  Even if model-driven techniques have been enabled the centrality of the
models in automated development processes, the majority of the industrial
settings does not embrace such a paradigm due to the procedural complexity of
managing model life cycle. This paper proposes a semi-automatic approach for
the completion of high-level models of critical systems. The proposal suggests
a specification guidelines that starts from a partial SysML (Systems Modeling
Language) model of a system and on a set of requirements, expressed in the
well-known Behaviour-Driven Design paradigm. On the base of such requirements,
the approach enables the automatic generation of SysML state machines
fragments. Once completed, the approach also enables the modeller to check the
results improving the quality of the model and avoiding errors both coming from
the mis-interpretation of the tool and from the modeller himself/herself. An
example taken from the railway domain shows the approach.
