Research Of Dynamic Modeling Based On Spacial Captive Motion Simulation And Maneuverability Optimization Of Autonomous Underwater Vehicle

As complex systems,integrated with artificial intelligence,information integration,underwater target detection,intelligent control and system integration,Autonomous Underwater Vehicles(AUVs)perform an irreplaceable role in many civil and military fields.Good maneuverability is an important guarantee for AUVs to accomplish various complex underwater tasks and return back.The study of maneuverability is also an essential part of performance investigation of AUVs.Establishing dynamic model correctly and mastering motion laws exactly are vital prerequisite to develop other performance analysis and improve design work during the study of underwater motion characteristics.Comprehensive optimization of AUVs considering mission objects will improve navigational efficiency and environmental adaptability.Dynamic modeling method and optimization of maneuverability are conducted in this paper to improve hydrodynamic performance.Specific researches are included as follows:Basic CFD knowledge is firstly introduced,and SUBOFF case is studied to figure out independence of grid for subsequent simulation,then an optimal meshing and simulating strategy are finally determined.Based on the fully investigated CFD approach,PMM model tests for SUBOFF and HEU model are simulated to identify hydrodynamic coefficients.Reasonable relative errors of most coefficients comparing with experimental data prove the reliability of the adopted CFD approach.To increase efficiency when establishing dynamic model,a time-efficient approach for the estimation of hydrodynamic coefficients using computational fluid dynamics(CFD)method is proposed in this paper.Instead of a repetitive and time-consuming process,the proposed spatial captive motion could provide all necessary information for determination of all required coefficients in only one simulation.The results of simulating for two different submarines proved that this method is correct and accurate.There are numerous coefficients in original dynamic model,in addition,parts of them have little effect on hull performance.Therefore,the dynamic model is simplified according to significance test results,while prediction accuracy ensured.According to motion properties of AUVs,a comprehensive evaluation method is proposed to evaluate the maneuverability.The method considers maneuverability criterions of all motions which can be divided into three aspects: vertical movement,horizontal movement and endurance.Modified AHP-FCE is introduced to overcome the defects of traditional evaluation method.It performs a more scientific and objective evaluation system.The method can avoid the limitation of maneuverability evaluation when using single or only a few criterions.The sensitivity analysis between maneuverability criteria and hull geometry parameters is conducted.Firstly,three classical approximate models are studied in detail and a Kriging model with the strongest fitting ability is established.Secondly,based on local and global sensitivity method,the sensitivity of maneuverability indexes to design variables is researched.Finally,effects of parameters on maneuverability are quantified to analyse improvement or deterioration degree of each maneuverability when design parameters change within a certain range.A comprehensive platform is established on the basis of robust design optimization method.Optimization of AUV maneuverability focuses on the detailed optimization of the established design plan,and the initial plan determination depends more on the designer's experience.In traditional robust methods,the deviation caused by approximate model will inevitably result in uncertainty in optimal solution.To address the issues,both parametric and metamodel uncertainty are considered and quantified based on Monte Carlo sampling.Combined with 6 Sigma quality management method and maneuverability evaluation system,a more reliable AUV operation comprehensive optimization platform is constructed.The proposed method is appropriate to identify optimal hull to meet requirements of different tasks with only parameters changing while the area of rudder fixed.Finally,both rudder and hull parameters are considered to optimize geometrical arrangement of AUVs comprehensively.