Fault-Tolerant Control of Nondeterministic Input/Output Automata subject to Actuator Faults

This paper presents concepts dealing with fault-tolerant control of discrete-event systems (DES) modeled by Input/Output (I/O) automata. It answers the question how to reconfigure the controller of a plant which is subject to actuator faults. The notion of the redundancy degree is addressed and formalized in an I/O automata framework. The reconfigurability condition which is essential in a reconfiguration scheme is investigated and a new method for checking the feasibility of a specification for a faulty system is introduced. A control design method, from which a deterministic baseline controller can be derived from a nondeterministic specification automaton, is presented. The diagnoser is assumed to be able to detect and identify actuator faults which occurred in the system. An example demonstrates the applicability of the concepts.