Model-aided And Sea Current Estimation For UUV Autonomous Navigation Research

Unmanned Underwater Vehicle(UUV)is a kind of marine equipment with strong autonomous,good controllability and long endurance.It plays an important role in marine development and exploration.High precision navigation and positioning system is an important guarantee for UUV to work and return safely.The dead reckoning algorithm is widely used in autonomous navigation,and it calculates position mainly by speed and attitude information collected by Doppler Velocity Log(DVL)and attitude sensor.The failure of DVL or mistakes of measured data will cause a great navigation positioning error when UUV operates underwater.In this paper,autonomous positioning navigation based on model-aided and sea current estimation is studied,which is to improve the robustness and stability of UUV navigation and positioning system.The main contents of the paper includes the following aspects:Firstly,establish the geodetic coordinate system and the moving coordinate system,construct transformation matrix between coordinate systems.On this basis,UUV's kinematics model and dynamics model of 6-dof are built.Considering the effect of sea current,the model of sea current interference is studied.The correctness of the UUV mathematical model is verified by simulation.Secondly,study on the sea current estimation technique in UUV navigation area.In the initial state of UUV,according to whether the distance between UUV and the seabed is greater than that of DVL,the flow estimation technique is divided into two aspects: shallow sea and deep sea.Under shallow sea environment,based on UUV dynamic model and least square method,the sea current estimation algorithm is studied.And under deep sea environment,based on Ultra Short Baseline(USBL)and Extended Calman algorithm(EKF)to study the sea current estimation algorithm.The rationality and feasibility of the algorithm are verified by simulation.Then,study on the autonomous navigation and positioning method based on dead reckoning.Analyze the error reason of dead reckoning algorithm and use actual navigation data of UUV to identify the installation error Angle and speed correction coefficient of DVL,and revise the error.The data processing method of UUV autonomous navigation and positioning is also studied.Lastly,combine the mathematical model,sea current estimation technique and dead reckoning algorithm to study on autonomous navigation and positioning method,which based on model-aided and sea current estimation.Contrast the UUV navigation trajectory in different circumstances to analysis the influence of sea water interference on UUV navigation and positioning.On this basis,conduct simulation to prove the validity and correctness of UUV autonomous navigation and positioning method.