Research On Intelligent Control Of Ship Roll Motion And Virtual Reality Simulation

Excessive ship-swing may occasionally result in the following consequences:damaging hull structure and main components, decreasing ship's speed and stability, leading to crew seasick, reducing crew's efficiency and even leading to ship-sink. In various ship swing motion, roll motion is the most serious and destructive. Therefore, to find out effective ways to reduce ship roll motion is a key and significant issue in the field of ship motion control, fin stabilizer as the most widely used roll reducing device is deeply researched.Taking ship fin stabilizer system as research object, intelligent control algorithm based on wavelet neural network and visual simulations of ship fin stabilizer system are investigated in the thesis. The aim is to further improve the stabilizing effect in different sea conditions, improve ship's seakeeping and seaworthiness and provide a visual simulation environment for ship fin stabilizer system.Firstly, sea wave model and wave slope angle model based on wave spectrum theory and ship roll motion model are established. On the base of a great deal of reference literatures, intelligent PID control algorithm of ship roll motion based on dyadic wavelet neural network has been proposed. Since the advantages of unique multi-scale resolution characteristic of wavelet analysis and inherent self-learning adaptive ability of artificial neural networks, when wavelet neural network is combined with conventional PID control algorithm, a kind of intelligent PID controller with self-learning parameters has been set up and better stabilizing effect is obtained in different sea conditions and ship's course. Simulation results show that intelligent PID controller based on wavelet neural network can overcome the poor adaptability of conventional PID controller, restrain disturbance effectively and enhance system's stability. Then virtual reality simulations of ship fin stabilizer system and virtual dashboard in accordance with a new type of ship have been designed. And the triune simulation effect which integrating wave model, ship model and intelligent control algorithm also has been realized. By manipulating virtual dashboard to control various states such as starting or stopping and reducing roll or generating roll of fin stabilizer system and observe output curve of controller, stabilizing effect can be observed by visual reality simulation environment. Thus visual simulation of ship fin stabilizer system is established to instead of simple curve simulation, so the work situation of ship fin stabilizer system can be reflected dynamically and realistically.