Event-Triggered Generalized State Observer-Based Finite-Time Fault-Tolerant Control of Underwater Vehicles With Input Saturation

This article addresses a finite-time trajectory tracking control problem for autonomous underwater vehicles with parametric uncertainties, external disturbances, thruster faults, and saturation. First, considering the unpredictable oceanic environment with the thruster faults and model uncertainties, an event-triggered finite-time generalized extended state observer (ETFTGESO) is developed to estimate the synthetic failure and unmeasured velocities simultaneously. Triggered position data is used as feedback in the correction terms of ETFTGESO, which consequently reduces unnecessary communication or computational burden. The observer order is expanded by two additional states, which enhance the estimation accuracy. Then, a homogeneous output feedback controller is proposed to achieve finite-time stability of the vehicle. To improve the convergence rate of the position and velocity trajectories, the finite-time control law is updated by integrating a homogeneous integral sliding surface. Rigorous theoretical analysis verifies fast convergence, the influence of control parameters on bounded stable region, and accurate dynamic positioning. Finally, numerical simulations are carried out to demonstrate the superiority of the proposed control scheme.