Adaptive fuzzy output feedback stabilization control for the underactuated surface vessel

This paper designs an adaptive fuzzy stabilization controller for the underactuated surface vessel in the presence of unknown time varying environment disturbances and input saturation. By combining adaptive fuzzy system and auxiliary dynamic function, a stabilization control scheme is developed via vectorial backstepping technique and Lyapunov direct method. To begin with, based on the diffeomorphism equivalent transformation, the stabilization problem of underactuated surface vessel can be transformed into the stabilization analysis of two subsystem. Further, the adaptive fuzzy system is employed to approximate the uncertain term induced by the unknown time varying environment disturbances in the control law. In particularly, an auxiliary dynamic function is exploited to deal with the input saturation. It is proved that the proposed adaptive fuzzy output feedback controller can stabilize the vessel to desired equilibrium origin, while guaranteeing the uniform ultimate boundedness of all closed loop signals in the underactuated system. Finally, simulation results are given to demonstrate the effectiveness of the proposed control approach.