## 3 OPC UA-Based VR/AR Collaboration Model
### VR Engineering Process  
The system maps the real-time values of the existing CPS server Address Space to the AR Object in the manner shown in Figure 3. The existing collaboration system has focused on object recognition and VR matching using VR/AR technology alone, and it only raises the actual value of AR through some data interfaces. Overseas, only PTC products receive actual data through Kepware's CPS Server. Figure 3 shows that rendering is possible through 3D design files by exchanging data through the CPS server to which OPC UA, an international standard technology, is applied. CPS maps from OPC UA Server to Address Space to exchange equipment information in real time without delay. As a central address space, the CPS system is built from multiple OPC UA Servers in the field as one huge central address space, and with one connection, the entire factory information can be mapped to the product inspection system in real time without delay. Figure 2: VR/AR collaborative model. The existing CPS played the role of collecting data from all equipment in the plant. In addition to the existing role, the proposed CPS plays a role of linking data to the 3D model through the OPC UA protocol. CPS performs the role of middleware including object information and value of the 3D model object delivered to the rendering server by applying technology based on the OPC UA Framework, which is an international table. The data stored in the CPS is utilized not only in the 3D model but also in the rendering server. In addition to communication, with computational control as the core concept, the physical world objects that coexist with humans and objects such as sensors, actuators, and embedded systems are fused into the cyber world, and the data communicated with the simulator are calculated and the results are redistributed. Using the OPC UA specification of international industrial standards, the system is constructed as depicted in Figure 4, with the smart factory optimized and both OPC UA modeling and CPS Node modeling connected with technological convergence with CPS. It converts CAD 3D binary files such as Solidworks into OPC UA Address Space data. If Edge is needed, data are collected from simulators, real machines, robots, etc., and data are delivered to CPS. Figure 4: System architecture of VR engineering. Figure 3: OPC UA information space of VR engineering. The design file is treated to the modeling and separation conversion of the design file, and the process proceeds as depicted in Figure 5. The CAD Data Import Interface provides an interface that allows designers to insert CAD data into applications and reads CAD Data Interface to VR Parser and converts it into 3D objects. For visualization, if a designer places 3D objects to collaborate and then performs virtual collaboration space work, CAD models are input to create virtual space objects through a 3D Converter, and designers can freely assemble and decompose objects in virtual space. It is also possible to easily create a virtual collaboration space so that it can be displayed to collaborators. Further, as shown in Figure 6, the contents of the BOM are referred to the relevant Node in the Address Space of the CPS server through extraction of the BOM from CAD or migration from legacy DB to enhance the functionality of the physical engine based on the BOM. Simulator advancements can be achieved with physical engine and Address Space. For the basic process of design management, all changes to the design for each stage are recorded in the DB, and then the rendering server lists the version history by referring to the DB. A blueprint for each stage of each VR/AR version can be recalled. It is possible to manage the version of each design level and real-time management of changes to each VR/R-based design. Products produced through VR collaboration design can be inspected using AR technology. When selecting a part list, the presence or absence of the relevant part, specifications, etc., are displayed to check for abnormalities.