Distributed Fault Diagnosis for Continuous time nonlinear systems: The input-output case

In this paper, new results on distributed fault diagnosis of continuous time nonlinear systems with partial state measurements are proposed. Following an overlapping decomposition framework, the dynamics of a nonlinear uncertain large-scale dynamical system are described as the interconnections of several subsystems. Each subsystem is monitored by a corresponding Local Fault Diagnoser: a set of local estimators, based on the nominal local dynamic model and on an adaptive approximation of the interconnection and of the fault function, permit to derive a local fault decision. A consensus-based protocol is used in order to improve the detectability and the isolability of faults affecting variables shared among different subsystems because of the overlapping decomposition. A sufficient condition assuring the convergence of the estimation errors is derived. Time-varying threshold functions guaranteeing no false-positive alarms and theoretical results containing detectability and isolability conditions are presented.2013 Elsevier Ltd. copyrigh