## 3 Architecture of DT Workshop System
### Design of DT Workshop Architecture Based on Five-Dimensional Model
All data are uniformly stored in the data warehouse within this layer, and the logical model serves as the control core to integrate the DT model with the actual data, providing a unified description and encapsulation of geometric properties, physical properties, operational behaviors, and simulation rules for each production-related physical entity. When instantiated virtual objects receive iterative data updates, their information updates can be quickly completed in the logical model. The service drive layer of DT data support can be expressed as follows:  
\[\mathbf{DD}=(\mathbf{D}_{PE},\mathbf{D}_{VO},\mathbf{D}_{AS},\mathbf{D}_{K},\mathbf{D}_{\Delta})^{ \mathrm{T}} \tag{6}\]  
where \(\mathbf{D}_{PE}\) represents the physical workshop's actual measurement data, \(\mathbf{D}_{VO}\) is the virtual object simulation data, \(\mathbf{D}_{AS}\) means the application service output data, \(\mathbf{D}_{K}\) represents the process knowledge base data, and \(\mathbf{D}_{\Delta}\) represents the data fusion-derived data. * Application Service Layer  
This layer supports the operation and maintenance of digital twin system applications. Based on the twin data and service drive layer, it is oriented to the workshop planning, work time, progress, resources, quality, storage, and energy control needs, extracting critical data in the logic model and supporting the realization of decision support functions. Intelligent workshop managers and workers can access application services through multiple clients. Taking the specific business of the welding workshop as an example, the application service provides block assembly and welding scheduling optimization, welding work time forecasting, steel resource demand analysis, sub-section quality traceability, storage availability analysis, logistics consolidation and distribution, energy consumption analysis, and other intelligent algorithm solutions. In the future, functions such as the welding process knowledge base and high-precision control of workshop equipment can be further expanded. The application services can be expressed as follows:  
\[\mathbf{AS}=\ (\mathbf{S}_{Scheduling},\mathbf{S}_{Workhours},\mathbf{S}_{Resources},\cdots)^{ \mathrm{T}} \tag{7}\]  
where \(\mathbf{S}_{*}\) means the data set corresponding to each service. * Digital Twin Display Layer Visualization of system functions is the significant feature of this layer, which is the only layer that the users of the digital twin system visualize. The application module proceeds from the simulation model of the virtual workshop and enters the business module by selecting the workshop components. The business module displays the functional indicators of the workshop and the product information based on the data analysis results of the application service layer, specifically including the decision board, data analysis reports, the product DT simulation, workshop monitoring, etc. The functionalities of the digital twin display layer are realized entirely based on the integrity data of the virtual objects, whose vectorized form is:  
\[\mathbf{M}_{DT\_workshop}=(\mathbf{PE},\mathbf{VO},\mathbf{DD},\mathbf{CN},\mathbf{AS})^{\rm T} \tag{1}\]0  
where \(\mathbf{G}_{VO}\) corresponds to the geometric model, \(\mathbf{P}_{VO}\) is the set of physical attributes, \(\mathbf{B}_{VO}\) means the quantitative representation of the operational behavior, and \(\mathbf{R}_{VO}\) represents the rule model. In a nutshell, the demand-oriented digital twin workshop architecture is based on the theory of the five-dimensional model, which is theoretically feasible and practically usable and sufficiently satisfies all elements of workshop production control. It realizes the comprehensive digital in the whole cycle of assembly and welding operation. With the logical model as the core and all production elements interlinked, the five-layer architecture materializes the iterative cycle of \"DT data simulation guidance--actual measurement data optimization\" based on the data chain.