Research On Virtual Testing System Of Ship Navigation Performance

Virtual testing is defined as a technology to measure the function and performance of a numerical or actual model in virtual conditions, based on relevant experimental specifications and regulations. Virtual testing is the outcome of developing digital shipbuilding. During last decade, it has become one of trends and hot topics in the field of experiment and validation.Virtual testing is an integrative technology involved in virtual prototype, simulation model, sensor and virtual reality, and is the extension and evolution of simulation testing. It could be used not only to identify the latent problem or fault of a ship before building or operation, but also to validate the performance of a ship on arbitrary state especially rough sea, and then to ensure the reliability and safety. Furthermore, the virtual reality technology enable operator to be involved in virtual testing system with higher interactivity, immersion and imagination and then keep the ship in control at heavy sea or intricate harbor. In conclusion, virtual testing is very important for enhancing capability, optimizing process, economizing cost.The application objects of virtual testing technology in shipbuilding field have been identified based on the investigation and comprehension of virtual testing and its application in different industries. The conception, frame and process for constructing a virtual testing system of ship navigation performances were put forward for the first time. The system ground on a simulator has been established basically, and verified by the sea trial data of a ship. The contributions from this dissertation may be summarized as follows,(1) For the virtual testing system of ship navigation performances, besides interactivity, immersion and imagination, the veracity of simulated model is crucial. The theoretical, experimental and analytical methods of ship speed, seakeeping and maneuvering performances were applied synthetically, to set up a time domain simulated model for a ship sailing on the sea with wind, wave and current. The numerical and experimental results, the coupling and simplifying schemes, the scale effect extrapolation were utilized to develop the simulated model. The precision and instantaneity were checked by numerical simulations, and showed satisfactory capabilities.(2) The system platform is constituted of ship motion control desk, image workstations, projectors, arc screen, the bus-mastering computer, the ship motion control computer and hubs. The system was designed logically to make the signals to be integrated, transmitted, interchanged, stored and displayed efficiently, reliably and stably. The engine telegraph and steering wheel for conventional single screw ship have been equipped on the ship motion control desk, and the interfaces for twin screws, twin rudders and transverse thrusters were preset for updating easily. The vision monitoring panel for ship navigation information, including speed, course, track, main engine revolution, latitude/longitude, wind speed/ direction, current speed/direction, etc., was developed.(3) With dynamic link library, the ship motion simulation model was embedded in control software package on the ship motion control desk. The real-time communication between control desk and simulation model was solved through serial interface, to simulate the man-machine interaction during navigation more realistically. Based on Creator and Vega Prime software systems, the 3D digital models of ship, wave, and water area were formed and the real-time demonstration of ship maneuvering in seas has been completed with higher reality. The codes for environment setting, data acquisition, display and processing have been developed on the Visual Studio platform. The system integration is under the frame of Windows Sockets communication protocol. The opening character and compatibility of the system have been considered to make the system to be modified, updated and maintained conveniently.The construction of the virtual testing system of ship navigation performances is a huge and complex systems engineering. The virtual testing technology was applied in full-scale ship navigation performance testing for the first time. Some innovations on system conformation and simulation modeling have been created primarily.