Research On Flexible Job Shop Integrated Scheduling Based On Double-layer MAS

With the personalized and diversified requires of customers,the manufacturing industry has gradually changed from mass continuous production to multi-variety,small-batch discrete production to adapt to the dynamic changes of the market.Flexible job shop scheduling problem plays an increasingly important role in production scheduling problem.However,in the actual production environment,various sudden dynamic interference events,such as machine failure,random arrival of workpiece,delivery delay,emergency order insertion,etc.,have a serious impact on the efficiency and stability of flexible job shop scheduling.The research on the dynamic flexible job shop scheduling problem has b ecome a hot topic in the field of production scheduling.At present,intelligent and automatic production mode puts forward higher requirements for material transportation in the workshop.More and more enterprises invest in AGV to distribute materials.AGV is widely used in production workshop and logistics system.While solving the dynamic flexible job shop scheduling problem,considering AGV scheduling can further rationally arrange workshop production,improve production efficiency and ensure that the plan is implemented on schedule.Therefore,in this paper,based on the actual situation of the enterprise,considering the AGV flexible job shop integrated dynamic scheduling problem,the flexible job shop scheduling model based on double-layer MAS and the integrated scheduling model are constructed respectively.The double-layer multi-agent scheduling and collaborative strategy based on service unit are used to solve the model before and after the integration,and the solution with certain accuracy and high robustness is obtained.The main contents of this paper are as follows:(1)Based on the service unit,a hybrid architecture of double-layer multi-agent system is designed.According to the actual demand of the integrated scheduling problem of flexible jop shop,firstly,the function of each agent is designed,and the multi-agent system of flexible job shop based on service unit is constructed.Then,according to the structural characteristics of multi-agent system,a hybrid architecture of double-layer multi-agent system is designed,and its structural characteristics are further analyzed in combination with actual scheduling problems.(2)The model of flexible job shop scheduling problem based on double-layer MAS is constructed and solved.According to the problem,a mathematical model with the objective of minimizing the maximum completion time is established.Combined with the hybrid architecture of the double-layer multi-agent system,the driving strategy of dynamic scheduling and the scheduling negotiation strategy of the top and bottom layers of the multi-agent system are studied to solve the model.Finally,the effectiveness of the multi-agent system method under the double-layer architecture is verified by using the standard case library Kacem.Compared with other algorithms,the superiority of the double-layer architecture multi-agent system method in dynamic environment is verified.(3)The model of flexible job shop integrated scheduling problem based on double-layer MAS is constructed and solved.On the basis of the flexible job shop scheduling problem,the AGV material handling problem is concerned.The mathematical model of the flexible job shop integrated scheduling problem considering AGV is established,and the integrated scheduling negotiation mechanism of AGV under the double-layer multi-agent system architecture is studied.The integrated scheduling of machines and AGV in the flexible job shop is realized.Finally,an experimental example based on the standard case library is used to verify the model.By comparing the single-layer multi-agent system method,the superiority of the double-layer multi-agent system method in dynamic environment is verified.(4)An engineering example of flexible job shop integrated scheduling based on service unit is given.Taking an enterprise’s gear production workshop as an engineering example,the production process,workshop layout and equipment information are analyzed,and the existing scheduling problems are researched.Aiming at the dynamic situation suc h as the arrival of new workpiece and machine failure,a discrimination method for real-time collection of dynamic factors is proposed.The flexible job shop integrated scheduling problem solving method based on double-layer MAS proposed in this paper is used to solve the engineering example.The integrated scheduling problem of flexible job shop under arrival of new workpiece and machine failure is effectively solved.