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Abstract

This paper presents an illustration of the utilization of an information model through a complex system. The information model is in support of a model driven methodology of complex system design. It allows addressing requirements definition and their traceability towards the solution and the Verification and Validation (V&V) elements. The work considers especially an important system propriety which is safety. SysML language is used to establish the information model thanks to the different available diagrams which make SysML as the language for systems engineering. The system considered is the braking system of an aircraft.

Abstract

This paper addresses the problem of safety evaluation of complex systems. It proposes an original and rigorous approach that integrates safety analysis in system engineering processes. The approach is based on system engineering (SE) principles and uses the famous industrial SE standard ANSI/EIA-632. The objective is to help designers and safety engineers in safety management of complex systems. For an efficient design, the model driven design is adopted through the definition of an information model. The system language SysML (System Modeling Language) is used to address requirements definition and their traceability towards the solution and the Verification and Validation (V&V) elements. This common language allows sharing information between the different persons involved in the design project like system engineer and safety engineer.

Résumé

L'intégration de diverses technologies, notamment celles de l'informatique et l'électronique, fait que les systèmes conçus de nos jours sont de plus en plus complexes. Ils ont des comportements plus élaborés et plus difficiles à prévoir, ont un nombre de constituants en interaction plus important et/ou réalisent des fonctions de plus haut niveau. Parallèlement à cette complexification des systèmes, la compétitivité du marché mondial impose aux développeurs de systèmes des contraintes de coût et de délais de plus en plus strictes. La même course s'opère concernant la qualité des systèmes, notamment lorsque ceux-ci mettent en jeu un risque en vies humaines ou un risque financier important. Ainsi, les développeurs sont contraints d'adopter une approche de conception rigoureuse pour répondre aux exigences du système souhaité et satisfaire les diverses contraintes (coût, délais, qualité, sûreté de fonctionnement,...). Plusieurs démarches méthodologiques visant à guider la conception de système sont définies par l'intermédiaire de normes d'Ingénierie Système. Notre travail s'appuie sur la norme EIA-632, qui est largement employée, en particulier dans les domaines aéronautique et militaire. Il consiste à améliorer les processus d'ingénierie système décrits par l'EIA-632, afin d'intégrer une prise en compte globale et explicite de la sûreté de fonctionnement. En effet, jusqu'à présent la sûreté de fonctionnement était obtenue par la réutilisation de modèles génériques après avoir étudié et développé chaque fonction indépendamment. Il n'y avait donc pas de prise en compte spécifique des risques liés à l'intégration de plusieurs technologies. Pour cette raison, nous proposons de nous intéresser aux exigences de Sûreté de Fonctionnement au niveau global et le plus tôt possible dans la phase de développement, pour ensuite les décliner aux niveaux inférieurs, ceci en s'appuyant sur les processus de la norme EIA-632 que nous étoffons. Nous proposons également une méthode originale de déclinaison d'exigences de sûreté de fonctionnement à base d'arbres de défaillances et d'AMDEC, ainsi qu'un modèle d'information basé sur SysML pour appuyer notre approche. Un exemple issu du monde aéronautique permet d'illustrer nos propositions.

Abstract

The integration of various technologies, including computer and electronics, makes the nowadays designed systems increasingly complex. They have behaviors which are more elaborate and difficult to predict, they have a greater number of components in interaction and/or perform highest level functions. Parallel to this increasing complexity of these systems, the competitive of the global market imposes strong constraints of cost and time to the system developers. Other strong constraints deal with the quality of these systems, especially when they involve human risks or significant financial risks. Thus, developers are forced to adopt a rigorous design approach to meet the desired system requirements and satisfy the various constraints (cost, time, quality, dependability...). Several methodological approaches to guide the system design are defined through system engineering standards. Our work is based on the EIA-632 standard, which is widely used, especially in the aeronautical and military fields. It is to improve the systems engineering process described by the EIA-632, in order to incorporate a global and explicit consideration of dependability. Indeed, till now the dependability was achieved by reusing generic models after having studied and developed independently each function. So there was no specific consideration of the risks associated with the integration of several technologies. For this reason, we propose to concern ourselves with the dependability requirements at the global level and as early as possible in the development phase. Then, these requirements will be decline to lower levels. We based our approach on the processes of the EIA-632 standard that we expand. We also propose an original method for the declination of the dependability requirements based on fault trees and FMEAC, and an information model based on SysML in order to support our approach. An example from the aeronautical field illustrates our proposals.

Mots-Clés / Keywords

Ingénierie système; Processus; EIA-632; Sûreté de fonctionnement; AMDEC; Arbres de défaillances; Exigence; Modèle d'information; SysML; System engineering; Processes; Dependability; FMECA; Fault trees; Requirements; Information model;

Abstract

This paper presents a new version of critical (feared) scenarios derivation tool ESA PetriNet (extraction scenarios algorithm from Petri net) available from: http://www.laas.fr/ESA. ESA PetriNet allows to derive scenarios leading to critical (feared) situation. In the past version of the tool hybrid aspect (both discrete and continuous dynamic) of system is tacked into account by temporal abstraction. In the version presented in this paper, the system model is given by a hybrid Petri net (differential predicate-transition Petri net) and the hybrid model is directly considered (without temporal abstraction). The algorithm implemented deals with both continuous and discrete dynamics. Furthermore, generated scenarios are minimal (only necessary events). Only necessary information is provided to designer.

Abstract

The aim of this paper is to propose a rigorous and complete design framework for complex system based on system engineering (SE) principles. The SE standard EIA-632 is used to guide the approach. Within this framework, two aspects are presented. The first one concerns the integration of safety requirements and management in system engineering process. The objective is to help designers and engineers in managing safety of complex systems. The second aspect concerns model driven design through the definition of an information model. This model is based on SysML (System Modeling Language) to address requirements definition and their traceability towards the solution and the Verification and Validation (V&V) elements.

Abstract

The work presented in this paper is part of a proposed framework as complete and rigorous as possible for the design of complex systems. The methodological framework used is System Engineering, which is a methodological approach to control the design of complex systems. The practices of this approach are transcribed in standards, realized by methods and supported by tools. In our case, the standard EIA-632 was adopted. Specifically, to deal with the dependability of these complex systems and to improve the processes dealing with dependability, we have defined a global approach. This approach incorporates the consideration of dependability in system engineering processes. The work presented in this paper supports and complements the overall approach: it is the proposal of an information model based on the SysML language, allowing the requirements management, including safety requirements