Trajectory Tracking Controller Design for Underactuated AUVs based on Adaptive Robust Control

In this paper, the trajectory tracking problem for underactuated Autonomous underwater vehicles (AUVs) is investigated. First, a nonlinear 4-DOF AUV model is adopted, considering the unknown parameters and external distances. Two control objectives and corresponding error dynamics are established according to different tracking errors. To achieve accurate AUV tracking control, an adaptive robust control strategy is proposed, combining the backstepping control ideology. This controller could adaptively estimate uncertain model parameters and disturbances recursively and compensate for the estimation errors robustly. Theoretical analysis demonstrates that the proposed control scheme can ensure system stability, enhance the transient response, and give great trajectory tracking performance, which is validated again by the numerical simulations.