JPH0256591A - Route searching method - Google Patents

Abstract

PURPOSE:To speed up search processing by storing road network data such as intersection data and road data in hierarchic structure and making a search from a low layer to a high layer in order. CONSTITUTION:For example, a start point and a destination are indicated by an intersection number I in a block 1 in a layer 1 and an intersection number III in a block 6. Intersection numbers in the high layer are found, a route up to intersection numbers III and IV is searched for, and the high layer is entered. The intersection number III in the block 6 moves up to the high layer as it is since there is an intersection number VIII in the layer 1 of the high layer. In the layer 1 of the high layer, the route from the intersection number I or II to the intersection number VIII is searched for in the layer 1 of the high layer in combination with information searched for in the layer 1. Consequently, the calculation time for the route search can be shortened.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a route search method for a navigation device that uses map data in a hierarchical structure to search for a route.

[Conventional technology]

Navigation devices provide route guidance to destinations for drivers who are unfamiliar with geography, and navigation devices have been actively developed in recent years.

A navigation device sets a route from a starting point to a destination by inputting a starting point and a destination in advance before traveling, and performs navigation according to the set route. In navigation, when instructing a route, a map is displayed on a CRT screen and the route is superimposed on it, or information about the next intersection to turn at according to a preset route is displayed. Some display the distance to the intersection at which you should turn using numbers, graphs, or distinctive photographs, and even provide audio output.

In a road network, there are generally multiple routes between a starting point and a destination.

Therefore, in navigation devices, attempts have been made to adopt a route search method in which, when a departure point and a destination are manually entered, a route with the shortest time or shortest distance (shortest route) between them is searched. One of them is
For example, in the case of a four-way intersection, the intersection is represented by 8 nodes and 16 directed links to express left/right turns, going straight, and U-turns, and the road technique to connect the intersections is 2 trees. A method of representing the information using directed links has been reported.

The other method is to search for the shortest route that does not include the prohibited route by comparing it with the prohibited route after searching for the shortest route and removing the shortest route that includes the prohibited route (for example, Japanese Patent Laid-Open No. 62-91811 No. 2) has been proposed.

[Problems to be Solved by the Invention] However, in the former method, all the right/left turn information at intersections is expressed as directed links, so there is a problem that the amount of data increases and the storage capacity increases. In addition, with the conventional data structure, if you try to search for a route in the shortest time by detecting left or right turns and weighting them according to the left or right turns,
Calculations for determining whether to turn left or right become complicated and time-consuming. In particular, when a four-way intersection is represented by eight nodes and 16 directed links, the amount of data increases because it is necessary to have weighted distance or time data for the 16 directed links. There will be more.

Additionally, in route searches, the longer the distance from the starting point to the destination, or the higher the density of the road network, the more intersections will be searched for the route.

Therefore, there is a problem that the calculation time required for route searching and the storage capacity of memory used during the search process increase.

The present invention is intended to solve the above-mentioned problems, and an object of the present invention is to provide a route search method that reduces calculation time for route search.

[Means to solve the problem]

To this end, the present invention provides a route search method for a navigation device that sets a route from a designated departure point to a destination and guides the user along the set route, in which the map data used for route search is structured in a hierarchical structure, A branch road network connected to the main road network is developed for the upper layer of the road network, and the network is divided into blocks, and the search from the lower layer to the intersection connected to the road network of the upper layer is sequentially repeated from the starting point. It is characterized by searching for a route to a destination. In addition, as map data, each block in each layer has connection information about intersections and roads between intersections, and connection intersection information with the upper layer, and the number of divided blocks in the lower layer is increased according to the amount of information. The search is repeated from the lower hierarchy until the block at the destination and the destination block become the same block or adjacent blocks, moving up to the upper hierarchy.

[Operations and Effects of the Invention] In the route search method of the present invention, first, when a route search is performed using a block including a departure point and a destination in the lowest hierarchy,
If it has an intersection number of a higher layer, the route search is performed using the block of that layer. If it does not have an intersection number in a higher hierarchy, a route search is performed from that intersection to an intersection with an intersection number in an upper hierarchy, and then it moves to a block in a higher hierarchy. Then, when the seven blocks of the starting point and the seven destination blocks become the same block or adjacent blocks, the route search from the starting point to the destination is finished between them.

Therefore, by setting block units for each layer so that the amount of data is the same, even if the road network is complex and has a large amount of information, it is only necessary to repeatedly search for a route within the same capacity. Therefore, the storage capacity required for the route search may be small, the route search can be performed efficiently, and the calculation time for the route search can be shortened.

[Example] Examples will be described below with reference to the drawings.

FIG. 1 is a diagram for explaining one embodiment of the route searching method according to the present invention.

In FIG. 1, layer l has intersection numbers 1, ■, ■,
It is a map of the main trunk road network with..., and is composed of one block 1. Layer 2 is a map that also includes branch road networks connected to the main trunk road network of Layer 1, and is composed of six blocks 1 to 6. The connection road between blocks includes layer 2 block l,
As shown in the intersection numbers ■ and H between 2, pseudo intersections are set so that a processing unit can be composed of blocks. The number of blocks is set so that each block has approximately the same amount of information. Therefore, block 1 of layer 1 and blocks 1 to 6 of layer 2 each have the same amount of information as road network data.

As described above, the route search method of the present invention uses, as map data, a hierarchical structure consisting of layers 1, 2, etc., which are expanded downward from main lines to branch lines and divided into blocks. It searches for a route from a place to a destination. Therefore, if there are further branch roads below the layer 2 road network, layer 3 is set,
The number of blocks increases depending on the amount of information. Similarly, when not only block l of layer l but also the surrounding road network is targeted, layer l is composed of block l and the blocks of the surrounding road network.

In this case, a layer above layer 1 is set.

Next, an example of a route search method using the road data shown in FIG. 1 will be explained.

For example, the departure point and destination are both layer 2 blocks.
Assume that the intersection number I is located in , and the intersection number ■ is located in Bronkuro.

First, the starting point of intersection number I in block 1 is an intersection number that is not in layer 1 of the upper hierarchy. Then, find the intersection numbers in layer 1 of the upper layer, and find the intersection numbers ■ and ■ (intersection numbers I and ■ in layer 1)
Explore the route up to and move up to the upper level.

On the other hand, the intersection number ■ in block 6 is listed as intersection number ■ in layer 1 of the upper layer, so it goes up to the upper layer as it is.

In Layer 1 of the upper layer, intersection number ■ is calculated from intersection number I or ■ along with the information searched in Layer 2 of lower layer.
Search the route to.

As is clear from the above example, depending on the block in which the departure point and destination exist, there are three types: (1) the same block, (2) adjacent blocks, and (2) separate blocks. Therefore, the route search method of the present invention performs route searches as follows according to each case.

First, if the departure point and destination in (■) are in the same block, a route search is performed within that block. In addition, if the departure and destination blocks in ■ are adjacent,
Intersections connecting the departure point and destination blocks (connection intersections) are detected, and the route is searched twice: from the departure point to the connection intersection, and from the destination to the connection intersection. However, if the departure point and destination blocks in ■ are far apart, search from the departure point to the intersection connected to the upper layer using the departure point block as in the example above, and do the same. Then, use the destination block to search from the destination to the intersections connected to the upper layer. Then, a similar search is performed in the upper layer until the above conditions (1) or (2) are satisfied.

Next, a specific structural example of road data suitable for use in the above route search method will be shown.

2 is a diagram showing an example of the data structure of block 1 in layer 2 of FIG. 1, FIG. 3 is a diagram showing an example of the data structure of block 4 in layer 2 of FIG. FIG. 5 is a diagram showing an example of the data structure of block 6 in layer 2 of the figure, and FIG. 5 is a diagram showing an example of the data structure of block 1 in layer 1 of the first circle.

The data for each block includes road data ((a) in the figure) and intersection data (as shown in Figures 2 to 5).
It consists of (b)) in the same figure. For example, as shown in Fig. 2, the road data includes, corresponding to each road number in the block, the intersection number of the starting point, the intersection number of the ending point, the road number with the same starting point, the road number with the same ending point, and the guide. unnecessary roads,
It has information such as the relative length of roads and layers. The unit of road number usually consists of a plurality of nodes. Although not shown, the node data is data related to one point on the road, and if the connection between nodes is called an arc, the road is expressed by connecting each of a plurality of node strings with an arc. In addition, the intersection data corresponds to the intersection number in the block, including east longitude, north latitude, exiting road number, entering road number, intersection number in the upper layer, intersection number in the lower layer, and intersection number (connection) in the horizontal block. It has information such as intersection numbers).

Among these, road numbers with the same starting point (end point) and exiting (entering) road numbers are information on connecting roads at intersections, and since there are usually multiple road numbers,
Register the earliest road number among them. In this way, it is easy to search for connecting roads at intersections, as will be described later.

Further, the relative length of a road that does not require guidance or the road is information that is necessary when calculating the actual time required for travel.

For example, even if the roads are the same width and length, the actual driving time on a road that does not require guidance can be converted to be shorter than on a road that requires guidance, and even if the roads are the same length, the driving conditions are poor. If the road is prone to traffic congestion, the relative length will be longer. The layer indicates the rank of the road. In other words, it is information indicating in which order layer the road has it. The intersection number of the upper (lower) layer, for example 1-1-2, indicates the intersection number in layer l-block 1-that layer block. The same applies to the intersection numbers of the horizontal flocks.

Next, the route searching method according to the present invention will be explained according to the process flow.

Figure 6 is a diagram showing the structure of the work file and index file, Figure 7 is a diagram to explain the overall process flow in route search, Figure 8 is a diagram showing an example of the same program search routine, and Figure 9 is a diagram showing the structure of the work file and index file. This figure shows an example of an adjacent block search routine, and FIG. 10 shows an example of a remote block search routine.

The work file is used to read and use intersection data and road data in a block when searching in block units, and as shown in Figure 6 (a), it contains the number of intersections, number of roads, starting point, ending point, It stores information such as the road number entering the intersection obtained as a result of the block search, and flags indicating the starting point and destination of the block search. The index file manages block information,
As shown in FIG. 2(b), it has information such as the number of blocks and block numbers.

As shown in Figure 7, in route searching, first, the positional relationship between the starting point and destination blocks is checked from the index file, and depending on the positional relationship, one of the following methods is used: same block search, adjacent block search, or remote block search. Branch to processing routine.

In the same block search, as shown in FIG. 8, intersection data and road data are input, the work area is initialized, and a starting point and destination are set.

Thereafter, the process branches to a route search subroutine and outputs the route generated there.

In the adjacent block search, the intersection number is expressed as C (layer Bronkou intersection number), the road number is expressed as R (layer Bronkou road number), and the starting point is C (2-1-1).
If the destination is C(2-4-4), the following processing is performed in the steps shown in FIG.

■,■ Read the data of layer 2 and flock 1 where the departure point is located.

■ Store the connecting intersection S in the memory as shown below.

■ Set and initialize all intersections in blocks in the work area as shown below.

Road coming to intersection ←0 Flag ←Unexplored distance ←7 F F F F F F F F
H ■ Departure intersection C in the work area (2-1-
1) Set "temporary" to the flag and "0" to the distance.

■ Continuous intersection (2-1-6), C (2-
1-7).

(2) A search is performed from the starting point intersection C (2-1-1) to the temporary destination continuous intersections (2-1-6) and C (2-1-7).

■,■ Save the work area. At this time, record the distance to the connecting intersection in memory as shown below.1. Revenge.

[Phase] ~ ■ Set the departure point as C (2-4-1) and the destination as the connecting intersection C (2-4-5L C (2-4-4)) ■ ~
Perform the same search as ■.

■～■ Select the connecting intersection that will give you the shortest course. For example, if the distance from the departure point and the distance from the destination are
The connecting intersections are C(2-1-6> and C(2-4-5), which are shorter distances from (6+5)<(11+8).
).

[Phase] Destination block route C (2-4-1) -
Create C (2-4-5).

[Phase] ~ [Phase] Load the work area and start route C (2-1-1) -C (2-1-3)-
Create C(2-1-6).

■ Combine each of the above routes and C(2-1-1
)-C(2-1-3)-C(2-1-6)-(2-4-
1) Output -C(2-4-5).

Next, remote block search will be explained. Here, the departure point is C(2-1-1) and the destination is C(2-6-2).

■～■ Read the data of layer 2, block 1 where the departure point is located.

■ Detect the connecting intersection S2 to the upper layer.

■〜■ Set the departure point to C (2-1-1) and the destination to C (2-
1-3), search as C (2-1-4) and save the work area.

■ Record the distance from the starting point to the connecting intersection S2 in memory 10. do.

■～[Phase] Read the data of layer 2, block 6 where the destination is located.

■ Detect the connection intersection D2 to the upper layer.

@〜■ Set the departure point to C (2-6-2), and the destination to C (2-
6-1), search as C (2-6-3) and save the work area.

■ Store the distance from the starting point to the connecting intersection D2 in memory.

■～■ Input the data of upper layer 1, block l.

[Phase] Connecting intersection 52 (C (1-1-1
), C(1-1-2)). Furthermore, the distance from the departure point to the connecting intersection S2 is set in cents as the initial distance.

[Phase] Connecting intersection D2 (C (1-1-7
), C(1-1-8)).

■ Connecting intersection S2 (C(1-1-1), C(1-1
-2)) to the connecting intersection D2 (C(t-t-7), C
(1-1-8)) Perform a search.

@ Compare the distance from the departure point to the connecting intersection D2 and the distance from the destination to the connecting intersection D2. For example, if the distance from the starting point and the distance from the destination are , the connecting intersections are C(2-6-3) and C(1-1- 8
) is the connecting intersection D2 that provides the shortest route.

0 Layer 1 root C(1-1-8) -C(1-1
-6) -c (1-1-5) -C (1-12) is taken out.

@〜[phase] Load the work area of the starting block, and load the starting block's work area) C(,2-1-4) -C
(2-1-2) -C (2-1-1) is taken out.

@〜[phase] Load the work area of the destination block, and load the destination block's route C(2-6-3)-C(2
-6-2).

@ Combine each of the above routes and create C(2-1-1
) -C(2-1-2) -C(2-1-4)-C(1
-1-5)-C(1-1-6)-C(2-6-3)-
Outputs C(2-6-2).

Next, the route search subroutine will be explained.

FIG. 11 is a diagram showing an example of a route search subroutine.

Here, L (c) is the distance, F (c) is the flag, and R (c
) is the road number passed through, Sll+sl is the intersection number on both sides of the departure point, and eo and e are the intersection numbers on both sides of the destination. In addition, C is the intersection number and flag F (
For c), "0" indicates not searched, "1" indicates searching, and "2" indicates search completed.

■　About all intersections Infinity (■) at distance L (c) Set flag F (c) to "0" (unsearched).

With this initial setting, all intersections will be unexplored,
The distance from the starting point is infinite.

■ Enter the distance from the departure point into the distances L (s, ), l, (S,) corresponding to the intersection numbers So, Sl on both sides of the departure point, and further calculate the intersection numbers s,, S, on both sides of the departure point. , the flag F (s, ) corresponding to .

Enter "l" in F (s, ), and the road number from the departure point in R(c), the road number passed through.

■ Search for the intersection number c0 for which the flag F is not 2J and the distance ML(c) is the minimum.

■ Execute the surrounding road search subroutine and find the intersection number c.
Search surrounding roads starting from 0.

■ Check whether there are any surrounding roads.

In the case of YES, the process moves to the next process (2), and in the case of NO, the process moves to the process (2).

■ Execute the optimal route condition setting subroutine to set road conditions and other conditions for searching for the optimal route.

■ Let CI be the intersection number at the end of the road, and let 2 be the length of the road.

■ Calculate the distance P to the intersection at the end of the road.

Calculate P = L (co) + 42.

Here, t-(co) is the distance from the starting point to the intersection number c0, and P is the distance from the intersection number c0 to the end point, intersection number C2, through that road (the road being searched).

(2) Check whether p<L(ci) and F(ci)≠2.

In the case of YES, the process moves to the next process [phase], and in the case of No, the process returns to process (2).

[Phase] The distance L (CI) from the starting point to the intersection number CI being searched is P, and the flag F of that intersection number C3 is
(ci') is set to "1", and the road number R(CI) passed through until reaching the intersection number C5 is set as the road number being searched.

■ If No in process ■, set F(c,) to “2”
Set to .

■ Execute the termination condition confirmation subroutine.

(2) Check whether the process has ended or not. If NO, return to process (2); if YES, terminate the process.

By performing the above processing, the road number of the optimal course from the departure point to the intersection number is set for each intersection number, corresponding to each intersection number.

Figure 12 is a diagram for explaining the processing flow of the surrounding road search subroutine, Figures 1 and 3 are diagrams for explaining the processing flow of the optimal route condition setting subroutine, and Figure 14 is a diagram for explaining the processing flow of the subroutine for checking termination conditions. FIG. 3 is a diagram for explaining the flow of processing.

The surrounding road search subroutine of process (2) above performs the process shown in FIG. That is, (1) Check whether this is the first search for surrounding roads.

If YES, proceed to process ■; if NO, proceed to process ■
Move to.

■ Extract the road number whose starting point is the current intersection C0 from the intersection data and store it.

■ Refer to the road data and extract the prohibited road with the road number that comes to the intersection C6 being searched for.

■ Check whether the road you just retrieved is a prohibited road.

In the case of YES, the process moves to process (2), and in the case of No, the process moves to the next process (2).

■ Store the road just taken out as a surrounding road and return (move to process ■ in Figure 11).

■ Extract the road number from the road data that has the same starting point as the previously searched road and has the next number.

■ Check whether the initially searched road and the road just retrieved are the same.

In the case of YES, the process moves to the next process (2), and in the case of NO, the process returns to the process (2).

■ Determine that there are no surrounding roads and return.

Further, the optimal route condition setting subroutine of process (2) shown in FIG. 11 above performs the process shown in FIG. 13. That is, (1) Read the relative length i from the road data.

■ Read the non-guidance data of the road that passed through the intersection currently being searched from the road data.

■ Check whether there are any surrounding roads that match the no-guidance data.

If YES, return; if NO, proceed to the next process (2).

(2) Furthermore, add bm to length 2, set the value as new length 2, and return. In other words, compared to intersections that do not require guidance, intersections that require guidance such as turning left or right are equivalent to b
It is evaluated by adding m.

In the end condition confirmation subroutine, as shown in FIG. 14, it is checked whether the intersection number c0 to be searched matches the intersection numbers on both sides of the target, etc., and if they match, for example, an end flag is set.

In this way, in route searching, the shortest route is searched by weighting the distance between intersections, taking into account driving conditions such as the size of surrounding roads and whether road guidance is required or not.

Note that the present invention is not limited to the above embodiments, and various modifications are possible. For example, in the above example, the search is performed by moving up to a higher layer until the starting point and destination are in the same block or adjacent blocks, but in the case of adjacent broncs, the search is also performed and The starting point and destination may be connected by searching within the same block. However, if this is done, even if there is a route between adjacent pronks that is not in the upper layer but is more suitable than the route of the main road in the upper layer, this route will not be set. Therefore, in the case of adjacent blocks, it can be said that it is more efficient to end the route search at that layer.

As is clear from the above description, according to the present invention, road network data such as intersection data and road data is stored in a hierarchical structure, and searches are performed by sequentially moving up from lower layers (layers) to lower layers. The search range can be limited and the search processing speed can be increased. Furthermore, since each layer is divided into blocks according to the amount of data and the search is performed in units of pronks, the work area required for the search can be reduced, and the storage area can be saved.

[Brief explanation of the drawing]

FIG. 1 is a diagram for explaining one embodiment of the route searching method according to the present invention, FIG. 2 is a diagram showing an example of the data structure of block 1 in layer 2 of FIG. 1, and FIG. A diagram showing an example of the data structure of block 4 in layer 2 of the diagram,
Figure 4 is a diagram showing an example of the data structure of block 6 in layer 2 in Figure 1, Figure 5 is a diagram showing an example of the data structure of block 1 in layer 1 in Figure 1, and Figure 6 is a work file. Figure 7 shows the structure of the index file.
The figure is a diagram for explaining the overall processing flow in route search, Figure 8 is a diagram showing an example of the same block search routine, Figure 9 is a diagram showing an example of the adjacent block search routine, and Figure 10 is a diagram showing an example of the adjacent block search routine. Diagram illustrating an example of a block search routine, 1st
Figure 1 is a diagram showing an example of the route search subroutine, Figure 12 is a diagram to explain the process flow of the surrounding road search subroutine, and Figure 13 is a diagram to explain the process flow of the optimal route condition setting subroutine. , FIG. 14 shows the termination condition f(i
FIG. 49 is a diagram for explaining the flow of processing of the No. 49 subroutine. Applicant Aisin AW Co., Ltd. (External 1)
Name) Agent Patent Attorney Abe and Ryukichi (4 others) Figure 2 (a) Figure 1 (b) FuUfufu1 ノQ-1rit Noro Shisoj Figure 3 (a) (b) ) Figure 5 (a) (b) Figure 4 (a) (b) Figure M6 Figure 7 Figure 11 Figure 12

Claims (3)

[Claims] (1) A route search method for a navigation device that sets a route from a specified departure point to a destination and guides the user along the set route, in which the map data used for route search is structured in a hierarchical structure, and the map data used for route search is structured in a hierarchical manner. A branch road network connected to the main road network is developed for the upper layer, and the network is divided into blocks, and the search is sequentially repeated from the lower layer to the intersections connected to the road network of the upper layer, from the departure point to the destination. A route search method characterized by searching for a route. (2) The number of divided blocks in the lower layer is increased according to the amount of information, and the search is repeated from the lower layer to the upper layer until the starting block and destination block are the same block or adjacent blocks. The route searching method according to claim 1. (3) A route search method characterized in that map data includes connection information regarding intersections and roads between intersections and connection intersection information with upper layers for each block in each layer.