An overall scheduling method based on the operating efficiency of automated container terminal quay cranes

Abstract

The present invention discloses an overall scheduling method based on the operation efficiency of the quay crane of an automated container terminal, comprising the following steps: S1, issuing a loading and unloading instruction to the scheduling system; S2, configuring the target efficiency of each quay crane, the maximum number of IGVs for loading, the maximum number of IGVs for unloading, and the minimum number of IGVs; S3, configuring the maximum number of concurrent operations Move and the minimum number of concurrent operations Move of each quay crane; S4, calculating and obtaining the number of Move requirements of each quay crane and the quay crane operation time window for each Move requirement; S5, according to the current state of each IGV, matching the IGV that meets the dispatching conditions with each Move that needs to be completed; S6, obtaining the IGV operation plan, and dispatching the matched IGV to each quay crane for loading and unloading operations. The present invention uniformly allocates all IGVs in the field to achieve the maximum balance between ship operation efficiency and resource utilization, thereby reducing the production cost of the terminal and improving the overall operation efficiency.

Description

Technical Field

[0001] The present invention relates to an intelligent operation method for a quay crane at a container terminal, and in particular to an overall scheduling method based on the operation efficiency of a quay crane at an automated container terminal. Background Art

[0002] In the currently operating automated or traditional terminals, the central control personnel basically rely on the creation of new trailer groups in the TOS system to bind the quay crane or ship to achieve this. The central control personnel evaluate the number of trailers required based on the workload of the ship or quay crane and add the trailer number to the trailer group. The trailer can only receive the operation instructions bound to the quay crane or ship. The manual determination of the number of trailer requirements by the central control personnel greatly increases the uncertainty. A small number of trailers dispatched will result in the ship being unable to leave on time, and a large number of trailers dispatched may cause a serious waste of resources, and it cannot be changed according to the actual operation situation. In addition, binding a specific trailer number greatly limits the flexible deployment of container trucks, increases transportation costs, and prevents trailers that are originally closer from being used nearby, affecting operating efficiency and resource utilization. Summary of the invention

[0003] The purpose of the present invention is to overcome the shortcomings of the prior art and provide an overall scheduling method based on the operating efficiency of an automated container terminal. This method uniformly allocates all IGVs in the terminal to achieve the maximum balance between ship operating efficiency and resource utilization, thereby reducing the production cost of the terminal and improving the overall operating efficiency.

[0004] The purpose of the present invention is achieved through the following technical solutions:

[0005] An overall scheduling method based on the operating efficiency of automated container terminal quay cranes comprises the following steps:

[0006] S1. Sending ship loading and unloading instructions to the dispatching system;

[0007] S2. Configure the target efficiency of each quay crane, the maximum number of IGVs for loading, the maximum number of IGVs for unloading, and the minimum number of IGVs; the minimum number of IGVs is applicable when loading or unloading;

[0008] S3. Configure the maximum and minimum concurrent Move numbers of each quay crane;

[0009] S4. According to the target efficiency configured for each quay crane in step S2 and the maximum number of concurrent operation Moves and the minimum number of concurrent operation Moves configured in step S3, the number of Move requirements of each quay crane and the quay crane operation time window for each Move requirement are obtained by calculation;

[0010] S5. According to the current status of each IGV, the IGV that meets the dispatching conditions is matched with each Move that needs to be completed;

[0011] S6. Generate an IGV operation plan and dispatch matched IGVs to each quay crane for ship loading and unloading operations.

[0012] In a preferred embodiment of the present invention, in step S2, the target efficiency of the quay crane refers to the number of hoisting times of the quay crane per unit time, and the dispatching system automatically and reasonably sets it according to the length of time the ship is in the port;

[0013] The target efficiency of the quay crane may be automatically changed as the operating conditions change, but is less than or equal to the limiting efficiency of the quay crane, where the limiting efficiency of the quay crane refers to the maximum operating capacity of the quay crane.

[0014] Preferably, the target efficiency of the quay crane is configured by the following formula:

[0015] EQCW / (ETC-CT)

[0016] Among them, EQCW is the estimated operation volume of the quay crane, ETC is the estimated completion time of the ship, and CT is the current time.

[0017] In a preferred embodiment of the present invention, in step S2, the maximum number of IGVs for loading and the maximum number of IGVs for unloading are configured by the following formula:

[0018] M=Y / (60 / X)

[0019] Wherein, M is the maximum number of IGVs for loading or unloading, Y is the target efficiency of the quay crane, and X is the average cycle time of the IGV. The average cycle time of the IGV refers to the time required for the IGV to obtain the loading and unloading task and complete the loading and unloading task;

[0020] The minimum number of IGVs is a fixed value and is configured based on actual conditions to ensure that each quay crane has a minimum number of IGVs to operate when IGV resources are insufficient.

[0021] In a preferred embodiment of the present invention, in step S4, the number of Moves to be completed is first calculated according to the efficiency cycle, and then the number of Moves required for the quay crane is calculated according to the number of Moves to be completed;

[0022] Among them, when the quay crane is unloading, the number of moves required by the quay crane is the sum of the number of moves that have been dispatched but the containers have not been loaded and the number of moves that have not been dispatched but need to be completed within the current decision cycle;

[0023] When the quay crane is performing loading operations, the number of Moves required by the quay crane is the sum of the number of Moves that have been dispatched but have not yet loaded with containers and the number of Moves that have not been dispatched but need to be completed within the current decision cycle, and the number of Moves that have already loaded with containers must be excluded.

[0024] Preferably, in step S4, the quay crane operation time window of each Move requirement includes a suggested start time and a suggested end time;

[0025] The earliest recommended start time is calculated based on the maximum number of concurrent job Moves; the latest recommended start time is calculated based on the minimum number of concurrent job Moves; recommended start time = (earliest recommended start time + latest recommended start time) / 2;

[0026] When the vehicle for the Move request has been dispatched and the container has been loaded, the end time of the Move is calculated using the maximum efficiency of the quay crane and used as the recommended end time;

[0027] When the vehicle has been dispatched for the Move demand but the container has not been loaded or the vehicle has not been dispatched, the target efficiency at the end time of the previous Move of the Move demand is calculated, and then it is determined whether the Move demand needs to catch up with the efficiency; if it does not need to catch up with the efficiency, the end time is calculated according to the original target efficiency, and this is used as the recommended end time; if it needs to catch up with the efficiency, the end time is calculated according to the limit efficiency of the quay crane, and this is used as the recommended end time.

[0028] A preferred solution of the present invention is that in step S5, the IGV that meets the dispatching conditions is matched with the Move that needs to be completed and the IGV using the KM algorithm; in a bipartite graph, the IGV is taken as the left vertex and the Move task that needs to be completed is taken as the right vertex, and the time cost for the IGV to travel to the starting point of the task is calculated to be the minimum; in the KM algorithm, the weight between the task and the IGV is calculated based on the static time matrix from the current position of the IGV to the position of the task.

[0029] Preferably, among the IGVs that meet the dispatching conditions, those that are not in the operating fleet, have low battery power, or have a mission are excluded.

[0030] In a preferred embodiment of the present invention, in step S5, the number of Moves of each quay crane that has not been dispatched is matched according to the size of the work box;

[0031] If the operating box size is 40 feet or double 20 feet, the number of IGVs is equal to the number of Moves; if the operating box size is single 20 feet, the number of IGVs is equal to half of the number of Moves; combined with the maximum number of IGVs for loading, the maximum number of IGVs for unloading, and the minimum number of IGVs, the actual number of IGVs required for each quay crane is generated.

[0032] Compared with the prior art, the present invention has the following beneficial effects:

[0033] The present invention uses the time the ship is in port as a benchmark and the ship's operating efficiency as a guide to uniformly deploy all IGVs in the terminal. By accurately calculating the number of IGVs required for each quay crane and the optimal dispatch time for each IGV, the most suitable IGV can be reasonably deployed for operation. This method aims to achieve the maximum balance between ship operating efficiency and resource utilization, thereby reducing the production cost of the terminal and improving the overall operating efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 This is a schematic diagram of the number of Moves that need to be completed in the current decision cycle of the present invention.

[0035] Figure 2 It is a diagram of the execution steps of the present invention. DETAILED DESCRIPTION

[0036] The present invention is further described below in conjunction with examples and drawings, but the embodiments of the present invention are not limited thereto.

[0037] See also Figure 1-Figure 2 This embodiment discloses an overall scheduling method based on the operating efficiency of automated container terminal quay cranes, including the following steps:

[0038] S1. Sending ship loading and unloading instructions to the dispatching system;

[0039] S2. Configure the target efficiency of each quay crane, the maximum number of IGVs for loading, the maximum number of IGVs for unloading, and the minimum number of IGVs; the minimum number of IGVs is applicable when loading or unloading;

[0040] S3. Configure the maximum and minimum concurrent Move numbers of each quay crane;

[0041] S4. According to the target efficiency configured for each quay crane in step S2 and the maximum number of concurrent operation Moves and the minimum number of concurrent operation Moves configured in step S3, the number of Move requirements of each quay crane and the quay crane operation time window for each Move requirement are obtained by calculation;

[0042] S5. According to the current status of each IGV, the IGV that meets the dispatching conditions is matched with each Move that needs to be completed;

[0043] S6. Generate an IGV operation plan and dispatch matched IGVs to each quay crane for ship loading and unloading operations.

[0044] Furthermore, in step S2, the target efficiency of the quay crane refers to the number of hoisting times of the quay crane in a unit time (efficiency cycle, which can be set to 60 minutes), and the dispatching system automatically sets it reasonably according to the length of time the ship is in the port. The target efficiency of the quay crane can be automatically changed with the change of operating conditions, but it is less than or equal to the limit efficiency of the quay crane, and the limit efficiency of the quay crane refers to the maximum operating capacity of the quay crane. Specifically, the target efficiency of the quay crane is configured by the following formula:

[0045] EQCW / (ETC-CT)

[0046] Among them, EQCW is the estimated operation volume of the quay crane, ETC is the estimated completion time of the ship, and CT is the current time.

[0047] Further, in step S2, the maximum number of IGVs for loading and the maximum number of IGVs for unloading are configured by the following formula:

[0048] M=Y / (60 / X)

[0049] Among them, M is the maximum number of IGVs for loading or unloading, Y is the target efficiency of the quay crane, X is the average cycle time of the IGV, and the average cycle time of the IGV refers to the time required for the IGV to obtain the loading and unloading task and complete the loading and unloading task; the minimum number of IGVs is a fixed value, which is configured according to the actual situation to ensure that each quay crane has a minimum number of IGVs to operate when IGV resources are insufficient.

[0050] For cost considerations, it is impossible for the terminal to configure enough IGVs for all quay cranes, so the maximum number of IGVs for loading, the maximum number of IGVs for unloading, and the minimum number of IGVs are set for control. When the demand quantity is greater than the configured maximum number of IGVs for loading, the actual number of vehicles dispatched shall be based on the maximum number of IGVs for loading. The maximum number of IGVs for unloading is the number of all unloading IGVs belonging to the quay crane, and the number of all unloading IGVs belonging to the quay crane includes empty IGVs and IGVs that have completed receiving containers. The IGV that has completed receiving containers can be understood as the IGV that has been overloaded with boxes unloaded by the quay crane and the boxes have not been hoisted into the yard by the rail; and when the boxes on the IGV are hoisted into the yard by the rail, the IGV becomes empty and no longer obtains the operation task of the quay crane. At this time, the IGV is not included in the number of trailers of the quay crane. Similarly, when the demand quantity for unloading is greater than the configured maximum number of IGVs for unloading, the actual number of vehicles dispatched shall be based on the maximum number of IGVs for unloading. The minimum number of IGVs is valid for both loading and unloading ships, which means that when the number of IGVs required by the quay crane is less than the minimum number of IGVs, the minimum number of IGVs will be dispatched.

[0051] In step S3, the maximum number of concurrent operations Move can be set to 3, and the minimum number of concurrent operations Move can be set to 1. Specifically, there are generally 6 lanes at the bottom of the quay crane, of which the first, third and fifth are working lanes (hereinafter referred to as QCTP), and the second, fourth and sixth are traffic lanes. In other words, there are generally three QCTPs in the quay crane. When there are IGVs waiting for operations at the same time in the three QCTPs, the number of IGVs dispatched can be at most the maximum number that can be parked at the bottom of the bridge. If this number is exceeded, resources will be wasted. Therefore, this data is called the maximum number of concurrent operations Move. When there is only one QCTP with IGVs waiting for operations, if the number of IGVs dispatched is lower than the minimum number, the quay crane will have no IGV operations, resulting in a decrease in efficiency. Therefore, the minimum number of concurrent operations Move is set to 1. The maximum number of concurrent operations Move and the minimum number of concurrent operations Move can be manually configured according to actual conditions. In principle, they are configured according to the number of available QCTPs.

[0052] Furthermore, in step S4, within a decision cycle (which can be set to 30 minutes), the number of Moves that need to be completed is first calculated based on the efficiency cycle, and then the number of Move requirements of the quay crane (i.e. the number of Moves to be operated) is calculated based on the number of Moves that need to be completed.

[0053] Among them, when the quay crane is performing unloading operations, the number of Moves required by the quay crane is the sum of the number of Moves for which the vehicle has been dispatched but the containers have not been loaded and the number of Moves for which the vehicle has not been dispatched but needs to be completed within the current decision cycle; when the quay crane is performing loading operations, the number of Moves required by the quay crane is the sum of the number of Moves for which the vehicle has been dispatched but the containers have not been loaded and the number of Moves for which the vehicle has not been dispatched but needs to be completed within the current decision cycle, and the number of Moves for which the containers have been loaded must be excluded.

[0054] See also Figure 1 , which is a schematic diagram for calculating the number of Moves that need to be completed in the current decision cycle. The operation start time is taken from the operation start time of the operating quay crane, and the current efficiency cycle is taken from the efficiency cycle range at the current time;

[0055] The operation start time of the current efficiency cycle = the integer quotient of [(current time – operation start time) / efficiency cycle] × efficiency cycle + operation start time;

[0056] The number of moves that the quay crane can complete at its maximum efficiency within a decision cycle = the quay crane's maximum efficiency × the decision cycle;

[0057] The number of Moves that need to be completed in the current decision cycle = the number of Moves that should be completed in the time period from "the start time of the operation in the current efficiency cycle" to "the end time of the decision cycle" - the number of Moves that have been completed.

[0058] If the calculated "number of Moves that need to be completed in the current decision cycle" is greater than the "number of Moves that can be completed by the quay crane at its maximum efficiency within one decision cycle", its value will be corrected to be equal to the latter.

[0059] Further, in step S4, the quay crane operation time window of each Move demand includes a recommended start time and a recommended end time. The earliest recommended start time is calculated according to the maximum number of concurrent operations Move; the latest recommended start time is calculated according to the minimum number of concurrent operations Move; recommended start time = (earliest recommended start time + latest recommended start time) / 2; when the vehicle for the Move demand has been dispatched and the container has been loaded, the end time of the Move is calculated using the maximum efficiency of the quay crane, and this is used as the recommended end time; when the vehicle for the Move demand has been dispatched but the container has not been loaded or the vehicle has not been dispatched, the target efficiency at the end time of the previous Move of the Move demand is calculated, and then it is determined whether the Move demand needs to catch up with the efficiency; if the efficiency does not need to be caught up, the end time is calculated according to the original target efficiency (i.e., the target efficiency configured in step S2), and this is used as the recommended end time; if the efficiency needs to be caught up, the end time is calculated according to the maximum efficiency of the quay crane, and this is used as the recommended end time.

[0060] For example, assuming that n = "the number of Moves that have been loaded onto the container", m = "the maximum number of concurrent Moves", and k = "the minimum number of concurrent Moves", the "suggested earliest start time" and "suggested latest start time" of the rth Move requirement of the quay crane are calculated as follows;

[0061] First, all the Moves with containers loaded are sorted in ascending order according to the estimated time of arrival (ETA) at the lane under the quay crane, that is, the one that arrives first under the quay crane is ranked first, and the one that arrives last is ranked nth.

[0062] Next, starting from the first Move demand, the planned start time of each Move demand is calculated in sequence. The Move corresponding to the first Move demand is placed under the n+1th arriving quay crane, and the Move corresponding to the rth Move demand is placed under the n+rth arriving quay crane. The calculation formula for the planned start time of the rth Move demand (r>=1) is:

[0063] If n+r<=m+1, the earliest recommended start time is the current time;

[0064] If n+r>m+1, the recommended earliest start time is the end time of the n-m+r-1th Move of the quay crane operation;

[0065] If n+r<=k+1, the latest recommended starting time is the current time;

[0066] If n+r>k+1, the recommended latest start time is the end time of the n-k+r-1th Move of the quay crane operation;

[0067] Recommended start time of the quay crane = (recommended earliest start time + recommended latest start time) / 2.

[0068] There are two methods to calculate the recommended end time of the quay crane plan. The details are as follows:

[0069] (1) Move where the vehicle has been dispatched and the box has been loaded

[0070] The time when the quay crane completes the move is always calculated using the limit efficiency. Because the move is actually being executed and is not a scheduling decision object, the quay crane will actually complete the move at the limit efficiency.

[0071] (2) Moves where the vehicle has been dispatched but the box has not been loaded, and Moves where the vehicle has not been dispatched but the decision has been made

[0072] For each Move, the "real-time target efficiency" at the end time of the previous Move must be recalculated to determine whether the Move needs to catch up with the efficiency. If the Move does not need to catch up with the efficiency, the original target efficiency is used for calculation. If the Move needs to catch up with the efficiency, the end time is calculated according to the limit efficiency. Because the Move is still a pending decision object for scheduling, the scheduler needs to control the end time of the Move and use it to calculate the earliest and latest recommended times for subsequent Moves. In addition, for the second Move of a double-box two-crane operation, the operation time of the quay crane is always calculated according to the limit efficiency.

[0073] Furthermore, in step S5, IGVs that are not in the working fleet, have low battery or have tasks are excluded as IGVs that meet the dispatch conditions. The IGVs that meet the dispatch conditions are matched with the Move that needs to be completed using the KM algorithm; in a bipartite graph, with the IGV as the left vertex and the Move task that needs to be completed as the right vertex, the time cost of the IGV traveling to the starting point of the task is calculated to be the minimum; in the KM algorithm, the weight between the task and the IGV is calculated based on the static time matrix from the current position of the IGV to the position of the task.

[0074] In addition, in step S5, the number of Moves that have not been dispatched by each quay crane is matched according to the size of the work box. If the work box size is 40 feet or double 20 feet, the number of IGVs is equal to the number of Moves; if the work box size is single 20 feet, the number of IGVs is equal to half of the number of Moves; combined with the maximum number of IGVs for loading, the maximum number of IGVs for unloading, and the minimum number of IGVs, the actual number of IGVs required for each quay crane is generated.

[0075] The scheduling method of this embodiment is guided by the ship operation efficiency, calculates the number of Move requirements of each quay crane, calculates the number of Moves that need to be completed in the current decision cycle within a decision cycle, and calculates the number of Move requirements of the quay crane based on the number of Moves that need to be completed. The number of Move requirements of the quay crane = the number of Moves that have been dispatched but not loaded + the number of Moves that have not been dispatched but need to be completed in the current decision cycle; when the quay crane is loading the ship, the Moves that have been loaded must be excluded, and the quay crane operation time window for each Move requirement is calculated based on the maximum number of concurrent operations and the minimum number of concurrent operations. The maximum number of concurrent operations is used to calculate the earliest recommended start time, and the minimum number of concurrent operations is used to calculate the latest recommended start time. Using this method can achieve the maximum balance between ship operation efficiency and resource utilization, thereby reducing the production cost of the terminal and improving overall operational efficiency.

[0076] The above is a preferred embodiment of the present invention, but the embodiment of the present invention is not limited to the above content. Any other changes, modifications, substitutions, combinations, and simplifications made without departing from the spirit and principles of the present invention should be equivalent replacement methods and are included in the protection scope of the present invention.

Claims

1. An overall scheduling method based on the operating efficiency of automated container terminal quay cranes, characterized in that: The following steps are involved: S1. Sending ship loading and unloading instructions to the dispatching system; S2. Configure the target efficiency of each quay crane, the maximum number of IGVs for loading, the maximum number of IGVs for unloading, and the minimum number of IGVs; the minimum number of IGVs is applicable when loading or unloading; S3. Configure the maximum and minimum concurrent Move numbers of each quay crane; S4. According to the target efficiency configured for each quay crane in step S2 and the maximum number of concurrent operation Moves and the minimum number of concurrent operation Moves configured in step S3, the number of Move requirements of each quay crane and the quay crane operation time window for each Move requirement are obtained by calculation; S5. According to the current status of each IGV, the IGV that meets the dispatching conditions is matched with each Move that needs to be completed; S6. Generate an IGV operation plan and dispatch the matched IGV to each quay crane for loading and unloading operations; In step S2, the target efficiency of the quay crane refers to the number of hoisting times of the quay crane per unit time, and the dispatching system automatically sets it reasonably according to the length of time the ship is in the port; The target efficiency of the quay crane may be automatically changed as the operating conditions change, but is less than or equal to the limit efficiency of the quay crane, where the limit efficiency of the quay crane refers to the maximum operating capacity of the quay crane; In step S4, the number of Moves that need to be completed is first calculated according to the efficiency cycle, and then the number of Moves required for the quay crane is calculated according to the number of Moves that need to be completed; Among them, when the quay crane is unloading, the number of moves required by the quay crane is the sum of the number of moves that have been dispatched but the containers have not been loaded and the number of moves that have not been dispatched but need to be completed within the current decision cycle; When the quay crane is loading, the number of Moves required by the quay crane is the sum of the number of Moves that have been dispatched but not loaded with containers and the number of Moves that have not been dispatched but need to be completed within the current decision cycle, and the number of Moves that have been loaded with containers must be excluded; The quay crane operation time window for each Move requirement includes a recommended start time and a recommended end time; The earliest recommended start time is calculated based on the maximum number of concurrent job Moves; the latest recommended start time is calculated based on the minimum number of concurrent job Moves; recommended start time = (earliest recommended start time + latest recommended start time) / 2; When the vehicle for the Move request has been dispatched and the container has been loaded, the end time of the Move is calculated using the maximum efficiency of the quay crane and used as the recommended end time; When the vehicle has been dispatched for the Move demand but the container has not been loaded or the vehicle has not been dispatched, the target efficiency at the end time of the previous Move of the Move demand is calculated, and then it is determined whether the Move demand needs to catch up with the efficiency; if it does not need to catch up with the efficiency, the end time is calculated according to the original target efficiency, and this is used as the recommended end time; if it needs to catch up with the efficiency, the end time is calculated according to the limit efficiency of the quay crane, and this is used as the recommended end time.

2. The overall scheduling method based on the operation efficiency of automated container terminal quay cranes according to claim 1 is characterized in that: The target efficiency of the quay crane is configured by the following formula: EQCW / (ETC-CT) Among them, EQCW is the estimated operation volume of the quay crane, ETC is the estimated completion time of the ship, and CT is the current time.

3. The overall scheduling method based on the operation efficiency of automated container terminal quay cranes according to claim 1 is characterized in that: In step S2, the maximum number of IGVs for loading and unloading is configured by the following formula: M=Y / (60 / X) Wherein, M is the maximum number of IGVs for loading or unloading, Y is the target efficiency of the quay crane, and X is the average cycle time of the IGV. The average cycle time of the IGV refers to the time required for the IGV to obtain the loading and unloading task and complete the loading and unloading task; The minimum number of IGVs is a fixed value and is configured based on actual conditions to ensure that each quay crane has a minimum number of IGVs to operate when IGV resources are insufficient.

4. The overall scheduling method based on the operation efficiency of automated container terminal quay cranes according to claim 1 is characterized in that: In step S5, the KM algorithm is used to match the IGVs that meet the dispatching conditions with the Moves that need to be completed. In a bipartite graph, the IGV is taken as the left vertex and the Move task that needs to be completed is taken as the right vertex. The time cost of the IGV traveling to the starting point of the task is calculated to be the minimum. In the KM algorithm, the weight between the task and the IGV is calculated based on the static time matrix from the current position of the IGV to the location of the task.

5. The overall scheduling method based on the operation efficiency of automated container terminal quay cranes according to claim 4 is characterized in that: Among the IGVs that meet the dispatch conditions, those that are not in the operating fleet, have low battery power, or have missions are excluded.

6. The overall scheduling method based on the operation efficiency of automated container terminal quay cranes according to claim 1 is characterized in that: In step S5, the number of Moves that have not been dispatched by each quay crane is matched according to the size of the work box; If the operating box size is 40 feet or double 20 feet, the number of IGVs is equal to the number of Moves; if the operating box size is single 20 feet, the number of IGVs is equal to half of the number of Moves; combined with the maximum number of IGVs for loading, the maximum number of IGVs for unloading, and the minimum number of IGVs, the actual number of IGVs required for each quay crane is generated.

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