Adaptive fuzzy dynamic surface tracking control for uncertain time-delay nonlinear systems with unknown control directions

This work investigates the adaptive tracking control problem for uncertain nonlinear systems with input delay and unknown control directions (UCDs). The proposed solution employs the Pade approximation to compensate for the ID, while incorporates the Nussbaum gain function (NGF) technique is manage UCDs. Fuzzy logic systems (FLSs) are employed to approximate unknown uncertain nonlinear dynamics, with corresponding adaptive laws for parameter estimation. Furthermore, an adaptive fuzzy DSC strategy is developed to achieve the desired tracking. It is proves that all signals in the closed-loop system are bounded and that the tracking error can converge to a small neighborhood of zero. Finally, two simulation examples are provided to verify the effectiveness of the designed control law.