Safety-guaranteed Trajectory Tracking Control For High-speed Unmanned Surface Vessels With State Constraints

In recent years,as countries around the world have paid more and more attention to the importance of maritime status,many countries have begun to vigorously develop maritime military forces and strengthen the integrated combat system of land,sea and air.Therefore,marine vehicle related technologies have been rapidly developed.As a new type of intelligent equipment,the Unmanned Surface Vehicle(USV)play an irreplaceable role in maintaining the safety of the marine territory and in other civilian applications.Therefore,more and more countries attach importance to the USV Technical research.However,due to the small size,light weight,rapidity,uncertainty and the complexity of the marine environment,ensuring the safe navigation of the USV in the marine environment is an important prerequisite for other tasks.Therefore,it is great significance to study the safety control methods of high-speed USV.In order to realize the safety control of high-speed USV navigation,the strict control of the tracking error and the yaw velocity of the USV ensure it within the safe range.And simulation verification of these two state constraints.The mathematical model of the three-degree-of-freedom motion of the USV is established.Firstly,the two coordinate systems needed in this paper are established in order to study the relationship between the position and attitude angle of the USV.Secondly,the three-degree-offreedom model needed for this paper is established by simplifying the original model according to the specific research content of this paper.Since the object of this study is high-speed USV,the influence of high-order items in the model parameters is considered in the model.Finally,the validity of the model is verified.Secondly,aiming at the position error and speed error of high-speed of the USV during driving,a preset performance backstepping sliding mode controller is proposed.By equivalent error conversion,the error is constrained within the preset range.An USV trajectory tracking controller based on preset performance is designed.First,in the kinematics loop,the position error model of the USV is transformed into an equivalent error model,and the desired surge and sway velocities are designed to converge the position error.Secondly,in the dynamic loop,the speed error model of USV is converted into Equivalent error model,and using the backstepping sliding mode method to design the controller in the dynamic loop,while ensuring that the position error tracking error converges to zero,the speed error of the USV also gradually converges to zero.Then,while tracking the desired trajectory,and the position error and velocity error of the USV converge to a preset range through simulation.The steady state and transient performance meet the preset requirements.Finally,aiming at the problem of the yaw speed of the high-speed USV during the sailing process,the tracking controller of the USV with the yaw speed constraint is designed.Firstly,considering the influence of external environmental disturbance on the navigation of high-speed USV,the disturbance observer is introduced to estimate the unknown disturbance to offset the external environmental interference,and the external disturbance is prevented from causing excessive yaw speed of the USV.The trajectory tracking controller of the USV with external disturbance is designed.Then,the command filter is introduced to constrain the virtual control rate within the preset range and obtain the first-order approximate derivative,which is prepared for the design of the obstacle Lyapunov function.Then limiting the error of the yaw speed by introducing the obstacle Lyapunov function,which indirectly limits the yaw speed of the USV within a certain safe range,so ensures the safe navigation of the USV.