Simple Dynamic Positioning Control Design for Surface Vessels With Input Saturation and External Disturbances

Abstract

This brief addresses the dynamic positioning (DP) control problem of surface vessels with input saturation and external disturbances, and a simple DP control law is proposed. First, a saturation handling model and a dynamic compensation system are designed to deal with input saturation. Then, an exponentially convergent disturbance observer is constructed to approximate the external disturbances. Moreover, to guarantee the asymptotic stability of the DP closed-loop system and reduce the design complexity of the DP control law, a simple auxiliary control law is designed by combining the hyperbolic tangent function. Notably, combined with LaSalle’s invariance principle, a DP system stability analysis strategy is constructed, which ensures that the DP system can be asymptotically stable, even if the derivative of the scalar function proving the stability of the DP system is semi-negative definite. Finally, the numerical simulation results demonstrate the effectiveness of the proposed DP control law.