JP5471218B2 - Road-to-vehicle communication system and in-vehicle device - Google Patents

Description

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

As a traffic information service using a road-to-vehicle communication system, so-called VICS (Vehicle Information and Communication System) using optical beacons, radio wave beacons or FM multiplex broadcasting has already been developed. Among these, the optical beacon employs optical communication using near infrared rays as a communication medium, and enables two-way communication with the in-vehicle device.
Specifically, uplink information including a vehicle ID for identifying a vehicle is transmitted from the in-vehicle device to the infrastructure-side optical beacon, and conversely includes traffic jam information, section travel time information, lane notification information, and the like. Downlink information is transmitted from the optical beacon to the in-vehicle device.

  The optical beacon is disposed on a road and includes a light emitter / receiver that performs bidirectional communication with an in-vehicle device. From this light emitter / receiver, lane notification information ( The first downlink information including the vehicle ID and the lane number is constantly transmitted to the downlink region of the road at a predetermined transmission cycle. When the vehicle passes through the downlink area, the in-vehicle device mounted on the vehicle receives the first downlink information, and the in-vehicle device starts transmitting uplink information storing its own vehicle ID.

  When the optical beacon receives the uplink information, the optical beacon starts to transmit the second downlink information including the vehicle ID to the in-vehicle device, and can transmit the second downlink information within a predetermined time. Repeat as long as possible. When confirming that the vehicle ID is stored in the second downlink information, the in-vehicle device recognizes that the second downlink information is transmitted to itself, and Necessary information can be obtained from the downlink information. The in-vehicle device repeatedly transmits the uplink information until it is confirmed that its own vehicle ID is stored in the second downlink information.

  For example, as shown in FIG. 9, in the optical beacon projector / receiver 104, a communication area A is set on the upstream side of the light beacon. According to the “near-infrared interface standard” of an optical beacon (optical vehicle detector), the uplink area UA that receives uplink information from the vehicle-mounted device 102 mounted on the vehicle C is connected as shown in FIG. It is set in the upstream portion of the area A in the vehicle traveling direction, and the downlink area DA is set to coincide with the entire communication area A. Accordingly, the upstream end c of the uplink area UA coincides with the upstream end of the downlink area DA, and the uplink area UA is set to overlap with the upstream portion of the downlink area DA. Therefore, the vehicle traveling direction length of the downlink area DA matches the same direction length of the entire communication area A.

  In the road-to-vehicle communication system using the above-mentioned conventional optical beacon, the vehicle is controlled so that the vehicle-mounted device 102 performs its own location using two-way communication and is forcibly stopped before the stop line. There is a case where a driver is given a safety driving support by giving a notification to stop or decelerate. For example, in FIG. 9, a specific position P in the communication area A (for example, approximately the center of the uplink area UA) is regarded as a vehicle position, and a predetermined position P0 (for example, downstream of the communication area A from the specific position) The distance information (distance L0) to the stop line 40) is included in the second downlink information. And the system which makes the vehicle equipment 102 receive the 2nd downlink information containing this distance L0 and makes the vehicle equipment 102 recognize about the distance L0 to the predetermined position P0 ahead of a vehicle advancing direction is proposed (for example, patent documents) 1).

JP 2007-293660 A

  In the road-to-vehicle communication system, the optical beacon repeatedly transmits the second downlink information after receiving the uplink information, but the in-vehicle device 2 transmits the second downlink information repeatedly transmitted a predetermined number of times. May end the reception. In this case, the vehicle equipped with the vehicle-mounted device 2 travels forward from when the optical beacon transmits the first second downlink information until the vehicle-mounted device 102 finishes receiving the second downlink information. Will be.

  For this reason, when the in-vehicle device 102 receives the second downlink information and acquires the distance information, the distance information includes an error caused by the vehicle traveling before the second downlink information is received. In some cases, the distance to the predetermined position ahead of the vehicle traveling direction cannot be obtained with high accuracy.

  This invention is made | formed in view of such a situation, and it aims at providing the road-to-vehicle communication system and vehicle equipment which can obtain | require accurately the distance to the predetermined position ahead of a vehicle advancing direction.

  (1) The present invention relates to an in-vehicle device that transmits uplink information in a communication area set in a predetermined range on a road, and predetermined transmission of predetermined downlink information after receiving the uplink information in the communication area. An optical beacon that repeatedly transmits to the in-vehicle device in a cycle, wherein the optical beacon includes total distance information about a distance from the communication area to a predetermined position ahead in the vehicle traveling direction. A beacon controller that stores in the predetermined downlink information composed of a plurality of transmission frames having a predetermined number of frames, the in-vehicle device, based on the total number of frames and the traveling speed of the vehicle, A correction distance calculation unit that obtains a correction distance for the distance information according to travel of the vehicle while receiving predetermined downlink information. It is.

  According to the road-to-vehicle communication system configured as described above, the correction distance calculation unit obtains a correction distance according to the traveling of the vehicle while receiving predetermined downlink information based on the total number of frames and the traveling speed of the vehicle. Therefore, an error caused by the vehicle traveling between the start of transmission of predetermined downlink information in response to reception of uplink information and the end of reception of the predetermined downlink information by the vehicle-mounted device is distance information. Can be corrected by the correction distance, and as a result, the distance to a predetermined position ahead in the vehicle traveling direction can be obtained with high accuracy.

(2) In the road-to-vehicle communication system, if the predetermined downlink information is transmitted twice from the optical beacon, the in-vehicle device transmits the predetermined downlink information with a probability of approximately 95% or more according to the standard. All of the stored transmission frames can be received.
For this reason, the correction distance calculation unit may obtain the distance traveled by the vehicle as the correction distance while the predetermined downlink information is transmitted twice.
(3) Furthermore, if the predetermined downlink information is transmitted once from the optical beacon, the in-vehicle device has all of the plurality of transmission frames storing the predetermined downlink information with a probability of 75% or more according to the standard. Can be received.
Therefore, when the probability is acceptable, the correction distance calculation unit may obtain the distance traveled by the vehicle while the predetermined downlink information is transmitted once as the correction distance.

(4) Since one predetermined downlink information is stored and transmitted in a plurality of transmission frames whose total number of frames is a predetermined number, one predetermined downlink information is determined from the transmission interval of the transmission frames and the total number of frames. The unit correction distance traveled by the vehicle while one predetermined downlink information is transmitted can be obtained by considering the traveling speed of the vehicle at that time. It is done.
Accordingly, the correction distance calculation unit obtains a unit correction distance that the vehicle travels while one predetermined downlink information is transmitted from the total frame number and the traveling speed, and corresponds to the total frame. The required number of transmissions of the predetermined downlink information necessary for receiving all the transmission frames can be obtained, and the correction distance can be obtained based on the unit correction distance and the necessary number of transmissions.

(5) The required number of transmissions is preferably determined based on the communication quality of the predetermined downlink information.
(6) Furthermore, when the reception probability for each transmission frame is obtained from the communication quality, the probability that all transmission frames corresponding to the total number of frames can be received can be obtained.
For this reason, the corrected distance calculation unit obtains all the transmission frames corresponding to the total number of frames corresponding to the number of transmissions when the predetermined downlink information is repeatedly transmitted, which is obtained from the communication quality. It is preferable that the required number of transmissions is determined based on a reception probability indicating a probability of reception.
In this case, an appropriate required number of transmissions can be set according to the reception probability of the transmission frame, and a more accurate correction distance can be obtained. As a result, the distance to a predetermined position ahead in the vehicle traveling direction can be obtained with higher accuracy.

  (7) (8) Specifically, the communication quality may be a bit error rate at the time of reception of the transmission frame, or may be a reception level of the received predetermined downlink information, By using these, the required number of transmissions can be suitably obtained.

(9) Further, the in-vehicle device is provided so as to receive the predetermined downlink information from the optical beacon through the wiped member of the vehicle to be wiped by a wiper device provided in the vehicle. If the wiped member is wiped by the operation of the wiper device, the predetermined downlink information may be prevented from reaching the in-vehicle device, and the correction distance calculation by the correction distance calculation unit may not be accurately performed. There is.
For this reason, when the operation of the wiper device is detected, the correction distance calculation unit preferably uses a preset alternative value instead of the calculated correction distance as the correction distance.
Thereby, even if the correction distance cannot be calculated with high accuracy by the operation of the wiper device, it is possible to prevent the correction distance that cannot be calculated with high accuracy from being used for correcting the distance information.

(10) In addition, the roadside communication device receives uplink information transmitted by another vehicle-mounted device mounted on a vehicle other than the vehicle, thereby transmitting downlink information that has been transmitted so far. When stopping and switching to predetermined downlink information according to the other in-vehicle device and starting transmission, the in-vehicle device has no continuity with the predetermined downlink information for the self received so far, Since a transmission frame storing predetermined downlink information corresponding to another vehicle-mounted device is received, there is a possibility that calculation of the correction distance by the correction distance calculation unit cannot be performed with high accuracy.
Therefore, when the correction distance calculation unit detects that the predetermined downlink information has been switched corresponding to another vehicle-mounted device other than itself when receiving the predetermined downlink information, It is preferable that an alternative value set in advance instead of the correction distance is used as the correction distance.
As a result, even if the calculation of the correction distance cannot be performed accurately by transmitting predetermined downlink information according to other in-vehicle devices, the correction distance that cannot be calculated accurately is used for correcting the distance information. Can be prevented.

  (11) Further, the present invention transmits uplink information in a communication area set in a predetermined range on a road, and is repeatedly transmitted at a predetermined transmission cycle from an optical beacon that has received the uplink information. An in-vehicle device that receives downlink information, wherein the predetermined downlink information is composed of a plurality of transmission frames having a predetermined total number of frames, and from the communication area to a predetermined position ahead in the vehicle traveling direction. Correction for the distance information according to the travel of the vehicle while receiving the predetermined downlink information based on the total number of frames and the travel speed of the vehicle. It is characterized by having a corrected distance calculation unit for obtaining the distance.

  According to the vehicle-mounted device having the above configuration, as described above, even if an error occurs due to the vehicle traveling before the downlink information is received, the distance to a predetermined position in the vehicle traveling direction is accurately determined. Can be sought.

  As described above, according to the road-to-vehicle communication system and the in-vehicle device of the present invention, the distance to a predetermined position ahead of the vehicle traveling direction can be obtained with high accuracy.

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 A of an optical beacon. It is a schematic block diagram of the vehicle carrying the optical beacon and the vehicle equipment which carries out road-to-vehicle communication with this. It is a figure which shows the procedure of the two-way road-to-vehicle communication performed between the beacon head of an optical beacon and the vehicle-mounted head of vehicle equipment in a communication area. It is a figure which shows an example of the aspect of the 2nd downlink information transmitted repeatedly from an optical beacon after switching. It is a block diagram which shows the whole structure of 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 optical beacon by 2nd embodiment. It is a side view which shows the communication area | region of the conventional optical beacon.

Next, preferred embodiments of the present invention will be described with reference to the accompanying drawings.
[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 optical beacons (optical vehicle detectors) 4 installed in many places on the road R. The optical beacon 4 performs bidirectional communication with the in-vehicle device 2 by optical communication using near infrared rays as a communication medium. The central device 3 is provided in the traffic control room.

[Configuration of optical beacon]
The optical beacon 4 includes a communication unit 6 that is a communication interface connected to the central apparatus 3 via a communication line 5 such as a telephone line, a beacon controller 7 to which the communication unit 6 is connected, and the beacon controller 7. And a plurality (four in the illustrated example) of beacon heads (projector / receiver) 8 connected to the sensor interface.
Each beacon head 8 is configured by housing a light emitting diode (LED) 10 and a photosensor (reception unit) 11 inside a casing (see FIG. 3). Among them, the LED 10 emits downlink information made of near infrared rays to a communication area A described later, and the photo sensor 11 receives uplink information made of near infrared rays from the in-vehicle device 2. A downlink area DA and an uplink area UA, which will be described later, are set to a predetermined range on the road by adjusting the LED 10 and the photo sensor 11.

FIG. 2 is a plan view of the optical beacon 4.
As shown in FIG. 2, the optical beacon 4 of this embodiment is installed on a road R having a plurality of lanes R1 to R4 (four in the illustrated example) in the same direction, and corresponds to each lane R1 to R4. The plurality of beacon heads 8 provided and a single beacon controller 7 serving as a control unit that collectively controls the beacon heads 8.
The beacon controller 7 is composed of a programmable microcomputer having a CPU, a memory (RAM), and a storage device (ROM). It has a function as a communication control unit that performs road-to-vehicle communication with the machine 2. The contents of road-to-vehicle communication by the beacon controller 7 will be described later.

The beacon controller 7 is installed on a support column 13 erected on the side of the road, and each beacon head 8 is attached to an installation bar 13 installed horizontally on the road R side from the support column 12, and each lane R <b> 1 of the road R. It is arrange | positioned just above -R4.
The LED 10 of each beacon head 8 emits near-infrared rays toward the upstream side in the vehicle traveling direction rather than directly below the lanes R1 to R4, thereby performing road-to-vehicle communication with the in-vehicle device 2. Is set on the upstream side of the head 8.

[About communication area]
FIG. 3 is a side view showing the communication area A of the optical beacon 4. The vehicle C travels in the direction of the arrow in the figure. In FIG. 3, the communication area A by the optical beacon 4 is a downlink area in which an in-vehicle head 20 (see FIG. 4) of the in-vehicle apparatus 2 described later can receive downlink information (in FIG. 3, a solid line hatching is provided). Area) DA and an uplink area (area provided with broken-line hatching in FIG. 3) UA from which the beacon head 8 of the optical beacon 4 can receive uplink information.

  In the “near infrared interface standard” of the optical beacon (optical vehicle detector) 4, the uplink region overlaps the upstream portion of the downlink region in the vehicle traveling direction, and the upstream end of the downlink region and the uplink region It is defined that the upstream ends coincide with each other. For this reason, the vehicle traveling direction length of the entire communication area A coincides with the length of the downlink area in the same direction.

With respect to the above standard, the downlink area DA of the present embodiment is set to an area connecting the beacon head 8 and the position d1 and the position d2 set on the road R, and the uplink area UA is the beacon head. 8, a point d2 indicating the upstream end of the uplink area UA is set to an area connecting the position u1 and the position u2 set on the road R, and the point d2 indicating the upstream end of the downlink area DA is a point u2 indicating the upstream end of the uplink area UA It is on the upstream side (right side in FIG. 3). Further, the length of the downlink area DA in the vehicle traveling direction coincides with the length of the entire communication area A in the same direction.
For this reason, the uplink area UA is set to overlap with the downlink area DA, and the area constituted only by the downlink area DA is not only downstream of the uplink area UA but also upstream of the area UA. It also exists on the side.

[Configuration of in-vehicle device and vehicle]
FIG. 4 is a schematic configuration diagram of a vehicle C in which the optical beacon 4 and the in-vehicle device 2 that communicates with the optical beacon 4 are mounted.
As shown in FIG. 4, the vehicle C includes a vehicle body 15 having a driver's boarding seat (not shown), the above-described in-vehicle device 2 mounted on the vehicle body 15, and an electronic device that integrally controls each part of the vehicle C. A control device (ECU) 16, an engine 17 that drives the vehicle body 15, a brake device 18 that brakes the vehicle body 15, and a speed detector 19 that constantly detects the current speed of the vehicle C are provided. The ECU 16 performs various controls on the vehicle C such as drive control of the engine 17 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 head 20 installed on a dashboard (not shown) of the vehicle C, an in-vehicle computer 21 to which the in-vehicle head 20 is connected, a display 22 and a speaker as a human interface for a driver in a passenger seat. Device 23.
Similar to the beacon head 8 of an optical beacon, the in-vehicle head 20 includes a light projecting / receiving unit 20a including a light emitting diode (LED) and a photosensor, and a control unit 20b for controlling the light emitting / receiving unit 20a (see FIG. Not shown). The LED provided in the light projecting / receiving unit 20a emits uplink information made of near infrared rays, and the photo sensor receives downlink information made of near infrared rays emitted to the communication area A.
The control unit 20b exchanges information to be transmitted / received with the in-vehicle computer 21, and causes the light projecting / receiving unit 20a to transmit / receive the uplink information and the downlink information for the information. More specific functions of the light projecting / receiving unit 20a and the control unit 20b will be described in detail later.

The in-vehicle computer 21 is constituted by a microcomputer having a CPU, a memory (RAM), and a storage device (ROM), and performs control processing of road-to-vehicle communication with the optical beacon 4 by the in-vehicle head 20. The in-vehicle computer 21 is connected to the ECU 16 of the vehicle C, and can acquire necessary information regarding the vehicle C.
The in-vehicle computer 21 stores a program that executes each predetermined function in a storage device, and the frame number acquisition unit 21a, the speed acquisition unit 21b, the correction unit 21c, and the support control unit 21d are functional units that the program executes. It has.

The frame number acquisition unit 21a of the in-vehicle computer 21 has a function of acquiring the total number of transmission frames constituting the second downlink information described later. The speed acquisition unit 21b has a function of acquiring the current traveling speed of the vehicle C detected by the speed detector 19 via the ECU 16. The correction unit 21c has a function of obtaining a correction distance described later.
The support control unit 21d controls safe driving support for the driver based on the support information included in the downlink information received by the in-vehicle device 2. The functions of the frame number acquisition unit 21a, the speed acquisition unit 21b, the correction unit 21c, and the support control unit 21d will be described in detail later.

[Aspects of road-to-vehicle communication]
FIG. 5 shows a two-way road-to-vehicle communication procedure performed between the beacon head 8 of the optical beacon 4 and the in-vehicle head 20 of the in-vehicle device 2 in the communication area A. Hereinafter, this aspect of road-to-vehicle communication will be described with reference to FIG.
First, the beacon controller 7 of the optical beacon 4 sends the first downlink information 28 including the lane notification information as the first information before switching the downlink from each beacon head 8 corresponding to each lane R1 to R4. In this case, the transmission continues to the downlink area DA of each lane R1 to R4 at a predetermined transmission cycle (F1 in FIG. 5). At this stage, the vehicle ID is not yet stored in the lane notification information.

When the vehicle C equipped with the vehicle-mounted device 2 enters the upstream portion of the downlink area DA, the vehicle-mounted head 20 of the vehicle-mounted device 2 receives the first downlink information 28 including the lane notification information (no vehicle ID). At this time, the in-vehicle computer 21 of the in-vehicle device 2 recognizes that the vehicle C exists in the communication area A.
Thereafter, the in-vehicle computer 21 starts transmission of the uplink information 29 (F2 in FIG. 5), and transmits this uplink information 29 to the beacon head 8 of the optical beacon 4 at a predetermined transmission cycle (F3 in FIG. 5). ).
The in-vehicle computer 21 stores a specific vehicle ID for the vehicle C in the uplink information 29 and transmits the uplink information 29. The in-vehicle computer 21 continues to transmit the uplink information 29 until it recognizes that the beacon controller 7 of the optical beacon 4 has switched the downlink.

On the other hand, when the beacon head 8 of the optical beacon 4 receives the uplink information 29 in the uplink area UA set by itself (F4 in FIG. 5), the beacon controller 7 transmits the second information after switching the downlink. The transmission of the second downlink information 30 including the lane notification information for the in-vehicle device 2 having the vehicle ID information is started (F5 in FIG. 5), and the transmission of the downlink information 30 is performed within a predetermined time. Repeat as much as possible (F6 in FIG. 5).
The lane notification information includes a field for storing a vehicle ID for each lane R1 to R4, and a lane number can be assigned to each vehicle ID. For this reason, the in-vehicle computer 21 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 beacon controller 7 stores, in the second downlink information 30, traffic information, event regulation information, and the support information for safe driving support for the driver, in addition to the lane notification information including the vehicle ID. To send.
This support information includes the traffic signal information, which is timing information for changing the color of the traffic light downstream of the optical beacon 4, and a predetermined position downstream of the optical beacon 4 from the downlink area DA (for example, before the front intersection). Distance information that is length information to a certain stop line) is included.

  The second downlink information 30 is composed of a plurality of transmission frames 31 that are sequentially transmitted in a predetermined transmission cycle. According to the “near infrared interface standard”, the total data amount of the transmission frame 31 is defined as 128 bytes, and 5 bytes are allocated to the header portion 32 and 123 bytes are allocated to the actual data portion 33.

  According to the standard, the second downlink information 30 can be composed of 1 to 80 transmission frames 31, and the transmission possible time is set to 250 ms. The downlink information 30 is composed of an arbitrary number of transmission frames 31 corresponding to the amount of information to be transmitted, and is repeatedly transmitted within the transmission available time range. The transmission cycle of the transmission frame 31 is about 1 ms.

  The in-vehicle device 2 recognizes the switching of the downlink in the optical beacon 4 at the time of receiving the second downlink information 30 (F7 in FIG. 5), and stops transmitting the uplink information 29 at this time.

  The in-vehicle device 2 can acquire the distance information stored in the second downlink information 30 by receiving the second downlink information 30, and as shown in FIG. The position is determined by recognizing the distance to (F8 in FIG. 5). Furthermore, safe driving support for the driver is performed using the recognized distance to the predetermined position P0.

Here, details of reception of the second downlink information 30 by the in-vehicle device 2 will be described.
FIG. 6 is a diagram illustrating an example of the second downlink information 30 that is repeatedly transmitted from the optical beacon 4 after switching.
The optical beacon 4 repeatedly transmits the second downlink information 30 after the downlink switching using a plurality of transmission frames 31 set at a predetermined transmission interval.
Specifically, the beacon controller 7 of the optical beacon 4 stores various information such as the distance information in the second downlink information 30 including a plurality of transmission frames 31 having a total number of frames. The beacon controller 7 determines the total number of frames necessary for transmitting the second downlink information 30 according to the information amount of the second downlink information 30 when switching the downlink. Then, the beacon controller 7 divides the second downlink information 30 to be transmitted by the determined total number of frames, and stores the divided information in the actual data part 33 of the transmission frame 31, respectively. The second downlink information 30 is configured by the transmission frames 31 corresponding to the determined total number of frames.
In this way, the optical beacon 4 repeatedly transmits the second downlink information 30 including the plurality of transmission frames 31.

  The header portion 32 of each transmission frame 31 includes a transmission frame 31 transmitted first from a plurality of transmission frames 31 constituting the second downlink information 30 to a transmission frame 31 transmitted last. The frame numbers assigned in order are stored, and in the header part 32 of the transmission frame 31 transmitted last, the transmission frame 31 includes a plurality of pieces constituting one second downlink information 30. The information (last information) indicating that it is the last transmission frame 31 of the transmission frames 31 is stored.

  FIG. 6 shows a case where the second downlink information 30 is transmitted by 15 transmission frames. In this case, the beacon controller 7 determines the total number of frames as “15”, generates 15 division information by dividing the second downlink information 30, and sets each of the 15 pieces of division information to 15. Stored in one transmission frame 31. The optical beacon 4 repeatedly transmits the second downlink information 30 composed of 15 transmission frames 31 each storing division information.

The in-vehicle device 2 acquires the second downlink information 30 by receiving all the 15 transmission frames 31 constituting the second downlink information 30.
Referring also to FIG. 3, specifically, as described above, the in-vehicle head 20 of the in-vehicle device 2 receives the transmission frame 31 transmitted from the optical beacon 4 by the light projecting / receiving unit 20 a. When receiving the transmission frame 31 from the optical beacon 4, the light projecting / receiving unit 20 a gives the received signal to the control unit 20 b of the in-vehicle head 20.

The control unit 20b acquires the information stored in the header part 32 and the actual data part 33 of the transmission frame 31 from the given received signal, and stores the acquired information (frame information) in its own storage unit. Store. At this time, the control unit 20b refers to the frame number stored in the header unit 32 and the information (last frame information) indicating the last transmission frame 31 included in the acquired frame information. The control unit 20b can grasp the total number of frames of the second downlink information 30 that is currently received by recognizing the frame number of the transmission frame including the last frame information.
Further, the control unit 20b refers to the frame number of the acquired frame information, and confirms whether or not there is frame information including the same frame number in the frame information already stored in its own storage unit. When frame information including the same frame number is already stored, the control unit 20b does not store the acquired frame information in the storage unit.

  As described above, the control unit 20b performs processing on the reception signal of the transmission frame 31 that is sequentially received by the light projecting / receiving unit 20a. Then, the frame number of the frame information stored in the storage unit is confirmed, and when the frame information including all the frame numbers up to the total number of frames is recognized, the control unit 20b reads the second downlink information 30. It is determined that the reception of all the transmission frames 31 corresponding to the total frames constituting is completed.

Here, in the optical communication between the optical beacon 4 and the in-vehicle head 20, when the in-vehicle head 20 receives the transmission frame 31 from the optical beacon 4, the probability is constant regardless of the conditions such as the communication environment. Since a reception error occurs, for example, it is not possible to receive all of the 15 transmission frames 31 constituting the second downlink information 30 by the transmission of the second downlink information 30 for the first time of repeated transmission immediately after switching. There is a case.
As described above, the control unit 20b of the in-vehicle head 20 corresponds to the total frames constituting the second downlink information 30 until it is recognized that all the frame information obtained from the reception signals from the light projecting / receiving unit 20a is complete. It is not determined that all the transmission frames 31 have been received. For this reason, when all (15) transmission frames 31 cannot be received in the transmission of the second downlink information 30 after the first repeated transmission, the second downlink information 30 after the second transmission is received. Wait for transmission. The in-vehicle head 20 can obtain the opportunity to receive the transmission frame 31 that could not be received first time by the transmission of the second downlink information 30 after the second repeated transmission, and could not receive it. The transmission frame 31 is complementarily received.
In this way, the in-vehicle head 20 is capable of transmitting all of the total frames constituting the second downlink information 30 while the second downlink information 30 stored in the plurality of transmission frames 31 is repeatedly transmitted. The transmission frame 31 is received.

  When the control unit 20b of the in-vehicle head 20 determines that all the transmission frames 31 have been received, all the information (all frame information stored in the storage unit) included in the transmission frame 31 including information such as the header unit 32 is received. Output to the in-vehicle computer 21.

The in-vehicle computer 21 to which the frame information included in all the transmission frames 31 constituting the second downlink information 30 is given determines that the reception of the second downlink information 30 has been completed (F7 in FIG. 5). In addition, when the second downlink information 30 recognizes that its own vehicle ID is included, the transmission of the uplink information 29 by the in-vehicle head 20 is stopped.
As described above, the in-vehicle device 2 according to the present embodiment has the second downlink when the in-vehicle head 20 receives all the transmission frames 31 and outputs the received information to the in-vehicle computer. It is determined that the reception of information 30 has been completed.

In the road-to-vehicle communication system according to the present embodiment, the vehicle-mounted device 2 that has finished receiving the second downlink information 30 as described above recognizes the distance from the communication area A to the predetermined position P0 on the downstream side. It functions as a distance recognition system that performs orientation (F8 in FIG. 5) and provides safe driving support for the driver based on this.
Hereinafter, the aspect of distance recognition for safe driving support performed by the in-vehicle device 2 will be described.

[Distance recognition mode]
The beacon controller 7 of the optical beacon 4 stores the distance information including the numerical value of the distance L1 from the predetermined position P1 in the communication area A to the predetermined position P0 on the downstream side in advance in a storage device. Then, the distance information about the distance L1 is stored in the second downlink information 30 and transmitted.
Referring to FIG. 3, the predetermined position P0 that is the downstream end (end point) of the distance L1 is set at the position of the stop line 40 that is installed on the downstream side of the optical beacon 4, for example, before the traffic light. Further, the predetermined position P1, which is the upstream end (starting point) of the distance L1, is set, for example, at a substantially central position in the vehicle traveling direction on the road R in the uplink area UA.

  The in-vehicle computer 21 acquires the distance information included in the received second downlink information 30, and recognizes the distance L1. And the assistance control part 21d of the vehicle-mounted computer 21 performs the safe driving assistance with respect to a driver using the distance L1.

  In this embodiment, the position of the vehicle-mounted device 2 (vehicle C) when the optical beacon 4 that has received the uplink information 30 starts transmission of the first second downlink information 30 after switching is the uplink area UA. The in-vehicle device 2 is made to recognize the distance L1 to the predetermined position P0 on the downstream side at that time.

  Here, as shown in FIG. 3, the in-vehicle device 2 starts from the transmission of the first second downlink information 30 after switching until it actually finishes receiving the second downlink information 30. , Need a certain time. Therefore, the in-vehicle device 2 finishes receiving the second downlink information 30 in the distance information stored in the second downlink information 30 acquired by finishing the reception of the second downlink information 30. Therefore, an error due to the vehicle C moving forward is included during the time required for this.

The in-vehicle device 2 of the present embodiment obtains the time necessary for the self to finish receiving the second downlink information 30, further obtains the error as a distance from the time, and by the obtained distance (correction distance), It has a function of correcting distance information (distance L1).
Hereinafter, the correction of distance information will be described.

Referring to FIG. 3, when it is determined that the reception of the second downlink information 30 is completed, the in-vehicle computer 21 transmits the transmission frame 31 constituting the second downlink information 30 to the frame number acquisition unit 21 a. While acquiring the total number of frames, the speed acquisition unit 21b is caused to acquire the current traveling speed of the vehicle C from the ECU 16.
The frame number acquisition unit 21a acquires the total number of frames by referring to information (frame number, last information) stored in the header unit 32 output from the in-vehicle head 20 together with the second downlink information 30. can do.
Further, the in-vehicle computer 21 causes the correction unit 21c to acquire the distance information included in the received second downlink information 30, and the total frames acquired by the frame number acquisition unit 21a and the speed acquisition unit 21b. Based on the number and the traveling speed, a correction distance for correcting the distance information is calculated, and the distance information is corrected.

  The correction unit 21c calculates the correction distance as follows. That is, since the second downlink information 30 is transmitted by a plurality of transmission frames 31 set in a predetermined transmission cycle as described above, it is necessary to transmit one second downlink information 30. The necessary time can be obtained by multiplying the total number of frames constituting the second downlink information 30 by the transmission period of the transmission frame 31.

Specifically, referring to FIG. 6, in the illustrated example, the second downlink information 30 has a total number of frames of “15” and is transmitted by 15 transmission frames 31.
Since the transmission cycle of the transmission frame 31 is about 1 millisecond, the time required to transmit the 15 transmission frames 31 sequentially, that is, the time required to transmit one second downlink information 30 is , About 15 milliseconds.

Furthermore, if the vehicle C is traveling at a speed of 70 km / h, for example, the traveling distance therebetween is approximately 0.32 m.
That is, if the transmission period of the transmission frame and the total number of transmission frames constituting the second downlink information 30 are recognized, the time required to transmit one second downlink information 30 Further, by considering the traveling speed of the vehicle C, the traveling distance (unit correction distance) that the vehicle C travels during that time can be determined.

Here, as described above, in the optical communication between the optical beacon 4 and the in-vehicle head 20, when the in-vehicle head 20 receives the transmission frame 31 from the optical beacon 4, regardless of the conditions such as the communication environment. A reception error occurs with a certain probability. For this reason, in the first transmission of the second downlink information 30 (the number of repeated transmissions) after the switching, all of the 15 transmission frames 31 constituting the second downlink information 30 may not be received. Yes, in this case, the in-vehicle head 20 interpolates the transmission frame 31 that could not be received by the transmission of the second downlink information 30 after the second repeated transmission in order to receive all of the transmission frames 31. Receive.
The in-vehicle head 20 receives all the transmission frames 31 corresponding to the total frames constituting the second downlink information 30 by repeatedly transmitting the second downlink information 30, and receives the received information (frame information). By outputting to the in-vehicle computer 21, the reception of the second downlink information 30 is finished.

  Therefore, in addition to the unit correction distance, the correction unit 21c includes the second downlink information 30 necessary for receiving all the transmission frames 31 corresponding to the total frames constituting the second downlink information 30. A required transmission count that is the number of repeated transmissions is obtained, and a correction distance is obtained by multiplying the unit correction distance by the required transmission frequency.

  The in-vehicle device 2 can receive all of the plurality of transmission frames 31 constituting the second downlink information 30 corresponding to the number of transmission times when the second downlink information 30 is repeatedly transmitted. It is determined based on the reception probability indicating the probability.

The reception probability is determined based on the communication quality of downlink information transmitted from the optical beacon 4. Specifically, the communication quality is the bit error rate of the transmission frame. In the optical beacon 4 of the present embodiment, the bit error rate of the transmission frame is 10 ⁻⁵ or less, and the “near infrared interface standard” It is stipulated in.
The reception probability is obtained according to the number of transmission frames necessary for transmitting one second downlink information 30 based on the bit error rate for each transmission frame.

For example, as shown in FIG. 6, when the total number of transmission frames 31 constituting the second downlink information 30 is “15”, the second downlink is the first repeat transmission count (first after switching). In the case of information 30, the reception probability is calculated as 75%. When the number of repeated transmissions is the second time, the reception probability is 95%, and when the number of repeated transmissions is the third time, the reception probability is almost 100%.
Further, since the reception probability is obtained from the bit error rate for each individual transmission frame 31, the number of transmission frames necessary for transmitting one second downlink information 30, that is, acquired by the frame number acquisition unit 21a. It changes according to the total number of frames to be performed. For example, if the total number of frames of the second downlink information 30 increases, the reception probability may decrease accordingly.

However, even if the total number of frames increases in accordance with the amount of information of the second downlink information 30, the reception probability is approximately 95% according to the standard when the number of repeated transmissions is the second. That's it. For this reason, the correction distance may be obtained by setting the required number of transmissions to “2”.
Further, as described above, even when the number of repeated transmissions is the first, the reception probability is 75% or more according to the standard.
Therefore, when the above reception probability is acceptable, the correction unit 21c may obtain the correction distance by setting the necessary number of transmissions to “1”.

In the present embodiment, for example, when the correction unit 21c is set to select, as the necessary number of transmissions, the number of repeated transmissions in which the reception probability corresponding to the number of repeated transmissions is 90% or more, the correction unit 21 selects “2” for the required number of transmissions in most cases.
Since the reception probability depends on the reception performance of the transmission frame of the in-vehicle device 2, the value of the reception probability set as a threshold for selecting the required number of transmissions can be selected as appropriate. .

As described above, the correction unit 21c calculates the unit correction distance and the necessary number of transmissions, and multiplies them to determine the correction distance.
Further, the correction unit 21c corrects the distance information by subtracting the correction distance from the distance L1 represented by the distance information acquired from the second downlink information 30, and obtains a corrected distance Lc.
The in-vehicle computer 21 performs safe driving support for the driver using the corrected distance information (distance Lc) obtained by the correction unit 21c.

[About safe driving support]
For example, the support control unit 21d reduces the distance to stop before the stop line 40 from the corrected distance Lc and the current traveling speed of the vehicle C that the correction unit 21c has obtained as the distance to the stop line 40. The speed (negative acceleration) is calculated, and the deceleration is notified to the ECU 16. The ECU 16 operates the brake device 18 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 21d may be alerting the driver using the display 22 or the speaker device 23.
For example, the distance Lc to the stop line 40 may be displayed on the display 22 by the support control unit 21d. When the current traveling speed of the vehicle C is too fast, the support control unit 21d displays a warning for stopping or decelerating on the display 22 or outputs the warning from the speaker device 23 by voice. May be.

Further, the support control unit 21d can perform safe driving support using the signal information included in the second downlink information together with the distance information (distance Lc).
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 21d of the in-vehicle computer 21 that has received this signal information estimates the time required to arrive at the stop line 40 from the corrected distance Lc to the stop line 40 and the traveling speed and acceleration of the vehicle C. Above, the signal lamp color after the said required time progress 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 21d may directly control the brake device 18 (FIG. 4) and the accelerator of the vehicle. Further, the assist control unit 21d may simply generate information on braking and speed maintenance, and notify the ECU 16 of the information to control the brake device 18 and the accelerator by the ECU 16. That is, the support control unit 21d may perform indirect control.

  In addition, the assist control unit 21d may perform not only control led by the in-vehicle device but also operation to assist the driving operation of the driver such as brake assist.

The support control unit 21d 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 23 to the driver, or displayed on the display 22 such as a head-up display or a navigation device with characters or symbols. Can do.
For safe driving support, 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 .

  As described above in detail, according to the road-to-vehicle communication system configured as described above, the correction unit 21c determines the second number based on the total number of transmission frames constituting the second downlink information 30 and the traveling speed. The correction distance according to the traveling of the vehicle C while receiving the downlink information 30 can be obtained. As a result, the vehicle C advances from when the transmission of the second downlink information 30 is started in response to the reception of the uplink information 29 until the vehicle-mounted device 2 receives the second downlink information 30. Even if an error due to this occurs in the distance information, it can be corrected by the correction distance, and the distance to the predetermined position P0 ahead in the vehicle traveling direction can be accurately obtained.

[Vehicle wipers]
In optical communication between the optical beacon 4 and the in-vehicle head 20, when the in-vehicle head 20 receives the transmission frame 31 from the optical beacon 4, a reception error occurs with a certain probability regardless of the conditions such as the communication environment. However, since the vehicle-mounted head 20 is normally disposed on the dashboard on the windshield side of the vehicle C, a reception error may be caused by operating the wiper during rainy weather.
On the other hand, when detecting the operation of the wiper, the correction unit 21c of the present embodiment is configured to correct the distance information using a preset alternative value as a correction distance instead of the calculated correction distance. .

Specifically, referring to FIG. 4, the in-vehicle head 20 is fixed on a dashboard or the like on the windshield G side, and performs optical communication with the optical beacon 4 via the windshield G. .
A wiper device W is disposed outside the windshield G. The wiper device W includes a wiper blade W1 for swinging and wiping the outer surface of the windshield G as a member to be wiped, and a drive control device W2 for driving and controlling the wiper blade W1. The drive control device W2 is connected to the ECU 16 of the vehicle C, and the ECU 16 can grasp the operation status of the wiper device W.
The correction unit 21c detects whether or not the wiper device W is operating via the ECU 16. When the correction unit 21c detects the operation of the wiper device W, the correction unit 21c uses a preset alternative value as a correction distance instead of the calculated correction distance. The distance information is corrected.

Therefore, when the wiper blade W1 swings and wipes the windshield G, reception of downlink information passing through the windshield G and reaching the in-vehicle head 20 is hindered, and the correction distance 21c is accurately calculated by the correction unit 21c. Even if there is a possibility that the correction cannot be performed, the correction unit 21c employs the alternative value as the correction distance, so that it is possible to prevent the correction distance that could not be calculated accurately from being used.
Here, the substitute value is set to the maximum distance from the predetermined position P1 in the uplink area UA to the position d1 at the downstream end of the downlink area DA. The substitute value is preferably a relatively large value among values that can be adopted as the correction distance. In this case, if the substitute value is a relatively small value, there is a high possibility that the predetermined position P0 ahead in the traveling direction is recognized as being ahead of the actual position. If set, it is highly possible that the predetermined position P0 is recognized as being upstream of the actual position (the front side of the vehicle), and it is determined whether or not to stop the predetermined position P0 or the like ahead in the traveling direction. This is because a necessary and sufficient distance can be secured.

[About switching downlink information]
In this embodiment, the downlink information 28 and 30 transmitted from the four beacon heads 8 included in the optical beacon 4 are all configured to transmit the same content. Further, when any one of the four beacon heads 8 receives the uplink information 29 from the in-vehicle device 2, the downlink information transmitted from all the beacon heads 8 is switched and a new one is generated. It is configured to transmit downlink information.

Therefore, as shown in FIG. 2, the optical beacon 4 receives the second information by receiving the uplink information transmitted from the vehicle-mounted device 2 of the vehicle C1 that has entered the uplink area of the communication area A set in the lane R2. When downlink information is transmitted to the in-vehicle device 2, the in-vehicle device 2 mounted on the vehicle C2 traveling in the lane R1 enters the uplink area of the communication area A set in the lane R1 and is uplinked. When the information is transmitted, the optical beacon 4 stops the transmission of the second downlink information that has been transmitted until then according to the uplink information from the vehicle-mounted device 2 of the vehicle C2, and the vehicle-mounted device 2 of the vehicle C2. Switch to the second downlink information for and transmit.
At this time, since the optical beacon 4 switches the downlink information transmitted in all lanes, the in-vehicle device 2 of the vehicle C1 has no continuity with the second downlink information for the self received so far. The second downlink information corresponding to the vehicle-mounted device 2 of the vehicle C2 is received.

  Here, if the in-vehicle device 2 of the vehicle C1 has not finished receiving the second downlink information, the transmission of the second downlink information that was about to be received will be canceled, so the correction of the in-vehicle device 2 The unit 21c cannot calculate the correction distance with high accuracy based on the transmission frame or the like in which the second downlink information to be received is stored.

On the other hand, when the correction unit 21c of the present embodiment receives the second downlink information 30, the second downlink information 30 is switched in correspondence with the other in-vehicle device 2 other than itself. When this is detected, an alternative value set in advance instead of the calculated correction distance is adopted as the correction distance.
Thereby, even if the calculation of the correction distance cannot be performed accurately by transmitting the second downlink information switched according to the other vehicle-mounted device 2, the correction distance that cannot be calculated accurately is the distance. It can be prevented from being used for correction of information. Note that the value of the substitute value is set based on the same standard as the substitute value adopted in accordance with the operation of the wiper device W.

  Further, in the above description, the relationship between the in-vehicle devices 2 mounted on the vehicle C traveling in different lanes has been described. However, among the plurality of vehicles C (in-vehicle devices 2) traveling in the same lane, the head When the in-vehicle device 2 traveling on the vehicle has received the second downlink information transmitted according to its own uplink information, before the first on-vehicle device 2 finishes receiving the second downlink information. The same applies to the case where the downlink information is switched to the subsequent vehicle-mounted device 2 when the subsequent vehicle-mounted device 2 enters the uplink region of the same lane.

  The in-vehicle device 2 immediately after switching whether or not the transmission of the second downlink information to itself is stopped and the transmission is switched to the second downlink information corresponding to the other in-vehicle device 2 other than itself. This can be determined by checking the number of times of switching downlink information stored in the header portion of the transmission frame in which the second downlink information is stored. That is, if the in-vehicle device 2 receives the second downlink information 30 for itself, and the second downlink information 30 is switched corresponding to the other in-vehicle device 2, the switching count is counted up. Is done. Therefore, the in-vehicle device 2 can recognize that the second downlink information 30 has been switched by confirming that the number of times of switching has been counted up.

In addition, for example, in the road-to-vehicle communication system shown in the conventional example, distance information from a specific position in the communication area A to a predetermined position on the downstream side such as a stop line in order to cause the vehicle-mounted device to perform its own position determination. In addition, transmission progress information based on the transmission time of the first second downlink information after receiving the uplink information may be included in the second downlink information for transmission.
The transmission progress information is an elapsed time from the time of transmission of the first second downlink information, and is stored and transmitted in any of a plurality of transmission frames constituting the second downlink information. .
The in-vehicle device acquires the distance information and the transmission progress information from the second downlink information that is repeatedly transmitted. Then, using the transmission progress information, an error caused by the vehicle traveling from the start of transmission of the first second downlink information to the end of reception of the second downlink information is obtained as a distance. Information can be corrected.

In the in-vehicle device, as shown in the present embodiment, the second downlink information composed of a plurality of transmission frames that are repeatedly transmitted is received, and all the necessary information for configuring the second downlink information is received. It may be configured to recognize that the reception of the second downlink information is finished when the transmission frame is received.
In this configuration, when transmission of the first second downlink information immediately after switching cannot receive all of the transmission frames constituting the second downlink information, the second downlink information is repeatedly transmitted thereafter. The transmission frame that could not be received is received by interpolation.

  Here, the receiving unit for receiving the downlink information is directly connected to the arithmetic processing unit that corrects the distance information, and recognizes the timing at which the arithmetic processing unit receives the transmission frame including the transmission progress information. If possible, the distance information can be corrected accurately based on the transmission progress information.

  However, since the receiving unit may be connected to the arithmetic processing unit included in a car navigation system or the like that is already installed in the vehicle and is already installed in the vehicle due to its configuration. Like the vehicle-mounted device 2 of the embodiment, the receiving unit (vehicle-mounted head 20) and the arithmetic processing unit (vehicle-mounted computer 21) may be configured independently. In this case, after receiving all the transmission frames in the reception unit, all the transmission frames constituting the second downlink information are arranged, and information related to all these transmission frames is output to the arithmetic processing unit. The operation processing unit completes reception of the second downlink information at a stage of acquiring information related to all transmission frames constituting the second downlink information output by the reception unit. May be configured to determine. Therefore, the arithmetic processing unit can recognize the time point when the reception of the second downlink information is completed.

  As described above, the arithmetic processing unit can recognize when the reception of the second downlink information is completed. Therefore, in the above configuration, after the optical beacon receives the uplink information, the second downlink information is received. If the in-vehicle device can recognize the reception elapsed time from the time when the vehicle is switched to the time when the in-vehicle device completes the reception of the second downlink information, the travel distance that the vehicle travels during that time can be obtained, The distance information is corrected by subtracting the travel distance from the distance information provided from the optical beacon, and the distance from the vehicle to a predetermined position on the downstream side can be obtained.

However, the transmission progress information provided to the in-vehicle device is information indicating the transmission elapsed time from the time of switching to the second downlink information to the time of transmitting the transmission frame storing the transmission progress information. The in-vehicle device may not be able to recognize the reception elapsed time.
That is, when the timing at which a frame including transmission progress information is received differs from the timing at which all the transmission frames constituting the second downlink information are received (timing at which reception of the second downlink information is completed). Therefore, the transmission elapsed time indicated by the transmission progress information and the reception elapsed time are different.
In the above case, the in-vehicle device obtains the transmission progress information to obtain the travel distance traveled during the transmission elapsed time, and obtains the distance from the vehicle to the predetermined position. The difference between the time and the transmission elapsed time causes a deviation between the distance traveled by the vehicle and the correct distance from the vehicle to the predetermined position.

  As described above, in the road-to-vehicle communication system, as in the in-vehicle device 2 of the present embodiment, the receiving unit (in-vehicle head 20) and the arithmetic processing unit (in-vehicle computer 21) are configured independently. In the case of a machine, accurate transmission progress information about downlink information (transmission elapsed time indicating transmission elapsed time that coincides with reception elapsed time) cannot be obtained, and distance information may not be corrected accurately. There has been a problem that the distance to a predetermined position ahead in the vehicle traveling direction cannot be obtained with high accuracy.

  In this regard, according to the road-to-vehicle communication system of the present embodiment, the correction unit 21c transmits the second downlink information 30 even if the transmission progress information is not stored in the transmission frame from the optical beacon 4. Based on the total number of frames 31 and the traveling speed of the vehicle C, a correction distance corresponding to the traveling of the vehicle during the reception of the second downlink information 30 can be obtained. The distance to the position can be obtained with high accuracy.

[Second Embodiment]
FIG. 7 is a block diagram showing the overall configuration of the road-vehicle communication system according to the second embodiment of the present invention, and FIG. 8 is a side view showing the communication area of the optical beacon.
The difference between this embodiment and said 1st embodiment is comprised by several (4) division area UA1-UA4 which the uplink area UA which comprises the communication area A divides | segments into a vehicle advancing direction. A plurality of beacon heads 8 arranged side by side along the direction corresponding to the vehicle traveling direction so as to be able to receive the uplink information 29 from the in-vehicle device 2 corresponding to the plurality of divided areas UA1 to UA4. And the beacon controller 7 of the optical beacon 4 on the basis of the light reception levels output by the plurality of photosensors 11, the uplink light of the vehicle-mounted device 2 in the uplink area UA. It is a point provided with the position specific | specification part 7a which specifies a transmission position. Since other points are the same as those in the first embodiment, description thereof is omitted.

  The communication area A of the present embodiment is configured by the downlink area DA and the uplink area UA as in the first embodiment, but the uplink area UA is the vehicle traveling direction as described above. It is divided into multiple parts. Specifically, the uplink area UA has three boundary lines (boundary portions) having the position of the beacon head 8 as the upper end and the positions e1 to e3 set between the position u1 and the position u2 on the road R as the lower end. Divided into four by K.

  The four photosensors 11 provided in the beacon head 8 use the divided areas UA1 to UA4 of the uplink area UA as reception areas. Therefore, for example, the uplink information transmitted from the in-vehicle head 20 in the divided area UA1 is received by the photosensor 11 corresponding to the divided area UA1.

As shown in FIG. 8, the optical beacon 4 stores numerical values of distances L2 to L5 from a predetermined position P2 to P5 in the communication area A to a predetermined position P0 downstream thereof as distance information. And distance information about these distances L2 to L4 is stored in the second downlink information 30 and transmitted.
Positions P2 to P5 that are upstream ends of the distances L2 to L5 are set according to the divided areas UA1 to UA4 of the uplink area UA. Specifically, the positions P2 to P5 are set at substantially the center position in the vehicle traveling direction on the road R in each of the divided areas UA1 to UA4.

The optical beacon 4 selects any one of the distance information about the plurality of distances L2 to L5 stored in advance, and stores it in the second downlink information 30. Which of the distances L2 to L5 is selected is determined based on the photosensor 11 that has received the uplink information 29 before switching the downlink.
For example, in the uppermost divided area UA1, the in-vehicle head 20 of the vehicle C traveling on the road R transmits the uplink information 29, and the photosensor 11 corresponding to the divided area UA1 receives the uplink information 29. , The position specifying unit 7a of the beacon controller 7 specifies the photosensor 11 that has received the uplink information 29, selects the distance information L2 corresponding to the divided area UA1, and switches the downlink, The second downlink information 30 including the distance information about L2 is transmitted.

  The same applies when any of the photosensors 11 corresponding to the other divided areas UA2 to UA4 receives the uplink information 29, and the position specifying unit 7a is set to the divided area corresponding to the received photosensor 11. The distances L3 to L5 corresponding to the positions P3 to P5 are selected, and the second downlink information 30 including the distance information about the distances L2 to L4 is transmitted.

That is, in this embodiment, the position of the vehicle-mounted device 2 (vehicle C) when the optical beacon 4 that has received the uplink information 30 starts transmission of the first second downlink information 30 after switching is the uplink. Assuming that it is one of the predetermined positions P2 to P5 in the area UA, the distances L2 to L5 to the predetermined position P0 on the downstream side at that time are selected and the in-vehicle device 2 recognizes them.
That is, the position specifying unit 7a of the beacon controller 7 specifies the position of the in-vehicle device 2 when the uplink information 29 is received, using the fact that the uplink area UA is composed of a plurality of divided areas. It has a function.

When the in-vehicle device 2 receives the second downlink information 30 including the distance information, the in-vehicle computer 21 extracts the distance information included in the downlink information 30, and the distance information is the distances L2 to L5. Recognize which one is.
And the correction | amendment part 21c of the vehicle-mounted computer 21 calculates | requires the distance Lc after correction | amendment by using the recognized distance (any of distance L2-L4) while calculating a correction distance, and performs the safe driving | operation assistance with respect to a driver. .

  According to the present embodiment, in addition to being able to correct the error in the distance information caused by the vehicle traveling before the in-vehicle device 2 receives the second downlink information 30 by the correction unit 21c, Since the position of the vehicle-mounted device 2 at the stage when the optical beacon 4 that is the stage has received the uplink information 29 can be specified, the distance to the predetermined position P0 ahead in the vehicle traveling direction in the vehicle-mounted device 2 is accurately obtained. Can do.

The present invention is not limited to the above embodiments.
In the above-described embodiment, the in-vehicle head 20 is configured to output information related to these to the in-vehicle computer 21 when all the transmission frames 31 corresponding to the total frames constituting the second downlink information 30 have been received. However, for example, each time the transmission frame 31 is received, the information related to the received transmission frame 31 may be output to the in-vehicle computer 21.

  In the above embodiment, the case where the required number of transmissions is selected according to the reception probability obtained from the bit error rate of the transmission frame 31 is exemplified. However, the in-vehicle head 20 receives the second downlink information from the optical beacon 4. The required number of transmissions may be selected according to the reception level (light reception level) when 30 is received.

That is, if the reception level is higher than the required strength, the communication quality in the optical communication between the optical beacon 4 and the vehicle-mounted device 2 is good, the occurrence rate of transmission errors and the like is reduced, and the second downlink information 30 The reception probability, which is the probability that the in-vehicle device 2 can receive all of the plurality of transmission frames 31 constituting the, increases. On the other hand, if the reception level is lower than the required strength, the reception probability decreases.
For this reason, for example, the in-vehicle head 20 detects the reception level when the second downlink information 30 from the optical beacon 4 is received, and the detected reception level is output to the in-vehicle computer 21, and the correction unit 21c The required number of transmissions may be selected according to the reception level.
Further, the reception probability can be obtained from the reception level, and the necessary number of transmissions can be selected according to the reception probability.

  Further, the communication quality such as the bit error rate and the reception level in the optical communication between the optical beacon 4 and the in-vehicle device 2 depends on the reception performance of the in-vehicle device 2 itself. . For this reason, you may comprise so that the correction | amendment part 21c may select a required transmission frequency according to own reception performance.

In each of the above embodiments, the correction unit 21c obtains a unit correction distance every time a correction distance is obtained in response to reception of the second downlink information 30, and further, based on the unit correction distance and the required number of transmissions. For example, the correction distance obtained from the traveling speed of the vehicle C and the required number of transmissions is stored in advance in a storage unit or the like in the form of a table or the like, and the traveling speed and the It can also be configured to acquire the correction distance when the necessary number of transmissions has been acquired.
Further, the required number of transmissions is determined in advance, and the combination of the traveling speed and the corresponding correction distance (= traveling speed × required number of transmissions) is stored in advance in a storage unit or the like in the form of a table or the like. It can also be configured to acquire the correction distance when it is acquired.

  Further, in each of the above embodiments, the positions of the predetermined positions P1 to P5 of the distances L1 to L5 constituting the distance information are not limited to the substantially central positions on the road R of the uplink area UA and the divided areas UA1 to UA4. Can be set. For example, it can be set at the upstream end or the downstream end in the region.

  In addition to the stop line 40, the predetermined position P0 on the downstream side in the vehicle traveling direction may be an installation position of a traffic light or a position of a vehicle detector. Further, the distance information in each of the above embodiments 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. There may be.

In the second embodiment, the number of divided areas UA1 to UA4 (the number of photosensors 11) may be two, three, or five or more.
Further, the photosensor 11 can logically divide the reception area into a plurality of areas, thereby making each a reception unit. That is, one photosensor 11 can have a plurality of receiving units. Then, these receiving units can be made to correspond to the divided areas UA1 to UA4 on the road, respectively, and distance information can be selected according to which area of the photosensor 11 is irradiated with the uplink light. In this case, it is possible to correspond to all the divided areas by using the photosensors 11 smaller than the number of the divided areas.

In each of the above embodiments, the distance information stored in the second downlink information 30 is such that the downstream end is the position P0 where the stop line or the like is located, and the upstream end is the uplink area UA, or each of the divided areas UA1 to UA1. Although the distances L1 to L5 between both ends when the positions P1 to P5 set in the UA4 are set (see FIGS. 3 and 8), the distance information may be information shown in other formats.
For example, in the first embodiment, the distance information includes the distance from the position u2 that is the upstream end of the uplink area UA to the position P1 (first distance) and the position u2 to the position P0 on the stop line 40 side. The distance (second distance) can be indicated by two pieces of information (see FIG. 3), and the vehicle-mounted device 2 obtains the distance L1 from the first distance and the second distance, and corrects the distance L1. Can do.
Similarly, in the case of the second embodiment in which the divided areas UA1 to UA4 are introduced, the distance information is the distances (first distances) from the position u2 to the positions P2 to P5 in each divided area, It can be indicated by two pieces of information of the distance (second distance) from the position u2 to the position P0 on the stop line 40 side (see FIG. 8). Correction can be performed by obtaining L2 to L5.

  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.

2 In-vehicle device 4 Optical beacon 7 Beacon controller 21c Correction unit 29 Uplink information 30 Second downlink information 31 Transmission frame 40 Stop line (predetermined position)
A Communication area C Vehicle R Road

Claims (17)

A vehicle-mounted device that transmits uplink information in a communication area set in a predetermined range on a road, and a predetermined downlink information is repeatedly transmitted to the vehicle-mounted device at a predetermined transmission cycle after receiving the uplink information in the communication region. A road-to-vehicle communication system comprising an optical beacon to transmit,
The optical beacon stores the distance information about the distance from the communication area to a predetermined position ahead in the vehicle traveling direction in the predetermined downlink information including a plurality of transmission frames having a total number of frames. Have a machine,
The in-vehicle device calculates a correction distance for a correction distance for the distance information according to the traveling of the vehicle while receiving the predetermined downlink information based on the total number of frames and the traveling speed of the vehicle. has a part,
The correction distance calculation unit obtains a unit correction distance that the vehicle travels while one predetermined downlink information is transmitted from the total number of frames and the traveling speed,
Obtaining a required number of transmissions of the predetermined downlink information necessary to receive all the transmission frames corresponding to the total frame;
Obtaining the correction distance based on the unit correction distance and the required number of transmissions;
Furthermore, the correction distance calculation unit is a road-to-vehicle communication system that determines the required number of transmissions based on communication quality of the predetermined downlink information defined in advance . The probability that the correction distance calculation unit can receive all the transmission frames corresponding to the total number of frames corresponding to the number of transmissions when the predetermined downlink information is repeatedly transmitted, which is obtained from the communication quality the based on the reception probability indicated, road-vehicle communication system according to claim 1 for determining the required number of transmission times. The road-to-vehicle communication system according to claim 1 , wherein the communication quality is a bit error rate when the transmission frame is received. An in-vehicle device that transmits uplink information in a communication area set in a predetermined range on a road and receives predetermined downlink information repeatedly transmitted at a predetermined transmission period from an optical beacon that has received the uplink information. There,
The predetermined downlink information includes a plurality of transmission frames having a predetermined total number of frames, and includes distance information about a distance from the communication area to a predetermined position ahead in the vehicle traveling direction,
Based on the traveling speed of the vehicle and the total number of frames, according to the running of the vehicle while receiving the predetermined downlink information, have a corrected distance calculation unit for determining a correction distance for the distance information,
The correction distance calculation unit obtains a unit correction distance that the vehicle travels while one predetermined downlink information is transmitted from the total number of frames and the traveling speed,
Obtaining a required number of transmissions of the predetermined downlink information necessary to receive all the transmission frames corresponding to the total frame;
Obtaining the correction distance based on the unit correction distance and the required number of transmissions;
Further, the correction distance calculation unit is an in- vehicle device that determines the required number of transmissions based on a predetermined communication quality of the predetermined downlink information . A vehicle-mounted device that transmits uplink information in a communication area set in a predetermined range on a road, and a predetermined downlink information is repeatedly transmitted to the vehicle-mounted device at a predetermined transmission cycle after receiving the uplink information in the communication region. A road-to-vehicle communication system comprising an optical beacon to transmit,
  The optical beacon stores the distance information about the distance from the communication area to a predetermined position ahead in the vehicle traveling direction in the predetermined downlink information including a plurality of transmission frames having a total number of frames. Have a machine,
  The in-vehicle device, after obtaining all transmission frames constituting the predetermined downlink information, a receiving unit that outputs all these transmission frames;
  A correction distance calculation unit that determines that the predetermined downlink information has been received when all the transmission frames output by the reception unit are acquired, and
  The correction distance calculation unit is based on the required number of transmissions of the predetermined downlink information necessary for receiving all the transmission frames corresponding to the total number of frames, and the traveling speed of the vehicle, A road-to-vehicle communication system characterized by obtaining a correction distance for the distance information according to the travel of the vehicle until it is determined that predetermined downlink information has been received. An in-vehicle device that transmits uplink information in a communication area set in a predetermined range on a road and receives predetermined downlink information repeatedly transmitted at a predetermined transmission period from an optical beacon that has received the uplink information. There,
  The predetermined downlink information includes a plurality of transmission frames having a predetermined total number of frames, and includes distance information about a distance from the communication area to a predetermined position ahead in the vehicle traveling direction,
  A receiver that outputs all the transmission frames after obtaining all the transmission frames constituting the predetermined downlink information;
  A correction distance calculation unit that determines that the predetermined downlink information has been received when all the transmission frames output by the reception unit are acquired, and
  The correction distance calculation unit is based on the required number of transmissions of the predetermined downlink information necessary for receiving all the transmission frames corresponding to the total number of frames, and the traveling speed of the vehicle, An in-vehicle device characterized in that a correction distance for the distance information is obtained according to the travel of the vehicle until it is determined that predetermined downlink information has been received. A vehicle-mounted device that transmits uplink information in a communication area set in a predetermined range on a road, and a predetermined downlink information is repeatedly transmitted to the vehicle-mounted device at a predetermined transmission cycle after receiving the uplink information in the communication region. A road-to-vehicle communication system comprising an optical beacon to transmit,
The optical beacon stores the distance information about the distance from the communication area to a predetermined position ahead in the vehicle traveling direction in the predetermined downlink information including a plurality of transmission frames having a total number of frames. Have a machine,
The in-vehicle device calculates a correction distance for a correction distance for the distance information according to the traveling of the vehicle while receiving the predetermined downlink information based on the total number of frames and the traveling speed of the vehicle. Department have a,
Further, the in-vehicle device is provided so as to receive the predetermined downlink information from the optical beacon through a wiped member of the vehicle that is wiped by a wiper device provided in the vehicle. ,
When the operation of the wiper device is detected, the correction distance calculation unit sets an alternative value set in advance as the correction distance instead of the calculated correction distance . The road-to-vehicle communication system according to claim 7 , wherein the correction distance calculation unit obtains a distance traveled by the vehicle while the predetermined downlink information is repeatedly transmitted twice as the correction distance. The road-to-vehicle communication system according to claim 7 , wherein the correction distance calculation unit obtains a distance traveled by the vehicle while the predetermined downlink information is transmitted once as the correction distance. The correction distance calculation unit obtains a unit correction distance that the vehicle travels while one predetermined downlink information is transmitted from the total number of frames and the traveling speed,
Obtaining a required number of transmissions of the predetermined downlink information necessary to receive all the transmission frames corresponding to the total frame;
The road-to-vehicle communication system according to claim 7 , wherein the correction distance is obtained based on the unit correction distance and the required number of transmissions. The road-to-vehicle communication system according to claim 10 , wherein the correction distance calculation unit determines the required number of transmissions based on communication quality of the predetermined downlink information. The probability that the correction distance calculation unit can receive all the transmission frames corresponding to the total number of frames corresponding to the number of transmissions when the predetermined downlink information is repeatedly transmitted, which is obtained from the communication quality The road-to-vehicle communication system according to claim 11 , wherein the required number of transmissions is determined based on a reception probability indicating The road-vehicle communication system according to claim 11 or 12 , wherein the communication quality is a bit error rate when the transmission frame is received. The road-vehicle communication system according to claim 11 or 12 , wherein the communication quality is a reception level of the predetermined downlink information received by the in-vehicle device. A vehicle-mounted device that transmits uplink information in a communication area set in a predetermined range on a road, and a predetermined downlink information is repeatedly transmitted to the vehicle-mounted device at a predetermined transmission cycle after receiving the uplink information in the communication region. A road-to-vehicle communication system comprising an optical beacon to transmit,
The optical beacon stores the distance information about the distance from the communication area to a predetermined position ahead in the vehicle traveling direction in the predetermined downlink information including a plurality of transmission frames having a total number of frames. Have a machine,
The in-vehicle device calculates a correction distance for a correction distance for the distance information according to the traveling of the vehicle while receiving the predetermined downlink information based on the total number of frames and the traveling speed of the vehicle. Department have a,
When the correction distance calculation unit detects that the predetermined downlink information has been switched corresponding to another in-vehicle device other than itself when receiving the predetermined downlink information, the correction distance calculated A road-to-vehicle communication system characterized in that an alternative value set in advance is used as the correction distance . An in-vehicle device that transmits uplink information in a communication area set in a predetermined range on a road and receives predetermined downlink information repeatedly transmitted at a predetermined transmission period from an optical beacon that has received the uplink information. There,
The predetermined downlink information includes a plurality of transmission frames having a predetermined total number of frames, and includes distance information about a distance from the communication area to a predetermined position ahead in the vehicle traveling direction,
Based on the traveling speed of the vehicle and the total number of frames, according to the running of the vehicle while receiving the predetermined downlink information, have a corrected distance calculation unit for determining a correction distance for the distance information,
Further, the predetermined downlink information from the optical beacon is provided so as to pass through a wiped member of the vehicle that is wiped by a wiper device provided in the vehicle,
When the operation of the wiper device is detected, the correction distance calculation unit sets an alternative value set in advance as the correction distance instead of the calculated correction distance . An in-vehicle device that transmits uplink information in a communication area set in a predetermined range on a road and receives predetermined downlink information repeatedly transmitted at a predetermined transmission period from an optical beacon that has received the uplink information. There,
The predetermined downlink information includes a plurality of transmission frames having a predetermined total number of frames, and includes distance information about a distance from the communication area to a predetermined position ahead in the vehicle traveling direction,
Based on the traveling speed of the vehicle and the total number of frames, according to the running of the vehicle while receiving the predetermined downlink information, have a corrected distance calculation unit for determining a correction distance for the distance information,
When the correction distance calculation unit detects that the predetermined downlink information has been switched corresponding to another in-vehicle device other than itself when receiving the predetermined downlink information, the correction distance calculated A vehicle-mounted device characterized in that an alternative value set in advance is used as the correction distance .

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