Study On Ship Motion Simulation Platform Based On The Fuzzy-PID Control

Ship occurs swaying motion during at sea, due to the influences of wind, current and wave. Swaying motion of ships can affect ship’s stability, threaten crew’s safety, cause damage of the goods, weaken the accuracy of weapons on warship, etc. Therefore, we should put more effort in study of vessel’s swaying motion control, especially the roll and pitch, which is based on the study of regularity of ship motion. Though tests on the real ship can produce a good effect, it spends more manpower and material resources. The simulation platform of ship motion can make up for this disadvantage.Based on the needs of scientific research, the lab built an integrated hydraulic propulsion of ship system, which contains a ship motion platform. The platform is designed to simulate ship roll and pitch motion under certain sea states. But so far, it can just simulate the curve of sine or several sinusoids superposition. In addition, the former control mode of this system is PID controlling, which can be ameliorated. Thus, this paper focuses on ship roll and improving the platform system from two aspects-simulation model and control mode.Firstly, this paper analyzed the basic theory of waves, wave amplitude model and slope of wave surface. Then Conolly ship roll motion model was established through the analysis of force during ship swaying. And by using the MATLAB software, this model was simulated based on a vessel given parameters. The simulation results would serve as the set values.After the brief summary of platform’s mechanical structure, hydraulic system and former control system, this paper designed the fuzzy-PID controller, which laid the foundation for later programming work.Then by using of the STEP7 programming software, this paper rewrote the programs according to modular programming thought to achieve the fuzzy-PID control mode and enable the platform to simulate ship roll motion under different sea states.Finally, this paper did a large number of simulation tests and revised the control program continually. In the end, the platform implemented the fuzzy-PID control mode and simulation of ship roll motion under different sea states. Besides, through the comparison of the test results produced by different control modes, we can find that the overshoots and error values under the control of fuzzy-PID controller are both smaller, which has a certain practical significance. And the more complex the sea state is, the more obvious the improvements are.