Research on a motion-inhibition fuzzy control method for moored ship with multi-robot system

Compared with the conventional mooring arrangements, robot mooring systems have better adaptability to sea conditions, higher operating efficiency and security. Due to strong random disturbances of wave, wind, currents and the mechanism near-singularity induced by the line distribution of mooring robots along the pier, PD control or other conventional control methods for the mooring robots are difficult to obtain a superior motion-inhibition effect. In this paper, a motion-inhibition fuzzy control method for a moored-ship with a kind of multi-robot system is proposed. By analyzing the motion-inhibition effect of the mooring restoring forces and damping forces, a three-dimensional (surge, sway and yaw) mooring force fuzzy controller (MFFC) is developed. Ac-cording to the force mapping relationship from mooring force space to the driving force space, adjustment factors for the outputs of the MFFC are given to decease the largest driving-force of robot actuators induced by the mechanism near-singularity. Numerical simulations are conducted to obtain the motion responses of a 60000DWT bulk carrier moored by a multi-robot mooring system (MRMS) considering different conditions and parameters. The results show that the MFFC can inhibit adaptively the ship motions for different sea conditions.