Finite-time trajectory tracking control for under-actuated unmanned surface vessels with saturation constraint

This article investigates the robust finite-time trajectory tracking control problem of under-actuated unmanned surface vessels (USVs) subject to model uncertainties, saturation constraints, and external disturbances. Firstly, the kinematic and dynamic models of under-actuated USVs are transformed into an equivalent tracking error dynamic by resorting to a novel output redefinition-based dynamic transformation (ORDT). Secondly, a smooth dead-zone operator-based model (DOBM) is introduced to deal with the control input saturation constraints problem. On basis of these, a sliding mode-based controller (SMC) is developed, which possesses the properties of chattering-free and finite-time convergence. Later, Lyapunov stability proved that the proposed control strategy is capable of guaranteeing the boundedness of all closed-loop signals, in spite of the parametric uncertainties, external disturbance, and input saturation constraints. Finally, numerical simulations illustrate the effectiveness of the proposed control approach.

Automated summary

This article investigates the robust finite-time trajectory tracking control problem of under-actuated unmanned surface vessels (USVs) subject to model uncertainties, saturation constraints, and external disturbances. A novel output redefinition-based dynamic transformation method is used to transform the kinematic and dynamic models of under-actuated USVs into an equivalent tracking error dynamic. A smooth dead-zone operator-based model is introduced to handle the control input saturation constraints. A sliding mode-based controller is developed to achieve chattering-free and finite-time convergence. The proposed control strategy is proven to guarantee the boundedness of all closed-loop signals despite parametric uncertainties, external disturbances, and input saturation constraints. Numerical simulations confirm the effectiveness of the proposed control approach.