Global stabilization of autonomous underactuated underwater vehicles in 3D space

In this paper, global asymptotic stabilization of an autonomous underactuated underwater vehicle (AUUV) is investigated, where the number of actuators of the AUUV is less than the vehicle's degrees of freedom. The model that is considered describes both the kinematics and dynamics of the AUUV with six degrees of freedom and four actuators. To cope with the underactuation characteristics of AUUV a state transformation is proposed to change the model of the vehicle to a cascade nonlinear system. Then a switching control algorithm is proposed where the stability of the whole vehicle is guaranteed based on the stability properties of cascade systems. To illustrate the performance of the proposed approach, simulation results are provided.