Position control of surface vessel with unknown disturbances

This paper describes dynamic position control of surface vessel with disturbances such as waves and wind. A smooth time-varying controller is proposed that performs both in presence and absence of disturbances. Using this controller, position of the vessel converges to neighborhood about zero that can be made arbitrarily small. In addition, if disturbance is small, orientation of the vessel converges to neighborhood about zero that is as small as possible. Effectiveness of proposed control law is demonstrated by simulation.