Improved observer-based adaptive fuzzy tracking control for MIMO nonlinear systems

In this paper, a stable observer-based adaptive fuzzy controller which combines a sliding mode and an adaptive Proportional Integral (PI) controllers is developed for a class of nonlinear Multiple Input Multiple Output (MIMO) systems with unknown parameters and in presence of external disturbances. The free parameters of the adaptive fuzzy controller are tuned on-line based on the Lyapunov approach. The overall adaptive fuzzy scheme guarantees the uniform ultimate boundedness of all the closed-loop signals as well as the tracking errors. The validity of the proposed approach is shown by computer simulations of a two-link robotic manipulator.