## 4 Design, Manufacturing and O&M Integration Mode of Complex Product Based on Digital Twin
### Operation Mechanism of Design, Manufacturing and O&M Integration  
The design, manufacturing and O&M integration of an operation mechanism driven by a digital twin is shown in Figure 3. The whole design, manufacturing and O&M process is interconnected and comprises the integration of a virtual model in addition to the traditional design, manufacturing and O&M to form the intact design, manufacturing and O&M digital twin body. Before design, the corresponding demands and functions are analyzed for the comprehensive design of the product, and the corresponding product 3D model is established based on the integrated design data. At the virtual layer, the model is analyzed to verify whether the model keeps consistent with design data. In the case of inconsistency, the system shall readjust the model parameters till consistency. These data are transmitted to the manufacturing department to formulate the intact production  
Figure 2: Digital-twin-based complex product design, manufacturing and O&M integration development process.  
plan. In addition to the design data, the workshop sensor data, abnormal production prediction data, etc., derived from fusion data, shall be collected. The corresponding production plan is generated, and the resource allocation is carried out in the planning and scheduling system based on those data. The virtual workshop shall be verified before actual production to find potential problems. In case of inconsistency, the production plan shall be amended till the potential conflict does not exist. At this time, the production plan data after amendment are issued to the production workshop to guide the actual processing and manufacturing of the whole workshop.  
Once the real-time status of the workshop changes in the actual production process, the amendment suggestions could still be returned to the production plan system. The finished products after production will be monitored in real-time by the O&M service system in  
Figure 3: Design, manufacturing, O&M integrated operation mechanism driven by digital twin.  
the operation process. The O&M service system predicts the fault occurrence as per the historical operation data. If there is a fault as predicted, the O&M service system shall carry out the O&M configuration, formulate the O&M plan as per the internal algorithm, and promptly issue the O&M plan to the virtual O&M space for O&M simulation. If the O&M plan contains conflict, the O&M plan will be corrected till the normal virtual O&M. Such plan is stored in the data platform. Once the fault occurs, the O&M plan is directly acquired for repair. The normal operation data are saved in the historical database and uploaded to the data platform for data fusion in order to provide an intact data basis for the normal operation of each part.  
The whole operation process saves the physical, virtual, and interactive data in the twin data platform. Then the twin data platform integrates, analyzes and digs the data and feeds the data back to each stage so that there is the corresponding virtual mapping in digital space at all stages to form the intact digital twin body of a complex product. The product's design, manufacturing and O&M stage are associated, and the product is continuously optimized and improved at each stage via virtual mapping and interaction at each stage.