Research On Dynamic Positioning Method Of AUV Recovery

Autonomous Underwater Vehicles(AUV)must be recycled to supplement energy after a certain period of underwater activity due to their specific energy constraints.Underwater docking can meet the continuity and concealment need of AUV underwater missions is the current research trend.Because of the large influence of AUV on underwater flow during underwater docking,this paper has participated in the development of an AUV autonomous docking experimental system.This paper also have designed corresponding full-drive AUV underwater docking strategy and dynamic positioning system.The main research work is as follows:Firstly,the design of the overall retrofit scheme of the full-drive AUV docking system is introduced.The conventional underwater docking strategy is improved according to the modification scheme and AUV driving characteristics,and the accuracy of docking is improved by dynamic positioning method.The mathematical model of the full-drive AUV docking system is built.Then,this paper focuses on the control method of full-drive AUV dynamic positioning,and proposes a sliding mode control method for AUV dynamic positioning based on extended observer.The extended observer is introduced to compensate the model deviation and environmental disturbance of sliding mode control.The sliding mode surface parameter rule table is developed by linear optimal quadratic form,so the controller can satisfy various speed changes and improve the maneuverability of AUV underwater docking.In addition,a torque priority thrust allocation algorithm is designed to avoid the thrust occupancy of AUV thrusters,thus ensuring the flexibility of the robot.Secondly,a state estimation method using adaptive hypersphere square root unscented kalman filter is designed.The Sage-Husa adaptive method is used to evaluate the statistical characteristic parameters of noise and model deviation.The hypersphere sampling is used to improve the speed of the algorithm.The square root filtering method improves the stability of the filter.Finally,this paper deals with a lake test of AUV combined with team.The lake test includes underwater fixed-point dynamic positioning experiment and underwater hexagon trajectory tracking experiment.The feasibility and stability of the design of AUV control system are checked by the experiment.In addition,the simulation comparison experiments are carried out for the designed docking strategy and docking system.The simulation results show that reasonable use of dynamic positioning control strategy can effectively improve the accuracy of docking and ensure the stability of docking.