Anti-pitching of high-speed multihull ships based on incremental predictive control

Abstract

In order to enhance the suppression ability of high-speed multihulls against wave disturbance and reduce the amplitude of vertical motion, it is necessary to use two types of appendages, active T-foil and flap, to implement closed-loop anti-pitching. Aiming at the problems of sea wave disturbance and appendages input constraints, an anti-pitching scheme based on incremental predictive control is proposed. First, the vertical coupled motion model of the high-speed multihull ship is established, the frequency-domain and time-domain characteristics of random wave disturbance are analyzed, and the wave disturbance force and moment are estimated based on the integral disturbance model. On this basis, the incremental model of multihull vertical motion that includes the change rate of wave disturbance is used as the prediction model to reduce the influence of the average wave disturbance force and disturbance moment on vertical motion, improve the model prediction accuracy, and introduce the amplitude and change rate of heave and pitch into the objective function to minimize both. At the same time, in order to solve the input constraints of the anti-pitching appendages and reduce the amount of online calculation, the Lagrange multiplier method and the stair-like parameterization strategy are used to derive the analytical anti-pitching predictive control law and analyze the stability of the closed-loop system. The simulation results show that the proposed incremental predictive control effectively reduces the change rate and amplitude of heave and pitch, the heave displacement is reduced by 43.51%, and the pitch angle is reduced by 50.88%.