JP2008090603A - Road-vehicle communication system and method, optical beacon for use therein, on-vehicle device, and vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a road-to-vehicle communication system that allows a driver to determine whether or not maintenance is necessary by making it possible to determine using an on-vehicle device whether or not downlink information is correct. <P>SOLUTION: The road-vehicle communication system includes an on-vehicle device 2 of a vehicle C running on a road R, and an optical beacon 4 having a light emitter-receiver 8 for which a downlink area DA is set within a predetermined range of the road. Two-way communication using optical signals is established between the on-vehicle device 2 and the light emitter-receiver 8 of the optical beacon 4. The optical beacon 4 has a communication control part 7 for storing, in a minimum frame 31 constituting downlink information 30, the cumulative number (n) of frames since the sending of vehicle ID information for the particular vehicle C has been started. The on-vehicle device 2 has a determining part 23 for determining whether or not the state of the road-vehicle communication is good by calculating a frame reception rate (r) based on the cumulative number (n) of frames contained in the minimum frame 31. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  TECHNICAL FIELD The present invention relates to a road-to-vehicle communication system and method, and an optical beacon, an in-vehicle device, and a vehicle used therefor, in which bidirectional communication is performed using an optical signal between an optical beacon installed on a road side and an in-vehicle device mounted on the vehicle. It is.

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 enables two-way communication with the in-vehicle device.
Specifically, uplink information including travel time information between beacons held by the vehicle is transmitted from the in-vehicle device to the optical beacon on the infrastructure side, and conversely, traffic jam information, section travel time information, event regulation information, and lanes Downlink information including notification information and the like is transmitted from the optical beacon to the vehicle-mounted device (see, for example, Patent Document 1).

The optical beacon includes a light projecting / receiving device (beacon head) that performs bidirectional communication with the vehicle-mounted device. The light projecting / receiving device includes a light emitting diode (LED) that transmits downlink information and a vehicle-mounted device. And a photo sensor for receiving the uplink information.
On the other hand, the in-vehicle device is also provided with a projector / receiver (vehicle-mounted head) having an LED and a photosensor in order to perform bidirectional communication with the projector / receiver of the optical beacon.
JP 2005-268925 A

In the road-to-vehicle communication system using the optical beacon, the in-vehicle device may not properly receive the downlink information from the optical beacon and may not be able to enjoy a predetermined service.
The cause of this is that when the light intensity of the LED of the light beacon light emitter / receiver decreases due to aging, the light emission panel of the light beacon light emitter / receiver becomes dirty and the light transmittance decreases, the light transmission on the in-vehicle device side is reduced. When the photosensitivity of the photo sensor of the receiver decreases due to aging, and when the signal is reflected in front of the projector / receiver of the in-vehicle device due to dirt on the windshield of the vehicle or the surrounding environment (rainfall, fog, etc.) Etc. are considered.

  However, the current in-vehicle device does not particularly grasp the reception error rate for the downlink information from the optical beacon, and does not have a function of self-determining whether road-to-vehicle communication with the optical beacon is normal. Therefore, conventionally, even when downlink information from an optical beacon is not properly received for some reason, it is assumed that an appropriate traffic information service has been obtained without the driver noticing it, and the vehicle continues to travel. There is a fear.

On the other hand, signal information and distance information to a stop line are included as downlink information from an optical beacon, and a safe driving support system that performs vehicle brake control, deceleration instructions, etc. using this information has been proposed. (For example, Japanese Patent Application Nos. 2006-121692 and 2006-121700).
If the downlink information includes information for such safe driving support, if the driver continues driving without noticing that the appropriate downlink information has not been received, the safe driving is incomplete. The support system will continue and may be dangerous.

  In view of such circumstances, the present invention enables a vehicle-to-vehicle device to determine whether or not downlink information is good and allows a driver to determine whether maintenance is necessary or not, and an optical beacon used therefor. An object is to provide an in-vehicle device and a vehicle.

  The 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 having a light emitter / receiver in which a downlink region is set in a predetermined range of the road, and the in-vehicle device and the optical beacon. A vehicle-to-vehicle communication system that performs two-way communication using an optical signal with a light emitter / receiver of the optical receiver, wherein the optical beacon starts to transmit vehicle ID information for a specific vehicle in a minimum frame constituting downlink information. A communication control unit that stores the total number of frames from the vehicle, and the vehicle-mounted device calculates a frame reception rate based on the total number of frames included in the minimum frame, and determines a communication state of road-to-vehicle communication. It has the determination part which determines pass / fail.

  According to this road-to-vehicle communication system, the communication controller of the optical beacon stores the total number of frames from the start of sending vehicle ID information for a specific vehicle in the minimum frame constituting the downlink information. The in-vehicle device that has received the link information can grasp the total number of frames from the time point when the vehicle ID information is transmitted by reading the data of the minimum frame constituting the downlink information.

Therefore, if the frame reception rate is calculated based on the total number of frames and a determination unit for determining whether the communication state of road-to-vehicle communication is good or not is provided in the in-vehicle device, a defect in downlink information is automatically detected. be able to.
Then, by providing the in-vehicle device with an output unit that notifies the driver of the abnormality in the communication state determined by the determination unit, the driver can determine whether maintenance is necessary.

As the output unit, a display device that visually alerts the driver of abnormality in the communication state, a speaker that alerts the abnormality by voice, or the like can be employed.
In addition, when the in-vehicle device having the determination unit includes a support control unit that controls the safe driving support for the driver based on the support information included in the downlink information received by the in-vehicle device, the communication state is It is preferable to provide a stop unit that stops the safe driving support by the support control unit when the determination unit of the in-vehicle device determines that it is abnormal.

According to the in-vehicle device having the stop unit, when the communication state of road-to-vehicle communication is abnormal, the stop unit stops the safe driving support, so the safe driving support system continues with incomplete road-to-vehicle communication. Can be prevented in advance.
In this case as well, if an output unit is provided to notify the driver that the safe driving support has been stopped by operating the stop unit, the driver can immediately determine whether maintenance is necessary.

  As described above, according to the present invention, since the total number of frames is included in the minimum frame constituting the downlink information of the optical beacon, the total number of frames is determined by the in-vehicle device to determine whether the downlink information is good or bad. It can be used as data. For this reason, the driver can determine whether the maintenance is good or not by notifying the driver of the abnormality of the communication state determined by the quality determination of the downlink information.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[Overall system configuration]
FIG. 1 is a block diagram showing the overall configuration of a road-vehicle communication system including an optical beacon according to 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 C traveling on a road R. 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 R. Two-way communication is performed with the in-vehicle device 2 by optical communication using as a communication medium. The central device 3 is provided in the traffic control room.

[Configuration of optical beacon]
The optical beacon 4 includes a communication unit 6 that is a communication interface connected to the 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, and the controller 7 A plurality of (four in the illustrated example) projector / receiver (beacon head) 8 connected to the sensor interface is provided.
Each projector / receiver 8 is configured by housing a light emitting diode (LED) 10 and a photosensor 11 inside a housing 9 (see FIG. 3). Among them, the LED 10 emits downlink information made of near infrared rays to a communication area A described later, and the photo sensor 11 receives uplink information made of near infrared rays from the in-vehicle device 2.

FIG. 2 is a plan view of the optical beacon 4.
As shown in FIG. 2, 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. The plurality of projectors / receivers 8 are provided, and one beacon controller 7 serving as a control unit that collectively controls these projectors / receivers 8 is provided.
The beacon controller 7 includes a programmable microcomputer having a CPU, a memory (RAM), and a storage device (ROM). The beacon controller 7 is a two-way communication with the central device 3 by the communication unit 6, and the in-vehicle device 2 by each projector / receiver 8. It functions as a communication control unit that controls road-to-vehicle communication. The contents of road-to-vehicle communication by the beacon controller 7 will be described later.

The beacon controller 7 is installed on a support column 12 erected on the side of the road, and each projector / receiver 8 is attached to an installation bar 13 installed horizontally on the road R side from the support column 12, and each lane on the road R. Arranged immediately above R1 to R4.
The LED 10 of each projector / receiver 8 emits near-infrared light toward the upstream side of the lanes R <b> 1 to R <b> 4, and thereby a communication area for performing road-to-vehicle communication with the in-vehicle device 2. A is set on the upstream side (right side in FIG. 2) of the light projector / receiver 8.

FIG. 3 is a side view showing the communication area A of the optical beacon 4.
As shown in FIG. 3, this communication area A is a downlink area (area provided with a solid line hatching in FIG. 3) DA in which a projector / receiver 20 of the vehicle-mounted device 2 described later can receive downlink information. The optical transmitter / receiver 8 of the optical beacon 4 is composed of an uplink area (area provided with broken-line hatching in FIG. 3) UA from which uplink information can be received.

In the “near-infrared interface standard” of the optical beacon (optical vehicle detector) 4, the uplink area UA overlaps with the upstream part (right side part of FIG. 3) of the downlink area DA in the vehicle traveling direction, The upstream end c of the downlink area DA and the uplink area UA coincide with each other.
Therefore, the vehicle traveling direction length of the downlink area DA matches the same direction length of the entire communication area A.

In the above standard, in the case of the optical beacon 4 for general roads, the downstream end a of the downlink area DA is located 1.0 to 1.3 m upstream immediately below the light emitter / receiver 8, and the downlink area The distance from the downstream end a of the DA to the downstream end b of the uplink area UA is defined as 2.1 m, 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. Has been. In this case, the total length of the communication area A in the vehicle traveling direction is 3.7 m.
However, the vehicle traveling direction lengths of the areas DA and UA are not limited to the above numerical values. Further, as indicated by a virtual line in FIG. 3, the upstream end c ′ of the downlink area DA may be positioned further upstream (right side in FIG. 3) than the upstream end c of the uplink area.

[Configuration of in-vehicle device and vehicle]
FIG. 4 is a schematic configuration diagram of the in-vehicle device 2 that communicates with the optical beacon 4 and a vehicle C in which the in-vehicle device 2 is mounted.
As shown in FIG. 4, the 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 electronic control for integrated control of each part of the vehicle C. A device (ECU) 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 are provided. The ECU 16 performs various controls on the vehicle C such as drive control of the engine 17 based on the accelerator operation of the driver and braking control based on the brake operation.

The in-vehicle device 2 includes an in-vehicle computer 19, a projector / receiver (in-vehicle head) 20 connected to the sensor interface of the computer 19, and a display 21 and a speaker device 22 as a human interface for the driver of the passenger seat. Yes.
The light emitter / receiver 20 of the in-vehicle device 2 also includes a light emitting diode (LED) and a photosensor (not shown), similar to the light receiver / receiver 8 of the optical beacon. Among these, the LED emits uplink information composed of near infrared rays, and the photosensor receives downlink information composed of near infrared rays emitted to the communication area A.

The in-vehicle computer 19 includes a programmable microcomputer having a CPU, a memory (RAM), and a storage device (ROM), and performs control processing of road-to-vehicle communication with the optical beacon 4 by the light projector / receiver 20.
The in-vehicle computer 19 stores a program for executing each predetermined function in a storage device, and includes a determination unit 23, a support control unit 24, and a stop unit 25 as functional units executed by the program.

[Processing content of in-vehicle computer]
The determination unit 23 calculates the reception rate r based on the total number n of the minimum frames 31 of the downlink information 30 described later.
The reception rate r is calculated as r = n1 / n, where n1 is the number of minimum frames 31 that can be received and n is the total number of frames. The determination unit 23 compares the reception rate r with a predetermined threshold set in advance, and determines that the communication state of road-to-vehicle communication is defective (abnormal) when the reception rate r is lower than the threshold. If it is equal to or greater than the threshold, it is determined that the communication state of road-to-vehicle communication is good.

When the determination unit 23 determines that the communication state is abnormal, the in-vehicle computer 19 displays a warning display to that effect on the display 21 or causes the speaker device 22 to output a sound output to that effect. To inform the driver. Note that both the display 21 and the speaker device 22 may notify the driver of an abnormal communication state.
The assistance control unit 24 controls safe driving assistance for the driver based on the assistance information included in the downlink information. This safe driving support includes, for example, deceleration control of the vehicle C based on support information such as signal information and distance information, and notification control to the driver.

This signal information is timing information at which a signal on the downstream side of the optical beacon 4 changes, and the distance information is length information from the downlink area DA to a predetermined position (for example, a stop line) on the downstream side of the optical beacon 4. It is.
When the signal information and the distance information are included in the downlink information, the support control unit 24 sets the brake device 18 to the ECU 16 so that the vehicle C does not enter the intersection when the signal changes to red. The display 21 or the speaker device 22 informs the driver that the vehicle C is decelerated and the signal changes to red.

Note that Japanese Patent Application No. 2006-121692 already proposed by the present applicant describes that the accuracy of the distance information is improved by narrowing the communication area A than usual, and Japanese Patent Application No. 2006-121700 describes the distance. It is described that the accuracy of the distance information is improved by correcting the information on the in-vehicle device 2 side.
If these techniques are applied to the support control unit 24 of the present embodiment to increase the accuracy of the distance information, the vehicle C can be accurately stopped at a predetermined position.

  The stop unit 25 of the in-vehicle computer 19 stops the safe driving support by the support control unit 24 when the determination unit 23 determines that the communication state is abnormal. In addition, when the stop unit 25 is activated and the safe driving support is stopped, the in-vehicle computer 19 displays a warning display to that effect on the display 30 or outputs a sound output to that effect from the speaker device 22. Speak and notify the driver. Note that both the display 21 and the speaker device 22 may notify the driver of the stop of safe driving support.

The display 21 includes an in-vehicle display that constitutes an image display unit of a navigation device or a television device, a head-up display that displays a figure on the windshield surface of the vehicle body 15, and the like. The speaker device 22 includes a speaker provided on the front panel or door of the vehicle body 15 of the passenger seat.
The display 21 and the speaker device 22 function as an output unit that notifies the driver of an abnormal communication state and the accompanying stop of safe driving assistance.

[Road-to-vehicle communication]
FIG. 5 shows a two-way road-to-vehicle communication procedure performed between the light projecting / receiving device 8 of the optical beacon 4 and the light projecting / receiving device 20 of the in-vehicle device 2 in the communication area A. Hereinafter, the contents of the road-to-vehicle communication will be described with reference to FIG.
First, the beacon controller 7 of the optical beacon 4 receives first downlink information 28 including lane notification information from each projector / receiver 8 corresponding to each lane R1 to R4 as the first information before downlink switching. Is continuously transmitted to the downlink area DA of each lane R1 to R4 at a predetermined transmission cycle (F1 in FIG. 5). At this stage, the vehicle ID is not yet stored in the lane notification information.

  When the vehicle C equipped with the vehicle-mounted device 2 enters the upstream portion of the downlink area DA, the light emitter / receiver 20 of the vehicle-mounted device 2 receives the first downlink information 28 including the lane notification information (no vehicle ID). . At this time, the in-vehicle computer 19 of the in-vehicle device 2 recognizes that the vehicle C exists in the communication area A. Thereafter, the in-vehicle computer 19 starts transmission of the uplink information 29 (F2 in FIG. 5), and transmits this uplink information 29 to the projector / receiver 8 of the optical beacon 4 at a predetermined transmission cycle (in FIG. 5). F3).

The in-vehicle computer 19 transmits the uplink information 29 in the uplink area UA (see FIG. 3), stores the specific vehicle ID in the vehicle C in the uplink information 29, and transmits the uplink information 29. .
In addition, when the vehicle-mounted computer 19 has the travel time information between beacons, this information is also included in the uplink information 29. The in-vehicle computer 19 continues to transmit the uplink information 29 until it recognizes that the beacon controller 7 of the optical beacon 4 has switched the downlink.

On the other hand, when the projector / receiver 8 of the optical beacon 4 receives the uplink information 29 (F4 in FIG. 5), the beacon controller 7 has the vehicle ID information as the second information after the downlink switching. 2 starts transmission of the second downlink information 30 including lane notification information for F2 (F5 in FIG. 5), and repeats transmission of this downlink information 30 as much as possible within a predetermined time (F6 in FIG. 5). .
The lane notification information includes a field for storing a vehicle ID for each lane R1 to R4, and a lane number can be assigned to each vehicle ID. For this reason, the vehicle-mounted computer 19 of each vehicle C traveling in different lanes R1 to R4 determines which lane R1 to R4 the host vehicle is in by determining which of the storage fields includes the vehicle ID of the host vehicle. Can recognize if you are driving.

The second downlink information 30 includes, in addition to the lane notification information including the vehicle ID, traffic jam information, section travel time information, event regulation information, the support information for safe driving support for the driver, and the like. ing.
The support information includes the signal information, which is timing information at which the downstream signal of the optical beacon 4 changes, and length information from the downlink area DA to a predetermined position (for example, a stop line) downstream of the optical beacon 4. The distance information etc. which are are included.

As shown in FIG. 5, the second downlink information 30 includes a single or a plurality of minimum frames 31. According to the “near infrared interface standard”, the data amount of the minimum frame 31 is defined as a total of 128 bytes, and 5 bytes are allocated to the header portion 32 and 123 bytes are allocated to the actual data portion 33.
Therefore, in the present embodiment, the storage unit 34 (1 to 2 bytes) for the total number of frames n is provided in the actual data portion 33 of the minimum frame 31.

  This total frame number n is the minimum frame when viewed from the transmission start time (T0 in FIG. 5) of the second downlink information 30 (including vehicle notification information having a vehicle ID for each lane R1 to R4). Reference numeral 31 indicates the frame number. The beacon controller 7 of the optical beacon 4 stores the total number n of frames in the storage unit 34 of each minimum frame 31 and transmits the frame 31 from the light projector / receiver 8.

According to the standard, the second downlink information 30 can be composed of 1 to 80 minimum frames 31, and the transmittable time is set to 250 ms. The downlink information 30 is composed of an arbitrary number of minimum frames 31 corresponding to the amount of information to be transmitted, and is repeatedly transmitted within the range of the transmittable time.
The transmission period of the minimum frame 31 is about 1 ms. Therefore, for example, when one downlink information 30 is composed of the three minimum frames 31, the transmission period of the downlink information 30 is about 3 ms. Therefore, the downlink information 30 has a predetermined transmittable time (250 m). ) Will be repeatedly transmitted about 80 times during this period.

The in-vehicle computer 19 of the in-vehicle device 2 recognizes the downlink switching in the optical beacon 4 at the time when the second downlink information 30 is received (F7 in FIG. 6), and at this time, transmits the uplink information 29. Stop.
Further, as described above, when the in-vehicle computer 19 receives the second downlink information 30, the determination unit 23 determines the frame based on the total frame number n included in the minimum frame 31 of the downlink information 30. The reception rate r (= n1 / n) is calculated, and the quality of the communication state of road-to-vehicle communication is determined (F8 in FIG. 5).

  Thus, according to the optical beacon 4 of this embodiment, the beacon control unit 7 has started to send vehicle ID information for the specific vehicle C to the minimum frame 31 constituting the second downlink information 30. Since the total number of frames n is stored, the vehicle-mounted computer 19 of the vehicle-mounted device 2 that has received the downlink information 30 reads the data of the minimum frame 31 that constitutes the downlink information 30, thereby The total number n of frames from the time of transmission can be grasped.

Further, according to the in-vehicle device 2 of the present embodiment, the determination unit 23 of the vehicle computer 19 calculates the frame reception rate r based on the total number of frames n, and determines the quality of the communication state of road-to-vehicle communication. It is possible to automatically detect a defect in the downlink information 30.
Moreover, according to the vehicle-mounted device 2 of the present embodiment, since the display 21 and the speaker device 22 for notifying the driver of the abnormality of the communication state determined by the determination unit 23 are provided, the driver who has boarded the vehicle C performs maintenance. The necessity can be easily determined.

  Furthermore, according to the in-vehicle device 2 of the present embodiment, the support control unit 24 that controls the safe driving support for the driver based on the support information included in the second downlink information 30, and the communication state is abnormal. Since the stop unit 25 that stops the safe driving support by the support control unit 24 when the determination unit 23 determines, the safe driving support system is prevented from continuing in an incomplete road-to-vehicle communication state. can do.

The present invention is not limited to the above embodiment.
For example, the functional units 23, 24, and 25 of the in-vehicle computer 19 can be incorporated into the electronic control unit (ECU) 16 of the vehicle C.
Although it is not standard, the storage unit 34 for the total number of frames n can be provided in a portion other than the actual data unit 33 of the minimum frame 31.

Furthermore, in the above embodiment, the total number of frames n is stored in each of the minimum frames 31, but it is not necessary to store in all the minimum frames 31, and the total number of frames n is set for each of the plurality of minimum frames 31. It can also be stored.
For example, when the beacon controller stores the total number of frames n for every 10 frames of the minimum frame 31, after the projector / receiver 20 of the in-vehicle device 2 receives the minimum frame 31 in which the total number of frames ns = 10 is received. If the in-vehicle computer 19 counts the number of frames n1 received until the total number of frames ne = 20 is received, the reception rate r can be calculated by the equation r = n1 / (ne−ns). .

It is a block diagram which shows the whole structure of the road-vehicle communication system of this invention. It is a top view of the optical beacon of the present invention. It is a side view which shows the communication area | region of the said optical beacon. It is a schematic block diagram of the vehicle equipment which communicates with an optical beacon, and the vehicle by which this vehicle equipment is mounted. It is a conceptual diagram which shows the procedure and data content of the road-vehicle communication performed in a communication area.

Explanation of symbols

1 Traffic control system 2 In-vehicle device 4 Optical beacon 7 Beacon controller (communication controller)
8 Emitter / receiver (beacon side)
15 Car body 16 Electronic control unit (ECU)
19 On-vehicle computer 20 Emitter / receiver (on-vehicle device side)
21 Display (output unit)
22 Speaker device (output unit)
23 Determination unit 24 Support control unit 25 Stop unit 28 First downlink information 29 Uplink information 30 Second downlink information 31 Minimum frame A Communication area C Vehicle R Road DA Downlink area UA Uplink area

Claims (8)

An in-vehicle device of a vehicle traveling on a road; and an optical beacon having a light emitter / receiver having a downlink area set in a predetermined range of the road, and light is transmitted between the in-vehicle device and the light emitter / receiver of the optical beacon. A road-vehicle communication system that performs bidirectional communication using signals,
The optical beacon has a communication control unit that stores the total number of frames from the start of sending vehicle ID information for a specific vehicle in a minimum frame constituting downlink information,
The vehicle-mounted device has a determination unit that calculates a frame reception rate based on the total number of frames included in the minimum frame and determines whether the communication state of road-to-vehicle communication is good or bad. Inter-vehicle communication system. 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 projector / receiver in which a downlink area is set in a predetermined range of the road,
A road-to-vehicle communication method characterized by storing the total number of frames from the start of sending vehicle ID information for a specific vehicle in a minimum frame constituting downlink information and transmitting the downlink information to the in-vehicle device. . An optical beacon having a light emitter / receiver in which a downlink area is set in a predetermined range of a road, and used for road-to-vehicle communication that performs two-way communication using an optical signal between the light emitter / receiver and an in-vehicle device of a vehicle. In the optical beacon that
An optical beacon having a communication control unit for storing the total number of frames from the start of sending vehicle ID information for a specific vehicle with respect to a minimum frame constituting downlink information. An in-vehicle device for a vehicle traveling on a road, which is used for road-to-vehicle communication that performs two-way communication using an optical signal with an optical beacon transmitter / receiver in which a downlink area is set in a predetermined range of the road For in-vehicle devices,
In-vehicle characterized by having a determination unit that calculates the frame reception rate based on the total number of frames included in the minimum frame constituting the downlink information and determines whether the communication state of road-to-vehicle communication is good or bad Machine.   The in-vehicle device according to claim 4, further comprising an output unit that notifies the driver of an abnormality in the communication state determined by the determination unit of the in-vehicle device.   A support control unit that performs control of safe driving support for the driver based on the support information included in the received downlink information, and a safe driving support by the support control unit when the determination unit determines that the communication state is abnormal The in-vehicle device according to claim 4 provided with the stop part which stops.   The in-vehicle device according to claim 6, further comprising an output unit that notifies a driver that the stop unit has been activated and safe driving support has been stopped.   A vehicle comprising: a vehicle body; a control device that controls driving and braking of the vehicle body; and the vehicle-mounted device according to claim 4 mounted on the vehicle body.

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