Distributed Formation Tracking Control for Underactuated AUVs based on Polar Coordinates Transformation with Disturbances

This paper presents a new cooperative controllers for multiple underactuated autonomous underwater vehicles (AUVs) to track a horizontal trajectory with unknown time-varying environmental disturbances, while the AUVs hold a desired formation. A polar coordinates transformation is used to tackle the control problem caused by unactuation of the sway dynamic. Based on the transformation and graph theory, we propose a virtual distributed formation tracking controller with a undirected topology in the kinematics model. Then, the actual controller is developed in the dynamic motion based on the command filtered backstepping. And the disturbance observer is constructed to provide the estimates of unknown time-varying disturbances. It is proved that the designed control law can guarantee the uniform ultimate boundedness of all signals in the multi-AUVs. Simulation results are given to validate the effectiveness of the proposed control strategy.