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

Abstract

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.