Nonlinear observers with H∞ performance for sensor fault detection and isolation: a linear matrix inequality design procedure

In this paper the problem of detecting and isolating sensor faults on a certain class of nonlinear systems is considered. A procedure to design a bank of extended H∞ observers for sensor fault detection and isolation (FDI) is carried out: each observer is composed of an open loop nonlinear part replicating the system dynamics and a linear feedback action. Sufficient conditions for the synthesis of the feedback action are provided in terms of linear matrix inequality (LMI) feasibility problems. Constraints on the position of the observer poles are added to fasten the residual generation dynamics and to avoid low-damped and/or high-frequency modes. Numerical results on the longitudinal dynamics of a commercial aircraft are provided to show the practical applicability of the proposed technique.