LAUSR

This brief investigates the problem of trajectory tracking control for dynamic positioning vessels under unknown and time-varying sea loads. A novel event-based prescribed performance control (PPC) scheme is proposed to address this problem. Firstly, an integral disturbance observer (IDO) is introduced to estimate the sea loads, and a new-type performance function (PF), which has advantages of flexible shape and appointed-time convergence, is proposed to form the funnel envelops for the trajectory tracking errors. Subsequently, by employing the IDO and the new-type PF, a dynamic event-triggered control policy is designed in the PPC framework to achieve the assigned trajectory tracking mission in an appointed-time with guaranteed performance bounds and less operating frequency of the actuator. The salient feature of the derived controller is that it can achieve a trade-off between the tracking performance and actuators’ operating frequency in a well-balanced way, which is of great importance for practical engineering applications. Finally, simulation results are given to show the effectiveness of the proposed method.