Periodic observer design for non-linear model with periodic parameters via Takagi-Sugeno form

In this paper, we propose a periodic observer design for a class of non-linear models in the discrete Takagi-Sugeno form with periodic parameters. The adopted framework is based on the Lyapunov theory and uses the linear matrix inequality (LMI) formalism. Only the stability of the estimation error is considered. The main goal is to reduce the conservatism of the stabilization conditions using some particular Lyapunov functions.