Research On Dynamic Planning And Scheduling Method Of Assembly Shop Based On Petri Net

When the assembly workshop assembles the products according to the planning and scheduling scheme,there will be some uncertain factors such as failure of equipment,lack of material and flow of personnel.These uncertain factors will affect the accuracy of the planning and scheduling scheme,making the planning and scheduling scheme can not accurately guide the actual assembly,thus affecting the efficiency of the assembly workshop.In the traditional workshops,the planning and scheduling system of traditional workshops dealing with these uncertain factor,due to the incompleteness of management and control mechanisms,poor real-time capability of monitoring data,and low level of intelligence in scheduling,the uncertain factors in the assembly process cannot be immediate treatment.The emergence of digital twin technology provides an important direction for solving this problem.This paper integrate the digital twin technology with the planning and scheduling systems to form a comprehensive management and control mechanisms of the dynamic planning and scheduling system,and a dynamic planning and scheduling system for assembly workshop based on the Petri net is formed,which solves the problems of incompleteness of management and control mechanisms,poor real-time capability of monitoring data,and low level of intelligence in scheduling,so that the uncertainty factors in assembly can be monitored and processed in real time.In response to the incompleteness of management and control mechanisms,the management and control mechanisms of dynamic planning and scheduling system based on digital twin was formed.From before,during and after the assembly,the prediction technology,simulation technology and real-time data acquisition technology of all elements are considered comprehensively.Based on the prediction of all assembly elements,the simulation verification and consistency test of real-time data are used to achieve the purpose that the assembly plan can accurately guide the actual assembly.In response to the poor real-time capability of monitoring data,the active sensing method of planning and scheduling resources in assembly shop based on the Petri net model is studied.The Petri net model is used to describe the state and activity of the planning and scheduling resources,and the corresponding RFID equipment is configured according to the resource type.The Petri net model is stored in the RFID device for the interaction of the planning and scheduling resources,and the real-time data of the planning and scheduling resources are obtained through MES.In response to the low level of intelligence in scheduling,the dynamic planning and scheduling model for assembly workshop based on Petri net is built.The dynamic planning and scheduling system based on Petri net is analyzed to find the conditions for the discovery of uncertain factors and the correlation between uncertain factors and planning and scheduling schemes.The planning and scheduling model based on Petri net is established with the minimum penalty cost of assembly workshop as the goal.The enterprise of A is taken as an example.Firstly,the planning and scheduling system is optimized by using the idea of the management and control mechanisms of dynamic planning and scheduling system.Then,the real-time data of the planning and scheduling resources is obtained by using the CPN TOOLS simulation tool.Finally,on this basis,the dynamic planning and scheduling system of the vehicle frame plant with the scheduling model is built to conduct real-time monitoring and timely processing of uncertain factors in the vehicle frame plant.This has brought good economic benefits to the vehicle frame plant.