Depth and Attitude Coordinated Control for Supercavitating Vehicle Avoiding Planing Force

Abstract

Supercavitating vehicles have particular high speeds. This unique advantage is obtained by the cavity separation from water to eliminate most drag. However, this may lead to the tail-slap phenomenon and the planing force. In addition, there are large and unpredictable uncertainties in the hydrodynamics of the supercavitating vehicle. All these factors impose a big challenge to achieve satisfactory depth tracking capability. In this paper, a depth and attitude coordinated control strategy is proposed for the longitudinal dynamics in order to realize depth tracking without planing force. The timely adjustment of the attitude ensures a small vertical speed which can be far away from the threshold value that causes the planing force. By designing the cascade control structure, the depth is regulated by proportional control to generate the pitch command for the attitude loop controller. The vertical speed and the pitch angular rate are both controlled by using the linear active disturbance reject control to guarantee sufficient accuracy and robustness. The simulation results demonstrate the effectiveness and the superiority of the proposed strategy.