Research On Control Method Of Autonomous Underwater Vehicle Based On Robust Control

The autonomous underwater vehicle is a complex system with nonlinear,coupled and uncertain hydrodynamic forces,and it is difficult to obtain an accurate mathematical model.A good control system is the premise of the work of the aircraft,and the robust control can improve the robustness of the aircraft in a complex environment and can basically meet the performance requirements of motion control.The paper takes a torpedo-type autonomous underwater vehicle as the research object,in order to improve the stability,accuracy and robustness of its motion control,robust control,nonlinear robust sliding mode control and Backstepping method,and their The application of the autonomous underwater vehicle controller design is studied.The six-degree-of-freedom kinematics and dynamics equations for underwater autonomous vehicles were established based on aircraft space motion and fluid mechanics.The model was linearized under specific operating point cruising conditions.The control design models of the aircraft's horizontal and vertical plane motions were obtained respectively.Aiming at the uncertainty of the model of the autonomous underwater vehicle and satisfying the control precision when working underwater,the method of selecting the weighting function in the hybrid sensitivity robust control and the design method based on the linear matrix inequality(LMI)H_?controller are studied.A robust controller for the heading,forward velocity,and depth of autonomous underwater vehicle based on mixed sensitivity and linear matrix inequality was designed,and the effectiveness of the design to suppress interference and the accuracy of control were verified through simulation analysis.In view of the conservativeness of the robustness of the hybrid sensitivityH_?robust control,the design method of the nonlinear robust sliding mode control is studied.In order to overcome the chattering phenomenon of the sliding mode control and ensure that the system state reaches the sliding mode surface within a finite time,the boundary layer technology is studied,ie nonlinear feedback is used in the boundary layer.This method has strong robustness.The navigation,trim,and depth controllers for autonomous underwater vehicles were designed using this method.The validity of the design results was verified by simulation.For the path tracking control of aircraft,the output feedback control method based on terminal sliding mode control combined with Backstepping algorithm is studied.The control method uses Backstepping to obtain the explicit solution of the control algorithm and constructs the structure of the controller.Then an inverse dynamic terminal sliding surface is designed based on the observer,which can make the system state tracking error in a limited time.It reaches the sliding surface and finally reaches the system stability.The simulation verified the good tracking performance of this method.