JP3910203B2 - Route selection method - Google Patents

Description

  The present invention relates to a route selection method, and more specifically to a method for selecting an optimum route between two arbitrary points on map data.

  As is well known, the car navigation system detects and displays the current location of the vehicle and automatically searches for the optimum route to the destination, and displays the vehicle along the optimum route by display guidance and / or voice guidance. It is a system that guides you to your destination. In such a car navigation system, it is required to select a practical route for guidance and guidance as soon as possible. Therefore, methods for searching for a route in a short time have been actively researched and proposed.

  Conventionally, as a technique for performing a route search in a short time, for example, there is a hierarchical search method disclosed in Japanese Patent Laid-Open No. 4-301515. This hierarchical search method has hierarchical map data with different levels of detail, and the search is performed using detailed map data around the departure point and the destination, and coarser map data at the intermediate route. According to such a hierarchical search method, when the distance between the starting point and the destination is a long distance, the intermediate route can be searched using rough map data, so when searching all routes with detailed map data As a whole, the search time can be shortened.

  Furthermore, in Japanese Patent Laid-Open No. 4-301515, map data of each hierarchy is divided and recorded in a plurality of blocks. According to such a configuration, since it is possible to search only by reading the map data of the necessary blocks from each layer, the map data access time is shortened compared to the case where all the map data of each layer is read and searched. Can be

  However, in the above conventional technique, the timing of the map reading process that occupies a large weight in the route selection time is not optimized, and furthermore, the map data to be searched is all searched in the hierarchical order. There was a problem that the selection time was relatively long.

  Therefore, an object of the present invention is to provide a method capable of providing the shortest cost route as the optimum route in a short time.

  A first invention is a route selection method for selecting an optimum route between two arbitrary points using hierarchical map data, and sets two points on the map data. Before searching the map and the optimum route between the two points set in step, the highest hierarchy to be routed is determined according to the positional relationship between the two points, and the route search is further performed. A search candidate hierarchy for which a route search is to be performed is determined by determining an intermediate hierarchy in which a route search is not performed from among the intermediate hierarchies between the highest hierarchy and the lowest hierarchy according to the positional relationship between two points. And a step of searching for an optimal route between two set points based on the map data, and the step of searching for the optimal route is a process of transitioning to a higher hierarchy between search candidate hierarchies as the search range widens Do Reluctant, characterized in that it searches for an optimum route between two points that are set.

  In a second aspect based on the first aspect, the step of determining a search candidate hierarchy should perform a path search when the number of hierarchies from the lowest hierarchy to the highest hierarchy on which a path search is to be performed is a predetermined number or more. It is characterized in that an intermediate hierarchy in which route search is not performed is determined so that the number of search candidate hierarchies is a certain number or less.

  A third invention is a method for selecting an optimal route between two arbitrary points using hierarchized map data, the step of setting two points on the map data, and the search range is expanded. And searching for the optimum route between two set points while moving the map data from the lower layer to the upper layer, and the step of searching for the optimum route is at the time of searching in a certain layer or at the end of the search Later, the number of points that can be transferred from the certain one layer to each upper layer is counted, and if there is an upper layer in which the counted number of points is greater than or equal to a predetermined value, The route search in the highest hierarchy is started without performing the route search in the hierarchy between the highest hierarchy and a certain hierarchy.

  According to the first invention, since the search candidate hierarchy excluding the search hierarchy that can be omitted is set according to the set positional relationship between the two points, the search time for the omitted hierarchy can be reduced. As a result, the search time can be shortened.

  According to the third invention, when there is an upper layer in which the counted number of points is greater than or equal to a predetermined value, the layer between the highest layer and the one layer among the upper layers By starting the route search in the highest hierarchy without performing the route search in, the search time for the hierarchy between the highest hierarchy and one hierarchy is reduced, and the route selection Time can be shortened.

  FIG. 1 is a block diagram showing a configuration of a car navigation system according to an embodiment of the present invention. In FIG. 1, the car navigation system of this embodiment includes an input device 101, a locator 102, a recording device 103, a communication device 104, a navigation device 105, and an output device 106.

  The input device 101 performs navigation system function selection (processing item change, map switching / hierarchy change, etc.), point setting, search mode selection, and the like using a remote controller, touch sensor, keyboard, mouse, and the like. The locator 102 includes a GPS, a vehicle speed sensor, an angular velocity sensor, an absolute azimuth sensor, and the like, and collects various information for calculating the current position of the vehicle. The recording device 103 includes an optical disk (CD, DVD, etc.), a hard disk, a large-capacity memory, and the like, and stores information related to the road network such as intersections, road connections, coordinates, shapes, attributes, and regulation information. The communication device 104 includes various wireless communication devices such as an FM multiplex communication device / light / radio wave beacon device, and transmits and receives various information such as traffic information and map information. The navigation device 105 usually includes a CPU, memory (program memory, working memory), etc., and detects the current position of the vehicle, searches for routes / guides, searches and provides various information (such as map information, traffic information, and peripheral information). I do. The output device 106 includes a display device (liquid crystal display, CRT display, etc.), a speaker, and the like, and performs image display and voice guidance for various information and guidance routes.

  Here, the map data recorded in the recording device 103 will be described. FIG. 2 is a diagram illustrating a configuration example of map data. Usually, map data is roughly divided into two components. The first component is node data that is information about an intersection. The second component is link data, which is information on roads connecting the intersections. In the present embodiment, the above-described two components are recorded according to hierarchy. FIG. 3 is a diagram for explaining the structure of the map data according to hierarchy. In FIG. 3, the map data is divided into four layers of layers 1 to 4 as an example. Here, the hierarchy 1 is the lowest hierarchy and the hierarchy 4 is the highest hierarchy. Further, each level of map data is divided into a plurality of blocks.

  The operation of the car navigation system configured as described above will be described below. The functions of the car navigation system include a route selection / guidance function, a current position display function, an information search / provision function, and the like. Here, a route selection / guidance function that is of interest to the present invention will be described.

  First, in the input device 101, the user sets a departure place and a destination. That is, by operating the input device 101, the user scrolls the map image displayed on the output device 106, and inputs desired points as the departure point and the destination. Note that the current position of the vehicle detected using the locator 102 may be used as the departure place.

  Next, the navigation device 105 selects the nearest node or the nearest link on the map of the lowest hierarchy stored in the recording device 103 based on the position of the departure place and the destination set as described above. The connecting node is adopted as the departure node and the destination node. Further, the navigation device 105 calculates the shortest cost route using a known Dijkstra method, etc., converts the obtained route into a link row, a node row, or a coordinate row to obtain a guidance route. However, the navigation device 105 calculates the shortest cost route from the lowest hierarchy using the departure node and destination node as the search start points, and does not find a route even if the search is expanded to a predetermined range for each hierarchy. In such a case, the process of calculating the shortest cost route is repeated using the upper level map data in which only the main road is recorded over a wider area. At this time, the route to be selected may be changed using a method such as changing the link cost based on the traffic information obtained by the communication device 104. The navigation device 105 sets a guidance route based on the search result selected in this way, calculates the current position of the vehicle from the position information detected by the locator 102, and guides the guidance route to the destination.

  Finally, the output device 106 receives an instruction from the navigation device 105 and presents guidance information to the user by voice or display.

  FIG. 4 is a functional block diagram showing a configuration example of the navigation device 105 shown in FIG. In FIG. 4, the navigation device 105 includes a position detection unit 201, an information search / providing unit 202, a route selection unit 203, and a guidance unit 204.

  The position detection unit 201 performs map matching on the road network of the map data recorded in the recording device 103 based on the position information detected by the locator 102, or uses the vehicle position correction information input from the input device 101. To identify the current position of the vehicle. Based on the current location detected by the position detector 201, the information search / provider 202 displays the map data recorded in the recording device 103 on the output device 106, or in accordance with a user request input by the input device 101. Searching and providing various information such as changing the display range and level of detail of the map and displaying the traffic information obtained by the communication device 104 are performed. The route selection unit 203 reads map data of a necessary range from the recording device 103, and based on the current position of the vehicle detected by the position detection unit 201 and the point information input by the input device 101, the departure point and destination The minimum cost route from the departure point to the destination is selected in consideration of intersection traffic restrictions and one-way restrictions. Further, in which direction the guidance unit 204 should proceed based on the map data acquired from the recording device 103 and the current position of the vehicle detected by the position detection unit 201 based on the guidance route selected by the route selection unit 203. Guide to the destination. Further, hereinafter, the route selection unit 203 that performs route selection processing will be described in detail.

(1) First Configuration Example of Route Selection Unit 203 FIG. 5 is a functional block diagram showing a first configuration example of the route selection unit 203 shown in FIG. In FIG. 5, the route selection unit 203 includes a map storage unit 301, a spot setting unit 302, a route search unit 303, a search result data storage unit 304, and a map reading parallel processing unit 401.

  The map storage unit 301 reads map data in a range necessary for route search and spot setting from the recording device 103 and stores the map data. The point setting unit 302 sets the current position of the vehicle detected by the position detection unit 201 as a departure point and the point input by the input device 101 as a destination, and sets a departure node and a destination node on the map corresponding to each point. To do. The route search unit 303 uses a known Dijkstra method or the like to perform a search process using the departure node and destination node set by the location setting unit 302 in order from the lowest layer as a search start point, and the minimum from the departure node to the destination node Find the cost path. The search result data storage unit 304 records intermediate data and route information at the time of search. The map reading parallel processing unit 401 reads all the map units in the range used for the next search into the map storage unit 301 in parallel with the processing of the point setting unit 302 and the route search unit 303.

  The operation of the route selection unit 203 of the first configuration example configured as described above will be described in detail below according to a flowchart.

  FIG. 6 is a flowchart showing the operation of the point setting unit 302 in the first configuration example of the route selection unit 203. First, in step S601 of FIG. 6, the point setting unit 302 obtains the map data of the lowest hierarchy from the recording device 103 (more specifically, the departure place (for example, the current position of the vehicle detected by the position detection unit 201). Map data of the block including the data) is read and stored in the map storage unit 301, the node closest to the departure place is set as the departure node, and the arrival cost (for example, 0) is set. Next, in step S <b> 602, the location setting unit 302 includes map data of a block including the lowest-level map data (more specifically, a destination (for example, a location input by the user using the input device 101) from the recording device 103. ) Is stored in the map storage unit 301, the node closest to the destination is set as the destination node, and the arrival cost (for example, 0) is set.

  At this time, the map reading parallel processing unit 401 starts the processing of the point setting unit 302 (see FIG. 6), and simultaneously obtains the map data in the range necessary for the search from the departure point side of the lowest hierarchy from the recording device 103. It is read and stored in the map storage unit 301. The map data read at this time is a plurality of blocks located around the block read for the point setting in step S601 (for example, eight blocks surrounding the block read for the point setting). Map data. Thus, the reason why the plurality of blocks of map data are required for the search processing is mainly to make it possible to more reliably move to a higher hierarchy.

  Next, a route search process for obtaining a minimum cost route is executed by the route search unit 303. FIG. 7 is a flowchart showing the operation of the route search process of the route search unit 303 in the first configuration example of the route selection unit 203.

  First, in step S701 in FIG. 7, the route search unit 303 sets the departure node as the departure side candidate state and the destination node as the destination side candidate state, and stores them in the search result data storage unit 304, respectively. Next, the route search unit 303 sets the lowest hierarchy as the first search hierarchy (step S702).

  Next, the route search unit 303 reads the necessary map data from the recording device 103 if the map storage unit 301 has not been read, and uses the known Dijkstra method as a starting point for the intermediate data. Is stored in the search result data storage unit 304, and a departure side search process within a certain area is performed (step S703). Next, the route search unit 303 determines whether or not the shortest cost route to the destination candidate state node has been determined during the search process in the fixed area in step S703 (step S704). When the shortest cost route to the destination side candidate state node is determined, the route search unit 303 finishes the departure side search processing assuming that the route has been obtained, proceeds to step S711, and stores the search result data storage unit 304 in the search result data storage unit 304. A route is constructed from the stored search results. On the other hand, when the shortest cost route to the destination candidate state node has not been determined, the route search unit 303 executes the process of step S705.

  In step S705, the route search unit 303 reads the necessary map data from the recording device 103 if the map storage unit 301 has not read the map data, and uses a known Dijkstra method with the destination side candidate state node as a starting point. While storing the intermediate data in the search result data storage unit 304, a destination side search process in a certain area is performed. Next, the route search unit 303 determines whether or not the shortest cost route to the departure point side search end node has been determined during the search process in the fixed area in step S705 (step S706). When the shortest cost route to the departure point side search end node is confirmed, the route search unit 303 finishes the destination side search process on the assumption that the route has been obtained, proceeds to step S711, and stores the search result data storage unit 304 in the search result data storage unit 304. A route is constructed from the stored search results. On the other hand, when the shortest cost route to the departure point side search end node has not been determined, the route search unit 303 executes the process of step S707.

  In step S707, the route search unit 303 determines whether the search hierarchy is the highest hierarchy. At this time, if the search hierarchy is the highest hierarchy, the route search unit 303 determines that the search has failed (step S710), and ends the route search process. On the other hand, if the search hierarchy is not the highest hierarchy, the route search unit 303 is a searched node located on the outer periphery of the departure place side search area and recorded in the upper hierarchy (hereinafter referred to as the departure place side upper rank). A node that has been searched and is also recorded in the upper hierarchy (hereinafter referred to as a destination-side higher-level transition node). Is set as a destination candidate state (step S708). Next, the route search unit 303 moves the search hierarchy up one level (step S709), and returns to the process of step S703. Thereafter, the route search unit 303 repeats the processes of steps S703 to S709 until a route is obtained.

  According to the first configuration example described above, the search time can be reduced as follows compared to the conventional example. FIG. 8 is a timing chart showing processing timing of the conventional route selection unit 203. FIG. 9 is a timing chart showing processing timing in the first configuration example of the route selection unit 203 in the present invention. Conventionally, as shown in FIG. 8, after the point setting process is completed, the map data for searching for the departure point side in the lowest hierarchy, that is, the lowest hierarchy, is executed. On the other hand, in the first configuration example of the route selection unit 203 according to the present invention, by adding a map reading parallel processing unit 401, as shown in FIG. In addition, the map reading parallel processing unit 401 performs the reading process of the departure point side search map data (the map data of the lowest layer 1). Thereby, since the search process of the route search unit 303 can be started immediately after the spot setting process of the spot setting unit 302, the search time can be shortened as a result.

  In the first configuration example, since the spot setting unit 302 and the map reading parallel processing unit 401 need to operate in parallel, the spot setting unit 302 and the map reading parallel processing unit 401 are realized by different CPUs. Alternatively, the map reading parallel processing unit 401 may be configured by a circuit block (for example, a DMA transfer device) that functions independently of the operation of the CPU.

(2) Second Configuration Example of Route Selection Unit 203 FIG. 10 is a functional block diagram showing a second configuration example of the route selection unit 203 shown in FIG. In FIG. 10, the route selection unit 203 includes a first map storage unit 501, a second map storage unit 502, a spot setting unit 302, a route search unit 303, a search result data storage unit 304, and a parallel map reading. And a processing unit 401.

  The first and second map storage units 501 and 502 read and store map data in a range necessary for route search and spot setting from the recording device 103. The point setting unit 302 sets the current position of the vehicle detected by the position detection unit 201 as a departure point and the point input by the input device 101 as a destination, and sets a departure node and a destination node on the map corresponding to each point. To do. The route search unit 303 uses a known Dijkstra method or the like to perform a search process using the departure node and destination node set by the location setting unit 302 in order from the lowest layer as a search start point, and the minimum from the departure node to the destination node Find the cost path. The search result data storage unit 304 records intermediate data and route information at the time of search. In parallel with the processing of the point setting unit 302 and the route search unit 303, the map reading parallel processing unit 401 stores all map units in the range used for the next search in the first map storage unit 501 or the second map storage unit 502. Read.

  The operation of the route selection unit 203 of the second configuration example configured as described above will be described in detail below. The only difference from the first configuration example is that the map storage unit 301 has two maps, the first map storage unit 501 and the second map storage unit 502, and the processing of the map reading parallel processing unit 401. Only the differences will be described.

  The map reading parallel processing unit 401 reads, from the recording device 103, the first map storage unit 501 from the recording device 103 the map data in the range necessary for the search for the departure point side of the lowest hierarchy at the same time when the processing of the point setting unit 302 is started. . Thereafter, the route search unit 303 uses the map data read into the first map storage unit 501 to execute the search process on the departure side of the hierarchy 1, and at the same time, the map in the range necessary for the destination side search of the lowest hierarchy Data is read from the recording device 103 into the second map storage unit 502. As described above, the map reading parallel processing unit 401 pre-reads map data necessary for the next search processing until the route search is completed while sequentially switching the duplicated map storage units.

  FIG. 11 is a timing chart showing processing timing in the second configuration example of the route selection unit 203. As described above, according to the second configuration example, by duplicating the map storage unit and adding the map reading parallel processing unit 401, as shown in FIG. 11, a point setting unit 302 and a route searching unit 303 are provided. In parallel with the process performed in step S1, the map data necessary for the next search process performed in the route search unit 303 can be prefetched. As a result, the search process for the next section can be started immediately after the end of the search for one section, and as a result, the search time can be shortened.

  In the second configuration example, the point setting unit 302, the route searching unit 303, and the map reading parallel processing unit 401 need to operate in parallel. Therefore, the map reading parallel processing unit 401 may be realized by a CPU different from the point setting unit 302 and the route searching unit 303, and the map reading parallel processing unit 401 functions independently of the operation of the CPU. You may make it comprise with a circuit block (for example, DMA transfer apparatus).

(3) Third Configuration Example of Route Selection Unit 203 FIG. 12 is a functional block diagram showing a third configuration example of the route selection unit 203 shown in FIG. In FIG. 12, the route selection unit 203 includes a map storage unit 301, a spot setting unit 302, a route search unit 303, a search result data storage unit 304, and a search hierarchy determination unit 601.

  The map storage unit 301 reads map data in a range necessary for route search and spot setting from the recording device 103 and stores the map data. The point setting unit 302 sets the current position of the vehicle detected by the position detection unit 201 as a departure point and the point input by the input device 101 as a destination, and sets a departure node and a destination node on the map corresponding to each point. To do. The search hierarchy determination unit 601 determines a hierarchy to be searched from the departure node and the destination node set by the point setting unit 302. The route search unit 303 uses the known Dijkstra method or the like to search for the departure node and the destination node set by the point setting unit 302 in order from the lowest layer to the search layer determined by the search layer determination unit 601. The minimum cost route from the departure node to the destination node is obtained. The search result data storage unit 304 records intermediate data and route information at the time of search.

  The operation of the route selection unit 203 of the third configuration example configured as described above will be described in detail below. The difference from the first configuration example is that the map reading parallel processing unit 401 is eliminated, the processing in the search hierarchy determination unit 601 and only a part of the processing of the route search unit 303, so only the different parts explain.

  The search hierarchy determination unit 601 determines a hierarchy to be searched from the departure node and the destination node set by the point setting unit 302. At this time, the highest hierarchy to be searched is set according to the distance between the departure node and the destination node. If the number of hierarchy is equal to or higher than a certain number of hierarchy (for example, 4 hierarchy), the lowest hierarchy and the highest hierarchy are By omitting the excluded intermediate hierarchies, the search target hierarchies are kept below a certain number of hierarchies (for example, three hierarchies). FIG. 13 is a conceptual diagram when layer 3 is omitted. In the example of FIG. 13, it is determined that the search is performed up to the hierarchy 4 from the distance between the departure node and the destination node, and the hierarchy 3 that is an intermediate hierarchy is omitted. It should be noted that the omitted intermediate hierarchies are preferably set at regular intervals with good balance.

  Further, the operation of the route search process in the route search unit 303 will be described in detail below according to the flowchart. FIG. 14 is a flowchart showing route search processing of the route search unit 303 in the third configuration example of the route selection unit 203. Since this flowchart is almost the same as the flowchart of the route search process of the route search unit 303 (see FIG. 5) in the first configuration example of the route selection unit 203 shown in FIG. 7, only different parts will be described.

  This flowchart is different from the flowchart (FIG. 7) of the route search process of the route search unit 303 in the first configuration example of the route selection unit 203 in steps S1901 to S1907 (corresponding to steps S701 to S707 in FIG. 7). Later, steps S1912 to S1915 are added. When the search processing of the current search hierarchy is completed by the processing of steps S1901 to S1907 and the route is not obtained, the route search unit 303 determines whether the search is performed according to the determination result of the search hierarchy determination unit 601 in step S1912. It is determined whether or not the upper hierarchy can be omitted. If it is not omissible, the route search unit 303 proceeds to step S1908 (corresponding to step S708 in FIG. 7), and as described in the first configuration example, the search processing is performed with the upper hierarchy as the search hierarchy. To continue. If it is determined in step S 1912 that the search can be omitted, the route search unit 303 proceeds to step S 1913 and is a searched node located on the outer periphery of the departure point side search area, and the next search determined by the search hierarchy determination unit 601. The node recorded in the candidate hierarchy is a (departure side higher hierarchy transition node) departure point side candidate state, a searched node located on the outer periphery of the destination side search area, and determined by the search hierarchy determination unit 601 The node recorded in the next search candidate hierarchy (destination side upper hierarchy transition node) is set to the destination side candidate state. Next, the route search unit 303 determines whether or not there are more than a specific number (for example, 8) of nodes (departure side upper layer transition node and destination side upper layer transition node) that have moved to the next search candidate layer. (Step S1914). If there is not a specific number or more, the route search unit 303 returns to step S1908 and continues the search process without omitting the upper layer one level above. On the other hand, if there is a specific number or more of nodes that have moved to the next search candidate hierarchy, the route search unit 303 proceeds to step S1915, shifts the search hierarchy to the next search candidate hierarchy, and continues the search process.

  As described above, according to the third configuration example, the search hierarchy determination unit 601 is added, and the search of the intermediate hierarchy excluding the lowest hierarchy and the highest hierarchy to be searched is omitted. As a result, the search time can be shortened.

  Further, in the route search unit 303, if the number of upper layer transition nodes to the next search candidate layer determined by the search layer determination unit 601 is equal to or less than a predetermined number, the lower layer is set as the next search layer. By doing so, it is possible to prevent the occurrence of a detour route caused by a shortage of the upper layer transition nodes, and as a result, it is possible to improve the route quality.

  In the third configuration example, the hierarchy that can be omitted is determined before the search is started. However, after the search for one hierarchy is completed, the number of upper transition points is checked for all the upper hierarchies. It is also possible to move to the highest hierarchy among the upper hierarchy where there are a certain number or more of the upper migration points. At that time, the highest hierarchy to be searched may be determined according to the positional relationship between the departure place and the destination.

  In the first to third configuration examples described above, when a route cannot be obtained in the current search hierarchy, the search is made to move to a higher hierarchy after the search in the fixed area is completed. Even if the search is not completed, the search may be stopped and the upper layer may be shifted to a higher layer when a certain number of upper layer transition nodes have been secured. By doing so, the search hierarchy can be shifted to a higher hierarchy with a minimum search range, and the route selection time can be shortened.

  Furthermore, the first to third configuration examples described above may be configured as hardware or may be configured by program processing such as multitasking of a microcomputer. The locator 102 may have any configuration as long as it has a function of detecting the current position of the vehicle. In addition, the input device 101 designates the position by scrolling the map image displayed on the output device 106. However, the input device 101 may designate the position by a method of selecting the latitude and longitude stored in advance. good. Further, the spot setting unit 302 may set the departure place according to the position where the user inputs. Furthermore, although the node closest to the departure point and the destination is set as the departure node or the destination node, it may be a point on the nearest link or a plurality of points may be set. Further, although the Dijkstra method is exemplified here as a search method, any method may be used as long as it is a method for obtaining the shortest cost path between two points based on cost information for each link. Further, the output device 106 performs guidance by display or voice. However, for example, an automatic control unit may be added to give the selected route to the control system of the automobile. Furthermore, the configurations described in the above embodiments may be used in combination.

  In addition, the present invention is realized by a program, and can be easily implemented by another independent computer system by recording and transferring the program on a recording medium such as a floppy (registered trademark) disk. In this case, the recording medium is not limited to a floppy (registered trademark) disk, and may be any medium such as an optical disk, an IC card, and a ROM cassette as long as the program can be recorded.

  The route selection method of the present invention can be applied to a navigation device or the like that can provide the shortest cost route as an optimum route in a short time.

It is a block diagram which shows the structure of the car navigation system which concerns on one Embodiment of this invention. It is a figure which shows one structural example of map data. It is a figure for demonstrating the structure of the map data according to a hierarchy. It is a functional block diagram which shows the structural example of the navigation apparatus 105 shown in FIG. FIG. 5 is a functional block diagram illustrating a first configuration example of a route selection unit 203 illustrated in FIG. 4. 10 is a flowchart showing an operation of a point setting unit 302 in the first configuration example of the route selection unit 203. 10 is a flowchart showing an operation of a route search unit 303 in the first configuration example of the route selection unit 203. It is a timing chart which shows the processing timing of search processing operation and map reading operation in the conventional car navigation system. 10 is a timing chart showing processing timings of a search processing operation and a map reading operation in the first configuration example of the route selection unit 203. FIG. 5 is a functional block diagram illustrating a second configuration example of the route selection unit 203 illustrated in FIG. 4. It is a timing chart which shows the processing timing of search processing operation and map reading operation in the 2nd example of composition of route selection part 203. FIG. 5 is a functional block diagram illustrating a third configuration example of the route selection unit 203 illustrated in FIG. 4. It is a conceptual diagram in case the hierarchy 3 is abbreviate | omitted in the 3rd structural example of the route selection part 203. FIG. 12 is a flowchart showing route search processing of a route search unit 303 in the third configuration example of the route selection unit 203.

Explanation of symbols

DESCRIPTION OF SYMBOLS 101 Input device 102 Locator 103 Recording device 104 Communication device 105 Navigation device 106 Output device 201 Position detection unit 202 Information search / providing unit 203 Route selection unit 204 Guide unit 301 Map storage unit 302 Point setting unit 303 Route search unit 304 Search result data Storage unit 401 Map reading parallel processing unit 501 First map storage unit 502 Second map storage unit 601 Search hierarchy determination unit

Claims (3)

A method for selecting an optimal route between two arbitrary points using hierarchical map data,
Setting the two points on the map data;
Before searching the optimum route between the two set points on the map data, the highest hierarchy to be searched for route is determined according to the positional relationship between the two points, and the highest route to be searched for is further determined. A step of determining a search candidate layer to be searched for a route by determining an intermediate layer in which a route search is not performed among the intermediate layers between the upper layer and the lowest layer according to the positional relationship between the two points. When,
Searching for an optimal route between the set two points based on the map data,
The step of searching for the optimum route searches for the optimum route between the set two points while performing a transition process to an upper layer between the search candidate layers as the search range widens. Selection method.   In the step of determining the search candidate hierarchy, when the number of hierarchies from the lowest hierarchy to the highest hierarchy to perform the route search is equal to or greater than a predetermined number, the number of search candidate hierarchies to perform the route search is a certain number or less. Thus, the route selection method according to claim 1, wherein an intermediate layer that does not perform route search is determined. A method for selecting an optimal route between two arbitrary points using hierarchical map data,
Setting the two points on the map data;
Searching for an optimal route between the set two points while shifting the map data from a lower hierarchy to an upper hierarchy as the search range widens,
The step of searching for the optimum route includes:
Count the number of points that can be transferred from one layer to each higher layer at the time of searching in one layer or after the search,
When there is an upper layer in which the counted number of points is equal to or greater than a predetermined value, route search is performed in a layer between the highest layer of the upper layer and the one layer. A route selection method, characterized in that a route search in the highest hierarchy is started.

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