Cooperative scheduling method for gantry crane and storage yard of bulk cargo wharf

Abstract

The invention discloses a method for co-scheduling a portal crane and a storage yard of a piece general cargo wharf, which comprises the following steps of: constructing an optimized objective function for co-scheduling the portal crane and the storage yard of the piece general cargo wharf on the basis of constraint conditions for co-scheduling the portal crane and the storage yard of the piece general cargo wharf, and solving the optimized objective function by adopting an improved NSGA-II (Non-dominated Sorting Genetic Algorithm-II) algorithm, so as to realize the cooperative scheduling of the portal crane and the storage yard of the piece general cargo wharf. And obtaining the positions of the portal crane, the trailer and the storage yard distributed to the cargo on the cargo ship so as to obtain an optimal portal crane and storage yard collaborative scheduling scheme. According to the method, decision reference can be provided for port dispatchers to design a dispatching scheme, reference is provided for dispatchers of a general cargo wharf to carry out dispatching plan arrangement, and the time for the dispatchers to design the scheme is greatly saved. The workload of wharf dispatchers can be reduced, the operation cost of the wharf is saved, and the loading and unloading efficiency of the wharf can be improved. The research of the bulk cargo wharf in the field of cooperative scheduling is enriched, and the bulk cargo wharf can maintain advantages in the market with intense competition.

Description

Technical Field

[0001] The present invention relates to the technical field of intelligent port dispatching, and in particular to a method for coordinated dispatching of gantry cranes and storage yards at general cargo terminals. Background Art

[0002] my country's breakbulk terminals are required to handle an increasing variety of cargo and workload. Faced with increasingly complex and demanding loading and unloading operations, breakbulk terminals are facing numerous new challenges and challenges, impacting the efficiency and effectiveness of terminal operations. While breakbulk transport is a relatively inefficient mode of loading, unloading, and transportation compared to container shipping, which features relatively mature standardization and loading and unloading automation, it remains irreplaceable to a certain extent due to the low containerization rates of many traditional general and bulk cargoes. This ensures that breakbulk terminals continue to play a vital role in my country's port system. The efficiency of breakbulk terminals' loading and unloading operations is influenced by a variety of factors, including vessel type, cargo type, machinery and equipment, tools, and cargo yards. The process is complex and diverse, and the current level of automation is low, resulting in generally low operational efficiency. Summary of the Invention

[0003] The present invention discloses a method for coordinated dispatching of a gantry crane and a storage yard at a general cargo terminal, so as to overcome the above technical problems.

[0004] In order to achieve the above object, the technical solution of the present invention is:

[0005] A method for coordinated scheduling of a gantry crane and a storage yard at a general cargo terminal comprises the following steps:

[0006] S1: Determine the constraints for coordinated scheduling of the gantry crane and the storage yard at the general cargo terminal;

[0007] S2: Construct an optimization objective function for the coordinated scheduling of the gantry crane and the storage yard at the breakbulk terminal. The optimization objective function aims to minimize the total cargo turnover time, the total cost consumed by the loading and unloading operations, and the total number of tool changes during the gantry crane loading and unloading operations.

[0008] S3: Based on the optimization objective function, the improved NSGA-II algorithm is used to obtain the positions of the gantry cranes, trailers, and storage yards assigned to the cargo on the cargo ship, so as to obtain the optimal coordinated scheduling solution for the gantry cranes and storage yards.

[0009] Furthermore, the optimization objective function for the coordinated scheduling of the gantry crane and the storage yard at the general cargo terminal is constructed as follows:

[0010] Minimize Cost=Z1+Z2+Z3

[0011] in,

[0012]

[0013] Where Cost represents the overall optimization goal; Z1 represents the total turnover time of all cargoes from the start of loading and unloading on the ship to the storage yard; Z2 represents the total cost incurred during cargo loading and unloading, including the gantry crane operation time cost, trailer transportation time cost, and trailer transportation distance cost; Z3 represents the total number of tool changes of all gantry cranes during loading and unloading operations; N j It indicates the total number of tool changes of a single gantry crane during loading and unloading operations; i indicates the cargo type number; n indicates the total number of cargo types; j indicates the gantry crane number; m indicates the total number of gantry cranes; l indicates the number of docked cargo ships; o indicates the total number of docked cargo ships; k indicates the trailer number; p indicates the total number of trailers; T ijl T represents the time required for the jth gantry crane to load and unload the i-th cargo on the l-th cargo ship; j Indicates the total time consumed by the door operator to replace the tools; T ikl S represents the time required for the k-th trailer to transport the i-th cargo on the l-th cargo ship to the designated storage site; j represents the cost per unit time of the jth gantry crane; x ijl is the decision variable used to indicate whether the jth gantry crane participates in loading and unloading the i-th cargo on the l-th cargo ship; L ilr represents the one-way path from the i-th cargo on the l-th cargo ship to the r-th yard; z ikl S represents the decision variable for whether the i-th cargo on the l-th cargo ship is transported by the k-th trailer; k It represents the cost per unit distance of trailer transportation; S represents the unit time cost of trailer transportation.

[0014] Furthermore, the constraints include: gantry crane constraints, trailer constraints, cargo constraints, and yard constraints.

[0015] Furthermore, the door machine constraints are expressed as follows:

[0016]

[0017] Where: T ijl represents the time required for the jth gantry crane to load and unload the i-th cargo on the l-th cargo ship; x ijl is the decision variable used to indicate whether the j-th gantry crane participates in loading and unloading the i-th cargo on the l-th cargo ship; ceil(·) is the upward rounding function; It represents the number of cargoes of type i cargo on ship l that are assigned to the jth gantry crane for operation; Indicates the maximum number of pieces of cargo that can be handled by the gantry crane in a single operation; Indicates the single operation time of the gantry crane for the i-th type of cargo;

[0018]

[0019] T j =N j *t j

[0020] Where: N j Indicates the total number of tool changes for a single gantry crane during loading and unloading operations; t j Indicates the average time required to replace the tools of the gantry crane;

[0021]

[0022] Where: Q i and Respectively represent the weight of a single piece of cargo of category i, Indicates the maximum lifting weight limit when the gantry crane is working;

[0023]

[0024] Furthermore, the trailer constraint is expressed as follows:

[0025]

[0026] Where: T ikl The time required for the k-th trailer to transport the i-th cargo on the l-th cargo ship to the designated storage area; ilr is the decision variable indicating whether the i-th cargo on the l-th cargo ship is allocated to the r-th yard; ikl represents the decision variable for whether the i-th cargo on the l-th cargo ship is transported by the k-th trailer; ceil(·) is the upward rounding function; L lr V represents the distance from the berth where the l-th cargo ship is located to the r-th yard, k represents the fully loaded speed of the k-th trailer; represents the unloaded speed of the k-th trailer, represents the total number of pieces of the i-th type of cargo on the l-th cargo ship, It represents the maximum number of fully loaded pieces of the i-th type of cargo that the k-th trailer can transport in a single trip;

[0027]

[0028] Where: is the maximum transport distance of the k-th trailer;

[0029]

[0030] Furthermore, the yard constraint is expressed as follows:

[0031] v ir *yilr =y ilr ,y ilr =1

[0032] Where: v ir The parameter indicating whether the i-th type of goods can be stacked in the r-th yard, when v ir =1, it means that the i-th type of goods can be stacked in the r-th yard; ilr The parameter indicating whether the i-th cargo on the l-th cargo ship is allocated to the r-th yard. ilr =1, it means that the i-th cargo on the l-th cargo ship is allocated to the r-th yard.

[0033]

[0034] Where: It represents the remaining capacity of the r-th yard for storing the i-th type of goods.

[0035] Furthermore, the cargo constraints are expressed as follows:

[0036]

[0037] Where: represents the total number of pieces of cargo of type i on cargo ship l; It represents the number of pieces of cargo of type i on cargo ship l that are assigned to gantry crane j.

[0038]

[0039] P il >P i′l

[0040]

[0041] Where: P il is the priority of the i-th cargo on the l-th cargo ship, Indicates the time when the i-th type of cargo on the l-th cargo ship begins to be loaded and unloaded; i′ and i both represent the cargo type number, i′≠i;

[0042]

[0043] Where: It represents the latest delivery time of the i-th cargo on the l-th cargo ship.

[0044] Furthermore, the improved NSGA-II algorithm performs the following steps:

[0045] S31: Get the initialization population;

[0046] S32: Based on the fitness function, obtain the fitness value of the initialized population;

[0047] S33: performing non-dominated sorting on the initialized population according to the fitness value of the initialized population, obtaining a non-dominated layer sequence, and obtaining the crowding degree of individuals in the non-dominated layer sequence;

[0048] S34: Based on the crowding degree of individuals in the non-dominated layer sequence, the individuals in the initialized population are sequentially subjected to selection operation, crossover operation, and mutation operation to obtain a child population; and a new population is obtained based on the parent population and the child population;

[0049] S35: performing a non-dominated sort on the new population to obtain a non-dominated layer sequence of the new population, and randomly selecting u non-dominated layer sequences of the new population so that the sum of the number of individuals in the 1st to u-1st non-dominated layer sequences of the new population is less than the number of individuals in the initialization population, and the sum of the number of individuals in the 1st to uth non-dominated layer sequences of the new population is not less than the number of individuals in the initialization population; wherein u≤U, U is the total number of non-dominated layers of the new population; and u is the index of the non-dominated layer of the new population;

[0050] S36: If the sum of the numbers of individuals in the u non-dominated layer sequences of the new population is greater than the number of individuals in the initialization population, then the crowding degrees of the individuals in the u non-dominated layer sequences of the new population are obtained, and individuals in the u non-dominated layer sequences of the new population are deleted in ascending order of their crowding degrees until the sum of the numbers of individuals in the u non-dominated layer sequences of the new population after deletion is equal to the number of individuals in the initialization population;

[0051] S37: For the individuals in the non-dominated layer sequence of the new population u after deletion, based on the dynamic crossover probability and the dynamic mutation probability, a dynamic crossover operation and a dynamic mutation operation are sequentially performed to obtain the evolved new population;

[0052] S38: Based on the evolved new population, repeat S32 to S37 until the iteration end condition is met.

[0053] Furthermore, the dynamic crossover probability is obtained as follows:

[0054]

[0055] Where: P c is the current crossover probability; and are the maximum crossover probabilities respectively. ;

[0056] Furthermore, the dynamic mutation probability is obtained as follows:

[0057]

[0058] Where: P m is the current mutation probability; and are the minimum and maximum values ​​of the mutation probability, respectively.

[0059] Beneficial Effects: The present invention provides a method for coordinated scheduling of gantry cranes and storage yards at breakbulk cargo terminals. Based on the constraints for coordinated scheduling of gantry cranes and storage yards at breakbulk cargo terminals, an optimization objective function for coordinated scheduling of gantry cranes and storage yards at breakbulk cargo terminals is constructed. The optimized objective function is then solved using an improved NSGA-II algorithm to determine the locations of gantry cranes, trailers, and storage yards assigned to cargo on cargo ships, thereby obtaining the optimal coordinated scheduling solution for gantry cranes and storage yards. This method overcomes the problems of over-reliance on manual experience in scheduling at breakbulk cargo terminals, which impacts the operating time of breakbulk cargo ships in port, and reduces terminal operational efficiency and economic benefits due to limited resources such as gantry cranes, trailers, and storage yard space at breakbulk cargo terminals and insufficient consideration of the rational scheduling of gantry cranes, trailers, and other equipment. The method completes the loading and unloading process for breakbulk cargo ships, provides a decision-making reference for port dispatchers in designing scheduling solutions, and provides a reference for dispatchers at breakbulk cargo terminals in making scheduling plans, significantly reducing the time required for dispatchers to design solutions. This not only reduces the workload of terminal dispatchers and saves terminal operating costs, but also improves loading and unloading efficiency. This systematic management approach enriches research in the field of collaborative scheduling at breakbulk terminals and helps them maintain their advantage in the highly competitive market. BRIEF DESCRIPTION OF THE DRAWINGS

[0060] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following is a brief introduction to the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative labor.

[0061] Figure 1 This is a flow chart of the method for coordinated scheduling of gantry cranes and storage yards at breakbulk cargo terminals according to the present invention;

[0062] Figure 2 Schematic diagram of a general cargo terminal yard in an embodiment of the present invention;

[0063] Figure 3 This is a flowchart of the unloading operation of the general cargo terminal in an embodiment of the present invention;

[0064] Figure 4 Flowchart of the improved NSGA-II algorithm in an embodiment of the present invention. DETAILED DESCRIPTION

[0065] To make the objectives, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0066] This embodiment introduces a method for coordinated scheduling of gantry cranes and storage yards at general cargo terminals, including the following steps: Figure 1 As shown:

[0067] S1: Based on the ship loading and unloading process at the general cargo terminal, determine the constraints for the coordinated scheduling of the gantry crane and the storage yard at the general cargo terminal; the constraints include gantry crane constraints, trailer constraints, cargo constraints, storage yard constraints, etc.

[0068] S2: Construct an optimization objective function for the coordinated scheduling of the gantry crane and the storage yard at the breakbulk terminal. The optimization objective function aims to minimize the total cargo turnover time, the total cost consumed by the loading and unloading operations, and the total number of tool changes during the gantry crane loading and unloading operations.

[0069] S3: Using the improved NSGA-II algorithm, according to the optimization objective function, the positions of the gantry crane, trailer, and storage yard assigned to the i-th cargo on the l-th cargo ship are obtained to obtain the optimal coordinated scheduling solution for the gantry crane and storage yard.

[0070] Specifically, in the actual operation of the general cargo terminal, the unloading operation time of the berthed ship is not only related to the number of allocated gantry cranes, but also affected by the efficiency of trailer transportation. Figure 2 This is a schematic diagram of the general cargo terminal yard.

[0071] like Figure 3 As shown, before unloading operations begin, the gantry cranes must be scheduled. Using the gantry cranes' operating sequence as input, the cargo unloading order is determined. Based on the unloading order, the cargo yard's capacity, and the distance to each yard, the cargo is assigned specific stacking locations. Once the gantry cranes begin operating, trailers deliver the cargo to the designated stacking locations. The stacking location's capacity status must be updated promptly after delivery. Once all cargo in a ship's holds has been unloaded by the gantry cranes and transported to the designated stacking locations by trailers, the gantry crane loading and unloading times and the trailer's transport times are recorded, and the gantry crane and trailer statuses are updated.

[0072] Preferably, the optimization objective function is constructed as follows:

[0073] Minimize Cost=Z1+Z2+Z3

[0074] in,

[0075]

[0076]

[0077] Where Cost represents the overall optimization goal; Z1 represents the total turnover time of all cargoes from the start of loading and unloading on the ship to the storage yard; Z2 represents the total cost incurred during cargo loading and unloading, including the gantry crane operation time cost, trailer transportation time cost, and trailer transportation distance cost; Z3 represents the total number of tool changes of all gantry cranes during loading and unloading operations; N j It indicates the total number of tool changes of a single gantry crane during loading and unloading operations; i indicates the cargo type number; n indicates the total number of cargo types; j indicates the gantry crane number; m indicates the total number of gantry cranes; l indicates the number of docked cargo ships; o indicates the total number of docked cargo ships; k indicates the trailer number; p indicates the total number of trailers; T ijl T represents the time required for the jth gantry crane to load and unload the i-th cargo on the l-th cargo ship; j Indicates the total time consumed by the door operator to replace the tools; T ikl S represents the time required for the k-th trailer to transport the i-th cargo on the l-th cargo ship to the designated storage site; j represents the cost per unit time of the jth gantry crane; x ijl is the decision variable used to indicate whether the jth gantry crane participates in loading and unloading the i-th cargo on the l-th cargo ship. When the jth gantry crane participates in loading and unloading the i-th cargo on the l-th cargo ship, x ijl =1, otherwise x ijl =0;L ilr represents the one-way path from the i-th cargo on the l-th cargo ship to the r-th yard; z ikl represents the decision variable for whether the i-th type of cargo on the k-th cargo ship is transported by the k-th trailer, where z is the decision variable for whether the i-th type of cargo on the l-th cargo ship is transported by the l-th trailer. ikl =1, otherwise z ikl =0;S k It represents the cost per unit distance of trailer transportation; S represents the unit time cost of trailer transportation.

[0078] Preferably, the door machine constraint is expressed as follows:

[0079] 1) The time required for the jth gantry crane to load and unload the i-th cargo on the l-th cargo ship is expressed as:

[0080]

[0081] Where: Tijl represents the time required for the jth gantry crane to load and unload the i-th cargo on the l-th cargo ship; x ijl is the decision variable used to indicate whether the j-th gantry crane participates in loading and unloading the i-th cargo on the l-th cargo ship; ceil(·) is the upward rounding function; It represents the number of cargoes of type i cargo on ship l that are assigned to the jth gantry crane for operation; Indicates the maximum number of pieces of cargo that can be handled by the gantry crane in a single operation; Indicates the single operation time of the gantry crane for the i-th type of cargo;

[0082] 2) Ensure that the i-th type of cargo on the l-th cargo ship cannot be assigned to more than two gantry cranes at most. This is to prevent more than two gantry cranes from operating at the same hatch on the cargo ship at the same time, which would cause interference between the gantry cranes and reduce loading and unloading efficiency. The constraints are set as follows:

[0083]

[0084] 3) The total number of tool changes during loading and unloading operations of the gantry crane is expressed as:

[0085]

[0086] Specifically, in actual operations at a breakbulk cargo terminal, if the cargo types of the preceding and subsequent operations of the gantry crane are different, the loading and unloading tools need to be replaced once.

[0087] The total time consumed by the door operator to replace the tools is as follows:

[0088] T j =N j *t j

[0089] Where: N j Indicates the total number of tool changes for a single gantry crane during loading and unloading operations; t j Indicates the average time required to replace the tools of the gantry crane;

[0090] 4) To ensure balanced operation of gantry cranes and avoid the situation where most tasks are concentrated on one gantry crane and individual gantry cranes have too much idle time, the constraints are set as follows:

[0091]

[0092] 5) During the actual loading and unloading operation, the gantry crane is subject to workload restrictions. Therefore, it is necessary to ensure the rationality of the maximum single operation weight of the gantry crane. The constraint is set and expressed as:

[0093]

[0094] Where: Indicates the maximum lifting weight of the gantry crane, Q i Indicates the weight of a single piece of cargo i;

[0095] 6) At the same time, the number of gantry cranes operating for a ship cannot exceed the total number of gantry cranes that can be dispatched at the terminal. The constraints are set as follows:

[0096]

[0097] Preferably, the trailer constraint is expressed as follows:

[0098] 7) The time for trailer transportation is expressed as:

[0099]

[0100] Where: T ikl The time required for the k-th trailer to transport the i-th cargo on the l-th cargo ship to the designated storage area; y ilr is the decision variable indicating whether the i-th cargo on the l-th cargo ship is allocated to the r-th yard. If it is allocated, then y ilr =1, otherwise y ilr =0;z ikl represents the decision variable for whether the i-th cargo on the l-th cargo ship is transported by the k-th trailer; ceil(·) is the upward rounding function; L lr V represents the distance from the berth where the l-th cargo ship is located to the r-th yard, k represents the fully loaded speed of the k-th trailer; represents the unloaded speed of the k-th trailer, represents the total number of pieces of the i-th type of cargo on the l-th cargo ship, It represents the maximum number of fully loaded pieces of the i-th type of cargo that the k-th trailer can transport in a single trip;

[0101] 8) Due to the limited range of the trailer, it is necessary to set a transport distance limit expressed as:

[0102]

[0103] Where: is the maximum transport distance of the k-th trailer, which is determined by the initial fuel carried.

[0104] 9) The number of trailers serving a cargo ship at the same time cannot exceed the total number of trailers that can be dispatched by the terminal. The constraint is expressed as:

[0105]

[0106] Preferably, the yard constraint is expressed as follows:

[0107] 10) To ensure that goods can be allocated to matching yards, set the following constraints:

[0108] v ir *y ilr =y ilr ,y ilr =1

[0109] Where: v ir The parameter indicating whether the i-th type of goods can be stacked in the r-th yard, when v ir =1, it means that the i-th type of goods can be stacked in the r-th yard; ilr The parameter indicating whether the i-th cargo on the l-th cargo ship is allocated to the r-th yard. ilr =1 means that the i-th cargo on the l-th cargo ship is allocated to the r-th yard. The necessary condition for the above formula to be valid is that v ir =1, thus ensuring the rationality of cargo distribution to the yard.

[0110] 11) When allocating goods, it is necessary not only to ensure that the yard is matched accordingly, but also to ensure that the remaining capacity of the yard is not exceeded.

[0111]

[0112] Where: It represents the remaining capacity of the r-th yard for stacking the i-th type of goods, in pieces.

[0113] Preferably, the cargo constraints are expressed as follows:

[0114] 12) To ensure the completeness of the number of cargo pieces assigned to each gantry crane on each ship, set the following constraints:

[0115]

[0116] Where: represents the total number of pieces of cargo of type i on cargo ship l; It represents the number of pieces of cargo of type i on cargo ship l that are assigned to gantry crane j.

[0117] 13) To ensure the continuity of operations, cargo assigned to the gantry crane for loading and unloading must also be assigned to a trailer for transportation. This can avoid the gantry crane waiting for the trailer on the shore, reducing the idle waiting time of the gantry crane and improving the efficiency of the unloading operation. The constraints are set as follows:

[0118]

[0119] When the above two formulas are true at the same time, it can ensure that the goods assigned to the gantry crane for loading and unloading are also assigned to the trailer for transportation.

[0120] 14) Ensure that a type of cargo on a cargo ship can only be allocated to one yard. Set the constraint as follows:

[0121]

[0122] 15) For the terminal, considering the actual situation of the shipper, there must be some cargo that needs to be loaded and unloaded from the ship urgently. Therefore, it is necessary to consider the priority of the cargo and set constraints, which can be expressed as:

[0123] P il >P i′l

[0124]

[0125] Where: P il is the priority of the i-th cargo on the l-th cargo ship, Indicates the time when the i-th cargo on the l-th cargo ship begins to be loaded and unloaded. For high-priority cargo, gantry crane loading and unloading can be arranged first; i′ and i both represent the cargo type number, i′≠i;

[0126] 16) Considering the actual operation of the terminal, the departure time of the ship is subject to constraints, so some cargo has a delivery time limit. Therefore, it is necessary to constrain the total transportation time of these ships and cargoes. The total transportation time of cargo consists of two parts: one is the time for the gantry crane to load and unload the cargo to the trailer, and the other is the time for the trailer to transport the cargo to the yard, which can be expressed as:

[0127]

[0128] Where: It represents the latest delivery time of the i-th cargo on the l-th cargo ship.

[0129] Specifically, the scheduling of gantry cranes and storage yards are two crucial links in the loading and unloading operations of piece cargo terminals.

[0130] This embodiment fully considers the costs of gantry crane and trailer scheduling when optimizing gantry crane and yard scheduling. Based on information and historical data provided by the terminal, gantry crane operating losses and trailer unit distance transportation costs are derived. By incorporating these factors into the objective function, the system more comprehensively reflects the terminal's actual costs and benefits. This improves the terminal's overall operational efficiency and service level, provides scientific decision-making support for terminals, and drives breakbulk terminals toward more sustainable development.

[0131] Specifically, this example minimizes the total turnover time of gantry crane and trailer operations. This integration of optimization objectives helps avoid over-allocating equipment to a single vessel during terminal unloading operations, rationally allocating terminal gantry crane and trailer resources, and ensuring a more balanced allocation of limited terminal equipment while ensuring that cargo can meet delivery time requirements. Furthermore, this example innovatively considers the time consumed by gantry cranes changing loading and unloading tools, and includes the number of such tool changes as one of the optimization objectives. At breakbulk terminals, gantry crane operating time is crucial to overall terminal efficiency, making this optimization objective more aligned with actual terminal operational needs.

[0132] In a specific embodiment, the improved NSGA-II algorithm is used to solve the optimization objective function to obtain the optimal solution set, that is, the optimal coordinated scheduling solution of the gantry crane and the storage yard. The specific process is as follows:

[0133] Preferably, if Figure 4 As shown, the improved NSGA-II algorithm performs the following steps:

[0134] During the algorithm preparation phase, parameters related to the coordinated scheduling model for gantry cranes and storage yards at breakbulk terminals are imported, including: the number of arriving ships and the type, number, and priority of their cargo; the number of gantry cranes at the breakbulk terminal, the number of trailers, the berth-to-stockyard distance (used in trailer transport constraints and for initializing the population); the stockyard capacity (used for allocating cargo to the stockyard) (both matrices are pre-existing parameters and are determined by the terminal to which the proposed solution is actually applied); the workload and cost of the gantry cranes and trailers; and the maximum travel distance for trailers. Basic parameters for initializing the algorithm include the population size N, the crossover probability, and the mutation probability.

[0135] S31: Initialize the population: Initialize the population by generating random real numbers.

[0136] S32: Based on the fitness function, obtain the fitness value of the initialized population and perform fitness evaluation on the initialized population P0:

[0137] (1) This embodiment uses the inverse objective function method to construct the fitness function:

[0138]

[0139] Where: z i Represents the value of the fitness function;

[0140] Therefore, the three fitness functions of this embodiment correspond to

[0141] (2) Evaluate the population: Calculate the three fitness values ​​of each individual in the initial population based on the fitness function: time, cost, and the total number of tool changes.

[0142] S33: performing non-dominated sorting on the initialized population according to the fitness value of the initialized population, obtaining multiple non-dominated layer sequences, and obtaining the crowding degree of individuals in the non-dominated layer sequences;

[0143] Specifically, in this embodiment, the non-dominated sorting of the initialized population and the acquisition of the crowding degree between individuals in the non-dominated layer sequence are both calculated using conventional techniques in the art, which will not be described in detail here.

[0144] S34: Based on the crowding degree of individuals in the non-dominated layer sequence, the individuals in the initialized population are sequentially subjected to selection, crossover, and mutation operations to obtain a child population P1; the parent population P0 and the child population P1 are merged into a new population, and the current population generation is updated to Gen'=Gen+1;

[0145] S35: performing a non-dominated sort on the new population to obtain a non-dominated layer sequence of the new population, and randomly selecting u non-dominated layer sequences of the new population so that the sum of the number of individuals in the 1st to u-1st non-dominated layer sequences of the new population is less than the number of individuals in the initialization population, and the sum of the number of individuals in the 1st to uth non-dominated layer sequences of the new population is not less than the number of individuals in the initialization population; wherein u≤U, U is the total number of non-dominated layers of the new population; and u is the index of the non-dominated layer of the new population;

[0146] S36: If the sum of the numbers of individuals in the u non-dominated layer sequences of the new population is greater than the number of individuals in the initialization population, then the crowding degrees of the individuals in the u non-dominated layer sequences of the new population are obtained, and individuals in the u non-dominated layer sequences of the new population are deleted in ascending order of their crowding degrees until the sum of the numbers of individuals in the u non-dominated layer sequences of the new population after deletion is equal to the number of individuals in the initialization population;

[0147] S37: For the individuals in the non-dominated layer sequence of the new population u after deletion, based on the dynamic crossover probability and the dynamic mutation probability, a dynamic crossover operation and a dynamic mutation operation are sequentially performed to obtain the evolved new population;

[0148] S38: Based on the evolved new population, repeat S32 to S37 until the iteration end condition is met.

[0149] Preferably, in this embodiment, the crossover operation based on dynamic crossover probability is the key to determining the global search capability of NSGA-II. Since the mutation operation does not play a major role in the early stages of evolution, the algorithm needs to make the crossover probability larger in the early stages to explore the solution space as much as possible. As the number of evolutions increases, the population becomes stable. In order to avoid falling into a local optimum, the crossover probability must be reduced by increasing the mutation probability to accelerate the convergence of the algorithm. Therefore, it is necessary to dynamically adjust the crossover and mutation probabilities to achieve the following optimization:

[0150]

[0151] Where: P c is the current crossover probability; and are the minimum and maximum values ​​of the crossover probability respectively; z i is the value of the fitness function; f max is the maximum fitness value in the current population;

[0152] Specifically, after the dynamic crossover operation is completed, a dynamic mutation operation is performed on the individual, and the dynamic mutation probability is obtained as follows:

[0153]

[0154] Where: P m is the current mutation probability; and are the minimum and maximum values ​​of the mutation probability respectively;

[0155] Specifically, when the number of iterations reaches the set maximum and the first-layer solution of all non-dominated layers is output, the optimal coordinated scheduling solution for the gantry crane and the yard can be obtained.

[0156] This method schedules cranes and trailers for berthing vessels based on known parameters related to ship loading and unloading at breakbulk terminals, including the number of cranes, the number of trailers, the berth-yard distance matrix, the yard capacity matrix, the number of approach bridges, the workload and cost of cranes and trailers, cargo weight, volume, and priority. This allows cargo from each hold to be transported to the yard, completing the loading and unloading process for breakbulk vessels. This provides a decision-making reference for port dispatchers in designing scheduling plans, significantly reducing their time. This systematic management approach helps breakbulk terminals maintain their competitive edge in the fiercely competitive market.

[0157] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the above embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for coordinated dispatching of gantry cranes and storage yards at general cargo terminals, characterized in that: The steps include: S1: Determine the constraints for coordinated scheduling of the gantry crane and the storage yard at the general cargo terminal; S2: Construct an optimization objective function for the coordinated scheduling of the gantry crane and the storage yard at the breakbulk terminal. The optimization objective function aims to minimize the total cargo turnover time, the total cost consumed by the loading and unloading operations, and the total number of tool changes during the gantry crane loading and unloading operations. S3: Based on the optimization objective function, the improved NSGA-II algorithm is used to obtain the positions of the gantry cranes, trailers, and storage yards assigned to the cargo on the cargo ship, so as to obtain the optimal coordinated scheduling solution for the gantry cranes and storage yards.

2. The method for coordinated dispatching of gantry cranes and storage yards at breakbulk cargo terminals according to claim 1, characterized in that: The optimization objective function for the coordinated scheduling of the gantry crane and the storage yard at the general cargo terminal is constructed as follows: Minimize Cost=Z1+Z2+Z3 in, Where Cost represents the overall optimization goal; Z1 represents the total turnover time of all cargoes from the start of loading and unloading on the ship to the storage yard; Z2 represents the total cost incurred during cargo loading and unloading, including the gantry crane operation time cost, trailer transportation time cost, and trailer transportation distance cost; Z3 represents the total number of tool changes of all gantry cranes during loading and unloading operations; N j It indicates the total number of tool changes of a single gantry crane during loading and unloading operations; i indicates the cargo type number; n indicates the total number of cargo types; j indicates the gantry crane number; m indicates the total number of gantry cranes; l indicates the number of docked cargo ships; o indicates the total number of docked cargo ships; k indicates the trailer number; p indicates the total number of trailers; T ijl T represents the time required for the jth gantry crane to load and unload the i-th cargo on the l-th cargo ship; j Indicates the total time consumed by the door operator to replace the tools; T ikl S represents the time required for the k-th trailer to transport the i-th cargo on the l-th cargo ship to the designated storage site; i represents the cost per unit time of the jth gantry crane; x ijl is the decision variable used to indicate whether the jth gantry crane participates in loading and unloading the i-th cargo on the l-th cargo ship; L ilr represents the one-way path from the i-th cargo on the l-th cargo ship to the r-th yard; z ikl S represents the decision variable for whether the i-th cargo on the l-th cargo ship is transported by the k-th trailer; k It represents the cost per unit distance of trailer transportation; S represents the unit time cost of trailer transportation.

3. The method for coordinated dispatching of gantry cranes and storage yards at breakbulk cargo terminals according to claim 1, characterized in that: The constraints include: gantry crane constraints, trailer constraints, cargo constraints, and yard constraints.

4. The method for coordinated dispatching of gantry cranes and storage yards at breakbulk cargo terminals according to claim 3, characterized in that: The door machine constraints are expressed as follows: Where: T ijl represents the time required for the jth gantry crane to load and unload the i-th cargo on the l-th cargo ship; x ijl is the decision variable used to indicate whether the j-th gantry crane participates in loading and unloading the i-th cargo on the l-th cargo ship; ceil(·) is the upward rounding function; It represents the number of cargoes of type i cargo on ship l that are assigned to the jth gantry crane for operation; Indicates the maximum number of pieces of cargo that can be handled by the gantry crane in a single operation; Indicates the single operation time of the gantry crane for the i-th type of cargo; T j =N j *t j Where: N j Indicates the total number of tool changes for a single gantry crane during loading and unloading operations; t j Indicates the average time required to replace the tools of the gantry crane; Where: Q i and Respectively represent the weight of a single piece of cargo of category i, Indicates the maximum lifting weight limit when the gantry crane is working; 5. The method for coordinated dispatching of gantry cranes and storage yards at breakbulk cargo terminals according to claim 3, characterized in that: The trailer constraint is expressed as follows: Where: T ikl The time required for the k-th trailer to transport the i-th cargo on the l-th cargo ship to the designated storage area; ilr is the decision variable indicating whether the i-th cargo on the l-th cargo ship is allocated to the r-th yard; ikl represents the decision variable for whether the i-th cargo on the l-th cargo ship is transported by the k-th trailer; ceil(·) is the upward rounding function; L lr V represents the distance from the berth where the l-th cargo ship is located to the r-th yard, k represents the fully loaded speed of the k-th trailer; represents the unloaded speed of the k-th trailer, represents the total number of pieces of the i-th type of cargo on the l-th cargo ship, It represents the maximum number of fully loaded pieces of the i-th type of cargo that the k-th trailer can transport in a single trip; Where: is the maximum transport distance of the k-th trailer; 6. The method for coordinated dispatching of gantry cranes and storage yards at breakbulk cargo terminals according to claim 3, characterized in that: The yard constraints are expressed as follows: v ir *and ilr =and ilr ,and ilr =1 Where: v ir The parameter indicating whether the i-th type of goods can be stacked in the r-th yard. v ir =1, it means that the i-th type of goods can be stacked in the r-th yard; ilr The parameter indicating whether the i-th cargo on the l-th cargo ship is allocated to the r-th yard. ilr =1, it means that the i-th cargo on the l-th cargo ship is allocated to the r-th yard; Where: It represents the remaining capacity of the r-th yard for storing the i-th type of goods.

7. The method for coordinated dispatching of gantry cranes and storage yards at breakbulk cargo terminals according to claim 3, characterized in that: The cargo constraints are expressed as follows: Where: represents the total number of pieces of cargo of type i on cargo ship l; represents the number of pieces of cargo of type i on cargo ship l assigned to gantry crane j; Pi l >Pi, l Where: Pil is the priority of the i-th cargo on the l-th cargo ship, Indicates the time when the i-th cargo on the l-th cargo ship begins to be loaded and unloaded; i′ and i both represent the cargo type number, i′≠i; Where: It represents the latest delivery time of the i-th cargo on the l-th cargo ship.

8. The method for coordinated dispatching of gantry cranes and storage yards at breakbulk cargo terminals according to claim 1, characterized in that: The improved NSGA-II algorithm performs the following steps: S31: Get the initial population; S32: Based on the fitness function, obtain the fitness value of the initialized population; S33: performing non-dominated sorting on the initialized population according to the fitness value of the initialized population, obtaining a non-dominated layer sequence, and obtaining the crowding degree of individuals in the non-dominated layer sequence; S34: Based on the crowding degree of individuals in the non-dominated layer sequence, the individuals in the initialized population are sequentially subjected to selection operation, crossover operation, and mutation operation to obtain a child population; and a new population is obtained based on the parent population and the child population; S35: performing a non-dominated sort on the new population to obtain a non-dominated layer sequence of the new population, and randomly selecting u non-dominated layer sequences of the new population so that the sum of the number of individuals in the 1st to u-1st non-dominated layer sequences of the new population is less than the number of individuals in the initialization population, and the sum of the number of individuals in the 1st to uth non-dominated layer sequences of the new population is not less than the number of individuals in the initialization population; wherein u≤U, U is the total number of non-dominated layers of the new population; and u is the index of the non-dominated layer of the new population; S36: If the sum of the numbers of individuals in the u non-dominated layer sequences of the new population is greater than the number of individuals in the initialization population, then the crowding degrees of the individuals in the u non-dominated layer sequences of the new population are obtained, and individuals in the u non-dominated layer sequences of the new population are deleted in ascending order of their crowding degrees until the sum of the numbers of individuals in the u non-dominated layer sequences of the new population after deletion is equal to the number of individuals in the initialization population; S37: For the individuals in the non-dominated layer sequence of the new population u after deletion, based on the dynamic crossover probability and the dynamic mutation probability, a dynamic crossover operation and a dynamic mutation operation are sequentially performed to obtain the evolved new population; S38: Based on the evolved new population, S32 to S37 are repeatedly executed until the iteration end condition is met.

9. The method for coordinated dispatching of gantry cranes and storage yards at breakbulk cargo terminals according to claim 8, characterized in that: The dynamic crossover probability is obtained as follows: Where: P c is the current crossover probability; and are the maximum crossover probabilities respectively.

10. The method for coordinated dispatching of gantry cranes and storage yards at breakbulk cargo terminals according to claim 8, characterized in that: The dynamic mutation probability is obtained as follows: Where: P m is the current mutation probability; and are the minimum and maximum values ​​of the mutation probability, respectively.

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