Extending the Real-Time Maude Semantics of Ptolemy to Hierarchical DE Models

This paper extends our Real-Time Maude formalization of the semantics of flat Ptolemy II discrete-event (DE) models to hierarchical models, including modal models. This is a challenging task that requires combining synchronous fixed-point computations with hierarchical structure. The synthesis of a Real-Time Maude verification model from a Ptolemy II DE model, and the formal verification of the synthesized model in Real-Time Maude, have been integrated into Ptolemy II, enabling a model-engineering process that combines the convenience of Ptolemy II DE modeling and simulation with formal verification in Real-Time Maude.Comment: In Proceedings RTRTS 2010, arXiv:1009.398

Distributed Simulation of Heterogeneous and Real-time Systems

This work describes a framework for distributed simulation of cyber-physical systems (CPS). Modern CPS comprise large numbers of heterogeneous components, typically designed in very different tools and languages that are not or not easily composeable. Evaluating such large systems requires tools that integrate all components in a systematic, well-defined manner. This work leverages existing frameworks to facilitate the integration offers validation by simulation. A framework for distributed simulation is the IEEE High-Level Architecture (HLA) compliant tool CERTI, which provides the infrastructure for co-simulation of models in various simulation environments as well as hardware components. We use CERTI in combination with Ptolemy II, an environment for modeling and simulating heterogeneous systems. In particular, we focus on models of a CPS, including the physical dynamics of a plant, the software that controls the plant, and the network that enables the communication between controllers. We describe the Ptolemy extensions for the interaction with HLA and demonstrate the approach on a flight control system simulation

SCCharts: The Mindstorms Report

SCCharts are a visual language proposed in 2012 for specifying safety-critical reactive systems. This is the second SCCharts report towards the usability of the SCCharts visual language and its KIELER SCCharts implementation. KIELER is an open-source project which researches the pragmatics of model-based languages and related fields. Nine case-studies that were conducted between 2015 and 2019 evaluate the pros and cons in the context of small-scale Lego Mindstorms models and similar projects. Par-ticipants of the studies included undergraduate and graduate students from our local and also external facilities, as well as academics from the synchronous community. In the surveys, both the SCCharts language and the SCCharts tools are compared to other modeling and classical programming languages and tools

SCCharts: The Railway Project Report

SCCharts is a visual language proposed in 2012 for specifying safety-critical reactive systems. We present the results of the first medium sized SCCharts case-study. The case-study was conducted in the context of the railway project performed by students at the Kiel University in the summer term 2014. The railway project is a regularly occurring student training project that teaches principles of concurrent cyber-physical systems on a complex live model railway demonstrator. This report presents details of the first medium size SCCharts models created during the project. We explain what additional language extensions to SCCharts were necessary and how they were implemented. To handle performance issues that arose while developing the controller, compiler enhancements became necessary and are evaluated here. Furthermore, the participants completed a survey at the end of the project to confirm the goals that the SCCharts language and our SCCharts tool chain are suitable to build complex controllers. In the survey, the participants compared both, the SCCharts language and our SCCharts tools, with other modeling and classical programming languages and tools

Simulating sensor networks

Tese de mestrado em Informática, apresentada à Universidade de Lisboa, através da Faculdade de Ciências, 2010Nos últimos anos, as redes de sensores sem fios conheceram um grande impulso em variadas ´áreas, nomeadamente na monitorização industrial e ambiental e, mais recentemente, na logística e noutras aplicações que envolvem processos de negócio e a chamada Internet das Coisas e dos Serviços. Contudo, e apesar dos avanços que se têm verificado tanto em termos de hardware como de software, estas redes são difíceis de programar, testar e instalar. A simulação de redes de sensores é frequentemente utilizada para testar e depurar aplicações para redes de sensores, pois permite testar a execução de das aplicações em ambientes virtuais. Esta tese aborda um problema que diz respeito a testar estas redes através de simulação: a definição (manual) de modelos. A nossa abordagem aponta para a geração de modelos de simulação directamente a partir de aplicações redes de sensores, em particular, modelos para o simulador VisualSense criados a partir de aplicações escritas em Callas, uma linguagem de programação para as redes de sensores. Para tal, criamos uma ferramenta capaz de gerar modelos que ´e paramétrica pelos modelos de rede e modelos sensores da rede que se pretende modelar, e ainda por um conjunto extensível de parâmetros de simulação. As nossas experiências mostraram resultados encorajadores na simulação de redes de grande escala, uma vez que conseguimos executar simulações com até 5000 nós. À medida que as redes de sensores sem fios começam a ser utilizadas em processos de negócio, a informação que recolhem do ambiente tem cada vez mais influência no decurso dos fluxos de trabalho associados aos processos de negócio. De um modo geral, os testes levados a cabo em fluxos de trabalho fazem uso de informação gravada em fluxos de trabalho executados previamente, tornando difícil testar o sistema como um todo. Em alternativa, e como uma segunda proposta desta tese, propomos testar fluxos de trabalho através da incorporação de resultados obtidos nas simulações das aplicações das redes de sensores. Além de cobrir os casos cobertos pela primeira abordagem, esta técnica permite testar novos fluxos de trabalho, bem como as mudanças ocorridas num determinado fluxo de trabalho por acontecimentos no ambiente.In recent years, Wireless Sensor Networks have gaining momentum in several fields, notably in industrial and environmental monitoring and, more recently, in logistics. However, and in spite of the advances in hardware and software, Wireless Sensor Networks are still hard to program, test, and deploy. Simulation is often used for testing and debugging sensor networks because they allow us to perform deployments in virtual environments. This paper addresses a key problem of testing such networks using simulation: (manual) model definition. Our approach is to generate simulation models directly from WSN applications, in particular, VisualSense simulator models from applications written in Callas, a programming language for WSN. For that purpose, we create a model generator tool that is parameter sable by network and sensor templates, and by an extensible set of simulation parameters. Our experiments show encouraging results on simulating large scale networks, as we are able to handle WSN with as many as 5000 nodes. As Wireless Sensor Networks begin to play some role in business processes, the information they gather from the environment influences the execution of workflows. Generally, the tests carried out on these systems make use of recorded information in earlier workflow executions, making it difficult to test the system as a whole. Alternatively, and as a second proposal of this thesis, we propose testing such workflows by incorporating results obtained from the simulation of sensor network applications. Besides covering the situations described in the first approach, this technique allows the testing of new workflows, as well as the changes made to a given workflow by events in the environment

Tools for Real-Time Control Systems Co-Design : A Survey

This report presents a survey of current simulation tools in the area of integrated control and real-time systems design. Each tool is presented with a quick overview followed by a more detailed section describing comparative aspects of the tool. These aspects describe the context and purpose of the tool (scenarios, development stages, activities, and qualities/constraints being addressed) and the actual tool technology (tool architecture, inputs, outputs, modeling content, extensibility and availability). The tools presented in the survey are the following; Jitterbug and TrueTime from the Department of Automatic Control at Lund University, Sweden, AIDA and XILO from the Department of Machine Design at the Royal Institute of Technology, Sweden, Ptolemy II from the Department of Electrical Engineering and Computer Sciences at Berkeley, California, RTSIM from the RETIS Laboratory, Pisa, Italy, and Syndex and Orccad from INRIA, France. The survey also briefly describes some existing commercial tools related to the area of real-time control systems

Co-simulation of Event-B and Ptolemy II Models via FMI

In the framework of model-based design formal modelling, verification and simulation of safety-critical systems are supported by several methods and tools. Interfacing these tools often becomes challenging for heterogeneous systems. The FMI standard enables integration of different simulation tools through artefacts called Functional Mockup Units (FMU) [1]. The FMI standard is mainly based on the concept of scalability of the simulation as it deals with heterogeneous cyber-physical systems. The combination of discrete behaviour and continuous-time environment is a common case study in hybrid simulation. Moreover, another aspect of the FMI is to enhance the capability of the tools. Thus, a collaborative simulation between the Rodin [2] and Ptolemy [3] is leveraged by both platforms. While Event-B is enhanced by new models of computation of Ptolemy,Ptolemy leverages the expressivity and properties validation (theorem/invariant proofs) implemented by Event-B. The main rationale of the co-simulation between Event-B and Ptolemy relies on the intention of dissimilarity and complementarity of the modelling viewpoints. Event-B provides formal modelling by specifying conditions, actions and properties that manage discrete event behaviour, whereas Ptolemy gives a structural viewpoint in terms of actors, components or functions with relation to concerned behaviour. Thus, the association of Ptolemy and Event-B puts together structural and formal aspects.This paper focuses on the collaborative simulation of models supported by both Ptolemy II and Event-B. The ongoing work consists of the design of a diagrammatic co-simulation surface and its application to a controller case study

ACTRESS: Domain-Specific Modeling of Self-Adaptive Software Architectures

International audienceA common approach for engineering self-adaptive software systems is to use Feedback Control Loops (FCLs). Advances have led to more explicit and safer design of some control architectures, however, there is a need for more integrated and systematic approaches that support end-to-end integration of FCLs into software systems. In this paper, we propose a tooled approach that enables researchers and engineers to design and integrate adaptation mechanisms into software systems through FCLs. It consists of a domain-specific modeling language that raises the level of abstraction on which FCLs are defined, making them amenable to automated analysis and implementation code synthesis. The language supports composition, distribution and reflection, thereby enabling coordination and composition of multiple distributed FCLs. Its use is facilitated by a modeling environment, ACTRESS, that provides support for modeling, verification and complete code generation. We report on its application to a concrete adaptation case study and also discuss resulting properties

Analysis and identification of possible automation approaches for embedded systems design flows

Sophisticated and high performance embedded systems are present in an increasing number of application domains. In this context, formal-based design methods have been studied to make the development process robust and scalable. Models of computation (MoC) allows the modeling of an application at a high abstraction level by using a formal base. This enables analysis before the application moves to the implementation phase. Different tools and frameworks supporting MoCs have been developed. Some of them can simulate the models and also verify their functionality and feasibility before the next design steps. In view of this, we present a novel method for analysis and identification of possible automation approaches applicable to embedded systems design flow supported by formal models of computation. A comprehensive case study shows the potential and applicability of our method11212