Philipp M. Fischer

Open source software framework for applications in aeronautics and space

The DLR developed the open source software framework RCE to support the collaborative and distributed work in the shipyard industry. From a technology side of view a software from the shipbuilding field has many requirements in common with aerospace software projects. Accordingly, RCE has become the basis for further projects within the DLR. Over the last years of usage a subset of frequently used software components could be derived and are provided by the RCE framework. In particular, the workflow engine, allowing the integration of different domain-specific tools from local and remote locations into one overall calculation has become important for various projects. We present RCE and show how its software components are reused in two aerospace applications.

Decision Support Tool for Concurrent Engineering in Space Mission Design

The concurrent engineering (CE) approach has been successfully applied to the early design phase of space missions. During CE sessions, a software support is needed to allow multidisciplinary design data exchange. At the moment, a spreadsheet-based solution enhanced with macros is used at the German Aerospace Center (DLR) to create a system model of a space mission during the early design phase. Now there is an increasing demand to take advantage of this system model and provide data analysis features which improve the decision making during CE sessions. Since the current approach is limited for such analysis, DLR has started developing a new tool called Virtual Satellite. It offers extended software support required by the Concurrent Engineering Facility of DLR in Bremen. On top of the previous spreadsheet functionalities, it provides means for online data analysis and system modeling. The results of these data analyses are presented to the discipline experts using different views which help in performing an early design optimization. In this paper, the impact of these views on the decision making during the AEGIS space mission study is presented as a proof of concept.

A Continuous Verification Process in Concurrent Engineering

This paper presents how a continuous mission verification process similar than in software engineering can be applied in early spacecraft design and Concurrent Engineering. Following the Model-based Systems Engineering paradigm, all engineers contribute to one single centralized data model of the system. The data model is enriched with some extra information to create an executable representation of the spacecraft and its mission. That executable scenario allows for verifications against requirements that have been formalized using appropriate techniques from the field of formal verification. The paper focuses on a current approach of integrating this verification mechanism into our Concurrent Engineering environment. In an example study, we explain how basic mission requirements are created at the beginning of the spacecraft design. After each iteration and change, the integrated verification will be executed. This instantly highlights the effects of the modification and points out potential problems in the design. Using the continuous verification process alongside the Concurrent Engineering process helps to mature both, the requirements and the design itself.

A formal method for early spacecraft design verification

In the early design phase of a spacecraft, various aspects of the system under development are described and modeled using parameters such as masses, power consumption or data rates. In particular power and data parameters are special since their values can change depending on the spacecrafts operational mode. These mode-dependent parameters can be easily verified to static requirements like a maximumdata rate. Such quick verifications allow the engineers to check the design after every change they apply. In contrast, requirements concerning the mission lifetime such as the amount of downlinked data during the whole mission, demands a more complex procedure. We propose an executable model together with a simulation framework to evaluate complex mission scenarios. In conjunction with a formalized specification of mission requirements it allows a quick verification by means of formal methods.

Collaborative satellite configuration supported by interactive visualization

Planning a spacecraft requires the expert knowledge from diverse disciplines, such as propulsion or structure. Reliable communication between the experts is crucial, as the individual requirements of a satellites various subsystems heavily depend on each other. Today, early mission design sessions are often held in specially designed rooms, so-called concurrent engineering facilities. Here, the experts come together and directly discuss with each other in a shared place, enabling them to find a common ground much quicker. Nevertheless, in certain aspects it remains difficult for the experts to share and describe their knowledge within the team. In particular for configuration purposes it is a hurdle to verbally discuss positions and orientations of different parts. We propose a new approach of using shared interactive visualization for the configuration task, which enables every engineer to individually place parts and to alter it in case of discrepancies.

Conceptual data model: A foundation for successful concurrent engineering

Today, phase A studies of future space systems are often conducted in special design facilities such as the Concurrent Engineering Facility at the German Aerospace Center (DLR). Within these facilities, the studies are performed following a defined process making use of a data model for information exchange. Quite often it remains unclear what exactly such a data model is and how it is implemented and applied. Nowadays, such a data model is usually a software using a formal specification describing its capabilities within a so-called meta-model. This meta-model, often referred as conceptual data model, is finally used and instantiated as system model during these concurrent engineering studies. Such software also provides a user interface for instantiating and sharing the system model within the design team and it provides capabilities to analyze the system model on the fly. This is possible due to the semantics of the underlying conceptual data model creating a common language used to exchange and process design information. This article explains the implementation of the data model at DLR and shows information how it is applied in the concurrent engineering process of the Concurrent Engineering Facility. It highlights important aspects concerning the modeling capabilities during a study and discusses how they can be implemented into a corresponding conceptual data model. Accordingly, the article presents important aspects such as rights management and data consistency and the implications of them to the software’s underlying technology. A special use case of the data model is depicted and shows the flexibility of the implementation proven by a study of a multi-module space station.

Systematic reuse and platforming: Application examples for enhancing reuse with model-based systems engineering methods in space systems development

Despite popular belief, space missions are not always one-of-a-kind, but are frequently benefiting from explicit or implicit reuse of different types. The Venus Express mission is one example of cost savings by reusing existing hardware in a new mission context. Other examples are based on the platform approach, popular, for example, in geostationary telecommunication satellites, which benefits from a pre-planned reuse and its application to a family of missions with commonality. While the latter is handled more strategically, promising more gain in its execution, the Venus Express example is more of an ad hoc nature. Given the increasing importance of design reuse, the practical question to be answered in this article is how to promote it using effective engineering methods and processes. Model-based systems engineering often advertises itself as especially beneficial to reuse projects and we provide a systematic review of the respective capabilities in this article. Furthermore, we describe two reuse application examples: an asteroid nanolander based on the Mobile Asteroid Surface Scout lander currently flying onboard Hayabusa2 and a Small Satellite Platform for Earth science missions. With Mobile Asteroid Surface Scout’s heritage generating strong interest for future small body missions, this creates a case for what we call ad hoc reuse. Conversely, the Small Satellite Technology Platform, which is currently in its definition phase, can be classified as systematic reuse case with the aim of developing a commonality-based small satellite family, suitable for a set of rapidly recurring missions in low Earth orbit. Our study of the Mobile Asteroid Surface Scout-2 reuse case has provided insights into reuse requirements, which are mapped to typical model-based systems engineering features that create value beyond those offered by classical approaches. The article identifies key areas where model-based systems engineering provides benefits in reuse cases: requirements reuse, system context analysis as well as interface compatibility checking. It further outlines an overall approach regarding tools and development processes.