Communication system

Abstract

To suppress an excessive amount of information received by a server in a communication system.SOLUTION: A communication system 10 comprises a plurality of vehicles 20 including a first vehicle 20A and a second vehicle 20B, and a server 40 capable of communicating with the plurality of vehicles 20. When the second vehicle 20B is traveling in a following relationship with the first vehicle 20A, the first vehicle 20A transmits, to the server 40, absolute position information AI of the first vehicle 20A including latitude and longitude coordinate values at which the first vehicle 20A is located, and inter-vehicle distance information DI of the second vehicle 20B. The second vehicle 20B does not transmit absolute position information AI of the second vehicle 20B to the server 40. The server 40 calculates an absolute position of the second vehicle 20B based on the absolute position information AI of the first vehicle 20A and the inter-vehicle distance information DI of the second vehicle 20B.SELECTED DRAWING: Figure 6

Description

[Technical Field]

[0001] The present invention relates to communication systems. [Background technology]

[0002] Patent Document 1 describes a communication system including a first vehicle, a second vehicle, and a server. In the communication system, the first vehicle transmits location information of the first vehicle and location information of the second vehicle to the server. The location information includes latitude and longitude information. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2016-212610 Summary of the Invention [Problem to be solved by the invention]

[0004] In a communication system such as that described in Patent Document 1, the server receives information on the latitude and longitude of the first vehicle and information on the latitude and longitude of the second vehicle, which may result in the server receiving an excessive amount of information. [Means for solving the problem]

[0005] In order to solve the above problem, the present invention is a communication system comprising a plurality of vehicles including a first vehicle and a second vehicle, and a server capable of communicating with the plurality of vehicles, wherein when the second vehicle is traveling in a following relationship with the first vehicle, the first vehicle acquires absolute position information of the first vehicle including the coordinate values ​​of the latitude and longitude at which the first vehicle is located, acquires inter-vehicle distance information of the second vehicle indicating the inter-vehicle distance between the first vehicle and the second vehicle, and transmits the absolute position information of the first vehicle and the inter-vehicle distance information of the second vehicle to the server, and the second vehicle does not transmit the absolute position information of the second vehicle including the coordinate values ​​of the latitude and longitude at which the second vehicle is located to the server, and the server calculates the coordinate values ​​of the latitude and longitude at which the second vehicle is located based on the absolute position information of the first vehicle and the inter-vehicle distance information of the second vehicle. [Effects of the Invention]

[0006] The above communication system can prevent the server from receiving an excessive amount of information. [Brief explanation of the drawings]

[0007] [Figure 1] FIG. 1 is a schematic diagram of a communication system. [Figure 2] FIG. 2 is a flowchart showing the process in which the server determines the group. [Figure 3] FIG. 3 is a flowchart showing the process in which the server makes a request to each vehicle. [Figure 4] FIG. 4 is a flowchart showing the transmission control process performed by the following vehicle. [Figure 5] FIG. 5 is a flowchart showing the transmission control process performed by the leading vehicle. [Figure 6] FIG. 6 is an explanatory diagram of a situation in which information is being transmitted from the leading vehicle to the server. DETAILED DESCRIPTION OF THE INVENTION

[0008] An embodiment of a communication system will be described below with reference to the drawings. <Communication system overview> As shown in FIG. 1, the communication system 10 includes a plurality of vehicles 20, a wireless communication network 30, and a server 40.

[0009] The vehicle 20 has a vehicle communication device 21, a vehicle control device 22, and a plurality of information acquisition devices 23. The vehicle communication device 21 communicates with the server 40 by wireless communication via a wireless communication network 30. The vehicle communication device 21 also communicates with other vehicles 20 by vehicle-to-vehicle communication. The vehicle control device 22 controls the communication of the vehicle communication device 21.

[0010] The multiple information acquisition devices 23 acquire various information about the vehicle 20. The multiple information acquisition devices 23 include a GPS receiver 24, a vehicle speed sensor 25, and a vehicle-to-vehicle distance sensor 26. The GPS receiver 24 receives absolute position information AI indicating the absolute position of the vehicle 20 from the GPS device. The absolute position is a position indicated by latitude and longitude coordinate values. Therefore, the absolute position information AI includes latitude and longitude information. The vehicle speed sensor 25 acquires the traveling speed of the vehicle 20 as a vehicle speed V. The vehicle-to-vehicle distance sensor 26 detects a vehicle-to-vehicle distance DV, which is the distance from the vehicle 20 to a vehicle 20 traveling ahead of the vehicle 20. An example of the vehicle-to-vehicle distance sensor 26 is a LIDAR. Note that "LIDAR" is an abbreviation for Laser Imaging Detection and Ranging. Each information acquisition device 23 outputs the acquired information about the vehicle 20 to the vehicle control device 22.

[0011] The vehicle control device 22 controls the following traveling of the vehicle 20. The vehicle control device 22 controls following traveling of another vehicle 20 traveling ahead of the vehicle 20, in response to a user operation. When the vehicle 20 is traveling following a preceding vehicle, the vehicle 20 and the preceding vehicle are traveling in a following relationship. When the vehicle control device 22 is in following traveling, it generates following information FD indicating that the vehicle is in following traveling. The vehicle control device 22 has a memory unit. The memory unit of the vehicle control device 22 includes a counter for counting the number NM of following vehicles RV, which will be described later. The memory unit of the vehicle control device 22 is also capable of temporarily storing information.

[0012] The vehicle control device 22 acquires, as moving object information VI, various pieces of information about the vehicle 20 acquired from the multiple information acquisition devices 23, the times at which the various pieces of information were acquired, and following information FD about the vehicle 20. The moving object information VI is information about the vehicle 20 in the real world.

[0013] The vehicle control device 22 outputs the moving object information VI to the vehicle communication device 21. Then, the vehicle communication device 21 transmits the moving object information VI to the server 40. Note that in FIG. 1, one vehicle 20 out of the multiple vehicles 20 is illustrated in detail, and the details of the other vehicles 20 are omitted. Each vehicle 20 transmits the moving object information VI to the server 40.

[0014] The server 40 is capable of communicating with a plurality of vehicles 20. The server 40 acquires a plurality of pieces of mobile object information VI from the plurality of vehicles 20. The server 40 is capable of transmitting various requests DM to the vehicles 20 based on predicted mobile object information FI generated based on the mobile object information VI, which will be described later. The server 40 includes a communication device 50, an information processing device 60, and a data center 70.

[0015] The communication device 50 communicates with a plurality of vehicles 20. The communication device 50 receives mobile object information VI transmitted from the vehicles 20. The communication device 50 outputs the received mobile object information VI to the information processing device 60. The communication device 50 also transmits information acquired from the information processing device 60 to the vehicles 20.

[0016] The information processing device 60 includes a CPU 61, which is an execution device, a peripheral circuit 62, a data storage unit 63, a program storage unit 64, and a bus 65. The bus 65 connects the CPU 61, the peripheral circuit 62, the data storage unit 63, and the program storage unit 64 so that they can communicate with one another. The peripheral circuit 62 includes a circuit that generates a clock signal that regulates internal operation, a power supply circuit, a reset circuit, etc. The data storage unit 63 stores data generated in accordance with the operation of the CPU 61. The program storage unit 64 stores a program P1 for generating predicted moving object information FI, a program P2 for determining a group GR, a program P3 for requesting the transmission of location information, and a program P4 for processing inter-vehicle distance information DI. The CPU 61 performs information processing by executing various programs stored in the program storage unit 64.

[0017] The data center 70 stores predicted mobile object information FI. The predicted mobile object information FI is information generated based on mobile object information VI of multiple vehicles 20, and includes multiple pieces of mobile object information VI from the time the mobile object information VI in a specified area was acquired. The specified area may be, for example, an area including one country, an area including only a portion of one country, or an area including the entire world. In other words, the predicted mobile object information FI is a so-called digital twin. The data center 70 also stores time series data of the predicted mobile object information FI generated by the information processing device 60. The data center 70 acquires the predicted mobile object information FI generated by the information processing device 60 multiple times over time. As a result, the data center 70 stores time series data of the predicted mobile object information FI.

[0018] <Generation of predicted moving object information> The CPU 61 repeatedly executes the generation program P1 for the predicted moving object information FI at a predetermined cycle, thereby repeatedly generating the predicted moving object information FI. The predetermined cycle is set to, for example, one minute.

[0019] When the CPU 61 starts executing the program P1 for generating predicted mobile object information FI, it first acquires mobile object information VI of each vehicle 20 in the communication system 10. Next, the CPU 61 generates predicted mobile object information FI based on the acquired mobile object information VI. First, the CPU 61 references information indicating the time at which the acquired multiple pieces of mobile object information VI were acquired. Next, the CPU 61 predicts the mobile object information VI at the reference time by setting the time of the most recently acquired mobile object information VI as the reference time and correcting the other mobile object information VI by the time difference. For example, the CPU 61 makes the prediction by correcting the mobile object information VI based on past vehicle speeds V and other mobile object information VI. Then, the CPU 61 generates various information of the predicted mobile object information VI as predicted mobile object information FI. As a result, the CPU 61 acquires the mobile object information VI of the multiple vehicles 20 synchronized with the reference time as predicted mobile object information FI. Thereafter, the CPU 61 stores the acquired predicted mobile object information FI in the data center 70. In this manner, the information processing device 60 generates predicted mobile object information FI.

[0020] <Determining whether a group is formed> The CPU 61 repeatedly executes a program P2 for determining a group GR traveling in a following relationship at a predetermined cycle. The predetermined cycle is set to, for example, one minute. As a result, the CPU 61 determines, among the multiple vehicles 20 in a predetermined area, which vehicles 20 belong to the group GR, i.e., which vehicles 20 are traveling in a following relationship, and which vehicles 20 do not belong to the group GR, i.e., which vehicles 20 are not traveling in a following relationship.

[0021] 2, when the CPU 61 starts execution of the judgment program P2 for the group GR, it first starts processing in step S11. In step S11, the CPU 61 acquires time-series data of the predicted moving object information FI in the data center 70 for a predetermined period of time in the past. The predetermined period of time in the past is, for example, three minutes. Thereafter, the CPU 61 proceeds to processing in step S12.

[0022] In step S12, the CPU 61 extracts multiple vehicles 20 that have been present within a specified range for the past specified period based on the time-series data of the predicted moving object information FI acquired in step S11. The specified range is, for example, a range in which the distance between multiple vehicles 20 is within 100 meters. The CPU 61 then proceeds to step S13. Note that if the CPU 61 is unable to extract multiple vehicles 20 in step S12, the CPU 61 adds non-component information indicating that all vehicles 20 do not constitute a group GR to the predicted moving object information FI, and ends this series of processes.

[0023] In step S13, the CPU 61 determines whether or not a specified percentage or more of the vehicles 20 are currently being followed among the plurality of vehicles 20 extracted in step S12. The specified percentage is set to, for example, 50%. Specifically, the CPU 61 determines whether or not the moving object information VI of the plurality of vehicles 20 extracted in step S12 includes following information FD. The CPU 61 then compares the number of moving object information VI that includes following information FD with the number extracted in step S12.

[0024] If the number of following information FDs is equal to or greater than the specified ratio (S13: YES), the CPU 61 proceeds to step S14. In step S14, the CPU 61 determines that the plurality of vehicles 20 extracted in step S12 are a group GR traveling together. Thereafter, the CPU 61 proceeds to step S15.

[0025] In step S15, the CPU 61 adds, to the predicted moving object information FI, configuration information indicating that the vehicles 20 are in one group GR and group identification information identifying the group GR, for the plurality of vehicles 20 determined to be in one group GR in step S14. Thereafter, the CPU 61 ends the series of processes.

[0026] On the other hand, if the number of pieces of following information FD does not exceed the specified ratio (S13: YES), the CPU 61 proceeds to step S21. In step S21, the CPU 61 does not determine that the multiple vehicles 20 extracted in step S12 belong to one group GR. Thereafter, the CPU 61 proceeds to step S22.

[0027] In step S22, the CPU 61 adds non-constitution information indicating that the vehicles 20 do not constitute a group GR to the predicted moving object information FI for the vehicles 20 that were not determined to constitute a group GR in step S21. The CPU 61 then terminates the series of processes. By executing the group GR determination program P2 in this manner, the predicted moving object information FI comes to include information indicating whether or not the vehicles 20 constitute a group GR.

[0028] <Request from server to vehicle> Next, the request DM to the vehicles 20 that make up the group GR performed by the information processing device 60 will be described. The CPU 61 repeatedly executes a request program P3 for transmitting location information at a predetermined cycle. The CPU 61 repeatedly executes this process for each group GR made up of multiple vehicles 20. Therefore, the CPU 61 refers to the predicted moving object information FI to determine the target for which the request program P3 should be executed, and then starts execution of the request program P3 for each group GR.

[0029] 3, when the CPU 61 starts executing the request program P3, it first executes the processing of step S31. In step S31, the CPU 61 determines whether the number of vehicles 20 that make up the group GR is less than a predetermined specified number RN. The specified number RN is, for example, 10 vehicles. If the number of vehicles 20 that make up the group GR is less than the specified number RN (S31: YES), the CPU 61 proceeds to the processing of step S32.

[0030] In step S32, the CPU 61 identifies the leading vehicle FV of the group GR based on the predicted moving object information FI. For example, the CPU 61 estimates a line of multiple vehicles 20 by referring to the absolute positions of the vehicles 20 in the predicted moving object information FI. Next, the CPU 61 estimates the direction in which the line will move by referring to the predicted moving object information FI. Then, the CPU 61 estimates that of the vehicles 20 at both ends of the estimated line, the vehicle 20 at the front in the estimated moving direction is the leading vehicle FV. After that, the CPU 61 proceeds to step S33.

[0031] In step S33, the CPU 61 transmits a request DM to the lead vehicle FV to acquire inter-vehicle distance information DI of the following vehicles RV, which are the vehicles 20 excluding the lead vehicle FV among the vehicles 20 constituting the group GR, and to transmit the information to the server 40. The inter-vehicle distance DV of the following vehicle RV is the inter-vehicle distance DV between the following vehicle RV and a preceding vehicle traveling ahead of the following vehicle RV. The CPU 61 then proceeds to step S34.

[0032] In step S34, the CPU 61 transmits to the following vehicle RV a request DM to stop transmitting the absolute position information AI to the server 40. Thereafter, the CPU 61 advances the process to step S35.

[0033] In step S35, the CPU 61 transmits a request DM to the following vehicle RV to transmit the inter-vehicle distance information DI to the leading vehicle FV, whereupon the CPU 61 ends the current series of processes.

[0034] On the other hand, if the number of vehicles 20 constituting the group GR is equal to or greater than the specified number RN (S31: NO), the CPU 61 proceeds to step S36. In step S35, the CPU 61 transmits a request DM to all vehicles 20 constituting the group GR to stop transmitting inter-vehicle distance information DI and to transmit absolute position information AI to the server 40. This causes the CPU 61 to end the current series of processes. Note that when non-constituent information is added to the predicted moving object information FI, the CPU 61 performs the same process as in step S36.

[0035] <Transmitting information about following vehicles> Next, the processing performed by the vehicle control device 22 of the following vehicle RV that receives the request DM from the server 40 through the processing of steps S34 and S35 will be described. Note that, hereinafter, the vehicle control device 22 of the following vehicle RV will be described as the vehicle control device 22R. Upon receiving the request DM from the server 40, the vehicle control device 22R controls the transmission of inter-vehicle distance information DI to the leading vehicle FV.

[0036] 4, when the vehicle control device 22R starts the transmission control, it first performs the process of step S41. In step S41, the vehicle control device 22R acquires information indicating the inter-vehicle distance DV detected by the inter-vehicle distance sensor 26 as inter-vehicle distance information DI of the host vehicle. The inter-vehicle distance DV of the host vehicle is the inter-vehicle distance DV between the host vehicle and a preceding vehicle traveling ahead of the host vehicle. Thereafter, the vehicle control device 22R proceeds to the process of step S42.

[0037] In step S42, the vehicle control device 22R transmits the following distance information DI of the host vehicle to the preceding vehicle. After that, the vehicle control device 22R advances the process to step S43. In step S43, the vehicle control device 22R determines whether or not it has received inter-vehicle distance information DI of the following vehicle RV from the following vehicle RV with the host vehicle as the leading vehicle. Specifically, the vehicle control device 22R determines whether or not it has received inter-vehicle distance information DI of the following vehicle RV from the following vehicle RV before a predetermined period of time has elapsed since the process of step S43 started. If the vehicle control device 22R has not received inter-vehicle distance information DI of the following vehicle RV from the following vehicle RV (S43: NO), the vehicle control device 22R ends this series of processes.

[0038] On the other hand, if the vehicle control device 22R receives the inter-vehicle distance information DI from the following vehicle RV (S43: YES), the vehicle control device 22R proceeds to step S44. In step S44, the vehicle control device 22R transmits the acquired inter-vehicle distance information DI of the following vehicle RV to the preceding vehicle. That is, the vehicle control device 22R transfers the inter-vehicle distance information DI from the vehicle 20 following the host vehicle to the vehicle 20 preceding the host vehicle. Thereafter, the vehicle control device 22R proceeds to step S45.

[0039] In step S45, the vehicle control device 22R determines whether or not it has completed receiving the inter-vehicle distance information DI from the following vehicle RV. Specifically, the vehicle control device 22R determines whether or not it has again received the inter-vehicle distance information DI of the following vehicle RV from the following vehicle RV within a predetermined period of time since starting the process of step S45. If the vehicle control device 22R has not received the inter-vehicle distance information DI of the following vehicle RV from the following vehicle RV, it determines that it has completed receiving the inter-vehicle distance information DI from the following vehicle RV. On the other hand, if the vehicle control device 22R has received the inter-vehicle distance information DI of the following vehicle RV, it determines that it has not completed receiving the inter-vehicle distance information DI from the following vehicle RV. If it has not completed receiving the inter-vehicle distance information DI from the following vehicle RV (S45: NO), the vehicle control device 22R returns the process to step S44. Then, the vehicle control device 22R again transmits the received inter-vehicle distance information DI to the leading vehicle. If the reception of the inter-vehicle distance information DI from the following vehicle RV is completed (S45: YES), the vehicle control device 22R ends the current series of processes.

[0040] <Transmitting information from the leading vehicle> Next, the processing performed by the vehicle control device 22 of the leading vehicle FV that receives the request DM from the server 40 through the processing of step S33 will be described. Note that, hereinafter, the vehicle control device 22 of the leading vehicle FV will be described as the vehicle control device 22F. Upon receiving the request DM for the leading vehicle FV from the server 40, the vehicle control device 22F controls the transmission of inter-vehicle distance information DI of the following vehicle RV to the server 40.

[0041] 5, when the vehicle control device 22F starts the transmission control, it first performs the process of step S51. In the process of step S51, the vehicle control device 22F acquires absolute position information AI from the GPS receiver 24. Thereafter, the vehicle control device 22F proceeds to the process of step S52.

[0042] In step S52, the vehicle control device 22F acquires information indicating the vehicle speed V from the vehicle speed sensor 25. After that, the vehicle control device 22F advances the process to step S53. In step S53, the vehicle control device 22F acquires the following distance information DI of the following vehicle RV from the following vehicle RV. After that, the vehicle control device 22F advances the processing to step S54.

[0043] In step S54, the vehicle control device 22F counts up the counter for the number NM of the following vehicles RV. After that, the vehicle control device 22F advances the process to step S55. In step S55, the vehicle control device 22F stores the following distance information DI. After that, the vehicle control device 22F advances the process to step S56.

[0044] In step S56, the vehicle control device 22F determines whether or not reception of the following distance information DI of the following vehicle RV from the following vehicle RV has been completed. Specifically, the process of step S56 is the same as the process of step S45. If reception of the following distance information DI from the following vehicle RV has not been completed (S56: NO), the vehicle control device 22F returns the process to step S54. On the other hand, if reception of the following distance information DI from the following vehicle RV has been completed (S56: YES), the vehicle control device 22F proceeds to step S57.

[0045] In step S57, the vehicle control device 22F transmits the absolute position information AI of the host vehicle, information indicating the vehicle speed V of the host vehicle, the stored inter-vehicle distance information DI of the following vehicle RV, and information indicating the number NM of the following vehicles RV to the server 40. After clearing the counter for the number NM of the following vehicles RV, the vehicle control device 22F ends this series of processes.

[0046] As shown in Fig. 1, upon receiving the inter-vehicle distance information DI, the CPU 61 starts executing the processing program P4 for the inter-vehicle distance information DI. When the CPU 61 starts executing the processing program P4 for the inter-vehicle distance information DI, the CPU 61 first checks whether or not the required number of inter-vehicle distance information DI has been acquired. Specifically, the CPU 61 compares the received number NM of following vehicles RV with the number of vehicles 20 constituting the group GR minus one. If the two numbers do not match, the CPU 61 performs the same processing as in step S36.

[0047] When the CPU 61 has acquired the necessary number of pieces of inter-vehicle distance information DI, the CPU 61 calculates the absolute position of the following vehicle RV based on the absolute position information AI of the leading vehicle FV and the inter-vehicle distance information DI of the following vehicle RV. Specifically, the CPU 61 calculates the absolute position of the following vehicle RV, i.e., the latitude and longitude coordinate values ​​of the following vehicle RV, as a position behind the following vehicle distance DV indicated by the inter-vehicle distance information DI, using the absolute position indicated by the absolute position information AI of the leading vehicle FV as a reference. When the CPU 61 has acquired inter-vehicle distance information DI of multiple following vehicles RV, the CPU 61 calculates the absolute positions of the following vehicles RV in order, starting from the leading vehicle FV. Specifically, the CPU 61 calculates the absolute position of the third following vehicle RV from the leading vehicle FV as a position behind the following vehicle distance DV indicated by the inter-vehicle distance information DI of the third following vehicle RV, using the absolute position of the second following vehicle RV as a reference. When the absolute positions of all vehicles 20 constituting the group GR have been calculated, the CPU 61 terminates execution of the processing program P4 for inter-vehicle distance information DI.

[0048] When generating the predicted moving object information FI, the CPU 61 uses the absolute position of the following vehicle RV calculated by executing the processing program P4 for the inter-vehicle distance information DI as the moving object information VI. For the following vehicle RV for which the absolute position information AI has not been acquired, the CPU 61 generates the predicted moving object information FI by using the calculated absolute position of the following vehicle RV.

[0049] <Operation of the embodiment> As shown in Fig. 6, five vehicles 20 are traveling in a group GR. Starting from the leading vehicle 20, the vehicles are referred to in order as the first vehicle 20A, the second vehicle 20B, the third vehicle 20C, the fourth vehicle 20D, and the fifth vehicle 20E. In this case, the first vehicle 20A is the leading vehicle FV, and the second vehicle 20B to the fifth vehicle 20E are the following vehicles RV.

[0050] In this case, since the number of vehicles 20 constituting the group GR is less than the specified number RN, the server 40 performs the processes of steps S32 to S34. As a result, the first vehicle 20A starts to execute the series of processes shown in Figure 5, and the second vehicle 20B to fifth vehicle 20E start to execute the series of processes shown in Figure 4.

[0051] As a result, the fifth vehicle 20E transmits the inter-vehicle distance information DI of the fifth vehicle 20E to the fourth vehicle 20D, which is the preceding vehicle. The fourth vehicle 20D sequentially transmits the inter-vehicle distance information DI of the fourth vehicle 20D and the inter-vehicle distance information DI of the fifth vehicle 20E to the third vehicle 20C, which is the preceding vehicle. The third vehicle 20C sequentially transmits the inter-vehicle distance information DI of the third vehicle 20C, the inter-vehicle distance information DI of the fourth vehicle 20D, and the inter-vehicle distance information DI of the fifth vehicle 20E to the second vehicle 20B, which is the preceding vehicle. The second vehicle 20B sequentially transmits the inter-vehicle distance information DI of the second vehicle 20B, the inter-vehicle distance information DI of the third vehicle 20C, the inter-vehicle distance information DI of the fourth vehicle 20D, and the inter-vehicle distance information DI of the fourth vehicle 20D, to the first vehicle 20A, which is the preceding vehicle.

[0052] On the other hand, the second vehicle 20B to the fifth vehicle 20E, which are the following vehicles RV, do not transmit information indicating the absolute position information AI of their own vehicles and the vehicle speed V of their own vehicles to the server 40. Therefore, the second vehicle 20B does not transmit the absolute position information AI of the second vehicle 20B to the server 40.

[0053] The first vehicle 20A transmits absolute position information AI of the first vehicle 20A to the server 40. The first vehicle 20A transmits inter-vehicle distance information DI of the second vehicle 20B to the fifth vehicle 20E to the server 40. The first vehicle 20A transmits information indicating the vehicle speed V of the first vehicle 20A to the server 40. The first vehicle 20A transmits information indicating that the number NM of the counted following vehicles RV is four to the server 40.

[0054] The server 40 then receives the absolute position information AI of the first vehicle 20A, information indicating the vehicle speed V of the first vehicle 20A, inter-vehicle distance information DI of the second vehicle 20B to the fifth vehicle 20E, and information indicating the number NM of the following vehicles RV. The server 40 then calculates the absolute positions of the second vehicle 20B to the fifth vehicle 20E based on the absolute position information AI of the first vehicle 20A and the inter-vehicle distance information DI of the second vehicle 20B to the fifth vehicle 20E. The server 40 also estimates the vehicle speed V of the second vehicle 20B to the fifth vehicle 20E as the vehicle speed V of the first vehicle 20A.

[0055] Thereafter, the server 40 generates predicted moving body information FI using the acquired absolute value of the first vehicle 20A and the vehicle speed V of the first vehicle 20A, and the calculated absolute positions of the second vehicle 20B to the fifth vehicle 20E and the vehicle speeds V of the second vehicle 20B to the fifth vehicle 20E.

[0056] <Effects of the embodiment> (1) According to the above embodiment, the first vehicle 20A transmits the absolute position information AI of the first vehicle 20A and the inter-vehicle distance information DI of the second vehicle 20B to the server 40. The second vehicle 20B does not transmit the absolute position information AI of the second vehicle 20B to the server 40. The server 40 then calculates the absolute position of the second vehicle 20B based on the absolute position information AI of the first vehicle 20A and the inter-vehicle distance information DI of the second vehicle 20B. Therefore, the amount of information received by the server 40 is less than when receiving the absolute position information AI of the second vehicle 20B. Therefore, the communication system 10 can prevent the amount of information received by the server 40 from becoming excessively large.

[0057] (2) According to the above embodiment, the first vehicle 20A transmits information indicating the vehicle speed V of the first vehicle 20A to the server 40. The second vehicle 20B transmits information indicating the vehicle speed V of the second vehicle 20B to the server 40. The server 40 then estimates the vehicle speed V of the second vehicle 20B to be the vehicle speed V indicated by the information indicating the vehicle speed V of the first vehicle 20A. This eliminates the need for the server 40 to receive information indicating the vehicle speed V of the following vehicle RV from the following vehicle RV.

[0058] (3) According to the above embodiment, the server 40 generates predicted moving object information FI based on the absolute positions of multiple vehicles 20. The server 40 determines whether the second vehicle 20B is traveling in a following relationship with the first vehicle 20A based on the predicted moving object information FI. When the second vehicle 20B is traveling in a following relationship with the first vehicle 20A, the server 40 transmits a request DM to the second vehicle 20B to stop transmission of the absolute position information AI of the second vehicle 20B. Therefore, the server 40 can generate predicted moving object information FI and transmit a request DM based on the predicted moving object information FI while minimizing the amount of information received.

[0059] (4) According to the above embodiment, when the second vehicle 20B is not traveling in a following relationship with the first vehicle 20A, the second vehicle 20B transmits the absolute position information AI of the second vehicle 20B to the server 40. Therefore, the server 40 can prevent a situation in which the absolute position of the second vehicle 20B cannot be acquired when the second vehicle 20B is not following the first vehicle 20A.

[0060] (5) If the first vehicle 20A transmits inter-vehicle distance information DI of an excessively large number of vehicles 20 to the server 40, it will take an excessively long time from when the inter-vehicle distance information DI is acquired by each vehicle 20 until the server 40 receives the inter-vehicle distance information DI. In this regard, according to the above embodiment, when a specified number RN or more of vehicles 20 are following, the following vehicle RV does not transmit inter-vehicle distance information DI to the server 40, and each vehicle 20 transmits absolute position information AI to the server 40. This prevents the absolute position of the vehicle 20 calculated by the server 40 from becoming excessively outdated information.

[0061] <Other embodiments> This embodiment can be modified as follows: This embodiment and the following modifications can be combined and implemented within the scope of technical compatibility.

[0062] When the number NM of the following vehicles RV is equal to or greater than the specified number RN, the server 40 does not need to transmit to the lead vehicle FV a request DM not to acquire the inter-vehicle distance information DI of the following vehicle RV. When the number NM of the following vehicles RV is equal to or greater than the specified number RN, the server 40 does not need to transmit to the following vehicle RV a request DM to transmit the absolute position information AI.

[0063] The server 40 does not have to generate the predicted moving object information FI. The server 40 does not have to use the absolute position of the vehicle 20 to generate the predicted moving object information FI. The server 40 does not have to determine whether the second vehicle 20B is following the first vehicle 20A based on the predicted moving object information FI. For example, the server 40 may determine the following relationship based on the following information FD without determining the composition of the group GR.

[0064] The second vehicle 20B may be a vehicle 20 that always follows the first vehicle 20A. In this case, since the second vehicle 20B does not travel without following the first vehicle 20A, the second vehicle 20B does not need to transmit the absolute position information AI of the second vehicle 20B to the server 40. In other words, the multiple vehicles 20 do not need to be able to travel in a following relationship.

[0065] The plurality of vehicles 20 may stop transmitting the absolute position information AI and transmit the inter-vehicle distance information DI to the preceding vehicle without receiving a request DM from the server 40. The following vehicle RV may transmit information indicating the vehicle speed V to the server 40 or to the leading vehicle FV. The following vehicle RV may transmit the inter-vehicle distance DV to the leading vehicle FV as inter-vehicle distance information DI instead of the inter-vehicle distance DV to the leading vehicle.

[0066] In the above embodiment, an example has been described in which the lead vehicle FV transmits the inter-vehicle distance information DI of the following vehicle RV to the server 40. However, among the vehicles 20 constituting the group GR, the vehicle 20 that transmits the inter-vehicle distance information DI of the other vehicles 20 to the server 40 is not limited to the lead vehicle FV. For example, among the vehicles 20 constituting the group GR, the rearmost vehicle 20 may transmit the inter-vehicle distance information DI of the other vehicles 20 to the server 40. In this case, the other vehicles 20 may transmit the inter-vehicle distance DV between themselves and the vehicle 20 traveling behind them as the inter-vehicle distance information DI of the vehicle 20 to the rearmost vehicle 20. In other words, the following relationship may be a case in which the second vehicle follows the first vehicle, or a case in which the first vehicle follows the second vehicle. Furthermore, for example, among the vehicles 20 constituting the group GR, a specific vehicle 20 may transmit the inter-vehicle distance information DI of the other vehicles 20 to the server 40. In this case, the other vehicle 20 simply transmits the inter-vehicle distance between itself and the vehicle 20 closest to the specific vehicle 20, among the vehicles 20 in front or behind it traveling side by side, to the specific vehicle 20 as inter-vehicle distance information DI of that vehicle 20. [Explanation of symbols]

[0067] 10...Communication system 20...Vehicle 20A...First vehicle 20B...Second vehicle 30...Wireless communication network 40...Server 60...Information processing device 61...CPU 64...Program storage unit AI...Absolute position information DI...Inter-vehicle distance information DM...Request DV...Inter-vehicle distance FI...Predicted moving object information FV...Leading vehicle GR...Group RN...Specified number RV...Subsequent vehicle V...Vehicle speed VI...Moving object information

Claims

1. A communication system including a plurality of vehicles including a first vehicle and a second vehicle, and a server capable of communicating with the plurality of vehicles, When the second vehicle is traveling in a following relationship with the first vehicle, The first vehicle is acquire absolute position information of the first vehicle, the absolute position information including the latitude and longitude coordinate values ​​of the location of the first vehicle; acquire inter-vehicle distance information of the second vehicle indicating an inter-vehicle distance between the first vehicle and the second vehicle; transmitting absolute position information of the first vehicle and inter-vehicle distance information of the second vehicle to the server; the second vehicle does not transmit absolute position information of the second vehicle, including coordinate values ​​of latitude and longitude where the second vehicle is located, to the server; The server calculates the coordinate values ​​of latitude and longitude where the second vehicle is located based on the absolute position information of the first vehicle and the inter-vehicle distance information of the second vehicle. Communication system.

2. When the second vehicle is traveling in the following relationship with the first vehicle, the first vehicle transmits information indicating a vehicle speed of the first vehicle to the server; the second vehicle does not transmit information indicating the vehicle speed of the second vehicle to the server; The server estimates the vehicle speed of the second vehicle as the vehicle speed indicated by the information indicating the vehicle speed of the first vehicle. The communication system of claim 1 .

3. The server generating predicted moving object information based on the coordinate values ​​of latitude and longitude where the first vehicle is located and the coordinate values ​​of latitude and longitude where the second vehicle is located; determining whether the second vehicle is traveling in the following relationship with the first vehicle based on the predicted moving object information; When the second vehicle is traveling in the following relationship with the first vehicle, a request is sent to the second vehicle to stop transmitting absolute position information of the second vehicle. The communication system of claim 1 .

4. When the second vehicle is not traveling in the following relationship with the first vehicle, The second vehicle transmits absolute position information of the second vehicle to the server. The communication system of claim 1 .

5. When a specified number or more of the vehicles including the second vehicle are traveling following the first vehicle as following vehicles with the first vehicle in the lead, The server Sending a request to the following vehicle to transmit absolute position information of the following vehicle, including latitude and longitude coordinate values ​​of the location of the following vehicle. The communication system of claim 1 .

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