Review of longitudinal motion and controls of ships on waves

  Objectives  With the advancement of the global economy and science, intellectualization is the inevitable trend of ship development. Applying active controls to a ship's ride control system for the purpose of improving hydrodynamic performance is a current research emphasis.

  Methods  First, the study of the algorithm of ship's motion is summed up, then the input signal of appendage is analyzed, and the development of the appendage's control method based on the calculation result of the motion is further summarized on this basis. Finally, the development status of longitudinal damping appendage's model test is summarized.

  Results  The analysis shows that the longitudinal motion response is reduced up to 60% by the appendages, and the anti-longitudinal motion effect is improved by more than 20% compared with passive control. In theory, the active control system based on robust control and predictive control has a better longitudinal attenuation effect than the traditional PID control system. However, the research of the model test is mainly based on PID control due to its simplicity and directness.

  Conclusions  Introducing robust control or predictive control into the practical application of appendage control systems is one of the most important development directions of intelligent ship research.