Finite-time disturbance-rejecting control of supercavitating vehicles during water entry

Supercavitating vehicles suffer from complex dynamics and strong disturbances during high-speed water entry, making precise control challenging for conventional methods. This paper proposes a composite control strategy based on a finite-time extended state observer (FTESO) and finite-time sliding mode control (FTSMC) for depth and attitude regulation. A longitudinal motion model is established and transformed into an error system. The FTESO estimates and compensates for lumped disturbances, while an exponential fast terminal sliding mode surface combined with a higher-order reaching law improves convergence speed and reduces chattering. Lyapunov analysis proves finite-time stability of the closed-loop system. Simulation results show that the proposed method achieves superior depth tracking, attitude control, disturbance rejection, and control smoothness compared with NTSMC combined with LESO, demonstrating enhanced robustness and engineering applicability.