Saturated Adaptive Fuzzy Fixed-Time Nonsingular Integral Terminal Sliding-Mode Control of AUVs.

This article investigates the trajectory tracking control issue of autonomous underwater vehicles (AUVs) subject to dynamic uncertainties, external disturbances, and input amplitude and rate saturations. Initially, two new stable systems with fixed-time convergence are developed, and their upper bounds of settling time and convergence regions are thoroughly analyzed. Building on these systems, an enhanced fast nonsingular integral terminal sliding-mode (NITSM) surface and a new virtual control law are designed, respectively.