| Because of the impact of some factors such as ocean wave, ocean breeze and ocean current, ships inevitably come into being various swaying motion when they navigate the sea. Rolling is the most notable and its impact on ship is the greatest. Fin stabilizer is the most widely used anti-rolling devices at present. The electro-hydraulic servo technology is commonly used in servo system of the fin stabilizer. In recent years, the electro-hydraulic proportional technology arouses the attention gradually by its obvious advantages such as reliability, energy saving, strong ability of anti-pollution, easy maintenance, low cost and so on. The ships control engineering laboratory replaced the traditional electro-hydraulic servo valves by the electro-hydraulic proportional valves in servo system of a certain retractable fin stabilizer. The fin stabilizer electro-hydraulic proportional control system was designed. The system was thoroughly researched in this subject.The composition and operating principle of the fin stabilizer system and the fin stabilizer electro-hydraulic proportional control system were analyzed at first. Then combining with the hydraulic control principle, the mathematical model of the fin stabilizer electro-hydraulic proportional control system was inferred and established. The system's parameters were calculated and variables were replaced with them. The stability analysis and the time domain simulation analysis to the system were carried on by using the MATLAB. The impact of proportional valve's dead zone characteristic on the system performance was discussed. The traditional PID control method was used to correct the system after the dead zone was compensated with a constant. Following, in view of the time-varying and asymmetrical characteristic of proportional valve's dead zone, dead zone fuzzy dynamic compensation method was applied to the system (that is, on the basis of the constant compensation and traditional PID correction in the system, a dynamic compensation value which produced by a fuzzy controller was added to the control signal) and the simulation research to the compensation effect was carried on. Finally, a digital PWM proportional amplifier was designed. This amplifier regarded the Single Chip Microcomputer AT89S52 as the kernel, produced the PWM signal used for controlling the proportional valve by the software system cooperating with hardware circuit. The PWM signal was amplified then drove electro-magnet of the proportional valve to move.The result of simulation proved that the system had certain stability, the dead zone fuzzy dynamic compensation method was more adaptive than the traditional PID control method which cooperated with constant compensation, and the performance of the system was well improved. The research on this subject laid the foundation for developing better fin stabilizer electro-hydraulic proportional control system. Moreover, the digital proportional amplifier designed in this paper had greater flexibility and reliability than the traditional analog proportional amplifier. It had a high value for engineering applications. |
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