Meenakshi Deshmukh

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.

Collaborative Development and Cataloging of Simulation and Calculation Models for Space Systems

The application of modeling and simulation in the design, development and validation process of complex systems has significantly increased in the last decades. Creating high quality models is a time-consuming task. Particularly, if models should be shared and reused in future projects. In this paper, results of the project Simulation Model Library (SimMoLib) are presented that address the issues concerning the preservation of knowledge that lies within simulation and calculation models. SimMoLib provides modeling guidelines and best practices to help the developer to prepare models that can be reused in other contexts. Validation and verification of these models is covered by proposing a set of guidelines and two test frameworks as well as by promoting peer reviews of models by other experts. To archive, catalogue, and distribute models, a software framework is under development which supports the creation, management, retrieval, and utilization of models. In order to allow the collaborative editing of calculation and simulation models a simplified version control mechanism is established. SimMoLib is currently targeted to support the development of space systems. In the future it will be opened to other domains.

Model driven language framework to automate command and data handling code generation

On-board computer software (OBSW) is an integral part of every space mission. It has been continuously growing in size and complexity. The insufficient level of automation in the development process of such software leads to low software re-usability and drives up the costs. This paper presents a generic approach to describe and model the on-board software in terms of data that is processed by it. Domain Specific Language (DSL) based framework is developed using which provides a DSL editor, a model validator, and a code generator. Using the framework, a system data model is created. The C++ code is generated from it which is then customized to implement low-level behavior. As a proof of concept, the telecommand handling functionality of OBSW is developed to prove the feasibility of applying the solution to the whole system. Based on the analysis conducted on the source code of the TET-1 satellite of the German Aerospace Center (DLR), a DSL is designed and implemented. The resulting DSL-based framework is tested with an example model and target code customization, showing its ease of use and proving that it behaves as expected.

Knowledge Management tools integration within DLR's concurrent engineering facility

The complexity of space endeavors has increased the need for Knowledge Management (KM) tools. The concept of KM involves not only the electronic storage of knowledge, but also the process of making this knowledge available, reusable and traceable. Establishing a KM concept within the Concurrent Engineering Facility (CEF) has been a research topic of the German Aerospace Centre (DLR). This paper presents the current KM tools of the CEF: the Software Platform for Organizing and Capturing Knowledge (S.P.O.C.K.), the data model Virtual Satellite (VirSat), and the Simulation Model Library (SimMoLib), and how their usage improved the Concurrent Engineering (CE) process. This paper also exposes the lessons learned from the introduction of KM practices into the CEF and elaborates a roadmap for the further development of KM in CE activities at DLR. The results of the application of the Knowledge Management tools have shown the potential of merging the three software platforms with their functionalities, as the next step towards the fully integration of KM practices into the CE process. VirSat will stay as the main software platform used within a CE study, and S.P.O.C.K. and SimMoLib will be integrated into VirSat. These tools will support the data model as a reference and documentation source, and as an access to simulation and calculation models. The use of KM tools in the CEF aims to become a basic practice during the CE process. The settlement of this practice will result in a much more extended knowledge and experience exchange within the Concurrent Engineering environment and, consequently, the outcome of the studies will comprise higher quality in the design of space systems.

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.

Model linking to improve visibility and reusability of models during space system development

The development of space systems involves complex interdisciplinary systems engineering. To manage such complexity, simulation and calculation models are becoming an integral part of it, where different domain-specific models (power, thermal, structure, propulsion, communication, etc.) are developed using different tools. Every domain model contains valuable knowledge of a respective discipline. However, creating such models takes an ample amount of time and efforts. Therefore, a common management for these models is needed to preserve the knowledge and to reuse them in future space missions. The project Simulation Model Library (SimMoLib) at the German Aerospace Center (DLR) develops guidelines and best practices regarding model development, model documentation, validation and verification, as well as model reviews to establish a collection of reusable models. To efficiently catalog the models, an innovative software system is created to support collaborative development, submission, archiving, review, search, and utilization of models. In SimMoLib, a model linking concept has been developed and implemented to enhance the model search and their probable reuse. Along with regular keyword-based search, a direct and an indirect linking between the models in the library has been implemented. Therefore, the model linking increases the visibility and consequently promotes the reuse of single and interdependent models within the library. The paper further describes different types of model relationships, categories, hierarchical levels of model development, implementation and presentation of model linking in detail.