Research On The Dynamic Docking Method Of UUV Underwater Recovery

With the rapid development of society and economy,all countries are formulating marine development plans in accordance with their own development.In marine exploration activities,unmanned equipment represented by underwater unmanned aerial vehicles(UUV)has been widely used.However,due to the current development of battery technology,UUV cannot carry long-term underwater work with its own energy.Therefore,the UUV needs to be replenished by an underwater mother ship as a supply station.In this paper,the underwater docking problem of the mother ship hovering,low speed and high speed under different sea conditions is studied in depth.This paper analyzes the interference problems of the mother ship under different motion conditions,and considers the docking process control problems caused by factors such as ocean current interference,mother ship interference and UUV parameter uncertainty during the docking process.In order to specifically analyze the docking problem of the mother ship under different motion states,a six-degree-of-freedom modeling of UUV and mother ship space was performed,and the UUV and mother ship models were simplified.Based on the simplified model,a master-slave state synchronization framework for UUV and mother ship is proposed.Aiming at the constraint problem of the underwater docking process under the hover state of the mother ship,unknown constant current interference was added.Combine the UUV with the master-slave state synchronization framework of the mother ship,and establish the docking system error equation after adding interference.Utilizing the finite-time convergence characteristics of the terminal sliding mode,a non-singular terminal sliding mode controller is designed so that the docking system error can converge to zero in a limited time.Through the Matlab simulation program,verify the docking process in the hover state of the mother ship.According to the actual project,simulation should be performed,and the simulation results are compared with the situation without current interference and with current interference,and it is finally proved that the controller has better control effect with or without current interference.And conduct pool experiments to verify that the controller effect meets the design requirements.Aiming at the constraint problem of the underwater docking process of the mother ship under the condition of low speed navigation,an unknown bounded mother ship spoiler interference is added under the premise of constant current interference.Combine the UUV with the master-slave state synchronization framework of the mother ship,and update the docking system error equation.A non-linear interference observer is proposed to estimate the interference force caused by the mother ship disturbance to UUV,and an improved terminal sliding mode controller based on the interference observer is given.Through Matlab simulation verification,compared with the control effect of the unimproved controller and the improved controller,the nonlinear interference observer can effectively estimate the unknown interference,and ensure the stability of the controller during the docking control of the mother ship at low speed.Aiming at the constraint problem of the underwater docking process of the mother ship at high speed,the influence of the uncertainties of the UUV system model on the UUV control during the docking process was added.An RBF network with fixed system learning parameters is proposed to compensate the interference caused by the UUV model uncertainty.By using the approximation characteristics of RBF neural network to any unknown nonlinear function,the UUV uncertainty is approximated,and an improved adaptive terminal sliding mode controller is added,which incorporates RBF network and interference observer.After Matlab simulation verification,compared with the controller control effect before and after the RBF network is added,the UUV motion trajectory fluctuation after adding the RBF network is significantly smaller without overshoot,which eliminates the UUV motion process fluctuation caused by the UUV model uncertainty.