JPH07103773A - Method and device for path calculation - Google Patents

Abstract

PURPOSE:To rewrite a total cost when it is smaller than an upper-limit cost in searching a calculation end link and then abort searching processing for the link of the total cost exceeding the upper-limit cost thereafter for reducing calculation time. CONSTITUTION:An optimum path is calculated by setting the calculation start links to A->B and A->C and a calculation end link to B->F. A CPU reads link data including a destination B from a disk and then creates a link table and then sets the initial value of the total cost to the maximum value. When the search continues and B->F is reached, the CPU judges that the link B->F is the calculation end link and then compares the total cost with the upper-limit cost. Since the upper-limit cost initial value is infinite, the upper-limit value is rewritten to the total cost. In this manner, once the upper-limit cost is rewritten by a finite value, the search for a connection link is aborted for the link of total cost exceeding it, thus eliminating the need for meaningless search for link and hence reducing path calculation time.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention reads out route network data in a range including a departure place (which may be the current position of a vehicle) and a destination from a road map memory in accordance with a destination set by a driver. The present invention relates to a route calculation method and device capable of calculating an optimum route to a destination on the basis of the route network data and showing it to a driver.

[0002]

2. Description of the Related Art Conventionally, there has been known a navigation device developed to display the position and orientation of a vehicle on a screen and to facilitate traveling on a strange land or at night.
The navigation device has a display, an orientation sensor, a distance sensor, a road map memory, and a computer mounted on a vehicle, and is stored in the orientation data input from the orientation sensor, the traveling distance data input from the distance sensor, and the road map memory. The vehicle position is detected based on the matching with the existing road pattern, and this vehicle position is displayed on the display together with the road map.

In this case, in order to select a traveling route from the starting point to the destination, the computer automatically calculates the current route from the starting point to the destination in response to the destination setting input by the driver. A method has been proposed (see Japanese Patent Laid-Open No. 5-53504). This method divides the roads to be calculated into a number of points, and defines the points as nodes.
A route connecting nodes is used as a link, a node or link closest to a starting point (which may be a destination) is a starting point, and a node or link closest to a destination (which may be a starting point) is an end point, and the starting point to the end point This is a method in which all the trees of links leading to are searched, the link costs of the routes forming the tree are sequentially added, and only the route with the lowest link cost to reach the destination or the departure place is selected.

This method is convenient for a driver who does not know the route because the destination can be reliably reached by calculating the route and traveling along the route. The conventionally proposed methods are summarized as the method for calculating the route as follows. Normal Dijkstra method: In the tree search process,
One path with the lowest cost is searched sequentially from the search range,
How to end the loop processing when any route reaches the destination. Potential method: A method of searching all the routes in the search range and selecting the route with the lowest cost.

In the above methods, the Dijkstra's method seems to be excellent in terms of calculation time, but in practice, the process of "sequentially searching for one path with the minimum cost" is required. It takes much longer than the potential method (Kobayashi et al. "Navigation system with recommended route display function" Sumitomo Electric No. 141, PP.1)
55-160, September 1992). If the calculation time is long, the utility value for the driver is significantly reduced, so a method that can shorten the calculation time is desired.

Therefore, the potential method of is currently used.

[0007]

However, recently, the route network database has been enriched, and the potential method tends to increase the calculation time. In detail, conventionally, the number of links in the route network is relatively small, and the number of loops for route calculation is small. However, when the number of links increases by including roads to be calculated, including narrow roads, the tree expands, and the number of link searches increases. This is because in the potential method, it is necessary to search for the number of routes even if the routes are the same but different routes.

As a result, the calculation time is significantly increased.
Therefore, the time ratio of the route calculation processing by the potential method in the whole processing (reading of route network data, rewriting to the link table, route calculation, map display, etc.) has begun to dramatically increase. Therefore, in the end, it has become impossible to expect a reduction in the total time unless the route calculation processing time is shortened. For that purpose, the number of calculation loops must be reduced.

The present invention has been made in view of the above problems, and when the link costs of the paths forming the tree are sequentially added, an upper limit cost is provided so that the number of calculation loops is not increased, and thus the calculation is performed. An object of the present invention is to provide a route calculation method and device that can shorten the time.

[0010]

Before explaining the constitution of the invention for achieving the above-mentioned object, a so-called potential method which is a premise of route calculation will be explained. This potential method starts from the calculation start link and searches for the link connected to it, as described in the "..." part of claim 1, and the total cost of the searched connection link is set in advance. If it becomes smaller than the total cost of the same link, the procedure of rewriting that value to the total cost of the connection link is repeated, and if the search is completed for all links, the link with the minimum total cost is focused on and the optimal route is selected. Is the method of determining.

In the route calculation method according to the first aspect, when the potential method is executed, if the link to be searched is a calculation end link, the total cost thereof is compared with the set value of the upper limit cost to determine the upper limit cost. If it is smaller than the set value of, the upper limit cost is reset to the value of the total cost, and when the step (d) is repeated thereafter, the total cost of the link entered in the second table is referred to, and that is the upper limit cost. If it is higher than that, the processing for the link is terminated without searching for the link.

A route calculation device according to a second aspect is a device for executing the method according to the first aspect.

[0013]

According to this route calculation method and device, if the link to be searched is a calculation end link, the total cost of the link is set as the upper limit cost, and for links with total cost exceeding this upper limit cost, After that, the search process for the connection link is terminated.

As a result, the search is stopped for the route that exceeds the cost of the route that first reaches the calculation end link, so that the number of loops can be prevented from increasing.

[0015]

Embodiments of the present invention will now be described in detail with reference to the accompanying drawings. As shown in FIG. 2, the navigation device for carrying out the route calculation method of the present invention is provided with a direction sensor 1
1, a distance sensor 12, a shift sensor 13, a memory drive 15 for reading stored data from a disk 14 storing road map data and route network data,
The traveling distance detected by the distance sensor 12 and the traveling direction change amount detected by the azimuth sensor 11 are integrated, and the vehicle position is detected based on the comparison between the integrated data and the road map data read from the memory drive 15. Locator 16 and a predetermined range of road maps are read, an optimum route is calculated using route network data, display data for guiding a vehicle is created, and a voice output device 1 is used.
8 and the locator 16 and other various controls, a display 19, and a touch key 20 for setting initial data and the like. A remote control key may be used instead of the touch key 20.

More specifically, the orientation sensor 11
Is for detecting a change in azimuth as the vehicle travels, and a gyro or the like can be used. The distance sensor 12 detects the traveling distance based on the speed of the vehicle or the number of rotations of the wheels, and a wheel speed sensor, a vehicle speed sensor, or the like can be used. The locator 16 integrates the distance data detected by the distance sensor 12 and the azimuth change data detected by the azimuth sensor 11 to calculate traveling locus data, and calculates the traveling locus data and the road data stored in the disk 14. The vehicle position is detected based on comparison with a pattern (so-called map matching method, see Japanese Patent Laid-Open No. 64-53112). A beacon receiver or a GPS receiver may be added to improve the accuracy of position detection.

The display 19 displays a menu screen on a screen such as a CRT or a liquid crystal panel, a road map, a current position and direction of the vehicle, an optimum route, a destination or a landmark. It displays the direction and distance to the destination, and displays the window of the enlarged shape of the complex intersection. A transparent touch key 20 is attached to the display 19. Touch key 20
On the initial setting menu screen, the optimum route selection criteria (shortest time route, shortest distance route, etc.), map magnification, destination, etc. are input. That is, it mediates the dialogue between the route guidance device and the driver.

The disk 14 includes a road map (including highway national roads, urban highways, general national roads, major local roads, general prefectural roads, general city roads of designated cities, and other living roads).
Is divided into meshes, and data in which nodes and links are combined is stored for each mesh. In addition, it may include background data for displaying railways, rivers, place names, famous facilities, points previously registered by the driver, contour lines, and the like.

The mesh is a Japanese road map with a longitude difference of 1
A primary mesh with a vertical and horizontal distance of about 80Km x 80Km divided by 40 degrees and a latitude difference of 40 minutes, and a secondary mesh that divides this primary mesh into 8 equal parts by a total of 10Km x 10Km. It has a double structure with. Here, a node is generally a coordinate position for identifying an intersection or a bend of a road. A node representing the intersection is an intersection node, and a node representing a bend (excluding the intersection) of the road is interpolated. Sometimes called a point node.

A link is a connection of the nodes. Link data includes link numbers, addresses of start and end nodes of links, link distances, directions passing through links, required time in that direction, road types, road widths, traffic regulation data such as one-way roads and toll roads. Become. In this way, since the link data includes the addresses of the start point node and the end point node of the link, the point can be specified only by the link. The link is called an "outgoing link" when the starting point of the link is specified by the link, and the "incoming link" is called when the ending point of the link is specified. Further, since the link data includes the direction of passing through the link, the traveling direction of the vehicle can be identified by identifying one link. FIG. 3 illustrates four outgoing links that specify a crossroads, and FIG. 4 illustrates four incoming links that specify a crossroads. In the following examples, it is assumed that the outgoing link is mainly used to identify the point.

The details of the controller 17 are shown in FIG. The controller 17 has a memory control unit 21 for obtaining necessary data from the disk 14 through the memory drive 15, a voice control unit 25 for uttering a voice electronically recorded in a voice output device, and a display for displaying a necessary image on the display 19. The control unit 22, the input processing unit 23 that processes the input information set by the touch key 20, the vehicle position recognition processing unit 2 that takes in the vehicle position calculated by the locator 16 as data.
4. The route calculation processing unit 26 calculates the optimum route from the destination to the departure place by the potential method.

The route calculation processing unit 26, based on the link information of a certain range including the starting point and the destination extracted from the disk 14, the link table and the arc table for searching the links connected to each link. Create and and calculate the optimal route based on these tables C
It has a PU 26a, a memory 26b that stores a value of an upper limit cost (described later), and a main memory 26c that stores a link table, an arc table, and a pivot table.
In addition, the link table and the arc table are defined in claim 1.
Of the first table, and the pivot table corresponds to the “second table”.

The link table has a sequence number, a mesh number of an exit link, and a link number of a certain range of links including a starting point and a destination taken out from the disk 14.
The mesh number of the approach link, the pointer to the arc table, the road type, the pointer to the previous link (hereinafter referred to as "previous link" or "entry link") on the route of the link, link cost, link length and total cost I remember.

The sequence number is an integer set in ascending order from 0. The link cost is a time expressed in seconds when traveling on the link. Actually, the link cost changes due to traffic congestion, etc., but here the time required for traveling at the legal speed is used. The total cost is the cost to reach the link in consideration of the progress of route calculation. More precisely, the total cost of a certain link is the sum of the arc costs of the links on the route connecting the starting value to the link. Here, the arc means from immediately after the start node of a link to immediately after the start node of the next link, as shown in FIG. 6 (a). As shown in FIG. 6B, the arc cost is the sum of the link cost of the link and the right-left turn or straight-line cost for leaving the link. For example, when entry is prohibited, the straight-line cost is infinite even if the link cost is finite, so the arc cost is also infinite.
If there is a signal, the arc cost is the link cost plus the average signal waiting time when turning right or left or going straight.

Although not shown in the table, the link table has a bit indicating whether or not each link is registered in the pivot table. The arc table has an arc cost for each sequence number, another mesh flag, an arc end identifier indicating whether it is the last arc among the arcs emitted from the same link, a pointer to the link table of the connection link connected to the arc (link table (Indicated by sequence number) is stored.

The arc cost is as described above, but if traffic congestion information of the road is input through the beacon receiver, the arc cost can be changed in consideration thereof. Also, the driver can change the cost according to his / her preference. For example, costs can be raised or lowered only for specific types of roads (highways, ferries, etc.).

Assuming that three arcs are output from one link, the arc end identifiers are the first and the second.
The arc end identifier is assigned 0 for the second arc, and 1 is assigned for the third arc. Therefore, when searching for a link connected to one link using the arc table, if the arc termination identifier is 0, there is another connection link, and if the arc termination identifier is 1, the connection is no longer performed. You can see that there is no link.

The pivot table is a first-in first-out type table in which the sequence numbers of the links currently required for calculation among the many links stored in the link table are stored. A more specific route network will be assumed and described. FIG. 7 shows nodes within a range including a starting point and a destination, which are targets of route calculation, as A, B, C, D,
A link route diagram in which E and F are used, A is used as a departure node, and B is used as a destination node is shown. The total number of links is A → B, A
→ C, B → A, B → C, B → E, B → F, C → A, C →
11 are B, C → D, D → E, and E → B.

The structures of the stored tables are shown in Table 1 and Table 2, respectively. Table 1 is a link table. For each link, sequence number, exit link mesh number, ingress link mesh number, arc table pointer, road type or previous link pointer, link cost, link length, total cost It has columns.

[0030]

[Table 1]

Table 2 is an arc table, which has columns for sequence number, arc cost, another mesh flag, arc end identifier, and pointer to link table.

[0032]

[Table 2]

The numerical values entered in the link table and arc table do not indicate the actual storage states of the link table and arc table, but are only entered for convenience of explaining the route calculation procedure later. I'll decline it. Next, a route search method using the link table, arc table and pivot table will be described. In the following calculation, a method of creating a tree from a starting point to a destination and calculating a route will be described. However, conversely, a method of creating a tree from a destination to a starting point and calculating a route may be used.

Referring to FIG. 7, it is assumed that link A → B or link A → C starts. It is assumed that the destination is near node B. Looking at the sequence number 0 column corresponding to the link A → B in the link table, the pointer to the arc table indicates 0, so the sequence number 0 column of the arc table is seen. The pointer to the link table is 4
Has become. Therefore, looking at the sequence number 4 column in the link table, the link with sequence number 4 is the link B → E specified by the start node B and the end node E.
Is. Therefore, it can be seen that the link B → E is connected to the link A → B. Since the arc end identifier of the arc table is 0, there are other arcs following the link A → B. Then, the arc table is traced down to see the column of sequence number 1. Since the pointer to the link table is 3, looking at the sequence number 3 column of the link table, the link is B → C. Therefore, it can be seen that the link B → C is also connected to the link A → B. Further, the arc table is traced downward to see the column of sequence number 2. Since the pointer to the link table is 12, looking at the column of sequence number 12 in the link table, it is link B → F. Therefore, it can be seen that the link B → F is also connected to the link A → B. Here, since the arc end identifier is 1, the search for the link connected to the link A → B is completed.

Next, a link connected to the link B → E is searched. Looking at the sequence number 4 column in the link table, there is no pointer to the arc table, so the search is aborted there. Next, the link connected to the link B → C is searched. Looking at the sequence number 3 column of the link table, the pointer to the arc table is 6. Therefore, looking at the sequence number 6 column of the arc table, the link is link C → A. Since the arc end identifier in the column of the sequence number 6 in the arc table is 0, there are other arcs connected to the link B → C. Therefore, sequence number 7 in the arc table
Looking at the column, the link is link C → D. The arc end identifier in the column of sequence number 7 in the arc table is 1
Therefore, the search ends there.

Next, a link connected to the link B → F is searched. This link is a calculation end link and there is no pointer to the arc table, so the search is aborted there. Next, the link connected to the link C → D is searched to find the link D → E.

As described above, connection links are obtained one after another like a tree. The obtained tree is as shown in FIG. FIG. 8A shows a tree extending from the link A → B, and FIG. 8B shows a tree extending from the link A → C. Although the tree extends infinitely, the calculation is aborted in the middle of the tree by devising the process as described later.

The method for searching links one after another has been described above. In the route calculation process, the arc cost is added in addition to the route search, and the optimum route with the least cost is calculated. Needs to be calculated. Therefore, a method of calculating the optimum route will be described in detail with reference to flowcharts (FIGS. 1 and 9).

First, the CPU 26a takes out a predetermined range of link data including a starting point and a destination from the disk 14 and creates a link table based on a predetermined program. At this time, if the certain range including the starting point and the destination includes a plurality of meshes, the mesh numbers are renumbered to the sequential numbers and stored. This will make map management easier and faster access possible.

At the time of creating the link table, all the values of the total cost of the link table are infinite (actually, it is sufficient to set the value about two orders of magnitude larger than the expected total cost), and there is no previous link. Initialize.
Hereinafter, assuming the route network in FIG. 7, the optimum route is calculated by setting the departure point links (referred to as calculation start links) to A → B and A → C and the destination links (referred to as calculation end links) to B → F.

The CPU 26a takes out the calculation start links A → B and A → C and registers these calculation start links A → B and A → C in the pivot table (step N).
1). The link registered in the pivot table is hereinafter referred to as "pivot link". Set the total cost corresponding to these pivot links to 0 on the link table,
The upper limit cost of the memory 26b is infinite (step N2).

The CPU 26a refers to the pivot table and determines whether or not there is an unprocessed pivot link (step N3). I didn't do anything at first, so
An unprocessed pivot link, for example calculation start link A → B, exists in the pivot table. This is taken out as an unprocessed pivot link (step N4). Then, it is determined whether or not the link A → B is a calculation end link (step N5). If it is not a calculation end link, link A → B
It is judged whether the total cost of the above exceeds the upper limit cost (step N8). The total cost of the links A → B is set to the initial value 0 and the upper limit cost is set to infinity on the link table. Therefore, the determination in step N8 is “NO”, and the process proceeds to step N9. In step N9, it is determined whether the search for all arcs has been completed. If the search is not completed, the CPU 26a searches for a link connected to the link A → B, and therefore the link A →
The link table corresponding to B is referenced, and the pointer to the arc table and the arc cost are acquired. As a result, as described above, the link B is first searched for in the arc table. The arc cost of link B → E is link A
→ 72 is the link cost 70 of B plus the right turn cost 2 at the intersection B. The arc cost 72 is added to the total cost of the links A → B (which is 0), and this is set as the total cost 72 of the links B → E (step N11 in FIG. 9). It is determined whether this total cost is smaller than the total cost (the initial value is infinite) of the connection link B → E written in the link table (step N12).

Since it is always small at first, the process proceeds to step N13, and the total cost of the connection links B → E is rewritten on the link table (step N13). Next, it is checked whether the link B → E exists in the pivot table (step N14). This survey takes time if you check each link in the pivot table,
The check is performed based on the predetermined bit on the link table described above. If it does not exist in the pivot table, the link B → E is registered in the pivot table (step N15).

Then, the pointer to the link A → B which is the previous link is recorded on the link table (step N1).
6). After that, the process returns to step N9, and the link A → B
In order to search for another link connected to, the column of sequence number 1 in the arc table is referenced. As a result, the link B → C is found. The arc cost of the link B → C is 72, which is the link cost 70 of the link A → B plus the right turn cost 2 at the intersection B. And link A
→ The arc cost 72 is added to the total cost of B (which is 0) to obtain the total cost of links B → C (step N11). And this total cost 7
2 is compared with the total cost of links B → C written in the link table (its initial value is infinite) to see if it is smaller (step N12).
The CPU 26a rewrites the total cost of the connection links B → C on the link table to 72 (step N).
13). Next, it is checked whether the link B → C exists in the pivot table (step N14), and if it does not exist in the pivot table, the link B → C is registered (step N15). Then, the pointer to the previous link A → B is recorded on the link table (step N).
16).

Then, the process returns to step N9 and the link A →
Referring to the arc end identifier of the row with the sequence number 1 in the arc table corresponding to B, it is 0, so there are other connection links. As a result, the link B → F is found. Also for this link B → F, the arc cost 70 is obtained in the same manner as above, and the straight-ahead cost 1 at the node B is added (the straight-ahead cost is not 0 because the signal waiting at the intersection is taken into consideration). The total cost 71 is set (step N11), and the total cost of the connection links B → F is rewritten to 72 on the link table (step N13). Further, the link B → F is registered in the pivot table (step N15), and the pointer to the previous link A → B is recorded on the link table (step N16).

Then, the process returns to step N9 and the link A →
Referring to the arc end identifier in the row of sequence number 2 in the arc table corresponding to B, it is 1, so it can be seen that there is no other connection link. As a result, step N3
Return to and determine if there are unprocessed pivot links in the pivot table. Since the calculation start links A → C exist as unprocessed pivot links in the pivot table, this is taken out (step N4), it is judged whether or not it is the calculation end link (step N5), and if it is not the calculation end link, step N8 To proceed to step N9. In step N9, a link connected to the link A → C is searched, but in this case, links C → B and C → D are searched. Calculation and rewriting of the total cost, registration in the pivot table, registration of the pointer to the previous link,
Since the method is the same as that described above, the description is omitted.

Then, returning to step N3, the link B → E is taken out as an unprocessed pivot link and a link connecting to the link B → E is searched, but since there is no such link, the pivot link B → C Link B
→ Search for a link C → A leading to C. As a result, the arc cost 42 for the link C → A is obtained and added to the total cost 72 of the previous link B → C to obtain the value 11
4 is set as the total cost of the connection link C → A on the link table. Further, the link C → A is registered in the pivot table, and the pointer to the previous link B → C is recorded.

Next, another link C → D connected to the link B → C is also searched, and as a result, the arc cost 41 for the link C → D is obtained and added to the total cost 72 of the previous link B → C. Thus, the value 113 is obtained.
Here, in step N12, the total cost of the connection links C → D on the link table is compared. Since the previous total cost is 26, since "non-small" is determined in step N12, the process such as cost rewriting and link connection changing is not performed, and the process returns to step N9. Therefore, the search for the route following the links A → B, B → C, C → D is terminated here.

At step N9, another link connected to the link B → C is searched for, but since it does not exist, the process returns to step N3, and the unprocessed pivot link B → F is taken out (step N4). Then, for the link B → F, it is determined whether or not the link B → F is a calculation end link (step N5). Link B → F
Is a calculation end link, the process proceeds to step N6,
Compare the total cost to the upper limit cost. Link B
→ The total cost of F is 71 as already described, and the initial value of the upper limit cost is infinite, so step N7
Then, the total cost 71 is used to replace the upper limit cost. Therefore, thereafter, the value of 71 is set as the upper limit cost. Then, in step N8, the total cost of link B → F is compared with this new upper limit cost, and it is checked whether (total cost of link B → F)> upper limit cost. Since the equal sign (=) holds now, it is judged as "NO" in Step N8, and Step N3
Return to.

Further, the unprocessed pivot link C → B is taken out (step N4). Then, for the link C → B, the link connecting to the link C → B is searched, the calculation and rewriting of the total cost, the registration in the pivot table, and the registration of the pointer in the previous link are performed in the same manner as described above. Is done. Thereafter, the links forming the tree of FIG. 8 are searched one after another by the same procedure as described above, and the total cost is rewritten according to the conditions.

Consider, for example, the case of searching for the link D → E connected to the link C → D, the total cost is 26, which is the total cost of the link C → D.
The arc cost of link D → E is 61 (link C → D
(Link cost 60 of 1 plus straight ahead cost 1)), which is 87. Therefore, if the determination is made in step N8 for link D → E, the inequality (total cost of link D → E) 87> upper cost 7
1 is satisfied, and a “YES” determination is made in step N8,
A link connected to the link D → E, for example, the link E → B is not searched. That is, once the upper limit cost is set to a finite value, the search for the connection link is terminated for the link having the total cost higher than that. Therefore, it is not necessary to search for unnecessary links, and the route calculation time is shortened.

Next, for example, considering the case of searching the link B → F connected to the link C → B, the total cost is 26, which is the total cost of the link C → B.
The arc cost of link B → F is 36 (link C → B
62, which is the sum of the link cost 35 and the straight-ahead cost 1). The link B to F is a calculation end link, and its total cost is compared with the upper limit cost 71 in step N6.

Since the relation of (total cost 62) <71 is established, 62 is newly set as the upper limit cost in step N7. Therefore, in the subsequent processing, this lower value 62 becomes the upper limit cost. This means that even after the calculation end link is searched once and the total cost is set as the upper limit cost, if a route (shortcut) to the calculation end link having a total cost less than that is searched, Thereafter, the lower total cost becomes the upper limit cost. Therefore, the route with the shortest cost can always be found.

Finally, when all the pivot links have been processed in step N3, the route search is completed. Finally, the route from the starting point to the destination is obtained by following the previous link of the calculation end link B → F. As described above, the links A → C, C → B, and B → F are finally determined as the optimum routes.

Referring to the total cost column of the calculation end link B → F, the total cost 62 becomes the optimum route cost from the starting point to the destination.

[0056]

As described above, according to the route calculation method and apparatus of the present invention, once the search reaches the calculation end link, the cost exceeding the cost required to reach the calculation end link thereafter is exceeded. Since the search is discontinued for the route of, the number of loops can be reduced and the calculation processing time can be shortened.

[Brief description of drawings]

FIG. 1 is a flowchart illustrating a method of calculating an optimum route according to the present invention.

FIG. 2 is a block diagram showing a navigation device that executes the route calculation method of the present invention.

FIG. 3 is a diagram showing an example of an outgoing link at a crossroads.

FIG. 4 is a diagram showing an example of an incoming link at a crossroads.

FIG. 5 is a detailed configuration diagram of a controller.

FIG. 6 is a simple link configuration diagram for explaining a total cost.

FIG. 7 is a link configuration diagram for a route calculation target including a departure place and a destination.

FIG. 8 is a diagram showing a tree of links obtained by sequentially obtaining connection links.

FIG. 9 is a flowchart (continuation of FIG. 1) illustrating a method of calculating an optimum route.

[Explanation of symbols]

 14 disk 17 controller 26 route calculation processing unit 26a CPU 26b initial search flag 26c main memory

 ─────────────────────────────────────────────────── ─── Continued Front Page (72) Inventor Kazuo Hirano 1-3-3 Shimaya, Konohana-ku, Osaka City Sumitomo Electric Industries, Ltd. Osaka Works

Claims (2)

[Claims] 1. A route network memory storing costs of respective links constituting a route network and a connection relation between the links, one or a plurality of connection links connected next to each link, and Enter the first table that has a column to enter the link on the calculated route that is connected before the link and the total cost of the calculated route that includes this link, and the link to search for the connection link Using the second table with columns, (a) read a certain range of route network data from the route network memory according to the setting of the origin and destination, and (b) configure the read route network. Set the initial value of the total cost of each link to a sufficiently large value,
Write in the corresponding column of the first table, (c) write the calculation start link in the second table, and set the total cost column of the first table corresponding to the link written in this second table to 0 (D) For the links entered in the second table, first
Connection table is searched for, the link cost of the searched connection link is added to the cost of the link entered in the second table, and the added value is entered in the first table. Compared with the total cost of the connection link, (e) If the added value is large as a result of the comparison, the processing for that connection link is terminated, and if it is smaller, the value is added to the total cost of the connection link in the first table. And write the link entered in the second table as a link on the calculated route to the connection link, and (f) newly enter the connection link in the second table, (G) When the processes of (d) and (e) are repeated, and (g) the connection link search is completed for all the links entered in the second table, the calculation end link from the first table In the route calculation method for determining the optimum route by starting and following the links on the calculated route reaching the link in order, the link entered in the second table in the step (d) is If the link is a calculation end link, the total cost is compared with the set value of the upper limit cost, and if it is smaller than the set value of the upper limit cost, the upper limit cost is updated to the value of the total cost, and the procedure (d) is repeated thereafter. In addition, referring to the total cost of the links entered in the second table, if the total cost is higher than the set upper limit cost, the process for the link is terminated without searching for the connecting link. Method. 2. A route network memory storing costs of respective links constituting a route network and a connection relation between the links, one or a plurality of connection links connected next to each link, and Enter the first table that has a column to enter the link on the calculated route that is connected before the link and the total cost of the calculated route that includes this link, and the link to search for the connection link A route including a second table having columns, and route calculation processing means for calculating an optimal route between two points on the road map by executing the steps (a) to (g) of claim 1. In the computing device, the route calculation processing means is configured to perform the second step in the step (d).
If the link entered in the table is a calculation end link, the total cost is compared with the set value of the upper limit cost, and if it is smaller than the set value of the upper limit cost, the upper limit cost is updated to the value of the total cost, When step (d) is repeated thereafter, the total cost of the link entered in the second table is referred to, and if the total cost is higher than the set upper limit cost, the processing for that link is executed without searching for the connected link. A route calculation device characterized by being cut.