Adaptive Output Feedback Control of Underactuated Marine Surface Vehicles Under Input Saturation

This study addresses the tracking control issue of underactuated marine surface vehicles (UMSVs) with parameter and external uncertainties, input saturation, and unmeasurable velocity. An adaptive output feedback control scheme is developed without assuming the fore-aft symmetry of the hull. First, a state observer is developed to estimate the unmeasurable velocity. Next, the UMSV model is transformed into an integral cascade form using the hand position approach to overcome the design difficulties caused by the underactuated feature and asymmetric hull characteristics. Then, an adaptive auxiliary dynamic system is designed to solve the problem of input saturation caused by actuator constraints. In addition, the Lyapunov theory is applied to demonstrate the capability of the proposed control scheme to ensure the boundedness of the observation and tracking errors in the control system. Finally, the effectiveness of the developed control scheme is verified through simulation.