# A Categorization of Digital Twin and Model-Based System Engineering Interactions
## 3 Results
### Case Study
[37] presented the development of a digital process twin architecture and illustrated its application using a hypothetical manufacturing company. The authors used data collected from 100 actual machines to create the digital equipment twins. The main goal of the case study was to assist in the decision-making regarding machine repair and maintenance on a shop floor. However, the authors did not provide specific details about the implementation of the digital process twin but rather focused on presenting high-level results. It is important to note that these results were obtained through simulation, since the shop floor did not exist. [PERSON] et al. [17] provided an example use case using their Digital Twin Specification Grid. They detailed the motion monitoring of a robotic arm in a production environment. In this context, they proposed a DT for the motor, for the robot arm, and for the production. To model the grid, they adapted the diagrams.net software tool according to the method specification. As its focus was to help stakeholders to collectively specify the DT, the grid provided a high-abstraction view of the model, which omitted technical specifications. Finally, the authors also validated their method, tool, and language in a workshop with eight participants. In the domain of aerospace, [PERSON] et al. [27] used a Mars landing scenario to further explain their EDT proposal. The authors modeled the system using SysML diagrams; however, the ones presented were simplified in order to focus on the overall methodology. The researchers developed three distinct EDTs using MBSE, each designed for a specific purpose: one for the lander, one for the rover, and one for the Mars environment. They discussed how to simulate this network of EDTs and the benefits of adopting a virtual testbed (VTB) as the integrated simulation environment. The authors further noted that EDTs have been applied in various other fields, such as on-orbit servicing, forest machine localization, driver assistance systems, and industrial automation. [PERSON] et al. [28] provided details about the ice protection system DT described in their article. The system was modeled using IBM Rational Rhapsody, utilizing high-level SysML internal block diagrams. The system consisted of multiple blocks, each representing a different model, with the color of each block reflecting the type of content that it contained. These content types included Simulink, Dassault Systemes Dymola, and Modelica models; Rhapsody state machines; and combinations of models. Furthermore, each high-level block was further described using another internal block diagram. Although the specific modelsemployed in each block were not disclosed by the authors, the diagrams presented were sufficient to gain a thorough understanding of the proposal. They simulated the system in Dymola to compare two different configurations to solve the icing problem; one was electrical and the other pneumatic. They observed the evolution of the ice thickness and the power consumption in each configuration. [PERSON] et al. [30] implemented their DT concept in a design process for a virtual CubeSat mission. The authors broke down the overall system function into smaller functions that could be assigned to individual designers using the SysML block definition diagram. Interfaces between these functions were represented using SysML internal block diagrams. Subsequently, the functions were allocated to specific designers, although the specific diagram used for this allocation was not provided by the authors. The authors then simulated the modeled system, taking into account the assumptions that they defined. This allowed them to estimate the complexity and workload of the project and analyze the effects of any changes made. In their study, [PERSON] et al. [36] introduced the concept of a product family DT based on MBSE. They provided an illustrative example of an airplane DT to demonstrate this concept. They showed how a DT could be used to keep track of the physical changes of the plane.