Research On Robust Scheduling Of Flexible Job Shop In M Company

The efficient workshop scheduling can improve the utilization of production equipment,shorten the production cycle and reduce the production cost.Therefore,more and more scholars and enterprises are paying attention to the scheduling problem of workshop production.With the rapid change of the social demand,the production cycle of the product is shortened,and the delivery time of the product is becoming more and more strict.The manufacturing industry is developing towards the multi variety and small batch direction.The fast response and on time delivery capability have become the core competitiveness of the enterprise.Job shop scheduling and robust scheduling in flexible job shop are more in line with the actual production environment requirements,thus becoming an important research direction of job shop scheduling.The mechanical workshops of M company are flexible workshops under the model of multi variety and small batch production.At present,the manual scheduling scheme is still adopted,which not only leads to the long processing cycle of the workshop,but also has a large deviation between the actual completion time and the plan,leading to the increase of production cost and weaking the quick response and on time delivery capability of the company directly.Robustness is an important indicator of job shop scheduling,which reflects the deviation between the actual scheduling results and scheduling plans.We always hope that this deviation is as small as possible,which is of great significance to reducing production costs and improving punctual delivery rate.Therefore,the goal of this thesis is to shorten the processing cycle of M machinery processing workshop and improve the robustness of scheduling plan.Firstly,this thesis review the domestic and foreign research status of the flexible job shop lotsplitting scheduling problem and the flexible job shop robust scheduling problem.Secondly,This thesis aims to reduce the processing cycle and improve the robustness of the scheduling plan in M company.The main work of this paper is as follows:1)The current situation of the scheduling in the machine shop of M company is analyzed and the existing problems in the workshop scheduling is summarized.On this basis,the scheduling model of the mechanical workshops of M company is built-the multi target flexible job shop batch robust scheduling model.In the model,the batch startup time and machine failure are taken into account to improve the robustness of the scheduling.According to the actual scheduling requirements,the corresponding processing cycle index and robustness index are designed as the optimization objectives of the model.2)The step solving strategy is choosed to solve the model: first,the effective batch strategy is designed to optimize the batch,and then the scheduling sub batches are optimized on the basis of the batch.3)The scheduling model constructed in this paper optimizes both the processing cycle index and robustness index,which is a class of multi-objective optimization problems.Therefore,based on the basic framework of the multi-objective optimization genetic algorithm NRGA,the algorithm is designed.Because the batch startup time is considered in the model,the decoding strategy considering batch startup time is proposed in the process of solving genetic algorithm and the number of chromosome coding methods are designed.4)when the robust scheduling is solved,the robustness solving strategy based on machine fault simulation and the robust solution strategy based on idle time insertion are adopted to improve the robustness of the scheduling plan,and the scheduling results obtained by the two strategies are compared and analyzed.Finally,the actual production data of the machine workshop in M company are analyzed and arranged with the aid of MATLAB programming.The simulation results show that the study can effectively shorten the processing cycle of the workshop,and ensure the high robustness of the scheduling plan.On the basis of the study of this thesis,M company's ability to respond quickly and on time is improved.Moreover,the study of this paper can not only effectively solve the problem of job shop scheduling in M company,but also has a general reference to the problem of batch robust scheduling in the general flexible job shop.