Research On Configuration Optimization And Scheduling Algorithm Of Four-way Shuttle-based Storage And Retrieval System

With the implementation of the "Made in China 2025" plan,more and more enterprises have begun to use automated three-dimensional warehouse systems in the storage link.Due to the diversity of enterprise storage requirements,the market has increasingly demanded the flexibility of automated three-dimensional warehouse systems.The four-way shuttle-based storage and retrieval System(FWSBS/RS)studied in this paper was born under this background.The shuttle in FWSBS/RS can move back and forth or left and right.FWSBS/RS can flexibly configure the number of shuttles,so it has strong flexibility.At the same time,how to configure a reasonable number of shuttles under different system parameters has become an urgent problem for enterprises.On the other hand,the shuttle in FWSBS/RS can perform storage and retrieval tasks across aisle,and the shuttle's motion path is more flexible.The rationality of FWSBS/RS's task scheduling has become a major factor affecting its operational efficiency.Therefore,this paper studies the configuration optimization problem and scheduling optimization problem of FWSBS/RS.First,we study the configuration optimization of FWSBS/RS.By analyzing the operation flow of the retrieval task,we get the average operation time model of the retrieval task.Considering the mutual waiting queue between the shuttle and retrieval tasks in the actual operation of FWSBS/RS,a semi-open queuing network(SOQN)model was established to describe its operation.The service rate of nodes in SOQN can be calculated by the average operation time model of retrieval tasks.Next,we use matrixgeometric method(MGM)to solve this SOQN.By comparing with the results of the warehouse simulation program,we verified the correctness of the SOQN and the accuracy of the MGM solution results we used.We carried out experiments on the retrieval task achievement rate,the number of tiers of storage shelves,and the number of columns of storage shelves in the factors affecting the number of shuttles to solve the optimal configuration of FWSBS/RS.We have obtained data on system performance that varies with the number of shuttles under different system parameters.Our experimental data can be used to guide the selection and planning of the enterprise storage system and the flexible adjustment during operation.The purpose of schedule task is to optimize the retrieval order and method of batch orders to minimize its total retrieval time.By analyzing the composition of the retrieval time,we construct a FWSBS/RS task scheduling model based on the lift operation timeline.To solve the problem of shuttle conflicts that may occur in the FWSBS/RS task scheduling process,we propose a conflict type judgment and conflict elimination scheme based on the path time window.In this paper,a genetic algorithm based discrete particle swarm optimization is used to solve the task scheduling model.We have designed individual coding schemes that encode each lift task separately,and have made adaptive improvements to the speed and location update method of the algorithm.Finally,the validity of GA-DPSO is proved by an example analysis,and the results are compared with the results obtained by discrete particle swarm optimization(DPSO)and genetic algorithm(GA).The results show that compared with DPSO and GA,GA-DPSO has greatly improved the convergence speed,global search capability,and algorithm stability.