Design Of Robust Sliding-Mode Repetitive Control For Longitudinal Motion Of Fully-Submerged Hydrofoils

At high speeds,the hull of a submerged hydrofoil can be lifted out of the water by the lift generated by the hydrofoil.Therefore,the wave-making resistance and frictional resistance,which have great influence on the running state of other kinds of ships,can be greatly overcome.At the same time,the impact of sea waves on the hull of the submerged hydrofoil can be reduced to a considerable extent,which makes the submerged hydrofoil have a good seaworthiness.However,under the condition of wing navigation,the static stability of a fully submerged hydrofoil needs to be further improved.In this paper,the attitude control of longitudinal motion of a submerged hydrofoil craft in a long peak-wave random wave is studied,that is,pitch and heave.This paper mainly carried out the following research work:Firstly,this paper introduces the purpose and significance of the research on this subject,and summarizes the structure of the paper according to the research direction of the subject.The development of hydrofoil craft at home and abroad,the control methods and the development history of the technology are also introduced.In this paper,the object of study is fully immersed hydrofoil.In order to control the longitudinal motion of fully immersed hydrofoil,we adopted controllable flaps and analyzed each structure of the fully immersed hydrofoil.Then the mathematical model and state space equation of the submerged hydrofoil are summarized according to the overall structure characteristics and the control requirements of the submerged hydrofoil.Then,the mathematical model of long peak wave random wave is established to obtain the longitudinal interference force and interference moment of the wave on the fully submerged hydrofoil.In the case of no controller added,simulink of Matlab was used to simulate the fully submerged hydrofoil with different wave height,wave direction Angle and speed,observe the variation of heave and pitch under different conditions,and make statistical analysis on the obtained data.Then,the sliding mode control algorithm is designed and the appropriate parameters are selected.But in order to make up for the chattering of sliding mode control common features,this article has studied the H_∞state feedback control,after adding controller to control system,a new simulation,under the condition of sliding mode control with total immersion of pitch and heave of hydrofoil,and observed under specific sea condition,the submerged hydrofoil boat longitudinal motion is more stable.Finally,when a fully submerged hydrofoil boat sails in random waves,it is inevitable that there will be some uncertain factors,mainly some uncertain parameters in the modeling process and some higher-order terms will be ignored in the linearization process.After analyzing these uncertain parameters,the state space model of fully immersed hydrofoil with uncertain parameters is obtained.A robust sliding mode repetitive controller is designed to reduce the external disturbance,that is,the effect of waves on the submerged hydrofoil hull,by using the repetitive controller and the state feedback link,and to reduce the influence of the uncertainty of the system on the longitudinal attitude by using the sliding mode controller.