Model to model transformation is a critical task in Model Based System Engineering (MBSE). Indeed, there is a growing need to migrate existing models, for instance in UML or SysML, to fit new modeling approaches such as Arcadia/Capella. The reverse is also desirable, as organizations have since long invested time and money in models and tools on top of these standards. In many situations a smooth integration of new tools requires compliancy with the in-place standards.

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Capella [1] is a model-based engineering solution that has been successfully deployed in a wide variety of industrial contexts. Based on a graphical modelling workbench, it provides system architects with rich methodological guidance relying on Arcadia [9], a comprehensive model-based engineering method.

SysML [2] supports complex modeling for system engineering applications at different steps of the system life cycle. SysML provides architects and system engineers an easy way to collaborate using a unique common language. It enables the management of systems with growing complexity across different development teams with many modeling capabilities: requirement, behavioral and structural definitions. Refer to OMG SysML definition [2] for further details on SysML.

To take advantage of the power of the Capella tool, as well as the conformance to the standardized SysML language, this paper depicts a first attempt of Capella to SysML mapping and a prototype of transformation tool as proof-of-concept. This work is part of the Clarity project [3].

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Two complementary languages for Systems Engineering:

– Descriptive modeling in SysML

– Formal equation-based modeling for analyses and trade studies in Modelica

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Objective:

– Leverage the strengths of both SysML and Modelica by integrating them to create a more expressive and formal MBSE language.

– Define a formal Transformation Specification:

 a SysML4Modelica profile

 a Modelica abstract syntax metamodel

 a mapping between Modelica and the profile

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Executable models can be used to support all engineering activities in Model-Based Systems Engineering. Testing and simulation of such models can provide early feedback about design choices. How-ever, in today’s complex systems, failures could arise due to subtle errors that are hard to find without checking all possible execution paths. Formal methods, and especially model checking can uncover such subtle errors, yet their usage in practice is limited due to the specialized expertise and high computing power required. There-fore we created an automated, cloud-based environment that can verify complex reachability properties on SysML State Machines using hidden model checkers. The approach and the prototype is illustrated using an example from the aerospace domain.

SysML is a modeling language used for systems analysis and design. While some domain-specific analyses (e.g., finite element analysis) can only be specified in SysML when combined with other vocabulary, many common analyses can be modeled purely in SysML using its parametric and behavioral semantics. In this paper, we focus on one kind of analysis, which is requirements verification, and propose a new Executable System Engineering Method (ESEM) that automates it using executable SysML modeling patterns that involve structural, behavioral and parametric diagrams. The resulting analysis model becomes executable using a general purpose SysML execution engine. We present our method and demonstrate it on a running example derived from an industrial case study where we have verified the power requirements of a telescope system. It involves dynamic power roll-ups in different operational scenarios and shows the automation capabilities of this method.

ABSTRACT

Applying systems engineering across the life-cycle results in a number of products built from interdependent sources of information using different kinds of system level analysis. This paper focuses on leveraging the Executable System Engineering Method (ESEM) [1] [2], which automates requirements verification (e.g. power and mass budget margins and duration analysis of operational modes) using executable SysML [3] models. The particular value proposition is to integrate requirements, and executable behavior and performance models for certain types of system level analysis. The models are created with modeling patterns that involve structural, behavioral and parametric diagrams, and are managed by an open source Model Based Engineering Environment (named OpenMBEE [4]). This paper demonstrates how the ESEM is applied in conjunction with OpenMBEE to create key engineering products (e.g. operational concept document) for the Alignment and Phasing System (APS) within the Thirty Meter Telescope (TMT) project [5], which is under development by the TMT International Observatory (TIO) [5].

In systems engineering practices, system design and analysis have historically been performed using a document-centric approach where stakeholders produce a number of documents that represent their views on a system under development. Given the ad-hoc, dis-parate, and informal nature of natural language documents, these views become quickly inconsistent. Rigor in engineering work is also lost in the transition from model-based engineering design and analysis to engineering documents. Once the documents are delivered, the engineering portion of the work is disconnected. In the Open Model Based Engineering Environment (OpenMBEE), Cross-References (aka transclusions) synthesize relevant engineer-ing information where model elements are not simply hyperlinked, but de-referenced in place in a document, upgrading a document-based process with model-based engineering technology. Those Cross-References are nowadays partially created manually, putting a burden on the engineer who is authoring the document. This paper presents an approach which can assist the engineer by pro-viding machine-generated suggestions for Cross-References using language processing, graph analysis, and clustering technologies on model data managed by the OpenMBEE infrastructure.

In the new era of Extreme large Telescopes (ELT) performance requirements are not the only critical parameters in the design space. Other requirements such as acquisition times and operational behavior of systems can influence the design significantly.

In an effort to address this challenge, this paper presents the TMT preliminary results of an ongoing effort towards creating a model, which captures the functional and physical architecture, behavior, requirements, and parametric relationships for TMT NFIRAOS LGS MCAO Acquisition Sequence and related use case scenarios at system level. Specifically, demonstrated and discussed are the results of using OMG’s Systems Modeling Language (SysML) to verify timing requirements in the early life-cycle phase through system-level simulation.

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Operational modes and behavior are modeled using activity diagrams. Scenarios are captured primarily using sequence and activity diagrams. Verifiable requirements are formally captured using constraints on properties.

This type of modeling can prove to be particularly useful when wanting to investigate the effect of parallelizing or re-ordering sequence acquisition tasks.

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Dans la pratique actuelle du développement des systèmes, existe un fossé important entre les activités liées à l’ingénierie système et le monde de la simulation dans les divers domaines d’expertise. En particulier, il n’y a pas de réel lien entre les modèles d’architecture développés en utilisant des langages comme SysML et les modèles d’analyse propres aux disciplines définis dans des outils spécialisés. Dans le but de pallier ce décalage, une fonctionnalité a été développée permettant d’intégrer des modèles décrits en SysML à des modèles d’analyse. Le présent article traite de l’utilisation de cette fonctionnalité pour la conception d’un système propulsif d’avion. Les exigences système et l’architecture sont définis dans un modèle SysML, les modèles d’analyse sont ensuite importés dans le modèle SysML, pour configurer des diagrammes paramétriques. Les analyses sont effectuées à partir du modèle SysML, afin de contrôler la conformité des exigences du système. Lorsque ces méthodes sont mises au service des processus de conception de l’industrie, la technologie peut permettre de rationaliser les demandes d’analyses à partir des modèles d’architecture système.

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L’article introduit tout d’abord la modélisation intégrée et ses capacités d’analyse puis il montre son application à une étude de cas industriel.

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