Ship parametric excitation rolling motion and its fin stabilizer control based on chaos analysis

Parametric excitation rolling can lead to dangerously large rolling motions, endangering the ship, cargo and crew. To decrease the influence caused by parametric resonance, stability of ships in longitudinal waves was analyzed using Lyapunov characteristic exponents and power spectrum. The mechanism of parametric excitation rolling was explained by chaos theory. The condition of chaos in parametric rolling was discussed, the safe and unsafe regions of target ships were identified. Then the fin stabilizer controller is designed by using Backstepping closed-loop gain shaping algorithm and simulation tests are carried out under certain disturbances. The simulation results show that the control effects are very effective for the elimination of chaos in the ship parametric rolling system and the effects have satisfactory robust stability.