# A Categorization of Digital Twin and Model-Based System Engineering Interactions
## 1 Introduction
The most well-known MBSE languages are the Unified Modeling Language (UML) and Systems Modeling Language (SysML). The tool is the software used for modeling; some examples include Cameo, Papyrus, and Capella. Each organization chooses to use the configuration that best caters to its needs [16]. MBSE emphasizes the use of models as central artifacts, allowing engineers, designers, and analysts to capture and analyze complex system behaviors, interactions, and dependencies. It can be inferred that the MBSE models developed to describe the system are a digital representation of it. In some works, the MBSE model is considered the authoritative source of truth for the system [18]. In the MBSE system verification and validation step, it is common to simulate the model to check for design errors, evaluate the early viability of the system, and demonstrate the outputs and outcomes of the use cases [14]. The intrinsic similarities and synergies between digital twins and MBSE have led to increasing interest in their integration. For instance, [PERSON] and [PERSON] [19] advocated for an MBSE-enabled DT to enhance system interconnectivity and streamline the optimization process, while also briefly reviewing the relevant literature on the subject. [PERSON] et al. [20] explored the application of MBSE to facilitate model integration in a DT context throughout the system life cycle for an application framework and conceptual architecture, implemented on an auto-braking system. [PERSON] et al. [21] introduced a DT-enabled MBSE research testbed designed to prototype and evaluate aerospace systems. They argued that an MBSE testbed expands on the conventional hardware-in-the-loop testbeds by including abstract models that may or may not interact with the hardware-in-the-loop, therefore supporting integration with DTs. [PERSON] et al. [22] proposed an MBSE-based DT engineering framework for production manufacturing systems. They distinguished the development of the digital twin according to two scenarios: one for when the physical entity is being designed and another for when it is in operation. These examples illustrate various interactions between DTs and MBSE. However, a systematic focus on these interactions is noticeably absent in the literature. Consequently, this article aims to address the following research questions:  
* How can DT and MBSE interact? * Can these interactions be categorized? In the context of system of systems engineering (SoSE), integrating DTs with MBSE presents a promising method for the management of complex, interconnected systems. SoSE involves large-scale systems composed of multiple autonomous but interrelated subsystems, each with its own goals and processes. Understanding the different interactions between MBSE and DTs is essential in enhancing system capabilities, managing interdependencies, and ensuring the dynamic collaboration of subsystems. In this study, a methodology for the selection of a representative set of articles on the research topic is proposed and utilized to curate a database of articles for analysis. This analysis categorizes the types of DT-MBSE interactions. Finally, a case study of the Perception system, which is a satellite data collection system, illustrates one of the categories.