New improvement approaches to H∞ controller designs based on fuzzy observers for T-S fuzzy systems with time-varying delay

This paper provides an improved result over that in (X.Liu. and Q.Zhang, Automatica, 2003) and (Y.Yuan. and W.Che, Control and Decision, 2005) for the problem of observer-based H-infinity control for nonlinear systems with time-varying delay in Takagi-Sugeno (T-S) fuzzy model. It contributes in three aspects: (i)The present result is less conservative than that in (Y.Yuan. and W.Che, Control and Decision, 2005); (ii) The present strict LMI method is a single step approach which overcomes the drawback of a two-step approach in (Y.Yuan. and W.Che, Control and Decision, 2005); (iii) The matrix dimensions are largely reduced compared with the corresponding ones in (Y.Yuan. and W.Che, Control and Decision, 2005).