Visit route calculation device and visit route calculation method

Abstract

The present invention relates to a visit route calculation device for calculating a visit route for minimizing a delay time, which is a time during which supply of a supply item is interrupted at each supply point, when a plurality of supply points are visited sequentially for supply of the supply item. Each supply point has a predefined importance associated with the delay time. The visit route calculation device includes a calculation unit that calculates a visit route under a condition that the delay time of a supply point is reduced as the supply point has higher importance such that a weighted delay time, which is a delay time weighted by the importance, becomes the lower limit of a search range at a supply point where the supply item is supplied last among a plurality of supply points.

Description

Visit route calculation device and visit route calculation method

[0001] The present invention relates to an apparatus and method for calculating a route to visit a plurality of supply points in order to supply supplies, for example, in the event of a disaster.

[0002] Conventionally, when supplies are delivered by vehicle to multiple supply points during a large-scale disaster or the like, a route is required that minimizes the time (delay time) that supplies run out at each supply point.

[0003] For example, in the event of a large-scale power outage, infrastructure such as water and electricity needs to be transported by vehicle to supply points in the affected area, but if there are multiple supply points, a delivery plan, i.e., a route for the vehicles, needs to be created.

[0004] Since the availability of infrastructure during a disaster can mean a difference in human life, delivery plans must be created as efficiently as possible. For example, the number of people needing each supply point varies from one supply point to another, and supply points with large numbers of people are important and should be visited first.

[0005] When creating a delivery plan, a target time at which each supply point is desired to receive materials from a vehicle is generally set in advance, and the processing time at each supply point and the travel time between each supply point are also set in advance.

[0006] Here, the difference between the actual arrival time and the target time at each supply point is called "delay" and is taken into consideration as a measure when creating a delivery plan. For example, if the importance of each supply point is specified in advance, a route with a shorter delay time is desired for a supply point with a higher importance, that is, a route that minimizes the maximum delay weighted by the importance.

[0007] The problem of "minimizing the maximum value of importance-weighted delay (hereinafter also referred to as "weighted delay")" has traditionally been solved by applying a branch-and-bound method.

[0008] A vehicle visits one point, performs a process, and then visits another point repeatedly. In the conventional branch and bound algorithm, a weighted delay (weighted delay) is defined as the product of the delay and importance at each point. The weighted delay is then calculated for each point using a delivery plan, and a delivery plan that minimizes the maximum weighted delay is found. The optimal delivery plan is found using the branch and bound algorithm, a general rigorous algorithm.

[0009] Tanaka, Shunji and Araki, Mituhiko, “An exact algorithm for the single-machine total weighted tardiness problem with sequence-dependent setup times,” Computers & Operations Research, Vol. 40, No. 1, pp. 344-352, 2013.

[0010] By the way, when using the branch and bound method, the set S consisting of all feasible solutions is a suitable subset.

[0011] Here, S ｉ is the set of paths that are visited first at vertex i.

[0012] In this case, S ｉ A unique path can be found that visits the vertices in the set S in order of the time remaining until the target time. ｉ is the upper limit of the optimal value for

[0013] Furthermore, as disclosed in Non-Patent Document 1, a path that visits vertices (however, vertex i is visited first) is constructed on a spatio-temporal neural network, allowing both 1) passing through the same vertex multiple times and 2) not passing through all vertices.

[0014] The minimum value of the maximum delay is estimated on this spatio-temporal neural network, and the estimated value is S ｉ is taken as the lower limit of the optimal value for

[0015] However, when the branch and bound method is applied as is, the search range becomes enormous, and the calculation time becomes enormous as the number of points increases, making it difficult to find an efficient delivery plan.

[0016] The present invention has been made in consideration of the above circumstances, and aims to provide a visiting route calculation device and visiting route calculation method that are capable of calculating a visiting route so as to minimize the time (delay time) that materials run out at each supply point when supplies are supplied by visiting multiple supply points in sequence.

[0017] In order to achieve the above object, a visiting route calculation device according to a first aspect of the present invention is a device that calculates a visiting route that minimizes the delay time, which is the time it takes for a supply to run out at each supply point when the supply is supplied by visiting a plurality of supply points in sequence, and is equipped with a calculation unit that calculates the visiting route so that the weighted delay time, in which the importance is weighted to the delay time, becomes the lower limit of the search range at the supply point among the plurality of supply points from which the supply is supplied last, under the condition that each supply point is assigned a predetermined importance associated with the delay time and the visiting route is calculated so that the more important the supply point is, the shorter the delay time.

[0018] According to the visiting route calculation device and visiting route calculation method of the present invention, when supplies are supplied by visiting multiple supply points in sequence, it is possible to calculate a visiting route so as to minimize the time (delay time) that the supplies run out at each supply point.

[0019] Fig. 1 is an electronic block diagram showing an example of the configuration of a visiting route calculation device to which a visiting route calculation method according to an embodiment of the present invention is applied. Fig. 2 is a diagram showing travel times between multiple vertices (number of demand points).

[0020] Hereinafter, embodiments of the present invention will be described with reference to the drawings. The drawings are schematic or conceptual, and the relationship between the thickness and width of each part, the size ratio between parts, etc., are not necessarily the same as those in reality. Furthermore, even when the same part is shown, the dimensions and ratios may be different depending on the drawing. In this specification and each drawing, elements similar to those described above with reference to the previous drawings are designated by the same reference numerals, and detailed and redundant explanations will be omitted as appropriate.

[0021] FIG. 1 is an electronic block diagram showing an example of the configuration of a visiting route calculation device to which a visiting route calculation method according to an embodiment of the present invention is applied.

[0022] That is, the visiting route calculation device 10 is a device that calculates a visiting route that minimizes the delay time, which is the time it takes for a supply to run out at each supply point, when a vehicle visits and delivers a supply to multiple supply points in sequence. Each supply point is assigned a level of importance associated with the delay time. The level of importance is determined by reflecting the number of people at each point.

[0023] The electronic configuration of the visiting route calculation device 10 comprises a CPU 12, a recording medium reading unit 14, an input unit 15, a display unit 16 such as a display, a memory 20 storing various programs, and a data storage unit 30, all of which are connected to one another by a bus 11.

[0024] The display unit 16 can be realized by a display or the like.

[0025] The data storage unit 30 can be realized by a storage device such as a hard disk, an SSD, etc. The data storage unit 30 stores the importance r associated with the delay time of each supply point.

[0026] The input unit 15 is composed of, for example, a mouse, a keyboard, etc., and the user can operate the input unit 15 to make inputs required for operating the visiting route calculation device 10 .

[0027] The memory 20 stores a program that realizes a calculation unit 21 that calculates a visiting route and a display control unit 22 that controls the display of the calculation results, etc., by the calculation unit 21 on the display unit 16 .

[0028] The calculation unit 21 calculates the visiting route so that the weighted delay time obtained by weighting the importance r to the delay time becomes the lower limit value of the search range at the supply point that is the last to receive the supply material among the multiple supply points, under the condition that the visiting route is calculated so that the delay time is shorter for a supply point with a higher importance r.

[0029] The calculation unit 21 calculates the visited route by a branch and bound method. The lower limit value of the search range is the lower limit value of the search range of the branch and bound method.

[0030] The programs that realize the calculation unit 21 and the display control unit 22 may be stored in advance in the memory 20, or may be read from an external recording medium 19 such as a memory card via the recording medium reading unit 14 and stored in the memory 20. The programs that realize the calculation unit 21 and the display control unit 22 are designed not to be rewritable.

[0031] In addition to this non-rewritable area, the memory 20 also has a writable data area 29 secured as an area for storing rewritable data.

[0032] The CPU 12 is a computer that controls the operations of the calculation unit 21 and the display control unit 22 in accordance with the programs stored in the memory 20 .

[0033] Such a visiting route calculation device 10 operates in cooperation with hardware such as a bus 11, a CPU 12, a recording medium reading unit 14, an input unit 15, a display unit 16, a memory 20, and a data storage unit 30, and software which is each program stored in the memory 20.

[0034] The visited route calculation device 10 can be realized by, but is not limited to, a PC or a tablet terminal. Alternatively, it does not necessarily have to be configured by the same hardware, and can be realized by multiple pieces of hardware with distributed functions, such as in the cloud.

[0035] Next, an example of the operation of the visiting route calculation device 10 according to this embodiment will be described.

[0036] The visiting route calculation device 10 proposes a method for quickly determining the lower limit of the search range of the branch and bound method. The maximum weighted delay is greater than the weighted delay of the last point to be visited. Therefore, the weighted delay of the last point to be visited is set as the lower limit of the search range.

[0037] Given a delivery plan ρ, the weighted delay for vertex i is can be calculated using the formula:

[0038] When calculating a delivery plan that minimizes the maximum weighted delay, the calculation unit 21 calculates the upper limit values ​​of the branching operation and the limiting operation in O(n) time using the following proposition Prop 1., as in Non-Patent Document 1. Prop 1. where L is the optimal value consisting of unvisited vertices. This is the lower limit of Proof. Optimal route ρ ＊ The last vertex to be visited is last ρ＊ Let's say.

[0039] Optimal route ρ ＊ The total travel time between vertices at ｍｓｔ is larger than the optimal route ρ ＊ The time when all vertices are visited is From (#), opt≧L. Here, i: vertex τ(i, j): travel time between vertices i and j t ｍｓｔ : The total length of the minimum spanning tree calculated from all unvisited vertices and a graph with edge length τ(i, j) ｉ : Weight of vertex i (>0) process ｉ : Stay time at vertex i due date ｉ : Exhaustion time of vertex i ρ: Path that passes through all unvisited vertices arrive ｉ (ρ): The time of arrival at i via route ρ.

[0040] S ｉ Since the calculation of the lower limit of the optimal value for can be done in O(n), it is expected that the optimal route can be found efficiently, which will enable faster disaster response.

[0041] Next, a specific example of route calculation by the visiting route calculation device 10 will be described. The route calculation is performed by the calculation unit 21.

[0042] FIG. 2 is a diagram showing travel times between a plurality of vertices (number of demand points).

[0043] Figure 2 shows the seven vertices v ０ ~v ６ and their vertices v ０ ~v ６ The figure shows the estimated travel time between two vertices of the route. The starting point of the vehicle is also called a depot, and each supply point is also called a vertex. The unit of the estimated travel time is [h] (hours).

[0044] Furthermore, if the vehicle reaches the vertex v ０ The target time when the departure time is set to 0 is １ : 17, p ２ : 29, p ３ : 27, p ４ : 18, p ５ : 29, p ６ : 18, and the processing time is d １ : 3, d ２ : 5, d ３ : 4, d ４ : 5, d ５ : 1, d ６ : 6, and the importance is １ : 1, r ２ : 1, r ３ : 1, r ４ : 2, r ５ : 2, r ６ :3, and v １ ~v ６ Assume all are unvisited.

[0045] The minimum delay time determined by total counting was 10.6.

[0046] When all points are unvisited, the lower limit of the optimum value is calculated by the present invention. １ ~v ６ The total length of the minimum spanning tree obtained was 15.39, and the total processing time was 24. In this way, we were able to confirm that this is indeed the lower limit of the optimal value.

[0047] After that, by repeating the branching and limiting operations, the optimal value 10.6 and the optimal path v ６ →v ５ →v ４ →v １ →v ３ →v ２ And got it.

[0048] The required calculation time was 0.047 s.

[0049] On the other hand, when the optimal delivery plan was calculated using a device constructed under the same environment using the method of Non-Patent Document 1, the same optimal value and optimal solution were obtained, and the required calculation time was 0.187 seconds.

[0050] In this way, by constructing an optimization algorithm that discovers the optimal route plan on an undirected graph in which the vehicle's starting point is the depot, each supply point is a vertex, and the roads between points are edges, it was confirmed that the use of the visiting route calculation device 10 makes it possible to find the optimal solution more quickly than conventional technology.

[0051] As described above, the visiting route calculation device 10 according to this embodiment utilizes the fact that the maximum weighted delay is greater than the weighted delay of the last point to be visited, and by setting the weighted delay of the last point to be visited as the lower limit of the search range, it is possible to quickly find the lower limit of the search range for the limitation method.

[0052] This allows the calculation of the lower bound of the optimal value for a subset of solutions to be performed in O(n), making it possible to efficiently find the optimal route and speed up the calculation of visiting routes in the event of a disaster.Numerical experiments confirmed that the calculation time using the proposed method was approximately one-quarter of that of existing methods.

[0053] As described above, according to the route calculation device of this embodiment, when supplies are supplied by vehicle visiting multiple supply points in sequence, the route can be calculated to minimize the time (delay time) that supplies run out at each supply point, making it possible to minimize the impact on people in the event of a disaster.

[0054] The present invention is not limited to the above-described embodiments, and can be embodied by modifying the components within the scope of the gist of the present invention. Furthermore, various inventions can be created by appropriately combining multiple components disclosed in the above-described embodiments. For example, some components may be omitted from all the components shown in the embodiments. Furthermore, components from different embodiments may be appropriately combined.

[0055] For example, in the above embodiment, the case where supplies are supplied to multiple demand points when a disaster occurs has been described as an example, but the present invention is not limited to this and can also be applied to calculating visiting routes when delivering goods to multiple stores during normal times, for example.

[0056] Furthermore, in addition to road vehicles such as trucks, it is possible to selectively use railroads, ships, and flying objects such as drones as transportation means. In addition, the functions of the visiting route calculation supply device, the processing procedures and processing contents, the types of supplies, the contents of the support information, etc. can be modified and implemented in various ways without departing from the spirit of this invention.

[0057] REFERENCE SIGNS LIST 10 Visited route calculation device 11 Bus 12 CPU 14 Recording medium reading unit 15 Input unit 16 Display unit 19 External recording medium 20 Memory 21 Calculation unit 22 Display control unit 29 Writable data area 30 Data storage unit

Claims

1. A device for calculating a visiting route that minimizes a delay time, which is the time it takes for a supply to run out at each supply point when a supply item is supplied by visiting a plurality of supply points in sequence, wherein each supply point is assigned a predetermined importance associated with the delay time, and the visiting route calculation device is equipped with a calculation unit that calculates the visiting route such that a weighted delay time, in which the importance is weighted to the delay time, becomes the lower limit of a search range at a supply point among the plurality of supply points to which the supply item is last supplied, under the condition that the supply route is calculated such that the delay time is shorter for a supply point with a higher importance.

2. The visiting route calculation device according to claim 1, wherein the calculation unit calculates the visiting route using a branch and bound method, and the lower limit value of the search range is the lower limit value of the search range of the branch and bound method.

3. A method for calculating a visiting route that minimizes a delay time, which is the time it takes for a supply to run out at each supply point, when a supply item is supplied by visiting a plurality of supply points in sequence, wherein each supply point is assigned a pre-specified importance associated with the delay time, and a processor calculates the visiting route such that a weighted delay time, in which the importance is weighted to the delay time, becomes the lower limit of a search range at a supply point among the plurality of supply points to which the supply item is last supplied, under the condition that the visiting route is calculated so that the delay time is shorter for a supply point with a higher importance.

4. The visiting route calculation method according to claim 3, wherein the processor calculates the visiting route by a branch and bound method, and the lower limit value of the search range is the lower limit value of the search range of the branch and bound method.

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