Study On Trajectory Control Of Unmanned System Support Ship

More and more products which are combined with unmanned systems,such as unmanned ships and unmanned cars gradually enter people's field of vision,integrate into people's life and become a fashion of modern life along with the rapid development of modern intelligent technology.This paper studies a kind of unmanned system support ship,which adopts a brand new boat type and is a water operation platform for carrying underwater submersibles and unmanned ships.It combines the functions of general ship protection with unmanned systems,and has the technical characteristics of autonomous navigation,strong endurance and the like.As the ship is still in the research and development stage,all aspects of work need to be verified in theory.Therefore,this paper focuses on the motion control part of the ship,which mainly includes the following aspects:Firstly,based on the six-degree-of-freedom nonlinear mathematical model of the surface ship,a three-degree-of-freedom motion mathematical model suitable for controller design of the ship is obtained,and a thrust distribution model is constructed according to the control input items in the model.Secondly,to solve the problem of unknown hydrodynamic parameters in the motion model,the CFD software STAR-CCM+ is used to simulate the constrained model of unmanned system support ship.The hydrodynamic parameters are obtained through the post-processing of the calculation results.The availability of the parameters is verified by the simulation experiments of the steady direct flight and steady rotation.Thirdly,in order to realize the motion control of the unmanned system to ensure the ship,a speed controller and a course controller based on sliding mode method are designed first.In the design process,random noise with zero mean Gaussian distribution is introduced to simulate the external disturbance,and the robustness of the controller is verified through simulation experiments.Then,aiming at the problem of unmanned system guaranteeing the ship's linear path tracking,the controller is designed by combining LOS guidance algorithm with sliding mode control method based on exponential reaching law,and the low-pass filter and saturation control link are introduced to realize the performance optimization of the controller.Through the tracking simulation of the expected linear path,the excellent performance of the designed sliding mode robust controller is verified.Fourthly,for the stabilization of the target point in motion control,a nonlinear motion stabilization controller is designed based on backstepping method,and dynamic surface technique and high gain observer are used to optimize the performance one after another.The system simulation verifies the good stabilization control effect of the controller.After the introduction of the high-gain observer,it can realize a more accurate estimation of the ship's movement speed and solve the problem that the actual ship's movement speed is not easy to measure directly in engineering.