Research On Formation Control And Obstacle Avoidance Strategy Of Autonomous Underwater Vehicle

Covering more than two thirds of the earth’s surface,the ocean is an important resource for human survival and development.With the continuous updating and iteration of science and technology underwater robot formation operation has become one of the important means of ocean development and exploration.Formation control and obstacle avoidance play an important role in underwater tasks.Formation control can improve the task scope and efficiency of autonomous underwater vehicles,and formation obstacle avoidance can ensure the safe operation of autonomous underwater vehicles and improve the safety and reliability of the robots.The two interact and jointly provide guarantee for the smooth completion of underwater tasks.Based on this,the formation control and obstacle avoidance strategies of underwater robots are studied in this paper.The main contents are as follows:Aiming at the problem of formation control of autonomous underwater vehicles,the kinematics and dynamics modeling of autonomous underwater vehicles are firstly carried out,and the 6-DOF vector model is obtained,and the mathematical model of underwater vehicle formation is established.In order to ensure the control accuracy of underwater vehicle,a nonlinear disturbance observer is designed to estimate the external interference effectively and output compensation to the controller.A fixed-time trajectory tracking controller based on reverse step method is designed to control the movement of the pilot in the formation of autonomous underwater vehicles in real time,so that the pilot can move according to the preset trajectory.A fixed-time trajectory tracking controller based on backward step method is designed to control the movement of the followers in formation in real time,so that the followers can keep the desired formation during formation movement.The stability analysis of the formation control system of autonomous underwater vehicles shows that the formation control system can reach stability in a fixed time.Finally,by simulation experiments,the following screw curve and Dubins curve are respectively adopted to verify the effectiveness of the fixed time formation controller based on the inverse step method.Aiming at the obstacle avoidance problem of underwater robot formation,safety potential field and internal safety threshold are introduced to ensure the navigation safety of underwater robot formation and its members.Formation shrinkage factor is introduced to facilitate the choice of formation obstacle avoidance mode.In view of the different passable widths of obstacle areas,three obstacle avoidance modes,namely shrink transform,complete transform and unilateral bypass,are designed respectively.Finally,three obstacle avoidance modes are adopted by the underwater robot formation to pass through the obstacle area in the simulation experiment,which verifies the effectiveness of the obstacle avoidance strategy proposed in this paper.