Structural Design of Supreme Controller with Uncontrollable Transitions.

This paper proposes an iterative control policy to design a less restrictive and admissible Petri net (PN) controller for a Discrete Event System (DES) with uncontrollable transitions, when a maximally permissive controller is not obtains by. This paper exploits a structural supervisory control method, avoiding reachability graph. This exciting method addresses the controllability condition of the desired functioning PN to define it as General Mutual Exclusion constraints (GMEC), which leads to design place invariant-based controller. The controller is non-admissible if one control place is connected to uncontrollable transition. To obtain an admissible PN controller, if such a controller exists, authors propose constraints transformation, which is computationally complex, while the controller arcs displacement approach is unsystematic. Based on it, we develop the idea to iterate the structural supervisory control method, to ensure that control place is connected to controllable transition. Through this, it was found that the displacement of arcs is systematic and the controller is less restrictive and admissible, namely the supreme controller. The results indicate that the linear constraints are never violated through the firing of uncontrollable transitions. The finding of this work may serve to evaluate the structural optimality of the controller, in order to perform it practically. [ABSTRACT FROM AUTHOR]