Adaptive Finite-Time PI Sliding Mode Trajectory Tracking Control for Underactuated Hovercraft With Drift Angle Constraint

Considering the sailing characteristics and difficult maneuverability of hovercraft, the three degree-of-freedom (DOF) mathematical model cannot describe effectively the motion of hovercraft. Therefore, a mathematical model of four-DOF motion of hovercraft is established. This paper addresses the trajectory tracking problem of the hovercraft with finite-time convergence to equilibrium point, model uncertainty, external disturbance and drift angle constraint based on the four-DOF model. A novel robust tracking controller is proposed by combining finite-time observer with adaptive sliding mode control to solve the problem of the finite-time convergence and handle approximation error. In order to ensure the safe navigation of the hovercraft, a safety constraint auxiliary system is designed to restrain the drift angle in real time. Furthermore, a finite-time observer is designed to estimate and compensate model uncertainties and external disturbances. We show that under the proposed control scheme, all tracking errors can converge to zero in finite time, the drift angle can be constrained in real time and all closed-loop signals are guaranteed to be bounded. Finally, the numerical simulation results show the effectiveness of the proposed method.