Research On Motion Stability Of Lift Autonomous Underwater Vehicle

As land resources become increasingly scarce,exploiting murine resources is attracting intensive attention.A growing number of countries have invested in the exploration and development of marine resources,and the competition among the countries on protecting the territorial sea is increasingly fierce.Autonomous Underwater Vehicle(AUV)plays a crucial role in this field with its high autonomous level and wide operating range,and has been widely used in marine resource exploration and marine environment monitoring.However,limited by volume and energy,the traditional AUV generally has the shortages of low speed,limited load types and low load capacity.What's more,it is difficult to carry out strategic resource transport missions.Therefore,the design and development of an AUV with large load and high-speed capability has become a research hotspot in the field.In recent years,the research direction on AUV has gradually shifted from the design and manufacture to its application,and AUV has developed into a multi-functional trend.New concept ocean robots have emerged for applications in different scenarios,in which the lift principle based AUV has demonstrated powerful deep sea operation capability and environmental adaptability.For the research of this new concept marine robot,there is no previous experience for reference in the design of the optimization stage,so the hydrodynamic calculation and motion stability research are of vital importance.This research focused on an autonomous underwater vehicle based on the principle of lift(lift AUV).In order to solve the hydrodynamic problems caused by the heavy load and high speed during the voyage,the Computational Fluid Dynamics(CFD)method was used to carry out the prediction of lift and drag,the dynamic modeling and the hydrodynamic coefficient calculation.The stability and maneuverability of the vehicle were analyzed according to the prediction results.Finally,the vertical navigation performance was analyzed.The main work of this paper is as follows:Firstly,the basic principles and methods of computational fluid dynamics were described,and the setting method of the example was described.Through the direct flight simulation of lift AUV,the force of lift and drag of its direct flight motion at different speeds were solved,and its lift-drag characteristics were analyzed.Secondly,the dynamic model of lift AUV was built according to the force of the AUV when it was moving,and the model was simplified and decoupled.The hydrodynamic coefficients in the decoupled model were solved by CFD wind tunnel test and plane motion mechanism test.The dynamic model and hydrodynamic coefficients could be used for maneuverability simulation test and cruise performance analysis.Thirdly,according to the submarine maneuvering theory,the vertical plane motion stability,horizontal plane motion stability,vertical plane motion mobility and horizontal plane motion mobility of lift AUV were analyzed by theoretical calculation and simulation test,and the motion stability and mobility of lift AUV were comprehensively analyzed.Fourthly,the vertical navigation performance of lift AUV was calculated by the CFD simulation method based on overset mesh and numerical calculation,and its vertical navigation performance was analyzed.Finally,based on the research in this paper,it is concluded that lift AUV is capable of generating lift on motion to provide high load capacity and strong adaptability to environment.The structure does not have the static stability of the vertical plane and the horizontal plane,but it has the vertical plane dynamic stability and the horizontal plane dynamic stability under all counterweights.Lift AUV has good vertical plane mobility,large steady turning radius in horizontal plane,excellent performance in response to propeller differential,and good maneuverability for horizontal directional control and obstacle avoidance scenarios.According to the simulation results,the influence of several typical factors on its diving performance and the parameter combination of steady-state cruise are obtained.This study can provide data support for field test and also can be used as the decision basis for the design of control algorithm.