Disturbance observer based finite-time trajectory tracking control of unmanned surface vehicles with unknown dead-zones

In this paper, a finite-time trajectory tracking control approach is proposed for an unmanned surface vehicle (USV) with unknown dead-zones and unknown disturbances. External disturbances can be observed exactly by a robust homogeneous differentiator with finite-time convergence. Based on the information of the bounds of the dead-zone slopes as well as treating the time-varying inputs coefficients as system uncertainties, a finite-time controller for trajectory tracking of an USV is eventually addressed via the non-singular terminal sliding mode control technique. Moreover, the boundary layer method with a novel saturation function is employed to reduce the chattering and to ensure that tracking errors can be rendered to zero in a finite time. Simulation results demonstrate the effectiveness of the proposed approach.

1 Introduction

In recent years, USV has received considerable attention, which is widely used in military, missions search and rescues, etc. [1]. For example, In [2] an adaptive recursive design technique is developed for a parametrically uncertain nonlinear plant describing the dynamics of a ship. The authors in [3] investigated an accurate and economic control optimization method for ships heading control system. Although the USV control design has achieved some progress, there are still some challenging tasks need to be solved.