Modeling And Control Of Submarine Low Speed Motion For Missile Lauching Conditions

A special working condition missile launching shows the combat effectiveness of submarine with launching depth about 30 meters,and now the hull will be greatly impacted in a short time,having a great impact on the submarine attitude.In order to make the submarine attitude stable after missile launching and meet the need of launching the missile again,simplification on submarine six motion model,analysis on missile launching force and interference force,and the corresponding control strategy are studied in this paper.Considering the time of measuring hydrodynamic coefficients and the requirement of real-time control,48 items of hydrodynamic coefficients in submarine motion equation are simplified the sensitivity index of hydrodynamic coefficients and verified.Firstly,the motion parameters under typical and missile launching conditions are selected,and then the direct threshold method,analytic hierarchy process(AHP)and threshold clustering cascade simplification strategy(DPK)based on principal component analysis are used to simplify the model,analytic hierarchy process(AHP)is a threshold classification method based on composite sensitivity index,DPK method classifies hydrodynamic coefficients by K-means after using principal component analysis to reduce dimension.DPK method has smaller errors in motion parameters under typical working conditions and missile launching condition,especially in missile launching condition,with the error of overtaking depth and overturning angle about 0.016% and 0.21% respectively,much smaller than that obtained by the other two simplified strategies,showing a good simplification effect.The sea water environmental disturbance force includes near-surface disturbance force,buoyancy change caused by sea water density change and hull compression.The attitude parameters are calculated under the consideration with or without those three disturbance forces.The simulation results show that in the depth of submarine at 30 meters,there is no error in the attitude parameters when considering the near-surface disturbance force,which can be neglected,while the submarine attitude changes greatly when considering the sea water density and the compression force,which can not be neglected.Based on the simplified six-degree-of-freedom model,the submarine motion fuzzy-PID control strategy under missile launching condition is studied.The experimental results show that the fuzzy PID control satisfies the attitude requirement of the re-launcher,under single-shot and mutiple-shot conditions,compared with the conventional PID control,the depth error under fuzzy PID control is less than that of PID,outperforming PID under both working conditions.Then,a submarine motion model predictive controller is constructed,and the control effect of quadratic programming and particle swarm optimization is compared.The error of the latter is 1.1% larger than that of the former,and the operation efficiency of the former is 319.68 times higher than that of the latter.Therefore,the quadratic programming predictive control and the fuzzy PID control are selected for missile launching simulation comparison.The results show that the maximum relative error of the depth controlled by fuzzy PID is 1.67 times and 85.67 times of that controlled by the predictive control under the conditions of single-shot and mutiple-shot,respectively.At this time,the predictive control strategy is far superior to the fuzzy PID control strategy.In this thesis,a simplified submarine model for missile launching and model predictive control based on quadratic programming optimization method are proposed,providing a theory base for the submarine motion control under missile launching and promoting the development of national defense.