Research On Path Planning And Tracking Control Of Underactuated Autonomous Underwater Vehicle

The ocean occupies most of the space on the earth’s surface and is rich in energy,biological and mineral resources,and countries are racing to accelerate the pace of exploring the ocean.Underactuated autonomous underwater vehicles are becoming increasingly popular in ocean exploration due to their advantages in cost savings,reduced system design,reduced energy consumption,and improved system reliability.Path planning and path tracking technology is the premise to ensure the safe and accurate completion of scheduled tasks of autonomous underwater vehicles,so this paper studies its path planning and path tracking technology.Aiming at the three-dimensional global path planning of autonomous underwater vehicles,this paper proposes a global path planning method based on improved particle swarm optimization algorithm,which improves the speed and position update rules of standard particle swarm optimization 2011(SPSO 2011)algorithm,introduces adaptive parameters to balance local and global search capabilities,and improves convergence accuracy.The mutation operator in the genetic algorithm is introduced to accelerate the convergence speed of the algorithm and avoid the algorithm falling into local optimum.The algorithm comprehensively considers the factors of "path length","path smoothness" and "path security" to establish the fitness function of the path planning algorithm.In addition,for the three-dimensional local path planning,the local path planning method based on the minimum encounter distance is adopted,the collision risk assessment is carried out by using the relative speed of autonomous underwater vehicle and the target obstacle,and the obstacle avoidance waypoint is generated by the geometric method,so as to achieve fast and real-time local path planning.In terms of motion control,the kinematics and dynamics of the 6-degree-offreedom(DOF)autonomous underwater vehicle are modeled and the relevant parameters are analyzed,and then the motion model of underactuated autonomous underwater vehicle with 5 DOF is established.Then,on the basis of the line-of-sight(LOS)guidance algorithm,the three-dimensional guidance problem of autonomous underwater vehicles is decomposed into horizontal guidance and vertical plane guidance,a three-dimensional LOS guidance algorithm for autonomous underwater vehicles is proposed and a controller is designed for simulation verification,and the simulation results show that the algorithm has good guidance performance.Finally,for the threedimensional trajectory tracking control of underactuated autonomous vehicles,the influence of external environmental interference(wind,wave,ocean current)on the trajectory tracking accuracy is considered,and an interference observer is used to estimate it,and then the estimated value is introduced into the controller for equal compensation.The first-order filter is used to filter the control law to eliminate the complexity of the traditional backstepping method,and the controller is designed and the stability is proved.