For stabilization of zero speed ships active anti roll tanks and gyro stabilizers are used. Because of anti roll tank limitations on working frequencies gyro stabilizers are proposed. A nonlinear model for ship is used to simulate hydrodynamic forces. Wave’s disturbances are considered as non-parametric uncertainty. A sliding mode controller is used for roll stabilizing. A nonlinear h infinity controller is designed to reduce the disturbance effects on the ship. The designed sliding mode controller uses more control energy from h infinity controller. Instead roll reduction of the sliding mode controller is grater from the other one. The main concept of the used model in this article was taken from an authority that ship model data estimated from real ship with Halcyon gyro actuator. Roll reduction increases by applying designed controllers in wide range of sea states. In addition nonlinear effects intended in this article. Simulation results based on Jonswap wave spectrum demonstrates the performance of robust system in confrontation with wave perturbations.

Keywords: Sliding mode controller, Nonlinear H infinity controller, Ship roll, Gyro, Stabilisation

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