Abstract: Considering the nonlinear damping and nonlinear restoring moment, an equation of marine vehicles roll in random wave is established. A stabilizer based on control-moment-gyro is also presented to attenuate roll motion. According to the characteristics of the gyro, the nonlinear dynamics equations of the ship and the gyro-stabilizer system are established, and a variable control gain method is used to control the precession angle of the gyro, so that a desired control moment can be generated and the ship roll will be restrained effectively. Taking a fishery administration ship as the research object, the effectiveness of the controller to suppress the ship roll motion is simulated under the random wave excitation as the perturbation in different sea state. When the significant wave height is 1 m and 4 m, the roll of the ship is reduced by 83.64% and 79.04% respectively. The simulation results show that the gyro stabilizer can attenuate the ship roll motion effectively.

Key words: Gyro-stabilizer, Nonlinear roll of marine vehicles, Random wave, Variable gain control