Research On Path Planning Of Multi AGV Automatic Sorting System In Logistics Center

The prosperity and booming development of online-shopping has changed people's shopping habits,bringing massive commodities to be sorted and delivered to customers in different regions through express mails,which leads to great challenges to modern logistics center.The traditional express sorting adopts the combination of conveyor belt and manpower,but it cannot cope with the increasing number of express mails,and the sorting capacity is not flexible to be expanded during the logistics peak period like ”double eleven”.Therefore the automatic sorting of express mails is of great significance for modern logistics center.Using special customized AGV(automated guided vehicles)robot to automatically transport and delivery express packages is gaining more and more attention of logistics enterprises.This paper studies the path planning problem of multiAGV automatic sorting in logistics center.For the given plant layout,our goal is to transport and sort as many packages as possible during the system operation and use as few AGVs as possible.To solve the problem of multi-AGV routing in logistics center,the main work of this paper is as follows:In this paper,the background and essentiality of multi-robot path planning problem are summarized,and the advantages and disadvantages of the existing approaches to solve multi-robot path planning are analyzed in detail.Based on the existing works on multirobot path planning,we abstract the actual warehouse map into a directed graph,after that we give the formal problem description of path planning for multi-AGV automatic sorting system.Aiming at the multi-AGV single-load routing problem,this paper proposed two heuristic time-window searching algorithms which are F-TWS and RS-TWS,the AGV determines its traveling time on each path blocks through searching the free time window combinations for all path blocks.Wait-and-go policy is used for avoiding the conflicts of entering the same path block with other AGVs.Experiment results show that compared with existing path planning algorithms such as HTN and TW-A*,our approaches can achieve higher sorting throughput while using less AGV during given period.For the multi-AGV multi-load path planning,this paper presents a complete description and mathematical modeling for the problem of to-be-sorted express mail selection and destination point visit sequence.Due to the NPC property of this problem,we present four heuristic methods: Rand-S,AF-S,NF-S,and GRASP-S for practical industrial application.The simulation results verify the effectiveness of those four methods and show the growth in efficiency of multi-load strategy compared with single-load strategy.