A fuzzy sliding mode controller for underactuated autonomous underwater vehicles with uncertain time delay

To realized the robust control of underactuated autonomous underwater vehicle with uncertainties of time-delay, un-modeled dynamics and time-varying hydrodynamic parameters, a fuzzy sliding mode controller is proposed, with switching function of variable structure control and its derivative as fuzzy control inputs, and derivative of the variable structure control law as fuzzy control output. The design method of the controller offers a systematical means of constructing a set of shrinking-span and dilating-span membership functions for the controller. A technique to adaptively tune scaling factors of fuzzy controller is presented for better performance of eliminating chattering. The contrast simulation results indicate that the proposed adaptive fuzzy sliding mode controller has better performance. And then the controller is applied to the dive plane control of AUV with parameter uncertainties, un-modeled dynamics and control input time delay. The results demonstrate the effectiveness and robustness of the controller with low control effort.