JPH04301515A - Route searching apparatus - Google Patents

Abstract

PURPOSE:To obtain a route searching apparatus which can speedily and correctly search for a route with a small quantity of data. CONSTITUTION:Road data formed from a first level to a third level are stored in an external storage device 6. The road data of each level stores the data of roads including overlapping areas of a block sectioned in a road map and the other peripheral blocks adjacent to the block. When a starting point and a destination are designated from an input device 2, a control device 8 selects sequentially from the road data of the lowest level road data including either one of the two points, and one road data including the two points or two road data able to connect the two points by the overlapping area, thereby to determine the road data to be used to search for a route. Then, the route connecting the two points is searched based on the determined road data.

Description

[Detailed description of the invention]

0001

[Industrial Field of Application] The present invention is provided in a vehicle travel guide device (navigation device) that guides the travel route of a vehicle, and based on pre-stored hierarchical map data,
The present invention relates to a route search device that searches for a travel route connecting a departure point and a destination.

0002

2. Description of the Related Art Conventionally, as a route searching device of this type, as disclosed in Japanese Patent Application Laid-Open No. 2-56591,
The road map is divided into multiple blocks, and road information for each block is created for each layer with different block sizes.When the starting point and destination are specified, first the block size is the smallest. At a lower level, it is determined whether there is road information including the departure point and destination within the same block,
If there is road information including a departure point and destination in the same block, a route from the departure point to the destination is searched based on the road information, and if there is no road information including the departure point and destination in the same block, Based on the road information of two blocks that each include a departure point and a destination, a route is searched from the departure point and destination in each block to a connection point that is connected to the road network in an adjacent block. If the connecting points of each block containing the starting point and destination are the same (that is, if the blocks are adjacent), the search results within each block are connected through this connecting point, and the search results from the starting point to the destination are connected. If the connecting points of each block do not match (that is, the blocks are not adjacent), change the layer of road information to be searched to a higher layer and perform the above procedure. It is known that a route is determined from a departure point to a destination by sequentially searching for a route from a lower layer to a higher layer of hierarchical road information.

0003

[Problems to be Solved by the Invention] However, in the conventional device described above, a road map is divided into a plurality of blocks, and the road information of each block is searched as one unit, and the road network within this search block and the roads of adjacent blocks are searched. Connection with the network is based on connection points that represent the points of roads that are divided when the road map is divided into blocks, so the road information for each block may differ from the intersection information that exists on the actual road. Another problem is that it is necessary to store connection point information that does not exist on actual roads, making it troublesome to create map data, and the amount of data increases, making route searching time-consuming. In addition, in the conventional device described above, the search processing differs depending on whether the search blocks from the departure point and the search blocks from the destination are the same or adjacent, so the program capacity of the microcomputer that performs the search processing is large. This also caused the problem that route searching took a long time.

The present invention has been made in view of these problems, and an object of the present invention is to provide a route search device that can quickly and accurately perform route searches using a small amount of data.

[0005]

[Means for Solving the Problems] That is, the present invention has been made to achieve the above object, as shown in FIG. A plurality of pieces of road information in which a predetermined area including an overlapping area with surrounding blocks surrounding the block is stored as one section are stored in map data storage means for each layer in which the size of one block is different, and the above-mentioned information is stored from outside. 2 on the road map
When one point is specified, road information including at least one of the two points specified above is stored in the map data storage means, in order from the lowest level of road information with the smallest block size; and road information that selects one piece of road information that includes the two points or two pieces of road information that can connect the two points based on the overlap area, and determines the road information necessary to connect the two points. The present invention is characterized by comprising a determining means, and a route searching means for searching for a route from one of the two points to the other point based on the road information determined by the road information determining means. The gist is a route search device.

[0006]

[Operation] As described above, in the route searching device of the present invention,
As in the past, the map data storage means stores a plurality of pieces of road information for each layer, but one piece of road information includes not only road information within a block into which a road map is divided, but also road information surrounding that block. Contains road information for areas that overlap with surrounding blocks. Then, when two points on the road map are specified from the outside, the road information determining means selects at least one of the two points specified from the outside in order from the lowest layer of road information stored in the map data storage means. Select road information that includes one point, and one road information that includes those two points, or two road information that can connect those two points using an overlap area, and then select the road information that is necessary to connect those two points. determine information. Then, the route search means searches for a route from one of the two externally specified points to the other point based on the determined road information.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Examples of the present invention will be described below with reference to the drawings. First, FIG. 2 is a block diagram showing a schematic configuration of a vehicle navigation device to which the present invention is applied. As shown in the figure, the navigation device of this embodiment includes switches for inputting the starting point, destination, etc., and sensors for detecting the direction, vehicle speed, etc. for detecting the current position of the vehicle, which changes as the vehicle travels. an input device 2, a display device 4 that displays a road map for driving route guidance, the current position of the vehicle, etc.
It is composed of an external storage device 6 as a map data storage means in which map data is stored in advance, and a control device 8 that searches for a vehicle travel route based on an input signal from the input device 2 and displays the map on the display device 4. has been done.

The external storage device 6 includes data from the first level to the third level.
Hierarchical road information is stored as map data. Here, the first level road information is divided into large areas (hereinafter referred to as "first block") such as Kanto, Tokai, Kinki, Hokuriku, Chugoku, etc., and the whole country is divided into large areas (hereinafter referred to as the first block), such as Kanto-Tokai, Kanto-Kinki, etc. A road consisting only of arterial roads such as national highways and expressways, created as one section that connects each of the first blocks (i.e., includes at least two first blocks), such as Kanto - Chugoku, etc. It is information.

[0009] Second-level road information divides the entire country into blocks (hereinafter referred to as second blocks) of a certain size (for example, 16 km square), and for each second block, the second block is Centered x×x (where x>1
In this embodiment, the road information is created with an area made up of x=5) second blocks as one section, and is made up of the above-mentioned arterial roads and major roads in various places such as prefectural roads.

Furthermore, the third level road information is created by adding one block (ie, the second block) when creating the second level road information to y×y (however, y>1, and in this embodiment Then, divide it into y=4) blocks (hereinafter referred to as the third block), and for each third block, z×z (however, z>1, and this embodiment Here, the road information is created with an area made up of z=3) third blocks as one section, and is made up of the above-mentioned arterial roads and main roads, and local roads such as municipal roads.

[0011] In other words, each of the hierarchical road information from the first level to the third level stored in the external storage device 6 includes the area surrounding the block (i.e., for each block into which the road map is divided). road information including overlapping areas with other blocks) is stored. Furthermore, the second
In the level and third level road information, if the section for which road information is to be created is in a mountainous area or the like and there is no road to be displayed within the section, no road information will be created.

[0012] Next, each of the above road information is such that if the road network in the section is as shown in FIG. 3(a),
Figure 3 (
It is created as shown in b). In other words, each road information is
For each node, there is node number information attached in order to each node, number of connected links information indicating the number of roads (links) connected to each node, and links attached in order to the links connected to each node. It is composed of number information, link standard code information for specifying the link connected to each node, and link distance information representing the distance of the link connected to each node.

[0013] The link standard code is assigned from 1 to the maximum number of links connected to a certain node.
Even if the number of links connected to a node in the upper layer road information decreases, the number does not change. In other words, in the road information at the lowest level (third level in this example), if links 1, 2, 3, and 4 are connected to a specific node, the upper level (that is, the second or first level) The standard code for a link connected to a specific node of road information is 1
, 3, 4, and so on.

[0014] Although not shown in the figure, each link constituting the road network has a national highway,
Type information indicating the type of road such as a prefectural road, road width information indicating the road width, identification information indicating whether it is a toll road or not, and rule information indicating traffic rules such as right and left turns and one-way streets are also attached.
Furthermore, each node includes coordinate information for specifying its position, and identification information indicating that the node is not suitable as the starting or ending point of the search, for example, the connected road (link) is one-way. , node standard code information, etc. for identifying the node are attached.

In the navigation device of this embodiment configured as described above, when a departure point and a destination are inputted from the outside via the input device 2, the control device 8 stores them in the external storage device 6. Search for a route between the starting point and the destination point based on the map data obtained. This search process will be explained below based on the flowcharts shown in FIGS. 4 to 6.

As shown in FIG. 4, when the search process is started, in step 100, search sections necessary for route search are determined in accordance with the procedure shown in FIG. Note that this step 100
The processing corresponds to road information determining means.

That is, as shown in FIG. 5, first step 31
A third level section (starting point third section) K31 that includes the departure point coordinates (start point coordinates) O at 0 and a third level section (end point third section) K32 that includes the destination coordinates (end point coordinates) D. In the following step 320, it is determined whether the calculated starting point third section K31 and end point third section K32 are the same section. As shown in FIG. 7(a), if the third starting point section K31 and the third ending section K32 are the same section, the route from the starting point to the destination can be searched based on the road information of this section, so step 330 Then, it is determined that the search section is one section at the third level, and the process moves to step 440, which will be described later.

On the other hand, in step 320, the starting point third section K3
If it is determined that 1 and the end point third section K32 are not the same section, the process moves to step 340, as shown in FIG. 7(b).
As shown, the starting point third section K31 and the ending point third section K32
It is determined whether route search is possible between the two sections, depending on whether the two sections are adjacent to each other and their overlapping areas overlap. Then, as shown in FIG. 7(b), if the route search is possible using two sections, the starting point third section K31 and the ending point third section K32, the process moves to step 350,
It is determined that the search sections are the two sections at the third level, and the process moves to step 440, which will be described later.

Next, in step 340, if it is determined that the route search cannot be performed in the two sections, the third section K31 at the starting point and the third section K32 at the end point, the process moves to step 360, and the process shown in FIG. ), depending on whether or not the starting point third section K31 and the ending point third section K32 can be connected in an overlapping state by another adjacent third level section K33, the route search is performed using the three sections. determine whether it is possible. Then, as shown in FIG. 7(c), if the route search is possible using the three sections of the starting point third section K31, the ending point third section K32, and the adjacent section K33, the process moves to step 370, and the search section is This third level 3
It is determined that it is a partition, and the process moves to step 440, which will be described later.

In FIG. 7, each block separated by a broken line represents the aforementioned third block, and one section of road information at the third level is composed of 3×3 third blocks as described above. This indicates that it is a region. Further, in step 310, a section in which the starting point coordinate O or the ending point coordinate D exists in the third block located at the center of the third level section is determined as the starting point third section K31 or the ending point third section K32.

[0021] Next, in step 360, if it is determined that the route search cannot be performed using the three sections of the third level, the process moves to step 380, and the search range is extended to the road information of the second level. In order to enlarge, the second level section (starting point second section) K containing the coordinates of the starting point (starting point coordinates) O
21 and the coordinates of the destination (end point coordinates) D. A second level section (end point second section) K22 is calculated. In the subsequent step 390, it is determined whether the calculated starting point second section K21 and ending point second section K22 are the same section, and as shown in FIG. 8(a), the starting point second section K21 and the ending point If the second section K22 is the same section, the road information of this section, the lower starting point third section K31 and the lower end point third section
Since the route from the departure point to the destination can be searched based on the road information of block K32, the process moves to step 400.
It is determined that the search sections are a total of three sections: the starting point third section K31, this second level section, and the end point third section K32, and the process moves to step 440, which will be described later.

On the other hand, in step 390, the starting point second section K2
If it is determined that 1 and the end point second section K22 are not the same section, the process moves to step 410, as shown in FIG. 8(b).
As shown, the starting point second section K21 and the ending point second section K22
It is determined whether route search is possible between the two sections, depending on whether the two sections are adjacent to each other and their overlapping areas overlap. Then, as shown in FIG. 7(b), if the route search is possible using two sections, the starting point second section K21 and the ending point second section K22, the process moves to step 420,
The search sections are the starting point third section K31 and the starting point second section K21.
, the second end point section K22, and the third end point section K32, a total of four sections are determined, and the process moves to step 440, which will be described later.

[0023] Next, in step 410, if it is determined that route search is not possible between the starting point second section K21 and the ending point second section K22, the process moves to step 430.
As shown in FIG. 9, the starting point second section K21 and the ending point second section K
The first level section (first section) K1 containing 22 is calculated, and the search sections are the starting point third section K31 and the starting point second section K2.
1, 1st section K1, end point 2nd section K22, and end point 3rd section
It is determined that there are five sections in total, including section K32, and the process moves to step 440.

In FIGS. 8 and 9, each block separated by a broken line represents the aforementioned second block, and one section of the second level road information is divided into 5×5 second blocks as described above. This indicates that the area consists of blocks.

[0025] Once the search sections have been determined in this manner, the process moves to step 440, and it is determined whether or not there is section data (ie, road information) for all of the determined search sections. In other words, as mentioned above, in the second and third level road information, if the section for which road information is to be created is in a mountainous area, etc., and there is no road to be displayed within the section, the road information will not be displayed. Since no data has been created, it is determined here whether data exists in all of the search sections determined above.

[0026] If it is determined in step 440 that data exists in all the search sections, the process in step 100 is terminated, and if there is a section in which no data exists among the determined search sections, , step 450
, the search section is changed by removing that section, and the process of step 100 ends.

That is, in step 450, for example, the determined search section is "K31" as shown in FIG. 8(b).
, K21, K22, K32", if there is no data for the third section K32 at the end point, then
As shown in FIG. 10(b), when the search section is changed to "K31, K21, K22" and the data of the starting point third section K31 does not exist, the search section is changed to "K31, K21, K22" as shown in FIG. 10(b).
21, K22, K32”. Further, for example, the determined search sections are "K31, K21" as shown in FIG.
.
, K21, K1'', and the starting point third section K31
And when the data of the starting point third section K21 does not exist, the search section is "K1, K22" as shown in FIG. 10(d).
, K32".

Returning to FIG. 4, step 100 as described above
Once the search section is determined in step 110, it is determined whether the search for the last section (search final section) of the determined search sections has been completed.

At this point, the search area has just been determined and the search has not yet been executed, so this step 110
If the answer is negative, the process moves to step 120, and the road information of the determined search section is read. Note that the road information loading process in step 120 is performed for each section in order from the first section (search start section) of the search sections determined above. For example, if the search section is one of the three sections shown in FIG. 7(c) In this case, each time the process of step 120 is executed, the road information is read in the order of starting point third section K31, adjacent section K33, and ending point third section K33.

When the road information is read in step 120 in this way, the process proceeds to step 130, where it is determined whether the current search section into which the road information has been read is the final section, and whether the search section is the final section or not. If so, proceed to step 140, find the node closest to the destination from the coordinates (node coordinates) of each node in that section, and determine this as the destination node.

On the other hand, if it is determined in step 130 that the search section is not the final section, or if the destination node is determined in step 140, the process moves to step 150, where the current search section is searched. Determine whether it is the starting partition. If the search section is a search start section, the process moves to step 160, where the node closest to the starting point is determined from the node coordinates within the section, and this is determined as the start node.

[0032] In step 140 and step 160, the aforementioned identification information attached to each node is used to determine the destination node and start node, respectively. Even if the node closest to the destination (or departure point) Even if the node is not suitable as the end point (or start point) of the search, the node is not set as the target node (or start node).

Next, in step 150, if it is determined that the search section is not the search start section, step 170
to reflect the results of the previous section search in the current search section. In other words, when there are multiple search sections, at least two consecutive search sections have an overlapping region, and some of the previous section results contain information that can be used as is as the search result for the current search section. In step 170, as shown in FIG. 6, the results of the previous partition search are read for each node, and it is determined whether the standard code of the read node matches the node standard code in the current search partition ( Step 510), if the node standard codes match, transfer information such as the weight given to that node during the previous section search as the search result for the current search section (Step 520). When this process is performed for all nodes in the previous section (step 500 - YES), the node with the smallest weight among the transferred node information is set as the start node of the current search section (step 53
0).

[0034] Once the start node of the current search section has been set, the process moves to step 180, where it is determined whether all nodes within the search section have been searched. At this point, since the search has just started, step 18
A negative determination is made at 0, and the process moves to step 190. Then, in step 190, the weight is calculated for each node in order from the start node, and in step 200, it is determined whether the destination node has been reached, and if the destination node has not been reached, the procedure moves to step 180 again. Then, all nodes in the partition are searched, or the weight calculation is repeated until the search node reaches the target node.

For example, when it is determined in step 200 that the search node has reached the destination node, step 21
At 0, it is determined that the search has been successful, the route is determined, and the process ends. In addition, weight calculation is performed for all nodes in the partition in step 190, and step 18
If it is determined in step 0 that the search for all nodes in the section has been completed, the process returns to step 110, where it is determined whether the search for the final section to be searched has been completed. If not, proceed to step 120, read the road information of the next search section, and perform step 130 described above.
If the subsequent processing is executed and it is determined in step 110 that the search for the final search section has been completed, a message indicating that the destination node has been reached is determined in step 200 even though the search for the final search section has been completed. Since it has not been determined, the process proceeds to step 220, where it is determined that the search has failed, and this fact is displayed on the display device 4, and the process ends.

The route search in this embodiment is executed by applying the well-known Dijkstra's algorithm. That is,
In this embodiment, node information and link information are read from the external storage device 6 in order from the starting point node, and coefficients are applied to information such as the distance, type, width, paid/free type, traffic rules, etc. of the link connected to the node. The sum is determined as the weight from the starting node to the node in question (step 190), and the route is determined by sequentially determining the node with the smallest weight (step 210). For example, if the search partition is one partition at the third level shown in FIG. The result is shown in Figure 3(c), and the route is
As shown by arrows in the figure, the nodes are determined in order from the node with node number n1-7, the node with node number n1-4, the node with node number n1-2, and the node with node number n1-1.

It should be noted that weight calculation and the like for such route searching are well known in the art, so detailed explanation will be omitted. In addition, in this embodiment, step 1
The processing of steps 110 to 220 described above, in which a route is searched along the search section determined in step 00, corresponds to the route search means.

As explained above, in this embodiment, road information is not only hierarchically arranged, but also each layer (first, second
, 3rd level) road information is created for each block into which the road map is divided, including the overlap area with surrounding blocks, making it easy to search for routes using adjacent blocks. In order to do this, there is no need to create connection point information that does not actually exist on the road as in the past, and map data to be stored in the external storage device 6 can be easily created using a road map. Furthermore, when performing route searching using two or more sections, there is no need to calculate the weights of connected points as in the past, and the previous search results can be used for nodes within the overlap area. The time required for searching is shortened, and the amount of data can also be reduced.

Furthermore, in this embodiment, the road information at the highest level (that is, the first level) divides the entire country into large regions such as Kanto, Tokai, Kinki, etc., and divides the two first blocks into Since the wide area connecting each area is used as a location division as a relocated tower, even when searching for a route between points with large distances, such as from Tokyo to Hiroshima, by using this first level division, it is possible to As shown in Figure 2, it is possible to search for a route using a maximum of five sections, thereby reducing the route search time and the amount of data.

Furthermore, in this embodiment, since the search section is determined before starting the route search, it is possible to estimate in advance a more rough calculation amount required for the route search. Therefore, the expected search time can be presented to the user. Furthermore, after searching the compartments on the departure point side and the destination side, the division is determined, the next search division is determined, and the route search is performed again. Since there is no need to execute any processing, this can also shorten the search time.

Furthermore, as described above, according to this embodiment, the route search time can be shortened and the amount of route search data can be reduced, so the memory capacity for storing the search results can be reduced. can be made smaller. Furthermore, if there is sufficient memory capacity, the size of the search section can be expanded to improve the optimality of the route.

[0042] In the above embodiment, although it was not explained in detail how the search section is limited and when the positional relationship between the two points, the departure point and the destination, is When determining, a search section pattern corresponding to the positional relationship of the two points is created in advance,
This may be stored in an external storage device together with the map data. In this way, when updating map data, it is also possible to change the search section pattern in accordance with the map data.

[0043] Also, it is possible to set the coefficients used for weight calculation for each section, store them in an external storage device together with the map data, and change the coefficients for each section when performing weight calculations. For example, the optimality of the route can be further improved.

Furthermore, in the above embodiment, one section of road information at the second level consists of 5 x 5 second blocks, and one section of road information at the third level consists of 3 x 3 third blocks. Although it has been explained that a section of road information at each level has an overlapping area with other blocks, it does not have to have the same number of blocks; for example, depending on the density of roads, etc. Accordingly, the second level road information is divided into two types: the second block has 5×5 sections and the 8×8 sections, and the third level road information is divided into the third block 3×3 sections. There may be three types: a partition, a 6×6 partition, and a 12×12 partition.

[0045] When the number of blocks in one section is set variously in this way, the road information of a section with a small number of blocks includes only data representing a section with a large number of blocks that has road information including that section. If the road information of the section with the largest number of blocks is used for the actual search, the amount of map data can be further reduced.

In other words, for example, among the road information for blocks 0 to 15 shown in FIG. 11, the road information for block 0 is set to sections consisting of 6×6 blocks (all sections shown in FIG. 11). , stores the actual map data, 1
For the road information for each block of ~15, set a section consisting of 3 x 3 blocks centered on that block, and indicate that the actual map data is included in the road information for block 0. If the data is stored, it is not necessary to include actual map data in the road information of each block 1 to 15, so the amount of data can be reduced. In this case, when the search section is determined to be a block section of 1 to 15 during route search, 0
It is necessary to use the road information for the blocks of , which increases the search range.
, 11 blocks are determined, route search can be performed using only one piece of road information for block 0, and as a result, the search speed can be improved. It becomes possible.

[0047]

[Effects of the Invention] As detailed above, in the route search device of the present invention, road information is not only hierarchically arranged, but also road information in each layer is divided into blocks into which a road map is divided. , because it is created in a form that includes the overlap area with the surrounding blocks, so it does not actually exist on the road as in the past, because route search is performed using information on two adjacent roads. There is no need to create connection point information, and map data can be easily created from a road map. Furthermore, when searching for a route using multiple road information, there is no need to calculate the weights of connected points as in the past, and when searching for a route in an overlapping area, it is necessary to search for other roads that were searched first. Since the information search results can be used, the time required for the search can be shortened, and the amount of data of the search results can also be reduced.

Furthermore, according to the present invention, since the road information to be used for route searching is determined before starting route searching, it is possible to estimate in advance a more rough calculation amount required for route searching. Therefore, it is also possible to present the expected search time to the user. Furthermore, after searching the compartments on the departure point side and the destination side, the division is determined, the next search division is determined, and the route search is performed again. Since there is no need to execute any processing, this can also shorten the search time.

[Brief explanation of drawings]

FIG. 1 is a block diagram illustrating the configuration of the present invention.

FIG. 2 is a block diagram showing a schematic configuration of a navigation device according to an embodiment.

FIG. 3 is an explanatory diagram showing the structure of road information and route search results based on this road information in the embodiment.

FIG. 4 is a flowchart showing a search process executed by the control device of the embodiment.

FIG. 5 is a flowchart illustrating a procedure for determining a search section in the search process of the embodiment.

FIG. 6 is a flowchart illustrating a procedure for reflecting the previous section search result on the current search section in the search process of the embodiment.

FIG. 7 is an explanatory diagram when search sections are determined only by third-level sections.

FIG. 8 is an explanatory diagram when a search section is determined by sections at the second and third levels.

FIG. 9 is an explanatory diagram when a search section is determined based on first to third level sections.

FIG. 10 is an explanatory diagram illustrating search sections when there is a section in which no data exists among the determined search sections.

FIG. 11 is an explanatory diagram illustrating an example of a method of setting second and third level partitions.

[Explanation of symbols]

2... Input device 4... Display device 6... External storage device 8... Control device K1... First section K21... Starting point second section
K22...End point second section K31...Start point third section K32...End point third section
K33...Adjacent section

Claims (1)

[Claims] Claim 1: A road map is divided into a plurality of blocks of a predetermined size, and a plurality of pieces of road information are created for each block, and each block is a predetermined area including an overlapping area with surrounding blocks surrounding the block. , a map data storage means in which the size of one block is stored for each layer, and when two points on the road map are specified from the outside, the size of one block stored in the map data storage means is stored. Road information that includes at least one of the two points specified above, and one road information that includes the two points, or the overlap area that connects the two points in order from the road information of the lower hierarchy with the smallest value. a road information determining means that selects two possible road information and determines the road information necessary to connect the two points; route searching means for searching for a route from one point to the other point;
A route searching device comprising: