JP6962516B2 - Optical beacon - Google Patents

Description

The present invention relates to an optical beacon that wirelessly communicates with an on-board unit of a moving vehicle by an optical signal.

As a traffic information service using a road-to-vehicle communication system, so-called VICS (Vehicle Information and Communication System: a registered trademark of the Vehicle Information and Communication System Center) using optical beacons, radio beacons, or FM multiplex broadcasting has already been developed. ing.
Of these, the optical beacon employs optical communication using near infrared rays as a communication medium, and is capable of two-way communication with an in-vehicle device. Specifically, uplink information including travel time information between beacons held by the vehicle is transmitted from the on-board unit to the optical beacon on the infrastructure side.

On the contrary, the optical beacon transmits downlink information including congestion information, section travel time information, event regulation information, lane notification information, and the like to the in-vehicle device (see, for example, Patent Document 1).
For this reason, the optical beacon is provided with a light emitting / receiving device (hereinafter, also referred to as “beacon head”) for transmitting / receiving an optical signal to / from the vehicle-mounted device for each lane. Inside the housing of each beacon head, a transmission / reception unit for optical communication having a light emitting element that emits downlink light toward the road and a light receiving element that receives uplink light transmitted by an in-vehicle device is mounted. ..

Japanese Unexamined Patent Publication No. 2005-268925

In an optical beacon in which beacons heads are installed in each of a plurality of lanes, it is necessary to perform light emission control for a plurality of beacon heads.

In view of the conventional problems, an object of the present invention is to provide an optical beacon capable of executing light emission control processing for a plurality of beacon heads.

(1) The optical beacon according to one aspect of the present invention is an optical beacon including a plurality of optical beacon heads each having a light emitting unit for communication and an optical beacon controller for the plurality of optical bean heads. The beacon controller includes a plurality of switching elements for controlling light emission of the communication light emitting unit and a control board, and the control board has a plurality of first output ports and a second output port. The plurality of first output ports are connected to each switching element by individual signal lines and are ports for outputting control signals to each switching element, and the second output port is a branched signal. It is a port connected to the plurality of switching elements by a wire and for outputting a signal for causing the communication light emitting unit of the plurality of optical beacon heads to emit light.

According to the present invention, it is possible to provide an optical beacon capable of executing light emission control processing for a plurality of beacon heads.

It is a block diagram which shows the schematic structure of the road-to-vehicle communication system. It is a top view of the road where the optical beacon is installed. It is a side view of the road which shows the communication area and the incident area of an optical beacon. It is a frame block diagram of an upstream frame. It is a frame block diagram of a downlink frame. It is a sequence diagram which shows an example of the road-to-vehicle communication performed in a communication area. It is a time chart which shows an example of the stop and start timing of the light emission of the downlink light applicable to an optical beacon. It is a block diagram which shows an example of the internal structure of an optical beacon which can execute a light emission control process for each lane. It is a block diagram which shows another example of the internal structure of the optical beacon which can execute light emission control processing for each lane. It is a block diagram which shows another example of the internal structure of the optical beacon which can execute light emission control processing for each lane.

<Outline of Embodiment of the present invention>
Hereinafter, the outlines of the embodiments of the present invention will be described in a list.
(1) The optical beacon of the present embodiment is an optical beacon including a plurality of optical beacon heads each having a light emitting unit for communication and an optical beacon controller for the plurality of optical bean heads, and the optical beacon controller. Is provided with a plurality of switching elements for controlling light emission of the communication light emitting unit and a control board, and the control board has a plurality of first output ports and a second output port, and the plurality of control boards include a plurality of first output ports and a second output port. The first output port is a port that is connected to each switching element by an individual signal line and outputs a control signal to each switching element, and the second output port is a plurality of branched signal lines. It is a port connected to the switching element of the above and for outputting a signal for causing the communication light emitting unit of the plurality of optical beacon heads to emit light.

According to the optical beacon of the present embodiment, the beacon controller can execute the light emission control process for each beacon head for each beacon head.

<Details of Embodiments of the present invention>
Hereinafter, details of the embodiment of the present invention will be described with reference to the drawings.
In the present embodiment, the uplink frame transmitted from the vehicle-mounted device 2 toward the optical beacon 4 or the information transmitted by the uplink frame may be referred to as "uplink information" or "uplink signal". Further, the downlink frame transmitted from the optical beacon 4 to the vehicle-mounted device 2 or the information transmitted by the downlink frame may be referred to as "downlink information" or "downlink signal".

[Overall system configuration]
FIG. 1 is a block diagram showing a schematic configuration of a road-to-vehicle communication system according to the present embodiment. FIG. 2 is a plan view of the road R when the installation portion of the optical beacon 4 of the present embodiment is viewed from above.
As shown in FIG. 1, the road-to-vehicle communication system of the present embodiment includes a traffic control system 1 on the infrastructure side and an in-vehicle device 2 mounted on a vehicle 20 (see FIG. 3) traveling on a road R.

The traffic control system 1 includes a central device 3 provided in a traffic control room or the like, and a large number of optical beacons (optical vehicle detectors) 4 installed in various places on the road R. The optical beacon 4 can perform wireless communication with the vehicle-mounted device 2 by optical communication using near infrared rays as a communication medium.
The optical beacon 4 includes a beacon controller (communication control unit) 7 that performs communication control and the like, and a plurality of (four in the example of FIG. 1) beacon heads (throw and receive) connected to the sensor interface of the beacon controller 7. Vessel) 8 and.

The beacon controller 7 is connected to the communication unit 6 on the infrastructure side, and the communication unit 6 is connected to the central device 3 by a communication line 5 such as a telephone line.
The communication unit 6 can be composed of, for example, a traffic signal controller that controls the color of the signal lamp, an information relay device that relays traffic information on the infrastructure side, and the like.

The optical beacon 4 of the present embodiment employs a full-duplex communication system. That is, the beacon controller 7 simultaneously performs transmission control in the downlink direction with respect to the light emitting unit 13 for optical communication and reception control in the uplink direction with respect to the light receiving unit 14 for optical communication.
On the other hand, the vehicle-mounted device 2 of the present embodiment employs a half-duplex communication system. That is, the in-vehicle controller 21 (see FIG. 3), which will be described later, does not simultaneously perform transmission control in the uplink direction with respect to the optical transmission unit 23 and reception control in the downlink direction with respect to the optical reception unit 24.

[Overall configuration of optical beacon]
The beacon head 8 of the optical beacon 4 includes a transmission / reception unit 11 (optical transmission / reception unit) for optical communication and a sensor unit 12 for vehicle detection in a housing 9 (see FIGS. 1 and 3).
As described above, in the optical beacon 4 of the present embodiment, the optical communication function and the vehicle sensing function are formed by incorporating the units 11 and 12 for optical communication and vehicle sensing into the housing 9 of one beacon head 8. It has a structure that has both.

The transmission / reception unit 11 for optical communication is an optical transceiver that wirelessly transmits / receives an optical signal to / from the vehicle-mounted device 2.
As shown in FIG. 1, the transmission / reception unit 11 receives the light emitting unit 13 for optical communication that sends out the downlink light DO (see FIG. 3) and the uplink light UO (see FIG. 3) and converts them into an electric signal. It has a light receiving unit 14 for optical communication.

The light emitting unit 13 for optical communication (hereinafter, also referred to as “light emitting unit 13 for communication”) includes a transmission circuit that converts a downlink frame transmitted from the beacon controller 7 into a serial transmission signal having a predetermined transmission speed. It has a light emitting element made of a light emitting diode (LED) that converts an output transmission signal into an optical signal in the downlink direction.
The light emitting element of the communication light emitting unit 13 transmits the downlink light DO, which is an optical signal of near infrared rays, obliquely downward toward the upstream side.

The light receiving unit 14 for optical communication (hereinafter, also referred to as “communication light receiving unit 14”) amplifies a light receiving element made of a photodiode (PD: Photo Diode) or the like and an electric signal output by the light receiving element. It has a receiving circuit that generates a digital signal.
The light receiving element of the communication light receiving unit 14 receives the uplink light UO, which is a near-infrared optical signal transmitted by the vehicle-mounted device 2 in front of the beacon head 8, and converts it into an electric signal. The receiving circuit of the communication light receiving unit 14 sends a digital signal generated from the converted electric signal to the beacon controller 7.

The sensor unit 12 is a light sensing sensor for non-contactly detecting the presence of the vehicle 20 passing substantially directly under the beacon head 8.
As shown in FIG. 1, the sensor unit 12 receives a light emitting unit 15 for vehicle detection that transmits incident light IO (see FIG. 3) and a vehicle that receives reflected light RO (see FIG. 3) and converts it into an electric signal. It has a light receiving unit 16 for sensing.

The vehicle sensing light emitting unit 15 (hereinafter, also referred to as “sensing light emitting unit 15”) transmits incident light IO, which is an optical pulse signal having a predetermined period, downward.
The light receiving unit 16 for vehicle detection (hereinafter, also referred to as “sensing light receiving unit 16”) receives the reflected light RO for the road R and the vehicle 20 of the incident light IO, and uses the received reflected light RO as an electric signal. It is converted and sent to the beacon controller 7.

The beacon controller 7 is composed of a computer device having a signal processing unit, a CPU, a memory, and the like, and has a function as a communication control unit that communicates with the central device 3 and performs road-to-vehicle communication with the vehicle-mounted device 2 according to a predetermined communication interface standard. , Has a function as a sensing control unit of the vehicle 20.
Further, the beacon controller 7 stores a computer program for communication control and sensing control in a storage device (not shown), and when the CPU reads and executes this program, the CPU controls the communication. It realizes the function as a unit and a sensing control unit.

For example, the beacon controller 7 includes a downlink signal (first downlink frame) including lane notification information in which the identification value of the vehicle ID (hereinafter, also referred to as “ID value”) is not stored, or predetermined provided information. A downlink signal (first downlink frame) including the above is constantly transmitted to the communication light emitting unit 13 at a predetermined cycle.
While continuing to transmit the downlink signal, the beacon controller 7 receives the uplink signal (uplink frame) including the ID value that the vehicle-mounted device 2 will transmit upon receiving the downlink signal. The presence or absence is judged.

When the beacon controller 7 detects the reception of the uplink signal by the communication light receiving unit 14, the beacon controller 7 includes lane notification information storing the ID value and the lane number value extracted from the uplink signal, and information provided for the vehicle 20. Is generated, and one or a plurality of downlink signals (second downlink frames) including the generated information are transmitted to the communication light emitting unit 13 for a predetermined time (for example, 250 to 350 ms).

Then, when the predetermined time elapses, the beacon controller 7 restores the content of the provided information included in the downlink signal and waits for the next arrival of the uplink signal from the vehicle-mounted device 2 of the vehicle 20. ..
The beacon controller 7 transfers information included in the uplink signal, such as probe data consisting of a traveling locus such as the position and time of the vehicle 20, to the central device 3.

The beacon controller 7 constantly sends the incident light IO of a predetermined wavelength to the sensing light emitting unit 15 at a constant intensity and pulse period, and whether the light receiving intensity of the reflected light RO received by the sensing light receiving unit 16 is equal to or higher than the threshold value. Depending on whether or not, the presence of the vehicle 20 is detected.
That is, when the light receiving intensity of the reflected light RO equal to or higher than the threshold value is detected in the sensing light receiving unit 16, the beacon controller 7 generates a sensing signal of the vehicle 20 and transmits the sensing signal to the central device 3. Note that this threshold value is not limited to a fixed value, and may vary depending on, for example, follow-up processing according to the light receiving intensity of the reflected light RO.

[Installation status of optical beacon]
As shown in FIG. 2, the optical beacon 4 of the present embodiment is installed on a road R having a plurality of (four in the example) lanes R1 to R4 in the same direction.
The optical beacon 4 comprises a plurality of the beacon heads 8 provided corresponding to the respective lanes R1 to R4, and one said beacon controller 7 which is a communication control unit for collectively controlling the beacon heads 8. Be prepared.

The beacon controller 7 is installed on a support column 17 erected on the sidewalk portion on the left side of the road R. Each beacon head 8 is attached to an erection bar (beam member) 18 erected horizontally from the support column 17 on the road R side, and is arranged directly above the substantially center position of each lane R1 to R4.
The communication light emitting unit 13 of the beacon head 8 emits the downlink light DO toward the upstream side in the vehicle traveling direction rather than directly under the own machine. As a result, the communication area A for performing road-to-vehicle communication with the vehicle-mounted device 2 is set on the upstream side of the beacon head 8.

The sensing light emitting unit 15 of the beacon head 8 emits incident light IO toward substantially directly below the own machine. As a result, the incident region B, which is the sensing area of the vehicle 20 passing through the predetermined lanes R1 to R4 on the road R, is set substantially directly below the beacon head 8.

[Communication area and incident area of optical beacon]
FIG. 3 is a side view of the road R showing the communication area A and the incident area B of the optical beacon 4.
As shown in FIG. 3, the communication area A of the transmission / reception unit 11 includes the downlink area DA (hatched portion of the solid line), which is the light receiving range of the downlink light DO by the vehicle-mounted device 2, and the uplink light UO by the beacon head 8. It is composed of an uplink region UA (hatched portion of a broken line), which is a light receiving range of the above.

According to the UTMS (Universal Traffic Management Systems) Association's "Optical Vehicle Sensor Near Infrared Interface Standard Version 2" (hereinafter referred to as the "old interface standard") formulated on August 3, 2001, each area DA and UA The standard values of the upstream and downstream end positions are as follows.
Downlink area DA downstream end position a0: + 1.3m
Downstream end position of uplink region UA b0: a0 + 2.1m (= 3.4m)
Upstream end positions of both regions DA and UA c0: b0 + 1.6m (= 5.0m)

According to the UTMS Association's "Advanced Optical Beacon Near Infrared Interface Standard Version 4" (hereinafter referred to as "new interface standard") formulated on January 28, 2016, the standard value of the upstream end position of each area DA and UA (hereinafter referred to as "new interface standard"). (In the case of general roads) is as follows.
Downlink region DA downstream end position a0: + 0.70 m
Downstream end position of uplink region UA b0: a0 + 2.70m (= 3.40m)
Upstream end positions of both regions DA and UA c0: b0 + 2.64m (= 6.04m)
The standard values of the positions a0 to c0 are values when the upstream direction from the position directly below the light emitting / receiving device 8 (origin O) on the reference surface having a height H from the road surface of 1.0 m is a positive number. ..

In the old interface standard, the transmission speed of the uplink optical UO transmitted by the vehicle-mounted device 2 is only 64 kbit / s, and the transmission speed of the downlink optical DO received by the vehicle-mounted device 2 is only 1024 kbit / s.
On the other hand, in the new interface standard, the transmission speed of the downlink optical DO is the same as before, but the transmission speed of the uplink optical UO is two types of high and low multi-rates (low speed is 64 kbit / s and high speed is 256 kbit /). It has been changed to s).

Therefore, the optical beacon 4 according to the new interface standard is called a multi-rate compatible optical beacon (“new optical beacon” or “advanced optical beacon”) capable of low-speed uplink reception as before and new high-speed uplink reception. ).
In addition, the in-vehicle device 2 that complies with the new interface standard is called a multi-rate compatible in-vehicle device (called "new in-vehicle device" or "advanced in-vehicle device") capable of performing low-speed uplink transmission as before and new high-speed uplink transmission. .).

In the present embodiment, it is assumed that both the optical beacon 4 and the vehicle-mounted device 2 are devices that support high-speed uplink communication.
That is, in the present embodiment, it is assumed that the optical beacon 4 is a new optical beacon (advanced optical beacon) and the in-vehicle device 2 is a new in-vehicle device (advanced optical in-vehicle device).

The incident region B of the sensor unit 12 is an irradiation range of the incident light IO that the sensing light emitting unit 15 incidents on the road R.
The center of the incident region B in the road width direction is located at a position substantially equal to the center of the lanes R1 to R4 corresponding to the beacon head 8 in the road width direction. The light emitting direction V1 of the incident light IO is normally directed to the upstream side (plus side) by a predetermined angle α (for example, 4.5 °) with respect to the vertical direction, but is downstream by a predetermined angle with respect to the vertical direction. It may be directed to the side (minus side).

[Configuration of in-vehicle device]
As shown in FIG. 3, the vehicle-mounted device 2 of the present embodiment includes a vehicle-mounted controller (communication control unit) 21 and an vehicle-mounted head (optical transmission / reception unit) 22. An optical transmission unit 23 and an optical reception unit 24 are housed inside the vehicle-mounted head 22.
The optical transmitting unit 23 has a light emitting element that emits an uplink light UO (optical signal in the uplink direction) composed of near infrared rays, and the optical receiving unit 24 has a downlink light UO (downlink direction) composed of near infrared rays. It has a light receiving element that receives light (optical signal).

The optical transmission unit 23 has a transmission circuit that converts an uplink frame output from the in-vehicle controller 21 into a serial transmission signal having a predetermined transmission speed, and a light emitting unit that converts the output transmission signal into an optical signal in the uplink direction. It has a light emitting element made of a diode or the like.
The optical receiver 24 includes a light receiving element including a photodiode or the like that photoelectrically converts an optical signal in the downlink direction and outputs an electric signal, and a receiving circuit that amplifies the output electric signal to generate a digital received signal. Has.

The in-vehicle controller 21 comprises a computer device having a signal processing unit, a CPU, a memory, and the like, and has a function as a communication control unit that performs road-to-vehicle communication with the optical beacon 4.
Further, the in-vehicle controller 21 stores a computer program for communication control in a storage device (not shown), and when the CPU reads and executes this program, the CPU functions as the communication control unit. do.

The in-vehicle controller 21 generates travel data of the own vehicle (for example, probe information which is travel locus data in which the passage position and the passage time are arranged in chronological order) as uplink data and uploads the data to the optical transmission unit 23. It also has a function to send a link.
In this case, if the uplink speed is increased as in the new interface standard, more probe information (longer road section for recording the traveling locus, or higher recording density of passing position and passing time in the same road section will be increased. It becomes possible to send information).

The in-vehicle controller 21 of the present embodiment may have a circuit configuration in which a simple control unit including an ASIC (Application Specific Integrated Circuit) or the like is provided in addition to the main body control unit including the CPU.
For example, when the optical receiving unit 24 receives some downlink frame, the simple control unit optically transmits only one uplink frame (conventional uplink frame having a transmission speed of 64 kbit / s) including the vehicle ID of the own vehicle. It has a function of causing the unit 23 to transmit an uplink.

[Frame configuration of upstream frame]
FIG. 4 is a frame configuration diagram of an upstream frame.
As shown in FIG. 4, in the storage area of the uplink frame, in order from the beginning, a transmission control unit for synchronization (hereinafter referred to as “synchronization unit”) for recognizing the frame break, a header unit, and an actual data unit. , And a transmission control unit (hereinafter referred to as “CRC unit”) for CRC (Cyclic Redundancy Check) is included.

In the uplink frame, 1 byte is allocated to the synchronization part, 10 bytes are allocated to the header part, a maximum of 59 bytes are allocated to the actual data part, and 4 bytes (1 byte idle part + 2 bytes CRC + 1 byte) are allocated to the CRC part. The final synchronization part) is assigned.
In the header part of the uplink frame, storage areas such as "number of subsystem key information", "vehicle ID", "vehicle-mounted model type", "information type", "final frame flag", and "frame number within the same information type" are stored. Is included.

In the "number of subsystem key information" (hereinafter, may be abbreviated as "number of information"), the number of "subsystem key information" to be stored in order from the beginning of the actual data section is stored.
That is, when the number of information is zero, the actual data section does not include "subsystem key information", and when the number of information is "1", the actual data section contains one "subsystem key information". When the number of information is "n", n "subsystem key information" is included in the actual data unit.

The above "subsystem key information" is a downlink of the optical beacon 4 such as a public vehicle priority system (PTPS), a vehicle operation management system (MOCS), a field express support system (FAST), and a safe driving support system (DSSS). This is key information for selecting additional information of information.
The vehicle-mounted device 2 determines the contents of the "number of subsystem key information" and the "subsystem key information" according to which system of the UTMS standard the own vehicle corresponds to.

For example, when the own vehicle corresponds to one system of the UTMS standard, the in-vehicle device 2 sets the value of the "number of subsystem key information" in the header part to "1" and complies with the standard of the one system. The "subsystem key information (1)" of the contents is stored in the actual data unit.
Further, when the own vehicle corresponds to the two systems of the UTMS standard, the in-vehicle device 2 sets the value of the "number of subsystem key information" in the header part to "2", and sets each of the standards of the two systems. The "subsystem key information (1)" and "subsystem key information (2)" according to the contents are stored in the actual data unit.

The data format of "subsystem key information" differs depending on the standard of each system, so details are omitted. For example, in the case of a safe driving support system (DSSS), the brake state, turn signal state, hazard state, etc. Information such as vehicle speed, direction of travel, acceleration / deceleration and accelerator pedal position is included.

The optical beacon 4 determines which system included in the UTMS standard the in-vehicle device 2 corresponds to based on the type of "subsystem key information" included in the uplink information, and provides information according to the standard of the system. Is stored in the downlink frame and transmitted as a downlink. This provided information is called "special information" in the standard.
In this way, the optical beacon 4 determines the type of "special information" to be included in the downlink information after receiving the uplink based on the type of "subsystem key information".

The "vehicle ID" is an area for storing the identification value (which may be a numerical value or a symbol) of the vehicle ID generated by the vehicle-mounted device 2 by itself or automatically generated by the optical beacon 4 and notified to the vehicle-mounted device 2. .. The vehicle-mounted device 2 stores the value of the vehicle ID stored at the time of uplink transmission in the vehicle ID of the header portion of the uplink frame.
The “vehicle-mounted device type” is an area for storing the type of the vehicle-mounted device 2. The "information type" is an area for storing the type of uplink information. In the new interface standard, the values in these areas indicate the old and new of the uplink transmitter and whether the uplink information is high speed or low speed.

Specifically, when transmitting a low-speed ascending frame, the in-vehicle device 2 stores a predetermined value (for example, "6") indicating the new in-vehicle device in the "vehicle-mounted device type" and determines it in the "information type". Store the value (eg, "1").
Further, when transmitting a high-speed uplink frame, the in-vehicle device 2 stores a predetermined value (for example, "6") indicating the new in-vehicle device in the "vehicle-mounted device type" and a predetermined value (for example, "for example") in the "information type". , "4") is stored.

Therefore, when the value of the in-vehicle model of the received uplink frame is "6" and the value of the information type is "1", the optical beacon 4 can be determined to be a low-speed frame from the new in-vehicle device and received. When the value of the in-vehicle device type of the uplink frame is "6" and the value of the information type is "4", it can be determined that the frame is a high-speed frame from the new in-vehicle device.
In the case of the old in-vehicle device, the value of the in-vehicle model is set to other than "6", so that the optical beacon 4 receives an uplink frame in which the value of "in-vehicle model" is other than "6". It can be determined that the communication partner is an old in-vehicle device that does not support high-speed uplink transmission.

The "final frame flag" is a storage area for indicating which of the one or a plurality of uplink frames transmitted by the vehicle-mounted device 2 is the final frame.
For example, when the vehicle-mounted device 2 continuously transmits a plurality of uplink frames, the vehicle-mounted device 2 stores a predetermined flag value (for example, "1") only in the "final frame flag" of the last uplink frame among them, and other than that. The flag value is not stored in the upstream frame. Further, when the vehicle-mounted device 2 transmits only one uplink frame, the vehicle-mounted device 2 sets the final frame flag in the uplink frame.

The "frame number within the same information type" is an sequence number of the uplink when the information of the same information type is transmitted in one uplink or is divided into a plurality of uplinks and continuously transmitted.
The maximum number of uplink frames that the vehicle-mounted device 2 can continuously transmit is defined as 16 frames. Therefore, for example, when the vehicle-mounted device 2 continuously transmits 16 uplink frames, the number values 1 to 16 are stored in the "frame number within the same information type" in order from the first uplink frame. A number value is added to the frame number even in the case of one frame transmission.

[Frame configuration of downlink frame]
FIG. 5 is a frame configuration diagram of a downlink frame.
As shown in FIG. 5, the storage area of the downlink frame also includes a synchronization unit, a header unit, an actual data unit, and a CRC unit in order from the beginning, as in the case of the frame configuration of the uplink frame (FIG. 4). ..

In the downlink frame, 1 byte is allocated to the synchronization part, 5 bytes are allocated to the header part, 123 bytes are allocated to the actual data part, and 4 bytes are allocated to the CRC part (1 byte idle part + 2 bytes CRC + 1 byte final). Synchronous part) is assigned.
The header portion of the downlink frame includes storage areas such as "information type", "final frame flag", and "frame number within the same information type".

The "information type" is an area for storing the type of downlink information provided by the optical beacon 4 to the vehicle 20. In the "information type", numerical values from 1 to 63, which are ID values set in advance according to the type of provided information, are stored.

The "final frame flag" is a storage area for indicating which of one or a number of downlink frames of the same information type transmitted by the optical beacon 4 is the final frame.
For example, the optical beacon 4 has a predetermined flag value (for example, "1") only for the "final frame flag" of the last downlink frame among a plurality of downlink frames of the same information type that are continuously transmitted in one downlink cycle. ”) Is stored, and the flag value is not stored in other downlink frames of the same information type. Further, when the optical beacon 4 transmits only one downlink frame, the optical beacon 4 sets the final frame flag in the downlink frame.

The "frame number within the same information type" is the sequence number of the downlink frame when the information of the same type is transmitted in one downlink frame or is divided into a plurality of downlink frames and continuously transmitted.
When the optical beacon 4 continuously transmits one provided information, the maximum number of downlink frames is defined as 80 frames (including the first frame for storing lane notification information). Therefore, for example, when 80 downlink frames are continuously transmitted, the optical beacon 4 stores the number values 1 to 80 in order from the first downlink frame in the "frame number within the same information type". A number value is added to the frame number even in the case of one frame transmission.

The type of information provided to the vehicle-mounted device 2 included in the actual data unit of the downlink may change before and after the optical beacon 4 receives the low-speed uplink frame from the vehicle-mounted device 2.
That is, the optical beacon 4 can switch the content of the information provided to the vehicle-mounted device 2 before and after the reception of the low-speed uplink frame.

Specifically, January 2016, when the optical beacon 4 transmits a downlink frame (hereinafter, referred to as “first downlink frame”) before receiving the low-speed uplink frame (before receiving the low-speed uplink). The UTMS Association's "Advanced Optical Beacon Near Infrared AMIS Communication Application Standard Version 3" (hereinafter referred to as "Communication Application Standard (Version 3)"), which was formulated on the 28th, requires the provision of uplink information. Information specified not to be specified (such as "current position information") can be included in the actual data section.

Further, the optical beacon 4 uses a communication application standard (version 3) for a downlink frame (hereinafter referred to as "second downlink frame") transmitted after receiving a low-speed uplink frame (after receiving a low-speed uplink). In addition to the information that is not stipulated that the provision of uplink information is a condition, the information that is stipulated in the communication application standard (version 3) that the provision of uplink information is a condition (such as "route signal information") Can also be included in the actual data section.

When the information provided to the vehicle-mounted device 2 in a single information type fits in the capacity (123 bytes) of the actual data unit, the optical beacon 4 provides the provided information to the vehicle-mounted device 2 by one downlink frame.
When the information provided to the vehicle-mounted device 2 in a single information type does not fit in the capacity (123 bytes) of the actual data unit, the optical beacon 4 divides the information into a plurality of downlink frames (downlink frame group) and transmits the information. The provided information is provided to the in-vehicle device 2. Therefore, downlink information of different information types is not mixed in one downlink frame.

As shown in FIG. 5, examples of the provided information included in the first downlink frame include, for example, "lane notification information" (however, information in which the identification value of the vehicle ID is not stored) and "current position information". There is. The "lane notification information" is information for notifying the lane number in which the vehicle 20 is traveling, and the "current position information" is the position information (latitude and longitude) of the installation point of the beacon head 8.
The storage area of the "lane notification information" includes a "vehicle ID", a "lane number", a "beacon identification flag" and the like. The optical beacon 4 does not store an identification value (ID value) in the "vehicle ID" in the lane notification information included in the first downlink frame before receiving the uplink.

When the optical beacon 4 receives a low-speed ascending frame including the identification value (ID value) of the vehicle ID from the vehicle-mounted device 2, the optical beacon 4 stores the acquired ID value in the "vehicle ID" of the lane notification information. Hereinafter, this downlink frame is also referred to as a “wrapping frame”), and the generated wrapping frame is continuously transmitted.
Therefore, the vehicle-mounted device 2 can determine the establishment of communication with the optical beacon 4 depending on whether or not the ID value of the own vehicle is included in the lane notification information of the received return frame.

The optical beacon 4 describes the lane number value corresponding to the beacon head 8 for which the uplink information has been acquired in the "lane number" of the lane notification information included in the return frame.
Therefore, the vehicle-mounted device 2 can determine which lane the own vehicle is traveling from from the lane number value included in the lane notification information of the received return frame.

The "beacon identification flag" is a storage area indicating whether or not the own device is a device that supports high-speed uplink reception.
The optical beacon 4 that supports high-speed uplink reception stores a predetermined flag value (for example, "01") in the "beacon identification flag" of the downlink frame, and the old optical beacon that does not support high-speed uplink reception is Other values (for example, "00") are stored in the "beacon identification flag" of the downlink frame.

Therefore, the on-board unit 2 determines whether the optical beacon of the communication partner is a new optical beacon 4 that supports high-speed uplink reception, or does not support it, depending on the value of the "beacon identification flag" included in the "lane notification information" of the downlink. It is possible to determine whether it is an old optical beacon of.

The type of the downlink frame for turning on the flag field of the lane notification information (beacon identification flag = 01) may be both the first and second downlink frames, or may be only the second downlink frame. However, as shown in FIG. 5, the latter case is assumed in the present embodiment.
That is, in the optical beacon 4 of the present embodiment, the flag field of the first downlink frame is set to off (beacon identification flag = 00), and the flag field of the second downlink frame is set to on (beacon identification flag = 01). Set.

The downlink frame group repeatedly transmitted by the transmission / reception unit 11 of the optical beacon 4 after receiving the low-speed uplink is composed of 1 to 80 downlink frames, and in the case of the old interface standard, the transmittable time of the repeated transmission is 250 ms. be.
Further, the downlink frame is composed of an arbitrary number of frames according to the amount of data to be transmitted in the downlink direction, and is repeatedly transmitted within the above-mentioned transmittable time range, and the transmission cycle of the downlink frame is about 1 ms.

Therefore, for example, when one significant data (provided information) is composed of three downlink frames, the transmission cycle is about 3 ms, and the data is transmitted about 80 times within a predetermined transmittable time (250 ms). It will be sent repeatedly.
However, in the optical beacon of the new interface standard, since the downlink region DA is expanded to the vicinity immediately below the beacon head 8, the number of times of repeatedly transmitting the downlink frame group composed of 1 to 80 downlink frames is increased. be able to.

As shown in FIG. 5, examples of the provided information included in the second downlink frame include, for example, "lane notification information" (however, the identification value of the vehicle ID is stored), "route signal information", and "route signal information". "Travel speed link information" and so on.
The "lane notification information" is as described above. The "route signal information" is the route signal information of an intersection located on the downstream side of the installation point of the optical beacon 4. The "travel speed link information" is the travel speed information of the provided link preset for each optical beacon 4.

[Road-to-vehicle communication in the communication area]
FIG. 6 is a sequence diagram showing an example of road-to-vehicle communication performed in the communication area A.
In FIG. 6, the downlink frame DL1 is a downlink frame (first downlink frame) that the optical beacon 4 repeatedly transmits in the initial state before receiving the low-speed uplink.
The downlink frame DL2 is a downlink frame (second downlink frame) that the optical beacon 4 repeatedly transmits after receiving the low-speed uplink.

The uplink frame UL1 is a low-speed uplink frame transmitted by the vehicle-mounted device 2 in response to reception of the downlink frame DL1. The low-speed ascending frame UL1 is also referred to as "low-speed frame UL1".
The uplink frame UL2 is a high-speed uplink frame transmitted by the vehicle-mounted device 2 in response to reception of the downlink frame DL2. The high-speed ascending frame UL2 is also referred to as a "high-speed frame UL2".
The frame with a white circle indicates a frame in which the ID value is not stored in the vehicle ID, and the frame with a black circle indicates a frame in which the ID value is stored in the vehicle ID.

In FIG. 6, U0 to U3 indicate a plurality of uplink frames (uplink frame group) UL1 and UL2 that the vehicle-mounted device 2 performs uplink transmission.
FIG. 6 illustrates a case where the number of frames in the upstream frame group is four, but the number of frames is not limited to four. For example, in the uplink frame group, three or more high-speed frames UL2 may be transmitted (maximum 16 frames according to the standard), or only one high-speed frame UL2 having a relatively long data length may be transmitted. ..

The upstream frame U0 without hatching indicates that it is a low-speed frame UL1 having a low transmission speed (64 kbps), and the upstream frames U1 to U3 with hatching are high-speed frames UL2 having a high transmission speed (256 kbps). Show that.
In the following description of road-to-vehicle communication, the operating subjects are the optical beacon 4 and the in-vehicle device 2, but the actual communication control is performed by the beacon controller (communication control unit) 7 of the optical beacon 4 and the in-vehicle device 2. The in-vehicle controller (communication control unit) 21 executes the operation.

As shown in FIG. 6, the optical beacon 4 receives a downlink frame DL1 including lane notification information in which the ID value is not stored in the vehicle ID from all the beacon heads 8 corresponding to the lanes R1 to R4 (see FIG. 2). , Continues to transmit toward the road R at a predetermined transmission cycle.
When the vehicle 20 traveling in any of the lanes R1 to R4 of the road R enters the downlink region DA, the on-board unit 2 receives the downlink frame DL1 or the other downlink frame DL1 including the lane notification information (no ID value). .. As a result, the vehicle-mounted device 2 detects that the own vehicle has entered the communication area A of the optical beacon 4.

At this time, the in-vehicle device 2 stores the ID value of the own vehicle in the vehicle ID, and sets the low-speed frame UL1 (hereinafter, also referred to as “ID storage frame U0”) in which the value of the in-vehicle device type is “6”. It is generated, the communication of the own machine is once switched from reception to transmission, and the generated low-speed frame UL1 is uplink-transmitted. After that, the vehicle-mounted device 2 returns the communication of its own device from transmission to reception.
When the on-board unit 2 has information to be provided to the optical beacon 4 such as travel time information, the in-vehicle device 2 stores the information in the actual data unit of the low-speed frame UL1 (ID storage frame U0).

When the low-speed frame UL1 is normally received after the CRC check of the reception frame, the optical beacon 4 includes the acquired ID value in the vehicle ID and the lane notification information in which the value of the beacon identification flag is "01". The downlink frame DL2 (hereinafter, also referred to as “wrapping frame”) is continuously transmitted.
The optical beacon 4 is a downlink frame including other provided information after the elapse of the period for continuously transmitting the above lane notification information (defined as 8 ± 2 ms in the interface standard. Hereinafter referred to as “continuous transmission period”). Repeated transmission of DL2 is executed every predetermined downlink cycle.

The plurality of downlink frames DL2 included in one downlink cycle are downs other than the first return frame (downlink frame DL2 including lane notification information with an ID value) and the lane notification information continuously transmitted thereafter. It consists of one or a plurality of downlink frames DL2 including link information.
The repeated transmission of the downlink frame DL2 performed after the continuous transmission period is repeated as much as possible within a predetermined time (for example, 350 ms).

Since the downlink frame DL2 included in one downlink cycle is composed of a maximum of 80 frames, the lane notification information transmitted by the first frame of the downlink cycle is one in 80 frames in the least frequent case. It becomes.
When the high-speed frames U1 to U3 are transmitted after the low-speed frame U0, the on-board unit 2 defines a "transmission interruption period" (maximum 20 ms in the new interface standard) between the low-speed frame U0 and the high-speed frame U1. ) Is provided to prepare for reception, and the return frame is received during this transmission interruption period.

The vehicle-mounted device 2 determines whether or not any of the downlink frames DL2 received from the optical beacon 4 includes lane notification information in which the ID value of the own vehicle is stored in the vehicle ID.
If the above determination result is affirmative, the on-board unit 2 determines that the loopback of the ID value of the own vehicle has succeeded, and receives the communication status of the own unit until the above transmission interruption period elapses. Keep it as it is.

While the above determination result is negative, the on-board unit 2 determines that the loopback of the ID value of the own vehicle has not succeeded, switches the communication state of the own unit from reception to transmission, and the uplink frame UL1. (See the upstream frame U0 shown by the broken line in FIG. 6).
In this case, the vehicle-mounted device 2 transmits the uplink frame UL1 again after a predetermined time (for example, 30 ms) has elapsed after the transmission of the uplink frame UL1 transmitted earlier. The vehicle-mounted device 2 repeats this retransmission operation until the loopback of the ID value of the own vehicle is successful.

The on-board unit 2 determines whether the communication partner supports or does not support high-speed uplink reception based on the beacon identification flag included in the downlink frame DL2 received during the transmission interruption period, and according to the determination result. It is determined whether or not to transmit the high-speed frames U1 to U3.
That is, the on-board unit 2 transmits the high-speed frame UL2 (U1 to U3) after the transmission interruption period when the above determination result is positive, and when the above determination result is negative, the high-speed frame Do not send UL2.

[Problems caused by reflected light from downlink light and their solutions]
In the optical beacon 4 having a plurality of beacon heads 8 installed in each lane R1 to R4 (see FIG. 2), for example, the reflected light of the downlink light DO from the beacon head 8 in one lane R1 is the reflected light in another lane R2. Beacon head 8 may be reached.
In this case, the beacon head 8 in the lane R2 may not be able to receive the uplink light UO transmitted by the vehicle 20 passing through the lane R2 due to the influence of the reflected light, and may fail to receive the uplink frames UL1 and UL2 in the lane R2. There is.

Further, the downlink light DO transmitted by the beacon head 8 of the lane R4, which is the traveling lane, is reflected by a roadside tree or the like and reaches the beacon head 8 of the same lane R4, so that the ascending frames UL1 and RL2 in the lane R4 are reached. It may worsen the reception rate of.
In particular, since the high-speed frame UL2 has a transmission speed closer to that of the downlink light DO than the low-speed frame UL1, it is more susceptible to the influence of the reflected light of the downlink light DO than the low-speed frame UL1, and the above problems are more remarkable. Is thought to be.

Therefore, in the optical beacon 4 of the present embodiment, the “light emission control process” (FIG. 6) temporarily stops the light emission of the downlink light DO by the beacon head 8 according to the period during which the high-speed frame UL2 is received from the vehicle-mounted device 2. See). The downlink frame DL2 shown by the virtual line in FIG. 6 indicates a downlink frame in which the emission of the downlink light DO is stopped.
This makes it easier for the optical beacon 4 to receive the high-speed frame UL2 that the in-vehicle device 2 corresponding to the high-speed uplink transmission transmits in the uplink, and suppresses the high-speed uplink communication from being hindered by the reflected light of the downlink light DO. can do.

In the present embodiment, the "light emission stop" of the downlink light DO is, for example, stopping the transmission of the downlink signal (electrical signal) from the beacon controller 7 to the communication light emitting unit 13, and the communication light emitting unit 13. It can be executed by stopping the light emission by the light emitting element.
The method of executing the light emission stop is not only to stop the transmission of the downlink signal, but also to stop applying the voltage to the light emitting element, physically shield the downlink light DO, and so on, to provide the downlink light UO to the outside of the beacon head 8. Any means can be used as long as it can be done without issuing it.

However, not only when the light emission by the light emitting unit 13 is completely eliminated, but also when a part of the plurality of light emitting elements is turned off, or when the light emitting element of the communication light emitting unit 13 having a dimming function is set to a predetermined value. The following reductions are also included in the concept of "light emission stop".

The light emission control process of the downlink light DO executes, for example, when the stop and restart conditions are satisfied in one lane R1 (see FIG. 2), the light emission stop and light emission restart of the downlink light DO is executed only for the lane R1. Two types of processing are mainly considered, one is "1 processing" and the other is "second processing" for stopping and resuming light emission of the downlink light DOs of all lanes R1 to R4, and any of them may be adopted. .. Further, the downlink light DO may be stopped and restarted for some lanes including the lane R1 (for example, the lane R1 and its adjacent lane), or a part excluding the lane R1 or The downlink light DO may be stopped and restarted for all lanes.
The present embodiment assumes a case where the optical beacon 4 executes the first process.

By the way, the start of reception of the high-speed frame UL2 by the optical beacon 4 differs depending on the response speed of the vehicle-mounted device 2 to the return frame received by the vehicle-mounted device 2 during the transmission interruption period. Further, the end of reception of the high-speed frame UL2 by the optical beacon 4 differs depending on the number of frames of the high-speed frame UL2 transmitted by the vehicle-mounted device 2.
Therefore, in order to appropriately execute the light emission control process of the downlink optical DO according to the reception period of the high-speed frame UL2, it is necessary to set appropriate stop and restart timings in advance.

The beacon controller (communication control unit) 7 of the present embodiment stops the light emission of the downlink light DO by the communication light emitting unit 13 when the stop condition described below is satisfied, and the restart condition described below is met. With the establishment, it has a function as a "light emission control unit" that restarts the light emission of the downlink light DO by the communication light emitting unit 13.

[Downlink light stop and restart timing]
FIG. 7 is a time chart showing an example of stop and restart timings of light emission of the downlink light DO applicable to the optical beacon 4.
In FIG. 7, the upper bar graph shows the transmission timing of the downlink frame DL2 by the optical beacon 4, and the lower bar graph shows the reception timing of the uplink frames UL1 and UL2 by the optical beacon 4. Time t progresses from left to right.

The hatched downlink frame DL2 is a downlink frame that stores lane notification information at the beginning of the downlink 80 frame, and the dotted downlink frame DL2 is the next downlink frame at the time when the condition is satisfied.
As shown in FIG. 7, in the optical beacon 4 of the present embodiment, the communication light emitting unit (optical transmission unit) 13 is triggered by the establishment of at least one of the stop conditions 1 and 2, which are necessary and sufficient conditions for stopping the light emission. The light emission of the downlink light DO is stopped, and the light emission of the downlink light DO by the communication light emitting unit 13 is restarted when at least one of the restart conditions 1 to 3 which is a necessary and sufficient condition for restarting the light emission is satisfied. ..

In the optical beacon 4 of the present embodiment, when any of the stop conditions 1 and 2 shown in FIG. 7 and other stop conditions are satisfied, the light emission of the downlink light DO is stopped. May be good.
In the optical beacon 4 of the present embodiment, when any of not only the restart conditions 1 to 3 shown in FIG. 7 but also other restart conditions are satisfied, the light emission of the downlink light DO is restarted. May be good.

Hereinafter, the stop conditions 1 and 2 and the restart conditions 1 to 3 shown in FIG. 7 will be described. In the following description, "reception" of a frame means a time when the CRC check for the frame is completed.
Further, in the following description, the operating subject is the optical beacon 4, but the actual information processing is executed by the beacon controller (communication control unit) 7 of the optical beacon 4.

Further, the stop conditions 1 and 2 include identification information indicating that the vehicle is an advanced in-vehicle device (value for each in-vehicle device = "6" (may be "E" indicating a new in-vehicle device compatible with full duplex)). It is included as a precondition (necessary condition) that the optical beacon 4 receives the low-speed frame UL1 including the above.
The reason is that in order to eliminate the reception failure of the high-speed frame UL2, it is premised that the in-vehicle device 2 transmits the high-speed frame UL2, and the low-speed frame UL1 including identification information indicating that the in-vehicle device is an advanced in-vehicle device is included. This is because the premise is established when the optical beacon 4 receives the above.

(Stop condition 1 and light emission stop 1)
As shown in FIG. 7, the optical beacon 4 executes the “light emission stop 1” when the “stop condition 1” is satisfied. That is, the light emission stop 1 is a process corresponding to the stop condition 1.
Specifically, the stop condition 1 is an example of the low-speed frame UL1 including the identification information indicating the advanced in-vehicle device, for example, a predetermined delay period from the reception of the low-speed frame UL1 in which the value of the in-vehicle device type is "6". D1 (for example, 10 ms) has elapsed, and the light emission stop 1 is executed at the time when the head of the next downlink frame DL2 at the time when the stop condition 1 is satisfied is transmitted.

In the stop condition 1, the reason why the time when the condition is satisfied is delayed by the delay period D1 from the reception of the low-speed frame UL1 is that when the light emission of the downlink light DO is immediately stopped at the time of reception of the low-speed frame UL1, the lane notification information (lane notification information during the continuous transmission period) This is because there is a high possibility that (with an ID value) cannot be transmitted, or the number of transmissions is reduced, and communication with the vehicle-mounted device 2 cannot be established.
Therefore, the delay period D1 of the stop condition 1 preferably substantially coincides with the continuous transmission period (8 ± 2 ms) of the interface standard, and 10 ms (maximum value) is adopted in this embodiment.

The delay period D1 may be measured based on the time measured by the timer built in the beacon controller 7, or the downlink frame DL2 (downlink signal composed of an electric signal) continuously generated by the beacon controller 7. It may be performed based on the number of frames of.
The transmission time for one frame of the downlink frame DL2 is approximately 1 ms. Therefore, when the delay period D1 is set to 10 ms, it can be determined that the delay period D1 has elapsed when the downlink signal for 10 frames is transmitted.

The reason why the light emission stop 1 is executed at the time when the head of the next downlink frame DL2 at the time when the stop condition 1 is satisfied is transmitted is that if the emission of the downlink light DO is stopped at the boundary of the downlink frame DL2, the amount of light is abrupt. This is to prevent the downlink communication in the other lanes from being hindered as the decrease extends to the other lanes.
For example, the optical beacon 4 synchronizes the downlink frames DL1 and DL2 from the plurality of beacon heads 8 to transmit downlinks, and the light emission is stopped only in the lane in which the stop condition 1 is satisfied (for example, lane R1). It is assumed that it is executed by.

In this case, if the light emission is stopped in the middle of the down frame DL2 in the lane R1, the amount of light in the adjacent lane R2 decreases in the middle of the down frame DL2, and the on-board unit 2 of the vehicle 20 traveling in the lane R2 is the down frame DL2. There is a high possibility that reception will fail.
On the other hand, when the light emission is stopped at the head of the down frame DL2 in the lane R1, the amount of light in the adjacent lane R2 also decreases at the head of the down frame DL2, and the on-board unit 2 of the vehicle 20 traveling in the lane R2 is the down frame. The possibility of failing to receive DL2 is reduced.

(Stop condition 2 and light emission stop 2)
The optical beacon 4 executes "light emission stop 2" when the "stop condition 2" is satisfied. That is, the light emission stop 2 is a process corresponding to the stop condition 2.
Specifically, the stop condition 2 is that the high-speed frame UL2 is received for the first time after the low-speed frame UL1 is received (hereinafter, referred to as “first reception”), and the light emission stop 2 is next to the time when the stop condition 2 is satisfied. It is executed at the time of transmitting the head of the downlink frame DL2.

The reason for adopting the first reception of the high-speed frame UL2 in the stop condition 2 is that, among the high-speed frame UL2 transmitted up to 16 frames, if the light emission is stopped triggered by the first reception, the high-speed frame UL2 related to the first reception is used. This is because it leads to the elimination of the reception failure of the remaining high-speed frame UL2, which is transmitted by uplink later.
For example, it is assumed that the vehicle-mounted device 2 transmits 16 high-speed frames UL2, and the optical beacon 4 receives the third high-speed frame UL2 for the first time.

In this case, if the light emission is stopped before the fourth high-speed frame UL2 starts to be received, the reception rate of the fourth to 16th high-speed frames UL2 can be improved.
The reason why the light emission stop 2 is executed at the time when the head of the next downlink frame DL2 at the time when the stop condition 2 is satisfied is transmitted is the case of the light emission stop 1 (suppressing the inhibition of downlink communication in other lanes). Is similar to.

In order to increase the number of frames of the high-speed frame UL2 for eliminating the reception failure, it is preferable to stop the light emission triggered by the first reception of the high-speed frame UL2 as described above, but the high-speed frame UL2 is performed a plurality of times (for example). The light emission may be stopped when the reception (such as twice) is triggered.

The optical beacon 4 of the present embodiment may adopt both the stop conditions 1 and 2, or may adopt either the stop condition 1 or 2. In the example of FIG. 7, since the stop condition 2 is satisfied later than the stop condition 1, when both the stop conditions 1 and 2 are adopted, the stop condition 2 is a pack-up stop of the stop condition 1. It becomes a condition.
That is, even if the light emission stop 1 based on the stop condition 1 fails, the light emission stop 2 of the downlink light DO can be reliably executed by executing the light emission stop 2 based on the stop condition 2.

On the contrary, if the timing at which the stop condition 1 is satisfied is later than that of the stop condition 2 depending on the setting of the delay period D1, the stop condition 1 becomes a backup stop condition of the stop condition 2.
That is, even if the light emission stop 2 based on the stop condition 2 fails, the light emission stop 1 of the downlink light DO can be reliably executed by executing the light emission stop 1 based on the stop condition 1.

In the optical beacon 4 of the present embodiment, the light emission stop 1 and 2 may be executed immediately when the condition is satisfied, without waiting for the head of the next downlink frame DL2 when the condition is satisfied. However, there is a processing delay due to information processing in the beacon controller 7 from the time when the stop conditions 1 and 2 are satisfied until the light emission of the downlink light DO is actually stopped.
Further, the light emission stop 1 and 2 may be performed at the delimiter of the downlink frame DL2 after the condition is satisfied. For example, the light emission stop 1 and 2 may be performed at the delimiter of the first downlink frame DL2 and the second downlink frame DL2 when the condition is satisfied. May be good.

(Resume condition 1 and light emission restart 1)
As shown in FIG. 7, the optical beacon 4 executes the “light emission restart 1” when the “restart condition 1” is satisfied. That is, the light emission restart 1 is a process corresponding to the restart condition 1.
Specifically, the restart condition 1 is that a predetermined delay period D2 has elapsed from the first reception of the high-speed frame UL2 while the light emission is stopped, and the light emission restart 1 is the next downlink frame at the time when the restart condition 1 is satisfied. It is executed at the time of transmitting the head of DL2.

In the restart condition 1, if the "frame number within the same information type" included in the high-speed frame UL2 of the first reception is used, there is a delay after the completion of reception of the final frame of the upstream frame group consisting of a plurality of high-speed frames UL2. The period D2 can be calculated. For example, for the optical beacon 4, the delay period D2 may be calculated by the following formula.
Delay period D2 = (16-frame number value) x 1 frame transmission time

In the above calculation formula, the "1 frame transmission time" is the time (= about 2.3 ms) required for the vehicle-mounted device 2 to transmit one high-speed frame UL2, and in the present embodiment, a margin is added to this. Considering this, it is set to 3.0 ms.
Therefore, for example, when the value of the frame number of the high-speed frame UL2 related to the first reception is "5", the delay period D2 = (16-5) x 3 ms = 33 ms, and the time when 33 ms is added from the first reception restarts. It is the time when condition 1 is satisfied.

Instead of adding the margin to the transmission time of one frame, the margin α may be added to the total number of seconds after multiplication. That is, the delay period D may be calculated by the following formula.
Delay period D2 = (16-5) x 2.3 ms + α ≒ 25.3 ms + α = 26.0 ms

As described above, if the delay period D2 having the final period after the completion of reception of the final frame (16 frames, which is the maximum number of frames in the standard) of the upstream frame group consisting of a plurality of high-speed frames UL2 is adopted, the delay period D2 after the first reception is adopted. It becomes possible to suppress the reception failure of all the remaining high-speed frames UL2.
However, the delay period D2 may be set to a fixed time length that can cover the remaining reception time of the high-speed frame UL2. As the fixed time length, for example, the maximum time (= 38 ms: idle 5 bytes + 16 frame transmission time) when the vehicle-mounted device 2 continuously transmits the high-speed frame UL2 may be adopted.

The fixed time length may be set in a table format as a plurality of setting values according to the number of remaining frames. An example of a plurality of setting values according to the number of remaining frames is as follows.
Remaining 15 frames: 15 × 2.3 = 34.5 ms → 35 ms is set as the set value.
Remaining 14 frames: 14 × 2.3 = 32.2 ms → 33 ms is set as the set value.
Remaining 13 frames: 13 × 2.3 = 29.9 ms → 30 ms is set as the set value.
(Omitted)
Remaining 2 frames: 2 × 2.3 = 4.6 ms → 5 ms is set as the set value.
The remaining 1 frame: 1 × 2.3 = 2.3 ms → 3 ms is set as the set value.

Similar to the delay period D1, the delay period D2 may be measured based on the time measured by the timer of the beacon controller 7, or the downlink frame DL2 (from the electric signal) continuously transmitted by the beacon controller 7. It may be performed based on the number of frames of the downlink signal).
The transmission time for one frame of the downlink frame DL2 is approximately 1 ms. Therefore, when the delay period D1 is set to 33 ms, it can be determined that the delay period D2 has elapsed when the downlink signal for 33 frames is transmitted.

The reason why the light emission restart 1 is executed at the time when the head of the next downlink frame DL2 at the time when the restart condition 1 is satisfied is transmitted is that if the light emission of the downlink light DO is restarted at the break of the downlink frame DL2, the amount of light is abrupt. This is to prevent downlink communication in other lanes from being hindered as the increase extends to other lanes.
For example, the optical beacon 4 synchronizes the downlink frames DL1 and DL2 from the plurality of beacon heads 8 to transmit downlinks, and for restarting light emission, only the lane in which the restart condition 1 is satisfied (for example, lane R1) is used. It is assumed that it is executed by.

In this case, when the light emission is restarted in the middle of the down frame DL2 in the lane R1, the amount of light in the adjacent lane R2 increases in the middle of the down frame DL2, and the on-board unit 2 of the vehicle 20 traveling in the lane R2 is the down frame DL2. There is a high possibility that reception will fail.
On the other hand, when the light emission is restarted at the head of the down frame DL2 in the lane R1, the amount of light in the adjacent lane R2 also increases at the head of the down frame DL2, and the on-board unit 2 of the vehicle 20 traveling in the lane R2 is the down frame. The possibility of failing to receive DL2 is reduced.

(Resume condition 2 and light emission restart 2)
As shown in FIG. 7, the optical beacon 4 executes the “light emission restart 2” when the “restart condition 2” is satisfied. That is, the light emission restart 2 is a process corresponding to the restart condition 2.
Specifically, the restart condition 2 is that the low speed frame UL1 (UL1 shown by the broken line in FIG. 7) is further received in the lane in which the low speed frame UL1 is received while the light emission is stopped. It is executed at the time of transmitting the head of the next downlink frame DL2 at the time when the restart condition 2 is satisfied.

The reason for adopting that the low speed frame UL1 is received in the restart condition 2 is that another vehicle 20 enters the communication area A while the light emission is stopped, and the on-board unit (either old or new) of the vehicle 20 is low speed. When the frame UL1 is transmitted or when the same vehicle 20 retransmits the low-speed frame UL1, it is necessary to restart the light emission of the downlink light DO in order to establish communication with these vehicles 20. Is.

As the low-speed frame UL1 transmitted by another vehicle 20, for example, the low-speed frame UL1 received by the beacon head 8 in the lane in which light emission is stopped (for example, lane R1) can be considered. Further, the low-speed frame UL1 transmitted by another vehicle 20 may be the low-speed frame UL1 received by the beacon heads 8 of other lanes R2 to R4 other than the lane R1 in which light emission is stopped.

The reason why the light emission restart 2 is executed at the time when the head of the next downlink frame DL2 at the time when the restart condition 2 is satisfied is transmitted is the case of the light emission restart 1 (suppressing the inhibition of downlink communication in other lanes). Is similar to.

(Resume condition 3 and light emission restart 3)
As shown in FIG. 7, the optical beacon 4 executes the “light emission restart 3” when the “restart condition 3” is satisfied. That is, the light emission restart 3 is a process corresponding to the restart condition 3.
Specifically, the restart condition 3 is that a predetermined delay period D3 (for example, 45 ms) has elapsed from the actual light emission stop of the downlink light DO (light emission stop 1 in the example), and the light emission restart 3 is It is executed at the time when the head of the next downlink frame DL2 at the time when the restart condition 3 is satisfied is transmitted.

The reason for adopting the light emission stop of the downlink light DO in the restart condition 3 is that if the actual light emission stop time is used as the reference of the restart condition, the light emission restart 3 is executed when the stop condition 1 or 2 is satisfied. This is because, for example, the process of resuming light emission by the beacon controller 7 becomes simpler than the case of the restart condition 1 on which the first reception of the high-speed frame UL2 is premised because it is automatically determined.

Similar to the delay period D1, the delay period D3 may be measured based on the time measured by the timer of the beacon controller 7, or the downlink frame DL2 (from the electric signal) continuously transmitted by the beacon controller 7. It may be performed based on the number of frames of the downlink signal).
The transmission time for one frame of the downlink frame DL2 is approximately 1 ms. Therefore, when the delay period D3 is set to 45 ms, it can be determined that the delay period D3 has elapsed when the downlink signal for 45 frames is transmitted.

The optical beacon 4 of the present embodiment may adopt both the restart conditions 1 and 3, or may adopt any of the restart conditions 1 and 3. In the example of FIG. 7, since the restart condition 3 is satisfied later than the restart condition 1, when both the restart conditions 1 and 3 are adopted, the restart condition 3 is a pack-up restart of the restart condition 1. It becomes a condition.
That is, even if the light emission restart 1 based on the restart condition 1 fails, the light emission restart of the downlink light DO can be reliably executed by executing the light emission restart 3 based on the restart condition 3.

On the contrary, if the timing at which the restart condition 1 is satisfied is later than that of the restart condition 3, depending on the settings of the delay periods D2 and D3, the restart condition 1 becomes a backup restart condition of the restart condition 3.
That is, even if the light emission restart 3 based on the restart condition 3 fails, the light emission restart of the downlink light DO can be reliably executed by executing the light emission restart 1 based on the restart condition 1.

The light emission restart 2 based on the restart condition 2 has an exception handling element that another low-speed frame UL1 is received while the light emission is stopped.
Therefore, the optical beacon 4 of the present embodiment cannot adopt the restart condition 2 alone. That is, the restart condition 2 is a restart condition that should be adopted together with at least one of the restart conditions 1 and 3.

In the optical beacon 4 of the present embodiment, the light emission restarts 1 to 3 may be executed immediately according to the condition satisfaction without waiting for the head of the next downlink frame DL2 at the time when the condition is satisfied. However, there is a processing delay due to information processing in the beacon controller 7 from the time when the restart conditions 1 to 3 are satisfied until the light emission of the downlink light DO is actually restarted.
Further, the light emission restarts 1 to 3 may be performed at the delimiter of the downlink frame DL2 after the condition is satisfied. For example, the light emission restart is performed at the delimiter of the first downlink frame DL2 and the second downlink frame DL2 when the condition is satisfied. May be good.

[Modification of downlink light stop condition]
One of the information received by the optical beacon 4 from the central device 3 and the like is "probe management information". By receiving the probe management information from the central device 3, the optical beacon 4 sets the flag value of the beacon identification flag to "01" (advanced optical beacon corresponding to 256 kbit / s) and behaves as a new optical beacon.

The on-board unit 2 collects probe information regardless of the instruction from the optical beacon 4, but in the road-to-vehicle communication with the optical beacon 4 (advanced optical beacon) in which the value of the beacon identification flag is "01", the light concerned. Uplink transmission of probe information to Beacon 4 is performed.
In this way, the optical beacon 4 behaves as an advanced optical beacon by receiving the probe management information from the central device 3 and the like, and the probe information can be collected from the in-vehicle device 2.

On the other hand, when the "probe management information" has not been received from the central device 3 or the like, the optical beacon 4 sets the flag value of the beacon identification flag to "00" regardless of the vehicle-mounted model code included in the low-speed frame UL1. (Conventional 64 kbit / s compatible optical beacon) and behaves as an old optical beacon.
Therefore, in the case of the optical beacon 4 for which the probe management information has not been received, the high-speed frame UL2 cannot be received even if the communication partner is the on-board unit 2 compatible with 256 bits / s.

Therefore, the precondition (necessary condition) for stopping the downlink optical DO is the identification information indicating the advanced in-vehicle device (value for each in-vehicle device = "6" ("E" indicating the new in-vehicle device compatible with full duplex. It is preferable that the optical beacon 4 has already received the probe management information in addition to the reception of the low-speed frame UL1 including)).

That is, for the optical beacon 4, which behaves as an old optical beacon when the probe management information has not been received, the prerequisite for stopping the downlink optical DO is that the probe management information has been received and the vehicle is compatible with 256 bits / s. It is preferable to define that the low-speed frame UL1 from the machine 2 has been received.

[Modified example of downlink light restart condition]
In addition to the above-mentioned restart conditions 1 to 3, the optical beacon 4 has received the final frame of the high-speed frame UL2 in the lane in which the light emission is stopped (hereinafter, "restart condition 4"). ) May be adopted.

Among the restart conditions 1 to 4 of the present embodiment including the restart condition 4, the restart conditions related to the reception of the high-speed frame UL2 include the following restart conditions 1 and 4.
Resume condition 1: In the lane in which the light emission is stopped, a predetermined delay time D2 corresponding to the frame number in which the high-speed frame UL2 is first received has elapsed.
Resume condition 4: The final frame of the high-speed frame UL2 has been received in the lane in which the light emission is stopped.

Here, assuming that the light emission of the downlink light DO is stopped and restarted for each lane R1 to R4 (first process), the restart conditions 1 and 4 are the vehicle ID included in the immediately preceding low-speed frame UL1. It is preferable to confirm the coincidence of the above and then transition to the restart of light emission.
That is, it is preferable that the high-speed frame UL2 to which the restart conditions 1 and 4 are applied is limited to the one including the identification value of the vehicle ID of the low-speed frame UL1 received immediately before. The reason is as follows.

For example, it is assumed that the light emission stop of the lane R1 is being executed because the delay time D1 has elapsed from the reception of the low-speed frame UL1 transmitted by the vehicle 20 (ID value = x1) traveling in the lane R1 (stop condition). 1 and stop emitting light 1).
In this case, when the downlink light DO of the lane R1 is restarted by receiving the high-speed frame UL2 transmitted by another vehicle 20 (ID value = x2) traveling in the adjacent lane R2, the high speed of the vehicle 20 in the lane R1 is resumed. This is because the possibility that the frame UL2 cannot be received increases.

[Internal configuration of optical beacon]
FIG. 8 is a block diagram showing an example of the internal configuration of the optical beacon 4 in which the light emission control process can be executed for each of the lanes R1 to R4.
As shown in FIG. 8, the beacon controller 7 of the optical beacon 4 has a control board 32 having a control unit 31 composed of an FPGA (Field-Programmable Gate Array) and a signal which is a transmission path of a downlink signal (electric signal). A terminal block board 34 for organizing the wire 33 is provided. The control unit 31 may be configured by a communication IC or the like instead of the FPGA.

A communication light emitting unit 13 and a sensing light emitting unit 15 are housed inside the beacon head 8 corresponding to the lanes R1 to R4, respectively.
The control unit 31 includes a plurality of (four in the example) output ports that transmit downlink signals, and a signal line 33 is connected to each output port. Each of the signal lines 33 is connected to the communication light emitting unit 13 of the beacon head 8.

That is, the output port for transmitting the downlink signal 1 for the lane R1 is connected to the communication light emitting unit 13 of the beacon head 8 in the lane R1 by the signal line 33.
Similarly, the output ports that transmit the downlink signals 2 to 4 for lanes R2 to R4 are connected to the communication light emitting unit 13 of the beacon head 8 of lanes R2 to R4 by the signal line 33, respectively.

The control unit 31 is programmed so that the synchronization process for synchronizing the downlink signals 1 to 4 can be executed, and the light emission control process can be executed for each of the lanes R1 to R4.
For example, the control unit 31 executes the light emission stop and the light emission restart due to the reception of the low-speed frame UL1 in the lane R1 by the transmission stop and the transmission restart of the downlink signal 1 corresponding to the lane R1.

In this way, if an output port for independently outputting downlink signals 1 to 4 corresponding to lanes R1 to R4 is provided and a control unit 31 capable of executing light emission control processing for each lane R1 to R4 is adopted. , It is possible to manufacture an optical beacon 4 capable of executing light emission control processing for each of the lanes R1 to R4.

As shown in FIG. 8, the signal line 33 is branched inside the beacon head 8, and the branch line 35 indicated by the broken line branching from the signal line 33 is connected to the sensing light emitting unit 15.
Therefore, the optical beacon 4 of FIG. 8 is a type of optical beacon that synchronizes the incident light IO for vehicle detection with the downlink light DO. Therefore, when the sensing light emitting unit 15 that independently generates the incident light IO asynchronous with the downlink light DO is adopted, the branch line 35 is unnecessary. This point is the same in the optical beacon 4 of FIGS. 9 and 10 described later.

FIG. 9 is a block diagram showing another example of the internal configuration of the optical beacon 4 in which the light emission control process can be executed for each of the lanes R1 to R4.
In the optical beacon 4 of FIG. 9, the control unit 31 has only one downlink signal output port. The downlink signal signal line 33 connected to the output port is branched into a plurality of branches on the terminal block board 34, and each branch line is connected to the communication light emitting unit 13 of each lane R1 to R4.

Therefore, the downlink signal output by the control unit 31 branches inside the terminal block board 34 and is transmitted to the communication light emitting units 13 of the lanes R1 to R4, respectively.
Beacon heads 8 in each of the lanes R1 to R4 are provided with a switching element 36 for turning on / off signal transmission by the signal line 33.
The control unit 31 includes a plurality of (four in the example) output ports for transmitting light emission control signals 1 to 4, and a gate voltage control line 37 is connected to each output port. The control lines 37 are connected to the switching element 36 of the beacon head 8, respectively.

That is, the output port for transmitting the light emission control signal 1 for the lane R1 is connected to the switching element 36 of the beacon head 8 in the lane R1 by the control line 37.
Similarly, the output ports for transmitting the light emission control signals 2 to 4 for the lanes R2 to R4 are connected to the switching element 36 of the beacon head 8 of the lanes R2 to R4 by the control line 37, respectively.

The control unit 31 sends a common downlink signal for each lane R1 to R4 to each beacon head, and generates light emission control signals 1 to 4 only for lanes R1 to R4 in which predetermined stop conditions and restart conditions occur. It is programmed to do.
For example, the control unit 31 executes the light emission stop and the light emission restart due to the reception of the low-speed frame UL1 in the lane R1 by controlling the gate voltage of the switching element in the lane R1 by the light emission control signal 1.

As described above, in the case of the optical beacon 4 that employs the control unit 31 that outputs the downlink signal common to the lanes R1 to R4, the switching element 36 and the control that turn on / off the transmission of the downlink signal for each lane R1 to R4. By providing the line 37, it is possible to manufacture an optical beacon 4 capable of executing light emission control processing for each of the lanes R1 to R4.

FIG. 10 is a block diagram showing another example of the internal configuration of the optical beacon 4 in which the light emission control process can be executed for each of the lanes R1 to R4.
Similar to the optical beacon 4 of FIG. 9, the optical beacon 4 of FIG. 10 has a control unit 31 having only one downlink signal output port, and is the same due to the signal line 33 branched by the terminal block board 34. The downlink signal is transmitted to the beacon heads 8 of each lane R1 to R4, respectively.

The difference between the optical beacon 4 of FIG. 10 and the optical beacon 4 of FIG. 9 is that the switching element 36 that turns the transmission of the downlink signal on and off for each lane R1 to R4 is not the beacon head 8 but the terminal of the beacon controller 7. It is at the point where it is housed in the base substrate 34. The other configurations and operations are the same as in the case of the optical beacon 4 of FIG.

The embodiments disclosed this time should be considered as exemplary in all respects and not restrictive. The scope of rights of the present invention is indicated by the scope of claims rather than the contents of the above-described embodiment, and is intended to include meaning equivalent to the scope of claims and all modifications within the scope thereof.

1 Traffic control system 2 On-board unit 3 Central device 4 Optical beacon 5 Communication line 6 Communication unit 7 Beacon controller (communication control unit, light emission control unit)
8 Beacon head 9 Housing 11 Transmission / reception unit 12 Sensor unit 13 Light emitting unit for communication (optical transmitter)
14 Light receiving unit for communication (optical receiver)
15 Light emitting unit for sensing 16 Light receiving unit for sensing 17 Strut 18 Elevating bar 20 Vehicle 21 In-vehicle controller 22 In-vehicle head 23 Optical transmitter 24 Optical receiver 31 Control unit 32 Control board 33 Signal line 34 Terminal block board 35 Branch line 36 Switching element 37 Control line R Road R1 to R4 Lane

Claims (1)

An optical beacon including a plurality of optical beacon heads each having a light emitting unit for communication and an optical beacon controller for the plurality of optical beacon heads.
The optical beacon controller
A plurality of switching elements for controlling the light emission of the communication light emitting unit and a control board are provided.
The control board
It has a plurality of first output ports and a second output port.
The plurality of first output ports are
It is a port that is connected to each switching element by an individual signal line and outputs a control signal to each switching element for executing light emission control processing for each of the plurality of beacon heads.
The second output port is
An optical beacon that is connected to a plurality of the switching elements by a branched signal line and is a port for outputting a signal that causes the communication light emitting unit of the plurality of optical beacon heads to emit light.

Images