A novel approach to fault diagnosis for time-delay systems

•A fault tracking approximator based fault diagnosis scheme is proposed.•The fault tracking properties of the fault tracking approximator are investigated.•An extension study to a class of nonlinear time-delay systems is made.•The selection of fault detection threshold is given in terms of theorem.

In this paper, a novel fault detection and identification (FDI) scheme for time-delay systems is presented. Different from the existing FDI design methods, the proposed approach utilizes fault tracking approximator (FTA) and iterative learning algorithm to obtain estimates of the fault functions. Performance of the FTA is rigorously analyzed by investigating its stability and fault tracking sensitivity properties in the presence of slowly developing or abrupt faults for state delayed dynamic systems. A novel feature of the FTA is that it can simultaneously detect and identify the shape and magnitude of the faults. Additionally, an extension to a class of nonlinear time-delay systems is made by using nonlinear control theories. Finally, the applicability and effectiveness of the proposed FDI scheme is illustrated by a practical industrial process.

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