FTUDE based event-triggered NMPC for trajectory tracking of dynamic positioning ships under input constraints

This study investigates the trajectory tracking problem of dynamic positioning ships under input constraints, model uncertainties and time-varying environmental disturbances. Firstly, the unmodeled nonlinear dynamics of the dynamic positioning (DP) ship and the external disturbances are integrated together as lumped uncertainties, and a fixed-time uncertainty and disturbance estimator (FTUDE) based on an integral sliding mode is developed to compensate effects of the lumped uncertainties. Then, the event-triggered nonlinear model predictive control (ENMPC) trajectory tracking control strategy for DP ship is established by introducing the event-triggered mechanism into nonlinear model predictive control, which can reduce the computational resource consumption while ensuring control effectiveness. The feasibility and input-to-state stability of ENMPC with FTUDE have been proved. Comparison simulations have been conducted to validate the effectiveness and superiority of the proposed method.