Research On Fin Stabilizers With Fin-lift/Fin-angle Integrated Control And Lift Control Strategy

Fin stabilizers are most frequently and successfully used active anti-rollequipments.The effectiveness of roll reduction can be more than 90 percent.Thefin angle feedback control is implemented in fin stabilizers system mainlyaccording to static hydrodynamic characteristic,but the dynamic hyddrodynamicproperty is more complicated during the reciprocating motion of fins.In addition,there are serious nonlinearity and uncertainty relationship among the fin and bilgekeel,the fin and hull,and fin pitch,etc.All these factors have harmful toanti-rolling effect,so the lift feedback control method is proposed.The thesis is derived from project 211 of Harbin engineering universityduring the 10th five-year plan:Lift feedback controlfin stabilizers.The anti-rolling principle of ship and the fins employment mechanism areintroduced firstly,the merits of the lift feedback control fin stabilziers are alsoanalyzed based on the faulted fin angle fin stabilizers.How to measure the liftforce in actual running is much important,the main influenced factors areparticularly analyzed aiming to the lift sensor,combinating the current researchsituation at home and abroad.The fin angle feedback control is widely used at the present time,thoughthere are still some flaws to be existed.The research on the lift feedback control ison the stage of experiments.For improving the lift fin stabilizer system,the finstabilizer with fin-lift/fin-angle integrated control was put forward.Aiming to the lift fin stabilizer test bed in Harbin Engineering University,themulti-sensor data fusion model of the control method with fin-lift/fin-angleintegrated was built applying information fusion technology,which also canperfect the measured lift force in fin stabilizers system.The construction methodwas in-depth study,and the feasibility was verified too.Signals collection,treatment and fusion arithmetic are mainly researched during the multi-sensor data fusion process,which are both decided the fusionaccuracy and control effect.The wavelet de-noising technology was applied todeal with all signals in the process of fusion,which was based on the fusion modelwe built.Relying on the constructed principle of the fusion model withoptimalizing weighted,all collected signals were decomposed by wavelettransform,all layers of the decomposed signals were then denoised by thresholdvalues,and both the decomposed low-frequency signals were fused by theiroptimalizing weights,and then the new lift force is reconstructed.The anti-rollingeffect of the lift fin stabilizer system used this data fusion arithmetic was verifiedby simulation.The lift instruction controller in the lift fin stabilizer system is discussed inthe thesis,the fuzzy-PID controller we applied to aim at the nonlinearity of thecontrol object.And for amending the dynamic and stability state performance,thefuzzy subcontroller is introduced too with quantizing and scaling factorsamending online.The theoretical analysis and experimental simulation of the liftfin stabilizer system with the complex fuzzy controller were given out,as a result,the system has upstanding adaptability and robustness,and the anti-rolling effectis improved too.