The Research For Lift-feedback Fin Stabilizer System And The Alteration Of Its Servo System

Fin stabilizer, which has been used more than seventy years, is the main equipment to stable the ship. But it is not so excellent that there are many problems to solve. Most of the fin stabilizers we use now are angle-feedback system, whose control torque is gotten by the calculation of fin angle. Because the relationship between the lift on the fin and the fin angle is gotten by the static hydrodynamic experiment, which has great error, especially dynamic hydrodynamic experiment, the control torque gotten by the experiment can not counteract the wave torque well and the stabilization result is not perfect. If we could obtain the lift directly all the problems in angle transition will be avoided. That's the principle of lift fin stabilizer.Lift fin stabilizer is a new kind of perfect stabilizer, whose control theory is improved on the basis of classical one. The research on lift fin stabilizer is so significant to improve stable effect and make the stabilizer work better.Almost all the servo systems of fin stabilizers are made of analog circuit, whose defects are clear. Its control precision, reliability and adaptability are not good enough. As the electronic technology develops so fast, the fin stabilizer also needs to be improved. So the alteration and improvement of servo system is necessary.The improvement of servo system should base on the merits of the old one, and cover the shortage. That is to say we need to better its precision, reliability and adaptability. Because of all above we select the PLC as the substitution.The work concerned are listed as follows:1. Combining the fin stabilizers of both here and abroad, comparing with angle feedback fin stabilizer, this thesis does research on the compose and structure of lift fin stabilizer. Finally an engineering design is achieved.2. Do much research on the characteristic and theory of PLC, and study its the application in fin stabilizer system. The necessity of application of PLC in fin stabilizer is also given.3. Replace the old servo system with the FPO programmable controller of Matsushita Electric Works. Improve the system on the basis of its primaryfunctions. The performance of the system improved is analyzed.4. Give the design of the substitution of the whole fin stabilizer control system by PLC, and finish all the preparatory works.