Adaptive Fuzzy Sliding Mode Controller for Dynamic Positioning of FPSO Vessels

Considering the unknown time-varying dynamic model parameters and the interference of marine environmental forces, it is necessary to estimate the uncertainties to make control effects better. This paper proposes an adaptive fuzzy sliding mode controller (AFSMC), comprises of the sliding mode control and an adaptive fuzzy logic. It is proposed for the dynamic positioning system to keep the vessel at the desired position and heading. The dynamic positioning control law is designed by the sliding mode control method. The adaptive fuzzy logic is used to approximate the uncertainties induced by unknown time-varying dynamic model parameters and the environment disturbances. The stability of the system is proved by Lyapunov theory. The adaptability, effectiveness and the robustness of the proposed controller is verified through a series of simulation tests in different cases and compared with the ordinary sliding mode controller (SMC) for a floating production storage and offloading (FPSO) vessel.