JP2017219415A - Route guidance method and route guidance system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a route guidance method that enables speed-up of a route search from a start point to a destination on a road map.SOLUTION: A route guidance method, for use in guiding a route from a start point to a destination on a road map, includes a route guidance apparatus performing the steps of: searching plural cells for a mesh route that consists of cells connecting a cell belonging to the start point to a cell belonging to the destination, on the basis of a passing easiness that depends on a traffic capacity within plural cells produced by partitioning the road map (S41, S42); and searching road links within the retrieved mesh for a route that consists of a road link connecting the start point to the destination (S43, S44).SELECTED DRAWING: Figure 12

Description

  The present invention relates to a route guidance method and a route guidance system.

  Conventionally, there has been proposed a vehicle route guidance device that searches for an optimum route from a departure place to a destination so as to avoid traffic jams and congestion (see Patent Document 1). The vehicle route guidance apparatus described in Patent Literature 1 calculates the ratio of the number of traffic jam occurrence links to the total number of links for which traffic information is provided for each area obtained by dividing the road map into a mesh shape, and according to the calculated ratio To correct the link cost of roads not covered by traffic information in the area. After that, the route from the starting point to the destination is searched for the minimum cost.

Japanese Patent Laid-Open No. 10-38597

  However, in the vehicle route guidance device described in Patent Document 1, since the route search performed after correcting the link cost of the non-target road is performed on the road link on the road map, the search requires a certain time. There is.

  In view of the above problems, an object of the present invention is to provide a route guidance method and a route guidance system that can speed up the route search from a departure point to a destination on a road map.

  According to one aspect of the present invention, when guiding a route from a departure point to a destination on a road map, the route map is based on ease of passage depending on traffic capacity in a plurality of cells divided into meshes. Thus, for a plurality of cells, a mesh route composed of cells connecting from the cell to which the departure point belongs to the cell to which the destination belongs is searched. Then, a route guidance method and a route guidance system are provided that search for a route constituted by a road link connecting from a departure place to a destination for a road link in the searched mesh route.

  ADVANTAGE OF THE INVENTION According to this invention, the route guidance method and route guidance system which can aim at speeding-up of the route search from the departure place on the road map to the destination can be provided.

It is a block diagram which shows an example of the route guidance system which concerns on embodiment of this invention. It is the schematic which shows an example which divided the road link map which concerns on embodiment of this invention by the some cell. It is the schematic which shows an example of the mesh map which concerns on embodiment of this invention. It is the schematic which shows an example of the change process of the passage cost which concerns on embodiment of this invention. It is the schematic which shows an example of the change process of the passage cost which concerns on embodiment of this invention. It is the schematic which shows an example of the change process of the passage cost which concerns on embodiment of this invention. 7A to 7D are schematic diagrams sequentially illustrating an example of route search processing according to the embodiment of the present invention. 8A and 8B are schematic views respectively showing examples of route guidance screens according to the embodiment of the present invention. It is a flowchart which shows an example of the route guidance method which concerns on embodiment of this invention. It is a flowchart which shows an example of the mesh map creation process which concerns on embodiment of this invention. It is a flowchart which shows an example of the change process of the passage cost according to the congestion degree to the cell which concerns on embodiment of this invention. It is a flowchart which shows an example of the search process of the mesh route | root which concerns on embodiment of this invention. FIG. 13A is a graph showing the relationship between the number of road links per cell boundary distance and the coefficient according to the first modification, and FIG. 13B shows the road link density and coefficient in the cell according to the second modification. FIG. 13C is a graph showing the relationship between the magnitude of the spatial deviation of the congestion degree in the cell and the coefficient of the deviation of the congestion degree according to the third modification. FIG. 14A and FIG. 14B are schematic diagrams illustrating examples of mesh maps having different mesh sizes according to a fourth modification. It is the schematic which shows an example of the mesh map which concerns on a 5th modification. 16A to 16D are schematic diagrams sequentially illustrating an example of a mesh route search process according to the sixth modification.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following description of the drawings, the same or similar parts are affixed with the same or similar reference numerals. However, it should be noted that the drawings are schematic, and the relationship between the thickness and the planar dimensions, the ratio of the thickness, and the like are different from the actual ones. Moreover, it is a matter of course that portions having different dimensional relationships and ratios are included between the drawings. Further, the following embodiments exemplify apparatuses and methods for embodying the technical idea of the present invention, and the technical idea of the present invention is the material, shape, structure, and arrangement of components. Etc. are not specified as follows. The technical idea of the present invention can be variously modified within the technical scope defined by the claims described in the claims.

<Configuration of route guidance system>
As shown in FIG. 1, the route guidance system according to the embodiment of the present invention includes a traffic management center 1, a traffic information collection device 2, and vehicles V1, V2, V3,..., Vn (n is a positive integer of 4 or more. There is.) In addition, the number of vehicles V1-Vn is not specifically limited. The traffic information collection device 2 is a vehicle detector installed on a road, for example, and collects road traffic information such as the number of vehicles passing the road per unit time. The traffic information collection device 2 transmits the collected road traffic information to the traffic management center 1 and the vehicles V1 to Vn.

  The vehicle V1 includes a vehicle-side communication device 10, an in-vehicle device 11, a map information storage device 12, and a display device 13. The vehicle-side communication device 10, the in-vehicle device 11, the map information storage device 12, and the display device 13 can be configured by, for example, a navigation device. The vehicle-side communication device 10 receives road traffic information from the traffic information collection device 2 and transmits / receives various information to / from the traffic management center 1. The map information storage device 12 is a memory such as a semiconductor storage device, a magnetic storage device, or an optical storage device, and stores road map information.

  The in-vehicle device 11 can be configured by a microcomputer including a central processing unit (CPU), a storage device (register, cache memory, main storage device), or the like, a processor equivalent to the microcomputer, or the like. The in-vehicle device 11 includes a destination setting unit 21, a vehicle information acquisition unit 22, and a display control unit 23. The destination setting unit 21 sets the destination of the vehicle V <b> 1 on the road map stored in the map information storage device 12 based on passenger input information and the like. The input information of the occupant is input via a user interface such as a touch panel of the display device 13 or a switch in the vehicle interior. Information on the destination set by the destination setting unit 21 is transmitted to the traffic management center 1 via the vehicle-side communication device 10.

  The vehicle information acquisition unit 22 acquires vehicle information including the current position of the vehicle V1 and the traveling state of the vehicle V1. The current position of the vehicle V1 can be acquired from, for example, the global positioning system (GPS). The traveling state of the vehicle V1 is, for example, a vehicle speed, and can be detected by a vehicle speed sensor attached to the vehicle V1. The vehicle information acquired by the vehicle information acquisition unit 22 is transmitted to the traffic management center 1 via the vehicle side communication device 10. The vehicle information acquisition unit 22 sets a departure place at a position different from the current location of the vehicle V1 on the road map stored in the map information storage device 12 based on the input information of the occupant and the set departure point. The ground may be included in the vehicle information.

  Based on the route guidance information received from the traffic management center 1 via the vehicle-side communication device 10, the display control unit 23 displays a recommended route from the departure point to the destination such as the current position of the vehicle V1. The display device 13 is controlled. For example, an output device such as a display can be used as the display device 13. Instead of the display device 13, a recommended route or the like may be presented to the occupant by voice using a voice output device (not shown). The other vehicles V2 to Vn also have the same configuration as the vehicle V1.

  The traffic management center 1 includes a center side communication device 30, a route guidance device 31, a map information storage device 32, and a mesh map creation device 34. The traffic management center 1 may not have the mesh map creation device 34. The center side communication device 30 receives road traffic information from the traffic information collection device 2 and transmits / receives various information to / from the vehicles V1 to Vn.

  The map information storage device 32 is a memory such as a semiconductor storage device, a magnetic storage device, or an optical storage device, and includes a road link map storage unit 51 and a mesh map storage unit 52. The road link map storage unit 51 stores a road link map indicating a connection relationship of road links on the road map. A road link is a road section obtained by dividing a road map between nodes such as intersections. The road link map includes attribute information such as position coordinates on the road map, road standard, link length, lane width, number of lanes, and construction status for each road link.

  The mesh map storage unit 52 stores a mesh map that divides the road link map into a plurality of cells in a mesh shape and manages the road link map in mesh units (cell units). Although the mesh map is illustrated as being stored in advance in the mesh map storage unit 52, the mesh map creation device 34 can also create it when searching for a route.

FIG. 2 shows a plurality of cells A _ij (i = 1 to n; j = 1) managed by the mesh map stored in the mesh map storage unit 52, in which the road link map stored in the road link map storage unit 51 is managed. ~ M: n and m are positive integers greater than or equal to 2. In Fig. 2 to Fig. 6, n = m = 4 is illustrated as an example. The mesh map describes a connection relationship between a plurality of road links R0 constituting a road link map and a plurality of cells _Aij .

FIG. 3 schematically shows the basic configuration of the mesh map. At the center of each cell A _ij managed by the mesh map, a mesh node N _ij (i = 1 to n; j = 1 to m: n, m, which is indicated by a white circle) is a positive integer of 2 or more. 4 and 6 illustrate the case of n = m = 4.) Is set. The mesh nodes N _ij are connected by mesh links L indicated by line segments.

The mesh link L represents a road link connection relationship between adjacent cells _Aij . When there is a road link straddling between adjacent cells _Aij , it is defined that there is a territorial connection relationship, and the mesh link L is set. On the other hand, when there is no road link straddling between adjacent cells _Aij , it is defined that there is no connection relationship between the cells _Aij , and the mesh link L is not set. The mesh link L shown in FIG. 3 corresponds to the road link R0 constituting the road link map shown in FIG. For example, since the cell A ₁₁ shown in FIG. 2 does not have the road link R0 straddling the adjacent cells A ₁₂ and A ₂₁ , the mesh node N ₁₁ and the adjacent mesh node N ₁₂ as shown in FIG. , N ₂₁ , the mesh link L is not set.

Further, the mesh link L is given a passing cost between adjacent cells A _ij (hereinafter referred to as “inter-cell cost”). The inter-cell cost is a numerical value of the degree of ease of passage depending on the traffic capacity between adjacent cells A _ij . Pass easily depend on traffic capacity between cells A _ij is an index representing the passing ease of vehicle when moving between cells A _ij, the number of lanes of the road link to cross the inter-cell A _ij, lane width It can be defined in consideration of the above. This means that the higher the ease of passage between cells A _ij, the easier it is to pass between cells A _{ij, and the} inter-cell cost is set smaller. Conversely, the lower the pass ease of inter-cell A _ij, which would be difficult to pass through the inter-cell A _ij, intercell cost is greater. For example, the greater the total value of the traffic capacity of road links between adjacent cells _{Aij, the} higher the ease of passage between cells _Aij , and the lower the intercell cost. In addition, the traffic capacity of a road link can be calculated | required based on the geometric shape of a road link, a road attribute, etc.

In FIG. 3, the thickness of the mesh link L is changed in accordance with the inter-cell cost so that it can be easily understood intuitively. That is, the thicker the mesh link L, the smaller the inter-cell cost assigned to the mesh link L. For example, since there are a relatively large number of three road links R0 between the cell A ₃₁ shown in FIG. 2 and the cell A ₃₂ adjacent to the right side thereof, between the mesh nodes N ₃₁ and N ₃₂ shown in FIG. The mesh link L is set relatively thick. On the other hand, the cell A ₁₄ shown in FIG. 2 and the cells A ₁₃ , A ₂₄ adjacent to the left side and the lower side thereof have relatively few road links R0, so the mesh node shown in FIG. The mesh links L between N ₁₃ and N ₁₄ and between the mesh nodes N ₁₄ and N ₂₄ are set relatively thin.

Further, the mesh node N _ij indicates a connection relationship of road links belonging to the cell A _ij . FIG. 3 illustrates the case where the mesh node N _ij is set to all the cells A _ij , but when there is a road link belonging to the cell A _ij , it is defined that there is a connection relationship and the cell A mesh node N _ij is set to A _ij . On the other hand, when there is no road link belonging to the cell A _ij , it is defined that there is no connection relationship, and no mesh node N _ij is set in the cell A _ij . The mesh node N _ij shown in FIG. 4 corresponds to the road link R0 constituting the road link map shown in FIG. For example, since there is no road link R0 belonging to cell A ₁₁ shown in FIG. 2, the mesh node is not set in the cell A ₁₁ as shown in FIG.

The mesh node N _ij is given a passing cost in the cell A _ij (hereinafter referred to as “in-cell cost”). The in-cell cost is obtained by quantifying the degree of ease of passage depending on the traffic capacity in the cell A _ij . Pass easily depend on traffic capacity in the cell A _ij is an index representing the street ease of vehicle in the cell A _ij, the frequency of congestion in the cell A _ij, the number of lanes, lane width, construction status, etc. It can be defined in consideration. The higher the ease of passing through the cell A _ij , the easier it is to pass through the cell A _ij , and the in-cell cost is set smaller. Conversely, the lower the pass ease in the cell A _ij, which would be difficult to pass through the cell A _ij, cell cost is greater. For example, the larger the total value of the traffic capacity of the road link in the cell A _ij, defined high pass ease in the cell A _ij, the cell cost is smaller.

In FIG. 4, the size of the mesh node N _ij is changed according to the intra-cell cost so that it can be easily understood intuitively. That is, the larger the mesh node N _ij, cell cost assigned to the mesh node N _ij is small. For example, since the density of the road links R0 belonging to the cells A ₃₁ and A ₃₂ shown in FIG. 2 is relatively high and the total value of the traffic capacity is relatively large, the mesh nodes N ₃₁ , N ₃₂ is set to be relatively large. On the other hand, the density of the road links R0 belonging to the cells A ₂₄ , A ₃₃ , A ₃₄ , A ₄₃ , A ₄₄ shown in FIG. 2 is relatively low and the total value of the traffic capacity is relatively small. As shown, mesh nodes N ₂₄ , N ₃₃ , N ₃₄ , N ₄₃ , and N ₄₄ are set relatively small.

  The route guidance device 31 shown in FIG. 1 is a controller having a route guidance function. The route guidance device 31 can be constituted by, for example, a microcomputer including a CPU and a storage device (register, cache memory, main storage device), a processor equivalent to the microcomputer, and the like. The route guidance device 31 includes a traffic demand prediction unit 41, a traffic volume prediction unit 42, and a route search unit 43. The traffic demand prediction unit 41 predicts traffic demand generated in a predetermined area in a predetermined time zone at present and in the future based on road traffic information received from the traffic information collection device 2 via the center side communication device 30. To do. The traffic volume predicting unit 42 determines the traffic demand predicted by the traffic demand predicting unit 41, the departure place, the destination, the traveling state of the vehicles V1 to Vn received from the vehicles V1 to Vn via the center side communication device 30. Based on this, the traffic volume of each road link in the present and future predetermined time zones is predicted.

  Further, the traffic volume prediction unit 42 calculates (predicts) the degree of congestion of each road link based on the predicted traffic volume of each road link. The congestion level is an index indicating the degree of congestion or congestion on the road link. Higher congestion means that the road link is congested or congested. For example, the degree of congestion may be calculated as a ratio of the traffic volume to the traffic capacity of the road link. Or you may substitute the average speed of vehicles on a road link, the number of traffic, etc. as congestion degree. For example, when the ratio of the traffic volume to the traffic capacity of the road link is set as the congestion level, it is determined that the congestion is when the congestion level exceeds a predetermined threshold, and it is determined that the traffic is not congested when the congestion level is equal to or less than the predetermined threshold. Good.

Traffic prediction unit 42 based on the degree of congestion of each road link, each cell A _ij, calculates a representative value of the congestion degree of the road link in the cell A _ij. As the representative value of the degree of congestion, for example, a simple average value of the degree of congestion of the road links in the cell A _ij , a weighted average value weighted by the road link length, or a maximum value can be adopted.

In FIG. 5, the degree of congestion (representative value) for each cell A _ij is indicated by shades of color (hatching) in three stages. The dark cells A ₃₁ and A ₃₂ indicate that the degree of congestion is relatively high. That is, in the cells A ₃₁ and A ₃₂ , traffic congestion or strong congestion occurs, which indicates that the passage is extremely difficult. The light colored cells A ₁₃ and A ₂₂ indicate that the degree of congestion is relatively medium. That is, the cells A ₁₃ and A ₂₂ are moderately congested, indicating that the ease of passing is moderate. The uncolored cells A ₁₁ , A ₁₂ , A ₁₄ , A ₂₁ , A ₂₃ , A ₂₄ , A ₃₃ , A ₃₄ , A ₄₁ , A ₄₂ , A ₄₃ , A ₄₄ have a relatively low degree of congestion. Show. That is, the cells A ₁₁ , A ₁₂ , A ₁₄ , A ₂₁ , A ₂₃ , A ₂₄ , A ₃₃ , A ₃₄ , A ₄₁ , A ₄₂ , A ₄₃ , A ₄₄ are not congested and easily pass through. Indicates that The degree of congestion for each cell A _ij calculated by the traffic volume prediction unit 42 may be transmitted to the vehicles V1 to Vn via the center side communication device 30 as part of the route guidance information.

Traffic prediction unit 42 based on the calculated cell A _ij for each degree of congestion (typical), to modify the cell cost per cell A _ij stored in the mesh map storage unit 52. For example, as shown in FIG. 5, the intra-cell costs of the cells A ₃₁ and A ₃₂ having a relatively high congestion degree are remarkably increased. Accordingly, the mesh nodes N ₃₁ and N ₃₂ shown in FIG. 4 are remarkably reduced as shown in FIG. Further, as shown in FIG. 5, the in-cell costs of the cells A ₁₃ and A ₂₂ having a medium degree of congestion are moderately increased. As a result, the mesh nodes N ₁₃ and N ₂₂ shown in FIG. 4 become medium and small as shown in FIG. Further, as shown in FIG. 5, the cells A ₁₁ , A ₁₂ , A ₁₄ , A ₂₁ , A ₂₃ , A ₂₄ , A ₃₃ , A ₃₄ , A ₄₁ , A ₄₂ , A ₄₃ , without modifying the a ₄₄ cell cost in mesh node mesh node _{N 11, N 12, N 14} , N 21, N 23, N 24, N 33, N 34, N 41, N 42 shown in FIG. 4, The sizes of N ₄₃ and N ₄₄ are maintained as shown in FIG.

The route search unit 43 uses the information on the departure and destination of the vehicles V1 to Vn received from the vehicles V1 to Vn via the center side communication device 30, the mesh map stored in the mesh map storage unit 52, and the like. The route from the departure point to the destination is searched for each of the vehicles V1 to Vn. The route search unit 43 as a target a plurality of cells A _ij, first search unit for searching for a configuration mesh route the cell A _ij connecting from the cell A _ij Field of the departure point to the cell A _ij Field of the destination 44 and a second search unit 45 for searching for a route constituted by road links connecting the departure point to the destination for the road links in the searched mesh route.

For example, as shown in FIG. 7A, the road map has a cell A _ij (i = 1 to n; j = 1 to m: n, where m is a positive integer greater than or equal to 2. In FIGS. 7A to 7D, n = 4. , M = 8 is illustrated as an example). In FIG. 7A, the congestion degree is calculated step by step (in four steps) for each cell A _{ij as} shown by the shades of color (hatching). This is a situation where the congestion degree of the cell A ₂₃ is the highest and a traffic jam occurs. The cells A ₁₂ , A ₁₃ , A ₁₄ , A ₁₅ , A ₂₂ , A ₂₄ , A ₂₅ , A ₃₁ , A ₃₂ , and A ₃₃ around the cell A ₂₃ are second highest in congestion. The cells A ₂₁ , A ₃₄ , A ₃₅ , A ₄₁ , A ₄₄ , A ₄₇ have the third highest congestion. In cells A ₁₁ , A ₁₆ , A ₁₇ , A ₁₈ , A ₂₆ , A ₂₇ , A ₃₆ , A ₃₇ , A ₃₈ , A ₄₂ , A ₄₃ , A ₄₅ , A ₄₆ , A ₄₈ , the degree of congestion is the lowest. This is a situation where there is no occurrence. It is assumed that the intra-cell cost of each cell A _ij is corrected by the traffic volume predicting unit 42 using this congestion degree.

The first search unit 44 reads out the mesh map stored in the mesh map storage unit 52, and uses a path search algorithm such as Dijkstra method based on the inter-cell cost and the intra-cell cost of each cell A _ij . as shown in FIG. 7B, the cell _{a 31,} a ₄₁ connecting from the cell _{a 31} Field of departure O until cell _{a 17} which belongs destination _{D, a 42, a 43,} a 44, a 45, a 46, a A mesh route R1 composed of ₃₆ , A ₃₇ , A ₂₇ , and A ₁₇ is searched. Specifically, among the arbitrary mesh routes that connect the cell A ₃₁ to which the departure place O belongs to the cell A ₁₇ to which the destination D belongs, the mesh route that minimizes the sum of the inter-cell cost and the intra-cell cost is selected. The That is, the mesh route R1 shown in FIG. 7B, the cell _A 31 constituting the mesh route _{R1, A 41, A 42,} A 43, A 44, A 45, A 46, A 36, A 37, A 27, A ₁₇ between the inter-cell costs and between the cells A ₃₁ and A ₄₁ adjacent in the mesh route R1, between the cells A ₄₁ and A ₄₂ , between the cells A ₄₂ and A ₄₃ , and between the cells A ₄₃ and A ₄₄ . Between cells A ₄₄ and A ₄₅ , between cells A ₄₅ and A ₄₆ , between cells A ₄₆ and A ₃₆ , between cells A ₃₆ and A ₃₇ , between cells A ₃₇ and A ₂₇ , and between cell A ₂₇ , A ₁₇ are selected because the total value of the inter-cell costs between them is the smallest.

  In addition, with reference to FIG. 7A and FIG. 7B, although the case where the mesh route R1 is searched using the intra-cell cost corrected in consideration of the congestion degree is illustrated, the first search unit 44 determines the congestion degree. It is also possible to search for the mesh route R1 using the in-cell cost before correction that is not taken into consideration.

In addition, there is a case where the mesh route R1 cannot always be searched so as to avoid a congested place due to the density of road links (for example, when a departure place, a congested place, and a destination line up on a main road on a single road). is assumed. In this regard, even if the in-cell cost of the cell A _{ij at} the congested location is greatly modified according to the degree of congestion, if only the mesh route R1 can be obtained, the first search unit 44 is expensive. Even if it exists, the mesh route R1 is searched. Therefore, there is no inconvenience that the mesh route R1 cannot be searched.

  As shown in FIG. 7C, the second search unit 45 extracts a road link R0 belonging to the mesh route R1 searched by the first search unit 44. As shown in FIG. 7D, the second search unit 45 is composed of a road link R0 that connects the starting point O to the destination D using a route search algorithm such as Dijkstra method for the extracted road link R0. The route (link route) R2 to be searched is searched. Information on the link route R2 searched by the second search unit 45 is transmitted to the vehicles V1 to Vn as route guidance information.

In the vehicle V1 illustrated in FIG. 1, the display control unit 23 displays the display screen of the display device 13 as illustrated in FIG. 8A based on the route guidance information received from the traffic management center 1 via the vehicle-side communication device 10. Then, a road map _{divided in} units of cell A _ij is displayed. In FIG. 8A, the current location O and road links around the current location O are displayed, for example, as in a normal navigation device. Further, the display control unit 23 displays the degree of congestion for each cell A _ij on the display screen of the display device 13 by color coding, shading, or the like.

Here, in a normal navigation device, information on traffic jams / congested areas is displayed by color coding etc. for each road link, so the position of the traffic jam / congested areas is clear, but the degree of congestion around the traffic jams / congested areas is Difficult to grasp. On the other hand, according to the embodiment of the present invention, by indicating the degree of congestion in units of cell A _ij by color coding, shading, etc., it becomes easier for the occupant to recognize a wide range of congestion distribution in units of cell A _ij. This makes it easier to recall the outline of the course.

Furthermore, when the link route R2 of FIG. 7D is searched, as shown in FIG. 8B, the display device 13 displays the link route R2 from the current location O to the destination D as a recommended route. As shown in FIG. 8B, the congestion degree for each cell A _ij is also displayed in a superimposed manner, so that it is intuitive for the occupant that the link route R2 has been searched avoiding the cell A _ij having a high congestion degree. Can understand. Therefore, it is possible to improve the satisfaction and acceptability of the occupant's recommended route. Furthermore, the time such as traffic congestion, congestion does not occur, the display device 13, by displaying the cell cost instead of congestion for each cell A _ij, roads distribution for each cell A _ij on the driver You can also intuitively understand the situation.

<Route guidance method>
Next, an example of the route guidance method according to the embodiment of the present invention will be described with reference to the flowchart of FIG.

  In step S <b> 10, the traffic demand prediction unit 41 acquires the current traffic demand in a predetermined area from the road traffic information and the like collected by the traffic information collection device 2. In step S <b> 11, the traffic demand prediction unit 41 predicts future traffic demand in a predetermined area based on road traffic information and the like collected by the traffic information collection device 2.

In step S12, the traffic volume predicting unit 42 determines whether the traffic congestion / congested location and the traffic jam / Identify the time of congestion. In step S13, the traffic amount predicting unit 42, among a plurality of cells A _ij mesh map stored in the mesh map storage unit 52, modify the cell cost of the cell A _ij with a specific traffic jam, congestion point To do.

  The subsequent steps S14 to S16 are performed one by one for all the vehicles V1 to Vn to be managed by the traffic management center 1. In step S <b> 14, for example, with the vehicle V <b> 1 as a processing target, the route search unit 43 acquires the position information and the like of the departure point and the destination of the vehicle V <b> 1 received via the center side communication device 30.

  In step S15, the route search unit 43 uses the mesh map stored in the mesh map storage unit 52 based on the position information of the starting point and the destination of the vehicle V1 to avoid congestion and congestion. Search for the route from the starting point to the destination. The route search is performed in the same manner even when there is no traffic jam or congestion in the target area.

  In step S <b> 16, route guidance information including the route information searched by the route search unit 43 is transmitted to the vehicle V <b> 1 via the center side communication device 30. On the vehicle V1 side, a recommended route or the like is displayed on the road map on the display screen of the display device 13 based on the route guidance information.

  In step S17, it is determined whether or not the processing of steps S14 to S16 has been performed on all the vehicles V1 to Vn to be managed. A process is completed when it determines with having performed with respect to all the vehicles V1-Vn. On the other hand, when it determines with not having performed with respect to all the vehicles V1-Vn, the process of step S14-S16 is repeated about the remaining vehicles.

  Next, an example of a method for creating a mesh map stored in the mesh map storage unit 52 shown in FIG. 1 will be described with reference to the flowchart of FIG.

In step S <b> 20, the mesh map creation device 34 uses the road link map stored in the road link map storage unit 51 to spread cells A _ij of a predetermined mesh size on the road link map, and creates a road link map. Partition into a plurality of cells A _ij .

In step S21, the mesh map creation device 34 assigns ID (i, j) to each cell A _ij . Here, a case where a two-dimensional index (i, j) is given assuming a two-dimensional structural cell _Aij is illustrated. Note that since the shape and structure of the cell A _ij are arbitrary, an ID may be assigned in accordance with the form of the cell A _ij .

In step S22, the mesh map creation device 34 extracts road links belonging to each cell _Aij . In step S <b> 23, the mesh map creation device 34 gives information indicating that the extracted road link belongs to the cell A _ij to each road link.

In step S24, the mesh map creation device 34, for the (i, j) -th cell among the plurality of cells A _ij , for the road link in the (i, j) -th cell, the road link length, the road The traffic capacity of the road link in the (i, j) th cell is calculated with reference to attribute information such as the width and the number of lanes. Furthermore, the mesh map creation device 34 calculates the total value of the traffic capacity of each road link.

  In step S25, the mesh map creation device 34 sets the intra-cell cost of the (i, j) th cell based on the calculated total traffic capacity of the road links in the (i, j) th cell. To the mesh node. The mesh map creation device 34 sets the in-cell cost smaller as the total traffic capacity value is larger.

In step S26, the mesh map creation device 34 determines whether or not the processing of steps S25 and S26 has been performed on all cells _Aij . If it is determined that the process has not been performed for all the cells A _ij , the processes in steps S25 and S26 are repeated for the remaining cells. On the other hand, when it determines with having performed with respect to all the cells _Aij in step S26, it transfers to step S27.

  In step S27, the mesh map creation device 34, the (i, j) -th cell, the (i-1, j) -th, (i, j-1) -th adjacent to the (i, j) -th cell, Focusing on four boundaries with the (i, j + 1) th and (i + 1, j) th four cells, road links across the four boundaries are extracted. The mesh map creation device 34 calculates the traffic capacity of each road link by referring to attribute information such as the road standard, road link length, road width, and number of lanes of the extracted road link. Further, the mesh map creation device 34 calculates the total value of the traffic capacity of the road links for each of the four boundaries.

  In step S <b> 28, the mesh map creation device 34 determines between (i, j) th cell and (i−1, j) th cell (i, j) based on the total traffic capacity for each of the four boundaries. , J) th cell and (i, j-1) th cell, (i, j) th cell and (i, j + 1) th cell, (i, j) th cell And the (i + 1, j) -th cell are set, and the inter-cell cost is assigned to the corresponding mesh link L. The mesh map creation device 34 sets the inter-cell cost smaller as the total traffic capacity value is larger.

In step S29, the mesh map creation device 34 determines whether or not the processing in steps S27 and S28 has been performed for all cells _Aij . If it is determined that the process is performed for all cells A _ij , the process is completed. On the other hand, when it is determined that the process has not been performed for all the cells A _ij , the processes in steps S27 and S28 are repeated for the remaining cells. As a result, mesh map containing cell cost and information intercell costs between all the cells A _ij in the entire cell A _ij is generated and stored in the mesh map storage unit 52.

  Next, referring to the flowchart of FIG. 11, the process of specifying the traffic jam / congested part in step S12 of the flowchart of FIG. 9 and the process of changing the intra-cell cost of the cell including the traffic jam / congested part of step S13. An example will be described.

  In step S <b> 31, the traffic volume prediction unit 42 calculates the degree of congestion of each road link based on the traffic volume of each current and future road link predicted by the traffic volume prediction unit 42. As the degree of congestion of each road link, a ratio of the traffic volume to the traffic capacity of the road link may be adopted, and an average speed or the number of passing vehicles of the road link may be substituted.

In step S32, the traffic volume predicting unit 42 calculates a representative value of the congestion degree for each cell A _ij based on the congestion degree of the road link in the cell A _ij calculated in step S31. As a representative value of the degree of congestion, for example, a simple average value, a weighted average value weighted by a road link length, a maximum value, or the like can be adopted.

In step S33, the traffic volume predicting unit 42 multiplies the intra-cell cost _assigned to the mesh node N _ij in step S25 of FIG. 10 by a coefficient corresponding to the representative value of the congestion degree calculated in step S32. , Modify the cost in all cells. Here, it is assumed that the coefficient takes a value of 1 or more. When the degree of congestion is relatively high, the corrected intra-cell cost increases from the value before correction by setting the coefficient relatively large. When the degree of congestion is relatively low, the corrected in-cell cost is set to a value close to the value before correction by setting the coefficient small. When no congestion occurs and the degree of congestion is less than a predetermined threshold, the coefficient is set to 1 and the value of the in-cell cost before correction is maintained.

In step S34, the traffic volume prediction unit 42 determines whether or not the intra-cell cost has been corrected for all the cells _Aij . If it is determined that the intra-cell cost has been corrected for all cells A _ij , the process is completed. On the other hand, when it is determined that the intra-cell cost is not corrected for all the cells A _ij , the processes in steps S31 to S33 are repeated for the remaining cells.

  Next, an example of route search processing for avoiding a traffic jam / congested location in step S15 of the flowchart of FIG. 9 will be described with reference to the flowchart of FIG.

In step S41, the first search unit 44 refers to the mesh map stored in the mesh map storage unit 52 from the position information of the starting point and the destination of the vehicle V1, and as shown in FIG. Among the cells A _ij, the cell A ₃₁ to which the departure place O belongs and the cell A ₁₇ to which the destination D belongs are specified.

In step S42, the first searching unit 44, based on cell cost and intercell costs of a plurality of cells A _ij, using a route search algorithm such as Dijkstra method, as for a plurality of cells A _ij, FIG The mesh route R1 is searched as shown in 7B. Mesh route R1, the cell _A 31 connecting from the cell _{A 31} Field of departure O until cell _{A 17} Field of _{destinations, A 41, A 42, A} 43, A 44, A 45, A 46, A 36, A ₃₇ , A ₂₇ , A ₁₇ .

In step S43, the second search unit 45 extracts the road link R0 belonging to each cell _Aij included in the mesh route R1, as shown in FIG. 7C. In step S44, the second search unit 45 uses the route search algorithm such as Dijkstra method for the road link R0 extracted in step S43, as shown in FIG. A link route R2 constituted by a road link R0 connecting the above is searched.

  The route guidance program according to the embodiment of the present invention can cause a computer such as the route guidance device 31 constituting the route guidance system to execute a series of processes of the route guidance method shown in FIG. The route guidance program according to the embodiment of the present invention can be stored in, for example, a storage device of the route guidance device 31.

As described above, according to the embodiment of the present invention, when performing a route search from the departure point O to the destination D, based on the ease of passage for each of the plurality of cells A _ij into which the road map is _divided , For a plurality of cells _Aij , a mesh route R1 composed of cells connecting from a cell to which the departure point O belongs to a cell to which the destination D belongs is searched. That is, when a certain road link is a traffic jam / congested location, there is a high possibility that the surrounding road link is also a traffic jam / congested location. On the other hand, since the road mesh route R1 is searched for in units of a plurality of cells A _ij before the route search is performed with respect to the road links, the road links that are likely to be congested or congested are _{displayed in} units of a plurality of cells A _ij. Can be avoided at once.

  Then, for the road link in the searched mesh route R1, a route (link route) R2 composed of a road link connecting from the departure point O to the destination D is searched. As a result, it is possible to perform a route search for road links after collectively excluding road links that are likely to be congested or congested outside the mesh route R1. Therefore, as compared with the case where the route search from the departure point O to the destination D is performed from the beginning for the road link, the calculation load for searching for the road link that is likely to be a traffic jam / congested place is reduced. The speed of route search can be increased. This is particularly effective when searching for a route with a high information load using probe information or big data.

In addition to cell-cost multiple cells A _ij, by searching the mesh route R1 based on inter-cell costs of a plurality of cells A _ij, based only on the cell cost of the plurality of cells A _ij mesh Compared to searching for route R1, information used to avoid traffic jams / congested locations increases, so search for routes that are easier to avoid traffic jams / congested traffic locations according to actual traffic jams / congested locations. Can do. Furthermore, depending on the degree of congestion of the road link in the cell A _ij, by modifying the cell costs of a plurality of cells A _ij, that searches for a route in consideration of traffic jam, congestion of the cell A _ij units it can.

(First modification)
In the embodiment of the present invention, when setting the inter-cell cost of the plurality of cells A _ij in steps S27 and S28 of FIG. 10, the total value of the traffic capacity of the road link straddling the boundary between the adjacent cells A _ij is calculated. The case where it calculated and the inter-cell cost was set according to the total value of the calculated traffic capacity was illustrated. On the other hand, in the first modified example, when setting the inter-cell cost, in addition to the traffic capacity of the road link straddling the boundary between adjacent cells, the number of road links straddling the boundary between adjacent cells. The case where is considered is illustrated.

  For example, assuming a 20km square cell, if there is one road link with a large and large traffic capacity in the center of the boundary line between adjacent cells, from the edge of the boundary line between adjacent cells to this road link A maximum distance of 10 km is required. On the other hand, if two road links with half the traffic capacity exist on the boundary line between the cells at a predetermined interval, the distance required to reach these road links is small and easy to pass. It is thought that it improves. However, when there are too many road links and there are many thin road links, the ease of passing may be reduced due to a decrease in vehicle speed or the like. That is, it is considered that the number of road links straddling the boundary between adjacent cells is high if there is a certain number per distance, and the number of road links is reduced if it is too few or too many.

Therefore, in the first modification, as shown in FIG. 13A, a coefficient (factor) corresponding to the number of road links per boundary distance between adjacent cells is set so that this situation is reflected in the inter-cell cost. To do. This coefficient is set to a high value even if the number of road links per cell boundary distance is large or small (that is, the passing cost increases), and the number of road links in the appropriate range passes between them. It shows that it is easy. In the first modified example, the inter-cell cost is corrected by multiplying the coefficient shown in FIG. 13A by the total traffic capacity of the road links. That, C ₁ intercell _cost, f ₁ the coefficients shown in FIG. _13A, the traffic capacity of the road link crossing between adjacent cells as C _L, intercell cost C ₁ can be determined by formula (1) .
C ₁ = f ₁ × ΣC _L (1)

  According to the first modification, it is possible to perform route guidance more in line with the actual situation by evaluating the inter-cell cost based on the traffic capacity of the road links straddling the cells and the number density of the road links.

(Second modification)
In the embodiment of the present invention, when setting the intra-cell cost of the cell A _ij in steps S24 and S25 of FIG. 10, the total traffic capacity of the road links belonging to the cell A _ij is calculated, and the calculated traffic capacity The case where the in-cell cost is set according to the total value of is illustrated. On the other hand, in the second modification, when setting the intra-cell cost, in addition to the traffic capacity of the road links belonging to the cell, the number of road links belonging to the cell is considered.

  For example, assuming a 20km square cell, if there are two wide road links with large traffic capacity in the center of the cell and intersecting in a cross shape, from the center position of each side of the cell to this road link It is necessary to move up to 10km, but if there are four road links with half the traffic capacity, and cross in a square shape with a predetermined interval, these road links will be reached. It can be considered that the distance required for this is small. That is, it is considered that a certain number of road links are more likely to pass through the cell. However, in a situation where thin road links are stretched, it is conceivable that the speed does not increase due to an intersection or the like, and the ease of passing is reduced. Therefore, the road links in the cell are easy to pass if there is a certain area density, but it is difficult to pass if the area density of the road links is too low or too high.

  Therefore, in the second modification, as shown in FIG. 13B, a coefficient corresponding to the road link density (the number of road links per area) in the cell is set to reflect this situation in the in-cell cost. This coefficient is set so as to be a high value (passage cost is increased) regardless of whether the road link density is large or small, and indicates that an appropriate road link density therebetween is easy to pass.

In the second modification, the in-cell cost is corrected by multiplying the total value of the road link traffic capacity by the coefficient shown in FIG. 13B. That is, the intra-cell cost is C ₂ , the coefficient shown in FIG. 13B is f ₂ , the traffic capacity of the road link in the cell is C _L , and the intra-cell cost C ₂ can be obtained by Expression (2).
C ₂ = f ₂ × ΣC _L (2)

  According to the second modified example, by evaluating the intra-cell cost based on the traffic capacity and road link density of the road links in the cell, it is possible to provide route guidance that is more realistic.

(Third Modification)
In the embodiment of the present invention, when the intra-cell cost is corrected in steps S31 to S33 of FIG. 11, the representative value of the congestion degree in the cell A _ij is calculated, and the intra-cell cost is calculated according to the calculated representative value of the congestion degree. The case where cost is corrected was illustrated. On the other hand, in the third modified example, when correcting the intra-cell cost, the case of considering the spatial bias of the congested link in the cell is illustrated.

  When the spatial deviation of the congestion is large, it is likely that the congestion is concentrated at the location where there is congestion, and the other locations in the cell are less crowded and easy to pass. On the other hand, when the spatial bias of the congestion is small, it is conceivable that the congestion spreads in the entire area in the cell and the ease of passage is low in the entire area.

  Therefore, in order to evaluate the spatial bias of the congestion, as shown in FIG. 13C, the intra-cell cost is relatively increased when the bias is relatively small, and the intra-cell cost when the bias is relatively small. The congestion bias coefficient is set so as to be relatively small.

In the third modification, the intra-cell cost is corrected by multiplying the intra-cell cost at the time of non-congestion by the congestion degree coefficient and the congestion bias coefficient shown in FIG. 13C. That is, the cell cost C _3, the cell cost for non-congested C _0, the coefficient of the degree of congestion of f _3, the deviation coefficient of the congestion shown in FIG. 13C as f _4, cell cost C ₃ has the formula It can be obtained in (3).
C ₃ = C ₀ × f ₃ × f ₄ (3)

  According to the third modification, the congestion state of the road links in the cell is evaluated based on the spatial deviation of the congestion in addition to the congestion degree in the cell, so that congestion and congestion can be avoided and reduced more effectively. Such route guidance is possible.

(Fourth modification)
In the embodiment of the present invention, the case where one mesh map is used has been exemplified. However, as the distance from the starting point to the destination increases, the number of cells to be searched for the mesh route increases, and the mesh route Search takes time. In addition, when the distance from the starting point to the destination is as short as the mesh size, both the starting point and the destination belong to one cell, or the starting point and the destination are respectively adjacent cells. It is assumed that the mesh route search does not function properly.

  For example, FIG. 14A and FIG. 14B show two mesh maps having different mesh sizes. The size of the cell A1 in the mesh map shown in FIG. 14A is four times the size of the cell A2 in the mesh map shown in FIG. 14B. As shown in FIG. 14A, when the starting point O and the destination D exist at the lower left and upper right ends of the mesh map, respectively, the mesh map is covered with 4 × 4 cells A1. On the other hand, when the positions of the starting point O and the destination D shown in FIG. 14A are made the same and the cell A2 shown in FIG. 14B is applied, the number of cells A2 to be searched becomes 16 × 16 cells A2. However, it increases 16 times compared to the case of the cell A1 shown in FIG. 14A, and the calculation time increases accordingly.

  In addition, when the distance from the departure point O to the destination D is short as shown in FIG. 14B, when the mesh map having a relatively large mesh size shown in FIG. 14A is applied, the departure is made to two adjacent cells A1. The ground O and the destination D are located respectively, and an appropriate mesh route R1 cannot be searched. Therefore, in the fourth modification, a plurality of mesh maps having different mesh sizes are stored in the mesh map storage unit 52 and selectively used according to the distance from the starting point O to the destination D.

  The route search unit 43 selects the mesh size of the map to be applied according to the distance from the departure point of the vehicle that is the route search target to the destination. The mesh size is a size that divides the distance from the departure point to the destination by several divisions (for example, 4 × 4 divisions as shown in FIG. 14A). This is one measure for searching several mesh routes accordingly. Therefore, it is considered appropriate to apply a mesh map having a mesh size according to the size of dividing the distance from the starting point to the destination by several. However, it is conceivable that the mesh size to be prepared is limited. Therefore, it is preferable to selectively use a mesh map having a size close to the size of dividing the distance from the starting point to the destination among several mesh maps of the prepared mesh size.

  In addition, when the distance from the starting point to the destination is relatively large, if a mesh map of a cell with a relatively coarse mesh is applied among multiple mesh maps, a route that is far away from the congested location when congestion occurs High possibility to explore. In that case, the overall effect of reducing / avoiding congestion and congestion is increased.

  According to the fourth modified example, a plurality of mesh maps having different mesh sizes are prepared, and the plurality of mesh maps are selectively used according to the distance from the starting point to the destination, thereby obtaining the distance. Appropriately sized cells can be used. Furthermore, the closer the distance from the departure point to the destination, the smaller the size of the plurality of cells, thereby ensuring the freedom of route search when the distance from the departure point to the destination is relatively close. be able to. On the other hand, when the distance from the departure place to the destination is relatively long, it is possible to suppress an increase in calculation load due to an excessive number of cells to be searched.

(Fifth modification)
In the embodiment of the present invention, as illustrated in FIG. 2, the case where the road link map is _divided by square cells _Aij having the same size is illustrated. However, since the density of road links varies depending on the region, if only cells A _{ij having the} same size are used in the entire area, a large number of cells A _ij not including road links may be generated. Therefore, in the fifth modification, cells of different sizes are set in one mesh map in order to reduce the number of cells not including road links.

  For example, as shown in FIG. 15, a mesh map having cells A1 to A3 having three sizes is used. In FIG. 15, the size of the cell A1 is the largest, the cell A2 is ¼ the size of the cell A1, and the cell A3 is ¼ the size of the cell A2. The cells A1 to A3 are respectively arranged according to the number density of road links constituting the road map. That is, a relatively large cell A1 is set in an area where the number density of road links is relatively low. A cell A2 having a medium relative size is set in an area having a relatively medium number of road links. A relatively small cell A3 is set in a region where the number density of road links is relatively high.

  According to the fifth modification, cells A1 to A3 having different sizes are set in one mesh map, and cells corresponding to areas where the road link density on the road map is relatively high are The sizes of the cells A <b> 1 to A <b> 3 are made different so as to be smaller than the cell corresponding to the region having a relatively low density. As a result, especially in areas where the density of road links is large, in areas where the density of road links is relatively high, the degree of freedom for searching for mesh routes is secured, while areas where the density of road links is relatively low. It is possible to reduce the calculation load for searching as a target, and to speed up the route search. In the fifth modification, the structure of the cells A1 to A3 is a non-structural system, and thus the description of the IDs and connection relations of the cells A1 to A3 are different from the embodiment of the present invention. A management method corresponding to the structure may be applied.

  Moreover, in the 5th modification, although the case where cell A1-A3 was a square was illustrated, the shape of cell A1-A3 is not specifically limited. For example, a rectangular shape in which a plurality of square cells A1 to A3 are connected may be used. Furthermore, the shape of the cells A1 to A3 is not limited to a rectangle, and may be a triangle, a rectangle, or a hexagon. Furthermore, it may be an irregularly shaped cell along, for example, a municipal boundary. In that case, it is possible to use data of existing regional divisions such as municipal boundaries.

(Sixth Modification)
In the embodiment of the present invention, the search for the mesh route R1 is performed only once, the road link belonging to the cell A _ij in the mesh route R1 is extracted later, and the link route that connects the departure point and the destination from the extracted road link The case where R2 is searched was illustrated. On the other hand, in the sixth modification, a plurality of mesh maps having different sizes are stored in the mesh map storage unit 52, and the mesh route is searched in multiple stages using the plurality of mesh maps sequentially. Illustrate.

  The first search unit 44 is divided by a plurality of cells (primary cells) A1 having a relatively large mesh size among the plurality of mesh maps stored in the mesh map storage unit 52, as shown in FIG. 16A. Extract the mesh map. As shown in FIG. 16B, the first search unit 44 searches for a mesh route (primary mesh route) R11 configured by a cell A1 that connects a cell A1 to which the departure point O belongs to a cell A1 to which the destination D belongs. To do.

  Further, the first search unit 44 extracts a mesh map divided by a plurality of cells (secondary cells) A2 having a relatively small mesh size from the plurality of mesh maps stored in the mesh map storage unit 52. To do. Then, the first search unit 44 extracts a cell A2 having a position coordinate corresponding to the mesh route R11 from among the plurality of cells A2 of the extracted mesh map, as shown in FIG. 16C. Further, the first search unit 44 searches from the cell A2 including the departure point O to the cell A2 including the destination D, as shown in FIG. 16D, based on the inter-cell cost and the intra-cell cost of the extracted cell A2. A mesh route (secondary mesh route) R12 configured by the cell A2 to be connected is searched.

  The second search unit 45 extracts a road link in the mesh route R12 searched by the first search unit 44. The second search unit 45 searches the extracted route link for a link route constituted by a road link connecting from the departure point O to the destination D.

  According to the sixth modified example, after searching for the mesh route R11 configured by the cell A1, the cell A2 is determined based on the ease of passage for each of the plurality of cells A2 in which the mesh route R11 is divided more finely than the cell A1. The mesh route R12 configured by the above is searched. As described above, by searching the mesh routes R11 and R12 in multiple stages while reducing the size of the cells A1 and A2 for the same starting point O and destination D, Highly probable road links can be excluded step by step in units of cells A1 and A2. Therefore, compared to the case where the search for the mesh route is performed only once, it is possible to exclude more road links that are likely to be congested or congested before starting the search for road links. The time required for route search can be further shortened. In the sixth modified example, the case where the mesh routes R11 and R12 are searched in two stages is illustrated, but the mesh route is searched in three or more stages using mesh maps of other different mesh sizes. May be.

(Other embodiments)
As mentioned above, although this invention was described by embodiment and the 1st-6th modification, it should not be understood that the statement and drawing which make a part of this indication limit this invention. From this disclosure, various alternative embodiments, examples and operational techniques will be apparent to those skilled in the art. It goes without saying that the present invention includes various embodiments not described herein. Therefore, the technical scope of the present invention is defined only by the invention specifying matters according to the scope of claims reasonable from the above description.

DESCRIPTION OF SYMBOLS 1 ... Traffic management center 2 ... Traffic information collection apparatus 10 ... Vehicle side communication apparatus 11 ... In-vehicle apparatus 12 ... Map information storage device 13 ... Display apparatus 21 ... Destination setting part 22 ... Vehicle information acquisition part 23 ... Display control part 30 ... Center side communication device 31 ... route guidance device 32 ... map information storage device 33 ... mesh map creation device 41 ... traffic demand prediction unit 42 ... traffic volume prediction unit 43 ... route search unit 44 ... first search unit 45 ... second Search unit 51 ... road link map storage unit 52 ... mesh map storage units V1 to Vn ... all vehicles

Claims (6)

A route guidance method for guiding a route from a departure point to a destination on a road map,
The route guidance device targets the plurality of cells from the cell to which the departure point belongs to the destination based on ease of passage depending on traffic capacity in the plurality of cells obtained by dividing the road map into a mesh shape. Searching for a mesh route composed of the cells connecting to the cell to which
The route guidance device includes a step of searching for a route constituted by the road link connecting the starting point to the destination for a road link in the searched mesh route. Route guidance method.   2. The route guidance method according to claim 1, wherein the step of searching for the mesh route further searches for the mesh route based on ease of passage depending on a traffic capacity between the adjacent cells.   3. The route guidance method according to claim 1, wherein the step of searching for the mesh route sets the size of the plurality of cells to be smaller as the distance from the departure point to the destination is shorter.   The step of searching for the mesh route includes, after searching for the mesh route, based on the ease of passage of each of the plurality of secondary cells obtained by dividing the inside of the primary mesh route into a mesh shape finer than the cell. And searching for a secondary mesh route composed of the secondary cells connecting the secondary cell to which the departure point belongs to the secondary cell to which the destination belongs. The route guidance method according to claim 1.   In the step of searching for the mesh route, the cell corresponding to the area where the density of the road links on the road map is relatively higher than the cell corresponding to the area where the density of the road links is relatively low. The route guidance method according to any one of claims 1 to 3, wherein the size of the cell is varied so as to be reduced. A route guidance system for guiding a route from a departure point to a destination on a road map,
A memory for storing a mesh map composed of a plurality of cells obtained by dividing the road map into mesh shapes;
The mesh map is read from the memory, and the plurality of cells are connected to the cell to which the destination belongs and the cell to which the destination belongs, based on the ease of passage in the plurality of cells. A microcomputer that searches for a mesh route constituted by cells and searches for a route constituted by the road link connecting the starting point to the destination for a road link in the searched mesh route; A route guidance system comprising:

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