Observer-based Saturated Control for Dynamic Positioning Ship with Mismatched Disturbance and Input MRS

In this article, an observer-based dynamic surface saturated control law is adopt for dynamic positioning(DP) ships subject to input magnitude and rate saturation(MRS), mismatched disturbance and unknown disturbance. The mismatched disturbance caused by the model transformation or measurement uncertainties is analyzed and two disturbance observers are introduced while the steady performance is improved. By using dynamic surface control technique, an observer-based control strategy is developed without solving partial differential equations. In addition, integrated augment MRS model and auxiliary system, the effect caused by input MRS is handled while the better transient performance is achieved. Then, the stability of the closed-loop system is proven via Lyapunov technique. Finally, simulations demonstrate the advantageous and effectiveness of the method in this paper comparing with previous works.