A design of polynomial fuzzy controller with disturbance observer

The so-called lumped disturbance in this paper includes modelling error, external disturbance, unmodelled dynamics and parameter perturbations. As the plant model, polynomial fuzzy model is employed, because it is more general than the widely used T-S fuzzy model. In this paper, a new fuzzy disturbance observer (FDO) is proposed to handle the lumped disturbance, and the estimate of the disturbance is used directly to synthesize a part of controller along with the regular control input where such a disturbance is not considered. As a result, a set of the conditions in the manner of the sum of squares (SOS) for the asymptotical stability of the closed-loop system is provided.