Integrated design of residual generation and evaluation for fault detection of networked control systems

In this paper, integrated design of residual generation and evaluation is proposed to fault detection (FD) of networked control systems. Both the imperfect network transmissions and the sampling effects are considered under the assumption that no stochastic network model is available. By deriving a linear discrete time-varying system equivalent to the sampled plant, the continuous-time behaviors of disturbances and faults during sampling intervals are captured. Moreover, the effects of unknown but bounded packet delays and dropouts in the controller-to-actuator link are described by uncertain input delays with finite number of possibilities. A parity relation-based FD module with multiple residuals is constructed for the derived system model. For the constructed FD module, the set of undetectable faults is obtained from integrated analysis of residual generation and evaluation and then designed to achieve its worst-case minimal geometrical size while guaranteeing zero false alarms. Simulation results on a networked three-tank system are provided to show the merits of the proposed integrated design approach. Copyright (C) 2015 John Wiley & Sons, Ltd.