Simulation of Systems of Systems

Complex systems have become a particular area of interest in the past years and the study of such systems, seen as a whole, has yielded many and varied approaches. One of the difficulties frequently encountered is that such systems display emergence, i.e. their global effect or behavior is greater than the sum of the behaviors of their agents and depends strongly on the interactions between these agents. Simulation is a very interesting approach for this study, since it allows focusing on the dynamic study of the system, thus pointing out these behaviors and interactions. Moreover, it is particularly interesting for aerospace systems, which are nowadays clearly studied as complex systems, since these systems are generally poor candidates for real experimentation, due to many diverse reasons (e.g. cost for space systems, criticality in terms of human life for air transport systems, etc.). Hence, they must be studied quite thoroughly before their full design or realization is possible and simulation plays an important part in this. This paper presents methods that can be used to study complex systems by simulation, as well as some techniques that take into account their specific nature, in particular distributed simulation, a paradigm quite intensively used at Onera. It also deals with the difficulties that may be encountered in setting such large simulations up and also addresses the problem of data in such a large simulation, from the handling to the exploitation.