JP2003087311A - Path finding device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a path finding device that can surely find paths from a start point node to an end point node in a short time. SOLUTION: A search processing section 12 includes; a branch sensitivity calculation means 61 for calculating the sensitivity of each branch with respect to a preset start point node and a preset and point node and extracting only branches with sensitivity in a graph where paths are expressed by nods and branches; a radiant configuration generating means 62 for searching a loop configuration included in the graph extracted by the branch sensitivity calculation means 61 and interrupting the searched loop configuration to generate combinations of branches being interruption objects to provide the radiant configuration to the graph; and a all route searching means 63 for searching all path candidates from the start point node to the end point node on the basis of the graph with the radiant configuration created by interrupting the branches of the interruption objects by the radiant configuration generating means 62.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a route search device for searching a route from a start point node to an end point node in a graph expressing a route with nodes and branches.

[0002]

2. Description of the Related Art Conventionally, as an apparatus for searching all routes from a start point node to an end point node in a graph in which a route is expressed by nodes and branches, for example, Japanese Patent Laid-Open No. 07-
There is one described in Japanese Patent No. 015469.

This all-routes searching device searches all routes by a so-called brute force method, and this brute force method will be described with reference to FIG.

In FIG. 13, when the start point node is point A and the end point node is point B, first, the connection destination node is checked for all relay paths extending from the start point node A, and if it is the end point node B, Store the route. If the connection destination node is not the end point node B, further check whether or not the connection destination node is the end point node B for all relay paths extending from the connection destination node, and finally reach the end point node B. , Store its route.

As described above, in the conventional apparatus, all routes from the start point node A to the end point node B are searched by checking the routes for all the relay paths extending from all the connection destination nodes.

[0006]

Since the conventional route search device is configured as described above, the number of combinations of route searches increases as the number of nodes and the number of branches increase, and the route search device is It takes time.

Further, regarding the shortest path search, conventionally, there are methods such as the Kurskal arithmetic method and the Dijkstraum method. However, in the above-mentioned conventional method, depending on the method of setting the objective function (such as when there is a branch with a negative evaluation), there is a problem that the local optimal solution cannot be found and the overall optimal route may not be found. Occurs.

The present invention has been made to solve the above problems, and an object of the present invention is to provide a route search device capable of surely performing a route search from a start node to an end node in a short time. And

[0009]

The present invention has the following features to attain the object mentioned above. That is,
The route search device according to the invention of claim 1 calculates only the sensitivity of each branch with respect to a preset start point node and end point node in a graph expressing a route with nodes and branches, and extracts only branches having sensitivity. A combination of branch sensitivity calculation means and a branch configuration to be cut for searching the loop configuration included in the graph extracted by this branch sensitivity calculation means and cutting the searched loop configuration to make the graph a radial configuration All paths that search for all the candidates of paths from the start point node to the end point node based on the radial configuration creating means for creating the and the radial configuration graph created by cutting the branch to be cut by the radial configuration creating means And a search means.

A route search device according to a second aspect of the present invention is, in the configuration of the first aspect of the invention, a route satisfying a constraint on a traveling direction of a branch from among the routes searched by the all-routes search means. It is characterized in that it has a route search means with a traveling direction constraint that searches for the candidate.

A route search device according to a third aspect of the present invention is the route of the invention according to the first aspect or the second aspect, wherein the route passes through a designated relay point node on the way from the start point node to the end point node. It is characterized in that it has a relay point via route searching means for searching for all the candidates.

According to a fourth aspect of the present invention, there is provided a route search device according to any one of the first to third aspects of the invention, wherein the route searched by the all-routes search means is: It is characterized by having a minimum cost route searching means for searching a route with the minimum cost.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiment 1. 1 is a block diagram showing a configuration of a route search device according to a first embodiment of the present invention. The route search device 1 includes a search data storage unit 11 including a hard disk and a search processing unit 12 including a microcomputer.

The search data storage unit 11 has a node branch connection information storage device 51. The node-branch connection information storage device 51 stores the number of branches, the number of nodes,
Node branch connection information such as a start node number and an end node number is stored in advance.

The search processing unit 12 performs a route search based on the node branch connection information stored in the node branch connection information storage device 51, and includes branch sensitivity calculation means 61, radial configuration creation means 62, and all paths. The searching means 63 is included. The search processing result of the search processing unit 12 is output to an output device such as a display or a printer (not shown).

The branch sensitivity calculating means 61 is set in advance in a graph representing a route with a node and a branch based on the node branch connection information generated from the node branch connection information storage device 51 of the search data storage unit 11. The sensitivity of each branch with respect to the start point node and the end point node is calculated, and only the branches having sensitivity are extracted.

Further, the radial configuration creating means 62 searches for a loop configuration included in the graph extracted by the branch sensitivity calculating means 61, and disconnects the searched loop configuration as a cutting target for making the graph a radial configuration. To create a combination of branches.

Further, the all-routes search means 63 searches for all the candidates of the route from the start point node to the end point node based on the radial configuration graph created by cutting the branch to be cut by the radial configuration creation means 62. To do.

Next, the entire route search processing operation in the route search device 1 having the above configuration will be described with reference to the flowchart shown in FIG. 2 and the explanatory diagrams shown in FIGS. The symbol S means each processing step.

First, the branch sensitivity calculation means 61 reads the node branch connection information stored in advance in the node branch connection information storage device 51 (S1), and determines the sensitivity of each branch with respect to the preset start point node and end point node. Calculate and extract only branches with sensitivity (S
2).

For example, if there is a graph in which routes are represented by nodes and branches as shown in FIG. 3, the starting point node is the node with the number 2 and the end point node is the node with the number 6 and the starting point node is the transmitting side. Considering that, the power generation point is defined as a slack node, and the end point node is considered as a power receiving side and is defined as a load node having a load amount of 1 MW. At this time, if a random impedance is set for each branch and the tidal current is calculated, there will be a branch through which the tidal current flows and a branch through which the tidal current does not flow. In FIG. 3, the branches through which the tidal current flows are numbered 2, 3,
The branches of 4, 5, 6, and 7 in which the tidal current does not flow are numbered 1, 8, 9, 10, and 11. Among them, the branch in which the tidal current does not flow can be considered to be irrelevant with respect to the start point node and the end point node, that is, have no sensitivity and can be considered to be 0.

As described above, when a plurality of branches are connected to the start point node and the end point node, the branch candidate of the route has a numerical value other than 0 among the plurality of branches.
The sensitivity is 0 for branches that are unrelated to the start point node and the end point node. Therefore, since the branch having a sensitivity of 0 is irrelevant to the route connecting the start point node and the end point node, such a branch is cut and deleted (S3). Also,
By deleting a branch having a sensitivity of 0, a floating node in which all connected branches are disconnected and is not connected to any node is also irrelevant to the route search and is deleted.

In this way, when unnecessary nodes and branches are deleted from the start point node and the end point node in FIG. 3, the search target nodes and branches are as shown in FIG. Therefore, the number of search target nodes and the number of branches are reduced in performing the route search, and the efficiency of the route search process can be improved.

Next, the radial structure creating means 62 searches the graph extracted by the branch sensitivity calculating means 61 (for example, FIG. 4) for a loop structure and extracts a portion having the loop structure (S4). The extraction of the loop configuration in this case is performed by the following algorithm, for example.

All nodes are initially unchecked. Check the start point node. Focus on one branch. With regard to the nodes at both ends of this focused branch, a) if either one of the nodes at both ends is checked, the node that is not checked is checked, and then the next branch is focused. b) If both nodes are unchecked, focus on the next branch.
c) If both end nodes have been checked, this branch belongs to a loop, so after registering this branch as a branch of a loop configuration, focus on the next branch. The above process is repeated until the number of checked nodes does not change. Thereby, for example, in the graph in FIG. 4, two loop configurations 1 and 2 are extracted as shown in FIGS. 5 (a) and 5 (b).

Subsequently, the radial configuration creating means 62 selects one branch to be disconnected for each loop for each loop configuration extracted in step 4, and the branch to be disconnected for making the graph a non-loop configuration. A combination is created (S5). Hereinafter, a branch having a non-loop structure is referred to as a radial branch.

For example, for the two loop configurations 1 and 2 shown in FIG. 5, a combination of branches 3 and 2 to be cut in FIG. 6 (a), and a combination of branches 4 and 2 in FIG. 6 (b).
6 is created, and in FIG. 6C, the combinations of branches 4 and 4 are created. In FIG. 6, three examples are shown as the combinations of branches to be cut, but the combinations of branches to be cut for the two loop configurations 1 and 2 in FIG. 5 are nine as shown in FIG. There are combinations.

As described above, the radial structure creating means 62 is
After extracting the loop structure included in the graph, one branch is cut for each loop to create a combination of branches to be cut to make the graph radial structure. , For the following reasons.

Searching for one path from the start point node to the end point node means creating a radial configuration with a single stroke from the start point node to the end point node. Also,
In order for the graph to have such a radial configuration, it is necessary to cut at least one branch forming the loop. Therefore, paying attention to the loop configuration part included in the graph and cutting the branch of the loop configuration to create a non-loop branch is most efficient in creating the radial configuration.

Next, the all-routes searching means 63 determines whether or not the graph obtained by cutting the branches according to the combination of the branches to be cut by the radial structure creating means 62 has a radial structure ( S
6). Here, the condition for the graph to have a radial configuration is “the number of nodes = the number of branches + 1” when there are no floating nodes.
Therefore, it is determined whether the graph has a radial configuration based on this relationship.

For example, as shown in FIG. 6A, when branch 3 is cut for loop structure 1 and branch 2 is cut for loop structure 2, the graph after cutting is as shown at the right end of FIG. However, at this time, since the number of nodes is 4 and the number of branches is 3, the graph has a radial configuration. Further, as shown in FIG. 6B, when branch 4 is cut for loop configuration 1 and branch 5 is cut for loop configuration 2, the graph after cutting is shown in FIG. 6B.
As shown at the right end, the graph has a radial configuration because the number of nodes is 4 and the number of branches is 3 at this time. Furthermore, as shown in FIG. 6C, when branch 4 is cut for loop configuration 1 and branch 4 is cut for loop configuration 2, the graph after cutting becomes as shown at the right end of FIG. 6C. At this time, since the branches to be cut in the loop configuration 1 and the loop configuration 2 overlap, the number of branches becomes 4 with respect to the number of nodes 4, so that the graph does not have a radial configuration.

Next, the all-routes searching means 63 invalidates this combination and shifts the processing to step 8 when the radial configuration is not obtained. Further, in the case of the radial configuration, subsequently, the branches sequentially traced from the end point node to the start point node are stored as one path (S7).

Subsequently, the all-routes searching means 63 determines whether or not all combinations of branches to be cut to cut the loop structure to make the graph radial structure have been executed (S8). At this time, if the processing is not completed for all the combinations, the processing is moved to step 5, and steps 5 to 8 are repeated until the processing is completed for all the combinations. In this way, for example, in the graph of FIG. 4, the combination result of all the branches to be cut for making the graph a radial configuration is shown in FIG. 7.

The all-routes searching means 63 uses the above step 8
If the processing has been completed for all the combinations in, then it is determined whether or not there is a combination of overlapping routes for the searched routes (S9). Then, if there is a combination of overlapping routes, the combinations of overlapping routes are unified with respect to the created radial configuration routes (S10).

For example, with respect to overlapping routes in the combination of nine routes searched as shown in FIG. 7, if unified into one route, there are the following three ways. The numbers are branch numbers. Route 1: 4 → 7 Route 2: 2 → 5 → 7 Route 3: 3 → 6 → 7

In the conventional case, when the all-routes search is performed, the number of combinations to be searched for the route is 2 ⁿ (n: the number of branches). , Paying attention only to the loop configuration, the number of combinations targeted for route search is RB1 × RB2 × ... (RB1, R
B2, ... Is the number of branches in each loop). In the case of the example shown in FIG. 3, there are 2 ¹¹ = 2048 combinations when the full search is performed by the conventional method, whereas when only the loop configuration is focused as in the first embodiment, the target of the route search. The number of combinations is 3 × 3 = 9. In this way, by limiting the branches to be excluded in the route search to the branches forming the loop, it is possible to improve the efficiency of the route search and reduce the time required for the entire route search. It becomes possible to do.

Embodiment 2. FIG. 8 is a block diagram showing the configuration of the route search device according to the second embodiment of the present invention.
The same components as those in the route search device according to the first embodiment shown in FIG. 1 are designated by the same reference numerals.

In the route search device 2 of the second embodiment, the search data storage unit 21 is provided with a branch traveling direction constraint storage device 52 in addition to the node branch connection information storage device 51. The branch advancing direction constraint storage device 52 stores branch advancing direction constraint conditions such as time constraint, cost constraint, direction constraint, energy constraint, etc. in each branch passing from the start point node to the end point node. The following information is stored in advance.

In addition to the branch sensitivity calculating means 61, the radial configuration creating means 62, and the all-routes searching means 63, the search processing section 22 also includes a traveling-direction-constrained route searching means 6
4 are provided. The route searching unit with traveling direction constraint 64 selects, from among the routes searched by the all-routes searching unit 63, a route candidate satisfying the constraint condition of the traveling direction of the branch stored in the branch traveling direction constraint storage device 52. It is something to explore. Since other configurations are similar to those of the first embodiment, detailed description thereof will be omitted here.

Next, the route search device 2 of the second embodiment
The route search processing operation in (1) will be described mainly with respect to the operation of the route search means with traveling direction restriction 64.

For example, as shown in FIG. 9, it is assumed that there are the following three combinations of routes searched by the all-routes search means 63. The numbers are branch numbers. Route 1: 4 → 7 Route 2: 2 → 5 → 7 Route 3: 3 → 6 → 7

Considering, for example, a power interchange route between electric power companies, each node is an electric power company, the start point node 2 is the electric power company on the transmission side, the end point node 6 is the electric power company on the power receiving side, and each branch is the electric power company. It is assumed that the power transmission side electric power company 2 exchanges the interchanged electric power with the power reception side electric power company 6 as an interconnection facility.

At this time, the interconnecting equipment (branch) 6 between the electric power company (node) 4 and the electric power company (node) 5 in the middle of the route 3 is supplied with electric power from the electric power company 4 due to the reason that the installed capacity exceeds the limit. If the company 5 cannot be accommodated, the route 3 cannot be adopted as a power accommodation route. Therefore, the traveling direction constrained route searching means 64 adopts only the routes 1 and 2 as routes through which electric power can be interchanged between electric power companies (that is, routes satisfying the traveling direction constraint).

As described above, in the second embodiment, the interchange power upper limit value for each interconnection facility (branch) is
It is possible to search for a route that satisfies the constraint of the traveling direction by designating the condition that becomes the constraint of the traveling direction of the route.

Embodiment 3. FIG. 10 is a block diagram showing the configuration of the route search device according to the third embodiment of the present invention, and the components corresponding to those of the route search device according to the first embodiment shown in FIG.

In the route search device 3 of the third embodiment, the search data storage unit 31 includes the relay point designation data storage device 5 in addition to the node branch connection information storage device 51.
3 is provided. The relay point designation data storage device 53 stores in advance information for designating each relay point to be passed from the start point node to the end point node.

In addition to the branch sensitivity calculating means 61, the radial configuration creating means 62, and the all-route searching means 63, the search processing section 32 is provided with a relay point via route searching means 65. The relay point via route searching means 65 is
Based on the relay point node stored in the relay point designation data storage device 53, all route candidates passing through the designated relay point node on the way from the start point node to the end point node are searched. Since other configurations are similar to those of the first embodiment, detailed description thereof will be omitted here.

Next, the route search device 3 of the third embodiment
The route search processing operation in (1) will be described mainly with reference to the operation of the relay point via route searching means 65.

For example, in the graph shown in FIG.
The start point node is designated as node number 2 and the end point node is designated as node number 6 by the information of the node branch connection information storage device 51, and the node number 3 is designated as the relay point node by the information of the relay point designation data storage device 53. Be present.

At this time, first, as in the case of the first embodiment, the branch sensitivity calculating means 61, the radial configuration creating means 62, and the all-routes searching means 63 perform all-routes search, and the combination of all the retrieved routes is carried out. However, there are the following three ways. The numbers are node numbers. Route 1: 2 → 3 → 5 → 6 Route 2: 2 → 5 → 6 Route 3: 2 → 4 → 5 → 6

Here, the relay point via route searching means 65 is
The route including the relay point node stored in the relay point designation data storage device 53 is adopted, and the route not including the relay point node is not adopted. Therefore, in the example of the graph shown in FIG. 3, the route is obtained as the route including the relay point node in which the route 1: 2 → 3 → 5 → 6 (numerals are node numbers) is designated.

When a plurality of relay point nodes are designated, the relay point via route searching means 65 adopts only the route including all the relay point nodes according to the above procedure.

Fourth Embodiment FIG. 11 is a block diagram showing the configuration of the route search device according to the fourth embodiment of the present invention, and the components corresponding to those of the route search device in the first embodiment shown in FIG.

In the route search device 4 of the fourth embodiment, the search data storage unit 41 is provided with a branch cost data storage device 54 in addition to the node branch connection information storage device 51. The branch cost data storage device 54 stores the cost information of each branch in advance.

Further, the search processing section 42 is provided with a minimum cost route searching means 66 in addition to the branch sensitivity calculating means 61, the radial configuration creating means 62, and the all route searching means 63. This minimum cost route search means 66
Based on the information stored in the branch cost data storage device 54, the route with the minimum cost is searched from the routes searched by the all-routes search means 63.
Since other configurations are similar to those of the first embodiment, detailed description thereof will be omitted here.

Next, the route search device 4 according to the fourth embodiment
The route search processing operation in (1) will be described with a focus on the operation of the minimum cost route search means 66.

For example, as shown in FIG. 12, it is assumed that there are the following three combinations of routes searched by the all-routes search means 63. The numbers are branch numbers. Route 1: 4 → 7 Route 2: 2 → 5 → 7 Route 3: 3 → 6 → 7

Here, considering, for example, to determine an interchange route between electric power companies with the least power transmission loss, when the starting point node 2 is the transmitting side electric power company and the ending point node 6 is the receiving side electric power company, the minimum cost route. The search unit 66 calculates the transmission loss for all the routes searched by the all-route search unit 63.

In this case, the transmission loss can be calculated by using the loss rate determined by the impedance of the transmission facility or the like for the receiving port of each power company. For example, in Figure 1.
2, the loss rate when transmitting power from the power company (node) 2 to the power company (node) 3 is 3%, and the loss rate when transmitting power from the power company (node) 3 to the power company (node) 5 is 2%. It looks like.

At this time, the route from the power transmitting side power company to the power receiving side power company is route 1: 4 → 7, route 2:
2 → 5 → 7, and route 3: 3 → 6 → 7, and assuming that 1 MW of interchange power is transmitted from the power transmission company, the transmission loss to the power receiving company by each route is calculated as follows.

Power transmission loss of path 1: 1- (1-0.06) × (1-0.01) × 1 MW =
0.0694 MW Transmission loss of route 2: 1- (1-0.03) x (1-0.02) x (1-0.
01) × 1 MW = 0.0589 MW Transmission loss of path 3: 1- (1-0.04) × (1-0.04) × (1-0.
01) × 1 MW = 0.0876 MW Therefore, the minimum cost route searching means 66 selects the route 2 as the route of the minimum power transmission loss.

In the above second to fourth embodiments, the case in which the traveling direction constrained route searching means 64, the relay point via route searching means 65, and the minimum cost route searching means 66 are individually provided has been described. The present invention is not limited to this, and each of these means 64, 6 can be used as necessary.
It is possible to have a configuration in which 5, 66 are appropriately combined.

Further, in the above-described first to fourth embodiments, the power transmission path is described as an example of the graph represented by the node / branch, but the present invention is not limited to such a power transmission path, and People passing through,
The present invention can be applied to various fields such as goods, money, energy, communication, and information. For example, as the shortest route search for car navigation, the route with the shortest time between the departure point and the destination can be searched. In this case, the traveling direction constraint conditions include constraints such as one-way traffic and avoidance of crowded routes. In addition, as a communication path search for the network, it is possible to search for a detour path in the event of a network line failure. In this case, the traveling direction restriction conditions include restrictions on router routing and traffic.

[0064]

According to the present invention, the following effects can be obtained. Since the route search device of the invention according to claim 1 can reduce the number of combinations of route searches from the start point node to the end point node as compared with the conventional method, all routes from the start point node to the end point node The search can be efficiently performed in a short time.

In addition to the effect of the invention described in claim 1, the route search device of the invention according to claim 2 has this condition even when the route between the start node and the end node is restricted in the traveling direction. It is possible to search for all the route candidates that satisfy the above condition.

In addition to the effect of the invention of claim 1 or claim 2, the route search device of the invention according to claim 3 should pass a predetermined relay point on the route from the start point node to the end point node. Even if there is a constraint, it is possible to search all route candidates that satisfy this condition.

The route search device according to the invention of claim 4 requires the minimum cost from the start point node to the end point node in addition to the effect of any one of the inventions of claims 1 to 3. Even if there is such a constraint, it is possible to search all the route candidates that satisfy the condition of the minimum cost.

[Brief description of drawings]

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

FIG. 2 is a flowchart for explaining an entire route search processing operation in the route search device of FIG.

FIG. 3 is an explanatory diagram illustrating an example of a graph that is a route search processing target.

FIG. 4 is an explanatory diagram showing an example of a case where a branch sensitivity is calculated by a branch sensitivity calculation means.

FIG. 5 is an explanatory diagram showing an example of a case where a loop configuration is extracted by a radial configuration creating means.

FIG. 6 is an explanatory diagram showing an example in which a radial configuration is created by a radial configuration creating means.

FIG. 7 is an explanatory diagram showing an example of an all-routes search result by the all-routes search means in a table.

FIG. 8 is a block diagram showing a configuration of a route search device according to a second embodiment of the present invention.

FIG. 9 is an explanatory diagram showing an example of a case where a route satisfying a traveling direction constraint is searched for by a traveling route restricted route searching means.

FIG. 10 is a block diagram showing a configuration of a route search device according to a third embodiment of the present invention.

FIG. 11 is a block diagram showing a configuration of a route search device according to a fourth embodiment of the present invention.

FIG. 12 is an explanatory diagram showing an example of a case of searching for a route of minimum cost (minimum transmission loss) by the minimum cost route searching means.

FIG. 13 is an explanatory diagram showing an example of a graph that is an all-routes search processing target by a conventional all-routes search device.

[Explanation of symbols]

1,2,3,4 route search device 11,21,31,4
1 Search Data Storage Unit, 12, 22, 32, 42 Search Processing Unit, 61 Branch Sensitivity Calculating Means, 62 Radial Configuration Creating Means, 63 All Route Searching Means, 64 Traveling Direction Restricted Route Searching Means, 65 Relay Point Via Route Searching Means, 66
Minimum cost route search means.

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Claims (4)

[Claims] 1. A branch sensitivity calculation means for calculating a sensitivity of each branch with respect to a preset start point node and end point node in a graph expressing a route with nodes and branches, and extracting only branches having sensitivity. A radial configuration creating means for searching a loop configuration included in the graph extracted by the branch sensitivity calculating means, and creating a combination of branches to be cut for cutting the searched loop configuration to make the graph a radial configuration , An all-routes search means for searching all candidates for routes from the start point node to the end point node based on the graph of the radial configuration created by cutting the branch to be cut by the radial configuration creating means. Characteristic route search device. 2. A route search unit with a traveling direction constraint that searches for a route candidate satisfying a constraint on a traveling direction of a branch from among the routes searched by the all-routes searching unit. The route search device described in 1. 3. A relay point via route searching means for searching for all candidates for a route passing through a designated relay point node on the way from a start point node to an end point node. The route search device described in 1. 4. The minimum cost route searching means for searching a route having the minimum cost from among the routes searched by the all route searching means, according to any one of claims 1 to 3. The route search device according to item.