Traffic-volume estimation device, update device, traffic-volume estimation method, update method, and computer program

Abstract

This traffic-volume estimation device comprises: a communication unit that communicates with a plurality of probe vehicles; a storage unit that accumulates probe information pertaining to the plurality of probe vehicles; and a processing unit that performs traffic-volume estimation processing for obtaining an estimate for the traffic volume of vehicles on a feeder road connected to a first target location in a road network. The traffic-volume estimation processing includes: a first process for obtaining, on the basis of the probe information, movement information that includes a time, that was needed for the probe vehicle positioned at a second target location on the feeder road to pass by the first target location, and the distance from the second target location to the first target location; and a second process for obtaining the estimate by referring to a traffic-volume estimation table that is updated on the basis of satellite data obtained by observing a region that includes the first target location and the feeder road. Vehicle-count information and the abovementioned movement information are recorded in association with each other in the traffic-volume estimation table, said vehicle-count information indicating the number of vehicles present on the feeder road during observation from the position of the probe vehicle to the first target location, said number of vehicles being counted on the basis of the satellite data, said movement information pertaining to the probe vehicle present on the feeder road during the observation, and said movement information being obtained on the basis of the probe information. During the second process, the estimate is obtained on the basis of the vehicle-count information corresponding to the movement information obtained during the first process.

Description

Traffic volume estimation device, update device, traffic volume estimation method, update method, and computer program

[0001] This disclosure relates to a traffic volume estimation device, an update device, a traffic volume estimation method, an update method, and a computer program. This application claims priority to Japanese Application No. 2022-173198 filed on October 28, 2022, and incorporates by reference all of the contents of said Japanese application.

[0002] Patent Document 1 discloses a technology for determining traffic indices such as load factors based on probe information and performing signal control.

[0003] International Publication No. 2020 / 071040

[0004] A traffic volume estimation device according to the present disclosure includes a communication unit that communicates with a plurality of probe vehicles, a storage unit that stores probe information of the plurality of probe vehicles, and a processing unit that executes a traffic volume estimation process that obtains an estimated value of vehicle traffic volume on an entrance road leading to a first target point on a road network. The traffic volume estimation process includes: a first process that obtains, based on the probe information, movement information including the time required for the probe vehicle located at a second target point on the entrance road to pass the first target point and the distance from the second target point to the first target point; and a second process that obtains the estimated value by referring to a traffic volume estimation table that is updated based on satellite data observing an area including the first target point and the entrance road. The traffic volume estimation table stores, in association with each other, vehicle count information that indicates the number of vehicles from the position of the probe vehicle on the entrance road at the time of observation to the first target point, which is counted based on the satellite data, and the movement information of the probe vehicle present on the entrance road at the time of observation, which is obtained based on the probe information. In the second process, the estimated value is obtained based on the number of vehicles information corresponding to the movement information obtained in the first process.

[0005] FIG. 1 is a perspective view showing an example of the overall configuration of an information provision system. FIG. 2 is a block diagram showing an example of the internal configuration of an information provision device included in the information provision system and an on-board device of a probe vehicle. FIG. 3 is a block diagram showing some of the processing functions of a processing unit. FIG. 4 is a diagram for explaining a traffic volume estimation process. FIG. 5 is a flowchart showing an example of the traffic volume estimation process. FIG. 6 is a diagram schematically showing trajectory points of a probe vehicle that has entered an entrance road. FIG. 7 is a diagram showing an example of a traffic volume estimation table. FIG. 8 is a flowchart showing an example of an update process. FIG. 9 is a diagram schematically showing a part of a captured image of a first target point and an entrance road included in satellite data. FIG. 10 is a schematic diagram of a sag section on an expressway as viewed from the side. FIG. 11 is a block diagram showing the configuration of an information provision system according to a modified example.

[0006] [Problem to be Solved by the Present Disclosure] As in the above-described conventional example, the use of probe information enables appropriate control in traffic signal control. However, it is conceivable to use probe information not only for traffic signal control but also for managing vehicle traffic volume at specific locations on roads. However, the proportion of probe vehicles among all vehicles is not high, and some probe vehicles have not uploaded probe information. Therefore, it is conceivable that there are a greater number of vehicles than expected that have not uploaded probe information. As a result, it may be difficult to accurately estimate traffic volume at specific locations.

[0007] Effect of the Present Disclosure According to the present disclosure, vehicle traffic volume can be estimated with high accuracy.

[0008] [Description of the embodiment of the present disclosure] First, the contents of the embodiment will be listed and described. [Outline of the embodiment]

[0009] (1) A traffic volume estimation device according to an embodiment includes a communication unit that communicates with a plurality of probe vehicles, a storage unit that stores probe information about the plurality of probe vehicles, and a processing unit that executes a traffic volume estimation process that obtains an estimated value of vehicle traffic volume on an entrance road leading to a first target point on a road network. The traffic volume estimation process includes: a first process that obtains, based on the probe information, movement information including the time required for the probe vehicle located at a second target point on the entrance road to pass the first target point and the distance from the second target point to the first target point; and a second process that obtains the estimated value by referring to a traffic volume estimation table that is updated based on satellite data observing an area including the first target point and the entrance road. The traffic volume estimation table stores, in association with each other, vehicle count information that indicates the number of vehicles from the position of the probe vehicle on the entrance road at the time of observation to the first target point, which is counted based on the satellite data, and the movement information of the probe vehicle on the entrance road at the time of observation, which is obtained based on the probe information. In the second process, the estimated value is obtained based on the number of vehicles information corresponding to the movement information obtained in the first process.

[0010] When satellite data, which is the observation result of an area including the first target point and the entrance road, is observed, if a probe vehicle is located on the entrance road, the presence of the probe vehicle and the presence of vehicles on the entrance road between the position of the probe vehicle and the first target point can be detected based on the satellite data. Therefore, using this satellite data, the number of vehicles between the probe vehicle's location and the first target point can be counted, and the number information can be associated with the probe information. This results in a traffic volume estimation table in which the number information, which is an actual measurement based on the satellite data, is associated with the movement information based on the probe information. According to the above configuration, by referencing the traffic volume estimation table and obtaining the number information corresponding to the movement information obtained in the first process from the traffic volume estimation table, the actually counted number of vehicles can be obtained as the estimated number of vehicles. Using the number information based on the actually counted number of vehicles as the estimated number of vehicles allows for accurate estimation of the vehicle traffic volume at a specific location, such as an entrance road.

[0011] (2) In the traffic volume estimation device of (1), when the entrance road includes a target section, the second target point may be at least one of a plurality of trajectory points in the target section included in the probe information of the probe vehicle that has entered the entrance road. In this case, a trajectory point suitable for the second target point can be selected from the plurality of trajectory points in the target section.

[0012] (3) In the traffic volume estimation device of (2), the second target point may be the locus point farthest from the first target point among the plurality of locus points. In this case, the time required for the vehicle to pass through the first target point from the second target point becomes relatively long, and the amount of information reflected in the estimated value can be increased.

[0013] (4) In the traffic volume estimation device of (1) above, each of a plurality of trajectory points in a target section on the entrance road, which are included in the probe information of the probe vehicle that has entered the entrance road, may be the second target point. In this case, a plurality of estimated values ​​can be obtained from the probe information of one probe vehicle, and processing can be performed to improve the accuracy of the estimated value using the plurality of estimated values, such as calculating an average value of the plurality of estimated values.

[0014] (5) In the traffic volume estimation device of any one of (1) to (4) above, in the second process, if the vehicle count information corresponding to the movement information obtained in the first process is not registered in the traffic volume estimation table, a predetermined other traffic volume estimation table described below is referenced to obtain the estimated value. Other traffic volume estimation table: a table for obtaining an estimated value of the traffic volume of vehicles on another incoming road different from the incoming road, and different from the traffic volume estimation table. In this case, a table from which accurate vehicle count information on the incoming road can be obtained, such as a traffic volume estimation table for another incoming road having road attributes similar to those of the incoming road, can be previously defined as the other traffic volume estimation table. This makes it possible to obtain a complementary estimated value even if the vehicle count information corresponding to the movement information obtained in the first process is not registered in the traffic volume estimation table.

[0015] (6) In the traffic volume estimation device according to any one of (1) to (5) above, the first target points may include points, nodes, and sags within links included in the road network.

[0016] (7) In any one of the traffic volume estimation devices (1) to (6) above, the estimated value may include the number of vehicles indicated by the number information and the vehicle density from the second target point to the first target point.

[0017] (8) In the traffic volume estimation device according to any one of (1) to (7), the communication unit may communicate with the satellite data providing device, and the processing unit may execute an update process to update the traffic volume estimation table based on the satellite data acquired from the providing device. In this case, the most recent satellite data is reflected in the traffic volume estimation table, thereby further improving the accuracy of the information registered in the traffic volume estimation table.

[0018] (9) In the traffic volume estimation device of (8), the update process may include a process of acquiring the satellite data from the providing device, a determination process of determining whether or not the probe vehicle is present on the incoming road at the time of observation based on the probe information, and a process of determining whether or not to use the acquired satellite data to update the traffic volume estimation table depending on the result of the determination process. In this case, satellite data indicating that a probe vehicle is present on the incoming road can be identified and used to update the traffic volume estimation table.

[0019] (10) A traffic volume estimation device according to another embodiment includes a communication unit and a processing unit that executes a traffic volume estimation process to obtain an estimated value of vehicle traffic volume on an entrance road leading to a first target point on a road network. The traffic volume estimation process includes: a process of acquiring probe information of a plurality of probe vehicles via the communication unit; a first process of obtaining, based on the probe information, movement information including a time required for the probe vehicle located at a second target point on the entrance road to pass the first target point and a distance from the second target point to the first target point; and a second process of obtaining the estimated value by referring to a traffic volume estimation table that is updated based on satellite data observing an area including the first target point and the entrance road. The traffic volume estimation table stores, in association with each other, vehicle count information indicating the number of vehicles from the position of the probe vehicle on the entrance road at the time of observation to the first target point, which is counted based on the satellite data, and the movement information of the probe vehicles on the entrance road at the time of observation, which is obtained based on the probe information. In the second process, the estimated value is obtained based on the number of vehicles information corresponding to the movement information obtained in the first process.

[0020] The above configuration also makes it possible to accurately estimate the traffic volume of vehicles at a specific location such as an approach road.

[0021] (11) An update device according to another embodiment includes: a communication unit that communicates with a satellite data providing device that observes an area including a first target point on a road network and its oncoming road, and also communicates with a probe vehicle; a storage unit that accumulates probe information of the probe vehicle; and a processing unit that executes an update process that updates a traffic volume estimation table based on the satellite data. The update process includes: a process of acquiring the satellite data from the providing device; a process of counting the number of vehicles between a position of the probe vehicle on the oncoming road at the time of observation and the first target point based on the satellite data; a process of acquiring, based on the probe information, movement information including a time required for the probe vehicle on the oncoming road at the time of observation to pass the first target point from its position and a distance from the position to the first target point; and a process of registering or updating number information indicating the number of vehicles in the traffic volume estimation table by associating the movement information with the movement information.

[0022] According to the above configuration, it is possible to obtain a traffic volume estimation table in which vehicle count information obtained based on satellite data and movement information obtained based on probe information are associated with each other.

[0023] (12) In the updating device of (11), the updating process may further include a determination process of determining whether or not at least one of the plurality of probe vehicles is present on the incoming road at the time of observation based on the probe information. In this case, satellite data indicating that a probe vehicle is present on the incoming road can be identified and used to update the traffic volume estimation table.

[0024] (13) An updating device according to another embodiment includes a communication unit and a processing unit that executes an update process for updating a traffic volume estimation table based on satellite data obtained by observing an area including a first target point on a road network and an oncoming road to the first target point. The update process includes: a process of acquiring the satellite data and probe information of a probe vehicle via the communication unit; a process of counting the number of vehicles between a position of the probe vehicle on the oncoming road at the time of observation and the first target point based on the satellite data; a process of acquiring, based on the probe information, movement information including a time required for the probe vehicle on the oncoming road at the time of observation to pass the first target point from its position and a distance from the position to the first target point; and a process of registering or updating vehicle count information indicating the number of vehicles in the traffic volume estimation table by associating the movement information with the movement information.

[0025] (14) An embodiment from another perspective is a traffic volume estimation method for obtaining an estimated value of vehicle traffic volume on an entrance road leading to a first target point on a road network. This method includes: a first step of obtaining, based on probe information, movement information including the time required for a probe vehicle located at a second target point on the entrance road to pass the first target point and the distance from the second target point to the first target point; and a second step of obtaining the estimated value by referring to a traffic volume estimation table that is updated based on satellite data observing an area including the first target point and the entrance road. The traffic volume estimation table stores, in association with each other, vehicle count information indicating the number of vehicles from the position of the probe vehicle on the entrance road at the time of observation to the first target point, which is counted based on the satellite data, and the movement information of the probe vehicle on the entrance road at the time of observation, which is obtained based on the probe information. In the second step, the estimated value is obtained based on the vehicle count information corresponding to the movement information obtained in the first step.

[0026] (15) An embodiment from another perspective is a computer program that causes a computer to execute a traffic volume estimation process to obtain an estimated value of vehicle traffic volume on an entrance road leading to a first target point on a road network. This computer program causes the computer to execute: a first step of obtaining, based on probe information, movement information including the time required for a probe vehicle located at a second target point on the entrance road to pass the first target point and the distance from the second target point to the first target point; and a second step of obtaining the estimated value by referring to a traffic volume estimation table that is updated based on satellite data observing an area including the first target point and the entrance road. The traffic volume estimation table stores, in association with each other, vehicle count information indicating the number of vehicles from the position of the probe vehicle on the entrance road at the time of observation to the first target point, which is counted based on the satellite data, and the movement information of the probe vehicle on the entrance road at the time of observation, which is obtained based on the probe information. In the second step, the estimated value is obtained based on the vehicle count information corresponding to the movement information obtained in the first step.

[0027] (16) An embodiment from another viewpoint is a method for updating a traffic volume estimation table. The method includes the steps of: acquiring satellite data observing an area including a first target point on a road network and an entrance road thereto; counting the number of vehicles between a position of the probe vehicle on the entrance road at the time of observation and the first target point based on the satellite data; acquiring movement information based on probe information of the probe vehicle, the movement information including the time required for the probe vehicle on the entrance road at the time of observation to pass the first target point from the position thereof and the distance from the position thereof to the first target point; and registering or updating vehicle count information indicating the number of vehicles and the movement information in the traffic volume estimation table in association with each other.

[0028] (17) An embodiment from another viewpoint is a computer program causing a computer to execute an update process for updating a traffic volume estimation table. The computer program causes a computer to execute the following steps: acquiring satellite data observing an area including a first target point on a road network and an entrance road to the first target point; counting the number of vehicles between a position of the probe vehicle on the entrance road at the time of observation and the first target point based on the satellite data; acquiring movement information including a time required for the probe vehicle on the entrance road at the time of observation to pass the first target point from the position and a distance from the position to the first target point based on probe information of the probe vehicle; and correlating vehicle count information indicating the number of vehicles with the movement information and registering or updating the movement information in the traffic volume estimation table.

[0029] [Details of the embodiment] Preferred embodiments will be described below with reference to the drawings. Note that at least some of the embodiments described below may be combined in any manner.

[0030] [Definition of Terms] Before describing the details of this embodiment, the terms used in this specification will first be defined. "Vehicle": refers to all vehicles traveling on roads. Vehicles are not limited to those powered by internal combustion engines, and electric vehicles and hybrid cars are also included in the vehicle category. In this embodiment, the term "vehicle" simply refers to both a probe vehicle that has an on-board device capable of transmitting probe information and a normal vehicle that does not have such an on-board device.

[0031] "Probe information" refers to various types of information about a vehicle sensed by a probe vehicle traveling on a road. Probe information is also called probe data or floating car data. Probe information includes various types of vehicle data, such as the identification information of the probe vehicle, vehicle position, vehicle speed, vehicle direction, and the time of measurement of these.

[0032] "Probe vehicle": A vehicle that senses probe information and transmits the obtained probe information to the outside. Vehicles traveling on roads include both probe vehicles and other vehicles.

[0033] [Overall Configuration of the System] Fig. 1 is a perspective view showing an example of the overall configuration of an information provision system. Fig. 2 is a block diagram showing an example of the internal configuration of an information provision device included in the information provision system and an on-board device of a probe vehicle. As shown in Figs. 1 and 2, the information provision system 1 includes an information provision device 2 and an on-board device 4 mounted on a probe vehicle 3. The information provision device 2 has a function of communicating with the on-board device 4 and a function of acquiring satellite data. The satellite data is data indicating the results of observation of the ground by an artificial satellite 40, and includes captured images of the ground, etc. The on-board device 4 has a function of communicating with the information provision device 2 and transmitting probe information of the probe vehicle 3.

[0034] The information provision system 1 of this embodiment has the function of generating traffic information indicating vehicle traffic volume, etc. based on satellite data and probe information, and distributing it to the on-board device 4 of the probe vehicle 3 and the user terminal 6 of other users 5, etc.

[0035] The information providing device 2 includes a computer such as a server. The information providing device 2 may be either an on-premise server or a cloud server. The operator of the information providing device 2 may be, for example, a public service provider responsible for traffic control, the manufacturer of the probe vehicle 3, or an IT company that provides various types of information. The information providing device 2 has a function of calculating an estimated value of vehicle traffic volume in area A, which is part of a road network, based on satellite data and probe information. The information providing device 2 also has a function of distributing the calculated estimated value as traffic information to the in-vehicle device 4 of the probe vehicle 3, the user terminal 6 of another user 5, etc.

[0036] The on-board device 4 of the probe vehicle 3 is capable of wireless communication with wireless base stations 7 (e.g., mobile base stations) in various locations. The wireless base stations 7 are capable of communicating with the information providing device 2 via a public communication network 8 such as the Internet. The on-board device 4 is capable of wirelessly transmitting uplink information S1 addressed to the information providing device 2 to the wireless base station 7. The information providing device 2 is capable of transmitting downlink information S2 addressed to a specific on-board device 4 to the public communication network 8.

[0037] The user terminal 6 is a data communication terminal carried by the user 5, such as a smartphone, tablet computer, or laptop computer. The user terminal 6 is capable of wireless communication with wireless base stations 7 in various locations. The user terminal 6 can wirelessly transmit uplink information S1 addressed to the information providing device 2 to the wireless base station 7. The information providing device 2 can transmit downlink information S2 addressed to a specific user terminal 6 to the public communication network 8.

[0038] 1 and 2 show the user terminal 6 as a mobile terminal, but the user terminal 6 may also be a computer device such as a desktop personal computer installed indoors. In this case, the user terminal 6 communicates with the information providing device 2 via a fixed communication network that is connected to the public communication network 8 via an optical communication line or the like. The information providing device 2 can also provide information to other servers (not shown) that communicate via the public communication network 8.

[0039] The artificial satellite 40 flying in the sky is, for example, a commercial satellite. The artificial satellite 40 has functions such as SAR (Synthetic Aperture Radar). The artificial satellite 40 is equipped with an antenna 40a. The artificial satellite 40 observes the ground by receiving reflected waves from the ground using the antenna 40a. The artificial satellite 40 observes the ground at regular time intervals (for example, every 10 minutes to several days). The artificial satellite 40 outputs the observation results of the ground as observation data (snapshots at the time of observation). The data is transmitted from the artificial satellite 40 in the sky to a data server 42 on the ground.

[0040] The data server 42 has a function of accumulating observation data. Therefore, the data server 42 accumulates the observation data at regular time intervals. The data server 42 is connected to the public communication network 8. The data server 42 is communicatively connected to an external device via the public communication network 8. In response to a request from the external device, the data server 42 has a function of providing the observation data to the requesting external device as satellite data. The satellite data provided by the data server 42 includes not only captured images, but also location information and image capture time information for the captured images. The captured images are images of the ground captured by the artificial satellite 40. The captured images can be generated based on the observation data. The satellite data may also include complex data before being converted into captured images. The complex data is data obtained based on the observation data. The resolution of the captured images included in the satellite data is several tens of centimeters. Therefore, vehicles on the ground are clearly recognizable in the captured images of the satellite data. Furthermore, the location of the captured vehicle can be recognized based on the location information of the captured images.

[0041] The information providing device 2 of this embodiment transmits a request to the data server 42 for satellite data including an image of area A. The data server 42 transmits the satellite data to the information providing device 2 in response to the request.

[0042] [Configuration of Information Providing Device] As shown in FIG. 2 , the information providing device 2 includes a server 10. The server 10 is configured with one or more computers. The server 10 includes a processing unit 11, a storage unit 12, and a communication unit 13. The storage unit 12 is a storage device including a non-volatile memory (storage medium) such as a hard disk drive (HDD) or a solid state drive (SSD), and a volatile memory (storage medium) such as a random access memory. The storage unit 12 stores a computer program 14 to be executed by the processing unit 11 and other necessary information. The storage unit 12 also stores various databases 21, 22, and a table 24.

[0043] The processing unit 11 includes an arithmetic processing device such as a CPU (Central Processing Unit) that reads a computer program 14 stored in the storage unit 12 and performs information processing in accordance with the program 14. The processing unit 11 executes the computer program 14 stored in a computer-readable non-transitory recording medium such as the storage unit 12, thereby realizing various processing functions of the information providing device 2.

[0044] 3 is a block diagram showing some of the processing functions of the processing unit 11. As shown in FIG. 3, the processing unit 11 has the function of executing a traffic volume estimation process 11a and an update process 11b. The traffic volume estimation process 11a is a process of obtaining an estimated value of the vehicular traffic volume on an approach road leading to a first target point on the road network by referring to a traffic volume estimation table 24 described later. The update process 11b is a process of updating the traffic volume estimation table 24 based on satellite data. These processes 11a and 11b will be described in detail later.

[0045] The communication unit 13 shown in Fig. 2 is a communication interface that communicates with the wireless base station 7 and the data server 42 via the public communication network 8. The communication unit 13 can receive uplink information S1 transmitted to the device by the wireless base station 7. The communication unit 13 can transmit downlink information S2 generated by the device to the wireless base station 7. The communication unit 13 can also receive satellite data transmitted from the data server 42 via the public communication network 8. The communication unit 13 may be connected to a central device 15 of a traffic control center via a predetermined dedicated line 16. The central device 15 is a server computer that comprehensively determines signal control parameters for intersections included in a predetermined traffic control area.

[0046] The databases 21, 22 and the table 24 are databases and tables constructed in a large-capacity storage such as an HDD or SSD included in the storage unit 12. The large-capacity storage including the databases 21, 22 and the table 24 may be one or more external storage devices connected to the server 10 so as to be able to transfer data. More specifically, the databases 21 and 22 include a map database 21 and a probe database 22. The table 24 includes a traffic volume estimation table 24.

[0047] The map database 21 stores road map data (digital road maps) 25 covering the entire country. The road map data 25 includes "node data" and "link data." A node is an intersection or other nodal point on the road network. A link is a section connecting a pair of adjacent nodes. Nodes include intersections as well as entrances and exits to service areas. "Node data" is data that associates IDs assigned to domestic nodes with the location information of the nodes. "Link data" consists of data that associates the following information 1) to information 4) with the link IDs of specific links assigned to domestic roads.

[0048] Information 1) Location information of the start point, end point, and interpolation point of a specific link. Information 2) Link ID connected to the start point of a specific link. Information 3) Link ID connected to the end point of a specific link. Information 4) Link cost of a specific link.

[0049] The road map data 25 forms a network corresponding to the actual road alignment and driving direction of the road. For this reason, the road map data 25 is a network in which road sections between nodes representing intersections are connected by directed links l (lowercase L). Specifically, the road map data 25 is configured as a directed graph in which a node n is set for each intersection and each node n is connected by a pair of directed links l in opposite directions. Therefore, in the case of a one-way road, only one directed link l is connected to node n.

[0050] The road map data 25 also includes road attribute information of the road corresponding to the directed link l. The road attribute information includes, for example, the following information 1) to information 6): Information 1) Road type information indicating whether the road is an ordinary road or a toll road Information 2) Number of lanes on the road Information 3) Road width for each lane Information 4) Radius of curvature of the road Information 5) Regulated speed of the road (for example, legal speed limit) Information 6) Facility type information indicating the type of facility such as a toll gate, interchange, service area, etc.

[0051] The road map data 25 also includes specific point information. A specific point is, for example, a point that does not appear as a link or node and that can cause congestion, such as a sag on a highway. The specific point information is information that indicates the position of the specific point. The specific point appears at a position on the directed link l.

[0052] The probe database 22 stores probe information received from probe vehicles 3 pre-registered in the information providing device 2 for each identification information of the probe vehicle 3. The stored probe information includes at least the vehicle position and the time of passing. The probe information may also include vehicle data such as vehicle speed, vehicle direction, and vehicle status information (stop / running events). The sensing cycle of the probe information is a time interval that allows the travel history of the probe vehicle 3 to be accurately identified, and is, for example, 0.1 to 1.0 seconds. Therefore, the travel trajectory of the probe vehicle 3 is stored in the probe database 22 as a plurality of discrete trajectory points. Each of the plurality of trajectory points is associated with at least the vehicle position and the time of passing. The traffic volume estimation table 24 will be described in detail later.

[0053] [Configuration of In-Vehicle Device] As shown in FIG. 2 , the in-vehicle device 4 is a computer device including a processing unit 31, a storage unit 32, a communication unit 33, etc. The processing unit 31 includes an arithmetic processing device such as a CPU. The storage unit 32 is a storage device including a non-volatile memory (recording medium) such as an HDD or SSD, and a volatile memory (recording medium) such as a random access memory. The computer program 34 of the in-vehicle device 4 includes programs that cause the CPU of the processing unit 31 to sense and generate probe information, search for a route for the probe vehicle 3, and perform image processing for displaying search results on the display of the navigation device. The processing unit 31 reads the computer program 34 stored in the storage unit 32 and performs various information processes in accordance with the program 34.

[0054] The communication unit 33 is composed of a wireless communication device permanently mounted on the probe vehicle 3, or a data communication terminal (for example, a smartphone, a tablet computer, or a node-type personal computer) temporarily mounted on the probe vehicle 3. The communication unit 33 has, for example, a GPS (Global Positioning System) receiver. The processing unit 31 monitors the current position of the vehicle in almost real time based on the GPS position information received by the communication unit 33. It is preferable to use a global navigation satellite system such as GPS for positioning, but other methods may be used.

[0055] The processing unit 31 measures vehicle data such as the vehicle position, vehicle speed, vehicle direction, and CAN information of the probe vehicle 3, which is the subject vehicle, at predetermined sensing intervals (e.g., 0.5 to 1.0 seconds), and records the measured data together with the measurement time in the storage unit 32. When the vehicle data has been accumulated for a predetermined recording time (e.g., 5 minutes) in the storage unit 32, the communication unit 33 generates probe information including the accumulated vehicle data and identification information of the subject vehicle (probe vehicle 3), and transmits the generated probe information to the information providing device 2 via uplink.

[0056] The in-vehicle device 4 has an input / output interface (not shown) which may be, for example, an input / output device associated with the navigation device or an input / output device of a data communication terminal mounted on the probe vehicle 3.

[0057] [Traffic Volume Estimation Process] FIG. 4 is a diagram illustrating the traffic volume estimation process. The processing unit 11 of this embodiment executes a traffic volume estimation process 11a to obtain an estimated value of traffic volume on an incoming road leading to a first target point P1 on a road network. FIG. 4 illustrates a case where the first target point P1 is set at an intersection J1. The processing unit 11 can obtain an estimated value for each of four incoming roads leading to the intersection J1. However, the following description focuses on one of the four incoming roads, the incoming road R1. The incoming road R1 connects the intersection J2 and the intersection J1. The intersection J2 is an intersection located upstream of the intersection J1. Therefore, each vehicle shown in FIG. 4 travels from the right side to the left side of the paper.

[0058] 4 shows a case where the first target point P1 is set at the center of the intersection J1, but the first target point P1 may be set at any position within the intersection J1. The first target point P1 may also be set at a stop line for the incoming road R1 at the intersection J1. At least the intersection J1, the incoming road R1, the intersection J2, and the incoming road R11 of the intersection J2 are located within the area A.

[0059] The incoming road R1 includes a target section S. The target section S is a section set by the processing unit 11 to calculate an estimated number of vehicles. The processing unit 11 estimates the number of vehicles between the probe vehicle 3 located in the target section S and the intersection J1. In this embodiment, an upstream point defining the target section S is located between the intersections J1 and J2. A downstream point defining the target section S is located at the intersection J1 (first target point P1). The target section S can be set anywhere within the section from the intersection J1 to the intersection J2. Therefore, the target section S may be set to the entire area on the incoming road R1 from the intersection J1 to the intersection J2, or both the upstream and downstream points of the target section S may be located between the intersections J1 and J2.

[0060] As shown in Fig. 4, when a probe vehicle 3 is present within the target section S, the processing unit 11 obtains an estimate of the number of vehicles located between a predetermined point (second target point) indicating the position of the probe vehicle 3 within the target section S and a first target point P1. In Fig. 4, when the probe vehicle 3 is located at the second target point, the processing unit 11 estimates the number of vehicles 30 located between the probe vehicle 3 and the first target point P1. Note that the vehicles 30 include the probe vehicle 3 and ordinary vehicles.

[0061] 5 is a flowchart showing an example of a traffic volume estimation process. In the traffic volume estimation process 11a, the processing unit 11 first determines whether or not a probe vehicle 3 has entered the target section S (step S11 in FIG. 5). The processing unit 11 refers to the probe database 22 and determines whether or not a probe vehicle 3 has entered the target section S. The processing unit 11 repeats step S11 until it determines that a probe vehicle 3 has entered the target section S.

[0062] When it is determined in step S11 that a probe vehicle 3 has entered the target section S, the processing unit 11 acquires movement information of the probe vehicle 3 in the target section S (step S12 in FIG. 5: first processing). The movement information includes the time T required for the probe vehicle 3 located at the second target point P2 on the entrance road R1 to pass the first target point P1 (intersection J1) and the distance L from the second target point P2 to the first target point P1 (intersection J1). The second target point P2 is a point for calculating an estimated number of vehicles using the probe vehicle 3.

[0063] Fig. 6 is a diagram schematically showing locus points of a probe vehicle 3 that has entered the incoming road R1. The multiple locus points tp shown in Fig. 6 are locus points when the probe vehicle 3 passes the intersection J2 in a straight line, and then passes the incoming road R1 and the intersection J1 in a straight line. Note that in Fig. 6, the distance between adjacent locus points tp is shown relatively wide to make it easier to understand. Because the probe vehicle 3 passes the incoming road R1 and the intersection J1 in a straight line, the multiple locus points tp are arranged in a straight line in Fig. 6.

[0064] The processing unit 11 identifies a plurality of locus points tp1 within the target section S from a plurality of locus points tp included in the probe information of the probe vehicle 3 that has entered the incoming road R1. Furthermore, the processing unit 11 determines, among the plurality of locus points tp1, the locus point tp11 that is farthest from the first target point P1 as the second target point P2.

[0065] When the second target point P2 is determined, the processing unit 11 calculates the distance L based on the probe information. The processing unit 11 also calculates the time T based on the probe information. The processing unit 11 calculates the difference between the passing time at the trajectory point tp2 immediately after the probe vehicle 3 that entered the entrance road R1 passed the first target point P1 and the passing time at the trajectory point tp11. The processing unit 11 sets this difference as the time T.

[0066] In this manner, the processing unit 11 acquires movement information including the time T and the distance L based on the probe information (step S12 in FIG. 5).

[0067] As shown in Figure 5, when movement information is acquired, the processing unit 11 proceeds to step S13, refers to the traffic volume estimation table 24, and determines whether or not the number of vehicles information corresponding to the acquired movement information is registered in the traffic volume estimation table 24 (step S13 in Figure 5).

[0068] 7 is a diagram showing an example of the traffic volume estimation table 24. The traffic volume estimation table 24 is a table that is updated based on satellite data observed over an area A including the first target point P1 and the incoming road R1. The traffic volume estimation table 24 is generated for each incoming road R1.

[0069] The traffic volume estimation table 24 stores vehicle count information and movement information in association with each other. The vehicle count information is information indicating the number of vehicles from the position of the probe vehicle 3 on the approach road R1 at the time of observation to the first target point P1, counted based on an image captured by satellite data. In other words, the vehicle count information is an actual measurement counted based on satellite data. The time of observation refers to the time when the satellite 40 performed observation to obtain the satellite data (observation data), i.e., the time of image capture.

[0070] The movement information registered in the traffic volume estimation table 24 is movement information of the probe vehicle 3 on the incoming road R1 at the time of observation, obtained based on the probe information. This movement information includes the time T required for the probe vehicle 3 on the incoming road R1 at the time of observation to pass the first target point P1 from its position at the time of observation, and the distance L from the position of the probe vehicle 3 at the time of observation to the first target point P1.

[0071] Each row of the traffic volume estimation table 24 corresponds to a distance L of the movement information. Each column of the traffic volume estimation table 24 corresponds to a time T of the movement information. Each field F of the traffic volume estimation table 24 registers number of vehicles information corresponding to a combination of distance L and time T.

[0072] For example, the number of vehicles corresponding to travel information in which the distance L is 170 meters and the time T is 24 seconds is 5. Also, the number of vehicles corresponding to travel information in which the distance L is 170 meters and the time T is 292 seconds is 21.

[0073] The processing unit 11 refers to the traffic volume estimation table 24 and determines whether or not the combination of distance L and time T included in the movement information acquired in step S12 in Fig. 5 and the vehicle count information corresponding to the combination are registered in the traffic volume estimation table 24 (step S13 in Fig. 5). If it is determined in step S13 that the vehicle count information corresponding to the movement information acquired in step S12 is registered in the table 24, the processing unit 11 proceeds to step S14 and calculates an estimated value of vehicle traffic volume based on the vehicle count information corresponding to the movement information (step S14 in Fig. 5: second processing).

[0074] The vehicle count information corresponding to the movement information acquired in step S12 indicates an estimated number of vehicles between the second target point P2 and the first target point P1 based on actual measurements using satellite data. In this way, the processing unit 11 calculates an estimated number of vehicles between the second target point P2 and the first target point P1, and calculates an estimated value of vehicle traffic volume. The estimated value includes the number of vehicles indicated by the vehicle count information, the vehicle density from the second target point P2 to the first target point P1, and the like. After calculating the estimated value, the processing unit 11 returns to step S11 again and repeats the same processing. The calculated estimated value is distributed as traffic information to the in-vehicle device 4 of the probe vehicle 3, the user terminal 6 of another user 5, and the like.

[0075] When satellite data is observed, which is the observation result of area A including first target point P1 and entrance road R1, if a probe vehicle 3 is located on entrance road R1, the presence of the probe vehicle 3 can be detected based on the satellite data, as well as the presence of vehicles 30 on entrance road R1 lined up between the position of the probe vehicle 3 and the first target point P1. Therefore, this satellite data can be used to count the number of vehicles between the position of the probe vehicle 3 and the first target point P1, and the number information can be associated with the probe information.

[0076] More specifically, if the probe vehicle 3 located on the approach road R1 is also captured in the captured image of area A, the vehicles 30 on the approach road R1 lined up between the location of the probe vehicle 3 and the first target point P1 will also be captured. Therefore, this captured image can be used to count the number of vehicles between the location of the probe vehicle 3 and the first target point P1, and the number information can be associated with the probe information. This allows for the generation of a traffic volume estimation table 24 in which the number information, which is an actual measurement based on satellite data (captured image), is associated with movement information based on the probe information.

[0077] According to the above configuration, the actually counted number of vehicles can be obtained as the estimated number of vehicles by referring to the traffic volume estimation table 24 and obtaining vehicle count information corresponding to the movement information acquired in step S12 from the traffic volume estimation table 24. By using the vehicle count information based on the actually counted number of vehicles as the estimated number of vehicles, the traffic volume of vehicles 30 at a specific location such as the approach road R1 can be accurately estimated.

[0078] The first target point P1 is set at a specific point such as a point, node, or sag within a link included in area A. For example, assume that a first target point P11 is also set for another intersection J2 in FIG. 4 . The first target point P11 is a different first target point from the first target point P1. An incoming road R11 is connected to the first target point P11. The incoming road R11 is a different incoming road from the incoming road R1. The processing unit 11 also calculates an estimated value of traffic volume on the incoming road R11 connected to the first target point P11 (intersection J2). In this case, a traffic volume estimation table 24 is also generated for the incoming road R11 of the intersection J2. The processing unit 11 calculates an estimated value of traffic volume on the incoming road R11 using the traffic volume estimation table 24 (another traffic volume estimation table) for the incoming road R11.

[0079] The first target point P11 (intersection J2) is located next to the first target point P1 (intersection J1). That is, the first target point P11 is located around the first target point P1. Furthermore, it is assumed that at least a portion of the road attribute information of the incoming road R11 is the same as the road attribute information of the incoming road R1. In this embodiment, the first target point P11 being located around the first target point P1 includes, for example, the case where the first target point P11 and the first target point P1 are both set at the intersection J11 and the intersection J1, and the intersection J11 and the intersection J1 are adjacent to each other, as described above, as well as the case where several other intersections exist between the intersection J11 and the intersection J1. In this case, the processing unit 11 may refer to the traffic volume estimation table 24 for the incoming road R11 to obtain an estimated value of the traffic volume on the incoming road R1.

[0080] In FIG. 5 , if it is determined in step S13 that the number of vehicles information corresponding to the movement information acquired in step S12 is not registered in the table 24, the processing unit 11 proceeds to step S15. The traffic volume estimation table 24 is updated based on satellite data. The satellite data may include a shadow area. A shadow area is, for example, an area that is shaded when part of the approach road R1 is shaded by a building or the like. For this reason, there may be movement information and number of vehicles information that cannot be acquired based on the satellite data. The movement information and number of vehicles information that cannot be acquired is not registered in the traffic volume estimation table 24. For this reason, the number of vehicles information corresponding to the movement information acquired in step S12 may not be registered in the table 24.

[0081] In step S15, the processing unit 11 refers to the traffic volume estimation table 24 for the incoming road R11 (another traffic volume estimation table) and determines whether the combination of distance L and time T included in the movement information acquired in step S12 and the number of vehicles corresponding to the combination are registered in the traffic volume estimation table 24 for the incoming road R11 (step S15 in FIG. 5). Note that the traffic volume estimation table 24 for the incoming road R11 referred to by the processing unit 11 in step S15 is preset as another traffic volume estimation table.

[0082] If it is determined in step S15 that the vehicle count information corresponding to the movement information acquired in step S12 is registered in the table 24 for the incoming route R11, the processing unit 11 proceeds to step S14 and calculates an estimated value of the vehicle traffic volume on the incoming route R1 based on the vehicle count information corresponding to the movement information (step S14 in FIG. 5). As described above, at least a portion of the road attribute information for the incoming route R11 is the same as the road attribute information for the incoming route R1. Therefore, it can be said that the road attribute information for the incoming route R1 and the road attribute information for the incoming route R11 are similar. Because the road attribute information for the incoming route R1 and the road attribute information for the incoming route R11 are similar, the traffic volume on the incoming route R1 and the traffic volume on the incoming route R11 are similar. In this case, the vehicle count information for the incoming route R1 obtained using the traffic volume estimation table 24 for the incoming route R11 can be calculated with accuracy comparable to that of the vehicle count information for the incoming route R1 obtained using the traffic volume estimation table 24 for the incoming route R1. In other words, in this embodiment, by predetermining another traffic volume estimation table that can accurately obtain number information on the incoming road R1, an estimated value can be obtained even if the number information corresponding to the movement information obtained in step S12 is not registered in the traffic volume estimation table 24 of the first target point P1.

[0083] In this embodiment, accurate vehicle count information can be obtained by referring to the traffic volume estimation table for the first target point P11 and the incoming road R11, which have road attributes similar to those of the first target point P1 and the incoming road R1. As a result, even if the vehicle count information corresponding to the movement information obtained in step S12 is not registered in the traffic volume estimation table 24 for the first target point P1, an estimated value can be obtained complementarily.

[0084] Note that the case where at least a part of the road attribute information of the incoming road R11 is the same as the road attribute information of the incoming road R1 means, for example, that at least one of the above-mentioned six pieces of road attribute information is the same.

[0085] In Figure 5, if it is determined in step S15 that the number of vehicles information corresponding to the movement information obtained in step S12 is not registered in the table 24 of the entrance route R11, the processing unit 11 returns to step S11 again and repeats the same processing.

[0086] In the above traffic volume estimation process, as shown in FIG. 6 , the second target point P2 is set to the locus point tp11 among the multiple locus points tp1 that is the farthest from the first target point P1. However, the second target point P2 may be any one of the multiple locus points tp1. In this case, a locus point tp1 suitable for the second target point P2 can be set from the multiple locus points tp1 within the target section S. Note that, by setting the second target point P2 as the locus point tp11 that is the closest from the first target point P1, as in this embodiment, the time required to pass from the second target point P2 to the first target point P1 is relatively long, thereby increasing the amount of information reflected in the estimated value obtained later.

[0087] Alternatively, a plurality of locus points tp1 may be selected from the plurality of locus points tp1, and the selected plurality of locus points tp1 may be set as the plurality of second target points P2. Furthermore, each of the plurality of locus points tp1 may be set as the second target point P2. In this case, a plurality of estimated values ​​can be obtained from the probe information of one probe vehicle 3, and processing can be performed to improve the accuracy of the estimated value using the plurality of estimated values, such as calculating an average value of the plurality of estimated values.

[0088] Furthermore, if multiple probe vehicles 3 are present simultaneously within the target section S, the estimated value may be calculated based on all of the probe vehicles 3, or may be calculated based on a portion of the multiple probe vehicles 3.

[0089] 8 is a flowchart showing an example of the update process. The processing unit 11 of this embodiment executes an update process 11b to update the traffic volume estimation table 24. The processing unit 11 executes the update process asynchronously with the traffic volume estimation process.

[0090] In the update process, the processing unit 11 first determines whether the latest satellite data has been acquired (step S21 in FIG. 8). The processing unit 11 periodically sends a request for satellite data to the data server 42 (FIGS. 1 and 2). The processing unit 11 references the satellite data sent from the data server 42 in response to this request and determines whether the latest satellite data has been acquired. The latest satellite data refers to satellite data captured at a more recent time than the most recently acquired satellite data.

[0091] The processing unit 11 repeats step S21 until it determines that the latest satellite data has been acquired. If it determines that the latest satellite data has been acquired, the processing unit 11 determines whether or not a probe vehicle 3 is imaged in the target section S (entrance road R1) in the captured image included in the latest satellite data (step S22 in FIG. 8 ). In step S22, the processing unit 11 references the probe information and determines whether or not the probe vehicle 3 is present in the target section S at the image capture time included in the satellite data. If the probe vehicle 3 is present in the target section S at the image capture time included in the satellite data, it can be determined that the probe vehicle 3 is imaged in the target section S in the satellite data (captured image). On the other hand, if it determines that the probe vehicle 3 is not imaged in the target section S in the satellite data, the processing unit 11 returns to step S21 and repeats steps S21 and S22. In this way, in step S22, a determination process is executed to determine whether or not a probe vehicle 3 is present in the target section S (entrance road) at the time of observation based on the probe information.

[0092] When the processing unit 11 determines that the probe vehicle 3 is captured in the target section S in the satellite data, it proceeds to step S23 in FIG. 8 and acquires vehicle count information (step S23 in FIG. 8). FIG. 9 is a diagram schematically illustrating a portion of the captured image of the first target point P1 and the entrance road R1 included in the satellite data. The processing unit 11 performs image processing and the like on the captured image included in the satellite data to identify the vehicles 30 on the entrance road R1. The processing unit 11 identifies the vehicles 30 on the entrance road R1 based on the processed image after image processing. Five vehicles 30 are present in the target section S in FIG. 9. The processing unit 11 identifies these five vehicles 30 and acquires position information for each of the five vehicles 30.

[0093] Next, the processing unit 11 compares the locus point tp3 of the probe vehicle 3 determined to be imaged in the target section S in the satellite data with the position information of each of the five vehicles 30. Note that the locus point tp3 used in the comparison is the locus point at the image capture time included in the satellite data. As a result of the comparison, the processing unit 11 identifies, as the probe vehicle 3, the vehicle 30 among the five vehicles 30 whose position information overlaps with the position of the locus point tp3. In FIG. 9 , the position of the fourth vehicle 30 from the intersection J1 overlaps with the position of the locus point tp3. This makes it possible to identify the probe vehicle 3 on the target section S imaged in the satellite data. The processing unit 11 counts the number of vehicles between the identified position (locus point tp3) of the probe vehicle 3 and the first target point P1, and acquires the counted number of vehicles as vehicle count information. In FIG. 9 , the processing unit 11 counts the number of vehicles, including the probe vehicle 3, between the position (locus point tp3) of the probe vehicle 3 and the first target point P1 as four.

[0094] 8, after acquiring the number information in step S23, the processing unit 11 proceeds to step S24 and acquires movement information of the probe vehicle 3 located at the locus point tp3 (step S24 in FIG. 8). The movement information includes the time T required for the probe vehicle 3 captured in the satellite data to travel from its position (locus point tp3) to the first target point P1, and the distance L from its position (locus point tp3) to the first target point P1. The method for calculating the time T and the distance L is the same as the method for calculating the time T and the distance L included in the movement information in the traffic volume estimation process. Therefore, the movement information in step S24 is acquired by the same method as in the traffic volume estimation process.

[0095] When the movement information is acquired, the processing unit 11 associates the number information acquired in step S23 with the movement information acquired in step S24 and registers them in the traffic volume estimation table 24 (step S25 in Figure 8), and returns to step S21.

[0096] Furthermore, in step S25, for example, if the movement information acquired in step S24 has already been registered in the traffic volume estimation table 24, the processing unit 11 overwrites the newly acquired movement information and the corresponding vehicle count information to update the traffic volume estimation table 24. This causes the most recent satellite data to be reflected in the traffic volume estimation table 24, and the accuracy of the information registered in the traffic volume estimation table 24 can be further improved.

[0097] By repeating the update process, many patterns of combinations of movement information (time T and distance L) and number of vehicles information are registered, and a complete traffic volume estimation table 24 is generated. In this way, by performing the update process, it is possible to obtain a traffic volume estimation table 24 in which number of vehicles information obtained based on satellite data and movement information obtained based on probe information are associated with each other.

[0098] 8 includes a process (determination process) for determining, based on the probe information, whether or not the probe vehicle 3 is captured in the target section S of the incoming road R1 in the acquired satellite data. In this case, satellite data indicating that the probe vehicle 3 is present in the target section S (incoming road) can be identified and used to update the traffic volume estimation table 24. That is, without using an image in which the probe vehicle 3 is not captured in the target section S, an image in which the probe vehicle 3 is captured in the target section S can be identified and used to update the traffic volume estimation table 24.

[0099] Furthermore, in the update process of this embodiment, the case where one probe vehicle 3 is photographed in the target section S in the satellite data has been exemplified, but it is also possible that there are multiple probe vehicles 3 photographed. When multiple probe vehicles 3 are photographed, the above-described update process is performed for each of the multiple probe vehicles 3.

[0100] In the update process of this embodiment, it may be determined that the same probe vehicle 3 exists in each of the plurality of satellite data due to congestion on the incoming road R1. In this case, the above-described update process is also performed for each of the same probe vehicles 3 that exist in the plurality of satellite data.

[0101] In this embodiment, it is determined whether or not a probe vehicle 3 is present in the target section S, and if a probe vehicle 3 is present, movement information of the probe vehicle 3 is acquired. The movement information includes the time T required for the probe vehicle 3 to pass the first target point P1 (intersection J1). Therefore, if the time T is extremely long or if the probe vehicle 3 has exited the target section S, it is possible that some kind of abnormality has occurred in the target section S. For example, if the vehicle 3 is immobilized due to a traffic accident or heavy snowfall, it will be difficult for the probe vehicle 3 to exit the target section S. Therefore, in this embodiment, it is also possible to determine that some kind of abnormality has occurred in the target section S if the time T included in the acquired movement information is longer than the time T registered in the traffic volume estimation table 24 or if the time T cannot be acquired.

[0102] [Variations of the first target point P1] FIG. 10 is a schematic diagram of a sag section U on a highway as viewed from the side. In FIG. 10, each vehicle 30 travels from the right side to the left side of the page. As shown in FIG. 10, the sag section U is a portion of the road where a downhill slope changes to an uphill slope. In FIG. 10, a first target point P1 is set at the sag section U. A target section S is set at an approach road R1, which is a downhill slope connected to the sag section U. The sag section U is a specific point, and is located at a predetermined point within the link. The processing unit 11 can also obtain estimated values ​​of traffic volume at the first target point P1 and the approach road R1 as shown in FIG. 10.

[0103] Generally, congestion is likely to occur at the sag section U. In response to this, the processing unit 11 can obtain an estimated value of the traffic volume of vehicles on the approach road R1 of the sag section U, and can accurately estimate the traffic volume at the sag section U where congestion is likely to occur.

[0104] [Others] Note that the embodiments disclosed herein should be considered to be illustrative in all respects and not restrictive. For example, in the above embodiment, the information providing device 2 executes the traffic volume estimation process and the update process. However, as shown in FIG. 11 , the traffic volume estimation process and the update process may be executed by a traffic volume estimation device 50 connected to a public communication network 8. The information providing system 1 shown in FIG. 11 is similar to the information providing system 1 of the above embodiment, except that the traffic volume estimation device 50 is connected to the public communication network 8. In FIG. 11 , the traffic volume estimation device 50 includes a processing unit 51, a memory unit 52, and a communication unit 53. The processing unit 51, the memory unit 52, and the communication unit 53 have the same configurations as the processing unit 11, the memory unit 12, and the communication unit 13 of the server 10.

[0105] The processing unit 51 performs processing to acquire necessary information, such as probe information and information related to the traffic volume estimation table 24, from the information providing device 2 via the communication unit 53. The processing unit 51 also has a function to execute traffic volume estimation processing and update processing using the acquired information. Therefore, the traffic volume estimation device 50 can execute traffic volume estimation processing and update processing in place of the information providing device 2.

[0106] The processing unit 51 provides the traffic volume estimation value obtained by the traffic volume estimation process to the information providing device 2. The processing unit 51 also performs an update process to update the traffic volume estimation table 24 held by the information providing device 2. In this case, the traffic volume estimation device 50 can execute the traffic volume estimation process and the update process even if the traffic volume estimation device 50 does not have the probe database 22 or the traffic volume estimation table 24.

[0107] Furthermore, although FIG. 11 illustrates an example in which the traffic volume estimation device 50 is connected to the public communication network 8, the traffic volume estimation device 50 and the information providing device 2 may be connected to each other so that they can communicate with each other, and the traffic volume estimation device 50 and the information providing device 2 may be connected to each other by a LAN, a dedicated line, or the like.

[0108] In the above embodiment, the traffic volume estimation process and the update process are performed mainly using captured images among the satellite data. However, the traffic volume estimation process and the update process may be performed using complex data or data equivalent thereto instead of captured images.

[0109] The scope of the present invention is defined by the claims, not by the meaning described above, and is intended to include meanings equivalent to the claims and all modifications within the scope thereof.

[0110] REFERENCE SIGNS LIST 1 Information provision system 2 Information provision device 3 Probe vehicle 4 In-vehicle device 5 User 6 User terminal 7 Wireless base station 8 Public communication network 10 Server 11 Processing unit 11a Traffic volume estimation process 11b Update process 12 Storage unit 13 Communication unit 14 Computer program 15 Central device 16 Dedicated line 21 Map database 22 Probe database 24 Traffic volume estimation table 25 Road map data 30 Vehicle 31 Processing unit 32 Storage unit 33 Communication unit 34 Computer program 40 Artificial satellite 40a Antenna 42 Data server 50 Traffic volume estimation device 51 Processing unit 52 Storage unit 53 Communication unit A Area F Field J1 Intersection J2 Intersection L Distance l Directed link P1, P11 First target point P2 Second target point R1, R11: Approach road R2: Approach road S: Target section S1: Uplink information S2: Downlink information U: Sag section tp, tp1, tp11, tp2, tp3: Trajectory points

Claims

1. A communication unit that communicates with a plurality of probe vehicles; A storage unit that stores probe information of the plurality of probe vehicles; A processing unit that executes a traffic volume estimation process for obtaining an estimated value of the traffic volume of vehicles on an inflow road connected to a first target point on a road network, comprising: The traffic volume estimation process includes: A first process of obtaining movement information including the time required for the probe vehicle located at a second target point on the inflow road to pass through the first target point and the distance from the second target point to the first target point, based on the probe information; A second process of obtaining the estimated value by referring to a traffic volume estimation table updated based on satellite data observing the area including the first target point and the inflow road; In the traffic volume estimation table, the number information indicating the number of vehicles from the position of the probe vehicle existing on the inflow road at the time of observation to the first target point, which is counted based on the satellite data, and the movement information of the probe vehicle existing on the inflow road at the time of observation, which is obtained based on the probe information, are registered in association with each other; In the second process, the estimated value is obtained based on the number information corresponding to the movement information obtained in the first process. A traffic volume estimation device.

2. The inflow road includes a target section, The second target point is at least one of the plurality of trajectory points within the target section included in the probe information of the probe vehicle that has entered the inflow road. The traffic volume estimation device according to Claim 1.

3. The second target point is the trajectory point farthest from the first target point among the plurality of trajectory points. The traffic volume estimation device according to Claim 2.

4. Each of the plurality of trajectory points within the target section on the inflow road included in the probe information of the probe vehicle that has entered the inflow road is the second target point. The traffic volume estimation device according to Claim 1.

5. In the second process, when the number information corresponding to the movement information obtained in the first process is not registered in the traffic volume estimation table, another traffic volume estimation table determined in advance is referred to, and the estimated value is obtained. The traffic volume estimation device according to Claim 1. Another traffic volume estimation table: A table for obtaining an estimated value of the traffic volume of vehicles on another inflow road different from the inflow road, and is a table different from the traffic volume estimation table.

6. The first target location includes locations, nodes, and sag portions within links included in the road network The traffic volume estimation device according to any one of claims 1 to 5

7. The estimated value includes the number of vehicles indicated by the vehicle number information and the vehicle density from the second target location to the first target location The traffic volume estimation device according to any one of claims 1 to 5

8. The communication unit can communicate with the satellite data providing device The processing unit executes an update process for updating the traffic volume estimation table based on the satellite data acquired from the providing device The traffic volume estimation device according to any one of claims 1 to 5

9. The update process includes A process of acquiring the satellite data from the providing device A determination process of determining whether or not the probe vehicle exists on the inflow road at the time of observation based on the probe information A process of determining whether or not to use the acquired satellite data for updating the traffic volume estimation table according to the result of the determination process including The traffic volume estimation device according to claim 8

10. A communication unit A processing unit that executes a traffic volume estimation process for obtaining an estimated value of the traffic volume of vehicles on an inflow road connected to a first target location on the road network, comprising The traffic volume estimation process includes A process of acquiring probe information of a plurality of probe vehicles via the communication unit A first process of obtaining movement information including the time required for the probe vehicle located at a second target location on the inflow road to pass through the first target location and the distance from the second target location to the first target location based on the probe information A second process of obtaining the estimated value by referring to a traffic volume estimation table updated based on satellite data observing the area including the first target location and the inflow road, including In the traffic volume estimation table, the number information indicating the number of vehicles from the position of the probe vehicle existing on the inflow road at the time of observation to the first target location counted based on the satellite data and the movement information of the probe vehicle existing on the inflow road at the time of observation obtained based on the probe information are registered in association with each other In the second process, the estimated value is obtained based on the number information corresponding to the movement information obtained in the first process Traffic volume estimation device

11. A communication unit that communicates with a satellite data providing device that observes a region including a first target point on a road network and its inflow road, and communicates with a probe vehicle; A storage unit that stores probe information of the probe vehicle; A processing unit that executes an update process for updating a traffic volume estimation table based on the satellite data, comprising: The update process includes: A process of acquiring the satellite data from the providing device; A process of counting the number of vehicles between the position of the probe vehicle existing on the inflow road at the time of observation and the first target point based on the satellite data; A process of obtaining movement information including the time required for the probe vehicle existing on the inflow road at the time of observation to pass from the position to the first target point and the distance from the position to the first target point based on the probe information; A process of registering or updating the traffic volume estimation table by associating the number information indicating the number of vehicles with the movement information. An update device.

12. The update process further includes: A determination process of determining whether or not at least one probe vehicle among the plurality of probe vehicles exists on the inflow road at the time of observation based on the probe information. The update device according to claim 11.

13. A communication unit; A processing unit that executes an update process for updating a traffic volume estimation table based on satellite data that observes a region including a first target point on a road network and its inflow road, comprising: The update process includes: A process of acquiring the satellite data and the probe information of the probe vehicle via the communication unit; A process of counting the number of vehicles between the position of the probe vehicle existing on the inflow road at the time of observation and the first target point based on the satellite data; A process of obtaining movement information including the time required for the probe vehicle existing on the inflow road at the time of observation to pass from the position to the first target point and the distance from the position to the first target point based on the probe information; A process of registering or updating the traffic volume estimation table by associating the number information indicating the number of vehicles with the movement information. An update device.

14. A traffic volume estimation method for obtaining an estimated value of the traffic volume of vehicles on an inflow road connected to a first target point on a road network, comprising: A first step of obtaining movement information including the time required for a probe vehicle located at a second target point on the inflow road to pass the first target point and the distance from the second target point to the first target point based on probe information; A second step of obtaining the estimated value by referring to a traffic volume estimation table updated based on satellite data observing the area including the first target point and the inflow road, including: In the traffic volume estimation table, the number information indicating the number of vehicles from the position of the probe vehicle existing on the inflow road at the time of observation to the first target point counted based on the satellite data and the movement information of the probe vehicle existing on the inflow road at the time of observation obtained based on the probe information are registered in association with each other. In the second step, the estimated value is obtained based on the number information corresponding to the movement information obtained in the first step. Traffic volume estimation method.

15. A computer program for causing a computer to execute a traffic volume estimation process for obtaining an estimated value of the traffic volume of vehicles on an inflow road connected to a first target point on a road network, Causing the computer to A first step of obtaining movement information including the time required for a probe vehicle located at a second target point on the inflow road to pass the first target point and the distance from the second target point to the first target point based on probe information; A second step of obtaining the estimated value by referring to a traffic volume estimation table updated based on satellite data observing the area including the first target point and the inflow road, and In the traffic volume estimation table, the number information indicating the number of vehicles from the position of the probe vehicle existing on the inflow road at the time of observation to the first target point counted based on the satellite data and the movement information of the probe vehicle existing on the inflow road at the time of observation obtained based on the probe information are registered in association with each other. In the second step, the estimated value is obtained based on the number information corresponding to the movement information obtained in the first step. Computer program.

16. An update method for updating a traffic volume estimation table, including: A step of obtaining satellite data observing an area including a first target point on a road network and its inflow road; counting, based on the satellite data, the number of vehicles between the position of the probe vehicle present on the inflow road at the time of observation and the first target point; obtaining, based on the probe information of the probe vehicle, movement information including the time required for the probe vehicle present on the inflow road at the time of observation to pass from the position to the first target point and the distance from the position to the first target point; registering or updating in the traffic volume estimation table by associating the number information indicating the number of vehicles with the movement information; updating method.

17. A computer program for causing a computer to execute an update process for updating a traffic volume estimation table, wherein the computer is caused to acquire satellite data obtained by observing a region including a first target point on a road network and its inflow road; count, based on the satellite data, the number of vehicles between the position of the probe vehicle present on the inflow road at the time of observation and the first target point; obtain, based on the probe information of the probe vehicle, movement information including the time required for the probe vehicle present on the inflow road at the time of observation to pass from the position to the first target point and the distance from the position to the first target point; execute a step of registering or updating in the traffic volume estimation table by associating the number information indicating the number of vehicles with the movement information; computer program.