A design of T–S fuzzy controller with disturbance observer

The so-called lumped disturbance in this paper includes modeling error, external disturbance, unmodeled dynamics, and parameter perturbations. The lumped disturbance and control input do not share the same coefficient matrix in the local Takagi–Sugeno (T–S) fuzzy model. In order to design a proper fuzzy disturbance observer (FDO) and involve the estimate from the FDO into controller to counteract the influence of the disturbance, system equivalence transformation is proposed in this paper. As a result, the conditions for both the asymptotical stability of the closed-loop system and the convergence of estimation error between the FDO and the disturbance are provided in the manner of linear matrix inequalities (LMIs). Also, computer simulations are provided to illustrate the effectiveness of the proposed FDO-based control system. © 2015 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.