Adaptive-sliding-mode trajectory tracking control for underactuated surface vessels based on NDO

摘要

In this paper, an adaptive sliding mode underactuated surface vessel trajectory controller based on disturbance observer is designed. Considering the influence of parametric perturbation in the ship model and external environmental disturbance, the chattering problem of the sliding mode controller is improved and the accuracy of system tracking is also improved. The perturbation of the model parameters and the external disturbances are regarded as time-varying compound disturbance in this paper. The nonlinear disturbance observer is used to estimate the time-varying compound disturbances on line and the equal amount of compensation is added to the controller to achieve the purpose of suppressing the interference. In order to solve the problem of chattering in the traditional sliding mode controller, the boundary layer theory is introduced and an adaptive method is adopted to adjust the thickness of the boundary layer in real time so as to reduce the chattering and improve the control accuracy. Finally, the effectiveness of the proposed method is verified by numerical simulation.