Résumé

@inproceedings{Prat2021,

title = {The BECCAL Experiment Design and Control Software},

author = { Arnau Prat and Jan Sommer and Ayush Mani Nepal and Tobias Franz and Hauke Müntinga and Andreas Gerndt and Daniel Lüdtke},

year  = {2021},

date = {2021-03-06},

booktitle = {IEEE Aerospace Conference, Virtual Event, March 6-20, 2021},

publisher = {IEEE},

keywords = {},

pubstate = {published},

tppubtype = {inproceedings}

}

@inproceedings{Azeem2021,

title = {A Constraints-based Interaction System for Spacecraft Design in Augmented Reality},

author = { Syed Muhammad Azeem and Krishnan Chandran and Georgia Albuquerque and Frank Steinicke and Andreas Gerndt},

year  = {2021},

date = {2021-03-06},

booktitle = {IEEE Aerospace Conference, Virtual Event, March 6-20, 2021},

publisher = {IEEE},

keywords = {},

pubstate = {published},

tppubtype = {inproceedings}

}

@inproceedings{Nepal2020,

title = {Modeling and Simulation of a Spacecraft Payload Hardware Using Machine Learning Techniques},

author = { Ayush Mani Nepal and Arnau Prat i Sala and Kilian Johann Höflinger and Andreas Gerndt and Daniel Lüdtke},

url = {https://elib.dlr.de/137571/},

doi = {10.2514/6.2020-4219},

year  = {2020},

date = {2020-11-16},

booktitle = {Accelerating Space Commerce, Exploration, and New Discovery Conference, ASCEND 2020, Virtual Event, Nov. 16-18, 2020},

publisher = {American Institute of Aeronautics and Astronautics (AIAA)},

abstract = {Space systems are complex and consist of multiple subsystems. Research and development teams of such complex systems are usually distributed among various institutions and space agencies. This affects the quality of the On-board Software (OBSW) since testing it without having all required subsystems at the software development site can be troublesome. In this paper, we present a data-driven method which can be used to synthesize parts of a system or even an entire system as a black-box model. We exploit the data collected from the real hardware to derive a model using a Machine Learning (ML) algorithm. The proposed model can easily be distributed among development teams and is dedicated to emulate the system for testing the OBSW.},

keywords = {},

pubstate = {published},

tppubtype = {inproceedings}

}

@inproceedings{Kovalov2020,

title = {Model-Based Reconfiguration Planning for a Distributed On-board Computer},

author = { Andrii Kovalov and Tobias Franz and Hannes Watolla and Vishav Vishav and Andreas Gerndt and Daniel Lüdtke},

url = {https://elib.dlr.de/137257/},

doi = {10.1145/3419804.3420266},

year  = {2020},

date = {2020-10-19},

booktitle = {12th System Analysis and Modelling (SAM) Conference - Languages, Methods and Tools for AI-based Systems, co-located with MODELS 2020, Virtual Event, Oct. 19-20, 2020},

pages = {55--62},

publisher = {Association for Computing Machinery (ACM)},

abstract = {The ScOSA project (Scalable On-board Computing for Space Avionics) of the German 

Aerospace Center aims at combining radiation hardened space hardware together 

with unreliable, but high performance COTS (commercial off-the-shelf) components 

as the processing nodes in a heterogeneous on-board network in order to provide 

future space missions with the necessary processing capabilities. However, such 

a system needs to cope with node failures. Our approach is to use a static 

reconfiguration graph that controls how software tasks are mapped to the 

processing nodes, and how this mapping should change in response to possible 

node failures. 

 

In this paper we present a model-based approach and a tool for automatic 

generation of reconfiguration graphs. Based on the software and hardware models, 

we traverse the graph of all possible failure situations. For every node of this 

graph we solve a combinatorial optimization problem of mapping tasks to 

processing nodes either with an SMT solver or using a genetic algorithm. The 

resulting reconfiguration graph can then be translated into the configuration 

files that are deployed on the target system, eliminating the need for tedious 

and error-prone manual configuration design.},

keywords = {},

pubstate = {published},

tppubtype = {inproceedings}

}

@inproceedings{Sommer2020,

title = {Shared Data Types for OSRA and TASTE using Modern C++},

author = { Jan Sommer and Andreas Gerndt and Daniel Lüdtke},

url = {https://elib.dlr.de/139230/},

year  = {2020},

date = {2020-09-28},

booktitle = {Workshop on Model Based Space Systems and Software Engineering (MBSE2020), ESA-Workshop, Virtual Event, Sep. 28-29, 2020},

publisher = {ESA},

abstract = {The European Space Agency (ESA) currently provides two tools for the modeling of on­board software: The Assert Set of Tools for Engineering (TASTE) and the On­Board Software Reference Architecture (OSRA). For data type modeling, TASTE uses the standardized Abstract Syntax Notation One (ASN.1), while OSRA provides an internal eCore­based data type representation. Unfortunately, the interworking between the two frameworks lacks a mechanism to exchange data easily without duplicating the data type information. In this work, we present our approach for the exchange of data types and data values between software developed with both tools. We show our additions to the OSRA infrastructure enabling the exchange of data types between OSRA and TASTE based on the same data type descriptions in ASN.1. This includes complementing the OSRA editor with the ability to read and write ASN.1 data type descriptions and to specify the data type encodings in TASTE's ASN.1 Control Notation. Our previous implementation of the ASN.1 data types in Modern C++ has been extended with a prototypical implementation for the serialization of the data types compatible with TASTE's ACN encoded types. As for the data types themselves, C++ metaprogramming techniques have been used for the encoder. This allows us to keep the code generators simple and maintainable. Some early results on the exchange of data between OSRA, enabled with our prototype generator, and the TASTE framework with its own ASN.1 compiler are presented and discussed.},

keywords = {},

pubstate = {published},

tppubtype = {inproceedings}

}

@inproceedings{Lund2020,

title = {A Fault-tolerant, Scalable and Distributed Middleware for Future Space Missions},

author = { Andreas Lund and Zain Alabedin Haj Hammadeh and Patrick Kenny and Vishav Vishav and Andrii Kovalov and Andreas Gerndt and Daniel Lüdtke},

url = {https://elib.dlr.de/136450/},

year  = {2020},

date = {2020-09-01},

booktitle = {Deutscher Luft- und Raumfahrtkongress (DLRK), Online Event, Sep. 1-3, 2020},

publisher = {Deutsche Gesellschaft für Luft- und Raumfahrt},

abstract = {The computational demands of current space missions outrun the capability of available state-of-the-art 

space-qualified computing hardware. Future missions, including earth-observation with high-resolution cameras, on-orbit real-time servicing, as well as autonomous spacecraft and rover missions on distant celestial 

bodies, will have even higher requirements concerning the computational power of the spacecrafts hardware. 

An approach to overcome these difficulties, which is already used and will be used widely in the future, is 

the use of interconnected commercial-off-the-shelf (COTS) processors for the on-board computers (OBC) of 

spacecraft. The COTS processors, while offering a much higher performance at a much lower cost, have the 

disadvantage of being more vulnerable to soft errors induced by radiation in comparison to space-qualified 

processors. In this context, the ScOSA Flight Experiment project develops an OBC which copes with the requirements for future space missions. The OBC will combine reliable computing nodes (RCNs) together with 

high-performance nodes (HPNs) into a single distributed system. For abstracting this complex architecture to 

a monolithic system, a middleware is needed. In this paper, we present the ScOSA middleware by means of 

its individual components. Furthermore, we explain its features of heterogeneity, scalability, reconfiguration, 

cross-processor distribution and fault-tolerance. Since the ScOSA Flight Experiment project is a successor of 

the OBC-NG and the ScOSA projects, its middleware is also a further development of the existing middleware. 

Therefore, we will present and discuss our contributions and plans for enhancement of the middleware in the 

course of the new project.},

keywords = {},

pubstate = {published},

tppubtype = {inproceedings}

}

@inproceedings{Mueller2020a,

title = {Towards an FDIR Software Fault Tree Library for Onboard Computers},

author = { Sascha Müller and Kilian Johann Höflinger and Michal Smisek and Andreas Gerndt},

url = {https://elib.dlr.de/135846/},

doi = {10.1109/AERO47225.2020.9172756},

year  = {2020},

date = {2020-03-08},

booktitle = {IEEE Aerospace Conference, Yellowstone Conference Center, Big Sky, Montana, March 8-13, 2020},

pages = {1--10},

publisher = {IEEE},

abstract = {The increasing complexity of space missions, their software architectures, and hardware that has to meet the demands for those missions, imposes numerous new challenges for many engineering disciplines such as reliability engineering. Affected by the ever growing demand for more onboard computation power are the onboard computers. They in return require Fault Detection, Isolation, and Recovery (FDIR) architectures to support their fault tolerant operation in the harsh environment of space. Especially high performance commercial processing units face the challenge of dealing with negative radiation effects, which may significantly degrade their operation. To design performant and fault tolerant onboard computers, it is of high interest to assess the effectiveness of the FDIR architecture in the early phase of system design. This can be achieved using Fault Tree Analysis (FTA). However, to create complete fault trees manually is an error prone and labor intensive task. In this paper, the methodology for assessing the FDIR design of onboard computers in space systems, presented in [1], is refined by introducing a library of FDIR routines. The routines are modeled using fault trees and are composed into a software system fault tree using a basic fault model and a design configuration chosen by the reliability engineer. To assess the configurations, we give a heuristic based on a factor-criteria-metric model. We demonstrate the feasability of our approach on the basis of a case study on the rover of the Martian Moons eXploration (MMX) mission. Several FDIR configurations are studied and fault trees are generated for them. For the chosen case study, we obtain a reduction of up to 80% in terms of modeling effort.},

keywords = {},

pubstate = {published},

tppubtype = {inproceedings}

}

@inproceedings{Bahnmueller2020,

title = {Evaluation of Interaction Techniques for Early PhaseSatellite Design in Immersive AR},

author = { Anna Bahnmüller and Syed Muhammad Azeem and Georgia Albuquerque and Andreas Gerndt},

url = {https://elib.dlr.de/137443/},

doi = {10.1109/AERO47225.2020.9172753},

year  = {2020},

date = {2020-03-08},

booktitle = {IEEE Aerospace Conference, Yellowstone Conference Center, Big Sky, Montana, March 8-13, 2020},

publisher = {IEEE},

abstract = {In this paper, we present a new controller-based interaction technique on the Microsoft HoloLens to support communication for the early phase satellite design at the Concurrent Engineering Facility (CEF). We design a virtual satellite with virtual moveable objects utilizing two different interaction methods: the default hand gesture-based interaction method and a novel controller-based interaction method for rotation and translation of satellite components in immersive augmented reality. In order to evaluate our method, we conduct a perceptual study with 12 participants. We apply multiple performance metrics for each user on both methods. Additionally, we measure user preferences and ease of use. Our results show that our controller-based method is significantly more precise for placing objects (consisting of position and orientation). Furthermore, it is less time consuming than the hand gesture-based method and more preferred by the participants.},

keywords = {},

pubstate = {published},

tppubtype = {inproceedings}

}

@inproceedings{SOMM19b,

title = {Creating a Reliable Data Type Framework for the OSRA Using Modern C++},

author = {Jan Sommer and Daniel Lüdtke and Andreas Gerndt},

url = {https://elib.dlr.de/130256/},

year  = {2019},

date = {2019-10-21},

booktitle = {70th International Astronautical Congress (IAC), Washington, D.C., USA, Oct. 21-25, 2019},

publisher = {International Astronautical Federation (IAF)},

abstract = {Ever increasing demands on the complexity of onboard software has lead the European Space Agency to define the On­Board Software Reference Architecture (OSRA) creating a common framework for modeling onboard software for space applications. OSRA provides tools for the description of onboard software (OSW) in a component­centric way, but leaves the implementation of the OSW itself or related auto­coding tools to other institutions. As a first step towards a code­generation framework from high level software models, we present source code mappings from the OSRA data type model to a C++ type system. The goal of the framework is to take care of type safety and value consistency issues and to provide an intuitive interface to the application developer for defining and working with data types, while at the same time having the target of auto­coding in mind. We use language features introduced with the modern C++ standards to allow for extensive validity checks at compile­time and additional checks at runtime. For the integration with OSRA tools, we take an intermediate step transforming the graphically declared types of OSRA into an ASN.1 representation before generating the corresponding C++ source code. The integration is bidirectional, i.e. data types, which have been constructed solely in ASN.1 notation, can also be used inside OSRA models which helps maintaining more complex data structures in a textual format and enables us to use existing complex data sets from previous projects and from The Assert Set of Tools for Engineering (TASTE) project to test the feasibility and the limitations of the type system. In the end, we present a type system which can be auto­generated and automatically avoids common sources of error like faulty initialization, out­of­bound access and accidental range overflows. Such errors cause compile­time errors if possible and runtime errors otherwise. In order to provide developers with a practical solution, efforts were made to facilitate integration with existing code bases or third party libraries which allows an iterative process of adaption. We strive to generate complete onboard software projects from the OSRA component model. The data type system defined here provides therefore the basis for that endeavor as it determines the way components will exchange data and how developers will need to interact with them.},

keywords = {},

pubstate = {published},

tppubtype = {inproceedings}

}

@inproceedings{FISC19,

title = {Spacecraft Interface Management in Concurrent Engineering Sessions},

author = {Philipp M Fischer and Caroline Lange and Volker Maiwald and Sascha Müller and Andrii Kovalov and Janis Häseker and Thomas Gärtner and Andreas Gerndt},

url = {https://elib.dlr.de/130164/

},

doi = {10.1007/978-3-030-30949-7_7},

year  = {2019},

date = {2019-10-06},

booktitle = {16th International Conference on Cooperative Design, Visualization and Engineering (CDVE2019), Mallorca, Spain, Oct. 6-9, 2019},

pages = {54--63},

publisher = {Springer, Cham},

abstract = {This paper contributes to the topic of spacecraft interface and data rate management in Concurrent Engineering (CE) sessions. At DLR, CE is used together with a CE process for designing new spacecraft. The software Virtual Satellite supports this process. It provides a shared system model to the engineers to exchange design information. Until today, it supports the structural decomposition of the system and the analysis of design drivers such as the mass or power consumption of the spacecraft. During one of the S2TEP studies for a multi-mission platform it was required to have a closer look to power and data interfaces. This paper discusses the state of the art to this topic and derives a generic approach to it. This approach is customized and nally implemented in Virtual Satellite and directly applied in the S2TEP study.},

keywords = {},

pubstate = {published},

tppubtype = {inproceedings}

}

@inproceedings{PETE19,

title = {Digital Availability of Product Information for Collaborative Engineering of Spacecraft},

author = {Diana Peters and Philipp M Fischer and Philipp M Schäfer and Kobkaew Opasjumruskit and Andreas Gerndt},

url = {https://elib.dlr.de/133030/},

doi = {10.1007/978-3-030-30949-7_9},

year  = {2019},

date = {2019-10-06},

booktitle = {16th International Conference on Cooperative Design, Visualization and Engineering (CDVE2019), Mallorca, Spain, Oct. 6-9, 2019},

pages = {74--83},

publisher = {Springer, Cham},

abstract = {In this paper, we introduce a system to collect product information from manufacturers and make it available in tools that are used for concurrent design of spacecraft. The planning of a spacecraft needs experts from dierent disciplines, like propulsion, power, and thermal. Since these dierent disciplines rely on each other there is a high need for communication between them, which is often realized by a Model-Based Systems Engineering (MBSE) process and corresponding tools. We show by comparison that the product information provided by manufacturers often does not match the information needed by MBSE tools on a syntactic or semantic level. The information from manufacturers is also currently not available in machine-readable formats. Afterwards, we present a prototype of a system that makes product information from manufacturers directly available in MBSE tools, in a machine-readable way.},

keywords = {},

pubstate = {published},

tppubtype = {inproceedings}

}

@inproceedings{HAMM19,

title = {Event-Driven Multithreading Execution Platform for Real-Time On-Board Software Systems},

author = {Zain A H Hammadeh and Tobias Franz and Olaf Maibaum and Andreas Gerndt and Daniel Lüdtke},

editor = {Adam Lackorzynski and Daniel Lohmann},

url = {https://elib.dlr.de/128249/},

year  = {2019},

date = {2019-07-09},

booktitle = {15th Workshop on Operating Systems Platforms for Embedded Real-Time applications (OSPERT), Stuttgart, Germany, July 9, 2019},

pages = {29--34},

abstract = {The high computational demand and the modularity of future space applications make the effort of developing multithreading reusable middlewares worthwhile. In this paper, we present a multihreading execution platform and a software development framework that consists of abstract classes with virtual methods. The presented work is written in C++ following the event-driven programming paradigm and based on the inverse of control programming principle. The platform is portable over different operating systems, e.g., Linux and RTEMS. This platform is supported with a modeling language to automatically generate the code from the given requirements. Our platform has been used in already flying satellites, e.g., Eu:CROPIS. We present in this paper an example that illustrates how to use the proposed platform in designing and implementing an on-board software system.},

keywords = {},

pubstate = {published},

tppubtype = {inproceedings}

}

@inproceedings{MAIB19,

title = {FDIR Handling in Eu:CROPIS},

author = {Olaf Maibaum and Ansgar Heidecker and Fabian Greif and Markus Schlotterer and Andreas Gerndt},

url = {https://elib.dlr.de/129297/},

year  = {2019},

date = {2019-05-06},

booktitle = {Proceedings, 12th IAA Symposium on Small Satellites for Earth Observation, Berlin, Germany, May 06-10, 2019,  IAA-B12-0704},

publisher = {International Academy of Astronautics (IAA)},

abstract = {Fault detection, isolation, and recovery (FDIR) mechanisms in on-board software are essential to guarantee the survival of the satellite in case of a hardware malfunction. E.g., outage of essential attitude control system (ACS) actuators or sensors can lead to mission loss. The on-board software has to handle such situation autonomously by switching to cold redundant devices or by isolation of information from hot redundant devices. The FDIR implementation for the ACS of the spin stabilized small satellite Eu:CROPIS (Euglena Combined Regenerative Organic food Production In Space) is shown in this paper.},

keywords = {},

pubstate = {published},

tppubtype = {inproceedings}

}

@inproceedings{UTZI19,

title = {Augmented Reality for Remote Collaboration in Aircraft Maintenance Tasks},

author = {Sebastian Utzig and Robert Kaps and Azeem Syed Muhammad and Andreas Gerndt},

url = {https://elib.dlr.de/128785/

},

doi = {10.1109/AERO.2019.8742228},

year  = {2019},

date = {2019-03-02},

booktitle = {Proceedings, IEEE Aerospace Conference, Yellowstone Conference Center, Big Sky, Montana, March 2-9, 2019},

publisher = {IEEE},

abstract = {In this paper, we present a concept study to facilitate maintenance of an operating aircraft based on its lifelong collected data, called Digital Twin. It demonstrates a damage assessment scenario on a real aircraft component. We propose a graphical user interface that contains menu-guided instructions and inspection documentation to increase the efficiency of manual processes. Furthermore, experts located at different sites can join via a virtual session. By inspecting a 3D model of the aircraft component, they can see synchronized information from a Digital Twin database. With Augmented Reality glasses, the Microsoft HoloLens, a Digital Twin can be experienced personally. In the inspector's view, the 3D model of the Digital Twin is directly superimposed on the physical component. This Mixed Reality Vision can be used for inspection purposes. Any inspection related information can be directly attached to the component. For example, damage locations are marked by the inspector on the component's surface and are stored in the Digital Twin database. Our scenario demonstrates how new information can be derived from the combination of collected data and analyses from the Digital Twin database. This information is used to maintain the continued airworthiness of the aircraft. Feedback from domain related engineers confirm that our interface has an enormous potential for solving current maintenance problems in the aviation industry. Additionally, our study provides ideas for the integration of further analysis functions into the interface.},

keywords = {},

pubstate = {published},

tppubtype = {inproceedings}

}

@inproceedings{HOEF19,

title = {Dynamic Fault Tree Analysis for a Distributed Onboard Computer},

author = {Kilian Höflinger and Sascha Müller and Ting Peng and Moritz Ulmer and Daniel Lüdtke and Andreas Gerndt},

url = {https://elib.dlr.de/128700/},

doi = {10.1109/AERO.2019.8742128},

year  = {2019},

date = {2019-03-02},

booktitle = {Proceedings, IEEE Aerospace Conference, Yellowstone Conference Center, Big Sky, Montana, March 2-9, 2019},

publisher = {IEEE},

abstract = {Future space missions will demand greater capabilities regarding the processing of sensor data on onboard computers of satellites than current space technology can provide. Limited downlink bandwidth, high resolution sensors and more rigid real-time control algorithms, dedicated to increase satellite autonomy, drive the need for growing onboard computing performance. To overcome these challenges, new high-performance onboard computers are necessary, leading to an increased consideration of Commercial-Of-The-Shelf (COTS) components. The DLR project Scalable Onboard Computing for Space Avionics (ScOSA) targets these challenges with a complex onboard computer design consisting of space-qualified and COTS computing devices, arranged as heterogeneous SpaceWire-interconnected grid computer in space. However, the utilization of COTS components in the harsh space environment imposes new challenges on the system. Therefore, Fault Detection Isolation and Recovery (FDIR) mechanisms are important functionalities of systems like ScOSA. These enable the preservation of the demanded dependability levels for an embedded system in space. To ensure this dependability, the FDIR subsystem configuration requires a detailed analysis regarding potential faults in the system. For this purpose, we employed Dynamic Fault Tree (DFT) analysis, a methodology which is used to model faults and their temporal propagation through an onboard computer. With this paper, we contribute a new building block for showing the applicability of DFT analysis and for closing the gap between theory and practical application of DFTs. The quantitative results of the analysis of the contribution of the ScOSA FDIR subsystem to the overall system reliability are taken as baseline for a discussion on how to effectively improve the system's reliability further. To showcase the methodology, an earth observation low earth orbit use case scenario is defined and the by FDIR means enforced processing system of the Xilinx Zynq SoC computing devices with a DFT analysis evaluated.},

keywords = {},

pubstate = {published},

tppubtype = {inproceedings}

}

@inproceedings{SOMM19b,

title = {Evaluation and Development of the Interaction Layer for Inter-Component Communication of the Onboard Software Reference Architecture},

author = {Jan Sommer and Raghuraj Tarikere Phaniraja Setty and Olaf Maibaum and Andreas Gerndt and Daniel Lüdtke},

url = {https://elib.dlr.de/128423/},

doi = {10.1109/AERO.2019.8741823},

year  = {2019},

date = {2019-03-02},

booktitle = {Proceedings, IEEE Aerospace Conference, Yellowstone Conference Center, Big Sky, Montana, March 2-9, 2019},

publisher = {IEEE},

abstract = {Ever increasing demands on the complexity of onboard software has led the European Space Agency to define the Onboard Software Reference Architecture (OSRA) to create a common framework for modeling onboard software for space applications. The first major version was released at the end of 2017 and provides the metamodel with additional documentation and a model editor. It enables the user to create a detailed high-level representation of an onboard software system, but leaves the choice of an execution platform and the generation of actual source code for it to the implementing party. The core philosophy of OSRA is to divide the onboard software into independent components with clearly defined interfaces and separate the functional and non-functional aspects of components. However, OSRA aims to cover a large range of applications and therefore provides a large variety of modeling artifacts for component interaction. While this gives a lot of design freedom to the software architect designing the overall software, it moves the responsibility of supporting all aspects and behavioral requirements correctly to the execution platform and interaction layer. In this study, we analyze the demands of OSRA towards the execution platform and necessary elements which have to be added or generated in order to support the multitude of different inter-component interactions. The results of the analysis are used to implement the first prototypical code-generation framework for OSRA models. The target execution platform for the code generators is the Tasking Framework, a reactive cooperative multitasking framework from DLR. It has successful flight heritage in numerous spacecraft projects and has also been the target of code generation from software models before. Nevertheless, many of the aspects discussed here apply equally to common priority-based preemptive multitasking frameworks. The analysis and the implementation both uncovered several issues where clarification in the OSRA.},

keywords = {},

pubstate = {published},

tppubtype = {inproceedings}

}

@inproceedings{MIKA18,

title = {Synthesizing and Optimizating FDIR Recovery Strategies from Fault Trees},

author = {Liana Mikaelyan and Sascha Müller and Andreas Gerndt and Thomas Noll},

editor = {Cyrille Artho and Peter Csaba Ölveczky},

url = {https://elib.dlr.de/125086/},

doi = {10.1007/978-3-030-12988-0_3},

year  = {2019},

date = {2019-02-02},

booktitle = {6th International Workshop on Formal Techniques for Safety-Critical Systems (FTSCS), ICEFM Workshop, Gold Coast, Australia, November 16, 2018},

volume = {1008},

pages = {37--54},

publisher = {Springer, Cham},

series = {Communications in Computer and Information Science (CCIS)},

abstract = {Redundancy concepts are an integral part of the design of space systems. Deciding when to activate which redundancy and which component should be replaced can be a difficult task. In this paper, we refine a methodology where recovery strategies are synthesized from a model of non-deterministic dynamic fault trees. The synthesis is performed by transforming non-deterministic dynamic fault trees into Markov Automata. From the optimized scheduler, an optimal recovery strategy can then be derived and represented by a model we call Recovery Automaton. We discuss techniques on how this Recovery Automaton can be further optimized to contain fewer states and transitions and show the effectiveness of our approach on two case studies.},

keywords = {},

pubstate = {published},

tppubtype = {inproceedings}

}

@inproceedings{BARA18,

title = {3D Spacecraft Configuration using Immersive AR Technology},

author = {Artur Baranowski and Sebastian Utzig and Philipp Fischer and Andreas Gerndt and Jens Herder},

editor = {Jens Herder and Christian Geiger and Ralf Dörner and Paul Grimm},

url = {https://elib.dlr.de/124540/},

year  = {2018},

date = {2018-10-10},

booktitle = {Virtuelle und Erweiterte Realität: 15. Workshop der GI-Fachgruppe VR/AR, Düsseldorf, Germany, October 10-11, 2018},

pages = {71--82},

publisher = {Shaker Verlag},

abstract = {In this paper we propose an integrated immersive augmented reality solution for a software tool supporting spacecraft design and verication. The spacecraft design process relies on expertise in many domains, such as thermal and structural engineering. The various subsystems of a spacecraft are highly interdependent and have diering requirements and constraints. In this context, interactive visualizations play an important role in making expert knowledge accessible. Recent immersive display technologies oer new ways of presenting and interacting with computer-generated content. Possibilities and challenges for spacecraft conguration employing these technologies are explored and discussed. A user interface design for an application using the Microsoft HoloLens is proposed. To this end, techniques for selecting a spacecraft component and manipulating its position and orientation in 3D space are developed and evaluated. Thus, advantages and limitations of this approach to spacecraft conguration are revealed and discussed.},

keywords = {},

pubstate = {published},

tppubtype = {inproceedings}

}

@inproceedings{FISC18b,

title = {Enabling a Conceptual Data Model and Workflow Integration Environment for Concurrent Launch Vehicle Analysis},

author = {Philipp M Fischer and Meenakshi Deshmukh and Aaron Koch and Robert Mischke and Antonio Martelo Gomez and Andreas Schreiber and Andreas Gerndt},

url = {https://elib.dlr.de/124541/},

year  = {2018},

date = {2018-10-01},

booktitle = {69th International Astronautical Congress (IAC), Bremen, Germany, October 1-5, 2018},

journal = {Proceedings of the International Astronautical Congress, IAC},

organization = {International Astronautical Federation (IAF)},

abstract = {Concurrent Engineering (CE) and Model Based Systems Engineering (MBSE) have increased the efficiency of spacecraft, and satellite design in particular. Early design of satellites in Concurrent Engineering Centers (CEC) has almost become business as usual. However, such progress has still to be achieved for the design of launchers. Applying the same approaches as used for satellites has not led to the same amount of improvement, yet. To address this, DLR initiated the project Concurrent Launch Vehicle Analysis (CLAVA) to investigate the shortcomings and to improve the efficiency of conceptual launcher design and analysis. From an MBSE point of view, investigations show that concurrent modelling requires new Conceptual Data Models. In contrast to designing satellites, they are focused on a much more physical abstraction rather than a functional one. Regarding simulations, it has become clear that the conceptual design phase of launchers requires far more computationally intense simulations in a sequential order. With this knowledge, it is possible to outline a new process for CE studies allowing for concurrent design phases and sequential simulation phases. For this, an adjusted architecture of tools is required as well. The data model used for satellite studies within DLR's Concurrent Engineering Facility (CEF) does not fit to the requirements of launcher design and has been adapted. Additionally, DLR's aeronautics divisions have already made substantial progress in increasing the efficiency of their simulations. They employ automated simulation workflows using a parametric model for information exchange between integrated tools. This approach has been adopted and integrated. This paper outlines how this approach is combined with CE and MBSE concepts used for satellites and addresses the specific requirements of launcher design. It provides details about the database used during CE sessions, and how its information is transferred into the parametric data model used to run the required simulations. The conceptual data model of this database has been adapted to the physical representation of launchers; these changes will also be discussed. Furthermore, the general idea of the workflow and the design of the parametric model will be presented. The paper concludes by providing an outlook of how DLR intends to continue on this work, and further refine the developed tools and processes into daily CE and CEF application.},

keywords = {},

pubstate = {published},

tppubtype = {inproceedings}

}

@inproceedings{WEPS18,

title = {A Model-Driven Software Architecture for Ultra-Cold Gas Experiments in Space},

author = {Benjamin Weps and Daniel Lüdtke and Tobias Franz and Olaf Maibaum and Thijs Wendrich and Hauke Müntinga and Andreas Gerndt},

url = {https://elib.dlr.de/126145/},

year  = {2018},

date = {2018-10-01},

booktitle = {69th International Astronautical Congress (IAC), Bremen, Germany, October 1-5, 2018},

organization = {International Astronautical Federation (IAF)},

abstract = {Developing software for large and complex experiments is a challenging task. It must incorporate many requirements from different domains, all with their own conceptions about the overall systems. An additional level of complexity is added if the experiment is conducted autonomously during a sounding rocket flight. Without a proper software architecture and development techniques, achieving and maintaining a high code quality is a very cumbersome task.

This paper describes the architecture and the model-driven development approach we used to implement the control software of the experiments in the MAIUS-1 mission (matter-wave interferometry in microgravity). In this mission, the software had to handle around 150 experiments in six minutes autonomously and adapt to changes in the control flow according to real-time data from the experiment.

The MAIUS-1 mission was the first mission to create Bose-Einstein condensates in space and conduct other experiments with ultra-cold gases on a sounding rocket. Besides the scientific goals in the area of quantum-optics, other important objectives of the mission were the miniaturization and further development of laser systems, vacuum components, optical sensors, and other related technologies. To fulfil these goals, new experimental hardware has been created which had to be integrated and tested with the software of the experiment computer.

The custom-made hardware and the considerable number of domains involved brought up many challenges for the software engineering. To face all these challenges of developing software with this high complexity, we chose to follow a model-driven software development approach. Several domain-specific languages (DSLs) accompanied with specialized tools were created to allow the physicists and electronic engineers to describe system components and the experiments in a domain-specific way. These descriptions were then automatically transformed in C++ code for the flight software. This way we could actively incorporate all the domains involved in conducting the experiment directly in building the flight software without compromising the software quality.

We created a versatile software platform not only for the MAIUS-1 mission but also for upcoming missions with similar experiments and hardware. With our approach we were able to generate around 84% of the source code for the final flight software from the domain-specific models. Besides the improvement of the development process, the code generation made a significant contribution to the overall software quality as almost all manual coding of error-prone boilerplate code could be mitigated.},

keywords = {},

pubstate = {published},

tppubtype = {inproceedings}

}

@inproceedings{SCHA18,

title = {Toward a Digital Platform for Spacecraft Manufacturing},

author = {Philipp Matthias Schäfer and Philipp M Fischer and Nico Brehm and Christian Erfurth and Andreas Gerndt and Kobkaew Opasjumruskit and Diana Peters},

url = {https://elib.dlr.de/122345/},

year  = {2018},

date = {2018-09-26},

booktitle = {8th International Systems & Concurrent Engineering for Space Applications Conference (SECESA), Glasgow, UK, September 26-28, 2018},

organization = {ESA},

abstract = {Professionals of many disciplines are involved in a spacecraft mission. They all use different software tools that are tailored to their tasks and they share data in various ways among themselves. These data sharing activities form a network, which, given modern software engineering practices, offers a lot of opportunities for improvement: simplify data source discoverability, automate previously manual data sharing activities, and better make use available data sources. To simplify data source discoverability, we propose a digital platform with a serviceoriented architecture. Such an architecture also helps to better make use of available data sources. Additionally, we present our projects that automate previously manual data sharing activities and that make better use of available data sources. With the development of the digital platform we aim at providing a significant reduction in resource expenditure, especially time expenditure, for spacecraft missions.},

keywords = {},

pubstate = {published},

tppubtype = {inproceedings}

}

@inproceedings{MUEL18,

title = {Towards a Conceptual Data Model for Fault Detection, Isolation and Recovery in Virtual Satellite},

author = {Sascha Müller and Andreas Gerndt},

url = {https://elib.dlr.de/122061/},

year  = {2018},

date = {2018-09-26},

booktitle = {8th International Systems & Concurrent Engineering for Space Applications Conference (SECESA), Glasgow, UK, September 26-28, 2018},

organization = {ESA},

abstract = {Reliability engineering is an integral part in the design of safety critical systems. Especially spacecraft that cannot receive physical maintenance 

once delivered into orbit heavily require a fault tolerant design approach. In order to overcome these challenges, concepts from the domain of Fault 

Detection, Isolation and Recovery (FDIR) are employed. With this paper we present our approach for bringing Model Based Systems Engineering into the realm of reliability engineering using the Virtual Satellite (VirSat) framework. The tool we are developing for this purpose is called VirSat FDIR. 

 

In this paper, we discuss a Conceptual Data Model for modelling important aspects of the FDIR domain that we have conceived and implemented for VirSat FDIR. It supports modelling of FDIR faults, recovery, analysis and requirements. We further discuss how these models can be actively used for the purpose of generation of FDIR artefacts and the process of Verification and Validation.},

keywords = {},

pubstate = {published},

tppubtype = {inproceedings}

}