The use of simulation in the design of critical embedded systems

Les plate-formes virtuelles permettant de prédire par simulation numérique les performances deviennent peu à peu une réalité dans la conception des systèmes de contrôle les plus complexes et les plus contraints (automobile, aéronautique, contrôle de réseaux power-grid, etc). Dès les phases amont du cycle de conception, ces outils guident les concepteurs dans leurs choix de conception. Le premier objectif de cet exposé est de dresser un rapide panorama des modèles et techniques de simulation de l'embarqué critique: simulation du comportement fonctionnel (lois de contrôle), simulation "timing-accurate" des plate-formes d'exécution, de leur complémentarité et limites actuelles. Contrairement à des techniques mathématiques, la simulation ne fournit a priori aucune garantie sur la couverture de vérification et les situations pire-cas ("corner cases") ne sont pas nécessairement identifiées. Néanmoins la simulation est de plus en plus incontournable car les modèles analytiques ne sont généralement pas en mesure de capturer toute la complexité des systèmes réels. Le second objectif de cet exposé est d'identifier des bonnes pratiques méthodologiques pour l'utilisation de la simulation dans les systèmes critiques (ex: choix des temps de simulation et nombre d'expérimentations en fonction de caractéristiques structurelles des processus simulés, métriques de performances pour les événements rares, etc)

CPAL: High-Level Abstractions for Safe Embedded Systems

Innovation in the field of embedded systems, and more broadly in cyber-physical systems, increasingly relies on software. The productivity gain in software development can hardly keep up with the demand for software despite the increasing adoption of Model-Driven Development (MDD). In this context, we believe that major productivity and quality improvements are still ahead of us through better programming languages and environments. CPAL, the Cyber-Physical Action Language, is a contribution in that direction with the objective to speed-up the development of embedded systems with dependability constraints. The objective of this paper is to present and illustrate the use-cases of the high-level abstractions offered to the developer in CPAL with respect to real-time scheduling, introspection mechanisms, native support of Finite State Machines (FSMs), abstracting the hardware and decoupling functional concerns from non-functional concerns

Towards a declarative modeling and execution framework for real-time systems

Our work is a contribution towards addressing what Thomas Henziger called the grand challenge in embedded software design [5]: "offering high-level programming models that exposes the execution properties of a system in a way that permits the programmer to express desired reaction and execution requirements, permits the compiler and run-time systems to ensure that these requirements are satisfied". In the programming model we describe here, the developer states the permissible timing behavior of the system, a system synthesis step involving both analysis and optimization generates a scheduling solution which at run-time is enforced by the execution environment. With respect to the synchronous programming models, our approach implements a weaker version of time-determinism, still providing a form of timing-predictability sufficient in many applications while remaining closer to mainstay software development practices. This approach is currently being implemented and experimented in the CPAL language development tools and associated runtime environment