Active Motion Control of High-Speed Vessels in Waves by Hydrofoils

摘要

This paper considers motion control of fully submerged hydrofoils in waves. The change of lift force due to the orbital motion of fluid particles is included as time-varying disturbance in the equation of coupled heave-pitch motion, and the corresponding state space equation is derived. Several control algorithms, including PID, LQR, and sliding mode control are applied for regular and irregular wave conditions, and the resultant motion responses are compared. The results are compared with existing experimental data to observe the effectiveness of each algorithm. Moreover, to observe the robustness of each control algorithm, motion simulations are performed in various wave lengths and wave heights. PID control is very easy to handle, however a poor performance is observed in irregular waves. LQR control gives robust and stable results throughout all the cases. The results of sliding mode control are remarkable when the information of the wave disturbance is exactly known. However, it is found that the motion tends to diverse as the discrepancy between the real disturbance and the estimated value becomes bigger.