The Design Of Ship Motion Simulation Platform For Ship Low-speed Moving

With the continuous development of the world economy, the transportation between countries is getting more and more busy, therefore ocean transportation is an absolutely necessary transport method because its huge loadage. Meanwhile, with the national industrial development, the demand for energy increases continually. Energy extraction on the land is near to exhausted due to human's exploration. Therefore, energy exploration should focus on the offshore in future, which also requires technology about marine energy extraction to be improved. It is needed to provide a control method to ensure that the operating system of a ocean vehicle and dynamic positioning systems of drilling platforms are high control precision while the sea state is not good and unpredictable. The movement of ships in the sea is a very complex process, which will be more nonlinear as the reduction of ship speed, and the disturbance from wind and wave will also become more obvious. Therefore, low-speed maneuvering and controlling of a ship is an important and difficult things in the navigation. Following the development of science and technology, various ship maneuvering control algorithms have appeared, most of them need to be verified about the availability, reliability and accuracy on a simulation test platform. Therefore, a ship motion control simulation platform has been designed to solve this problem. It is mainly used to simulate the low-speed ship's movement in the sea.The hardware of ship motion control simulation platform consists of the following components:(1) Four tracks and a rotating platform which overlying each other and driven by five stepper motors. Among them, the bottom two tracks are wave simulation layer, and the upper two tracks, together with the rotating platform, compose of the ship simulation layer; (2) Two PC 104 IPCs. They are used to simulate the wave motion and the ship motion respectively, and they are the core control sections of the simulation platform; (3) Laser range finders and an inertial navigator. They are used to detect the current position of each track and direction of the rotation platform; (4) Other:limit switches, control box, etc. In this thesis, the ship simulation layer is designed to simulate the movement of low-speed ship. Firstly a lot of references and information have been read about how to build a mathematical model of a ship when it moving with low-speed Secondly, a ship mathematical model has been built with Matlab and the simulation data take from "Yu Kun" ship which belongs to Dalian Maritime University. The simulation has been done in computer to verify the correctness of the model. Finally, in the case of mathematical models available, c++ program has been designed and written into the ship simulation controller (IPC) of the platform. Hardware debug has been done to ensure that can move correctly according to the mathematical model described. When the all work finished, the simulation platform can be used to design and verify the control algorithms about the berthing/unberthing of ships and dynamical positioning of offshore drilling platforms.