Research On Anti-interference Control Method Of Autonomous Underwater Robo

Autonomous underwater vehicle has been widely used in many fields with its distinctive characteristics,such as chart drawing,military defense,ocean research,seabed resource detection and so on.Since autonomous underwater robot is susceptible to various unknown disturbances,such as wind,waves and ocean currents,it is particularly important to design a motion controller with anti-disturbance ability in the process of completing various underwater tasks.Therefore,in this paper,aiming at the motion and attitude control system of autonomous underwater vehicle,the disturbance observer with sliding mode control method and Backstepping control method are combined to design a composite antidisturbance controller to suppress the adverse effects of external interference on the motion and attitude control performance of autonomous underwater vehicle,and improve the stability and anti-disturbance ability of autonomous underwater vehicle.The main contents of this paper include the following aspects:(1)A sliding mode controller based on nonlinear disturbance observer is designed to improve the course tracking control performance of the underwater underwater vehicle horizontal system under the influence of external disturbances.Firstly,the horizontal plane model of underactuated autonomous underwater vehicle is simplified conditionally,and the state equation of the simplified model is established.Secondly,the nonlinear disturbance observer is constructed,and the sliding mode controller based on the disturbance observer is designed.According to Lyapunov stability theory,the appropriate observer gain and controller gain are selected to ensure the stability of the closed-loop system.The simulation results show that the sliding mode controller based on nonlinear disturbance observer can realize the heading tracking control of autonomous underwater vehicle better than the traditional sliding mode controller in the case of external interference,and has good antiinterference performance.(2)In order to improve the attitude control performance of the vertical plane system of underactuated autonomous underwater vehicle under the influence of external disturbances,an equivalent sliding mode controller based on disturbance observer is designed.Firstly,the vertical plane model of underactuated autonomous underwater vehicle is simplified according to the actual situation,and its state equation is established through the simplified model.Then the disturbance observer is constructed,and the equivalent sliding mode controller is designed based on the disturbance observer.The stability of the closed-loop system is proved according to Lyapunov stability theory.The simulation results show that compared with the traditional sliding mode controller,the proposed controller can realize the vertical depth control of autonomous underwater vehicle better and has good anti-interference performance when there is external interference.Through the comparison between the estimation effect of external disturbance by the disturbance observer designed in this part and the estimation effect of external disturbance by the disturbance observer designed in past reference,the simulation results show that the disturbance observer designed in this part can estimate the external disturbance effectively faster.(3)In order to realize 3d linear path tracking control of underactuated autonomous underwater vehicle in the presence of external disturbance,the path tracking control problem is transformed into a stabilization problem of nonlinear system based on kinematics and dynamics equations.Then the sliding mode controller is designed based on disturbance observer and backstepping method and Lyapunov theory to ensure the stability and robustness of the system.The simulation results show that the disturbance observer designed in this part can estimate the external disturbance and compensate the control,and the controller can accurately track the 3d linear path and has good anti-disturbance performance.