Study And Design Of Simulation Platform For Ship Motion

The mathematical model for ship motion, which is usually very complex, is crucial for the security and efficiency of ship motion. Due to this reason, many researchers have invested great efforts to investigate the mathematical model for ship motion. With the aid of computer simulation technology, this thesis develops a simulation platform for ship motion, which not only helps the researchers understand the motion characteristics, but also provides an interface for testing the performance of the controllers. The developed platform thus can shorten the develop period of ship motion systems.Being regarded as a digital pool for the ship, the platform in this thesis can provide an efficient and intuitive experiment environment for ship designing, navigation training and performance testing of the controller. Based on LabVIEW, the platform is designed and implemented under the guidance of systems engineering methodology. The simulation software designed contains three modules:model module, display module and control module. The work in this thesis includes four parts, as follows.Firstly we lay the foundation of the platform to be developed by establishing a mathematical model for ship motion. Specifically, we construct a mathematical model with3degrees of freedom for plane motion by integrating the kinematical equation, dynamical equation, hydrodynamic force and environmental perturbations together. With this model, the researchers can obtain the desired outputs by only inputting the ship size and environment parameters.Secondly, we focus on designing the display module in order to make the ship’s global poise more visualizable. Conventionally the simulation results are displayed in pure waveforms, which fail to provide intuitive information on the ship’s global poise. To overcome such shortcoming, we establish a display module capable of realizing the visualization of the whole simulation process with distinct images, with the assistance of3ds Max and3D Picture Control Toolkit in LabVIEW.The third part is devoted to designing an interface of the control module. Being the key module of automation and intelligentization, Ship motion control is crucial to ensure the safety, economicality and comfort during navigation. This interface provides both a simulation environment for testing the controller’s performance, and a programming environment in which the researchers can implement their control algorithms, whose effect and performance can be visualized through the display module mentioned above.The last part studies she topic of motion control. At present, most ship systems employ PID to regulate the motion of the ship. It is well known that the performance of PID control depends heavily on the parameters. However, due to the complexity of ship motion, pure PID control is not only time-consuming, but also incapable of satisfying high performance. Motivated by the drawback of PID control, we try to combine the fuzzy logic control and PID control along with experts’experiences. Based on incremental PID, we develop an adaptive fuzzy controller being able to fuzzily self-tune the PID parameters. Simulation results show that adaptive fuzzy controller can remarkably improve the control precision and the ability of anti-interference and adaptivity.