FDI of disturbed nonlinear systems: A nonlinear UIO approach with SOS techniques

Abstract

This paper presents a novel unknown input observer (UIO) design method for fault detection and isolation (FDI) of a class of nonlinear affine systems with disturbance. By using Lie geometry and sum-of-squares (SOS) theory as the main tools, a simple and systematic design procedure is proposed. Compared with the traditional UIO design, the rank constraint is much relaxed. Meanwhile, we show that the threshold can be easily obtained from a L2 gain result using a SOS formulation.