The Modeling And Semi-physical Simulation Of Two-dimensional Wave

The ship movement is closely related with waves. In the design and research of the ship control system, the influence of the waves must be considered. Therefore, we need to establish a high precision real-time wave model for simulation. At present, the domestic and international research literatures show that the researches of the waves are almost statistic and simulation experiments which are unconvincing in practice application. Therefore, it is necessary to establish a high precision real-time wave simulation model. To the end, our laboratory develop a semi-physical ship position control platform, which includes ship sway, vertical swing, yawing, and establish real-time simulation model of two-dimensional wave.In the hardware design of the ship position control platform, the hardware design of the mechanical structure of the platform, drive and data collection are mainly included in this experiment. The platform consists of four tracks driven by stepper motor group. The upper two tracks and the lower two tracks floors represent wave model and ship model respectively, and they are used for simulating waves and ship movement in the two-freedom of plane. The control commands of wave and ship are generated by two independent PC machines, including direction, enable and pulse signals. The three signals are applied to each of the stepper motor drivers module, so as to realize the position control of the ship.The parameter and mathematical model of the wave is mainly introduced in this paper. In order to obtain the response of the ship on the wave, we adopted two method——Response Amplitude Operator method(RAO) and Torque method, and analyzed the advantage and disadvantage of these two methods by Matlab simulation. According to the simulation process and result, we discrete the displacement and velocity response function of Torque method, and establish the wave simulation model according to the hydrodynamic coefficients of the "YU KUN" ship. At last, we apply this method to the semi-physical simulation platform by open-loop and close-loop control. The result demonstrates that the later is preferred.In the semi-physical simulation, we can change the speed and direction of the wave tracks by changing the frequency and direction signals. So the semi-physical platform can simulate waves in different conditions which have high real-time and also can meet the needs of the simulation accuracy. It can be used to test various algorithms of the third-party ship motion controller’s ability to control the external wind and wave.