A decentralized fault prognosis scheme for nonlinear interconnected discrete-time systems

This paper deals with the design of a decentralized fault diagnosis and prognosis methodology for interconnected nonlinear dynamical systems. For each subsystem, a local fault detector (LFD) is designed based on the measured local states of the subsystem alone. A fault is detected by using a local residual signal generated via the measured local subsystem states and the LFD estimates states. Each LFD consists of an adaptive online approximator to compensate the fault dynamics from local and non-local faults. Due to the interconnection nature of the large scale system, the non-local faults propagate to other subsystems and therefore are detected thus eliminating the need to measure and transmit the states of other subsystems. Fault detectability condition is also included for both local and non-local faults. Upon detection, faults local to the subsystem and to other subsystems are isolated. In addition, the proposed scheme provides the time to failure (or remaining useful life) information by using local measurements alone. Simulation results verify the effectiveness of the proposed decentralized fault diagnosis and prognosis scheme.