Study On Digital Twins Modeling And Management Control Techniques For Manufacturing Cell

With the acceleration of the process of economic globalization and the intensification of the international market competition environment,the market demand with personalization as the main feature requires enterprises to have higher flexibility in their production systems.At the same time,the Cyber-Physical System with new information and communication technology as the core enables more distributed and enhanced intelligent features of manufacturing resources,realizes the decoupling of manufacturing resources,and reduces the rigidity of the production system.The manufacturing unit is the smallest granularity unit of the production system in the CPS environment.Studying its modeling and control issues is of great significance for improving the flexibility of the production system in the CPS environment and supporting the realization of the production system functions.Digital twins is an effective method and a new technology to realize the fusion of Information and physics.Because of its characteristics of simulation and virtual-real mapping,it not only provides a virtual hardware test environment for the development and validation of manufacturing cell management and control system,but also provides a new mode for off-line simulation and real-time operation management of manufacturing system.Therefore,this thesis puts forward higher requirements for the flexibility of production system according to the market demand of customization.Based on the higher flexibility of CPS enabling production system and other functions and characteristics,the discrete manufacturing cell under CPS environment is taken as the research object,and the modeling and control of manufacturing cell is taken as the research starting point,based on the characteristics of virtual-real mapping and simulation of digital twins,the modeling and control technology of manufacturing cell driven by digital twins is studied.The main research contents are as follows:(1)On the basis of studying and summarizing the current research situation at home and abroad,combining the function characteristics of CPS and digital twins,the connotation,characteristics,functions and resources composition of manufacturing cell based on digital twins are defined,and its management and control architecture is constructed,design its operating mechanism,to provide the overall support for the followup research content.(2)According to the modeling specifications of digital twins,focusing on the requirements of the operation and control scenarios of manufacturing units,the thesis use modeling theories and methods such as related ontologies and hybrid Petri nets to focus on the construction of digital twins single-view models such as the resource structure and control behavior of manufacturing units.Furthermore,on the basis of integrating the geometric and physical models of the manufacturing cell,a multi-view integrated modeling method for manufacturing cell based on digital twins is proposed.And based on the definition of multi-view Model Coordination Mechanism,the digital twins model of manufacturing cell is constructed,which provides model support for the research of digital twin-driven manufacturing cell management and control technology.(3)According to the different time-effectiveness requirements of manufacturing cell management and control,combined with the virtual-real synchronization and off-line simulation characteristics of digital twins,based on the design of the overall management and control index system of manufacturing cell,and based on the digital twins model of manufacturing cell,the management and control requirements of visual real-time monitoring and abnormal production diagnosis are studied.Among them,around the visual real-time monitoring target,based on the research of key technologies such as resource identification and collection,virtual-real mapping and communication of digital twin manufacturing cells,the visual real-time monitoring model of digital twin manufacturing cell is built to support the real-time monitoring demand of manufacturing cell,and then the virtual-real synchronization of digital twins is highlighted;Secondly,focusing on the needs of abnormal diagnosis and the focus of management and control,focusing on equipment management and control,on the basis of building a fault tree of manufacturing units and an expert knowledge system for abnormal diagnosis,the research on digital twin manufacturing unit production abnormality diagnosis and feedback control method based on knowledge reasoning is studied to highlight the offline simulation characteristics of the digital twins.(4)Combined with the above research results,based on completing the development and verification environment construction,the prototype system was developed and verified from the aspects of system operation flow design,digital twin model construction,integrated management and control scene development,and simulation.Through the above research,it is possible to prove the rationality and effectiveness of the digital twins in changing the control mode of the manufacturing unit under the CPS environment and improving the management and control capability of the manufacturing unit.It is hoped that the method proposed in this thesis can provide research cases and reference basis for the application research of digital twins in the management and control of manufacturing cells and production systems.