# Design and Application of Logical Range Framework Based on Digital Twin
## 2 Logical Range Framework Based on Digital Twin  
According to the flight test task process and the requirements of the Logical Range virtual test, the idea of hierarchical development is adopted to construct the Logical Range framework based on digital twin technology, which is divided into a physical layer, data layer, virtual layer, service layer, and implementation layer, as depicted in Figure 1. In Figure 1, it can be seen that in order to meet the dynamic expansion of equipment and data communication requirements during cross-regional flight tests, a proxy has been introduced into our framework, which can connect hardware equipment and software systems to meet the dynamic expansion and data communication needs of the equipment. This part of the content will be detailed in subsequent chapters. 1. _Physical Layer_ As the basis of the whole framework, the physical layer is divided into an equipment layer (\(E_{l}\)), range layer (\(R_{l}\)), and test layer (\(T_{l}\)), according to the application scenario and functional structure. The relationship between these layers is as follows: \[E_{l}\subset R_{l}\subset T_{l}.\] (1) The equipment layer can be regarded as the basis of the physical layer, which is composed of theodolite, high-speed camera, radar, and GPS (Global Positioning System) equipment, along with the other equipment and test resources distributed in each range. The range layer consists of ranges distributed in different regions. As a complex of test resources, the range is also the basic unit of the flight test process. The test layer consists of different test schemes. The test scheme includes all the supporting resources and information needed for a test, usually consisting of one or more ranges. 2. _Data Layer_ Data play a crucial role in the whole system. Data flow between different parts of the system drives the operation of the whole system. The data in the data layer are mainly composed of physical layer data, virtual layer data, and service layer data. The physical layer data are mainly composed of static data and dynamic data. Static data include equipment information, geometric parameters, and so on. Dynamic data are the data collected and generated by the equipment during operation. The data of the virtual layer are mainly composed of the data model, geometric model, behavioral model, and data generated by the virtual twin scene. The real-time data and historical data collected and generated during the operation of each model and scene in the virtual layer are part of the virtual layer data. The data of the service layer are composed of the data generated by each functional module in the service layer during operation, including the source data obtained from different databases and the data generated by various calculations in the service layer. 3. _Virtual Layer_  
As the \"twin\" of the physical layer, the virtual layer is an indispensable part of the system. The virtual layer is mainly composed of a data model (\(D_{m}\)), geometric model (\(G_{m}\)), behavior model (\(B_{m}\)), and virtual twin scene (\(V_{s}\)). The relationship between them is given as follows:  
\[((D_{m}\subset G_{m}),B_{m})\subset V_{s}. \tag{2}\]  
Figure 1: Logical Range Framework based on digital twin. The data model is constructed from static data in the data layer, providing data support for the geometric model. The geometric model, supported by the data model, describes geometric information such as the appearance, structure, and size of various types of equipment and ranges. The behavior model is driven by dynamic data, through the script file, in order to achieve real-time data matching. The virtual twin scene is a virtual scene constructed under the joint action of the three models mentioned above, which can logically restore the Logical Range with high fidelity. 4. _Service Layer_ The service layer implements its corresponding functions based on the drivers of the data layer.