JP5003717B2 - Road-to-vehicle communication system and optical beacon - Google Patents

Description

The present invention relates to a road-to-vehicle communication system that performs bidirectional communication using optical signals between an optical beacon installed on a road side and an in-vehicle device mounted on a vehicle, and an optical beacon used therefor .

As a traffic information service using a road-to-vehicle communication system, so-called VICS (Vehicle Information and Communication System: registered trademark of Road Traffic Information Communication System Center) using optical beacons, radio beacons or FM multiplex broadcasting has already been developed. ing. Among these, the optical beacon employs optical communication using near infrared rays as a communication medium, and bidirectional communication with the in-vehicle device is possible.
Specifically, uplink information including travel time information between beacons held by the vehicle is transmitted from the in-vehicle device to the optical beacon on the infrastructure side, and conversely, traffic jam information, section travel time information, event regulation information, and lanes Downlink information including notification information and the like is transmitted from the optical beacon to the vehicle-mounted device (see, for example, Patent Document 1).

The optical beacon includes a beacon head (projector / receiver) that performs two-way communication with an in-vehicle device, and the projector / receiver emits (transmits) downlink information as an optical signal. And a light receiving unit configured by a photodiode (PD) that receives (receives) uplink information transmitted as an optical signal from the in-vehicle device.
For example, as shown in FIG. 9, in the beacon head (projector / receiver) 108 of the optical beacon 104, the communication area A is usually set on the upstream side from directly below. According to the “near-infrared interface standard” of the optical beacon (optical vehicle sensor) 104, the uplink area UA set as an area capable of receiving uplink information is set as an area for transmitting downlink information. The downlink area DA overlaps with the upstream portion in the vehicle traveling direction (the right side portion in FIG. 9), and the upstream ends of the downlink area DA and the uplink area UA coincide with each other.

  Therefore, the vehicle traveling direction length of the downlink area DA matches the same direction length of the entire communication area A. Further, according to the above standard, in the case of the optical beacon 104 for general roads, the downstream end a of the downlink area DA is located on the upstream side of 1.0 to 1.3 m immediately below the beacon head 108, and the downlink The distance from the downstream end a of the area DA to the downstream end b of the uplink area UA is defined as 2.1 m, and the distance from the downstream end b of the uplink area UA to the upstream end c of the area UA is 1.6 m. It is prescribed. Accordingly, in this case, the total length of the communication area A in the vehicle traveling direction is 3.7 m.

  In practice, however, the upstream end of the downlink area DA is often set further upstream (for example, c ′ in FIG. 9) than the upstream end c of the uplink area UA.

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

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

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

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

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

  On the other hand, in order to divide the uplink area in the vehicle traveling direction and set a plurality of divided areas, a plurality of light receiving units for receiving uplink information corresponding to each of the plurality of divided areas are provided. An optical beacon provided in a light receiver has been proposed (see, for example, Patent Document 4).

JP 2005-268925 A JP 2007-293660 A JP 2007-317166 A JP 2008-186349 A

If an optical beacon having a plurality of light receiving portions corresponding to each divided area of the uplink area (hereinafter, sometimes referred to as “PD divided type” optical beacon) is used, the uplink area is in the vehicle traveling direction. Even if it is set widely, by setting the uplink area as a plurality of divided areas, each divided area is set narrow in the vehicle traveling direction, and “distance information” is set in each divided area. It is possible to set a specific position as a starting point. And the position of a vehicle (vehicle equipment) can be specified by specifying in which division field the vehicle equipment transmitted uplink information.
As a result, the starting point of the “distance information” and the actual position of the vehicle (on-vehicle device) do not deviate so much, so the accuracy in specifying the position of the vehicle can be improved, and safe driving support for the driver is provided. It can be performed with high accuracy.

By the way, in the road-to-vehicle communication system using the optical beacon, the light receiver / receiver of the optical beacon is a light other than the uplink light transmitted by the vehicle (on-vehicle device) traveling in the lane in which the projector / receiver is installed, For example, there is a case where sunlight or the like reflected by a road surface or an object existing on the road is received.
When the light projecting / receiving device receives the sunlight that arrives by reflection almost simultaneously with receiving the uplink light from the vehicle-mounted device, the following problems occur. That is, the above-mentioned optical beacon identifies the divided area where the in-vehicle device was located when the uplink light was transmitted by specifying which of the plurality of light receiving units received the uplink light. Can be identified. However, as described above, if the light projector / receiver receives light other than the uplink light transmitted by the in-vehicle device, it is difficult to identify the light receiving unit that has received the uplink light, and the position specifying accuracy of the in-vehicle device is difficult. This causes a problem of lowering.

This invention is made | formed in view of such a situation, suppresses the fall of the specific precision at the time of performing the vehicle position specification using the optical beacon which comprises an uplink area | region in a some division | segmentation area | region, An object of the present invention is to provide a road-to-vehicle communication system capable of providing highly accurate information regarding the position , and an optical beacon used therefor.

  (1) The present invention includes an in-vehicle device of a vehicle traveling on a road, and an optical beacon having a projector / receiver in which a communication region is set in a predetermined range of the road, and the in-vehicle device and the light in the communication region A road-to-vehicle communication system that performs two-way communication using optical signals with a beacon light emitter / receiver, and is provided in the light emitter / receiver, and an uplink region included in the communication region is divided in a vehicle traveling direction. A plurality of light receiving units arranged side by side along a direction corresponding to the vehicle traveling direction so that uplink light can be received corresponding to the plurality of divided regions, and each of the plurality of light receiving units outputs A determination unit that determines whether or not light reception is recognized in each of the plurality of light receiving units based on a light reception level, and the vehicle in an uplink region based on a determination result of the determination unit The position specifying unit for specifying the transmission position of the uplink light of the machine and the determination unit determine that light reception is recognized only in one light receiving unit or only two light receiving units adjacent to each other among the plurality of light receiving units. In this case, a control unit that causes the light projector / receiver to transmit downlink light including position information related to the transmission position specified by the position specifying unit is provided.

In the road-to-vehicle communication system configured as described above, the uplink light transmitted to the light projecting / receiving device as the spot light is received by the light receiving units arranged side by side in correspondence with each of the plurality of divided regions. When it is determined that light reception is recognized only in one light receiving unit or only two light receiving units adjacent to each other among the plurality of light receiving units, it is determined that the light emitter / receiver receives one uplink light. The position specifying unit can accurately specify the light receiving unit receiving the uplink light.
In the road-to-vehicle communication system of the present invention, the control unit determines that the light reception is recognized by only one light receiving unit or only two light receiving units adjacent to each other among the plurality of light receiving units. When it is possible to accurately determine the light receiving unit receiving the uplink light by determining that it has received two uplink lights, the downlink light including the position information specified by the position specifying unit Send to projector / receiver.
For this reason, the optical beacon can transmit only position information relating to the transmission position accurately located by receiving one uplink light to the in-vehicle device, and provides highly accurate information regarding the position of the vehicle. be able to.
In the road-to-vehicle communication system, when the control unit determines that light reception is recognized in only one light receiving unit or only two light receiving units adjacent to each other among the plurality of light receiving units, In addition to the position information related to the transmission position specified by the position specifying unit, the vehicle ID included in the received uplink light and the downlink light including traffic information are transmitted to the light projector / receiver, and the determination unit includes the When it is determined that light reception is recognized in two light receiving parts arranged at positions not adjacent to each other among the plurality of light receiving parts, the vehicle ID and the traffic information, which are information other than the position information, are included. You may make a downlink light transmit to the said light projector / receiver.

(2) In addition, when the determination unit determines that light reception is recognized in two light receiving units arranged at positions not adjacent to each other among the plurality of light receiving units, the control unit receives the up It is preferable that information obtained from the link light is discarded.
If it is determined that light is received by two light receiving units arranged at positions that are not adjacent to each other, the light emitter / receiver receives at least two or more lights, so which light receiving unit is the uplink light It is impossible to specify whether or not the light is received, and the position specification by the position specifying unit cannot be performed with high accuracy.
In other words, in the above configuration, when the projector / receiver receives at least two or more lights and cannot specify the uplink light and the position cannot be accurately determined, the control unit receives the received up information including the position information. Since the information obtained from the link light is discarded, it is possible to prevent position information with low accuracy from being transmitted to the in-vehicle device.

(3) When the control unit determines that light reception is recognized in two light receiving units arranged at positions not adjacent to each other among the plurality of light receiving units, the control unit determines the position information. The downlink light not included may be transmitted to the projector / receiver.
In the above configuration, the control unit causes the transmitter / receiver to receive at least two or more lights, and when the uplink light cannot be identified and the position cannot be accurately identified, the control unit causes the downlink light not including the position information to be transmitted. Therefore, it is possible to prevent transmission of position information with low accuracy to the in-vehicle device.

(4) In the road-to-vehicle communication system, when it is determined that light reception is recognized in two light receiving units adjacent to each other, the position specifying unit sets the uplink light transmission positions of the vehicle-mounted devices adjacent to each other. The boundary part of the two divided regions corresponding to the two light receiving units may be specified, in this case, the position specifying unit can more specifically specify the transmission position of the uplink light of the in-vehicle device, The accuracy of the information regarding the position of the vehicle can be improved.
Further, the present invention is an optical beacon having a light projecting and receiving device that sets a communication area in a predetermined range of a road and performs bidirectional communication with an in-vehicle device using an optical signal, and is provided in the light projecting and receiving device, The uplink areas included in the communication area are arranged side by side along the direction corresponding to the vehicle traveling direction so as to be able to receive uplink light corresponding to a plurality of divided areas obtained by dividing the uplink area in the vehicle traveling direction. Based on a plurality of light receiving units, a light receiving level output from each of the plurality of light receiving units, a determination unit that determines whether or not light reception is recognized in each of the plurality of light receiving units, and a determination result of the determination unit The position specifying unit that specifies the transmission position of the uplink light of the in-vehicle device in the uplink region and the determination unit are only one light receiving unit among the plurality of light receiving units or adjacent to each other. A control unit that transmits downlink light including position information related to the transmission position specified by the position specifying unit to the light projector / receiver when it is determined that light reception is recognized only in the two light receiving units. It is characterized by being.
When the determination unit determines that light reception is recognized only in one light receiving unit or only two light receiving units adjacent to each other among the plurality of light receiving units, the position specifying unit specifies the In addition to the positional information related to the transmission position, the vehicle ID included in the received uplink light and the downlink light including traffic information are transmitted to the light projecting / receiving device, and the determination unit is the plurality of light receiving units, When it is determined that light reception is recognized at two light receiving units arranged at positions not adjacent to each other, the light emitting / receiving the downlink light including the vehicle ID and the traffic information, which is information other than the position information You may make it transmit to a device.

As described above, according to the road-to-vehicle communication system of the present invention, it is possible to suppress a decrease in vehicle position specifying accuracy when specifying the position of a vehicle using an optical beacon that configures an uplink region with a plurality of divided regions. It is possible to provide highly accurate information regarding the position of the vehicle. Further, according to the optical beacon of the present invention, it is possible to provide highly accurate information regarding the position of the vehicle.

1 is a block diagram showing an overall configuration of a road-vehicle communication system according to a first embodiment of the present invention. It is a top view of an optical beacon. It is a side view which shows the communication area | region of an optical beacon. It is a schematic block diagram of the vehicle equipment which carries out road-vehicle communication, and the vehicle carrying this. It is a block diagram which shows an example of the circuit structure of a light-receiving part and a beacon controller. It is the graph which showed the relationship between the transmission position when a vehicle equipment transmits uplink light, and the light reception level of each light-receiving part when receiving the uplink light. It is a conceptual diagram which shows the procedure and data content of the road-vehicle communication performed in a communication area. It is a conceptual diagram which shows the procedure and data content of the road-vehicle communication in the road-vehicle communication system which concerns on 2nd embodiment of this invention. It is a side view which shows the communication area | region of the conventional optical beacon.

[First embodiment]
[Overall system configuration]
FIG. 1 is a block diagram showing an overall configuration of a road-vehicle communication system according to a first embodiment of the present invention. As shown in FIG. 1, the road-to-vehicle communication system includes an infrastructure-side traffic control system 1 and an in-vehicle device 2 mounted on each vehicle C traveling on a road R.
The traffic control system 1 includes a central device 3 provided in a control room, and a large number of optical beacons (optical vehicle detectors) 4 installed at various locations on the road R. The optical beacon 4 performs bidirectional communication with the in-vehicle device 2 by optical communication using near infrared rays as a communication medium.

[Configuration of optical beacon]
The optical beacon 4 includes a communication unit 6 that is a communication interface connected to the central apparatus 3 via a communication line 5 such as a telephone line, a beacon controller 7 to which the communication unit 6 is connected, and the beacon controller 7. And a plurality (four in the illustrated example) of beacon heads (projector / receiver) 8 connected to the sensor interface.
Each beacon head 8 houses a light projecting unit 10 constituted by light emitting diodes (LEDs) and a plurality of light receiving units 9 constituted by photodiodes (PDs) (see FIG. 3). ).

Among these, the light projecting unit 10 projects (transmits) downlink light DO (an optical signal constituting the downlink information 34 and 36) made of near infrared rays to a communication area A described later.
The plurality of light receiving units 9 are for receiving uplink light UO (an optical signal constituting the uplink information 35) made of near-infrared rays from the in-vehicle device 2, each of which is an uplink area UA described later. Are provided corresponding to the divided areas UA1 to UA4.

  FIG. 2 is a plan view of the optical beacon 4. As shown in FIG. 2, the optical beacon 4 of this embodiment is installed on a road R having a plurality of lanes R1 to R4 (four in the illustrated example) in the same direction, and corresponds to each lane R1 to R4. A plurality of beacon heads 8 and one beacon controller 7 serving as a control unit that collectively controls the beacon heads 8.

The beacon controller 7 is composed of a programmable microcomputer having a CPU, a memory (RAM), and a storage device (ROM). It has a function as a control unit 49 that performs control of road-to-vehicle communication with the aircraft 2 and determination of a determination result of a determination unit 50 described later.
The contents of road-to-vehicle communication by the beacon controller 7 will be described later.

Further, the beacon controller 7 stores a computer program for executing each predetermined function in its own storage device, and in addition to the control unit 49, each light receiving unit 9 as a functional part to be executed by this program. For determining whether or not the uplink light UO is received, and for determining the transmission position of the in-vehicle device 2 when transmitting the uplink light UO based on the determination result of the determination unit 50 A position specifying unit 51 is provided (see FIGS. 1, 2 and 4).
The processing contents of the determination unit 50 and the position specifying unit 51 will be described later.

The beacon controller 7 is installed on a support column 13 standing on the side of the road, and each beacon head 8 is attached to an installation bar 14 installed horizontally on the road R side from the support column 13, and each lane R1 of the road R. It is arrange | positioned just above -R4.
The light projecting unit 10 of each beacon head 8 emits near infrared rays toward the upstream side in the vehicle traveling direction from directly below the lanes R <b> 1 to R <b> 4. A communication area A for performing the above is set on the upstream side of the head 8.

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

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

According to the “near infrared interface standard” of the optical beacon (optical vehicle sensor) 4, the formal area dimensions of the downlink area DA and the uplink area UA are defined. In this rule, in the case of an optical beacon 4 for a general road, the downstream end a of the downlink area DA is located 1.0 to 1.3 m upstream immediately below the beacon head 8 and is downstream of the downlink area DA. The distance from the end a to the downstream end b of the uplink area UA is defined as 2.1 m.
Further, the distance from the downstream end b of the uplink area UA to the upstream end c of the area UA is defined as 1.6 m. Accordingly, the total length of the official communication area A in the vehicle traveling direction (the length between ac) is 3.7 m.

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

Further, the uplink area UA is composed of divided areas UA1 to UA4 obtained by dividing the area UA in the vehicle traveling direction to such an extent that the traveling position of the vehicle C can be specified. In FIG. 3, the uplink areas UA <b> 1 to UA <b> 4 are divided into four by three boundary lines (boundary portions) BL having the position d as the upper end and the positions e <b> 1 to e <b> 3 on the road R as the lower end. In practice, as will be described later, however, there are overlapping regions that overlap each other at the boundary between adjacent divided regions.
The four light receiving units 9 (see FIG. 1) provided in the beacon head 8 use the divided areas UA1 to UA4 of the uplink area UA as light receiving areas. Therefore, for example, the uplink light UO transmitted from the in-vehicle head 27 in the divided area UA1 located on the most upstream side is received by the light receiving unit 9 corresponding to the divided area UA1.

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

The ECU 22 performs various controls on the vehicle C, such as drive control of the engine 23 based on the accelerator operation of the driver and braking control based on the brake operation.
The in-vehicle device 2 includes an in-vehicle computer 26, an in-vehicle head (projector / receiver) 27 connected to the sensor interface of the computer 26, a display 28 and a speaker device 29 as a human interface for the driver of the passenger seat. Yes.

The vehicle-mounted head 27 includes a light projecting unit made of a light emitting diode (LED) and a light receiving unit made of a photodiode (not shown), like the light beacon light projecting / receiving device 8. The light projecting unit transmits uplink light UO (uplink information 35) made of near infrared rays, and the light receiving unit is downlink light DO (downlink information 34, 36) made of near infrared rays emitted to the communication area A. Is received.
The in-vehicle computer 26 includes a programmable microcomputer having a CPU, a memory (RAM), and a storage device (ROM), and performs control processing for road-to-vehicle communication with the optical beacon 4 by the in-vehicle head 27.

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

[Circuit configuration of light receiving unit and beacon controller]
FIG. 5 is a block diagram illustrating an example of a circuit configuration of the light receiving unit and the beacon controller. In FIG. 5, four light receiving units 9 are provided in the beacon head 8, and photodiodes that function independently from each other are arranged side by side, and correspond to the divided areas UA <b> 1 to UA <b> 4. Of the four light receiving portions 9 (hereinafter, also referred to as photodiodes PD1 to PD4), the photodiode PD1 corresponds to the divided area UA1 on the most upstream side, and the photodiodes PD2 to PD4 are respectively 2 from the upstream side. This corresponds to the third, fourth, and fourth divided areas UA2 to UA4.
The photodiodes PD1 to PD4 can be arranged by arranging a plurality of photodiodes made of independent substrates, or a plurality of photodiodes functioning independently from each other on a single substrate. You can also

  Each of the photodiodes PD1 to PD4 includes a plurality of amplification circuits 42 connected to each of the photodiodes to amplify each output voltage, an adder 43, a comparator 44, and a detection circuit 46 on the subsequent stage of the amplification circuit 42. It is mounted on a plurality of beacon heads 8 corresponding to the respective lanes R1 to R4.

The amplifying circuit 42 includes an amplifying element such as an n-type MOSFET and a plurality of operational amplifiers for further amplifying the output voltage of the element, and amplifies the output voltage of each PD1 to PD4 on the order of 10,000 to 100,000 times, for example. be able to. In the present embodiment, the amplification factors of the amplification circuits 42 corresponding to the photodiodes PD1 to PD4 are all set to be substantially the same.
The output side of each amplifier circuit 42 is connected to a single adder 43, and a comparator 44 is connected to the output side of this adder 43.
The output voltage from each amplifier circuit 42 is superimposed on one analog signal by the adder 43. Further, the analog signal output from the adder 43 is converted into a digital signal by the comparator 44 and sent to the processing processor 45 of the beacon controller 7. The processor 45 extracts the data signal and communication control signal included in the uplink information 35 from the digital signal sent from the comparator 44.

The output side of each amplifier circuit 42 is branched and connected to a plurality of detection circuits 46. The output sides of these detection circuits 46 are connected to an A / D converter 47 in the beacon controller 7. The output voltage of each amplifier circuit 42 is smoothed by the detection circuit 46, converted to a digital signal by the A / D converter 47 in the subsequent stage, and sent to the processing processor 45 of the beacon controller 7.
The processing processor 45 acquires the light reception levels of the photodiodes PD1 to PD4 from the digital signal of the A / D converter 47, and compares these light reception levels with a predetermined threshold value, so that the uplink light in the photodiodes PD1 to PD4. It is determined for each of the photodiodes PD1 to PD4 whether light reception for UO or other light is recognized.
Further, based on the determination result, the processor 45 identifies any one of the photodiodes PD1 to PD4 as a light receiving photodiode that has received the uplink light UO, and has transmitted the uplink light UO. The transmission position of the vehicle-mounted device 2 is specified.
Furthermore, the processing processor 45 performs a light reception error determination described later based on the determination result.

The processing processor 45 executes a computer program stored in the storage device 48 in the beacon controller 7, so that each of the photodiodes PD <b> 1 to PD <b> 4 based on the above-described light reception level in addition to the communication control function related to road-to-vehicle communication. A light reception determination function, a function for specifying the transmission position of the vehicle-mounted device 2, and a light reception error determination function are realized.
The storage device 48 includes a computer program related to each of the above functions, and stores the threshold value for determining whether light reception is recognized in each photodiode.

  In other words, the processing processor 45 and the storage device 48 determine the light receiving level of the photodiodes PD1 to PD4 based on the light receiving levels of the photodiodes PD1 to PD4. A position specifying unit 51 that specifies a transmission position and a control unit 49 that performs light reception error determination based on the determination result of the determination unit 50 are configured (see FIGS. 1 and 2).

  Further, the processing processor 45 is based on the data signal included in the uplink information 35, the information on the transmission position of the specified in-vehicle device 2, the information given from the central device 3 through the communication unit 6, and the like. Generate information to be sent to.

  In the present embodiment, the processing processor 45 is configured to perform both processing on the digital signal output from the comparator 44 and processing on the digital signal output from the A / D converter 47. Although illustrated, for example, the beacon controller 7 includes a first processor for performing processing for the output of the comparator 44 and a second processor for performing processing for the output of the A / D converter 47. Each processor may be configured to perform each process. In this case, the beacon controller 7 includes a storage device corresponding to each of the processors, and the storage device corresponding to the first processor stores a computer program for realizing a communication control function by the first processor. Remembered. In addition, the storage device corresponding to the second processor stores a computer program for realizing a light reception determination function, a transmission position specifying function, and the like by the second processor, and the threshold value. Furthermore, the storage device corresponding to the second processor can also be configured by a storage device for storing various computer programs and a storage device for storing the threshold value.

[Processing contents of the determination unit and position specifying unit]
Next, processing contents performed by the determination unit 50 and the position specifying unit 51 of the beacon controller 7 will be described. FIG. 6 shows the relationship between the transmission position when the in-vehicle device 2 transmits the uplink light UO and the light reception level of each light receiving unit 9 (photodiodes PD1 to PD4) when the uplink light UO is received. It is a graph.

In FIG. 6, the horizontal axis indicates the position when the vehicle-mounted device 2 transmits the uplink light UO, and the vehicle-mounted device positioned upstream from the reference point with the reference point (0) directly below the beacon head 8. The distance to position 2 is shown. Therefore, on the graph, the right side of the drawing is the upstream side and the left side is the downstream side. The vertical axis indicates the light receiving level of each of the photodiodes PD1 to PD4 when output to the processing processor 45.
Each of the diagrams V1 to V4 shows an example of the result of measuring the relationship between the transmission position of the uplink light by the in-vehicle device 2 and the light reception level of the photodiodes PD1 to PD4 at that time.

The uplink light UO transmitted by the in-vehicle device 2 is transmitted as spot light from the in-vehicle head 27, and thus forms an irradiation surface having a certain area with respect to the photodiode. 2 sequentially passes over the photodiodes PD1 to PD4. For this reason, the irradiation area with respect to the photodiode on the irradiation surface of the uplink light UO gradually increases and reaches the maximum when the irradiation surface enters the region on the photodiode from the region outside the photodiode. After that, it gradually decreases when leaving the region on the photodiode. That is, the light receiving area in which each photodiode receives the uplink light UO gradually increases and reaches the maximum value when the light reception of the uplink light UO is started in accordance with the movement of the vehicle-mounted device 2. Decreases when exceeds the maximum value.
Further, the light receiving level of the photodiode changes according to the light receiving area for receiving the uplink light UO.
For this reason, the diagrams V1 to V4 showing the light receiving levels of the photodiodes PD1 to PD4 increase to the maximum value as the vehicle-mounted device 2 advances from the upstream side toward the downstream side, as shown in FIG. When the maximum value is reached, it appears in a mountain shape that decreases as the vehicle-mounted device 2 progresses.
Further, since the photodiodes PD1 to PD4 are arranged side by side, both receive the uplink light UO in the vicinity of the boundary between the photodiodes arranged adjacent to each other. Diagrams of photodiodes that are adjacent to each other appear to overlap each other.

The light intensity of the uplink light UO when it reaches the photodiode depends on the installation angle of the photodiode, the transmission angle of the uplink light UO of the in-vehicle device 2, the distance between the photodiode and the in-vehicle device 2, and the like. Of these, the influence of the distance between the photodiode and the vehicle-mounted device 2 on the light intensity of the uplink light UO appears as follows.
That is, in general, light diverges as the distance from the light source increases, and the intensity thereof decreases. Therefore, the light intensity of the uplink light UO when it reaches the photodiode is the in-vehicle device when the uplink light UO is transmitted. The farther the divided area where 2 is located is from the beacon head 8, the lower it is. In addition, since the received light level of the photodiode increases as the intensity of received light increases, the photodiode is located at the most upstream side as shown in FIG. The maximum value of the light receiving level of the photodiode PD4 corresponding to UA4 appears to be the smallest as compared with the other ones, and the maximum value of the light receiving level increases as the corresponding divided area sequentially approaches the beacon head 8, The maximum value of the light receiving level of the photodiode PD1 corresponding to the divided area UA1 set at the position closest to the beacon head 8 appears the largest as compared with the others.

The beacon head 8 according to the present embodiment has an output characteristic when the uplink light UO transmitted from the in-vehicle device 2 is received as shown in FIG. 6, and is divided into areas UA1 on the road R by the photodiodes PD1 to PD4. ~ UA4 are set, and the uplink area UA is set.
That is, based on the light reception levels of the photodiodes PD1 to PD4, in this embodiment, whether the light reception level when the photodiode receives the uplink light UO is a value that can be recognized as receiving light. A threshold value for determining whether or not each of the photodiodes PD <b> 1 to PD <b> 4 is defined, and divided areas UA <b> 1 to UA <b> 4 on the road R are defined.
The processor 45 compares the light reception level of each of the photodiodes PD1 to PD4 with the threshold value, and determines whether or not light reception is recognized in each of the photodiodes PD1 to PD4, whereby the received uplink light UO is detected. Of the divided areas UA1 to UA4, it can be recognized from which divided area, and as a result, the transmission position of the in-vehicle device 2 when the uplink optical UO is transmitted can be specified. it can.

The processor 45 determines that light reception is recognized for each of the photodiodes PD1 to PD4 when the light reception level is higher than the threshold values v _{th1 to} v _th4 shown in FIG.
Among these thresholds v _th1 to v _th4, threshold v _th4 is set to the largest value, or less, in the order of threshold v _th3 to v _th1, is set to gradually decrease. That is, each value of the threshold v _th1 to v _th4 is farther position of the divided region UA1~UA4 corresponding to the photodiode PD1~PD4 is respectively set from the position of the beacon heads 8 of each threshold v _th1 to v _th4 It is set so that it may become a small value in order from what is. These threshold values v _{th1 to} v _th4 are stored and stored in the storage device 48, and the processing processor 45 can refer to them as necessary.

In the present embodiment, the values of the threshold values v _{th1 to} v _th4 are set so that the values of the divided areas UA1 to UA4 corresponding to the threshold values v _{th1 to} v _th4 become smaller in order from the position farther from the position of the beacon head 8. was set, and the threshold value v _th2 to v _th4 photodiode PD2~4 the same value, the threshold value of the threshold v _th1 only other photodiode PD2~4 photodiodes PD1 corresponding to the divided region UA1 located most upstream It may be set smaller than v _{th2 to} v _th4 .

Next, the processing of the beacon controller 7 (processing processor 45) when the vehicle-mounted device 2 approaching the beacon head 8 passes the uplink area UA while transmitting the uplink light UO will be specifically described.
When the vehicle-mounted device 2 approaching the beacon head 8 is at a position farther than the position of the distance g0 in FIG. 6, none of the photodiodes receives the uplink light UO, so that each of the photodiodes PD1 to PD4 The light reception levels are all “0”. For this reason, the processing processor 45 does not determine that any of the photodiodes PD1 to PD4 is receiving the uplink light UO.

Next, when the vehicle-mounted device 2 passes the position of the distance g0 and is located between the distance g0 and the distance g1, the photodiode PD1 starts receiving the uplink light UO, and the light reception level increases. The light reception level is smaller than the threshold value v _{th1 and the} light reception levels of the other photodiodes PD2 to PD4 are “0”. In this case as well, the processing processor 45 performs any of the photodiodes PD1 to PD4. It is not determined that the uplink light UO is received. In this case, the processing processor 45 does not identify the light receiving photodiode that receives the uplink light UO.

When the in-vehicle device 2 passes the position of the distance g1 and is located between the distance g1 and the distance g2, the light receiving level of the photodiode PD1 is larger than the threshold value v _th1 , so that the processing processor 45 determines that the photodiode PD1 is It is determined that the uplink light UO is received. In addition, the photodiode PD2 starts to receive the uplink light UO, and the light reception level rises. However, since the light reception level is smaller than the threshold value _vth2 , the processing processor 45 receives the uplink light UO. Not determined to be.
For this reason, when the vehicle-mounted device 2 is located between the distance g1 and the distance g2, the processing processor 45 determines that the uplink light UO is received only by the photodiode PD1. Therefore, if the processing processor 45 determines that the uplink light UO is received only by the photodiode PD1, the vehicle-mounted device 2 is positioned in the divided area UA1 (between the distance g1 and the distance g2) corresponding to the photodiode PD1. It can be determined.

Next, when the vehicle-mounted device 2 passes through the position of the distance g2 and is located between the distance g2 and the distance g3, the light receiving level of the photodiode PD2 becomes larger than the threshold value v _th2 , so the processor 45 It is determined that the photodiode PD3 is receiving the uplink light UO. On the other hand, since the light receiving level of the photodiode PD1 is also larger than the threshold value v _th1 , the processing processor 45 determines that the photodiode PD1 is also receiving the uplink light UO.
The region between the distance g2 and the distance g3 is an overlapping region where the divided region UA1 corresponding to the photodiode PD1 and the divided region UA2 corresponding to the photodiode PD2 overlap each other at the boundary. When the processing processor 45 determines that PD1 and PD2 are receiving the uplink light UO, the in-vehicle device 2 is an overlapping region where the divided region UA1 and the divided region UA2 overlap (between the distance g2 and the distance g3). It can be determined that
Further, in the overlapping area between the divided areas UA1 and UA2, the light receiving levels of the photodiodes PD1 and PD2 are compared, and the position of the in-vehicle device 2 that has transmitted the uplink light UO is within the overlapping area. It is also possible to make the processing processor 45 specify whether it is closer to the divided area.

  The overlapping area exists at the boundary between adjacent divided areas, and is an area between the distance g4 and the distance g5. The overlapping area UA2 (between the distance g3 and the distance g4) and the divided area UA3 (distance) between the divided area UA3 and the divided area UA4 (between the distance g7 and the distance g8) in the area between the distance g6 and the distance g7. Overlapping areas are configured.

  Since the reception determination result when the uplink optical UO is received differs depending on which of the above-described areas the position of the vehicle-mounted device 2 to which the uplink optical UO is transmitted, the processing processor 45 Similarly, by performing the light reception determination of the photodiodes PD1 to PD4, it is possible to specify which of the above regions is the position of the in-vehicle device 2 when the received uplink light UO is transmitted.

When the in-vehicle device 2 passes the distance g8, the light receiving level of the photodiode PD4 becomes smaller than the threshold value v _th4 , and thus the processing processor 45 does not determine that the photodiode PD1 is receiving the uplink light UO. Further, since the light receiving levels of the other photodiodes PD1 to PD3 are “0”, the processing processor 45 does not determine that any of the photodiodes PD1 to PD4 is receiving the uplink light UO.

  Further, the uplink area UA is set in the range from the distance g1 to the distance g8, which is an area in which it is determined that any one of the photodiodes receives the uplink light UO in FIG. That is, the upstream end c in FIG. 3 corresponds to the position of the distance g1 in FIG. 6, and the downstream end b in FIG. 3 corresponds to the position of the distance g8 in FIG. However, as shown in FIG. 6, the uplink optical UO can be received from a position at a distance g0 upstream from the distance g1 to a position at a distance g9 downstream from the distance g8. The area in which the uplink optical UO as information can be received is slightly wider than the uplink area UA for specifying the position of the in-vehicle device 2. In addition, the communication area such as the uplink area UA may slightly fluctuate due to system operation errors such as the installation mode of each device.

As described above, in this embodiment, the threshold values v _{th1 to} v _th4 for determining whether or not light reception is permitted are set for each of the photodiodes PD1 to PD4, so that the divided areas UA1 to UA4 on the road R are set. (And overlapping area) are set.
The processor 45 performs light reception determination for each of the photodiodes PD1 to PD4, and based on the determination result, the received uplink light UO is transmitted from any divided area (or overlapping area) among the divided areas UA1 to UA4. As a result, the transmission position of the vehicle-mounted device 2 when transmitting the uplink optical UO can be specified in units of the divided areas UA1 to UA4 or in units smaller than that. .

[Determination of light reception error]
Here, the beacon head 8 receives light other than the uplink light UO transmitted by the vehicle-mounted device 2, for example, sunlight reaching the road R or an object existing on the road R, etc. There is a case.
If the beacon head 8 receives the uplink light UO from the in-vehicle device 2 and receives sunlight or the like that arrives by reflection, two light beams are received in the photodiodes PD1 to PD4. As a result, it is difficult to identify the photodiode that actually received the uplink light UO, and there is a risk that the accuracy in identifying the transmission position of the uplink light UO of the in-vehicle device 2 may be reduced.

  Therefore, the processing processor 45 determines whether or not the beacon head 8 receives light other than the uplink light UO such as sunlight based on the determination result of the determination unit 50. When determining that light other than the uplink light UO is received, the processing processor 45 determines that a light reception error has occurred.

The processor 45 performs light reception error determination based on the determination result of the determination unit 50 as follows.
Referring to FIG. 6, when the beacon head 8 receives only the uplink light UO, the result of the light reception determination of each photodiode PD1 to PD4 by the determination unit 50 is one photo of each photodiode PD1 to PD4. There are two cases: light reception is recognized only in the diode (divided region) and light reception is recognized only in two adjacent photodiodes (overlapping region). As described above, the uplink light UO from the in-vehicle device 2 is transmitted as spot light from the in-vehicle head 27, thereby constituting an irradiation surface having a certain area with respect to the photodiode. This is because the irradiation surface sequentially passes over the photodiodes PD <b> 1 to PD <b> 4 according to the movement of the vehicle-mounted device 2. That is, when the beacon head 8 receives the uplink light UO, the irradiation surface is located only on one photodiode or on the boundary between two photodiodes arranged adjacent to each other. Because it is either.

For example, in FIG. 6, when the in-vehicle device 2 is located in the divided area UA1 between the distance g1 and the distance g2, only the light reception level of the photodiode PD1 is larger than the corresponding threshold value v _th1 , so the determination unit 50 It is determined that light reception is recognized only in the photodiode PD1. Similarly, the position of the vehicle-mounted device 2 is between the divided area UA2 that is between the distance g3 and the distance g4, the divided area UA3 that is between the distance g5 and the distance g6, and the distance g7 and the distance g8. In the case of the divided area UA4, the determination unit 50 determines that light reception is recognized only in the photodiodes PD2, PD3, and PD4.

Further, when the vehicle-mounted device 2 is located in the overlapping region between the distance g2 and the distance g3, the photodiode PD1 and the light receiving level of the photodiode PD2 arranged adjacent to each other correspond to the threshold _values v _th1 respectively. , V _th2 , the determination unit 50 determines that light reception is recognized only in the photodiodes PD1 and PD2. Similarly, when the position of the vehicle-mounted device 2 is between the distance g4 and the distance g5, which are overlapping regions, and between the distance g6 and the distance g7, the determination unit 50 includes the photodiodes PD2, PD3, In addition, it is determined that light reception is recognized in the photodiodes PD3 and PD4.

  As described above, in the present embodiment, when the beacon head 8 receives one uplink light UO in the uplink area UA, the determination unit 50 determines only one of the photodiodes PD1 to PD4. The determination is made either in the case where light reception is recognized in FIG. 5 or in the case where light reception is recognized only in two adjacent photodiodes.

  Conversely, when the determination unit 50 determines that light reception is recognized only in one photodiode or in two adjacent photodiodes among the photodiodes PD1 to PD4 as described above, the beacon head 8 Since it can be determined that one uplink light UO is received, and the position specifying unit 51 can accurately specify the photodiode receiving the uplink light UO, the processor 45 When the determination unit 50 performs the above determination, it is determined that no light reception error has occurred.

On the other hand, if the determination unit 50 determines that light reception is recognized in two photodiodes arranged at positions not adjacent to each other among the photodiodes PD1 to PD4, a light reception error occurs. It is determined that
When the beacon head 8 simultaneously receives the uplink light UO from the vehicle-mounted device 2 and light other than the uplink light UO such as sunlight, the light receiving level by the uplink light UO is received at each of the photodiodes PD1 to PD4. In addition to the increase in the light receiving level, an increase in the light receiving level due to light other than the uplink light UO appears. As described above, among the photodiodes PD1 to PD4, the two photodiodes arranged at positions that are not adjacent to each other. When the diode receives light, it can be determined that light other than the uplink light UO is received.

For example, when light reception is recognized at the photodiode PD1 and the photodiode PD3 that is not adjacent to the photodiode PD1, the uplink light UO is received by one of the photodiodes, and the other photodiode is received. It is clear that light other than the uplink light UO is received by the diode.
Further, even when light reception is recognized in the photodiodes PD1 to PD3, the uplink light UO is received by only one photodiode or only two photodiodes adjacent to each other, and thus either the photodiode PD1 or PD3. Thus, it is clear that light other than the uplink light UO is received. Even in this case, light reception is recognized by the two photodiodes PD1 and PD3 arranged at positions not adjacent to each other.

  As described above, when the determination unit 50 determines that light reception is recognized in two photodiodes arranged at positions not adjacent to each other among the photodiodes PD1 to PD4, a light reception error occurs. Determine that it has occurred.

As described above, the processing processor 45 performs the light reception error determination in which the beacon head 8 determines whether the beacon head 8 receives light other than the uplink light UO together with the uplink light UO based on the determination result of the determination unit 50. Do.
Processing performed based on this light reception error determination will be described later.

  The light reception error determination is based on the determination result of the determination unit 50, that is, the light reception determination of each of the photodiodes PD1 to PD4. For example, the photodiode that has received light other than the uplink light UO and the uplink When the photodiode that has received the light UO is exactly the same, the determination unit 50 determines that light reception is recognized in the photodiode that has received both lights. Therefore, in this case, it is possible to specify the photodiode that has received the uplink light UO, and various signals included in the uplink light UO received by the photodiode are light other than the uplink light UO. However, there is no influence on the decrease in accuracy when the transmission position of the uplink optical UO of the in-vehicle device 2 is specified.

[Contents of road-to-vehicle communication (processing contents of the control unit)]
FIG. 7 shows a two-way road-to-vehicle communication procedure performed between the beacon head 8 and the vehicle-mounted head 27 in the communication area A. Hereinafter, the contents of the road-to-vehicle communication of the present embodiment will be described with reference to FIG.

First, the beacon controller 7 (the control unit 49) of the optical beacon 4 starts from the beacon heads 8 corresponding to the lanes R1 to R4, as the first information before switching the downlink, the first down including the lane notification information. The link information 34 is constantly transmitted to the downlink area DA of each lane R1 to R4 at a predetermined transmission cycle (F1 in FIG. 7).
At this stage, the vehicle ID is not yet stored in the lane notification information.

When the vehicle C equipped with the in-vehicle device 2 enters the actual downlink area DA, the in-vehicle head 27 of the in-vehicle device 2 receives the first downlink information 34 including the lane notification information (no vehicle ID).
At this time, the in-vehicle computer 26 of the in-vehicle device 2 recognizes that the vehicle C exists in the actual communication area A. Thereafter, the in-vehicle computer 26 starts transmission of the uplink information 35 (F2 in FIG. 7), and transmits this uplink information 35 to the beacon head 8 at a predetermined transmission cycle (uplink transmission cycle) (FIG. 7). 7 F3).

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

On the other hand, when the beacon head 8 of the optical beacon 4 receives (receives) the uplink information 35 (F4 in FIG. 7), the determination unit 50 of the beacon controller 7 performs light reception determination for each of the photodiodes PD1 to PD4. At the same time, the control unit 49 performs the above-described light reception error determination based on the determination result by the determination unit 50 (F5 in FIG. 7).
Next, the control unit 49 determines whether or not a light reception error has occurred as a result of the light reception error determination (F6 in FIG. 7).
When it is determined that a light reception error has not occurred, the control unit 49 performs downlink switching and starts transmitting the second downlink information 36 including the lane notification information including the vehicle ID information as the second information. Then, the transmission of the second downlink information 36 is repeated as much as possible within a predetermined time (F9 in FIG. 7).

On the other hand, when it is determined that a light reception error has occurred, the control unit 49 discards the information obtained from the received uplink information 35, and switches to the first downlink information 36 without switching to the transmission of the second downlink information 36. The transmission of the downlink information 34 is continued (F7 in FIG. 7).
Then, again, the beacon head 8 receives (receives) the uplink information 35 transmitted according to the first downlink information 34, and the determination unit 50 has an opportunity to make a determination on each of the photodiodes PD1 to PD4. wait.
Thus, when it is determined that a light reception error has occurred (F6 in FIG. 7), the control unit 49 is located at a position where the determination unit 50 is not adjacent to each other among the plurality of photodiodes PD1 to PD4. When it is determined that light reception is recognized in the two arranged photodiodes, the uplink information is not received by discarding information (including position information based on the light reception determination) obtained from the received uplink information 35. As a result, the transmission of the first downlink information 34 is continued (F7 in FIG. 7). That is, discarding the uplink information does not perform switching from transmission of the first downlink information 34 to transmission of the second downlink information 36 based on the uplink information in transmission of the downlink information. Means that.
When the beacon head 8 receives the uplink information 35 again, the beacon controller 7 repeats the same process as described above.

The lane notification information includes a field for storing a vehicle ID for each lane R1 to R4 (FIG. 2), and a lane number can be assigned to each vehicle ID.
For this reason, the in-vehicle computer 26 of each vehicle C traveling in different lanes R1 to R4 determines which lane R1 to R4 the host vehicle is in by determining which of the storage fields includes the vehicle ID of the host vehicle. Can recognize if you are driving.

The second downlink information 36 includes traffic information, section travel time information, event regulation information, and support information for safe driving support for the driver, in addition to the lane notification information including the vehicle ID. Yes.
The support information includes signal information that is timing information for changing the color of the traffic light downstream from the optical beacon 4 and a predetermined downstream side from the uplink area UA based on the transmission position specified by the position specifying unit 51. The distance information related to the distance to the position (for example, the stop line) is included.

As shown in FIG. 7, the second downlink information 36 includes a single or a plurality of minimum frames 37. According to the “near infrared interface standard”, the data amount of the minimum frame 37 is defined as a total of 128 bytes, and 5 bytes are allocated to the header portion 38 and 123 bytes are allocated to the actual data portion 39.
According to the standard, the second downlink information 36 can be composed of 1 to 80 minimum frames 37, and the transmittable time is set to 250 ms. The downlink information 36 includes an arbitrary number of minimum frames 37 corresponding to the amount of information to be transmitted, and is repeatedly transmitted within the range of the transmittable time.

The transmission period of the minimum frame 37 is about 1 ms. Therefore, for example, when one downlink information 36 is constituted by three minimum frames 37, the transmission period of the downlink information 36 is about 3 ms. Therefore, the downlink information 36 has a predetermined transmittable time (250 ms). ) Will be repeatedly transmitted about 80 times during this period.
The in-vehicle computer 26 of the in-vehicle device 2 recognizes the downlink switching in the optical beacon 4 at the time of receiving the second downlink information 36 (F10 in FIG. 7), and transmits the uplink information 35 at this time. Stop.

As shown in FIG. 3, the road-to-vehicle communication system according to the present embodiment recognizes distances L1 to L4 from a plurality of reference positions P1 to P4 included in the communication area A to a predetermined position P0 on the downstream side, thereby positioning. (F11 in FIG. 7), and based on this, it functions as a distance recognition system that provides safe driving support to the driver.
Hereinafter, the content of the distance information described above and distance recognition for safe driving support performed by the vehicle-mounted device 2 based on the content will be described.

[Contents of distance information]
In the beacon controller 7 of the present embodiment, each of the numerical values in the distances L1 to L4 (see FIG. 3) from the respective reference positions P1 to P4 in the communication area A to the predetermined position P0 on the downstream side thereof. The distance information is stored in the storage device 48 in advance.
As shown in FIG. 3, the predetermined position P <b> 0 that is the downstream end of the distances L <b> 1 to L <b> 4 is set, for example, at the position of the stop line 40 that is installed on the downstream side of the optical beacon 4.

Further, four reference positions P1 to P4 that are upstream ends of the distances L1 to L4 are set as reference positions in the vehicle traveling direction of the divided areas UA1 to UA4, respectively, and are set to predetermined positions in the divided areas UA1 to UA4, respectively. Is set.
In each of the divided areas UA1 to UA4, a reference position is also set for an overlapping area located at the boundary between adjacent divided areas, but the description thereof is omitted in FIG.

  The control unit 49 of the beacon controller 7 selects any one of the plurality of distances L1 to L4 and stores it in the transmission frame of the second downlink information 36. Which distance L1 to L4 is selected as the distance information is determined based on the determination result of the light reception determination of the photodiode (or the transmission position of the in-vehicle device 2 when the uplink light UO is transmitted) before switching the downlink. Determined based on the region).

The beacon controller 7 stores the distance information about the distances L1 to L4 in the transmission frame of the second downlink information 36, and repeatedly transmits the frame from the beacon head 8.
For example, as shown in FIG. 3, when the beacon head 8 receives the uplink light UO (solid arrow in FIG. 3) transmitted by the vehicle-mounted device 2 in the uppermost divided area UA4, the beacon controller 7 The light receiving photodiode that has received the link light UO is specified as the photodiode PD4, and the uplink information 35 is acquired from the uplink light UO. Further, the beacon controller 7 selects the distance L4 corresponding to the divided area UA4 as the distance information, switches the downlink, and transmits the distance information to the in-vehicle device 2 via the light projecting unit 10. Send.

The beacon controller 7 also identifies the photodiodes PD1 to PD3 as light receiving photodiodes similarly to the above when the in-vehicle device 2 receives the uplink light UO transmitted in the other divided areas UA1 to UA3, respectively. The distances L1 to L3 corresponding to the divided areas are selected, and the second downlink information 36 including the distance information about the distances L1 to L3 is transmitted to the in-vehicle device 2 via the light projecting unit 10.
Thus, the beacon controller 7 specifies the distance information according to the photodiode specified as the light receiving photodiode (or the divided area specified as the transmission position of the vehicle-mounted device 2 when transmitting the uplink light UO). The distance information is included in the downlink information 36 and also has a function as a control unit for switching the downlink.

[Contents of safe driving support]
As shown in FIG. 4, when the in-vehicle head 27 receives the second downlink information 36 including the distance information, the distance recognition unit 30 of the in-vehicle computer 26 includes the distance included in the frame of the downlink information 36. The information (distances L1 to L4) is recognized as the distance to the stop line 40. The support control unit 32 of the in-vehicle computer 26 performs safe driving support for the driver using the distance information recognized by the distance recognition unit 30.

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

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

Further, the support control unit 32 can also perform safe driving support using signal information included in the second downlink information 36.
Here, the signal information refers to information related to the current or future signal lamp color displayed by the traffic signal device, and includes information (display schedule information) regarding the display continuation period of each signal lamp color, the display order, and the like. For example, “the current lamp color is blue and the scheduled duration is 5 seconds, the next lamp color is yellow and the scheduled duration is 8 seconds, and the next lamp color is a right turn blue arrow lamp and the scheduled duration is 10 seconds. It is information such as “second”.

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

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

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

The signal information may be only the currently displayed lamp color and its duration, or information for one cycle may be provided collectively. Further, in addition to these pieces of information, parameter information related to the control, information on a time zone in which the control is performed, and the like may be included at the point where the point sensitive control is performed.
The signal information may be acquired from an optical beacon or may be acquired from an infrastructure device other than the optical beacon.

  In the latter case, for example, when the signal controller of the traffic signal is equipped with a wireless communication device, it may be acquired from the wireless communication device, or may be acquired by inter-vehicle communication from the preceding vehicle that acquired the signal information. Also good. The signal information receiving unit that receives the signal information may use the in-vehicle head 27 or may be another receiver provided in the in-vehicle device 2.

As described above in detail, according to the road-to-vehicle communication system of the present embodiment, the control unit 49 determines that the determination unit 50 includes only one photodiode among the plurality of photodiodes PD1 to PD4 or two adjacent photodiodes. When it is determined that light reception is recognized only by the diode, that is, when it can be determined that one uplink light UO is received, and the photodiode receiving the uplink light UO can be accurately identified. The beacon head 8 is caused to transmit the downlink light DO including the position information specified by the position specifying unit 51.
For this reason, the optical beacon 4 can transmit only the positional information related to the transmission position accurately positioned by receiving one uplink light UO to the in-vehicle device 2, and information with high accuracy regarding the position of the vehicle. Can be provided.

  In this embodiment, when it is determined from the determination result of the determination unit 50 that a reception error has occurred, that is, two photodiodes arranged at positions not adjacent to each other among the plurality of photodiodes PD1 to PD4. If it is determined that a light reception error has occurred by determining that light reception is recognized by the diode, the beacon head 8 receives at least two or more lights, and thus which photodiode receives the uplink light UO. Whether the light is received cannot be specified, and the position specifying unit 51 cannot specify the position with high accuracy.

In this regard, the control unit 49 cannot accurately determine the position when the determination unit 50 determines that light reception is recognized in two photodiodes arranged at positions not adjacent to each other (FIG. 7). F6), the information obtained from the received uplink information is discarded and the transmission of the first downlink information 34 is continued (F7 in FIG. 7), so that the position information with low accuracy is transmitted to the in-vehicle device. Can be prevented.
Then, the control unit 49 repeats the processes of F4 to F7 in FIG. 7 until it is determined that no light reception error has occurred, thereby transmitting only the position information accurately located to the in-vehicle device 2. can do.

  Further, in the present embodiment, when causing the in-vehicle device 2 to recognize the distance information, any one of the distances L1 to L4 from each of the reference positions P1 to P4 to the predetermined position P0 is selected and the second downlink information 36 is selected. For example, both the distance L0 from the predetermined position P0 to the upstream end c and the distances ΔL1 to ΔL4 from the upstream end c to the reference positions P1 to P4 are stored in the optical beacon in advance. A method is adopted in which any one of the distances ΔL1 to ΔL4 and the distance L0 are transmitted to the in-vehicle device and the distance to the predetermined position P0 is recognized by taking the difference between the two on the in-vehicle device 2 side. You can also.

[Second Embodiment]
FIG. 8 is a conceptual diagram showing a road-to-vehicle communication procedure and data contents in the road-to-vehicle communication system according to the second embodiment of the present invention.
In this embodiment, if the uplink light UO is received (F4 in FIG. 8), the control unit 49 performs the second down regardless of whether or not a light reception error has occurred in the light reception error determination (F5 in FIG. 8). This is different from the first embodiment in that transmission of link information 36 is started (F8 in FIG. 7). The other points are the same as those in the first embodiment, and a description thereof will be omitted.

In FIG. 8, when it is determined that a light reception error has not occurred (F6 in FIG. 8), the control unit 49 of the present embodiment uses the uplink region based on the transmission position specified by the position specifying unit 51 as support information. Downlink information including distance information related to the distance from the UA to a predetermined position on the downstream side (for example, a stop line) is generated (F71 in FIG. 8), and the downlink information 36 (downlink light) is directed toward the vehicle-mounted device 2. (DO) transmission is started (F8 in FIG. 8).
On the other hand, when it is determined that a light reception error has occurred (F6 in FIG. 8), the control unit 49 generates downlink information that does not include the distance information (F72 in FIG. 8), toward the vehicle-mounted device 2. Transmission of the downlink information 36 is started (F8 in FIG. 8).
In addition, as a specific example of the “downlink information not including distance information”, information that does not indicate a specific distance such as “indefinite” is included instead of the distance information related to the predetermined position. For example, downlink information is generated.

In this embodiment, when it is determined that a light reception error has occurred, that is, the determination unit 50 determines that light reception is recognized in two photodiodes arranged at positions that are not adjacent to each other, thereby specifying the position. When it cannot be performed with high accuracy (F6 in FIG. 7), the control unit 49 causes the beacon head 8 to transmit the downlink light DO that does not include the distance information, and therefore transmits position information with low accuracy to the in-vehicle device 2. Can be prevented.
As a result, it is possible to transmit only the position information whose position is accurately identified to the in-vehicle device 2.

  In the present embodiment, the distance information may not be transmitted to the in-vehicle device 2 depending on the determination result. However, since transmission of the downlink information 36 is started regardless of the result of the light reception error determination, for example, other than the distance information For example, traffic information transmitted from the central device 3 via the communication unit 6 can be transmitted to the in-vehicle device 2.

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

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

Also, the information transmitted by the optical beacon 4 is not the value of the distance itself, but the absolute position (latitude / longitude or a coordinate value in a three-dimensional space with an arbitrary point in outer space as the origin). Etc.).
For example, the distance information includes position information regarding the reference positions P1 to P4 in the uplink area UA, position information of the predetermined position P0, and the transmission position of the uplink optical UO obtained by the position specifying unit 50. Based on the absolute position, the distance recognition unit 30 of the in-vehicle device 2 may calculate the distance by itself.

In this case, when the absolute position of the predetermined position P0 is stored on the in-vehicle device 2 side, it is sufficient to transmit only the reference positions P1 to P4 and the transmission position of the uplink optical UO from the optical beacon 4 side.
Further, the road shape information and detailed map information indicating the shape of the road including the point of the predetermined position P0, and the position on the road or the map and corresponding to the position in the uplink area UA obtained by the present invention A method in which the optical beacon 4 transmits information and the in-vehicle device 2 acquires the distance to the predetermined position P0 based on this information may be used.

In this case, road shape information and map information may be stored in the in-vehicle device 2 in advance, or may be transmitted to the in-vehicle device 2 by wireless communication other than the optical beacon 4.
Furthermore, each function part 30 and 32 of the vehicle-mounted computer 26 can also be incorporated in the electronic control unit (ECU) of the vehicle C.
In each of the above embodiments, the communication area A (particularly, the uplink area UA) has been described as being wider than the “near infrared interface standard” of an optical beacon, but the communication area A conforms to the standard. It may be set to a dimension.

  With respect to the present invention, the embodiments disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is not meant to be described above, but is intended to include all modifications within the meaning and scope equivalent to the scope of the claims.

1 Traffic control system (road-to-vehicle communication system)
2 In-vehicle device 4 Optical beacon 7 Beacon controller 8 Beacon head (projector / receiver)
DESCRIPTION OF SYMBOLS 9 Light-receiving part 10 Light projection part 34 1st downlink information 35 Uplink information 36 2nd downlink information 45 Processor 48 Memory | storage part 49 Control part 50 Determination part 51 Location specific part A Communication area C Vehicle R Road UA Up Link area UA1-UA4 Divided area UO Uplink light

Claims (7)

An in-vehicle device of a vehicle traveling on a road, and an optical beacon having a light-receiving / receiving device in which a communication area is set in a predetermined range of the road, wherein the in-vehicle device and the light-beacon of the optical beacon in the communication region Road-to-vehicle communication system that performs two-way communication with optical signals between,
In the vehicle traveling direction so as to be able to receive the uplink light corresponding to a plurality of divided areas formed by dividing the uplink area included in the communication area in the vehicle traveling direction. A plurality of light receiving units arranged side by side along the corresponding direction;
A determination unit that determines whether or not light reception is recognized in each of the plurality of light receiving units based on a light reception level output by each of the plurality of light receiving units;
Based on the determination result of the determination unit, a position specifying unit that specifies the transmission position of the uplink light of the in-vehicle device in the uplink region;
Position information related to the transmission position specified by the position specifying unit when the determining unit determines that light is received only in one light receiving unit or in two adjacent light receiving units among the plurality of light receiving units. A road-to-vehicle communication system, comprising: a control unit that transmits downlink light including: to the projector / receiver.   When the determination unit determines that light reception is recognized only in one light receiving unit or only two light receiving units adjacent to each other among the plurality of light receiving units, the position specifying unit specifies the In addition to the positional information related to the transmission position, the vehicle ID included in the received uplink light and the downlink light including traffic information are transmitted to the light projecting / receiving device, and the determination unit is the plurality of light receiving units, When it is determined that light reception is recognized at two light receiving units arranged at positions not adjacent to each other, the light emitting / receiving the downlink light including the vehicle ID and the traffic information, which is information other than the position information The road-to-vehicle communication system according to claim 1, wherein the road-to-vehicle communication system is transmitted to a device.   The control unit is obtained from the received uplink light when the determination unit determines that light reception is recognized in two light receiving units arranged at positions not adjacent to each other among the plurality of light receiving units. The road-vehicle communication system according to claim 1, wherein the information is discarded.   When the determination unit determines that light reception is recognized in two light receiving units arranged at positions not adjacent to each other among the plurality of light receiving units, the downlink does not include the position information. The road-to-vehicle communication system according to claim 1, wherein light is transmitted to the light projector / receiver. When it is determined that light reception is recognized in two light receiving units adjacent to each other, the position specifying unit divides the uplink light transmission position of the in-vehicle device into two divisions corresponding to the two light receiving units adjacent to each other The road-to-vehicle communication system according to any one of claims 1 to 4 , wherein the road-to-vehicle communication system is specified as a boundary portion of a region.   An optical beacon having a light emitter / receiver that sets a communication area within a predetermined range of a road and performs bidirectional communication with an on-vehicle device using an optical signal,
  In the vehicle traveling direction so as to be able to receive the uplink light corresponding to a plurality of divided areas formed by dividing the uplink area included in the communication area in the vehicle traveling direction. A plurality of light receiving units arranged side by side along the corresponding direction;
  A determination unit that determines whether or not light reception is recognized in each of the plurality of light receiving units, based on a light reception level output by each of the plurality of light receiving units;
  Based on the determination result of the determination unit, a position specifying unit that specifies the transmission position of the uplink light of the in-vehicle device in the uplink region;
  Position information related to the transmission position specified by the position specifying unit when the determining unit determines that light is received only in one light receiving unit or in two adjacent light receiving units among the plurality of light receiving units. An optical beacon, comprising: a control unit that transmits downlink light including: to the projector / receiver.   When the determination unit determines that light reception is recognized only in one light receiving unit or only two light receiving units adjacent to each other among the plurality of light receiving units, the position specifying unit specifies the In addition to the positional information related to the transmission position, the vehicle ID included in the received uplink light and the downlink light including traffic information are transmitted to the light projecting / receiving device, and the determination unit is the plurality of light receiving units, When it is determined that light reception is recognized at two light receiving units arranged at positions not adjacent to each other, the light emitting / receiving the downlink light including the vehicle ID and the traffic information, which is information other than the position information The optical beacon according to claim 6, which is transmitted to a device.

Images