Determination Of Navigation State And Longitudinal Seakeeping Optimization System Of Unmanned Surface Vehicle

With the development of ocean resources in recent years,unmanned surface vehicle(USV)has been widely studied and applied because of its excellent motion characteristics.In view of the wide market prospect of unmanned surface vehicle(USV),scholars at home and abroad have invested a lot of research on its motion characteristics,excellent design of hull form and hydrodynamic optimization,etc..The surface unmanned craft is a special operating planing ship,which is different from the traditional displacement ship.With the increasing of the speed of the craft,its motion state will change from the conventional displacement state to the planing state,most of the stern part of the boat will be out of the water,resulting in an imbalance between the gravity of the boat and the buoyancy generated by the drain volume.In fact,it is supported by the flowing water lift generated by part of the hull in contact with the water.Therefore,the Longitudinal Angle should be taken into account when studying the hydrodynamic forces of unmanned craft.According to the characteristics of the unmanned craft,firstly,using the hydrodynamic analysis software(STAR-CCM +)and based on the six-degree-of-freedom dynamic grid technology,the gliding motion of the unmanned craft is simulated,and the Longitudinal Angle of the unmanned craft at different speeds is obtained.Then,this paper uses Matlab language to write SIT method to predict the static water glide attitude.Compared with the former method,STAR-CCM + is feasible to calculate the Longitudinal hydrodynamic force.Due to its advantages of rapidity and automation,surface unmanned craft(usvs)often undertake navigation tasks under various bad working conditions.In the course of carrying out the task,especially if the speed is too low or too high,the position of the center of gravity and so on,the phenomenon of low-speed bow inclination and the "Dolphin Motion" of Longitudinal motion instability may occur.In this paper,a new method for identifying the ship states is presented,which is based on the classification of the Support vector machine,which is used to generate the "Dolphin motion" or drain bow tilt’s boundary between the Longitudinal stability gliding and the longitudinal instability of an unmanned surface vehicle.The motion prediction and optimization can be realized.Finally,according to the bad working characteristics of the unmanned craft,the unmanned surface vehicle(usvs)designed by Dalian University of Technology is selected as the mothership type.Parametric modeling is carried out in UG.NX software,and CAD/CFD software co-drive is realized through script program and software interface,which is connected with STAR-CCM+.An integrated hydrodynamic optimization system based on the multidisciplinary optimization platform ISIGHT is designed to optimize usual longitudinal seakeeping index of an unmanned underwater vehicle(usvs),the method solves the inefficiency of the traditional hydrodynamic optimization method of ship form greatly,so as to avoid the phenomenon of longitudinal instability such as Dolphin and improve the navigation safety.