On reconfiguration-based Fault Tolerance

Fault Tolerance (FT) aims at guaranteeing specified system properties, at least in a degraded sense, under system component faults. Fault Accommodation (FA) - which handles the faulty system - and System Reconfiguration (SR) - which handles the healthy part of the faulty system - are the two possible approaches to FT. This lecture focuses on System Reconfiguration. It presents and analyzes the key role played by the lattice of system configurations, a mathematical framework that also underlies the problem of architecture design. This framework provides useful concepts and tools that will be shown to cover many aspects of Fault Tolerance, both from the design (passive / active / reliable control or estimation laws), and from the evaluation (fault recoverability, fault tolerance effectiveness, components usefulness) points of view.