Reachable Area Guidance System

Abstract

Providing technology that increases the possibility of rapidly performing the process of identifying reachable areas by tracing paths in any direction. [Solution] The reachable range guidance system comprises: a map information acquisition unit that acquires map information representing a road network expressed by links and nodes which are the endpoints of the links; a division unit that divides a predetermined area in which a plurality of the nodes exist into a plurality of cells which are areas with continuous links as boundary lines; a reachable node acquisition unit that acquires as reachable nodes the nodes that can be reached by following the links on the boundary lines from the current position using the remaining energy of the vehicle, and the nodes within the cells that can be reached by following the links on the boundary lines; and a guidance control unit that causes a guidance unit to guide the reachable range indicated by the reachable nodes.

Description

Technical Field

[0004] , ,

[0005] , , , , ,

[0001] The present invention relates to a reachable range guidance system.

Background Art

[0002] Conventionally, a technique for displaying a reachable range using the remaining energy of a vehicle is known. For example, in Patent Document 1, a technique is disclosed in which routes to a plurality of provisional destinations are searched, points at which the remaining charge of the vehicle reaches a predetermined value are specified on each route, and a travelable area is specified by connecting the points. <00000!0>

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the conventional technique, since the reachable range is specified by searching for routes for a small number of representative points, the reachable range is inaccurate for positions different from the representative points. However, if a route is searched for an arbitrary point existing in an arbitrary direction from the current position of the vehicle, the number of possible routes becomes extremely large. Therefore, conventionally, it has been difficult to specify an accurate reachable range within a realistic required time. The present invention has been made in view of the above problems, and an object thereof is to provide a technique that increases the possibility of quickly performing a process of specifying a reachable range by following a route in an arbitrary direction.

Means for Solving the Problems

[0005] To achieve the above objective, the reachable range guidance system comprises: a map information acquisition unit that acquires map information showing a road network represented by links and nodes which are the endpoints of the links; a division unit that divides a predetermined area where a plurality of the nodes exist into a plurality of cells which are areas with continuous links as boundaries; a reachable node acquisition unit that uses the vehicle's remaining energy to acquire the nodes that can be reached by following the links on the boundary line from the current position, and the nodes within the cells that can be reached by following the links on the boundary line, as reachable nodes; and a guidance control unit that causes the guidance unit to guide the vehicle through the reachable range indicated by the reachable nodes.

[0006] In other words, the reachability guidance system converts the road network into boundary lines composed of continuous links and cells enclosed by those boundaries. The reachability node acquisition unit then identifies reachable nodes based on whether or not the nodes and cells on the boundary lines are reachable, using the vehicle's remaining energy. As a result, the reachability range can be determined much faster compared to a configuration that identifies reachable nodes based on the road network before conversion to boundaries and cells. Furthermore, when determining the reachability range, there is a low possibility that only a specific direction from the current location will be accurately analyzed while other directions will be inaccurate. Therefore, it is possible to increase the likelihood of quickly determining the reachability range by following a route in any direction. [Brief explanation of the drawing]

[0007] [Figure 1] This is a block diagram of the reachable range guidance system. [Figure 2] This is a flowchart of the cell generation process. [Figure 3] Figures 3A and 3B are diagrams illustrating cell division. [Figure 4] This diagram schematically shows cells and their boundaries. [Figure 5] This is a flowchart of the judgment information generation process. [Figure 6]This is a schematic diagram showing cells and the nodes inside and outside of those cells. [Figure 7] This is a flowchart for determining the reachable range. [Figure 8] This diagram shows the search for reachable nodes. [Modes for carrying out the invention]

[0008] Here, embodiments of the present invention will be described in the following order. (1) Configuration of the reachability guidance system: (2) Cell generation process: (3) Judgment information generation process: (4) Processing to determine reachable range: (5) Other embodiments:

[0009] (1) Configuration of the reachability guidance system: Figure 1 is a block diagram showing the configuration of a reachable range guidance system 10 according to one embodiment. In this embodiment, the reachable range guidance system 10 can communicate with a communication unit 600 mounted on a vehicle 100. Note that there may be multiple vehicles 100. In this embodiment, the vehicle 100 is equipped with a navigation system 200, a GNSS receiver 210, a vehicle speed sensor 220, a gyro sensor 230, a user I / F unit 240, a drive control ECU 300, a motor 400, a battery 500, and a communication unit 600.

[0010] In this embodiment, the vehicle 100 is a battery-powered electric vehicle (EV) that runs using energy stored in the battery 500. The motor 400 rotates by receiving power from the battery 500. The motor 400 is connected to a power transmission mechanism (not shown), and the vehicle is driven by the power transmission mechanism converting the rotational driving force into propulsion force. Furthermore, when torque is transmitted to the motor 400 via the power transmission mechanism as the vehicle 100 moves, regenerative power is generated and the battery 500 is charged.

[0011] The motor 400 is controlled by the drive control ECU 300. The drive control ECU 300 can output control signals to the motor 400, controlling it to generate rotational driving force. The drive control ECU 300 can also obtain the State of Charge (SOC) [%] from the battery 500 and notify the navigation system 200.

[0012] The navigation system 200 includes a control unit (not shown) equipped with a CPU, ROM, RAM, etc., and a storage medium (not shown). The storage medium stores various programs, including a route search program for searching for a planned route to the destination, a route guidance program for guiding the user to travel along the planned route, and a display program that shows the reachable range using the remaining energy of the battery 500, as well as map information. This map information has the same configuration as the map information 30a described later and is used for determining the current location, displaying maps, searching for routes, etc.

[0013] The GNSS receiver 210 receives radio waves from GNSS (Global Navigation Satellite System) satellites and outputs a signal to calculate the vehicle's current position via an interface (not shown). The vehicle speed sensor 220 outputs a signal corresponding to the rotational speed of the vehicle's wheels. The navigation system 200 acquires the vehicle speed based on the signal from the vehicle speed sensor 220. The gyro sensor 230 detects the angular acceleration of the vehicle 100 during a turn in the horizontal plane and outputs a signal corresponding to the vehicle's orientation. The navigation system 200 acquires the direction of travel of the vehicle 100 based on the signal from the gyro sensor 230. The navigation system 200 acquires the vehicle's current position by identifying the vehicle's trajectory based on the output signals of the vehicle speed sensor 220 and the gyro sensor 230. The output signals from the GNSS receiver 210 are used for correction of the vehicle's current position identified from the vehicle speed sensor 220 and the gyro sensor 230.

[0014] The user I / F unit 240 is an interface unit for providing various information to the user (the passenger of the vehicle 100) and inputting the instructions of the user. Specifically, it includes a display unit such as a touch panel display and a speaker. The navigation system 200 outputs a control signal to the touch panel display as the display unit to output various images such as maps. Further, the navigation system 200 outputs a control signal to the speaker to output various guidance voices. Also, the navigation system 200 acquires the operation of the user based on the touch operation on the touch panel display.

[0015] The communication unit 600 is equipped with a circuit for wireless communication with the reachable range guidance system 10. The navigation system 200 can perform wireless communication with the reachable range guidance system through the communication unit 600. In the present embodiment, when the navigation system 200 executes the function of displaying the reachable range, it acquires the current position of the vehicle 100 based on the outputs of the GNSS reception unit 210, the vehicle speed sensor 220, and the gyro sensor 230. Also, the navigation system 200 acquires the SOC indicating the current remaining energy of the vehicle 100 from the drive control ECU 300. Then, the navigation system 200 transmits the current position of the vehicle 100 and the current SOC of the vehicle 100 through the communication unit 600.

[0016] The reachable range guidance system 10 generates information indicating the range that the vehicle 100 can reach using the remaining energy based on the current position of the vehicle 100 and the current SOC of the vehicle 100, and transmits it to the vehicle 100. The navigation system 200 acquires the information, controls the display unit (touch panel display) of the user I / F unit 240, and causes the reachable range to be displayed on the display unit.

[0017] The reachable range guidance system 10 is a computer having a function of acquiring a reachable range, and cooperates with the vehicle 100. In the present embodiment, the reachable range guidance system 10 includes a control unit 20, a storage medium 30, and a communication unit 40. The control unit 20 can execute a program recorded in the storage medium 30 or the like. The communication unit 40 includes a circuit for communicating with the vehicle 100. The control unit 20 can communicate with the vehicle 100 via the communication unit 40.

[0018] Map information 30a is recorded in the storage medium 30 in advance. The map information 30a is information indicating a road network represented by links and nodes that are the endpoints of the links. Specifically, the map information 30a includes node data indicating the positions of nodes virtually set on a road on which a vehicle travels, that is, an actual road, shape interpolation point data indicating the positions of shape interpolation points for specifying the shape of the road between nodes, link data indicating the connection between nodes, facility data indicating the positions of facilities existing around the road, and the like. Various types of information for each road section may be associated with the link data. For example, information indicating the traveling direction of the vehicle on the link, that is, information indicating the traveling direction in the case of one-way traffic or information indicating two-way traffic, is associated with the link data.

[0019] The segmented map information 30b is information generated by transforming the road network shown in map information 30a. Specifically, the segmented map information 30b is generated by dividing the road network into multiple cells and includes information indicating cells containing multiple nodes and continuous links corresponding to the cell boundaries. In this embodiment, nodes are classified as either nodes belonging to a cell or nodes on the boundary line. The boundary line is composed of nodes and links. That is, links are information indicating the connection between nodes and represent road sections. Continuous road sections composed of continuous links can become cell boundaries. Furthermore, the area inside the boundary line and enclosed by the boundary line is a cell, and there is one or more nodes within a cell. Therefore, a cell can be said to be a discontinuous set of nodes that are close to each other and connected to each other. The boundary line is composed of all nodes not included in a cell.

[0020] In the segmented map information 30b, information indicating cells and boundaries may be defined in various ways. For example, one example is in which the segmented map information 30b is defined in a format in which identification information for identifying cells is associated with identification information for nodes contained in cells, and identification information indicating that a boundary is associated with identification information indicating links and nodes that constitute a boundary. A method for generating segmented map information 30b based on map information 30a will be described later.

[0021] In the segmented map information 30b according to this embodiment, determination information for determining whether or not a cell is reachable is associated with information indicating a cell. In this embodiment, the determination information indicates whether or not any node within the cell is reachable from an external node, which is a node adjacent to the cell outside the cell and linked to a node within the cell. In this embodiment, the determination information indicates the energy required to travel from the external node to the node within the cell that requires the greatest energy. The determination information is associated with each external node. Details of the process for obtaining the determination information will be described later.

[0022] The control unit 20 is equipped with a CPU, RAM, ROM, etc., and can execute various programs stored in the storage medium 30. In this embodiment, one of these programs is a reachable range guidance program 21. When the reachable range guidance program 21 is executed, the control unit 20 functions as a map information acquisition unit 21a, a division unit 21b, a reachable node acquisition unit 21c, and a guidance control unit 21d.

[0023] The map information acquisition unit 21a has the function of acquiring map information that shows a road network represented by links and nodes which are the endpoints of those links. In other words, the control unit 20 uses the function of the map information acquisition unit 21a to refer to the storage medium 30 and acquire map information 30a.

[0024] The division unit 21b has the function of dividing a predetermined area containing multiple nodes into multiple cells, which are areas bounded by consecutive links. In this embodiment, the predetermined area is the area containing all the nodes indicated by the map information 30a. That is, in this embodiment, the entire road network indicated by the map information 30a is converted into divided map information 30b in advance.

[0025] The control unit 20, using the functions of the division unit 21b, refers to the map information 30a and obtains information indicating nodes and links within a predetermined area. Then, using the functions of the division unit 21b, the control unit 20 divides the area using boundary lines consisting of continuous links within the predetermined area so that the area of ​​the divided areas is as equal as possible (details will be described later). Once cells are obtained through division, the control unit 20 generates divided map information 30b indicating the cells and boundary lines and stores it in the storage medium 30.

[0026] The reachable node acquisition unit 21c has the function of acquiring reachable nodes, which are nodes that can be reached by following links on the boundary line from the current position, and nodes within cells that can be reached by following links on the boundary line, using the remaining energy of the vehicle. Specifically, the control unit 20 acquires the current position of the vehicle 100 transmitted from the vehicle 100 using the function of the reachable node acquisition unit 21c, and if the current position of the vehicle 100 is on the boundary line of the divided map information 30b, it searches for the node on the boundary line closest to the current position and extends the path. Based on the SOC of the vehicle 100 transmitted from the vehicle 100, the control unit 20 identifies nodes that can be reached on the boundary line from the current position within a range where the SOC does not fall below a lower limit, and considers them to be reachable nodes. The control unit 20 searches for paths in all directions on the boundary line and identifies reachable nodes on the paths extending in each direction. Details of this process will be described later.

[0027] If the current location is within a cell, the control unit 20 can identify the path to the node adjacent to the cell and the amount of SOC reduction, and then perform the same processing as described above for searching the path along the boundary line beyond that node. If the SOC at the vehicle 100's current location is low and it cannot reach a node outside the cell, the number of searches is relatively small, so it is sufficient to search all paths within the cell and determine whether it is possible to reach each node. Alternatively, the predetermined area for which segmented map information 30b is generated may change dynamically according to the vehicle 100's current location, in which case the boundary line may be determined such that the vehicle 100's current location lies on the boundary line.

[0028] When reachable nodes on the boundary line are identified, the control unit 20 identifies reachable cells by following the links on the boundary line. As described above, in the segmented map information 30b, determination information is associated with each external node adjacent to each cell. When the path on the boundary line reaches an external node adjacent to a cell, the control unit 20 determines whether the State of Charge (SOC) when the vehicle 100 reaches the external node is greater than the determination information for the energy associated with that external node. If the SOC when the vehicle 100 reaches the external node is greater than the determination information, the control unit 20 determines that it is possible to reach a node within the cell from that external node. If it is determined that it is possible to reach a node within the cell from at least one of the external nodes adjacent to the cell, the control unit 20 considers that the vehicle 100 is reachable to that cell. In this embodiment, being reachable to a cell means that it is possible to reach all nodes within the cell using the remaining energy of the vehicle 100.

[0029] If it is determined that the cell is not reachable, the control unit 20 identifies the route and the amount of SOC reduction from an external node adjacent to the cell to any node within the cell, and determines whether each node is reachable. The number of nodes within a cell is small compared to the total number of nodes that can be reached from the vehicle 100's current position, so searching for a route to all nodes within the cell can be done in a relatively short time.

[0030] The guidance control unit 21d has the function of guiding the vehicle to the reachable range indicated by the reachable nodes. The control unit 20 generates information indicating the reachable range based on information indicating reachable nodes that can be reached with the vehicle 100's remaining energy. Then, the control unit 20 transmits the information indicating the reachable range to the vehicle 100 via the communication unit 40, using the function of the guidance control unit 21d. The navigation system 200 of the vehicle 100 acquires the information indicating the reachable range via the communication unit 600 and displays the reachable range on the display unit of the user I / F unit 240. The display of the reachable range can take various forms. For example, one configuration is to display a map on the display unit that includes the vehicle 100's current position and the reachable range, and to display a line indicating the reachable range on the map. Of course, it is also possible to display only the outermost reachable nodes from the vehicle 100's perspective and not display a line, or to display all reachable nodes on the map to indicate the reachable range.

[0031] With the above configuration, it is possible to search for nodes reachable with the vehicle 100's remaining energy based on cells and boundaries. Therefore, it is not necessary to individually search for routes to all nodes around the vehicle 100. For this reason, the reachable range can be determined much faster compared to a configuration that identifies reachable nodes based on boundaries and the road network before conversion to cells.

[0032] Furthermore, in this embodiment, the discoverable nodes are not limited to nodes located in a specific direction from the vehicle 100, nor are they limited to representative nodes. Therefore, it is unlikely that only a specific direction from the current position will be accurately analyzed while other directions will be inaccurate. For this reason, this embodiment increases the possibility of rapidly performing the process of identifying the reachable range by following a path in any direction.

[0033] (2) Cell generation process: Next, the cell generation process performed by the control unit 20 will be described in detail. Figure 2 is a flowchart of the cell generation process. In this embodiment, the cell generation process only needs to be performed before the reachable range acquisition process is executed.

[0034] When the cell generation process begins, the control unit 20 acquires map information for a predetermined area using the functions of the map information acquisition unit 21a (step S100). That is, the control unit 20 refers to the map information 30a stored in the storage medium 30 and acquires information on all nodes and links. Figure 3A is a schematic diagram showing the predetermined area. In Figure 3A, the area containing all nodes and links is schematically shown as the predetermined area Z.

[0035] Next, the control unit 20 divides the region by boundary lines using the function of the division unit 21b (step S105). Specifically, for each region that is not set as a cell, the control unit 20 selects links that constitute the boundary line dividing the region so that the areas of the two regions obtained by dividing the region are as equal as possible. In Figure 3A, a boundary line Lb1 dividing a predetermined region Z is shown as an example, and the regions Z1 and Z2 obtained by the division by this boundary line are shown as examples. Note that nodes on the boundary line are shown as black circles and links as straight lines, but cells and nodes within the region are not shown.

[0036] Next, the control unit 20 counts the number of nodes in the divided region using the function of the division unit 21b (step S110). That is, the control unit 20 refers to the map information 30a, identifies the nodes that exist inside the divided region, and determines their number. In the example shown in Figure 3A, the control unit 20 counts the number of nodes in regions Z1 and Z2.

[0037] Next, the control unit 20, using the function of the division unit 21b, sets areas where the number of nodes is below a threshold as cells (step S115). That is, if there are areas where the number of nodes counted in step S110 is below a preset threshold, the control unit 20 associates the cell threshold information with those areas and stores the information indicating the nodes within those cells in the division map information 30b. In the example shown in Figure 3A, it is assumed that the number of nodes in both areas Z1 and Z2 is not below the threshold. The threshold is a value that defines the maximum size of a cell. That is, an area becomes a cell when the number of nodes in the area obtained by division falls below the threshold for the first time. The size of the cell should be set so that even if a path search is performed to all nodes within the cell, it does not take an excessive amount of time, and the threshold is predetermined so that the cell size is such.

[0038] Next, the control unit 20 determines whether or not there are areas that are not cells, based on the function of the division unit 21b (step S120). That is, if there are areas remaining that are not defined as cells among the areas obtained by dividing the predetermined area acquired in step S100, the control unit 20 determines that there are areas that are not cells.

[0039] If it is determined in step S120 that there is a region that is not a cell, the control unit 20 repeats the processing from step S105 onwards. Since the number of nodes in regions Z1 and Z2 shown in Figure 3A is not below the threshold, the processing from step S105 onwards is repeated. Figure 3B shows an example in which region Z1 generated in Figure 3A is divided into regions Z11 and Z12, and region Z2 is divided into regions Z21 and Z22. The control unit 20 repeats this division process.

[0040] In step S120, if it is determined that no non-cell areas exist, the control unit 20 adds boundary line information to the divided map information 30b using the function of the division unit 21b (step S125). That is, the control unit 20 identifies identification information indicating the links and nodes that were designated as boundary lines in step S105, associates this identification information with information indicating that it is a boundary line, and adds it to the divided map information 30b. As a result, the divided map information 30b records information indicating cell identification information and identification information of the nodes contained in the cells. The above cell generation process makes it easy to perform a division process to speed up calculations for obtaining reachable ranges.

[0041] Figure 4 schematically illustrates cells and boundaries. In Figure 4, nodes are shown as black circles, links as straight lines, and cells as dashed lines. Some nodes and links are omitted in Figure 4. Links that exist outside the cells shown by dashed lines do not constitute cells and are considered boundaries.

[0042] (3) Judgment information generation process: Next, the determination information generation process performed by the control unit 20 will be described in detail. Figure 5 is a flowchart of the determination information generation process. The determination information generation process only needs to be performed before the reachability range acquisition process is executed. When the determination information generation process starts, the control unit 20 identifies the cell to be processed using the function of the reachability node acquisition unit 21c (step S200). That is, the determination information generation process is performed by repeating the loop of steps S200 to S240, and in each loop, one of the cells stored in the segmented map information 30b is selected as the target of processing. For this reason, in step S200, cells that are not the target of processing in the loop are extracted and identified as targets for processing.

[0043] Next, the control unit 20 identifies internal nodes located within the cell to be processed using the function of the reachable node acquisition unit 21c (step S205). That is, the control unit 20 refers to the segmented map information 30b, obtains identification information of nodes associated with the cell identified as the target of processing in step S200, and identifies each node as an internal node.

[0044] Next, the control unit 20 identifies external nodes adjacent to the cell to be processed using the function of the reachable node acquisition unit 21c (step S210). Here, an external node adjacent to the cell to be processed refers to a node linked to a node within the cell to be processed, and located outside the cell to be processed. Figure 6 is a schematic diagram showing cell Ce and the nodes inside and outside cell Ce. In Figure 6, external nodes N1 to N7 adjacent to cell Ce are shown as examples. If cell Ce in this example is the cell to be processed, the control unit 20 identifies external nodes N1 to N7 in step S210.

[0045] Next, the control unit 20 identifies the external node to be processed using the function of the reachable node acquisition unit 21c (step S215). That is, the control unit 20 generates determination information corresponding to each external node by repeating the loop of steps S215 to S235. In each loop, one of the external nodes identified in step S210 is selected as the target for processing. Therefore, in step S215, an external node that has not been targeted for processing in the loop processing of steps S215 to S235 is extracted and identified as a target for processing.

[0046] Next, the control unit 20 uses the function of the reachable node acquisition unit 21c to search for the most energy-efficient path from the external node to be processed to each internal node (step S220). That is, the control unit 20 refers to the segmented map information 30b and searches for a path with the external node to be processed as the starting point and each node within the cell Ce to be processed as the destination. The search can be carried out using various known algorithms, such as Dijkstra's algorithm, the A* algorithm, or improved versions thereof, with the energy used as the cost. For example, if the external node to be processed is external node N1, the control unit 20 searches for a path with external node N1 as the starting point and one of the nodes within cell Ce as the destination. The control unit 20 searches for a path from the external node to each internal node to be processed by repeating this process until all nodes within cell Ce are covered. Through the above process, the most energy-efficient path to reach each node within cell Ce from an external node adjacent to cell Ce is found. In Figure 6, a portion of the paths explored with external node N1 as the starting point is shown by dashed arrows.

[0047] Next, the control unit 20 identifies the route requiring the most energy using the function of the reachable node acquisition unit 21c (step S225). That is, the control unit 20 refers to the segmented map information 30b and identifies the energy required to travel along each route obtained in step S220. For example, it is possible to adopt a configuration in which the energy required to travel per unit distance is determined in advance, and the energy required to travel along a route is determined according to the distance of the route. Then, the control unit 20 identifies the route requiring the most energy among the routes identified in step S220. The routes searched in step S220 are routes that can reach each internal node from an external node with the minimum energy. Therefore, in step S225, the route requiring the most energy among the most energy-efficient reachable routes is identified. If the vehicle 100 can reach the node at the end of the route requiring the most energy by following that route, the vehicle 100 will be able to reach all nodes in the cell. This is because the energy required to reach any other node in the cell will be less than or equal to the energy of the most energy-consuming route.

[0048] For example, if the energy of path Rmax shown in Figure 6 is at its maximum, then the energy of any other path is less than or equal to the energy of path Rmax, so vehicle 100 can reach any node in cell Ce via external node N1. Therefore, if vehicle 100 can reach external node N1, and the remaining energy at external node N1 is sufficient to travel the energy of path Rmax, then vehicle 100 can be considered to be able to reach cell Ce (all nodes in cell Ce).

[0049] Therefore, the control unit 20 associates the energy required to travel the route identified in step S225 with the external node to be processed as determination information and stores it in the storage medium 30 as segmented map information 30b (step S230).

[0050] Next, the control unit 20 determines whether processing has been completed for all external nodes using the function of the reachable node acquisition unit 21c (step S235). That is, the control unit 20 processes all external nodes identified in step S210, and if the loop processing from steps S215 to S235 is completed, it determines that processing has been completed for all external nodes. If it is not determined in step S235 that processing has been completed for all external nodes, the control unit 20 repeats the processing from step S215 onward.

[0051] In step S235, if it is determined that processing has been completed for all external nodes, the control unit 20 determines whether processing has been completed for all cells using the function of the reachable node acquisition unit 21c (step S240). That is, the control unit 20 determines that processing has been completed for all cells if it has processed all cells indicated by the segmented map information 30b and the loop processing from steps S200 to S240 has been performed. In step S240, if it is not determined that processing has been completed for all cells, the control unit 20 repeats the processing from step S200 onward.

[0052] In step S240, if it is determined that processing has been completed for all cells, the control unit 20 terminates the determination information generation process. Through the above process, for any vehicle 100 that can reach an external node adjacent to any cell, it is possible to determine whether or not it can reach a cell (all nodes within the cell) simply by using the determination information. Therefore, the computational load on the reachable range can be kept from becoming excessively large.

[0053] (4) Processing to determine reachable range: Next, the reachability range determination process performed by the control unit 20 will be described in detail. Figure 7 is a flowchart of the reachability range determination process. The reachability range determination process is performed when a request for reachability range is sent from vehicle 100 along with the vehicle 100's current position and SOC.

[0054] When the reachability range determination process is initiated, the control unit 20 uses the function of the reachability node acquisition unit 21c to identify reachable nodes by following a path along the boundary line from the current position of the vehicle 100 (step S300). Specifically, the control unit 20 acquires the current position of the vehicle 100 transmitted from the vehicle 100, and if the current position of the vehicle 100 lies on a boundary line defined in the segmented map information 30b, it extends the path along the boundary line by sequentially searching for nodes close to the current position along the links.

[0055] In other words, the control unit 20 searches for other nodes adjacent to the current position, and when other nodes are found, it determines whether the vehicle 100 can reach those other nodes based on the SOC of the vehicle 100 transmitted from the vehicle 100. Whether or not it can reach them is determined based on whether the energy that can be supplied by the SOC at the current position exceeds the energy required to travel the route from the current position along the boundary line to those other nodes. The control unit 20 repeats the above process until it has searched for all reachable nodes along the boundary line after the current position.

[0056] Figure 8 illustrates a similar example to Figure 4, where the current position of vehicle 100 is position Pc, and the nodes on the boundary line that can be reached by extending a path along the boundary line from position Pc are identified. In Figure 8, the links on the boundary line connected to the reachable nodes are shown with thick solid lines. The nodes connected to these thick solid lines are reachable nodes. Furthermore, among these nodes, nodes that cannot be reached to adjacent nodes in the direction of extending the path along the boundary line can be considered to indicate the reachable range. For example, nodes N8 to N14 in Figure 8 can be said to be nodes that indicate the reachable range.

[0057] Next, the control unit 20 identifies the cell to be processed using the function of the reachable node acquisition unit 21c (step S305). Here, the cell to be processed is a cell that includes a node linked to the reachable node identified in step S300. For example, in the example shown in Figure 6, if at least one of the external nodes N1 to N7 is a reachable node, then cell Ce can be processed. There is one or more cells that can be processed, but whether or not a cell is reachable is determined by repeating the loop from steps S305 to S340, and in each loop, one cell selected from the cells that can be processed is made the target of processing. For this reason, in step S305, cells that are not targeted for processing in the loop processing are extracted and identified as targets for processing.

[0058] Next, the control unit 20 uses the function of the reachable node acquisition unit 21c to identify reachable external nodes from among the external nodes adjacent to the cell to be processed (step S310). Specifically, the control unit 20 refers to the segmented map information 30b and identifies nodes that are linked to nodes within the cell to be processed but are located outside the cell to be processed as external nodes. Then, if the external node matches the node identified in step S300, it is identified as a reachable external node. For example, in the example shown in Figure 6, if the vehicle 100 can reach external nodes N1, N2, and N3 by following a path along the boundary line, but cannot reach external nodes N4 to N7, the control unit 20 identifies external nodes N1, N2, and N3 as reachable external nodes.

[0059] Next, the control unit 20 identifies the external nodes to be processed using the function of the reachable node acquisition unit 21c (step S315). The external nodes to be processed here are the external nodes identified in step S310. Each of these external nodes will be processed in the loop from steps S315 to S335. Therefore, in step S315, external nodes that are not being processed in the loop are extracted and identified as targets for processing.

[0060] Next, the control unit 20 acquires determination information associated with the external node to be processed using the function of the reachable node acquisition unit 21c (step S320). That is, the control unit 20 refers to the segmented map information 30b and acquires energy as determination information associated with the external node to be processed. Next, the control unit 20 determines whether or not it is possible to transport the energy indicated by the determination information using the function of the reachable node acquisition unit 21c (step S325). That is, the control unit 20 determines that it is possible to transport the energy indicated by the determination information if the energy that can be supplied by the remaining SOC at the external node to be processed is equal to or greater than the energy indicated by the determination information. (step S325)

[0061] In step S325, if it is determined that the energy indicated by the determination information is not able to travel, the control unit 20 uses the function of the reachable node acquisition unit 21c to determine whether the loop processing has been completed for all external nodes identified in step S310 (step S335). In step S335, if it is determined that the loop processing has not been completed for all external nodes, the control unit 20 repeats the processing from step S315 onward. In step S335, if it is determined that the loop processing has been completed for all external nodes, the control unit 20 does not determine that the target cell is reachable and executes the processing from step S340 onward.

[0062] On the other hand, in step S325, if it is determined that the energy indicated by the determination information is able to travel, the control unit 20 determines that the cell to be processed is reachable using the function of the reachable node acquisition unit 21c (step S330). That is, the control unit 20 associates information indicating that the cell is reachable (all nodes inside are reachable) with the identification number indicating the cell to be processed. In Figure 8, cells Ce1 to Ce4, which have been determined to be reachable, are shown with thick dashed lines.

[0063] If step S330 is executed, or if it is determined in step S335 that the loop processing has been completed for all external nodes, the control unit 20 uses the function of the reachable node acquisition unit 21c to determine whether or not the loop processing has been completed for all cells (step S340). If it is determined in step S340 that the loop processing has not been completed for all cells, the control unit 20 repeats the processing from step S305 onwards.

[0064] On the other hand, if it is determined in step S340 that the loop processing has been completed for all cells, the control unit 20 uses the function of the reachable node acquisition unit 21c to identify reachable nodes within the cells that were not determined to be reachable (step S345). Even if a cell containing nodes linked to reachable nodes identified in step S300 contains cells that are not determined to be reachable (it is not determined that all nodes within the cell can be reached), some nodes within that cell may still be reachable. In Figure 8, cells Ce5 to Ce8 that were not determined to be reachable are shown by a dashed line. Cells near the outer edge of the reachable range Za schematically shown in Figure 8, or cells that include the outer edge, may not be determined to be reachable.

[0065] Therefore, for cells that were not determined to be reachable, the control unit 20 individually determines whether each node within the cell is reachable. To this end, the control unit 20 refers to the segmented map information 30b and searches for a route with an external node adjacent to each cell that is reachable by the vehicle 100 as the starting point, and each node within the cell Ce being processed as the destination. The control unit 20 then identifies the energy required to travel along the searched route. Furthermore, the control unit 20 determines that each node is reachable if the identified energy is less than the energy that can be supplied by the vehicle 100's SOC at the external node. This process determines whether each node within the cell is reachable. In Figure 8, nodes that were determined to be reachable by the process in step S345 are shown as white circles, and the route to those nodes is shown as a dashed line.

[0066] Through the above processing, the nodes identified in step S300, the nodes within the cells identified in step S330, and the nodes identified in step S345 can be considered as reachable nodes. The control unit 20 identifies the reachable range using the function of the guidance control unit 21d and displays it on the display unit (step S350). That is, the control unit 20 considers the outermost nodes among the nodes determined to be reachable (in the example shown in Figure 8, nodes N8 to N14, nodes N15 to N18 located within cells Ce1 and Ce4, and the nodes indicated by white circles located within cells Ce5 to Ce8) to represent the reachable range.

[0067] Therefore, the control unit 20 transmits identification information and location information for these nodes to the vehicle 100 via the communication unit 40. The navigation system 200 of the vehicle 100 acquires this information via the communication unit 600. The navigation system 200 then controls the display unit of the user interface unit 240 to display information indicating the reachable range.

[0068] (5) Other embodiments: The above embodiments are merely examples for carrying out the present invention, and various other embodiments can be adopted. For example, the reachable range guidance system 10 that constitutes the above-described embodiment may be composed of multiple systems. In this case, some functions of the reachable range guidance system 10 may be implemented in the ECU or other terminals within the vehicle 100, or on a server such as a cloud server.

[0069] Furthermore, some of the devices shown in Figure 1 may be shared, or they may be distributed among other devices. For example, the reachable range guidance system 10 and the navigation system 200 may be integrated into a single system. Furthermore, the reachable range guidance system 10 may be a portable terminal or the like. In addition, at least some of the components of the reachable range guidance system 10 (map information acquisition unit 21a, division unit 21b, reachable node acquisition unit 21c, guidance control unit 21d) may be divided among multiple devices. Also, configurations in which some of the components of the above-described embodiment are omitted, or configurations in which the order of processing is changed or omitted, can also be envisioned.

[0070] The map information acquisition unit only needs to be able to acquire map information that shows a road network represented by links and nodes that are the endpoints of those links. In other words, the map information acquisition unit only needs to be able to acquire map information that shows the road network of existing roads using links and nodes. The road network only needs to be represented by links and nodes. Links correspond to road sections, and nodes correspond to intersections, but nodes may also be set at points that are not intersections (for example, tunnel entrances and exits, points where road types change, etc.).

[0071] The division unit only needs to be able to divide a predetermined area containing multiple nodes into multiple cells, each cell being a region bounded by a continuous link. In other words, the division unit only needs to be able to transform the road network into a simpler network in order to enable the exploration of reachable areas based on the cells.

[0072] The designated area can be any area containing multiple nodes and including the vehicle's reachable range. The designated area may change dynamically according to the vehicle's current position, or it may be a fixed area. An example of the former is an area centered on the vehicle's current position with a predetermined radius, where the predetermined distance is set in advance so that the vehicle's drivable range is included. An example of the latter is an area that includes all road networks belonging to the same country or region, or an area that includes all road networks in the region where the vehicle is located.

[0073] A boundary line is composed of continuous links and only needs to constitute the boundary of a cell. In other words, a cell is formed by dividing an area with a boundary line. Of course, this division by the boundary line can be performed repeatedly, and as the division is repeated, the total distance of the boundary line increases.

[0074] A cell is defined as any area within its boundaries and can contain multiple nodes. In other words, any node located within the area enclosed by the boundaries is considered a node in a cell. Whether or not a node in a cell is reachable can be determined based on the provided criteria; it is not necessary to individually determine the reachability of every node within the cell. Therefore, this configuration allows for faster determination of the reachability range compared to a configuration that individually determines the reachability of every node within a cell.

[0075] The reachable node acquisition unit only needs to be able to acquire, as reachable nodes, nodes that can be reached by following links on the boundary line from the current position using the vehicle's remaining energy, and nodes within cells that can be reached by following links on the boundary line. Nodes reachable by following links on the boundary line are nodes that lie on a path formed by links on the boundary line from the vehicle's current position and are reachable with the remaining energy. This path may be explored using various methods other than the method of sequentially extending the path from the starting point as in the embodiment described above. For example, various search algorithms such as Dijkstra's algorithm may be used.

[0076] The guidance control unit only needs to be able to guide the vehicle to the reachable range indicated by the reachable node. In other words, the guidance control unit only needs to be able to guide the vehicle to the range that it can reach with its remaining energy. The mode of guidance is not limited and may be performed in various ways. The timing of the guidance is also not limited and may be before departure or during travel. During travel, the reachable range may be updated according to the change in remaining energy during the travel process. Furthermore, the direction in which the reachable range is guided may be limited according to the direction of travel.

[0077] The remaining energy of a vehicle can be any energy used to propel the vehicle, and is not limited to the electricity stored in the battery as in the embodiments described above. For example, in a vehicle that uses various fuels to power the engine, the remaining fuel corresponds to the remaining energy. Of course, it may be possible to use multiple types of energy. Also, the remaining energy may increase during driving through regeneration.

[0078] Furthermore, the configuration for determining whether a cell is reachable is not limited to the configuration described above. Specifically, in the above embodiment, the most energy-efficient route (the route using the least energy) from an external node adjacent to the cell to each node within the cell was searched for, and if it was possible to travel along the route that required the most energy among all the energy-efficient routes, the cell was considered reachable. However, when searching for a route from an external node to each node within the cell, various cost-based searches may be performed.

[0079] Specifically, costs other than energy consumption include, for example, costs that increase with increasing travel time, costs that increase with increasing distance, and costs that increase with increasing number or distance of toll roads. The route that minimizes energy consumption to reach a particular node may differ from the route that minimizes other costs. Therefore, a configuration may be adopted in which the optimal route to each node is determined based on costs other than energy consumption, and whether or not a vehicle can travel that route is determined based on energy consumption.

[0080] Such a configuration can be realized in the configuration shown in Figure 1 above by having the reachable node acquisition unit 21c perform the following processing. In this configuration, the control unit 20 performs a determination information generation process based on the functions of the reachable node acquisition unit 21c and generates determination information based on costs other than energy consumption.

[0081] Specifically, in step S220, the control unit 20 searches for the path from the external node to be processed to each internal node that minimizes cost, based on costs other than energy consumption (e.g., time cost). Then, in step S225, the control unit 20 identifies the path requiring the most energy among the paths searched in step S220 as the maximum energy path. Then, in step S230, the control unit 20 stores the energy required to travel along the identified path as determination information, associating it with the external node to be processed. The processing from step S235 onward is the same as in the first embodiment.

[0082] According to the above process, the energy of the path that requires the most energy to travel among the paths from an external node to each node within the cell that minimize cost becomes the determination information. Therefore, if the remaining energy at the external node is greater than the energy indicated by the determination information at that external node, it can be determined that all nodes within the cell can be reached via the path with the lowest cost.

[0083] However, if there are multiple external nodes connected to a node within a cell, even if a node within the cell can be reached from one external node via the least cost route, it may be possible to reach it from other external nodes via an even less cost route. Therefore, the control unit 20 considers that a node within a cell can be reached via the least cost route from all external nodes adjacent to the cell if the remaining energy at each node is greater than the energy indicated by the determination information (i.e., it is possible to travel along the maximum energy route determined for each node using the remaining energy at each node).

[0084] Such processing can be exemplified by a configuration in which, in step S325 of the reachability range identification process shown in Figure 7, if it is determined that the energy indicated by the determination information can be transported, the control unit 20 turns on the flag corresponding to the cell to be processed and proceeds with the processing from step S335 onward. Then, in step S335, if it is determined that processing has been completed for all external nodes, the control unit 20 executes step S330 if the flag is on for all external nodes. The control unit 20 also skips step S330 if the flag is off for at least one external node. With the above configuration, it becomes possible to determine whether it is possible to reach the cell via a route that minimizes costs other than energy consumption.

[0085] Furthermore, the present invention is also applicable as a program or method. Moreover, such systems, programs, and methods may be implemented as standalone devices or by utilizing components shared with various devices, encompassing a variety of embodiments. They can also be modified as appropriate, such as being partly software and partly hardware. Furthermore, the invention also functions as a storage medium for a program that controls a device. Of course, the storage medium for the software may be a magnetic storage medium, a semiconductor memory, or any storage medium developed in the future can be considered in exactly the same way. [Explanation of Symbols]

[0086] 10... Reachable Range Guidance System, 20... Control Unit, 21... Reachable Range Guidance Program, 21a... Map Information Acquisition Unit, 21b... Division Unit, 21c... Reachable Node Acquisition Unit, 21d... Guidance Control Unit, 30... Storage Medium, 30a... Map Information, 30b... Division Map Information, 40... Communication Unit, 100... Vehicle, 200... Navigation System, 210... GNSS Receiver, 220... Vehicle Speed ​​Sensor, 230... Gyro Sensor, 240... User I / F Unit, 300... Drive Control ECU, 400... Motor, 500... Battery, 600... Communication Unit

Claims

1. A map information acquisition unit acquires map information representing a road network expressed by links and nodes which are the endpoints of those links. A division unit that divides a predetermined region containing multiple nodes into multiple cells, each cell being a region with a continuous link as its boundary, An reachable node acquisition unit that uses the vehicle's remaining energy to acquire as reachable nodes the nodes that can be reached by following the links on the boundary line from the current position, and the nodes within the cell that can be reached by following the links on the boundary line, A guide control unit that causes the guide unit to guide the reachable range indicated by the reachable node, A reachable range guidance system equipped with the following features.

2. The aforementioned divided portion is The cell is generated by repeatedly dividing it until the number of nodes present in the cell falls below a threshold. The reachable range guidance system according to claim 1.

3. The aforementioned reachable node acquisition unit, Among the paths that can reach the node in the cell from the node on the boundary line with the minimum energy, the path that requires the most energy to travel is determined as the maximum energy path, and if it is possible to travel along the maximum energy path from at least one of the nodes adjacent to the cell using the remaining energy at that node, The node within the cell is considered to be reachable. The reachable range guidance system according to claim 1 or claim 2.

4. The aforementioned reachable node acquisition unit, Among the paths that can reach the nodes within the cell from the node on the boundary line at the lowest cost, the path that requires the most energy to travel is determined as the maximum energy path, and if it is possible to travel along the maximum energy path determined for each node from all the nodes adjacent to the cell using the remaining energy at each node, The node within the cell is considered to be reachable. The reachable range guidance system according to claim 1 or claim 2.

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