Advanced Methodologies for Real-Time Discrete Event Modelling and Simulation

实时嵌入式系统是作为与周围环境（交通、自动化建筑等）交互的组件集构建的。它们的正确性和及时性至关重要：系统任务执行的那一刻可能会导致灾难性的后果（对货物或生命）。我们建议进一步研究建模和仿真在实时嵌入式环境中的应用。我们建议使用形式化建模和仿真方法，因为形式化方法可以提供良好的结果，因为用于实时建模和仿真的软件工件具有更高的质量。我们特别关注DEVS形式化的应用，这是一种基于通用动态系统概念的形式化建模和仿真框架。我们建议在实时系统中使用DEVS，使用DEVS理论。尽管最新的DEVS建模技术稳步发展，但现有的用于实时环境的DEVS研究成果都没有考虑到实时应用中的各种复杂问题：容错、传感器复制、瞬态系统过载等。为了解决这一问题，我们将在使用不精确计算和调度方法的基础上推进新技术，提出在瞬态过载下控制退化的新方法（通过将任务划分为强制部分以提供基本结果，可选部分以改进所获得的结果；也可以提供相同任务的多个版本，根据当前负载使用不同的版本）。我们的研究计划的目标是结合各种理论框架，提供一种基于DEVS的不精确实时计算技术。从方法论的角度来看，我们感兴趣的是开发一种使用不精确计算的动态RT DEVS理论。目标是提供安全性，减少开发时间，以及开发模拟的正式框架的优势。仿真结果可用于实时系统的开发。从实际的角度来看，我们希望提供一套工具，可以应用于开发实时软件和模拟硬件在环（需要实时响应）。通过调用适当的执行引擎，我们将提供在逻辑时间（通常的仿真时钟）和实时时间（受限于挂钟时间）中执行模型的能力。

Real-Time Embedded systems are built as sets of components interacting with their surrounding environment (transport, automated buildings, etc.). Their correctness is critical, as well as their timeliness: the moment when system tasks are executed can lead to catastrophic consequences (for goods or lives). We propose advance researching the use of Modeling and Simulation in real-time embedded environments. We propose use a formal modeling and simulation approach as formalized methods can provide good results because the software artifacts used for real-time modeling and simulation are of higher quality. In particular, we focus on the application of the DEVS formalism, a formal modeling and simulation framework based on generic dynamic systems concepts. We propose using DEVS for Real-time systems, using DEVS theory. Although the state-of-the-art in DEVS modeling has advanced steadily, none of the existing DEVS research results applied in real-time contexts consider a variety of complex problems in real-time applications: fault tolerance, sensor replication transient system overloading, and others. We will advance in new techniques to solve this problem, based on the use of imprecise computation and scheduling methods, presenting new methods for controlled degradation under transient overloads (by dividing the tasks in a mandatory part to provide basic results, and an optional part to improve the results obtained; also multiple versions of the same task can be provided, using a different version depending on the present load). The goal of our research program is to combine various theoretical frameworks, providing a technique for imprecise real-time computing based on DEVS. From the methodological point of view, we are interested in developing a theory of dynamic RT DEVS using imprecise computing. The goal is to provide security, reduction in the development times, and the advantages of a formal framework to develop simulations. The results of the simulated system can be applied in the development in the real-time system. From the practical point of view, we expect to provide a set of tools that can be applied to develop real-time software and simulations with hardware-in-the-loop (requiring real-time response). By invoking appropriate execution engines, we will provide the ability to execute models in both logical time (the usual simulation clock) and real time (constrained to wall-clock time).