Desafíos en el diseño de sistemas Ciber-Físicos

Los sistemas cyber-físicos ─Cyber-Physical Systems CPS─ es un proceso que integra la computación con los procesos físicos. Los computadores embebidos, el monitoreo de redes y el control de procesos físicos, usualmente tienen ciclos de retroalimentación en los que los procesos físicos afectan los cálculos, y viceversa. En este artículo se examinan los desafíos en el diseño de estos sistemas, y se plantea la cuestión de si la informática y las tecnologías de redes actuales proporcionan una base adecuada para ellos. La conclusión es que para mejorar los procesos de diseño de estos sistemas no será suficiente con elevar el nivel de abstracción o verificar, formalmente o no, los diseños en los que se basan las abstracciones de hoy. El potencial social y económico de los CPS es mucho mayor de lo que hasta el momento se ha pensado; en todo el mundo se están realizando grandes inversiones para desarrollar esta tecnología, pero los retos son considerables. Para aprovechar todo el potencial de los CPS se tendrán que reconstruir los procesos de las abstracciones informáticas y de las redes, y los procesos se deberán acoger en pleno a los principios de las dinámicas físicas y de la computación

Reconciling Repeatable Timing with Pipelining and Memory Hierarchy

This paper argues that repeatable timing is more important and more achievable than predictable timing. It describes microarchitecture approaches to pipelining and memory hierarchy that deliver repeatable timing and promise comparable or better performance compared to established techniques. Specifically, threads are interleaved in a pipeline to eliminate pipeline hazards, and a hierarchical memory architecture is outlined that hides memory latencies

From Dataflow Specification to Multiprocessor Partitioned Time-triggered Real-time Implementation *

International audienceOur objective is to facilitate the development of complex time-triggered systems by automating the allocation and scheduling steps. We show that full automation is possible while taking into account the elements of complexity needed by a complex embedded control system. More precisely, we consider deterministic functional specifications provided (as often in an industrial setting) by means of synchronous data-flow models with multiple modes and multiple relative periods. We first extend this functional model with an original real-time characterization that takes advantage of our time-triggered framework to provide a simpler representation of complex end-to-end flow requirements. We also extend our specifications with additional non-functional properties specifying partitioning, allocation , and preemptability constraints. Then, weprovide novel algorithms for the off-line scheduling of these extended specifications onto partitioned time-triggered architectures à la ARINC 653. The main originality of our work is that it takes into account at the same time multiple complexity elements: various types of non-functional properties (real-time, partitioning, allocation, preemptability) and functional specifications with conditional execution and multiple modes. Allocation of time slots/windows to partitions can be fullyor partially provided, or synthesized by our tool. Our algorithms allow the automatic allocation and scheduling onto multi-processor (distributed) sys-tems with a global time base, taking into account communication costs. We demonstrate our technique on a model of space flight software systemwith strong real-time determinism requirements

Region Type Checking for Core-Java

Region-based memory management offers several important advantages over garbage-collected heap, including real-time performance, better data locality and efficient use of limited memory. The concept of regions was first introduced for a call-by-value functional language by Tofte and Talpin, and has since been advocated for imperative and object-oriented languages. Scope memory, a lexical variant of regions, is now a core feature in a recent proposal on Real-Time Specification for Java (RTSJ). In this paper, we propose a region-based memory management system for a core subset of Java. Our region type analysis can completely prevent dangling references and thus is ready to cater for the no-dangling requirement in RTSJ. Our system also supports modular compilation, which is an important feature for Java, but was missing in recent related work.Singapore-MIT Alliance (SMA

Multi-Facets Contract for Modeling and Verifying Heterogeneous Systems

Critical and cyber-physical systems (CPS) that exist in large industries, such as nuclear power plants, railway, automotive or aeronautical industries are complex heterogeneous systems. They are complex because they are open, perimeter-less, often built by assembling various heterogeneous and interacting components which are frequently reconfigured due to requirements. Consequently, the modeling and analysis of such systems is a challenge in software engineering. We introduce a new method for modeling and verifying heterogeneous systems. The method consists in: equipping individual components with generalized contract, ordering these contracts according to given facets, composing these components and verifying the resulting system with respect to the facets. We illustrate the use of the method by a case study. The proposed method may be extended to cover more facets, and by strengthening assistance tool through proactive aspects in modelling and property verification

An Introduction to Pervasive Interface Automata

Pervasive systems are often context-dependent, component based systems in which components expose interfaces and offer one or more services. These systems may evolve in unpredictable ways, often through component replacement. We present pervasive interface automata as a formalism for modelling components and their composition. Pervasive interface automata are based on the interface automata of Henzinger et al, with several significant differences. We expand their notion of input and output actions to combinations of input, output actions, and callable methods and method calls. Whereas interfaces automata have a refinement relation, we argue the crucial relation in pervasive systems is component replacement, which must include consideration of the services offered by a component and assumptions about the environment. We illustrate pervasive interface autmotata and component replacement with a small case study of a pervasive application for sports predictions

Contributions to multi-view modeling and the multi-view consistency problem for infinitary languages and discrete systems

The modeling of most large and complex systems, such as embedded, cyber-physical, or distributed systems, necessarily involves many designers. The multiple stakeholders carry their own perspectives of the system under development in order to meet a variety of objectives, and hence they derive their own models for the same system. This practice is known as multiview modeling, where the distinct models of a system are called views. Inevitably, the separate views are related, and possible overlaps may give rise to inconsistencies. Checking for multiview consistency is key to multi-view modeling approaches, especially when a global model for the system is absent, and can only be synthesized from the views. The present thesis provides an overview of the representative related work in multi-view modeling, and contributes to the formal study of multi-view modeling and the multi-view consistency problem for views and systems described as sets of behaviors. In particular, two distinct settings are investigated, namely, infinitary languages, and discrete systems. In the former research, a system and its views are described by mixed automata, which accept both finite and infinite words, and the corresponding infinitary languages. The views are obtained from the system by projections of an alphabet of events (system domain) onto a subalphabet (view domain), while inverse projections are used in the other direction. A systematic study is provided for mixed automata, and their languages are proved to be closed under union, intersection, complementation, projection, and inverse projection. In the sequel, these results are used in order to solve the multi-view consistency problem in the infinitary language setting. The second research introduces the notion of periodic sampling abstraction functions, and investigates the multi-view consistency problem for symbolic discrete systems with respect to these functions. Apart from periodic samplings, inverse periodic samplings are also introduced, and the closure of discrete systems under these operations is investigated. Then, three variations of the multi-view consistency problem are considered, and their relations are discussed. Moreover, an algorithm is provided for detecting view inconsistencies. The algorithm is sound but it may fail to detect all inconsistencies, as it relies on a state-based reachability, and inconsistencies may also involve the transition structure of the system