Research On Dynamic Production Scheduling Of Flexible Assembly Job Shop With Disturbance

In order to meet the customized demand of products,most of the mould manufacturing enterprises are single or small-batch production mode.Most of the customized moulds are trial-manufacturing assembly products,whose parts can be assembled only after finishing machining with different routines and processing time.The trial manufacturing characteristics of the mould greatly increase the disturbance frequency,and accidents such as rework and machine break bring great difficulties to the coordination of the related parts.In addition,in order to meet all kinds of process requirements,mould enterprises will generally configure all kinds of processing resources as far as possible,which greatly increases the flexibility of mould production.If processing routines of parts is unreasonable,it will lead to the workshops load imbalance,and reduce the performance of the workshop production.In this paper,the dynamic scheduling problem of customized mould shop is studied,which is essentially a kind of dynamic scheduling problem of flexible assembly shop with disturbance.In this paper,the following three scheduling solutions are studied:(1)priority scheduling rules,a real-time fully reactive scheduling strategy,which can complete the scheduling quickly and in real time,but its decision-making is decentralized and lacks of global optimization of the workshop;(2)Periodic rolling scheduling,a pre-reactive scheduling method for centralized planning of all parts processing plan in workshop,but the disturbance will lead to the decline of the performance of pre-scheduling plan;(3)A hierarchical scheduling method coupled release control and dispatching Rule.It makes the production plan of the workshop from the point of view of load balancing and timely,but does not specify the start-up and completion time of the parts to the machine,while real-time dispatching of the parts is completed by the job priority dispatching rules,which has the optimization power of centralized release and is suitable for the situation of disturbance.Based on the dynamic production simulation model of a flexible assembly job shop,,considering the effect of disturbance intensity on different scheduling solution,the main research work of this paper is as follows:Firstly,there are two kinds of complete reactive scheduling rules in flexible workshop: machine selection rule and job dispatching rules.The performance of these two kinds of rules is analyzed respectively,and the combination effect of the two kinds of rules and the trend of their performance changing with disturbance intensity are further analyzed.Secondly,a periodic rolling scheduling algorithm based on genetic algorithm is implemented as a representative of pre-reactive scheduling.Comparing the complete reactive scheduling combination rules,the performance trend of the two scheduling method with the change of disturbance intensity is analyzed through simulation experiments.Finally,considering the lack of global optimization of complete reactive scheduling and the deterioration of performance of pre-reactive scheduling in high disturbance,a load balancing based release control method will be introduced to formulate the production plan of the workshop to improve the global optimization.At the same time,real-time priority scheduling rules will be combined to ensure the flexibility of the internal scheduling of the workshop.