Adaptive and Coloured Structured Petri-Nets for Description, Analysis and Synthesis of Hierarchical Control and Reliability of Flexible Cells in Manufacturing Systems

We present a methodological approach to the analysis and synthesis of the control of Flexible Cells in Manufacturing (F.C.M.). An F.C.M. can be described by a three levels modelization: the production tools the direct automatic-control of the operative system and the hierarchical level to parameter the working conditions. Adaptive coloured and structured Petri-nets are used to model the “Control System” with high level of parallelism and its different communications with the “Operative System” and with the hierarchical level by means of a top-down approach. Modelling the changes of working modes, taking the failures into account, adding degraded modes or priorities, parametrizing a flexible production, all these notions could be added to the “Control System” but the command graph would be more cumbersome and unreadable. The notion of an upper hierarchical level enables this problem to be solved. It is more adequate to model this last level in a declarative way which guarantees any “a posterieuri” modification of this level by the user giving the correct requirements of flexibility to the “Operative System”.