JP5935530B2 - Light beacon - Google Patents

Description

  The present invention relates to an optical beacon, and more particularly to an optical beacon having a function of specifying the position of a vehicle from uplink light transmitted from the vehicle.

  As a traffic information service using a road-to-vehicle communication system, an optical beacon has already been developed. This optical beacon employs optical communication using near infrared rays as a communication medium, and is capable of bidirectional communication with a vehicle (on-vehicle device). Specifically, uplink information including travel time information etc. possessed by the vehicle is transmitted from the vehicle to the optical beacon, and conversely, downlink including traffic jam information, section travel time information, event regulation information, lane notification information, etc. Information is transmitted from the light beacon to the vehicle.

  In the road-to-vehicle communication system using such an optical beacon, the optical beacon specifies the position of the vehicle, and “distance information from the specified position to a predetermined position on the downstream side (for example, a stop line provided in front of the intersection). This information is included in the downlink information, and the vehicle that receives this information uses the distance information to perform braking control so that it stops before the stop line, or to stop or decelerate the driver. For example, it is possible to perform safe driving support control for the driver (see, for example, Patent Documents 1 and 2).

  In order to perform such safe driving support, the optical beacon needs to accurately identify the position of the traveling vehicle. Therefore, the applicant defines the uplink region as a plurality of divided regions divided in the vehicle traveling direction, and receives a plurality of light receiving portions that receive the uplink light corresponding to the plurality of divided regions arranged in the vehicle traveling direction. The optical beacon provided with the part (photodiode) is proposed (for example, refer patent document 3).

  According to such an optical beacon controller provided with a plurality of light receiving units corresponding to a plurality of divided regions, for example, the ratio of the light receiving levels of the plurality of light receiving units that have received one uplink light is calculated. This makes it possible to specify the vehicle position at the moment when the uplink light is transmitted, that is, the uplink transmission position. In addition, specification of the position of the vehicle by an optical beacon in this way is also called position location.

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

  FIG. 7 is a block diagram of a controller 81 included in a conventional optical beacon. The controller 81 includes a main processing device 82 (hereinafter referred to as “main CPU 82”. The CPU is a Central Processing Unit), a sub processing device 83 (hereinafter referred to as “sub CPU 83”), and a programmable logic device 84 (hereinafter referred to as “sub CPU 83”). PLD 84 ”) and a communication control circuit unit 85.

The position determination by the optical beacon as described above is performed by the sub CPU 83, and when the sub CPU 83 obtains the result of the position determination, the result is notified to the main CPU 82 via the PLD 84.
Each time the sub CPU 83 obtains the result of position determination, the sub CPU 83 notifies the result to the main CPU 82. For this purpose, it is necessary to interrupt the main CPU 82 from the sub CPU 83 through the PLD 84. This interrupt cycle varies depending on the operating condition of the sub CPU 83, but is about 200 to 300 microseconds.

On the other hand, the main CPU 82 performs processing for acquiring uplink information from the received uplink light, downlink switching processing, and the like as processing for road-to-vehicle communication.
The main CPU 82 generates downlink information by using the uplink information and the information on the position determination result obtained from the sub CPU 83, and transmits the information to the vehicle 87 through the communication control circuit unit 85 and the beacon head 86. To send.

As described above, the main CPU 82 performs the downlink switching process. According to the “near-infrared interface standard” of the optical vehicle detector (light beacon), the switching time is set to 8 ± 2 milliseconds. It is necessary to meet.
When such a downlink switching process needs to be performed within a predetermined processing time, and the interruption from the sub CPU 83 occurs frequently at a cycle of, for example, 200 to 300 microseconds, the main CPU 82 This process is delayed and it becomes difficult to satisfy the above condition.

  Furthermore, even if the regular uplink light is not transmitted from the vehicle 87, it is conceivable that the light receiving unit of the beacon head 86 receives noise light such as reflected light. In this case, when a signal based on the noise light is output from the light receiving unit, the sub CPU 83 processes the output signal, and performs the interrupt as described above to the main CPU 82, the load on the main CPU 82 further increases, and the main CPU 82 There is a problem that necessary processing that should be originally performed by the CPU 82 is delayed. In addition, as reflected light, the reflected light by sunlight, the reflected light by the downlink light of an optical beacon, etc. can be considered.

  Accordingly, an object of the present invention is to provide an optical beacon that can reduce the load on the main CPU as much as possible and notify the main CPU of necessary information.

(1) The present invention processes a light receiving unit that receives uplink light, which is an optical signal constituting uplink information transmitted from a vehicle, and also receives noise light , and an output signal output from the light receiving unit. an optical beacon and a control unit, of the said uplink light and the noise light, from the output signal by said uplink optical can acquire the uplink information communication processing A sub-processing unit that obtains position information for specifying the position of the vehicle based on the output signal, and requests the communication processing unit to read the position information; and the position information or information based on the position information and a main processing unit for generating a downlink information based on the uplink information, the communication processing unit, said position read in accordance with the prior SL read request Interrupt processing for obtaining prior Symbol main processing unit to broadcast or information based on this position information, it can be performed with respect to the main processing unit, the communication processing unit, the time to get the uplink information The position information corresponding to the read request is read, and the interrupt processing for causing the main processing unit to acquire the read position information or information based on the position information is performed.

According to the present invention, the communication processing unit performs interrupt processing for causing the main processing unit to acquire position information read in response to a read request during acquisition of uplink information or information based on the position information. Therefore, the interruption to the main processing unit based on light other than the uplink light can be eliminated, and the load on the main processing unit can be reduced as compared with the related art.
For example, the light receiving unit receives noise light as light other than the uplink light, the sub processing unit obtains some information based on the output signal from the light receiving unit, and makes a request to read the information to the communication processing unit However, since the communication processing unit cannot acquire the uplink information from the noise light, the main processing unit performs an interrupt process for causing the main processing unit to acquire the information obtained by the noise light. Don't do that. As a result, it is possible to reduce the load on the main processing unit as compared with the conventional case.
The “information based on position information” includes, for example, representative position information.

(2) Further, the optical beacon further includes a storage unit that stores the uplink information and the position information or information based on the position information, and the communication processing unit acquires the uplink information, It is preferable to store the uplink information and the position information read in response to the reading request or information based on the position information in the storage unit.
In this case, when one interruption process is performed on the main processing unit, the main processing unit obtains the uplink information and the position information or information based on the position information by one access or 2 It is possible to reduce the load on the main processing unit by reading with one access and reducing the number of interrupt processing for the main processing unit.
(3) Although it can be read by one or two accesses in this way, the main processing unit, when the interrupt processing is performed, the uplink information stored in the storage unit and the position It is particularly preferable to read the information or the information based on the position information with one access, and this can further reduce the load on the main processing unit.

(4) Further, the communication processing unit, during the acquisition of the uplink information is considered to be that the read request over multiple times by the sub-processing unit.
Therefore, the communication processing unit generates a representative specific one of the position information based on the read the position information of the multiple in accordance with the read request, the representative one of the position information to the position information It is preferable to perform the interrupt process for causing the main processing unit to acquire the information based on the information .
In this case, one representative position information is generated by the communication processing unit, and an interrupt process is performed to cause the main processing unit to acquire this one representative position information. Instead of reading information, it is only necessary to read this representative single location information.

  (5) In addition, the position information for position determination obtained by the sub-processing unit can be information as a result of specifying the position of the vehicle on the road. In this case, the position of the vehicle on the road is The information of the identified result is obtained by the sub processing unit, and the main processing unit does not need to obtain the information, and the burden on the main processing unit can be reduced.

(6) Alternatively, the position information for position determination obtained by the sub-processing unit is information for causing the communication processing unit to specify the position of the vehicle on the road, and the communication processing unit The position information read in response to the read request by the processing unit is converted into position information specifying the position of the vehicle on the road, and the converted position information or information based on the converted position information is converted into the main information. The interrupt process for causing the processing unit to acquire can be performed.
In this case, information as a result of specifying the position of the vehicle on the road is obtained by the communication processing unit, and the main processing unit does not need to obtain the information, and the burden on the main processing unit can be reduced. .

(7) The optical beacon further includes a storage unit that stores the position information or information based on the position information, and the communication processing unit reads the position information read in response to the read request or the position information. Based information and the uplink information are stored in a predetermined storage area of the storage unit, and the main processing unit is stored in the prescribed storage area when the interrupt processing is performed by the communication processing unit It is preferable to read the information in one access.
In this case, when receiving an interrupt request, the main processing unit can acquire the uplink information and the position information by one access by reading the information stored in the predetermined storage area.

(8) The optical beacon further includes a storage unit that stores the position information or information based on the position information, and the communication processing unit is receiving uplink information based on the output signal. And determining that it is being received, the position information read in response to the read request only during the reception or information based on the position information is stored in the storage unit, and the main processing unit Preferably, when the interrupt processing is performed by the communication processing unit, the position information stored in the storage unit or information based on the position information is read.
In this case, the information generated by the sub processing unit based on the noise light is not stored in the storage unit.

(9) In addition, when the optical beacon further includes a storage unit having a storage area for storing the position information read in response to the read request, the storage area is limited. Preferably, the communication processing unit acquires the uplink information, and clears the information in the storage area when the interrupt processing is performed in the main processing unit.
In this case, a storage area for newly obtained position information can be secured.

  According to the present invention, the communication processing unit performs interrupt processing for causing the main processing unit to acquire position information read in response to a read request during acquisition of uplink information or information based on the position information. Therefore, the interruption to the main processing unit based on light other than the uplink light can be eliminated, and the load on the main processing unit can be reduced as compared with the related art.

It is a side view which shows the optical beacon of this invention and its communication area. It is a block diagram which shows an example of the structure of the light-receiving part of an optical beacon, and a controller. It is explanatory drawing of the signal which a communication process part processes. It is explanatory drawing of the memory | storage information in a memory | storage device when it sees from main CPU. It is explanatory drawing of the memory | storage information in a memory | storage device when it sees from main CPU. It is a distribution map of the light reception level of the light receiving unit when the vehicle traveling direction is taken as the horizontal axis. It is a block diagram of the controller which the conventional optical beacon has.

Embodiments of the present invention will be described below.
[Overall configuration of optical beacon]
FIG. 1 is a side view showing an optical beacon of the present invention and its communication area. The optical beacon 1 includes a beacon head (projector / receiver) 2 and a controller 3 connected to the beacon head 2.
The beacon head 2 has a plurality of light receiving parts 4 constituted by photodiodes (PD) and a light projecting part 5 constituted by light emitting diodes (LEDs), which are housed in a housing 6. Has been. In the present embodiment, four light receiving units 4 are provided, and these light receiving units 4 are PD1, PD2, PD3, and PD4.

The light projecting unit 5 projects (transmits) downlink light DO (an optical signal constituting the downlink information) made of near-infrared light to the communication area.
Each of the plurality of light receiving units 4 (PD1 to PD4) receives an uplink light UO (an optical signal constituting uplink information) made of near infrared rays transmitted from the vehicle 8 (onboard device 9). , Provided corresponding to the divided areas UA1 to UA4 of the uplink area UA. The light receiving unit 4 includes a condensing lens, and the uplink light UO from the in-vehicle device 9 is collected by the condensing lens, and the light receiving surfaces of the plurality of light receiving units 4 (PD1 to PD4). A part is irradiated as spot light.

The controller 3 includes a microcomputer having the processor unit 7 and the storage device 14, processes the output signal output from the light receiving unit 4 (PD1 to PD4) that has received the uplink light UO, and generates the generated downlink information. Is transmitted from the light projecting unit 5 as downlink light DO. The storage device 14 can be an internal memory, SDRAM, or SRAM included in the processor unit 7 (a communication processing unit 13 described later).
Thus, the controller 3 has a function as a communication control unit that performs road-to-vehicle communication with the vehicle-mounted device 9 through the beacon head 2. Further, the controller 3 specifies a position specifying function for specifying the position of the in-vehicle device 9 (vehicle 8) at the moment when the light receiving unit 4 receives the uplink light UO from the in-vehicle device 9 (also referred to as an uplink reception position). Also have. These functions are realized by the processor unit 7 executing a computer program stored in the storage device of the controller 3.

The four light receiving units 4 (PD1 to PD4) use the divided areas UA1 to UA4 of the uplink area UA as light receiving areas, respectively. For example, the uplink light UO (the spot light) transmitted from the vehicle-mounted device 9 in the divided area UA4 located on the most upstream side is mainly received by the light receiving unit PD4 corresponding to the divided area UA4. Therefore, the processor unit 7 performs arithmetic processing on the output signals of the light receiving units 4 (PD1 to PD4) that have received the uplink light UO, thereby specifying the position of the vehicle-mounted device 9 at the moment of receiving the uplink light UO. It becomes possible to do.
Note that various methods can be adopted as such a vehicle position specifying method. For example, the method described in Patent Document 3 (Japanese Patent Laid-Open No. 2008-186349) or Japanese Patent Application Laid-Open No. 2012-84072. It is possible to use the method described in the publication.
In addition, while explaining the structure of the light-receiving part 4 and the controller 3, the method described in Unexamined-Japanese-Patent No. 2012-84072 is demonstrated easily.

FIG. 2 is a block diagram illustrating an example of the configuration of the light receiving unit 4 and the controller 3. Each of the four light receiving parts 4 (PD1 to PD4) is composed of photodiodes that function independently of each other, and these PD1 to PD4 are arranged close to each other in the beacon head 2, and each of PD1 to PD4 is located on the road side. This corresponds to the divided areas UA1 to UA4 (see FIG. 1).
In FIG. 1, PD1 corresponds to the most downstream division area (final division area) UA1 in the communication area A, and PD2 to PD4 are the second, third, and fourth divisions from the downstream side, respectively. This corresponds to the areas UA2 to UA4.

Each of PD1 to PD4 receives the uplink light UO and outputs a signal corresponding to the received light level. Further, the beacon head 2 includes an amplifier circuit that amplifies signals (voltages) output from the PD1 to PD4, an adder circuit that adds these signals, and the like.
The light receiving levels of PD1 to PD4 are V1 to V4. FIG. 6 is a distribution diagram of the received light levels of PD1 to PD4 when the vehicle traveling direction is taken as the horizontal axis. Aj indicates a subdivision area obtained by subdividing each of the divided areas UA1 to UA4 (j = 1 to 10). Lk is a representative point defined for each Aj. As shown in FIG. 6, each of the light receiving levels V1 to V4 has a mountain-shaped distribution with a broad base, and adjacent PDi and PDi + 1 overlap each other in a region of about half the maximum width.
Therefore, by using this distribution characteristic, a subdivision area Aj is defined by subdividing the boundary positions of the divided areas and the distances between the boundary positions. For example, an intermediate position where the light reception levels Vi and Vi + 1 of PDi and PDi + 1 in which the divided areas are adjacent to each other has a constant ratio m1 / m2 or its inverse m2 / m1 is defined, and the divided areas are subdivided using these intermediate positions as boundaries. doing. As described above, by using the ratio of the light receiving levels Vi and Vi + 1 corresponding to the adjacent divided areas, subdivision areas Aj less than the length of the divided areas can be defined in each divided area. In this embodiment, the downstream end position of each subdivision area Aj is defined as a representative point Lk (k = 0 to 9) of the subdivision area. In this embodiment, it is divided into 10 subdivision areas, and 10 representative points are defined. The representative point Lk may be a position other than the downstream end position of each subdivision area Aj, or may be an upstream end position (k = 1 to 10).

The method for specifying the uplink light reception position (that is, the position of the vehicle-mounted device 9) in the divided area (subdivision area Aj) defined in this way is performed as follows. The controller 3 specifies one representative point Lk of Aj as a reception position of the uplink light from the vehicle based on a predetermined determination criterion. For example, in the controller 3, when the light reception levels V3 and V4 are acquired and the ratio V4 / V3 is greater than or equal to the ratio m1 / m2 (m1 / m2 ≦ V4 / V3), the reception position of the uplink light is set to A1. Considering the range, the representative point L9 of A1 is specified as the position of the vehicle.
As described above, the processor unit 7 performs arithmetic processing on the output signals (light reception levels) of the light receiving units 4 (PD1 to PD4) that have received the uplink light UO, so that the uplink light UO is received. It becomes possible to specify the position of the vehicle-mounted device 9.

  The processor unit 7 includes a main processing unit 11, a sub processing unit 12, and a communication processing unit 13. The main processing unit 11 and the sub processing unit 12 are composed of a central processing unit (CPU), and the communication processing unit 13 is composed of a programmable logic device (PLD). Hereinafter, the main processing unit 11 is referred to as a main CPU 11, and the sub processing unit 12 is referred to as a sub CPU 12.

The signals output from PD1 to PD4 are converted into digital signals and then input to the communication processing unit 13 of the processor unit 7.
In addition, signals (voltages) output from the PD1 to PD4 are converted into digital signals and then input to the sub CPU 12 of the processor unit 7.

Here, uplink information by uplink light will be described. The uplink information is framed according to the “near infrared interface standard” of the optical vehicle detector (light beacon), and according to this standard, a predetermined synchronization byte, That is, a synchronization byte of a data string of 0x7E = 0b01111110 is added.
Therefore, “7E” on the left side shown in FIG. 3 is a synchronization byte indicating the beginning of the frame of uplink information, and “7E” on the right side is a synchronization byte indicating the end of the frame of uplink information. Note that the time required for transmission of uplink information (uplink information reception time) is about 3 milliseconds, although it depends on the contents of the actual data portion.

  Therefore, when the output signal output from the light receiving unit 4 (PD1 to PD4) is input to the communication processing unit 13, the communication processing unit 13 starts and ends the frame of the uplink information based on the output signal. And uplink information can be acquired (extracted). Further, the communication processing unit 13 can determine whether or not uplink information is being received (receiving) by finding the synchronization byte.

  That is, the acquisition of uplink information, which is a process performed by the communication processing unit 13, extracts useful information to be given to the optical beacon 1 side in road-to-vehicle communication from the output signal of the light receiving unit 4 based on regular uplink light. Say. Therefore, the light receiving unit 4 receives the noise light to output a signal and the communication processing unit 13 receives the signal, but uplink information is not acquired (extracted) from the noise light.

  Furthermore, as will be described later, the communication processing unit 13 performs “interrupt” for causing the main CPU 11 to acquire the position information obtained by the sub CPU 12 or information based on this position information (typical position information described later). It has a function of performing “processing” on the main CPU 11.

Independently of the processes in the communication processing unit 13, the sub CPU 12 acquires the light reception levels (voltage values V1 to V4) of the PD1 to PD4 that have received the uplink light UO, and receives these light reception levels (V1). -V4), it is possible to obtain information for specifying at which position in the uplink area UA the uplink optical UO is received.
That is, when the output signals from PD1 to PD4 are input to the sub CPU 12, the sub CPU 12 can obtain position information for specifying the position of the vehicle 8 that has transmitted the uplink light UO based on the output signal. .
In addition, as an example of this position information for position specification, it is information indicating the position on the road at the moment when the vehicle transmits the uplink light UO, and the position information according to the present embodiment is position specification (position location). The result information.
With this information, the sub CPU 12 can specify the position of the vehicle 8 at the moment when the uplink light UO is transmitted.

Then, the sub CPU 12 makes a “read request” for the obtained position information to the communication processing unit 13.
The sub CPU 12 samples the output signal at a predetermined cycle to generate position information. For example, sampling is performed at a cycle of 200 to 300 microseconds, position information is generated, and a “read request” is sent to the communication processing unit 13 each time it is generated. As shown in FIG. 3, this sampling period is sufficiently smaller than the time (3 milliseconds) required for transmitting uplink information. If the sampling period is, for example, 300 microseconds and the uplink information transmission time is 3 milliseconds, the communication processing unit 13 receives about 10 “read requests” within the uplink information reception time. .

Then, the communication processing unit 13 stores the position information read in response to this “read request” in the storage device 14.
In the present embodiment, as will be described later, the communication processing unit 13 in response to the “read request” stores the position information read from the sub CPU 12 and the information generated based on the position information in the storage device 14. Data is written in a predetermined storage area (storage areas M1 and M2 in FIG. 4 or FIG. 5). Therefore, the “read request” by the sub CPU 12 can also be said to be a write request to the storage device 14.
The information generated based on the position information obtained by the sub CPU 12 is calculated from the position information read by the communication processing unit 13 in response to the “read request” while the communication processing unit 13 is receiving the uplink information. “Representative location information”.

  4 and FIG. 5 are explanatory diagrams of stored information in the storage device 14 when viewed from the main CPU 11, respectively. The storage device 14 includes storage areas M1 and M2 for storing position information read in response to a “read request” and information (typical position information) generated based on the position information.

  The main CPU 11 generates downlink information based on the position information obtained by the sub CPU 12 (in this embodiment, information based on this position information) and the uplink information acquired by the communication processing unit 13.

[Processing by the processor unit 7 for specifying the vehicle position]
Processing by the processor unit 7 for specifying the vehicle position performed in the optical beacon 1 (controller 3) having the above configuration will be described.
In FIG. 2, the light receiving unit 4 receives noise light in addition to the regular uplink light UO and outputs a signal. However, as described above (see FIG. 3), the communication processing unit 13 can acquire (extract) uplink information from the regular uplink light UO, but cannot acquire uplink information from noise light. Therefore, it is possible to distinguish uplink light from noise light.
Further, the sub CPU 12 obtains position information at a predetermined sampling period based on an output signal from the light receiving unit 4 and makes a “read request” to the communication processing unit 13.

  The communication processing unit 13 reads the position information read in response to the “read request” from the sub CPU 12 during the acquisition of the uplink information, and causes the main CPU 11 to acquire information based on the read position information. “Interrupt processing” is performed on the main CPU 11. This “interrupt processing” is executed when reception of the uplink information is completed.

  That is, as described above, in FIG. 3, based on the output signal from the light receiving unit 4, the communication processing unit 13 recognizes the uplink information by finding the synchronization byte (7E). Further, the arrow P in FIG. 3 indicates the timing of “read request” by the sub CPU 12, and “read request” is made every sampling period (300 microseconds). In this embodiment, since the sampling period is set to 300 microseconds, a plurality of (about 10 times) position information is obtained during reception of uplink information (during 3 milliseconds). Is done. When the sampling cycle is long, etc., only one piece of position information is required, and the “reading request” may be once.

Further, since the light receiving unit 4 also receives noise light or the like, the “reading request” is performed in a time zone other than during reception of uplink information (3 milliseconds).
However, the communication processing unit 13 reads the position information for which the “reading request” has been made only during the time period during which the downlink information is being received, and stores this position information in a predetermined area of the storage device 14 (area M1 in FIG. 4 or FIG. 5). ). That is, the communication processing unit 13 determines whether or not the uplink information is being received based on the output signal. When the communication processing unit 13 determines that the uplink information is being received, the communication processing unit 13 makes a “read request” only during reception of the uplink information. In response, the read position information is stored in a predetermined area of the storage device 14. The communication processing unit 13 also stores the received downlink information in a predetermined area of the storage device 14 (see FIG. 4 or FIG. 5).

In particular, in the present embodiment, when acquiring the uplink information, the communication processing unit 13 acquires the uplink information, the position information read in response to the “read request”, and the information generated based on the position information (typical Is stored in the storage device 14. Then, when the “interrupt processing” is performed by the communication processing unit 13, the main CPU 11 reads the uplink information stored in the storage device 14 and the representative position information. Then, the main CPU 11 generates downlink information using such information.
Thus, the main CPU 11 can read the uplink information and the position information (representative value) by performing the “interrupt process” once for the main CPU 11, and the interrupt process for the main CPU 11 can be read. The number of times can be reduced, and the load on the main CPU 11 can be reduced.

  In particular, in the present embodiment, the communication processing unit 13 generates representative position information based on a plurality (or one) of position information read in response to the “read request”. That is, in this embodiment (FIG. 3), the communication processing unit 13 reads position information by 10 “read requests” during reception of uplink information, and stores the position information in the storage area M1 ( 4 or 5). Then, the communication processing unit 13 generates one representative position information based on the position information stored in the storage area M1. The representative position information can be an average value of a plurality of position information stored in the storage area M1.

The communication processing unit 13 stores the representative position information in a predetermined storage area of the storage device 14. For example, in the case of FIG. 4, representative position information is stored in the area of the address “A000”. Then, the communication processing unit 13 performs “interrupt processing” for causing the main CPU 11 to acquire the representative position information.
For the main CPU 11, since it is predetermined that representative position information is stored in this area “A000”, the main CPU 11 receives a single interrupt process from the communication processing unit 13. By referring to the address of the specified area “0000” where the uplink information is stored and the address of this area “A000”, that is, the uplink information and the position information (representative value) in two accesses. It becomes possible to acquire.

  FIG. 5 shows another example. In the case of FIG. 5, the communication processing unit 13 stores representative position information and uplink information in a predetermined storage area of the storage device 14. That is, the prescribed storage area is an area where addresses are continuous, and uplink information and representative position information are stored continuously. In this case, when the main CPU 11 receives one interrupt process from the communication processing unit 13, the main CPU 11 accesses the area “0000” in which the uplink information is stored and the area “0010” continuous to this area once. Can be read continuously. That is, in the case of FIG. 5, it is not necessary to read two addresses as in the case of FIG. 4, and uplink information and position information (representative value) can be acquired together by one access. .

As described above, when the communication processing unit 13 acquires the uplink information, the communication processing unit 13 uses the uplink information and the position information (representative value) read in response to the “reading request” as the default storage area of the storage device 14 unit. It is stored in M2 (see FIGS. 4 and 5).
Thereby, when the main CPU 11 receives the “interrupt request”, the information stored in the storage device 14 is read by accessing twice (in the case of FIG. 4) or once (in the case of FIG. 5). Uplink information and position information (representative value) can be acquired.

  Further, since the communication processing unit 13 generates position information (representative value), the main CPU 11 does not have to obtain this position information (representative value), and the main CPU 11 stores the position information (representative value) in the area M1 of the storage device 14. It is sufficient to read representative position information instead of a plurality of position information. For this reason, the burden on the main CPU 11 is reduced.

In the present embodiment, the position information (representative value) for specifying the position of the vehicle obtained by the sub CPU 12 is information obtained as a result of specifying the position of the vehicle on the road, and specifically, the reference position. Information on the distance from the vehicle to the position of the vehicle (vehicle-mounted device 9). The reference position is, for example, the position of the upstream end of the uplink area UA, and the position of the vehicle (vehicle-mounted device 9) is a position specified based on the light reception levels by PD1 to PD4 as described with reference to FIG. .
In addition, in the downlink information generated and transmitted by the optical beacon 1, in addition to the position information for specifying the position of the vehicle (information on the distance from the reference position to the vehicle position), the stop of the intersection ahead of the reference position Information on the distance to various nodes such as a line is included, and the vehicle-mounted device 9 that has transmitted uplink light and acquired this downlink information obtains the distance from the various nodes such as a stop line to the position of the vehicle. Is possible.
Since the position information (representative value) for specifying the position of the vehicle is obtained by the sub CPU 12, the main CPU 11 does not need to obtain position information (representative value), and the processing load of the main CPU 11 is reduced. The Then, the communication processing unit 13 performs “interrupt processing” for causing the main CPU 11 to acquire this position information.

On the other hand, as another example, the position information for specifying the position of the vehicle obtained by the sub CPU 12 may be information for causing the communication processing unit 13 to specify the position of the vehicle on the road. That is, the position information obtained by the sub CPU 12 may be information on the light reception level (light reception level ratio) of each of PD1 to PD4, for example, instead of information on the result of specifying the position of the vehicle. In this case, the communication processing unit 13 specifies the position of the vehicle on the road by using the position information for position specification (information on the respective light receiving levels of PD1 to PD4) read in response to the “read request” by the sub CPU 12. Convert to location information. In other words, as described with reference to FIG. 6, the conversion process obtains the position of the vehicle-mounted device 9 at the time of receiving the uplink light UO based on the ratio of the received light levels, and from the reference position to the position of the vehicle-mounted device 9 The position information obtained by conversion by the communication processing unit 13 is information on the distance from the reference position to the position of the vehicle (onboard unit 9).
Then, the communication processing unit 13 performs “interrupt processing” for causing the main CPU 11 to acquire the converted position information.

  According to the above-described optical beacon 1 according to the present embodiment, even if the light receiving unit 4 receives noise light and the “reading request” from the sub CPU 12 frequently occurs at a sampling period of, for example, 300 microseconds, Since the communication processing unit 13 cannot acquire uplink information from the noise light, an “interrupt process” for causing the main CPU 11 to acquire information obtained from the noise light is performed on the main CPU 11. Not performed. That is, the interruption to the main CPU 11 based on light other than uplink light can be eliminated. As a result, the load on the main CPU 11 can be reduced, and the main CPU 11 can perform downlink switching processing within a specified time (8 ± 2 milliseconds) as processing for road-to-vehicle communication. Thus, it is possible to prevent a necessary process that should be originally performed from being delayed.

  Then, when the communication processing unit 13 acquires the uplink information and “interrupt processing” is performed in the main CPU 11, the position information stored in the storage area M <b> 1 (see FIGS. 4 and 5) of the storage device 14 is obtained. Clear (erase) and secure a storage area for newly obtained position information.

The embodiments disclosed herein are illustrative and non-restrictive in every respect. The scope of rights of the present invention is not limited to the above-described embodiments, but includes all modifications within the scope equivalent to the configurations described in the claims.
For example, in the above-described embodiment, the case where the main CPU 11 reads representative position information when interrupt processing is performed has been described. However, the main CPU 11 may read the position information itself obtained by the sub CPU 12.

Moreover, although the said embodiment demonstrated the case where the light-receiving part 4 consists of four photodiodes (PD1-PD4) provided side by side in the beacon head 2, the light-receiving part 4 may be another form.
For example, the light receiving unit 4 may be configured by a position detection element (Position Sensitive Detector) that detects the incident position of the uplink light (spot light) with one detector. PSD) is a non-split type light receiving element using the surface resistance of a photodiode. Although not shown, the position detection element is rectangular, and is attached to the beacon head such that the longitudinal direction of the position detection element corresponds to the traveling direction of the vehicle. Then, according to the position where the vehicle transmits the uplink light, the incident position of the spot light changes in the longitudinal direction of the position detection element, and thereby the output signal output from the position detection element also changes. Using this characteristic, the sub CPU 12 can obtain position information for specifying the vehicle position based on an output signal from the position detection element.

  1: optical beacon 3: controller (control unit) 4: light receiving unit 8: vehicle 11: main CPU (main processing unit) 12: sub CPU (sub processing unit) 13: communication processing unit 14: storage device (storage unit) M1: Storage area M2: Storage area UO: Uplink light

Claims (9)

A light receiving unit that receives uplink light, which is an optical signal that constitutes uplink information transmitted from a vehicle, and also receives noise light , and a control unit that processes an output signal output from the light receiving unit. An optical beacon,
The controller is
Among said noise light and the uplink optical, a communication processing unit is said from said output signal by uplink optical can acquire the uplink information,
Obtaining a position information for specifying the position of the vehicle based on the output signal, and a sub-processing section for making a request for reading the position information to the communication processing section;
A main processing unit that generates downlink information based on the position information or information based on the position information and the uplink information;
With
The communication processing unit, the interrupt processing for obtaining prior Symbol main processor information based on the position information or the position information read in accordance with the prior SL read request, it is made to the main processing unit Can
The communication processing unit reads the position information corresponding to the reading request made within the time to acquire the uplink information, and causes the main processing unit to acquire the read position information or information based on the position information. For performing the interrupt processing for,
Light beacon characterized by. A storage unit for storing the uplink information and the position information or information based on the position information;
The communication processing unit, when acquiring the uplink information, causes the storage unit to store the uplink information and the position information read in response to the read request or information based on the position information. The optical beacon described in 1.   The main processing unit reads the uplink information stored in the storage unit and the position information or information based on the position information in one access when the interrupt process is performed. 2. The optical beacon according to 2. The communication processing unit generates a representative specific one of the position information based on the read the position information of the multiple in accordance with the read request, information based this representative one position information to the position information light beacons according to any one of claims 1-3 performs the interruption process to get to the main processing unit as.   The optical beacon according to any one of claims 1 to 4, wherein the position information for position determination obtained by the sub-processing unit is information obtained as a result of specifying a position of a vehicle on a road. The position information for position determination obtained by the sub-processing unit is information for specifying the position of the vehicle on the road by the communication processing unit,
The communication processing unit converts the position information read in response to the reading request from the sub-processing unit into position information specifying the position of the vehicle on the road, and the converted position information or the converted position information The optical beacon according to any one of claims 1 to 4, wherein the interrupt processing for causing the main processing unit to acquire information based on position information is performed. A storage unit for storing the position information or information based on the position information;
The communication processing unit stores the position information read in response to the read request or information based on the position information and the uplink information in a predetermined storage area of the storage unit,
7. The main processing unit according to claim 1, wherein when the interrupt processing is performed by the communication processing unit, the main processing unit reads the information stored in the specified storage area by one access. Light beacon. A storage unit for storing the position information or information based on the position information;
The communication processing unit determines whether or not uplink information is being received based on the output signal, and if it is determined that reception is being performed, the communication processor reads the read request only in response to the read request. Store location information or information based on this location information in the storage unit,
The main processing unit reads the position information stored in the storage unit or information based on the position information when the interrupt processing is performed by the communication processing unit. Light beacon. A storage unit having a storage area for storing the position information read in response to the read request;
The optical beacon according to any one of claims 1 to 8, wherein the communication processing unit acquires the uplink information and clears the information in the storage area when interrupt processing is performed in the main processing unit.

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