Adaptive Trajectory Tracking Control for Small Unmanned Underwater Vehicles With Prescribed Performance and Dynamic Compensation

This article is concerned with the trajectory tracking control problem for small unmanned underwater vehicles (UUVs) with dynamic uncertainty, external disturbance, input saturation, and even unmeasured velocities. To guarantee transient and steady-state prescribed performance, a finite-time prescribed performance control (PPC) method is designed for the boundness and convergence of tracking errors, where the desired settling time can be chosen in advance to obtain a fast convergence, instead of existing exponential-time and asymptotic-time convergence. To attenuate the adverse effects of saturation constraints, an energy-efficient smoothing auxiliary system governed by implementing switching functions is formulated to automatically achieve the dynamic compensation, wherein a discontinuous singularity can be completely avoided. Then, both full-state and output-feedback control schemes are developed by incorporating neural networks and first-order filtering into backstepping procedures, and particularly a high-gain observer is employed to recover unmeasured velocities. The closed-loop system is proven to be uniformly ultimately bounded (UUB). Finally, simulation and experimental results validate the effectiveness of the proposed methods.