Adaptive fuzzy tracking control for a class of MIMO nonaffine uncertain systems

In this paper, a novel fuzzy adaptive controller is investigated for a class of multi-input multi-output (MIMO) nonaffine systems with unknown control direction. An equivalent model in affine-like form is first derived for the original nonaffine system by using a Taylor series expansion. Then, a fuzzy adaptive control is designed based on the affine-like equivalent model. The adaptive fuzzy systems are used to appropriately approximate the unknown nonlinearities, while the lack of knowledge of the control direction being closely related to the sign of control gain matrix is handled by incorporating in the control law a Nussbaum-type function. A decomposition property of the control gain matrix is used in the controller design and the stability analysis. The effectiveness of the proposed fuzzy adaptive controller is illustrated through simulation results.