Event-trigger NMPC for 3-D trajectory tracking of UUV with external disturbances

In this paper, a novel Three-Dimensional (3-D) trajectory tracking method based on Event-triggered Nonlinear Model Predictive Control (ENMPC) is designed for an Underwater Unmanned Vehicle (UUV) with external disturbances. Firstly, the 5-Degrees of Freedom (5-DoF) model of UUV is represented by both kinematics and dynamics. After that, a Nonlinear Model Predictive Control (NMPC) algorithm is designed for the 3-D trajectory tracking of UUV, and the feasibility of the control method and the stability of the closed-loop system are proved, which are further verified by simulation experiments. Then, an event-triggered mechanism is introduced on the basis of NMPC algorithm, which reduces the amount of calculation iterations without affecting the 3-D trajectory tracking performance. Finally, the simulation results verify the feasibility and effectiveness of the proposed algorithm. Compared with the Traditional Model Predictive Control (TMPC) and NMPC algorithm, the ENMPC strategy can effectively reduce the amount of calculation iterations and improve the tracking efficiency.