JPH05134601A - Route searching device for vehicle - Google Patents

Abstract

PURPOSE:To attain smooth transition between hierarchies in a multi-hierarchy route search. CONSTITUTION:A route searching part 14 executes a route search to the destination inputted from an input part 10 by utilizing data of a road network data storage part. At the time of data expansion from each intersection, in the case both intersections of a superordinate hierarchy and a subordinate hierarchy are connected with regard to the same connecting road, the data is expanded to the intersection of the superordinate hierarchy, and in the case of a road to which only the intersection of the subordinate hierarchy is connected, the data is expanded to the intersection of the subordinate hierarchy only in the case the original intersection is not one which connects the superordinate hierarchy and the subordinate hierarchy. Accordingly, the transition to the road of the superordinate hierarchy is executed automatically and a route search can be executed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicle route searching device for searching a travel route to a destination, and more particularly to a device for efficiently searching according to the type of road.

[0002]

2. Description of the Related Art Conventionally, various types of navigation devices have been known, and these are now being installed in ordinary passenger cars. This navigation device
It stores data about road maps inside,
Some drivers have a function of searching a route from the current position to the destination when the driver inputs the destination. By using such a function, even when driving to the destination for the first time, the route can be easily known and an appropriate road can be selected.

Heretofore, various methods for searching for the optimum route from the present location to the destination have been proposed in the past, but a method for accelerating the search by hierarchizing and storing the road network has been proposed. .. That is, in Japanese Unexamined Patent Publication No. 1-250200, the road network is divided into a plurality of stages of hierarchical data and stored. For example, in the case of two-level hierarchical data, the data about the entire road network is stored in the lower layer, and the connecting intersection information with the upper layer is also stored. On the other hand, in the upper layer, only data about the highway network is stored. The search is performed by the Dijkstra method, and the road network of the lower hierarchy is used near the starting point and the destination point, and the road network of the higher hierarchy is used for the other search. According to this, the number of intersections and the number of roads to be considered are reduced by the search using the data of the upper layer, and the search can be speeded up. Further, in this conventional technology, as an algorithm for transition between layers, a search is performed by the data of the lower layer up to the nearest layer connection point, and the search is shifted to the data of the upper layer from that point. There is.

[0004]

Thus, by hierarchizing the road data, it is possible to speed up the search. However, if the search for a hierarchical connection point is made the hierarchical connection point with the shortest connection distance from the starting point (or destination point), and the hierarchical connection point closest to the starting point is in the opposite direction to the destination point. However, there is a problem that a U-turn route or a large-around line may be obtained. That is, by selecting the hierarchical connection point obtained in this way, a route that moves once in the opposite direction to the destination point and then moves to the road of the upper hierarchical level is selected.

Further, according to Japanese Patent Laid-Open No. 2-56591, as an algorithm for transition between layers, all hierarchical connection points of the database in the block being searched are searched,
The method of obtaining the optimum hierarchical connection point is adopted. However, according to this method, most of the points in the table of the lower hierarchy are searched for in order to obtain the hierarchy connection point, and this processing takes time, and there is a problem that speedup cannot be achieved. there were.

The present invention has been made to solve the above problems, and it is an object of the present invention to provide a route search device capable of smoothly moving between layers and finding an appropriate route more quickly. To aim.

[0007]

In order to achieve the above-mentioned object, the present invention has intersection data connected to each intersection via a road, and is sequentially connected based on this intersection data. Select the intersection and expand the data,
In a vehicle route search device that searches for a route from a departure point to a destination, the intersection data is data of both an intersection of an upper hierarchy and an intersection of a lower hierarchy connected to the intersection via a road, and Data that indicates whether the intersection connects upper and lower floors, and when the data from each intersection is expanded, both upper and lower intersections are connected for the same connecting road. If there is, expand the data at the intersection of the upper hierarchy,
For roads that connect only lower-level intersections, determine whether the underlying intersection connects upper and lower levels,
The feature is that the route search is performed by expanding the data at the intersection of the lower hierarchy only when the connection is not made.

[0008]

The vehicle route search device according to the present invention has the above-mentioned configuration, and when the data is developed from each intersection, the same connecting road can be used for both the upper layer and the lower layer. If the intersection is connected, the data is expanded for the upper-level intersection, and if the road is connected only to the lower-level intersection, it is determined whether the original intersection is an intersection connecting the upper and lower levels. If the intersection is a hierarchy only, the data is expanded to the intersection of the lower hierarchy. On the other hand, if the intersection connects the upper and lower hierarchies, the data is not expanded to the intersection of the lower hierarchy. By such an operation, even when the data of the upper layer and the lower layer are stored in the same file, the data can be expanded by automatically shifting from the lower layer to the upper layer, and the road of the upper layer is given priority. A route search can be performed.

[0009]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing a schematic configuration of the present invention. An input unit 10 for inputting various data and a road network data storage unit 12 for storing data about a road network.
And a route search unit 14 that performs actual route search processing, and a display unit 16 that displays results and guides input. The input unit 10 includes a touch panel provided on the display unit 16 including a color liquid crystal display,
It is composed of a plurality of push buttons and the like, and the road network data storage unit 12 is composed of a CDROM and the like. In addition, the route search unit 14 uses a normal CPU and RA.
It is composed of M and the like.

The operation of such an apparatus will be described with reference to the flowchart of FIG. First, when the mode for starting the route search is set, a search start point and a destination point are selected (S101). As the search start point, the route search unit 14 usually automatically selects the intersection closest to the current location, but the driver may also input it. Also, the selection of the target point is
The operation is performed on the map displayed on the display unit 16 by operating the input unit 10. The current position is recognized by GPS (Global Positioning System) or dead reckoning.

Next, an actual search operation is performed. In the present embodiment, the route search is performed by the Nicholson algorithm. Therefore, as the next step, the node to be expanded next is selected (S102). According to the Nicholson method algorithm, the data is developed not only from the starting point side to the destination point side but from both the starting point and the destination point. Then, the route search adds costs from one intersection to all the intersections connected here,
Label the next intersection. Therefore, the selection of the node (intersection) to be expanded next is to compare the node with the minimum label on the start point side with the node with the minimum label on the destination point side and select the smaller one as the next expansion node. means. As a result, expansion is performed from both the start point side and the destination point side.

Next, the label for the connection node of the expanded node is updated (S103). As a result, the labels of all the nodes connected to the selected node are updated. Note that this label is updated only when the new label is smaller than the existing label. Therefore, no U-turn is made and the label is not updated for the already searched node.

Then, it is determined whether or not the shortest route has been obtained (S104), and if it has not been obtained, the process returns to S102 and is repeated until the shortest route is obtained. The determination as to whether or not the shortest route has been obtained is made based on the fact that the minimum label value on the start point side + the minimum label value on the destination point side is equal to or greater than the distance of the shortest route in the formed routes. Various search methods have been known in the past, and the search method is not limited to the Nicholson method and can be appropriately selected.

Structure of Road Network Data Next, the structure of data in the road network data storage unit 12 in this embodiment will be described with reference to FIGS. 3 and 4. FIG. 3 illustrates an example of a road network. In this example, there are two hierarchies: a higher hierarchy (a trunk network composed of trunks such as highways and national roads) and a lower hierarchy (a road network composed of all roads). All roads and intersections are stored according to this hierarchy. That is, the intersections 3, 4 in FIG.
9 and 12 are intersections of both upper and lower layers,
The thick lines in the figure represent roads in the upper hierarchy.
Then, the intersections 1, 2, 11 are intersections of the lower layer that are connected only to the roads of the lower layer. Also, at intersection 5,
Although 6, 7, 8, and 10 are connected to roads in the upper layer, they are intersections in the lower layer. The numbers shown along the road represent the distance of the road between the intersections.

The data on the road network shown in FIG. 3 is set as data for each intersection as shown in FIG. That is, the data for each intersection indicates that the intersection number is a number that identifies this intersection, the number of connecting roads that represents the total number of roads connected to the intersection, and the intersection that connects the lower layer and the upper layer. It is made up of data on a hierarchical connection point flag and connection roads.
The data about the connecting roads includes, for each road to be connected, the intersection number of the connection destination in the lower layer, the distance to the intersection, and the number and distance of the connection destination in the upper layer.

Therefore, in the case of the intersection with the intersection number 4, the number of roads connected here is 4, and the hierarchical connection point flag is 1. This hierarchical connection point flag is set to 1 when it is a connection point and 0 when it is not a connection point. The data on the connecting roads are sequentially stored in a clockwise direction from true north. Therefore, connecting road 1 is the first road,
An intersection 1 of a lower hierarchy is connected to this connecting road 1. Therefore, the connection number is 1 and 2 is described as the distance. On the other hand, the connecting road 1 extending above the intersection 4 is a road of the lower hierarchy, and the intersection of the upper hierarchy is not connected here.

Therefore, the connection destination number and the distance data of the upper layer of the connection road 1 are both set to 0. Next, for the connecting road 2, 5 is selected as the connecting destination intersection number of the lower layer, and the distance 4 to that is stored. The connecting road 2 is a road of an upper layer, and an intersection number 9 is connected as an intersection of the upper layer. Therefore, as the data of the upper hierarchy of the data about the connection road 2, 9 is stored as the connection number and 39 is the distance. Similarly, on the connecting road 3, the intersection 10 of the lower hierarchy and the intersection 12 of the upper hierarchy are selected, and for the connecting road 4, the lower and upper common intersection number 3 is selected.

On the other hand, in the data of the intersection 5 of the lower hierarchy, the number of connecting roads is 4, but the hierarchy connecting point flag is 0. This is because the intersection 5 is provided on the road of the upper hierarchy, but is not the intersection of the upper hierarchy. Then, the lower layer connection destination number of the connection road 1 is 2, and the upper connection destination number is 0. In connection road 2, the lower layer connection destination number is 6 and the upper layer connection number is 9
Becomes

As described above, all the data for each intersection has data for both the upper layer and the lower layer, and also has the layer connection point flag. Therefore, a suitable route search including the transition between the two layers is performed using these data.

Selection of a connection node, that is, updating of the connection destination label in S103 in FIG. First, data is expanded from the original intersection to the intersection connected to it. First, the upper connection point of the connecting road is 0.
(S201). That is, in the case of the data of the intersection number 4 in FIG. 4, the upper connection destination number of the connection road 1 is 0. Therefore, in this case, the determination is YES, and the determination is NO for the connecting roads 2 to 4 with the intersection number 4. Then, in the case of NO in S201, the development has already started from the intersection of the upper hierarchy, and the upper connection destination is selected (S202), and the label of the connection destination is updated (S203).

When the result in S201 is YES, only intersections of lower levels are connected to this road. In this case, it is then determined whether or not the expansion source intersection is a hierarchical connection point (S204). This decision is
This is performed depending on whether or not the hierarchical connection point flag of data is 1.

On the other hand, in the case of the intersection with the intersection number 4 described above, this determination is made on the connection road 1 and the hierarchical connection point flag is 1, so the label update processing is not performed (S205). This is because, in the case of the intersection with the intersection number 4, it is already the intersection of the upper layer and does not move to the lower layer.

When the result in S204 is NO, this intersection is an intersection of a lower hierarchy, and the intersection of the lower hierarchy must be included before the expansion. Therefore, the lower connection destination is selected (S206), and the label of the connection destination is updated (S203). As described above, according to this embodiment, even if the data of both the upper layer and the lower layer are stored in one data table, the data of the upper layer can be expanded to the intersection of the upper layer without fail. At the connection point between the upper layer and the lower layer, the transition from the lower layer to the upper layer can be automatically performed. And
In order to expand the data from both the starting point and the destination point, if there is a road in the upper layer, the road is always moved to the upper layer by the expansion, and the shortest route can be searched at high speed by expanding the upper layers.

Other Configuration Examples Even after once entering the upper layer, it may be required to search the connection point of the lower layer. In this case, S204 in FIG. 5 may be omitted. Therefore, an appropriate changeover switch may be provided so that whether or not to make this determination can be changed over.

[0025]

As described above, according to the vehicle route search device of the present invention, the route table of the upper and lower layers can be easily performed by the data table having the simple structure, and the route search can be performed at high speed. It can be performed.

[Brief description of drawings]

FIG. 1 is a block diagram showing a schematic configuration of a vehicle route search device according to the present invention.

FIG. 2 is a flowchart illustrating the overall operation of the same embodiment.

FIG. 3 is an explanatory diagram of a configuration example of a road network.

FIG. 4 is an explanatory diagram of a configuration example of a data table.

FIG. 5 is a flowchart illustrating an operation of selecting a connecting intersection.

[Explanation of symbols]

 10 input unit 12 road network data storage unit 14 route search unit 16 display unit

Claims (1)

[Claims] 1. Intersection data connected via a road to each intersection, and based on the intersection data,
In a vehicle route search device that selects intersections that are sequentially connected and develops data, and searches for a route from a departure point to a destination, the intersection data is an upper layer that is connected to the intersection via a road. Data of both intersections and lower level intersections, and data indicating whether or not the intersections connect upper and lower levels. When developing data from each intersection, , If both upper and lower intersections are connected, expand the data to the upper intersection, and if the road is connected only to lower intersections, the base intersection is the upper and lower To determine whether to connect
A route search device for a vehicle, which develops data at an intersection of a lower hierarchy and performs a route search only when the route is not connected.