The Structure Design Of Shallow Water Floating Monitoring Platform And The Research Of Its Static Hydraulic Characteristics

The underwater video monitoring system(UVMS)of shallow water testing field,which is used for observing and recording of the underwater equipment testing process,is an important part of shallow water testing field monitoring system.The underwater video monitoring system has been developed into various forms after many years such as stationary underwater monitoring equipment,floating underwater monitoring equipment,mobile underwater monitoring equipment,and others according to different camera carriers.This paper firstly proposes a new kind of floating underwater monitoring equipment on the basis of usage requirements of shallow water testing field and finishes the building of UVMS which is based on this floating platform and then implements relevant research on static hydraulic characteristics of the floating platform.The UVMS contains two stationary cameras and two floating cameras,which ensured the whole testing equipment to be monitored by controlling the movement of the floating platform.The whole system which is employing functions of large screen display,video storage,playback,and video alarm includes underwater lighting system with LED matrix as underwater lights,control system and data acquisition system,and video monitoring system which is built by VC++ and separated from control system to guarantee its sensitivity and uses PAL video formats and MPEG/AVI compression method to save the surveillance video.The design of the floating platform of UVMS is based on the sea buoy and the Spar platform,and includes the structure framework,drum system and selection of mooring line system.As a result,the strength of the floating platform structure can meet the design requirements of the underwater monitoring with the help of ANSYS analysis and calculation.After finishing the design of structure of the floating platform,the center of gravity and buoyancy coordinates of this floating platform has been estimated and the area moment of the floating body section has been calculated thus to determine the high stability,restoring moment,stability coefficient and static and dynamic stability curve,and stability criterion under different angles.The approximate calculation of the natural period of both rolling and pitching of floating platform has been carried out and an analysis of the changing curve of static hydraulic characteristics under different structural parameters in term of the distanceof the weight,weight,diameter of floating body,and analysis of the influence of natural period of rolling and pitching and heaving motion on static hydraulic characteristics has been made.It has been found that on the one hand,diameter of floating body exerted the greatest influence on static hydraulic characteristics and weight followed suit,on the other hand,the natural period of rolling,pitching and heaving of floating platform could be changed by the means of changing structure parameter.It turns out from the pool experiments on a floating monitoring platform that floating monitoring platform could meet the demand of underwater video monitoring function,and shows a great stability.The free decay cycle of roll,pitch and heave has been measured from the free attenuation curve,and the influence of structural parameters on static hydraulic characteristics could still work on free attenuation movement.In the end,the damping coefficient has been got from the extinction curve which is calculated from the free attenuation curve of the roll and pitch.