JP2017092891A - Optical beacon - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent reflection light of downlink light from disturbing uplink communication at another lane.SOLUTION: An optical beacon according to one aspect of the present invention performs radio communication with an on-vehicle device of a travelling vehicle by using an optical signal. The optical beacon comprises: beacon heads installed on one or more lanes included in a road; a beacon controller for causing the beacon heads to transmit downlink light; and a light emission adjustment member capable of adjusting the amount of downlink emission light of part or all of the one or more beacon heads in at least two stages.SELECTED DRAWING: Figure 9

Description

  The present invention relates to an optical beacon that performs wireless communication using an optical signal with an in-vehicle device of a traveling vehicle.

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

Conversely, downlink information including traffic jam information, section travel time information, event regulation information, lane notification information, and the like is transmitted from the optical beacon to the in-vehicle device (see, for example, Patent Document 1).
For this reason, the optical beacon includes a light projecting / receiving device (hereinafter also referred to as a “beacon head”) that projects and receives an optical signal with the vehicle-mounted device for each lane. In each beacon head casing, there is mounted a transmission / reception unit for optical communication having a light emitting element for transmitting downlink light toward the road and a light receiving element for receiving uplink light transmitted by the vehicle-mounted device. .

JP 2005-268925 A

In an optical beacon in which a beacon head is installed for each of a plurality of lanes, reflected light of downlink light from a beacon head of a certain lane (hereinafter referred to as “first lane”) is reflected in another lane (hereinafter referred to as “second lane”). May reach the beacon head.
In this case, the beacon head in the second lane cannot receive the uplink light transmitted by the vehicle traveling in the second lane due to the influence of the reflected light, and uplink communication in the second lane may be hindered.

In particular, in the case of a “high-speed optical beacon” that has two types of uplink optical transmission rates, the high-speed uplink frame transmission rate (256 kbit / s) is the low-speed uplink frame transmission rate (64 kbit / s). Compared to the transmission speed of the downlink light (1024 kbit / s).
For this reason, the high-speed uplink frame is more easily affected by the reflected light of the downlink light from other lanes than the low-speed uplink frame, and the above-described problem becomes even more remarkable.

  In view of the conventional problems, an object of the present invention is to suppress the reflected light of downlink light from hindering uplink communication in other lanes.

  (1) An optical beacon according to an aspect of the present invention is an optical beacon that performs wireless communication with an in-vehicle device of a running vehicle using an optical signal, and is installed on one or more lanes included in a road. A head, a beacon controller that causes the beacon head to transmit downlink light, and a light emission adjusting member that can adjust the amount of downlink light emission of some or all of the one or more beacon heads in at least two stages, It has.

  ADVANTAGE OF THE INVENTION According to this invention, it can suppress that the reflected light of downlink light inhibits uplink communication in another lane.

It is a block diagram which shows schematic structure of a road-vehicle communication system. It is the top view of the road which looked at the installation part of an optical beacon from the top. It is a side view of the road which shows the communication area | region and incident area of an optical beacon. It is a frame block diagram of an uplink frame (uplink information). It is a frame block diagram of a downlink frame (downlink information). It is explanatory drawing in the case of clearing the reference value of the amount of light reaching the downlink with one head. It is explanatory drawing in the case of clearing the reference value of the amount of light reaching the downlink with two heads. It is a top view of the road which shows an example of the adjustment method of the downlink light emission amount of a beacon head. It is the schematic of the light emitting circuit which has a 1st voltage adjustment member. It is the schematic of the light emitting circuit which has a 2nd voltage adjustment member. It is the schematic of the light emitting circuit which has a 3rd voltage adjustment member. It is explanatory drawing which shows the example of the addition of the resistor using a relay board | substrate.

<Outline of Embodiment of the Present Invention>
Hereinafter, an outline of embodiments of the present invention will be listed and described.
(1) An optical beacon that performs wireless communication with an in-vehicle device of a running vehicle by an optical signal, a beacon head installed on one or a plurality of lanes included in a road, and downlink light to the beacon head A beacon control device to be transmitted, and a light emission adjusting member capable of adjusting a downlink light emission amount of a part or all of one or a plurality of the beacon heads in at least two stages.

According to the optical beacon of the present embodiment, the light emission adjusting member can adjust the amount of downlink light emission of a part or all of one or a plurality of beacon heads in at least two stages. It is possible to employ an adjustment method for reducing the light emission amount of each beacon head to such an extent that the reference value on the side is cleared by a plurality of beacon heads.
For this reason, the reflected light of the downlink light in the first lane does not easily reach the beacon head in the second lane, and the uplink light (particularly the high-speed uplink frame) transmitted by the vehicle traveling in the second lane is The possibility that the beacon head in the lane cannot be received can be reduced.

  Also, since the reflected light of the downlink light in the first lane does not easily reach the beacon head in the first lane, the uplink light (particularly the high-speed uplink frame) transmitted by the vehicle traveling in the first lane is The possibility that the one-lane beacon head cannot be received can also be reduced.

(2) In the optical beacon of this embodiment, it is preferable that the light emission adjusting member has an operation unit on the beacon controller side that receives an operation for adjusting a downlink light emission amount.
If such a light emission adjusting member is adopted, the amount of downlink light emission can be adjusted by the operation unit on the beacon controller side, so that each beacon head can be used at the site after the beacon head is installed as well as before the product is shipped. It becomes easy to perform the adjustment work of the downlink light emission amount for.

(3) In the optical beacon of this embodiment, when the optical beacon includes a plurality of the beacon heads, it is preferable that the light emission adjusting member is capable of adjusting a downlink light emission amount for each of the plurality of beacon heads. .
If such a light emission adjusting member is employed, the downlink light emission amount can be adjusted for each of a plurality of beacon heads, and thus the downlink light emission amount can be adjusted for each lane.

<Details of Embodiment of the Present Invention>
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
In the present embodiment, an uplink frame transmitted from the in-vehicle device 2 toward the optical beacon 4 may be referred to as “uplink information” or “uplink signal”.
In addition, a downlink frame transmitted from the optical beacon 4 toward the in-vehicle device 2 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 when the installation portion of the optical beacon 4 of this embodiment is viewed from above.
As shown in FIG. 1, the road-to-vehicle communication system of this embodiment includes an infrastructure-side traffic control system 1 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 at various locations on the road R. The optical beacon 4 can perform wireless communication with the in-vehicle device 2 by optical communication using near infrared as a communication medium.
The optical beacon 4 includes a beacon controller (communication controller) 7 that performs communication control and the like, and a plurality (four in the example of FIG. 1) of beacon heads (transmit / receive) connected to the sensor interface of the beacon controller 7. 8).

The beacon controller 7 is connected to a communication unit 6 on the infrastructure side, and the communication unit 6 is connected to the central apparatus 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 performs a relay process of traffic information on the infrastructure side, and the like.

The optical beacon 4 of this embodiment employs a full-duplex communication method. That is, the beacon controller 7 simultaneously performs transmission control in the downlink direction for the light emitting unit 13 for optical communication and reception control in the uplink direction for the light receiving unit 14 for optical communication.
On the other hand, the in-vehicle device 2 of the present embodiment employs a half-duplex communication method. That is, the below-described vehicle-mounted controller 21 (see FIG. 3) does not simultaneously perform uplink direction transmission control for the optical transmission unit 23 and downlink direction reception control for 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 detection function are obtained by incorporating the units 11 and 12 for optical communication and vehicle detection in the housing 9 of one beacon head 8, respectively. It has a structure with both.

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

A light emitting unit 13 for optical communication (hereinafter also referred to as “communication light emitting unit 13”) includes a transmission circuit that converts a downstream frame transmitted from the beacon controller 7 into a serial transmission signal having a predetermined transmission rate; A light emitting element made of a light emitting diode (LED) that converts the output transmission signal into an optical signal in a downlink direction.
The light emitting element of the communication light emitting unit 13 sends 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 a light receiving element such as a photodiode (PD) and an electric signal output from the light receiving element. A receiving circuit for generating 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 before the beacon head 8, and converts it into an electrical signal. The reception circuit of the communication light receiving unit 14 sends a digital signal generated from the converted electrical signal to the beacon controller 7.

The sensor unit 12 is a light detection sensor for detecting the presence of the vehicle 20 passing almost directly below the beacon head 8 without contact.
As shown in FIG. 1, the sensor unit 12 includes a vehicle sensing light emitting unit 15 that transmits incident light IO (see FIG. 3), and a vehicle that receives reflected light RO (see FIG. 3) and converts it into an electrical signal. And 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 cycle, downward.
The vehicle sensing light receiving unit 16 (hereinafter also referred to as “sensing sensing light receiving unit 16”) 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 electrical signal. Convert and send to the beacon controller 7.

The beacon controller 7 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 communication with the central device 3 and communication between the in-vehicle device 2 and the vehicle according to a predetermined communication interface standard. And a function as a sensing control unit of the vehicle 20.
The beacon controller 7 stores a computer program for communication control and sensing control in a storage device (not shown), and the CPU reads out and executes the program so that the CPU performs the communication control. Functions as a control unit and a sensing control unit.

For example, the beacon controller 7 may include 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, or predetermined provision information. Is transmitted to the communication light-emitting unit 13 at a predetermined cycle.
The beacon controller 7 continues to transmit the downlink signal, and receives the uplink signal (uplink frame) including the ID value that the vehicle-mounted device 2 will transmit when receiving the downlink signal. Judgment is made.

  When the beacon controller 7 detects the reception of the uplink signal by the communication light receiving unit 14, the lane notification information storing the ID value and the lane number value extracted from the uplink signal, the provision information for the vehicle 20, and 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 provision information included in the downlink signal and waits for reception of the uplink signal from the in-vehicle device 2 of the vehicle 20 that comes next. .
Note that the beacon controller 7 transfers information included in the uplink signal, such as probe data including a travel locus such as the position and time of the vehicle 20, to the central device 3.

The beacon controller 7 always 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 received light intensity of the reflected light RO received by the sensing light receiving unit 16 is equal to or greater than a threshold value. The presence of the vehicle 20 is sensed depending on whether or not.
That is, the beacon controller 7 generates a sensing signal of the vehicle 20 and transmits the sensing signal to the central device 3 when the light receiving intensity of the reflected light RO that is equal to or greater than the threshold value is detected in the sensing light receiving unit 16. This threshold value is not limited to a fixed value, and may vary depending on, for example, a follow-up process according to the received light intensity of the reflected light RO.

[Optical beacon installation status]
As shown in FIG. 2, the optical beacon 4 of the present embodiment is installed on a road R having a plurality (four in the illustrated example) of 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 these beacon heads 8. Prepare.

The beacon controller 7 is installed on a support column 17 erected on the left side of the road R. Each beacon head 8 is attached to an erection bar (beam member) 18 that is laid horizontally on the road R side from the column 17 and is disposed immediately above the 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 from directly below the own device. Thereby, 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 the incident light IO almost directly below the own device. As a result, the incident area B, which is the sensing area of the vehicle 20 passing through the predetermined lanes R1 to R4 on the road R, is set almost directly below the beacon head 8.

[Communication area and incident area of optical beacons]
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 hatched portion) that is a receivable range of the downlink light DO by the in-vehicle device 2 and an uplink light UO by the beacon head 8. And an uplink area UA (broken line hatched portion) which is a light receiving range.

According to the UTMS (Universal Traffic Management Systems) Association “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 / downstream end positions are as follows.
Downstream area DA downstream end position a0: +1.3 m
Downstream end position b0 of the uplink area UA: a0 + 2.1 m (= 3.4 m)
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 3” (hereinafter referred to as “New Interface Standard”) of the UTMS Association, which was formulated on January 5, 2015, the standard value of the upstream end position of each area DA, UA ( For general roads):
Downstream area DA downstream end position a0: +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 values of the positions a0 to c0 are values when the upstream direction is a positive number from the position immediately below the light emitter / receiver 8 (origin O) on the reference plane having a height H of 1.0 m from the road surface. .

In the old interface standard, the transmission rate of the uplink optical UO transmitted by the vehicle-mounted device 2 is only 64 kbit / s, and the transmission rate 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 (low speed is 64 kbit / s and high speed is 256 kbit / s. s).

Therefore, the optical beacon 4 according to the new interface standard is a multi-rate compatible optical beacon (hereinafter referred to as “new optical beacon”) that can perform conventional low-speed uplink reception and new high-speed uplink reception.
The in-vehicle device 2 conforming to the new interface standard is a multi-rate in-vehicle device (hereinafter referred to as “new in-vehicle device”) that can perform conventional low-speed uplink transmission and new high-speed uplink transmission.

The optical beacon 4 and the in-vehicle device 2 according to the present embodiment may conform to any of the old interface standard and the new interface standard described above.
However, in the following description, it is assumed that the optical beacon 4 of the present embodiment is a new optical beacon, and the in-vehicle device 2 of the present embodiment is a new in-vehicle device.

The incident area B of the sensor unit 12 is an irradiation range of the incident light IO on which the sensing light emitting unit 15 enters the road R.
The center of the incident area B in the road width direction is 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 emission direction V1 of the incident light IO is normally directed upstream (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 in-vehicle device 2 of the present embodiment includes an in-vehicle controller (communication control unit) 21 and an in-vehicle head (optical transmission / reception unit) 22. An optical transmitter 23 and an optical receiver 24 are accommodated in the in-vehicle head 22.
The optical transmitter 23 has a light emitting element that emits an uplink light UO (uplink direction optical signal) made of near infrared rays, and the optical receiver 24 has a downlink light UO (downlink direction made of near infrared rays). A light receiving element for receiving an optical signal).

The optical transmission unit 23 is a light emitting circuit that converts an upstream frame output from the in-vehicle controller 21 into a serial transmission signal having a predetermined transmission rate, and converts the output transmission signal into an optical signal in the uplink direction. And a light emitting element made of a diode or the like.
The optical receiver 24 includes a light receiving element such as a photodiode 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.
The in-vehicle controller 21 stores a computer program for communication control in a storage device (not shown), and the CPU reads and executes the program, so that the CPU functions as the communication control unit. To do.

The in-vehicle controller 21 generates traveling data of the host vehicle (for example, probe information that is traveling locus data in which passing positions and passing times are arranged in time series) as uplink data, and uploads it to the optical transmitter 23. It also has a function to transmit a link.
In this case, if the uplink speed is increased as in the new interface standard, more probe information (longer road sections that record the travel trajectory, higher recording density of passing positions and passing times in the same road section) Information can be transmitted.

The in-vehicle controller 21 of this embodiment may have a circuit configuration in which a simple control unit including an ASIC (Application Specific Integrated Circuit) is provided separately from the main body control unit including the CPU.
For example, when the optical receiving unit 24 receives any downlink frame, the simple control unit transmits only one uplink frame (conventional uplink frame having a transmission rate of 64 kbit / s) including the vehicle ID of the host vehicle. The unit 23 has a function of causing uplink transmission.

As shown in FIG. 3, a navigation device 25 is mounted on the vehicle 20. The navigation device 25 includes a route search unit that searches for an optimal route when traveling to a destination, an operation unit for a passenger to input to the route search unit, and an optimal route that is a calculation result using an image or voice. A display and a speaker for guiding the user.
In general, the route search unit calculates a minimum cost route that minimizes the link cost by a specific route search logic. As the route search logic, for example, the Dijkstra method or the potential method is used.

The navigation device 25 has a time synchronization function for acquiring the current time from the GPS signal, a position detection function for measuring the current position (latitude, longitude, and altitude) of the host vehicle from the GPS signal, and an azimuth and angular velocity of the host vehicle by the direction sensor. It has an orientation detection function that measures
The navigation device 25 also includes a storage device (not shown) in which road map data is stored. The road map data is used to map match the position information of the host vehicle during the search process by the route search unit.

The in-vehicle controller 21 outputs the information to the navigation device 25 when the information regarding the traffic restriction and the information useful for navigation (for example, “simple graphic information” of the road) are included in the downlink signal. .
For example, when the navigation device 25 acquires simple graphic information from the in-vehicle controller 21, the navigation device 25 displays the graphic information on the display. Thereby, the passenger of the vehicle 20 can visually recognize a simple image or the like indicating road traffic information in the vicinity of the intersection on the downstream side of the beacon head 8 in advance.

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

In the upstream frame, 1 byte is assigned to the synchronization part, 10 bytes are assigned to the header part, 59 bytes at maximum are assigned to the real data part, and 4 bytes (1 byte idle part + 2 bytes CRC + 1 byte) are assigned to the CRC part. Of the last synchronization part).
The header portion of the upstream frame includes storage areas such as “number of subsystem key information”, “vehicle ID”, “vehicle equipment type”, “information type”, and “last frame flag”.

In the “number of subsystem key information” (hereinafter sometimes abbreviated as “number of information”), the number of “subsystem key information” stored in order from the top of the actual data portion is stored.
That is, when the number of information is zero, “subsystem key information” is not included in the actual data portion, and when the number of information is “1”, one “subsystem key information” is included in the actual data portion. When the number of information is “n”, n “subsystem key information” is included in the actual data part.

The above-mentioned “subsystem key information” indicates that the optical beacon 4 is a downlink of 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.
The in-vehicle device 2 determines the contents of “subsystem key information” and “subsystem key information” according to which system of the UTMS standard the host vehicle is compatible with.

For example, the in-vehicle device 2 sets the value of the “number of subsystem key information” in the header part to “1” when the host vehicle corresponds to one system of the UTMS standard, and follows the standard of the one system. The “subsystem key information (1)” of the contents is stored in the actual data part.
In addition, when the host vehicle is compatible with 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 the standard of the two systems respectively. The “subsystem key information (1)” and “subsystem key information (2)” having the contents are stored in the actual data part.

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

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

“Vehicle ID” is an area for storing a vehicle ID identification value (which may be a numerical value or a symbol) 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 in-vehicle 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.
“In-vehicle device type” is an area in which the type of the in-vehicle device 2 is stored. “Information type” is an area for storing the type of uplink information. In the new interface standard, the values of these areas indicate whether the uplink transmission subject is new or old, and whether the uplink information is high speed or low speed.

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

Therefore, the optical beacon 4 can be determined as a low-speed frame from the new in-vehicle device when the in-vehicle device type value of the received upstream frame is “6” and the information type value is “1”. 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 an 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 uplink frame having a value of “vehicle-mounted device type” 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 “last frame flag” is a storage area for indicating which of the uplink frames is the final frame when the in-vehicle device (which may be new or old) transmits an uplink frame group including a plurality of uplink frames. It is.
That is, the in-vehicle device 2 stores a predetermined flag value (for example, “1”) only in the “final frame flag” of the last frame among the plurality of uplink frames constituting the uplink frame group, and other uplink frames Does not store the flag value.

[Frame structure of downstream frame]
FIG. 5 is a frame configuration diagram of a downlink frame (downlink information).
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 top, as in the case of the frame structure of the upstream frame (FIG. 4). .

In the downstream frame, 1 byte is allocated to the synchronization section, 5 bytes are allocated to the header section, 123 bytes are allocated to the real data section, and 4 bytes are allocated to the CRC section (1 byte idle section + 2 bytes CRC + 1 byte final). Synchronous part) is assigned.
The type of information provided to the in-vehicle device 2 included in the actual data portion of the downstream frame may change before and after the optical beacon 4 receives the upstream frame from the in-vehicle device 2.

That is, the optical beacon 4 can switch the content of the information provided to the in-vehicle device 2 before and after receiving the uplink frame.
Specifically, the optical beacon 4 receives a downlink frame (hereinafter referred to as “first downlink frame”) 2015 that is downlink-transmitted before receiving an uplink frame from the in-vehicle device 2 (before uplink reception). Provision of uplink information in "Advanced Optical Beacon Near-Infrared AMIS Communication Application Standard Version 2" (hereinafter referred to as "Communication Application Standard (Version 2)") formulated by UTMS Association on January 5, It is possible to include information (such as “lane notification information”) that is defined not to be a condition in the actual data part.

  The optical beacon 4 has a communication application standard (version 2) in a downlink frame (hereinafter referred to as “second downlink frame”) transmitted in downlink after receiving the uplink frame from the in-vehicle device 2 (after receiving the uplink). ) In the communication application standard (version 2) as well as information stipulated not to be provided with the provision of uplink information (“lane communication information”, etc.) ("Route signal information" etc.) can also be included in the actual data part.

The optical beacon 4 provides the provision information to the in-vehicle device 2 by one downlink frame when the provision information of the single information type to the in-vehicle device 2 fits in the capacity of the actual data part (123 bytes).
The optical beacon 4 is divided into a plurality of downlink frames (downstream frame groups) when the provision information of the single information type to the in-vehicle device 2 does not fit in the capacity of the actual data part (123 bytes), The provided information is provided to the in-vehicle device 2. Therefore, different information types are not mixed in one downstream frame.

As shown in FIG. 5, examples of the provision information included in the first downlink frame include, for example, “lane notification information” (where the vehicle ID identification value is not stored), “current position information”, and the like. There is. The “lane notification information” is information for notifying the lane number where the vehicle 20 travels, and the “current position information” is the position information (latitude and longitude) of the installation location of the beacon head 8.
The storage area of “lane notification information” includes “vehicle ID”, “lane number”, and “beacon identification flag”. The optical beacon 4 does not store the identification value in the “vehicle ID” in the lane notification information included in the downlink frame before uplink reception.

When the optical beacon 4 receives the upstream frame including the identification value (ID value) of the vehicle ID from the in-vehicle device 2, the optical beacon 4 stores the acquired ID value in the “vehicle ID” of the lane notification information (hereinafter, this downstream frame). Is also referred to as a “turnback frame”), and the generated return frames are downlink transmitted at predetermined intervals.
Therefore, the in-vehicle device 2 can determine communication establishment with the optical beacon 4 based on whether or not the ID value of the host vehicle is included in the received lane notification information of the return frame.

In addition, the optical beacon 4 writes the lane number value corresponding to the beacon head 8 that acquired the uplink information in the “lane number” of the lane notification information included in the return frame.
Therefore, the in-vehicle device 2 can determine which lane the host vehicle is traveling 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 supports high-speed uplink reception.
When the optical beacon 4 is a new optical beacon, the optical beacon 4 stores a predetermined flag value (for example, “01”) in the “beacon identification flag” of the downstream frame. Other values (for example, “00”) are stored in the “beacon identification flag” of the downstream frame.

  Accordingly, the in-vehicle device 2 determines whether the optical beacon 4 of the communication partner is a new optical beacon or an old optical beacon based on the value of the “beacon identification flag” included in the “lane notification information” of the downlink frame. Can do.

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

Therefore, for example, when one significant data (provided information) is constituted by three downstream 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, the downlink area DA is expanded to the vicinity immediately below the beacon head 8, so that the number of times of repeatedly transmitting a 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 “route signal information” and “travel speed link information”.
“Route signal information” refers to route signal information at an intersection in the forward direction from the point where the optical beacon 4 is installed. “Travel speed link information” is travel speed information of provided links preset for each optical beacon 4.

[Problems caused by reflected light of downlink light]
FIG. 6 is an explanatory diagram in the case where the reference value of the amount of light reaching the downlink is cleared by one head.
As shown in FIG. 6, in each of the old and new interface standards, the road width direction range of the downlink area DA is the center of the lanes R1 to R4 on the reference plane having a predetermined height (H = 1.0 m) from the road surface. At a measurement position P of ± 1.75 m in the left-right direction as the origin, it is defined as a range in which a downlink reaching light amount equal to or greater than a predetermined reference value (= 4.5 μW / cm ² ) is obtained.

The measurement position P needs to be within the vehicle traveling direction range of the downlink area DA (the range from the downstream end position a0 to the upstream end position c0 in FIG. 3), and usually the upstream end position of the downlink area DA. Set to c0.
Accordingly, the vehicle traveling direction position of the measurement position P is set to a position of 5.0 m from directly under the head in the case of the old interface standard, and 6 in the upstream direction from under the head in the case of the new interface standard. .04m position.

In each interface standard, the amount of light reaching the downlink according to the number of installed beacon heads 8 is not specified. Therefore, the manufacturer of the optical beacon 4 generally adjusts the light emission amount so that the reference value is achieved by the single beacon head 8.
For this reason, in the actual road R where the beacon heads 8 are respectively installed in the plurality of lanes R1 to R4, the downlink light DO from the plurality of beacon heads 8 arrives in duplicate, and the downlink arrival light amount is consequently increased. There may be areas that are too high.

  This is because in the case of the road R where the width of the lanes R1 to R4 is less than 3.5 m, or in order to ensure downlink communication, the light amount of the downlink beacon 4 is larger than the reference value. This is conspicuous when the manufacturer adjusts the light emission amount of the downlink light DO of the beacon head 8.

On the other hand, for example, as shown in FIG. 6, if the downlink irradiation range of the beacon head 8 in each lane R1, R2 protrudes into the other lanes R2, R1, the downlink light DO from the beacon head 8 in the lane R1 The reflected light may reach the beacon head 8 in the lane R2.
In this case, the beacon head 8 in the lane R2 cannot receive the uplink light UO transmitted by the vehicle 20 passing through the lane R2 due to the influence of reflected light, and uplink communication in the lane R2 may be hindered.

In particular, among the low-speed uplink frame UL1 and the high-speed uplink frame UL2 transmitted by the new vehicle-mounted device, the transmission rate of the high-speed uplink frame UL2 (256 kbit / s) is the transmission rate of the low-speed uplink frame UL1 (64 kbit / s). Compared to the transmission rate of the downlink optical DO (1024 kbit / s).
Therefore, it can be said that the high-speed uplink frame UL2 is more susceptible to the reflected light of the downlink light DO than the low-speed uplink frame UL1, and is more likely to be received.

[Optical beacons to solve problems]
Therefore, in this embodiment, the reflected light of the downlink light DO is reduced to other lanes by reducing the light emission amount of each beacon head 8 to the extent that the reference value of the downlink arrival light amount is cleared by the plurality of beacon heads 8. Inhibiting uplink communication is suppressed, thereby solving the above-mentioned problems.

FIG. 7 is an explanatory diagram when the reference value of the amount of light reaching the downlink is cleared by two heads.
As shown in FIG. 7, in the optical beacon 4 of the present embodiment, the amount of light reaching the downlink at the measurement position P described above under the condition that the downlink light DO is simultaneously emitted from the beacon heads 8 of the two adjacent lanes R1, R2. Is adjusted to be equal to or greater than a predetermined reference value (= 4.5 μW / cm ² ), the light emission amount of the beacon head 8 in each lane R1, R2 is adjusted.

FIG. 8 is a plan view of a road showing an example of a method for adjusting the downlink light emission amount of the beacon head 8.
The XY coordinates in FIG. 8 are orthogonal coordinates representing a planar position on the reference plane having a predetermined height H (= 1.0 m) from the road surface, and the origin is a position directly below the beacon head 8 in the lane R1. The X coordinate represents the position in the vehicle traveling direction, and the upstream side is positive. The Y coordinate represents the position in the road width direction, and the left side is positive with respect to the positive direction of the X coordinate.

Points P1 to P3 in FIG. 8 are measurement positions of the amount of light reaching the downlink, and the XY coordinate values of the measurement positions P1 to P3 are as follows.
P1 = (+ 6.04, -1.75)
P2 = (+ 6.04, +1.75)
P3 = (+ 6.04, +5.25)

Under the above measurement conditions, the downlink light DO is simultaneously irradiated from the two beacon heads 8 installed in the lanes R1 and R2, and the downlink arrival light quantity at least at the measurement positions P1 and P3 is measured.
Then, the light emission amount when the measurement values at the measurement positions P1 and P3 reach the reference value (= 4.5 μW / cm ² ) is set as an appropriate light emission amount of each of the beacon heads 8 and 8. In this case, it is preferable to confirm that the measurement value at the measurement position P2 is greater than or equal to the reference value.

Here, assuming that the beacon head 8 in the lane R1 is “head 8A” and the beacon head in the lane R2 is “head 8B”, in the case of simultaneous light emission, the two heads 8A and 8B are placed at the measurement positions P1 to P3. Downlink light DO arrives in a superimposed manner.
Therefore, the light emission amount of each of the heads 8A and 8B when the reference values at the measurement positions P1 to P3 are satisfied by simultaneous light emission is smaller than the light emission amount when the reference values at the measurement positions P1 to P3 are satisfied by single light emission. .

Therefore, if the above-described adjustment method is adopted, the light emission of the downlink light DO by one beacon head 8 as compared with the case where the beacon head 8 alone satisfies the reference value on the lower limit side of the amount of light reaching the downlink (FIG. 6). The amount (= downlink emission amount) can be reduced.
For this reason, the reflected light of the downlink light DO in the lane R1 is difficult to reach the beacon head 8 in the other lane R2, and the uplink light UO (particularly, the high-speed uplink frame UL2) transmitted by the vehicle 20 passing through the lane R2. , The possibility that the beacon head 8 in the lane R2 cannot be received can be reduced.

  Further, it is difficult for the reflected light of the downlink light DO in the lane R1 to reach the beacon head 8 in the lane R1. Therefore, it is possible to reduce the possibility that the beacon head 8 in the lane R1 cannot receive the uplink light (particularly, the high-speed uplink frame UL2) transmitted by the vehicle 20 traveling in the lane R1.

In FIG. 8, the adjustment method of the downlink light emission amount when the beacon head 8 is installed in the two lanes R1 and R2 is illustrated, but when the beacon head 8 is installed in the three lanes R1 to R3, the measurement position P4 = The same adjustment method may be performed by adding (+6.04, +8.75).
That is, the downlink light DO is simultaneously irradiated from the three beacon heads 8 installed in the respective lanes R1 to R3, and the downlink arrival light amounts at least at the measurement positions P1 and P4 are measured.

And let the emitted light quantity when the measured value in measurement position P1, P4 reaches | attains a reference value (= 4.5 microwatt / cm < ² >) be an appropriate emitted light quantity of each beacon head 8,8,8. In this case, it is preferable to confirm that the measurement values at the measurement positions P2 and P3 are equal to or higher than the reference value.
In the case of the three lanes R1 to R3, only the light emission amount of the beacon head 8 in the middle lane R2 is reduced (the light may be turned off) without adjusting the light emission amounts of the lanes R1, R3 at both ends. Alternatively, the beacon heads 8 in the lanes R1, R3 at both ends may be turned off, and the light emission amount of the beacon head 8 in the middle lane R2 may be adjusted.

In order to perform the above-described adjustment method at a factory or an installation site, the optical beacon 4 has a downlink light emission amount of at least 2 for a plurality of beacon heads 8 (may be all or a part) to be installed on the road R. What is necessary is just to provide the light emission adjustment member which can be adjusted in a step.
Such a light emission adjusting member can be realized by, for example, a voltage adjusting member that adjusts a voltage applied to the light emitting element of the light emitting unit 13 mounted on the beacon head 8. Hereinafter, some specific examples of the voltage adjusting member will be described.

[Specific example 1 of voltage adjusting member]
FIG. 9 is a schematic diagram of the light emitting circuit 27 having the first voltage adjusting member 31.
As shown in FIG. 9, the light emission circuit 27 of the optical beacon 4 includes a DC power supply 28 and a switching element 30 provided in the beacon controller 7, a light emission unit 13 provided in the beacon head 8, and the beacon controller 7. A power cable 29 connecting the beacon head 8 and a first voltage adjusting member 31 that can be operated from the beacon controller 7 side are provided.

The first voltage adjusting member 31 includes a variable resistor 32 connected in series to the DC power supply 28 in the beacon controller 7 and an operation unit 33 for changing the resistance value of the variable resistor 32.
The operation unit 33 is a member that receives an operation of changing a resistance value by a user, and includes a rotary or slide operation knob. Therefore, when the user operates the operation unit 33 to change the resistance value of the variable resistor 32, the output voltage of the DC power supply 28 changes, and the amount of downlink light emitted by the light emitting user 13 of each beacon head 8 can be adjusted. it can.

According to the first voltage adjustment member 31, the output voltage of the DC power supply 28 is changed by the operation unit 33 on the side of the beacon controller 7. Therefore, the beacon controller 7 adjusts the downlink light emission amount of all the beacon heads 8. Can be done from the side.
For this reason, not only before the product is shipped, but also at the site after the beacon heads 8 are installed, it is easy to perform the adjustment operation of the downlink light emission amount for each beacon head 8.

[Specific example 2 of voltage adjusting member]
FIG. 10 is a schematic diagram of the light emitting circuit 27 having the second voltage adjusting member 35.
As shown in FIG. 10, the light emission circuit 27 of the optical beacon 4 includes a DC power supply 28 and a switching element 30 provided in the beacon controller 7, a light emitting unit 13 provided in the beacon head 8, and the beacon controller 7. A power cable 29 that connects the beacon head 8 and a second voltage adjustment member 35 that can be operated from the beacon controller 7 side are provided.

The second voltage adjusting member 35 includes a variable resistor 36 connected in series to the light emitting unit 13 in each beacon head 8 and an operation unit 37 provided in the beacon controller 7.
The operation unit 37 is a member that receives an operation of changing the resistance value by the user, and includes a rotary or slide type operation knob that can output an operation signal to the variable resistor 36 of each beacon head 8.

  Accordingly, when the user operates the operation unit 37 to change the resistance value of the variable resistor 36 of any one of the beacon heads 8, the voltage applied to the light emitting unit 13 changes, and the light emitting user 13 of the beacon head 8 decreases. The amount of link light emission can be adjusted.

According to the second voltage adjustment member 35, the voltage applied to the beacon head 8 is individually changed by the operation unit 37 on the side of the beacon controller 7. Therefore, the same effect as the first voltage adjustment member 35 is obtained.
Moreover, according to the 2nd voltage adjustment member 35, since the voltage applied to the beacon head 8 is changed separately, the downlink light emission amount can be adjusted for every some beacon head 8. FIG. For this reason, it becomes possible to adjust the downlink light emission amount for each of the lanes R1 to R4.

[Specific example 3 of voltage adjusting member]
FIG. 11 is a schematic view of the light emitting circuit 27 having the third voltage adjusting member 39.
As shown in FIG. 11, the light emission circuit 27 of the optical beacon 4 includes a DC power supply 28 and a switching element 30 provided in the beacon controller 7, a light emission unit 13 provided in the beacon head 8, and the beacon controller 7. A power cable 29 connecting the beacon head 8 and a third voltage adjusting member 39 detachably provided on a power line (including the power cable 29) constituting the light emitting circuit 27.

The third voltage adjusting member 39 is, for example, a resistor 40 retrofitted to a power line inside the beacon controller 7, a resistor 41 retrofitted to a power line inside the beacon controller 7, and a power cable 29 afterward. It comprises at least one of the resistors 42 to be operated.
The resistors 40 and 41 provided in the beacon controller 7 or the beacon head 8 may be resistors directly attached to the circuit board of the beacon controller 7 or the beacon head 8, or relays connected to the circuit board by cables. It may be a resistor mounted on a substrate.

  The resistors 40 to 42 may be members having a function of increasing a voltage drop in an arbitrary section of the light emitting circuit 27, and may be a relatively long load such as a cable, a diode, and an LED.

The relay board is very suitable for attaching a resistor to the cable of the installed optical beacon 4. Hereinafter, this point will be described with reference to FIG.
FIG. 12 is an explanatory diagram showing an example of adding a resistor 47 using the relay board 45. Specifically, FIG. 12A shows a state before the relay board 45 is attached, and FIG. 12B shows a state after the relay board 45 is attached.

As shown in FIG. 12A, the board 7B of the beacon controller 7 and the beacon head 8 can be connected by a concentrating cable 44 made of a flat cable having connectors Cm at both ends.
A connector Cf that is detachably fitted to the connector Cm of the concentrating cable 45 is attached to the board 7B and the beacon head 8 of the beacon controller 7.

  As shown in FIG. 12B, the relay board 45 includes a connector Cf that can be fitted with the connector Cm of the concentrating cable 44, a connector Cb into which the loose electric wires constituting the concentrating cable 44 can be respectively inserted, and these connectors. A plurality of electric wires 46 wired so as to connect corresponding ports of Cm and Cb, and a resistor 47 provided on a power line of the electric wires 46 are provided.

When the resistor 47 is added to the existing optical beacon 4 using the relay board 45 shown in FIG. 12B, the operation may be performed in the following procedure, for example.
First, the controller-side connector Cm of the concentrator cable 44 connected to the beacon head 8 is removed from the connector Cf of the board 7B of the beacon controller 7.

Next, the concentrating cable 44 connected to the beacon head 8 is cut near the connector Cf on the controller side (see FIG. 12A), and the cut portion is discarded.
Next, the connector Cf of the board 7B of the beacon controller 7 and the connector Cf of the relay board 45 are connected by another concentrating cable 48 having connectors Cm at both ends (see FIG. 12B).

Finally, each electric wire of the concentrating cable 44 that has been separated by unraveling the cut portion is inserted into the connection hole of the connector Cb of the relay board 45 (see FIG. 12B).
In this way, the resistor 47 can be connected to the optical beacon 4 without replacing the board 7B of the beacon controller 7 of the installed optical beacon 4 or performing a cable replacement work between the head and the controller. Can be added to other cables.

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

DESCRIPTION OF SYMBOLS 1 Traffic control system 2 In-vehicle apparatus 3 Central apparatus 4 Optical beacon 5 Communication line 6 Communication part 7 Beacon controller 7B Board | substrate 8 Beacon head 9 Case 11 Transmission / reception unit 12 Sensor unit 13 Light emitting unit 14 for communication 14 Light-receiving unit 15 for communication Light-emitting unit for sensing 16 Light-receiving unit for sensing 17 Support column 18 Beam member 20 Vehicle 21 Vehicle-mounted controller 22 Vehicle-mounted head 23 Light-transmitting unit 24 Light-receiving unit 25 Navigation device 27 Light-emitting circuit 28 DC power supply 29 Power cable 31 First voltage Adjustment member (light emission adjustment member)
32 Variable resistor 33 Operation unit 35 Second voltage adjustment member (light emission adjustment member)
36 variable resistor 37 operation unit 39 third voltage adjusting member (light emission adjusting member)
40 Resistor 41 Resistor 42 Resistor 44 Concentration Cable 45 Relay Board 46 Electric Wire 47 Resistor 48 Concentration Cable Cm Connector Cf Connector Cb Connector

Claims (3)

An optical beacon that performs wireless communication with an in-vehicle device of a running vehicle using an optical signal,
A beacon head installed on one or more lanes included in the road;
A beacon controller that causes the beacon head to transmit downlink light;
An optical beacon comprising: a light emission adjusting member capable of adjusting a downlink light emission amount of some or all of the one or more beacon heads in at least two stages.   2. The optical beacon according to claim 1, wherein the light emission adjusting member has an operation unit on a side of the beacon controller that receives an operation for adjusting a downlink light emission amount.   3. The optical beacon according to claim 1, wherein, when the optical beacon includes a plurality of the beacon heads, the light emission adjusting member is capable of adjusting a downlink light emission amount for each of the plurality of beacon heads.

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