Event Feedback Supervision for a Class of Petri Nets With Unobservable Transitions

In this paper, we propose a method to design an on-line event feedback supervisor (EFS) for a class of Petri nets whose augmented unobservable subnets are acyclic forward synchronization and backward conflict-free (FSBCF) nets. In more detail, an FSBCF net is an ordinary Petri net in which each place has at most one output transition, and each transition has at most one input place. The designed EFS is able to compute a set of transitions that need to be forbidden based on the current observation of the system. In particular, the EFS is maximally permissive, i.e., it ensures that the controlled system never enters into illegal markings while minimally restricting its behavior. Finally, we use an example to illustrate the effectiveness of the proposed method.