Advanced Methodologies for Real-Time Discrete Event Modelling and Simulation

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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).