The Design Of Embedded Fin Stabilizer And Optimization Of Variable Parameters Controller

All the ships will sway when they are sailing on the sea. The excessive lateral swayhas most influenced the stability. It will affect the safety of products on the ship andreduce the ships’ comfort and diminish some efficiency of the equipment. The directionof the sailing ship will be affected too. So it is important to reduce the excessive lateralsway. Fin stabilizer is one of the equipments in common use. According to theparameters of some ship, the fin stabilizer with embedded fin is designed to reduce thesize of the fin box in the hull. Then the work is done including fulfilling the kinematicsimulation of the fin stabilizer, establishing the model of the fin control system,optimizing the parameters of the controller and researching the simulation of the fincontrol system.Fin stabilizer includes non-retractable fin stabilizer and retractable fin stabilizer.The dimension of the non-retractable ones is limited by ship structure size. Theretractable ones can be taken back in the body of vessel when the fins don’t work.Although it diverts the defect of the non-retractable fin stabilizer, it increases the fin boxin the bull which influences the velocity of ship. To reduce the effect, designing theembedded fin that the small fin can retracts in the big fin is aimed at lessening thedimension of the box. Fin stabilizer includes rotating fin mechanism, retractable finmechanism, embedded fin and fixed mechanism. Besides, the whole fin device isinstalled to simulate the working process of fin. The result shows fin stabilizermechanism meets the requirements accurately.According to the linear rolling motion theory, the ship model is established. Itincludes angular rate gyroscope, amplifier, PID controller, ship speed compensator andwave scale controller, servo system with the electro-hydraulic position feedback. Thewhole control system is accomplished using the parts mentioned above. It will be usedfor optimizing the parameters.In order to increase the property of the control system and reduce the rollingangular of ship, the three parameters of PID controller are optimized through classicgenetic algorithm (abbreviated GA) and new-style GA. Under the invariant seacondition, the control system is simulated using the two groups of the parameters. Fromthe result, new-type GA is better than classic GA and the values by new-style GA arecloser to the truth-values. In addition to this, the controller is applied variableparameters so that the controller is affected not only the initial parameters but also theerror. Under the variant sea condition, the control system is simulated using fixedparameter controller and variable parameter one. In comparison, the system with thevariable parameter controller is slightly better than the fixed parameter one, which explains the variable parameter controller making the system improve its performanceslightly.