Research On Horizontal Trajectory Tracking Control Algorithm Of Underactuated AUV

With the continuous progress and development of human society,it is particularly important for the exploitation and utilization of the ocean.As the place with the most resources in the world,the ocean attracts people's exploration all the time.In recent decades,autonomous underwater vehicles(AUVs)have become the focus of many Marine research efforts due to their extensive applications in many fields,including Marine exploration,Marine mapping,underwater pipeline inspection,scientific and military tasks.Due to the model characteristics of AUV(non-linear,coupling and uncertainty),the existence of many external disturbances underwater in practical applications,and most AUV in order to reduce the weight of the form of underdrive,all of these make the control system design of AUV become one of the biggest difficulties in its development.Therefore,it is necessary to study the robust control of underdriven AUV.First of all,this paper establishes the six-degree-of-freedom kinematics and dynamics model of underactuated AUV,and,based on the literature and considering the parameter uncertainty,establishes the horizontal nominal motion model and parameter uncertainty model of underactuated AUV.Secondly,a terminal sliding mode controller is designed for the horizontal trajectory tracking problem of underdriven AUV with parameter uncertainty,and the closed-loop stability of the control system is proved by Lyapunov stability theory.The two models are simulated numerically.The simulation results show that the proposed controller can track the expected trajectory well even if there is parameter uncertainty,which proves that the proposed control strategy has good robustness to parameter uncertainty.Then,in view of the possible external interference(ocean currents,waves,etc.),a sliding mode interference observer was proposed to compensate the external interference,and two schemes.this paper proposed a homogeneous high-order sliding mode interference observer and a sliding mode observer based on the adaptive super-twisting algorithm,and a comparison was made to them through numerical simulation.A fast terminal sliding mode controller is designed for the finite time convergence of system state error away from the equilibrium point.The controller is combined with the observer and the corresponding numerical simulation is made under the condition of external interference.Simulation results show that AUV can track a given trajectory well even with external interference.And the control scheme can make the state error converge to zero quickly.It is proved that the scheme has good control performance and strong robustness against external interference.