Research On Control Methods Of SWATH Ship

The Small Waterplane Area Twin Hull (SWATH) ship is one kind of the high-performance ships because of its superior seakeeping characteristics, few resistance at middle and high speed, large weather-deck area, etc. It can satisfy the needs under various kinds of condition, and be paid more and more attention by many countries. Since 1980s, our country began to research and design the SWATH ship. But the major work is done on the structure, hydrodynamic and the motion performance. And the research of motion stability control technology was neglected. Therefore, it has most important significance to research the stabilizing fin of the SWATH ship and its control method. On the one hand, it could fill the technology blanks of this field in our country; on the other hand, the multi-hull ship technology based on the catamaran has been paid more and more attention by the world. The multi-hull ship' pitch and heave motion are also unstable at high speed. So, grasping the control methods of SWATH ship movement stable can provide the technology assurance for the research of the multi-hull ship, in the future.At first this paper established the equations of motion for coupled heave and pitch, and the hydrodynamic coefficients associated with the equations of motion were obtained with the strip method developed by Lee. Then, using regular waves of different frequency as the disturbance input of the SWATH ship to study the SWATH ship' pitch and heave motion performance in different frequency regular wave. Thirdly, analyzed and researched which factors such as the size and location of stabilizing fin can effect the motion performance and the stabilize characteristics of the SWATH ship. Established the basic theory of design and fixing stabilizing fin of SWATH ship. Finally, designed an optimizing controller, from the simulation results, it could be seen that this method reduced most of the vertical motion response of SWATH ship.