Research On Control Of Supercavitating Vehicle Based On Feed Back Linearization

The supercavitating vehicle surrounded by gas surface can attain very high speed while it is traveling underwater, because the vehicle has very small skin friction drag. Supercavitation technology can make the torpedo actually fly in the water like a missile. Supercavitation technology makes great achievements in drag reduction but also poses technical challenges in system stability and control. Because the vehicle is surrounded by cavity, its fluid dynamic characteristics have a great changes, the control strategy was also proposed more stringent requirements. The article completes equations of motion according to theorem of momentum and theorem of angular momentum based on the force analysis of the supercavitating vehicle, and makes motor control and attitude control for supercavitating vehicle. The main works are:Complete supercavitating vehicle dynamics modeling. In order to describe the movement of vehicle, the coordinate systems are defined, parameters of the motion are selected, and the transform relationships between the coordinate systems are reckoned. By contrasting the stable navigation programs of underwater supercavitating vehicle, we select the appropriate program. We select the equation of cavity model and research the morphology factors of the cavity. We determine the geometrical model of vehicle, analyse the fluid force and moment. Finally, according to theorem of momentum and theorem of angular momentum, we establish six degree of freedom supercavitating nonlinear dynamic and kinematic equations.Establish vertical motion model and lateral movement without roll motion model of supercavitating vehicle and analyse the open-loop characteristics, dynamic coupling characteristics, manipulation of coupling characteristics of the two models. In the process of establishing models, we simplify motion models according to the relevant guidelines. In the process of establishing lateral movement model, taking into account the influence of the roll angle on the cross-connect between the vertical movement and lateral movement, establishe the lateral motion model without roll when the roll has been effectively controlled.Complete nonlinear control of supercavitating vehicle. Based on dynamic modeling and dynamic analysis of supercavitating vehicle, sliding mode variable structure control and LQR control are used on depth control, pitch control, lateral control and yaw control. Because of the nonlinear, dynamic coupling and control coupling characteristics of the models are serious, the feedback linearization is respectively used on vertical model and lateral motion model without roll. Finally, sliding mode variable structure control and LQR control are compared to analyse.