The system evaluation objective is to assure that the requirements have been correctly managed through the different stages of the life cycle.
 
Properties analysis and simulation

The research for formal properties is one of the means used for requirement verification and validation. Our approach for critical scenarios derivation can help designers to verify the validity of a logical solution from the dependability point of view.
When the verification of the composed models (system or subsystem level) is done, the simulation can be used to complete the verification in order to validate the properties of the considered system.
These concepts have been used for the elaboration of the European project SYMPASS (embedded systems in rail domain)

Simulation as an evaluation tool

In order to take into account the evolution of models, tools and environment, we have adopted the Model Driven Architecture (MDA) approach that allows making separation between the model and the simulation contexts. We have been interested by the question of simulation confidence. We work on the production of methods in order to guarantee a sufficient level of simulation confidence. This work has been implemented in two ways:

• First, we used the notion of virtual system that consists in encapsulating the formalism as a component, and makes obvious the notion of interface and connector to insure structural and semantic interoperability. This approach will continue with the study of controllability and observability system properties
• The second consists in either using meta-modelling to keep the different models and their own expression, or obtaining a unique model using metamodeling and model transformation. One of the most important results with this last case is the model transformation from PN-ADE to VHDL-AMS and the associated simulation.

System simulation and prototyping

Virtual prototyping is an essential element for system validation. It consists in associating to the simulation, the notion of a visualisation imitating the real system. Virtual prototyping allows a clear understanding of the sequence of raw results. It allows validating the abstraction and approximation, the hierarchy and heterogeneity. The study starts by connecting a simulation to a physical entity through a distributed simulation. It has shown that the process synchronisation mechanism of a distributed simulation can be used to insure the temporal coherence. It is focused on methods and tools for co-simulation, distributed or not.

The proposed prototyping must be considered on a wide understanding because it can also concern evaluation of mixed architectures (hard/soft). Indeed, using together co-simulation and prototyping in an MDA context, leads to the evaluation of hard/soft architectures and to incremental implementation. After having demonstrated the feasibility of this approach (modelling a system with Petri nets, transforming the model into VHDL, and implementing it on an FPGA microcontroller target), this work is presently followed by a research on methods and tools for co-simulation in the aim of evaluating architectures, automatic and  semi-automatic soft/hard partitioning, and implementation on physical targets (SOC for example).