Discrete integral sliding mode multiobserver for simultaneous estimation of states and sensor faults: Application on a chemical reactor

The present work proposes an integral sliding mode multiobserver (ISMMO) for nonlinear systems in the presence of sensor faults. By augmenting the sliding manifold with an integral term, the sliding mode multiobserver exhibits low-pass filtering dynamics that attenuate high-frequency chattering while preserving the stability of the estimation error dynamics. For the simultaneous estimation of the states and the sensor faults, these faults are considered as auxiliary state variables, thus an augmented multiobserver structure based on a discrete-time decoupled state multimodel is constructed. The stability conditions are presented in terms of Linear Matrix Inequalities (LMIs) using a common Lyapunov function. The superiority and effectiveness of the proposed ISMMO are illustrated through an experimental validation on a chemical reactor and a comparative study.