Sliding mode controller design for supercavitating vehicles

The supercavitating vehicle are capable of achieving high speed through cavitation reduction technology, however, the model of the vehicle is inferior stability and nonlinear dynamics. Inferior stability is mainly reflected in the sensitivity to the interference. The strong nonlinear characteristics embodies in the special planing force caused by water-cavity interaction on the aft part of the vehicle. Regarding to the inferior stability and strong nonlinear dynamics of the supercavitating vehicle, sliding mode controllers are presented in this paper. By using boundary sliding mode control, boundary of nonlinear planing force is estimated. In order to reduce the switch gain of the boundary sliding mode controller, the sliding mode controller based on disturbance observer is proposed. The disturbance observer is designed. The stability of the system is proved by Lyapunov stability theorem. Evaluations results through simulation on tracking performance of the nominal and uncertainty system with time delay show the effectiveness of the control method.