Fault-tolerant control of a class of asynchronous sequential machines with permanent faults

In this note, we address a fault-tolerant control scheme for asynchronous sequential machines with permanent faults. The considered asynchronous machine is influenced by faults that change perpetually a portion of its state transition logic. If the asynchronous machine has appropriate analytic redundancy in its reachability, we can design a corrective controller so that the stable-state behavior of the closed-loop system can match that of a reference model despite occurrences of permanent faults. It is assumed that the controller is always fault-free. The existence condition and design procedure for an appropriate controller are presented based on the corrective control scheme. We also provide a controller synthesis example for validating the proposed scheme.