JP6725111B2 - Light beacon - Google Patents

Description

The present invention relates to an optical beacon that wirelessly communicates with an in-vehicle device of a running vehicle by an optical signal.

A so-called VICS (Vehicle Information and Communication System: registered trademark of the Road Traffic Information and Communication Systems Center) using optical beacons, radio beacons or FM multiplex broadcasting has already been deployed as a traffic information service using the road-vehicle communication system. ing.
Among them, the optical beacon employs optical communication using near infrared rays as a communication medium, and is capable of bidirectional communication with an in-vehicle device. Specifically, uplink information including travel time information between beacons held by the vehicle is transmitted from the vehicle-mounted device to the optical beacon on the infrastructure side.

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

JP, 2005-268925, A

In an optical beacon in which a beacon head is installed for each of a plurality of lanes, light emission control needs to be performed for a plurality of beacon heads.

The present invention has been made in view of such conventional problems, and 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) An optical beacon according to an aspect of the present invention includes a plurality of optical beacon heads each having a communication light emitting unit, and an optical beacon controller for the plurality of optical beacon heads. The plurality of optical beacon heads each include a switching element for controlling light emission of the communication light emitting unit, the optical beacon controller includes a control board, and the control board includes a plurality of first output ports and a second output. And a plurality of first output ports, the plurality of first output ports of the communication light emitting unit corresponding to one or more lanes including at least the lane when a predetermined stop condition or restart condition is satisfied in one lane. emitting a port for outputting a control signal for stopping or resuming the switching element, the second output port is a port for outputting a signal for emitting the passing credit emission units, a plurality of first output ports Are connected to the switching elements of a plurality of optical beacon heads in a one-to-one relationship by individual signal lines, and the second output port is a plurality of optical beacons in a one-to-many relationship by a branched signal line having a trunk line and a plurality of branch lines. The switching element is connected to the communication light emitting unit of the head, and each branch line of the branched signal line is provided with a switching element.

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 showing a schematic structure of a road-vehicle communication system. It is a top view of the road which looked at the installation part of an optical beacon from the above. It is a side view of a road showing a communication field and an incidence field of an optical beacon. It is a frame block diagram of an upstream frame. It is a frame block diagram of a downstream frame. It is a sequence diagram which shows an example of road-to-vehicle communication performed in a communication area. It is a time chart which shows an example of stop and start timing of light emission of downlink light applicable to an optical beacon. It is a block diagram which shows an example of an internal structure of the optical beacon which can perform light emission control processing for every lane. It is a block diagram which shows another example of the internal structure of the optical beacon which can perform light emission control processing for every lane. It is a block diagram which shows another example of the internal structure of the optical beacon which can perform light emission control processing for every lane.

<Outline of Embodiment of the Present Invention>
Hereinafter, the outline of the embodiments of the present invention will be listed and described.
(1) The optical beacon of the present embodiment includes 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 plurality of optical beacon heads each include a switching element for controlling light emission of the communication light emitting unit, the optical beacon controller includes a control board, and the control board includes a plurality of first output ports and a second output. And a plurality of first output ports, the plurality of first output ports of the communication light emitting unit corresponding to one or more lanes including at least the lane when a predetermined stop condition or restart condition is satisfied in one lane. emitting a port for outputting a control signal for stopping or resuming the switching element, the second output port is a port for outputting a signal for emitting the passing credit emission units, a plurality of first output ports Are connected to the switching elements of a plurality of optical beacon heads in a one-to-one relationship by individual signal lines, and the second output port is a plurality of optical beacons in a one-to-many relationship by a branched signal line having a trunk line and a plurality of branch lines. The switching element is connected to the communication light emitting unit of the head, and each branch line of the branched signal line is provided with a switching element.

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 the embodiment of the present invention>
Hereinafter, the embodiment of the present invention will be described in detail 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 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-vehicle communication system according to the present embodiment. FIG. 2 is a plan view of the road R in which the installation portion of the optical beacon 4 of this embodiment is viewed from above.
As shown in FIG. 1, the road-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 and the like, and a large number of optical beacons (optical vehicle detectors) 4 installed at 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 controller) 7 that performs communication control, and a plurality of (four in the example of FIG. 1) beacon heads (projection and reception of light) that are connected to the sensor interface of the beacon controller 7. Container) 8.

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 configured by, for example, a traffic signal controller that controls the color of a signal lamp, an information relay device that relays traffic information on the infrastructure side, or the like.

The optical beacon 4 of this embodiment employs a full-duplex communication system. That is, the beacon controller 7 simultaneously performs downlink direction transmission control for the optical communication light emitting unit 13 and uplink direction reception control for the optical communication light receiving unit 14.
On the other hand, the vehicle-mounted device 2 of this embodiment employs the half-duplex communication method. That is, the vehicle-mounted 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 transmitter 23 and reception control in the downlink direction with respect to the optical receiver 24.

[Overall structure of optical beacon]
The beacon head 8 of the optical beacon 4 includes a transceiver unit 11 (optical transceiver) 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, by incorporating the units 11 and 12 for optical communication and vehicle detection in the housing 9 of one beacon head 8, respectively, an optical communication function and a vehicle detection function are provided. The structure has both.

The transceiver unit 11 for optical communication is an optical transceiver that wirelessly transmits and receives an optical signal to and from the vehicle-mounted device 2.
As shown in FIG. 1, the transmission/reception unit 11 receives a light emitting unit 13 for optical communication that sends out a downlink light DO (see FIG. 3) and an uplink light UO (see FIG. 3) and converts it into an electric signal. And 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 at a predetermined transmission speed, And a light emitting element formed of a light emitting diode (LED) that converts the output transmission signal into an optical signal in the downlink direction.
The light emitting element of the communication light emitting unit 13 sends out the downlink light DO, which is a near-infrared light signal, 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 an electric signal output from the light receiving element including a photodiode (PD: Photo Diode) and the like. And a receiver circuit that generates a digital signal.
The light receiving element of the communication light receiving unit 14 receives the uplink light UO, which is an optical signal of near-infrared light 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 an optical sensor for noncontactly detecting the presence of the vehicle 20 passing directly under the beacon head 8.
As shown in FIG. 1, a sensor unit 12 includes a light emitting unit 15 for detecting a vehicle that emits incident light IO (see FIG. 3) and a vehicle that receives reflected light RO (see FIG. 3) and converts it into an electric signal. And a light receiving unit 16 for sensing.

The light emitting unit 15 for vehicle detection (hereinafter, also referred to as “light emitting unit 15 for detection”) sends out incident light IO which is an optical pulse signal of a predetermined cycle in a downward direction.
The light-receiving unit 16 for vehicle detection (hereinafter, also referred to as “light-receiving unit 16 for detection”) receives the reflected light RO of the incident light IO on the road R and the vehicle 20, 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 performs communication with the central device 3 and road-to-vehicle communication with the vehicle-mounted device 2 according to a predetermined communication interface standard. , And has a function as a sensing control unit of the vehicle 20.
In addition, the beacon controller 7 stores a computer program for communication control and sensing control in a storage device (not shown), and the CPU reads and executes this program so that 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 an identification value of a vehicle ID (hereinafter, also referred to as “ID value”) is not stored, and predetermined provision information. The downlink signal (first downlink frame) including the is always transmitted to the communication light emitting unit 13 at a predetermined cycle.
The beacon controller 7 continues the transmission of the downlink signal and receives the uplink signal (uplink frame) including the ID value, which the vehicle-mounted device 2 will transmit when the downlink signal is received. The presence or absence is judged.

When the beacon light receiving unit 14 detects the reception of the uplink signal by the communication light receiving unit 14, the beacon controller 7 stores the lane notice information storing the ID value and the lane number value extracted from the uplink signal, and the provision information for the vehicle 20. Then, the communication light emitting unit 13 is caused to send out one or a plurality of downlink signals (second downlink frames) including the generated information for a predetermined time (for example, 250 to 350 ms).

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

The beacon controller 7 constantly causes the incident light IO having a predetermined wavelength to be sent to the sensing light emitting unit 15 at a constant intensity and a pulse cycle, and whether the received light intensity of the reflected light RO received by the sensing light receiving unit 16 is a threshold value or more. The presence of the vehicle 20 is sensed depending on whether or not the vehicle 20 is present.
That is, the beacon controller 7 generates a sensing signal of the vehicle 20 and transmits the sensing signal to the central unit 3 when the received light intensity of the reflected light RO that is equal to or more than the threshold is detected by the sensing light receiving unit 16. Note that this threshold value is not limited to a fixed value, and may change, for example, due to the tracking process according to the received light 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 illustrated example) lanes R1 to R4 in the same direction.
The optical beacon 4 includes a plurality of the beacon heads 8 provided corresponding to the respective lanes R1 to R4, and one beacon controller 7 that is a communication control unit that collectively controls the beacon heads 8. Prepare

The beacon controller 7 is installed on a pillar 17 standing on the sidewalk portion on the left side of the road R. Each beacon head 8 is attached to a erection bar (beam member) 18 that is horizontally erected on the road R side from the pillar 17, and is arranged just above the center position of each of the lanes 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 from directly below itself. As a result, the communication area A for performing road-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 the incident light IO almost directly below itself. As a result, the incident area B, which is the sensing area of the vehicle 20 passing through the predetermined lanes R1 to R4 of 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 a downlink area DA (solid line hatching portion), which is a light receiving area of the downlink light DO by the vehicle-mounted device 2, and an uplink light UO by the beacon head 8. And an uplink area UA (a hatched portion with a broken line) which is a light-receivable range.

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

In the "Advanced Optical Beacon Near-Infrared Interface Standard Version 4" (hereinafter referred to as "new interface standard") of the UTMS Association established on January 28, 2016, the standard value of the upstream end position of each area DA, UA ( (For general roads) is as follows.
Downstream end position a0 of the downlink area DA: +0.70 m
Downstream end position b0 of the uplink area UA: a0+2.70 m (=3.40 m)
Upstream end position c0 of both areas DA and UA: b0+2.64 m (=6.04 m)
The standard value of each of the positions a0 to c0 is a value when the upstream direction from the position (origin O) immediately below the light emitter/receiver 8 on the reference plane having a height H from the road surface of 1.0 m is a positive number. ..

According to 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 the conventional one, but the transmission speed of the uplink optical UO is two types of high and low multirates (low speed is 64 kbit/s and high speed is 256 kbit/s). s) has been changed.

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

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 vehicle-mounted device 2 is a new vehicle-mounted device (advanced optical vehicle).

The incident area B of the sensor unit 12 is an irradiation range of the incident light IO that the sensing light emitting unit 15 enters toward the road R.
The center of the incident area B in the road width direction is substantially at the same position as 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 toward the upstream side (plus side) by a predetermined angle α (for example, 4.5°) with respect to the vertical direction, but it 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 in-vehicle device 2 of the present embodiment includes an in-vehicle controller (communication control unit) 21 and an in-vehicle head (optical transceiver unit) 22. An optical transmitter 23 and an optical receiver 24 are housed inside the vehicle-mounted head 22.
The optical transmitter 23 has a light emitting element that emits an uplink light UO (optical signal in the uplink direction) made of near infrared rays, and the optical receiver 24 has a downlink light UO (downlink direction in the near infrared rays). It has a light receiving element for receiving an optical signal).

The optical transmission unit 23 includes a transmission circuit that converts an upstream frame output from the vehicle-mounted controller 21 into a serial transmission signal having a predetermined transmission speed, and a light emission that converts the output transmission signal into an optical signal in the uplink direction. And a light emitting element formed of a diode or the like.
The optical receiving unit 24 includes a light receiving element that is 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 and generates a digital received signal. Have.

The in-vehicle controller 21 includes 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-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 the CPU functions as the communication control unit by the CPU reading and executing the program. To do.

The on-vehicle controller 21 generates travel data of the host vehicle (for example, probe information, which is travel locus data in which the passing position and the passing time are arranged in time series) as uplink data, and uploads it 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 (such as a longer road section for recording a traveling locus, or a higher recording density for passing positions and passing times in the same road section) can be obtained. Information).

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

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

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

The "number of subsystem key information" (hereinafter sometimes abbreviated as "number of information") stores the number of "subsystem key information" stored in order from the head of the actual data part.
That is, when the number of information is zero, the actual data part does not include “subsystem key information”, and when the number of information is “1”, the actual data part includes one “subsystem key information”, When the number of pieces of information is “n”, the actual data portion includes n pieces of “subsystem key information”.

In the above "subsystem key information", the optical beacon 4 is a downlink for public vehicle priority system (PTPS), vehicle operation management system (MOCS), on-site express support system (FAST), safe driving support system (DSSS), etc. It is key information for selecting additional information of information.
The in-vehicle device 2 determines the contents of the “subsystem key information number” and the “subsystem key information” depending on which system of the UTMS standard the vehicle supports.

For example, when the own vehicle corresponds to one system of the UTMS standard, the in-vehicle device 2 sets the value of “number of subsystem key information” in the header section to “1” and follows the standard of the one system. The "subsystem key information (1)" having the contents described above is stored in the actual data part.
Further, when the own vehicle is compatible with two systems of the UTMS standard, the vehicle-mounted device 2 sets the value of the “number of subsystem key information” in the header part to “2”, and each of the two systems has the standard. The "subsystem key information (1)" and "subsystem key information (2)" having the following contents are stored in the actual data part.

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

The optical beacon 4 determines which system the in-vehicle device 2 corresponds to in the UTMS standard according to the type of “subsystem key information” included in the uplink information, and provides information provided according to the standard of the system. Is stored in the downlink frame and is transmitted by 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 the uplink reception, based on the type of "subsystem key information".

The “vehicle ID” is an area for storing the identification value (either a numerical value or a symbol) of the vehicle ID generated by the vehicle-mounted device 2 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 in the header portion of the upstream 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 of these areas indicate the old and new of the uplink transmission subject and whether the uplink information is high speed or low speed.

Specifically, when transmitting the low-speed upstream frame, the vehicle-mounted device 2 stores a predetermined value (for example, “6”) indicating the new vehicle-mounted device in the “vehicle-mounted device type” and stores the predetermined value in the “information type”. The value (for example, “1”) is stored.
When transmitting a high-speed upstream frame, the vehicle-mounted device 2 stores a predetermined value (for example, “6”) indicating a new vehicle-mounted device in the “vehicle-mounted device type” and a predetermined value (for example, “6”) in the “information type”. , "4") is stored.

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

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

The “frame number within the same information type” is a sequence number of the upstream frame when information of the same information type is transmitted in one upstream frame or is divided into a plurality of upstream frames and continuously transmitted.
The maximum number of upstream frames that the vehicle-mounted device 2 can continuously transmit is specified to be 16 frames. Therefore, for example, when continuously transmitting 16 upstream frames, the vehicle-mounted device 2 stores a number value from 1 to 16 in order in the “frame number within the same information type” from the leading upstream frame. Note that a number value is added to the frame number even in the case of 1 frame transmission.

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

In the downlink frame, 1 byte is assigned to the synchronization part, 5 bytes to the header part, 123 bytes to the actual data part, 4 bytes 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", "last frame flag", and "frame number within 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. The "information type" stores a numerical value of 1 to 63 which is an ID value preset according to the type of the provided information.

The “final frame flag” is a storage area for indicating which of the one or the 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 in the "final frame flag" of the last downlink frame among a plurality of downlink frames of the same information type 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 transmitting only one downlink frame, the optical beacon 4 sets a final frame flag in the downlink frame.

The “frame number within the same information type” is a sequence number of the downlink frame when information of the same type is transmitted in one downlink frame or divided into a plurality of downlink frames and continuously transmitted.
The maximum number of downlink frames when the optical beacon 4 continuously transmits one piece of provision information is specified to be 80 frames (including the leading frame that stores lane notification information). Therefore, for example, when 80 downlink frames are continuously transmitted, the optical beacon 4 stores the number values from 1 to 80 in order in the “frame number within the same information type” from the leading downlink frame. Note that a number value is added to the frame number even in the case of 1 frame transmission.

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

Specifically, the optical beacon 4 has a downlink frame (hereinafter, referred to as “first downlink frame”) to be transmitted before receiving a low-speed uplink frame (before low-speed uplink reception), January 2016. UTMS Association's "Advanced Optical Beacon Near Infrared AMIS Communication Application Standard Version 3" (hereinafter referred to as "Communication Application Standard (Version 3)") established by the UTMS Association is subject to the provision of uplink information. Information (for example, “current position information”) specified not to be included can be included in the actual data part.

Further, the optical beacon 4 has 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 low-speed uplink). In addition to the information specified as not requiring the provision of uplink information, the information (such as "route signal information") specified as the condition for providing uplink information in the communication application standard (Version 3) Can also be included in the actual data part.

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

As shown in FIG. 5, examples of the provision information included in the first downlink frame include, for example, “lane notification information” (however, 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 on which the vehicle 20 travels, and the “current position information” is position information (latitude and longitude) of the installation point of the beacon head 8.
The storage area of the “lane notification information” includes “vehicle ID”, “lane number”, “beacon identification flag”, and the like. The optical beacon 4 does not store the 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 the low-speed upstream frame including the identification value (ID value) of the vehicle ID from the vehicle-mounted device 2, the second downlink frame (the vehicle ID) storing the acquired ID value in the “vehicle ID” ( Hereinafter, this downlink frame is also referred to as a “folded frame”), and the generated folded 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 received lane notification information of the return frame includes the ID value of the own vehicle.

The optical beacon 4 writes the lane number value corresponding to the beacon head 8 that has acquired the uplink information 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 vehicle is traveling in from the lane number value included in the received lane notification information of the return frame.

The “beacon identification flag” is a storage area indicating whether or not the own device is a device compatible with high-speed uplink reception.
The optical beacon 4 compatible with 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 not compatible with high-speed uplink reception is Other values (for example, "00") are stored in the "beacon identification flag" of the downlink frame.

Therefore, the in-vehicle device 2 determines whether the optical beacon of the communication partner is the new optical beacon 4 compatible with high-speed uplink reception or not depending on the value of the “beacon identification flag” included in the “lane notification information” of the downlink frame. It is possible to determine whether or not it is the old optical beacon of.

The types of downlink frames for which the flag field of the lane notification information is turned on (beacon identification flag=01) may be both the first and second downlink frames, or may be only the second downlink frames. However, as shown in FIG. 5, the latter case is assumed in this embodiment.
That is, the optical beacon 4 of the present embodiment sets the flag field of the first downlink frame to off (beacon identification flag=00) and turns on the flag field of the second downlink frame (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. In the case of the old interface standard, the transmittable time of the repeated transmission is 250 ms. is there.
The downlink frame is composed of an arbitrary number of frames according to the amount of data to be transmitted in the downlink direction, 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, so that the data is 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 area 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 provision 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".
The “lane notification information” is as described above. The “route signal information” is route signal information of an intersection located downstream of the installation location of the optical beacon 4. The “travel speed link information” is 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) repeatedly transmitted by the optical beacon 4 in the initial state before low-speed uplink reception.
The downlink frame DL2 is a downlink frame (second downlink frame) repeatedly transmitted by the optical beacon 4 after receiving the low speed uplink.

The upstream frame UL1 is a low-speed upstream frame transmitted by the vehicle-mounted device 2 in response to the reception of the downstream frame DL1. The low-speed upstream frame UL1 is also referred to as “low-speed frame UL1”.
The upstream frame UL2 is a high-speed upstream frame transmitted by the vehicle-mounted device 2 in response to the reception of the downstream frame DL2. The high-speed upstream frame UL2 is also referred to as “high-speed frame UL2”.
A frame with a white circle shows a frame in which an ID value is not stored in the vehicle ID, and a frame with a black circle shows that a frame has an ID value stored in the vehicle ID.

In FIG. 6, U0 to U3 indicate a plurality of uplink frames (uplink frame groups) UL1 and UL2 that the vehicle-mounted device 2 performs uplink transmission.
FIG. 6 exemplifies 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 upstream frame group, three or more high-speed frames UL2 may be transmitted (maximum 16 frames in 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 with a low transmission rate (64 kbitp/s), and the upstream frames U1 to U3 with hatching are high-speed frames UL2 with a high transmission rate (256 kbps). Indicates that.
In the following description of road-to-vehicle communication, the operation subject is the optical beacon 4 and the vehicle-mounted device 2. However, the actual communication control is performed by the beacon controller (communication control unit) 7 of the optical beacon 4 and the vehicle-mounted device 2. The in-vehicle controller (communication control unit) 21 executes this.

As shown in FIG. 6, the optical beacon 4 outputs the downlink frame DL1 including the lane notification information whose vehicle ID has no ID value stored therein from all the beacon heads 8 corresponding to the lanes R1 to R4 (see FIG. 2). , And continues to transmit to the road R at a predetermined transmission cycle.
When the vehicle 20 traveling on one of the lanes R1 to R4 on the road R enters the downlink area DA, the vehicle-mounted device 2 receives the downlink frame DL1 including the lane notification information (no ID value) or another downlink frame DL1. .. As a result, the vehicle unit 2 detects that the vehicle has entered the communication area A of the optical beacon 4.

At this time, the vehicle-mounted device 2 stores the low-speed frame UL1 (hereinafter, also referred to as “ID storage frame U0”) in which the vehicle ID is stored as the vehicle ID and the value of the vehicle-mounted device type is set to “6”. The generated low-speed frame UL1 is generated, the communication of the own device is once switched from reception to transmission, and the generated low-speed frame UL1 is transmitted by uplink. Then, the vehicle unit 2 returns the communication of the own unit from the transmission to the reception.
When there is information to be provided to the optical beacon 4 such as travel time information, the vehicle-mounted device 2 stores the information in the actual data portion of the low speed frame UL1 (ID storage frame U0).

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

A plurality of downlink frames DL2 included in one downlink cycle include one return frame at the beginning (a downlink frame DL2 including lane notification information with an ID value) and a downlink frame other than lane notification information continuously transmitted thereafter. It is composed 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 every 80 frames in the case of the least frequency. Becomes
When transmitting the high speed frames U1 to U3 after the low speed frame U0, the vehicle-mounted device 2 has 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 for the reception, and the return frame is received during the transmission interruption period.

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

While the above determination result is negative, the in-vehicle device 2 determines that the loopback of the ID value of the own vehicle has not succeeded, switches the communication state of the own device from reception to transmission, and transmits the uplink frame UL1. Is retransmitted (see the upstream frame U0 indicated by the broken line in FIG. 6).
In this case, the vehicle-mounted device 2 transmits the upstream frame UL1 again after a predetermined time (for example, 30 msec) has elapsed after transmitting the upstream frame UL1 transmitted earlier. The vehicle-mounted device 2 repeats this re-sending operation until loopback of the ID value of the own vehicle succeeds.

The vehicle-mounted device 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 the high speed frames U1 to U3 are transmitted.
That is, the in-vehicle device 2 transmits the high speed frame UL2 (U1 to U3) after the transmission interruption period when the above determination result is affirmative, and when the above determination result is negative, the high speed frame is transmitted. Do not send UL2.

[Problems due to reflected light of downlink light and its solution]
In the optical beacon 4 having the plurality of beacon heads 8 installed for each of the lanes R1 to R4 (see FIG. 2), for example, the reflected light of the downlink light DO from the beacon head 8 of a certain lane R1 is different from that of the other 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 traveling in 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 from 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 uplink frames UL1, RL2 in the lane R4 are concerned. May worsen the reception rate of.
In particular, since the high-speed frame UL2 has a transmission speed closer to that of the downlink optical DO than the low-speed frame UL1, the high-speed frame UL2 is more susceptible to the reflected light of the downlink optical DO than the low-speed frame UL1, and the above problems are more remarkable. It is believed that

Therefore, in the optical beacon 4 of the present embodiment, “light emission control processing” (FIG. 6) that temporarily stops the emission of the downlink light DO by the beacon head 8 in accordance with the period of receiving the high-speed frame UL2 from the vehicle-mounted device 2 (FIG. 6). ). A downlink frame DL2 indicated by a virtual line in FIG. 6 is 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 transmitted by the vehicle-mounted device 2 that supports high-speed uplink transmission, and prevents 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, by stopping the transmission of the downlink signal (electrical signal) from the beacon controller 7 to the communication light emitting unit 13, and This can be performed 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 the voltage application to the light emitting element and to physically shield the downlink light DO so that the downlink light UO is external to the beacon head 8. Any means can be used as long as it can be done without putting it out.

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 the light emission amount of the light emitting element of the communication light emitting unit 13 having a dimming function is set to a predetermined value. The case of reducing to the following is also included in the concept of "light emission stop".

In the light emission control process of the downlink light DO, 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 DO are executed only for the lane R1 “first Two types of processing, “processing” and “second processing” for stopping and restarting light emission of the downlink DO of all lanes R1 to R4 are mainly considered, and either of them may be adopted. Further, the emission stop and the emission restart of the downlink DO may be executed for a part of the lane including the lane R1 (for example, the lane R1 and its adjacent lane), or a part or all of the lane R1 except the lane R1. The emission stop and the emission restart of the downlink DO may be executed for this lane.
This 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 varies 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. The end of reception of the high-speed frame UL2 by the optical beacon 4 depends on the number of high-speed frames UL2 transmitted by the vehicle-mounted device 2.
Therefore, in order to appropriately execute the light emission control process of the downlink 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 emission of the downlink light DO by the communication light emitting unit 13 upon the establishment of the stop condition described below, and sets the restart condition described below. With the establishment as a trigger, the communication light emitting unit 13 has a function as a “light emission control unit” that restarts the emission of the downlink light DO.

[Stop and restart timing of downlink light]
FIG. 7 is a time chart showing an example of the stop and restart timings of the emission of the downlink optical DO applicable to the optical beacon 4.
In FIG. 7, the bar graph on the upper side shows the transmission timing of the downlink frame DL2 by the optical beacon 4, and the bar graph on the lower side shows the reception timing of the upstream frames UL1, 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, the optical beacon 4 of the present embodiment is triggered by the establishment of at least one of the stop conditions 1 and 2 which is a necessary and sufficient condition for stopping the light emission, and the communication light emitting unit (optical transmitting unit) 13 The emission of the downlink light DO is stopped, and the emission of the downlink DO by the communication light emitting unit 13 is restarted when at least one of the restart conditions 1 to 3 which is the necessary and sufficient condition for restarting the light emission is satisfied.

In the optical beacon 4 of the present embodiment, not only the stop conditions 1 and 2 shown in FIG. 7 but also any other stop condition (stop condition 3 of FIG. 8 described later and stop conditions other than this) are satisfied. When doing so, the emission of the downlink DO may be stopped.
In the optical beacon 4 of the present embodiment, the emission of the downlink optical DO is restarted when any one of the restart conditions 1 to 3 shown in FIG. 7 is satisfied including further restart conditions. 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 the time when the CRC check for the frame is completed.
Further, in the following description, the operation subject is the optical beacon 4, but the actual information processing is performed by the beacon controller (communication control unit) 7 of the optical beacon 4.

Further, in the stop conditions 1 and 2, identification information indicating that the vehicle is an advanced vehicle-mounted device (the value of the vehicle-mounted device type=“6” (“E” indicating a full-duplex new vehicle-mounted device may be used)). The reception of the low-speed frame UL1 including the optical beacon 4 is included as a precondition (necessary condition).
The reason is that the in-vehicle device 2 transmits the high-speed frame UL2 in order to eliminate the poor reception of the high-speed frame UL2, and the low-speed frame UL1 including the identification information indicating the advanced in-vehicle device is transmitted. This is because the premise is satisfied when the optical beacon 4 receives. This point is the same in the case of the stop condition 3 shown in FIG. 8 (modified example).

(Stop condition 1 and light emission stop 1)
As illustrated in FIG. 7, the optical beacon 4 executes “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, the predetermined delay period from the reception of the low-speed frame UL1 in which the in-vehicle device type value is “6”. Since D1 (for example, 10 ms) has elapsed, the light emission stop 1 is executed at the time when the beginning of the downlink frame DL2 next to the time when the stop condition 1 is satisfied is transmitted.

In the stop condition 1, the reason for delaying the condition satisfaction time from the reception of the low speed frame UL1 by the delay period D1 is that when the emission of the downlink light DO is immediately stopped at the reception time of the low speed frame UL1, the lane notification information ( This is because there is a high possibility that communication with the vehicle-mounted device 2 will not be established because the number of transmissions will be reduced or the number of transmissions will decrease.
Therefore, it is preferable that the delay period D1 of the stop condition 1 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 measurement of the delay period D1 may be performed based on the time measured by a timer built in the beacon controller 7, or the downlink frame DL2 (downlink signal consisting of an electric signal) continuously generated by the beacon controller 7. May be performed based on the number of frames.
The transmission time for one frame of the downlink frame DL2 is about 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 of transmitting the beginning of the downlink frame DL2 next to the time when the stop condition 1 is satisfied is that if the emission of the downlink light DO is stopped at the delimiter of the downlink frame DL2, the sudden light amount is increased. This is because it is possible 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 is transmitting downlink frames DL1 and DL2 from a plurality of beacon heads 8 in synchronization with each other, and the light emission is stopped only in the lane in which the stop condition 1 is satisfied (for example, in the lane R1). Suppose you want to run in.

In this case, when the light emission is stopped in the lane R1 in the middle of the down frame DL2, the light amount of the adjacent lane R2 is decreased in the middle of the down frame DL2, and the vehicle-mounted device 2 of the vehicle 20 traveling in the lane R2 is in the down frame DL2. There is a high possibility that the reception will fail.
On the other hand, when light emission is stopped at the beginning of the downlink frame DL2 in the lane R1, the light amount of the adjacent lane R2 also decreases at the beginning of the downlink frame DL2, and the vehicle-mounted device 2 of the vehicle 20 traveling in the lane R2 has the downlink frame concerned. 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 beginning of the downlink frame DL2.

The reason why the first reception of the high-speed frame UL2 is adopted in the stop condition 2 is that, among the high-speed frames UL2 that are transmitted up to 16 frames, if the light emission is stopped upon the first reception, the high-speed frame UL2 related to the first reception is This is because it leads to elimination of reception failure of the remaining high-speed frame UL2 that is transmitted in the 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 reception of the fourth high-speed frame UL2 is started, 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 of transmitting the beginning of the downlink frame DL2 subsequent to the time when the stop condition 2 is satisfied is that the light emission stop 1 is (suppresses the obstruction of downlink communication in other lanes). Is the same as.

As described above, in order to increase the number of high-speed frames UL2 that eliminates poor reception, it is preferable to stop light emission when the high-speed frame UL2 is received for the first time. The light emission may be stopped upon reception of two times or the like.

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

On the contrary, if the timing at which the stop condition 1 is satisfied becomes later than 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 based on the stop condition 1 can be executed to reliably stop the light emission of the downlink light DO.

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

(Restart condition 1 and light emission restart 1)
As shown in FIG. 7, the optical beacon 4 executes “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 downstream frame after the restart condition 1 is satisfied. It is executed at the time of transmitting the beginning of DL2.

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

In the above calculation formula, “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 this 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)×3 ms=33 ms, and the time point when 33 ms is added from the first reception is restarted. This is the time when Condition 1 is satisfied.

Instead of adding the margin to one frame transmission time, 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)×2.3 ms+α≈25.3 ms+α=26.0 ms

As described above, if the delay period D2 having the end after the reception of the final frame (16 frames which is the maximum number of frames in the standard) of the upstream frame group including the plurality of high-speed frames UL2 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 defined 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 a set value.
The remaining 14 frames: 14×2.3=32.2 ms→33 ms is set.
The remaining 13 frames: 13×2.3=29.9 ms→30 ms is set as the set value.
(Omitted)
The remaining 2 frames: 2×2.3=4.6 ms→5 ms is set as a set value.
1 frame remaining: 1×2.3=2.3 ms→3 ms as a set value.

Similar to the delay period D1, the delay period D2 may be measured based on the time counted by the timer of the beacon controller 7, or the downlink frame DL2 continuously transmitted by the beacon controller 7 (from an electric signal). May be performed based on the number of frames of downlink signals).
The transmission time for one frame of the downlink frame DL2 is about 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 of transmitting the beginning of the downlink frame DL2 next to the time when the restart condition 1 is satisfied is that if the emission of the downlink light DO is restarted at the delimiter of the downlink frame DL2, the sudden light amount is increased. This is to prevent the downlink communication in other lanes from being hindered as the increase extends to other lanes.
For example, the optical beacon 4 synchronizes downlink frames DL1 and DL2 from a plurality of beacon heads 8 and performs downlink transmission, and regarding the restart of light emission, only the lane in which the restart condition 1 is satisfied (for example, the lane R1). Suppose you want to run in.

In this case, when light emission is restarted in the lane R1 in the middle of the downlink frame DL2, the light amount of the adjacent lane R2 increases in the middle of the downlink frame DL2, and the vehicle-mounted device 2 of the vehicle 20 traveling in the lane R2 has the downlink frame DL2. The possibility of failure in reception increases.
On the other hand, when light emission is restarted at the head of the downlink frame DL2 in the lane R1, the light amount of the adjacent lane R2 also increases at the head of the downlink frame DL2, and the vehicle-mounted device 2 of the vehicle 20 traveling in the lane R2 has the downlink frame concerned. The possibility of failing to receive DL2 is reduced.

(Restart condition 2 and light emission restart 2)
As shown in FIG. 7, the optical beacon 4 executes "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 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 when the beginning of the downlink frame DL2 next to the time when the restart condition 2 is satisfied is transmitted.

The reason for adopting that the low-speed frame UL1 is received further under the restart condition 2 is that another vehicle 20 enters the communication area A while the light emission is stopped and the vehicle-mounted device (both old and new) of the vehicle 20 is at 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 emission of the downlink optical DO in order to establish communication with these vehicles 20. Is.

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

The reason why the restart of light emission 2 is executed at the time of transmitting the beginning of the downlink frame DL2 next to the time when the restart condition 2 is satisfied is the case of restart of light emission 1 (suppressing obstruction of downlink communication in other lanes). Is the same as.

(Restart condition 3 and light emission restart 3)
As illustrated in FIG. 7, the optical beacon 4 executes “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 stop of light emission of the downlink light DO (light emission stop 1 in the illustrated example). It is executed at the time when the beginning of the downlink frame DL2 next to the time when the restart condition 3 is satisfied is transmitted.

The reason why the emission stop of the downlink light DO is adopted in the restart condition 3 is that when the actual emission stop time is used as the reference of the restart condition, the emission restart 3 is executed at the time when the stop condition 1 or 2 is satisfied. This is because the determination is automatically performed, and therefore, the processing for restarting light emission by the beacon controller 7 is simpler than in the case of restart condition 1, which is premised on the first reception of the high-speed frame UL2.

Similar to the delay period D1, the delay period D3 may be measured based on the time counted by the timer of the beacon controller 7, or the downlink frame DL2 continuously transmitted by the beacon controller 7 (from an electric signal). May be performed based on the number of frames of downlink signals).
The transmission time for one frame of the downlink frame DL2 is about 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 signals for 45 frames are transmitted.

The optical beacon 4 of the present embodiment may adopt both the restart conditions 1 and 3, or may adopt either 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 restart conditions 1 and 3 are adopted, the restart condition 3 is a restart of the restart condition 1 like a pack-up. It becomes a condition.
That is, even if the light emission resumption 1 based on the resumption condition 1 fails, the light emission resumption 3 based on the resumption condition 3 can be executed to reliably perform the light emission resumption of the downlink light DO.

On the other hand, depending on the setting of the delay periods D2 and D3, when the timing at which the restart condition 1 is satisfied is delayed compared with the restart condition 3, the restart condition 1 becomes a backup restart condition of the restart condition 3.
That is, even if the light emission resumption 3 based on the resumption condition 3 fails, the light emission resumption 1 based on the resumption condition 1 can be executed to reliably perform the light emission resumption of the downlink light DO.

Note that the light emission resumption 2 based on the resumption condition 2 has an exceptional processing element that another low-speed frame UL1 is received while the light emission is stopped.
Therefore, the optical beacon 4 of this embodiment cannot independently adopt the restart condition 2. That is, the restart condition 2 is a restart condition to 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 satisfaction of the condition without waiting for the beginning of the next downlink frame DL2 at the time when the condition is satisfied. However, there is a processing delay associated with information processing in the beacon controller 7 from the time when the restart conditions 1 to 3 are satisfied until the emission of the downlink DO is actually restarted.
Further, the light emission restarts 1 to 3 may be performed at the division of the downlink frame DL2 after the condition is satisfied, for example, at the division of the first downlink frame DL2 and the second downlink frame DL2 when the condition is satisfied. Good.

[Internal structure of optical beacon]
FIG. 8 is a block diagram showing an example of the internal configuration of the optical beacon 4 capable of executing the light emission control process for each of the lanes R1 to R4.
As shown in FIG. 8, the beacon controller 7 of the optical beacon 4 includes a control board 32 having a control unit 31 formed of an FPGA (Field-Programmable Gate Array) and a signal which is a transmission path of a downlink signal (electrical signal). And a terminal board substrate 34 for collecting the wires 33. 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.
The control unit 31 includes a plurality of (four in the illustrated example) output ports for transmitting downlink signals, and a signal line 33 is connected to each output port. The signal lines 33 are connected to the communication light emitting unit 13 of the beacon head 8, respectively.

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

The control unit 31 is capable of executing a synchronization process for synchronizing the downlink signals 1 to 4, and is programmed to perform a light emission control process 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 stopping the transmission of the downlink signal 1 corresponding to the lane R1 and restarting the transmission.

In this way, if the control unit 31 that includes the output ports that independently output the downlink signals 1 to 4 corresponding to the lanes R1 to R4 and that can execute the light emission control process for each of the lanes R1 to R4 is adopted. The optical beacon 4 capable of executing the light emission control process can be manufactured for each of the lanes R1 to R4.

As shown in FIG. 8, the signal line 33 branches inside the beacon head 8, and a branch line 35, which is a broken line branched from the signal line 33, is connected to the sensing light emitting unit 15.
Therefore, the optical beacon 4 of FIG. 8 is an optical beacon of a type that synchronizes the incident light IO for vehicle detection with the downlink light DO. Therefore, when the sensing light emitting unit 15 that uniquely 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 beacons 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 capable of executing the light emission control process for each of the lanes R1 to R4.
In the optical beacon 4 of FIG. 9, the control unit 31 has only one output port for downlink signals. The signal line 33 of the downlink signal connected to the output port is branched into a plurality of lines on the terminal board 34, and each branch line is connected to the communication light emitting unit 13 of each of the lanes R1 to R4.

Therefore, the downlink signal output by the controller 31 is branched inside the terminal board 34 and is transmitted to the communication light emitting units 13 of the lanes R1 to R4.
The beacon head 8 of each of the lanes R1 to R4 is provided with a switching element 36 that turns on and off signal transmission through the signal line 33.
The control unit 31 includes a plurality of (four in the illustrated example) output ports for transmitting the 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 elements 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 on the lane R1 by the control line 37.
Similarly, the output ports for sending the light emission control signals 2 to 4 for the lanes R2 to R4 are connected to the switching elements 36 of the beacon heads 8 on the lanes R2 to R4 by the control lines 37, respectively.

The control unit 31 sends a common downlink signal for each of the lanes R1 to R4 to each beacon head, and generates the light emission control signals 1 to 4 only for the lanes R1 to R4 in which the predetermined stop condition and the restart condition are generated. Is programmed to do so.
For example, the control unit 31 executes light emission stop and light emission restart by receiving the low-speed frame UL1 in the lane R1 by controlling the gate voltage of the switching element of 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 of the lanes R1 to R4. By providing the line 37, the optical beacon 4 capable of executing the light emission control process for each of the lanes R1 to R4 can be manufactured.

FIG. 10 is a block diagram showing another example of the internal configuration of the optical beacon 4 capable of executing the light emission control process for each of the lanes R1 to R4.
Like the optical beacon 4 of FIG. 9, the optical beacon 4 of FIG. 10 has only one output port for the downlink signal by the control unit 31, and the same signal line 33 is branched by the terminal board 34. Downlink signals are transmitted to the beacon heads 8 of the lanes R1 to R4, respectively.

The optical beacon 4 of FIG. 10 is different from the optical beacon 4 of FIG. 9 in that the switching element 36 that turns on/off the downlink signal transmission for each lane R1 to R4 is not the beacon head 8 but the terminal of the beacon controller 7. The point is that it is accommodated in the base substrate 34. Note that other configurations and operations are similar to those of the optical beacon 4 of FIG.

The embodiments disclosed this time are exemplifications in all respects, and should be considered not to be restrictive. The scope of rights of the present invention is shown not by the contents of the above-described embodiments but by the scope of claims, and is intended to include meanings equivalent to the scope of claims and all modifications within the scope.

1 Traffic control system 2 In-vehicle device 3 Central unit 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 transmission unit)
14 Light receiving unit for communication (light receiving unit)
15 Light emitting unit for sensing 16 Light receiving unit for sensing 17 Strut 18 Installation bar 20 Vehicle 21 Vehicle-mounted controller 22 Vehicle-mounted head 23 Optical transmitter 24 Optical receiver 31 Controller 32 Control board 33 Signal line 34 Terminal board 35 Branch line 36 switching element 37 control line R road R1 to R4 lane

Claims (1)

A plurality of optical beacon heads each having a light emitting unit for communication, and an optical beacon comprising an optical beacon controller for the plurality of optical beacon heads,
The plurality of optical beacon heads,
Each is provided with a switching element for controlling light emission of the communication light emitting unit,
The optical beacon controller includes a control board,
The control board has a plurality of first output ports and a second output port,
The plurality of first output ports stops the light emission of the communication light emitting unit corresponding to one or a plurality of lanes including at least the lane when a predetermined stop condition or a restart condition is satisfied in one lane, or A port for outputting a control signal to be restarted to the switching element ,
The second output port is a port for outputting a signal for emitting the pre-Symbol communication emitting unit,
The plurality of first output ports are connected to the switching elements of the plurality of optical beacon heads in a one-to-one relationship by individual signal lines,
The second output port is connected to the communication light emitting units of the plurality of optical beacon heads in a one-to-many relationship by a branched signal line having a trunk line and a plurality of branch lines, and is provided in the middle of each branch line of the branched signal line. An optical beacon in which the switching elements are respectively interposed .

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