The Research On Ship Tracking Control Based On Improved ARX Model

In the ship’s intelligent control,the track tracking control is the most basic content.Only by navigating on a precise route can tasks such as autonomous control be achieved.This content includes the research of ship motion control.Such as course keeping,model building and ship attitude,etc.This thesis takes the electric propulsion of a small surface vessel with twin hull and twin propeller as the object to study the design and related contents of the track tracking controller.In order to realize the track tracking control design of small unmanned vessel,the first step is to establish the shore base station.It can always observe the motion state of the unmanned vessel and adjust the control algorithm at any time.The host computer platform is designed in the environment of VS2010(Microsoft Visual Studio).The target around track tracking can mainly complete real-time data reception,control command issuance,manual automatic switching,course keeping and track tracking control algorithm programming,etc.At the same time,the accurate acquisition method of the heading angle in the course keeping system is analyzed.On the basis of the establishment of the experimental platform,the next work is to establish a suitable unmanned vessel model.According to the characteristics of the current experimental environment,the ARX model with affine structure is selected as the unmanned vessel model in this thesis.This improved methods proposes an indirect modeling method for the ship’s course-keeping control process.The long-term prediction comparisons with the direct ARX model are conducted under a group of testing data.The simulation results show that the indirect modelling mothed could give a preferable modeling performance for the ship’s course-keeping control process.Then it is applied to the unmanned vessel of this subject,and the optimal model is selected from the three groups of models for controller design and simulation.In the study of track tracking controllers,track planning must first be carried out.Combined with GPS signal,the real-time position of unmanned vessel can be monitored by coordinate system transformation.Based on this,the position error and yaw angle error in straight line or curve tracking state are obtained.Then,the PID control strategy and the LQR control strategy are designed.At the same time,the iterative solution of discrete-time algebraic Riccati equation is solved,and the feasibility of the two control methods is tested under the linear route.After that,the control strategy was optimized and the impact on the system was observed to provide a valuable reference for the actual ship experiment.Finally,LQR and PID control strategies are applied in the real ship to achieve the straight line track tracking task.Comparing the control accuracy of the two systems in the same environment,it shows that the control strategy has practical significance.The content of the thesis has done basic research for the following work.