Comments on "Constrained controller design of discrete Takagi–Sugeno fuzzy models"

In the above paper, Chang et al. (Fuzzy Sets and Systems 133 (2003) 37) proposed an interesting approach to design the fuzzy static output feedback controller with a common observability Gramian. However, since it involves a nonlinear output function, the results obtained are not correct for the general case. This note intends to circumvent these problems by modifying the approach proposed in Chang et al. (Fuzzy Sets and Systems 133 (2003) 37).