Research On Joint Steering Control Technology Of Submarine In Vertical Plane With Sliding Mode Controller Based On Nonlinear Observer

Since the natural resources are becoming less and less,we human beings are gradually focusing our attention on the ocean,as an important military weapon for marine defense,research of submarine technology has been widely carried out worldwide.Owing to the secrecy and motility of its mission type,the mechanical structure of a submarine is usually very complex,which makes its system highly nonlinear and time-varying,therefore,having good maneuverability is particularly important during submarine motion control.Steering control is an important component of submarine's control system,it is very meaningful to design a good steering control system to deal with complex ocean conditions and combat missions.Usually,the movement of a submarine can be decoupled to heading control in the horizontal plane and depth and pitch control in the vertical plane,this paper focuses on the problem of depth control in the vertical surfaces.Different steering control strategies have been designed to solve the problem of depth control aiming at the submarine which is equipped with bow horizontal rudder and stern horizontal rudder.To solve the problem of pitch angle control,an adaptive guidance law based on the line-of-sight angle is designed to obtain the desired pitch angle.Concerning about the uncertain dynamic errors that may occur in the depth control,the nonlinear disturbance observer(NDO)and extended state observer(ESO)are designed,as well as the sliding mode controller,which has good robustness that can deal with the disturbance.In the end,digital simulation experiments have been conducted to judge which steering control strategy is superior,at the same time,the feasibility and effectiveness of the controller designed based on the observers have been verified.First of all,by searching a mass of papers and references,the research status and development trend of motion control of submarine in the vertical surface have been summarized,nonlinear observer and sliding mode control technologies which are applied to the motion control of submarine have been introduced;based on the naval highlights researched project—UUV,whose stricter is similar to a submarine,the system structure and control system composition of this UUV have been described.Expanding to a general submarine system,the reference coordinate system is established,as well as the kinematic equations and kinetic equations,do the further research,simplified model of a submarine in the vertical surface has been obtained.Secondly,strategies of depth control with single rudder,depth control with separation double rudder,depth control with united double rudder have been developed by analyzing the control characteristic of the bow horizontal rudder and stern horizontal rudder.In order to solve the coupling problem of pitch angle and depth,an adaptive guidance law based on the line of sight angle is designed to provide motion guidance that is compliant with maneuverability of the submarine.A sliding mode controller with good robustness has been designed,concerning about the chattering phenomenon caused by the SMC,an improved SMC method with power reaching law and boundary layer has been developed.Then,in order to restrain the influence of the disturbance such as the modeling error,the measuring error and the environmental change and so on,the nonlinear disturbance observer(NDO)that can observe the value of disturbance directly and the extended state observer(ESO)that can estimate the impact of disturbance have been designed,what is more,based on the designed observers,corresponding sliding mode controller are developed,the stability of the observers and the controllers have been certified as well.Finally,simulation experiments have been conducted,experiments results show the observe effect of the observers,meanwhile,control effects of the normal sliding mode controller and the sliding mode controller designed based on the observers have been compared,comparison result verified the feasibility and effectiveness of the observer and the controller.