Robust adaptive fuzzy output feedback control strategy for uncertain perturbed nonlinear system

For uncertain multiple-input multiple-output (MIMO) nonlinear system, a robust adaptive fuzzy output feedback control scheme is proposed. The augmented system structure includes uncertain disturbance resulting from exosystem while the unmeasurable errors of the augmented system are obtained by passing the observation error vector to a set of state variable filters. With a switching gain adaptation method to alleviate chatters, a robustifying term compensates for fuzzy approximation errors and external disturbances. Overall stability analysis for the closed-loop system concludes that the robust adaptive fuzzy output feedback controller with the composite adaptive update laws and the switching gain adaptation achieves asymptotic convergence to a desired trajectory in presence of uncertainties and external disturbances.