JPH10170295A - Route searching device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To read route searching data efficiently to reduce processing time, by reading control data in order of first reading, second, third, fourth, and fifth. SOLUTION: During searching of a route, a first link connecting information which corresponds to a map with a specific contraction scale is read prior to a second link connecting information which corresponds to a larger area map than a specific contraction scale map so that reading of the first link connecting information and reading of the second link connecting information are not mixed each other. Thus, the first, second, and third reading of the first link connecting information are executed prior to fourth and fifth reading of the second link connecting information so that the reading of the first link connecting information and the reading of the second link connecting information are not mixed each other. Therefore, data can be read efficiently.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a route searching device applied to a vehicle-mounted navigation device for searching for a route from a departure place to a destination.

[0002]

2. Description of the Related Art A vehicle equipped with a function of displaying a road map around a vehicle position, a function of accurately detecting a vehicle position by performing map matching, and a function of calculating a recommended route from a departure place to a destination. Navigation devices are known. In this in-vehicle navigation device, data for road map display, data for map matching, and data for route search are stored in one CD-ROM.

The road map display data includes the widest area map data for displaying a wide area with the smallest scale, the most detailed map data for displaying the narrowest area with the largest scale in detail, and the widest area map data. And the most detailed map data and a plurality of map data of different scales. For example, the widest map data is referred to as level 4 data, the most detailed map data is referred to as level 1 data, and the data between levels 4 and 1 is referred to as level 3 and 2 data, respectively. The route search data includes two data corresponding to level 4 and level 2 of the road map data. In route search, the vicinity of the departure point and the destination are searched at level 2, and the other areas are searched at level 4. The route search time is shortened.

[0004]

However, when one or more stopovers are set between the departure point and the destination, reading of the level 2 route search data and reading of the level 4 route search data are mixed. However, even if a buffer memory or the like is provided between the CD-ROM device and the control device, the read data does not efficiently hit on the buffer memory, causing a problem that the processing speed is reduced.

[0005] It is an object of the present invention to provide a route search apparatus that efficiently reads route search data and shortens the processing time.

[0006]

In order to achieve the above object, a route search apparatus according to claim 1 uses a minimum unit of a road on a map as a link to link position information and a map of a predetermined scale. Storage means for storing corresponding first inter-link connection information and second inter-link connection information corresponding to a map wider than a predetermined map, and a point for setting a departure point, a transit point, and a destination The present invention is applied to a route search device that includes a setting unit and a control unit that performs a route search from a departure place to a destination via a transit point. A first read for reading the inter-link connection information, a second read for reading the first inter-link connection information near the set waypoint, and the first inter-link connection information near the set destination Perform a third read to read, A fourth reading for reading the second link connection information in the range including the determined departure point and the via point, and a fifth reading for reading the second link information in the range including the set via point and the destination point And read the
(B) A route search near the departure place is performed based on the read first inter-link connection information near the departure place, and (c) based on the read first inter-link connection information near the transit place. (D) A route search near the destination is performed based on the read first connection information between links near the destination, and (e) A route search result near the departure place And a route search from the departure point to the stopover is performed based on the route search result near the stopover and the readout point and the second link connection information in the range including the stopover. Performing a route search from the stopover to the destination based on the route search result in the vicinity, the route search result in the vicinity of the destination, and the read connection information between the links including the stopover and the destination, (G) The first to third readings correspond to the fourth reading. It is obtained to perform prior to than to and fifth read. According to a second aspect of the present invention, in the route search device, the control unit performs the reading in the order of the first reading, the second reading, the third reading, the fourth reading, and the fifth reading. Claim 3
The route searching device described above controls the control means in the route search from the departure place to the transit point and the route search from the transit point to the destination in the first route near the transit point read by the second reading.
In this case, a route search result near a transit point, which has been searched for a route based on the link connection information, is commonly used. The route search device according to claim 4, wherein the point setting means can set a plurality of transit points, and the control means reads out the second link connection information in a range including the set plural transit points. And performing a route search between the transit points based on the route search results near the plurality of transit points and the read second link information between the links including the plurality of transit points. The first to third readings are performed prior to the sixth reading. According to a fifth aspect of the present invention, in the route search device, the control unit includes:
The first reading, the second reading, the third reading, the fourth reading, the sixth reading, and the fifth reading are performed in this order. According to a sixth aspect of the present invention, the storage means is a CD-ROM device, and the control means includes a buffer memory. In a preferred embodiment, the storage means is a magnetic disk drive, and the control means includes a buffer memory.

[0007]

FIG. 1 is a block diagram of an embodiment in which a route search device according to the present invention is applied to an on-vehicle navigation device. In FIG. 1, reference numeral 1 denotes a current position detecting device for detecting a current position of a vehicle, for example, a direction sensor for detecting a traveling direction of the vehicle, a vehicle speed sensor for detecting a vehicle speed, and a GPS signal from a GPS (Global Positioning System) satellite. It consists of a GPS sensor and the like.

Reference numeral 2 denotes a control circuit for controlling the entire apparatus.
It consists of a microprocessor and its peripheral circuits. Reference numeral 3 denotes an input device for inputting a destination of the vehicle and the like.
AM and 5 are image memories for storing image data to be displayed on the display device 6, and the image data stored in the image memory 5 is appropriately read and displayed on the display device 6.
Reference numeral 7 denotes an SRAM for storing node information, link information, and the like on the recommended route calculated by the control circuit 2.

Reference numeral 8 denotes a map database device for storing various data for performing road map display, route search (route search), map matching, and the like.
-It is composed of a ROM device, a magnetic recording device and the like. The map database device 8 stores map display data including information on road shapes and road types, and route search data including branch point information and intersection information that are not directly related to the road shapes. The map display data is mainly used when displaying a road map on the display device 6, and the route search data is mainly used when calculating a recommended route (recommended route).

Reference numeral 9 denotes a buffer memory provided between the map database device 8 and the control circuit 2. When the control circuit 2 attempts to read data from the map database device 8, the data is temporarily stored in the buffer memory 9 from the map database device 8, and then the contents of the buffer memory 9 are read. Therefore, CD-
When accessing data in a certain area of the ROM or the magnetic disk, if the data already exists in the buffer memory 9, the data is read from the buffer memory 9 without accessing the CD-ROM or the magnetic disk. Time can be reduced. When data is read out to the buffer memory 9, the data is read out in a predetermined capacity unit, and thus there is a possibility that the data is read out to the buffer memory 9 up to a range beyond the area to be read out. Therefore, when reading data subsequent to previously read data, the probability that the data already exists in the buffer memory 9 is high, and the access time can be reduced from now on. The operation of the buffer memory is well known in computer systems and the like, and will not be further described. The buffer memory 9 may be built in the map database device 8.

Next, the data structures of the map display data and the route search data stored in the map database device 8 will be described in detail.

[1] Map Display Data (1) Outline of Link String Data The map display data of the present embodiment manages data for each mesh area obtained by dividing a road map into predetermined ranges. Each road existing in the area is set as a separate link row. For example, as shown in FIG. 2, when two roads D1 and D2 intersect in one mesh region, each road is represented by separate link columns 1 and 2, respectively. Is composed of links 11 and 12, and the link row 2 is composed of links 21 to 23. In this case, each link in the link row 1 and each link in the link row 2 are roads of the same type. A link is a minimum unit representing a road. In FIG. 2, a link between intersections is a unit of a link, and each link is distinguished by a unique number (hereinafter, referred to as a link number). The intersections in FIG. 2, that is, the connection points of the links are represented by nodes N0 to N4. A node is also a starting point and an ending point of each link, and as described later, an interpolation point for further dividing between nodes may be provided.

The map display data includes a plurality of data having different scales. In the present embodiment, data of each scale is referred to as data of level n (n is, for example, 1 to 4). Level 1 is the most detailed road map. The higher the level, the smaller the scale and the wider the road map. Further, in the present embodiment, as described later, the same link is assigned to the same (unique) link number at each level and managed to facilitate data association between different levels.
The link number will be described later.

(2) Data Structure of Link String Data To explain the road shown in FIG. 2, data for map display is as follows.
As shown in FIG. 3, link string data describing various information related to link strings 1, 2 to n is provided for each link string, and the data of each link string has link string information and node link information, The link string information is composed of the following data as shown in FIG. Link row size Number of element points Link attribute Road name offset Route number

The node link information is composed of the following data as shown in FIG. Attribute 1 + X coordinate Attribute 2 + Y coordinate Same node offset Guidance offset Link number Height information

(3) Link String Information In FIG. 3, the link string size is the accommodation size of the link string data, and the next link string data can be immediately accessed by this accommodation size. The number of element points is data representing the sum of the number of node points and the number of interpolation points, the link attribute is data representing the type of road such as a national road, a prefectural road, or an expressway, and the route number is the number of a national road or prefectural road. The road name offset is irrelevant in this embodiment, and a description thereof will be omitted.
The interpolation points will be described later.

(4) Regarding Node Link Information FIG. 4 shows details of the link strings 1 and 2 shown in FIG. For example, the node link information of the link row 2 indicated by the thick line in FIG. 4 is as shown in FIG. As illustrated, the data of the link sequence 2 includes node information on nodes N1, N02, and N3 (black circles in FIG. 4) on the link sequence and interpolation point information on interpolation points (white circles in FIG. 4). The node information includes position coordinates X and Y of the node, an attribute of a link connected to the node, and a link number, and the interpolation point information includes position coordinates X and Y of the interpolation point.
Y. These position coordinates are used as shape data for displaying a recommended route or shape data for map matching to be described later. The link line 2 in bold lines in FIG. 4 includes a link with a link number 21 between the nodes N1 and N02, a link with a link number 22 between the nodes N02 and N3,
And a link with a link number 23 connected to the node N3. As can be seen from FIG. 5, the node information of the node N02 is shared by the link of the link number 21 and the link of the link number 22. The node information and the interpolation point information are arranged in data in the order of link connection. Therefore, by sequentially reading out the link string data from the head address, the road shape, the road type, and the like of the entire link string can be detected.

(5) Attribute 1 Attribute 1 stored together with the X coordinate of the node can be used as offset information for reading the link string data in the reverse direction. As shown in FIG. 6, 11 bits to 15 bits can be used, but details are omitted.

(6) Attribute 2 Attribute 2 stored together with the Y coordinate of the node includes traffic regulation information, road width information, and lane number information. The data length of each piece of node link information constituting link string data is 16
Bits (2 bytes = 1 word). In the lower 11 bits of the data representing the attribute 2 + Y coordinate, as shown in FIG.
The traffic control information, road width information, and lane number information are stored in the bits. 7 (b) is selected according to the combination of the upper 5 bits.

(7) Unique link number between levels The link number is, as shown in FIG.
Attribute 2 + Y coordinate and attribute 1 + X coordinate of next node, attribute 2
+ Y coordinate is stored for each link. In this embodiment, the link number given to the link at the highest level is set as the link number of the corresponding link at the lower level. That is, the same link number as the link number assigned to one link at the highest level is set as a unique link number and is set as the link number of the link corresponding to the lower level.

The link numbers will be further described with reference to FIG. Link row 1 of the highest level 4 is linked to link number 1
Assuming that the link is composed of two links, at the level 3, the link of the link number 1 of the upper level 4 is composed of two links of the common link number 1. Level 2 is composed of three links with link number 1, and level 1 is composed of four links with link number 1.

As described above, by using the same link number as that of the upper level as the link number of the lower level link corresponding to the upper level link, the same link sequence can be associated between different levels, or The same link string can be easily associated with the map display data and the route search data, and the processing time can be reduced. The description of the same node offset, guidance offset, and height information in FIG. 3 is omitted.

[2] Route Search Data The route search data includes a plurality of data corresponding to a plurality of road map display data having different scales, and the data at each scale is referred to as level m data. In the present embodiment, level 2 and level 4 data are prepared. Further, as described above, the same link at each level is managed by the same link number, and it is easy to associate data between different levels and to associate data with road map display data.

FIG. 9 is a diagram showing a data structure of route search data. As shown in the drawing, the route search data stores, for each connection point (node) of a link that is a minimum unit representing a road, node information indicating a connection relationship with another node. Each node information is composed of own node information and adjacent node information, and the own node information stores the position coordinates of the node. On the other hand, the adjacent node information stores an adjacent node number, a link number of a link from the own node to the adjacent node, a link cost of the link, and traffic regulation information of the link, as illustrated. ing. Each node information is stored in the order in which the links are connected, and the node number of the own node can be ascertained based on the order in which the nodes are stored.
Therefore, the node number of the own node can be grasped without storing the node number of the own node as own node information, and the memory capacity can be reduced.

[3] Recommended Route Data FIG. 10 is a diagram showing an outline of a data structure of recommended route data representing a recommended route from the departure point to the destination searched based on the route search data. In the recommended route data, node information and link information on the recommended route are classified and stored in mesh area units. Note that the mesh region refers to each of the divided regions when the road map is divided into predetermined ranges.

As shown in FIG. 10, recommended route data includes a mesh code, the number of nodes, node information, the number of link types, link information, ferry information, and tunnel information. Of these, the mesh code storage area stores a number for identifying the mesh area, the node number storage area stores the number of nodes existing in the mesh area, and the node information storage area stores As shown in detail in FIG. 11A, a node number, a position coordinate, a distance cost, and the like of each node in the mesh area are stored. The number of types of links existing in the mesh area is stored in the storage area of the number of link types, and the storage area of the link information is stored in the storage area of the link information, as shown in detail in FIG. The link type, the number of links, the link number, and the like of the link are stored. FIG. 11 shows a case where data from link row 1 to link row 2 exists in the area indicated by the same mesh code.

As described above, the recommended route data is created for each level, and in the present embodiment, the recommended route data of level 2 is provided near the start point and the end point on the recommended route. Level 4 recommended route data is created between the point and the end point.

Hereinafter, the operation of this embodiment will be described with reference to a flowchart. In this embodiment, a recommended route is displayed on the display device 6 as follows. Level 4
The recommended route is searched using the route search data of level 2 and the level 2 to create the recommended route data of levels 4 and 2. Further, the recommended route data of level 4 is converted into the level 2 recommended route data, and the level 2 The recommended route is superimposed on the level 2 or level 1 road map displayed on the display device 6 based on the recommended route data and the level 2 or 1 road map display data to draw the recommended route, for example. Display with a thick red line.

FIGS. 12 and 13 are flowcharts showing the outline of the main processing performed by the control circuit 2. FIG. In step S1 in FIG. 12, the vehicle position is detected using the current position detection device 1. In step S2, the destination input by the input device 3 is read. In step S3, based on the map display data stored in the map database device 8, the start point and the end point of the route search are set on the road on which the route search is possible. For example, the start point of the vehicle is the current position (vehicle position) of the vehicle, and the end point is the destination. The setting of the start point and the end point of the route search will be further described later.

In step S4, a route search near the start point of the route search is performed using the level 2 route search data. Then, a plurality of recommended route candidates near the start point are selected. In step S5, a route search near the end point of the route search is performed using the level 2 route search data. Then, a plurality of recommended route candidates near the end point are selected.

At step S6, the level 4 is set for the route between the recommended route candidates selected at steps S4 and S5.
A route search is performed using the route search data of the above, and a recommended route from the start point to the end point is calculated.

Thus, the vicinity of the start point and the end point,
The reason for using the different levels of route search data near the middle of the start point and the end point is that if the route search is performed for all routes using the level 2 route search data, the amount of data is enormous. This is because the calculation time required for the search becomes longer. In step S7, step S
The information on the recommended route calculated in 6 is stored in the SRAM 7 as recommended route data.

When the process in step S7 in FIG. 12 is completed, the process proceeds to step S8 in FIG. 13, where a background map drawing process is performed, and data on a road map around a recommended route to be displayed on the display device 6 is drawn in the image memory 5. (Store. When the process in step S8 is completed, the process proceeds to step S9, in which data necessary for displaying the recommended route calculated in step S6 is drawn (stored) in the image memory 5 in an overlapping manner. In step S10, the data stored in the image memory 5 is read, and the recommended route and a road map around the recommended route are displayed on the display device 6.

-Setting of start point and end point of route search-Setting of start point and end point of route search in the present embodiment will be described in further detail. FIG. 14 is a diagram illustrating a case where a start point of a route search is set. The mark represented by the symbol S indicates the vehicle position (departure position) detected by the current position detection device 1. This vehicle position S is the starting point of the route search. Two roads represented by links a and b are located near the vehicle position S.
In the conventional apparatus, a route search is performed by selecting the nearest link, for example, as a start point. However, if this link a is, for example, a one-way road and cannot travel in the direction of the arrow in FIG. 14, it is impossible to escape from the link a when performing a route search, so that the route search cannot be performed. In the present embodiment, a plurality of links that are candidates for the start point are selected within a certain range around the vehicle position S. As a result, even if a route search cannot be performed on a certain link, a route search can be performed on another candidate link. In FIG. 14, a link a and a link b are selected as starting point candidates, and a route search is performed for each. Then, even if the route search cannot be performed on the link a, the route search starting from the link b succeeds, so that the result does not mean that the route search is finally impossible.

FIG. 15 is a diagram for explaining a case where the end point of the route search is similarly set. The mark represented by the symbol D indicates a destination specified by the input device 3. This destination D is the end point of the route search. Destination D
In this case, a plurality of links are selected as candidates for the end point, but the description is omitted because the content is the same as above.

FIG. 16 is a diagram for explaining a case where a stopover point V is set between the host vehicle position S and the destination point D. For the route point V, in the route search from the vehicle position S to the route point D, the vehicle position S is the start point of the route search, and the route point V is the end point of the route search. Next, in the route search from the stopover to the destination, the stopover V is the start point of the route search, and the destination D is the end point of the route search. In FIG. 16, a stopover V is, for example, a rotary at a station, links a and b are one-way roads in the direction of the arrows, the vehicle position S is on the left in the figure, and the destination D is set on the right in the figure. ing. Since the stopover point V is a rotary, data exists for the links a and b as roads, but the portion indicated by c is not set as a road (link) and has no data.

In this case, in the route search from the vehicle position S to the stopover V, a plurality of links a and b which are candidates for the stopover at the stopover V are selected. When the link a is set as the end point, the route search succeeds, and the link b
The route search with the end point as a result results in that the route cannot be searched depending on the one-way direction of the link b. On the other hand, in the route search from the waypoint V to the destination D, the waypoint V is the starting point of the route search, and the links a and b of the starting point candidates are similarly set.
Is selected. Then, the route search using the link a as the starting point results in a route search being impossible, but the link b
The route search starting from is successful. In the present embodiment, in the route search from the own vehicle position S to the destination D via the waypoint V, the result is that the road is interrupted at the waypoint V as described above, but the route search is disabled as a whole. Instead, each route search is output.

FIG. 17 is a flowchart showing a multiple link selection process for selecting a plurality of links and storing them in the storage table at the start point or the end point of the route search described above.

In step S101, a search range is determined based on the set position (own vehicle position or departure position, waypoint, destination). As for the search range, a predetermined range is set by the program. For example, a range that can be displayed on the screen in the display of the most detailed scale map is set as a search range, a range of the currently displayed screen is set as a search range, or a range set by an operator operating the input device 1 is set as a search range. It can be a search range. This range can be varied according to specific conditions. For example, the search range may be reduced in an area with many nodes such as a city center, and the search range may be expanded in an area with few nodes such as a mountainous area. Step S
At 102, one link in the search range is selected, and the distance value (d) from the set position to the selected link (Ld)
Is calculated. The distance value (d) is the distance of the perpendicular from the set position to the link (Ld) based on the map display data. If the perpendicular cannot be lowered, the distance to the node located closer to the set value is set as the distance value (d). When considering up to the interpolation point in the link, the node is replaced with the interpolation point and the calculation is performed in the same way.

In step S103, it is determined whether a predetermined number of links are stored in the storage table. The predetermined number here is the number of the plurality of link candidates at each of the start point, the waypoint, and the end point of the route search. This number is predetermined in the program, but may be arbitrarily changed by the operator. When the predetermined number is stored, the process proceeds to step S104, and the link (LD) having the maximum distance value (D) is acquired from the links already stored in the storage table. In step S107 to be described later, the table is sorted in ascending order using the distance value as a parameter, so that the link located at the rear end may be obtained. In step S105, the selected link (Ld)
(D) and the maximum distance value (D) in the storage table
Is compared with the distance value (D) of the link (LD) having The distance value (d) of the selected link (Ld) is
When the distance is smaller than the distance value (D) of the link (LD) having the maximum distance value in the storage table, the process proceeds to step S106, and the link Ld is replaced with the link LD in the storage table. Next, in step S107, the table is sorted using the distance value as a parameter, and the process proceeds to step S108. In step S108, it is determined whether or not the verification of all the links within the search range has been completed. If it is determined that the verification has been completed, the process ends. Returning to S102, the process is repeated.

If it is determined in step S103 that the predetermined number of links are not stored in the storage table, the flow advances to step S109 to store the unconditionally selected link Ld in the table, and to step S107. .

By the above processing, the departure place (vehicle position),
At the waypoints and destinations, links that are candidates for the route search start point and end point are stored in the table at any time until a predetermined number is stored in the table, and the predetermined number is stored in the table. Thereafter, if there is a link with a distance value smaller than the link with the maximum distance value in the table, the link is replaced, and a plurality of links are selected and stored in the table in ascending order of the distance value. Then, at each of the selected start points, a route search is performed in step S4 of FIG. 12 described above. At each of a plurality of end points similarly selected, a route search is performed in step S5.
Next, in step S6, a route search using the level 4 route search data is performed between all the recommended routes searched in steps S4 and S5. In addition,
The recommended routes searched in steps S4 and S5 may be weighted, and a route search using level 4 route search data may be performed between a predetermined number of recommended routes. For example, on the start point side, the direction of the end point is preferentially adopted, and the top 25 lines with the lowest weighting (cumulative value such as distance cost) given to each route are considered. Can be The same applies to the end point side. If both the start point and the end point of the route search are included in the level 2 route search data read in order to execute step S4, the route search is completed with the level 2 route search data. Is not executed using the level 4 route search data. If it is predicted that the number of nodes between the recommended routes searched in steps S4 and S5 is small, a route search using the level 2 route search data is also performed in step S6.

As described above, even if the link selected as the start point or the end point of the route search has one-way traffic or other traffic restrictions and the route search cannot be performed, the next candidate link is selected and the route search is performed. Is performed. Therefore, the probability that the route search is finally impossible is reduced.

In the above processing, the link is selected on the basis of the distance value to the link. However, the link may be selected using a parameter other than the distance value, or may be selected in consideration of the parameter other than the distance value. For example, it is conceivable to preferentially select a road as large as possible (a road having a large width). Further, the distance value may be selected, for example, by weighting the distance value with, for example, traffic regulation information information, such as not selecting a link that is not allowed to pass in both directions.

-Reading out route search data when there is a stopover-Next, reading out of route search data when a route search is performed by setting a stopover between a departure place and a destination will be described.

FIG. 18 is a view for explaining the reading of route search data when there is one stopover point V between the departure point S and the destination point D. As described above, the route search data is prepared for level 2 and level 4 in the present embodiment. Level 4 data corresponds to wide area map data, and level 2 corresponds to more detailed map data than level 4. FIG. 18A conceptually shows that the set departure place S, transit point V, and destination D are located on the level 4 route search data. FIG.
(B) conceptually shows level 2 route search data near the departure point S, the waypoint V, and the destination D. Regarding R1 to R5 surrounded by dotted lines, the range in which the route search data is read from the map database device 8 is conceptually shown.

First, one mode of reading route search data and route search processing will be described with reference to FIG. FIG. 21 is a flowchart of a process of reading route search data and a route search process in a conventional device. Here, the description of the processing before and after the reading of the route search data and the route search processing is omitted.

First, a route search from the departure point S to the stopover point V is performed. Since the setting of the start point and the end point of the route search is as described above, the description is omitted here. Referring to FIG. 21, in step S401, level 2 route search data near the departure point S is read (R1). In step S402, a route search near the start point is performed using the departure point S as a start point of the route search, and a plurality of recommended route candidates are selected. In step S403, the waypoint V
Read the route search data of level 2 in the vicinity (R
2). In step S404, a route search near the end point is performed using the waypoint V as the end point of the route search, and a plurality of recommended route candidates are selected. In step S405, level 4 route search data including the departure point S and the waypoint V is read (R3). In step S406, a route search is performed between the above-described plurality of recommended route candidates, and a recommended route from the start point to the end point, that is, the recommended route from the departure point S to the stopover point V is calculated.

Next, a route search from the waypoint V to the destination D is performed. In step S407, the level 2 route search data near the waypoint V is read (R2). In step S408, a route search near the start point is performed using the waypoint V as a start point of the route search, and a plurality of recommended route candidates are selected. In step S409, the level 2 route search data near the destination D is read (R3). Step S410
Then, a route search near the end point is performed using the destination D as the end point of the route search, and a plurality of recommended route candidates are selected. In step S411, level 4 route search data including the waypoint V and the destination D is read (R5). In step S412, a route search is performed between the above-described plurality of recommended route candidates, and a recommended route from the start point to the end point, that is, the recommended route from the waypoint V to the destination D is calculated. As described above, a recommended route from the destination S to the destination V via the waypoint V is derived.

In one embodiment of the above-described route search data reading and route search processing, the order of access to the map database device 8 is as follows: R 1 → R 2 → R 4 → R 2 → R 3 → R
It becomes 5. Normally, when the route search data is stored in a CD-ROM or the like, it is stored collectively for each level. A buffer memory 9 is provided between the map database device and the control circuit. When accessing level 4 data after accessing level 2 data and then accessing level 2 data again, the buffer memory 9 is used. On 9, there is a high probability that the previous data in the vicinity of level 2 has been replaced with level 4 data, and the probability of hitting data in the buffer memory 9 decreases. Therefore, it is necessary to access the CD-ROM device or the magnetic recording device which involves a mechanical movement again, which causes a reduction in the speed of the reading process.

FIG. 19 is a flowchart in which the above problem is improved. In FIG. 19, in step S201, level 2 route search data near the starting point S is read (R1). In step S202, a route search near the start point is performed using the departure place S as a start point of the route search, and a plurality of recommended route candidates are selected. In step S203, level 2 route search data near the waypoint V is read (R
2). In step S204, a route search near the end point is performed using the waypoint V as the end point of the route search, and a plurality of recommended route candidates are selected. In step S205, level 2 route search data near the destination D is read (R3). In step S206, a route search near the end point is performed using the destination D as the end point of the route search, and a plurality of recommended route candidates are selected.

Next, in step S207, level 4 route search data including the departure point S and the waypoint V is read (R4). In step S208, the above-mentioned departure point S
A route search is performed between a plurality of recommended route candidates in the vicinity and near the waypoint V, and a recommended route from the start point to the end point, that is, the recommended route from the starting point S to the waypoint V is calculated. In step S209, the level 4 including the waypoint V and the destination D
Is read out (R5). Step S2
In step 10, a route search is performed between a plurality of recommended route candidates near the above-mentioned route V and around the destination D, and a recommended route from the start point to the end point, that is, the route from the route V to the destination D is calculated. As described above, a recommended route from the destination S to the destination V via the waypoint V is derived.

In the above-described improved processing, the order of access to the map database device 8 is as follows: R 1 → R 2 → R 3 → R 4
→ R5. Here, since all the level 2 route search data is read out first, and then the level 4 route search data is read out, for example, when the level 2 data is read out at R2, the data read out at R3 is also collected in the buffer. The probability of being read to the memory 9 is high,
Next, when the route search data near the destination D is read at R3, the probability of a hit on the buffer memory 9 increases. Also, since the read data at R4 and the read data at R5 both include the waypoint V, when the data is read at R4 and subsequently read at R5, the overlapping data portion is surely stored in the buffer memory 9. Hit on. Furthermore, in this processing flow, it is not necessary to read the data of the waypoint V twice, and the route search near the waypoint V only needs to be performed once, and the processing time can be reduced in these cases. It should be noted that a similar concept is used when a plurality of via values are set.

-Improving the apparent processing speed of the route search process-In the above description of the flowchart of FIG.
2. A description has been given of a case in which the route search process is continued after the destination and the like are set in step S3. In this case, for convenience of explanation, instructions by the operator and the like are omitted. However, when starting a route search, the operator usually sets a destination or the like, and then inputs a route search start instruction using the input device 3, and the program starts the route search according to the instruction. I do.

In this embodiment, the following processing is performed to increase the processing speed in this processing. FIG.
0 shows a flowchart of a route search process for apparently increasing the processing speed in the route search. Step S3
At 01, the operator sets a destination or a waypoint. Here, when one of the destination or the plurality of transit points is set, the process proceeds to the next step S302.
That is, the processing of steps S301 to S303 is repeated for each setting of one destination or waypoint. In step S302, a route search near the destination or waypoint set by the operator is started using the level 2 route search data, and the process proceeds to step S303 without waiting for the end of the route search process. In step S303, it is determined whether or not all the settings by the operator have been completed. If all the points have not been set yet, the process returns to step S301 and repeats the processing. If it is determined in step S303 that all the points have been set, the process proceeds to step S304, and waits for an instruction to start a route search by the operator. At this point, if the route search started in step S302 has not been completed, the processing is continued. Step S303 and step S304
Has been described in steps, but when the operator instructs the start of the route search, it can be regarded that the setting of all points has been completed.

In step S304, when an instruction to start a route search is given by the operator using the input device 3, the process proceeds to step S305. In step S305,
The current position detection device 1 detects the position of the own vehicle. In step S306, a route search near the own vehicle position is started using the level 2 route search data. The route search near the own vehicle position is started after the operator gives an instruction to start the route search, because the own vehicle position changes every moment. In step S307, it is determined whether or not the route search near the destination, the waypoint, and the own vehicle position has all been completed. If it is determined that all of the routes have been completed, the process proceeds to step S308, and among the plurality of recommended routes searched for the route near the destination, the waypoint, and the own vehicle position, the level 4
A route search is performed using the route search data of. In addition,
When the own vehicle position exists in the result of the route search near the destination using the level 2 route search data, the route search using the level 4 route search data is not performed. The route search is completed by the route search data of No. 2. This means that if a stopover is set,
The same applies to between a destination and a waypoint, between a waypoint and the next waypoint, and between a waypoint and a destination.

In the above description, the position of the own vehicle detected by the current position detection device 1 is set as the departure point. However, in step S301, the operator sets the departure position using the input device 3 in the same manner as the destination and the waypoint. You may make it. At that time, a route search near the departure place set in step S302 is performed.

In this way, after the operator has set the destination and the like, the route search processing is advanced in advance by utilizing the idle time until the operator instructs the start of the route search. Therefore, the time from when the operator actually issues a route search instruction to when the route search is completed is reduced. In this processing, parallel processing, such as starting a route search for a destination or a waypoint and simultaneously monitoring the operation of the operator, is realized by performing a multitask program processing. If the operator changes the destination or stopover after starting the process in advance of the route search, the already started process is stopped, and if the result of the process is already available, the result is discarded. do it. Note that the same concept is applied to a case where a plurality of via values are set.

[0059]

As described above, the route search device of the first aspect performs the first to third reading of the first interlink connection information and the fourth reading of the second interlink connection information. Since the reading and the fifth reading are performed before the reading and the reading of the first inter-link connection information and the reading of the second inter-link connection information are not mixed,
Data can be read efficiently. In the route search device according to the second aspect, the first reading, the second reading, the third reading, the fourth reading, and the fifth reading are performed in this order, so that the first inter-link connection is performed. In the information and the second link-to-link connection information, the data can be read efficiently when the data is arranged in the order from the departure point to the destination via the waypoint. Since the route search device according to the third aspect commonly uses the route search result near the waypoint, there is no need to read the route search data near the waypoint and perform the route search process redundantly. In addition, the processing time can be reduced. Since the route search device according to the fourth aspect can set a plurality of transit points, it is possible to search for a route between the transit points while obtaining the same effect as in the first aspect. According to the route search device of the fifth aspect, the same effects as those of the second aspect can be obtained even when a plurality of transit points are set. The route search device according to the sixth aspect can efficiently read data when a CD-ROM device and a buffer memory are provided. The route search device according to the seventh aspect can efficiently read data when the magnetic disk device and the buffer memory are provided.

[Brief description of the drawings]

FIG. 1 is a block diagram of an embodiment of an in-vehicle navigation device according to the present invention.

FIG. 2 is a diagram showing an example in which two roads intersect in a mesh area;

FIG. 3 is a diagram showing a configuration of road map display data.

FIG. 4 is a diagram showing an example of a road map having a plurality of nodes and interpolation points;

FIG. 5 is a diagram showing link string data of a thick road in FIG. 5;

FIG. 6 is a diagram showing an example of attribute 1 + X coordinate data.

FIG. 7 is a diagram showing an example of attribute 2 + Y coordinate data.

FIG. 8 is a diagram for explaining link numbers of route search data.

FIG. 9 is a diagram showing a data configuration of route search data.

FIG. 10 is a diagram showing an outline of a data configuration of recommended route data.

FIG. 11 is a detailed diagram of a data configuration of node information and link information of recommended route data.

FIG. 12 is a flowchart showing an outline of a main process performed by a control circuit;

FIG. 13 is a flowchart following FIG. 12;

FIG. 14 is a diagram illustrating a case where a start point of a route search is set.

FIG. 15 is a diagram for explaining a case where an end point of a route search is set.

FIG. 16 is a diagram for explaining a case where a stopover is set between the own vehicle position and the destination;

FIG. 17 is a flowchart showing a multiple link selection process.

FIG. 18 is a diagram illustrating reading of route search data.

FIG. 19 is a flowchart of readout of route search data and route search processing.

FIG. 20 is a flowchart of a route search process for increasing the apparent processing speed of the route search.

FIG. 21 is a flowchart of readout of route search data and route search processing;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Current location detection device 2 Control circuit 3 Input device 4 DRAM 5 Image memory 6 Display device 7 Map database device 8 SRAM 9 Buffer memory

Claims (7)

[Claims] 1. A map in which a minimum unit of a road on a map is a link, position information of the link, first link connection information corresponding to a map of a predetermined scale, and a map wider than the predetermined map. Storage means for storing corresponding second link-to-link connection information; point setting means for setting a departure point, a waypoint, and a destination; Control means for performing a route search, the control means comprising: (a) a first reading for reading first link-to-link connection information near a set departure point; A second reading for reading the first inter-link connection information in the vicinity;
Performing a third reading of reading the first inter-link connection information in the vicinity of the set destination, and reading a second inter-link connection information in a range including the set departure place and transit point; And (b) performing a fifth read for reading the second link connection information in a range including the set transit point and the destination, and (b) reading the first link near the departure place. Performing a route search near the departure place based on the connection information; (c) performing a route search near the stopover based on the read connection information between the first links near the stopover; Performing a route search in the vicinity of the destination based on the read first inter-link connection information in the vicinity of the destination; and (e) a route search result in the vicinity of the departure place and a route search result in the vicinity of the waypoint. The read departure point and via Performing a route search from the departure place to the stopover based on the second link connection information in a range including the ground, and (f) a route search result near the stopover and a route search result near the destination, and A route search is performed from the via point to the destination based on the read out via point and the second inter-link connection information including the destination, and (g) the first to third readings. Is
A route search device, wherein the search is performed prior to the fourth reading and the fifth reading. 2. The route search device according to claim 1, wherein the control unit is configured to control the first read, the second read, the third read, the fourth read, and the fifth read. A route search device that sequentially reads data. 3. The route search device according to claim 1, wherein the control means is read by the second read in a route search from a departure place to a stopover and a route search from a stopover to a destination. A route search device that commonly uses a route search result near a waypoint that has been searched based on the first inter-link connection information near the waypoint. 4. The route search device according to claim 1, wherein said point setting means is capable of setting a plurality of transit points, and said control means is adapted to set a plurality of transit points in a range including said plurality of transit points. A sixth read for reading the second inter-link connection information is performed, and based on the route search results near the plurality of transit points and the read second inter-link connection information in the range including the plurality of transit points. A route search between transit points, wherein the first to third readings are performed prior to the sixth reading. 5. The route search device according to claim 4, wherein said control means includes: said first read, said second read, said third read, said fourth read, said sixth read, A route search device that performs reading in the order of the fifth reading. 6. The route search device according to claim 1, wherein said storage means is a CD-ROM device, and said control means includes a buffer memory. . 7. The route search device according to claim 1, wherein the storage unit is a magnetic disk device, and the control unit includes a buffer memory.