Prescribed performance control for dynamic positioning vessels with a dynamic event-triggered mechanism

This paper addresses the problem of trajectory tracking control for dynamic positioning vessels in the presence of unknown sea loads. Firstly, an integral disturbance observer is introduced to estimate the unknown sea loads, which enhances the estimation accuracy by incorporating an integral term. Then, a novel second-order prescribed performance function combined with a tracking differentiator is proposed. Compared to traditional performance functions, this function can better enforce error constraints. As a starting point, a Non-full-state event-triggered control (NFSETC) scheme and a full-state event-triggered control (FSETC) scheme are designed to achieve trajectory tracking while addressing environmental uncertainty and limited communication resources. Furthermore, a novel full-state event-triggered mechanism, utilizing a dynamic threshold event-triggered strategy with a performance safety evaluation factor (PSEF), is employed for stable control input, low communication consumption, and improved tracking accuracy. It is also proven that both the event-triggered controller and the full-state event-triggered controller do not exhibit the Zeno phenomenon. Finally, numerical simulations are conducted to verify the theoretical findings and effectiveness of the proposed method.