A SysML-based language for evaluating the integrity of simulation and physical embodiments of Cyber–Physical systems

Evaluating early design concepts is crucial as it impacts quality and cost. This process is often hindered by vague and uncertain design information. This article introduces the SysML-based Simulated-Physical Systems Modeling Language (SPSysML). It is a Domain-Specification Language for evaluating component reusability in Cyber-Physical Systems incorporating Digital Twins and other simulated parts. The proposed factors assess the design quantitatively. SPSysML uses a requirement-based system structuring method to couple simulated and physical parts with requirements. SPSysML-based systems incorporate DTs that perceive exogenous actions in the simulated world. SPSysML validation is survey- and application-based. First, we develop a robotic system for an assisted living project. We propose an SPSysML application procedure called SPSysAP that manages the considered system development by evaluating the system designs with the proposed quantitative factors. As a result of the SPSysML application, we observed an integrity improvement between the simulated and physical parts of the system. Thus, more system components are shared between the simulated and physical setups. The system was deployed on the physical robot and two simulators based on ROS and ROS2. Additionally, we share a questionnaire for SPSysML assessment. The feedback that we already received is published in this article. • Goal : We aim to improve the integration between simulated and physical parts of CPS in various system setups, resulting in controlling the simulated and real hardware with a shared controller. We propose an integrity evaluation method between the simulated and physical embodiments of the system. The assessment is done in various scopes, e.g. per pair of Digital Twins (DT) and its physical counterpart— Physical Twin (PT), system-wide, or one of many system setups. • Method : We propose a Domain-Specific Language based on Systems Modeling Language (SysML). The Simulated-Physical Systems Modeling Language (SPSysML) defines the taxonomy of considered CPS consisting of at least a physical or simulated part. Based on SPSysML concepts, we define quantitative factors and a requirement-based system structuring method, which enhances requirement analysis and allows DT to perceive exogenous actions in the simulated world. We propose an application procedure called SPSysAP that manages the considered systems development by evaluating the system designs with the proposed quantitative factors. • Result : SPSysML is used to develop a robotic system for the INCARE project. In subsequent iterations of the system’s design process, the simulated-physical integrity of the system is improved, and a more significant fraction of the system components is shared between its simulated and physical embodiments. The designed system was deployed on the physical robot and two simulators. System setups are based on Robot Operating System (ROS) or ROS2. Therefore, we argue that SPSysML is neither specific for a control system framework nor a robot simulator. SPSysML was used by a third-party developer and was assessed by him and other practitioners in a survey. • Conclusion : SPSysML with SPSysAP enables the design of SPSys (including DT and CPS) and evaluating the design in their multi-setup system development. The system features improved integrity between simulated and physical parts in its setups. The proposed systematic requirement-based system structuring also enhances the traceability of system requirements allocation to simulated and physical system parts.