Predefined-time tracking control for underwater robots

This paper introduces and validates a predefined-time control (PTC) strategy for trajectory tracking of autonomous underwater vehicles (AUVs). In contrast to conventional methods like sliding mode control (SMC), where convergence time is state-dependent and cannot be directly prescribed, the proposed controller guarantees convergence to the desired trajectory within a user-defined time frame, independent of initial conditions. The performance of the PTC is rigorously evaluated against SMC on two representative planar trajectories. Obtained results demonstrate that the proposed method achieves faster and precisely adjustable convergence, particularly with smaller, mission-critical time horizons. While SMC offers robust stability for applications where smooth operation is paramount, the predefined-time approach is particularly well suited for time-sensitive missions. These findings provide a clear comparative framework, aiding practitioners in selecting and tuning controllers based on specific mission requirements, and establish PTC as a promising solution for precision guidance of autonomous underwater vehicles.