Research On Path Tracking Control Of USV And Control System Design

Unmanned Surface Vehicle(USV),as a kind of intelligent platform for unmanned tasks to be carried out autonomously,plays a variety of roles in the sea area.It has broad application prospects in the military and civil fields,and has become a research hotspot in various countries.For USV to perform specific tasks,it is necessary to sail along the expected path.So it is of great practical significance to study the path tracking control of USV.USV is a typical underactuated nonlinear control system.Because there is no lateral thrust input,the control of USV is more complex and challenging than that of fully actuated USV.This thesis takes the torpedo shaped USV independently developed by our research group as the research object,combines the theories of active disturbance rejection control and sliding mode control,and studies the interference and tracking accuracy of the USV in the course of path tracking control.The main research work is as follows:A path tracking control strategy based on active disturbance rejection control algorithm was proposed to solve the problem of USV with uncertain model and internal and external interference.To solve the problem of sensor noise interference,the nonlinear function in the extended state observer is modified to function,which restrains the influence of noise and improves the observation accuracy.Aiming at the problem that the controller has many parameters and is difficult to set,the grey wolf optimization algorithm is introduced and its objective function is improved,which improves the control efficiency and is more in line with practical application.The simulation results show that the proposed control strategy can effectively suppress noise interference and improve tracking accuracy.Considering the problems of model parameter perturbation,external disturbance and saturation limit of controller input,a motion control strategy based on sliding mode control was proposed in this thesis.In order to solve the chattering problem near the switching surface of sliding mode control,the approach law based on saturation function is improved,the parameter is introduced.The introduction of parameter can ensure that the control accuracy of the system is improved when the saturation width Δ is unchanged,the influence of chattering is weakened.Aiming at the problem of controller input saturation limitation,the auxiliary system is designed to improve the control performance of the system.Based on the above improvements,the kinematic controller and the dynamic controller are designed.The simulation results show that the proposed control strategy is effective.The path tracking control system of USV is designed and developed,and the function test experiment of each module is carried out.The pool experiment is carried out to verify the basic performance of the USV control system.The path tracking experiment of USV was carried out in an outdoor lake to track the target point and path autonomously.The control algorithms designed in this thesis are implemented by Matlab and Qt programming,simulation and lake experiments are carried out.The experimental results verify the effectiveness of the designed path tracking control strategy,and the developed USV path tracking control system is reliable and stable.