| High-speed multihull ships have good lateral stability,seakeeping and maneuverability,which is one of the hotspots in the field of ship research.However,the slender side body of highspeed multihull ship causes large longitudinal overturning moment and small restoring moment during high-speed navigation,which causes the pitching and heave of high-speed multihull ship to change sharply and greatly under harsh sea conditions.It is easy to cause stalling,bow slamming and other phenomena,which seriously affects seaworthiness.Therefore,how to effectively restrain the amplitude of heave and pitch motion has become the focus of research on high-speed multihulls.In order to improve the seaworthiness of high-speed multihull ships,T-foil and flap attachments are installed on the high-speed multihull ship and a reasonable anti-pitching reduction control strategy is designed to achieve coordinated anti-pitching reduction.The motion model of high-speed multihull ships has problems such as coupling,uncertainty,time-varying,and being interfered by strong waves.The anti-pitching signal estimation and anti-pitching control of highspeed multihull ships are the key to the overall anti-pitching performance.This paper focuses on signal estimation and anti-pitching stabilization control,the main research contents of the thesis are as follows:(1)To study the reaction force generated by the two types of pitch appendages of T-foil and flap on high-speed multihull ships,and to establish the control force and control moment model of T-foil and flap.On this basis,a complete vertical motion model of the high-speed multihull is established to analyze the coupling of heave and pitch motion.At the same time,the power spectrum analysis of the sea wave interference during high-speed navigation is carried out,and data fitting and superposition are used.The method is to obtain the interference force and the interference moment of random waves acting on the high-speed multihull ship.(2)Aiming at the problem that heave velocity and pitch angular velocity cannot be directly measured,and the heave and pitch motion are affected by non-Gaussian random wave interference and noise,the maximum entropy Kalman filter estimation of multihull under non-Gaussian noise is proposed.The robust maximum entropy criterion is used as the optimal performance,and the pitch reduction control signal and covariance matrix are obtained based on the prior estimation of the state and covariance matrix.Then the fixed-point iterative algorithm is used to update the posterior estimation to improve the estimation accuracy of the anti-pitching control signal.(3)Aiming at the problem of excessive pitch and heave motion of high-speed multihull ships during navigation,a finite-time anti-pitching control method is proposed.The T-foil and flap are used as the vertical control model of the multi-hull ship with anti-pitching appendages and transformed into a decoupled pitch and heave motion model.A finite-time expansion observer is designed to estimate the time-varying coupling terms of pitch and heave motion online,and perform real-time compensation control.On this basis,for the decoupled pitch and heave motion models,a finite-time feedback control law is proposed to improve the system’s anti-pitching performance and interference suppression ability,and give a closed-loop system stability analysis.The effectiveness of the proposed algorithm is verified by digital simulation,the heave is reduced by 20%～35%,and the pitch angle is reduced by 40%～50%.(4)In order to further optimize and improve the pitch performance,a one-step predictive control anti-pitching stabilization is proposed.The expansion state observer of the pitch and heave channels is designed to estimate the lumped uncertainty items of the pitch and heave channels online,and feed forward compensation is performed to improve the robustness of the anti-pitching stabilization control.The optimization goal of one-step predictive control is proposed.The onestep prediction error is given based on the nominal model of the high-speed multihull.The onestep predictive analytical control law is obtained according to the necessary conditions of optimization,and the stability analysis of the closed-loop system is given.The validity of the proposed algorithm is verified by digital simulation. |
