Maneuverability and dynamics of autonomous underwater gliders: Study and review of the spiral path maneuver

Underwater Gliders are a class of AUVs that move without a conventional propeller and are known to behave like Dubin's car for point to point traverse (Dubins, 1957). The turning motion or the spiral maneuver hence becomes an important motion trajectory that has to be studied for efficient maneuvering and control of the vehicle. Control of the glider to follow a given path has been extensively studied from control strategies. However, the effect of hull form on maneuvering characteristics has not been researched extensively. This paper reviews the published literature for maneuverability of underwater gliders from the viewpoint of Naval Architecture and hydrodynamics of hull form. The dynamics equation formulation for a glider, hull forms of underwater gliders in use, hydrodynamics coefficients and methods of their estimation are discussed. Further, analysis of spiral maneuver is undertaken for the characteristic variables of the maneuver, namely velocity, turning control inputs and radius of the spiral trajectory. Methods of numerical prediction of a glider executing spiral are discussed. Scope for further research based on the review is proposed.