JP5176703B2 - In-vehicle system, communication device, and control device - Google Patents

Description

  The present invention relates to an in-vehicle system that receives downlink information from a roadside device in a communicable area with the roadside device.

  An optical beacon is widely used as a system for providing information to a vehicle traveling on a road. In this system, a road section of about 3.7 m near a roadside machine installed on the side of the road is set as a communicable area. And a roadside machine transmits downlink information by projecting an optical signal with respect to the communication apparatus mounted in the vehicle which passes this communicable area. The communication device that has received the downlink information transmits the uplink information to the roadside device using an optical signal. Then, the roadside device that has received the uplink information transmits downlink information including traffic jam information and traffic regulation information to the communication device.

  In the future, optical beacons will provide distance information between the roadside machine and the previous intersection of this roadside machine, etc., and use this distance information etc. to control the behavior when the vehicle passes the intersection There is a concept of providing assistance. However, in order to perform such driving assistance, the distance between the vehicle after passing the vicinity of the roadside machine and the intersection is accurately determined by a control device that performs driving assistance (hereinafter simply referred to as “control device”). It is necessary to grasp well. In order to grasp this distance, for example, the communication possible area is determined based on the arrival time when the vehicle has reached the communicable area, the current time, and the history of the speed after reaching the communicable area to the present. It is conceivable to calculate the moving distance of the vehicle after reaching the road number and subtract the moving distance from the distance information from the roadside machine to the intersection or the like. In order to accurately grasp the distance between the vehicle and the intersection by this method, it is necessary to accurately grasp the moving distance, and for that purpose, at least the arrival time when the vehicle reaches the communicable area is accurate. You must grasp it well.

  One method for accurately specifying the arrival time is to specify the transmission time of the uplink information normally received by the roadside device by the communication device or the control device, and to regard this transmission time as the arrival time. Can do. Here, for example, if the communication device is built in the control device, the communication unit that communicates with the roadside device in the control device and the control unit that performs driving assistance communicate at a sufficiently high speed. In addition, the time can be synchronized between the communication unit and the control unit. For this reason, the communication unit specifies the transmission time of the uplink information and notifies the control unit, or the communication unit notifies the control unit that the downlink information has been received as a response to the uplink information without a large delay. And can be. Therefore, the transmission time of the uplink information normally received by the roadside device can be accurately identified by the control unit, and the arrival time can be accurately grasped by the control unit.

  However, for example, when the communication device and the control device are connected by a serial bus having a low communication speed, such as when the communication device is externally attached to the control device, the communication device transmits the downlink information. There is a delay after the reception until the control device receives the data based on the downlink information. For example, it is assumed that 10 kbytes of data is transmitted as downlink information from the roadside device to the communication device, the baud rate between the communication device and the control device is 19.2 kbps, and the transfer efficiency is 50%. At this time, when the communication device transfers all the data to the control device, it takes about 10 s until the control device receives all the data. At this time, if the vehicle is traveling at 36 km / h, the vehicle travels a distance of 100 m during this time, and the traveling distance increases due to an increase in the speed of the vehicle. When an error in the distance between the vehicle and the intersection or the like has occurred as much as 100 m, the control device cannot appropriately control the behavior when the vehicle passes through the intersection. As described above, when specifying the arrival time in the control device to which the communication device is externally attached, it is necessary to consider the time required for the control device to receive data based on the downlink information from the communication device. is there.

  Here, in Patent Document 1, the distance between the start end and the end of the communicable area is set to a predetermined range, thereby accurately recognizing the distance between the vehicle that has reached the communicable area and the intersection. A road-to-vehicle communication system that enables this is described. In the distance authentication system described in Patent Document 2, the downlink information transmitted from the roadside device that received the uplink information includes the distance information between the communicable area and the intersection, and the roadside after receiving the uplink information. Transmission progress information based on the timing at which the machine first transmits downlink information is included. Based on this transmission progress information, the travel distance of the host vehicle after reaching the communicable area is calculated, and by correcting the distance information, the distance between the host vehicle passing through the communicable area and the intersection, etc. is further increased. It is possible to calculate accurately.

However, in Patent Literature 1 and Patent Literature 2, it is necessary for the control device to receive data based on downlink information from the communication device, as in the case where an optical beacon communication device is externally attached to the control device. In the case where time needs to be taken into account, there is no description of a method for accurately identifying the arrival time when the host vehicle reaches the communicable region with the control device.
JP 2007-293660 A JP 2007-293825 A

  The present invention has been made in order to solve the above-described problems. When the communication device and a control device that performs driving assistance are connected by a transmission line, the transmission time of data from the communication device to the roadside unit is set. An object is to provide an in-vehicle system that can be accurately estimated by a control device.

  The in-vehicle system according to claim 1, which has been made to solve the above problems, includes a communication device that communicates with a roadside device, and a control device that is connected to the communication device via a transmission path. The communication apparatus includes a downlink information receiving unit that receives downlink information transmitted from the roadside device, and an uplink that transmits uplink information to the roadside device when the downlink information receiving unit receives the downlink information. Link information transmission means. In addition, when the uplink information transmission unit succeeds in transmitting the uplink information to the roadside device, the communication device transmits the data based on the downlink information received by the downlink information reception unit via the transmission line. And a data transmission means for starting a data transmission process, which is a process for transmitting data at a data transmission start timing that is a timing at which a predetermined waiting time has elapsed, starting from a transmission timing of uplink information that has been successfully transmitted. Further, the control device includes a data receiving unit that receives data transmitted from the communication device, a reception start time specifying unit that specifies a reception start time that is a time when the data receiving unit starts receiving data, and a reception start time. When the reception start time is specified by the specifying means, a transmission time estimation means for estimating the transmission time of the uplink information by the communication device based on the specified reception start time and a predetermined waiting time is provided.

  Note that the data transmission means may regard the timing at which transmission of uplink information that has been successfully transmitted to the roadside machine is started as transmission timing, or regard the timing at which transmission of this uplink information is terminated as transmission timing. Also good. Further, any timing during transmission of the uplink information may be set as the transmission timing.

  The transmission time estimation means may estimate the transmission time of the uplink information by the communication device by estimating the transmission start time of the uplink information by the communication device, or may end the transmission of the uplink information by the communication device. By estimating the time, the transmission time of the uplink information by the communication device may be estimated. Further, the transmission time of the uplink information by the communication device may be estimated by estimating the time at any timing when the communication device is transmitting the uplink information.

  The time required for the host vehicle to pass through the communicable area, which is the area in which the communication device and the roadside machine can communicate, differs depending on the speed of the host vehicle, etc. The time varies depending on the speed of the host vehicle. Therefore, the communication device constituting the in-vehicle system according to claim 1 is configured so that when a predetermined waiting time elapses from the transmission timing of the uplink information that has been successfully transmitted to the roadside device, the communication device Start data transmission based on downlink information received from the machine. Further, the control device specifies the reception start time of the data transmitted from the communication device, and estimates the transmission time of the uplink information by the communication device based on the specified reception start time and a predetermined waiting time.

  By doing so, the communication device can perform a period from the transmission timing of the uplink information successfully transmitted to the roadside device to the start of data transmission processing to the control device for data based on the downlink information received from the roadside device. Time fluctuation can be suppressed. Then, the control device estimates the transmission time of the uplink information that has been successfully transmitted from the communication device to the roadside device based on the reception start time of the data based on the downlink information and a predetermined waiting time, and therefore transmits the data accurately. Time can be estimated.

  Therefore, the control device can calculate the travel distance of the host vehicle starting from the position of the host vehicle at the transmission time based on the estimated transmission time and the history of the speed of the host vehicle after the transmission time has elapsed. it can. For example, when the communication device receives distance information from the roadside unit to the intersection, etc., the distance between the own vehicle and the intersection, etc. is accurately grasped by subtracting the movement distance from the received distance information. It becomes possible. Thereby, the control device can accurately perform driving assistance when the host vehicle passes the intersection or the like.

Further, the communication apparatus may consider that the uplink information has been successfully transmitted to the roadside device in the following cases.
That is, as described in claim 2, the data transmission unit downlinks the downlink information transmitted by the roadside unit based on reception of the uplink information after the uplink information transmission unit transmits the uplink information. When the information receiving unit receives the information, the uplink information transmitting unit may consider that the uplink information has been successfully transmitted to the roadside device.

By so doing, it is possible to accurately determine whether or not the transmission of uplink information from the communication device to the roadside device has succeeded.
When communication is performed via a transmission line such as a serial bus, generally, data is divided into a plurality of packets, and transmission / reception of the packets is performed. In general, the hardware of a microcontroller that controls packet transmission / reception is configured to be able to specify the packet reception end time, but cannot be configured to specify the packet reception start time. In many cases, it is difficult to accurately specify the reception start time of a packet.

  Therefore, in the in-vehicle system according to claim 3, in the data transmission process, the data transmission unit transmits data based on the downlink information received by the downlink information reception unit to the control device as a plurality of packets, and starts reception. The time specifying means specifies the time when the data receiving means has completed the reception of the packet first transmitted by the data transmitting means, and based on the specified time and the data length of the packet first transmitted by the data transmitting means. The reception start time is specified.

In this way, when the microcontroller of the control device has a configuration that cannot specify the reception start time of the packet, or when it is difficult to specify the reception start time accurately. Even in this case, the reception start time of the packet can be accurately specified based on the reception end time of the packet.
Further, the communication device may perform communication with the roadside device as follows.

  That is, as described in claim 4, the downlink information receiving means receives the downlink information via the optical signal projected from the roadside device, and the uplink information transmitting means via the optical signal. Uplink information may be transmitted.

  In this way, when the communication device communicates with the roadside device of the optical beacon via the optical signal, the control device accurately grasps the transmission time of the uplink information that has been successfully transmitted to the roadside device of the optical beacon. can do.

  By the way, for example, in an optical beacon, an optical signal is generated using a light emitting diode as a light emitting element, and communication between the roadside device and the communication device is performed by the optical signal. When generating an optical signal, it is necessary to cause the light emitting diode to emit light with high luminance, which causes the light emitting diode to generate heat. For this reason, in an optical beacon, unless downlink information or uplink information is transmitted with a sufficient transmission interval, the light emitting diode may be destroyed due to heat generation. However, if the transmission of uplink information from the communication device to the roadside device fails, the communication device retransmits the uplink information. However, if the transmission interval is increased, the transmission time when the uplink information is first transmitted and the second time Thereafter, the difference in transmission time when uplink information is transmitted becomes large. Therefore, when the traveling speed of the host vehicle is high, the difference between the position where the uplink information is first transmitted and the position where the uplink information is transmitted after the second time becomes large. In this way, when distance information from a roadside machine to an intersection or the like is received, and the distance between the own vehicle and the intersection or the like is calculated using the movement distance of the own vehicle after the transmission time calculated based on the transmission time or the like The difference in the position that becomes the starting point of the movement distance becomes large. As a result, the control device cannot accurately calculate the distance between the host vehicle and the intersection or the like.

  Therefore, in the in-vehicle system according to the fifth aspect, the uplink information transmitting means repeatedly transmits the uplink information after transmitting the uplink information for the first time until the transmission of the uplink information is successful. Then, after the uplink information transmitting means transmits uplink information for the first time, the time interval until the uplink information is transmitted for the second time is after the uplink information transmitting means transmits the uplink information for the second time or later. The time interval until the next uplink information transmission is shorter.

  By doing this, if the transmission of the uplink information transmitted first when the vehicle is traveling at high speed fails, the uplink information is transmitted at the position where the uplink information was transmitted first and the second and subsequent times. It is possible to reduce the difference from the selected position. Therefore, when the host vehicle is traveling at a high speed, it is possible to improve the accuracy when the control device calculates the distance between the host vehicle and the intersection or the like. In addition, after the uplink information is transmitted for the first time, only the time interval until the uplink information is retransmitted for the second time is set shorter than the time interval when the uplink information is retransmitted for the third time and thereafter. Therefore, the occurrence of a situation where the light emitting diode is destroyed by heat generation can be suppressed.

  Further, in the future, there may be an increase in the number of installed roadside units for optical beacons, and it is possible to assume a situation in which roadside units are installed adjacent to each other due to an increase in the number of installed roadside units. In such a case, the communication apparatus can assume a case in which new downlink information is received from another roadside device before the data transmission process based on the downlink information received from the roadside device is terminated. . For example, it is assumed that 10 kbytes of data is transmitted as downlink information from the roadside device to the communication device, the baud rate between the communication device and the control device is 19.2 kbps, and the transfer efficiency is 50%. At this time, when the communication device transmits all of this data to the control device, it takes 10 s. If the vehicle is traveling at 36 km / h, the vehicle travels a distance of 100 m during this time. To do. Therefore, under the above assumption, if the roadside device is not installed with an interval of at least 100 m or more, the communication device may have another roadside device before ending the data transmission process based on the already received downlink information. May receive new downlink information.

Therefore, in the in-vehicle system according to claim 6, after the downlink information receiving means receives the downlink information from the roadside device, the downlink information reception is performed until the data transmission processing regarding the received downlink information is completed. When the means receives new downlink information from another roadside machine, the previously received downlink information and new information are based on the contents of the previously received downlink information and the newly received downlink information. The communication apparatus further includes a determination unit that determines downlink information having a high priority among the downlink information received in the first step. The other roadside machine means a roadside machine other than the roadside machine that is the transmission source of the downlink information that has already been received. Then, the data transmitting means, when the determining means determines that the downlink information newly received by the downlink information receiving means is downlink information with high priority, the data related to the newly received downlink information At the transmission start timing , data transmission processing regarding the downlink information is started.

  Assume that the downlink information includes information that requires estimation of the transmission time, such as distance information from a roadside machine to an intersection, etc., and the case where such information is not included. Can do. The determination unit determines that the priority of the downlink information that includes information that requires estimation of the transmission time is higher than the priority of the downlink information that does not include information that requires estimation of the transmission time. May be.

In this way, for example, the downlink information received first by the communication device does not include information that needs to be estimated, and the newly received downlink information needs to be estimated. When the information is included, the communication apparatus can start the data transmission process at the data transmission start timing for the newly received downlink information. Therefore, the control device can accurately estimate the transmission time for the down ink information newly received by the communication device.

In addition, assuming that roadside units are not installed with a sufficient interval, the in-vehicle system may have the following configuration.
That is, in the in-vehicle system according to claim 7, the data transmission unit receives the downlink information after the downlink information reception unit receives the downlink information from the roadside device until the data transmission process regarding the received downlink information is completed. When the information receiving means receives new downlink information from another roadside device, the data related to the downlink information received earlier even if the data transmission start timing related to the newly received downlink information has elapsed If the transmission process is not completed, the data transmission process related to the newly received downlink information may be started after the data transmission process related to the previously received downlink information is completed. The other roadside machine means a roadside machine other than the roadside machine that is the transmission source of the downlink information that has already been received. In addition, the communication device specifies a delay time between the data transmission start timing and the data transmission processing start timing when the data transmission means starts the data transmission processing after the data transmission start timing elapses. And a delay time transmitting unit that transmits the delay time specified by the delay time specifying unit to the control device via the transmission line.

  By doing so, when the communication device receives new downlink information from another roadside machine before finishing the data transmission process, and the timing for starting the data transmission process based on the newly received downlink information is delayed Even if it exists, the control device can grasp the delay time. The control device can estimate the transmission time with high accuracy by estimating the transmission time of the uplink information for another roadside device that is the transmission source of the new downlink information in consideration of the delay time. .

  In addition, since the control device can accurately estimate the transmission time even when the roadside machine is provided adjacent to the roadside machine by having the configuration according to claim 6 or claim 7, the roadside machine When installing the roadside machine, it becomes possible to install the roadside machine without considering the distance from other roadside machines.

  By the way, the communication device of the in-vehicle system described in claims 1 to 7 may be configured as a single unit and distributed in the market. Moreover, you may comprise the control apparatus as described in Claims 1-7 in a single body, and may distribute | circulate it to the market. Even if the communication device and the control device are configured as a single unit, the above-described effects can be obtained by combining with the corresponding control device or communication device.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. The embodiments of the present invention are not limited to the following embodiments, and various forms can be adopted as long as they belong to the technical scope of the present invention.

[Description of configuration]
(1) Overall Configuration FIG. 1 is a block diagram showing the configuration of the in-vehicle system 1. The in-vehicle system 1 includes an optical beacon receiver 10 and a navigation device 20. The optical beacon receiver 10 and the navigation device 20 are connected via a bus 30. The navigation device 20 is connected to an external device (not shown) that controls the behavior of the host vehicle, such as speed, via an in-vehicle LAN (not shown).

  The optical beacon receiver 10 is a device that performs bidirectional communication with the roadside device 40 via an optical signal using near infrared rays in a communicable area with the roadside device 40. When the own vehicle reaches the communicable area and the optical beacon receiver 10 enters the communicable area, the optical beacon receiver 10 uses the downlink information (hereinafter referred to as the downlink information for notifying that the own vehicle has entered the communicable area). (Also described as downlink information as idle information) is received from the roadside device 40. Then, the optical beacon receiver 10 that has received the downlink information transmits the uplink information to the roadside device 40. The roadside device 40 that has received the uplink information, with respect to the optical beacon receiver 10, information such as traffic jam information and road regulation information, distance information to an intersection existing in front of the vehicle passing through the communicable region, etc. Send downlink information that contains. The optical beacon receiver 10 transmits traffic jam information, distance information, and the like received from the roadside device 40 to the navigation device 20 via the bus 30.

  The navigation device 20 is a known navigation device that performs route guidance and the like. The navigation device 20 performs route guidance based on the traffic jam information received from the optical beacon receiver 10. In addition, the navigation device 20 enters the communicable region based on the distance information received from the optical beacon receiver 10 after the host vehicle reaches the communicable region and the speed history of the host vehicle after reaching the communicable region. The travel distance of the host vehicle after reaching is calculated, and the distance between the host vehicle and the intersection is calculated by subtracting the travel distance from the distance information. And the navigation apparatus 20 specifies the timing at which the own vehicle passes the said intersection based on the calculated distance. And, for example, before the own vehicle passes the intersection or the like, or when the own vehicle passes the intersection or the like, an instruction for appropriately controlling the speed of the own vehicle is provided to control the behavior of the own vehicle. By performing this operation on a device (not shown), driving assistance when the host vehicle passes through the intersection or the like is performed. In addition, the navigation device 20 notifies the warning of the vehicle, for example, when the vehicle passes the intersection, based on the calculated distance between the vehicle and the intersection. Provide driving assistance when passing.

  The roadside device 40 includes a light projecting / receiving unit 41 that performs light projection of near-infrared light signals and light reception of near-infrared light signals, and the optical beacon receiver 10 in the communicable region via the near-infrared light signals. Is a device that performs two-way communication. The roadside device 40 transmits downlink information as idle information at a predetermined cycle. And if the vehicle carrying the optical beacon receiver 10 enters the communicable region and receives the uplink information from the optical beacon receiver 10 that has received the downlink information as idle information, the roadside device 40 is Downlink information including traffic jam information and distance information (hereinafter also referred to as downlink information that the roadside device 40 transmits based on reception of uplink information) is transmitted at a predetermined cycle.

(2) Communicable Area Next, the communicable area between the roadside device 40 and the optical beacon receiver 10 will be described with reference to the explanatory diagram shown in FIG.

  The light projecting / receiving unit 41 of the roadside device 40 is installed directly above the traveling road of the vehicle, and performs bidirectional communication using near infrared rays with the optical beacon receiver 10 existing in the communicable area formed on the traveling road. Do. This communicable area includes an uplink area in which the light projecting / receiving unit 41 of the roadside device 40 can receive uplink information transmitted from the optical beacon receiver 10, and the optical beacon receiver 10 is connected to the roadside machine 40. The downlink area is an area in which downlink information transmitted from the light projecting / receiving unit 41 can be received. Note that the roadside device 40 may receive the uplink information transmitted from the optical beacon receiver 10 also in the region near the uplink region, and also receives the optical beacon in the region near the downlink region. The machine 10 may receive downlink information transmitted from the roadside machine 40.

  (A) of FIG. 2 is an explanatory diagram showing an uplink region when viewed from a position facing the traveling road, and (c) of FIG. 2 shows an uplink region when viewed from the side of the traveling road. It is explanatory drawing shown. FIG. 2B is an explanatory diagram showing a downlink region when viewed from a position opposed to the road, and FIG. 2D is a downlink when the road is viewed from the side. It is explanatory drawing which shows an area | region. The downlink area and the communicable area are the same area, and the uplink area is narrower than the downlink area.

  Here, the positional relationship of the uplink area with respect to the downlink area will be described. The uplink area is arranged so that the vehicle that has reached the communicable area enters the area that is the uplink area and the downlink area. Further, the uplink area is arranged such that when a vehicle that has reached the communicable area travels along the travel path, it first exits the uplink area and then exits the downlink area. The length in the vehicle traveling direction at the bottom in the uplink region is 1.6 m, and the length in the vehicle traveling direction at the bottom in the downlink region is 3.7 m.

(3) About optical beacon receiver Next, the structure of the optical beacon receiver 10 which comprises the vehicle-mounted system 1 is demonstrated. FIG. 3 is a block diagram showing a configuration of the optical beacon receiver 10. The optical beacon receiver 10 includes a light receiving unit 11, a light transmitting unit 12, and a control unit 13.

  The light receiving unit 11 is a part that receives an optical signal indicating downlink information projected from the roadside device 40 and converts the received optical signal into a format that can be read by the control unit 13. Specifically, it is composed of a photodiode or the like.

  The light transmission unit 12 is a part that generates an optical signal based on near infrared rays based on the uplink information generated by the control unit 13 and projects the light toward the roadside device 40. Specifically, it is composed of a light emitting diode or the like.

  The control unit 13 is mainly configured by a known microcomputer including a CPU, a ROM, a RAM, an I / O, a bus line connecting these, and the like. The control unit 13 is a part that controls each part of the optical beacon receiver 10 according to a program stored in the ROM. The control unit 13 has a clock function that can specify the current time in units of 1 ms.

The communication unit 14 is a part that transmits and receives various information to and from the navigation device 20 via the bus 30.
(4) About the navigation apparatus Next, the structure of the navigation apparatus 20 which comprises the vehicle-mounted system 1 is demonstrated. FIG. 4 is a block diagram showing a configuration of the navigation device 20. The navigation device 20 includes an operation unit 21, a display unit 22, an audio output unit 23, a storage unit 24, a map data input device 25, a control unit 26, a position detector 27, an in-vehicle LAN communication unit 28, and a communication unit 29. Has been.

The operation unit 21 is a part that receives various instructions from the user, and specifically includes a mechanical key switch, a touch switch, and the like.
The display unit 22 is a part that performs various displays, and specifically includes an LCD, an organic EL, or the like.

The sound output unit 23 is a part that outputs sound based on a signal input from the control unit 26.
The storage unit 24 includes a device (for example, HDD) that does not require a storage holding operation, and can store various types of information.

  The map data input device 25 is a device for inputting various data such as map data used when performing route guidance and the like, and facility search information used when searching for a predetermined facility. As a storage medium for these data, a DVD-ROM or the like is generally used because the amount of data is enormous.

  The control unit 26 is configured around a known microcomputer including a CPU, ROM, RAM, I / O, a bus line connecting these, and the like. The control unit 26 is a part that controls each part of the navigation device 20 in accordance with a program stored in the ROM. The control unit 26 has a clock function that can specify the current time in 1 ms units.

  The position detector 27 receives a radio wave from an artificial satellite for GPS (Global Positioning System) via a GPS antenna (not shown) and detects the position, azimuth, speed, etc. of the vehicle. A gyroscope 27b for detecting the magnitude of the rotational motion to be applied and a distance sensor 27c for detecting the distance traveled from the longitudinal acceleration of the vehicle or the like are provided. Since these have errors of different properties, they are configured to be used while complementing each other.

The in-vehicle LAN communication unit 28 is a part that transmits and receives various information via an in-vehicle LAN (not shown).
The communication unit 29 is a part that transmits and receives various information to and from the optical beacon receiver 10 via the bus 30.

[Description of operation]
Next, the operation of the in-vehicle system 1 will be described.
(1) About Downlink Information Reception Processing First, when the host vehicle travels in a communicable region with the roadside device 40, the downlink transmitted from the roadside device 40 by the optical beacon receiver 10 that has entered the communicable region. A downlink information reception process that is a process for receiving information will be described with reference to the flowchart shown in FIG. This downlink information reception process is started when the host vehicle starts to travel.

  In S <b> 105, the control unit 13 of the optical beacon receiver 10 receives the downlink information transmitted from the roadside device 40 via the light receiving unit 11. When the downlink information is received, the control unit 13 proceeds to S110.

  In S110, the control unit 13 determines whether the received downlink information is normal. Specifically, it is determined whether the received downlink information is downlink information (downlink information as idle information) for notifying that the host vehicle has entered the communicable area. When the received downlink information is downlink information as idle information (S110: Yes), the control unit 13 shifts the process to S115. When the received downlink information is not downlink information as idle information (S110: No), the control unit 13 shifts the process to S105.

In S <b> 115, the control unit 13 transmits uplink information to the roadside device 40 via the light transmission unit 12. And when transmission is complete | finished, the control part 13 transfers a process to S120.
In S120, the control unit 13 specifies the current time (T0) in units of 1 ms using the clock function, and the process proceeds to S125.

  In S125, the control unit 13 sets a response waiting time for the uplink information transmitted in S115, and the process proceeds to S130. The controller 13 sets 20 ms as a response waiting time at the time of transmitting the first uplink information, and thereafter sets a random time around 40 ms as the response waiting time.

  In S <b> 130, the control unit 13 receives downlink information transmitted from the roadside device 40 via the light receiving unit 11. When the downlink information is received or when the response waiting time after the transmission of the uplink information has elapsed, the control unit 13 proceeds to S135.

  In S135, the control unit 13 determines whether or not the uplink information transmission performed in S115 is successful. Specifically, when the downlink information received in S130 is the downlink information transmitted from the roadside device 40 based on the uplink information transmitted in S115, the control unit 13 is normal downlink information. Is considered received. When the downlink information received in S130 is normal (S135: Yes), the control unit 13 shifts the process to S150. When the downlink information received in S130 is not normal (S135: No), the control unit 13 shifts the process to S140.

  In S140, the control unit 13 determines whether or not the response waiting time after uplink information transmission has elapsed. When the response waiting time has elapsed (S140: Yes), the control unit 13 shifts the process to S145. When the response waiting time has not elapsed (S140: No), the process proceeds to S130.

  In S145, the control unit 13 determines whether downlink information has been received in S130. When the downlink information is received (S145: Yes), it is assumed that the host vehicle is passing through the communicable area with the roadside device 40, and the control unit 13 proceeds to S115. When downlink information is not received (S145: No), the control part 13 considers that the own vehicle passed the area | region which can communicate with the roadside machine 40, and transfers a process to S105.

  In S150, the control unit 13 sets a time obtained by adding 250 ms to the current time (T0) specified in S120 as a downlink information reception end time, and the process proceeds to S155.

In S155, the control unit 13 sets the data transmission process described later to be called as a timer interrupt process after 250 ms from the current time (T0) specified in S120, and shifts the process to S170. The control unit 13 temporarily stores the received downlink information in the RAM included in the control unit 13, and the process proceeds to S175.

  In S175, the control unit 13 specifies the current time in units of 1 ms using the clock function, and determines whether or not the current time has passed the reception end time set in S150. When the reception end time has elapsed (S175: Yes), the control unit 13 proceeds to S180. When the reception end time has not elapsed (S175: No), the control unit 13 proceeds to S160.

  In S <b> 160, which is shifted when the downlink information reception end time has not elapsed, the control unit 13 receives the downlink information transmitted from the roadside device 40 via the light receiving unit 11. When receiving the downlink information, the control unit 13 shifts the process to S165.

  In S165, the control unit 13 determines whether normal downlink information is received in S160. Specifically, when the downlink information received in S160 is the downlink information transmitted based on the uplink information transmitted in S115 by the roadside device 40, the control unit 13 performs normal downlink. Assume that information has been received. When normal downlink information is received (S165: Yes), the control unit 13 shifts the process to S170. When the normal downlink information is not received (S165: No), the control unit 13 shifts the process to S175.

  In S180, which is shifted when it is determined in S175 that the reception end time has passed, the control unit 13 waits until the host vehicle passes through the downlink region. Specifically, the control unit 13 determines whether or not downlink information has been received via the light receiving unit 11. For example, when no downlink information is received for 1 s, the host vehicle passes through the downlink region. The process proceeds to S185.

  In S185, the control unit 13 waits until transmission of data based on the downlink information is completed. Specifically, when the data transmission process called as the timer interrupt process ends, it is considered that the data transmission based on the downlink information has ended. When the transmission of data based on the downlink information ends, the control unit 13 ends the downlink information reception process.

(2) Data transmission process Next, the data transmission process in which the optical beacon receiver 10 transmits data based on the received downlink information as a packet to the navigation device 20 via the bus 30 will be described with reference to FIG. This will be described with reference to the flowchart described in the above. This process is a process called as a timer interrupt process, and is a process called at a transmission start timing that is a timing when 250 ms has elapsed after completion of transmission of uplink information that has been successfully transmitted to the roadside device 40.

  In S205, the control unit 13 determines whether or not the downlink information temporarily stored in the RAM included in the control unit 13 is normal by performing a checksum or the like. When the downlink information is not normal, the control unit 13 ends the data transmission process. When the downlink information is normal, the control unit 13 proceeds to S210.

  In S210, the control unit 13 sets the total number N of packets to be transmitted to the navigation device 20 based on the data amount of the downlink information stored in the RAM included in the control unit 13. Further, the control unit 13 sets 1 to a counter i when transmitting a packet, and shifts the processing to S215.

In S215, the control unit 13 sets 1s as a timeout period for retry transmission performed when packet transmission fails, and the process proceeds to S220.
In S220, the control unit 13 generates the i-th packet based on the downlink information temporarily stored in the RAM, and transmits the generated i-th packet to the navigation device 20 via the communication unit 14. To do. And the control part 13 transfers a process to S225. Note that the first packet has a fixed data length.

  In S225, the control unit 13 determines whether or not the transmitted packet is normally received by the navigation device 20. Specifically, when an ACK is returned as a response from the navigation device 20, it is determined that the packet is normally received by the navigation device 20, and when a NAC is returned as a response from the navigation device 20, The navigation device 20 determines that the packet has not been received normally. When the transmitted packet is normally received by the navigation device 20 (S225: Yes), the control unit 13 shifts the process to S230. When the transmitted packet is not normally received by the navigation device 20 (S225: No), the control unit 13 shifts the process to S240.

In S230, the control unit 13 updates the counter i by adding 1 to the counter i, and proceeds to S235.
In S235, the control unit 13 determines whether transmission of all packets has been completed. Specifically, when the counter i is larger than the total number N of packets, it is considered that transmission of all packets has been completed. When transmission of all packets is completed (S235: Yes), the control unit 13 ends the data transmission process. When transmission of all packets has not been completed (S235: No), the control unit 13 proceeds to S220.

  In S240 that is transferred when the transmitted packet is not normally received by the navigation device 20, the control unit 13 determines whether or not the timeout time (1 s) has elapsed after first transmitting the i-th packet. judge. When the timeout time has elapsed (S240: Yes), the control unit 13 ends the data transmission process. When the timeout time has not elapsed (S240: No), the control unit 13 shifts the process to S220.

(3) Packet Reception Process Next, the packet reception process, which is a process in which the navigation device 20 receives a packet transmitted from the optical beacon receiver 10, will be described with reference to the flowchart shown in FIG. This process is a process that is started when the communication unit 29 of the navigation device 20 detects a reception signal of a packet transmitted from the optical beacon receiver 10.

  In S <b> 305, the control unit 26 of the navigation device 20 receives a packet transmitted from the optical beacon receiver 10 via the communication unit 29. When reception ends, the control unit 26 proceeds to S310.

In S310, the control unit 26 specifies the current time (T1) in units of 1 ms by the clock function, and the process proceeds to S315.
In S315, the control unit 26 determines whether or not the received packet data is normal by performing a checksum or the like. If the received packet data is normal (S315: Yes), the control unit 26 shifts the process to S320. If the received packet data is abnormal (S315: No), the process proceeds to S340.

In S320, the control unit 26 stores the received packet in the RAM included in the control unit 26, and the process proceeds to S325.
In S325, the control unit 26 determines whether or not the packet stored in the RAM in S320 is the first packet. If it is the first packet (S325: Yes), the control unit 26 shifts the process to S330. If it is not the first packet (S325: No), the control unit 26 shifts the process to S335.

  In S330, the control unit 26 sets the current time (T1) specified in S310 as the reception completion time of the first packet. Further, the control unit 26 estimates the time required to receive this packet based on the data length of the first packet, and starts receiving data based on the downlink information by subtracting this time from the reception completion time. Time. Then, the transmission succeeds by subtracting 250 ms, which is a waiting time until the transmission of the first packet after the optical beacon receiver 10 transmits the uplink information that has been successfully transmitted, from the reception start time. Estimate the uplink information transmission time. And the control part 26 transfers a process to S335.

  In S335, the control unit 26 determines whether or not the packet received in S320 is the Nth packet. If it is the Nth packet (S335: Yes), the control unit 26 ends the packet reception process. When the packet is not the Nth packet (S335: No), the control unit 26 proceeds to S305.

  In S340, which is shifted when the packet data received in S305 is not normal, the control unit 26 determines whether or not 1 s has elapsed after first detecting an abnormality in the packet data in S315. When 1 s has elapsed (S340: Yes), the control unit 26 ends the packet reception process. When 1 s has not elapsed (S340: No), the control unit 26 shifts the process to S345.

  In S345, the control unit 26 receives a packet transmitted from the optical beacon receiver 10 via the communication unit 29. When reception ends, the control unit 26 proceeds to S315.

[effect]
According to the in-vehicle system 1 of the present embodiment, the optical beacon receiver 10 provides downlink information (downlink information as idle information) for notifying that the own vehicle has entered the communicable area from the roadside device 40. Upon reception (S105), uplink information is transmitted to the roadside device 40 (S115). When the transmission of the uplink information is successful, the optical beacon receiver 10 receives the downlink information (downlink information transmitted from the roadside device 40 based on the received uplink information) from the roadside device 40 a plurality of times. (S130, S160). Then, the optical beacon receiver 10 transmits data based on the downlink information received in S130 or S160 to the navigation device 20 after 250 ms has elapsed from the transmission timing of the uplink information successfully transmitted to the roadside device 40. The data transmission process that is the process of transmitting is started. In addition, when the navigation device 20 receives the first packet transmitted from the optical beacon receiver 10, the navigation device 20 specifies the reception completion time of this packet. Then, based on the reception completion time and the data length of the first packet, the data reception start time based on the downlink information is calculated. Then, the transmission time of the uplink information that has been successfully transmitted is subtracted from the calculated reception start time by subtracting 250 ms, which is the waiting time until the transmission of the first packet starts after successful transmission of the uplink information. Is estimated (S330). By doing so, the optical beacon receiver 10 can suppress fluctuations in time from the transmission timing of the uplink information successfully transmitted to the roadside device to the start of data transmission based on the downlink information. it can. Then, the navigation device 20 accurately determines the transmission time of the uplink information successfully transmitted to the roadside device based on the reception completion time of the first packet, the data length of the first packet, and the waiting time of 250 ms. It can be estimated well.

  Thereby, the navigation apparatus 20 calculates the movement distance of the own vehicle from the position of the own vehicle at the transmission time based on the estimated transmission time and the history of the speed of the own vehicle after the transmission time has elapsed. be able to. For example, when the distance information from the roadside device 40 to the intersection or the like is included in the downlink information, by subtracting the moving distance from the received distance information, the distance to the intersection or the like of the own vehicle is obtained. It becomes possible to grasp with high accuracy. As a result, the navigation device 20 can accurately perform driving assistance when the host vehicle passes the intersection or the like.

  The optical beacon receiver 10 considers that the uplink information has been successfully transmitted when the downlink information transmitted by the roadside device 40 is received based on the uplink information transmitted by the optical beacon receiver 10 ( S135). Therefore, it is possible to accurately determine whether or not the uplink information has been successfully transmitted.

  Moreover, the optical beacon receiver 10 repeatedly transmits uplink information until the transmission of uplink information is successful. At this time, the optical beacon receiver 10 sets 20 ms as a time interval until the uplink information is transmitted next after transmitting the uplink information first, and then transmits the uplink information after the second time. Thereafter, a random time around 40 ms is set as a time interval until the next uplink information is transmitted.

  By doing so, it is possible to reduce the difference between the position of the host vehicle when uplink information is transmitted for the first time and the position of the host vehicle when uplink information is transmitted for the second and subsequent times. Therefore, when the host vehicle is traveling at high speed, it is possible to improve the accuracy when the navigation device 20 calculates the distance between the host vehicle and the intersection or the like. In addition, the time interval until the next uplink information is retransmitted after the uplink information is transmitted for the first time is 20 ms. Thereafter, the time interval for retransmitting the uplink information is about 40 ms. It's time. For this reason, it is possible to suppress the occurrence of a situation where the light emitting diode is destroyed by heat generation.

[Other Embodiments]
(1) In this embodiment, the optical beacon receiver 10 starts data transmission processing when 250 ms has elapsed from the end of transmission of uplink information that has been successfully transmitted, and the navigation device 20 The time is estimated as the transmission time. However, the optical beacon receiver 10 starts data transmission processing when 250 ms has elapsed from the start of transmission of uplink information that has been successfully transmitted, and the navigation device 20 estimates the time at the start of transmission as the transmission time. You may do it. Further, the optical beacon receiver 10 starts data transmission processing when 250 ms elapses from any timing during transmission of the uplink information, and the navigation device 20 estimates the time of the timing as the transmission time. You may do it. Even in the case of having such a configuration, the navigation device 20 can accurately estimate the transmission time, and based on the estimated transmission time and the history of the speed of the host vehicle after the transmission time has passed, It is possible to accurately calculate the moving distance of the host vehicle starting from the position of the host vehicle at the transmission time.

  (2) In the present embodiment, 250 ms is set as a waiting time until the optical beacon receiver 10 first transmits uplink information and then starts packet data transmission processing. However, needless to say, a different time may be set as this waiting time. Even when a time other than 250 ms is set as the waiting time, the same effect can be obtained.

  (3) When the roadside unit 40 is installed adjacent to the optical beacon receiver 10, before the optical beacon receiver 10 finishes the data transmission process related to the downlink information received from the roadside unit 40, the own vehicle has another roadside unit 40. It is possible to envisage a case where the communication reachable area is reached. Since the optical beacon receiver 10 of the present embodiment ends the downlink information reception process after the data transmission process is completed, the downlink information transmitted from the other roadside device 40 is received before the data transmission process is completed. Never done.

  However, the optical beacon receiver 10 may start receiving downlink information when entering the communicable area of another roadside device 40 even before the end of the data transmission process. And the control part 13 may determine downlink information with high priority among these downlink information based on the content of the downlink information received previously and the newly received downlink information. And when it determines with the newly received downlink information having a high priority, the control part 13 may interrupt the data transmission process regarding the downlink information received previously. And the control part 13 is the data regarding the downlink information newly received in the transmission start timing which is the timing which 250 ms passed from the time of completion | finish of transmission of the uplink information in which transmission with respect to the other roadside machine 40 was successful. Transmission processing may be started.

  In addition, when the control unit 13 determines the priority of the downlink information, the priority of the downlink information that includes the information that needs to be estimated for the transmission time is included in the information that needs the estimation of the transmission time. It may be determined that the priority is higher than the priority of the downlink information that is not.

  By doing so, for example, the downlink information previously received by the optical beacon receiver 10 does not include information that requires estimation of the transmission time, and the newly received downlink information includes the estimation of the transmission time. Is included, the data transmission process can be started at the transmission start timing for the newly received downlink information. Therefore, the navigation device 20 can accurately estimate the transmission time for the newly received down ink information.

  In addition, by having such a configuration, the navigation device 20 can accurately estimate the transmission time even when the roadside device 40 is provided adjacent to the roadside device 40. Can be installed without considering the distance from other roadside units 40.

  (4) In addition, after the optical beacon receiver 10 receives the downlink information from the roadside device 40, new downlink information is received from the other roadside devices 40 until the data transmission process regarding the received downlink information is completed. In this case, the control unit 13 may perform the following process. That is, the control unit 13 may start the data transmission process related to the newly received downlink information after the data transmission process related to the downlink information received previously ends. At this time, the delay time between the transmission start timing regarding the newly received downlink information and the timing to start the data transmission process is specified, and the delay time is transmitted to the navigation device 20 via the communication unit 14. You may do it. Then, the navigation device 20 may estimate the transmission time with high accuracy by estimating the transmission time of the uplink information for the other roadside devices 40 in consideration of the delay time.

  In this way, the transmission time of the uplink information for the other roadside devices 40 can be estimated with high accuracy by the navigation device 20. In addition, by having such a configuration, the navigation device 20 can accurately estimate the transmission time even when the roadside device 40 is provided adjacent to the roadside device 40. Can be installed without considering the distance from other roadside units 40.

[Correspondence with Claims]
The correspondence between the terms used in the description of the above embodiment and the terms used in the description of the claims is shown.

  The optical beacon receiver 10 corresponds to a communication device. The light receiving unit 11 and the control unit 13 of the optical beacon receiver 10 are the downlink information receiving means, the light transmitting unit 12 and the control unit 13 are the uplink information transmitting means, and the control unit 13 and the communication unit 14 are. The control unit 13 corresponds to the data transmission unit, the determination unit and the delay time specifying unit, and the communication unit 14 corresponds to the delay time transmission unit.

  The navigation device 20 corresponds to a control device. The control unit 26 of the navigation device 20 corresponds to the reception start time specifying unit and the transmission time estimation unit, and the communication unit 29 corresponds to the data reception unit.

Also, the timing at which S115 in the downlink information reception process is completed corresponds to the transmission timing.
In addition, 250 ms, which is a waiting time from the end of transmission of uplink information successfully transmitted to the roadside device 40 until the optical beacon receiver 10 starts data transmission processing, corresponds to a predetermined waiting time.

The timing at which the data transmission process is started as the timer interrupt process corresponds to the data transmission start timing.
Further, the current time (T0) specified after the transmission of the uplink information that has been successfully transmitted to the roadside device 40 corresponds to the transmission time.

  The bus 30 corresponds to a transmission path.

It is a block diagram which shows the vehicle-mounted system. It is explanatory drawing about a communicable area | region. 1 is a block diagram showing an optical beacon receiver 10. FIG. 2 is a block diagram showing a navigation device 20. FIG. It is a flowchart for demonstrating a downlink information reception process. It is a flowchart for demonstrating a data transmission process. It is a flowchart for demonstrating a packet reception process.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... In-vehicle system, 10 ... Optical beacon receiver, 11 ... Light receiving part, 12 ... Light transmission part, 13 ... Control part, 14 ... Communication part, 20 ... Navigation apparatus, 21 ... Operation part, 22 ... Display part, 23 ... Audio output unit, 24 ... storage unit, 25 ... map data input device, 26 ... control unit, 27 ... position detector, 27a ... GPS receiver, 27b ... gyroscope, 27c ... distance sensor, 28 ... in-vehicle LAN communication unit, 29 ... communication part, 30 ... bus, 40 ... roadside machine, 41 ... light emitting / receiving part.

Claims (9)

An in-vehicle system having a communication device that communicates with a roadside device, and a control device that is connected to the communication device via a transmission path,
The communication device
Downlink information receiving means for receiving downlink information transmitted from the roadside device,
When the downlink information receiving means receives the downlink information, uplink information transmitting means for transmitting uplink information to the roadside device;
When the uplink information transmission means succeeds in transmitting the uplink information to the roadside device, the control device transmits data based on the downlink information received by the downlink information reception means via the transmission path. Data transmission processing that is a process of transmitting data to a data transmission start timing that is a timing at which a predetermined waiting time has elapsed, starting from the transmission timing of the uplink information that has been successfully transmitted,
The controller is
Data receiving means for receiving the data transmitted from the communication device;
A reception start time specifying means for specifying a reception start time which is a time when the data receiving means starts receiving the data;
When the reception start time is specified by the reception start time specifying means, a transmission time estimation for estimating a transmission time of the uplink information by the communication device based on the specified reception start time and the predetermined waiting time Providing means,
In-vehicle system characterized by The in-vehicle system according to claim 1,
The data transmission means receives the downlink information transmitted by the roadside device based on the reception of the uplink information after the uplink information transmission means transmits the uplink information. The transmission of the uplink information to the roadside device by the uplink information transmission means is considered successful,
In-vehicle system characterized by In the in-vehicle system according to claim 1 or claim 2,
The data transmitting means transmits the data based on the downlink information received by the downlink information receiving means to the control apparatus as a plurality of packets in the data transmission processing,
The reception start time specifying unit specifies a time at which the data receiving unit has completed reception of the packet first transmitted by the data transmitting unit, and the specified time and the data transmitting unit transmitted first Identifying the reception start time based on the data length of the packet;
In-vehicle system characterized by In the in-vehicle system according to any one of claims 1 to 3,
The downlink information receiving means receives the downlink information via an optical signal projected from the roadside device,
The uplink information transmitting means transmits the uplink information via an optical signal;
In-vehicle system characterized by In the in-vehicle system according to any one of claims 1 to 4,
The uplink information transmission means transmits the uplink information repeatedly after transmitting the uplink information for the first time until the transmission of the uplink information is successful,
The time interval from when the uplink information transmitting means first transmits the uplink information to when the uplink information is transmitted for the second time is determined by the uplink information transmitting means after the second time. Shorter than the time interval between transmission and the next transmission of the uplink information,
In-vehicle system characterized by In the in-vehicle system according to any one of claims 1 to 5,
After the downlink information receiving means receives the downlink information from the roadside device and before the data transmission processing related to the received downlink information is completed, the downlink information receiving means is connected to the other roadside. When new downlink information is received from a machine, based on the contents of the previously received downlink information and the newly received downlink information, the previously received downlink information and newly received The communication apparatus further includes a determination unit that determines the downlink information having a high priority among the received downlink information,
The data transmission means, when the determination means determines that the downlink information newly received by the downlink information reception means is the downlink information having a high priority, the newly received downlink information. Starting the data transmission process related to the downlink information at the data transmission start timing related to link information;
In-vehicle system characterized by In the in-vehicle system according to any one of claims 1 to 6,
After the downlink information receiving means has received the downlink information from the roadside device, the data transmitting means has not received the downlink information receiving means until the data transmission processing related to the received downlink information is completed. In the case where the new downlink information is received from the roadside device, the data transmission start timing related to the newly received downlink information has elapsed, and the downlink information received earlier If the data transmission process is not completed, the data transmission process related to the newly received downlink information is started after the data transmission process related to the previously received downlink information is completed. ,
The communication device
When the data transmission means starts the data transmission process after the data transmission start timing has elapsed, the delay time between the data transmission start timing and the timing to start the data transmission process is specified A delay time specifying means;
Delay time transmitting means for transmitting the delay time specified by the delay time specifying means to the control device via the transmission line;
Further comprising
In-vehicle system characterized by   A communication apparatus comprising the configuration described for the communication apparatus in the in-vehicle system according to any one of claims 1 to 7.   A control device comprising the configuration described for the control device in the in-vehicle system according to claim 1.

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