The future of model based systems engineering for space missions.
Virtual Satellite is an internal DLR project that started in 2007. As its name suggests, the initial focus was on supporting spacecraft assembly, integration and test (AIT) activities with a digital mockup and simulation. Quite soon the project focus shifted from AIT to the early phases in the life of a spacecraft, to the Concurrent Engineering Facility (CEF) in. Here spacecraft and their missions are born and therefore a smart tool was needed that lets the engineers collaboratively work on a shared digital representation of the spacecraft. Enabling collaboration is one of the key features of Virtual Satellite.
Continues evolution and integration of the Virtual Satellite software family builds the backbone of DLR’s MBSE activities. Here the latest research results are evaluated, implemented and shipped to the projects. The Virtual Satellite Family contains the Versions 3 and 4, some of the best and most advanced tools to support the design, development and production of tomorrow’s spacecraft. Most tools are based on the Eclipse Rich Client Platform (RCP) and are written in Java within a state of the art software engineering environment.
Virtual Satellite 3 mainly supports the work at CEF. It was developed to improve collaboration during the design studies and to allow the engineers to create a common digital mock-up of their spacecraft. It introduces a simple data model that is tailored to the needs of the engineers and that perfectly fits the way CEF studies are conducted. Even quite simple, it follows the paradigm of letting the engineers be creative. Virtual Satellite is easy to use and does not distract the engineers from their original task of designing a spacecraft. Besides the day by day business in the CEF, Virtual Satellite 3 has also levered some pioneering new directions such as continuous verification or visual spacecraft configuration approaches. The software has been developed in close cooperation with the department for System Analysis Space Segment. We opened it up to the community and it is available for download free of charge.
A flexible and extensible data model
Virtual Satellite 4 is the new evolution and rebuilt platform. With a customizable data model it can be tailored to the various needs of individual engineering tasks and project requirements. Rather than the historic approach of trying to create the data model and system engineering language that can handle all possible tasks, the new approach focuses on necessities leading to simple and easy to use applications. The data model of a Virtual Satellite 4 application can be extended by a concept. It can be downloaded from a concept store and activated when needed. Such a concept is a set of data model extensions plus functionality to provide corresponding user interfaces and further functionality. All this together with this concept-based extension mechanism offers Virtual Satellite 4 in three product lines:
- “Virtual Satellite 4 Core” as the baseline product. It provides all you need to start designing your system. Further functionality needed can either be downloaded from the concept store or implemented by your experts using the Virtual Satellite Development Tools. They offer a domain specific language (DSL) to easily describe your data model extension. Code generators will use that description to offer you an initial up and running implementation to start working with your extension.
- “Virtual Satellite 4 Research”, based on Virtual Satellite Core. PhD students build their own individual applications with their proof of concepts. It is the playground and the sandbox for experiments, which is detached from the productive applications and systems. Here failures and crashes don’t harm the productive systems and open up the space for experiments and scientific output.
- The projects “Powered by Virtual Satellite 4”. These are the custom made applications such as the one for our internal project S2tep. Here functionality is tailored closely to the demands of the project. More details on how we use Virtual Satellite 4 to support S2tep project are in this publication (Publication).
The research platform
The project Virtual Satellite is the foundation for our research activities in the whole frame of system engineering activities along the whole lifecycle of a spacecraft. Results of this research are directly fed back into the software implementations. The platform approach allowed questioning new ways of working in the area of Model Based Systems Engineering (MBSE). Some of these research activities are:
- Modeling Methods – Even though the classical modelling languages like UML and SysML are great approaches for system engineering, we discovered that they have certain limitations. Still, we use them as a baseline and we raise questions where we can’t apply them as desired. This brought us, for example, to questions of Multilevel Modeling. And even with the commonly agreed syntax of languages such as UML and SysML we have to question the semantical and ontological meaning when designing spacecraft. We don’t yet have all the needed answers here, but it points to the direction of our future research.
- Formal Verification – Having a digital mockup is commonly agreed to be a good thing. In the past these models were often created for the sake of having a digital representation. Today they are used more and more to understand and verify the system in an early stage before things get actually built. Quite often this is achieved by system simulation, but there are other ways as well. Trying to formalize the system in a mathematical way opens the door to rigorous proving of certain system properties. Accordingly, this gives confidence that the system will behave as expected in any case, not just in a limited set of simulated scenarios.
- Model Interaction – By today most system engineering tools use classical UML-style diagrams to create and define the models. In the frame of Virtual Satellite we try to include new technologies into modeling activities. For example, interactive 3D visualization has already highlighted some new ways of creating and discussing spacecraft design (Publication). On top of that, thinking about smart devices, mobile applications, speech recognition and new virtual reality (VR) gear, they promise additional value for future mission planning.
By today Virtual Satellite already supports the digitalization of the whole lifecycle of a spacecraft mission. Our goal is to evolve Virtual Satellite into the best and most advanced MBSE application to support space missions. Virtual Satellite is one of the key assets turning the digitalization of Industry 4.0 into reality.
Virtual Satellite is a DLR open source software for model based systems engineering MBSE. One of the major features of Virtual Satellite is the modular data model, that can be easily customized to your personal needs. Today, there are already various different versions:
- Virtual Satellite 4 - Core is the entry point to start developing and the basis for all other versions
- Virtual Satellite 4 - CEF is a specialized version for the use in our Concurrent Engineering Facility
- Virtual Satellite 4 - FDIR is a research version for Failure Detection, Isolation and Recovery
- Virtual Satellite 4 - DEV IDE is a spezial Eclipse IDE for easy and fast VIrtual Satellite development.
This project contains the deployed artefacts from the Virtual Satellite Eco-System. Donwnloads for Virtual Satellite 4 Core are also provided.
The artefacts contain p2 builds for:
- Daily development builds
- Regular integration builds
- Specific release builds