Research On Path Following Control Of Unmanned Catamaran

As an intelligent platform with autonomous navigation and decision-making ability,unmanned ship plays an important role in dealing with climate and marine environment changes and national security.Among them,the small waterline double body unmanned ship has been widely used in the military and civil fields because of its excellent wave resistance.With the development of artificial intelligence,network technology,new materials and other high-tech in recent years,this also puts forward higher requirements for unmanned ship control.In this paper,taking the catamaran as the research object,considering the complex marine working environment,the uncertainty of the hull model itself,and the physical constraints of the propeller,the following researches are carried out:(1)Based on the MMG model and considering the special structure of the catamaran,the motion model of the catamaran is established.Aiming at the problem of path tracking control,a finite time line of sight(FLOS)guidance law is designed based on LOS guidance law.The guidance law can make the heading angle error converge to zero and ensure the path tracking error converge to zero in finite time.Then,on the premise of ignoring the external disturbance,considering the parameter uncertainty of catamaran model due to hull wear,external environment and other factors,the adaptive backstepping method is introduced to design the path following control law,which effectively solves the problem of model parameter uncertainty.Differential tracker is used to deal with the singularity problem that may appear in the derivation.Finally,the simultaneous interpreting guidance law in this chapter is compared with the traditional LOS guidance law in the MATLAB simulation platform,which proves the superiority of the above design scheme.(2)Considering the influence of current on ships,an improved FLOS guidance law(IFLOS)is proposed under the assumption that the current information is known.The guidance law can overcome the negative effects caused by current disturbance and ensure the position error converges to zero in finite time.Then,considering the maximum output power of propeller and actuator in practice,an adaptive finite time state observer backstepping method with auxiliary dynamic system is designed.The auxiliary dynamic system is used to solve the problem of control input saturation.At the same time,the adaptive finite time state observer can quickly estimate the unknown external disturbance and compensate the control law in real time.Finally,MATLAB simulation results verify the path tracking performance and robustness of the proposed method.(3)Because the guidance law of IFLOS needs to obtain the information of current,however,the information of current interference is usually unknown.Considering the unknown current information,a finite time current observer is designed to estimate the current information and provide information compensation for the IFLOS guidance law.Then,based on the input saturation problem,aiming at the problem that it is difficult to accurately determine the actual model of the catamaran unmanned ship,a neural network backstepping method is designed.The method uses neural network technology based on minimum learning parameters to approximate unknown items online.Finally,the effectiveness and robustness of the proposed path tracking control scheme are verified by MATLAB simulation.