Research On The Path Following Control Of USV With Dual Propulsions

"Adhere to the principle of balance the land with the sea,speed up the construction of Marine power",which is our country's major strategic deployment in the field of ocean,requires us to vigorously promote the ability of Marine development and protection,in addition,actively develop the related marine equipment industry.USV works as an indispensable equipment for Marine development and protection,widely used in various fields,but the complex ocean environment poses challenges for unmanned craft to perform certain tasks,thus need to research on the basic motion control and crack this problem gradually.Aiming at the path folllowing control which is based on a certain type of USV of Harbin Engineering University,this thesis conducts related control algorithm research,and executes a series of works on designing as well as validating the path following controller direct at straight path and curve path.The research contents of this paper mainly includes the following aspects:First of all,according to the characteristics of the USV with dual propulsions,a planar 3-dof kinematics and dynamics model is established,in view of the control input of the model,a water-jet thrust model is built,then introduce a zero-mean-value random noises with Guassian distribution to describe the external disturbance.For solving the unknown hydrodynamic parameters in the model that has been built,with the help of the PMM platform of Star-CCM+ software,one numerical simulation of forced movement on the USV model is carried out.In order to test the availability of the simulation results,a constant rotation simulation as well as experiment is executed,verifing that the accuracy of hydrodynamic parameters ever obtained.For realizing the straight path following function,the work of designing expected heading angle based on the LOS guidance algorithm was executed,and the sliding mode function is constructed through heading angle error.On the basis of Hurwitz conditions,design exponential approach law to improve the approach performance between the moving point and the sliding mode plane,then sliding mode control law is obtained,what's more,through a low-pass filter and saturated function to optimizate the control performance,finally through a straight path following simulation,verifies the outstanding performance of the sliding mode robust controller.Finally,the system model is further optimized for the uncertainty of the USV's hydrodynamic parameters and the response disturbance of the two actuators.The parametric design of the LOS guidance algorithm is constructed based on the curve path,in addition,a sliding mode controller based on the upper boundary is established,by means of the Lyapunov stability theory,accomplish parametric design.A saturated function together with one and second-order filter are introduced to optimize the feedback information and the controller output of the closed-loop system.Finally through the model simulation,confirm that the path following precision together with actuator response form both meet the demand of the actual control.