Influence of the propeller on motion performance of HUGs

Among the existing outstanding gliders, Hybrid Underwater Gliders (HUGs), which are often equipped with a propeller as the propulsion system, are the typical ones with better performance. However, studies on the HUG showed that the glider was very easy to yaw left or right, while the pure buoyancy-driven gliders didn't show such problem. The most possible reason may be from the propeller. In this paper, to investigate this problem, the six degrees of freedom (6-DOF) kinematic model and dynamic model of PETREL-II was established using Newton-Euler approach, in which the viscous fluid forces and control inputs were expressed in independent forms. And the motion performance of the HUG was simulated using MATLAB codes. Results indicated that the deviating behavior of the HUG did be caused by the torque from the propeller. Four schemes were proposed to reduce the impact of the propeller and to improve motion stability of the HUG. It was deemed that Scheme II is the optimal method to eliminate the influence of propeller and improve the motion performance.