JP7579121B2 - Inventory planning system and inventory planning method - Google Patents

Description

The present invention relates to an inventory planning system and an inventory planning method.

In traditional logistics operations, inventory plans were created that included order quantities, transportation volumes, and stock amounts by day and/or product in order to minimize total costs.

The following prior art is known as background technology in this technical field. Patent Document 1 describes an ordering method selection system that calculates the order quantity when ordering goods while changing the parameters of various ordering methods such as the regular fixed quantity method, the irregular fixed quantity method, the regular unfixed quantity method, and the irregular unfixed quantity method, simulates the inventory quantity, calculates the total cost of inventory management, and calculates the specific values of the ordering parameters that minimize the total cost.

JP 2017-199282 A

In recent years, the logistics industry has been strained by a shortage of drivers, resulting in tight transportation capacity. On the other hand, products with sudden changes in demand, or seasonal products such as apparel and air conditioners that cannot be sold if the opportunity is missed, need to be sold in large quantities during short busy periods.

Therefore, if inventory planning is made without taking into account the upper limit on the number of units to be transported, as in Patent Document 1, there is a problem of delivery delays and shortages for units that exceed the upper limit.

Therefore, even when there is a limit on the number of units that can be transported, the challenge is to create an inventory plan that includes daily transportation volumes, incoming and outgoing volumes, and inventory levels to avoid delivery delays and stockouts.

The present invention is an inventory planning system having a calculation device that executes predetermined processing and a memory accessible to the calculation device, wherein the calculation device receives as input a predetermined forecast demand amount for an item and statistical data of a demand forecast error that changes depending on the number of days until the required arrival date of the item, performs predetermined processing on the demand forecast amount and the statistical data, and determines and outputs an upper limit of the transportation amount of the item , and in determining the upper limit of the transportation amount, the calculation device uses an upper limit of the number of days for advance transportation when transporting an item ahead of the required arrival date .

According to one aspect of the present invention, by setting an upper transport volume limit based on demand forecast volume and statistical data on demand forecast error that changes depending on the number of days until the required arrival date, it is possible to plan a transport volume that reduces the storage costs and disposal costs due to excess inventory that occurs when demand drops. In addition, by creating an inventory plan that satisfies the above-mentioned upper transport volume limit and upper transport number limit and minimizes the total cost including the transportation cost, storage cost, and disposal cost added per vehicle, it is possible to determine the transport volume that minimizes the cost of the entire supply chain.

Details of at least one implementation of the subject matter disclosed herein are set forth in the accompanying drawings and the description below. Other features, aspects, and advantages of the disclosed subject matter will become apparent from the following disclosure, drawings, and claims.

1 is a block diagram illustrating an example of a configuration of an inventory planning system according to an embodiment of the present invention. FIG. 10 illustrates an example of product information according to the embodiment of the present invention. FIG. 11 illustrates an example of base information according to the embodiment of the present invention. FIG. 2 illustrates an example of demand forecast information according to the embodiment of the present invention. FIG. 11 illustrates an example of route information according to the embodiment of the present invention. FIG. 11 illustrates an example of vehicle type information according to the embodiment of the present invention. FIG. 11 illustrates an example of transportation constraint information according to the embodiment of the present invention. FIG. 11 illustrates an example of unit price information according to the embodiment of the present invention. FIG. 11 illustrates an example of initial inventory information according to the embodiment of the present invention. FIG. 11 illustrates an example of upper limit stock-out rate information according to the embodiment of the present invention. FIG. 11 illustrates an example of demand forecast error information according to the embodiment of the present invention. FIG. 11 illustrates an example of upper limit information of the number of days for advanced transportation according to the embodiment of the present invention. FIG. 11 illustrates an example of transportation volume upper limit information according to the embodiment of the present invention. FIG. 11 illustrates an example of transportation volume information according to the embodiment of the present invention. FIG. 11 illustrates an example of transportation number information according to the embodiment of the present invention. FIG. 11 is a diagram illustrating an example of incoming/outgoing inventory information according to an embodiment of the present invention. FIG. 11 illustrates an example of cost information according to the embodiment of the present invention. FIG. 11 illustrates an example of stock-out rate information according to the embodiment of the present invention. 1 is a flowchart illustrating an example of an inventory planning process performed in the inventory planning system according to the embodiment of the present invention. 1 is a graph illustrating an example of the variance of the forecast error and the number of days until the required arrival date, illustrating an embodiment of the present invention. 10 is a flowchart illustrating an example of evaluation processing performed in the inventory planning system according to the embodiment of the present invention. FIG. 2 is a diagram illustrating an example of an input/confirmation screen of the inventory planning system according to the embodiment of the present invention. FIG. 13 is a diagram illustrating an example of a confirmation screen for a planning result of the inventory planning system according to the embodiment of the present invention.

The following describes an embodiment of the present invention with reference to the attached drawings.

Figure 1 is a block diagram showing an example of the configuration of an inventory planning system according to an embodiment of the present invention.

The inventory planning system 1 according to the embodiment of the present invention is composed of a computer having a processor (CPU) 11, a communication interface 12, an input/output interface 13, and a memory 14.

The processor 11, communication interface (communication IF in the figure) 12, input/output interface (input/output IF in the figure) 13 and memory 14 are connected to each other so as to be accessible via a communication means such as a bus (not shown).

The processor 11 is a computing device that executes programs stored in the memory 14. The processor 11 executes various programs to realize various functions of the inventory planning system 1. Note that some of the processing performed by the processor 11 by executing the programs may be executed by another computing device (for example, a hardware FPGA or ASIC).

The memory 14 includes a ROM, which is a non-volatile storage element, and a RAM, which is a volatile storage device. The ROM stores immutable programs (e.g., BIOS, UEFI), etc. The RAM is a high-speed, volatile storage device such as a DRAM (Dynamic Random Access Memory), and temporarily stores programs executed by the processor 11 and data used when executing the programs (e.g., data read from the storage device 2).

For example, the processor 11 functions as a transport volume upper limit determination unit f1 by executing a transport volume upper limit determination program. The transport volume upper limit determination unit f1 determines the transport volume upper limit on a daily basis based on various data including demand forecast information.

The processor 11 also executes an inventory planning program to function as an inventory planning unit f2. The inventory planning unit f2 creates an inventory plan based on various data including transportation volume upper limit information.

The processor 11 also functions as a total cost evaluation unit f3 by executing a total cost evaluation program. The total cost evaluation unit f3 evaluates the total cost of the inventory plan based on various data including the inventory plan information.

The processor 11 also executes a screen generation program to function as a screen generation unit f4. The screen generation unit f4 generates data to be displayed on the screen so that the user can visually check the daily determined transportation volume upper limit, the inventory plan, and the total cost and stockout rate.

The communication interface 12 is a network interface device that controls communication with other devices according to a specified protocol.

The input/output interface 13 is connected to output devices such as a display device (not shown) and a printer (not shown), and input devices such as a keyboard (not shown), a mouse (not shown), and a touch panel (not shown), and is an interface that outputs the results of program execution in a format that can be viewed by the user and receives input from the user.

The programs executed by the processor 11 are provided to the server via removable media (CD-ROM, flash memory, etc.) or a network, and are stored in non-volatile memory 14, which is a non-transient storage medium, or in an auxiliary storage device. For this reason, the inventory planning system 1 should have an interface for reading data from the network or removable media.

The inventory planning system 1 is a computer system that is configured on one physical computer, or on multiple logically or physically configured computers, and may run on a virtual computer built on multiple physical computer resources.

The inventory planning system 1 is connected to a storage device 2. The storage device 2 has a large capacity, non-volatile storage device such as a magnetic storage device (HDD) or a flash memory (SSD), and stores data used by the processor 11 when executing a program.

For example, the storage device 2 stores data used by the inventory planning system 1 for calculation processing, such as product information i1, base information i2, demand forecast information by day, product, and route i3, route information i4, vehicle type information i5, transportation constraint information by day, route, and vehicle type i6, unit price information by product and base i7, initial inventory information by product and base i8, stock-out rate upper limit information by product i9, demand forecast error information i10, and advanced transportation days upper limit information by product and route i11. Note that product information i1 to advanced transportation days upper limit information i11 are preset information.

The storage device 2 also stores transportation volume upper limit information o1 and inventory planning information o2 by day, product, and route that are output by the inventory planning system 1 as a result of calculation processing.

The inventory planning information o2 includes transportation volume information o21 by day, product, and route, transportation volume information o22 by day, vehicle type, and route, incoming/outgoing inventory volume information o23 by day, product, and base, cost information o24, and stockout rate information o25. Details of this information will be described later. The storage device 2 may also store a program executed by the processor 11.

In the configuration shown in FIG. 1, a storage device 2 is provided separately from the inventory planning system 1, but an auxiliary storage device, which is a non-volatile storage device for storing data, may also be provided within the inventory planning system 1.

The inventory planning system 1 may be connected to other systems (e.g., a customer POS system 3, a production planning system 4, an inventory management system 5, and a transportation management system 6) via a communication interface 12.

The customer POS system is a system for managing the sales of goods at retail stores, and is also used by retail stores to order goods. The production planning system 4 is a system for planning the production of goods at each base, such as a factory. The shipping management system 5 is a system for managing the shipping of goods at each base, such as a factory or a warehouse. The transportation management system 6 is a system for transport companies to manage the operation of transportation means.

For example, the inventory planning system 1 collects product demand forecast information and order information sent from the customer POS system 3, generates the required arrival date and predicted required quantity for each product, determines the upper limit of transportation volume on a daily basis, and creates and outputs the minimum-cost inventory plan.

Based on the output inventory plan, the production planning system 4 can create a production plan, the shipping management system 5 can generate shipping instructions, and the transportation management system 6 can generate dispatch instructions.

Figure 2 is an example of product information i1. Product information i1 has at least a data item that defines the "product name" (i101). It may also have data items of index values that indicate the load on the storage capacity of the warehouse, such as the "unit weight" (i102), which is the weight per unit quantity of the product, and the "unit volume" (i103), which is the volume per unit quantity of the product.

In this embodiment, the unit quantity is hereinafter referred to as "pieces", but other units such as cases or pallets may be used. Also, in this embodiment, the unit of volume is cubic meters, but other units such as liters may be used. Also, a data item for "upper limit of storage days" (i104) may be included. Products for which upper limit of storage days i104 is set must be discarded if the number of days of storage after entering the warehouse exceeds upper limit of storage days i104.

Figure 3 is an example of base information i2. Base information i2 has at least a data item that defines "base name" (i201). It may also have data items of index values that indicate the upper limit of the storage capacity of the warehouse, such as "inventory storage volume limit" (i203), "inventory storage quantity limit" (not shown), and "inventory storage weight limit" (not shown).

In this embodiment, the unit of inventory storage volume upper limit i203 is cubic meters, but other units such as liters may also be used. In addition, there may be data items of index values indicating the upper limit of the warehouse's work capacity, such as "upper limit of incoming volume (i204)" and "upper limit of outgoing volume" (i205). There may also be data items of information used to determine whether each product can be stored, such as "presence of refrigeration function" (not shown) and "presence of crane" (not shown).

It may also have a data item of "base operating days" (not shown) that defines the days on which goods can be received and shipped from the base (not shown). It may also have data items of "address" (i202) and "latitude and longitude" (not shown) that indicate the geographic location of the base.

Figure 4 is an example of demand forecast information i3 by arrival date, product, and route. Demand forecast information i3 by date, product, and route has at least the following data items: "Forecast date" (i302), "Requested arrival date" (i303), "Product name" (i304), "Name of origin" (i305), "Name of destination" (i306), and "Forecasted demand quantity" (i307).

The forecast date i302 is the date on which the demand forecast data was generated. The demand forecast information i3 indicates that the specified product must be delivered to the destination location i306 in the amount of the forecasted request amount i307 by the arrival request date i303. The demand forecast information i3 may also have a data item of the order ID i301 that is set for each order. The forecasted request amount i307 corresponds to the demand forecast amount.

Figure 5 is an example of route information i4. Route information i4 has data items that define at least the "origin base name" (i401) and the "destination base name" (i402). The origin base name i401 is the name of the base that is the departure point. The destination base name i402 is the name of the base that is the arrival point. It may also include information on "transportation time required" (i403) that defines the time required for transportation from departure from the origin base to arrival at the destination base. When costs proportional to the transportation volume are continuously added as transportation costs, a "transportation unit price" (not shown, units of $/m3, $/kg, $/CS (number of cases), etc.) that is the transportation unit price per unit volume may be defined.

Figure 6 shows an example of vehicle type information i5, which includes the data items "Vehicle type name" (i501) and "Load capacity limit" (i502, i503). Load capacity limits i502 and i503 are the upper limit of the load capacity per vehicle, and in addition to the weight limit and volume limit shown in the figure, data items such as quantity limit (number of pallets, etc.) may be added or replaced with these.

Figure 7 is an example of transport constraint information i6 by day, route and vehicle type. Transport constraint information i6 by day, route and vehicle type has at least the data items "departure date" (i601), "start point name" (i602) and "destination point name" (i603). A data item for "vehicle type name" (i604) may be prepared so that data can be defined by day, route and vehicle type.

The data column for "Maximum number of vehicles transported" (i605) may be defined to set the maximum number of vehicles per departure date as shown in FIG. 7. If a transportation cost proportional to the number of vehicles transported is added per vehicle, the data column for "Unit transportation cost" (i606) may be defined to set the unit cost per vehicle as shown in FIG. 7. Note that the maximum number of vehicles transported i605 may be treated as the upper limit of transportation capacity.

Figure 8 is an example of unit price information i7 by product and location. Unit price information i7 by product and location has at least a data item for "location name" (i702). It may also have a data item for "product name" (i702) and be set for each combination of location and product.

The "storage cost" (i703) is the cost incurred when storing goods at the base. The "storage and shipping work cost" (i704) is the work cost incurred when storing and shipping goods at the base. The storage work cost and the shipping work cost may be defined separately.

The "unit cost of disposal" (i705) is the unit cost incurred when the number of days that a product is stored at the site exceeds the upper limit of storage days i104 and the product is to be disposed of. The unit of currency may be dollars, yen, etc. The unit of quantity may be CS, pieces, lots, pallets, m3, kg, etc.

It also has data items for "equipment name" (not shown) and "workload per CS" (not shown) to define the workload per CS when working using that equipment, and can also separately define the upper limit of the workload per day for each piece of equipment.

Figure 9 shows an example of initial inventory information i8 by product and location. Initial inventory information i8 has at least the following data items: "Product name" (i801), "Location name" (i802), "Storage start date" (i803), and "Initial inventory amount" (i804).

Initial inventory information i8 allows you to set the initial inventory amount for each combination of product and location.

Figure 10 is an example of upper limit information i9 on stockout rates by product. Upper limit information i9 on stockout rates has at least the data items "Product name" (i901) and "Upper limit information on stockout rates" (i902).

The stockout rate upper limit information i9 can set the stockout rate upper limit for each product. The stockout rate upper limit information i9 can also be set for each combination of product and destination location by adding a data item for "destination location name" (not shown).

Figure 11 is an example of the demand forecast error information i10. The demand forecast error information i10 can set statistical values of the forecast error, such as "variance of forecast error" (i1004), for each combination of "product name" (i1001), "destination base name" (i1002), and "number of days until requested arrival date" (i1003).

In well-known or publicly known examples, the shorter the number of days until the requested arrival date, the more likely it is that the order will be confirmed. Therefore, for example, it is sufficient to set the number of days until the requested arrival date i1003 to be shorter, so that the variance of the forecast error becomes smaller.

Furthermore, compared to standard products for which a constant demand is expected, the variance i1004 of the forecast error can be set to be larger for seasonal products and products whose demand is subject to sudden fluctuations. Furthermore, the variance i1004 of the forecast error can be set for each destination base name i1002 according to the characteristics of orders from that destination base. The variance i1004 of the forecast error can be treated as statistical data of the demand forecast error.

Instead of "Product name" (i1001) and "Destination location name" (i1002), a data item "Order ID" (not shown) may be added, and the variance of the forecast error may be set for each combination of the number of days until the requested arrival date i1003 for each individual order ID. In addition, if the forecast error does not follow a normal distribution, the variance when the forecast is below average and the variance when the forecast is above average may be set separately (not shown).

Figure 12 is an example of information i11 about the upper limit of the number of days for advanced transport by product and route. Information i11 about the upper limit of the number of days for advanced transport has the following data items: "Product name" (i1101), "Name of departure base" (i1102), "Name of arrival base" (i1103), and "Upper limit of the number of days for advanced transport" (i1104).

The information i11 on the upper limit of days for advanced transport can set the upper limit of days for advanced transport i1104, which is the upper limit of the number of days between the requested arrival date and the arrival date due to advanced transport when transporting ahead of the requested arrival date, for a combination of a product name and a route consisting of a combination of a departure base name and a destination base name.

Figure 13 is an example of transportation volume upper limit information o1 by day, product, and route output by the inventory planning system 1. The transportation volume upper limit information o1 has the following data items: "Departure date" (o101), "Product name" (o102), "Departure base name" (o103), "Destination base name" (o104), and "Transport volume upper limit" (o105).

The transportation volume upper limit information o1 stores the transportation volume upper limit determined by the inventory planning system 1 for a route combination consisting of a departure date, a product name, and a combination of a departure base name and a destination base name.

Figures 14 to 18 are examples of transportation volume information o21 by day, product, and route, transportation volume information o22 by day and route, inventory quantity information o23 by day, product, and base, cost information o24, and stockout rate information o25, which make up the inventory planning information o2 output by the inventory planning system 1.

Figure 14 is an example of transportation volume information o21 by day, product, and route. The transportation volume information o21 has the following data items: "Departure date" (o2101), "Product name" (o2102), "Departure base name" (o2103), "Destination base name" (o2104), "Vehicle model name" (o2105), and "Transport volume" (o2106).

The transportation volume information o21 stores the transportation volume o2106 that is planned as an inventory plan by the inventory planning system 1 for a route combination consisting of a combination of a departure date o2101, a product name o2102, a vehicle model name o2105, a departure base name o2103, and a destination base name o2104.

Figure 15 is an example of information o22 on the number of vehicles transported by date, vehicle type, and route. Information o22 on the number of vehicles transported has the following data items: "Departure date" (o2201), "Vehicle type name" (o2202), "Departure base name" (o2203), "Destination base name" (o2204), and "Number of vehicles transported" (o2205).

The transport volume information o22 stores the number of transported vehicles o2205 that is planned as an inventory plan by the inventory planning system 1 for a route combination consisting of a combination of the departure date o2201, the vehicle model name o2202, the departure base name o2203, and the destination base name o2204.

Figure 16 is an example of incoming/outgoing inventory and inventory information o23 by day, product, and location. The incoming/outgoing inventory and inventory information o23 has the following data items: "Date" (o2301), "Product name" (o2302), "Location name" (o2303), "Incoming inventory amount" (o2304), "Outgoing inventory amount" (o2305), "Discard amount" (o2306), "Requested outgoing inventory amount" (o2307), "Out of stock amount" (o2308), and "Inventory amount" (o2309).

The incoming/outgoing inventory/inventory information o23 stores the incoming amount o2304, outgoing amount o2305, waste amount o2306, outgoing request amount o2307, stockout amount o2308, and inventory amount o2309 that are planned as an inventory plan by the inventory planning system 1 for the combination of date o2301, product name o2302, and base name o2303. Note that the combination of the incoming amount o2304 and outgoing amount o2305 can be treated as the incoming/outgoing amount.

Figure 17 is an example of cost information o24. The cost information o24 has the following data items: "Date" (o2401), "Transportation cost" (o2402), "Storage cost" (o2403), "Disposal cost" (o2404), "Warehousing operation cost" (o2405), "Shipping operation cost" (o2406), and "Total cost" (o2407).

The cost information o24 stores the costs of transportation, storage, disposal, warehousing, and shipping operations for each date o2401 calculated for the inventory plan drawn up by the inventory planning system 1, as well as the total cost o2407, which is the sum of these costs. Other data items such as fixed costs for bases and facilities, production costs, and procurement costs may also be defined (none of which are shown).

Figure 18 is an example of stockout rate information o25. The stockout rate information o25 has the data items "Product name" (o2501), "Total requested quantity" (o2502), "Total stockout quantity" (o2503), and "Stockout rate" (o2504).

The stockout rate information o25 stores the total requested quantity by product o2502, the total stockout amount o2503, and the stockout rate o2504 calculated for the inventory plan drawn up by the inventory planning system 1. By adding data items such as "originating location name" (not shown) and "destination location name" (not shown), information such as the stockout rate for each combination may be stored.

Figure 19 is a flowchart S1 of the inventory planning process by the inventory planning system 1. This process is started when a command is received from a user (or administrator) of the inventory planning system 1, or when a calculation start condition, such as a weekly calculation date and time, is met. In the following explanation, each functional unit is described as the subject of processing, but the processor 11 or the inventory planning system 1 can also be interpreted as the subject of processing.

First, the inventory planning system 1 imports product information i1 through advanced transportation days upper limit information i11 as input data from the storage device 2 (S10).

Next, the transportation volume upper limit determination unit f1 uses the data of the forecast demand volume i307 in the daily, product, and route-specific demand forecast information i3 and the forecast error variance i1004 by number of days until the requested arrival date i1003 in the demand forecast error information i10 to determine the daily, product, and route-specific transportation volume upper limit o105, and stores it in the daily, product, and route-specific transportation volume upper limit information o1 (S11).

Next, the inventory planning unit f2 creates an inventory plan consisting of daily, product, and route-specific transportation volume information o21, daily, vehicle type, and route-specific transportation volume information o22, and daily, product, and base-specific incoming/outgoing inventory volume information o23, so as to satisfy the transportation volume upper limit o105 determined in step S11 and the daily, route, and vehicle type-specific transportation volume upper limit i605 in the daily, route, and vehicle type-specific transportation constraint information i6 (S12).

Next, the total cost evaluation unit f3 evaluates the total cost o2407, including the costs of transportation, storage, disposal, warehousing, and shipping, and the stockout rate o2504, when the inventory plan devised in step S12 is executed, taking into account the demand forecast error, and stores the results in the cost information o24 and the stockout rate information o25 (S13).

Next, the total cost evaluation unit f3 determines whether the stockout rate o2504 in step S13 satisfies the stockout rate upper limit i902 set in the product-specific stockout rate upper limit information i9, and if there is a tentative solution saved up to that point, whether the total cost o2407 evaluated in step S13 is cheaper than the total cost of the inventory plan of that tentative solution (S14).

If the total cost in step S13 is lower, the total cost evaluation unit f3 saves the inventory plan drawn up in step S12 and the total cost o2407 and stockout rate o2504 evaluated in step S13 as a provisional solution (S15).

Next, the total cost evaluation unit f3 determines whether a predetermined termination condition (described below) is satisfied (S16). If the predetermined termination condition is satisfied, the total cost evaluation unit f3 stores the provisional solution as the minimum-cost inventory plan and outputs it (S17).

If the specified termination condition is not met, the total cost evaluation unit f3 repeats the above steps S12 to S16 until the termination condition is met.

The details of step S10 will now be described. From the captured input data, the screen generation unit f4 generates display data, which may be output from the input/output interface 13 and displayed on a display device or the like.

For example, d1 shown in FIG. 22 is an example of an input/confirmation screen for data for inventory planning. The input/confirmation screen d1 for data for inventory planning can display each input data, such as transportation constraint information by date, route, and vehicle type (d11) and demand forecast error information (d12).

In addition, on the input/confirmation screen d1 for inventory planning data, the user may be allowed to directly edit/update the input data by pressing an edit input data button (d13). In addition, the process from step S11 onward shown in FIG. 19 may be started by pressing an execute planning button (d14).

Details of step S11 will be described. In step S11, the transportation volume upper limit determination unit f1 determines the transportation volume upper limit o105 by day, product, and route using the forecast demand volume i307 in the daily, product, and route-specific demand forecast information i3 and the data on the variance i1004 of the forecast error by number of days i1003 until the arrival request date in the demand forecast error information i10.

In addition, data on the upper limit of the number of days for advanced transportation in the information on the upper limit of the number of days for advanced transportation by product and route i11 may also be used to determine the upper limit of the transportation volume o105. For example, for a product i ordered from a base w to a base f, the departure date t of a route (f, w) with the departure base f and the destination base w, and the upper limit of the transportation volume trans _ub (t, i, f, w) for the product i can be determined, for example, as follows:

·set:
Planning target dates: 0, 1, ..., T
・Collection of products: I
Set of orders for product i, arrival location w, and required date τ: O(i, w, τ)

・Constant: Hereinafter, o∈O, t∈T
・Procurement LT (lead time): ProcLT
Upper limit of number of days for advanced transportation of product i, route (f, w): MoveUpDayCntUB
Variance of demand forecast error for product i, arrival location w, and number of days until arrival request date ρ: σ(i, w, ρ)
Forecasted demand quantity of order o: OrderQty(o)
Request date of order o: ArrivalDay(o)
The amount of the forecasted required quantity of order o that can depart on departure date t: OrderQty(o, t) can be expressed as follows:

Here, the weighting coefficient of the variance in determining the upper limit of the traffic volume is k
Then,
A formula for determining the upper transportation volume limit for product i, departure date t, and route (f, w): trans _ub (t, i, f, w) can be expressed as follows.

The above formula (2) calculates the upper limit of transportation volume for each departure date as the sum of the values obtained by subtracting the demand forecast variance corresponding to the number of days from the departure date to the order's requested arrival date, weighted by a coefficient, from the order's forecast required volume i307 for all orders of the target product and route that can be transported on that departure date.

Here, the demand forecast variance σ(i, w, ρ) may be set for each product name, arrival point, and number of days until the requested arrival date i1003, as in the example of FIG. 11 described above, or a function may be used, as in the graph of FIG. 20, in which the variance is large when the number of days until the requested arrival date is long and the variance decreases as the number of days until the requested arrival date decreases. Functions such as (a), (b), and (c) in the figure may be used depending on the slope at which the variance decreases as the number of days until the requested arrival date becomes shorter.

Next, step S12 will be described in detail. In step S12, an inventory plan is created that includes daily, product, and route-specific transportation volume information o21, daily, vehicle type, and route-specific transportation volume information o22, and daily, product, and base-specific incoming/outgoing inventory volume information o23, so as to satisfy the transportation volume upper limit o105 determined in step S11 and the daily, route, and vehicle type-specific transportation volume upper limit i105 in the daily, route, and vehicle type-specific transportation constraint information i6.

As a method of creating an inventory plan, for example, all possible combinations of transportation volume, number of transported vehicles, incoming and outgoing volume, inventory volume, waste volume, and stockout volume may be automatically generated to generate all possible inventory plans. Then, from all the generated inventory plans, the process from step S12 to step S16 may be repeated for each inventory plan to search for all possible combinations, and an inventory plan that satisfies the upper limit of stockout rate i902 and minimizes the total cost o2407 may be determined.

Another method of creating an inventory plan is to allocate transportation to capacity slots with leeway up to the transportation volume upper limit o105 and the transportation number upper limit i605 so as to satisfy the requested quantity of the order, starting with the order with the latest requested arrival date among all orders, and to determine the transportation volume o2106 by day, product, and route by allocating the amount exceeding the capacity slots ahead of schedule.

For departure date t, route p, vehicle type v, and product i, the number of vehicles transported vcnt(t, p, v) can be calculated using the following formula based on the transport volume trans(t, p, v, i).

The constants are
Unit volume of item i: ItemUnitVol(i)
・ Loading volume upper limit of vehicle type v: VehicleVolUB(i)
The calculation formula for the number of transported vehicles vcnt(t, p, v) can be expressed as follows:

The above formula (3) only considers the volume as the upper load capacity limit i503, but if weight is also considered, the larger of the number of transported vehicles calculated for the upper load capacity limit and the number of transported vehicles calculated for the upper load weight limit can be used.

Based on the above transportation volume, the inventory volume by day, location, and product o2304 is calculated as the sum of the transportation volumes of all routes from upstream for the same arrival date and the same product.

The inventory volume by day, location, and product o2304 is calculated as the sum of the transportation volume for all routes from upstream for the same arrival date and the same product.

The amount of waste by day, location, and product is calculated as the total value of the amount of inventory by location and product on that day for which the number of days stored from the storage start date exceeds the upper limit for storage days.

For date t, location w, and product i, the inventory amount by day, location, and product, stock(t,w,i), is calculated using the incoming amount in(t,w,i) calculated using the method above, the outgoing amount out(t,w,i), and the discarded amount dispose(t,w,i) using the following formula.

The constants are
Initial stock amount: InitStock(w, i)
Then, the inventory amount stock(t, w, i) can be expressed by the following equation.

When defining the inventory storage volume upper limit i203, the incoming volume upper limit i204, and the outgoing volume upper limit i205 in the base information i2, the incoming volume or outgoing volume that exceeds the upper limit can be corrected to be below the upper limit, and that amount can be treated as a shortage.

The stockout quantity shortenage(t,w,i) by day, location, and product is calculated using the request quantity requestQty(t,p,i) (p∈P) from downstream for a set P of routes downstream of location w, as follows:

The formula for calculating the requested delivery quantity from downstream to base w, requestQty(t, w, i), is given as follows:

The formula for calculating the shortage amount, shorten(t, w, i), is as follows:

Next, step S13 will be described in detail. In step S13, the total cost o2407, including the costs of transportation, storage, disposal, warehousing, and shipping, and the stockout rate o2504, when the inventory plan devised in step S12 is executed, are evaluated taking into account the demand forecast error. A flowchart S2 of an example of the evaluation process performed in step S13 is shown in FIG. 21.

First, in step S21, the total cost evaluation unit f3 generates an expected demand amount by day, product, and route that is expected as actual demand based on the predicted demand amount i307 in the demand forecast information i3 by day, product, and route, and the variance i1004 of the forecast error in the demand forecast error information i10. The expected demand amount can be generated by adding random noise generated based on the variance i1004 of the forecast error to the predicted demand amount i307.

Next, in step S22, the total cost evaluation unit f3 simulates the transportation volume, number of transported vehicles, incoming and outgoing volume, inventory volume, waste volume, stockout volume, and outgoing volume request volume when the inventory plan devised in step S12 based on the demand forecast is executed and the actual demand is the estimated demand volume generated in step S21, and a difference between the forecast and actual demand occurs, one day at a time from the first day of the planning period until the final day is reached.

For example, if demand falls short on a certain day, some of the inventory held in preparation for that demand will become surplus and will be rolled over to the next day. If demand rises on a certain day and exceeds inventory, a shortage will occur, inventory will reach zero, and inventory will be rolled over to the next day. By repeating this process until the final day, it is possible to simulate the trends in each quantity, taking into account errors in the demand forecast.

Finally, in step S23, the total cost evaluation unit f3 evaluates the total cost and stockout rate based on the transportation volume, number of transported units, incoming and outgoing volume, inventory volume, waste volume, stockout volume, and outgoing request volume obtained as a result of the simulation, using the following formula.

The constants are the transportation cost TransUnitCost(t,p,v), the storage cost StockUnitCost(w,i), the disposal cost DisposalUnitCost(w,i), the input cost InputUnitCost(w,i), and the output cost OutputUnitCost(w,i).

The variables are total cost (totCost), transportation cost (transCost), storage cost (stockCost), disposal cost (disposalCost), inputCost (inputCost), outputCost (outputCost), and stockout rate (shorthageRate).

The cost calculation formula can be expressed as follows:

The formula for calculating the stockout rate can be expressed as follows:

In the above example, the transportation cost transCost (o2402) is calculated per vehicle, but a variable cost term that is continuously calculated in proportion to the transportation volume may be added.

Next, steps S14 and S15 will be described in detail. In the example of FIG. 19, a provisional solution is saved only when the upper limit i902 of the stockout rate is satisfied and the total cost o2407 is lower than the provisional solution. However, even if the upper limit i902 of the stockout rate is not satisfied, the provisional solution may be saved as a plan that relaxes the condition of the upper limit i902 of the stockout rate, and even if the total cost o2407 is higher, all plans may be saved as the next best plan, etc.

Details of step S16 will be described. As termination conditions for the process in FIG. 19, an upper limit for the number of repetitions of the process from step S12 to step S16, a lower limit for the total cost o2407, a lower limit for the improvement rate of the total cost o2407, etc. are set, and when the upper or lower limit is reached, it is determined that the termination conditions are met and the process proceeds to step S17.

If the termination condition is not met, the processes from step S12 to step S16 are repeated. In this case, in step S12, for example, in the case of a full search, an inventory plan may be generated for combinations of unsearched transport volume, number of transported vehicles, incoming and outgoing volumes, inventory volume, waste volume, and stockout volume. Alternatively, a new inventory plan may be generated by increasing or decreasing some of the quantities in the inventory plan of the provisional solution.

Details of step S17 will now be described. The total cost evaluation unit f3 saves the tentative solution as the minimum-cost inventory plan, and the screen generation unit f4 generates display data. The generated data is output from the input/output interface 13 and displayed on a display device or the like.

Figure 23 is an example of the display of a confirmation screen d2 for the planning results. The confirmation screen d2 may display the results of planning for maximum transportation volume by day, product, and route (d21), and the results of inventory planning (d22).

Also, as described above, if plan proposals other than the minimum-cost plan have been saved, pressing the Display Other Plans button (d23) at the bottom of the figure may display plans other than the minimum-cost plan, allowing the user to compare the minimum-cost inventory plan proposal with the other plans and select the most preferable plan. Pressing the Adopt button (d24) may adopt the displayed inventory plan and use it in actual operations.

The inventory planning results d22 may be displayed as a time series graph showing the number of vehicles to be transported, the required amount, and the stock amount for each date (d221). The graph of the number of vehicles to be transported may display the upper limit and the planned value of the number of vehicles to be transported by route and vehicle type. The graph of the required amount may display the forecast required amount i307 by forecast date set in the demand forecast information i3 by day, product, and route, and the estimated required amount by day, product, and route generated in step S21 of FIG. 21 and used in the simulation taking into account the demand forecast error. The graph of the inventory amount may display the inventory amount by product.

The time series graph d221 may also display a comparison between an inventory plan (d2211) drawn up without a transportation volume upper limit and a minimum-cost inventory plan (d2212) calculated with a transportation volume upper limit. In the example of FIG. 23, the forecast demand volume for May and June is 30 units for each of products A through C, whereas the expected demand volume assumed as the actual demand volume is 22 units for each product.

In contrast, in the plan with no upper limit on transportation volume (d2211), in order to meet the upper limit on the number of units to be transported, 30 units of A and B were transported ahead of schedule during May and June, which caused demand to fall to 22 units each in July, resulting in surplus inventory of 8 units each of A and B.

On the other hand, in the minimum cost inventory plan with transportation volume upper limit (d2212) using the transportation volume upper limit determined in step S11, 10 units of each product A through C are transported ahead of schedule in each of May and June, and after the required quantity for each product is confirmed as 22 units in July, 2 units of each product A through C are transported, reducing the excess inventory of A through C to zero. Also, the number of vehicles in July was reduced in line with the decline in demand.

As a display of the inventory plan creation results d22, the total cost of the creation results may be displayed in a stacked graph for each cost item (d222). Also, the stockout rate of the creation results may be displayed in a graph together with the stockout rate upper limit (d223). As in the example of Figure 23, both the cost d222 and the stockout rate d223 may be displayed to compare the results of the creation without a transportation volume upper limit and the minimum cost inventory plan created with a transportation volume upper limit determined.

In the above example, a method was shown for searching for a plan with the lowest total cost o2407 by generating all combinations or by increasing or decreasing some of the quantities of items in the provisional solution to generate a new inventory plan, but the present invention is not limited to such a method. For example, an inventory plan may be created under the conditions entered above so as to minimize the total cost using a mathematical optimization method such as mixed integer programming.

In the above, a method for creating an inventory plan with the minimum total cost o2407 has been described, but for example, an inventory plan may be generated based on demand forecast information i3 by day, product, and route, in which products are shipped and transported in order of earliest requested date so that the requested quantity can be delivered by the input arrival request date i303.

<Conclusion>
As described above, the inventory planning system 1 of this embodiment can plan a transportation volume that reduces storage costs and disposal costs due to surplus inventory that occurs when demand drops, by setting the transportation volume upper limit o105 based on the demand forecast volume (forecasted required volume i307) and statistical data of the demand forecast error that changes depending on the number of days until the arrival request date i1003 (variance of the forecast error i1004). Also, by planning an inventory plan that satisfies the above-mentioned transportation volume upper limit and transportation number upper limit and minimizes the total cost including the transportation cost, storage cost, and disposal cost added per vehicle, it is possible to determine the transportation volume that minimizes the cost of the entire supply chain.

The inventory planning system 1 of this embodiment has been developed in consideration of the above-mentioned problems, and plans divided transports that are brought forward from the busy season, taking into account the upper limit on the number of units to be transported. In doing so, in periods when the number of days until the requested arrival date is long and the accuracy of the demand forecast is low, the transport volume is determined to minimize the amount of transport that is brought forward, in order to reduce excess inventory when actual demand falls short of the forecast.

The above is achieved by following the steps below. First, a daily and product-specific transportation volume upper limit is set based on the predicted demand volume by day and product, and the accuracy of the demand forecast, which changes depending on the number of days until the required arrival date. Next, taking into account the determined daily and product-specific transportation volume upper limit and the daily transportation number upper limit, an inventory plan is created consisting of daily and product-specific transportation volumes, incoming and outgoing volumes, and inventory volumes. The total cost, which is the sum of the costs of transportation, storage, disposal, work, etc. required to execute the plan, is calculated, and an inventory plan that minimizes the total cost is created.

A representative example of the invention disclosed in this embodiment is as follows. That is, the inventory planning system has a calculation device that executes a predetermined process and a memory accessible to the calculation device, and the calculation device determines an upper limit of the transportation volume based on the demand forecast volume and statistical data of the forecast error such as the variance of the demand forecast error that changes depending on the number of days until the arrival request date, determines the transportation volume and the number of transported units so as to satisfy the upper limit of the transportation volume and the upper limit of the number of transported units, calculates the incoming/outgoing volume and the inventory volume from the transportation volume, calculates the costs of transportation, storage, disposal, work, etc. from the transportation volume, the number of transported units, the incoming/outgoing volume, and the inventory volume, and outputs an inventory plan consisting of the transportation volume, the number of transported units, the incoming/outgoing volume, and the inventory volume when the total cost, which is the sum of the costs, is minimized.

The inventory planning system of the above embodiment can be configured as follows:

(1) An inventory planning system (1) having a calculation device (processor 11) that executes a predetermined process and a memory (14) accessible to the calculation device (11), wherein the calculation device (11) receives as input a previously set demand forecast amount (predicted demand amount i307) for an item and statistical data of a demand forecast error (variance of forecast error i1004) that changes depending on the number of days until the required arrival date of the item (i1003), performs a predetermined process on the demand forecast amount (i307) and the statistical data (i1004), and determines and outputs an upper limit of the transportation volume (o105) for the item on a daily basis.

With the above configuration, the inventory planning system 1 can set the upper limit of the transportation volume on a daily basis based on the demand forecast volume and statistical data on the demand forecast error that changes depending on the number of days until the required arrival date, thereby planning the transportation volume that reduces the storage costs and disposal costs due to excess inventory that arise when demand falls.

(2) The inventory planning system described in (1) above, wherein the calculation device (11) uses an upper limit on the number of days for advanced transportation (upper limit on number of days for advanced transportation i1104) when transporting goods ahead of the requested arrival date (i303) in determining the upper limit on the transportation volume (o105).

With the above configuration, the inventory planning system 1 plans split transportation ahead of the busy season, taking into account the upper limit of the number of vehicles to be transported i605. In doing so, it becomes possible to reduce excess inventory when actual demand falls short of the forecast. In addition, the inventory planning system 1 can also reduce the number of vehicles in line with the fall in demand.

(3) The inventory planning system described in (2) above, wherein the calculation device (11) determines the transportation volume (o2106) of the item so as to satisfy the determined transportation volume upper limit (o105) and a preset transportation capacity upper limit (transportation number upper limit i605 and vehicle model name i604), calculates the inbound/outbound volume and inventory volume from the transportation volume (o2106), and outputs an inventory plan (d2) consisting of the transportation volume (o2106), the inbound/outbound volume (inbound volume o2304 and outbound volume o2305), and the inventory volume (o2306).

With the above configuration, the inventory planning system 1 can set the transportation volume upper limit o105 based on the demand forecast volume and statistical data on the demand forecast error (variance of the forecast error i1004) that changes depending on the number of days until the required arrival date i1003, thereby planning the transportation volume that reduces the storage costs and disposal costs due to excess inventory that arise when demand falls.

(4) The inventory planning system described in (3) above, wherein the calculation device (11) calculates and outputs at least one of the transportation cost (o2402), storage cost (o2403), disposal cost (o2404), and inventory work cost (o2405, o2406) based on the determined transportation volume (o2106), inventory volume (o2304, o2305), inventory volume (o2306), and the preset transportation unit price (i606), storage unit price (i703), disposal unit price (i705), and inventory work unit price (i704).

The above configuration allows for the determination of the transportation volume that minimizes the cost of the entire supply chain by creating an inventory plan that satisfies the upper limit of transportation volume and the upper limit of the number of vehicles to be transported and minimizes the total cost, including transportation costs, storage costs, and disposal costs, which are added on a vehicle-by-vehicle basis.

(5) The inventory planning system described in (4) above, wherein the calculation device (11) calculates a total cost (o2407) which is the sum of the calculated transportation cost (o2402), storage cost (o2403), disposal cost (o2404), and inbound/outbound work costs (o2405, o2406), and outputs an inventory plan (d2) consisting of the transportation volume (o2106), inbound/outbound volume (o2304, o2305), and inventory volume (o2306) that minimizes the total cost (o2407).

With the above configuration, the inventory planning system 1 can determine the transportation volume that minimizes the cost of the entire supply chain by creating an inventory plan that satisfies the upper limit of transportation volume and the upper limit of the number of vehicles to be transported and minimizes the total cost, including transportation costs, storage costs, and disposal costs, which are added on a per-vehicle basis.

(6) An inventory planning system according to (5) above, characterized in that the calculation device (11) calculates and outputs the stockout rate (o2504) based on the determined transportation volume (o2106), incoming and outgoing volumes (o2304, o2305), and inventory volume (o2306).

With the above configuration, the inventory planning system 1 can reduce the stockout rate by creating an inventory plan that meets the upper limit of transportation volume and the upper limit of transportation number, and minimizes the total cost, including transportation costs, storage costs, and disposal costs, which are added on a per-vehicle basis.

(7) The inventory planning system according to (6) above, wherein the calculation device (11) outputs the inventory plan (d2) in which the stockout rate (o2504) satisfies a predetermined stockout rate upper limit (i902) and the total cost (o2407) is minimized.

With the above configuration, the inventory planning system 1 can reduce the stockout rate by creating an inventory plan that meets the upper limit of transportation volume and the upper limit of transportation number, and minimizes the total cost, including transportation costs, storage costs, and disposal costs, which are added on a per-vehicle basis.

(8) The inventory planning system described in (7) above, wherein the calculation device (11) defines the transport capacity upper limit (i605, i604) as the upper limit of the number of transported units (i605), determines the transport volume (o2106) so as to satisfy the upper limit of the transport volume (o105) and the upper limit of the number of transported units (i605), calculates the required number of transported units from the transport volume (o2106), and calculates the transport cost (o2402) based on the transport volume (o2106), the number of transported units (o2205), and the transport unit price (i605).

With the above configuration, the inventory planning system 1 allocates transportation to capacity slots with leeway up to the transportation volume upper limit o105 and the transportation volume upper limit i605 so as to satisfy the requested volume of the order, starting with the order with the latest requested arrival date, among all possible combinations of transportation volume, number of transported units, incoming and outgoing volumes, inventory volume, waste volume, and stockout volume, and allocates the amount exceeding the capacity slots ahead of schedule, thereby planning transportation volumes that reduce storage costs and waste costs due to excess inventory that arise when demand drops. It is also possible to determine transportation volumes o2106 by day, product, and route.

(9) The inventory planning system described in (2) above, wherein the calculation device (11) determines the transportation volume (o2106) so that the products are shipped and transported in order of the earliest arrival request date (i303) so as to satisfy the transportation volume upper limit (o105) and the transportation capacity upper limit (i605, i604).

With the above configuration, the inventory planning system 1 generates an inventory plan to ship and transport products in the order of earliest requested date, making it possible to deliver the requested quantity by the input arrival requested date i303 based on the demand forecast information i3.

As stated above, the present invention is not limited to the above-described embodiments, but includes various modified examples and equivalent configurations within the spirit of the appended claims. For example, the above-described embodiments have been described in detail to clearly explain the present invention, and the present invention is not necessarily limited to having all of the configurations described. Furthermore, part of the configuration of one embodiment may be replaced with the configuration of another embodiment. Furthermore, the configuration of another embodiment may be added to the configuration of one embodiment. Furthermore, part of the configuration of each embodiment may be added, deleted, or replaced with other configurations.

Furthermore, each of the configurations, functions, processing units, processing means, etc. described above may be realized in part or in whole in hardware, for example by designing them as integrated circuits, or may be realized in software by a processor interpreting and executing a program that realizes each function.

Information such as programs, tables, and files that realize each function can be stored in a storage device such as a memory, hard disk, or SSD (Solid State Drive), or in a recording medium such as an IC card, SD card, or DVD.

In addition, the control lines and information lines shown are those considered necessary for explanation, and do not necessarily represent all control lines and information lines necessary for implementation. In reality, it is safe to assume that almost all components are interconnected.

1 Inventory planning system 2 Storage device 11 Processor 12 Communication interface 13 Input/output interface 14 Memory f1 Transport days upper limit determination unit f2 Inventory planning unit f3 Total cost evaluation unit f4 Screen generation unit i1 Product information i2 Base information i3 Demand forecast information i4 Route information i5 Vehicle type information i6 Transport constraint information i7 Unit price information i8 Initial inventory information i9 Stockout rate upper limit information i10 Demand forecast error information o1 Transport volume upper limit information o2 Inventory planning information o21 Transport volume information o22 Transport volume information o23 Inventory/outlet and inventory volume information o24 Cost information o25 Stockout rate information

Claims (13)

A computing device for executing a predetermined process;
and a memory accessible to the computing device,
the computing device receives as input a preset demand forecast amount of the item and statistical data of a demand forecast error that changes depending on the number of days until the required arrival date of the item, performs a predetermined process on the demand forecast amount and the statistical data, and determines and outputs an upper limit of the transportation amount of the item on a daily basis ;
The inventory planning system according to claim 1, wherein the calculation device uses an upper limit of the number of days for which transportation can be brought forward when transporting an item ahead of the required arrival date in determining the upper limit of the transportation volume . 2. The inventory planning system of claim 1,
The inventory planning system is characterized in that the calculation device determines a transportation volume of the item so as to satisfy the determined transportation volume upper limit and a predetermined transportation capacity upper limit, calculates incoming/outgoing volumes and inventory volumes from the transportation volume, and outputs an inventory plan consisting of the transportation volume, the incoming/outgoing volumes, and the inventory volume. 3. The inventory planning system of claim 2,
The inventory planning system is characterized in that the calculation device calculates and outputs at least one of a transportation cost, a storage cost, a disposal cost, and a loading/unloading operation cost based on the determined transportation volume, loading/unloading volume, and inventory volume, and a preset transportation unit cost, storage unit cost, disposal unit cost, and loading/unloading operation unit cost. 4. The inventory planning system of claim 3,
The inventory planning system is characterized in that the calculation device calculates a total cost which is the sum of the calculated transportation costs, storage costs, disposal costs, and incoming and outgoing work costs, and outputs an inventory plan consisting of transportation volumes, incoming and outgoing volumes, and inventory volumes which minimize the total cost. 5. The inventory planning system of claim 4,
The inventory planning system is characterized in that the calculation device calculates and outputs a stockout rate based on the determined transportation volume, incoming/outgoing volume, and inventory volume. 6. The inventory planning system of claim 5,
The inventory planning system is characterized in that the calculation device outputs the inventory plan in which the stock-out rate satisfies a predetermined stock-out rate upper limit and the total cost is minimized. 7. The inventory planning system of claim 6,
The inventory planning system is characterized in that the calculation device defines the transportation capacity upper limit as an upper limit on the number of transported units, determines a transportation volume so as to satisfy the transportation volume upper limit and the transportation number upper limit, calculates the required number of transported units from the transportation volume, and calculates the transportation cost based on the transportation volume, the number of transported units, and the transportation unit price. 2. The inventory planning system of claim 1,
The inventory planning system is characterized in that the calculation device determines a transportation volume so that products are shipped and transported in order of the earliest required arrival date so as to satisfy the transportation volume upper limit and a preset transportation capacity upper limit. 1. An inventory planning method for creating an inventory plan using a computer having a calculation device that executes a predetermined process and a memory accessible by the calculation device, comprising:
an input step in which the computer inputs a preset demand forecast amount of an item and statistical data of a demand forecast error that changes depending on the number of days until the arrival date of the item;
a transportation volume upper limit determination step in which the computer performs a predetermined process on the demand forecast volume and the statistical data to determine and output an upper limit on the transportation volume of the item on a daily basis;
Including,
In the transportation volume upper limit determination step,
a maximum number of days for transportation of an item ahead of said required arrival date, when said upper limit of said transportation volume is determined; 10. The inventory planning method of claim 9, further comprising:
a transportation amount determination step in which the computer determines a transportation amount of the item so as to satisfy the determined transportation amount upper limit and a preset transportation capacity upper limit;
an inventory plan output step in which the computer calculates an incoming/outgoing amount and an inventory amount from the transportation amount, and outputs an inventory plan including the transportation amount, the incoming/outgoing amount, and the inventory amount;
The inventory planning method further comprising: 11. The inventory planning method of claim 10, further comprising:
An inventory planning method characterized by further comprising a cost output step in which the computer calculates and outputs at least one of a transportation cost, a storage cost, a disposal cost, and a loading/unloading operation cost based on the determined transportation volume, loading/unloading volume, and inventory volume, and a preset transportation unit cost, storage unit cost, disposal unit cost, and loading/unloading operation unit cost. 12. The inventory planning method of claim 11, further comprising:
The inventory planning method is characterized in that the inventory plan output step calculates a total cost which is the sum of the calculated transportation costs, storage costs, disposal costs, and incoming and outgoing work costs, and outputs an inventory plan consisting of transportation volumes, incoming and outgoing volumes, and inventory volumes which minimizes the total cost. 13. The inventory planning method of claim 12, further comprising:
The inventory planning method further comprises a stockout rate output step in which the computer calculates and outputs a stockout rate based on the determined transportation volume, incoming/outgoing volume, and inventory volume.

Images