Research On Trajectory Tracking Control Of Small Underwater Vehicles

Autonomous underwater vehicle(AUV)is widely used in marine rescue,development of marine resources and military fields.However,the 6-DOF space motion of underwater vehicles has the characteristics of strong coupling and nonlinear dynamics,which has causedgreat challenges to the design of the controller.In this paper,the trajectory tracking control problem of small low-speed underwater vehicles is studied,and relevant simulation experiments are carried out with Kambara AUV as the simulation object.First of all,considering the nonlinear hydrodynamics of AUV and the coupling of various degrees of freedom,the 6-DOF kinematics model and dynamic model of AUV are established.Targeted at the problem of 2-DOF AUV attitude control in plane motion,the 6-DOF AUV model decoupling is simplified into horizontal and vertical motion models,and an improved Multiple output PID Neural Network(MPIDNN)controller is designed to realize AUV motion attitude control in horizontal and vertical planes.Secondly,for the 3-DOF AUV horizontal trajectory tracking control problem,since the AUV mathematical model has a clear "kinematic-dynamic" structural feature,the double closed-loop control strategy is adopted,and the integral sliding mode is used to reduce the system steady-state error.The quasi-sliding mode method reduces chattering,and verifies the effectiveness of the strategy through horizontal straight line trajectory and circular trajectory simulation.Finally,for the problem of 6-DOF AUV space trajectory tracking,the adaptive law is used to estimate the ocean current velocity according to Back Stepping's design idea considering the effect of ocean current velocity and external slow disturbance.Meanwhile,the quasi-sliding mode control method is used to overcome the slow disturbance from outside,the AUV space trajectory tracking controller is synthetically designed,and the simulation experiment of AUV space curve trajectory tracking and control is carried out.