A Petri Net based approach for the synthesis of parts' controllers for reconfigurable manufacturing systems

The goal of this work is to address the problem of the synthesis of Petri Nets controllers to design Reconfigurable Manufacturing Systems. Our approach is inspired by supervisory control but proposes to use Petri nets (PN) to model both the plant model and the user specifications. Since Ramadge and Wonham original works [1], many authors have investigated supervisory control problems based on automata formalism. However, finite automata present some drawbacks such as the difficulty to model parallelism, synchronization and resource sharing. The approaches based on this formalism are generally limited by the combinatorial explosion that occurs when attempting to model complex systems. On the other hand, Petri Net is a more powerful tool for modeling parallelization or synchronization, but its uses for synthesis has not been largely investigated. The method developed here is based on the Ghaffari's Region Theory [2] to synthesis control places that are added to the original plant model in order to obtain a closed-loop PN that respect the user specifications. In this study one assumes that the system production is based on cyclic scheduling performed by sharing resources. More specifically the goal is to synthesis on-line resources allocators based on the scheduling of operations that is established off-line by the scheduling task.