Integrated Scheduling Optimization Of Flexible Job Shop Machines And AGVs Based On Hybrid Simulation

Driven by the requirements of "Made in China 2025" intelligent manufacturing strategy and the rapid development of information technology,flexible job shop plays an increasingly important role in multi-variety and small-batch production mode.In flexible job shop,due to the existence of parallel equipment or multiple processing capabilities of the same machine,there are multiple machines to choose from in one process,and these machines are located at different locations in the workshop,and often have different transfer times as the workpiece moves through the workshop with the Automatic Guided Vehicle(AGV).In the traditional flexible job shop scheduling research,most of them ignore the influence of AGV transfer time while the machine resource is the center,and the formed scheduling scheme has problems such as task delay and logistics chaos due to untimely material transportation.Therefore,it is necessary to integrate flexible job shop scheduling with AGV scheduling to reasonably arrange workshop production.In addition,in the actual production environment,there are dynamic interference events such as AGV collision,emergency order insertion and equipment failure,which affect the original scheduling scheme.Therefore,it has become an urgent problem to develop a robust integrated scheduling scheme of machines and AGVs under dynamic disturbance.Therefore,this thesis takes the flexible job shop as the research object,aiming at the integrated scheduling problem of machines and AGVs,carries out the research on the integrated scheduling optimization method of machines and AGVs based on hybrid simulation.In this thesis,a hybrid simulation model combining discrete event simulation and agent simulation is constructed,and the static and dynamic integrated scheduling for machines and AGVs is realized by using improved contract network technology and agent interaction.The main research contents of this thesis are as follows:(1)Construction of hybrid simulation model for flexible job shop machines and AGVs integrated scheduling problem.Aiming at the integrated scheduling problem of machines and AGVs in flexible job shops,according to the characteristics of the problem,discrete event simulation and agent based simulation methods are used to construct a production process sub-model that controls the product process in the workshop and an agent decision-making sub-model that handles decision-making problems in the workshop.The two models are integrated to construct a hybrid simulation model for the integrated scheduling problem of flexible job shop.(2)Solution of machines and AGVs static integrated scheduling problem based on improved contract network protocol.Aiming at the static integration scheduling of machines and AGVs in flexible job shops,the contract network protocol is used as the negotiation mechanism between agents,and a hybrid simulation solution method based on the contract network protocol for real-time allocation of process tasks is studied.Based on the expansion of the task buffer pool and the bidding priority mechanism,the problems of bidding broadcast,vicious bidding,single task authorization,and no feedback on the quality of task completion in the negotiation process of the contract network are improved,and combined with the execution process of process tasks,a selection strategy of machines and AGVs that conforms to the characteristics of the integrated scheduling problem is formulated to realize the static integrated scheduling of machines and AGVs.Finally,a numerical example is used for simulation verification to prove the effectiveness and superiority of the proposed method.(3)Machines and AGVs dynamic integrated scheduling problem considering multi-AGV collision-free path planning.Aiming at the dynamic integration scheduling problem of flexible job shop machines and AGVs,a hybrid simulation solution method that integrates path planning and disturbance response strategies is studied.Based on the information interaction between the node agent and the AGV agent,the shortest collision-free path of the AGV is planned,and three types of conflict detection and resolution strategies during the driving process of the AGV are formulated,and then the path planning results are fed back to the task allocation level to form an integrated scheduling scheme that considers AGV path planning.On this basis,the disturbance response strategy for order insertion and equipment failure is formulated to realize the dynamic integrated scheduling of machines and AGVs,and simulation examples are used to verify the effectiveness and superiority of the proposed method.(4)Application of integrated scheduling method of flexible Job shop based on hybrid simulation.Taking a gear production workshop of an enterprise as an engineering example,based on the hybrid simulation model of workshop,the static and dynamic integrated scheduling problems in workshop are solved respectively by combining improved contract network technology and agent information interaction,which further verifies the feasibility and practical application value of the proposed method in engineering.