| With the increasingly fierce global economic competition,the manufacturing industry needs to constantly transform to meet the diversification and customization of market demand.The production mode of enterprises has gradually changed from the mode of mass production with fixed product types to the mode of multi variety and small batch production.In order to adapt to the changing market demand,the internal structure of manufacturing system also needs to be adjusted accordingly,so the reconfigurable manufacturing system(RMS)emerges as the times require.Reconfigurable manufacturing system can respond to market changes quickly,improve production efficiency and reduce production costs by reconfigurating the configuration of the system.Equipment layout and job scheduling are not only the two key technologies of reconfigurable manufacturing system,but also the classical combinatorial optimization problem.The two problems are interrelated and interact in practical application.Therefore,it is necessary to study the integrated simulation optimization of equipment layout and job scheduling.In order to solve the integrated optimization of equipment layout and job scheduling in each reconfiguration cycle of reconfigurable workshop,this paper constructs a multi-objective simulation optimization model of equipment layout and job scheduling by designing nested gravitational search genetic algorithm and combining Entropy-TOPSIS multi-objective evaluation model.It provides a theoretical and simulation optimization method for the reconfigurable workshop periodic reset equipment layout and job scheduling scheme.Based on the analysis of the characteristics of reconfigurable workshop,the types of equipment layout and job scheduling process,the solution method of layout and scheduling is designed,and the evaluation indexes of integrated optimization of equipment layout and job scheduling in reconfigurable workshop are determined.The overall research framework of the integrated optimization of equipment layout and job scheduling is designed.The discrete event modeling method is used to build the simulation model.The simulation model is used to calculate the index values,and the optimization algorithm is combined to solve the integration problem.The mathematical model is established with the minimum completion time,the shortest AGV load distance and the minimum maximum machine load as the optimization objectives.The simulation model is designed on the basis of model constraints and optimization objectives.In order to get a relatively better layout and scheduling scheme,the entropy method is used to weight each evaluation index,and then the TOPSIS method is used to evaluate and sort different schemes,so as to realize the optimal selection of schemes.According to the relationship between equipment layout and job scheduling in reconfigurable workshop,a nested gravitational search genetic optimization algorithm is designed.The nested algorithm is divided into two layers.Among them,the lower layer is adaptive genetic algorithm,which allocates the equipment location reasonably;the upper layer is improved gravity search algorithm,which calculates the job shop scheduling effectively.The upper and lower layers of the nested gravitational search genetic algorithm achieve the optimal solution through data interaction in the iterative process.In order to solve the integrated problem of layout and scheduling in reconfigurable job shop,a simulation optimization model of equipment layout and job scheduling is established by combining the simulation model with nested gravitational search-genetic optimization algorithm.The effectiveness and feasibility of the whole optimization model,the proposed algorithm and each module are verified by an example. |
