Trajectory tracking and hydrodynamics of a tethered underwater vehicle based on hybrid grid

Abstract

A coupling hydrodynamic model including a tethered underwater vehicle integrated with three 19 A + Ka 4–70 ducted propellers and PID control algorithm is proposed. The paper focused on the trajectory tracking and hydrodynamic performance of a tethered underwater vehicle under the influence of sea current. The proposed model is solved by Star-ccm+, a commercial software based on the finite volume method, and hybrid grids, including sliding mesh and overset grid, are utilized. The Navier-Stokes equation governs the flow field around a tethered underwater vehicle, and determination of the cable is based on the catenary equation. The six-degrees-of-freedom for a tethered underwater vehicle's motion is also analyzed. The numerical result indicates that the horizontal trajectory of a tethered underwater vehicle is greatly influenced by sea current without adjusting by the control algorithm, while the vertical trajectory controlled by the PID algorithm is influenced little by sea current. The control effect of the ducted propeller decreases as the sea current speed increases. The coupling approach of the hydrodynamic model and PID control scheme is feasible, and provides a new way to analyze the underwater vehicle trajectory.