Exact fault recovery for asynchronous sequential machines with output bursts

This paper presents an enhanced fault tolerant control strategy for a class of input/output asynchronous sequential machines (ASMs) in which output feedback takes the form of bursts. We design a corrective controller that counteracts any unauthorized state transition occurring to the ASM. As the controlled machine is steered on a feedback path, uncertainty about the goal state is reduced by the information that output bursts provide. Hence the use of output bursts in the correction procedure allows the controller to conduct more refined fault recovery than the case of accessing unit output characters as feedback. We present the existence condition and design procedure for a controller that achieves exact fault recovery, and provide an illustrative example to demonstrate the procedure of controller synthesis.