11 in the vehicle traveling direction. Is provided. In FIG. 3, the distance between the two is shown as a distance d. Therefore, the time (arrival time or light reception start time) when the first light receiving element 10 received near infrared rays transmitted from the light emitting diode of the in-vehicle head 20 and the time (arrival) when the second light receiving element 11 received light. A difference (hereinafter referred to as a time difference) occurs.

This time difference is that the first and second light receiving elements 10 and 11 are provided apart from each other in the front-rear direction. Distance e1 is also referred to as a first optical path length)) and a distance e2 from the in-vehicle head 20 to the second light receiving element 11 (hereinafter referred to as a second transmission distance (or distance e2 is also referred to as a second optical path length)). It is caused by the difference. This time difference is a function of the difference between the first transmission distance e1 and the second transmission distance e1. That is, the time difference Δt can be expressed by Δt = (e2−e1) / c [where c is the speed of light (3.0 × 10 ⁸ m)].

Furthermore, the difference (e2−e1) between the first transmission distance e1 and the second transmission distance e2 changes according to the position of the in-vehicle head 20 in the vehicle traveling direction with respect to the position of the beacon head 8. That is, the difference (e2−e1) changes according to the distance L0 in the vehicle traveling direction along the road from the position g immediately below the beacon head 8 to the in-vehicle head 20.
Therefore, instead of detecting the difference (e2-e1) between the first transmission distance e1 and the second transmission distance e2, the beacon controller 7 detects a time difference Δt that is a function of this difference (e2-e1). As described later, based on this time difference Δt, it is possible to detect the traveling position (for example, the distance L1 in FIG. 3) of the vehicle-mounted device 2 (vehicle-mounted head 20) in the vehicle traveling direction.

[Specific processing contents of the beacon controller 7]
The difference detection unit 21 (see FIG. 2) of the beacon controller 7 receives the near-infrared light transmitted from the in-vehicle head 20 by the first light receiving element 10 of the beacon head 8 and the near-infrared light of the beacon head 8. A difference (time difference) from the time when the second light receiving element 11 receives light is detected. A method for detecting a time difference by the difference detection unit 21 will be described. In FIG. 3, the second light receiving element 11 is separated from the vehicle-mounted head 20 by the distance d in a direction parallel to the road R than the first light receiving element 10, so that the first light receiving element 11 is shown in FIG. 5. The second light receiving element 11 receives the near infrared ray with a delay of Δt with respect to the time when the element 10 starts receiving the near infrared ray from the beacon head 20. The difference detector 21 detects the time difference that is Δt.

  The difference detection unit 21 has a function as a frequency counter. As shown in FIG. 5, when the difference detection unit 21 converts the signals received by the first light receiving element 10 and the second light receiving element 11 into a digital signal (pulse wave), the rising of the pulse wave by the first light receiving element 10. From time to time until the rise of the pulse wave by the second light receiving element 11, a time difference (phase difference) Δt is generated, and this is measured by the difference detector 21 which is a frequency counter. The received data length is in units of 1 [μs], whereas the time difference Δt is in units of 0.01 [ns]. There is no problem in processing. The difference detector 21 can detect the reception time difference Δt between the first and first light receiving elements 10 and 11 using a counter that operates with a predetermined clock.

The position specifying unit 22 of the beacon controller 7 obtains the travel position of the in-vehicle device 2 (in-vehicle head 20) corresponding to the time difference Δt detected by the difference detection unit 21 from the functional relationship stored in the storage unit 23. . This functional relationship is information about the relationship between the time difference Δt and the position of the in-vehicle head 20 in the vehicle traveling direction along the road R. FIG. 6 illustrates this functional relationship more specifically. FIG. 6 shows the relationship between the time difference Δt [ns] and the distance L1 from the upstream end c of the uplink area UA (of FIG. 3) to the in-vehicle head 20. Information. FIG. 6 shows the case where the distance d (see FIG. 3) is obtained as 5 cm, and the solid line in FIG. 6 shows the case where the height of the in-vehicle head 20 from the road surface is 1 m. This functional relationship is information obtained in advance when the optical beacon 4 is installed, and the storage unit 23 of the beacon controller 7 stores this functional relationship. As a result, when the position specifying unit 22 obtains the time difference Δt detected by the difference detecting unit 21, the position specifying unit 22 does not obtain it by calculation, but from the functional relationship stored in the storage unit 23, the position of the vehicle-mounted device 2 (distance L 1 ) Can be easily obtained.
Then, the optical beacon 4 uses the beacon head 8 to transmit the information on the travel position (distance L1) obtained by the position specifying unit 22 to the in-vehicle device 2, and the in-vehicle device 2 uses the in-vehicle head 20. By receiving this information, it is possible to obtain its own traveling position.

  The determination unit 24 of the beacon controller 7 determines whether or not the traveling position obtained by the position specifying unit 22 is within the prescribed uplink area UA. In other words, in FIG. 3, it is determined whether or not the value of the distance L1 obtained by the position specifying unit 22 is a value corresponding to between the downstream end b and the upstream end c of the uplink area UA. Specifically, in FIG. 3, when the value of the distance L1 is in the range of −1.6 [m] or more and 0 [m] or less, the determination unit 24 determines that the travel position obtained by the position specifying unit 22 is If it is determined that the position is within the uplink area UA and the value of the distance L1 is outside the range, the determination unit 24 determines that the travel position obtained by the position specifying unit 22 is outside the uplink area UA. Then, when the determination unit 24 determines that the travel position obtained by the position specifying unit 22 is within the uplink area UA, the determination unit 24 sends predetermined downlink information (second down-link described later) to the in-vehicle device 2. Transmission of link information) can be started.

  6 will be further described. As described above, the difference (e2-e1) between the first transmission distance e1 (in FIG. 3) and the second transmission distance a2 is the in-vehicle head 20 with respect to the position of the beacon head 8. Depending on the position in the vehicle traveling direction (distance L1 or distance L0). As is clear from FIG. 3, for example, as the in-vehicle head 20 approaches the beacon head 8, the transmission distance difference (e2−e1) decreases. Then, the difference (e2−e1) is 0 at a position immediately below the first light receiving element 10 and the second light receiving element 11 (a position directly below the beacon head 8 g: L1 = −5 [m]). In this way, the relationship between the time difference Δt, which is a function of the transmission distance difference (e2-e1), and the position L1 of the in-vehicle head 20 can be obtained in advance, and this is stored in the storage unit 23 as a functional relationship. ing.

The in-vehicle head 20 of the in-vehicle device 2 can be selected from a plurality of types of installation heights (for example, 1 m and 2 m) and mounted on the vehicle. For example, the in-vehicle head 20 is mounted on a normal passenger car. Therefore, the installation height can be selected as 1 m. Moreover, in order to mount the vehicle-mounted head 20 on a large vehicle such as a bus or truck, the installation height can be selected as 2 m. Thus, the installation height of the in-vehicle head 20 differs depending on the vehicle type because the in-vehicle head 20 is usually attached to a portion (position on the dashboard) in front of the windshield in the driver's seat.
And the continuous line of FIG. 6 is a case where the height of the vehicle-mounted head 20 is 1 m, and is a case where the vehicle equipment 2 is mounted in a normal passenger car. The broken line in FIG. 6 is the case where the height of the vehicle-mounted head 20 is 2 m, and the case where the vehicle-mounted device 2 is attached to a large vehicle such as a bus or truck. Thus, when the mounting height of the vehicle-mounted head 20 is different, the relationship between the time difference Δt and the position L1 of the vehicle-mounted device 2 changes.

  Therefore, the storage unit 23 stores a plurality of the functional relationships that differ depending on the installation height of the in-vehicle head 20. And the said position specific | specification part 22 acquires the height information regarding the installation height of the vehicle equipment 2 (vehicle-mounted head 20) further, selects the functional relationship corresponding to this height information, and the driving | running | working of the said vehicle equipment 2 The position is detected. This height information may be included in the uplink information transmitted from the in-vehicle device 2 and may be obtained by the optical beacon 4 receiving this uplink information from the in-vehicle device 2. Alternatively, another sensor (not shown) is provided on the upstream side of the beacon head 8, and the height of the vehicle C is determined by this sensor, whereby the mounting height of the vehicle-mounted head 20 of the vehicle C is determined. The height information may be obtained by determining and receiving the determination information (height information) by the position specifying unit 22. As described above, based on the height information of the vehicle-mounted device 2, the position specifying unit 22 selects a function relationship for a normal vehicle (solid line in FIG. 6) or a function relationship for a large vehicle (dashed line in FIG. 6). Thus, the detection accuracy by the position specifying unit 22 can be increased.

[Road-to-vehicle communication]
FIG. 8 shows a two-way road-to-vehicle communication procedure performed between the beacon head 8 and the vehicle-mounted head 20 in the communication area A. The contents of this road-to-vehicle communication will be described below with reference to FIGS.
First, the beacon controller 7 of the optical beacon 4 sends the first downlink information 28 including the lane notification information as the first information before switching the downlink from each beacon head 8 corresponding to each lane R1 to R4. The lanes R1 to R4 are continuously transmitted at a predetermined transmission cycle (F1 in FIG. 8). At this stage, the vehicle ID is not yet stored in the lane notification information. The first downlink information 28 may be transmitted to the specified downlink area DA, but in actuality, it is also transmitted to a wide area upstream of the downlink area DA.

  When the vehicle C equipped with the in-vehicle device 2 exists on the upstream side of the prescribed downlink area DA and the in-vehicle head 20 receives the first downlink information 28, the in-vehicle computer 19 transmits the uplink information 29. Is started (F2 in FIG. 8), and this uplink information 29 is transmitted to the beacon head 8 at a predetermined transmission cycle (F3 in FIG. 8). The transmission of the uplink information 29 may also be performed in a region upstream of the prescribed uplink region UA. In addition, a specific vehicle ID is stored in the vehicle C in the uplink information 29 and the uplink information 29 is transmitted.

  In this case, when the first light receiving element 10 and the second light receiving element 11 of the beacon head 8 receive the uplink information 29 (F4 in FIG. 8), first, the beacon controller 7 The position specifying unit 22 is caused to function, and the in-vehicle device 2 determines whether or not the uplink information 29 has been transmitted in a state of entering the specified uplink area UA. That is, the beacon controller 7 detects the position of the in-vehicle device 2.

In other words, the difference detection unit 21 receives the near-infrared light (uplink information 29) transmitted from the vehicle-mounted head 20 by each of the first light receiving element 10 and the second light receiving element 11 (the time difference when the light reception starts). The position specifying unit 22 detects the position of the in-vehicle device 2 based on the time difference detected by the difference detecting unit 21 and the functional relationship (see FIG. 6). Further, at the time of this position detection, the position specifying unit 22 obtains height information about the height of the in-vehicle head 20, and further detects the position of the in-vehicle device 2 based on this height information.
Specifically, the position specifying unit 22 detects that the height of the in-vehicle head 20 is 1 m, and when the difference detecting unit 21 detects the time difference Δt as 0.15 [ns], a solid line in FIG. By selecting the function relationship according to, the distance L1 can be detected as 4.9 m. That is, the in-vehicle device 2 (vehicle C) can recognize that it exists at a position 4.9 m upstream from the start point c (see FIG. 3) of the uplink area UA.

In this case, the determination unit 24 can determine that the near-infrared light received by the beacon head 8 is not transmitted in the specified uplink area UA. In this case, the determination unit 24 uses the optical beacon 2 The process for returning to the step of F1 in FIG. 8 is performed without performing the subsequent processes (the processes after F5 in FIG. 8 described later).
On the other hand, when the position specifying unit 22 detects the distance L1 as 0 m or less (minus value: −1.6 [m] or more in FIG. 3) using the detection result detected by the difference detection unit 21, The determination unit 24 can determine that the uplink information 29 received by the beacon head 8 has been transmitted in the specified uplink area UA. In this case, the determination unit 24 performs the following in the optical beacon 2. (The process after F5 in FIG. 8) is performed.

  Explaining the processing after F5 in FIG. 8, the beacon controller 7 includes the second downlink including the lane notification information for the vehicle-mounted device 2 having the vehicle ID information as the second information after the downlink switching. The transmission of the information 30 is started (F5 in FIG. 8), and the transmission of the downlink information 30 is repeated as much as possible within a predetermined time (F6 in FIG. 8).

The second downlink information 30 includes traffic information, section travel time information, event regulation information, and support information for safe driving support for the driver, in addition to the lane notification information including the vehicle ID. Yes. The support information includes, for example, the traffic signal information that is timing information at which the light color of the traffic light downstream of the optical beacon 4 changes, and a predetermined position downstream of the optical beacon 4 (for example, a stop before the front intersection) The distance information about the target distance to the line) is included. The target distance is a distance from the predetermined position (stop line) to the upstream end c of the uplink area UA, and a distance from the upstream end c to the in-vehicle head 20 when the optical beacon 4 receives the uplink information. L1 (see FIG. 3), the distance from the predetermined position (stop line) to the upstream end c is a specified value (measured in advance) and stored in the beacon controller 7. Information, and the distance L1 is obtained by the position specifying unit 22.
Then, the in-vehicle computer 19 of the in-vehicle device 2 recognizes the downlink switching in the optical beacon 4 at the time of receiving the second downlink information 30 (F7 in FIG. 8), and at this time, the uplink information 29 Stop sending.

As described above, when the determination unit 24 of the beacon controller 7 determines that the travel position obtained by the position specifying unit 22 is within the specified uplink area UA, The transmission of the downlink information 30 can be started.
And the vehicle-mounted computer 19 of the vehicle-mounted apparatus 2 can start control of safe driving assistance based on this assistance information, if this 2nd downlink information 30 containing assistance information is received (F8 of FIG. 8). . For example, the safe driving assistance is performed by automatically decelerating the vehicle C to a predetermined speed or automatically stopping the vehicle C at a predetermined position (stop line) downstream of the beacon head 8 in the vehicle traveling direction. It is an operation that can be performed.

In the above road-to-vehicle communication, after the information on the installation height of the in-vehicle device 2 is acquired on the optical beacon 4 side, the position specifying unit 22 specifies the travel position (distance L1) of the in-vehicle device 2, and the travel position is When the determination unit 24 determines that it is outside the prescribed uplink area UA, downlink switching (F5 in FIG. 8) is not performed.
As a method other than this embodiment, a method in which the position specifying unit 22 specifies the travel position (distance L1) of the in-vehicle device 2 without acquiring information on the installation height of the in-vehicle device 2 on the optical beacon 4 side will be described below.

The configuration of the road-to-vehicle communication system is the same as that in the embodiment (FIG. 2). As described above, the vehicle-mounted device 2 is selected from a plurality of types of installation heights (for example, 1 m and 2 m) and mounted on the vehicle C. be able to. In this embodiment, the functions of the beacon controller 7 are partially different.
2 and 8, when the first light receiving element 10 and the second light receiving element 11 of the beacon head 8 receive the uplink information 29 from the vehicle-mounted device 2 (F4 in FIG. 8), the beacon controller 7 shows, based on the time difference when the first and second light receiving elements 10 and 11 receive the uplink information 29, the traveling position of the vehicle-mounted device 2 in the vehicle traveling direction is set to the plurality of types of installation heights. Ask every time.

That is, the position specifying unit 22 determines the function relationship between the traveling position of the in-vehicle device 2 when the installation height of the in-vehicle device 2 is 1 m and the traveling position of the in-vehicle device 2 when the installation height is 2 m. (See FIG. 6). Then, the beacon controller 7 stores correspondence information regarding the travel position of the in-vehicle device 2 corresponding to each installation height in the second downlink information 30, and the beacon head 8 transmits this correspondence information to the in-vehicle device 2. To do.
And the in-vehicle device 2 receives and stores information about its own installation height when it is attached to the vehicle C, and receives the received response based on the stored information on its own installation height. From the information, the in-vehicle computer 19 obtains (selects) its own travel position corresponding to the information of the installation height.

According to this embodiment, even if it does not acquire the information on the installation height of the vehicle-mounted device 2 on the optical beacon 4 side, it is advantageous in that the vehicle-mounted device 2 can obtain the travel position information.
In addition, in this embodiment, although the installation height of the vehicle equipment 2 was made into two types, 1m and 2m, in addition to this, the kind of installation height can be made into three or more types. In this case, the functional relationship corresponding to each installation height is stored in the storage unit 23.

[Second Embodiment of Beacon Head 8]
The beacon head 8 has a first light receiving element 10 and a second light receiving element 11 (see FIG. 3), as in the above embodiment, and these light receiving elements 10 and 11 are within the housing of the beacon head 8. The installation positions in the vehicle traveling direction are different. Specifically, the two light receiving elements 10 and 11 are provided at the same height in front and rear positions in the vehicle traveling direction, and the first light receiving element 10 is upstream of the second light receiving element 11 in the vehicle traveling direction. Is provided. In FIG. 3, the distance between the two is shown as a distance d.
Therefore, in this embodiment, the light receiving intensity of the first light receiving element 10 when the first light receiving element 10 receives near infrared rays transmitted from the light emitting diode of the in-vehicle head 20, and the second light receiving element. A difference (hereinafter, referred to as a difference in received light intensity) occurs between the received light intensity in the second light receiving element 11 when 11 receives light, and this difference is utilized. This will be described below.

  The light receiving intensity of each of the light receiving elements 10 and 11 depends on the near-infrared spatial propagation loss with the in-vehicle head 20 because the output of the in-vehicle head 20 is constant. It depends on the distance between them (near infrared transmission distance). Therefore, the difference in the received light intensity includes the distance e1 (hereinafter referred to as the first transmission distance) from the in-vehicle head 20 to the first light receiving element 10 and the distance e2 (hereinafter referred to as the first light receiving element 11) from the in-vehicle head 20 to the second light receiving element 11. Two transmission distances).

  The difference in received light intensity is a function of the difference (ratio) between the first transmission distance e1 and the second transmission distance e2. That is, the received light intensity S is obtained by subtracting the spatial propagation loss Γ from the output P of the in-vehicle head 20 [(received light intensity S) = (output P of the in-vehicle head 20) − (spatial propagation loss Γ)]. The loss Γ can be expressed by Γ = 20 log (4πe / λ) [where e: transmission distance, λ: wavelength (850 nm to 950 nm)]. Thus, the received light intensity difference ΔS can be expressed as ΔS = 20 log (e2 / e1). Note that the output P of the in-vehicle head 20 is constant.

Furthermore, the ratio (e2 / e1) between the first transmission distance e1 and the second transmission distance e2 changes according to the position of the in-vehicle head 20 in the vehicle traveling direction with respect to the position of the beacon head 8. That is, the ratio (e2 / e1) changes according to the distance L0 in the vehicle traveling direction along the road from the position g immediately below the beacon head 8 to the vehicle-mounted head 20.
Therefore, instead of detecting a value based on the ratio (e2 / e1) between the first transmission distance e1 and the second transmission distance e2, the beacon controller 7 receives the received light intensity difference ΔS that is a function of the ratio (e2 / e1). As will be described later, the traveling position of the in-vehicle device 2 (in-vehicle head 20) in the vehicle traveling direction (for example, the distance L1 in FIG. 3) can be detected based on this difference in received light intensity ΔS. .

[Specific processing contents of the beacon controller 7]
The difference detector 21 (see FIG. 2) of the beacon controller 7 receives light intensity at the first light receiving element 10 when the first light receiving element 10 of the beacon head 8 receives near infrared rays transmitted from the in-vehicle head 20. And the received light intensity difference ΔS is detected from the received light intensity of the light receiving element 11 when the second light receiving element 11 of the beacon head 8 receives the near infrared light. In the detection method of the difference in received light intensity ΔS, the difference detecting unit 21 receives near-infrared light reception intensity [dB] received by the first light-receiving element 10 and near-infrared light reception intensity [dB] received by the second light-receiving element 11. Is detected, and the received light intensity difference ΔS is obtained by calculation from these differences.

  In the position specifying unit 22 of the beacon controller 7, the storage unit 23 stores the traveling position of the in-vehicle device 2 (in-vehicle head 20) corresponding to the received light intensity difference ΔS detected by the difference detection unit 21. Obtained from the functional relationship. This functional relationship is information about the relationship between the received light intensity difference ΔS and the position of the in-vehicle head 20 in the vehicle traveling direction along the road R. FIG. 7 illustrates this functional relationship more specifically, and the relationship between the received light intensity difference ΔS [dB] and the distance L1 from the upstream end c of the uplink area UA (in FIG. 3) to the in-vehicle head 20. Information about. FIG. 7 shows the case where the distance d is obtained as 5 cm, and the solid line in FIG. 7 shows the case where the height of the in-vehicle head 20 is 1 m. This functional relationship is information obtained in advance when the optical beacon 4 is installed, and the storage unit 23 of the beacon controller 7 stores this functional relationship. As a result, when the position specifying unit 22 obtains the received light intensity difference ΔS detected by the difference detecting unit 21, the position specifying unit 22 does not obtain it by calculation, but from the functional relationship stored in the storage unit 23, the traveling position ( The distance L1) can be easily determined.

Then, the optical beacon 4 uses the beacon head 8 to transmit the information on the travel position (distance L1) obtained by the position specifying unit 22 to the in-vehicle device 2, and the in-vehicle device 2 uses the in-vehicle head 20. By receiving this information, it is possible to obtain its own traveling position.
The determination unit 24 of the beacon controller 7 determines whether or not the travel position obtained by the position specifying unit 22 is within the specified uplink area UA, as in the embodiment.

  The functional relationship in FIG. 7 will be further described. As described above, the ratio (e2 / e1) between the first transmission distance e1 and the second transmission distance a2 (in FIG. 3) is the in-vehicle head 20 with respect to the position of the beacon head 8. Depending on the position in the vehicle traveling direction (distance L1 or distance L0). As is clear from FIG. 3, for example, as the in-vehicle head 20 approaches the beacon head 8, the transmission distance ratio (e2 / e1) increases. The ratio (e2 / e1) is 1 at a position immediately below the first light receiving element 10 and the second light receiving element 11 (a position directly below the beacon head 8: L1 = −5 [m]). Thus, the relationship between the received light intensity difference ΔS, which is a function of the transmission distance ratio (e2 / e1), and the position L1 of the in-vehicle head 20 can be obtained in advance, and this is stored in the storage unit 23 as a functional relationship. I remember it.

  Moreover, the continuous line of FIG. 7 is a case where the height of the vehicle-mounted head 20 is 1 m, and is a case where the vehicle equipment 2 is mounted in a normal passenger car. And the broken line of FIG. 7 is a case where the height of the vehicle-mounted head 20 is 2 m, and is a case where the vehicle-mounted apparatus 2 is attached to large vehicles, such as a bus and a truck. Thus, when the mounting height of the vehicle-mounted head 20 is different, the relationship between the difference in received light intensity and the position of the vehicle-mounted device 2 changes. Therefore, as in the embodiment, the storage unit 23 stores a plurality of functional relationships that differ for each installation height of the in-vehicle head 20. And the said position specific | specification part 22 acquires the height information regarding the installation height of the vehicle equipment 2 (vehicle-mounted head 20) further, selects the functional relationship corresponding to this height information, and the driving | running | working of the said vehicle equipment 2 The position is detected. Thereby, based on the height information of the vehicle-mounted device 2, the position specifying unit 22 can select a functional relationship for ordinary vehicles (solid line in FIG. 7) or a functional relationship for large vehicles (broken line in FIG. 7). It is possible to increase the detection accuracy by the position specifying unit 22.

  The road-to-vehicle communication according to this embodiment is the same as the road-to-vehicle communication according to the above-described embodiment (see FIG. 8), and the first light receiving element 10 and the second light receiving element 11 of the beacon head 8 are uplinked from the in-vehicle device 2. When the information 29 is received (F4 in FIG. 8), first, the beacon controller 7 causes the difference detection unit 21 and the position specifying unit 22 to function, and receives light in the first light receiving element 10 and the second light receiving element 11. By using the intensity difference ΔS, the in-vehicle device 2 determines whether or not the uplink information 29 has been transmitted in the state of entering the specified uplink area UA.

That is, the difference detection unit 21 receives the near-infrared light (uplink information 29) transmitted from the vehicle-mounted head 20 between the received light intensity received by the first light receiving element 10 and the received light intensity received by the second light receiving element 11. The position specifying unit 22 detects the position of the in-vehicle device 2 based on the difference in received light intensity detected by the difference detecting unit 21 and the functional relationship (see FIG. 7). Further, at the time of this position detection, the position specifying unit 22 obtains height information about the height of the in-vehicle head 20, and further detects the position of the in-vehicle device 2 based on this height information.
More specifically, when the position identifying unit 22 detects that the height of the in-vehicle head 20 is 1 m and the difference detecting unit 21 detects the received light intensity difference ΔS as 0.04 [dB], FIG. In FIG. 5, a function relationship by a solid line is selected, and thereby the distance L1 can be detected as 3.5 m. That is, the in-vehicle device 2 (vehicle C) can recognize that it exists at a position 3.5 m upstream from the start point c of the uplink area UA.

In this case, the determination unit 24 can determine that the near-infrared light received by the beacon head 8 is not transmitted in the specified uplink area UA. In this case, the determination unit 24 uses the optical beacon 2 The process for returning to the step of F1 in FIG. 8 is performed without performing the subsequent processes (the processes after F5 in FIG. 8 described later).
On the other hand, when the position specifying unit 22 detects the distance L1 as 0 m or less (minus value: −1.6 [m] or more in FIG. 3) using the detection result detected by the difference detection unit 21, The determination unit 24 can determine that the uplink information 29 received by the beacon head 8 has been transmitted in the specified uplink area UA. In this case, the determination unit 24 performs the following in the optical beacon 2. (The process after F5 in FIG. 8) is performed.

The present invention is not limited to the above embodiment.
In the embodiment described above, the beacon controller 7 is based on only one of the time difference and the light intensity difference when the first and second light receiving elements 10 and 11 receive the uplink information from the in-vehicle device 2 respectively. In the above description, the traveling position of the in-vehicle device 2 in the vehicle traveling direction has been described. When the beacon head 8 can detect both the time difference and the difference in received light intensity (simultaneously), the beacon controller 7 May determine the traveling position of the in-vehicle device 2 by each means described in the above embodiment using both the time difference and the received light intensity difference. In this case, the average of the travel position obtained based on the time difference and the travel position obtained based on the difference in received light intensity may be used as the resulting travel position. In addition, if the difference between the travel position obtained based on the time difference and the travel position obtained based on the difference in received light intensity exceeds a prescribed threshold value stored in the beacon controller 7, some detection abnormality occurs. It may be determined that the travel position is determined, and the processing for obtaining the travel position may be stopped.
As described above, in the present invention, the beacon controller 7 obtains the traveling position of the in-vehicle device 2 in the vehicle traveling direction based on at least one of the time difference and the received light intensity difference.

Further, for example, in the first (second) embodiment of the beacon head 8, the functional relationship of FIG. 6 (FIG. 7) is expressed by the time difference Δt (light reception intensity difference ΔS) and the communication area A to the in-vehicle head 20. Although described as information about the relationship with the distance L1, the distance L0 along the road R from the position g directly below the beacon head 8 to the in-vehicle head 20 may be used instead of the distance L1.
Moreover, although the functional relationship of FIG. 6 (FIG. 7) was demonstrated as information acquired beforehand about the relationship between time difference (DELTA) t (light reception intensity difference (DELTA) S) and the position of the vehicle equipment 2 of the vehicle advancing direction along the road R, In addition to this, the functional relationship may be information about a calculation formula (calculation program) for detecting the position of the in-vehicle device 2 (for example, the distance L0 or L1) based on the time difference Δt (light reception intensity difference ΔS). The calculation formula may be stored in the storage unit 23. In this case, when the difference detecting unit 21 detects the time difference Δt (light reception intensity difference ΔS), the position specifying unit 22 can detect the position of the in-vehicle device 2 (in-vehicle head 20) by using the above calculation formula. it can.

1 is a block diagram showing an overall configuration of a road-to-vehicle communication system according to the present invention. It is a schematic block diagram of the optical beacon, the vehicle equipment which communicates with this optical beacon, and the vehicle by which the said vehicle equipment is mounted. It is a side view which shows the schematic structure of a beacon head, and the communication area | region of an optical beacon. It is a top view of an optical beacon. It is explanatory drawing explaining the detection method of the time difference by a difference detection part. It is explanatory drawing explaining a function relationship. It is explanatory drawing explaining another function relationship. It is explanatory drawing which shows the procedure of the road-vehicle communication performed between a beacon head and a vehicle-mounted head.

Explanation of symbols

2 In-vehicle device 4 Optical beacon 7 Beacon controller (calculation unit)
8 Beacon head (transmitter)
DESCRIPTION OF SYMBOLS 10 1st light receiving element 11 2nd light receiving element 19 Car-mounted computer (control part)
20 On-vehicle head (emitter / receiver)
21 difference detection unit 22 position specifying unit 23 storage unit 24 determination unit A communication area C vehicle R road

Claims (9)

A vehicle-to-vehicle device that travels on a road, and an optical beacon in which a communication area is set in a predetermined range of the road, and that performs two-way communication using an optical signal between the vehicle-mounted device and the optical beacon. A communication system,
The optical beacon is
A projector / receiver having first and second light receiving elements having different installation positions in the vehicle traveling direction;
An operation for obtaining a travel position of the in-vehicle device in the vehicle traveling direction based on at least one of a time difference and a received light intensity difference when the first and second light receiving elements respectively receive an optical signal from the in-vehicle device. And
A road-to-vehicle communication system comprising:   The calculation unit includes a difference detection unit that detects a time difference between light reception times of the first and second light receiving elements, a storage unit that stores a functional relationship established between the time difference and the travel position, The road-to-vehicle communication system according to claim 1, further comprising a position specifying unit that obtains the travel position corresponding to the time difference detected by the difference detection unit from the functional relationship.   The calculation unit includes a difference detection unit that detects a difference in received light intensity between the first and second light receiving elements, and a storage unit that stores a functional relationship established between the difference in received light intensity and the travel position; The road-to-vehicle communication system according to claim 1, further comprising: a position specifying unit that obtains the traveling position corresponding to the difference in received light intensity detected by the difference detecting unit from the functional relationship.   The storage unit stores a plurality of different functional relationships for each installation height of the in-vehicle device, and the position specifying unit obtains information about the installation height of the in-vehicle device and determines the installation height. The road-vehicle communication system according to claim 2 or 3, wherein the corresponding functional relationship is selected.   The road-to-vehicle communication system according to any one of claims 1 to 4, wherein the optical beacon transmits the obtained travel position information to the in-vehicle device. An on-vehicle device of a vehicle traveling on a road, and an optical beacon in which a downlink region and an uplink region are set in a predetermined range of the road, and bidirectional by an optical signal between the on-vehicle device and the optical beacon Performing communication, the optical beacon is a road-vehicle communication system that transmits predetermined downlink information according to uplink information from the in-vehicle device,
The optical beacon is
A projector / receiver having first and second light receiving elements having different installation positions in the vehicle traveling direction;
An operation for obtaining a travel position of the in-vehicle device in the vehicle traveling direction based on at least one of a time difference and a received light intensity difference when the first and second light receiving elements respectively receive an optical signal from the in-vehicle device. And
A determination unit that starts transmission of the predetermined downlink information when it is determined that the travel position obtained by the calculation unit is within the set uplink region;
A road-to-vehicle communication system comprising: An in-vehicle device capable of selecting and mounting an installation height on a vehicle traveling on a road, and an optical beacon in which a communication area is set in a predetermined range of the road, and between the in-vehicle device and the optical beacon. A road-vehicle communication system that performs two-way communication using optical signals,
The optical beacon is
A projector / receiver having first and second light receiving elements having different installation positions in the vehicle traveling direction;
Based on at least one of a time difference and a received light intensity difference when the first and second light receiving elements respectively receive an optical signal from the in-vehicle device, the installation position of the in-vehicle device in the vehicle traveling direction is set A plurality of calculation units for each height,
A transmission unit that transmits correspondence information of the travel position corresponding to each installation height to the in-vehicle device,
The on-vehicle apparatus includes a control unit that obtains its traveling position from the received correspondence information based on its installation height. An optical beacon used for road-to-vehicle communication, which performs bidirectional communication with an in-vehicle device of a vehicle using an optical signal,
A projector / receiver having first and second light receiving elements having different installation positions in the vehicle traveling direction;
An operation for obtaining a travel position of the in-vehicle device in the vehicle traveling direction based on at least one of a time difference and a received light intensity difference when the first and second light receiving elements respectively receive an optical signal from the in-vehicle device. And
An optical beacon characterized by comprising: A road-to-vehicle communication method for performing bidirectional communication with an optical signal between an in-vehicle device of a vehicle traveling on a road and an optical beacon in which a communication area is set in a predetermined range of the road,
In the optical beacon, the first and second light receiving elements are provided so that the installation positions in the vehicle traveling direction are different, and the time difference when the first and second light receiving elements receive the optical signals from the in-vehicle device, and A road-to-vehicle communication method characterized in that, based on at least one of received light intensity differences, a travel position of the vehicle-mounted device in the vehicle traveling direction is obtained.

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