JPH05323870A - Course searching method - Google Patents

Abstract

PURPOSE:To make a search by using an intersection network so that a guide course includes a U-turn course. CONSTITUTION:An optimum course search part 15g finds a 1st optimum course connecting an upper-layer start point and an end point, which are the closest to a starting point and a destination and present on a freeway or national road in an upper layer, and the starting point and upper-layer start point and a 2nd optimum course connecting the upper-layer end point and the destination by Dijksta method by using an intersection network list regarding a small-scale lower-layer map in a course search memory 15h, and then finds a 3rd optimum course connecting the upper-layer start point and upper-layer end point by the Dijksta method by using an intersection network list regarding an large-scale upper-layer map; when the upper-layer start point or upper-layer end point is not a dummy intersection based upon the upper-layer road data, an upper- layer intersection network list regarding the dummy intersection is previously added and the 1st course, 3rd course, and 2nd course are connected in order to obtain the optimum course connecting the starting point and destination.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a route searching method, and more particularly to a route searching method for searching an optimum route connecting a starting point to a destination by using a Dijkstra method using an intersection netlist.

[0002]

2. Description of the Related Art An in-vehicle navigator has a mass storage device such as a CD-ROM for storing a large amount of map data, a display device, and a vehicle position detection device for detecting the current position of a vehicle. CD-R corresponding map data
The map is read from the OM, the map is drawn on the display screen based on the map data, the vehicle position mark (location cursor) is fixed at a fixed position (for example, the center of the screen) on the display screen, and the map is scrolled according to the movement of the vehicle. By displaying or fixing the map on the screen and moving and displaying the vehicle position mark, it is possible to see at a glance where the vehicle is currently traveling.

The map stored in the CD-ROM is divided into map sheets of a longitude width and latitude width of an appropriate size according to the scale level, and roads and the like are vertices (nodes) expressed in latitude and longitude. , Which is represented by a coordinate set of, and these drawing is performed by connecting the nodes in order with straight lines. It should be noted that a road is composed of two or more nodes, and a part connecting two nodes is called a link. As shown in FIG. 19, the map data is divided into four data units (4
Each data sheet corresponds to one screen. The map data includes (1) a road layer including a road list, a node table, an intersection node list, and an adjacent node list, (2) a background layer for displaying roads, buildings, rivers, etc. on the map screen,
(3) It is composed of a character layer for displaying the names of cities, towns and villages, road names, and the like.

Of these, the road layer has the structure shown in FIG. The road list RDLT is classified by road into road types (highways, national roads, and other roads), the total number of nodes that make up the road, and a node table N of nodes that make up the road.
It is composed of data such as the position on the DTB and the width to the next node. Intersection node list CRLT
Is a set of positions on the node table NDTB of the other end node of the link (referred to as an intersection composing node) for each intersection on the map. Adjacent node list N
In the case of an adjacent node that is defined by a unit boundary and is shared by multiple units on a road whose node spans multiple units (see FIG. 21), the NLT determines the number of units shared by other units except its own unit. The number of adjacent nodes shown (for the adjacent node RN defined by the unit AU ₁ (AU ₂ ) in FIG. 21 (1), the other shared unit is AU _2).
(AU ₁ ), the number of adjacent nodes is 1, and
Regarding the adjacent node RN defined in the unit AU ₁₁ in (2), the other shared units are AU ₁₂ , A ₂₁ , and A ₂₂ , so the number of adjacent nodes is 3), the figure leaf number, and the figure leaf. It is composed of the unit code to which the adjacent node belongs and the position on the node table in the unit. The node table NDTB is a list of all nodes on the map,
Coordinate information (longitude, latitude) for each node, an intersection identification flag indicating whether or not the node is an intersection, if it is an intersection, points to a position on the intersection constituent node list, and if not, the node on the road list Is composed of a pointer indicating the position of the road to which the node belongs, an adjacent node identification flag indicating whether or not the node is an adjacent node, and a pointer indicating the position in the adjacent node list NNLT if the node is an adjacent node.

By the way, the in-vehicle navigator has a route guidance function of searching an optimum route from the starting point to the destination point, for example, tracing the shortest distance and displaying the guidance route on the screen to guide the driver to travel. When driving, the driver's purpose is to distinguish the road from other roads by displaying the guide route in a bold color, or to display a guide mark that moves along the guide route in front of the vehicle position mark. The ground is easily reachable.

A method utilizing the Dijkstra method has been proposed as a method for obtaining an optimum route from a starting point to a destination point. The general method of this method is to refer to road data and refer to all intersections existing in one or a plurality of adjacent quadrants (including originally a square area having a straight line connecting a starting point and a destination as diagonal lines). In addition to the intersections, the intersection netlist CRNL is created for each intersection, and stored in the route search memory. The shortest route to is searched by referring to the intersection netlist.

The intersection netlist CRNL includes (1) intersection sequential number (information for identifying the intersection) for each intersection (including intersection nodes and simple nodes that are adjacent nodes). 2) Map leaf number of the map including the intersection (3) Data unit code (4) Position on the node table (5) Longitude (6) Latitude and above, intersection ID (7) Position on intersection constituent node list (the intersection Is an original intersection node) (8) Number of intersection constituent nodes (same as above) (9) Position on adjacent node list (when the intersection is an adjacent node) (10) Number of adjacent nodes (same as above) (11) Each adjacent Sequential number of intersection (12) Distance to each adjacent intersection (13) Attribute of road to each adjacent intersection (road type, width) (14) One before the intersection sequential number (15) total distance from the departure point to the intersection (16) Search degree or the like of the intersection are registered (where (14) -
(16) is registered when the route search is executed).

First, as shown in FIG. 22, the method for creating the intersection netlist CRNL is as follows: From the map leaf management information of the map data, for each map leaf including a rectangular area having a straight line connecting the starting point and the destination as a diagonal line. Get the leaf number. Then, from these map data, the road data for each of the four divided map leaves (AU ₁₁ to AU _{44 in} FIG. 22) including a rectangular area whose diagonal line is a straight line connecting the starting point and the destination is input from these map leaves. However, each four-division diagram leaf is specified by the diagram leaf number and the data unit code. From the node table NDTB, an intersection node with an intersection identification flag set and a simple node with the intersection identification flag turned off are adjacent to each other. An adjacent node with a node identification flag is searched for, an intersection net list with sequential numbers (1) is prepared in the route search memory, and the intersection IDs are registered ((2) to (6)). .. Then, the node table NDT
B, the position on the intersection constituent node list, the number of intersection constituent nodes, the position on the adjacent node list, the number of adjacent nodes are obtained from the intersection constituent node list CRDT and the adjacent node list NNLT, and (7) to (10) are registered. To do. Next, for each road in the road list RDLT, the node table ND
By referring to TB, the distance of the link between adjacent intersections (including the case where one is an adjacent node of a simple node) and the attributes (road type, width) of the link are obtained, and the intersection of one of the links is determined. In the intersection netlist, the other intersection of the link is set as an adjacent intersection, and the intersection sequential number (adjacent intersection sequential number) registered in the intersection net list of the adjacent intersection, the distance and the attribute of the link are registered ( (11)-(13)). If the target for which the intersection netlist is created also serves as an adjacent node at the intersection node, and if the target for which the intersection netlist is created is an adjacent node of a simple node, the same adjacent node is shared by other nodes. Since an intersection netlist may be created under a unit, the adjacent node list NNLT is referenced to find the intersection sequential numbers of all other shared units, and the adjacent netlist is searched for The intersection sequential number and distance are registered, and adjacent node connection processing is performed. At this time, the distance is 0.

In this way, the intersection netlist CR
When the NL is completed, the optimum route search process is performed by the Dijkstra method based on the departure point data and the destination data. FIG. 23 is a schematic explanatory diagram of the Dijkstra method. A road is a straight line, and intersections (including adjacent nodes at simple nodes) are graphed as intersections of straight lines. The distances between the intersections are known, and STP is Origin (intersection), DSP is destination (intersection).

In the Dijkstra method, the 0th-order intersection is set as the 0th-order intersection (degree 0 is registered in (16) of the intersection netlist related to the starting-point intersection) with reference to the intersection netlist CRNL. Search for adjacent primary intersections A _{1 to} A ₄ along the road, and for each primary intersection A _{1 to} A ₄ , the corresponding previous intersection (an intersection of one lower order. determine the total distance from the starting point that has passed through the itself), each intersection a ₁ ~
Corresponding to A ₄ , 1 in each intersection netlist
Intersection sequential number that identifies the previous intersection,
It is registered together with the search order 1 ((14) to (16) in the intersection net list). Then, each primary intersection A ₁ -A
Find the secondary intersection B _ij for ₄ and for each secondary intersection, find the cumulative distance from the departure point via the corresponding preceding primary intersection, and make it correspond to each intersection B _ij It is registered in the list together with the intersection sequential number that specifies the previous intersection and the search order 2. For example, for the primary intersection A ₁ , three secondary intersections B ₁₁ , B ₁₂ , and B ₁₃ are found, and corresponding to each of these intersections, B ₁₁ : Cumulative distance from the departure point via the primary intersection A _1. Bd ₁₁ B ₁₂ : Cumulative distance from departure point via primary intersection A ₁ Bd ₁₂ B ₁₃ : Cumulative distance from departure point via primary intersection A ₁ Bd ₁₃ ··· (a) corresponds to intersection A Memorize with the intersection sequential number of ₁ . Further, three secondary intersections B ₂₁ , B ₂₂ , and B ₂₃ are obtained for the primary intersection A ₂ , and each secondary intersection B is obtained.
Corresponding to ₂₁ , B ₂₂ , and B ₂₃ , B ₂₁ : Cumulative distance from departure point via primary intersection A ₂ Bd ₂₁ ··· (b) B ₂₂ : From departure point via primary intersection A ₂ Cumulative distance Bd ₂₂ B ₂₃ : The cumulative distance Bd ₂₃ from the departure point via the primary intersection A _{2 is} stored together with the intersection sequential number of the corresponding intersection A ₂ . Similarly, for other primary intersections A ₃ and A ₄ , adjacent secondary intersections are searched for and predetermined data are stored. By the way, the intersections B ₁₃ and B ₂₁ are the same intersection. In this way, the intersections that should store data overlap,
When the accumulated distance data for different routes has already been stored for the intersection, the accumulated distances Bd ₁₃ and Bd ₂₁ from the departure place are compared, and the smaller distance data is rewritten and stored. For example, if Bd ₁₃ > Bd ₂₁ , the intersection netlist of the intersection B ₁₃ (= B ₂₁ ) has the final sequential number of the intersection A ₂ corresponding to the cumulative distance Bd ₂₁ shown in (b). Be remembered.

Thereafter, similarly, the adjacent tertiary intersection C _ij is obtained for each secondary intersection B _ij , and for each intersection C _ij , the cumulative distance from the departure point via the corresponding _preceding intersection is obtained. , The intersection number of the preceding intersection is stored, and generally, the (i + 1) th intersection is obtained for each i-th intersection with reference to the intersection netlist, and the corresponding 1 is obtained for each (i + 1) th intersection.
If the cumulative distance from the departure point via the i-th intersection before this one is obtained, and it is stored in the intersection netlist of the (i + 1) -th intersection with the intersection sequential number of the previous intersection, the final Destination (intersection)
Reach the DSP.

When the destination DSP is reached, the destination (m
(M−1) th intersection stored in the intersection netlist in association with the next intersection, and stored in the intersection netlist in association with the (m−1) th intersection (m−). 2) Next intersection ... The primary intersection stored in the intersection netlist in association with the secondary intersection, and the 0th intersection stored in the intersection netlist in association with the primary intersection. The shortest optimum route is a route connecting (departure place) in order from the 0th intersection side toward the destination side.

The intersection netlist CRNL is created in the vehicle-mounted navigator from the road data not including the intersection netlist stored in the CD-ROM as described above, and expanded together with the road list, the intersection netlist and the like. It may be prepared as a part of the road data, or may be stored in advance in a CD-ROM as a part of the road data (road layer). Further, even if the route search is advanced from the destination intersection to the departure intersection, the optimum route can be similarly obtained. As described above, according to the Dijkstra method, the optimum route can be obtained by using the shortest distance as an index in graph theory. Therefore, the optimum route can be displayed together with the vehicle position mark in the map image on the screen, and the driver can be guided to the desired destination.

By the way, in the search for the optimum route, the use of a small-scaled map leaf (enlarged map) gives a narrower node interval and more accurate route data can be obtained.
When the departure point and the destination are relatively close, the total number of intersection netlists required for route search is relatively small, the memory required for route search is not so large, and the time required for route search is also short. However, if the starting point and the destination are far away,
The required total number of intersection netlists is large, an extremely large capacity is required for the route search memory, and the time required for route search becomes long, so that a long waiting time is required until the optimum route is obtained. Furthermore, when creating an intersection netlist from road data, using a small-scale map leaf,
It takes a lot of time to create.

Therefore, conventionally, when the starting point and the destination are relatively distant from each other, as shown in FIG. 24, a straight line connecting the starting point STP and the destination DSP is defined as a diagonal line in the upper layer of a large scale leaf. 1 or a plurality of adjacent 4 including a rectangular area
From the road data related to the divided map leaf (shown as four 4-divided map leaves of AU _{11 to} AU _{22 in} FIG. 24) (in the case of a large-scale map leaf, only main roads such as highways and national roads are included),
The intersection closest to the departure point (here, SA on National Road RD _a
And the intersection closest to the destination (here National Road R
Find DA on D _b ), and set SA to the upper origin intersection,
DA is set as the upper-level end point intersection. Then, by using the intersection netlist created from the road data of the upper-layer map leaf or included in the road data, the optimum route connecting the upper-layer start intersection SA and the upper-layer end intersection DA is searched by the Dijkstra method, and the first route And

[0016] Next, in the small-scale map leaf of the lower layer (in the small-scale map leaf, in addition to the main road, prefectural roads and city roads are also included), the original departure place ( Departure point intersection) STP and the above-mentioned upper-layer starting point intersection SA including a square area having a diagonal line as a straight line, or a plurality of adjacent four-division diagrams (in FIG. 24, four quadrants of BU _{11 to} BU ₂₂ ) The second route is searched by the Dijkstra method for an optimal route connecting the departure point intersection STP and the upper-layer origin intersection SA by using the intersection netlist created from the road data according to (as a leaf) or included in the road data. And Furthermore, in the lower-layer map leaf having a small scale, one or adjacent square regions having a diagonal line as a straight line connecting the original destination (destination intersection in the lower-layer map leaf) DSP and the above-mentioned upper-layer end point intersection DA. A plurality of quadrants (CU in FIG. 24)
₁₁ created from the road data relating to a) as the four quadrant diagram leaves to CU _22, or the optimal route using the intersection network list included in the road data, connecting the upper end point intersection DA and destination intersection DSP Is searched by the Dijkstra method and is set as the third route. Finally, by connecting the second route data, the first route data, and the third route data in order, the final guidance of a series of connections from the departure point (departure intersection) STP to the destination (destination intersection) DSP. The route data is completed.

As described above, since the intersection netlist relating to the upper layer is used between the upper layer starting point and the upper layer ending point,
The required total number of intersection netlists is much smaller than that using the lower layer leaf, the capacity load of the route search memory is reduced, and the time required for route search is short. In addition, when an intersection netlist is created from road data, the creation time can be greatly shortened.

[0018]

However, in the above-mentioned conventional technique, the upper-layer starting point intersection SA does not take into consideration road data including fine roads such as prefectural roads and city roads in the lower layer, Since it is obtained only from the road data of the main roads such as national roads and highways, as shown in FIG. 24, when going from the departure point STP to the national road RD _a when seen in the lower layer, the area closer to the destination from the upper origin intersection SA Even if there is an intersection SA ′ (intersection in the lower layer), since the intersection SA ′ does not constitute an intersection in the upper layer, the upper-layer starting point intersection SA is SA ′.
It may be a point farther from the destination different from. At this time, as a result of an optimal route search connecting the starting point intersection STP to the upper layer starting point intersection SA in the lower layer, the second route may be STP → SA ′ → SA. In such a case, the starting point STP is changed to the destination. The overall guide route connecting the DSPs is STP → SA ′ → SA → SA ′ →
DA → DSP, U-turn path is included in part,
In some cases, it became an inappropriate route as the shortest route.

Similarly, for the upper-layer end point intersection DA,
As shown in Fig. 24, the road data including fine roads such as prefectural roads and city roads in the lower layer is not considered at all, and only the road data of the main roads such as national roads and highways in the upper layer are obtained. Even when there is an intersection DA ′ (an intersection in the lower layer) closer to the starting point than the ending point DA in the upper layer when heading toward the destination DSP from the national highway RD _b when seen in the lower layer, the intersection D
Since A'does not form an intersection in the upper layer, the upper layer end point intersection DA may be different from DA 'and may be a point farther from the starting point. At this time, as a result of performing an optimum route search in the lower layer from the upper-layer end point intersection DA to the destination intersection DSP, the third route is DA → DA ′ → DSP.
In such a case, the overall guidance route connecting the departure point STP to the destination DSP is STP → DA ′ →
In some cases, DA → DA ′ → DSP, so that the U-turn route is included in part, and the route becomes inappropriate as the shortest route.

From the above, it is an object of the present invention to provide a route search method in which a U-turn route is not included in a final guide route.

[0021]

In the present invention, the above problem is solved by using the lower road data relating to a lower scale leaf having a small scale to determine the start point and the destination respectively in the nodes forming the lower road. On the other hand, the node on the same road as the upper road that is located at the nearest position and is represented by the upper road data relating to the large scale upper leaf is the upper layer start point and the upper layer end point, and is the best connection from the starting point to the upper layer start point. Means for obtaining an optimum second route connecting the first route and the upper layer end point to the destination, and when the upper layer start point or upper layer end point is not an intersection in the upper layer road data, the upper layer start point or upper layer end point is set as the upper layer road data. As a pseudo intersection in the above, using a means for including the intersection netlist related to the pseudo intersection in advance in the road data of the upper layer, and the road data of the upper layer,
A means for obtaining an optimum third route connecting the upper layer start point to the upper layer end point by the Dijkstra method, and these optimal first route, third route, and second route are connected in order to connect the starting point to the destination. This is achieved by providing means for making an optimal route for connection.

[0022]

According to the present invention, by using the lower road data related to the lower-layer map leaf having a small scale, the nodes existing in the nodes forming the lower road are located at the positions closest to the starting point and the destination, respectively, and the scale is reduced. , The optimal first route connecting the starting point to the upper layer starting point and the upper layer ending point with the node on the same road as the road expressed by the upper layer road data related to the large upper layer map leaf as the upper layer starting point and the upper layer ending point The optimal second that connects to the ground
While determining the route, the uppermost road data is used to find the optimum third route connecting the upper layer starting point to the upper layer ending point by the Dijkstra method, and when the upper layer starting point or the upper layer ending point is not an intersection in the upper layer road data. Uses the upper layer start point or the upper layer end point as a pseudo intersection in the upper layer road data, and previously includes an intersection netlist related to the pseudo intersection in the upper layer road data, and obtains the optimum first The route, the third route, and the second route are connected in order to make an optimum route connecting the starting point to the destination. As a result, the optimal route connecting the departure point to the upper layer start point and the optimal route connecting the upper layer end point to the destination do not include the roads defined in the upper layer road data. Since it is possible to prevent the U-turn route from entering the entire optimum route route connecting the vehicle to the destination, it is possible to obtain an appropriate guide route.

[0023]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Overall Configuration FIG. 1 is an overall configuration diagram of an in-vehicle navigator embodying the route search method of the present invention. In the figure, 11 is a CD-ROM (map information storage unit) for storing map data. The map data is composed of a road layer, a background layer, a character layer, and the like. Reference numeral 12 is a display device (CRT) that draws a map image and a vehicle position mark according to the current position of the vehicle, a guide route searched by the optimum route search, and 13 is a vehicle based on the traveling distance and the direction of the traveling vehicle. Is a vehicle position detection unit that calculates the current position of the vehicle. The vehicle position detector 13
Although not shown, it has a direction sensor for detecting the traveling direction of the vehicle, a distance sensor for detecting the traveling distance, and a position calculation CPU for calculating the current position (longitude, latitude) of the vehicle based on the direction and the traveling distance. ..

Reference numeral 14 is an operation unit equipped with a map search key, an enlargement / reduction key, a map scroll key, a route guidance mode key, a start key, and the like, and 15 is a map display control device. The map image is generated, and the vehicle position mark and the guide route image are generated.

In the map display control device 15, 15a reads out map data (for example, 9 screens of map data) in a range wider than the screen display range around the present location from the CD-ROM 11 based on the vehicle position data, and temporarily stores it in the buffer memory. And a map image drawing unit for generating a dot image map image based on the map data. When the enlargement key is pressed by the operation unit 14 while the map image is displayed based on the map data relating to the upper layer map leaf having a large scale, the map image drawing unit 15a displays the map data relating to the lower layer map leaf from the CD-ROM 11. The read operation is performed to generate an enlarged map image, and conversely, while the map image is being displayed, the operation unit 14
When the reduction key is pressed with, the map image drawing unit 15a displays C
The map data relating to the upper layer map leaf is read from the D-ROM 11 to generate a reduced map image.

Reference numeral 15b is a buffer memory for temporarily storing the map data read from the CD-ROM 11, and 15c is a guide route image generated based on the guide route data from the starting point to the destination obtained by the optimum route searching process. The guide route drawing unit 15d is a video RAM for storing the map image and the guide route image. The map image drawing unit 15a rewrites the video RAM 15d at any time as the vehicle runs so that the display range of the display screen does not exceed the image range of the video RAM 15d, and the guide route drawing unit 15a
c also generates a guide route image according to the traveling of the vehicle and stores it in the video RAM 15d.

Reference numeral 15e is a read-out control unit for reading out one screen of map image from the video RAM 15d so that the current position of the vehicle is located at the center of the display screen, and the read-out position is designated by the map image drawing unit 15a. 15
f is a vehicle position mark generation unit for displaying a vehicle position mark at the center of the display screen, 15g is an optimum route search unit, and during normal driving that is not in the route guidance mode,
Predetermined lower-level four-divided map with small scale (Here, in addition to expressways and national roads, it is assumed that small roads such as prefectural roads and city roads are also included.) A lower layer intersection netlist for one leaf and eight four-divided map leaves surrounding the four-divided map leaf is created and updated and stored in the route search memory, and the destination is input in the route guidance mode. If the current vehicle position (departure point) and the destination are relatively close to each other, create the required lower-layer intersection netlist, store it in the route search memory, and then start by the Dijkstra method only in the lower layer. The optimum route (shortest route) that connects the ground to the destination is calculated (here, simple node interpolation is also performed).

In contrast to this, when the destination is input in the route guidance mode, if the own vehicle position (departure point) and the destination are relatively far at that time, the optimum route search unit 15g displays the lower four-division diagram. In the leaves, one 4-divided map leaf including a destination and a lower-layer intersection netlist for eight 4-divided map leaves surrounding the map leaf are created and additionally stored in the route search memory. Large-scaled, upper 4-part map leaf (here, only expressways and national roads are included)
, Create an upper-level intersection netlist for one or more adjacent four-divided map leaves that include a rectangular area whose diagonal line is a straight line connecting the starting point and the destination, and additionally store it in the route search memory. Let If the upper layer start point or upper layer end point is not an intersection on an upper layer road, the upper layer start point or upper layer end point is set as a pseudo intersection in the upper layer road data, and an intersection netlist related to the pseudo intersection node is separately created. And additionally stored in the route search memory.

The optimum route searching unit 15g uses the intersection netlist of the lower layer and exists at the position closest to the starting point and the destination among the nodes constituting the road of the lower layer and has a large scale. A node on the same road as the road represented by the upper-layer road data related to the map leaf is set as the upper-layer starting point and the upper-layer ending point, and the optimum first route connecting the starting point to the upper-layer starting point and the upper-layer starting point and the upper-layer ending point The optimum second route connecting to the ground and the upper layer end point are obtained by the Dijkstra method, while the optimal third route connecting the upper layer start point to the upper layer end point is obtained by the Dijkstra method using the intersection netlist of the upper layer. Finally, the optimum first route, the third route, and the second route are connected in order to form a final optimal route connecting the starting point to the destination (simple node interpolation is also performed here).

Reference numeral 15h is a route search memory which is connected to the optimum route search unit and stores road data such as intersection netlists, and the data is backed up even after the power supply of the vehicle-mounted navigator is turned off together with the guide route storage unit. It is supposed to be done. This data backup is performed by battery backup when the storage element is a volatile memory such as DRAM. In addition, the storage element is EEPRO
By using a rewritable ROM such as M, data backup can be performed. Reference numeral 15i is a guide route storage unit that stores, as guide route data, a node sequence that forms an optimum route from a starting point to a destination.

Reference numeral 15j is a synthesizing section, which is a video RAM 15
d, the map image, the guide route image, and the vehicle position mark image respectively read from the vehicle position mark generating unit 15f are combined and output to the display device 12 for image display.

The map stored in the map data CD-ROM is divided into map sheets of a longitude width and latitude width of appropriate sizes according to the scale level, but here, for simplicity, the scale level is , 2 types of large and small are prepared. Map data of each leaf is
It is divided into four data units corresponding to one screen (each of four divided map leaves) (see FIG. 19), and in the map data, roads and the like are a coordinate set of vertices (nodes) expressed in latitude and longitude. As shown, these plots are made by connecting each node in turn with a straight line. It should be noted that a road is composed of two or more nodes, and a part connecting two nodes is called a link. The map data includes (1) a road layer including a road list, a node table, an intersection node list, and an adjacent intersection list, (2) a background layer for displaying roads, buildings, rivers, etc. on the map screen, ( 3)
It is composed of character layers for displaying the names of cities, towns and villages, road names, and the like. Of these, the road layer has the same data structure as in FIG. 20, and the road list RDL
T, intersection configuration node list CRLT, node table NDTB, adjacent node list NNLT, and the like.

The intersection network list C of the intersection network list optimal route search unit 15g to create
The RNL is configured as shown in FIG. 2, and is an original intersection (intersection node (regardless of whether it is an adjacent node or not)) and an adjacent node among simple nodes. (1) Intersection sequential number (information for identifying the intersection) (2) Map leaf number of the map including the intersection (3) Data unit code (4) Position on node table (5) Longitude (6) Latitude or more, intersection ID (7) Position on intersection node list (8) Number of intersection nodes (9) Position on adjacent node list (10) Number of adjacent nodes (11) Upper node presence flag / upper layer Road identification data /
Upper layer intersection Sequential number (12) Sequential number of each adjacent intersection (13) Distance to each adjacent intersection (14) Attribute of road to each adjacent intersection (road type, width) (15) Intersection immediately before the intersection Sequential number (16) Cumulative distance from the departure place to the intersection (17) The search order of the intersection is registered (however, (15) ~
(17) is registered when the route search is executed).

Items other than (11) when compared with the prior art
Are the same. (11) is entirely represented by 2 bytes
However, among them, MSB is an upper layer node existence flag, 2SB to 4S
B is upper road identification data, 5SB to LSB are upper intersections
It is a sequential number. The upper node existence flag is
As shown in FIG. 3, the intersection netlist has a small scale.
When the target is the lower layer leaf B, the lower layer
Intersection CP at_B1(A simple node becomes an adjacent node
(Including the case where there is a road)
₁However, it is represented by road data, and the intersection CP
_B1There is an intersection CP at the upper level_A(Of simple nodes, adjacent nodes
(Including the case of)
"1" is set, otherwise it is set to "0" (Fig.
CP of 3 _B2, CP_B3in the case of). On the other hand, the upper level intersection seek
The number of the relevant intersection netlist is small.
If you are targeting a lower layer
For the same intersection as the
If a strike has been created, the intersection seek at the upper layer
The serial number is registered.

The upper road identification data indicates whether or not the intersection is on the same road as the road included in the road data of the upper layer when the intersection netlist is intended for the lower layer of the small scale map. Used as data to represent, when 2SB to 4SB is “000”, it indicates that it is an intersection on the same road as the road included in the upper road data (in the case of CP _B1 and CP _{B2 in} FIG. 3), “111” Indicates that it is not an intersection on the same road as the road included in the upper road data (in the case of CP _B3 in FIG. 3). In addition,
The data of the item (11) is meaningless in the intersection netlist created for the upper layer map leaf.

4 to 13 are flow charts showing the processing of the map display control device 15, FIG. 14 is an explanatory diagram of a method for creating a lower intersection netlist around the vehicle position, and FIG. FIG. 16 is an explanatory diagram of a route search by the Dijkstra method in the case of closeness, FIG. 16 is an explanatory diagram of the route search method of the present invention, and FIGS. Yes, and will be described below with reference to these figures.

When the power of the vehicle-mounted navigator is turned on in the normal guidance mode , the map display control device 15 reproduces the map image display state immediately before the power was turned off last time (step 101 in FIG. 4). Here, assuming that the normal guide mode is reproduced by using the upper-layer map sheet having a large scale, the map image drawing unit 15a first starts the CD-RO.
The CD-RO is read out from the M11 by reading the drawing-leaf management information into the buffer memory 15b and referring to the drawing-leaf management information.
The map data relating to a plurality of upper-layer leaves around the position of the own vehicle, which is large in scale from M11, is read into the buffer memory 15b, and a map image of an area for nine screens including the position of the own vehicle is drawn in the video RAM 15d. Detection unit 13
Based on the vehicle position data input from, the read control unit 15e cuts out a one-screen map image centered on the vehicle position from the video RAM 15d and outputs it to the synthesizing unit 15j. The vehicle position mark generation unit 15f also generates a predetermined vehicle position mark in the direction indicated by the vehicle direction data detected by the vehicle position detection unit 13 and outputs it to the synthesis unit 15j. The synthesizing unit 15j synthesizes the vehicle position mark on the map image, outputs it to the display device 12, and displays it on the screen. As a result, the map image around the vehicle position is displayed on the screen together with the vehicle position mark.

When the power was turned off last time, if it was in the route guidance mode, the power is turned on and then the route guidance mode is set. Based on the vehicle position data, the route drawing unit 15c selects a portion within the area drawn in the video RAM 15d from the guide route data stored in the guide route storage unit 15i, and the video RAM 1
5d is drawn by emphasizing the guide route with a predetermined color and thickly. As a result, the map image around the vehicle position is displayed on the screen together with the vehicle position mark and the optimum guide route connecting the departure point to the intersection.

The map display control device 15 checks whether it is in the normal guidance mode (step 102). If YES, the optimum route search unit 15g uses the lower-layer drawing leaf of a small scale in the route search memory 15h. It is checked whether or not the lower-level intersection netlist has been created for each of the four 4-division leaf including the vehicle position and the eight 4-division leaf surrounding the 4-division leaf (step 103). When NO, the optimum route searching unit 15g refers to the map leaf management information in the buffer memory 15b and uses the vehicle position data to enclose one four-divided map leaf including the own-vehicle position of the lower layer having a small scale and the surrounding map. 8
After reading the map data relating to the four 4-divided map leaves from the CD-ROM 11 to the buffer memory 15b (if the map data already exists in the buffer memory 15b, the reading is not performed), and then, from the road data for each 4-divided map leaf. , An intersection netlist is created in the route search memory 15h for each intersection (including an original intersection node and a simple node that is an adjacent node) (step 104).

In the creation of the intersection netlist, the nine four-division diagrams in the lower layer around the position of the vehicle are shown in B as shown in FIG.
When it consists of U _{11 to} BU ₃₃ , first, one of the four-divided map leaves BU
_{As for 11} , search the node table NDTB of the data unit for an intersection node with an intersection identification flag and a neighboring node with an intersection identification flag set but an adjacent node identification flag, and ascending from 1 Each intersection netlist with sequential numbers and intersection sequential numbers is prepared in the route search memory, and the intersection ID is registered ((0) to (5) in FIG. 2 step 1.
04-106). Then, the node table NDTB, the intersection constituent node list CRDT, and the adjacent node list NN
The positions on the intersection constituent node list, the number of intersection constituent nodes, the positions on the adjacent node list, and the number of adjacent nodes are obtained from the LT, and (6) to (9) in FIG. 2 are registered (step 1
07). Next, for each road in the road list RDLT, by referring to the node table NDTB, the distance of the link between adjacent intersections (including the case where one is a simple node and the adjacent node), the attribute of the link (road (Type, width), the intersection netlist related to one intersection of the link, the other intersection of the link as an adjacent intersection, the intersection sequential number (adjacent intersection sequential number) registered in the intersection netlist related to the adjacent intersection , The distance and attribute of the link are registered ((1 in FIG. 2
1) to (31). Step 108).

Also, in the road list RDLT, it is checked whether or not the intersection related to the intersection netlist exists on a highway or a national highway. If it does not exist, it is the same as the road included in the road data of a large scale upper layer map leaf. As information indicating that it is not an intersection on a road, the upper road identification data in (10) of FIG. 2 is set to “111”. On the contrary, when it exists on a highway or a national road, the upper-layer map leaf with a large scale is shown. The upper road identification data is set to "000" as information indicating that the road is an intersection on the same road as the road included in the road data (step 109). Similar processing
After performing BU ₁₂ to BU _{33 in} FIG. 14 (steps 104 to 109), finally, when the target for which the intersection netlist is created also serves as an adjacent intersection at the intersection node and when the intersection netlist is created. When the obtained target is a neighbor node of a simple node, an intersection netlist may be created under another shared unit for the same neighbor node (the neighbor node RN ₁ in FIG. 14,
RN ₂ ), referring to the neighbor node list NNLT,
Search for intersection sequential numbers in all other shared units, register adjacent intersection sequential numbers and distances (= 0) in the intersection netlist, and perform adjacent node connection processing between divided map leaves (step 110).

As described above, the route search memory 15h
After completing the creation of the intersection netlist related to the lower layer map around the vehicle position, the map display control device 15 operates the operation unit 14
Was the map enlargement / reduction key pressed with? (Step 11
1) Was the route guidance mode key pressed (step 1
12) It is checked whether the power is turned off (step 113). If neither is found, the optimum route searching unit 15g also finds the intersection netlist that has been stored in the route searching memory 15h until the own vehicle position. 4 for each lower layer
It is checked (step 114) whether or not one of the four divisional leaflets at the center is out of the range of the four divisional leaflets (initially, BU ₂₂ in FIG. 14). If not, the process returns to step 111.

The map display control device 15 executes step 101.
After that, interrupts are periodically generated to perform the processing of FIG. In the flow of FIG. 5, first, the map image drawing unit 15a inputs the vehicle position data from the vehicle position detecting unit 13 and checks whether the vehicle position has changed from that time (step 201). If there is no change, the process returns to the original processing, and if there is a change, from the map image drawn in the video RAM 15d,
Check if the range of one screen centered on the position of the vehicle is out. If it is out, if necessary, CD-ROM1
From 1 to the vicinity of the own vehicle position, while reading new map data related to the same leaf as the scale level that has been displayed so far into the buffer memory 15b, a map image for 9 screens centering on the own vehicle position is displayed in the video RAM 15d. Is drawn (steps 202 and 203). Then, the guide route drawing unit 15c
Checks if it is currently in route guidance mode (step 20
4) Since it is NO here, the guide route is not drawn. If the vehicle is in the route guidance mode, a portion within the area drawn in the video RAM 15d is selected from the guidance route data stored in the guidance route storage unit 15i on the basis of the vehicle position data, and is stored in the video RAM 15d. The guide route is drawn by thickly emphasizing it with a predetermined color (step 2).
05).

If the result is not out of step 202, the video RAM 15d is not rewritten. Then, the map image drawing unit 15a causes the read control unit 15e to cut out a one-screen map image centered on the vehicle position from the video RAM 15d and outputs it to the synthesizing unit 15j. The vehicle position mark generation unit 15f also generates a predetermined vehicle position mark in the direction indicated by the vehicle direction data detected by the vehicle position detection unit 13 and outputs it to the synthesis unit 15j. The synthesizing unit 15j synthesizes the vehicle position mark with the map image, outputs it to the display device 12, and displays it on the screen (step 20).
6). After step 206, the map display control device 15 returns to the original processing.

In this way, as the vehicle position changes due to the traveling of the vehicle in the normal guidance mode, the map image scrolls on the screen in the direction opposite to the traveling direction of the vehicle, and the map around the vehicle position is constantly displayed. The map image can be viewed, and the vehicle position on the map image can be confirmed.

After that, when the vehicle position changes into, for example, the four-division diagram leaves BU ₂₂ to BU ₂₃ of FIG. 14 due to the change of the vehicle position, the optimum route searching unit 15g performs Y in step 114 of FIG.
When it is determined to be ES, at this time, the process proceeds to the flow of FIG. 6 to update the lower layer intersection netlist around the vehicle position and update and store it in the route search memory 15h. At this time, with respect to the unnecessary four-divided map leaf (BU ₁₁ , BU ₂₁ , BU _{31 in} FIG. 14), the lower layer intersection netlist in the route search memory 15h is deleted (step 301), and it is newly required. Four
An intersection netlist is created in sequence for each of the divided map leaves (BU ₁₄ , BU ₂₄ , BU _{34 in} FIG. 14) in the same manner as described above. First, regarding the four-division diagram leaf BU ₁₄ , an intersection node with an intersection identification flag set from the node table NDTB of the data unit, and an adjacent node that is a simple node with the intersection identification flag set but an adjacent node identification flag set , And prepare each intersection netlist on the route search memory after adding the last number at the time of creating the previous intersection netlist and then adding the intersection sequential numbers in ascending order to register the intersection ID. ((0)-(5) of FIG. 2, steps 302-30
4). Then, from the node table NDTB, the intersection configuration node list CRDT, and the adjacent node list NNLT,
Obtain the position on the intersection constituent node list, the number of intersection constituent nodes, the position on the adjacent node list, and the number of adjacent nodes,
The items (6) to (9) in FIG. 2 are registered (step 305).
When the intersection sequential number reaches a predetermined upper limit value, it is returned to number 0 and referred to.

Next, for each road in the road list RDLT, by referring to the node table NDTB, the distance of links between mutually adjacent intersections (including the case where one of them is an adjacent node of a simple node), Attribute (road type, width)
, The intersection netlist related to one intersection of the link, the other intersection of the link as an adjacent intersection, the intersection sequential number registered in the intersection netlist related to the adjacent intersection (adjacent intersection sequential number),
The distance and attribute of the link are registered ((1 in FIG. 2
1) to (31). Step 306).

When the intersection related to the intersection netlist does not exist on the highway or the national road in the road list RDLT, it is on the same road as the road included in the road data of the upper layer map leaf having a large scale. As the information indicating that the road is not an intersection, the upper road identification data in (10) of FIG. 2 is set to “111”. On the contrary, when the road exists on a highway or a national road, the road data of a large-scale upper-layer map leaf is large. The upper road identification data is “000” as information indicating that it is an intersection on the same road as the road included in
(Step 307). Similar processing is performed in B of FIG.
After doing U ₂₄ and BU ₃₄ (Step 302-
307), and finally, all four split view leaves BU ₁₂ ~BU being made to the route search memory 15h _24, BU ₂₂ ~BU _24,
If the target of the intersection netlist according to BU _{32 to} BU ₃₄ also serves as an adjacent intersection at the intersection node, or if the target for which the intersection netlist is created is an adjacent node of a simple node, the same adjacent node is Since the intersection netlist may be created even under the shared unit of (see adjacent nodes RN ₃ and RN _{4 in} FIG. 14), the adjacent node list NNLT is referred to, and The intersection sequential number is searched, the adjacent intersection sequential number and the distance (= 0) are registered in the intersection netlist, and the adjacent node connection processing between the divided map leaves is performed (step 308). At this time, as for the adjacent unit RN ₁ of the 4-division diagram leaf BU ₁₂ in FIG. 14, for the other unit (4-division diagram leaf BU ₁₁ ) that is no longer shared, the intersection netlist is deleted, Delete the adjacent intersection sequential number and distance from the intersection netlist.

In this way, each time the vehicle position deviates from the previous four-division diagram leaf while the vehicle is traveling, unnecessary ones are deleted from the lower-layer intersection netlist of the route search memory 15h, and a new one is newly added. Since necessary items are added, the lower layer intersection netlist for the lower four nine-divided map sheets centering on the vehicle position is always held in the route search memory 15h.

If a map image with a large scale is displayed on the screen, the user may enlarge the operation unit 14 to see a more detailed map image by going off a highway or a national road and entering a prefectural road. When the key is pressed, the map image drawing unit 1
5a determines YES in step 111 of FIG. 4, inputs the vehicle position data detected by the vehicle position detection unit 13, and
The buffer memory 15 is provided with new map data related to the lower-layer map leaf having a small scale from the CD-ROM 11 around the vehicle position.
While reading out to b, a map image for 9 screens centering on the position of the vehicle is drawn on the video RAM 15d. Then, the map image drawing unit 15a controls the read control unit 15e,
A one-screen map image centered on the vehicle position is cut out from the video RAM 15d and output to the combining unit 15j. In addition, the vehicle position mark generation unit 15f also includes the vehicle position detection unit 1
A predetermined vehicle position mark is generated in the direction indicated by the vehicle direction data detected in 3, and is output to the synthesizing unit 15j. The synthesizing unit 15j synthesizes the vehicle position mark with the map image, outputs it to the display device 12, and displays it on the screen (step 115). As a result, this time, the enlarged detailed map image will be displayed together with the vehicle position mark, and even if you drive off the highway or national road, you can grasp the road condition around your vehicle position. ..

On the contrary, in the state where a small scale map image is displayed on the screen, in order to see a wider range of map images such as entering a national highway or a highway from a prefectural road or city road, the operation unit 14 is used. When the reduction key is pressed, the map image drawing unit 15a determines YES in step 111, inputs the vehicle position data detected by the vehicle position detection unit 13, and inputs the vehicle position data from the CD-ROM 11 to the scale around the own vehicle position. Buffer memory 15a for the map data related to the map leaf in the upper layer of
While reading out, a map image for 9 screens centering on the position of the vehicle is drawn on the video RAM 15d. Then, the map image drawing unit 15a causes the read control unit 15e to cut out a one-screen map image centered on the vehicle position from the video RAM 15d and outputs it to the synthesizing unit 15j. Also,
The vehicle position mark generation unit 15f also generates a predetermined vehicle position mark in the direction indicated by the vehicle azimuth data detected by the vehicle position detection unit 13 and outputs it to the synthesis unit 15j. Synthesis unit 15
j combines the vehicle position mark with the map image, outputs it to the display device 12, and displays it on the screen (step 11).
5). As a result, this time, the reduced map image is displayed together with the vehicle position mark, and it is possible to grasp a wide range of road conditions around the vehicle position.

Route search processing (departure-destination is close
Unlike this, when the driver wants to travel to the desired destination in the route guidance mode, the route guidance mode key on the operation unit 14 is pressed to enter the route guidance mode (YES in step 112 of FIG. 4, Step 401 in FIG. 7). Next, the map image drawing unit 15 is operated by operating the map search key, the enlargement key, or the like.
A small scale map image of the lower layer including the destination is displayed on the display screen by a, and then the vehicle position mark is positioned at the destination using the map scroll key to set the destination (step 402 in FIG. 7). ).

When the destination is set, the optimum route searching unit 1
5g automatically sets the current vehicle position as the departure place (step 403), and the optimum route searching unit 15f defines the departure place in the lower layer road data based on the map data of the lower layer map including the departure place. The intersection (the original intersection node or an adjacent node of simple nodes) (step 4
04), if it is an intersection, it is set as the departure point intersection STP (step 405), and the processing after step 407 is performed. , Processing after step 407 is performed. When the departure point intersection STP is determined, the optimum route searching unit 15g checks whether the destination is the intersection defined by the road data of the lower layer (the original intersection node or the adjacent node of the simple nodes) (step 4).
07), if it is an intersection, it is set as the destination intersection DSP (step 408) and the processing from step 410 is performed. If it is not the intersection, the nearest intersection is set as the destination intersection DSP (step 409) and the processing after step 410 is performed. To do.

Departure intersection STP and destination intersection DS
When P is determined, the optimum route search unit 15g calculates the distance between the departure point intersection STP and the destination intersection DSP, and checks whether they are present at relatively close positions within a certain distance (steps 410 and 411), In the case of YES, referring to the map leaf management information, one or a plurality of four-divided map leaves including a rectangular area having a straight line connecting the starting point and the destination as a diagonal line is obtained, Route search memory 1
It is checked at 5h whether or not the lower intersection netlist has been created (step 412). Origin STP and destination DSP
Is in a positional relationship as shown in FIG. 14, and has not been created.
If there are U ₁₅ and BU ₂₅ , a lower layer intersection netlist is created for these four-divided map leaves and is additionally stored in the route search memory 15h in the same manner as described above (step 413). Here, the intersection sequential number of the added intersection netlist is also sequentially numbered after the last number assigned last time. Originally, it takes a relatively long time to create an intersection netlist, but here, for the map leaves around the departure point, the lower level intersection netlist has already been created, so the time required for addition is It can be short.

In this way, one or a plurality of all four areas including a rectangular area having a straight line connecting the starting point and the destination as a diagonal line.
When the lower level intersection netlist is completed for the divided map leaves, the optimal route searching unit 15g uses the lower level intersection netlist to find the optimal route connecting the starting point to the destination by the Dijkstra method. Search (see FIG. 15). First, the search order is set to 0 (step 501 in FIG. 8), and it is checked whether or not an intersection adjacent to the i-th intersection (the 0th is the departure intersection) remains by referring to the intersection netlist CRNL at the departure intersection STP. (Step 5
02). In step 502, the jth intersection (j = 0, 1, ..., I) that has been determined so far is excluded.

If an adjacent intersection remains, one of the adjacent intersections, for example, A ₁ , is the starting point intersection STP.
The cumulative distance D from the departure point intersection STP to the adjacent intersection A ₁ is calculated by referring to the distance d ₂ from the departure point intersection STP to the first adjacent intersection A _{1 in the} lower intersection netlist CRNL according to Step 503). D ₁ The total distance D from the departure point intersection STP to i-th order intersection, when the distance d ₂ from the i-th order intersection to the adjacent intersection A _1, but found by the following equation d ₁ + d ₂ → D, initially Since d ₁ = 0 when i = 0, D
= D ₂ . d ₂ is stored in the item (33) in FIG. 2 of the intersection netlist CRNL related to the departure point intersection STP.

Next, referring to item (17) of the intersection netlist CRNL relating to the adjacent intersection A ₁ , whether the search order is (i + 1), in other words, the intersection A ₁ has already been accumulated on different routes. It is checked whether or not the information (intersection sequential number) for specifying the distance and the intersection just before is registered (step 504), and since it is NO here, the intersection net list CR relating to the adjacent intersection A ₁ is checked.
In (32) to (34) of FIG. 2 of the NL, the following data (A) the intersection sequential number of the 0th intersection STP currently being focused on, (B) the departure intersection STP to the adjacent intersection A ₁ Total distance (Ad ₁ ), (C) (i +) as the search order of the adjacent intersection A ₁
1) = 1 is registered (step 505), and thereafter, the process returns to step 502, refers to the intersection net list CRNL targeting the departure point intersection STP, and refers to the intersection adjacent to the 0th intersection of interest. It is checked whether or not it remains, and if it remains, the same processing is repeated. As a result, if there are adjacent intersections A _{1 to} A _{3 in} the intersection netlist of the departure point intersection STP, these are regarded as primary intersections, and the intersection netlist CRNL indicates the previous intersection (here, the departure point). The intersection sequential number of the intersection STP), the search order 1 and the cumulative distances Ad _{1 to} Ad ₃ are registered.

When the processing is completed for all the adjacent intersections included in the intersection net list CRNL for the departure point intersection STP, the optimum route searching unit 15g determines whether there is a 0th intersection other than the departure point intersection STP. (Step 506), because there is no destination, continue to destination intersection D
It is determined whether SP has been reached, in other words, whether the destination intersection DSP is included in the (i + 1) th intersection (step 507). If not, i is incremented to 1 (step 507). 508). Then, paying attention to one of the first-order intersections, for example, A ₁ , and referring to the intersection netlist relating to the intersection A ₁ stored in the route search memory 15h, the 0th order intersection,
It is determined whether or not there is an adjacent intersection other than the primary intersection (step 502). Here, B ₁₁ , B
Since there are ₁₂ and B ₁₄ , one of them, for example, the adjacent intersection B ₁₁ , is referred to the intersection netlist relating to the intersection A ₁ , and the departure point STP and the first-order intersection A currently being focused on. ₁ , the cumulative distance D on the route of the adjacent intersection B ₁₁ is calculated (step 503). Cumulative distance d ₁ from the departure point intersection STP to the primary intersection A ₁ currently being focused on and the adjacent intersection B ₁₁ from the primary intersection A ₁
The distance d _{2 to} is stored as the items (33) and (12) in FIG. 2 of the intersection netlist CRNL related to the intersection A _1, and therefore Ad ₁ + d ₂ → D from the departure point STP to the adjacent intersection B. The total distance D up to ₁₁ is obtained.

Next, with reference to the intersection netlist CRNL related to the adjacent intersection B ₁₁ , it is checked whether the search order registered in the item (34) of FIG. 2 is (i + 1) = 2 (step 504). Since it is NO, the following data is associated with the adjacent intersection B ₁₁ (A) the intersection sequential number of the primary intersection A ₁ currently being focused on, (B) from the departure point intersection STP to the adjacent intersection B ₁₁ Cumulative distance (Bd ₁₁ ), (C) (i +) as the search order of the adjacent intersection B ₁₁
1) = 2 FIG. 2 of the intersection netlist CRNL related to the intersection B ₁₁
(32) to (34) (step 505), the process returns to the step 502, and if there is a next adjacent intersection related to the first intersection A ₁ , the same processing is performed.

In the intersection netlist of intersection A ₁ ,
If there are adjacent intersections B _{12 to} B ₁₄ and B ₁₃ is the same as the starting point intersection STP, the intersection STP is removed in step 502 and processed. In each processing of the remaining B _12, B _14, when both become YES at step 502, B _12, B ₁₄ is a secondary intersection of intersection A ₁ to the corresponding intersections netlist CRNL intersection sequential The number, cumulative distances Bd ₁₂ , Bd ₁₄ , and search order 2 are registered.

First intersection A₁Intersections for
All adjacent intersections included in Toristo CRNL are treated
When the processing ends, the optimum route searching unit 15g determines that the other
It is judged whether there is a difference (step 506), and A₂And A
₃, There is one intersection A₂The new first
As the next intersection (step 509), after step 502
Repeat the process of descending. Intersection A₂Intersection netlist
To adjacent intersection B_{twenty one}~ B _{twenty four}Exists and B_{twenty four}= Origin
If it is an intersection STP, it is removed in step 502 and processed.
Be done. Also, B_{twenty one}In the processing of B_{twenty one}= B₁₂So
In step 504, the adjacent intersection B₁₂The degree of is already
Since it is 2, it becomes YES. This is the first
Intersection A₁Intersection B adjacent to₁₂Processed as (as above
(A) to (C) data has been stored)
However, in this case, the adjacent intersection B₁₂Intersection Net Relating to
From the departure point intersection STP registered in the strike CRNL
Total distance D '= Bd₁₂And this time, I got it in step 503
The magnitude of the distance D is compared (step 510).

If D <D ', the adjacent intersection B
The i-th intersection A ₁ stored in the item (34) in FIG. 2 of the intersection netlist CRNL of ₁₂ (= B ₂₁ ).
The intersection sequential number of is replaced by the intersection sequential number of the ith intersection A ₂ currently being focused on, and the cumulative distance D ′ is rewritten with D = Bd ₂₁ (step 511), and thereafter the process returns to step 502. Also, D ≧
In the case of D ′, the intersection netlist CRNL of the intersection B ₁₂ (= B ₂₁ ) in FIG.
The procedure returns to step 509 without changing the contents of 4).

With respect to the intersection A ₂ , when the predetermined processing for each adjacent intersection is completed, subsequently, the same processing is performed by setting A ₃ as the primary intersection. If another primary intersection does not exist in step 506, it is checked whether the destination intersection DSP is reached (step 507).
Since i has not yet been incremented, i is incremented to 2 (step 508). Then, the process proceeds to step 502, and the same processing as described above is sequentially repeated. In step 507, the destination intersection DSP is included in all the (i + 1) th intersections, and when the determination is YES, the destination intersection DSP and the destination intersection DSP
Intersection netlist CR relating to (m-th intersection)
It is stored as the item (34) in FIG. 2 of the NL (m-
1) The next intersection, the (m-1) th intersection stored in the intersection netlist CRNL relating to the (m-1) th intersection, ... to the intersection netlist CRNL relating to the second intersection. The 0th-order intersections = starting-point intersections STP stored in the intersection netlist CRNL related to the first-order intersections and the first-order intersections that have been stored are sequentially connected in the order from the starting-point side to the destination-side to obtain the shortest route. Determine (step 51)
2).

Then, among the obtained shortest routes, between the intersections adjacent to each other, the road list RDLT is used to determine the intersection using the road type ((13) in FIG. 2 etc.) of the intersection net list CRNL. A simple node on the link connecting the two is searched for, interpolated, and the final node sequence forming the optimum route from the departure point intersection STP to the destination intersection DSP is stored in the guide route storage unit 15g as guide route data. The route search process ends (step 513).

Route search processing (departure-destination is far
In contrast to this, when the destination set by the driver is far from the departure point and NO is determined in step 411 of FIG. 7, the optimum route searching unit 15g refers to the map leaf management information and displays the scale. Among the small lower layer map leaves, the map data related to the map leaves around the destination is read from the CD-ROM 11 to the buffer memory 15b, and one 4-division map leaf including the destination and eight 4-division map leaves surrounding the map leaf are extracted. Ask. Here, if it is assumed that the lower right of FIG.
For U _{11 to} CU ₃₃ , create a lower-layer intersection netlist in the same manner as described above, distinguish it from the already-created lower-layer intersection netlist around the vehicle position (starting point), and It is additionally stored in the route search memory 15h as the ground side (step 601 in FIG. 9). Here again, the intersection sequential number of the added lower-layer intersection netlist is a sequential number that follows the last number added last time (following the last number of the lower-layer intersection netlist on the departure side).
In addition, the intersection related to the intersection net list is the road list R.
If it does not exist on a highway or national road in the DLT, the upper layer road of the intersection netlist is information indicating that it is not an intersection on the same road as the road included in the road data of the upper layer map leaf with a large scale. The identification data is “11
1 ", on the contrary, when the road exists on a highway or a national road, the upper road identification is used as information indicating that it is an intersection on the same road as the road included in the road data of the upper map leaf with a large scale. The data is set to “111”. Originally
Although it takes a relatively long time to create the intersection netlist, the time required for addition is also short here because the lower level intersection netlist has already been created for the departure point side.

When the creation of the intersection netlist of the lower layer on the peripheral side of the target is completed, the straight line connecting the starting point and the destination is drawn in the upper layer of the large scale by referring to the leaf management information. the calculated (in this case, 4 split view leaf upper shall become as AU ₁₁ ~AU ₂₂ in FIG. 16) one or more of the four-divided diagram leaf including a square area whose diagonal is, of the upper layer 4 An intersection netlist is created for each of the divided map leaves, and is additionally stored in the route search memory 15h separately from the intersection netlist of the lower layer (step 60).
2). Here again, the intersection sequential number of the added upper-layer intersection netlist is a serial number following the last-added last number (following the last number of the destination-side lower-layer intersection netlist).

When the creation of the intersection netlist of the upper layer is completed, the optimum route search unit 15g sets the road identification data of the upper layer to "000" in each of the intersection netlists of the lower layer as the connection processing of the lower layer and the upper layer. If there is an upper-level intersection netlist created in the upper-level intersection netlist at the same position coordinates as the lower-level intersection, refer to the upper-level intersection netlist etc., and if there is, the upper-level intersection sequential number 5SB to LSB of the item (10) in FIG. 2 of the corresponding lower intersection netlist.
Is registered as an upper layer sequential number, and the MSB (upper layer node existence flag) of the item data of (11) in the figure is set to 1 to indicate that there is an upper layer intersection corresponding to the lower layer intersection ( Step 60
3).

When the creation of the intersection netlist is completed in this way, the optimum route search unit 15g first uses the lower-layer intersection netlist CRNL on the peripheral side of the departure place,
By the Dijkstra method, the intersection on the expressway or the national road closest to the departure point in the lower layer (including simple nodes that are adjacent nodes) is used as the upper layer intersection SA
As the upper layer intersection SA and the departure point intersection STP
To search for the optimum first route connecting from to the upper layer intersection SA (see FIG. 17). First, referring to the upper layer road identification data of the lower intersection netlist CRNL related to the departure point intersection STP stored in the route search memory 15h,
It is checked whether it is "000", in other words, whether the intersection exists on a highway or a national road (step 604), and if YES, the upper-layer starting intersection SA =
The search is completed as a node of the departure point intersection STP and the first route = the departure point intersection STP, and the upper layer origin intersection SA is stored in the route search memory 15h and the first route data is stored in the guidance route storage unit 15i (step 605).

Subsequently, it is checked whether the upper layer node existence flag is set in (10) of the intersection netlist CRNL related to the upper layer origin intersection SA and the intersection having the same coordinates is defined in the upper layer (step 606). ,
If YES, the intersection netlist has already been created in the upper layer for the intersection, and the upper layer intersection sequential number registered in the same item (10) is registered in the route search memory 15h (step 607). If NO in step 606, since the same intersection does not exist in the upper layer, the upper layer starting point intersection SA can be treated as an upper layer starting point intersection as shown in the upper part of FIG. One upper layer intersection netlist is additionally created using SA as a pseudo-intersection in the upper layer, and additionally stored in the route search memory 15h (step 608).

At this time, the intersection sequential number follows the last number given last time (follows the last number in the lower layer intersection netlist on the destination side). Then, from the intersection ID and position coordinates of the lower-layer intersection netlist CRNL related to the upper-layer origin intersection SA and the leaf management information, one 4-layer map leaf of the upper layer where the upper-layer origin intersection SA is located is obtained, and its leaf number And the unit code, and the upper level intersection SA
It is registered as items (1) to (5) in FIG. 2 of the upper-layer intersection netlist added this time together with the position coordinates of. Then, the road to which the upper-layer origin intersection SA belongs is obtained from the road data of the lower-layer four-segment map leaf to which the upper-layer origin intersection SA belongs, and the same road is obtained from the road data related to the upper-layer four-segment map leaf where the upper layer origin intersection SA is located. , And two intersections (including adjacent nodes at simple nodes) F ₁ and F ₂ defined at positions sandwiching the upper-layer origin intersection SA in the upper-layer map data, and these two intersections are searched. F
₁ , F ₂ as an adjacent intersection to the upper-layer origin intersection SA in the upper layer, the intersection F ₁ seen from the upper-layer origin intersection SA,
The distance of the link to F ₂ , the attribute of the link (road type,
Width), and together with the intersection sequential numbers of the upper-layer intersection netlist related to the intersections F ₁ and F ₂ ,
Registered as (11) to (16) in FIG. 2 in the upper-layer intersection net list related to the intersection SA.

On the other hand, in the upper-layer intersection netlist related to the intersection F ₁ , the upper-layer origin intersection SA is set as a new adjacent intersection, and the link distance between the intersection F ₁ and the upper-layer origin intersection SA and the attribute of the link (road type) , Width) at the intersection S
A is added together with the intersection sequential number of the upper layer intersection netlist, and similarly, in the upper layer intersection netlist related to the intersection F ₂ , the upper layer origin intersection SA is set as a new adjacent intersection between the intersection F ₂ and the upper layer intersection SA. The distance of the link, the attribute of the link (road type, width),
The connection process is performed by adding together with the intersection sequential number of the upper layer intersection netlist of the intersection SA. For other items in the upper intersection netlist of the intersection SA,
Unregistered or dummy data. Then, the process of step 607 is performed.

On the other hand, when the answer is NO in step 604, the optimum route searching unit 15g sets the search order to 0 (step 701 in FIG. 10) and sets the intersection adjacent to the i-th intersection (the 0th is the departure intersection). Is checked by referring to the intersection netlist CRNL at the starting point intersection STP (step 702). In step 702, the j-th intersection (j = 0, 1, ..., I) that has been determined so far is excluded.

If an adjacent intersection remains, one of the adjacent intersections, for example, A _1, will have a departure point STP.
The cumulative distance D from the departure point intersection STP to the adjacent intersection A ₁ is calculated by referring to the distance d ₂ from the departure point intersection STP to the first adjacent intersection A _{1 in the} lower-layer intersection netlist CRNL of ( Step 703). D ₁ The total distance D from the departure point intersection STP to i-th order intersection, when the distance d ₂ from the i-th order intersection to the adjacent intersection A _1, but found by the following equation d ₁ + d ₂ → D, initially Since d ₁ = 0 when i = 0, D
= D ₂ . d ₂ is stored in the item (33) in FIG. 2 of the intersection netlist CRNL related to the departure point intersection STP.

Next, referring to the item (17) of the intersection net list CRNL related to the adjacent intersection A ₁ , whether the search order is (i + 1), in other words, the intersection A ₁ has already been accumulated on different routes. It is checked whether or not the information (intersection sequential number) for specifying the distance and the previous intersection is registered (step 704), and since it is NO here, the intersection net list CR related to the adjacent intersection A ₁ is checked.
In (32) to (34) of FIG. 2 of the NL, the following data (A) the intersection sequential number of the 0th intersection STP currently being focused on, (B) the departure intersection STP to the adjacent intersection A ₁ Total distance (Ad ₁ ), (C) (i +) as the search order of the adjacent intersection A ₁
1) = 1 is registered (step 705), and thereafter, the process returns to step 702, the intersection net list CRNL for the departure point intersection STP is referred to, and the intersection adjacent to the 0th-order intersection of interest is still detected. It is checked whether or not it remains, and if it remains, the same processing is repeated. As a result, if there are adjacent intersections A _{1 to} A _{3 in} the intersection netlist of the departure point intersection STP, these are regarded as primary intersections, and the intersection netlist CRNL indicates the previous intersection (here, the departure point). The intersection sequential number of the intersection STP), the search order 1 and the cumulative distances Ad _{1 to} Ad ₃ are registered.

When the processing is completed for all the adjacent intersections included in the intersection net list CRNL for the departure point intersection STP, the optimum route searching unit 15g determines whether there is a 0th intersection other than the departure point intersection STP. However, since it does not exist (step 706), the upper road identification data is “000” while the vehicle has reached the highway or the national road (upper road intersection SA), or in other words, is the (i + 1) th intersection. It is determined whether any of the following are included (step 707), and if not, i is incremented to 1 (step 708). Then, paying attention to one of the first-order intersections, for example, A ₁ , and referring to the intersection netlist relating to the intersection A ₁ stored in the route search memory 15h, the 0th order intersection,
It is determined whether or not there is an adjacent intersection other than the primary intersection (step 702). Here, B ₁₁ , B
Since there are ₁₂ and B ₁₄ , one of them, for example, the adjacent intersection B ₁₁ , is referred to the intersection netlist relating to the intersection A ₁ , and the departure point STP and the first-order intersection A currently being focused on. ₁ , the cumulative distance D on the route of the adjacent intersection B ₁₁ is calculated (step 703). Cumulative distance d ₁ from the departure point intersection STP to the primary intersection A ₁ currently being focused on and the adjacent intersection B ₁₁ from the primary intersection A ₁
The distance d _{2 to} is stored as the items (33) and (12) in FIG. 2 of the intersection netlist CRNL related to the intersection A _1, and therefore Ad ₁ + d ₂ → D from the departure point STP to the adjacent intersection B. The total distance D up to ₁₁ is obtained.

Next, with reference to the intersection netlist CRNL related to the adjacent intersection B ₁₁ , it is checked whether the search order registered in the item (34) of FIG. 2 is (i + 1) = 2 (step 704). Since it is NO, the following data is associated with the adjacent intersection B ₁₁ (A) the intersection sequential number of the primary intersection A ₁ currently being focused on, (B) from the departure point intersection STP to the adjacent intersection B ₁₁ Cumulative distance (Bd ₁₁ ), (C) (i +) as the search order of the adjacent intersection B ₁₁
1) = 2 FIG. 2 of the intersection netlist CRNL related to the intersection B ₁₁
(32) to (34) (step 705), the process returns to the side of step 702, and if there is the next adjacent intersection related to the first intersection A ₁ , the same processing is performed.

In the intersection netlist of intersection A ₁ ,
If there are adjacent intersections B _{12 to} B ₁₄ and B ₁₃ is the same as the starting point intersection STP, the intersection STP is removed in step 702 and processed. In each processing of the remaining B _12, B _14, when both become YES at step 702, B _12, B ₁₄ is a secondary intersection of intersection A ₁ to the corresponding intersections netlist CRNL intersection sequential The number, cumulative distances Bd ₁₂ , Bd ₁₄ , and search order 2 are registered.

First intersection A₁Intersections for
All adjacent intersections included in Toristo CRNL are treated
When the processing ends, the optimum route searching unit 15g determines that the other
It is judged whether there is a difference (step 706), and A₂And A
₃, There is one intersection A₂The new first
As the next intersection (step 709), after step 702
Repeat the process of descending. Intersection A₂Intersection netlist
To adjacent intersection B_{twenty one}~ B _{twenty four}Exists and B_{twenty four}= Origin
If it is an intersection STP, it is removed in step 702 and processed.
Be done. Also, B_{twenty one}In the processing of B_{twenty one}= B₁₂So
In step 704, the adjacent intersection B₁₂The degree of is already
Since it is 2, it becomes YES. This is the first
Intersection A₁Intersection B adjacent to₁₂Processed as (as above
(A) to (C) data has been stored)
However, in this case, the adjacent intersection B₁₂Intersection Net Relating to
From the departure point intersection STP registered in the strike CRNL
Total distance D '= Bd₁₂And this time, I got it in step 703
The magnitude of the distance D is compared (step 710).

If D <D ', the adjacent intersection B
The i-th intersection A ₁ stored in the item (34) in FIG. 2 of the intersection netlist CRNL of ₁₂ (= B ₂₁ ).
The intersection sequential number of No. is replaced with the intersection sequential number of the ith intersection A ₂ currently being focused on, and the cumulative distance D ′ is rewritten with D = Bd ₂₁ (step 711), and thereafter the process returns to step 702. Also, D ≧
In the case of D ′, the intersection netlist CRNL of the intersection B ₁₂ (= B ₂₁ ) in FIG.
The procedure returns to step 702 without changing the contents of 4).

With respect to the intersection A ₂ , when the predetermined processing for each adjacent intersection is completed, subsequently, the same processing is performed by setting A ₃ as the primary intersection. Then, if another primary intersection does not exist in step 706, it is checked whether or not the vehicle has reached an expressway or a national road (step 707).
Since i has not yet been incremented, i is incremented to 2 (step 708). Next, the process proceeds to step 702, and the same processing as described above is sequentially repeated. In the check in step 707, the upper road identification data is "000" among all the intersections of the (i + 1) th order, and when the determination is YES, the intersection is determined. The upper layer starting point intersection SA is stored, and the upper layer starting point intersection SA and the intersection netlist CRNL related to the upper layer starting point intersection SA (m-th order intersections) are stored as the item (34) in FIG. , The intersection of the (m-1) th intersection, which is stored in the intersection netlist CRNL, and the (m-2) th intersection, which is stored in the intersection netlist CRNL of the second intersection. A certain crossing,
The 0th-order intersection = starting-point intersection STP stored in the intersection netlist CRNL related to the first-order intersection is sequentially connected in the order from the starting point side to the upper-layer starting point intersection side to determine the shortest route (step 712). At this time, the upper-layer starting point intersection is registered in the route search memory 15h.

Then, between the adjacent intersections of each of the obtained shortest routes, the road list RDLT is used to determine the intersection using the road type ((13) in FIG. 2 etc.) of the intersection net list CRNL. A simple node on the link connecting the two is searched for, interpolated, and the final node sequence forming the optimum route from the departure point intersection STP to the upper-layer origin intersection SA is stored in the guide route storage unit 15g as guide route data. The route search process ends (step 713).

Then, the optimum route search unit 15g proceeds to step 606 of FIG. 9 and refers to the upper layer node identification flag relating to the upper layer origin intersection SA in the same manner as described above, and refers to the same intersection as the upper layer. Check whether it exists in the road data, and if it exists, (10) in FIG.
The upper-layer intersection sequential number registered in the above is registered in the route search memory 15h (step 607), and if it does not exist as an intersection in the upper layer, it is treated as a pseudo-intersection in the upper layer, and an intersection netlist is additionally created in the upper layer to generate a route. It is stored in the search memory 15h (step 608), and the intersection sequential number of the added intersection net list is registered (step 607).

Next, the optimum route searching unit 15g uses the lower layer intersection netlist CRNL on the destination peripheral side and uses the Dijkstra method to select an intersection (on the highway or on the national road closest to the destination in the lower map leaf). Among the simple nodes, those that are adjacent nodes are included as the upper layer end point intersection DA, and an optimal second route connecting the upper layer end point intersection DA and the upper layer end point intersection DA to the destination intersection DSP is searched (Fig. 18). That is, first, the route search memory 15h
Refer to the upper-layer road identification data of the lower-level intersection netlist CRNL related to the destination intersection DSP stored in “000”, in other words, the intersection exists on a highway or a national road. If it is YES (step 609), and if YES, the upper-layer end point intersection DA = destination intersection DSP, the second route = destination intersection D
As the SP node, the search is completed and the upper-level end point intersection DA
Is stored in the route search memory 15h and the second route data is stored in the guide route storage unit 15i (step 610).

Then, it is checked whether the upper layer node existence flag is set in (10) of the intersection netlist CRNL related to the upper layer end point intersection SA in FIG. ,
If YES, the intersection netlist has already been created in the upper layer for the intersection, and the upper layer intersection sequential number registered in the same item (10) is registered in the route search memory 15h (step 612). If NO in step 611, since the same intersection does not exist in the upper layer, the upper layer end point intersection DA is treated as an upper layer end point intersection as shown in the upper side of FIG. One upper-layer intersection netlist is additionally created using DA as a pseudo-intersection in the upper layer and additionally stored in the route search memory 15h (step 613).

At this time, the intersection sequential number continues from the last assigned number. Then, from the intersection ID and position coordinates of the intersection net list CRNL of the lower layer related to the upper-layer end point intersection DA and the map leaf management information, the upper-layer end point intersection D
One of the upper four-divided map leaves where A is located is obtained, the map leaf number and unit code are obtained, and together with the position coordinates of the upper-layer end point intersection DA, the item (1) -in FIG. Register as (5). Next, the road to which the upper-layer end point intersection DA belongs is obtained from the road data of the lower-layer four-part map leaf to which the upper-layer end point intersection DA belongs, and the same road is obtained from the road data related to the upper-layer four-part map leaf where the upper layer end point intersection DA is located. , And two intersections (including adjacent nodes at simple nodes) G ₁ and G ₂ that are defined at positions sandwiching the upper-layer end point intersection DA in the upper-layer map data, and these two intersections are searched. G ₁ , G ₂
As an adjacent intersection to the upper-layer end point intersection DA in the upper layer, the distances of the links from the upper-layer end point intersection DA to the intersections G ₁ and G ₂ , the attributes of the links (road type, width), and the intersection G ₁ , G ₂ together with the intersection sequential number of the upper-layer intersection netlist, the upper-layer intersection netlist of the intersection DA (11) of FIG.
Register as (16).

On the other hand, in the upper-layer intersection netlist related to the intersection G ₁ , the upper-layer end point intersection DA is set as a new adjacent intersection, and the link distance between the intersection G ₁ and the upper-layer end point intersection DA and the attribute of the link (road type) , Width), at intersection D
A is added together with the intersection sequential number of the upper-layer intersection netlist, and similarly, in the upper-layer intersection netlist related to the intersection G ₂ , the upper-layer end point intersection DA is set as a new adjacent intersection between the intersection G ₂ and the upper-layer end point intersection DA. The distance of the link, the attribute of the link (road type, width),
Connection processing is performed by adding together with the intersection sequential number of the upper layer intersection netlist of the intersection DA. For other items in the upper intersection netlist of the intersection DA,
Unregistered or dummy data. Then, the process of step 612 is performed.

On the other hand, if NO in step 609, the optimum route searching unit 15g sets the search order to 0 (step 801 in FIG. 11) and sets the intersection adjacent to the i-th intersection (the 0th is the destination intersection). Is checked by referring to the intersection netlist CRNL at the destination intersection DSP (step 802). In step 802, the j-th intersection (j = 0, 1, ...

If an adjacent intersection remains, one of the adjacent intersections, for example, A ₁ , is the destination intersection DSP.
The cumulative distance D from the destination intersection DSP to the adjacent intersection A ₁ is calculated by referring to the distance d ₂ from the destination intersection DSP to the first adjacent intersection A _{1 in} the intersection netlist CRNL of the lower layer of ( Step 803). D is the cumulative distance from the destination intersection DSP to the i-th intersection d ₁ and the distance d ₂ from the i-th intersection to the adjacent intersection A ₁ is given by the following equation d ₁ + d ₂ → D. Since d ₁ = 0 when i = 0, D
= D ₂ . d ₂ is stored in the item (33) in FIG. 2 of the intersection netlist CRNL related to the destination intersection DSP.

Next, referring to the item (17) of the intersection net list CRNL related to the adjacent intersection A ₁ , whether the search order is (i + 1), in other words, the intersection A ₁ has already been accumulated on different routes. It is checked whether or not the information (intersection sequential number) that specifies the distance and the previous intersection is registered (step 804), and since it is NO here, the intersection net list CR relating to the adjacent intersection A ₁ is checked.
In (32) to (34) of FIG. 2 of the NL, the following data (A) the intersection sequential number of the 0th intersection STP currently being focused on, (B) the departure intersection STP to the adjacent intersection A ₁ Total distance (Ad ₁ ), (C) (i +) as the search order of the adjacent intersection A ₁
1) = 1 is registered (step 805), and thereafter, the process returns to step 802, the intersection net list CRNL targeted for the destination intersection DSP is referred to, and the intersection adjacent to the 0th-order intersection of interest is still detected. It is checked whether or not it remains, and if it remains, the same processing is repeated. As a result, if the adjacent intersections A _{1 to} A ₃ are present in the intersection netlist of the destination intersection DSP, these are regarded as primary intersections, and the intersection netlist CRNL shows the preceding intersection (here, the destination intersection). The intersection sequential number of the intersection DSP), the search order 1 and the cumulative distances Ad _{1 to} Ad ₃ are registered.

When the processing is completed for all the adjacent intersections included in the intersection net list CRNL for the destination intersection DSP, the optimum route searching unit 15g determines whether there is a 0th intersection other than the destination intersection DSP. However, since it does not exist (step 806), the upper road identification data is “000” while the vehicle has reached the highway or the national road (upper-level end point intersection DA), or in other words, the (i + 1) th intersection. Is included (step 807), and if not, i is incremented to 1 (step 808). Then, paying attention to one of the first-order intersections, for example, A ₁ , and referring to the intersection netlist relating to the intersection A ₁ stored in the route search memory 15h, the 0th order intersection,
It is determined whether or not there is an adjacent intersection other than the primary intersection (step 802). Here, B ₁₁ , B
Since there are ₁₂ and B ₁₄ , one of them, for example, the adjacent intersection B ₁₁ , is referred to the intersection netlist related to the intersection A ₁ while referring to the destination intersection DSP and the first-order intersection A currently being focused on. ₁ , the cumulative distance D on the route of the adjacent intersection B ₁₁ is calculated (step 803). The from total distance d ₁ between first intersection A ₁ from the destination intersection DSP to first intersection A ₁ of interest currently adjacent intersection B ₁₁
The distance d _{2 to} is stored as the items (33) and (12) in FIG. 2 of the intersection netlist CRNL related to the intersection A ₁ , so that Ad ₁ + d ₂ → D from the destination intersection DSP to the adjacent intersection B The total distance D up to ₁₁ is obtained.

Next, with reference to the intersection netlist CRNL related to the adjacent intersection B ₁₁ , it is checked whether the search order registered in the item (34) in FIG. 2 is (i + 1) = 2 (step 804). Since it is NO, the following data is associated with the adjacent intersection B ₁₁ (A) the intersection sequential number of the primary intersection A ₁ currently being focused on, (B) the destination intersection STP to the adjacent intersection B ₁₁ Cumulative distance (Bd ₁₁ ), (C) (i +) as the search order of the adjacent intersection B ₁₁
1) = 2 FIG. 2 of the intersection netlist CRNL related to the intersection B ₁₁
(32) to (34) (step 805), the process returns to the side of step 802, and if there is the next adjacent intersection related to the first intersection A ₁ , the same processing is performed.

In the intersection netlist of intersection A ₁ ,
If there are adjacent intersections B _{12 to} B ₁₄ and B ₁₃ is the same as the starting point intersection STP, the intersection STP is removed in step 802 and processed. In each processing of the remaining B _12, B _14, when both become YES at step 802, B _12, B ₁₄ is a secondary intersection of intersection A ₁ to the corresponding intersections netlist CRNL intersection sequential The number, cumulative distances Bd ₁₂ , Bd ₁₄ , and search order 2 are registered.

First intersection A₁Intersections for
All adjacent intersections included in Toristo CRNL are treated
When the processing ends, the optimum route searching unit 15g determines that the other
It is judged whether there is a difference (step 806), and A₂And A
₃, There is one intersection A₂The new first
As the next intersection (step 809), after step 802
Repeat the process of descending. Intersection A₂Intersection netlist
To adjacent intersection B_{twenty one}~ B _{twenty four}Exists and B_{twenty four}= Destination
If it is an intersection DSP, it is removed in step 802 and processed.
Be done. Also, B_{twenty one}In the processing of B_{twenty one}= B₁₂So
In step 804, the adjacent intersection B₁₂The degree of is already
Since it is 2, it becomes YES. This is the first
Intersection A₁Intersection B adjacent to₁₂Processed as (as above
(A) to (C) data has been stored)
However, in this case, the adjacent intersection B₁₂Intersection Net Relating to
From the destination intersection DSP registered in strike CRNL
Total distance D '= Bd₁₂And this time, I got it in step 803
The magnitude of the distance D is compared (step 810).

If D <D ', the adjacent intersection B
The i-th intersection A ₁ stored in the item (34) in FIG. 2 of the intersection netlist CRNL of ₁₂ (= B ₂₁ ).
The intersection sequential number is replaced with the intersection sequential number of the ith intersection A ₂ currently being focused on, and the cumulative distance D ′ is rewritten with D = Bd ₂₁ (step 811), and thereafter, the process returns to step 802. Also, D ≧
In the case of D ′, the intersection netlist CRNL of the intersection B ₁₂ (= B ₂₁ ) in FIG.
The procedure returns to step 802 without changing the contents of 4).

With respect to the intersection A ₂ , when the predetermined processing for each adjacent intersection is completed, subsequently, the same processing is performed by setting A ₃ as the primary intersection. Then, if another primary intersection does not exist in step 806, it is checked whether or not the vehicle has reached an expressway or a national road (step 807),
Since i has not yet been incremented, i is incremented to 2 (step 808). Then, the process proceeds to step 802, and the same processing as described above is sequentially repeated. In the check in step 807, the upper road identification data is included in all the (i + 1) th intersections, and when the determination is YES, the intersection is The upper-layer end point intersection DA is stored, and the upper-layer end point intersection DA and the intersection net list CRNL related to the upper-layer end point intersection SA (m-th order intersection) are stored as the item (34) in FIG. , The intersection of the (m-1) th intersection, which is stored in the intersection netlist CRNL, and the (m-2) th intersection, which is stored in the intersection netlist CRNL of the second intersection. A certain crossing,
The 0th-order intersection = destination intersection DSP stored in the intersection netlist CRNL related to the primary intersection is sequentially connected in the order from the upper-layer end-point intersection side toward the destination-intersection side to determine the shortest route (step 812). . At this time, the upper-layer end point intersection is registered in the route search memory 15h.

Then, among the obtained shortest routes, between adjacent intersections of each phase, the road list RDLT is used to determine the intersection using the road type ((13) in FIG. 2 etc.) of the intersection net list CRNL. A simple node on the link connecting the two is searched for, interpolated, and the final node sequence forming the optimum route from the upper layer end point intersection DA to the destination intersection DSP is stored in the guide route storage unit 15g as guide route data. The route search process ends (step 813).

Then, the optimum route search unit 15g proceeds to step 611 of FIG. 9 and refers to the upper layer node identification flag relating to the upper layer end point intersection DA in the same manner as described above, and determines that the same intersection as the upper layer is the upper layer node. Check whether it exists in the road data, and if it exists, (10) in FIG.
The upper-layer intersection sequential number registered in the route registration memory 15h is registered in the route search memory 15h (step 612), and if it does not exist as an intersection in the upper layer, it is treated as a pseudo-intersection in the upper layer, and an intersection netlist is additionally created in the upper layer to generate a route. It is stored in the search memory 15h (step 613), and the intersection sequential number of the added intersection net list is registered (step 612).

After determining the first route and the second route in the lower layer, the optimum route searching unit 15g uses the upper layer intersection netlist stored in the route search memory 15h by the Dijkstra method to determine the upper layer starting point intersection SA. The shortest optimum route (third route) connecting from to the upper layer end intersection DA is obtained (step 901 in FIG. 12). Even if the upper-layer origin intersection SA and the upper-layer end intersection DA are originally not defined in the map data of the upper-layer leaf, as described above, the upper-layer intersection netlist is added as a pseudo-intersection in the upper layer. Therefore, the third route can be reliably obtained by the Dijkstra method. The specific method of obtaining the third route is exactly the same as in the flow of FIG. 8, and thus the details are omitted, but instead of the starting point intersection STP, the upper layer starting point intersection SA, and instead of the destination intersection DSP, the upper layer ending point intersection. DA. Then, of the third routes obtained by the Dijkstra method, between the adjacent intersections of each phase, the road type of the intersection netlist CRNL ((13) in FIG. 2).
Etc.), the intersection ID, etc. are used to search for a simple node on the link connecting the intersections from the road list RDLT and interpolate the final node to form the optimum route from the upper layer start intersection DA to the upper layer end intersection DA. The column is stored in the guide route storage unit 15g as the third route data (step 902). At this time, using the map data of the lower layer,
Fine node interpolation may be performed. Then, the first route data, the third route data, and the second route data are combined in this order with respect to the first and second route data obtained earlier, and the overall guide route data is obtained (step 903).

Here, the third route is along the highway or the national highway here, but the first route and the second route are along the highways and roads other than the national highway. The overall guidance route does not include a U-turn route, and the first route and the second route are the shortest route connecting the departure point STP and the nearest highway or national road, respectively, and the destination. Since it is the shortest route that connects the DSP and the nearest highway or national road, no detour occurs as shown by the one-dot chain line AB in FIG.

Route guidance In this way, when the start key is pressed after the search for the optimum route is completed, the upper layer map including the vehicle position is based on the vehicle position data input from the vehicle position detection unit 13 by the map image drawing unit 15a. Of the map data is read from the CD-ROM 11 to the buffer memory 15b and drawn on the video RAM 15d. On the other hand, the guide route drawing unit 15c selects a portion within the area drawn in the video RAM 15d from the guide route data stored in the guide route storage unit 15i based on the vehicle position data, and displays the guide route in the video RAM 15d in a predetermined color. To highlight boldly. In response to the read control of the map image drawing unit 15a, the read control unit 15e cuts out a map image of one screen centered on the vehicle position from the map images drawn in the video RAM 15d, and the combining unit 15j.
Output to. The vehicle position mark generation unit 15f also generates a predetermined vehicle position mark and outputs it to the synthesis unit 15j.
The synthesizing unit 15j synthesizes the vehicle position mark with the map image including the emphasized guidance route, outputs it to the display device 12, and displays it on the screen (steps 904 and 905).

After that, the map display control device 15 displays the information shown in FIG.
If the map enlargement / reduction key is pressed on the operation unit 14 (step 1001), the route guidance mode key is pressed (step 1002), or the destination is reached (step 1003), the power is turned off. Check whether it has been done (step 1004). The map display control device 15 is shown in FIGS.
5 is stopped while the process of FIG. 5 is being performed, and the interrupt process is restarted at the point where the flow of FIG. Therefore, each time the vehicle position changes, the vehicle position mark is located in the center of the screen, the map image scrolls along with the emphasis guidance route, and the screen always shows the departure point intersection S.
Since the guide route for traveling from the TP to the destination intersection DSP is displayed, the driver can correctly reach the desired destination. In addition, since there is no U-turn route in the guide route displayed on the screen, there is no fear that the direction toward the destination cannot be known or that the vehicle may run unnecessarily.

However, after pressing the start key, a map image is displayed based on the upper layer map leaf, so the departure point STP
From the road to the intersection SA, except for the highways and national roads, only the first route is displayed. Therefore, if you want to know the detailed road conditions around the first route, press the expansion key on the operation unit 14 to display the lower layer. An enlarged map image (including the emphasis guidance route) based on the map leaf may be displayed (steps 1001 and 100).
Five). Since the guide route data stored in the guide route storage unit 15i is subjected to node interpolation with respect to the intersection sequence obtained by the Dijkstra method and the node interval is narrowed, even with an enlarged map image, sufficient accuracy is obtained. The guide route display of is obtained.

After that, when the vehicle travels and the vehicle position reaches the destination DSP or the route guidance key is pressed again, the map display control device 15 cancels the guidance route mode and performs the normal guidance. Return to mode (step 1003,
1006, 1007, or steps 1002, 1006, 1007). In addition, when the power of the vehicle-mounted navigator is turned off during the normal guidance mode, a predetermined power-off process is performed. The intersection netlist is backed up (steps 113 and 116 in FIG. 4).
Therefore, when the power is turned on next time, the process of step 103 in FIG. 4 is unnecessary. Further, when the power of the vehicle-mounted navigator is turned off while the vehicle is traveling in the route guidance mode, a predetermined power-off process is performed.
The intersection netlist created based on the lower-layer map around the vehicle position and the guide route data stored in the guide route storage unit 15i stored in h are backed up (steps 1104 and 1108 in FIG. 13). ). For this reason,
Even when the power is turned on, the route guidance can be continued (steps 101 and 102 in FIG. 4, the flow in FIG. 13).

In the above-described embodiment, the lower-layer intersection netlist around the departure place is sequentially created and updated and stored in the route search memory 15h while the vehicle is traveling in the normal guidance mode. Although it is configured to hold the four-divided map leaves, the number may be less than or more than nine, or may be held in the illustrated leaf units instead of in the divided graph leaf units. Further, the lower-layer intersection netlist around the departure place may be created in the route guidance mode when the destination is input, instead of sequentially creating it while traveling in the normal guidance mode. Further, the departure place of the route search is the own vehicle position when the route guidance mode is set, but it may be set by the driver using the operation unit. In addition, the scale level is 2
Although described as a layer, if the map data stored in the CD-ROM is composed of three or more layers, if the starting point and the destination are very far apart, the route should be divided into three or more layers for route search. May be. The intersection netlist is C
The map display control device creates the map data from the map data stored in the D-ROM. However, the created map data is stored in advance in the data unit of the map data on the CD-ROM, and the necessary intersection net is created. The list may be read from the CD-ROM and used.

Further, the node density is increased for the route data obtained by the Dijkstra method to increase the data density, but the interpolation is not always necessary. Further, instead of interpolating the node at the time of route search, in the intersection netlist of the upper layer, the intersection sequential number in the lower layer for the same lower layer intersection as the upper layer intersection is registered,
When the map image is instructed to be enlarged while traveling in the guide route mode, the first route or the second route included in the enlarged map image in the video RAM is node-interpolated by using the road data of the lower layer. However, for the third route, if the corresponding lower layer intersection sequential number is registered in the intersection net list of the intersection at the upper layer intersection forming the third route, the corresponding lower layer is used by using the intersection sequential number. Search for the intersection netlist of, and perform node interpolation using the intersection ID and the like in it and the road data of the lower layer, or at the intersection of the upper layer, in the intersection netlist of the intersection,
If the corresponding lower-layer intersection sequential number is not registered, the upper-layer road data, etc. are used to sequentially interpolate between upper-layer intersections and perform route searches to display highly accurate guidance routes with short node intervals. May be performed.

[0106]

As described above, according to the present invention, by using the lower road data relating to the lower map leaf having a small scale, the nodes forming the lower road exist at the positions closest to the starting point and the destination, respectively. However, with the node on the same road as the road represented by the upper layer road data relating to the upper layer map leaf having a large scale being the upper layer starting point and the upper layer ending point, the optimal first route connecting the starting point to the upper layer starting point and the upper layer While obtaining the optimal second route connecting the end point to the destination, the optimal third route connecting the upper layer start point to the upper layer end point is obtained by the Dijkstra method using the upper layer road data. If the upper layer end point is not an intersection in the upper layer road data, the upper layer start point or the upper layer end point is set as a pseudo intersection in the upper layer road data, and the intersection net related to the pseudo intersection in the upper layer road data is set in advance. Strikes are included, and the obtained optimum first route, third route, and second route are combined in order to form an optimum route connecting the starting point to the destination. It is possible to exclude the roads defined in the upper road data from the optimum route connecting from to the upper layer start point and the optimum route connecting the upper layer end point to the destination. Since the U-turn route is prevented from entering the entire optimum route route to be connected, a proper guide route can be obtained.

Further, the upper layer start point and the upper layer end point are intersections in the lower layer road data, and the upper layer start point and the first route and the upper layer end point and the second route are obtained by the Dijkstra method using the lower layer road data. Thus, the upper layer start point and the first route, and the upper layer end point and the second route can be made optimal in terms of distance.

In addition, information indicating whether or not an intersection is on the same road as the road included in the upper layer road data is included in the lower layer intersection netlist in advance, and the information is referred to during the search by the Dijkstra method. Then, the search for the upper layer start point and the first route and the upper layer end point and the second route is completed when the intersection on the same road as the road included in the upper layer road data is reached. And the upper layer end point can be easily obtained.

When the lower-layer intersection is common with the upper-layer intersection, the lower-layer intersection netlist for the common intersection includes information specifying the upper-layer intersection netlist for the common intersection in advance. By making it possible to specify the intersection netlist of the upper layer corresponding to the upper layer start point and the upper layer end point searched in the lower layer by referring to the information,
The upper layer intersection netlist corresponding to the upper layer start point and the upper layer end point can be easily specified, and the route search processing in the upper layer can be performed quickly.

[Brief description of drawings]

FIG. 1 is an overall configuration diagram of an in-vehicle navigator embodying a route search method of the present invention.

FIG. 2 is an explanatory diagram of an intersection netlist.

FIG. 3 is an explanatory diagram of upper layer existing nodes and upper layer road identification data.

FIG. 4 is a first flowchart showing the operation of the map display control device.

FIG. 5 is a second flowchart showing the operation of the map display control device.

FIG. 6 is a third flowchart showing the operation of the map display control device.

FIG. 7 is a fourth flowchart showing the operation of the map display control device.

FIG. 8 is a fifth flowchart showing the operation of the map display control device.

FIG. 9 is a sixth flowchart showing the operation of the map display control device.

FIG. 10 is a seventh flowchart showing the operation of the map display control device.

FIG. 11 is an eighth flowchart showing the operation of the map display control device.

FIG. 12 is a ninth flowchart showing the operation of the map display control device.

FIG. 13 is a tenth flowchart showing the operation of the map display control device.

FIG. 14 is an explanatory diagram of a method of creating a lower-layer intersection netlist around a vehicle position.

FIG. 15 is an explanatory diagram of a route search when the place of departure is close to the destination.

FIG. 16 is an explanatory diagram of the route search method of the present invention when the distance between the departure place and the destination is long.

FIG. 17 is an explanatory diagram of a route search when the distance between the departure place and the destination is long.

FIG. 18 is an explanatory diagram of a route search when the distance between the departure place and the destination is long.

FIG. 19 is an explanatory diagram of how to hold map data on a CD-ROM.

FIG. 20 is an explanatory diagram showing a data structure of a road layer.

FIG. 21 is an explanatory diagram of an adjacent node.

FIG. 22 is an explanatory diagram of a drawing leaf for which an intersection netlist is created.

FIG. 23 is an explanatory diagram of the Dijkstra method.

FIG. 24 is an explanatory diagram of a conventional route search method when the distance between the departure place and the destination is long.

[Explanation of symbols]

 11 map information storage unit (CD-ROM) 12 display device 14 operation unit 15 map display control device 15c guide route drawing unit 15g optimum route search unit 15h route search memory 15i guide route storage unit

Claims (4)

[Claims] 1. A route search method for obtaining an optimum route connecting a starting point to a destination by a Dijkstra method using road data such as an intersection netlist, using lower layer road data relating to a lower layer map leaf having a small scale. hand,
Among the nodes that make up the lower layer road, the nodes on the same road as the roads that are located closest to the starting point and the destination and are represented by the upper layer road data related to the large-scale upper layer map leaf While determining the optimal first route connecting the starting point and the upper layer starting point and the optimal second route connecting the upper layer ending point and the destination while using the starting point and the upper layer ending point, from the upper layer starting point using the upper layer road data An optimum third route connecting to the upper layer end point is obtained by the Dijkstra method. At this time, when the upper layer start point or the upper layer end point is not an intersection in the upper layer road data, the upper layer start point or the upper layer end point is simulated by the upper layer road data. As an intersection, the road data of the upper layer should include an intersection netlist related to the pseudo intersection in advance, and the obtained optimum first route, third route, and second route are sequentially set. Route searching method that is characterized in that an optimum route connecting to the destination from the combined and departure. 2. The upper layer start point and the upper layer end point are intersections in the lower layer road data, and the lower layer road data is used to
The route search method according to claim 1, wherein the upper layer start point and the first route and the upper layer end point and the second route are obtained by the Dijkstra method. 3. An intersection netlist of a lower layer includes information indicating in advance whether or not it is an intersection on the same road as the road included in the upper layer road data, and the information is referred to during the search by the Dijkstra method. The search for the upper layer start point and the first route and the upper layer end point and the second route is ended when the vehicle reaches an intersection on the same road as the road included in the upper layer road data. The route search method described. 4. When the intersection of the lower layer is common with the intersection of the upper layer, information for specifying the intersection netlist of the upper layer of the common intersection is included in advance in the intersection netlist of the lower layer for the common intersection. The route search method according to claim 2, wherein the intersection netlist of the upper layer corresponding to the upper layer start point and the upper layer end point searched in the lower layer can be identified by referring to the information.