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Practical Cascade Control for Supercavitating Vehicle

Supercavitating vehicles, compared with other underwater vehicles, have amazing high speeds. However, the supercavitating vehicles have the unique tail-slap phenomenon in motion due to the lack of buoyancy and the existence of the planing force. In addition, there are large and unpredictable uncertainties in the hydrodynamics of the supercavitating vehicle because of the approximate understanding of this kind of mechanics. All these together impose big challenge to the controller design. In this paper, the longitudinal model of the supercavitating vehicles is adopted to carry out control investigation. A cascade control strategy is designed to coordinate depth control and avoid the planing force. In the outer-loop, the depth is controlled by the classical proportional-integral-derivative (PID) method; in the inner-loop, the control of longitudinal velocity and pitch rate use the linear active disturbance reject control (LADRC). The feasibility of the method is verified by mathematical simulation. The simulation results demonstrate the effectiveness and the superiority of the proposed strategy.