Research On Integrated Optimization Of Intercell Scheduling And Vehicle Routing Planning

At present,most studies about intercell scheduling use transportation strategies to determine vehicle arrangements and driving routes.However,most of these transportation strategies restrict vehicles to transport only one exceptional part at a time,resulting in low vehicle utilization,increased number of transportation between cells,which increase total cost.In order to improve improve the utilization rate of vehicles and effectively reduce total cost while ensuring production efficiency,this paper intends to optimize intercell scheduling in cellular manufacturing systems with different numbers of vehicles,and optimize vehicle path at the same time,allowing a vehicle to transport multiple exceptional parts at a time,and vehicles are shared by all cells.Firstly,for cases of one vehicle and multiple vehicles in cellular manufacturing system,integrated optimization models of intercell scheduling and 1-PDP and of intercell scheduling and m-PDP are established respectively aiming to minimize makespan and total cost.Secondly,select multi-objective evolutionary algorithm based on decomposition MOEA/D to solve the integrated optimization model,and due that the basic MOEA/D algorithm has insufficient population diversity and is easy to fall into the local optimal,an improved IMOEA/D algorithm using two-stage search strategy based on double reference points is designed to ensure solution quality.A five-segment chromosome coding based on operation,cell,machine,vehicle and vehicle route is designed.And because randomly generated vehicle routing codes may violate process planning of parts and vehicle capacity constraints,a binary tree-based adjustment method and a vehicle capacity constraint adjustment method are respectively designed to change infeasible vehicle routing codes to be feasible.Finally,in order to verify the integrated optimization,for a inter-cell scheduling case,integrated optimization is carried out.And the results of integrated optimization are compared with those of different vehicle transportation strategies under the same conditions.It is found that integrated optimization is superior to vehicle transportation strategy in terms of minimizing makespan and total cost.In order to ensure comparability,eliminate the influence of different inter-cell scheduling schemes for results,under the same scheduling scheme comparison,further compared with the vehicle transportation strategies,integrated optimization by allowing a vehicle can transport multiple exceptional parts and vehicles are shared between cells,improves the utilization rate of vehicles,reduces the number of transportation between cells,therefore effectively reduces transportation cost,thereby reduces total cost.In this case,integrated optimization also shorten waiting time of exceptional parts,which is beneficial to reduce makespan.In addition,IMOEA/D algorithm and the original algorithm are used to solve the same integration optimization case,and the performance index of the algorithm is compared,which verifies the advantages of IMOEA/D algorithm in solving the integration optimization problem.