Nonlinear dynamics and control of underwater supercavitating vehicle

Supercavitation can be viewed as a phenomenon that could boost the speed of underwater vehicles. The vehicle is entirely surrounded by the cavity while it is traveling under water in the supercavitation stage. Thus, the vehicle actually travels in air and bears very small skin friction drag. Hydrodynamic behaviors and stability of the supercavitating vehicle do not depend on the hydrodynamic coefficients as in the case of a fully wetted underwater vehicle. The contact of the aft of the vehicle with the cavity wall gives rise to the nonlinear planing force, and it is really hard to control and maneuver a supercavitating vehicle. The hydrodynamic forces applied on all parts of the supercavitating vehicle were analysed. The efficiency of the fin while it is traveling under water was computed. The nonlinear dynamic model of supercavitating vehicle was completed. The controller was designed by use of nonlinear switched control strategy.