Prescribed performance trajectory tracking fault-tolerant control for dynamic positioning vessels under velocity constraints

• A trajectory tracking method with prescribed performance is proposed for dynamic positioning vessels by artfully constructing the intermediated error variable, and combining with appointed-time performance function, time-invariant and time-varying asymmetric barrier Lyapunov functions. The derived controller can restrain not only the trajectory-level but also the velocity-level tracking errors from exceeding the corresponding performance constraints, meanwhile the tracking operation can achieve in a pre-appointed time. • Neural network and adaptive techniques are incorporated to construct a fault-tolerant trajectory tracking controller, which can not only estimate thruster faults, but also provide better robustness against model uncertainties and external disturbance. This paper investigates the prescribed performance trajectory tracking control problem for dynamic positioning vessels in the presence of velocity constraints and thruster faults. By using a structurally simple error transformation, the issue of guaranteeing prescribed transient and steady state tracking performance is converted to a general state-constraint problem, which together with the velocity constraints form a trajectory tracking control problem with full-state constraint. Time-invariant and time-varying asymmetric barrier Lyapunov functions are adopted to realize the constraint of trajectory-level and velocity-level errors. Within this setting, neural network and adaptive techniques are incorporated to construct a fault-tolerant trajectory tracking controller, which can not only estimate thruster faults, but also provide better robustness against model uncertainties and external disturbance. Finally, tracking control task for dynamic positioning systems is carried out to illustrate the merits of the proposed method.