On the use of macroactions in supervisory control theory for monitoring purpose

In this paper, some extensions are proposed to model and to synthesize supervisory control strategies ensuring compensation and return within operational safety (OpS) context. OpS attempts to design optimally suited reactivity control over critical failure so as to ensure degraded functioning. Control provided by OpS integrates techniques which permit continuing production under failure, subject to specific accepted risks. Thus, in the proposed structure, at the occurrence of a critical failure, the reactivity loop allows a degraded functioning which replaces the nominal one, until the return action stabilizes the system. To make the specification easier, the macroactions freeze, release and force are advantageously used within a hierarchical framework. The proposed formalization defines these macroactions in the supervisory control theory context. The controllability and the existence condition of high and low levels supervisors are formally stated