Research on 3D trajectory tracking of underactuated AUV under strong disturbance environment

Underactuated AUV (automatic underwater vehicle) possess a lower number of actuators than its degrees of freedom, which helps to conserve energy and improve maneuverability in complex underwater environments. However, the complex and variable disturbance environment under the sea makes the control of underactuated AUVs extremely difficult, so it is urgent to study controllers with strong disturbance capability. This paper focuses on 3D trajectory tracking under strong disturbance environment. The 5-DOF underactuated AUV kinematics and dynamics equations are established and simplified by adopting appropriate assumptions. The NDOB (nonlinear disturbance observer) combined with sliding mode control is utilized to complete the 3D trajectory tracking of underwater unmanned cluster under strong disturbance environment. The effectiveness of the control algorithm is verified through multiple sets of simulation experiments. Through the comparison of experimental data, the anti-disturbance ability of the algorithm proposed in this paper is more than 80% higher than that of the adaptive sliding mode controller under strong disturbance environment. This research provides an effective solution for 3D Trajectory tracking of underactuated AUV, which is of great practical significance for improving the efficiency of underwater exploration, ocean observation, and underwater operations.