Synthesis of optimal fault-tolerant supervisor for discrete event systems

In an earlier work (Q. Wien et al., 2007), (2007), we introduced a framework for fault-tolerant supervisory control of discrete event systems and presented a necessary and sufficient condition for its existence. Here we propose an approach to synthesize an optimal fault-tolerant supervisory controller. Given a discrete event plant with both faulty and nonfaulty behaviors, an optimal fault-tolerant supervisor we synthesize enforces a set of behaviors in which (i) a recovery is guaranteed within a bounded delay following any fault, (ii) the enforced set of nonfaulty behaviors are maximized, and (iii) the enforced set of faulty behaviors prior to the recovery are minimized. An example is given to illustrate the approach.