The Design Of Backstepping Sliding Mode Track Autopilot Based On ESO

When the ship sails on the sea surface,the mathematical model of ship motion control has obvious uncertainty due to external environmental disturbance,speed change and draught condition.At the same time,the ship exhibits large inertia and nonlinearity.Therefore,research on robustness The non-linear ship heading and track autopilot control algorithm with good adaptability and easy engineering practice is very important for improving the performance of the autopilot.In order to solve the course and track tracking control problems in ship motion control,this paper considers the interference factors,the nonlinearity of mathematical model,and the characteristics of the steering gear in actual navigation,combines backstepping control with sliding mode control and add an extended state observer to design course and track autopilots with strong robustness and high accuracy.The simulation experiment proves that the designed controller can accurately track a given heading and track,and has strong anti-disturbance capability.The specific work is as follows:1.The design of course autopilot:considering the steering characteristics of the ship,and use the Norrbin nonlinear response model to establish the second-order nonlinear mathematical model of the ship course control system,optimize the backstepping method,add a first-order filter to filter the virtual control variable,and avoid the problem of "number of items expansion".In the last step of the backstepping method,the non-singular terminal sliding mode(NTSM)surface is introduced,and the ship course control law is designed to improve the convergence speed of the system and eliminate the steady state error,based on the idea of Active Disturbance Rejection Control technology,the expansion state observer(ESO)is designed to observe and estimate the external disturbances and model uncertainties of the system in real time,and compensated to the control law.The backstepping and non-singular terminal sliding mode(BNTSM)course autopilot based on extended state observer is designed.2.The design of tracking autopilot:to solve the track tracking control problem of under-actuated surface ships under external disturbances,an indirect control method based on course is introduced to establish the expected ship bow equation for the target path by hyperbolic tangent function.Based on the course controller,the sliding surface is optimized,and the non-singular fast terminal sliding mode(FTSM)surface and the continuous approaching law with terminal attractor are introduced.The backstepping and fast terminal sliding mode(BFTSM)track autopilot based on extended state observer is designed.The controller improve the convergence speed and anti-interference ability of the system and solve the chattering problem existing in the sliding mode control.3.Simulation verification:This paper uses Simulink to carry out the simulation experiments of fixed course keeping,variable course tracking,linear track tracking and curve track tracking under different degrees of interference.The results show that the backstepping and sliding mode course and track autopilot base on ESO can track the course and tracking quickly and accurately under different external disturbances,and the course changes are not over-adjusted,the rudder angle changes smoothly,the steering is reasonable,the system is has high robustness and accuracy.