Robust Anti-pitching Control Of High-speed Multihull Ship

The high-speed multi-hull ship uses streamlined struts to connect the drainage body and the main part,which not only has the advantages of spacious deck area,but also has the advantages of low sailing resistance,good wave resistance,maneuverability,strong carrying capacity,good lateral stability,etc.Research objects widely concerned by shipbuilding industries in various countries.However,the vertical stability of high-speed multi-hull ships is poor,and they are easily disturbed by random wind,waves,and currents when sailing at high speeds at sea,resulting in excessive amplitude of heave and pitch movements,which seriously affects the seaworthiness of multi-hull ships..Therefore,designing effective high-speed multi-hull ship pitch reduction control has important theoretical value and practical significance.High-speed multi-hull ship anti-rolling reduces the heave and pitch motion amplitude by installing two types of T-foil and flaps appendages.Certainty,and the anti-rolling appendage T-foil and flaps have strict input constraints,the current single anti-rolling control method is not effective.This paper starts from three aspects: strong coupling,uncertainty,and input constraints of high-speed multi-hull anti-rolling.The main contents are as follows:(1)Establish the hull coordinate system of the multi-hull ship,on this basis,establish the vertical kinematics model based on the rigid body momentum theorem and the momentum moment theorem;study the force generated by the T-foil and the flaps on the multihull ship Modeling of sea wave disturbances to obtain random sea wave disturbance inputs acting on multi-hull ships;using CFD method to solve hydrodynamic parameters faster and more accurately.(2)Aiming at the problems of strong coupling and parameter uncertainty in the heave and pitch motion of high-speed multi-hull ships,a decoupled robust longitudinal anti-roll control method is proposed.A multi-hull ship model with T-foil and flaps as anti-rolling appendage was established,which was transformed into a decoupled pitch and heave control model through mathematical transformation,and a time-varying coupling term.The proportional-derivative method and the equivalent minimum noise bandwidth are used to design the decoupling pitch and heave controller,which simplifies the control complexity.On this basis,the time-varying coupling term is used as the system uncertainty,and an expanded observer is designed for online estimation and compensation.Finally,the integrated total control quantity is used to obtain the angle of attack of the T-foil and the flaps through the anti-roll appendage control distribution matrix,and the stability of the closed-loop system is proved based on the Lyapunov stability theory.Through simulation and experiment to verify the effectiveness of the proposed algorithm,heave is reduced by 20%-35% and pitch is reduced by 40%-50%.(3)In view of the strong coupling between the pitching and heave motions of high-speedmulti-hull ships,and the strict input constraints of the anti-rolling appendage T-foil and the flaps,a predictive control anti-rolling method based on a finite-time observer is proposed.A finite-time expansion observer is designed to quickly estimate the time-varying coupling of pitch and heave,and the state quantities of pitch and heave,and a theoretical proof of the convergence of the finite-time observer is given.Aiming at the decoupled time-varying pitch and heave motion models,a single-step predictive control is proposed to obtain an adaptive control amount to improve the system's anti-roll performance and ensure that the anti-roll appendage meets the constraints.(4)To further improve the real-time performance of predictive control anti-shake,a random explicit predictive control anti-shake method is proposed.The random motion model of the high-speed multi-hull ship is established,and the prediction and estimation of the multi-hull ship's pitch / heave state is converted into the state average prediction model through the Kalman filter prediction estimation.In order to reduce the online optimization calculation of predictive control and improve real-time performance,an explicit predictive control combining offline design and online query is proposed,and the input state stability of the closed-loop system is analyzed based on Lyapunov theory.The effectiveness of the proposed method was verified by simulation.The results of the study showed that pitch reduction was reduced by 50% and heave reduction by 35%,which significantly improved the longitudinal motion performance of the multihull.