  This paper proposes an intelligent fault-tolerant control (FTC) strategy to
tackle the trajectory tracking problem of an underwater vehicle (UV) under
thruster damage (power loss) cases and meanwhile resolve the actuator
saturation brought by the vehicle's physical constraints. In the proposed
control strategy, the trajectory tracking component is formed by a refined
backstepping algorithm that controls the velocity variation and a sliding mode
control deducts the torque/force outputs; the fault-tolerant component is
established based on a Grasshopper Optimization Algorithm (GOA), which provides
fast convergence speed as well as satisfactory accuracy of deducting optimized
reallocation of the thruster forces to compensate for the power loss in
different fault cases. Simulations with or without environmental perturbations
under different fault cases and comparisons to other traditional FTCs are
presented, thus verifying the effectiveness and robustness of the proposed
GOA-based fault-tolerant trajectory tracking design.
