JP2009205444A - Road-vehicle communication system and optical beacon therefor, and abnormality determining method of light receiving part - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To easily prevent degrading in reliability in road-vehicle communication caused by abnormality of a light receiving part by autonomously determining, in an infrastructure side, abnormalities of an optical beacon of the light receiving part. <P>SOLUTION: The road-vehicle communication system executes interactive communication by an optical signal between a vehicle-mounted device 2 and a light emitter and receiver 8 of the optical beacon 4 in a communication area A. The system includes: the light receiving part 9 mounted in the light emitter and receiver 8 for receiving uplink information 35 transmitted by the vehicle-mounted device 2 in an uplink area UA included in the communication area A; and a determining part 16 for temporarily pulling up an amplification factor for an amplifying circuit 42 of the light receiving part 9, and performing an abnormality determination processing of the light receiving part 9, depending on whether or not a reception level corresponding to the pulling-up is obtained. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a road-to-vehicle communication system that performs bidirectional communication using an optical signal between an optical beacon installed on a road side and an in-vehicle device mounted on a vehicle, an optical beacon used therefor, and an optical receiving unit thereof The present invention relates to an abnormality determination method.

As a traffic information service using a road-to-vehicle communication system, so-called VICS (Vehicle Information and Communication System: registered trademark of Road Traffic Information Communication System Center) using optical beacons, radio beacons or FM multiplex broadcasting has already been developed. ing. 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 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 beacon head (projector / receiver) that performs bidirectional communication with an in-vehicle device. The projector / receiver includes a light-emitting diode (LED) that transmits downlink information and an in-vehicle device. And a photodiode (PD) for receiving the uplink information.
For example, as shown in FIG. 8, in the beacon head (projector / receiver) 108 of the optical beacon 104, the communication area A is usually set on the upstream side from directly below. According to the “near-infrared interface standard” of the optical beacon (optical vehicle sensor) 104, the uplink area UA overlaps with the upstream part (right side part in FIG. 8) of the downlink area DA in the vehicle traveling direction, The upstream ends of the downlink area DA and the uplink area UA are made to 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. Further, according to 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 on the upstream side of 1.0 to 1.3 m immediately below the beacon head 108, and the downlink The distance from the downstream end a of the area 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 1.6 m. It is prescribed. Accordingly, in this case, the total length of the communication area A in the vehicle traveling direction is 3.7 m.

  However, in practice, the currently set upstream end of the downlink area DA is often set on the upstream side (for example, c ′ in FIG. 8) relative to the upstream end c of the uplink area UA.

In the road-to-vehicle communication system, the following communication is performed between the optical beacon 104 and the vehicle-mounted device 102. First, the optical beacon 104 first always transmits the first downlink information including the lane notification information (no vehicle ID) to the downlink area DA of the road at a predetermined transmission cycle.
When the vehicle enters the downlink area DA and the projector / receiver (vehicle-mounted head) of the vehicle-mounted device 102 mounted on the vehicle receives the first downlink information, the vehicle-mounted device 102 receives the own vehicle. Transmission of uplink information including lane notification information storing the ID is started.

  Then, when the beacon head 108 of the optical beacon 104 receives the uplink information, the optical beacon 104 performs downlink switching, and the second down including the lane notification information having the vehicle ID with respect to the in-vehicle device 102. Start sending link information. This second downlink information is repeatedly transmitted as much as possible within a predetermined time and is received by the in-vehicle device 102.

  By such a road-to-vehicle communication system using an optical beacon, for example, a specific position in the communication area A (for example, the upstream end in the vehicle traveling direction) is regarded as the position of the vehicle (onboard unit 102), and the downstream from the specific position. The “distance information” to the predetermined position P0 on the side (for example, the stop line 40 provided in front of the traffic light) is included in the second downlink information, and the in-vehicle device 102 that has received this distance information Using the distance information, the vehicle may be braked so as to be forcibly stopped before the stop line 40, or the driver may be advised to stop or decelerate to provide safe driving assistance to the driver. (For example, refer to Patent Documents 2 and 3).

However, when such safe driving support is performed, there are the following problems.
Currently, the communication area A of the optical beacon 104 that is actually operated, especially the uplink area UA, receives the uplink information from the in-vehicle device 102 more reliably, for example, as shown by a virtual line in FIG. In many cases, the area is considerably wider than the official area defined by the standard (for example, an area indicated by Δdb′c ′). Similarly, the downlink area DA is often set more than the standard area.

Thus, if the communication area A is wider than the official area, the difference between the specific position in the communication area A that is the starting point of the “distance information” and the actual position when the vehicle receives the distance information Is likely to increase, and the accuracy of the distance information decreases.
For this reason, the accuracy of the safe driving support using the distance information is similarly reduced. For example, although the vehicle is braked so as to stop before the stop line 40 by the safe driving support function, A situation may occur in which the stop line 40 is exceeded and the vehicle stops.

JP 2005-268925 A JP 2007-293660 A JP 2007-317166 A

  Therefore, the present inventor accurately provides safe driving support to the driver even when the uplink region is widely set in the vehicle traveling direction when performing safe driving support by the road-to-vehicle communication system using the optical beacon. In order to perform well, by dividing the uplink region in the vehicle traveling direction, a plurality of divided regions are set, and a plurality of light receiving units composed of photodiodes or the like that receive uplink information corresponding to each divided region, An optical beacon that has been mounted on a projector / receiver has already been proposed (see the specification of Japanese Patent Application No. 2007-20910).

In the case of the above-described optical beacon having a plurality of optical receivers corresponding to each divided region of the uplink region (hereinafter sometimes referred to as “PD split type” optical beacon), one of the plurality of optical receivers Even if there is an abnormality, road-to-vehicle communication is usually completed well as described below.
Here, the abnormality of the optical receiver includes not only failure of the photodiode (PD) itself but also disconnection of circuit wiring connected to the diode, failure of the amplifier, and the like.

Here, for example, if there is an abnormality in one of the four optical receivers, an optical beacon is transmitted even if a certain vehicle transmits uplink light in the divided area corresponding to the abnormal optical receiver. Then, since the uplink light is not recognized, switching of the downlink by the optical beacon is not performed.
Therefore, the vehicle transmits uplink light again when a time corresponding to an uplink transmission interval (for example, 30 ms interval) has elapsed after uplink transmission.

At this time, if the vehicle transmits uplink light in a divided area corresponding to a normal light receiving unit, the uplink light at that time is recognized by the optical beacon, thereby switching the downlink and switching the vehicle-mounted device Later downlink information can be received.
In this way, if one of the plurality of light receiving units corresponding to each divided area is broken, road-to-vehicle communication ends as a result, so that the abnormality of the light receiving unit remains unnoticeable. turn into.

Also, if there is an abnormal optical receiver such as a failure, the probability that the uplink light is recognized by the optical beacon will decrease accordingly, so if the vehicle is traveling at a very high speed, There may be an increase in the number of cases where inter-vehicle communication fails.
In particular, when the optical receiving unit corresponding to the most upstream divided area fails, the influence on the failure of road-to-vehicle communication increases. The reason is that in most vehicles, communication is established with the first uplink light transmitted in the vicinity of the upstream end of the uplink region, and road-to-vehicle communication is completed with this uplink light as the beginning.

For this reason, when the optical receiver corresponding to the most upstream divided area where it is easy to receive the uplink light first fails, even after the vehicle-mounted device passes through the upstream end of the uplink area, it is 2 degrees and 3 degrees. Uplink light must be transmitted.
Therefore, the point at which downlink switching is performed by that amount is biased toward the downstream side, and the number of downlink frames that can be received by the in-vehicle device after downlink switching is reduced, thereby ensuring the reliability and reliability of road-to-vehicle communication. There is a problem that will decrease.

On the other hand, in the above-described PD split type optical beacon, in order to individually determine whether or not each light receiving unit mounted on the projector / receiver is out of order, for example, a light emitting device (on-vehicle device) installed in each split region However, it can be performed by transmitting uplink light from each other and checking whether or not each optical receiving unit properly receives the uplink light.
However, such inspection work requires a minimum of two workers and is difficult to perform, and there is a problem that it may cause traffic congestion because it involves traffic regulation during the work.

  Even if there is only one light receiving unit in the light emitter / receiver, if an abnormality occurs in the light receiving unit, road-to-vehicle communication cannot be performed at all, or the number of downlink frames is reduced and road-to-vehicle communication is not performed. Since there is no change in the reliability and reliability, there is no change in the point that it is desirable to design the optical beacon to be fail-safe so that the abnormality of the optical receiver can be autonomously determined on the infrastructure side. .

  In view of the above-mentioned problems, the present invention autonomously determines an abnormality of an optical receiving unit of an optical beacon on the infrastructure side, and easily prevents a decrease in reliability of road-to-vehicle communication due to an abnormality of the optical receiving unit. The purpose is to do.

  A road-to-vehicle communication system according to the present invention (Claim 1) includes an in-vehicle device of a vehicle traveling on a road, and an optical beacon having a projector / receiver in which a communication area is set in a predetermined range of the road, A road-to-vehicle communication system that performs bidirectional communication using an optical signal between the vehicle-mounted device and the light beacon light-receiving / receiving device, and the uplink transmitted by the vehicle-mounted device in an uplink region included in the communication region In order to receive information, an optical receiver provided in the light projector / receiver and an amplification factor for the amplifier circuit of the optical receiver are temporarily raised, and whether or not a reception level commensurate with this increase can be obtained. A determination unit that performs an abnormality determination process of the optical receiving unit.

According to the road-to-vehicle communication system of the present invention, the determination unit temporarily increases the amplification factor of the optical reception unit with respect to the amplification circuit, and determines whether the optical reception unit is abnormal depending on whether or not a reception level corresponding to the increase is obtained. Therefore, the abnormality occurring in the optical receiver can be autonomously determined on the infrastructure side.
For this reason, even if it does not perform the inspection work accompanied by traffic regulation, it is possible to find an abnormality in the optical receiver, and it is possible to easily prevent a decrease in the reliability of road-to-vehicle communication due to an abnormality in the optical receiver.

By the way, in the road-to-vehicle communication system of the present invention, if the determination unit performs the abnormality determination process in a time zone in which the vehicle passes frequently, uplink information may not be received correctly.
Therefore, it is preferable that the determination unit performs the abnormality determination process only when the vehicle is not traveling in the communication area.
In this case, since the determination unit performs the abnormality determination process only when no vehicle is present in the communication area, it is possible to prevent a reception failure associated with performing the abnormality determination process.

In the road-to-vehicle communication system of the present invention, the determination unit may perform the abnormality determination process only for the optical reception unit that does not receive uplink information within a predetermined time. .
In this case, since the abnormality determination process is performed only for the optical receiver that has a high probability of failure, the frequency can be reduced compared with the case where the process is performed uniformly and regularly. Can be done automatically.

Furthermore, in the road-vehicle communication system according to the present invention, the determination unit may perform the abnormality determination process based on an artificial execution signal from the outside.
In this case, since the optical receiver abnormality determination process is performed only when an artificial execution signal is received from the outside, the frequency can be reduced compared to the case where the process is performed uniformly and regularly. The processing can be performed efficiently.

In the road-to-vehicle communication system of the present invention, when the light receiving unit is provided in the light emitter / receiver corresponding to a plurality of divided areas obtained by dividing the uplink area in the vehicle traveling direction, Preferably, the determination unit performs the abnormality determination process on each of the plurality of optical reception units.
In this case, since the determination unit performs an abnormality determination process for each of the plurality of light receiving units, since there are a plurality of light receiving units in one projector / receiver, it is difficult to find the abnormality individually. Even in an optical beacon, an abnormality that has occurred in the optical receiver can be individually determined.

In the road-to-vehicle communication system according to the present invention, when the light emitter / receiver is installed corresponding to each lane of the road of a plurality of lanes, the determination unit is It is preferable to perform the abnormality determination process on each of the optical receivers (claim 6).
In this case, since the determination unit performs the abnormality determination process for the light receiving unit of each projector / receiver provided for each lane, the abnormality generated in the light receiving unit is individually determined for each projector / receiver. be able to.

The optical beacon of the present invention (Claim 7) is an optical beacon that is a main component of the road-to-vehicle communication system (Claim 1), and has the same operational effects as the system.
Moreover, the abnormality determination method (Claim 8) of the optical receiver of the present invention is an abnormality determination method performed in the road-to-vehicle communication system (Claim 1), and has the same effects as the system.

  As described above, according to the present invention, the abnormality of the optical receiving unit of the optical beacon can be determined autonomously on the infrastructure side, so that the abnormality of the optical receiving unit can be found without performing inspection work with traffic regulation. Can do. For this reason, it is possible to easily prevent a decrease in reliability of road-to-vehicle communication due to an abnormality in the optical receiver.

[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 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. The optical beacon 4 performs bidirectional communication with the in-vehicle device 2 by optical communication using near infrared rays 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 beacon controller 7. And a plurality (four in the illustrated example) of beacon heads (projector / receiver) 8 connected to the sensor interface.
Each beacon head 8 houses a light emitting diode (LED) 10 and a light receiving unit 9 including a photodiode (PD) 11 in a housing.

Among these, the light emitting diode 10 emits downlink light DO (an optical signal constituting the downlink information 34 and 36) made of near infrared light to a communication area A to be described later, and the photodiode 11 An uplink light UO (an optical signal constituting the uplink information 35) made of infrared rays is received.
The beacon head 8 is provided with a plurality (four in the illustrated example) of photodiodes 11 corresponding to each of the divided areas UA1 to UA4 of the uplink area UA, which will be described later. Together with an amplifier circuit that amplifies the output signal, the optical receiver 9 for the uplink optical UO is configured (see FIG. 7).

As shown in FIG. 3, a vehicle detector 12 for detecting the number of passing vehicles C is provided on the upstream side of the optical beacon 4. The vehicle sensor 12 includes a transmitter / receiver that transmits a detection wave such as a near infrared ray or an ultrasonic wave and receives a reflected wave thereof, and irradiates the detection wave intermittently (for example, every 50 milliseconds) toward the road surface. The presence of the vehicle C is sensed by determining whether the reflected wave of the detected wave is from the vehicle C or from the road surface.
The detection signal of the vehicle sensor 12 is transmitted to the communication unit 6 of the optical beacon 4, and the determination unit 16 of the beacon controller 7 described later determines whether the vehicle C exists in the communication area A. Used as data.

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 beacon heads 8 provided and a single beacon controller 7 serving as a control unit that collectively controls the beacon heads 8.
The beacon controller 7 is composed of a programmable microcomputer having a CPU, a memory (RAM), and a storage device (ROM). It has a function as a communication control unit that performs road-to-vehicle communication with the machine 2.
The contents of road-to-vehicle communication by the beacon controller 7 will be described later.

The beacon controller 7 stores a computer program for executing each predetermined function in a storage device. In addition to the function unit as the communication control unit, the beacon controller 7 further includes a plurality of function units to be executed by the program. A determination unit 16 that performs an abnormality determination process for detecting whether or not an abnormality has occurred in any one of the photodiodes 11 is provided (see FIGS. 1, 2, and 4).
The processing content of the determination unit 16 will also be described later.

The beacon controller 7 is installed on a support column 13 standing on the side of the road, and each beacon head 8 is attached to an installation bar 14 installed horizontally on the road R side from the support column 13, and each lane R1 of the road R. It is arrange | positioned just above -R4.
The LED 10 of each beacon head 8 emits near-infrared rays toward the upstream side in the vehicle traveling direction rather than directly below the lanes R1 to R4, thereby performing road-to-vehicle communication with the in-vehicle device 2. Is set on the upstream side of the head 8.

[About communication area]
FIG. 3 is a side view showing the communication area A of the optical beacon 4.
As shown in FIG. 3, the communication area A of the optical beacon 4 is a downlink area in which the in-vehicle head 27 which is the light emitter / receiver of the in-vehicle device 2 can receive downlink information (in FIG. 3, a solid line hatching is provided). DA) and an uplink area (area provided with broken-line hatching in FIG. 3) UA in which the beacon head 8 of the optical beacon 4 can receive uplink information from the in-vehicle head 27.

The downlink area DA is set in a range indicated by Δdac having apexes at the light emitting / receiving position d of the beacon head 8 and the positions a and c on the road R. The uplink area UA is set in the range indicated by Δdbc with the position d and the positions b and c on the road R as vertices.
Accordingly, the upstream end c of the downlink area DA and the uplink area UA coincide with each other, and the uplink area UA overlaps with the upstream portion (right side portion in FIG. 3) of the downlink area DA in the vehicle traveling direction. Further, the vehicle traveling direction length of the downlink area DA coincides with the same direction length of the entire communication area A.

According to the “near infrared interface standard” of the optical beacon (optical vehicle sensor) 4, the formal area dimensions of the downlink area DA and the uplink area UA are defined. In this rule, in the case of an optical beacon 4 for a general road, the downstream end a of the downlink area DA is located 1.0 to 1.3 m upstream immediately below the beacon head 8 and is downstream of the downlink area DA. The distance from the end a to the downstream end b of the uplink area UA is defined as 2.1 m.
Further, 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. Accordingly, the total length of the official communication area A in the vehicle traveling direction (the length between ac) is 3.7 m.

However, in this embodiment, the distance from the downstream end b of the uplink area UA to the upstream end c of the area UA is set longer to the upstream side and the downstream side than the above definition. As a result, the uplink area UA extends in the vehicle traveling direction from the above definition, and the downlink area DA also extends in the vehicle traveling direction from the above definition.
Thus, when the uplink area UA and the downlink area DA are widened, the certainty of transmission / reception of the uplink information 35 and the downlink information 34 and 36 between the in-vehicle device 2 and the optical beacon 4 is increased.

Further, the uplink area UA is composed of divided areas UA1 to UA4 obtained by dividing the area UA in the vehicle traveling direction to such an extent that the traveling position of the vehicle C can be specified. Specifically, the uplink area UA of the present embodiment is divided into four by three boundary lines (boundary portions) BL having a position d as an upper end and positions e1 to e3 on the road R as lower ends. Yes.
The four photodiodes 11 (see FIG. 1) provided in the beacon head 8 use the divided areas UA1 to UA4 of the uplink area UA as reception areas. Therefore, for example, the uplink light UO transmitted from the in-vehicle head 27 in the divided area UA1 located on the most upstream side is received by the photodiode 11 corresponding to the divided area UA1.

Further, as shown in FIG. 3, the vehicle sensor 12 for detecting the traffic volume sends detection waves such as near infrared rays directly below the respective lanes R1 to R4. A sensing area K of the vehicle sensor 12 is arranged upstream of the area A.
The vehicle detector 12 provided for each of the lanes R1 to R4 detects the presence of the vehicle C by detecting a reflected wave when the vehicle C passes through the sensing region K corresponding to each of the lanes R1 to R4. .

The beacon controller 7 receives an OFF signal from the vehicle detector 12 when the vehicle C does not exist, receives an ON signal when the vehicle C exists, and counts the number of ON signals. The number of vehicles C (traffic volume) passing through each lane R1 to R4 is detected.
Further, the beacon controller 7 can detect not only the traffic volume but also the traveling speed of the vehicle C based on the duration of the ON signal (the occupation time during which the vehicle detector 12 continues to sense the presence of the vehicle C). ing.

[Configuration of in-vehicle device and vehicle]
FIG. 4 is a schematic configuration diagram of the in-vehicle device 2 that performs road-to-vehicle communication 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 21 having a driver's boarding seat (not shown), the vehicle-mounted device 2 mounted on the vehicle body 21, and electronic control that integrally controls each part of the vehicle C. An apparatus (ECU) 22, an engine 23 that drives the vehicle body 21, a brake device 24 that brakes the vehicle body 21, and a speed detector 25 that constantly detects the current speed of the vehicle C are provided.

The ECU 22 performs various controls on the vehicle C, such as drive control of the engine 23 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 26, an in-vehicle head (projector / receiver) 27 connected to the sensor interface of the computer 26, a display 28 and a speaker device 29 as a human interface for the driver of the passenger seat. Yes.

The vehicle-mounted head 27 includes a light emitting diode (LED) and a photodiode (not shown), like the light beacon projector / receiver 8. Among these, the LED emits uplink information composed of near infrared rays, and the photodiode receives downlink information composed of near infrared rays emitted to the communication area A.
The in-vehicle computer 26 includes 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 27.

  The in-vehicle computer 26 stores a program for executing predetermined functions in a storage device, and includes a distance recognition unit 30, a correction unit 31, and a support control unit 32 as functional units to be executed by the program. . The processing contents of these functional units 30, 31, and 32 will be described later.

[Contents of road-to-vehicle communication]
FIG. 5 shows a two-way road-to-vehicle communication procedure performed between the beacon head 8 and the vehicle-mounted head 27 in the communication area A. Hereinafter, the contents of the road-to-vehicle communication of the present embodiment will be described with reference to FIG.
First, the beacon controller 7 of the optical beacon 4 sends the first downlink information 34 including the lane notification information from the beacon heads 8 corresponding to the lanes R1 to R4 as the first information before switching the downlink. The transmission continues 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 in-vehicle device 2 enters the actual downlink area DA, the in-vehicle head 27 of the in-vehicle device 2 receives the first downlink information 34 including the lane notification information (no vehicle ID).
At this time, the in-vehicle computer 26 of the in-vehicle device 2 recognizes that the vehicle C exists in the actual communication area A. Thereafter, the in-vehicle computer 26 starts transmission of the uplink information 35 (F2 in FIG. 5), and transmits this uplink information 35 to the beacon head 8 at a predetermined transmission cycle (uplink transmission cycle) (FIG. 5). 5 F3).

  The in-vehicle computer 26 stores a specific vehicle ID for the vehicle C in the uplink information 35 and transmits the uplink information 35. If the in-vehicle computer 26 has travel time information between beacons, this information is also uploaded. It is included in the link information 35. The in-vehicle computer 26 continues to transmit the uplink information 35 until it recognizes that the beacon controller 7 of the optical beacon 4 has switched the downlink.

  On the other hand, when the beacon head 8 of the optical beacon 4 receives the uplink information 35 (F4 in FIG. 5), the beacon controller 7 performs downlink switching, and uses the lane notification information having the vehicle ID information as the second information. The transmission of the included second downlink information 36 is started (F5 in FIG. 5), and the transmission of the second downlink information 36 is repeated 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 (FIG. 2), and a lane number can be assigned to each vehicle ID.
For this reason, the in-vehicle computer 26 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 36 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.
In this support information, in addition to signal information that is timing information for changing the color of the traffic light downstream from the optical beacon 4, length information from the uplink area UA to a predetermined position (for example, a stop line) downstream thereof. The distance information etc. which are are included.

As shown in FIG. 5, the second downlink information 36 includes a single or a plurality of minimum frames 37. According to the “near infrared interface standard”, the data amount of the minimum frame 37 is defined as a total of 128 bytes, and 5 bytes are allocated to the header portion 38 and 123 bytes are allocated to the actual data portion 39.
According to the standard, the second downlink information 36 can be composed of 1 to 80 minimum frames 37, and the transmittable time is set to 250 ms. The downlink information 36 includes an arbitrary number of minimum frames 37 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 37 is about 1 ms. Therefore, for example, when one downlink information 36 is constituted by three minimum frames 37, the transmission period of the downlink information 36 is about 3 ms. Therefore, the downlink information 36 has a predetermined transmittable time (250 ms). ) Will be repeatedly transmitted about 80 times during this period.
The in-vehicle computer 26 of the in-vehicle device 2 recognizes the downlink switching in the optical beacon 4 at the time of receiving the second downlink information 36 (F7 in FIG. 6), and transmits the uplink information 35 at this time. Stop.

As shown in FIG. 3, the road-to-vehicle communication system according to the present embodiment recognizes the distance from the communication area A to the predetermined position P0 on the downstream side, and performs position location (F8 in FIG. 5). It functions as a distance recognition system that provides safe driving support to the driver.
Hereinafter, the content of the distance information described above and distance recognition for safe driving support performed by the vehicle-mounted device 2 based on the content will be described.

[Contents of distance information]
As shown in FIG. 3, the beacon controller 7 of the optical beacon 4 stores in advance the distance information that is a numerical value of distances L1 to L4 from the predetermined positions P1 to P4 in the communication area A to the predetermined position P0 on the downstream side thereof. It is stored in the device. Then, the distance information about the distances L1 to L4 is stored in the transmission frame of the second downlink information 36, and the frame is repeatedly transmitted from the beacon head 8.
The downstream end (end point) P0 of the distances L1 to L4 is set, for example, at the position of the stop line 40 installed on the downstream side of the optical beacon 4 before the traffic light.

Further, upstream ends (start points) P1 to P4 of the distances L1 to L4 are set at four locations according to the respective divided areas UA1 to UA4 of the uplink area UA. Specifically, the positions of the upstream ends P1 to P4 are set at approximately the center position in the vehicle traveling direction on the road R in each of the divided areas UA1 to UA4.
The beacon controller 7 selects any one of the distance information about the plurality of distances L1 to L4 stored in advance and stores it in the transmission frame of the second downlink information 36. Then, which distances L1 to L4 are selected is determined based on the photodiode 11 that has received the uplink information 35 before switching the downlink.

  For example, as shown in FIGS. 3 and 6, the in-vehicle device 2 transmits the uplink light UO1 (solid arrow in FIG. 3) in the uppermost divided area UA1, and this uplink light UO1 is transmitted to the divided area UA1. When the corresponding photodiode PD1 receives light and is recognized as the uplink information 35 in the beacon controller 7, the beacon controller 7 selects the distance information L1 corresponding to the divided area UA1, and switches the downlink. Then, the second downlink information 36 including the distance information about the distance L1 is transmitted to the in-vehicle device 2 via the LED 10.

In addition, when the beacon controller 7 acquires the uplink information 35 by the uplink light UO received by the photodiodes PD2 to PD4 corresponding to the other divided areas UA2 to UA4, the upstream point becomes P2 to P4. The distances L2 to L4 are selected, and the second downlink information 36 including the distance information about the distances L2 to L4 is transmitted to the in-vehicle device 2 via the LED 10.
As described above, the beacon controller 7 identifies distance information by the photodiodes PD1 to PD4 that have received the uplink information 35, and includes the distance information in the downlink information 36 as a control unit that performs downlink switching. It also has functions.

[Contents of safe driving support]
As shown in FIG. 4, when the in-vehicle head 27 receives the second downlink information 36 including the distance information, the distance recognition unit 30 of the in-vehicle computer 26 includes the distance included in the frame of the downlink information 36. Information is extracted to recognize the distances L2 to L4.
And the assistance control part 32 of the vehicle-mounted computer 26 performs the safe driving assistance with respect to a driver using the distances L1-L4.

For example, the support control unit 32 calculates a deceleration (negative acceleration) for stopping before the stop line 40 from the distances L1 to L4 to the stop line 40 and the current traveling speed of the vehicle C, The deceleration is notified to the ECU 22.
The ECU 22 operates the brake device 24 so as to achieve the deceleration, whereby the vehicle C can be automatically stopped before the stop line 40.

Further, the safe driving support of the support control unit 32 may be alerting the driver using the display 28 or the speaker device 29.
For example, the distance L1 to the stop line 40 may be displayed on the display 28 by the support control unit 32. When the current traveling speed of the vehicle C is too fast, the support control unit 32 displays a warning for stopping or decelerating on the display 28, or outputs the warning from the speaker device 29 as a voice. May be.

Moreover, the assistance control part 32 can also perform safe driving assistance using the signal information contained in 2nd downlink information with the said distance information.
Here, the signal information refers to information related to the current or future signal lamp color displayed by the traffic signal device, and includes information (display schedule information) regarding the display continuation period of each signal lamp color, the display order, and the like. For example, “the current lamp color is blue and the scheduled duration is 5 seconds, the next lamp color is yellow and the scheduled duration is 8 seconds, and the next lamp color is a right turn blue arrow lamp and the scheduled duration is 10 seconds. It is information such as “second”.

The support control unit 32 of the in-vehicle computer 27 that has received this signal information estimates the time required to arrive at the stop line 40 from the distances L1 to L4 to the stop line 40 and the traveling speed v of the vehicle C. The signal lamp color after the required time has elapsed can be estimated.
For example, if the current signal lamp color is a blue signal, but the signal lamp color is predicted to be a red signal when arriving at the stop line 40, it can be safely stopped before the stop line 40. Thus, control for braking the vehicle C is performed. Conversely, if it can be determined that the vehicle can safely pass through the intersection unless the vehicle is decelerated, the control for maintaining the speed of the vehicle C can be performed.

In order to brake the vehicle C or maintain the speed, the support control unit 32 may directly control the brake device 24 (FIG. 4) and the accelerator of the vehicle.
Further, the support control unit 32 may simply generate information related to braking and speed maintenance and notify the ECU 22 of the information to control the brake device 24 and the accelerator by the ECU 22. That is, the support control unit 32 may perform indirect control. In addition, the support control unit 32 may perform not only control led by the in-vehicle device but also operation for assisting the driving operation of the driver such as brake assist.

The support control unit 32 may notify the passenger of the vehicle C of the result of the signal lamp color estimation by voice or image information. For example, sound such as “Since the signal changes soon and should be stopped” is emitted from the speaker device 29 to the driver, or displayed on the display 28 such as a head-up display or a navigation device with characters or symbols. Can do.
For safe driving assistance, a human interface that does not notify the driver of information at an inappropriate timing or content, for example, it is possible to prevent notification by voice or image display during low-speed driving .

The signal information may be only the currently displayed lamp color and its duration, or information for one cycle may be provided collectively. Further, in addition to these pieces of information, parameter information related to the control, information on a time zone in which the control is performed, and the like may be included at the point where the point sensitive control is performed.
The signal information may be acquired from an optical beacon or may be acquired from an infrastructure device other than the optical beacon. In the latter case, for example, when the signal controller of the traffic signal is equipped with a wireless communication device, it may be acquired from the wireless communication device, or may be acquired by inter-vehicle communication from the preceding vehicle that acquired the signal information. Also good. The signal information receiving unit that receives the signal information may use the in-vehicle head 27 or may be another receiver provided in the in-vehicle device 2.

[Circuit configuration of optical receiver]
FIG. 7 is a block diagram illustrating an example of a circuit configuration of the optical receiving unit.
The light receiving unit 9 of this embodiment is mounted on the beacon heads 8 of the lanes R1 to R4 together with the plurality of photodiodes 11, and as shown in FIG. And an amplifying circuit 42 connected to each other.
The output side of each amplifier circuit 42 is connected to a single adder 43, and a comparator 44 is connected to the output side of this adder 43.

Each amplifying circuit 42 includes an amplifying element 45 made of an n-type MOSFET, an amplifying part 46 for further amplifying the output voltage of the element 45, and an amplification factor changing part 47 for controlling the gain of the amplifying part 46. I have.
The output terminal of each photodiode 11 is connected to the gate of the FET 45, and the drain of the FET 45 is connected to the input side of the amplification unit 46 at the subsequent stage.
The amplifying unit 46 is configured by, for example, connecting a plurality of operational amplifiers in series, and can amplify the drain voltage of the FET 45 on the input side, for example, on the order of 10,000 to 100,000 times.

The amplification factor changing unit 47 is composed of, for example, a digital potentiometer, and a part or all of the operational amplifiers constituting the amplifying unit 46 are based on the change signal (digital signal) S1 transmitted from the determination unit 16 of the beacon controller 7. Change the gain (amplification factor).
The change signal S1 can be individually input not only to the uppermost amplifier circuit 42 in FIG. 7, but also to all the amplifier circuits 42 corresponding to PD1 to PD4.

The output voltage from each amplifier circuit 42 is superimposed on one analog signal by the adder 43, converted to a digital signal by the comparator 44, and sent to the beacon controller 7.
The beacon controller 7 extracts a control signal and a data signal included in the uplink information 35 from the digital signal, and performs the road-to-vehicle communication described above.

[Contents of abnormality judgment processing]
Next, the abnormality determination process of the optical receiver performed by the determination unit 16 of the beacon controller 7 will be described.
In the following, among the plurality of photodiodes 11, the photodiode 11 corresponding to the uppermost divided region UA1 is referred to as PD1, and the second, third, and fourth photodiodes 11 from the upstream side are respectively PD2, It is called PD3 and PD4.

Here, when a certain photodiode 11 among PD1 to PD4 is out of order, it is estimated that the reception level of the uplink optical UO by the diode 11 is significantly lower than that in the normal state. Is done.
Therefore, the determination unit 16 of the beacon controller 7 sequentially transmits the change signal S1 to each of the amplifier circuits 42 corresponding to PD1 to PD4, and temporarily increases the amplification factor of each amplifier circuit 42. For example, the determination unit 16 increases the amplification factor to 10 times the normal value by the change signal S1, and detects the reception level at that time.

In this case, if the photodiode 11 is normal, even if the vehicle-mounted device 2 is not present in the communication area A, the infrared reception level due to sunlight reflected on the road surface, etc. should simply increase 10 times. In the case of the photodiode 11, the reception level does not change corresponding to the amplification factor of the amplifier circuit 42.
Therefore, the determination unit 16 determines whether or not the reception level before and after the increase of the amplification factor is equal to or less than a predetermined value (for example, 3 times or less) compared to the increase rate (10 times in this case) by the change signal S1. Then, it is determined that the photodiode 11 that is equal to or less than the predetermined value is abnormal.

The determination unit 16 periodically repeats such an abnormality determination process for each light receiving unit 9 (for each of the PD1 to PD4), and whether any of the light receiving units 9 in the beacon head 8 has failed. Determine whether.
Note that the cause of the abnormality of the optical receiver 9 is that the photodiode 11 itself is abnormal, the connection between the photodiode 11 and the amplifier circuit 42 is abnormal, the connection in the amplifier circuit 42 and the amplification. There are a case where the element 45 and the amplification unit 46 itself are abnormal, a case where the connection from the amplifier circuit 42 to the beacon controller 7 is abnormal, and the like.

[Operation timing of abnormality determination processing]
By the way, when the abnormality determination process as described above is performed in a time zone in which many vehicles C frequently pass through the communication area A, the amplification factor of the amplification unit 46 is increased during the reception time of the uplink optical UO. As a result, normal reception cannot be performed, and road-to-vehicle communication may be obstructed.
Therefore, the determination unit 16 of the present embodiment performs the abnormality determination process only when the vehicle C is not traveling in the communication area.

Specifically, the determination unit 16 confirms that the vehicle sensor 12 does not detect the vehicle C and then determines whether or not there is an abnormality within a time corresponding to an average required time from the vehicle sensor 12 to the communication area A. The process is executed so that the process can be completed.
For example, if the required time is 10 seconds, the determination unit 16 may perform the abnormality determination process for each of PD1 to PD4 in approximately 2 seconds.

On the other hand, on a general trunk road, there is an empirical rule that when the uplink light UO is received by any one of the photodiodes 11, the vehicle C does not pass for about 2 seconds immediately after that (except during a traffic jam).
Therefore, after about 200 ms sufficient for the vehicle C to pass through the communication area A from when the uplink light UO is received, the abnormality determination process may be performed only for a time of about 2 seconds. In this case, while the vehicle C is in the communication area A, the reception level largely fluctuates due to sunlight reflection from the vehicle body. Therefore, it is preferable to perform the abnormality determination process after the vehicle C has completely passed.

In addition, when the determination unit 16 according to the present embodiment determines that there is a suspicion only for the photodiode 11 that is suspected of failure, such as the photodiode 11 that has not received the uplink optical UO within a predetermined time. In this case, the abnormality determination process may be executed.
In this case, since the abnormality determination process is performed only for the photodiode 11 having a high probability of failure, the frequency can be reduced as compared with a case where the process is performed uniformly and regularly. Can be done automatically.

Further, for example, a manual switch may be provided in the beacon controller 7, and an operator may operate this switch so that the abnormality determination process by the determination unit 16 is performed. The determination unit 16 may execute the abnormality determination process at the time when an artificial instruction is issued from the central device 3 or the traffic signal controller.
In this case, since the abnormality determination process of the optical receiving unit is performed only when an artificial execution signal is received from the outside, the frequency can be reduced as compared with the case where the process is uniformly performed periodically. And the processing can be performed efficiently.

As described above in detail, according to the road-to-vehicle communication system of the present embodiment, the determination unit 16 of the beacon controller 7 temporarily increases the amplification factor for the amplification circuit 42 of the light receiving unit 9 and increases the rate. Therefore, the abnormality determination process of the optical receiver 9 is performed depending on whether or not a reception level suitable for the optical receiver 9 is obtained, so that an abnormality occurring in the optical receiver 9 can be determined autonomously on the infrastructure side.
For this reason, it is possible to find an abnormality in the light receiving unit 9 including the photodiode 11 without performing an inspection operation with traffic regulation, and to easily prevent a decrease in reliability of road-to-vehicle communication due to the abnormality. Can do.

  Further, in the case of a PD split type optical beacon as in the present embodiment in which a single beacon head 8 has a plurality of optical receivers 9, road-to-vehicle communication is possible even if any one of the photodiodes 11 breaks down. However, according to the road-to-vehicle communication system of the present embodiment, the determination unit 16 performs the abnormality determination process on each of the optical reception units 9 corresponding to the divided areas UA1 to UA4. Therefore, even in such a PD split type optical beacon 4, an abnormality occurring in any one of the optical receiving units 9 can be individually determined for each optical receiving unit 9.

  Furthermore, according to the road-to-vehicle communication system of the present embodiment, the determination unit 16 performs an abnormality determination process on the light reception unit 9 of the beacon head 8 provided for each of the lanes R1 to R4. There is also an advantage that the abnormalities occurring in can be individually determined for each beacon head 8.

[Other variations]
Although the PD split type optical beacon 4 in which a plurality of optical receivers 9 are provided in the beacon head 8 is illustrated in the above embodiment, the beacon head 8 having only one optical receiver 9 (photodiode 11) is used. Even if it exists, this invention is applicable. The present invention can also be applied to a road R having only a single lane in the same direction.
Furthermore, in the said embodiment, although the determination part 16 is provided in the beacon controller 7 of the optical beacon 4, this determination part 16 may be provided in other infrastructure side apparatuses, such as the central apparatus 3. FIG.

  On the other hand, in the road-to-vehicle communication system of the present embodiment, downlink switching is not performed immediately upon reception of the first uplink information 35, but based on a plurality of uplink information 35 received from the same vehicle C. The traveling speed v of the vehicle C may be calculated on the light beacon 4 side. In this case, the traveling speed v is included in the second downlink information 36, so that accurate speed information is given to the vehicle C. (For details, see the specification of Japanese Patent Application No. 2007-288175).

However, since downlink switching is not performed in the first uplink reception as described above, if the reception timing of the uplink information 35 is too late, the subsequent downlink switching timing is also delayed.
Therefore, in this case, it is impossible to transmit the second downlink information 36 in the communication area A, and the original road-to-vehicle communication in which the downlink information 36 includes predetermined information such as traffic jam information and is sent to the in-vehicle device 2. May be disturbed.

  Specifically, when the optical beacon 4 receives the first uplink information 35 for the first time after the vehicle C reaches the area (for example, the divided area UA3) from the downstream side of the uplink area UA, the distance information In addition, when waiting for the reception of the second uplink information 35 to obtain speed information, the downlink switching timing may be delayed and the second downlink information 36 may not be transmitted.

Therefore, only when the traveling position of the vehicle C corresponding to the first uplink information 35 is from the upstream side in the uplink area UA (in FIG. 3, the first divided area UA1 and the second divided area UA2), It is preferable to calculate the speed information of the vehicle C.
But in this embodiment, the vehicle advancing direction length of each divided area UA1-UA4 can be set according to the level requested | required as distance recognition accuracy. Moreover, the vehicle traveling direction lengths of the divided areas UA1 to UA4 may be different from each other.

  Further, in the present embodiment, the method of selecting the distance according to the photodiode 11 that received the uplink information 35 from the distances L1 to L4 and including the distance information in the second downlink information 36 has been described. However, for example, all of the distances L1 to L4 are assigned identification numbers, and all the distances L1 to L4 and the corresponding identification numbers are included in the second downlink information. At the same time, the uplink information 1 may be included in the second downlink information 36 in accordance with the photodiode 11 that has received 35.

In this case, the distance recognition unit 30 of the in-vehicle computer 26 can select and recognize an accurate distance based on the first identification number included in the second downlink information 36.
When the in-vehicle computer 26 stores the distances L1 to L4 and their identification numbers in advance, only the one identification number corresponding to the photodiode 11 that received the uplink information 35 is used as the second downlink information. May be included.

Furthermore, the distance information notified to the in-vehicle device 2 includes the first information regarding the distance L0 from the uppermost stream end c of the uplink area UA to the predetermined position P0, and the predetermined positions of the divided areas UA1 to UA4 from the uppermost stream end c. You may decide to divide into the 2nd information regarding distance difference (DELTA) 1-Δ4 to P1-P4.
In this case, the distance recognition unit 30 of the in-vehicle device 2 extracts the first information and the second information from the second downlink information 36, and subtracts the second information from the extracted first information, whereby the predetermined position P0. The actual distance to (stop line 40) can be calculated.

Further, for example, as shown in FIG. 3, the positions of the upstream ends P1 to P4 of the distances L1 to L4 constituting the distance information are not limited to the substantially central positions on the road R of the divided areas UA1 to UA4, and are arbitrarily set. can do.
For example, the upstream ends P1 to P4 are set to the upstream ends (positions indicated by c, e1, e2, and e3) of the divided areas UA1 to UA4 on the road R, or on the road R of the divided areas UA1 to UA4. It can be set at the downstream end (position indicated by e1, e2, e3, b).

The number of divided areas UA1 to UA4 (number of photodiodes 11) may be two, three, or five or more.
Furthermore, the downstream ends of the distances L1 to L4 that constitute the distance information may be the installation position of the traffic light or the position of the vehicle detector in addition to the stop line 40.
In addition, the distance information in the present embodiment is not limited to a format that directly stores a distance value to the predetermined position P0, and any format may be used as long as the information can uniquely determine the distance to the predetermined position P0. May be.

For example, one or a plurality of nodes may be set between the uplink area UA and a predetermined position P0 on the downstream side, and the distance information may be configured by a plurality of distance value groups corresponding to these nodes.
For example, a distance from a predetermined position (for example, upstream end c of the uplink area UA) to the nearest node in the uplink area UA that is the starting point, a distance between the nodes, and a predetermined position from the node nearest to the predetermined position P0 The distance information can be configured by the distance to P0. In this case, the in-vehicle computer 26 that has received the distance information can recognize the distance to the predetermined position P0 by obtaining the total value of the distances.

Further, the distance information transmitted by the optical beacon 4 is not the value of the distance itself, but the absolute position (latitude / longitude or an arbitrary point in outer space) of the distance. Value).
For example, the distance information is configured to include information related to the absolute position in the uplink area UA obtained by the present invention and information related to the absolute position of the predetermined position P0. The distance recognition unit 30 may calculate the distance. Moreover, when the information regarding the absolute position of the predetermined position P0 is stored on the in-vehicle device 2 side, the optical beacon 4 may transmit only the information regarding the absolute position in the uplink area UA obtained by the present invention. Good.

  Further, the road shape information and detailed map information indicating the shape of the road including the point of the predetermined position P0, and the position on the road or the map and corresponding to the position in the uplink area UA obtained by the present invention A method in which the optical beacon 4 transmits information and the in-vehicle device 2 acquires the distance to the predetermined position P0 based on this information may be used. In this case, road shape information and map information may be stored in the in-vehicle device 2 in advance, or may be transmitted to the in-vehicle device 2 by wireless communication other than the optical beacon 4.

Furthermore, each function part 30,31,32 of the vehicle-mounted computer 26 can also be integrated in the electronic controller (ECU) of the vehicle C.
In each of the above embodiments, the communication area A (particularly, the uplink area UA) has been described as being wider than the “near infrared interface standard” of the optical beacon, but the communication area A conforms to the standard. It may be set to a dimension.

It is a block diagram which shows the whole structure of a road-vehicle communication system. It is a top view of an optical beacon. It is a side view which shows the communication area | region of an optical beacon. It is a schematic block diagram of the vehicle equipment which carries out road-vehicle communication, and the vehicle carrying this. It is a conceptual diagram which shows the procedure and data content of the road-vehicle communication performed in a communication area. It is the schematic which shows the procedure in which one of optical receivers transmits downlink information after receiving uplink information. It is a block diagram which shows an example of the circuit structure of an optical receiver. It is a side view which shows the communication area | region of the conventional optical beacon.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Traffic control system 2 Car equipment 3 Central apparatus 4 Optical beacon 7 Beacon controller (communication control part)
8 Beacon head (emitter / receiver)
9 Light receiver 10 Light emitting diode (LED)
11 Photodiode (PD)
16 determination unit 34 first downlink information 35 uplink information 36 second downlink information 42 amplifying circuit 47 gain changing unit A communication area C vehicle R road P0 stop line (predetermined position)
P1 to P4 Start point position DA Downlink area UA Uplink area UA1 to UA4 Divided area
DO Downlink light UO Uplink light

Claims (8)

An in-vehicle device of a vehicle traveling on a road, and an optical beacon having a light-receiving / receiving device in which a communication area is set in a predetermined range of the road; Road-to-vehicle communication system that performs two-way communication with optical signals between,
An optical receiver provided in the light emitter / receiver for receiving uplink information transmitted by the in-vehicle device in an uplink region included in the communication region;
A determination unit that temporarily raises the amplification factor for the amplification circuit of the optical reception unit and performs abnormality determination processing of the optical reception unit depending on whether a reception level corresponding to the increase is obtained,
A road-to-vehicle communication system comprising:   The road-to-vehicle communication system according to claim 1, wherein the determination unit performs the abnormality determination process only when the vehicle is not traveling in the communication area.   The road-to-vehicle communication system according to claim 1, wherein the determination unit performs the abnormality determination process only for the optical reception unit that does not receive uplink information within a predetermined time.   The road-vehicle communication system according to claim 1, wherein the determination unit performs the abnormality determination process based on an artificial execution signal from the outside. The light receiving unit is provided in each of the light projecting and receiving units corresponding to a plurality of divided regions obtained by dividing the uplink region in the vehicle traveling direction,
The road-vehicle communication system according to any one of claims 1 to 4, wherein the determination unit performs the abnormality determination process on each of the plurality of optical reception units. The light emitter / receiver is installed corresponding to each lane of the road in a plurality of lanes,
The road-to-vehicle communication system according to any one of claims 1 to 5, wherein the determination unit performs the abnormality determination process on the light receiving unit of each of the projectors and receivers. An optical beacon having a light emitter / receiver in which a communication area is set in a predetermined range of a road, and performing two-way communication with an optical signal between the light emitter / receiver and an in-vehicle device of a vehicle in the communication area,
An optical receiver provided in the light emitter / receiver for receiving uplink information transmitted by the in-vehicle device in an uplink region included in the communication region;
A determination unit that temporarily raises the amplification factor for the amplification circuit of the optical reception unit and performs abnormality determination processing of the optical reception unit depending on whether a reception level corresponding to the increase is obtained,
An optical beacon characterized by comprising: An anomaly detection method for detecting an anomaly that has occurred in an optical receiver provided in a light receiver / receiver of an optical beacon in order to receive uplink information comprising an optical signal from an in-vehicle device,
The optical receiver of an optical beacon, wherein the amplification factor of the optical receiver for the amplifier circuit is temporarily increased, and abnormality determination processing of the optical receiver is performed depending on whether or not a reception level commensurate with this increase is obtained. Anomaly judgment method.

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