Modelling and motion simulation of an underwater glider with independently controllable main wings

The purpose of this research is to provide an underwater glider with high manoeuvrability. This paper deals with the modelling and motion simulation of an experimental vehicle named `ALEX' as a test-bed for an underwater glider with independently controllable main wings. ALEX was designed to realise high performance manoeuvrability. The main wings, rudder, elevator, movable balance weight and vent-blow valves can all be controlled by an on-board microcomputer system. The simple cylindrical shape with a NACA0050-shaped nose cone and main wings with the NACA0009 section were found to be suitable for modelling and estimating the hydrodynamic forces. A computational fluid dynamics (CFD) technique was introduced to estimate the hydrodynamic forces acting on the ALEX glider such as lift and drag under various conditions for the angles of incidence for both wings and environmental flow, i.e., the angle of attack. Equations of motion were also formulated for the modelling of ALEX. Motion simulation was conducted to clarify the characteristics of the `underwater glider with independently controllable main wings' in comparison with a conventional `underwater glider with fixed main wings'. Results of the motion simulations were compared with the actual experiments. Several kinds of motion simulations in diving corresponded well with the motions of ALEX actually observed in the experiment tank.