Roll Control Technique Research Of Surface Ship In Extreme Sea Condition

For the complexity of ocean environment, the motion of ship is a very complex movement. Roll is considered as the most significant motion in all of it.In order to control the roll of ship, a mathematics model of roll control by rudder or fin was developed in the thesis. All hydrodynamic parameters in the model were calculated by STF strip method. For evaluation the roll control effectiveness of various nonlinear control algorithm and forecast the seakeeping performance, a simulation model in time domain was developed. Correction of nonlinear damping and nonlinear restore moment of ship was concerned in the model. The result of ship model test in high sea condition indicated that the accuracy of prediction by the use of model developed in this paper was better than traditional frequency analysis method.From the result of preparatory simulation and take account of the character of valve-controlled hydraulic steering system, Several control algorithm were simulated, such as LQG, MLD, Bang-Bang and self adaptive GPC. From the results we focus the Generalized predictive control (GPC) to be the control algorithm for ship model rudder roll damping test. The performance of GPC was analyzed.The result from model test in wave basin shown the roll reduce effectiveness is satisfied while the times of switch of rudder is not so frequently. And this provided a practicable control algorithm to make the use rudder roll damping system in full-scale ship.Roll and pitch controlled by means of a high efficient flap slant rudder was introduced and discussed in the end of the thesis.