Research On Multi-flexible Integrated Scheduling Problems

Integrated scheduling is a scheduling method for complex products,which schedules the process parts and assembly operations simultaneously.This scheduling mode makes up for the shortcomings of traditional scheduling mode which ignores the interaction between processing and assembly operations,enhances the parallel relationship between them,reduces the waiting time of assembly operations,and improves the efficiency of equipment.Besides,it can also handle large complex products with reprocessing characteristics of sub-assemblies.At present,most intelligent algorithms for general integrated scheduling problems adopt the coding method based on operation sequence,which increases the duplicate samples in the population and has the disadvantages of mutation or crossover operator invalidation.In addition,due to the complex relationship between operations of tree structure products,they need to designed correction strategy to ensure the feasibility of the solution generated after crossover or mutation,which often increases the complexity of the algorithms.Besides the general integrated scheduling problems,flexible integrated scheduling has also received extensive attention.However,previous researches only considered the flexibility of the equipment,but ignored the flexibility of the processing routes and the operations.And most of them use the short-time strategy to simplify the flexible process tree and construct the path attributes of operations,ignoring the influence of other non-shortest processing time of the operations.Therefore,in order to improve the optimization effect of the integrated scheduling problems and fully consider the multi-flexible characteristics of the flexible integrated scheduling problems,this paper has studied the integrated scheduling problems and the multi-flexible integrated scheduling problems.The main research contents are as follows:Firstly,aiming at solving the general integrated scheduling problem with more intelligent methods,an effective integrated scheduling algorithm based on estimation of distribution algorithm and signal-driven method is proposed.Firstly,the probabilistic model is used to describe the position relationship of each operation on the equipment.In addition,the machine-dependent chain is used to reduce the repetition rate of individuals in a generation.On this basis,a signal-driven-based sampling mechanism is proposed to ensure that individuals are feasible solutions with good diversity,and the enhanced sampling probability is designed to speed up the search for the optimal solutions.During the sampling,the trigger time chain can save individual decoding time.Finally,an update mechanism based on incremental learning is used to update the probabilistic model and gradually narrow the search range to obtain the best solution.Experimental results show that the proposed algorithm has better optimization performance and better solution quality than other comparison algorithms.Secondly,aiming at the problem of integrated scheduling with equipment flexibility,a flexible integrated scheduling system framework with three management subsystems is designed,and a signal-driven-based flexible integrated scheduling algorithm with bidirectional coordination mechanism is proposed by simulating the information interaction between subsystems and resources.It makes up for the shortcomings of the previous flexible integrated scheduling algorithms,which relies too much on short-time strategy,weakens the flexibility of the equipment,ignores the dual selection relationship between the equipment and the operations,and ignores the flexibility of the independent operations in tree structure products.In the proposed algorithm,a bidirectional coordination mechanism is proposed to coordinate the selection between the equipment and the operations.The influence of the equipment and the operations on each other is fully considered,and the shortcoming of paying too much attention to one of them is avoided.A bidirectional scheduling strategy is proposed to eliminate the influence of the operation tree scheduling direction on products.The equipment-operation coordination strategy based on the grey correlation analysis is designed to comprehensive consider the effects of the processing time,the relative path,and other factors on the machine scheduling and the operation scheduling.Then the optimal combination strategy is used to solve the conflict between machines and operations.Experimental results show that the proposed algorithm outperforms other comparison algorithms in solving flexible integrated scheduling problem.Thirdly,the integrated scheduling problem with processing route flexibility is proposed.According to the information transfer between the resources and the system in a smart workshop,the integrated scheduling system framework based on the idle machine event-driven is proposed.Under this framework,the dual event-driven-based integrated scheduling algorithm considering flexible processing routes is proposed.The algorithm uses an equipment-operation event-driven strategy based on maximum relaxation time to simulate the negotiation process of the equipment and the operations.The device-driven strategy realizes the negotiation process in which the equipment dominates the negotiation,and the operation-driven strategy realizes the negotiation process in which the operations dominate the negotiation.The cooperation between schedulable operations and busy devices is considered,which is realized by recalling driven time and freezing the original cooperations.The strategy of the earliest completion of the last flexible operation is proposed to solve the problem of choosing the first flexible operation and its corresponding equipment on the equivalent path.Experiments show that the proposed algorithm can effectively solve the integrated scheduling problem considering the flexible processing routes.Meanwhile,compared with the previous integrated scheduling algorithms,it also has better optimization ability in solving the general integrated scheduling problem.Finally,a multi-flexible integrated scheduling problem considering setup times is proposed,which considers the flexibility of equipment,the flexibility of processing routes,and the flexibility of operations.To solve this problem,the multi-flexible integrated scheduling algorithm is proposed.The operation optimization allocation strategy,based on the long relative subsequent path principle,is proposed to allocate the operation with the optimal processing time to the idle machine.The parallel optimization strategy is proposed to adjust the scheduling of planning operations and planning machines,so as to make the processing as parallel as possible and reduce the no-load machines.Then,the flexible operation determination strategy is combined with the above two strategies to determine the flexible operation as the dynamic choice of the planned operations.Finally,the potential operation preemption strategy is proposed to judge whether the planned operations will be interrupted by other operations.Experimental results show that the proposed algorithm can effectively solve multi-flexible integrated scheduling problem with setup times,and can also solve flexible integrated scheduling problem well.