Research On Maneuverability Forecast Method Of Autonomous Underwater Vehicles

With the ocean resources being utilized more and more progressively,researchers from all over the world attach more importance to Autonomous Underwater Vehicles for its good properties in both civil services and military services.Good maneuverability is the basis of AUV's safe navigation,good performance,as well as the focus of overall design.The diversified development of AUV puts forward higher requirements on all aspects of its performance,so it is important to investigate its maneuverability deeply.In order to study its maneuvering properties,it is necessary to simulate AUV's motions to achieve maneuverability forecast.The accurate prediction of maneuvering capabilities not only provide a scientific reference for AUV's structural design,propulsion system design and control system design,but also effectively improve its endurance.The estimation of maneuvering properties requires the construction of maneuverability equations.Hydrodynamic coefficients are the coefficients of these equations,therefore,based on the maneuvering equation to predict maneuvering capabilities,the hydrodynamic coefficients must be determined firstly.In this paper,the computational fluid dynamics software Star CCM+ is used to study the hydrodynamic calculation.An underwater robot is chosen as the research project in this thesis,firstly the feasibility of the CFD method is verified by comparing the CFD results with experiment results of standard ellipsoid.After the verification is completed,use CFD software to simulate two kinds of steady motions of an AUV,which are direct-route and off-course.The corresponding hydrodynamic force and moment are obtained according to the simulation.Import the data of CFD simulation into Matlab to obtain corresponding velocity coefficients,angular velocity coefficients.acceleration coefficients,and angular acceleration coefficients.In order to obtain the acceleration hydrodynamic coefficients,the unsteady motions are supposed to be numerically simulated.In this paper,pure sway and pure yaw,two kinds of unsteady motions in horizontal plane,are simulated by the PMM module of Star CCM+.Based on the analysis of the motion properties,two kinds of unsteady motions in vertical plane,pure heave and pure pitch,are simulated by translation module and the translation module superimposed rotation motion.After the numerical simulation,the hydrodynamic force and moment are calculated.The calculated results are processed by Fourier integral and data fitting to obtain the acceleration coefficients and angular acceleration coefficients.Finally,on the basis of the obtained hydrodynamic coefficients,themaneuverability equation is constructed.According to the equation,implement an AUV maneuvering simulator with Matlab-Simulink to simulate turning circle maneuver and zig-zig maneuver and forecast AUV's maneuverability.