COMMUNICATION CONTROL DEVICE, COMMUNICATION CONTROL PROGRAM, AND COMMUNICATION CONTROL METHOD

Abstract

A communication control device (100A) mounted on a vehicle (300A) acquires the position of the vehicle (300A) and receives a vehicle ID, a position, and a coexistence range index (Ri) from each of the multiple rear vehicles (300B, 300C, 300D). The communication control device (100A) extracts a rear vehicle from among the multiple rear vehicles (300B, 300C, 300D) based on the position of the vehicle (300A) and the positions and coexistence range indexes (Ri) of each of the rear vehicles (300B, 300C, 300D). The communication control device (100A) determines a communication range indicating the presence range of the rear vehicle to which the sensing information (305A) is to be transmitted based on the extracted positions of the rear vehicles.

Description

[Technical field]

[0001] The present disclosure relates to a technique for determining a group of vehicles to communicate with in an inter-vehicle communication system. [Background technology]

[0002] When a moving vehicle observes information necessary for vehicle driving control, such as an accident or an obstacle, it notifies surrounding vehicles of the observed information through V2V communication. Each vehicle that receives the observed information relays the information to other vehicles. This relay allows the information to be promptly communicated to vehicles that need it. Here, the relative positions of multiple traveling vehicles change frequently, which poses a problem that communication may be interrupted between the vehicles when performing inter-vehicle communication among multiple traveling vehicles.

[0003] To solve this problem using only the communication terminals installed in the vehicles, the communication terminals need to exchange information with each other at short intervals, and each communication terminal needs to keep updating the positional relationships between the multiple vehicles. However, short-interval information exchange between vehicles requires repeated vehicle-to-vehicle communication at short intervals. This may increase the amount of traffic. To address the issue of increased traffic, there is a conventional technology in which one vehicle adjusts the communication range in which it exchanges information with another vehicle, depending on the speed and position information of the other vehicle. This conventional technology prevents problems caused by an excessive amount of communication information (for example, Patent Document 1).

[0004] However, in the patent document, the communication range for exchanging information with the other vehicle is determined by only one vehicle based on the driving status of the other vehicle. Therefore, when vehicle-to-vehicle communication is performed by applying the technology of Patent Document 1, the communication range is determined by only one vehicle, so there is a risk that the other vehicle that truly needs the information of the one vehicle will not be selected as the communication target of the one vehicle. In addition, when the communication range is determined based only on the driving status of the one vehicle, communication may be interrupted due to a change in the positional relationship of the multiple vehicles, and the information of the one vehicle may not be notified to the communication target vehicle that needs the information. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent Publication No. 2021-033558 Summary of the Invention [Problem to be solved by the invention]

[0006] The present disclosure has an object to provide vehicle-to-vehicle communication that reliably transmits information about a forward vehicle to a rear vehicle that requires the information about the forward vehicle. [Means for solving the problem]

[0007] The communication control device according to the present disclosure is mounted on a vehicle. The communication control device according to the present disclosure includes: A position acquisition unit that acquires a position of the vehicle; a receiving unit that receives, from each of a plurality of rear vehicles traveling behind the vehicle, a position of the rear vehicle and a coexistence range index that is an index indicating a coexistence range between the vehicle and the rear vehicle, and that is an index requesting the vehicle to transmit event information indicating the observed event if the vehicle observes an event while the vehicle and the rear vehicle are present in the coexistence range; a vehicle extraction unit that extracts a rear vehicle to be used for determining a communication range indicating a range in which the rear vehicle to which the event information is to be transmitted is present, from the plurality of rear vehicles, based on a position of the vehicle, a position of the rear vehicle, and the coexistence range index; a range determination unit that determines the communication range based on the extracted position of the rear vehicle; Equipped with. Effect of the Invention

[0008] According to the communication control device of the present disclosure, it is possible to provide inter-vehicle communication in which information about a forward vehicle is reliably transmitted to a rear vehicle that requires the information about the forward vehicle. [Brief description of the drawings]

[0009] [Figure 1] FIG. 1 is a diagram of a first embodiment, showing an overview of an inter-vehicle communication system 1. [Diagram 2] FIG. 2 is a diagram showing a communication relationship between communication control devices 100 according to the first embodiment. [Diagram 3] FIG. 1 is a functional block diagram of a communication control device 100 according to a first embodiment. [Figure 4] FIG. 2 is another diagram showing an overview of the inter-vehicle communication system 1 according to the first embodiment. [Diagram 5] FIG. 1 is a diagram showing a hardware configuration of a communication control device 100 according to a first embodiment. [Figure 6] FIG. 2 is a sequence diagram showing the operation of the inter-vehicle communication system 1 according to the first embodiment. [Figure 7] FIG. 1 is a flowchart showing the operation of the communication control device 100 according to the first embodiment. [Figure 8] FIG. 2 is a diagram of the first embodiment, showing vehicle extraction different from that in FIG. 1; [Figure 9] FIG. 2 is another diagram showing vehicle extraction different from that in FIG. 1 according to the first embodiment. [Figure 10] FIG. 2 is a diagram of the first embodiment, showing yet another vehicle extraction different from that in FIG. 1; [Figure 11] FIG. 11 is a diagram according to the first embodiment, showing how a communication target vehicle is viewed by a range determination unit 60A. [Figure 12] FIG. 11 is a diagram of the second embodiment, showing a sending vehicle 300F, a receiving vehicle 300A, and a receiving vehicle 300R. [Figure 13] FIG. 11 is a diagram of the second embodiment, showing a communication relationship between the communication control devices 100. [Figure 14] FIG. 11 is a functional block diagram of a communication control device 100 according to a second embodiment. [Figure 15] FIG. 11 is a hardware configuration diagram of the communication control device 100 according to the second embodiment. [Figure 16] FIG. 11 is a diagram of the second embodiment, supplementing the hardware configuration of the communication control device 100. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] In the description of the embodiments and the drawings, the same elements and corresponding elements are given the same reference numerals. Descriptions of elements given the same reference numerals are omitted or simplified as appropriate. In the following embodiments, "unit" may be read as "circuit", "step", "procedure", "process" or "circuitry" as appropriate.

[0011] (1) In the following embodiment, a plurality of vehicles 300 will appear. The plurality of vehicles 300 are equipped with a communication control device 100. For ease of explanation, the plurality of vehicles 300 will be distinguished as vehicle 300A, vehicle 300B, ..., but the plurality of vehicles 300 are treated equally. When it is not necessary to distinguish between vehicles, they will be referred to as vehicle 300. In the embodiment, the explanation will be based on vehicle 300A. (2) The communication control device 100 is also distinguished by adding A, B, ... like the vehicle 300, but multiple communication control devices 100 are equal. The communication control device 100i is mounted on the vehicle 300i (i = A, B, ...). When there is no need to distinguish, the communication control device is written as the communication control device 100. The vehicle identifier is written as the vehicle ID or ID. The information transmitted by the communication control device 100i includes the vehicle ID (i) of the vehicle 300i. The vehicle ID (i) corresponds to the source address. The other communication control device 100 that receives information from the communication control device 100i can recognize the source of the received information by the source address. Furthermore, when the vehicle 300i transmits information to a specific other vehicle 300k (k ≠ i), the vehicle ID (k) is included in addition to the ID (i). The vehicle ID (k) corresponds to the destination address. (3) In the following embodiment, there is a description that the vehicles 300 exchange information with each other. This means that the communication control devices 100 exchange information with each other. (4) In the following embodiments, information regarding vehicle 300i (i=A, B, . . .) will be expressed as vehicle ID(i), position X(F), speed V(i), coexistence range index Ri(i), communication range CA(i), information sharing group G(i), or as ID(i), X(F), V(i), Ri(i), CA(i), G(i).

[0012] Embodiment 1 A vehicle-to-vehicle communication system 1 and a communication control device 100 according to the first embodiment will be described with reference to Figs. FIG. 1 shows an overview of an inter-vehicle communication system 1. As shown in FIG. Fig. 2 shows the communication relationship between the communication control devices 100. As shown in Fig. 2, the communication control devices 100 communicate with each other on an equal footing. Fig. 3 shows a functional block diagram of the communication control device 100. The configuration of the communication control device 100 will be described later. The vehicle-to-vehicle communication system 1 is composed of a plurality of vehicles. For the sake of simplicity of explanation, in Fig. 1, the vehicle-to-vehicle communication system 1 is assumed to include four vehicles, 300A, 300B, 300C, and 300D. The communication control device 100 is mounted on the vehicle 300. Each vehicle is equipped with the communication control device 100.

[0013] Each of the vehicles 300A, 300B, 300C, and 300D is a transmitting vehicle and a receiving vehicle. The transmitting vehicle is a vehicle that transmits information about an event related to the driving control of the vehicle (transmitting vehicle) to a rear vehicle that requires the information when various sensors mounted on the vehicle observe the observed event. Event information about an event observed by the transmitting vehicle is expressed as sensing information. The sensing information is event information. The sensing information is not limited, but may be, for example, an accident, a traffic jam, an entry into an intersection, detection of a pedestrian, an entry into a junction, and the like. The receiving vehicle is a candidate vehicle that receives the sensing information from the transmitting vehicle. A vehicle that is determined to receive the sensing information from the transmitting vehicle is a communication target vehicle described later. As explained with reference to FIG. 1, the communication target vehicle is a vehicle 300 to which the sensing information should be transmitted when the vehicle 300A detects the sensing information necessary for the vehicle driving control of the vehicle 300A by a sensor group. The sensing information is transmitted by the range determination unit 60A.

[0014] The following description will be given with reference to FIG. 1. In FIG. 1, the vehicle 300A is assumed to be a transmitting vehicle. When the vehicle 300A observes sensing information 305A, the vehicle 300A transmits the sensing information 305A to the rear vehicle 300 that requires the sensing information 305A by the range determination unit 60A. In FIG. 1, various sensors of the vehicle 300A observe an event 5 as the sensing information 305A. The event 5 in FIG. 1 is a collision accident between the vehicle 300X and the vehicle 300Y. The communication control device 100A exchanges vehicle information with the communication control device 100k mounted on the vehicle 300k (k=B, C, D) by the packet transmission unit 70A and the packet reception unit 80A. The vehicle information includes the vehicle ID, the position X, the speed V, the vehicle rank, and the like for the vehicle 300. As a result, the communication control device 100k (k=B, C, D) calculates a coexistence range index Ri(k) (k=B, C, D) for requesting notification of the sensing information 305A. The coexistence range index Ri(k) (k=B, C, D) is information used by the communication control device 100A to determine whether or not to treat the vehicle 300k (k=B, C, D) as a communication target vehicle to which the sensing information 305A is to be transmitted. Details of the coexistence range index Ri will be described later.

[0015] The communication control device 100k (k=B, C, D) transmits a coexistence range index Ri(k) (k=B, C, D) to the vehicle 300A traveling in the same direction. The coexistence range index Ri(k) (k=B, C, D) is an information transmission request from the communication control device 100k (k=B, C, D) to the vehicle 300A.

[0016] The vehicle 300A recognizes the position X(k) (k=B, C, D) of the vehicle 300k (k=B, C, D) through vehicle-to-vehicle communication of vehicle information. The vehicle 300A also broadcasts the vehicle information 302A. When the vehicle 300A receives the coexistence range index Ri(k) (k=B, C, D), the vehicle 300A determines whether the corresponding range R(k) (k=B, C, D) corresponding to the coexistence range index Ri(k) (k=B, C, D), which is considered to be fixed to the vehicle 300k (k=B, C, D), is included in the forward sensing range 301A of the vehicle 300A, based on the position X(A), the position X(k) (k=B, C, D), and the coexistence range index Ri(k) (k=B, C, D). The corresponding range R(k) will be described later in <Calculation method of coexistence range index Ri>. Based on this determination, the vehicle extraction unit 50A extracts the rear vehicles to be used in determining the communication range CA(A) from the vehicles 300k (k=B, C, D). In FIG. 1, the vehicles 300B and 300C are extracted. Note that the determination method using this corresponding range R(k) is an example. The vehicles extracted by the vehicle extraction unit 50A are referred to as extracted vehicles.

[0017] The range determination unit 60A determines the communication range CA(A) in which communication is required, from the vehicle 300A to the extracted vehicle with the furthest relative distance. In FIG. 1, the range determination unit 60A determines the communication range CA(A) in which communication is required, from the vehicle 300A to the extracted vehicle 300C with the furthest relative distance. The range determination unit 60A sets an information sharing group G(A), which is a vehicle group that notifies the sensing information 305A, from the communication range CA(A). In FIG. 1, the vehicles 300B, 300C, and 300D are set in the information sharing group G(A). Note that the vehicle 300D is not an extracted vehicle, but is located in the communication range CA(A). Therefore, the range determination unit 60A sets the vehicle 300D in the information sharing group G(A). The vehicles set in the information sharing group G(A) are communication target vehicles of the vehicle 300A. The communication target vehicles of the vehicle 300A are vehicles from which the sensing information 305A is transmitted from the vehicle 300A. The range determination unit 60A notifies the vehicle 300B, the vehicle 300C, and the vehicle 300D located in the communication range CA(A) of the information sharing group G(A) and the communication range CA(A). The information sharing group G(A) is a group of vehicle IDs of the communication target vehicles set in the information sharing group G(A). The notified communication range CA(A) will be described later.

[0018] As a result of the above, when the vehicle 300A observes the sensing information 305A, a communication target vehicle to which the sensing information 305A should be transmitted is determined.

[0019] ***Configuration Description*** Each functional unit of the communication control device 100A will be described with reference to Fig. 3. The communication control device 100A includes a signal processing unit 10A, a position acquisition unit 20A, a speed acquisition unit 30A, an index calculation unit 40A, a vehicle extraction unit 50A, a range determination unit 60A, a packet transmission unit 70A, and a packet reception unit 80A.

[0020] The communication control device 100A transmits the following information (1) to (6) to the other communication control device 100 through inter-vehicle communication. (1) vehicle ID (A) of vehicle 300A; (2) Position X(A) of vehicle 300A; (3) The speed of vehicle 300A is V(A), (4) a coexistence range index Ri(A) for vehicle 300A; (5) Communication range CA(A), (6) Information Sharing Group G(A). The vehicle ID(A), the position X(A), and the speed V(A) are transmitted as vehicle information 302A of the vehicle 300A. The vehicle information 302A is transmitted periodically or irregularly, separately from the coexistence range index Ri(A), the communication range CA(A), and the information sharing group G(A).

[0021] <Signal processing unit 10A> The signal processing unit 10A converts the position X(A) output by the position acquisition unit 20A, the speed V(A) output by the speed acquisition unit 30A, the coexistence range index Ri(A) output by the index calculation unit 40A, and the communication range CA(A) and information sharing group G(A) output by the range determination unit 60A into signals that can be transmitted by the packet transmission unit 70A. The signal processing unit 10A outputs each piece of converted information to the packet transmission unit 70A. The signal processing unit 10A converts the information received by the packet reception unit 80A into signals that can be processed by the index calculation unit 40A, the vehicle extraction unit 50A, and the range determination unit 60A. The packet receiving unit 80A receives the ID(k), position X(k), and coexistence range index Ri(k) of each of the multiple rear vehicles 300(k) (k=B, C, D) traveling behind the vehicle 300A. Furthermore, when the vehicle 300A is a communication target vehicle, the vehicle receiving unit 80A receives the vehicle ID, position X, speed V, communication range CA, information sharing group G, etc. from the vehicle ahead of the vehicle 300A. The packet receiving unit 80A inputs the received information to the signal processing unit 10A. The signal processing unit 10A converts the input vehicle ID, position X, speed V, coexistence range index Ri, communication range CA, and information sharing group G into a format that can be processed by the index calculation unit 40A and the vehicle extraction unit 50A.

[0022] <Position acquisition unit 20A> The position acquisition unit 20A acquires the position X(A) of the vehicle 300A. The position acquisition unit 20A receives a positioning signal transmitted by a positioning satellite by the antenna 29A. The position acquisition unit 20A calculates the position X(A) of the vehicle 300A using the received positioning signal. The position acquisition unit 20A outputs the position X(A), which is the positioning result, to the signal processing unit 10A, the index calculation unit 40A, and the vehicle extraction unit 50A.

[0023] <Speed ​​acquisition unit 30A> The speed acquisition unit 30A acquires the speed V(A) of the vehicle 300A calculated based on the signal output from the vehicle speed sensor 39A. The speed acquisition unit 30A outputs the speed V(A) to the signal processing unit 10A and the index calculation unit 40A.

[0024] <Indicator calculation section 40A> Assuming that a vehicle traveling ahead of the vehicle 300A observes an event, the index calculation unit 40A calculates a coexistence range index Ri(A) based on an avoidance time for the vehicle 300A, which is a vehicle behind the vehicle traveling ahead of the vehicle 300A, to avoid the event. The index calculation unit 40A then transmits the coexistence range index Ri(A) to the vehicle traveling ahead using the packet transmission unit 70A. The traveling time T(A) in (Equation 2) described later is the avoidance time. The index calculation unit 40A calculates the coexistence range index Ri(A). FIG. 4 is a diagram in which the position of the vehicle 300A and the position of the vehicle 300B are exchanged in FIG. 1. In FIG. 4, the vehicle 300B is a transmitting vehicle, and the vehicle 300A is a receiving vehicle. Assume that the vehicle 300A is a receiving vehicle. With reference to FIG. 4, the calculation of the coexistence range index Ri(A) by the index calculation unit 40A will be described. The index calculation unit 40A calculates the coexistence range index Ri(A) for the vehicle 300A using the speed V(A) of the vehicle 300A input from the speed acquisition unit 30A, the speeds V(k) (k=C, D) of the surrounding vehicles 300C and 300D input from the signal processing unit 10A, and the travel time T(A) for the vehicle 300A. The coexistence range index Ri(A) is also information that the vehicle 300A requests the forward vehicle to transmit sensing information detected by the forward vehicle. In FIG. 4, the vehicle 300B is the vehicle to which the sensing information is requested. The index calculation unit 40A outputs the coexistence range index Ri(A) to the signal processing unit 10A. The coexistence range index Ri(A) is transmitted to the vehicle 300B via the signal processing unit 10A and the packet transmission unit 70A. The coexistence range index Ri(A) will be described in detail in step S14 of FIG. 7.

[0025] <Vehicle extraction unit 50A> Consider FIG. 1. Vehicle 300A is a transmitting vehicle. Vehicle extraction unit 50A extracts, from the multiple rear vehicles, a rear vehicle to be used for determining a communication range CA(A) indicating the range of existence of the rear vehicle to which event information should be transmitted. Vehicle extraction unit 50A extracts, from the multiple rear vehicles, a rear vehicle to be used for determining the communication range CA(A) based on the position of vehicle 300A, the positions of each rear vehicle, and the coexistence range index Ri of each rear vehicle. Here, the event information is sensing information. In extracting the vehicles, the vehicle extraction unit 50A determines whether the vehicle 300A and the rear vehicle 300(k) coexist in the coexistence range indicated by the coexistence range index Ri for each rear vehicle. The vehicle extraction unit 50A extracts the rear vehicle determined to coexist as a rear vehicle to be used in determining the communication range CA(A). The vehicle 300A is further equipped with a group of sensors having a detection range for detecting an event occurring in front of the vehicle 300A. The vehicle extraction unit 50A determines whether there is an overlapping range between the coexistence range fixed to the rear vehicle and the detection range (front sensing range 301A) of the vehicle 300A for each rear vehicle. The vehicle extraction unit 50A extracts the rear vehicle determined to have an overlapping range as a rear vehicle to be used in determining the signal range CA(A). A specific description will be given below. The case of FIG. 1 will be considered. The vehicle extraction unit 50A extracts vehicles to be used in determining the communication range CA(A) using the position X(A), the position X(k) (k=B, C, D), and Ri(k) (k=B, C, D). The vehicle extraction unit 50A extracts vehicles to be used in determining the communication range CA(A) from the surrounding vehicles 300k (k=B, C, D) using the position X(A), the position X(k) input from the signal processing unit 10A, and the coexistence range index Ri(k). The vehicle extraction unit 50A inputs a group EV(A) consisting of pairs of IDs and positions of the extracted vehicles to the range determination unit 60A. EV(A) = {[ID(B), X(B)], [ID(C), X(C)]}. Details will be explained in step S16 of FIG.

[0026] <Range determination unit 60A> The range determination unit 60A determines the communication range CA(A) based on the positions of the following vehicles extracted by the vehicle extraction unit 50 A. Here, the range determination unit 60A determines the communication range CA(A) based on the position of the following vehicle that is located farthest from the position X(A) of the vehicle 300A among the extracted following vehicles. A specific description will be given below. Consider FIG. 1. The range determination unit 60A calculates a communication range CA(A) for the vehicle 300A based on the position X indicated by the EV(A) input from the vehicle extraction unit 50A. The range determination unit 60A determines the communication range CA(A) for the vehicle 300A using the positions X(B) and X(C) input from the vehicle extraction unit 50A. The method of determining the communication range CA(A) will be described in detail later. The range determination unit 60A inputs the communication range CA(A) to the signal processing unit 10A. The signal processing unit 10A converts the communication range CA(A) into a format that can be processed by the packet transmission unit 70, and inputs the converted communication range CA(A) to the packet transmission unit 70.

[0027] <Packet transmitting unit 70A> The packet transmitting unit 70A is a transmitting unit. The packet transmitting unit 70A transmits sensing information to a communication target vehicle. The packet transmitting unit 70A transmits information input from the signal processing unit 10A to the communication control device 100 mounted on another vehicle 300. The packet transmitting unit 70A transmits at least the following information (1) to (6). (1) ID(A) of vehicle 300A; (2) Position X(A) of vehicle 300A; (3) The speed of vehicle 300A is V(A), (4) A coexistence range index Ri(A) transmitted to the vehicle ahead; (5) A communication range CA(A) transmitted to the rear vehicle; (6) Information Sharing Group G(A). The information (1) to (3) is transmitted as vehicle information 302A. The coexistence range index Ri(A) (4) is transmitted from vehicle 300A to vehicle 300B, which is the leading vehicle, in Fig. 4. The communication range CA(A) and information sharing group G(A) (5) and (6) are transmitted from vehicle 300A to vehicles 300B, 300C, and 300D, which are the trailing vehicles, in Fig. 1.

[0028] <Packet receiving unit 80A> The packet receiving unit 80A is a receiving unit. The packet receiving unit 80A receives, from each of a plurality of rear vehicles traveling behind the vehicle 300A, an identifier of the rear vehicle, the position of the rear vehicle, and a coexistence range indicator transmitted by the rear vehicle of the vehicle 300A. Specifically, the packet receiving unit 80A receives the following information (1) to (6) from a communication control device 100k mounted on another vehicle 300k. The packet receiving unit 80A outputs this information to the signal processing unit 10A. (1) ID(k), (2) position X(k), (3) Speed ​​V(k), (4) Coexistence range index Ri(k), (5) communication range CA, (6) Information Sharing Group G. The information (1) to (3) is received as vehicle information 302k (k=B, C, D). The coexistence range index Ri(k) (k=B, C, D) (4) is received from the rear vehicles 300B, 300C, and 300D in Fig. 1. The communication range CA and information sharing group G (5)) and (6) are received from the front vehicle 300B in Fig. 4.

[0029] ***Hardware Configuration Description*** Fig. 5 shows a hardware configuration of the communication control device 100. The hardware configuration of the communication control device 100 will be described with reference to Fig. 5.

[0030] The communication control device 100 is a computer. The communication control device 100 includes a processor 110. The communication control device 100 includes multiple pieces of hardware in addition to the processor 110. The multiple pieces of hardware are a main memory device 120, an auxiliary memory device 130, an input IF 140, an output IF 150, and a communication IF 160. IF indicates an interface. The processor 110 is connected to the other hardware via a signal line 170 and controls the other hardware.

[0031] The communication control device 100 includes, as functional elements, a signal processing unit 10, a position acquisition unit 20, a speed acquisition unit 30, an index calculation unit 40, a vehicle extraction unit 50, a range determination unit 60, a packet transmission unit 70, and a packet reception unit 80. The functions of the signal processing unit 10, the position acquisition unit 20, the speed acquisition unit 30, the index calculation unit 40, the vehicle extraction unit 50, the range determination unit 60, the packet transmission unit 70, and the packet reception unit 80 are realized by a communication control program 131.

[0032] The processor 110 is a device that executes a communication control program 131. The processor 110 executes the communication control program 131 to realize the functions of a signal processing unit 10, a position acquisition unit 20, a speed acquisition unit 30, an index calculation unit 40, a vehicle extraction unit 50, a range determination unit 60, a packet transmission unit 70, and a packet reception unit 80. The processor 110 is an IC (Integrated Circuit) that performs arithmetic processing. Specific examples of the processor 110 are a CPU (Central Processing Unit), a DSP (Digital Signal Processor), and a GPU (Graphics Processing Unit).

[0033] The main memory 120 is a storage device. Specific examples of the main memory 120 include a static random access memory (SRAM) and a dynamic random access memory (DRAM). The main memory 120 holds the results of calculations by the processor 110.

[0034] The auxiliary storage device 130 is a storage device that stores data in a non-volatile manner. A specific example of the auxiliary storage device 130 is a hard disk drive (HDD). The auxiliary storage device 130 may also be a portable recording medium. Examples of portable recording media include a Secure Digital (SD) memory card, a NAND flash, a flexible disk, an optical disk, a compact disk, a Blu-ray (Blu-ray) disk, and a digital versatile disk (DVD). The auxiliary storage device 130 stores a communication control program 131.

[0035] The input IF 140 is a port through which data is input from each device. The output IF 150 is connected to various devices. The output IF 150 is a port through which the processor 110 outputs data to the various devices. The communication IF 160 is a communication port through which the processor communicates with other communication control devices 100. The communication IF 160 is also a communication port through which the processor communicates with various sensors.

[0036] The processor 110 loads the communication control program 131 from the auxiliary storage device 130 to the main storage device 120. The processor 110 reads the loaded communication control program 131 from the main storage device 120 and executes it. In addition to the communication control program 131, an OS (Operating System) is also stored in the main storage device 120. The processor 110 executes the communication control program 131 while executing the OS. The communication control device 100 may include multiple processors that replace the processor 110. These multiple processors share the execution of the communication control program 131. Each processor is a device that executes the communication control program 131, just like the processor 110. Data, information, signal values, and variable values ​​used, processed, or output by the communication control program 131 are stored in the main storage device 120, the auxiliary storage device 130, or a register or cache memory in the processor 110.

[0037] The communication control program 131 is a program that causes a computer to execute each process, procedure, or step of the signal processing unit 10, position acquisition unit 20, speed acquisition unit 30, index calculation unit 40, vehicle extraction unit 50, range determination unit 60, packet transmission unit 70, and packet reception unit 80, where "part" is replaced with "process," "procedure," or "step."

[0038] The method is performed by the communication control device 100, which is a computer, executing the communication control program 131. The communication control program 131 may be provided by being stored in a computer-readable recording medium, or may be provided as a program product.

[0039] ***Explanation of Operation*** FIG. 6 shows a sequence illustrating the operation of the inter-vehicle communication system 1. As shown in FIG. Fig. 7 shows a flowchart of the communication control device 100. The operation of the communication control device 100 will be described with reference to Figs. 6 and 7. The operation of the communication control device 100 corresponds to a communication control method. The operation of the communication control device 100 is executed by a communication control program 131.

[0040] Vehicle 300A transmits vehicle information 302A including vehicle ID (A), position X (A) and speed V (A) to vehicles 300k (k=B, C, D) traveling in the vicinity. Similarly, vehicle 300A receives vehicle information 302k (k=B, C, D) from vehicles 300k (k=B, C, D). In this way, each vehicle 300 collects the positions X and speeds V of other vehicles located within a communication range.

[0041] <Steps S11 and S12> The following description focuses on vehicle 300A. Assume the state shown in FIG. 1. In the communication control device 100A, the packet transmitting unit 70A broadcasts vehicle ID (A) (step S11). The packet receiving unit 80A determines whether there is a response to the broadcasted ID (A) (step S12). If there is no response, the process returns to step S11 (NO in step S12). If there is a response, the packet receiving unit 80 recognizes that the responding vehicle is located within a communication range. In the case of FIG. 1, it is assumed that there is a response from vehicle 300k (k=B, C, D).

[0042] <Step S13> Assume the state in Fig. 1. In step S13, the packet transmitting unit 70A exchanges vehicle information with the vehicles 300k (k = B, C, D) that have responded. The vehicle 300A transmits vehicle information 302A to the vehicles 300k (k = B, C, D). The vehicle 300A also receives vehicle information 302B, vehicle information 302C, and vehicle information 302D from each of the vehicles 300k (k = B, C, D).

[0043] <Step S14> Consider a vehicle 300A in the position of FIG.

[0044] <Travel time T(A)> The user inputs "travel time T(A)" to the index calculation unit 40A through the input unit 49A. The travel time T(A) is calculated by dividing the travel time T(A) by the travel time V * If the speed V * indicates the time to continue running. Speed ​​V * is sometimes expressed as a constant speed. The traveling time T(A) is input from the input unit 49A, but may be set fixedly for each vehicle 300. The index calculation unit 40A receives the speed V(k) (k=B, C, D) from the packet receiving unit 80A and the speed V(A) from the speed acquisition unit 30A. The index calculation unit 40A calculates a coexistence range index Ri(A) from the traveling time T(A), the speed V(k) (k=B, C, D), and the speed V(A). The coexistence range index Ri(A) is calculated using the following equation 1. Ri(A)=F1(V(A),V(B),V(C),V(D),T(A)) (Formula 1) F1 shows the process for finding Ri(A). The running time is calculated by "speed V * The time (in seconds) indicates how many seconds ahead information on the location ahead is needed in order to allow vehicle 300A traveling at a certain speed to avoid an obstacle that occurs ahead of vehicle 300A with ample time to maneuver.

[0045] <Calculation method of coexistence range index Ri> A specific method for calculating the coexistence range index Ri(A) by the index calculation unit 40A will be described. The coexistence range index Ri is an index indicating the coexistence range between a front vehicle and a rear vehicle. At the same time, the coexistence range index Ri is an index that requests the front vehicle to transmit event information indicating the observed event if the front vehicle observes an event while the front vehicle and the rear vehicle are in the coexistence range. More specifically, the coexistence range index Ri(A) is an index indicating the coexistence range between the front vehicle and the rear vehicle 300A, and is an index accompanied by a transmission request from the vehicle 300A to transmit event information related to the observed event to the rear vehicle 300A when various sensors mounted on the front vehicle observe an event related to the driving control of the front vehicle while the front vehicle and the rear vehicle 300A are present in the coexistence range. That is, the coexistence range index Ri(A) is an index indicating the coexistence range between the front vehicle and the rear vehicle 300A, and is also a transmission request from the rear vehicle 300A to the front vehicle for sensing information. An example of a specific method of calculating the coexistence range index Ri(A) is the following Equation 2. As shown in Equation 2, the index calculation unit 40A calculates the constant speed V * and the travel time T(A), is calculated as the coexistence range index Ri(A). Coexistence range index Ri(A) = constant speed V * (m / sec) x traveling time T(A)(sec) (Formula 2) Constant speed V * teeth, (1) The speed V(A) of vehicle 300A while it is traveling, (2) the average speed of multiple surrounding vehicles, excluding vehicle 300A; (3) the overall average speed of the surrounding vehicles, including the currently moving vehicle 300A; (4) A fixed, pre-specified speed; Here, the surrounding vehicles are vehicles 300k (K=C, D). The surrounding vehicles may include the forward vehicle 300B. As described above, the constant speed is any one of the speed of the traveling vehicle 300A, the average speed of multiple surrounding vehicles traveling around the vehicle 300A, the overall average speed of the traveling vehicle 300A and the multiple surrounding vehicles, and a speed specified as a fixed value. In addition, the coexistence range index Ri(A) is a length. In FIG. 4, the vehicle extraction unit 50B of the vehicle 300B that receives the coexistence range index Ri(A) from the vehicle 300A recognizes the range R(A) corresponding to the coexistence range index Ri(A) from the coexistence range index Ri(A) by the following method. Hereinafter, the range R(A) is referred to as the corresponding range. That is, the vehicle extraction unit 50B recognizes a rectangle having the coexistence range index Ri(A) obtained by the formula 2 as the long side as the corresponding range R(A). The vehicle extraction unit 50B uses the lane width of the lane in which the vehicle 300B is traveling as the short side of the rectangle. FIG. 4 shows the lane width 306B used by the vehicle extraction unit 50B. The lane width 306B may be set in advance by the user in the vehicle extraction unit 50B, or may be detected by an imaging device such as a camera among the sensor group of the vehicle 300B. This conversion of the coexistence range index Ri(A) into the corresponding range R(A) is used by the vehicle extraction unit 50A in converting the coexistence range index Ri(B) into the corresponding range R(B) in step S16.

[0046] <Step S15> The signal processing unit 10A converts the coexistence range index Ri(A) calculated by the index calculation unit 40A into a format that can be processed by the packet transmission unit 70A and inputs it to the packet transmission unit 70A. The packet transmission unit 70A transmits the coexistence range index Ri(A) together with the ID(A) to the vehicle ahead traveling in the same traveling direction as the vehicle 300A. In this way, the index calculation unit 40A transmits the coexistence range index Ri(A) together with the ID(A) via the packet transmission unit 70A to the vehicle ahead traveling in the same traveling direction as the vehicle 300A. For example, in the state of Fig. 4, the packet transmission unit 70A transmits a set of ID(A) and coexistence range index Ri(A) to the vehicle ahead 300B. The packet transmission unit 70A can identify the vehicle ahead 300B traveling in the same direction as the vehicle 300A, based on vehicle information received periodically or irregularly from the surrounding vehicles. This completes the generation and transmission of the coexistence range index Ri(A) by the vehicle 300A.

[0047] <Step S16> Step S16 is a process of extracting a vehicle to be used in determining the communication range CA(A). Steps S16 to S19 are processes performed when the vehicle 300A receives a requested range Ri(k) (k=B, C, D) from the surrounding vehicle 300k (k=B, C, D). In steps S16 to S19, the state of FIG. 1 is assumed. That is, the vehicle 300A is a sending vehicle. In step S16, the vehicle extraction unit 50A extracts a vehicle to be used in determining the communication range CA(A). As shown in FIG. 3, the packet receiving unit 80A receives the coexistence range index Ri(k) (k=B, C, D) and the position X(k) (k=B, C, D) from the vehicle 300k (k=B, C, D). The packet receiving unit 80A inputs these to the signal processing unit 10A. The signal processing unit 10A inputs the coexistence range index Ri(k) and the position X(k) to the vehicle extraction unit 50A, where k=B, C, D. The position acquisition unit 20A inputs the position X(A) to the vehicle extraction unit 50A.

[0048] The vehicle extraction unit 50A uses the coexistence range index Ri(k) (k=B, C, D), the position X(k) (k=B, C, D), and the position X(A) to extract vehicles to be used in determining the communication range CA(A) from Equation 3. EV(A)=F3(X(k),Ri(k),X(A)) (Equation 3) F3 shows a process for calculating EV(A). In FIG. 1, EV(A) is the vehicle 300B and the vehicle 300C. That is, as a result of (Equation 3), EV(A)={[ID(B), X(B)], [ID(C), X(C)]} The vehicle extraction unit 50A inputs EV(A) to the range determination unit 60A.

[0049] <How to extract vehicles> The vehicle extraction unit 50A extracts vehicles as follows. The vehicle extraction unit 50A extracts a rear vehicle 300k whose corresponding range R(k) (k=B, C, D) of the coexistence range index Ri(k) overlaps with a forward sensing range 301A of the vehicle 300A that can be sensed by various sensors mounted on the vehicle 300A. A description will be given with reference to FIG. 1. Focus on the vehicle 300B. The vehicle extraction unit 50A recognizes the position X(B), speed V(B) and traveling direction of the vehicle 300B by exchanging vehicle information 302A and vehicle information 302B. The vehicle extraction unit 50A also recognizes the coexistence range index Ri(B), position X(A) and forward sensing range 301A. The forward sensing range 301A is a range relative to the body of the vehicle 300A. The vehicle extraction unit 50A places one end of the coexistence range index Ri(B) at the position X(B) so that the coexistence range index Ri(B) starts from the position X(B) and faces the traveling direction of the vehicle 300B. The vehicle extraction unit 50A places a rectangle so that one end of the coexistence range index Ri(B) is the midpoint of the short side of the rectangle. This rectangle is the corresponding range R(B). The vehicle extraction unit 50A determines whether the corresponding range R(B) has an overlapping range with the forward sensing range 301A. In FIG. 1, the corresponding range R(B) has an overlapping range with the forward sensing range 301A. In this case, the vehicle extraction unit 50A extracts the vehicle 300B. In FIG. 1, the vehicle 300C is also extracted by the vehicle extraction unit 50A. On the other hand, in the vehicle 300D, the corresponding range R(D) does not have an overlapping range with the forward sensing range 301A. In this case, the vehicle extraction unit 50A does not extract the vehicle 300D.

[0050] In the above method, a vehicle is extracted based on whether or not the corresponding range R(B) corresponding to the coexistence range index Ri has an overlapping range with the forward sensing range 301A. This is just an example, and the method is not limited to this method. Fig. 8 shows another example of vehicle extraction. A transmitting vehicle 300A recognizes a position X(A), a position X(B), and a coexistence range index Ri(B). Therefore, as shown in Fig. 8, the vehicle extraction unit 50A may extract a vehicle based on whether or not the position X(A) is inside a circle 303B having the position X(B) as the center and the coexistence range index Ri(B) as the radius. If the position X(A) is inside the circle 303B, the vehicle 300B is extracted. Fig. 9 shows yet another example of vehicle extraction. As shown in Fig. 9, the vehicle extraction unit 50A may extract a vehicle based on whether or not the position X(B) is present inside a circle 303A having the position X(A) as the center and the coexistence range index Ri(B) as the radius. If the position X(B) is present inside the circle 303A, the vehicle 300B is extracted. Note that in the cases of Figs. 8 and 9, the forward sensing range 301A is not used, and therefore the coexistence range index Ri(B) used as the radius may be corrected to be shorter by the amount that the forward sensing range 301A is not used.

[0051] FIG. 10 shows a method similar to the method using the correspondence range R. FIG. 10 shows yet another example of vehicle extraction. FIG. 10 shows a transmitting vehicle 300A and a receiving vehicle 300B. The vehicle extraction unit 50A determines a specific range Ri-B for the vehicle 300B from the coexistence range index Ri(B). For example, the vehicle extraction unit 50A has correspondence information in which the range Ri is determined using the coexistence range index Ri as an index, and determines a specific range Ri-B from the coexistence range index Ri(B). Then, the vehicle extraction unit 50A determines whether the range Ri-B has an overlapping range with the forward sensing range 301A. If there is an overlapping range, the vehicle extraction unit 50A extracts the vehicle 300B.

[0052] 1, vehicle extraction unit 50A extracts vehicles 300B and 300C from vehicles 300B to 300D as vehicles to be used in determining communication range CA(A). Vehicle extraction unit 50A outputs ID(B), ID(C) and position X(B) and position X(C) of extracted vehicles 300B and 300C to range determination unit 60A.

[0053] <Step S17> In step S17, range determination unit 60A determines communication range CA(A) using the following equation 4. CA(A)=F4(X(k),X(A)) (Eq. 4) F4 indicates a process for obtaining CA(A). Here, X(k) is the position X(B) and the position X(C). The range determination unit 60A determines the extracted vehicle with the furthest relative distance from the position X(A) based on the position X(B) and the position X(C) of the extracted vehicle 300B and the extracted vehicle 300C, which are extracted by the vehicle extraction unit 50A, and the position X(A) of the vehicle 300A. In FIG. 1, the range determination unit 60A judges the vehicle 300C as the extracted vehicle with the furthest relative distance. The range determination unit 60A determines the communication range CA(A) that requires communication based on the distance from the position X(A) to the extracted vehicle 300C with the furthest relative distance. In FIG. 1, in a circle 304C centered at the position X(A) and with a radius of the length between the position X(A) and the position X(C), the inside of the circle 304C including the vehicle 300A is the communication range CA(A) of the vehicle 300A.

[0054] <Step S18> In step S18, the range determination unit 60A sets an information sharing group G(A). The range determination unit 60A sets the vehicles 300 present inside the communication range CA(A) as the information sharing group G(A). In FIG. 1, the range determination unit 60A sets the vehicles 300B, 300C, and 300D as the information sharing group G(A). Although the vehicle 300D is not an extracted vehicle, it is located in the communication range CA(A) and is therefore set to the information sharing group G(A).

[0055] <Step S19> Please refer to FIG. 1. In step S19, the range determination unit 60A transmits the ID(A), the communication range CA(A), and the information sharing group G(A) to each of the communication target vehicles 300B, 300C, and 300D as destinations. That is, the range determination unit 60A transmits the vehicle ID(A), the information sharing group G(A), and the value of the communication range CA(A) to the vehicle 300B, the vehicle 300C, and the vehicle 300D via the signal processing unit 10A and the packet transmission unit 70A. The information sharing group G(A) is a group of vehicle IDs set in the information sharing group G(A). The value of the communication range CA(A) is, for example, information on a circle 304C whose center is the position X(A) and whose radius is the length between the positions X(A) and X(C).

[0056] <Step S20> First, the case where the vehicle 300A is the receiving vehicle will be described. See FIG. 4. In step S20, the index calculation unit 40A determines whether there is a change in the positional relationship between the vehicle 300A and the surrounding vehicles 300B, C, and D. The transmitting vehicle 300B is also a surrounding vehicle 300. The position X(k) (k=B, C, D) and the position X(A) are input to the index calculation unit 40A periodically or irregularly. This makes it possible to detect a change in the positional relationship. Specifically, the index calculation unit 40A receives ID(k), X(k), V(k), X(A), and V(A). If a change in the positional relationship is detected (YES in step S20), the process returns to step S11. If no change in the positional relationship is detected (NO in step S20), the process proceeds to step S21. Next, step S20 will be described when vehicle 300A is the transmitting vehicle. Please refer to FIG. 1. When vehicle 300A is the transmitting vehicle, there is a possibility that transmitting vehicle 300A may become a receiving vehicle due to a change in the positional relationship with surrounding vehicles. Index calculation unit 40A determines whether there has been a change in the positional relationship between vehicle 300A and surrounding vehicles 300B, C, D. Position X(k) (k=B, C, D) and position X(A) are input to index calculation unit 40A periodically or irregularly. If a change in the positional relationship is detected (YES in step S20), the process returns to step S11. If no change in the positional relationship is detected (NO in step S20), the process proceeds to step S21. Note that the case where a notification in step S22 is received from another vehicle 300 also corresponds to the "change detection" in step S20. Therefore, when a notification in step S22 is received from another vehicle 300, the index calculation unit 40A returns the process to step S11.

[0057] <Step S21> First, the case where the vehicle 300A is the receiving vehicle will be described. See FIG. 4. In step S21, the index calculation unit 40A determines whether or not a trigger has occurred that changes the positional relationship of the vehicle 300A with the surrounding vehicles 300k (k=B, C, D). If a trigger has occurred (YES in step S21), the process proceeds to step S22. In step S22, the index calculation unit 40A transmits the fact of the change in the positional relationship of the vehicle 300A and the vehicle information 302A to the surrounding vehicles 300k (k=B, C, D) via the packet transmission unit 70A. If a trigger has not occurred (NO in step S21), the process proceeds to step S20. Next, the case where vehicle 300A is the transmitting vehicle in step S21 will be described. See FIG. 1. In step S21, similar to the case of a receiving vehicle, index calculation unit 40A determines whether or not a trigger has occurred that causes a change in the positional relationship of vehicle 300A with surrounding vehicles 300k (k=B, C, D). If a trigger has occurred (YES in step S21), processing proceeds to step S22. In step S22, similar to the case of a receiving vehicle, the fact of the change in the positional relationship of vehicle 300A and vehicle information 302A are transmitted to surrounding vehicles 300k (k=B, C, D). If a trigger has not occurred, processing proceeds to step S20. Since the originating vehicle is traveling at the front, the originating vehicle can detect the occurrence of the trigger and transmit the signal in step S22 first.

[0058] As shown in steps S20 and S21, when the receiving vehicle 300A detects a change in the positional relationship with the surrounding vehicles 300k (k=B, C, D), the process returns to step S11. Then, the index calculation unit 40A recalculates the coexistence range index Ri(A) in step S14.

[0059] <Recalculation of the coexistence range index Ri(A)> The recalculation of the coexistence range index Ri(A) for the receiving vehicle 300A will be described in more detail with reference to FIG. 4. The communication control device 100A recalculates the coexistence range index Ri(A) when the speed of any of the vehicle 300A and the surrounding vehicles 300k (k=B, C, D) changes, or when the positional relationship between the vehicle 300A and the surrounding vehicles 300k (k=B, C, D) changes. The communication control device 100A can detect the change in speed and the change in the positional relationship by the vehicle information 302A, 302k (k=B, C, D) that is transmitted and received periodically or irregularly, the position acquisition unit 20A, and the speed acquisition unit 30A. Recalculation of the coexistence range index Ri(A) can be triggered by acceleration / deceleration of the vehicle 300A, a change in the driving route of the vehicle 300A, entry of the vehicle 300A into a point where the positional relationship with other vehicles is likely to change, such as entry into an intersection, or a change in the driving state of the vehicle 300A. Alternatively, the communication control device 100A may recalculate the coexistence range index Ri(A) by periodically or irregularly performing the calculation operation of the coexistence range index Ri, which starts with the packet transmitting unit 70A and the packet receiving unit 80A transmitting and receiving the vehicle ID with surrounding vehicles and transmitting and receiving the vehicle information.

[0060] In this way, the index calculation unit recalculates the coexistence range index periodically or irregularly, and transmits the recalculated coexistence range index via the packet transmission unit 70A.

[0061] Please refer to FIG. 4. When the relative speed ΔV between any of the speeds V(k) (k=B, C, D) acquired from the surrounding vehicles 300k (k=B, C, D) as vehicle information and the speed V(A) of the vehicle 300A is greater than a preset threshold TH, the communication control device 100A of the receiving vehicle 300A periodically or irregularly recalculates the coexistence range index Ri(A) and notifies the front of the vehicle 300A. As a result, the transmitting vehicle 300B updates the communication range CA and the information sharing group G. This is because there is a risk of communication interruption of the sensing information exchanged between the vehicles 300B and 300A when the receiving vehicle 300A, which is located in the communication range CA(B) of the transmitting vehicle 300B, moves outside the communication range CA(B) due to acceleration / deceleration or a change in driving lane. The communication interruption will be explained in more detail in FIG. 11. Fig. 11 shows how communication target vehicles are viewed by range determination unit 60A. Fig. 11 corresponds to Fig. 1. The communication target vehicles are vehicles 300B, 300C, and 300D. Vehicle 300D is not extracted by vehicle extraction unit 50A, but is located in communication range CA(A). Therefore, vehicle 300D is also recognized as a communication target vehicle by range determination unit 60A. The range determination unit 60A monitors the positions of the vehicles 300B, 300C, and 300D based on the positions X(B), X(C), and X(D) included in the vehicle information 302B, 302C, and 302D. For example, when the receiving vehicle 300B moves outside the communication range CA(A) due to acceleration / deceleration or a change in lane, the sensing information 305A is no longer transmitted to the receiving vehicle 300B. In this way, movement outside the communication range CA(A) may cause a communication interruption for the vehicle 300B.

[0062] ***Advantages of the First Embodiment*** In the inter-vehicle communication system 1 of the first embodiment, the receiving vehicle transmits the coexistence range index Ri(A) to the transmitting vehicle, and when the transmitting vehicle determines that the receiving vehicle is a communication target vehicle, the transmitting vehicle transmits sensing information to the communication target vehicle. Therefore, the sensing information of the forward vehicle can be reliably transmitted to a rear vehicle that truly requires the sensing information of the forward vehicle. Furthermore, since the vehicles to which the sensing information is transmitted can be limited, the communication device resources of the vehicles belonging to the inter-vehicle communication system 1 can be utilized efficiently. In addition, the receiving vehicle recalculates the coexistence range index Ri(A) and transmits it to the transmitting vehicle (YES in steps S20, YES in S21, YES in S11, S12, S14, S15), thereby preventing communication interruption of the sensing information exchanged between the transmitting vehicle and the communication target vehicle.

[0063] <Variation 1> A first modified example of the communication control device 100A will be described below. The range determination unit 60A may determine the communication range CA(A) based on the speed V(A) of the vehicle 300A or the maximum speed of the road on which the vehicle 300A is traveling, without collecting the coexistence range index Ri(k) from the surrounding vehicles 300k, and set the information sharing group G(A).

[0064] <Variation 2> The following describes a second modified example of the communication control device 100A. The range determination unit 60A may expand or reduce the communication range CA(A) by referring to the maximum speed of the road on which the vehicle is traveling, the gradient of the road on which the vehicle is traveling, the importance of the information to be notified, and the like.

[0065] Embodiment 2 The second embodiment will be described with reference to FIGS. FIG. 12 is a diagram showing a transmitting vehicle 300F, a receiving vehicle 300A, and a receiving vehicle 300R. In the second embodiment, when the transmitting vehicle 300F, the receiving vehicle 300A, and the receiving vehicle 300R are traveling in this order, the transmitting vehicle 300F and the receiving vehicle 300R cannot communicate with each other, but the other vehicles can communicate with each other. The receiving vehicle 300A relays communication information between the transmitting vehicle 300F and the second receiving vehicle 300R. The vehicle 300A is a relay vehicle. Hereinafter, it may be referred to as the relay vehicle 300A. The vehicle 300 can be any of the transmitting vehicle, the receiving vehicle, and the relay vehicle.

[0066] In the first embodiment, as shown in Fig. 1, the range determination unit 60A of the transmitting vehicle 300A determines a communication range CA(A) to which the sensing information 305A should be transmitted. The range determination unit 60A sets the vehicles 300 traveling in the communication range CA(A) to an information sharing group G(A). The information sharing group G(A) is a group consisting of the vehicles 300 to which the sensing information 305A is transmitted.

[0067] In the second embodiment, receiving vehicle 300R, which cannot directly communicate with transmitting vehicle 300F, is included in communication target vehicles of transmitting vehicle 300F. 13 shows a communication relationship in embodiment 2. In embodiment 2, receiving vehicle 300A, which can directly communicate with transmitting vehicle 300F, relays communication between transmitting vehicle 300F and receiving vehicle 300R. In this way, transmitting vehicle 300F exchanges information with receiving vehicle 300R, which cannot directly communicate with transmitting vehicle 300F. 14 shows a functional block diagram of a communication control device 100A of embodiment 2. The communication control device 100A of embodiment 2 further includes a relay determining unit 90A in addition to the components of the communication control device 100A of embodiment 1. The function of the relay determining unit 90A will be described later. 15 shows a hardware configuration of a communication control device 100A of embodiment 2. The communication control device 100A of embodiment 2 further includes a relay determining unit 90A in addition to the components of the communication control device 100A of embodiment 1.

[0068] <Relay from vehicle 300R to originating vehicle 300F> See Fig. 12. When the relay determination unit 90A receives transmission information of the receiving vehicle 300R, such as the coexistence range index Ri(R), from the receiving vehicle 300R, it relays the transmission information of the receiving vehicle 300R to the sending vehicle 300F.

[0069] <Relay from sending vehicle 300F to receiving vehicle 300R> Please refer to Fig. 12. When the relay determination unit 90A receives the transmission information of the originating vehicle 300F with a communication range CA(F) from the originating vehicle 300F, the relay determination unit 90A performs the following process. Based on the speed V(A), position X(A), speed V(F), position X(F), and communication range CA(F), the relay determination unit 90A determines whether the vehicle 300A will be a relay vehicle that transmits the transmission information of the originating vehicle 300F to a receiving vehicle that is behind and traveling in the same direction as the originating vehicle 300F.

[0070] ***Explanation of Operation*** The relay operation will be described with reference to Fig. 12. The operation will be described below.

[0071] <Relay of coexistence range index Ri(A)> 12, attention is focused on vehicle 300A. Vehicle 300A is a relay vehicle.

[0072] The following process is added between the transmission of the coexistence range index Ri to the surrounding vehicles (step S15) and the setting of the information sharing group G(A) (step S18) in FIG. 7 of the first embodiment. When the relay determination unit 90A receives the coexistence range index Ri(R) of the vehicle 300R, the relay determination unit 90A relays the coexistence range index Ri(R) to the forward vehicle 300F. This relay step is added between the transmission of the coexistence range index Ri to the surrounding vehicles (step S15) and the setting of the information sharing group G(A) (step S18). Although not illustrated in FIG. 12, the relay determination unit 90A may transmit the coexistence range index Ri(R) to a surrounding vehicle other than the originating vehicle 300F as a relay destination vehicle. A vehicle that receives the coexistence range index Ri(R) relays the coexistence range index Ri(R) to the originating vehicle 300F. Alternatively, the coexistence range index Ri(R) may be relayed to the vehicle 300F in a chain of relays, such as the vehicle 300B receiving the coexistence range index Ri(R) from the vehicle 300A, and the vehicle 300C receiving the coexistence range index Ri(R) from the vehicle 300B. In addition, when there are a plurality of vehicles 300 that can receive the coexistence range index of the vehicle 300R, such as the vehicles 300A-D, if all the vehicles 300A-D perform relaying, unnecessary relaying may occur. To prevent such a case, the vehicle 300R may refer to the relative distance between the vehicle and the candidate relay vehicle. For example, the vehicle 300R may determine whether to relay the coexistence range index Ri(R), such as not selecting the candidate relay vehicle as the relay vehicle if the candidate relay vehicle and the vehicle 300R are sufficiently close to each other.

[0073] Alternatively, the relay determining unit 90A can determine, as a transmission target, a vehicle located within the range indicated by the received coexistence range index Ri(R), a vehicle located in front of the vehicle 300A, or a vehicle whose relative distance is greater than a threshold value previously held by the relay determining unit 90A. Note that the relay determining unit 90A has information capable of converting the coexistence range index Ri(R) provided as a distance into a range Ri-B.

[0074] <Operations of the vehicle extraction unit 50F and the range determination unit 60F> In the second embodiment, the vehicle extraction (step S16), the determination of the communication range CA by the range determination unit 60, and the setting of the information sharing group G(A) (steps S17 and S18) in the first embodiment are performed as follows. Please refer to Fig. 12. In step S16, the vehicle extraction unit 50F extracts vehicles to be used in determining the communication range CA(F). Specifically, the vehicle extraction unit 50F extracts the relay vehicle 300A and the receiving vehicle 300R by the method described in Fig. 1 as follows. In Fig. 12, the corresponding range R(A) of the coexistence range index Ri(A) and the corresponding range R(R) of the coexistence range index Ri(R) overlap with the forward sensing range 301F of the vehicle 300F. Therefore, the vehicle extraction unit 50F extracts the relay vehicle 300A and the receiving vehicle 300R. The vehicle extraction unit 50F instructs the range determination unit 60F to EV(F)={[ID(A), X(A)], [ID(R), X(R)]} Output.

[0075] The range determination unit 60F calculates the distance L(k) (k=A, R) to the extracted vehicle 300k (k=A, R) based on the position X(k) (k=A, R) acquired from the relay vehicle 300A. Then, from the calculation result, the range determination unit 60F determines the communication range CA(F) which is the transmission range of the sensing information 305F of the originating vehicle 300F. The range determination unit 60F sets the relay vehicle 300A and the receiver 300R located in the communication range CA(F) to the information sharing group G(F) of the originating vehicle 300F. The above operations of the vehicle extraction unit 50F and the range determination unit 60F are similar to the operations of the vehicle extraction unit 50A and the range determination unit 60A of the first embodiment.

[0076] <Relaying sensing information> Please refer to Fig. 12. After the transmission of the communication range CA(A) to the information sharing group G(A) (step S19) in Fig. 7 of the first embodiment, the following process is added. The following process is the process of the relay vehicle 300A in Fig. 12.

[0077] When the relay determination unit 90A is notified of the information sharing group G(F) and communication range CA(F) from the originating vehicle 300F, it calculates the relative speed ΔV(F,A) and relative distance ΔX(F,A) between the originating vehicle 300F and the vehicle 300A. The vehicles set in the information sharing group G(F) are the relay vehicle 300A and the receiving vehicle 300R. The relay determination unit 90A (1) The relative velocity ΔV(F,A) is smaller than the preset relative velocity threshold, and, (2) The difference between the relative distance ΔX(F,A) and the communication range RA(F) is smaller than a preset distance judgment threshold. It is determined whether the relay condition is satisfied. When the relay conditions (1) and (2) are met, the relay determining unit 90A sets the communication control device 100A as a sensing information repeater that relays the sensing information 305F of the originating vehicle 300F. When a plurality of vehicles, for example, the vehicle 300B and the vehicle 300C, are located near the relay vehicle 300A, the vehicles 300A, 300B, and 300C can serve as relay vehicles. In order to prevent such a case, when the relay condition is satisfied in each vehicle 300, the relay determination unit 90 of that vehicle 300 notifies the surrounding vehicles that the relay condition is satisfied and the determination content. Specifically, the determination content is (1) the relative speed ΔV and (2) the relative distance ΔX. Each vehicle 300 refers to the determination content received from the other vehicles 300. Then, when both the (1) relative speed ΔV and (2) relative distance ΔX of its own vehicle 300 are smallest, the relay determination unit 90 of each vehicle sets the communication control device 100 mounted in its own vehicle 300 as a sensing information repeater that relays the sensing information 305F of the originating vehicle 300F.

[0078] The communication control device 100A of the relay vehicle 300A is as follows. The communication control device 100A includes a relay determination unit 90A. When the packet receiving unit 80A receives a coexistence range index Ri transmitted with a destination vehicle other than the vehicle 300A, the relay determination unit 90A relays the coexistence range index Ri to the destination. When the packet receiving unit 80A receives sensing information transmitted with a destination vehicle other than the vehicle 300A, the relay determination unit 90A relays the sensing information to the destination of the sensing information.

[0079] ***Effects of the second embodiment*** According to the inter-vehicle communication system 1 of the second embodiment, even if there is a receiving vehicle that cannot communicate with the originating vehicle within the communication range CA of the originating vehicle, the originating vehicle can transmit the sensing information of the originating vehicle to the receiving vehicle.

[0080] <Variation 1> A first modified example of the communication control device 100 described in the second embodiment will be described below. The relay vehicle may be set by the originating vehicle. The relay vehicle may be set based on criteria such as the vehicle most likely to run parallel to the originating vehicle, the vehicle with the largest number of communicable vehicles, or the vehicle with the furthest relative distance by comparing the vehicle speed V, parallel running distance, and number of communicable vehicles of each vehicle set in the information sharing group G.

[0081] <Variation 2> The following describes a second modified example of the communication control device 100A. If the rank of the vehicle is higher than that of a general vehicle, regardless of the above judgment, the relay determination unit 90 may set the vehicle in which the communication control device 100 is mounted as a relay vehicle if the rank of the vehicle is higher than that of a general vehicle. This is because a high-ranking vehicle may block communication.

[0082] Embodiment 3 As the third embodiment, the hardware configuration of the communication control device 100 described in the first and second embodiments will be supplemented.

[0083] <Hardware configuration supplement> 5 and 15, the functions of the communication control device 100 are realized by software. However, the functions of the communication control device 100 may be realized by hardware. FIG. 16 shows a configuration in which the functions of the communication control device 100 are realized by hardware. The electronic circuit 400 in FIG. 16 is a dedicated electronic circuit that realizes the functions of the signal processing unit 10, the position acquisition unit 20, the speed acquisition unit 30, the index calculation unit 40, the vehicle extraction unit 50, the range determination unit 60, the packet transmission unit 70, and the packet reception unit 80 of the communication control device 100. The electronic circuit 400 is connected to a signal line 401. Specifically, the electronic circuit 400 is a single circuit, a composite circuit, a programmed processor, a parallel programmed processor, a logic IC, a GA, an ASIC, or an FPGA. GA is an abbreviation for Gate Array. ASIC is an abbreviation for Application Specific Integrated Circuit. FPGA is an abbreviation for Field-Programmable Gate Array. The functions of the components of the communication control device 100 may be realized by one electronic circuit, or may be distributed and realized by multiple electronic circuits. Also, some of the functions of the components of the communication control device 100 may be realized by electronic circuits, and the remaining functions may be realized by software.

[0084] Each of the processor 110 and the electronic circuit 400 is also called a processing circuitry or a circuitry. In the communication control device 100, the functions of the signal processing unit 10, the position acquisition unit 20, the speed acquisition unit 30, the index calculation unit 40, the vehicle extraction unit 50, the range determination unit 60, the packet transmission unit 70, and the packet reception unit 80 may be realized by the circuitry.

[0085] As described above, in the first and second embodiments, among the multiple technical matters included in each embodiment, one technical matter may be partially implemented. Alternatively, the technical matters included in each embodiment may be partially combined and implemented. [Explanation of symbols]

[0086] 5 Event, 10,10A Signal processing unit, 20,20A Position acquisition unit, 30,30A Speed ​​acquisition unit, 40,40A Index calculation unit, 50,50A,50F Vehicle extraction unit, 60,60A,60F Range determination unit, 70,70A Packet transmission unit, 80,80A Packet reception unit, 90,90A Relay determination unit, 100,100A Communication control device, 110 Processor, 120 Main memory device, 130 Auxiliary memory device, 140 Input IF, 150 Output IF, 160 Communication IF, 170 Signal line, 300,300A,300B,300C,300D,300F Vehicle, 301,301A Front sensing range, 302,302A Vehicle information, 305,305A Sensing information, 306B Lane width.

Claims

1. In a communication control device mounted on a vehicle, A position acquisition unit that acquires a position of the vehicle; a receiving unit that receives, from each of a plurality of rear vehicles traveling behind the vehicle, a position of the rear vehicle and a coexistence range index that is an index indicating a coexistence range between the vehicle and the rear vehicle, and that is an index requesting the vehicle to transmit event information indicating the observed event if the vehicle observes an event while the vehicle and the rear vehicle are present in the coexistence range; a vehicle extraction unit that extracts a rear vehicle to be used for determining a communication range indicating a range in which the rear vehicle to which the event information is to be transmitted exists from the plurality of rear vehicles based on a position of the vehicle, a position of the rear vehicle, and the coexistence range index; a range determination unit that determines the communication range based on the extracted position of the rear vehicle; A communication control device comprising:

2. The vehicle extraction unit includes:

2. The communication control device according to claim 1, wherein for each of the rear vehicles, it is determined whether the vehicle and the rear vehicle coexist in the coexistence range indicated by the coexistence range index, and the rear vehicle determined to coexist is extracted as the rear vehicle to be used in determining the communication range.

3. The vehicle equipped with the communication control device further includes: A group of sensors having a detection range for detecting the event occurring in front of the vehicle are mounted on the vehicle, The vehicle extraction unit includes:

3. The communication control device according to claim 1 or 2, which determines for each of the rear vehicles whether there is an overlapping range between the coexistence range fixed to the rear vehicle and the detection range of the vehicle, and extracts the rear vehicle for which it is determined that there is an overlapping range as the rear vehicle to be used in determining the communication range.

4. The range determination unit is 3 . The communication control device according to claim 1 , wherein the communication range is determined based on the position of the rear vehicle that is farthest from the position of the vehicle among the extracted rear vehicles.

5. The communication control device further includes: Assuming that a vehicle traveling ahead of the vehicle observes the event, an index calculation unit that calculates the coexistence range index based on an avoidance time required for the vehicle corresponding to the rear vehicle of the front vehicle to avoid the event, and transmits the coexistence range index; The communication control device according to claim 1 or 2, comprising:

6. The index calculation unit is The communication control device according to claim 5 , wherein a travel distance of the vehicle calculated from a constant speed and the avoidance time is calculated as the coexistence range index.

7. The constant speed is 7. The communication control device according to claim 6, wherein the speed is one of the speed of the vehicle, the average speed of a number of surrounding vehicles traveling around the vehicle, the overall average speed of the vehicle and the number of surrounding vehicles traveling, or a speed specified as a fixed value.

8. The index calculation unit is The communication control device according to claim 5 , wherein the coexistence range index is recalculated periodically or irregularly, and the recalculated coexistence range index is transmitted.

9. The communication control device further includes:

3. The communication control device according to claim 1, further comprising a relay determination unit that relays the received coexistence range indicator to the destination when the receiving unit receives the coexistence range indicator transmitted to a destination vehicle different from the vehicle.

10. The relay determination unit, The communication control device according to claim 9 , wherein when the receiving unit receives the event information transmitted to a destination vehicle other than the vehicle, the receiving unit relays the received event information to the destination of the event information.

11. A communication control device, which is a computer mounted on a vehicle, A position acquisition process for acquiring a position of the vehicle; a receiving process for receiving, from each of a plurality of rear vehicles traveling behind the vehicle, a position of the rear vehicle and a coexistence range index which is an index indicating a coexistence range between the vehicle and the rear vehicle, and which is an index requesting the vehicle to transmit event information indicating the observed event if the vehicle observes an event while the vehicle and the rear vehicle are present in the coexistence range; a vehicle extraction process for extracting a rear vehicle to be used for determining a communication range indicating a range in which the rear vehicle to which the event information is to be transmitted is present, from the plurality of rear vehicles, based on a position of the vehicle, a position of the rear vehicle, and the coexistence range index; a range determination process for determining the communication range based on the extracted position of the rear vehicle; A communication control program that executes the above.

12. A communication control device which is a computer mounted on a vehicle, Obtaining a location of the vehicle; receiving, from each of a plurality of rear vehicles traveling behind the vehicle, a position of the rear vehicle and a coexistence range indicator which is an indicator indicating a coexistence range between the vehicle and the rear vehicle, and which is an indicator requesting the vehicle to transmit event information indicating the observed event if the vehicle observes an event while the vehicle and the rear vehicle are present in the coexistence range; extracting a rear vehicle to be used for determining a communication range indicating a range in which the rear vehicle to which the event information is to be transmitted is present, from the plurality of rear vehicles, based on a position of the vehicle, a position of the rear vehicle, and the coexistence range index; determining the communication range based on the extracted position of the rear vehicle; Communications control method.

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